A kind of high heat-resistant power battery diaphragm adhesive and its preparation method

Abstract

The application discloses a kind of high heat-resistant power battery diaphragm binders, preparation raw material includes by weight parts: emulsifier 0.1-5 parts, acrylic monomer 20-30 parts, functional monomer 1-5 parts, initiator 0.01-0.5 parts, auxiliary 0.5-2 parts.The emulsifier of the present application, acrylic ester monomer and functional monomer are gradually reacted with different addition ratios, which can improve the adhesion performance with battery, has good heat resistance, and the thermal yield is low at 150 DEG C high temperature.And using methacrylic acid, butyl acrylate, styrene, acrylonitrile combination as acrylic monomer, the air permeability of adhesive can be improved, and the air permeability is significantly increased compared with traditional adhesive after bonding with battery diaphragm.

Description

TECHNICAL FIELD

[0001] The application relates to a high-heat-resistant power battery separator adhesive and a preparation method thereof, and relates to the field of C09J, in particular to the field of adhesives. BACKGROUND

[0002] With the gradual reduction of petrochemical resources, new energy power is gradually popularized, and a large number of electric vehicles, electric bicycles and electric balance cars are gradually put into use. Power batteries are power sources for providing power for a large number of vehicles. The battery separator is an important part of the battery and will affect the structure, performance and service life of the battery. The traditional battery separator adhesive is polyvinylidene fluoride, which has stable chemical properties and is therefore widely used. In traditional fuel vehicles, the battery only provides a small amount of power output, and low power can meet the use of fuel vehicles. However, with the in-depth study of electric vehicles, electric vehicles need to achieve high power output on the highway to achieve high driving speed, and therefore the battery needs to provide greater power output. The battery will overheat during high-load operation, and polyvinylidene fluoride is prone to thermal runaway. Therefore, it is crucial to develop a new type of battery separator adhesive that can be used in high-temperature environments and has a small thermal shrinkage rate.

[0003] Chinese invention patent CN202110997826.X discloses a kind of acrylic adhesive for lithium battery and its preparation and use method, by using acrylic adhesive, containing long chain easy to entangle, under the action of chemical crosslinking and ionic bond etc., form three-dimensional network structure, improve the bonding strength, improve the shortcomings of polyacrylic acid brittleness, film formation is relatively fragile. However, the high-temperature performance is insufficient, and the properties change easily under high-temperature environment. Chinese invention patent CN201910119488.2 discloses the application of acrylic adhesive in lithium battery separator, which combines polyvinylidene fluoride powder and acrylic adhesive, and coats the lithium battery separator. The problem of air permeability of the battery separator after the adhesive is bonded can be improved, and the tensile property is also obviously improved, but the shrinkage rate changes greatly after heating. SUMMARY

[0004] In order to develop a battery separator adhesive with excellent heat resistance and small heat shrinkage, the first aspect of the application provides a high-heat-resistant power battery separator adhesive, and the preparation raw materials include, by weight: 0.1-5 parts of emulsifier, 20-30 parts of acrylic monomer, 1-5 parts of functional monomer, 0.01-0.5 parts of initiator and 0.5-2 parts of auxiliary agent.

[0005] As a preferred embodiment, the emulsifier is selected from one or a combination of several of anionic surfactants or nonionic surfactants.

[0006] As a preferred embodiment, the non-ionic surfactant is selected from one of polyoxyethylene type non-ionic surfactant or polyether non-ionic surfactant, the polyoxyethylene type non-ionic surfactant is fatty alcohol polyoxyethylene ether, the fatty alcohol is long chain fatty alcohol of C12-C15.

[0007] As a preferred embodiment, the emulsifier is sodium fatty alcohol ether sulfate Disponil FES32.

[0008] As a preferred embodiment, the acrylic monomer is selected from one or combination of acrylic acid, methacrylic acid, butyl acrylate, methyl methacrylate, styrene, acrylonitrile.

[0009] As a preferred embodiment, the acrylic monomer is a combination of methacrylic acid, butyl acrylate, styrene, acrylonitrile.

[0010] As a preferred embodiment, the weight ratio of the methacrylic acid, butyl acrylate, styrene, acrylonitrile is (10-20):(20-30):(10-15):10.

[0011] As a preferred embodiment, the weight ratio of the methacrylic acid, butyl acrylate, styrene, acrylonitrile is 15:25:10:10.

