Ultrahigh-temperature-resistant tab glue

Abstract

The invention relates to an ultrahigh-temperature-resistant tab adhesive, which has the following structure: D / C / B / A / PET / A / B / C / D. PET is a polyethylene glycol terephthalate film layer, A is an alkane dry-process composite adhesive layer, B is a polypropylene layer, D is a maleic anhydride modified polypropylene layer, and C is a pigment layer. The pigment layer C particles are prepared by adding carbon black into maleic anhydride modified polypropylene in proportion for granulation and then mixing with maleic anhydride modified polypropylene thinner particles according to a designed chromaticity proportion; processing the B-layer material particles, the C-layer material particles and the D-layer material particles into a co-extrusion cast film; the double-sided composite co-extrusion cast film technology is adopted for PET, the processing technology is simple, materials are easy to obtain, the cost is greatly reduced, and it is proved that the film is stable in performance, can meet the performance requirements of lithium battery materials and can completely replace imported tab films.

Description

Technical Field

[0001] The invention relates to the technical field of lithium battery packaging, in particular to an ultra-high temperature resistant tab glue. Background Art

[0002] Before 2005, the packaging process of soft-package lithium batteries and tabs was a soft-seal process. The temperature of the top seal was set between 200℃ and 300℃, and the packaging time was 3 to 5 seconds. The lower the top seal temperature was set, the longer the packaging time was, and the lower the efficiency was. On the contrary, the higher the top seal temperature was set, the shorter the packaging time was, and the higher the efficiency was. In order to avoid short circuit or micro-short circuit between the tab metal belt and the aluminum foil in the middle layer of the soft-package aluminum-plastic composite film during top sealing, the tab glue must have an ultra-high temperature resistant layer in the structural design. In 2002, the Japanese company DNP designed and launched the black tab glue for the tabs in the soft-seal process, which still monopolizes the black tab glue. The core of the glue is not the black color, but the high-temperature resistant PEN film in the middle of the film. Nowadays, high-end lithium battery companies all use the hard-sealing top-sealing process, and the top-sealing head temperature of this process is between 170℃~200℃, and the packaging time is short, from 3~5 seconds for soft sealing to 1~2 seconds for hard sealing. The hard seal has compression limit and will not short-circuit. Therefore, there is no high-temperature resistance requirement for the ear glue. The traditional low-end soft sealing process used by other low-end battery manufacturers requires the ear glue to be resistant to high temperatures. Summary of the invention

[0003] The technical problem to be solved by the present invention is to address the deficiencies of the prior art and to propose an ultra-high temperature resistant tab glue for soft-packaged tabs of soft-packaged lithium battery cells, which can significantly reduce production costs.

[0004] The technical problem to be solved by the present invention is achieved through the following technical solution: an ultra-high temperature resistant ear glue, which is characterized by having the following structure: D / C / B / A / PET / A / B / C / D Wherein: PET is a polyethylene terephthalate film layer, A is an alkane dry composite adhesive layer, B is a polypropylene layer, D is a maleic anhydride modified polypropylene layer, and C is a colorant layer; The specific preparation process is: To prepare the color material layer C pellets, carbon black is added into maleic anhydride modified polypropylene at a mass ratio of 5-20%, and pelletized to prepare masterbatch pellets; According to the designed chromaticity ratio requirement, the masterbatch particles and the maleic anhydride modified polypropylene particles are uniformly mixed to prepare the particles of the color material layer C for standby use; Processing the B-layer pellets, the C-layer pellets and the D-layer pellets into a co-extrusion cast film through a three-layer co-extrusion cast device; Single-sided lamination: one side of the PET is corona treated, and then a layer of A alkane dry lamination adhesive is coated on the corona treated surface, the solvent in the A alkane dry lamination adhesive is dried in an oven, and then the adhesive is laminarized with the B layer of the co-extruded cast film. Before lamination, the surface of the B layer of the co-extruded cast film is also corona treated; Repeat the above-mentioned laminating process to laminate the other side of the PET with the B layer of the co-extruded cast film to form a double-sided laminated film of PET; Put the double-sided composite film into a constant temperature oven for curing; The cured composite film is cut into finished rolls of required width.

[0005] The technical problem to be solved by the present invention can be further achieved by the following technical solution, wherein the thickness ratio of the three layers B, C and D is 1:2-3:1.

[0006] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the total thickness of the three layers B, C and D is between 30μ and 50μ.

[0007] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the amount of the masterbatch particles in the C layer particles is 5-20% of the mass of the maleic anhydride modified polypropylene particles.

[0008] The technical problem to be solved by the present invention can also be further achieved by the following technical solution: the coating thickness of the A alkane-based dry composite adhesive is 1μ~5μ.

[0009] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the double-sided composite film is placed in a constant temperature oven for curing at a temperature of 50°C to 90°C, and the curing time is 3 to 5 days.

[0010] Compared with the prior art, the present invention adopts PET as the intermediate base film and adopts a double-sided composite co-extrusion cast film process. The processing technology is simple and the materials are easily available, which greatly reduces the cost. It has been proven that its performance is stable and can meet the performance requirements of lithium battery materials, and can completely replace imported ear glue. DETAILED DESCRIPTION

[0011] The specific technical solutions of the present invention are further described below. To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer and to facilitate those skilled in the art to further understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them, and do not constitute a limitation on the rights thereof. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0012] An ultra-high temperature resistant ear glue has the following structure: D / C / B / A / PET / A / B / C / D Among them: PET is a polyethylene terephthalate film layer, A is an alkane dry composite adhesive layer, B is a polypropylene layer, D is a maleic anhydride modified polypropylene layer, and C is a colorant layer.

