CN1333031C - Electric insulating tape, its back film and its back film production method - Google Patents

Abstract

The invention relates to an electric insulating adhesive tape, a back film thereof and a method for preparing the back film thereof, wherein the back film of the electric insulating adhesive tape comprises about 20 to 80 weight percent of polyethylene, about 80 to 20 weight percent of EPDM rubber, about 0 to 30 weight percent of filler and about 0 to 20 weight percent of processing aid. The back film is an environment-friendly material without halogen, has physical properties similar to those of a PVC back film, and can replace PVC in an electrical insulating tape.

Description

Electric insulating tape, its back film and its back film production method

technical field

The invention relates to an electrical insulating adhesive tape, its back film and a method for making the back film. The electrical insulating adhesive tape back film is an environmentally friendly material that does not contain halogen, and its physical properties are similar to those of the PVC electrical insulating tape back film. Electrical insulating tape can replace traditional PVC electrical insulating tape.

Background technique

Generally, polyvinyl chloride (PVC) backing film is used to make electrical insulation tape, because PVC has low cost, good processability, heat resistance and flame resistance, and the output and consumption are extremely large. However, in the past ten years, in response to the trend of environmental protection, advanced countries in the world have actively developed environmentally friendly materials (environmental friendly materials), or eco-materials (eco-materials). Products containing lead and halogens. Therefore, there is an urgent need for other more environmentally friendly materials to replace chlorine-containing PVC backsheets for use in electrical insulating tapes.

In the previous technology, there were researches and developments to replace the back film of PVC electrical insulation tape, but in order to achieve a good feel similar to that of PVC back film, bridging reinforcement was added to the formula, which has an adverse effect on material recycling.

For example, U.S. Patent No. 5,284,889 discloses a back film of an electrical insulating tape, including 60 to 100 parts of EVA (ethylene-vinyl acetate copolymer, poly(ethylene vinylacetate) copolymer), 0 to 40 parts of EPDM (ethylene propylene diene rubber , ethylenepropylene diene rubber), 0.05 to 5 parts of silane coupling agent, 5 to 25 parts of bromine-containing flame retardant, 1.5 to 10 parts of antimony-containing flame retardant and 1 to 20 parts of metal oxide hydrate. It uses EVA as the main body, adds part of EPDM, and then reinforces it by bridging, so it is not easy to recycle.

US Patent No. 5,498,476 discloses a back film of an electrical insulating tape, comprising 60 to 100 parts of EVA, 0 to 40 parts of EPDM, 0.05 to 5 parts of an aminosilane coupling agent and 40 to 150 parts of a phosphate-containing ethylenediamine flame retardant. It uses EVA as the main body, adds part of EPDM, and then reinforces it by bridging, so it is not easy to recycle.

US Patent No. 6,376,068 discloses an insulating protective tape, which includes polyolefin, EPDM and flame retardant, and further includes plasticizer, dye, pigment, antioxidant, or antistatic agent. It is applied to the protection of steel pipes.

The Republic of China Patent Announcement No. 419485 discloses a film and a laminate (electrical insulation material), comprising an ethylene-α-olefin copolymer and cyclopentadiene, methylcyclopentadiene, 1,3-dimethyl Cyclopentadiene, methylcyclopentadienetrimethylsilane, butylcyclopentadiene and other copolymers. Used in electrical cables, containing an electrical insulating layer of the above-mentioned insulating materials.

Contents of the invention

The object of the present invention is to provide a back film of electrical insulating tape, which is similar to PVC back film in terms of hand feel and physical properties, but has no problems of halogen pollution or difficult recycling, and is an environmentally friendly material.

Another object of the present invention is to provide an electrical insulating tape comprising the above-mentioned back film of the electrical insulating tape.

Another object of the present invention is to provide a method for manufacturing the back film of electrical insulating tape. The back film of electrical insulating tape is produced by an original method. Its feel and physical properties are similar to those of PVC, but it does not contain halogen and is easy to recycle.

Another object of the present invention is to provide a back film of electrical insulating tape and an electrical insulating tape comprising the back film, the back film of which is the back film of electrical insulating tape prepared by the above method.

Therefore, the back film of the electrical insulating tape of the present invention includes 20 to 80 weight percent polyethylene, 80 to 20 weight percent EPDM rubber, 0 to 30 weight percent filler, and 0 to 20 weight percent processing aid.