[0012] As a preferred embodiment, the functional monomer is selected from one or combination of glycidyl methacrylate, hydroxyethyl methacrylate, ethylene-vinyl acetate copolymer, acrylamide.

[0013] As a preferred embodiment, the functional monomer is a combination of hydroxyethyl methacrylate and acrylamide.

[0014] As a preferred embodiment, the weight ratio of the hydroxyethyl methacrylate and acrylamide is 1:(1-2).

[0015] As a preferred embodiment, the weight ratio of the hydroxyethyl methacrylate and acrylamide is 1:1.

[0016] The emulsifier, acrylate monomer and functional monomer are gradually reacted in different addition ratios, which can improve the bonding performance with the battery and has good heat resistance, and the possible reason is that different types of acrylic monomers are combined, the weight ratio of butyl acrylate and styrene in the emulsifying kettle A is 5:2, and then the ratio is gradually reduced, the reaction time is controlled to be 1-3h, the Tg point of the prepared polymer connected to different temperatures can be made, the polymer monomer with low glass transition temperature can provide the film forming performance and bonding force of the adhesive, and the polymer monomer with high glass transition temperature can provide high heat resistance, and the application of the adhesive in the power battery separator has excellent comprehensive performance.

[0017] As a preferred embodiment, the initiator is selected from one or a combination of several of organic peroxide initiator, inorganic peroxide initiator, azo initiator, redox system initiator.

[0018] As a preferred embodiment, the inorganic peroxide initiator is selected from one or a combination of several of ammonium sulfate, potassium persulfate, sodium persulfate.

[0019] As a preferred embodiment, the organic peroxide initiator is selected from one or a combination of several of tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, diisopropyl peroxydicarbonate.

[0020] As a preferred embodiment, the initiator is an organic peroxide initiator.

[0021] As a preferred embodiment, the initiator is tert-butyl hydroperoxide.

[0022] The second aspect of the application provides a preparation method of a high-heat-resistant power battery separator adhesive, comprising the following steps:

[0023] (1) adding water and emulsifier in the reaction kettle and heating to 65-90℃;

[0024] (2) adding water, emulsifier, acrylic monomer and functional monomer in the emulsifying kettle A for emulsification to obtain a mixed solution A for standby; adding water, emulsifier, acrylic monomer and functional monomer in the emulsifying kettle B for emulsification to obtain a mixed solution B for standby; adding water, emulsifier, acrylic monomer and functional monomer in the emulsifying kettle C for emulsification to obtain a mixed solution C for standby.

[0025] (3) adding water and initiator in the catalyst kettle to obtain an initiator solution;

[0026] (4) add mixed solution A into the reactor, simultaneously add initiator solution, keep for 0.5-1 h, then add mixed solution B, simultaneously add initiator solution, keep for 0.5-1 h, then add mixed solution C, simultaneously add initiator solution, keep for 0.5-1 h;

[0027] (5) cool to 70-75 °C, add auxiliary agent, mix uniformly, cool to room temperature, filter the product.

[0028] As a preferred embodiment, the weight ratio of water and emulsifier in step 1 is (2-4):(1-3).

[0029] As a preferred embodiment, the weight ratio of water and emulsifier in step 1 is 3:2.

[0030] As a preferred embodiment, the weight ratio of water and initiator in step 3 is (1-5):(0.05-0.3).

[0031] As a preferred embodiment, the weight ratio of water and initiator in step 3 is 3:0.2.

[0032] As a preferred embodiment, in step 4, mixed solution A and initiator solution are added in batches, first add 3-6% of the total volume of mixed solution A and 10-30% of the total volume of initiator solution, carry out initial reaction, after 10-20 min of reaction, add the remaining mixed solution A and 25-35% of the total volume of initiator solution.

[0033] As a preferred embodiment, in step 4, the remaining mixed solution A, mixed solution B and mixed solution C are added dropwise, and the dropwise addition takes 1-2 h.

[0034] As a preferred embodiment, the specific steps of step 4 are: first add 3-6% of the total volume of mixed solution A and 10-30% of the total volume of initiator solution, carry out initial reaction, after 10-20 min of reaction, dropwise add the remaining mixed solution A and 25-35% of the total volume of initiator solution, dropwise addition takes 1-2 h, the remaining mixed solution A and initiator solution are added simultaneously, keep for 0.5-1 h; then dropwise add mixed solution B, simultaneously dropwise add 25-35% of the total volume of initiator solution, dropwise addition takes 1-2 h, keep for 0.5-1 h; then dropwise add mixed solution C, simultaneously dropwise add 25-35% of the total volume of initiator solution, dropwise addition takes 1-2 h, keep for 0.5-1 h.

