Colored polyester film for lithium battery termination tape

Abstract

The present application relates to a kind of colored polyester film for lithium battery termination tape, belong to polyester film technical field, the colored polyester film is the three-layer structure film of surface layer-core layer-surface layer;Wherein, the composition raw material of the surface layer includes polyester chip;The composition raw material of the core layer includes polyester chip and color masterbatch.The present application is made into product with stronger cohesion strength by forming compact network structure on one hand;On the other hand, by introducing material with larger steric hindrance and introducing material that can make the steric hindrance of system single bond rotation larger, to play stronger steric hindrance effect;In this way, from two aspects, the colored polyester film product made can effectively have excellent electrolyte resistance.In addition, in order to prevent the precipitation of color, the present application also adds molybdenum zinc polyphosphate hydrate to prevent the exudation of color, so it can show excellent protection performance to the color body in system to make the colored polyester film product without color precipitation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyester film, and particularly relates to a colored polyester film for lithium battery termination tape. BACKGROUND

[0002] The lithium battery termination tape is a material for insulating protection and fixed protection of termination parts of various aluminum shell, steel shell, soft package battery cells such as lithium / nickel / cadmium, which usually has color. However, the color of the lithium battery termination tape is not a decorative design, but a necessary choice based on safety warning, functional demand and material performance standardization in the use process. The colorless film cannot replace the core role of the colored film in the protection of lithium batteries due to the lack of visual identification and functional advantages. The lithium battery termination tape is mainly made of polyester, polypropylene or polyimide film as the base material and special lithium battery electrolyte resistant glue coated on the base material, and the polyester film is often selected as the base material of the termination tape due to its excellent mechanical strength and dimensional stability.

[0003] The existing lithium battery termination tapes on the market are generally divided into two types. One is to use transparent polyester film as the base film and add pigments in the glue layer to prepare various colored termination tapes. The other is to directly use colored polyester film as the base film. However, the above two products on the market will have suspended matter or turbidity phenomenon when soaked in electrolyte, and color will also be precipitated, which is easy to cause use risk. Therefore, it is of great practical significance to provide a colored polyester film for lithium battery termination tape to meet the high-end lithium battery standards of electrolyte resistance and safety. SUMMARY

[0004] The purpose of the present application is to provide a colored polyester film for lithium battery termination tape, which solves the problem of electrolyte resistance and color precipitation of the existing colored polyester film for lithium battery termination tape.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A colored polyester film for lithium battery termination tape, the colored polyester film is a three-layer structure film composed of a surface layer, a core layer and a surface layer.

[0007] The surface layer accounts for 10-15% of the total thickness of the colored polyester film, and the core layer accounts for 70-80% of the total thickness of the colored polyester film.

[0008] The composition raw materials of the surface layer include polyester chips; the composition raw materials of the core layer include 90-100 parts by weight of polyester chips and 5-10 parts by weight of color masterbatch.

[0009] As a preferred technical solution of the present application, the polyester chips include the following raw materials:

[0010] 50-60 parts by weight of purified terephthalic acid, 20-25 parts by weight of ethylene glycol, 0.01-0.03 parts by weight of pentaerythritol, 15-20 parts by weight of isooctyl acrylate, 5-8 parts by weight of tung oil, 0.4-0.5 parts by weight of epoxidized m-xylylenediamine, 10-13 parts by weight of isosorbide, 10-15 parts by weight of 1,4-cyclohexanedimethanol, 3-3.5 parts by weight of molybdenum zinc polyphosphate hydrate, 0.4-0.55 parts by weight of initiator, 0.004-0.005 parts by weight of catalyst, and 0.005-0.01 parts by weight of stabilizer;

[0011] The color masterbatch comprises the following raw materials: 100 parts by weight of polyester chips, 20-35 parts by weight of inorganic color powder, and 0.005-0.01 parts by weight of antioxidant.

[0012] Further, the 1,4-cyclohexanedimethanol comprises trans-1,4-cyclohexanedimethanol; the initiator comprises benzoyl peroxide; the catalyst comprises any one of antimony catalyst and titanium catalyst; and the stabilizer comprises at least one of triphenyl phosphite and triphenyl phosphate.