The electrical insulating tape of the present invention comprises the above-mentioned electrical insulating tape back film and an adhesive coated on one surface of the back film.

The method for manufacturing the back film of electrical insulating tape of the present invention comprises the following steps: (i) providing a mixture formed by mixing polyethylene and EPDM rubber; (ii) melting the mixture to form a film at 100 to 240° C., (iii) The film is stretched in the longitudinal direction with a stretch ratio of 1:1 to 1:10 and in the transverse direction with a stretch ratio of 1:1 to 1:10; and (iv) surface-treating the film obtained in step (iii).

The invention uses environmentally friendly polyethylene to make a standard back film for use in electrical insulating tapes, without the problem of difficult recycling in the prior art.

Description of drawings

Fig. 1 shows the stress-strain characteristic curve of the back film of prior art;

Fig. 2 shows the stress-strain characteristic curves of the back film of the electrical insulating tape of the present invention, the conventional PVC back film and the back film of the comparative example.

Detailed ways

The back film of the electrical insulating tape of the present invention comprises about 20 to 80 weight percent, preferably about 30 to 70 weight percent polyethylene (PE). The polyethylene has a molecular weight ranging from about 50,000 to 300,000, preferably about 100,000 to 200,000.

The back film of the electrical insulating tape of the present invention comprises about 80 to 20 weight percent, preferably about 70 to 30 weight percent of EPDM. The EPDM may include about 50 to 95 weight percent ethylene, about 5 to 50 weight percent propylene, and about 0 to 3 weight percent diene.

The electrical insulating tape back film of the present invention may further comprise about 0 to 30 weight percent, preferably about 1 to 20 weight percent filler, for example, silicon dioxide, titanium dioxide, calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate , aluminum silicates and the like. No filler can be added, or a small amount can be added, whichever does not affect the required physical properties of the back film.

The back film of the electrical insulating tape of the present invention may further include about 0 to 20% by weight, preferably about 0.5 to 15% by weight of processing aids, such as release agents, coupling agents, slip agents and the like. The type and amount of processing aids depend on the manufacturing process, and may not be added or added in a small amount, whichever does not affect the required physical properties of the backing film.

The back film of the electrical insulating tape of the present invention may also include for example pigments, dyes, ultraviolet stabilizers, plasticizers, bactericides, antioxidants, waxes, etc., in conventional amounts but without affecting the required physical properties of the back film. use.

The thickness of the back film of the electric insulating adhesive tape of the present invention is between about 0.02 to 0.30mm, preferably between about 0.08 and 0.20mm, the tensile strength is between 1.3 and 3.0kgf/mm ² , and the elongation at break is between 100 and 700%. Among them, the breakdown voltage is between 39 and 150kv/mm, and the deformation recovery ratio is between 5 and 20%. These physical properties are similar to PVC backing film, and the property of breaking voltage is better than PVC backing film. Further by analyzing the stress-strain curve changes when the back film is stretched and retracted, it can be known that the feel of the back film of the present invention is similar to that of the PVC back film, that is, skilled PVC tape users use the electrical insulating tape of the present invention When covering and tearing off the electrical insulating tape made of the back film, the elasticity, toughness, touch feeling, and tight covering caused by stretching and retraction of the tape are similar to those of PVC tape. Therefore, the electrical insulation tape back film of the present invention can completely replace the PVC tape, and has the advantages of no halogen and easy recycling.

The method for manufacturing the electrical insulating tape back film of the present invention, at first provides as above-mentioned polyethylene and EPDM rubber, and other raw materials such as filler, processing aid or additive as above are mixed with mixer or extruder , forming a mixture. The mixing conditions are not limited, and generally the higher the speed of mixing, the better the effect.

Film production can be started after mixing, but generally under the design of convenient mechanical operation, pellets will be pre-pelleted (pellets), for example, using twin-screw kneading and extruding pellets, the screw temperature is about 100 to 240°C.

The above mixture or mixture pellets are melted at about 100 to 240°C, preferably about 140 to 180°C, to form a film. The film-making method can be film-making by blown film forming, single-screw extrusion film-making, twin-screw extrusion film-making, or calendering film-making. The film thickness is in the range of about 0.02 to 0.30 mm.