[0035] As a preferred embodiment, the specific steps of step 4 are: first add 5% of the total volume of mixed solution A and 10% of the total volume of initiator solution, carry out the initial reaction, after 20 minutes of reaction, drop the remaining mixed solution A and 30% of the total volume of initiator solution, drop for 2 hours, and the remaining mixed solution A and initiator solution are added synchronously, and the temperature is kept for 0.5 hours; then drop mixed solution B, synchronously drop 30% of the total volume of initiator solution, drop for 2 hours, and keep the temperature for 0.5 hours; then drop mixed solution C, synchronously drop 30% of the total volume of initiator solution, drop for 2 hours, and keep the temperature for 1 hour.

[0036] As a preferred embodiment, the mass ratio of water, emulsifier, acrylic monomer and functional monomer in the emulsification kettle A of step 2 is 10:(1-2):(20-30):(1-3).

[0037] As a preferred embodiment, the mass ratio of water, emulsifier, acrylic monomer and functional monomer in the emulsification kettle A of step 2 is 10:1.5:25:1.

[0038] As a preferred embodiment, the weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene and acrylonitrile in the emulsification kettle A is 15:25:10:10.

[0039] As a preferred embodiment, the weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene and acrylonitrile in the emulsification kettle B is 15:20:15:10.

[0040] As a preferred embodiment, the weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene and acrylonitrile in the emulsification kettle C is 15:15:20:10.

[0041] The applicant further found that the addition of styrene in the emulsification kettle A, the emulsification kettle B and the emulsification kettle C accounts for (5-10):(10-15):(15-20) of the total mass, which can make the battery adhesive meet the requirement of high temperature resistance of 150℃, and the heat shrinkage rate is less than 2%, which may be due to the fact that the monomer with low glass transition temperature forms a polymer at the beginning of the reaction, and as the reaction proceeds, the polymerization steric hindrance of styrene increases, by controlling the concentration of introduction, improving the polymerization state, and reducing the polymerization resistance, thereby realizing the polymerization of monomers with multiple Tg points.

[0042] As a preferred embodiment, the auxiliary agent includes but is not limited to one or a combination of several of defoaming agent, pH regulator, preservative.

[0043] As a preferred embodiment, the auxiliary agent is an organic silicon defoaming agent.

[0044] Compared with the prior art, the application has the following beneficial effects:

[0045] (1) The high-heat-resistant power battery diaphragm adhesive of the application can improve the bonding performance with the battery on the basis of good heat resistance, and has a low heat yield at a high temperature of 150°C, by gradually reacting emulsifiers, acrylate monomers and functional monomers in different proportions.

[0046] (2) The high-heat-resistant power battery diaphragm adhesive of the application can improve the air permeability of the adhesive by using a combination of methacrylic acid, butyl acrylate, styrene and acrylonitrile as the acrylate monomer, and the air permeability is significantly increased after the adhesive is bonded to the battery diaphragm compared with traditional adhesives.

[0047] (3) The high-heat-resistant power battery diaphragm adhesive of the application can improve the puncture strength of the adhesive by using hydroxyethyl methacrylate and acrylamide as the functional monomer, reduce changes in the performance of the battery diaphragm during use of the battery, and avoid the intercommunication of the positive and negative electrodes of the battery. DETAILED DESCRIPTION

[0048] Example 1

[0049] A high-heat-resistant power battery diaphragm adhesive, the preparation raw materials include, by weight: 3 parts of emulsifier, 25 parts of acrylate monomer, 3 parts of functional monomer, 3 parts of initiator, and 1 part of auxiliary agent.

[0050] The emulsifier is sodium fatty alcohol ether sulfate, model number Disponil FES32, purchased from BASF.

[0051] The acrylate monomer is a combination of methacrylic acid, butyl acrylate, styrene and acrylonitrile.

[0052] The functional monomer is a combination of hydroxyethyl methacrylate and acrylamide, with a weight ratio of 1:1.

[0053] The initiator is tert-butyl peroxide.

[0054] The auxiliary agent is an organic silicon defoaming agent, model number BYK-028, purchased from BYK.

