JP2002525819A - Wire insulation - Google Patents

Abstract

  (57) [Summary] An electric wire or cable having an insulator, wherein the insulator is (i) at least a first layer of a polyolefin-based composition, at least 20% by weight of the polymer portion of the composition, preferably at least 40% by weight. %, More preferably at least 60% by weight, or particularly preferably at least 80% by weight, of a carbonyl-containing polymer (homopolymer or copolymer or terpolymer), wherein at least one constituent monomer of said polymer is a carboxylic acid ester, preferably Is an acrylate or acetate, especially an alkyl acrylate (preferably, methyl acrylate, ethyl acrylate, propyl acrylate, or butyl acrylate), where a copolymer or terpolymer is used when the copolymer or terpolymer is used. Preferably, at least 5%, preferably at least 9%, more preferably at least 15% by weight of the polymer is comprised, and the remainder of the copolymer or terpolymer is preferably derived from olefin monomers, preferably ethylene. At least a first layer of a polyolefin-based formulation; and (ii) at least a second layer of a formulation of another material in contact with the first layer, wherein at least 10% by weight of the second layer. %, More preferably at least 50% by weight, particularly preferably at least 90% by weight, in particular 100% by weight, of polyvinylidene fluoride (PVDF), particularly preferably VDF and copolymers based on partially or fully fluorinated comonomers, most preferably VDF and Containing a copolymer of hexafluoropropylene (HFP), etc. Having at least a second layer of a formulation of the material; preventing delamination of the two layers during an acetone soak test at 23 ° C. for 1 hour, or delamination between the layers by the method of ASTM B1876-95 It is sufficient to increase the bond strength to at least 5N, preferably at least 50%, more preferably at least 100%, especially at least 500% or 1000%, as compared to the bond strength between the non-crosslinked layers. As such, the layers (i) and (ii) have been subjected to a crosslinking reaction, preferably in contact with one another, by radiation, more preferably by ionizing radiation; wires or cables.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD The present invention relates to an electric wire or cable (hereinafter referred to as “electric wire”) in which a strong bond is achieved at an interface between a layer of a polyolefin-based material and a layer of a polyvinylidene fluoride-based material. Related to insulators. The present invention is particularly useful for multilayer insulation of electrical wires, allowing for high performance bonding between such layers of material, while maintaining the standard for other types of articles such as moldings or packaging films. Maintain an acceptable balance in the complex relationship of different specific other wire performance conditions.

BACKGROUND OF THE INVENTION The following abbreviations are used for: PJ = primary jacket; prorad = crosslinking accelerator; TMPTM = trimethylolpropane trimethacrylate; ASTM = American Society for Testing and Mat
erials; PVDF = polyvinylidene fluoride; VDF = vinylidene fluoride; HFP = hexafluoropropylene; HDPE = high density polyethylene;
EA = ethylene / ethyl acrylate; EMA = ethylene / methyl acrylate;
EVA = ethylene / vinyl acetate; EA = ethyl acrylate; MA = methyl acrylate; VA = vinyl acetate.

[0003] Polyolefin inner layer (core) and polyvinylidene fluoride (PVDF)
Double-layer wire insulation having an outer layer (primary jacket or PJ) has been commercially available for 30 years and is available from several manufacturers. All these products have very little adhesion between the inner layer (polyolefin) and the outer layer (PVDF) and can therefore be easily separated. Several inconveniences arising from this lack of bonding that limited the strength of the structure had to be accepted. For example, when exposed to mechanical stress, certain liquids, contact with sharps, or impact, the outer insulating layer may crack and peel from the inner layer. The abrasion resistance and bending fatigue resistance of the insulator, and the resistance to wrinkling when bent (which can make it difficult to seal the wires or insert the wires into grommets or connectors) are also two-fold. Disadvantageously affected by easily separating insulating layers. It was believed that it was not possible to combine layers of two such different types of materials, such as polyolefins and PVDF, in electrical wires at commercially acceptable costs and manufacturing efficiencies. Further, available coupling methods may have unacceptable effects on the performance characteristics of the wire. A conventional method of bonding polyolefin and PVDF is to use a tie layer material (eg, US Pat.
89028), however, these are often costly and can impair other properties, such as heat aging resistance, when used in electrical wires, and complicate the manufacturing process by forming extra layers. They also have limited effectiveness in terms of the bond strength obtained.