[0013] Still further, the antimony catalyst comprises antimony acetate or diantimony trioxide, and the titanium catalyst comprises tetrabutyl titanate.

[0014] Further, the inorganic color powder comprises, but is not limited to, chromium oxide green, cobalt blue, ultramarine blue, iron yellow, iron oxide red, titanium white, and iron oxide black.

[0015] Further, the antioxidant comprises at least one of antioxidant 1010 and antioxidant 1076.

[0016] As a preferred technical solution of the present application, the preparation method of the polyester chips comprises the following steps:

[0017] A1, temperature-controlling and stirring purified terephthalic acid, ethylene glycol, pentaerythritol, catalyst and stabilizer, then heating and controlling pressure for esterification, and obtaining esterification material after the esterification is completed;

[0018] A2, preparing an initiating liquid, adding isooctyl acrylate and half of the mass of the initiating liquid into the esterification material, then adding isosorbide, 1,4-cyclohexanedimethanol, tung oil and the remaining mass of the initiating liquid in sequence under temperature control, stirring under nitrogen atmosphere, adding molybdenum zinc polyphosphate hydrate after the stirring is completed, stirring uniformly, then adding epoxidized m-xylylenediamine, discharging, casting belt cooling and cutting, removing water, drying, obtaining polyester chip semi-product, and adjusting the intrinsic viscosity of the polyester chip semi-product by using a drum-type solid-phase tackifying device, thereby obtaining polyester chip product.

[0019] As a preferred technical scheme of the present application, the temperature of the temperature-controlled stirring in step A1 is 155-165 DEG C, and the time is 0.5-1 h; the pressure-controlled esterification is specifically: the temperature is raised to 220-250 DEG C, and the esterification is carried out under a pressure of 0.2-0.3 MPa until the total esterification rate reaches 95% or above.

[0020] As a preferred technical scheme of the present application, the initiator solution in step A2 is prepared by diluting the initiator with ethyl acetate to a mass concentration of 10%.

[0021] As a preferred technical scheme of the present application, the conditions for adding the isooctyl acrylate and half of the mass of the initiator solution into the esterification material are 80-90 DEG C and normal pressure; the stirring time after the stirring and temperature control is 1.5-2 h, and the temperature is 210-230 DEG C; the stirring time under the nitrogen atmosphere is 3-4 h; and the stirring time for adding the epoxidized m-xylylenediamine is 0.5-1 h.

[0022] As a preferred technical scheme of the present application, the adjustment of the intrinsic viscosity of the polyester chip semi-product in step A2 is adjusted to 0.75-0.85 dL / g.

[0023] As a preferred technical scheme of the present application, the preparation method of the color master batch comprises the following steps:

[0024] The polyester chip is crushed, mixed with inorganic color powder and antioxidant, and uniformly extruded by a double-screw extruder, and then cast-belt cooled and pelletized to obtain a color master batch semi-product, and the intrinsic viscosity of the color master batch semi-product is adjusted by using a rotary drum solid-phase tackifying device to obtain a color master batch product.

[0025] As a preferred technical scheme of the present application, the temperature of each zone of the double-screw extruder, the temperature of the die head, and the rotation speed are as follows: the temperature of the first zone is 180-200 DEG C, the temperature of the second zone is 210-220 DEG C, the temperature of the third zone is 220-240 DEG C, the temperature of the fourth zone is 220-240 DEG C, the temperature of the die head is 240 DEG C, and the rotation speed is 120-130 r / min.

[0026] As a preferred technical scheme of the present application, the adjustment of the intrinsic viscosity of the color master batch semi-product is adjusted to 0.50-0.65 dL / g.

[0027] A preparation method of a colored polyester film for a lithium battery termination adhesive tape, comprising the following steps:

[0028] S1, the component raw materials of the core layer are uniformly mixed after drying, and are melt-extruded by using a single-screw extruder and vacuumized to obtain a core layer melt;

[0029] S2, the component raw materials of the surface layer are melt-extruded by using a single-screw extruder after drying and vacuumized to obtain a surface layer melt;

[0030] S3, the obtained core layer melt and surface layer melt are respectively transported through melt pipes to a three-layer die in which the surface layer melt-core layer melt-surface layer melt are combined and extruded, the combined and extruded melt is cast onto a cooling roller to form a cast sheet, the cast sheet is subjected to bidirectional stretching, shaping, traction, corona treatment and winding, thereby obtaining a colored polyester film product.