Next, the film is stretched in the longitudinal direction at a stretch ratio of about 1:1 to 1:10, preferably about 1:1 to 1:5, and in the transverse direction at a stretch ratio of about 1:1 to 1:10, preferably The extension ratio is about 1:1 to 1:5. This membrane extension step is the key and unique part of the method of the present invention. This step endows the prepared electrical insulating tape back film with unique physical properties similar to PVC.

Finally, the film obtained above is subjected to surface treatment to obtain the electrical insulating tape back film of the present invention. Surface treatment is to increase the surface adhesion of the film, so that it can be bonded well with the adhesive used for the tape. Usable surface treatment methods are not limited, and well-known techniques such as corona treatment (eg, 1000 to 5000 volts/cm ² ) or chemical treatment (eg, primer coating) and the like can be used. The final film thickness is about 0.02 to 0.30 mm, preferably 0.08 to 0.20 mm.

The above-mentioned surface-treated back film of the present invention is evenly coated with 0.01 to 0.05mm polymer pressure-sensitive adhesive, such as acrylic, rubber and other adhesives. The insulating tape has the same adhesive force as the traditional PVC electrical insulating tape. Therefore, the electrical insulating tape of the present invention can completely replace the PVC electrical insulating tape, and has environmental protection advantages such as no halogen.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, examples are described as follows.

Example:

Please refer to the stress-strain characteristic curve of the back film of prior art shown in Fig. 1;

Put the release agent of the PE (sub-poly 7100 of Taiwan sub-poly 7100 of 100 weight parts), 118 weight parts of EPDM (DuPont Nordel 1070) and 4.4 weight parts in mixer, high-speed mixing, through twin-screw machine Kneading and extruding to granulate at 190°C. The obtained pellets are placed in a single-screw extruder (the used screw diameter is 90mm, the screw length and diameter ratio (L/D)=30, and the die hole diameter is 400mm) at a temperature range of 140 to 180°C Extruded and blown film. The thickness of the film at the exit of extrusion is 1.8 mm, and then the film is stretched 3.0 times in the longitudinal direction and 4.0 times in the transverse direction using stretching equipment to obtain a film with a thickness of 0.15 mm. Next, corona treatment was performed on the film at a voltage of 2000 volts/cm ² to obtain the finished electrical insulation tape back film of the present invention.

Comparative example:

Only unmodified PE (Yaju 7100, product of Taiwan Yaju Company) was used as raw material, and the back film was prepared as in the embodiment.

Test 1:

Test respectively the tensile strength, elongation at break, breaking voltage and deformation recovery ratio ( According to CNS C4049 test specification). The results are shown in Table 1.

It can be seen from Table 1 that the physical properties of unmodified PE are poor, and the deformation recovery ratio reaches 27 to 32%. The physical properties of the back film of the electrical insulating tape of the embodiment are enhanced, and the stress-strain curve overlaps with that of PVC when stretched, showing the same physical properties, but the breaking voltage is better.

Table 1

sample Tensile strength kgf/mm ² Elongation at break%   Destruction voltage kV/mm Deformation recovery ratio% CNS C4049 qualified value 1.3 100 39 PVC 2.5 124 79 9～12 comparative example 1.5 458 99 27～32 Example 1.8 615 133 11～13

Test 2:

According to CNS C4049 test standard, tensile speed 200mm/ minute, test respectively the stress of the electrical insulation tape back film of the present invention of conventional PVC electrical insulating tape back film, the unmodified PE back film of comparative example and embodiment gained- The strain characteristics are drawn as a stress-strain characteristic curve, as shown in Figure 2. It can be seen from the figure that the tensile strength of the back film of the electrical insulating tape of the present invention is very similar to that of the conventional PVC when stretched, and the tensile strength during retraction is tested again, and there is also a curve similar to that shown by PVC. This data shows that the hand feel of the electrical insulation tape back film of the present invention is very similar to that of conventional PVC when used (pull off, tear off, and wrapped), which is one of the characteristics of the present invention. Referring to Fig. 1, it is three embodiments (material composition is respectively EVA2/EPDM2:75/25 (does not contain filler), EVA2 /EPDM2: 85/25 (without filler), EVA2/EPDM2/ATH1/Br1/Sb1/Mb1: 59/15/11/74/4 (26% filler)) and the stress-strain characteristic curve of PVC Figure, which only analyzes the curve changes during extension, but does not test the tensile strength during retraction, nor does it disclose or teach the physical properties of the electrical insulation tape back film of the present invention similar to PVC during retraction. The present invention analyzes the curve changes when stretching and retracting, and can better grasp the difference between the non-PVC backing film and the PVC backing film, so that the backing film of the electrical insulating tape with better properties can be obtained.