DISCLOSURE OF THE INVENTION According to the present invention, different insulating materials of a polyolefin-based core and a polyvinyldenfluoride-based PJ can be bonded to a wire or cable at a significant adhesion level; It has been found that this bond is obtained without unacceptably affecting crack growth resistance, cost, or the overall balance of wire performance; Was.

[0005] In the wire or cable insulation of the present invention, surprisingly, the selected formulation of the polyolefin-based layer in contact with the polyvinylidene fluoride-based layer and the crosslinking preferably effected by the application of radiation, especially ionizing radiation. Significant binding strength is obtained by combination with the reaction.

Accordingly, the present invention relates to (i) at least a first layer of a polyolefin-based material, wherein at least 20%, preferably at least 40%, more preferably at least 60%, or at least 60% by weight of said material. 80% by weight (based on the total material composition) of a carbonyl-containing polymer (homopolymer or copolymer or terpolymer) having a non-aromatic backbone, wherein at least one constituent monomer of the polymer is a carboxylic acid ester, Preferably, it is an acrylate or acetate, especially an alkyl acrylate (preferably methyl acrylate, ethyl acrylate, propyl acrylate or butyl acrylate), and when a copolymer or terpolymer is used, the monomer is a copolymer or terpolymer. At least 5 wt%, preferably at least 9 wt%, more preferably at least 15
At least a first layer of a polyolefin-based material, preferably from an olefin monomer, preferably ethylene, comprising the remaining weight of the copolymer or terpolymer; and (ii) ) At least 10%, more preferably at least 50%, or at least 90% by weight of polyvinylidene fluoride (PVDF), particularly preferably VDF and a copolymer based on partially or fully fluorinated comonomers, most preferably VDF and hexafluoro At least a second layer of a material containing a copolymer of propylene (HFP); increasing the peel bond strength between said layers to at least 5N, preferably at least as compared to the bond strength between non-crosslinked layers. 50%, more preferably at least 100%,
The layers (i) and (ii) are brought into contact with one another, preferably by radiation, more preferably by ionizing radiation, such that at least 500% or 1000% is sufficient to increase the bond strength. An electric wire having an insulator.

In accordance with another aspect of the present invention, (i) at least a first layer of a polyolefin-based formulation, wherein the polymer portion of the formulation is at least 20% by weight, preferably at least 40% by weight, more Preferably at least 60% by weight, or particularly preferably at least 80% by weight
Consists of a carbonyl-containing polymer (homopolymer or copolymer or terpolymer), wherein at least one constituent monomer of the polymer is a carboxylic acid ester, preferably an acrylate or acetate, especially an alkyl acrylate (
Preferably, methyl acrylate, ethyl acrylate, propyl acrylate, or butyl acrylate), wherein when a copolymer or terpolymer is used, the monomer is at least 5% by weight of the co or terpolymer, preferably at least 9% by weight, more At least a first layer of a polyolefin-based formulation, preferably comprising at least 15% by weight, wherein the rest or the majority of the remainder of the copolymer or terpolymer is preferably derived from olefin monomers, preferably ethylene; Contacting the first layer; (ii) at least a second layer of a blend of other materials, wherein at least 10
%, More preferably at least 50% by weight, particularly preferably at least 90% by weight.
% By weight, especially 100% by weight, of polyvinylidene fluoride (PVDF), particularly preferably other copolymers containing VDF and copolymers based on partially or fully fluorinated comonomers, most preferably copolymers of VDF and hexafluoropropylene (HFP) Preventing delamination of said two layers during an acetone soak test as described below, or said layer by the method of ASTM B1876-95 described below. Peel strength of at least 5N
And preferably at least 50% compared to the bond strength between the non-crosslinked layers,
More preferably at least 100%, especially at least 500% or 1000%
The layers (i) and (ii) are sufficient to increase the bond strength at
Providing a wire having a cross-linking reaction, preferably in contact with one another, by radiation, more preferably by ionizing radiation; an insulator.