[0031] As a preferred technical solution of the present application, the drying degree of steps S1 and S2 is that the moisture content of each component raw material is less than 50 ppm; the temperature of the single-screw extruder is 255-285℃; and the vacuum degree of the vacuumizing is less than 10 mbar.

[0032] As a preferred technical solution of the present application, the temperature of the cooling roller in step S3 is 18-25℃; the power of the corona treatment is 3-5kW; and the film thickness of the prepared colored polyester film product is 6-25μm.

[0033] The present application has the following advantages:

[0034] (1) The present application innovatively adds isooctyl acrylate to increase the chain length of the system, increase the molecular weight of the whole film, adds tung oil containing conjugated triene structure to introduce more unsaturated double bonds and increase crosslinking sites, and further adds epoxidized m-xylylenediamine to assist in increasing the crosslinking density of the system, so that the system has a compact network structure, effectively enhances the cohesive strength of the system, and the prepared product can effectively resist the corrosion of electrolyte.

[0035] (2) The present application further adds isosorbide with large steric hindrance as another functional monomer to copolymerize to the molecular chain of the system, and trans-1,4-cyclohexanedimethanol with cyclohexyl group is used to make the steric hindrance of the single bond rotation in the molecular chain of the system larger, so that the prepared product has strong steric hindrance effect to effectively resist electrolyte.

[0036] (3) The present application forms a compact network structure to make the prepared product have strong cohesive strength, and introduces functional raw materials with large steric hindrance and raw materials that can make the steric hindrance of the single bond rotation of the system larger to play a strong steric hindrance effect, so that the prepared colored polyester film product has excellent electrolyte resistance from two aspects.

[0037] (4) The molybdenum zinc polyphosphate hydrate is rich in phosphate, and is a modified positive zinc aluminum phosphate with improved phosphate content; in order to prevent color separation, the molybdenum zinc polyphosphate hydrate and inorganic color powder are added to form a protective layer to prevent color penetration, so that the colored polyester film product has no color separation. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] The raw materials used in the embodiments, comparative examples and test examples of the present application are all commercially available products; among them, isooctyl acrylate is purchased from Shandong Xinhongyun Guanghua Chemical Co., Ltd.; tung oil is purchased from Shandong Jibei New Material Co., Ltd.; epoxidized m-xylylenediamine, CAS: 63738-22-7, is purchased from Hubei Hengjie Chemical Co., Ltd.; isosorbide is purchased from Shandong Wenhui Chemical Co., Ltd.; trans-1,4-cyclohexanedimethanol is purchased from Jiangsu Puleisi Biological Technology Co., Ltd.; molybdenum zinc polyphosphate hydrate (ZPA) brand: HEUCOPHOS is purchased from Shanghai Xiaogexin Material Technology Co., Ltd.; the above will not be described in detail hereinafter.

[0040] Embodiment 1

[0041] The polyester chip and the color masterbatch are prepared respectively, and the polyester chip comprises the following raw materials:

[0042] 50 parts by weight of purified terephthalic acid, 22.5 parts by weight of ethylene glycol, 0.02 parts by weight of pentaerythritol, 20 parts by weight of isooctyl acrylate, 5 parts by weight of tung oil, 0.5 parts by weight of epoxidized m-xylylenediamine, 10 parts by weight of isosorbide, 12.5 parts by weight of trans-1,4-cyclohexanedimethanol, 3 parts by weight of molybdenum zinc polyphosphate hydrate, 0.4 parts by weight of benzoyl peroxide, 0.004 parts by weight of tetrabutyl titanate and 0.01 parts by weight of triphenyl phosphite;

[0043] The color masterbatch comprises the following raw materials:

[0044] 100 parts by weight of the polyester chip, 20 parts by weight of chromium oxide green and 0.0075 parts by weight of antioxidant 1010.