[0055] A preparation method of a high-heat-resistant power battery diaphragm adhesive, comprising the following steps:

[0056] (1) Add water and emulsifier to a reaction kettle, and heat to 80°C, with a weight ratio of water to emulsifier of 3:2;

[0057] (2) In the emulsification kettle A, water, emulsifier, acrylic monomer, functional monomer are emulsified to obtain mixed solution A for standby; In the emulsification kettle B, water, emulsifier, acrylic monomer, functional monomer are emulsified to obtain mixed solution B for standby; In the emulsification kettle C, water, emulsifier, acrylic monomer, functional monomer are emulsified to obtain mixed solution C for standby.

[0058] (3) In the catalyst kettle, water and initiator are added, and the weight ratio of water and initiator is 3:0.2 to obtain initiator solution;

[0059] (4) First, 5% of the total volume of mixed solution A and 10% of the total volume of initiator solution are added, and the initial reaction is carried out, after 20 min, the remaining mixed solution A and 30% of the total volume of initiator solution are added dropwise, the dropwise time is 2h, the remaining mixed solution A and initiator solution are added synchronously, and the temperature is kept at 80℃ for 0.5h; Then mixed solution B is added dropwise, and 30% of the total volume of initiator solution is added synchronously, dropwise for 2h, and the temperature is kept at 80℃ for 0.5h; Then mixed solution C is added dropwise, and 30% of the total volume of initiator solution is added synchronously, dropwise for 2h, and the temperature is kept at 80℃ for 1h;

[0060] (5) Cool to 70℃, add auxiliary, mix evenly, cool to 25℃, filter out the material, and get the product.

[0061] The mass ratio of water, emulsifier, acrylic monomer, and functional monomer in the emulsification kettle A, B, and C of step 2 is 10:1.5:25:1.

[0062] The weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene, and acrylonitrile in the emulsification kettle A is 15:25:10:10.

[0063] The weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene, and acrylonitrile in the emulsification kettle B is 15:20:15:10.

[0064] The weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene, and acrylonitrile in the emulsification kettle C is 15:15:20:10.

[0065] Example 2

[0066] A kind of high heat-resistant power battery diaphragm adhesive and its preparation method, the specific steps are the same as example 1, the difference is that the acrylic monomer is a combination of butyl acrylate and styrene.

[0067] The weight ratio of acrylic monomers methyl methacrylate, butyl acrylate, styrene, and acrylonitrile in the emulsification kettle A is 15:25:10:10.

[0068] The weight ratio of acrylic monomers in the emulsification kettle B is 15:25:10:10, which are methacrylic acid, butyl acrylate, styrene and acrylonitrile.

[0069] The weight ratio of acrylic monomers in the emulsification kettle C is 15:25:10:10, which are methacrylic acid, butyl acrylate, styrene and acrylonitrile.

[0070] Example 3

[0071] A kind of high heat-resistant power battery separator binder and its preparation method, the specific steps are same with example 1, the difference lies in the mass ratio of water, emulsifier, acrylic monomer, functional monomer in the emulsification kettle A in step 2 is 10:1:35:5.

[0072] Example 4

[0073] A kind of high heat-resistant power battery separator binder and its preparation method, the specific steps are same with example 1, the difference lies in the functional monomer is the combination of glycidyl methacrylate and acrylamide, and the weight ratio is 1:3.

[0074] Example 5

[0075] A kind of battery separator binder, which is a commercially available polyvinylidene fluoride binder, purchased from Korea Xiaoxing, model Kynar741.

[0076] Performance test

[0077] The battery separator binder of examples 1-5 is coated on the battery separator, the coating thickness is 3.1 μm, the battery separator thickness is 12.1 μm, the coating area density is 4.9 g / m 2 , the total area density is 10.1 g / m 2 .

[0078] 1. Air permeability test: use 4110 type air permeability tester, lift the instrument air cylinder and select 100 cc volume, place the example 1-5 sample on the instrument, lower the air cylinder, the air cylinder makes the gas pass through the sample under gravity, record the time required for the gas to pass through the sample. Air permeability = time / 100 cc.

[0079] 2. Puncture performance test: coat examples 1-5 on the battery separator, and test the puncture performance according to GB / T 36363-2018.

[0080] 3. Peel strength: coat examples 1-5 on the battery separator, and test the peel strength according to GB / T 7122-1996.

[0081] 4. Thermal shrinkage: The transverse shrinkage and longitudinal shrinkage of the adhesive for battery separator of Examples 1-5 were tested at 150°C. The GB / T 16998-1997 standard was referred to.

[0082] The test results are shown in Table 1.

