CN115447236A - Polyester film for lithium battery diaphragm process protection and preparation method thereof - Google Patents

Polyester film for lithium battery diaphragm process protection and preparation method thereof Download PDF

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CN115447236A
CN115447236A CN202211349376.4A CN202211349376A CN115447236A CN 115447236 A CN115447236 A CN 115447236A CN 202211349376 A CN202211349376 A CN 202211349376A CN 115447236 A CN115447236 A CN 115447236A
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polyester film
surface layer
lithium battery
parts
process protection
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余勇
吴晓如
陈弘
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Guangdong Xinrui New Material Technology Co ltd
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Guangdong Xinrui New Material Technology Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
    • C08J3/226—Compounding polymers with additives, e.g. colouring using masterbatch techniques using a polymer as a carrier
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2467/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/24—Acids; Salts thereof
    • C08K3/26—Carbonates; Bicarbonates
    • C08K2003/265—Calcium, strontium or barium carbonate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
    • C08K2003/3045—Sulfates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/54—Silicon-containing compounds
    • C08K5/544—Silicon-containing compounds containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The invention discloses a polyester film for lithium battery diaphragm process protection and a preparation method thereof, relating to the technical field of polyester films and comprising an upper surface layer, a middle layer and a lower surface layer which are sequentially laminated, wherein the upper surface layer and the lower surface layer respectively comprise polyethylene glycol terephthalate and blending modified master batches, and the ratio of the polyethylene glycol terephthalate to the master batches is (95-80) to (5-20); the middle layer is pure polyethylene glycol terephthalate; the master batch comprises 94-97.6 parts of polyethylene glycol terephthalate, 1-2 parts of modified barium sulfate, 1-2 parts of calcium carbonate, 0.1-0.5 part of stearic acid, 0.2-2 parts of fumed silica and 0.1-1 part of silane coupling agent. The polyester film has excellent antistatic capacity, low friction coefficient and mechanical performance through the matching of the components and the matching of the upper surface layer, the lower surface layer and the middle layer.

Description

Polyester film for lithium battery diaphragm process protection and preparation method thereof
Technical Field
The invention relates to the technical field of polyester films, in particular to a polyester film for lithium battery diaphragm process protection and a preparation method thereof.
Background
With the rapid development of new energy automobiles and 5G, the battery industry is also greatly developed, and the battery diaphragm, which is an important component of the lithium battery, determines the interface structure, internal resistance and the like of the lithium battery, can directly influence the capacity, cycle, safety performance and the like of the battery, and has important significance on the comprehensive performance of the lithium battery.
At present, because the electrolyte of the lithium battery is an organic solvent system, the adopted diaphragm material is a polyolefin porous membrane. However, the conventional polyolefin porous separator has certain defects in insulation, mechanical strength, heat resistance, safety and the like. The novel diaphragm comprises a polyester film, which has the characteristics of heat resistance, cold resistance, oil resistance, chemical resistance and the like, and is one of the main research directions of future lithium batteries, but the polyester film still has a plurality of defects, for example, the Chinese invention patent CN103832030A is a polyester film for electronic information and a preparation method thereof, wherein the polyester film comprises a top layer, a core layer and a bottom layer, master batches of the top layer and the bottom layer both contain antistatic agents, and the antistatic agents are tin oxide, zinc oxide or mica sheets, wherein the materials exerting the antistatic ability are single, the stronger antistatic effect is difficult to exert, the improvement of the mechanical property of the novel diaphragm is lacked, and the defects exist in the aspect of the mechanical property. Therefore, a technique to solve the above problems is needed.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a preparation method of a polyester film for lithium battery diaphragm process protection, which aims to solve the problems of poor antistatic capability and poor mechanical property of the existing polyester film.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a polyester film for lithium battery diaphragm process protection comprises an upper surface layer, a middle layer and a lower surface layer which are sequentially laminated, wherein the upper surface layer and the lower surface layer respectively comprise polyethylene terephthalate and blending modified master batches, and the ratio of the polyethylene terephthalate to the master batches is (95-80) to (5-20); the middle layer is pure polyethylene glycol terephthalate; namely, the upper surface layer comprises polyethylene terephthalate and blending modified master batches, and the proportion of the polyethylene terephthalate to the master batches is (95-80) to (5-20); the lower surface layer comprises polyethylene glycol terephthalate and blending modified master batch, and the proportion of the polyethylene glycol terephthalate to the master batch is (95-80) to (5-20); the middle layer is pure polyethylene glycol terephthalate;
the master batch comprises the following components in parts by weight:
94-97.6 parts of polyethylene terephthalate
1-2 parts of modified barium sulfate
1-2 parts of calcium carbonate
0.1 to 0.5 portion of stearic acid
0.2 to 2 portions of fumed silica
0.1-1 part of silane coupling agent.
