Nylon thin film composite material for lithium ion polymer battery outer membrane

Abstract

The invention discloses a nylon film composite material for an outer film of a lithium-ion polymer battery, aiming at providing a nylon film composite material which is stable in thermal property, not easy to absorb moisture, puncture-resistant, high in dry-state and low-temperature impact strength, non-deformable in case of absorbing water, good in multi-layer coextrusion compounding compatibility, balanced in flow extension, and capable of realizing no breakage of a corner in case of an impact depth of 3-12 mm or more. The nylon film composite material disclosed by the invention is realized via the following technical scheme: 8-12 wt% of maleic anhydride (MAH), MAH-blended K resin and graft K-MAH grafted POE (polyolefin elastomer) blend material are contained in a nylon filling body; the nylon filling body takes maleic anhydride grafted polyethylene and ethylene propylene terpolymer rubber as interface compatibilizers; a maleic anhydride grafted elastomer carboxylic acid group is reacted with a polyamide end group or a polyamine group in a main chain to form a grafted copolymer; and epoxy resin siloxane hydrolysate is reacted with an amide group molecular-chain amino group to polymerize the composite material with a multi-element interwoven network. According to the composite material disclosed by the invention, the problem of the phenomenon that PA (polyamide) film heat seal is easy to fold, layer and break at a certain corner is solved.

Description

technical field [0001] The invention relates to a composite nylon material mainly used in polymer lithium ion batteries. Background technique [0002] Polyamide, a general term for thermoplastic resins containing repeated amide groups -[NHCO]- on the main chain of the molecule, is commonly known as nylon (Nylon), and the English abbreviation is PA. PA is a high crystallinity polymer, which will crystallize immediately after stretching, so it cannot be stretched continuously. It must be produced by adding special additives in the traditional two-step production line, and the price is expensive. Since nylon film is a product that is very easy to absorb moisture, it will have adverse effects on the packaging of the polymer lithium-ion battery when it absorbs moisture, such as insufficient composite strength and foaming caused by the water film on the surface. Although it meets different special requirements, it is widely used as a substitute for traditional materials such as m...

AI Technical Summary

Problems solved by technology

Due to its high water absorption, there are still defects such as low dry and low temperature impact strength and deformation after water absorption.

[0003] In the prior art, in order to meet the multi-layer co-extrusion and compounding of the outer layer of the aluminum-plastic composite film flexible packaging material used in the polymer lithium-ion battery, PET and nylon BOPA / aluminum foil are usually selected as the outer packaging barrier layer of the polymer lithium-ion battery. Co-extrusion composites usually use many barrier materials with excellent barrier properties newly developed in recent years, such as MXD6 special nylon film and silicon oxide film as the barrier substrate for the outer layer of aluminum-plastic composite film flexible packaging materials used in polymer lithium-ion batteries, but Due to the large differences in the physical and mechanical properties of the above-mentioned materials in multi-layer co-extrusion, it is often difficult to meet the simultaneous molding of the outer barrier layer of the polymer lithium-ion battery, so that in the process of multi-layer co-extrusion, the fluidity of each layer of material is different. The inconsistency makes the relationship between the cold stamping depth, aluminum foil elongation, and aluminum foil thickness change before and after cold stamping of the most difficult cold stamping flexible packaging material in terms of barrier properties become extremely complicated, which cannot be achieved in multi-layer co-extrusion. After the PP, PE or CPP and the outermost nylon PA or PET of the aluminum foil are compounded, it is difficult to meet the cold stamping formability requirement. The cold stamping depth is 3-12mm or more, and the stamping depth is less than 3mm. Delamination, cracking, Pinhole light leakage, loss of shape retention, and no suitable solution found

This performance of BOPA film will have a great impact on its production and use

For example, after the BOPA film absorbs moisture to a certain extent, it will shrink and deform, which will affect the overprinting accuracy in the printing process, reduce the composite fastness in the compounding process, and cause quality failures such as front and rear misalignment in the bag making process.