[0045] The preparation method of the polyester chip comprises the following steps:

[0046] A1, temperature control 160℃, stirring for 1h, then increase the temperature to 220℃, pressure control 0.2MPa, esterification until the total esterification rate reaches more than 95%, then the esterification is completed, and the esterification material is obtained;

[0047] A2, the initiator is diluted with ethyl acetate to form an initiator solution with a mass concentration of 10%, at 90℃ and normal pressure, the initiator solution is added to the esterification material, stirring for 1.5h, then temperature control 220℃, adding isosorbide, 1,4-cyclohexane dimethanol, tung oil and the remaining mass of initiator solution in turn, stirring for 3h under nitrogen atmosphere, after stirring is completed, adding molybdenum zinc polyphosphate hydrate and stirring uniformly, then adding epoxidized m-xylylenediamine and stirring for 0.5h, discharging, casting belt cooling, granulation, water removal and drying, obtaining polyester chip semi-product, using a drum type solid phase tackiness device to adjust the intrinsic viscosity of the polyester chip semi-product to 0.85dL / g, and then the polyester chip product is obtained;

[0048] The preparation method of the color master batch comprises the following steps:

[0049] The polyester chip product obtained above is crushed and mixed with chromium oxide green and antioxidant 1010 uniformly, then melt extruded through a double screw extruder, casting belt cooling and granulation, obtaining color master batch semi-product, using a drum type solid phase tackiness device to adjust the intrinsic viscosity of the color master batch semi-product to 0.50dL / g, and then the color master batch product is obtained;

[0050] The temperature, die head temperature and rotating speed of each zone of the double screw extruder are as follows: 190℃ for the first zone, 210℃ for the second zone, 220℃ for the third zone, 220℃ for the fourth zone, 240℃ for the die head temperature and 125r / min for the rotating speed.

[0051] Example 2

[0052] The polyester chip and the color master batch are prepared respectively, and the polyester chip comprises the following raw materials:

[0053] 60 parts by weight of purified terephthalic acid, 20 parts by weight of ethylene glycol, 0.03 parts by weight of pentaerythritol, 17.5 parts by weight of isooctyl acrylate, 6.5 parts by weight of tung oil, 0.4 parts by weight of epoxidized m-xylylenediamine, 11.5 parts by weight of isosorbide, 15 parts by weight of trans-1,4-cyclohexane dimethanol, 3.2 parts by weight of molybdenum zinc polyphosphate hydrate, 0.55 parts by weight of benzoyl peroxide, 0.005 parts by weight of antimony acetate and 0.0075 parts by weight of triphenyl phosphate;

[0054] The color master batch comprises the following raw materials:

[0055] 100 parts by weight of the polyester chip, 35 parts by weight of ultramarine blue and 0.01 parts by weight of antioxidant 1076.

[0056] The preparation method of the polyester chip comprises the following steps:

[0057] A1, temperature control 155℃ of purified terephthalic acid, ethylene glycol, pentaerythritol, catalyst and stabilizer, stirring for 0.5h, then increasing the temperature to 250℃, controlling the pressure to 0.3MPa, esterification until the total esterification rate reaches more than 95%, then the esterification is completed, and the esterification material is obtained;

[0058] A2, the initiator is diluted with ethyl acetate to form an initiator solution with a mass concentration of 10%, at 80℃ and normal pressure, the initiator solution is added to the esterification material, stirring for 2h, then temperature control 210℃, adding isosorbide, 1,4-cyclohexane dimethanol, tung oil and the remaining mass of initiator solution in sequence, stirring for 4h under nitrogen atmosphere, after stirring is completed, adding molybdenum zinc polyphosphate hydrate and stirring uniformly, then adding epoxidized m-xylylenediamine and stirring for 1h, discharging, casting belt cooling, cutting, water removal and drying, obtaining polyester chip semi-finished product, using a drum type solid phase tackiness device to adjust the intrinsic viscosity of the polyester chip semi-finished product to 0.75dL / g, and obtaining polyester chip finished product;

[0059] The preparation method of the color master batch comprises the following steps:

[0060] The polyester chip finished product is crushed, mixed with ultramarine blue and antioxidant 1076 uniformly, and then melt extruded through a double screw extruder, and the color master batch semi-finished product is obtained by casting belt cooling and cutting, and the intrinsic viscosity of the color master batch semi-finished product is adjusted to 0.60dL / g by using a drum type solid phase tackiness device, and the color master batch finished product is obtained;

[0061] The temperature, die head temperature and speed conditions of each zone of the double screw extruder are as follows: the first zone is 180℃, the second zone is 220℃, the third zone is 230℃, the fourth zone is 230℃, the die head temperature is 240℃, and the speed is 120r / min.

