CN117565504A - Battery pack buffer fabric with flame retardant function - Google Patents

Abstract

The invention discloses a battery pack buffer fabric with flame retardant function, and relates to the technical field of layered products. It includes a base layer composed of a buffer layer, an absorption layer and a protective layer, and a flame retardant layer composed of a clay layer and a composite flame retardant fabric. The cushioning fabric in this application is added with a flame retardant during manufacture, so that the cushioning fabric itself also has a flame retardant effect. Therefore, when applied to a battery, in addition to having a buffering effect, it also has certain flame retardant properties, which improves the For safety between batteries, in order to prevent adjacent batteries from being affected when a battery catches fire, a thermal conductive layer is also provided on the buffer fabric. The heat transferred from the battery to the buffer fabric is dissipated through the thermal conductive layer, thereby reducing the risk of the buffer fabric. In terms of internal heat, the flame retardant layer of this application not only uses composite flame retardant fabric to retard the battery, but also has a clay layer made of refractory mud, which has better heat resistance and heat isolation to further protect the buffer fabric and battery components.

Description

A kind of battery pack buffering fabric with flame retardant function

Technical field

The invention relates to the technical field of layered products, specifically a battery pack buffer fabric with flame retardant function.

Background technique

In the later stages of the battery cycle, the electrolyte side reactions increase and the battery produces gas, which will further aggravate the expansion of the battery. If the expansion of the battery is not released to a certain extent, the internal expansion force of the battery will cause the pole pieces to swell with each other due to excessive expansion force. Lithium is precipitated by extrusion, thereby accelerating the capacity attenuation of the battery. Therefore, buffer materials are usually added between the batteries inside the module to release the stress generated by the battery during the charge and discharge process. Currently, commonly used buffer materials include ceramic pads and MPP. , return frame, airgel felt, etc., but their heat dissipation performance is poor and the elastic modulus is low. When the battery thermal runaway occurs, the buffer material is quickly damaged and burned, and cannot delay the heat spread of the battery.

The Chinese patent discloses a "buffering flame-retardant material structure and battery pack" (CN217047831U), which uses basalt fiber layer, glass fiber layer, ceramic fiber layer, foamed ceramic layer, rock wool board layer, flame-retardant nylon layer, and mica layer The flame retardant material layer is made of one or at least two laminates of aluminum silicate fiber paper layer and high silica cloth layer. It has a "sandwich" structure and can meet the initial preload force requirements during battery assembly. , and can effectively alleviate the expansion force generated when the battery is charged and discharged, and can also prevent the heat spread of the battery.

Most of the existing flame retardant layers are made of one or more flame retardant materials. This flame retardant method only makes the material itself difficult to ignite, but its heat cannot be well isolated. Therefore, when a certain battery burns, The high temperature generated will still affect adjacent batteries and cause them to expand.

Contents of the invention

The purpose of this section is to outline some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, the abstract and the title of the invention to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the invention.

In view of the fact that the existing flame retardant layer mentioned above or existing in the prior art cannot provide good insulation, when a certain battery is burned, the high temperature generated will still affect the adjacent batteries and cause them to expand.

In order to achieve the above objects, the present invention provides the following technical solutions:

A battery pack buffer fabric with flame retardant function, including a base layer and a flame retardant layer,

Grassroots include:

Buffer layer, the buffer layer is made of foam material and added with foaming agent;

Absorption layer, the absorption layer is made of polyvinyl chloride foam and added with a foaming agent;

Thermal conductive layer, the thermal conductive layer is cut from a thermally conductive silicone sheet;

Protective layer, the protective layer is made of aluminum film;

Flame retardant layer includes:

Clay layer, the clay layer is made of plastic refractory mud,

Composite flame-retardant fabric, the composite flame-retardant fabric is selected from the group consisting of basalt fiber layer, glass fiber layer, ceramic fiber layer, foamed ceramic layer, rock wool plate layer, flame-retardant nylon layer, mica layer, and aluminum silicate fiber paper layer and a laminate of at least two types of high silica cloth layers.

As a further solution of the present invention: the foam material is specifically a composite material mixed with any two materials among polyethylene foam, polyurethane foam and cross-linked polyethylene foam.

