Composite material for cable shielding layer film and preparation method therefor

Abstract

Disclosed in the present invention are a composite material for a cable shielding layer film and a preparation method therefor, a resin matrix of the composite material comprising 30-60 parts by mass of metallocene linear low-density polyethylene, 3-10 parts by mass of an ethylene-octylene copolymer, 3-20 parts by mass of polytrifluorochloroethylene, 3-10 parts by mass of an ethylene trifluorochloroethylene copolymer and 15-40 parts by mass of an ethylene-tetrafluoroethylene copolymer, with the resin matrix totaling 100 parts by mass. The composite material for a cable shielding layer film provided by the present invention has a tensile strength greater than 40 MPa and is not prone to delamination from a metal tape, a yield strength greater than 10 MPa and is not easily stretched or deformed during lamination with the metal tape, and a water vapor transmission rate of less than 6, thereby exhibiting good water vapor barrier performance. In addition, the composite material is resistant to hydrolysis, exhibits good aging resistance, provides effective protection for the metal tape within the service life thereof, and further has excellent flame‑retardant properties.

Description

A composite material for cable shielding film and its preparation method Technical Field

[0001] This invention relates to the field of cable shielding membrane technology, and in particular to a composite material for cable shielding membranes and its preparation method. Background Technology

[0002] Metal composite tape is a common shielding material in the cable industry. It is formed by bonding metal tape, plastic film, and adhesive through a semi-dry bonding process, and is then applied over the insulation layer to provide electromagnetic shielding. The function of the metal composite tape is determined by the characteristics of each layer of materials. The metal layer should possess excellent shielding performance, mechanical properties, and corrosion resistance, and is mainly composed of aluminum tape, stainless steel tape, and copper tape. The plastic film layer is generally made of polyethylene or ethylene copolymer resin material, which has excellent mechanical properties, strong adhesion to the metal tape, and high heat-sealing strength. In recent years, through technological development in this field, the plastic film layer material has evolved from the original single polyethylene film and EAA film to multi-layered films combining EAA, PE, and PET.

[0003] Metal composite tape possesses excellent shielding properties, and its barrier properties prevent moisture absorption of the wire core. The film layer structure also provides good corrosion resistance, protecting the internal wire core and metal tape. However, insufficient tensile strength of the film material leads to delamination between the metal tape and the plastic film layer. Furthermore, due to its low yield strength, the film is prone to stretching and deformation during the metal tape-film lamination process. Insufficient water-blocking properties of polyethylene and the aging of the internal metal layer caused by the hydrolysis of PET fail to meet the quality requirements for cable materials with a 30-year warranty. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a composite material for cable shielding film and its preparation method, which can achieve excellent tensile strength and high yield strength of the film material, as well as good water vapor barrier properties, excellent flame retardancy, high temperature resistance and aging resistance.

[0005] To address the aforementioned technical problems, a first aspect of the present invention is to provide a composite material for cable shielding films.

[0006] Its resin matrix comprises the following components in parts by weight:

[0007] 30-60 parts by weight of metallocene linear low-density polyethylene;

[0008] 3-10 parts by weight of ethylene-octene copolymer;

[0009] 3-20 parts by weight of polychlorotrifluoroethylene;

[0010] 3-10 parts by weight of ethylene trifluorochloroethylene copolymer;

[0011] 15-40 parts by weight of ethylene tetrafluoroethylene copolymer;

[0012] The resin matrix comprises 100 parts by weight;

[0013] The composite material also includes the following components in parts by mass:

[0014] 3-8 parts by weight of compatibilizer;

[0015] 8-18 parts by weight of magnesium hydroxide;

[0016] 0.2-1 parts by weight of silicon dioxide;

[0017] 3-15 parts by weight of montmorillonite;

[0018] 0.3-1 parts by weight of silane coupling agent;

[0019] Dispersant 0.1-1 parts by weight;

[0020] Antioxidant 0.1-1 parts by weight.