Preferably, the layers are brought into contact with each other at a temperature above the melting point or softening point of the polymer material in at least one of the two layers, thus maximizing the tightness of their interfacial contact, so that: Can promote the formation of adhesion-promoting interfacial cross-linking in the cross-linking reaction.

[0009] The polyolefin-based layer (i) is used as an additive such as a known antioxidant, coloring agent, filler, flame retardant, etc., in addition to the polymer portion of the blend in which the conditions for the polyolefin are defined above. The required mechanical, thermal, electrical properties and the like can be imparted to the polymer, including those required.

The polyvinylidene fluoride-based layer (ii) also contains other known additives,
The required properties can be imparted in addition to the binding property.

The advantages of obtaining a strong bond according to the invention include the following: the resistance of the surface layer and of the insulator as a whole when it is bonded to the substrate; -Increased abrasion resistance, especially when one of the layers is damaged / penetrated;-improved bulging resistance of the two layers when heat is applied;-for example, mechanical stress or chemicals Improved delamination / crease / wrinkle resistance between the two layers, for example by exposure to solvents; reduced wire wrinkling and said properties while maintaining adequate cut and notch growth resistance (This was unexpected because a firmly adhered layer is generally considered to transmit cuts or notches in the outer layer to the inner layer quite easily).

[0012] The bond strength described herein can be measured as the peel strength between a bond strip of two materials of interest. A common method that can be used for such a test is ASTM 1876-95. According to this standard, a significant bond is a bond with a peel force of more than 5N, and a strong bond is a bond with a peel force of more than 10N. The conventional method of measuring the bond strength between the layers (i) and (ii) when processed in an electric wire is to conduct a wire sample having a total length of 60 mm at a depth corresponding to 70% of the length of the wire sample. Acetone at 23 (+/- 3) ° C (eg, Fisher Scientific UK,
It is a method of putting in AR guaranteed brand acetone) for 1 hour. Wires with very little bonding of the insulation layer have a P along the wire axis that is independent of the extension of the polyolefin core.
Indicating the expansion of the VDF PJ and / or the occurrence of wrinkles in the PJ,
Peeled from the core in some places. When that happens, the stretching of the PJ is
Following the test, a PJ "tube" is provided that extends 1 mm or more beyond the cut end of the sample core. Wires with a significantly bonded insulation layer do not separate, and along the wire axis, beyond the conductor cut, both the core and the PJ stretch and / or without delamination. Both produce wrinkles. By examining the cross-section of the wrinkles under a microscope, the occurrence of such core and PJ wrinkles can be distinguished from the occurrence of PJ-only wrinkles.

[0013] The method of manufacturing the wire encompasses any method that produces intimate contact between the layers (i) and (ii). An example of such a method is a method of coating one material on a preformed layer of another two-layer or multi-layer extrudate to form an insulating layer containing one or the other of each of the two materials. It is. The olefin-based material (i) is preferably the inner layer of the electric wire, and the PVDF-based layer (ii) is preferably the outer layer. Layers made from the two materials can be co-extruded, tandem extruded, multi-pass extruded, or coated by other means. One or more layers can be formed using known wire insulation techniques, such as tube drawdown extrusion, but a known pressure extrusion is applied to the previously formed lower layer. Preferred for optimal deposition of the insulating layer and the next insulating layer.

[0014] The insulator in the wire is exposed to a cross-linking reaction which can use chemical reagents such as peroxides, which preferably form radiation, especially radicals, and thus cross-links, in the polymer. Preferably, the irradiation is effected by radiation from an ionizing source, and preferably some of the crosslinking is formed in the interface region of the two materials.
Preferably, the radiation penetrates the material at least up to the interface, but is not necessary if, for example, ionic or radical mobility allows the molecular reaction to continue at or near the interface after the radiation step. The radiation source is, for example, a radioisotope or X-ray source, or a non-ionizing radical generating source, for example an ultraviolet source, but is preferably an electron beam, more preferably more than 2 Mrad, preferably at least 5 Mr
An electron beam which gives a material a beam dose of ad, more preferably at least 10 Mrad, particularly preferably at least 15 Mrad is preferred.

