Impact-resistant allyl double-sided hot-melt adhesive tape for lithium ion battery and preparation method of impact-resistant allyl double-sided hot-melt adhesive tape

Abstract

The invention relates to the field of adhesives, in particular to an anti-impact propenyl double-sided hot melt adhesive tape for a lithium ion battery and a preparation method thereof.The anti-impact propenyl double-sided hot melt adhesive tape comprises a bonding layer, a back bonding layer and a base tape, the bonding layer and the back bonding layer are arranged on the two sides of the base tape respectively, the bonding layer is used for bonding a battery cell, and the back bonding layer is used for bonding an aluminum-plastic film surface; the bonding layer comprises a bonding layer adhesive, and the bonding layer adhesive comprises a bonding layer organic component, a bonding layer solvent and a bonding layer additive. Compared with the prior art, the impact-resistant propenyl double-sided hot melt adhesive tape for the lithium ion battery and the preparation method thereof have the advantages that the dosage of the hydrogenated styrene block copolymer is greatly reduced, and meanwhile, due to elastomer modification, the mechanical property of an adhesive film is excellent, and various mechanical impacts can be effectively endured; the adhesive is prepared into an emulsion adhesive, on one hand, the use amount of an organic solvent is reduced, the environmental friendliness is improved, on the other hand, a conventional electrolyte-intolerant adhesive is used as supplement in a water phase part, after actual bonding use, the conventional adhesive losing viscosity is gradually inactivated, and a cheese-shaped small-hole adhesive film is formed; and under the conditions of falling, rolling, friction and the like, the impact force can be effectively relieved, the stress borne by the tabs is relieved, and the tabs and the battery cell are protected from being damaged.

Description

[Technical field]

[0001] The invention relates to the field of adhesives, and in particular to an impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries and a preparation method thereof. [Background technology]

[0002] Patent CN114958230A mentions the use of a debonding pressure-sensitive adhesive layer whose viscosity decreases rapidly when immersed in electrolyte, and is composed of a plurality of adhesive units arranged at intervals. Under the action of the electrolyte, it gradually loses its viscosity, and when the battery cell falls, it can dissipate the impact force through the gaps in the substrate layer, thereby protecting the battery cell. However, there are two problems with this patent. First, the longitudinal intermittent coating planned is difficult to install in the coating production process, and it is difficult to have suitable equipment for coating; second, after the debonding pressure-sensitive adhesive layer loses its viscosity, when the battery moves longitudinally multiple times, it is possible to slip between the second and fourth substrate layers described in it, thereby concentrating all longitudinal stresses at the pole ears of the lithium-ion battery, which may cause failure and fracture at the pole ears or even short circuits, posing certain safety hazards.

[0003] CN113913138B mentions an electrolyte-resistant double-sided hot-melt adhesive tape, which uses a hydrogenated styrene block copolymer system electrolyte-resistant adhesive as the main component. This patent mainly uses organic solvent glue, and the amount of organic vapor produced in production is large, which puts forward more requirements for production and environmental protection. At the same time, although the styrene-based material has high strength, its flexibility is low, and it can only be improved by adding polyolefin plastics to achieve a balance. In this context, the aluminum foil material of the battery core material is equivalent to forcibly bonding with the aluminum-plastic film, which easily transmits stress during falling and vibration, causing the surface layer of the battery core to tear, thereby causing the battery core to fail.

[0004] CN109517533B mentions a double-sided hot-melt adhesive tape for lithium batteries without a substrate, which uses two different formulations of glue with different initial viscosity for the surface of the aluminum-plastic film and the surface of the battery foil. This solution eliminates the base tape, reducing the production cost and film thickness on the basis of ensuring strength. However, during the hot pressing process of the substrate-free solution, since the battery cell has not yet undergone the second sealing process during hot pressing, it is generally placed in an inclined state, and the melting thickness of the tape is easily changed due to uneven hot pressing pressure, with one side thicker and the other side thinner, which leads to uneven performance or poor appearance.