[0021] In this invention, polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and ethylene-tetrafluoroethylene copolymer (ETFE) are added to a matrix of metallocene linear low-density polyethylene (MLLDPE) and ethylene-octene copolymer (POE). This significantly improves the mechanical properties of the composite material, such as tensile strength and yield strength, as well as effectively enhances its water vapor barrier properties. In particular, ETFE is mainly used to improve the mechanical properties of the composite material, PCTFE is mainly used to improve the water vapor barrier effect, and ECTFE is mainly used to enhance the compatibility between ETFE and PCTFE.

[0022] In this invention, montmorillonite is a trialkyl quaternary ammonium modified layered silicate, mainly used to further improve the water vapor barrier effect; silica mainly acts as a nucleating agent and also has a certain reinforcing effect, improving the strength of the product; the compatibilizer is preferably maleic anhydride-grafted metallocene polyethylene; the silane coupling agent is one or more of triethoxysilane coupling agent and fluorinated silane coupling agent (heptadecyltrimethoxysilane); the dispersant is EBS and / or PE wax, preferably EBS and PE wax. The mixture comprises a compound in which the mass ratio of EBS to PE wax is 1:0.5-2; the antioxidant is one or more of antioxidant 1010, antioxidant DLTP, or antioxidant 168, preferably a mixture of antioxidant 1010, antioxidant DLTP, and antioxidant 168, wherein the mass ratio of antioxidant 1010 to antioxidant DLTP is 1:0.5-2, and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:0.05-0.2.

[0023] In one specific embodiment, when the composite material is a membrane with a thickness of 25-80 μm, it possesses the following properties:

[0024] Tensile strength greater than 40 MPa;

[0025] Yield strength greater than 15 MPa;

[0026] Tensile strength at break greater than 300%;

[0027] The water vapor transmittance is less than 6 under the conditions of 38℃ temperature and 100% relative humidity.

[0028] At a temperature of 130℃, the thermal shrinkage is less than 8% after 30 minutes.

[0029] The composite material for cable shielding membrane provided by this invention has a tensile strength greater than 40 MPa, making it difficult to peel off from the metal strip; its yield strength is greater than 10 MPa, making it difficult to be stretched and deformed during the composite process with the metal strip; its water vapor permeability is less than 6, providing excellent water vapor barrier effect; it is also not easily hydrolyzed, has good aging resistance, and can play a good role in protecting the metal strip within its shelf life.

[0030] To address the aforementioned technical problems, a second aspect of the present invention is to provide a method for preparing the aforementioned composite material for cable shielding films, comprising the following steps:

[0031] S1. Magnesium hydroxide, montmorillonite, dispersant, silica, antioxidant and silane coupling agent are pre-blended to obtain modified powder;

[0032] S2. The modified powder from step S1 is granulated with metallocene linear low-density polyethylene, ethylene-octene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and compatibilizer through a twin-screw extruder to obtain primary granulated modified particles.

[0033] S3. The particles modified by the initial granulation in step S2 are granulated again by a twin-screw extruder to obtain composite material particles for cable shielding film.

[0034] In this invention, pre-blending magnesium hydroxide, montmorillonite, dispersant, silica, and silane coupling agent facilitates metering and feeding of components with lower content, effectively modifies the powder, and improves dispersion uniformity. The pre-blended modified powder is then granulated with metallocene linear low-density polyethylene, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and a compatibilizer using a twin-screw extruder. This initial granulation produces modified particles with poor dispersion uniformity. Direct film formation may result in particles or agglomerates on the film surface, affecting film performance. Therefore, secondary modification and granulation are necessary to obtain composite material particles for cable shielding films with excellent mechanical and barrier properties. This invention's preparation method is simple, easy to operate, and suitable for industrial application.

[0035] In one specific scheme, in step S1, premixing is carried out in a high-speed mixer, with a premixing speed of 100-200 rpm, a mixing time of 15-25 min, and a temperature of 25-40℃.