As a further solution of the present invention: the polyvinyl chloride foam plastic includes resin, plasticizer, stabilizer, lubricant, filler, foaming agent and flame retardant, specifically:

Resin, using SG resin;

Plasticizer, use any one of phthalate esters, linear esters, epoxy, and phosphate esters;

Stabilizers, including heat stabilizers, antioxidants, and chelating agents;

Lubricant uses silicone oil, paraffin, monoglyceride, stearyl alcohol and esters;

Fillers specifically use talc, barium sulfate, calcium carbonate, titanium dioxide and clay;

Foaming agent uses AADC foaming agent, azobisisobutyronitrile and inorganic foaming agent;

Flame retardant uses chlorinated paraffin, antimony trioxide (2-5 parts), and phosphate ester.

As a further solution of the present invention: the thermally conductive silica gel sheet in the thermally conductive layer is synthesized by using silica gel as a base material and adding metal oxide materials.

As a further solution of the present invention: the raw material of refractory mud is made by crushing, screening and mixing any one or more of dolomite, kaolin, siliceous quartz sand, quartz powder, sepiolite, bentonite and refractory clay.

Compared with the existing technology, the beneficial effects of the battery pack buffer fabric with flame retardant function of the present invention are:

(1) The cushioning fabric in this application is added with a flame retardant during manufacture, so that the cushioning fabric itself also has a flame retardant effect. Therefore, when applied to a battery, in addition to having a buffering effect, it also has certain flame retardant properties. , improves the safety between batteries.

(2) At the same time, in order to prevent the heat generated on the battery from gathering on the buffer fabric, causing the buffer fabric to accumulate heat and affecting other battery components, this application also provides a thermal conductive layer on the buffer fabric, through which the battery is transferred to the buffer fabric. The heat is dissipated, thereby reducing the internal heat of the cushioning fabric. Therefore, when the cushioning fabric in this application is used, the side with the thermal conductive layer needs to be close to the battery.

(3) In order to prevent the battery from affecting adjacent batteries when it catches fire, this application is provided with a flame-retardant layer. In addition to using the composite flame-retardant fabric in the prior art to flame-retard the battery, the flame-retardant layer is further provided with a layer made of refractory mud. The clay layer has good heat resistance and heat insulation to further protect the cushioning fabric and battery components.

At the same time, this application also provides another technical solution, which mainly provides a method for preparing a flame-retardant buffer fabric, and uses a scientific and reasonable preparation method to produce a safe and effective flame-retardant buffer fabric.

In order to achieve the above objects, the present invention provides the following technical solutions:

A method for preparing a battery pack buffer fabric with flame retardant function. The specific steps are as follows:

Grassroots production

(1) The buffer layer is made by cutting polyethylene foam as the base material. The polyethylene foam preparation process can be divided into three steps:

Pre-foaming, pre-foaming is to expand the beads through heating;

For maturation, the pre-expanded beads are placed in a large silo or open container, in contact with external air, and absorb air for solidification. The temperature is controlled at 22-26°C, and the maturation time is 8-10 hours;

Molding, steam heating molding, according to different heating methods, can be divided into cylinder foaming and hydraulic press direct steam foaming;

(2) The absorption layer is made by cutting polyvinyl chloride foam as the base material. The preparation process of polyvinyl chloride foam can be divided into four steps:

Mix, mix the resin, plasticizer, stabilizer, lubricant, filler, foaming agent and flame retardant, grind them on a three-roller mill for 2 to 3 hours, and then add them to a kneader for grinding;

Press film and send the mixture to the mold for compression. The temperature of molding and foaming is 160~165℃, the time is 30~45min, the molding pressure is 5MPa, the cooling temperature is 50℃, the time is 20min;

The heat treatment is carried out in a drying room at a temperature of 90 to 100°C and a time of 15 to 20 minutes;

Cool and place the finished product at room temperature for more than 48 hours;

(3) The thermal conductive layer is made by cutting thermally conductive silicone sheets as raw materials. The main production process steps of thermally conductive silicone gaskets are:

Raw material preparation, mixing metal oxide thermal conductive filler in silica gel;

Plasticizing and mixing reduces the molecular weight and viscosity of raw rubber through mechanical or chemical methods, improves its plasticity, and obtains fluidity. The raw materials of thermally conductive silicone sheets are usually crushed through high-speed mechanical stirring;

Molding vulcanization, the mixed raw materials are vulcanized twice to form a soft thermal conductive layer;

Trimming and cutting, the thermally conductive silicone sheet after high temperature treatment is cut after natural cooling;

Inspection, testing of silicone finished products including thermal conductivity, temperature range, volume resistivity, voltage resistance, flame retardancy, tensile strength, hardness, and thickness;

(4) Flame retardant layer production

Pretreatment, the bulk materials in the raw materials first go through pretreatment steps such as crushing and screening, and then are loaded into storage tanks respectively.