It has been found that by using certain additives, the interfacial bond strength can be increased. The additive preferably includes a crosslinking accelerator (prorad) in the polyolefin-based material and / or the PVDF-based material. Known crosslinking agents, preferably those based on methacrylates / acrylates, particularly preferably those of the trimethylolpropane trimethacrylate (TMPTM) type, can be used for polyolefin materials and / or PVDF-based materials.

Experimental Results All the results shown in the table below were obtained by testing press plaques of two materials made by known general polymer handling methods. The plaque was pressed to join the faces together and the combined assembly was irradiated as specified.
Plaques, rather than wires, were used in these certification tests because the bond strength at the plaques was relatively easy to measure. The conditions of these experiments were as follows: Plaque dimensions: 150 mm x 150 mm x 0.85 mm Press temperature: 200 ° C Press time: 2 minutes preheating, 1 minute under pressure Press pressure: 20-40 tons on 300 mm x 300 mm metal plate Cooling conditions: At the above pressure, between water cooled 300 mm x 300 mm metal plates for 2 minutes.

Examples of the effect of radiation dose on the bond strength between suitable polyolefin and PVDF-based materials

[Table 1]

Examples of the effect of the percentage of comonomer in an ethylene copolymer material on the bond strength to a suitable PVDF-based material after electron beam crosslinking

[Table 2]

Examples of the effect of the percentage of copolymer in a polyolefin polymer blend on the bond strength with a suitable PVDF-based material after electron beam crosslinking

[Table 3]

[0020] PV after bonding with an appropriate polyolefin-based material after electron beam crosslinking
Example of influence of DF material type

[Table 4]

Examples of the effect of the addition of prorad in olefin materials on bond strength with appropriate PVDF-based materials after electron beam crosslinking

[Table 5]

Wire Making Examples Wires were made wherein the insulator consisted of two bonded polymer layers of the present invention as follows: The inner layer of the insulator (ie, the layer closer to the conductor) was a polyolefin-based material. , Mainly (a) an EEA copolymer containing 15% by weight of EA and (b) H
DPE comprises about 8: 2 copolymer: HDPE by weight, and other common additives including cross-linking accelerators, stabilizers, antioxidants, colorants, and processing aids comprise 24 parts by weight. It is present in small proportions at a total level of weight percent. This layer was pressure extruded onto a metal conductor. The outer layer of the insulator mainly comprises a PVDF / HFP copolymer containing 10% by weight of HFP, and in this sample, the crosslinker, and the colorants, plasticizers, stabilizers, antioxidants, and processing aids. Other known additives such as 7.
It is contained in a general proportion of 5% by weight. This outer layer was pressure extruded onto the previously formed inner layer in a separation operation. Next, the coated electric wire was passed through an electron beam,
Exposure to ad radiation dose.

In a second example, an electric wire was produced as described above, and the crosslinking accelerator in the inner layer was 4%
TMPTM, the outer layer of the insulator being PVDF / H containing 10% by weight of HFP
Consisted solely of the FP copolymer. Next, the coated electric wire was passed through an electron beam,
Received radiation dose of Mrad. This wire was subjected to an acetone immersion test, and it was confirmed that the insulating layer was significantly bonded.

In a third example, an electric wire having the same structure as the second example was manufactured by tandem pressure extrusion of the inner insulating layer and the outer insulating layer. The coated wire was then passed through an electron beam and exposed to a radiation dose of 20 Mrad. This wire was subjected to an acetone immersion test, and it was confirmed that the insulating layer was significantly bonded.

The improved performance of the wire manufactured as in the second example above is shown in comparison to currently marketed wires. In testing wire strength for harsh handling and end use environments, wires of the above construction and manufacturing method (referred to as wire A) were replaced by commercially available polyolefin / PVDF double-layer wires occupying the mainstream of the market with the same dimensions. (Referred to as electric wire B). The following results were obtained.