[0036] In step S2, the initial granulation temperature is 185-245℃;

[0037] In step S3, the temperature for regranulation is 185-245℃.

[0038] In one specific embodiment, step S2 further includes drying the initially granulated modified particles at a temperature of 70-90℃ for 2-8 hours.

[0039] In one specific formulation, the materials are added in the following proportions by weight during the preparation process:

[0040] 30-60 parts by weight of metallocene linear low-density polyethylene;

[0041] 3-10 parts by weight of ethylene-octene copolymer;

[0042] 3-20 parts by weight of polychlorotrifluoroethylene;

[0043] 3-10 parts by weight of ethylene trifluorochloroethylene copolymer;

[0044] 15-40 parts by weight of ethylene tetrafluoroethylene copolymer;

[0045] 3-8 parts by weight of compatibilizer;

[0046] 8-18 parts by weight of magnesium hydroxide;

[0047] 0.2-1 parts by weight of silicon dioxide;

[0048] 3-15 parts by weight of montmorillonite;

[0049] 0.3-1 parts by weight of silane coupling agent;

[0050] Dispersant 0.1-1 parts by weight;

[0051] Antioxidant 0.1-1 parts by weight.

[0052] The mixture comprises 100 parts by weight of metallocene linear low-density polyethylene, ethylene-octene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer and ethylene-tetrafluoroethylene copolymer.

[0053] In one specific embodiment, the compatibilizer is maleic anhydride-grafted metallocene polyethylene;

[0054] The silane coupling agent is one or more of triethoxysilane coupling agents and fluorinated silane coupling agents;

[0055] The dispersant is EBS and / or PE wax, preferably a mixture of EBS and PE wax, with a mass ratio of EBS to PE wax of 1:0.5-2.

[0056] The antioxidant is one or more of antioxidant 1010, antioxidant DLTP, or antioxidant 168, preferably a mixture of antioxidant 1010, antioxidant DLTP, and antioxidant 168, wherein the mass ratio of antioxidant 1010 to antioxidant DLTP is 1:0.5-2, and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:0.05-0.2.

[0057] The composite material for cable shielding membranes provided by this invention has good mechanical properties such as tensile strength and yield strength, making it easy to combine with metal strips. After combination, it is not easily peeled off and has good barrier properties, providing excellent protection for both the metal strip and the cable. At the same time, the composite material for cable shielding membranes provided by this invention has good flame retardancy, good resistance to high-temperature aging, and a long service life, providing excellent protection at least within the shelf life. Furthermore, the preparation method of the composite material for cable shielding membranes provided by this invention is simple, easy to operate, and convenient for industrial application. Detailed Implementation

[0058] The technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0059] The raw materials used in the embodiments of this invention are all commercially available, including:

[0060] Metallocene linear low-density polyethylene: melt index 4-8 g / 10 min (190℃, 2.16 kg).

[0061] Ethylene-octene copolymer: melt index 0.5-2 g / 10 min (190℃, 2.16 kg);

[0062] Polychlorotrifluoroethylene: melt index range 15-25 g / 10 min (250℃, 2.16 kg);

[0063] Ethylene-trifluorochloroethylene copolymer: melt index range 15-25 g / 10 min (250℃, 2.16 kg);

[0064] Ethylene-tetrafluoroethylene copolymer: melt index of 15-25 g / 10 min (250℃, 2.16 kg);

[0065] Compatibilizer: Maleic anhydride-grafted metallocene polyethylene;

[0066] Silane coupling agents: Fluorinated silane coupling agents (heptadecyltrimethoxysilane);

[0067] Dispersants: Vinyl bis-stearamide and PE wax;

[0068] Antioxidants: Antioxidant 1010, Antioxidant DLTP, Antioxidant 168;

[0069] In addition to magnesium hydroxide, silicon dioxide and montmorillonite.