Further, the proportions of the polyethylene glycol terephthalate and the master batch in the lower surface layer and the upper surface layer are the same;
the polyester film for lithium battery diaphragm process protection comprises an upper surface layer, a middle layer and a lower surface layer, wherein the upper surface layer and the lower surface layer comprise polyethylene glycol terephthalate and master batches, the polyethylene glycol terephthalate is used as a main material and plays a supporting role after being prepared into the film, the mechanical property of a product base is ensured, the master batches comprise the polyethylene glycol terephthalate, modified barium sulfate, calcium carbonate, stearic acid, fumed silica and a silane coupling agent, wherein the calcium carbonate/modified barium sulfate not only has better film opening property, so that the polyester film can not be adhered when being curled, but also has better mechanical property, the stearic acid can enable components to be uniformly distributed, the time and energy required by other substances in a dispersion process are reduced, the stability of the film is improved, the friction coefficient of the surface of the film can be reduced, the antistatic capacity of the film is improved, and the silane coupling agent can strengthen the combination of the fumed silica and the polyester, so that the action of the fumed silica is promoted. According to the invention, calcium carbonate and modified barium sulfate are used as an opening agent, stearic acid is used as a dispersing agent, and fumed silica is used as a slipping agent to be matched together, so that the friction coefficient of the polyester film can be reduced, the antistatic capability of the polyester film can be improved, and the mechanical property of the polyester film can be improved.
Preferably, the calcium carbonate has a particle size of 0.8 to 1.2 μm. The superfine calcium carbonate can enable the polyester film to have better opening performance and mechanical property.
Preferably, the fumed silica has a particle size of 30 to 80nm. The nano-scale fumed silica has smaller molecular weight and higher migration speed to the polyester film; after the nano-scale fumed silica is transferred to the polyester film, the nano-scale fumed silica is solidified and crystallized to form a plurality of bulges, so that the contact area of the polyester film is reduced, and the friction coefficient of the film is reduced.
Preferably, the silane coupling agent is N- (β -aminoethyl) - γ -aminopropyltriethoxysilane. The invention adopts N- (beta-aminoethyl) -gamma-aminopropyltriethoxysilane as silane coupling agent to strengthen the combination of nanometer fumed silica and polyester, so that the two are chemically bonded into a whole to improve the physical and mechanical properties of the polyester film.
Preferably, the particle size of the modified barium sulfate is 0.8 to 1.5 μm.
The particle size of the modified barium sulfate adopted by the invention is 0.8-1.5 mu m, the adopted particle size is smaller, and compared with the modified barium sulfate with larger particle size, the modified barium sulfate enables the polyester film to have better toughness and tear resistance.
Preferably, the thickness of the upper surface layer accounts for 5-10% of the total thickness of the polyester film, the thickness of the middle layer accounts for 80-90% of the total thickness of the polyester film, and the thickness of the lower surface layer accounts for 5-10% of the total thickness of the polyester film. The thickness ratio among the upper surface layer, the middle layer and the lower surface layer can be (10-5) to (80-90) to (10-5). Further, the upper surface layer is the same thickness as the lower surface layer.
The upper surface layer, the middle layer and the lower surface layer are set to be in the thickness proportion, so that the effect of the polyester film on the protection of the lithium battery diaphragm in the manufacturing process can be ensured, and the production cost of the polyester film can be effectively controlled.
Preferably, the thickness of the polyester film is 10 to 20 μm; more preferably, the thickness of the polyester film is 12 μm.
The thickness of the polyester film is 10-20 microns, preferably 12 microns, and the thickness not only can perfectly protect the coating and prevent the polyester film from being deformed caused by equipment traction in the processing process, but also can effectively reduce the use cost in the production process of the power battery diaphragm.
The preparation method of the polyester film comprises the following steps:
preparation of A1 master batch: blending and modifying polyethylene glycol terephthalate, modified barium sulfate, calcium carbonate, stearic acid, fumed silica and a silane coupling agent in corresponding parts by a double-screw extruder, and then extruding;
preparation of A2 polyester film: mixing the pre-prepared master batch and pure polyethylene terephthalate according to a proportion to be used as raw materials of an upper surface layer and a lower surface layer, respectively feeding the pure polyethylene terephthalate as a middle layer into a melt extruder for blending melt extrusion, cooling and casting a sheet, longitudinally stretching, transversely stretching, crystallizing and shaping to obtain the target polyester film. The raw material parts are prepared according to the required thickness proportion of each layer, and the polyester film with the corresponding thickness proportion of the upper surface layer, the middle layer and the lower surface layer is obtained through the step A2. Further, mixing the pre-prepared master batch and pure polyethylene terephthalate according to a proportion to be used as raw materials of an upper surface layer and a lower surface layer, respectively feeding the pure polyethylene terephthalate as a middle layer into a melt extruder with the length-diameter ratio of 35-45 for blending melt extrusion, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Preferably, in the step of preparing the A1 master batch, the blending temperature set by a double-screw extruder is 270-285, and the blending time is 1-3min. Can make various materials in the master batch fully melt and mix, and further improve the granulation effect.