[0005] CN115820158A mentions a double-sided hot melt adhesive tape for lithium batteries with a large amount of α-olefin copolymer added. The double-sided adhesive tape has good bonding performance and sufficient film elasticity, and can effectively protect the battery core of lithium-ion batteries. However, since a large amount of POE and hydrogenated styrene block copolymer are required at the same time, the thickness of the tape is relatively thick to ensure performance, which in turn affects the thickness of the lithium-ion battery pack, has a poor space utilization effect, and reduces the energy density of the battery pack.

[0006] In summary, the double-sided hot-melt adhesive tape for lithium batteries in the prior art has shortcomings and needs to be improved. [Summary of the invention]

[0007] In order to overcome the above problems, the present invention provides an impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries and a preparation method thereof, which can effectively solve the above problems.

[0008] The present invention provides a technical solution to solve the above technical problems: providing an impact-resistant propylene-based double-sided hot-melt tape for lithium-ion batteries, comprising an adhesive layer, a back adhesive layer and a base tape, wherein the adhesive layer and the back adhesive layer are respectively arranged on both sides of the base tape, the adhesive layer is used to bond the battery cell, and the back adhesive layer is used to bond the aluminum-plastic film surface; the adhesive layer comprises an adhesive layer adhesive, and the adhesive layer adhesive comprises an adhesive layer organic component, an adhesive layer solvent and an adhesive layer additive.

[0009] Preferably, the back adhesive layer comprises a back adhesive layer adhesive, and the back adhesive layer adhesive comprises a back adhesive layer organic component, a back adhesive layer solvent and a back adhesive layer additive.

[0010] Preferably, the bonding layer adhesive presents an oil-in-water phase, and the bonding layer organic components include a first resin, a second resin and a third resin, wherein the first resin accounts for 60-90% of the total organic components of the bonding layer, the second resin accounts for 10-30% of the total organic components of the bonding layer, and the third resin accounts for 5-15% of the total organic components of the bonding layer.

[0011] Preferably, the adhesive of the back adhesive layer presents a water-in-oil phase, and the organic component of the back adhesive layer includes a first resin and a second resin, wherein the first resin accounts for 80-100% of the total organic component of the back adhesive layer, and the second resin accounts for 0-10% of the total organic component of the back adhesive layer.

[0012] Preferably, the first resin is an electrolyte resistant resin, the second resin is an initial adhesion providing resin, and the third resin is a pore resin.

[0013] Preferably, the adhesive layer solvent includes an oil phase organic solvent and an aqueous phase solvent, and the back adhesive layer solvent includes an oil phase organic solvent; the oil phase organic solvent is a hydrocarbon non-polar or low-polar organic solvent, and the aqueous phase solvent is distilled water.

[0014] Preferably, the adhesive layer additives include a first additive, a second additive and a third additive, and the back adhesive layer additives include a second additive and a third additive; the first additive is an emulsifier, the second additive is an acid-base balancer, and the third additive is an adhesion promoter.

[0015] A method for preparing an impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries, characterized in that it comprises the following steps:

[0016] Step S1, preparing adhesive solution for bonding layer;

[0017] Step S2, preparing adhesive solution for the back adhesive layer;

[0018] Step S3, preparing double-sided hot melt adhesive.

[0019] Preferably, the step S1 includes the following steps:

[0020] Step S11, placing the first resin and the second resin in a container, adding an oil phase organic solvent, heating to 50-80° C., ensuring condensation and reflux, stirring at 100-1000 RPM until completely dissolved, cooling to a constant temperature of 30-40° C. and adding the second additive and the third additive, and stirring for more than 10 minutes to obtain an oil phase solution;

[0021] Step S12, placing the third resin in a container, adding a mixed solvent of distilled water and ethanol, heating to 30-40°C, ensuring condensation and reflux, stirring at a speed of 100-1000 RPM until completely dissolved and set aside to obtain an aqueous phase solution.