[0062] Example 3

[0063] The polyester chip and the color master batch are prepared respectively, and the polyester chip comprises the following raw materials:

[0064] 55 parts by weight of purified terephthalic acid, 25 parts by weight of ethylene glycol, 0.01 part by weight of pentaerythritol, 15 parts by weight of isooctyl acrylate, 8 parts by weight of tung oil, 0.45 part by weight of epoxidized m-xylylenediamine, 13 parts by weight of isosorbide, 10 parts by weight of trans-1,4-cyclohexane dimethanol, 3.5 parts by weight of molybdenum zinc polyphosphate hydrate, 0.48 part by weight of benzoyl peroxide, 0.0045 part by weight of antimony trioxide and 0.005 part by weight of triphenyl phosphite;

[0065] The color master batch comprises the following raw materials:

[0066] The polyester chip 100 parts by weight, cobalt blue 27.5 parts by weight, antioxidant 1076 0.005 parts by weight.

[0067] The preparation method of the polyester chip comprises the following steps:

[0068] A1, the purified terephthalic acid, ethylene glycol, pentaerythritol, catalyst and stabilizer temperature control 165℃ stirring 0.5h after heating to 235℃ control pressure 0.2MPa esterification until the total esterification rate reaches more than 95%, esterification is completed, the esterification material is obtained;

[0069] A2, the initiator is diluted with ethyl acetate to a mass concentration of 10% initiator solution, at 85℃, normal pressure conditions, to the esterification material, adding isooctyl acrylate and half of the mass of the initiator solution stirring 2h, then control temperature 230℃, in turn adding isosorbide, 1,4-cyclohexane dimethanol, tung oil and the remaining mass of the initiator solution stirring 3.5h under nitrogen atmosphere, after stirring, adding molybdenum zinc polyphosphate hydrate stirring uniform, then adding epoxidized m-xylylenediamine stirring 1h, through the discharge, casting belt cooling cutting, water removal, drying, to get polyester chip semi-finished product, using the drum type solid phase tackiness device to adjust the intrinsic viscosity of polyester chip semi-finished product is 0.8dL / g, namely the polyester chip product is obtained;

[0070] The preparation method of the color masterbatch comprises the following steps:

[0071] The polyester chip product prepared above is crushed and mixed uniformly with cobalt blue and antioxidant 1076, and then is melt extruded through a double screw extruder, cast belt cooling cutting, to obtain color masterbatch semi-finished product, using the drum type solid phase tackiness device to adjust the intrinsic viscosity of color masterbatch semi-finished product is 0.65dL / g, namely the color masterbatch product is obtained;

[0072] The temperature, die head temperature and rotating speed of each zone of the double screw extruder are as follows: 200℃ for the first zone, 215℃ for the second zone, 240℃ for the third zone, 240℃ for the fourth zone, 240℃ for the die head temperature, and 130r / min for the rotating speed.

[0073] Comparative Example 1

[0074] The difference between Comparative Example 1 and Example 1 is that no isooctyl acrylate is added in Comparative Example 1, and the other parameters and operation steps are the same as those in Example 1.

[0075] Comparative Example 2

[0076] The difference between Comparative Example 2 and Example 1 is that no tung oil is added in Comparative Example 2, and the other parameters and operation steps are the same as those in Example 1.

[0077] Comparative Example 3

[0078] The difference compared with Example 1 is that no epoxidized m-xylylenediamine is added in Comparative Example 3, and the rest of the parameters and operation steps are the same as Example 1.

[0079] Comparative Example 4

[0080] The difference compared with Example 1 is that no isosorbide is added in Comparative Example 4, and the rest of the parameters and operation steps are the same as Example 1.