Preferably, in the preparation of the A2 polyester film, the temperature of blending melt extrusion is 270-285. The upper surface layer melt, the middle layer melt and the lower surface layer melt can be fully melted in the temperature range, and the extrusion effect is further improved.
Preferably, the ratio of the length to the diameter of the melt extruder in the step A2 is 35 to 45.
Compared with the prior art, the invention has the following effective effects: the polyester film for protecting the lithium battery diaphragm process comprises an upper surface layer, a middle layer and a lower surface layer, wherein the upper surface layer and the lower surface layer comprise polyethylene glycol terephthalate and master batches, the master batches comprise polyethylene glycol terephthalate, modified barium sulfate, calcium carbonate, stearic acid, fumed silica and a silane coupling agent, and the calcium carbonate not only has better film opening property, so that the polyester film cannot be adhered when being curled, but also has better mechanical property, the stearic acid promotes the uniform distribution of components, the time and energy required by the dispersion process of other substances are reduced, and the stability of the film is improved; the fumed silica can reduce the friction coefficient of the surface of the film and improve the antistatic capability of the film, and the silane coupling agent can strengthen the combination of the fumed silica and the polyester, so that the fumed silica is promoted to play a role. In addition, the invention adopts calcium carbonate as an opening agent, stearic acid as a dispersing agent and fumed silica as a slipping agent to be matched together, so that the friction coefficient of the polyester film can be reduced, the antistatic capability of the polyester film can be improved, and the mechanical property of the polyester film can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of a polyester film for lithium battery separator process protection according to the present invention.
In the figure: 1. an upper surface layer; 2. an intermediate layer; 3. and (4) a lower surface layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
97 parts of polyethylene terephthalate, 1 part of modified barium sulfate, 1 part of calcium carbonate, 0.2 part of stearic acid, 0.7 part of fumed silica and 0.1 part of silane coupling agent are subjected to blending modification by a double-screw extruder and then extruded to obtain master batches;
blending 87 parts of polyethylene terephthalate and 13 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of a middle layer;
according to the proportion of 8 of the upper surface layer, the middle layer and the lower surface layer, respectively entering a main extruder/auxiliary extruder for blending, melting and extruding, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Example 2:
97 parts of polyethylene terephthalate, 1 part of modified barium sulfate, 1 part of calcium carbonate, 0.2 part of stearic acid, 0.7 part of fumed silica and 0.1 part of silane coupling agent are subjected to blending modification by a double-screw extruder and then are extruded and granulated to obtain master batches;
blending 87 parts of polyethylene terephthalate and 13 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of a middle layer;
respectively feeding the materials into a main extruder and an auxiliary extruder for blending, melting and extruding according to the proportion of 10 of an upper surface layer, a middle layer and a lower surface layer, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Comparative example 1:
blending and modifying 96.6 parts of polyethylene terephthalate, 1.5 parts of modified barium sulfate, 1.5 parts of calcium carbonate, 0.2 part of stearic acid, 0 part of fumed silica and 0.2 part of silane coupling agent by a double-screw extruder, and then extruding and granulating to obtain master batches;
blending 83 parts of polyethylene terephthalate and 17 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of an intermediate layer;
and (3) according to the proportion of 5 of the upper surface layer, the middle layer and the lower surface layer, respectively entering a main extruder/auxiliary extruder for blending, melting and extruding, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Comparative example 2:
blending and modifying 93.6 parts of polyethylene terephthalate, 3 parts of modified barium sulfate, 3 parts of calcium carbonate, 0.1 part of stearic acid, 0.2 part of fumed silica and 0.1 part of silane coupling agent by a double-screw extruder, and then extruding and granulating to obtain master batches;
blending 87 parts of polyethylene terephthalate and 13 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of a middle layer;
respectively feeding the materials into a main extruder and an auxiliary extruder for blending, melting and extruding according to the proportion of 10 of an upper surface layer, a middle layer and a lower surface layer, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Comparative example 3:
blending and modifying 98 parts of polyethylene terephthalate, 1 part of modified barium sulfate, 0 part of calcium carbonate, 0.2 part of stearic acid, 0.7 part of fumed silica and 0.1 part of silane coupling agent by a double-screw extruder, and then extruding and granulating to obtain master batches;