Ingredients, prepare raw material powder according to proportion;

Mix, mix and stir the various powdered raw materials;

Molding, the mixed refractory mud raw materials are molded, using the molding methods of extrusion, pressing, extrusion, injection and painting;

Drying. After the molding is completed, the refractory mud is naturally dried to remove the moisture and strengthen the molding;

After firing, the refractory mud must be fired at high temperature after drying, and the firing temperature is 1000-2000°C;

Composite flame-retardant fabrics are made by mixing any two refractory materials as raw materials, with a basalt fiber layer and a glass fiber layer. The process can be divided into five steps:

Melting, put the mixed materials into a high-temperature furnace for melting, using an electric arc furnace or an induction furnace;

Fiberization, when the mixed material is completely melted, the molten mixed material is drawn into fibers through a wire drawing machine, and the fibers are blown away by high-speed airflow to form a fiber network structure;

After curing, the fibers are blown away and then enter the curing chamber for curing treatment;

Collection, where the solidified basalt fibers are collected and further processed;

Processing, the collected mixed material fibers are pressed to produce mixed material sheets.

As a further solution of the present invention: when making the buffer layer and the absorption layer, a brominated flame retardant is added to the raw materials.

As a further solution of the present invention: the preparation method is as follows:

Step 1: Glue the prepared buffer layer and absorption layer, and attach the aluminum film to the outer surface of the buffer layer;

Step 2: Cut the prepared clay layer according to the size of the absorption layer, and fit the cut clay layer into the absorption layer;

In step 3, the composite flame-retardant fabric is bonded to the clay layer using ceramic glue, and the surface of the composite flame-retardant fabric is directly bonded to the battery surface.

Compared with the existing technology, the beneficial effects of the preparation method of the battery pack buffer fabric with flame retardant function of the present invention are: using each raw material to be manufactured in batches and then through adhesion and pressing, the raw materials at all levels are pressed into a whole to form a Cushioning fabrics with flame-retardant functions can reduce the production time of flame-retardant buffers to a certain extent by using the pressing process. At the same time, the raw materials of the cushioning fabrics are made of non-flammable materials, so that the fabric used for cushioning itself is also flame-retardant. Function.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and understandable, specific implementation modes of the present invention are described in detail below.

Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Those skilled in the art can do so without departing from the connotation of the present invention. Similar generalizations are made, and therefore the present invention is not limited to the specific embodiments disclosed below.

Second, reference herein to "one embodiment" or "an embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. "In one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

Example 1

A battery pack buffer fabric with flame retardant function. The flame retardant performance of the buffer fabric is improved through a clay layer. It includes a base layer and a flame retardant layer. The base layer includes:

Buffer layer. The buffer layer is made of foam material with a foaming agent as an additive. The foam material is specifically a composite material mixed with any two materials among polyethylene foam, polyurethane foam and cross-linked polyethylene foam. The foam material has Low density, closed cell structure, low water absorption, excellent water resistance; good colorability, strong temperature adaptability, excellent radiation resistance, good mechanical strength, excellent buffering performance; good processability, easy molding and other advantages;

The absorption layer is made of polyvinyl chloride foam with a foaming agent as an additive. It is divided into two categories: hard and soft. This application uses soft materials, which have good mechanical properties and impact absorption; it is a A closed-cell soft foam; its density is between 0.05 and 0.1g/cm3; it has stable chemical properties and strong corrosion resistance; it does not absorb water and is not easy to burn. In this embodiment, the polyvinyl chloride foam raw materials include resin, plasticizer, stabilizer, lubricant, filler, foaming agent and flame retardant, specifically:

The resin uses SG resin. SG resin has a loose structure, absorbs plasticizer quickly, has a fast plasticization speed, and has an irregular surface shape. The cross section is loose and porous in a mesh shape to absorb vibration;