[0070] The equipment used in the embodiments of this invention is all commercially available: high-speed mixer, twin-screw granulator, and cast extruder (for high temperature and corrosion resistance).

[0071] Example 1: Preparation of Composite Material Particles for Cable Shielding Film

[0072] S1. Magnesium hydroxide, montmorillonite, dispersant, silica, antioxidant and silane coupling agent are pre-mixed in a high-speed mixer to obtain modified powder; wherein the pre-mixing speed is 100-200 rpm, the mixing time is 15-25 min, and the temperature is 25-40℃.

[0073] S2. The modified powder from step S1 is granulated with metallocene linear low-density polyethylene, ethylene-octene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and compatibilizer using a twin-screw extruder to obtain primary granulated modified particles. During the granulation process, the temperature is controlled between 185℃ and 245℃. The obtained primary granulated modified particles are dried at 85℃ for 4 hours before use.

[0074] S3. The particles modified by the initial granulation in step S2 are granulated again by a twin-screw extruder to obtain composite material particles for cable shielding film. During the granulation process, the temperature is controlled between 185℃ and 245℃.

[0075] The proportions of each component added in this embodiment are detailed in Table 1.

[0076] Examples 2-6 and Comparative Examples 1 and 2

[0077] The preparation methods for Examples 2-6 and Comparative Examples 1 and 2 are the same as those for Example 1, except that the components of each material are different, as detailed in Table 1:

[0078] Table 1

[0079] Example 7 Performance Test

[0080] The testing method of this invention is as follows:

[0081] Tensile strength, yield strength and elongation at break were tested according to the test methods of GB / T 1040.3-2006;

[0082] Water vapor transmission rate was tested in an environment with a temperature of 38℃ and a relative humidity of 100%.

[0083] Heat shrinkage was tested at 130℃ for 30 minutes;

[0084] The water contact angle is measured using a water contact angle tester.

[0085] Roughness is measured using a surface roughness tester;

[0086] Sample preparation: The composite material particles of Examples 1-6 and Comparative Examples 1 and 2 were extruded into 50μm films (the conventional thickness of plastic films in cable shielding layers) using a high-temperature corrosion-resistant special casting extruder. The extrusion temperature was 190-270℃. The melt flowing out through the T-die was cooled to 130 / 110 / 90℃ by a special cooling roller group. The cooled and formed film was then subjected to plasma treatment to obtain a film with adhesive properties. The formed film was then pressed by special rollers to obtain a film with a certain surface roughness. The samples in this example were prepared according to the standard of plastic film layers in metal composite strips. The surface treatment of the film was to facilitate the adhesion of other materials and increase anti-slip properties.

[0087] The thin film was tested, and the test results are shown in Table 2:

[0088] Table 2

[0089] As can be seen from Table 2, the films prepared by the composite materials obtained in Examples 1 to 6 of the present invention have significantly improved tensile strength and yield strength, and have low water vapor permeability and good water vapor barrier performance, making them suitable for use in cable shielding layers. The breaking tensile strength of Comparative Example 1 is relatively low, and the tensile strength and yield strength of Comparative Example 2 are poor, and the water vapor permeability is also high, making them unsuitable for use in cable shielding layers.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite material for cable shielding film, characterized in that, Its resin matrix comprises the following components in parts by weight: 30-60 parts by weight of metallocene linear low-density polyethylene; 3-10 parts by weight of ethylene-octene copolymer; 3-20 parts by weight of polychlorotrifluoroethylene; 3-10 parts by weight of ethylene trifluorochloroethylene copolymer; 15-40 parts by weight of ethylene tetrafluoroethylene copolymer; The resin matrix comprises 100 parts by weight.

2. The composite material further includes the following components in parts by weight: 3-8 parts by weight of compatibilizer; 8-18 parts by weight of magnesium hydroxide; 0.2-1 parts by weight of silicon dioxide; 3-15 parts by weight of montmorillonite; 0.3-1 parts by weight of silane coupling agent; Dispersant 0.1-1 parts by weight; Antioxidant 0.1-1 parts by weight.