[0022] Step S13, placing the first additive in a container, adding the remaining oil phase solvent in step S11, heating to 30-40° C., ensuring condensation and reflux, stirring at 100-1000 RPM until completely dissolved and set aside;

[0023] Step S14, respectively adding the first additive and the aqueous phase solution to the oil phase solution, the adding time should be 40-80 minutes, and the first additive and the aqueous phase solution should be added at the same time, the system temperature is controlled at 30-40°C, and the rotation speed is controlled at 100-1000RPM during the adding;

[0024] Step S15, after the dropwise addition is completed, the temperature is naturally lowered, and the rotation speed is increased to 500-3000 RPM, and stirring is continued for at least 60 minutes to obtain a bonding layer glue solution.

[0025] Preferably, step S2 includes the following steps:

[0026] Place the first resin and the second resin in a container, add an oil phase organic solvent, heat to 50-80°C, ensure condensation reflux, stir at 100-1000RPM until completely dissolved, cool to 30-40°C and add the second additive and the third additive, keep stirring for more than 10 minutes to obtain a back adhesive layer.

[0027] Compared with the prior art, the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries of the present invention and the preparation method thereof are developed based on adhesive modification of elastomers such as POE and ethylene-propylene rubber. By making it have bonding ability, the amount of hydrogenated styrene block copolymer used is greatly reduced. At the same time, since it is an elastomer modification, the film has excellent mechanical properties and can effectively withstand various mechanical impacts.

[0028] On this basis, the present invention makes the adhesive into an emulsion adhesive, which reduces the amount of organic solvent used to improve environmental friendliness on the one hand, and uses conventional electrolyte-intolerant adhesives as a supplement in the aqueous phase on the other hand. After actual bonding use, the conventional de-sticking adhesive gradually inactivates to form a cheese-like small-pore adhesive film, which can effectively alleviate the impact force and stress on the tabs in the event of falling, tumbling, friction, etc., and protect the tabs and battery cells from damage.

Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries of the present invention;

[0030] Figure 2 This is a physical picture of the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries of the present invention;

[0031] Figure 3 The peeling force curve of the back adhesive layer and the electrolyte resistance peeling force curve of Example 1 of the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium ion batteries of the present invention;

[0032] Figure 4 The peeling force curve of the adhesive layer and the electrolyte resistance peeling force curve of Example 1 of the impact-resistant propylene-based double-sided hot-melt tape for lithium-ion batteries of the present invention. [Specific implementation method]

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0035] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0036] See also Figures 1 to 4 The impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries of the present invention comprises an adhesive layer 10, a back adhesive layer 20 and a base tape 30. The adhesive layer 10 and the back adhesive layer 20 are respectively arranged on both sides of the base tape 30. The adhesive layer 10 is used for bonding the battery cell, and the back adhesive layer 20 is used for bonding the aluminum-plastic film surface.

[0037] The bonding layer 10 includes a bonding layer adhesive, and the bonding layer adhesive includes a bonding layer organic component, a bonding layer solvent, and a bonding layer additive.

[0038] The adhesive of the bonding layer mainly presents an oil-in-water phase, and the organic components of the bonding layer include a first resin, a second resin and a third resin, wherein the first resin accounts for 60-90% of the total organic components of the bonding layer, the second resin accounts for 10-30% of the total organic components of the bonding layer, and the third resin accounts for 5-15% of the total organic components of the bonding layer.

[0039] The back adhesive layer 20 includes a back adhesive layer adhesive, and the back adhesive layer adhesive includes a back adhesive layer organic component, a back adhesive layer solvent, and a back adhesive layer additive.

[0040] The adhesive of the back adhesive layer mainly presents a water-in-oil phase, and the organic components of the back adhesive layer include a first resin and a second resin, wherein the first resin accounts for 80-100% of the total organic components of the back adhesive layer, and the second resin accounts for 0-10% of the total organic components of the back adhesive layer.

[0041] The first resin is an electrolyte resistant resin, mainly acid-modified polyolefins, including POE (polyolefin elastomer), EPDM (ethylene propylene diene monomer rubber), EPM (ethylene propylene diene monomer rubber) and the like modified by small molecule acid anhydrides such as maleic anhydride, acetic anhydride and benzoic anhydride. The first resin is required to be soluble in cyclohexane or toluene system, with an acid anhydride grafting rate in the range of 1-8%, and be in a highly elastic state at room temperature (25°C). In the adhesive layer 10, the first resin accounts for 60-90% of the total resin, and in the back adhesive layer 20, the first resin accounts for 80-100% of the total resin.