[0013] The specific preparation process is: To prepare color material layer C pellets, carbon black is added into maleic anhydride modified polypropylene at a mass ratio of 5-20%, and granulated to prepare masterbatch pellets; the masterbatch pellets and maleic anhydride modified polypropylene pellets are uniformly mixed according to the designed chromaticity ratio requirements to prepare color material layer C pellets for standby use; the amount of the masterbatch pellets in the C layer pellets is 5-20% of the mass of the maleic anhydride modified polypropylene pellets.

[0014] The B layer pellets, the C layer pellets and the D layer pellets are processed into a co-extruded cast film through a three-layer co-extrusion casting device; the thickness ratio of the B layer, the C layer and the D layer is 1:2-3:1. The total thickness of the B layer, the C layer and the D layer is between 30μ and 50μ.

[0015] Single-sided lamination: one of the surfaces of PET is subjected to corona treatment, and then a layer of A alkane dry-process laminating adhesive is coated on the corona-treated surface, the solvent in the A alkane dry-process laminating adhesive is dried in an oven, and then laminating with the B layer of the co-extruded cast film. Before laminating, the surface of the B layer of the co-extruded cast film is also subjected to corona treatment; the coating thickness of the A alkane dry-process laminating adhesive is 1μ~5μ.

[0016] The other side of the PET is subjected to corona treatment, and then a layer of A alkane dry composite adhesive is coated on the corona treated surface, wherein the coating thickness of the A alkane dry composite adhesive is 1μ~5μ. The solvent in the A alkane dry composite adhesive is dried in an oven, and then composited with the B layer of the co-extruded cast film. Before the composite, the surface of the B layer of the co-extruded cast film is also subjected to corona treatment; The double-sided composite film is placed in a constant temperature oven for curing and forming; the temperature of the double-sided composite film in the constant temperature oven for curing and forming is 50° C. to 90° C., and the curing time is 3 to 5 days.

[0017] The cured composite film is cut into finished rolls of required width.

[0018] The chemical structure and properties of PET and PEN are very similar. After years of stability experiments on lithium battery electrolyte resistance, it is proved that the stability of PET in lithium batteries is basically equivalent to that of PEN in lithium batteries, and can meet the performance requirements of lithium battery materials.

[0019] The adhesive adopts an alkane-based dry composite adhesive, which has the ability to organically bond PET and polypropylene together with a certain strength, and the film layer material solidified by the adhesive is stable in the electrolyte.

[0020] Carbon black is added to the C color layer, not to other layers, and the masterbatch in the C color layer is also made of D maleic anhydride modified polypropylene particles. The purpose of this is to minimize the impact of carbon black in the masterbatch layer on the overall composite interlayer strength, and to avoid the carbon black in the D maleic anhydride modified polypropylene layer affecting the hot melt bonding strength with the pole metal strip and the hot melt packaging strength with the inner film of the battery aluminum-plastic composite film.

[0021] In addition, the present invention adopts corona treatment on the surface of the bonding material layer to improve the composite strength and meet the interlayer strength requirements of the ear glue.

[0022] The above is only a detailed description of the best example of the ultra-high temperature resistant ear glue of the present invention, and is not only a limitation of this patent. Those skilled in the art should realize that this patent has many embodiments, and any further improvement or equivalent technical solution based on this patent falls within the scope of protection of this patent.

Claims

1. An ultra-high temperature resistant ear glue, characterized in that Has the following structure: D / C / B / A / PET / A / B / C / D Wherein: PET is a polyethylene terephthalate film layer, A is an alkane dry composite adhesive layer, B is a polypropylene layer, D is a maleic anhydride modified polypropylene layer, and C is a colorant layer; The specific preparation process is: To prepare the color material layer C pellets, carbon black is added into maleic anhydride modified polypropylene at a mass ratio of 5-20%, and pelletized to prepare masterbatch pellets; According to the designed chromaticity ratio requirement, the masterbatch particles and the maleic anhydride modified polypropylene particles are uniformly mixed to prepare the particles of the color material layer C for standby use; Processing the B-layer pellets, the C-layer pellets and the D-layer pellets into a co-extrusion cast film through a three-layer co-extrusion cast device; Single-sided lamination: one side of the PET is corona treated, and then a layer of A alkane dry lamination adhesive is coated on the corona treated surface, the solvent in the A alkane dry lamination adhesive is dried in an oven, and then the adhesive is laminarized with the B layer of the co-extruded cast film. Before lamination, the surface of the B layer of the co-extruded cast film is also corona treated; Repeat the above-mentioned laminating process to laminate the other side of the PET with the B layer of the co-extruded cast film to form a double-sided laminated film of PET; Put the double-sided composite film into a constant temperature oven for curing; The cured composite film is cut into finished rolls of required width.

2. The ultra-high temperature resistant ear glue according to claim 1, characterized in that: The thickness ratio of the three layers, B layer, C layer and D layer, is 1:2-3:

1.

3. The ultra-high temperature resistant ear glue according to claim 1, characterized in that: The total thickness of the three layers, B layer, C layer and D layer, is between 30μ and 50μ.

4. The ultra-high temperature resistant ear glue according to claim 1, characterized in that: The amount of the masterbatch particles in the C layer particles is 5-20% of the mass of the maleic anhydride modified polypropylene particles.

5. The ultra-high temperature resistant ear glue according to claim 1, characterized in that: The coating thickness of the A alkane-based dry composite adhesive is 1 μm to 5 μm.

6. The ultra-high temperature resistant ear glue according to claim 1, characterized in that: The double-sided composite film is placed in a constant temperature oven for curing at a temperature of 50° C. to 90° C., and the curing time is 3 to 5 days.