Plasticizers can be any one of phthalates, linear esters, epoxy, and phosphate esters. The addition of plasticizers can reduce the force between PVC molecular chains and increase the glass transition temperature of PVC plastics. , the flow temperature and the melting point of the contained microcrystals are reduced. The plasticizer can improve the plasticity of the resin, making the product soft and good in low temperature resistance. In addition, when the plasticizer is added, the heat resistance and corrosion resistance of the product are reduced. , for every additional part of plasticizer, the heat resistance of Martin decreases by 2-3. Therefore, generally no plasticizer is added to hard products or less plasticizer is added. Sometimes a few parts of plasticizer are added in order to improve processing fluidity, while soft products Products need to add a large amount of plasticizer. The greater the amount of plasticizer, the softer the product will be;

Stabilizers include heat stabilizers, antioxidants, and chelating agents. When PVC is processed at high temperatures, it is easy to release HCl, forming an unstable polyene structure. At the same time, HCl has an autocatalytic effect, which will further degrade PVC through stabilization. The addition of additives stabilizes the PVC structure. Specifically, the heat stabilizer must be able to capture the autocatalytic HCl released by the PVC resin, or be able to react with the unstable polyene structure produced by the PVC resin to prevent or mitigate the PVC resin. For the decomposition of PVC products, epoxy stabilizers are usually used as auxiliary stabilizers. During the processing and use of PVC products, they are oxidized due to the action of heat and ultraviolet rays. The oxidative degradation is related to the generation of free radicals. The main antioxidant is a chain break terminator. It is also called a free radical scavenger. Its main function is to combine with free radicals to form a stable compound to terminate the chain reaction. The main antioxidant for PVC is usually bisphenol A, as well as auxiliary antioxidants or hydrogen peroxide decomposers. , PVC auxiliary antioxidants are triphenyl phosphite and benzene diisooctyl phosphite. The main and auxiliary antioxidants can play a synergistic effect when used together; in the PVC plastic stabilization system, the phosphites that are often added are not only auxiliary antioxidants but also It is an oxygenating agent and also acts as a chelating agent. It can form metal complexes with harmful metal ions that promote the removal of HCl from PVC. Commonly used phosphites include triphenyl phosphite, benzene diisooctyl phosphite and phenylene diisooctyl phosphite. Diphenyl octyl phosphate, in PVC agricultural film, is generally used in a dosage of 0.5-1 part. When used alone, it is easy to color in the early stage and has poor thermal stability. It is generally used in combination with metal soaps;

Lubricant uses silicone oil, paraffin, monoglyceride, stearyl alcohol and esters. The function of lubricant is to reduce the friction between the polymer and the equipment, as well as the internal friction between the polymer molecular chains. The former is called external friction. Lubrication, the latter is called internal lubrication, those with external lubrication are silicone oil, paraffin, etc., and those with internal lubrication are monoglycerides, stearyl alcohol and esters;

Filling materials are selected from the formula of soft products, specifically talc, barium sulfate, calcium carbonate, titanium dioxide and clay. Some inorganic fillers are added to PVC as extenders to reduce costs and improve some physical and mechanical properties. (such as hardness, heat distortion temperature, dimensional stability and reduced shrinkage), increase electrical insulation and flame resistance;

Foaming agent uses AADC foaming agent, azobisisobutyronitrile and inorganic foaming agent;

Flame retardants use chlorinated paraffin, antimony trioxide (2-5 parts), and phosphate esters. Rigid PVC plastics are flame retardant due to their high chlorine content. They are used for PVC cables, decorative walls, and plastic draperies. Flame retardants can increase its flame resistance. Phosphate esters and chlorine-containing plasticizers are also flame retardant;

Thermal conductive layer, the thermal conductive layer is cut from at least one of thermally conductive silica gel sheet or carbon fiber thermally conductive pad. Taking thermally conductive silica gel sheet as an example, its density is 3.40g/cc, and the applicable temperature is -50-180°C; carbon fiber thermally conductive pad , density is 3.1g/cm3, applicable temperature is -50-160℃;

Protective layer, the protective layer is made of aluminum film;

Flame retardant layer includes:

Clay layer, the clay layer is made of plastic refractory mud, which generally contains Al2O3≥22%~30%, Si02≥42%73%, and has a refractory degree of 1580~1670°C. This kind of refractory clay becomes soft when soaked in water. It can be made into various shapes and is a raw material for making refractory materials;

Composite flame-retardant fabric, the composite flame-retardant fabric is selected from the group consisting of basalt fiber layer, glass fiber layer, ceramic fiber layer, foamed ceramic layer, rock wool plate layer, flame-retardant nylon layer, mica layer, and aluminum silicate fiber paper layer and a laminate of at least two types of high silica cloth layers.