3. The composite material for cable shielding film as described in claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted metallocene polyethylene. The silane coupling agent is one or more of triethoxysilane coupling agents and fluorinated silane coupling agents; The dispersant is EBS and / or PE wax; The antioxidant is one or more of antioxidant 1010, antioxidant DLTP, or antioxidant 168; 3. The composite material for cable shielding film as described in claim 2, characterized in that, The dispersant is a mixture of EBS and PE wax, with a mass ratio of EBS to PE wax of 1:0.5-2; The antioxidant is a mixture of antioxidant 1010, antioxidant DLTP and antioxidant 168, wherein the mass ratio of antioxidant 1010 to antioxidant DLTP is 1:0.5-2 and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:0.05-0.

2.

4. The composite material for cable shielding film as described in claim 1, characterized in that, When the composite material is a membrane material with a thickness of 25-80 μm, it has the following properties: Tensile strength greater than 40 MPa; Yield strength greater than 15 MPa; Tensile strength at break greater than 300%; The water vapor transmittance is less than 6 under the conditions of 38℃ temperature and 100% relative humidity. At a temperature of 130℃, the thermal shrinkage is less than 8% after 30 minutes.

5. A method for preparing a composite material for cable shielding film according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Magnesium hydroxide, montmorillonite, dispersant, silica, antioxidant and silane coupling agent are pre-blended to obtain modified powder; S2. The modified powder from step S1 is granulated with metallocene linear low-density polyethylene, ethylene-octene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, and compatibilizer through a twin-screw extruder to obtain primary granulated modified particles. S3. The particles modified by the initial granulation in step S2 are granulated again by a twin-screw extruder to obtain composite material particles for cable shielding film.

6. The production method according to claim 5, wherein In step S1, premixing is carried out in a high-speed mixer at a speed of 100-200 rpm, a mixing time of 15-25 min, and a temperature of 25-40℃. In step S2, the initial granulation temperature is 185-245℃; In step S3, the temperature for regranulation is 185-245℃.

7. The production method according to claim 5, wherein Step S2 also includes drying the initially granulated modified particles at a temperature of 70-90℃ for 2-8 hours.

8. The production method according to claim 5, wherein The materials added are as follows, by weight: 30-60 parts by weight of metallocene linear low-density polyethylene; 3-10 parts by weight of ethylene-octene copolymer; 3-20 parts by weight of polychlorotrifluoroethylene; 3-10 parts by weight of ethylene trifluorochloroethylene copolymer; 15-40 parts by weight of ethylene tetrafluoroethylene copolymer; 3-8 parts by weight of compatibilizer; 8-18 parts by weight of magnesium hydroxide; 0.2-1 parts by weight of silicon dioxide; 3-15 parts by weight of montmorillonite; 0.3-1 parts by weight of silane coupling agent; Dispersant 0.1-1 parts by weight; Antioxidant 0.1-1 parts by weight.

9. wherein, A total of 100 parts by weight of metallocene linear low-density polyethylene, ethylene-octene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer and ethylene-tetrafluoroethylene copolymer.

10. The preparation method according to claim 5, characterized in that, The compatibilizer is maleic anhydride-grafted metallocene polyethylene. The silane coupling agent is one or more of triethoxysilane coupling agents and fluorinated silane coupling agents; The dispersant is EBS and / or PE wax; The antioxidant is one or more of antioxidant 1010, antioxidant DLTP, or antioxidant 168; 10. The preparation method according to claim 9, characterized in that, The dispersant is a mixture of EBS and PE wax, with a mass ratio of EBS to PE wax of 1:0.5-2; The antioxidant is a mixture of antioxidant 1010, antioxidant DLTP and antioxidant 168, wherein the mass ratio of antioxidant 1010 to antioxidant DLTP is 1:0.5-2 and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:0.05-0.2.