[0042] The second resin is a resin for initial adhesion, mainly hydrogenated petroleum resin, hydrogenated styrene block copolymer, acrylate and other conventional pressure-sensitive tape resin materials. The second resin is required to be soluble in hydrocarbon organic systems such as cyclohexane, insoluble or slightly soluble in aqueous systems, and no other properties are required. It only provides initial adhesion. The second resin accounts for 10-30% of the total resin in the adhesive layer 10, and the second resin accounts for 0-10% of the total resin in the back adhesive layer 20.

[0043] The third resin is a porous resin, mainly a water-soluble resin such as polyvinyl alcohol, modified starch, polyacrylamide, etc. The third resin is required to have good solubility in water and can also be dissolved in the electrolyte ester resin, and the dissolved product does not have a negative impact on the SEI film and electrode of the battery. The third resin is not used in the back adhesive layer 20, and the third resin accounts for 5-15% of the total resin in the adhesive layer 10.

[0044] The total content of the first resin, the second resin and the third resin in the adhesive is in the range of 10-20%.

[0045] The adhesive layer solvent includes an oil phase organic solvent and an aqueous phase solvent, and the back adhesive layer solvent includes an oil phase organic solvent.

[0046] The oil phase organic solvent is mainly hydrocarbon non-polar or low-polar organic solvents such as cyclohexane, methylcyclohexane, toluene, xylene, cyclopentane, etc., accounting for 85-95% of the solvent system and 100% of the content in the back adhesive layer solvent.

[0047] The aqueous phase solvent is mainly distilled water, accounting for 5-15% of the solvent system, and 0-5% of ethanol can be added as a phase dispersion aid according to the dispersion requirements. It is not used in the back adhesive layer solvent.

[0048] The adhesive layer additives include a first additive, a second additive and a third additive, and the back adhesive layer additives include a second additive and a third additive.

[0049] The first additive is an emulsifier, mainly hexadecyl ammonium sulfate, sodium octadecyl sulfate, glyceryl monostearate or other commercially available water-in-oil emulsifiers, and the added amount is 1%-3% of the total amount of the resin. The first additive is not used in the back adhesive layer additive.

[0050] The second additive is an acid-base balancer, mainly lithium hydroxide and other lithium-containing alkali salts. Due to the presence of acidic groups in the electrolyte-resistant resin, an acid-base balancer needs to be added to avoid emulsion instability. At the same time, in order to avoid the influence of residues on the battery cell, battery-grade lithium-containing alkali salts need to be used. The specific amount of addition is determined according to the pH value to ensure that the pH value is in the range of 6-7.

[0051] The third additive is an adhesion promoter, mainly epoxy resin, which helps to slightly crosslink each resin and increase the molecular weight. The addition amount is 1-5% of the anhydride group under the grafting rate based on 0.42eq / 100g as the base (for example: 1000g electrolyte resistant resin, grafting rate 3%, then the epoxy addition amount is 1000*0.03*0.01~0.05=0.3~1.5g, if 0.84eq / 100g resin is used, it is 0.15-0.75g).

[0052] The base tape 30 is a 6-25 μm thick base tape made of polyolefin film materials such as PE, PP, and random copolymer PP. The surface is corona treated to make its dyne value in the range of 30-42. Using a coating process, the adhesive layer adhesive and the back adhesive layer adhesive are double-sidedly coated on the base tape 30, wherein the adhesive layer 10 is 10-25 μm thick after drying, and the back adhesive layer 20 is 2-10 μm thick after drying. It is recommended to pass through a suspension drying tunnel or other drying tunnels that meet the cleanliness requirements for drying, and then composite the release paper 40. After winding and slitting, the double-sided hot-melt adhesive tape of the present invention is obtained.

[0053] The method for preparing the impact-resistant propylene-based double-sided hot melt adhesive for lithium-ion batteries of the present invention comprises the following steps:

[0054] Step S1, preparing the bonding cell surface, that is, preparing the adhesive solution for the bonding layer 10.