Example 2

This application also provides another technical solution. This solution mainly provides a method for preparing a flame-retardant buffer fabric. Through a scientific and reasonable preparation method, a safe and effective flame-retardant buffer fabric can be manufactured.

Specific steps are as follows,

(1) Grassroots production:

The buffer layer is made by cutting polyethylene foam as the base material. The polyethylene foam preparation process can be divided into three steps.

Pre-foaming, pre-foaming is to expand the beads to a certain extent by heating, thereby reducing the density of the molded product and reducing the tendency of density gradient formation. The beads after pre-foaming are still granular, but their volume is larger than the original beads. Many times, usually called pre-expansion. If the product density is required to be greater than 100g/L, it can be directly molded with beads without going through the two processes of pre-foaming and curing. During the pre-foaming process, expandable polystyrene beads can be The beads enter the cylinder continuously and evenly through the screw feeder. Under the action of the stirrer, when the beads are heated and expanded, due to different volumetric weights, the light ones rise and the heavy ones sink. As the screw feeder continues to advance, material, the beads at the bottom push the beads at the upper part, rising along the cylinder wall to the discharge port, and then pushed out of the cylinder by centrifugal force, falling into the air duct, and sent to the dryer. The discharge port is equipped with a worm gear mechanism, which can be adjusted Rise and fall, thereby controlling the residence time of the pre-foamed beads in the cylinder, so that the pre-foamed material reaches the specified volume density. There is a stirrer and four pipes in the cylinder, and three steam pipes enter directly from the small holes on the pipes. cylinder to help foaming, and the pipe at the bottom is connected to the compressed air to adjust the temperature at the bottom. The temperature inside the foaming machine barrel should be controlled at 90-105°C. The bulk density of pre-foaming can be determined according to the temperature in the cylinder and the discharge. The height of the outlet and the amount of feed are controlled. When the temperature is high, the position of the outlet is high and the amount of feed is small. The volume density of the pre-expanded beads is small. On the contrary, the volume density is high.

To mature, pre-expanded beads need to be stored for a period of time to absorb air for solidification and prevent shrinkage after molding. Curing is generally carried out in large silos or open containers, with the temperature controlled at 22-26°C. The curing time is determined based on requirements such as bulk density, bead shape, air conditions, etc. Ripening time is generally 8-10h.

Molding, steam heating molding, according to different heating methods, can be divided into cylinder foaming and hydraulic press direct steam foaming;

(2) The absorption layer is made by cutting polyvinyl chloride foam as the base material. The preparation process of polyvinyl chloride foam can be divided into four steps:

Mix, mix the resin, plasticizer, stabilizer, lubricant, filler, foaming agent and flame retardant according to the proportion, grind it on a three-roller mill for 2 to 3 hours, and then add it to the kneader for grinding;

Press film and send the mixture to the mold for compression. The temperature of molding and foaming is 160~165℃, the time is 30~45min, the molding pressure is 5MPa, the cooling temperature is 50℃, the time is 20min;

The heat treatment is carried out in a drying room at a temperature of 90 to 100°C and a time of 15 to 20 minutes;

Cool and place the finished product at room temperature for more than 48 hours;

(3) The thermal conductive layer is made by cutting thermally conductive silicone sheets as raw materials. The main production process steps of thermally conductive silicone gaskets are:

Raw material preparation. The thermal conductivity of general organic silica gel is generally only about 0.2W/m·K. Mixing thermally conductive fillers into ordinary silica gel can improve its thermal conductivity. Metal oxides are commonly used thermally conductive fillers. The thermal conductivity of the filler is not only related to the material itself. It is also closely related to the particle size distribution, shape, interface contact, internal bonding degree of the molecules, etc. of the thermally conductive filler. Generally speaking, fibrous or foil thermally conductive fillers have better thermal conductivity.