[0081] Comparative Example 5

[0082] The difference compared with Example 1 is that no trans-1,4-cyclohexanedimethanol is added in Comparative Example 5, and the rest of the parameters and operation steps are the same as Example 1.

[0083] Comparative Example 6

[0084] The difference compared with Example 1 is that no molybdenum zinc polyphosphate hydrate is added in Comparative Example 6, and the rest of the parameters and operation steps are the same as Example 1.

[0085] Example 4

[0086] A colored polyester film for lithium battery termination tape, the colored polyester film is a three-layer structure film composed of a surface layer-core layer-surface layer;

[0087] The surface layer accounts for 12.5% of the total thickness of the colored polyester film, and the core layer accounts for 75% of the total thickness of the colored polyester film;

[0088] The composition raw materials of the surface layer include the polyester chips prepared in Example 2; the composition raw materials of the core layer include 100 parts by weight of the polyester chips of Example 2 and 10 parts by weight of the color masterbatch of Example 2;

[0089] A preparation method of a colored polyester film for lithium battery termination tape, comprising the following steps:

[0090] S1, the composition raw materials of the core layer are mixed uniformly after drying, and are subjected to melt extrusion and vacuum extraction using a single screw extruder, to obtain a core layer melt;

[0091] S2, the composition raw materials of the surface layer are subjected to melt extrusion and vacuum extraction using a single screw extruder after drying, to obtain a surface layer melt;

[0092] S3, the obtained core layer melt and surface layer melt are respectively conveyed to a three-layer die in which the surface layer melt-core layer melt-surface layer melt are placed, and are combined and extruded, and the combined and extruded melt is cast onto a cooling roller to form a cast piece, and the cast piece is subjected to bidirectional stretching, shaping, traction, corona treatment and winding, to obtain a colored polyester film finished product;

[0093] The drying degree of steps S1 and S2 is that the moisture content of each component raw material is less than 50 ppm; the temperature of the single screw extruder is 255℃; and the vacuum degree of the vacuumizing is less than 10 mbar;

[0094] The temperature of the cooling roller in step S3 is 25℃; the power of the corona is 5 kW; and the film thickness of the prepared colored polyester film product is 6 μm.

[0095] Example 5

[0096] A colored polyester film for lithium battery termination tape, the colored polyester film is a three-layer structure film composed of a surface layer-core layer-surface layer;

[0097] The surface layer accounts for 15% of the total thickness of the colored polyester film, and the core layer accounts for 70% of the total thickness of the colored polyester film;

[0098] The component raw material of the surface layer includes the polyester chip prepared in Example 3; and the component raw material of the core layer includes 95 parts by weight of the polyester chip prepared in Example 3 and 5 parts by weight of the color masterbatch prepared in Example 3;

[0099] A preparation method of a colored polyester film for lithium battery termination tape, comprising the following steps:

[0100] S1, the component raw material of the core layer is mixed uniformly after drying, and is melt-extruded by a single screw extruder and vacuumized, to obtain a core layer melt;

[0101] S2, the component raw material of the surface layer is melt-extruded by a single screw extruder after drying and vacuumizing, to obtain a surface layer melt;

[0102] S3, the obtained core layer melt and surface layer melt are respectively conveyed to a three-layer die in which the surface layer melt-core layer melt-surface layer melt are placed, to be combined and extruded, the combined and extruded melt is casted on a cooling roller to form a cast piece, and the cast piece is bidirectionally stretched, shaped, pulled, corona treated and wound, to obtain a colored polyester film product;

[0103] The drying degree of steps S1 and S2 is that the moisture content of each component raw material is less than 50 ppm; the temperature of the single screw extruder is 285℃; and the vacuum degree of the vacuumizing is less than 10 mbar;

[0104] The temperature of the cooling roller in step S3 is 18℃; the power of the corona is 4 kW; and the film thickness of the prepared colored polyester film product is 25 μm.