[0055] The step S1 includes the following steps:

[0056] Step S11, place the first resin and the second resin in a container, add the corresponding oil phase organic solvent, heat to 50-80°C, ensure condensation reflux, stir at 100-1000RPM until completely dissolved, cool to 30-40°C and keep constant temperature, add the second additive and the third additive, and keep stirring for more than 10 minutes. After this step, an oil phase solution is obtained.

[0057] Step S12, place the third resin in a container, add the corresponding distilled water and ethanol mixed solvent, heat to 30-40°C, ensure condensation and reflux, stir at 100-1000RPM until completely dissolved and set aside. After this step, an aqueous phase solution is obtained.

[0058] Step S13, (optional step) place the first additive in a container, add the remaining oil phase solvent in step S11, raise the temperature to 30-40°C, ensure condensation and reflux, stir at 100-1000RPM until completely dissolved and set aside.

[0059] Step S14, the first additive (or diluent) and the aqueous solution are added dropwise to the oil phase solution respectively, the addition time should be guaranteed to be 40-80 minutes, and the first additive and the aqueous solution should be added dropwise as much as possible at the same time. During the addition, the system temperature is controlled at 30-40°C, and the rotation speed is controlled at 100-1000RPM.

[0060] Step S15, after the dropwise addition is completed, the temperature is naturally lowered, and the rotation speed is increased to 500-3000 RPM, and stirring is continued for at least 60 minutes. After this step, the adhesive solution of the bonding layer 10 is obtained.

[0061] The adhesive layer 10 obtained by the above method has a shelf life of 48 hours, and the shelf life starts from the time when stirring is stopped. After the adhesive layer 10 is prepared, the double-sided tape coating should be completed as soon as possible. If storage is required, it is recommended to be sealed and stored at 15-35°C, and repeat step S15 before use when activated.

[0062] Step S2, preparing the bonding aluminum-plastic film surface, that is, preparing the adhesive solution for the back adhesive layer 20.

[0063] The step S2 includes the following steps:

[0064] Place the first resin and the second resin in a container, add the corresponding oil phase organic solvent, heat up to 50-80°C, ensure condensation reflux, stir at 100-1000RPM until completely dissolved, cool to 30-40°C and add the second additive and the third additive, keep stirring for more than 10 minutes, and obtain the back adhesive layer 20 adhesive solution through this step.

[0065] The adhesive solution for back adhesive layer 20 obtained by the above method has a shelf life of 7 days, and the shelf life starts from the time when stirring is stopped. The storage condition is to store in a sealed state at 15-35°C.

[0066] Step S3, preparing double-sided hot melt adhesive.

[0067] The step S3 includes the following steps:

[0068] Step S31 , selecting a suitable base tape 30 , coating the adhesive layer 10 and the adhesive layer 20 with a micro-concave coating method, separating them with release paper 40 and rolling them up.

[0069] Step S32, selecting a suitable wide band for slitting to obtain a double-sided hot-melt adhesive tape.

[0070] The impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries of the present invention and its preparation method are described below in conjunction with specific embodiments.

[0071] Embodiment 1

[0072] The specific composition is as follows, with a total thickness of 32 μm.

[0073]

[0074] Preparation method: Take 12kg / 5kg as an example.

[0075] 1. Prepare the bonding surface of the battery cell (bonding layer glue) - 12kg

[0076] Step 1, 1.92 kg of the first resin and 360 g of the second resin are placed in a 15L flask, 8.00 kg of cyclohexane is added thereto, stirring is started, the speed is set to 200 RPM, and the temperature is raised to 65° C. After stirring until completely dissolved (no obvious particles are suspended at the bottom of the flask and in the solution), the temperature is set to drop to 40° C., 6.5 g of the third additive and the corresponding second additive (24.7 g in this embodiment) are added to the container, the pH value is controlled to 6.7, and stirring is maintained for standby.

[0077] Step 2: Place 120 g of the third resin in a 1.5 L flask, add 960 g of distilled water, start stirring, set the speed to 100 RPM, and raise the temperature to 40° C. After stirring until completely dissolved, transfer to a constant pressure funnel of the same volume for standby use.