Example of improvement of scraping abrasion resistance Method: Apparatus = conventional type wire scraping and abrasion tester, wire dimension 0.75 mm ² (conductor cross section), blade type: flat, width 3.5 mm, wire Holds vertically, rounded edges with 0.05mm on both sides, applied load 1.8kg, stroke length 10cm, 55 cycles / min.

[Table 6]

[Table 7]

Examples of Improvement of Cold Impact Resistance Method: Wire dimensions 6 mm ² (conductor cross-sectional area), impact weight 800 g, drop on anvil 275 mm, area of anvil that impacts wires with dimensions of 7 mm × 2 mm Spread 3.4 mm with a 45 ° taper, ambient temperature 5 ° C. Visual inspection of insulator crack growth.

[Table 8]

Example of Improvement in Solvent Resistance Method: Wire dimensions: 0.75 mm ² , wire length: 60 mm, acetone immersion depth:
75% of the wire length, immersion time: 1 hour, temperature: 23 ° C.

[Table 9]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 15/08 103 B32B 15/08 103Z 27/32 101 27/32 101 // B29K 27:12 B29K 27: 12 33:00 33:00 105: 22 105: 22 B29L 31:34 B29L 31:34 F term (reference) 4F100 AB01C AK03A AK19B AK71A AL01A AL01B BA03 BA07 BA10A BA10C CA02 DD31 EH20 EH202 EH23 EH232 EJ05 EJ052 EJ53 EJ532A41 GB41 AA04E AA16 AA21E AB03 AD03 AD15 AG03 AH35 AP18 AR19 KA01 KB11 KB18 KB22 KB26 KJ05 KL58 KM03 KM15 KW33 KW50 5G309 RA04 RA09

Claims (20)