Molding and mixing, through mechanical or chemical methods, reduce the molecular weight and viscosity of the raw rubber, improve its plasticity, and obtain appropriate fluidity to meet the needs of further processing, mixing and molding. The raw materials of thermally conductive silicone sheets are usually stirred at high speed by machinery. to be broken,

Molding vulcanization. In order to improve the buffering performance, this application uses a soft thermally conductive layer, so secondary vulcanization of organic silica gel is required. Vulcanization can actually be called curing. After the first stage of heating and molding, the cross-linking density of the liquid thermally conductive silica gel is not enough. In order to increase the tensile strength, resilience, hardness, expansion degree, density and thermal stability of the thermally conductive silicone sheet, further vulcanization reaction is required. If secondary vulcanization is not performed, the performance of the thermally conductive silicone sheet produced may be affected to a certain extent, and a product with better performance may not be obtained. The product parameters after primary vulcanization are inconsistent with those after secondary vulcanization.

Trimming and cutting, the thermally conductive silicone sheet after high temperature treatment is cut to the same specifications after natural cooling.

Inspection, the main testing items of silicone finished products include thermal conductivity, temperature range, volume resistivity, voltage resistance, flame retardancy, tensile strength, hardness, and thickness;

(4) Flame retardant layer production

The clay layer is made using refractory mud as raw material. The refractory mud preparation process can be divided into six steps:

Pretreatment, the large pieces of raw materials first go through pretreatment steps such as crushing and screening, and then are loaded into storage tanks respectively to facilitate subsequent unloading operations;

Ingredients, according to the different needs for the production of refractory mud, prepare various raw material powders in proportion to ensure the uniformity and quality of subsequent production;

Mix, mix and stir the various powdered raw materials;

Molding: After mixing, the mixed refractory mud raw materials are molded. According to the requirements of the product, different molding methods such as extrusion, pressing, extrusion, injection and painting can be used;

Drying. After the molding is completed, the refractory mud is naturally dried to remove the moisture and strengthen the molding;

After firing, the refractory mud must be fired at high temperature after drying to obtain a certain hardness and high temperature resistance. The firing temperature is 1000-2000°C.

Composite flame-retardant fabrics are made by mixing any two refractory materials as raw materials. Taking the mixed material of basalt fiber layer and glass fiber layer as an example, the process can be divided into five steps.

Melting, the preliminarily processed mixed materials are put into a high-temperature furnace for melting. Electric arc furnaces or induction furnaces are usually used to provide a high-temperature environment. At high temperatures, the mixed materials gradually become liquid;

Fiberization, when the mixed material is completely melted, the molten mixed material is drawn into fibers through a wire drawing machine. The wire drawing machine is composed of multiple sets of rollers. The molten magma is drawn into slender fibers through gradually decreasing gaps, and high-speed airflow is used to draw the molten magma into slender fibers. The fibers are blown apart to form a fiber network structure;

After solidification, the fibers are blown away and then enter the curing chamber for curing treatment. The temperature in the curing chamber is moderate, which causes the fibers to quickly cool and solidify. In this process, the structure of the fibers gradually becomes stable, forming strong mixed material fibers;

Collection, the solidified basalt fibers are collected and further processed, usually using airflow or mechanical devices to extract the fibers from the solidification chamber, and perform operations such as classification and grading;

Processing, the collected mixed material fibers are pressed to produce mixed material sheets.

In this embodiment, when making the buffer layer and the absorption layer, a bromine-based flame retardant is added to the raw material. The preparation method of the bromine-based flame retardant is as follows: under the catalysis of AlCl3, p-xylene reacts with Br2 to obtain 2,3, 5,6-Tetrabromo-p-xylene, continue α-H substitution to obtain the product;

(1) Synthesis of tetrabromo-p-xylene: Add 1000kg bromine and 3kg anhydrous AlBr3 into the reaction kettle in sequence. Use ice brine to cool to 0~3°C, and slowly add 80kg xylene while stirring. When lumps appear in the reaction kettle or the viscosity is too high, add 450kg of bromine for dilution. During the dilution process, the temperature can be controlled at 30-35°C. After the lumps disappear, cool to 10-15°C and continue to add the remaining bromine. xylene, react at 20°C for 4 to 6 hours, and evaporate excess bromine. Put the reaction solution into a centrifuge, filter and spin dry, and recrystallize with methanol. The melting point is 253~254°C.