blending 87 parts of polyethylene terephthalate and 13 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of a middle layer;
respectively feeding the materials into a main extruder and an auxiliary extruder for blending, melting and extruding according to the proportion of 10 of an upper surface layer, a middle layer and a lower surface layer, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
The equipment and parameters used in the above example are as follows:
the apparatus comprises: a biaxial tension polyester film production line with the width of 6.7m and a gantry cutting machine adaptive to the 6.7m wide film;
temperature: the blending temperature is 270-285, the extrusion temperature is 270-285, the casting temperature is 22-35, the longitudinal stretching temperature is 60-90, the setting temperature after longitudinal stretching is 22-40, the transverse stretching temperature is 80-130, the setting temperature after transverse stretching is 220-250, and the drawing, winding and slitting are carried out to room temperature;
screw rotation speed: the rotating speed of the screw is controlled to be 120rpm-160rpm;
test examples
The polyester films obtained in examples 1 to 2 and comparative examples 1 to 3 were subjected to the following tests:
the antistatic property, tensile property and surface property of the polyester film for lithium battery process protection prepared in examples 1-2 and comparative examples 1-3 were respectively tested, the film thickness was 12 μm, and the test results are shown in the following table:
Figure BDA0003918285030000061
the test result shows that: the polyester films of examples 1 and 2 have excellent antistatic ability, low friction coefficient, and excellent mechanical properties. While comparative example 1 shows high electrostatic residue and weak antistatic ability; comparative example 2 is too high in haze, resulting in additional cost increase; comparative example 3 the friction coefficient is higher, which easily causes salient point abnormity when the product is cut, and influences the smoothness of the product. In general, examples 1, 2 meet the overall performance requirements, while the performance of the polyester film is susceptible to being affected in different ways when the other components are in excess or in small amounts. At least in the comparative example, it was shown that without the addition of fumed silica, the static friction coefficient of the product increased and the static residue increased; when calcium carbonate/barium sulfate is excessively added, haze increases, and when the total amount of calcium carbonate/barium sulfate is excessively small, the friction coefficient increases.
The influence of this type of performance can bring more inconvenience for use or production, for example, the remaining increase of product static can bring the hidden danger for the downstream use, and the haze risees (additive adds excessively) can bring extra cost to increase, and the coefficient of friction is too high and can cause the bump anomaly in the product is cut, influences the product planarization. Based on the component scheme provided by the application, the influence can be balanced, and the polyester film with excellent comprehensive performance can be obtained.
Specifically, the applicant also prepared the following example polyester films by the same preparation method as example 1;
example 3:
blending and modifying 94 parts of polyethylene terephthalate, 2 parts of modified barium sulfate, 1.9 parts of calcium carbonate, 0.5 part of stearic acid, 2 parts of fumed silica and 1 part of silane coupling agent by a double-screw extruder, and extruding to obtain master batches;
blending 92 parts of polyethylene terephthalate and 8 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of an intermediate layer;
and (3) according to the proportion of 6 of the upper surface layer, the middle layer and the lower surface layer, respectively entering a main extruder/auxiliary extruder for blending, melting and extruding, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Example 4:
blending and modifying 95 parts of polyethylene terephthalate, 1.5 parts of modified barium sulfate, 1.5 parts of calcium carbonate, 0.4 part of stearic acid, 1 part of fumed silica and 0.3 part of silane coupling agent by a double-screw extruder, and then extruding and granulating to obtain master batches;
blending 83 parts of polyethylene terephthalate and 17 parts of the blended and modified master batch to obtain raw materials of an upper surface layer and a lower surface layer, wherein pure polyethylene terephthalate is used as a raw material of an intermediate layer;
and (2) according to the proportion of the upper surface layer, the middle layer and the lower surface layer of 9, respectively feeding the materials into a main extruder/auxiliary extruder for blending, melting and extruding, cooling and casting sheets, longitudinally stretching, transversely stretching, crystallizing and shaping, rolling, slitting and packaging to obtain the target polyester film.
Then, the same test method as that described above is adopted, and the test results show that the effects of the examples 3 and 4 are similar to those of the examples 1 and 2, and the antistatic performance, the low friction coefficient and the mechanical performance are excellent, the problem of obvious defects in some aspects is avoided, and the practical use and production requirements are met.