[0083] Table 1

[0084]

[0085]

Claims

1. A binder for a high-heat-resistant power battery separator, characterized by comprising: The raw materials are prepared by weight parts, including: emulsifier 0.1-5 parts, acrylic monomer 20-30 parts, functional monomer 1-5 parts, initiator 0.01-0.5 parts, auxiliary 0.5-2 parts; The acrylic monomer is a combination of methyl methacrylate, butyl acrylate, styrene and acrylonitrile, with a weight ratio of (10-20):(20-30):(10-15):10; The functional monomer is a combination of hydroxyethyl methacrylate and acrylamide, with a weight ratio of 1:(1-2); The preparation method of the high-heat-resistant binder for power battery separator comprises the following steps: (1) Add water and emulsifier in the reaction kettle and heat to 65-90℃; (2) Add water, emulsifier, acrylic monomer and functional monomer in emulsification kettle A for emulsification to obtain mixed liquid A for standby; add water, emulsifier, acrylic monomer and functional monomer in emulsification kettle B for emulsification to obtain mixed liquid B for standby; add water, emulsifier, acrylic monomer and functional monomer in emulsification kettle C for emulsification to obtain mixed liquid C for standby; (3) Add water and initiator in the catalyst kettle to obtain initiator solution; (4) Add mixed liquid A into the reaction kettle, synchronously add initiator solution, heat for 0.5-1h, then add mixed liquid B, synchronously add initiator solution, heat for 0.5-1h, then add mixed liquid C, synchronously add initiator solution, heat for 0.5-1h; (5) Cool to 70-75℃, add auxiliary, mix uniformly, then cool to room temperature, filter the product to obtain the binder; The mass ratio of water, emulsifier, acrylic monomer and functional monomer in emulsification kettle A in step 2 is 10:(1-2):(20-30):(1-3); The mass ratio of styrene added in emulsification kettle A, emulsification kettle B and emulsification kettle C is (5-10):(10-15):(15-20).

2. The binder for high-heat-resistant power battery separators according to claim 1, characterized by The emulsifier is selected from one or a combination of several of anionic surfactants or non-ionic surfactants.

3. The binder for high-heat-resistant power battery separators according to claim 2, characterized by The non-ionic surfactant is selected from one of polyoxyethylene type non-ionic surfactants or polyether type non-ionic surfactants, the polyoxyethylene type non-ionic surfactant is fatty alcohol polyoxyethylene ether, and the fatty alcohol is long-chain fatty alcohol of C12-C15.

4. The binder for high-heat-resistant power battery separators according to claim 1, characterized by The initiator is selected from one or a combination of several of organic peroxide initiator, inorganic peroxide initiator, azo initiator and oxidation-reduction system initiator.

5. A process for the preparation of the binder for high-temperature-resistant power battery separators according to any one of claims 1 to 4, characterized in that The preparation method comprises the following steps: (1) Add water and emulsifier in the reaction kettle and heat to 65-90℃; (2) Add water, emulsifier, acrylic monomer and functional monomer in emulsification kettle A for emulsification to obtain mixed liquid A for standby; add water, emulsifier, acrylic monomer and functional monomer in emulsification kettle B for emulsification to obtain mixed liquid B for standby; add water, emulsifier, acrylic monomer and functional monomer in emulsification kettle C for emulsification to obtain mixed liquid C for standby; (3) Add water and initiator in the catalyst kettle to obtain initiator solution; (4) Add mixed solution A into the reactor, synchronously add initiator solution, keep warm for 0.5-1h, then add mixed solution B, synchronously add initiator solution, keep warm for 0.5-1h, then add mixed solution C, synchronously add initiator solution, keep warm for 0.5-1h; (5) Cool to 70-75℃, add auxiliary agent, mix uniformly, then cool to room temperature, filter out the product.

6. The process for the preparation of the binder for heat-resistant power battery separators according to claim 5, characterized by the fact that, In step 4, mixed solution A and initiator solution are added in batches, first add 3-6% of mixed solution A in total volume of mixed solution A and 10-30% of initiator solution in total volume of initiator solution, carry out initial reaction, after 10-20min of reaction, add the remaining mixed solution A and 25-35% of initiator solution in total volume of initiator solution.

7. The process for the preparation of the binder for heat-resistant power battery separators according to claim 5, characterized by, In step 4, the remaining mixed solution A, mixed solution B and mixed solution C are added dropwise, the dropwise adding time is 1-2h.

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