(2) Synthesis of hexabromo-p-xylene: Add 80kg of carbon tetrachloride into the reaction kettle, add 42kg of the above-prepared tetrabromo-p-xylene under stirring, and slowly add bromine-containing carbon tetrachloride under N2 protection. The solution (32kg bromine dissolved in 50L carbon tetrachloride) was heated to reflux for 15 hours, and then cooled to about 3°C. Centrifuge, filter and dry to obtain α, α', 2, 3, 5, 6-hexabromo-p-xylene.

The method of using the above materials to make flame retardant buffer fabric is as follows:

Step 1: Glue the prepared buffer layer and absorption layer, and attach the aluminum film to the outer surface of the buffer layer. The surface of the buffer layer is not in contact with the battery;

Step 2: Cut the prepared clay layer according to the size of the absorption layer, and fit the cut clay layer into the absorption layer;

Step 3: Use ceramic glue to attach the composite flame-retardant fabric to the clay layer, and the surface of the composite flame-retardant fabric is directly attached to the battery surface;

It is important to note that the construction and arrangements of the present application shown in various exemplary embodiments are illustrative only. Although only a few embodiments are described in detail in this disclosure, those reviewing this disclosure will readily appreciate that many modifications are possible without materially departing from the novel teachings and advantages of the subject matter described in this application. are possible (e.g. variations in size, scale, structure, shape and proportion of various elements, as well as parameter values (e.g. temperature, pressure, etc.), mounting arrangements, use of materials, colors, orientations, etc.). For example, an element shown as integrally formed may be constructed from multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of this invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means-plus-function" clauses are intended to cover the structures described herein as performing the function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operation and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the invention is not limited to particular embodiments, but extends to various modifications which still fall within the scope of the appended claims.

Furthermore, in order to provide a concise description of the exemplary embodiments, not all features of an actual implementation may be described (i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention, or that are not relevant to carrying out the invention) feature).

It is understood that numerous implementation-specific decisions may be made during the development of any actual implementation, as in any engineering or design project. Such a development effort might be complex and time consuming, but would be a routine effort of design, manufacture and production without undue experimentation to those of ordinary skill having the benefit of this disclosure.

It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solution of the present invention can be carried out. Modifications or equivalent substitutions without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of the claims of the present invention.

Claims (8)