Although the embodiments have been described, other variations and modifications of the embodiments may occur to those skilled in the art once they learn of the basic inventive concepts, so that the above description is only for the embodiments of the present invention, and is not intended to limit the scope of the invention, which is intended to be covered by the present invention.

Claims (10)

1. A polyester film for lithium battery diaphragm process protection is characterized by comprising an upper surface layer, a middle layer and a lower surface layer which are sequentially laminated,
the upper surface layer and the lower surface layer both comprise polyethylene glycol terephthalate and blending modified master batches, and the proportion of the polyethylene glycol terephthalate to the master batches is (95-80) to (5-20); the middle layer is pure polyethylene glycol terephthalate;
the master batch comprises the following components in parts by weight:
94-97.6 parts of polyethylene terephthalate
1-2 parts of modified barium sulfate
1-2 parts of calcium carbonate
0.1 to 0.5 portion of stearic acid
0.2-2 parts of fumed silica
0.1-1 part of silane coupling agent.
2. The polyester film for lithium battery separator process protection as claimed in claim 1, wherein the particle size of the calcium carbonate is 0.8-1.2 μm.
3. The polyester film for lithium battery separator process protection as claimed in claim 1, wherein the particle size of the fumed silica is 30-80nm.
4. The polyester film for lithium battery separator process protection as claimed in claim 1, wherein the silane coupling agent is N- (β -aminoethyl) - γ -aminopropyltriethoxysilane.
5. The polyester film for lithium battery diaphragm process protection of claim 1, wherein the particle size of the modified barium sulfate is 0.8-1.5 μm.
6. The polyester film for lithium battery diaphragm process protection according to any one of claims 1 to 5, wherein the upper surface layer thickness accounts for 5 to 10% of the total thickness of the polyester film, the middle layer thickness accounts for 80 to 90% of the total thickness of the polyester film, and the lower surface layer thickness accounts for 5 to 10% of the total thickness of the polyester film. Further, the upper surface layer is the same thickness as the lower surface layer.
7. The polyester film for lithium battery separator process protection according to any one of claims 1 to 5, wherein the thickness of the polyester film is 10 to 20 μm.
8. The method for preparing the polyester film for the lithium battery diaphragm process protection of any one of claims 1 to 7, is characterized by comprising the following steps:
preparation of A1 master batch: blending and modifying polyethylene glycol terephthalate, modified barium sulfate, calcium carbonate, stearic acid, fumed silica and a silane coupling agent in corresponding parts by a double-screw extruder, and then extruding and granulating;
preparation of A2 polyester film: mixing the pre-prepared master batch and pure polyethylene glycol terephthalate according to a proportion to be used as raw materials of an upper surface layer and a lower surface layer, respectively feeding the pure polyethylene glycol terephthalate as a middle layer into a melt extruder for blending melt extrusion, cooling and casting a sheet, longitudinally stretching, transversely stretching, crystallizing and shaping to obtain the target polyester film.
9. The method for preparing the polyester film for the lithium battery diaphragm process protection according to claim 8, wherein in the preparation of the A1 master batch, the blending temperature set by a double-screw extruder is 270-285, and the blending time is 1-3min;
and/or, in the preparation of the A2 polyester film, the temperature of blending melt extrusion is 270-285.
10. The method for preparing polyester film for lithium battery separator process protection as claimed in claim 8, wherein the ratio of the melt extruder length to diameter in step A2 is 35-45.
CN202211349376.4A 2022-10-31 2022-10-31 Polyester film for lithium battery diaphragm process protection and preparation method thereof Pending CN115447236A (en)

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CN104861530A (en) * 2014-10-15 2015-08-26 青岛欣展塑胶有限公司 Functional white master batch for PTT polyesters and preparation method therefor
CN108773141A (en) * 2018-05-22 2018-11-09 南京亚博联新材料科技股份有限公司 A kind of polyester reflective film and its preparation method and application
CN114083864A (en) * 2021-12-04 2022-02-25 富维薄膜（山东）有限公司 Polyester film for three-layer dry film resist and preparation method thereof
CN114103364A (en) * 2021-12-07 2022-03-01 合肥乐凯科技产业有限公司 Optical polyester film and preparation method thereof

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005329580A (en) * 2004-05-19 2005-12-02 Toray Ind Inc Biaxially oriented laminated thermoplastic resin film
CN101402784A (en) * 2008-11-10 2009-04-08 上海金发科技发展有限公司 Glass fiber reinforced polyethylene terephthalate composite material and method of producing the same
CN103832030A (en) * 2014-02-26 2014-06-04 安徽国风塑业股份有限公司 Polyester film for electronic information and preparation method for polyester film
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