[0105] Example 6

[0106] A colored polyester film for lithium battery termination tape, the colored polyester film is a three-layer structure film composed of a surface layer-core layer-surface layer;

[0107] The surface layer accounts for 10% of the total thickness of the colored polyester film, and the core layer accounts for 80% of the total thickness of the colored polyester film;

[0108] The composition raw materials of the surface layer include the polyester chips prepared in Example 1; the composition raw materials of the core layer include 90 parts by weight of the polyester chips prepared in Example 1 and 7.5 parts by weight of the color masterbatch prepared in Example 1;

[0109] A preparation method of a colored polyester film for lithium battery termination tape, comprising the following steps:

[0110] S1, the composition raw materials of the core layer are mixed uniformly after drying, and are subjected to melt extrusion and vacuum extraction using a single screw extruder, to obtain a core layer melt;

[0111] S2, the composition raw materials of the surface layer are subjected to melt extrusion and vacuum extraction using a single screw extruder after drying, to obtain a surface layer melt;

[0112] S3, the obtained core layer melt and surface layer melt are respectively conveyed to a three-layer die in which the surface layer melt-core layer melt-surface layer melt are placed, and are combined and extruded, and the combined and extruded melt is cast onto a cooling roller to form a cast sheet, and the cast sheet is subjected to bidirectional stretching, shaping, traction, corona treatment, and winding, to obtain a colored polyester film product;

[0113] The drying degree in steps S1 and S2 is that the moisture content of each composition raw material is less than 50 ppm; the temperature of the single screw extruder is 270°C; and the vacuum degree of the vacuum extraction is less than 10 mbar;

[0114] The temperature of the cooling roller in step S3 is 21.5°C; the power of the corona treatment is 3 kW; and the thickness of the prepared colored polyester film product is 16 μm.

[0115] Comparative Examples 7-12

[0116] Comparative Examples 7-12 are different from Example 6 in that the polyester chips and color masterbatch prepared in Comparative Examples 1-6 are used to replace the polyester chips and color masterbatch prepared in Example 1 in Example 6, and the remaining parameters and operation steps are unchanged.

[0117] Test Example

[0118] The colored polyester film products prepared from Examples 4-6 and Comparative Examples 7-12 were respectively immersed in the same electrolyte under the condition of 85℃*24h. After the immersion, the electrolyte was cooled to room temperature, and the colored polyester film product was observed for color precipitation, suspended matter and turbidity. If the electrolyte has suspended matter or turbidity, it indicates that the prepared colored polyester film product has components that can be dissolved or chemically reacted with the electrolyte, i.e. it does not have electrolyte resistance. Therefore, the judgment standard for the electrolyte-resistant colored polyester film product is: no color precipitation, no suspended matter and no turbidity. The test results are shown in Table 1.

[0119] Table 1

[0120] Coloration Presence of suspended matter Turbidity Example 4 No No No Example 5 No No No Example 6 No No No Comparative Example 7 No No Slight turbidity Comparative Example 8 No Trace of suspended matter More turbid Comparative Example 9 No No Slight turbidity Comparative Example 10 No No Slight turbidity Comparative Example 11 No No Slight turbidity Comparative Example 12 More coloration No No

[0121] As can be seen from Table 1, the colored polyester film products prepared from the raw materials selected in the application can effectively resist the erosion of electrolyte and have excellent electrolyte resistance. As can be found from the comparison between Comparative Example 12 and Examples 4-6, the addition of the molybdenum zinc polyphosphate hydrate in the application can effectively make the prepared colored polyester film product have no color precipitation even after being immersed in electrolyte.

[0122] In the description of the specification, the description of the reference terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0123] The above is only an example and description of the concept of the application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the concept of the application or exceed the scope defined by the claims.

Claims

1. A colored polyester film for a lithium battery termination tape, characterized by, The colored polyester film is a three-layer structure film composed of a surface layer, a core layer and a surface layer. The surface layer accounts for 10-15% of the total thickness of the colored polyester film, and the core layer accounts for 70-80% of the total thickness of the colored polyester film. The composition of the surface layer includes polyester chips; the composition of the core layer includes polyester chips 90-100 parts by weight and color masterbatch 5-10 parts by weight. The polyester chips include the following raw materials: 50-60 parts by weight of purified terephthalic acid, 20-25 parts by weight of ethylene glycol, 0.01-0.03 parts by weight of pentaerythritol, 15-20 parts by weight of isooctyl acrylate, 5-8 parts by weight of tung oil, 0.4-0.5 parts by weight of epoxidized m-xylylenediamine, 10-13 parts by weight of isosorbide, 10-15 parts by weight of trans-1,4-cyclohexane dimethanol, 3-3.5 parts by weight of molybdenum zinc polyphosphate hydrate, 0.4-0.55 parts by weight of initiator, 0.004-0.005 parts by weight of catalyst, and 0.005-0.01 parts by weight of stabilizer. The color masterbatch includes the following raw materials: 100 parts by weight of polyester chips, 20-35 parts by weight of inorganic color powder, and 0.005-0.01 parts by weight of antioxidant.