1. A battery pack buffer fabric with flame retardant function, including a base layer and a flame retardant layer, characterized by: Grassroots include: Buffer layer, the buffer layer is made of foam material and added with foaming agent; Absorption layer, the absorption layer is made of polyvinyl chloride foam and added with a foaming agent; Thermal conductive layer, the thermal conductive layer is cut from a thermally conductive silicone sheet; Protective layer, the protective layer is made of aluminum film; Flame retardant layer includes: Clay layer, the clay layer is made of plastic refractory mud; Composite flame-retardant fabric, the composite flame-retardant fabric is selected from the group consisting of basalt fiber layer, glass fiber layer, ceramic fiber layer, foamed ceramic layer, rock wool plate layer, flame-retardant nylon layer, mica layer, and aluminum silicate fiber paper layer and a laminate of at least two types of high silica cloth layers. 2. A battery pack buffer fabric with flame retardant function according to claim 1, characterized in that the foam material is a mixture of any two materials among polyethylene foam, polyurethane foam and cross-linked polyethylene foam. composite materials. 3. A battery pack cushioning fabric with flame retardant function according to claim 1, characterized in that the polyvinyl chloride foam plastic includes resin, plasticizer, stabilizer, lubricant, filler, foaming agents and flame retardants, specifically: Resin, using SG resin; Plasticizer, use any one of phthalate esters, linear esters, epoxy, and phosphate esters; Stabilizers, including heat stabilizers, antioxidants, and chelating agents; Lubricant uses silicone oil, paraffin, monoglyceride, stearyl alcohol and esters; Fillers specifically use talc, barium sulfate, calcium carbonate, titanium dioxide and clay; Foaming agent uses AADC foaming agent, azobisisobutyronitrile and inorganic foaming agent; Flame retardant uses chlorinated paraffin, antimony trioxide (2-5 parts), and phosphate ester. 4. A battery pack buffer fabric with flame retardant function according to claim 1, characterized in that the thermally conductive silicone sheet in the thermally conductive layer is synthesized by adding silica gel as a base material and adding metal oxide materials. 5. A battery pack buffer fabric with flame retardant function according to claim 1, characterized in that the refractory mud raw materials are dolomite, kaolin, siliceous quartz sand, quartz powder, sepiolite, bentonite, and refractory clay. Any one or two or more of them are made by crushing and screening. 6. A method for preparing a battery pack buffer fabric with a flame retardant function, used to prepare a battery pack buffer fabric with a flame retardant function as claimed in claim 1, characterized in that the specific steps are as follows: Grassroots production: (1) The buffer layer is made by cutting polyethylene foam as the base material. The polyethylene foam preparation process can be divided into three steps: Pre-foaming, pre-foaming is to expand the beads through heating; For maturation, the pre-expanded beads are placed in a large silo or open container, in contact with external air, and absorb air for solidification. The temperature is controlled at 22-26°C, and the maturation time is 8-10 hours; Molding, steam heating molding, according to different heating methods, can be divided into cylinder foaming and hydraulic press direct steam foaming; (2) The absorption layer is made by cutting polyvinyl chloride foam as the base material. The preparation process of polyvinyl chloride foam can be divided into four steps: Mix, mix the resin, plasticizer, stabilizer, lubricant, filler, foaming agent and flame retardant, grind them on a three-roller mill for 2 to 3 hours, and then add them to a kneader for grinding; Press film and send the mixture to the mold for compression. The temperature of molding and foaming is 160~165℃, the time is 30~45min, the molding pressure is 5MPa, the cooling temperature is 50℃, the time is 20min; The heat treatment is carried out in a drying room at a temperature of 90 to 100°C and a time of 15 to 20 minutes; Cool and place the finished product at room temperature for more than 48 hours; (3) The thermal conductive layer is made by cutting thermally conductive silicone sheets as raw materials. The main production process steps of thermally conductive silicone gaskets are: Raw material preparation, mixing metal oxide thermal conductive filler in silica gel; Molding and mixing, reduce the molecular weight and viscosity of raw rubber through mechanical or chemical methods, improve its plasticity, and obtain fluidity. The raw materials of thermally conductive silicone sheets are usually crushed through high-speed mechanical stirring; Molding vulcanization, the mixed raw materials are vulcanized twice to form a soft thermal conductive layer; Trimming and cutting, the thermally conductive silicone sheet after high temperature treatment is cut after natural cooling; Inspection, testing of silicone finished products including thermal conductivity, temperature range, volume resistivity, voltage resistance, flame retardancy, tensile strength, hardness, and thickness; (4) Flame retardant layer production The clay layer is made using refractory mud as raw material. The refractory mud preparation process can be divided into six steps: Pretreatment, the bulk materials in the raw materials first go through pretreatment steps such as crushing and screening, and then are loaded into storage tanks respectively. Ingredients, prepare raw material powder according to proportion; Mix, mix and stir the various powdered raw materials; Molding, the mixed refractory mud raw materials are molded, using the molding methods of extrusion, pressing, extrusion, injection and painting; Drying. After the molding is completed, the refractory mud is naturally dried to remove the moisture and strengthen the molding; After firing, the refractory mud needs to be fired at high temperature after drying, the firing temperature is 1000℃-2000℃; Composite flame-retardant fabrics are made by mixing any two refractory materials as raw materials, with a basalt fiber layer and a glass fiber layer. The process can be divided into five steps: Melting, put the mixed materials into a high-temperature furnace for melting, using an electric arc furnace or an induction furnace; Fiberization, when the mixed material is completely melted, the molten mixed material is drawn into fibers through a wire drawing machine, and the fibers are blown away by high-speed airflow to form a fiber network structure; After curing, the fibers are blown away and then enter the curing chamber for curing treatment; Collection, where the solidified basalt fibers are collected and further processed; Processing, the collected mixed material fibers are pressed to produce mixed material sheets. 7. The method for preparing a battery pack buffer fabric with flame retardant function according to claim 6, characterized in that, when making the buffer layer and the absorption layer, a brominated flame retardant is added to the raw material. 8. A method for preparing a battery pack buffer fabric with a flame retardant function according to claim 6, characterized in that the flame retardant buffer fabric preparation method is as follows: Step 1: Glue the prepared buffer layer and absorption layer, and attach the aluminum film to the outer surface of the buffer layer; Step 2: Cut the prepared clay layer according to the size of the absorption layer, and fit the cut clay layer into the absorption layer; In step 3, the composite flame-retardant fabric is bonded to the clay layer using ceramic glue, and the surface of the composite flame-retardant fabric is directly bonded to the battery surface.