Claims (25)

1. An electrical insulating tape back film, characterized in that: the electrical insulating tape back film comprises 20 to 80 weight percent polyethylene, 80 to 20 weight percent ethylene propylene diene rubber, 0 to 30 weight percent filling agent, and 0 to 20 weight percent processing aids. 2. The back film of electrical insulating tape according to claim 1, characterized in that: the back film of electrical insulating tape does not contain halogen. 3. The electrical insulation tape back film according to claim 1, characterized in that: the electrical insulation tape back film has a tensile strength of 1.3 to 3.0 kgf/mm ² . 4. The electrical insulation tape back film according to claim 1, characterized in that: the electrical insulation tape back film has an elongation at break of 100 to 700%. 5. The back film of electrical insulating tape according to claim 1, characterized in that: the back film of electrical insulating tape has a breakdown voltage of 39 to 150 kv/mm. 6. The back film of electrical insulating tape according to claim 1, characterized in that: the back film of electrical insulating tape has a deformation recovery ratio of 5 to 20%. 7. The electrical insulation tape back film according to claim 1, characterized in that: the thickness of the electrical insulation tape back film is between 0.02 and 0.30 mm. 8. An electrical insulating adhesive tape, characterized in that the back film of the electrical insulating adhesive tape comprises: A back film, the back film includes 20 to 80 weight percent polyethylene, 80 to 20 weight percent ethylene propylene diene rubber, 0 to 30 weight percent filler, and 0 to 20 weight percent processing aids; and An adhesive coated on a surface of the back film. 9. The electrical insulating tape according to claim 8, wherein the back film does not contain halogen. 10. The electrical insulating tape according to claim 8, wherein the back film has a tensile strength of 1.3 to 3.0 kgf/mm ² . 11. The electrical insulating tape according to claim 8, wherein the back film has an elongation at break of 100 to 700%. 12. The electrical insulating tape according to claim 8, wherein the back film has a breakdown voltage of 39 to 150 kv/mm. 13. The electrical insulating tape according to claim 8, wherein the back film has a deformation recovery ratio of 5 to 20%. 14. The electrical insulating tape according to claim 8, characterized in that: the thickness of the back film is between 0.02 and 0.30 mm. 15. A method of manufacturing an electrical insulating tape backing film, comprising the steps of: (i) provide a mixture formed by mixing polyethylene and EPDM rubber, in which polyethylene accounts for 20 to 80 weight percent, and EPDM rubber accounts for 80 to 20 weight percent; (ii) melting the mixture to form a film at 100 to 240°C; (iii) stretching the film in the longitudinal direction with a stretch ratio of 1:1 to 1:10 and in the transverse direction with a stretch ratio of 1:1 to 1:10; and (iv) Surface treating the film obtained in step (iii). 16. The method for manufacturing a back film of an electrical insulating tape according to claim 15, wherein the mixture further contains 0 to 30 weight percent of a filler. 17. The method for manufacturing a back film of an electrical insulating tape according to claim 15, wherein the mixture further contains 0 to 20 weight percent of a processing aid. 18. The method for manufacturing a back film of an electrical insulating tape according to claim 15, wherein the mixture further contains 0 to 15 weight percent of a colorant. 19. The method for producing a back film of an electrical insulating tape according to claim 15, wherein step (ii) melts the mixture at 140 to 180° C. to form a film. 20. The method for manufacturing an electrical insulating tape back film according to claim 15, wherein the method of film making in the step (ii) is blown film forming film making, single-screw extruding film making, twin-screw extruding film making, or calendering membrane. 21. The method for manufacturing an electrical insulating tape back film according to claim 20, wherein the method of film making in step (ii) is single-screw extrusion film making, the screw diameter is 90mm, and the screw length to diameter ratio is 30. 22. The method for manufacturing a back film of an electrical insulating tape according to claim 15, wherein the surface treatment is corona treatment or chemical treatment. 23. The method for manufacturing the back film of an electrical insulating tape according to claim 15, further comprising the step of granulating the mixture after the step (i) and before the step (ii). 24. The electrical insulating tape back film prepared by the method according to any one of claims 15 to 23. 25. according to the electric insulating tape back film that the method described in any one of claim 15 to 23 makes is as the electrical insulating tape that back film makes.

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