[Claims] 1. An electric wire or cable having an insulator, the insulator comprising: (i) at least a first layer of a polyolefin-based material,
0% by weight (based on the total material composition) of a carbonyl-containing polymer (homopolymer or copolymer or terpolymer) in which at least one constituent monomer of the polymer is a carboxylic acid ester, preferably an acrylate or acetate, especially an alkyl An acrylate (eg, methyl acrylate, ethyl acrylate, propyl acrylate, or butyl acrylate), wherein when a copolymer or terpolymer is used, the monomer comprises at least 5% by weight of the copolymer or terpolymer; At least a first layer of a polyolefin-based material, the remainder of the polymer preferably being derived from an olefin monomer, preferably ethylene; and contacting the first layer (ii) based on the total material composition At least 10% by weight of polyvinylidene fluoride (PVDF), or at least a second layer of a material containing VDF and a copolymer based on partially or fully fluorinated comonomers. the layers (i) and (ii) have been subjected to a cross-linking reaction while contacting each other so as to be sufficient to increase the peel bond strength between ii) to at least 5N; cable. 2. An electric wire or cable having an insulator, the insulator comprising: (i) at least a first layer of a polyolefin-based composition, wherein at least 20% by weight of a polymer portion of the composition; Preferably at least 40% by weight, more preferably at least 60% by weight, or particularly preferably at least 80% by weight
Consists of a carbonyl-containing polymer (homopolymer or copolymer or terpolymer), wherein at least one constituent monomer of the polymer is a carboxylic acid ester, preferably an acrylate or acetate, especially an alkyl acrylate (
Preferably methyl acrylate, ethyl acrylate, propyl acrylate, or butyl acrylate), wherein when a copolymer or terpolymer is used, the monomer is at least 5% by weight of the copolymer or terpolymer;
A polyolefin-based formulation, preferably comprising at least 9% by weight, more preferably at least 15% by weight, wherein the remainder or the majority of the remainder of the copolymer or terpolymer is preferably derived from olefin monomers, preferably ethylene. And (ii) at least a second layer of another material formulation, wherein said second layer comprises at least 10% by weight of said second layer, more preferably at least 50% by weight of said second layer. % By weight, particularly preferably at least 90% by weight, especially 100% by weight of polyvinylidene fluoride (PVD
F), or particularly preferably a copolymer based on VDF and partially or fully fluorinated comonomers, most preferably VDF and hexafluoropropylene (HFP)
At least a second layer of another material formulation containing a copolymer of the following: preventing delamination of said two layers during an acetone soak test at 23 ° C. for 1 hour, or ASTM B1876- Increasing the peel bond strength between said layers by at least 95 by at least 5N, preferably at least 50%, more preferably at least 100%, especially at least 500% or 1000%, compared to the bond strength between non-crosslinked layers The layers (i) and (ii) have been subjected to a crosslinking reaction, preferably by radiation, more preferably by ionizing radiation, in contact with each other, so as to be sufficient to increase the strength; . 3. The layers (i) and (ii) are brought into contact with each other so as to be sufficient to prevent delamination of the two layers during an acetone soak test at 23 ° C. for 1 hour. The wire or cable according to claim 1, which is preferably subjected to a crosslinking reaction by radiation, more preferably by ionizing radiation. 4. The crosslinking reaction is at least 50%, more preferably at least 100%, especially at least 500% or 1% as compared to the bond strength between the non-crosslinked layers.
The electric wire or cable according to any one of claims 1 to 3, wherein the bonding strength is increased by 000%. 5. The wire or claim according to claim 1, wherein prior to crosslinking of the layers, the layers are brought into contact with each other at a temperature above the melting or softening point of the polymer material in at least one of the layers. cable. 6. The polyvinylidene fluoride-based layer comprises a copolymer of VDF and hexafluoropropylene (HFP), wherein the copolymer comprises a majority, preferably substantially all, of the material of the layer by weight. The electric wire or cable according to any one of claims 1 to 5, which constitutes. 7. A copolymer of VDF and hexafluoropropylene (HFP), wherein the polyvinylidene fluoride-based layer has a hexafluoropropylene (HFP) content of preferably 8 to 12% by weight, particularly preferably 9 to 11% by weight. The electric wire or cable according to any one of claims 1 to 6, comprising: 8. The electric wire or cable according to claim 1, wherein the polyolefin-based layer comprises a mixture of polyethylene and the carbonyl-containing polymer. 9. The electric wire or cable according to claim 1, comprising an inner layer of the polyolefin-based material and an outer layer of the polyvinylidene fluoride-based material. 10. The wire or cable according to claim 9, wherein said outer layer is extruded under pressure into said inner layer. 11. The wire or cable according to claim 1, wherein the crosslinking reaction is carried out by radiation, preferably by ionizing radiation. 12. An electric wire or cable according to claim 1, comprising alternating layers of the material constituting said layers (i) and (ii). 13. The material of one or both of said layers (i) and (ii) contains at least one type of crosslinking accelerator, said crosslinking accelerator being added only to the material of said layer (i). The electric wire or cable according to any one of claims 1 to 12, which is preferably provided. 14. The material of one or both of the layers (i) and (ii) contains at least one crosslinking accelerator, wherein the crosslinking accelerator is a polyfunctional acrylate or methacrylate ester, preferably The electric wire or cable according to any one of claims 1 to 13, which is trimethylolpropane trimethacrylate (TMPTM). 15. The electric wire or cable according to claim 14, wherein the crosslinking accelerator is added only to the material of the layer (i). 16. The polyvinylidene-based layer (ii) is substantially transparent,
2. The method of claim 1, wherein the composition comprises substantially only PVDF or the VDF copolymer.
16. The electric wire or cable according to any one of items 15 to 15. 17. The method of claim 1, further comprising the step of providing said layers (i) and (ii) in contact with each other on a conductor, and subjecting said layers to said crosslinking reaction while contacting each other. A method for producing an electric wire or cable according to any one of the above. 18. The method of claim 17, wherein the layers are brought into contact with each other before (a) crosslinking the layers and (b) at a temperature above the melting or softening point of the polymer material in at least one of the layers. Method. 19. The layer (i) is extruded under pressure into a conductor and / or the layer (ii)
19. The method according to claim 17 or claim 18, wherein pressure is extruded into layer (i). 20. The method of claim 17, 18 or 18, wherein layers (i) and (ii) are co-extruded or tandem extruded into an electrical wire in a single pass of the conductor from the extrusion process unwind device to the extrusion process take-off device. 20. The method according to 19.