2. The colored polyester film for a lithium battery termination tape according to claim 1, characterized by, The initiator includes benzoyl peroxide; the catalyst includes any one of antimony-based catalyst and titanium-based catalyst; and the stabilizer includes at least one of triphenyl phosphite and triphenyl phosphate.

3. The colored polyester film for a lithium battery termination tape according to claim 1, characterized by, The inorganic color powder includes chromium oxide green, cobalt blue, ultramarine, iron yellow, iron oxide red, titanium white, and iron oxide black.

4. The colored polyester film for a lithium battery termination tape according to claim 1, characterized by, The preparation method of the polyester chips includes the following steps: A1, temperature-controlled stirring of purified terephthalic acid, ethylene glycol, pentaerythritol, catalyst and stabilizer, then temperature and pressure control esterification, esterification is completed to obtain esterification material; A2, prepare an initiating liquid, add isooctyl acrylate and half of the mass of the initiating liquid to the esterification material, then control the temperature, and successively add isosorbide, 1,4-cyclohexane dimethanol, tung oil and the remaining mass of the initiating liquid under nitrogen atmosphere, stir until completion, then add molybdenum zinc polyphosphate hydrate and stir until uniform, add epoxidized m-xylylenediamine and stir, discharge, cast belt cooling, granulation, water removal, drying to obtain polyester chip semi-product, use a drum type solid phase tackiness device to adjust the intrinsic viscosity of the polyester chip semi-product, and the polyester chip product is obtained.

5. The colored polyester film for a lithium battery termination tape according to claim 4, characterized by The adjustment of the intrinsic viscosity of the polyester chip semi-product in step A2 is adjusted to 0.75-0.85 dL / g.

6. The colored polyester film for a lithium battery termination tape according to claim 1, characterized by, The preparation method of the color masterbatch includes the following steps: After the polyester chips are crushed, mix the inorganic color powder and the antioxidant uniformly, melt extrude through a double screw extruder, cast belt cooling and granulation to obtain color masterbatch semi-product, use a drum type solid phase tackiness device to adjust the intrinsic viscosity of the color masterbatch semi-product, and the color masterbatch product is obtained.

7. The colored polyester film for a lithium battery termination tape according to claim 6, characterized by The adjustment of the intrinsic viscosity of the color masterbatch semi-product is adjusted to 0.50-0.65 dL / g.

8. A process for the production of a colored polyester film for the termination tape of lithium batteries as claimed in any one of claims 1 to 7, characterized in that, The method includes the following steps: S1, mix the composition of the core layer after drying uniformly, melt extrude through a single screw extruder, and vacuumize to obtain core layer melt; S2, melt extrude the composition of the surface layer after drying through a single screw extruder, and vacuumize to obtain surface layer melt; S3, the obtained core layer melt and surface layer melt are respectively transported through melt pipes to a three-layer die in which the surface layer melt-core layer melt-surface layer melt are combined and extruded, the combined and extruded melt is cast onto a cooling roller to form a cast sheet, the cast sheet is subjected to bidirectional stretching, shaping, traction, corona treatment and winding, thereby obtaining a colored polyester film product.

9. The method for preparing the colored polyester film for lithium battery termination tape according to claim 8, characterized in that, The drying degree in steps S1 and S2 is that the moisture content of each component raw material is less than 50 ppm; the temperature of the single-screw extruder is 255-285°C; the vacuum degree of the vacuumizing is less than 10 mbar; the temperature of the cooling roller in step S3 is 18-25°C; the power of the corona treatment is 3-5 kW; and the thickness of the obtained colored polyester film product is 6-25 μm.