[0078] Step 3, 36 g of the first additive was placed in a 1 L flask, 640 g of cyclohexane was added thereto, stirring was started, the speed was set to 100 RPM, and the temperature was raised to 40° C. After stirring until completely dissolved, the first additive was transferred to a constant pressure funnel of the same volume for later use.

[0079] Step 4, the mixed solution obtained in steps 2 and 3 is gradually added dropwise to the oil phase solution prepared in step 1 using a constant pressure funnel. The addition is expected to take 60 minutes (in this embodiment, the first additive takes 53 minutes and the aqueous solution takes 62 minutes). During the addition, the rotation speed is increased to 800 RPM.

[0080] Step 5. After the addition is completed, turn off the heating and wait for natural cooling, while increasing the speed to 1500RPM.

[0081] Step 6, after the temperature returns to room temperature, the adhesive layer glue solution is obtained, and the shelf life of the glue solution is 48 hours, which is calculated by stopping stirring. If the shelf life is exceeded, step 5 needs to be repeated to confirm that the emulsion state is stable.

[0082] 2. Preparation of bonding aluminum-plastic film surface (back adhesive layer glue) - 5kg

[0083] Step 1, 450g of the first resin and 50g of the second resin are placed in a 10L flask, 4.00kg of cyclohexane is added thereto, stirring is started, the speed is set to 150RPM, and the temperature is raised to 60°C. After stirring until completely dissolved, the temperature is set to drop to 40°C, 1.5g of the third additive and the corresponding second additive (10g in this embodiment) are added to the container, the pH value is controlled to 6.4, and stirring is maintained for standby.

[0084] Step 2: The back adhesive obtained by this method has a shelf life of 7 days, and the shelf life starts from the time when stirring stops. The storage condition is to store in a sealed container at 15-35°C. If the shelf life is exceeded, it needs to be stirred again for use.

[0085] 3. Make double-sided hot melt adhesive

[0086] Step 1, select the biaxially oriented polypropylene film resin of TPC company, use the biaxially oriented casting machine to cast, and obtain a BOPP film with a width of 1040mm. After corona treatment, the dyne value of both sides is 34.

[0087] Step 2, using a micro-concave coating line, with a coating width of 1000 mm, setting the coating amount on the adhesive surface to 54 g (20%) and the coating amount on the back adhesive surface to 45 g (10%), coating the BOPP film and pressing the release paper before winding. The resin amount on the adhesive surface was measured to be 10.8 g, the thickness was 11.7 μm, and the resin amount on the back adhesive surface was 4.5 g, the thickness was 4.8 μm.

[0088] Step 3, cut small rolls according to usage requirements to obtain double-sided hot-melt tape.

[0089] 4. Laboratory testing and data statistics.

[0090] The test method mainly refers to GB / T2792, and the test data are as follows:

[0091] Example 1 Test data unit Peel force per mm Test data recording value (10 mm width) Initial adhesion peel strength (back adhesive surface) N ≈0 No detection Initial adhesion peel strength (adhesive surface) N 0.32 3.1 / 3.3 / 3.5 / 3.1 / 3.1 Hot press peel strength (adhesive back surface) N 0.49 5.1 / 4.7 / 4.8 / 4.7 / 5.3 Hot press peel strength (bonding surface) N 0.61 6.4 / 6.1 / 5.9 / 5.9 / 5.8 Electrolyte peel strength (back adhesive surface) N 0.41 4.0 / 4.3 / 4.0 / 4.1 / 4.1 Electrolyte peel strength (bonding surface) N 0.54 5.1 / 5.3 / 5.2 / 5.4 / 6.0

[0092] from Figure 2 It can be seen that the bonding surface has pore-like dispersion.

[0093] Embodiment 2

[0094]

[0095] Embodiment 3

[0096]

[0097]

[0098] Compared with the prior art, the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries of the present invention and the preparation method thereof are developed based on adhesive modification of elastomers such as POE and ethylene-propylene rubber. By making it have bonding ability, the amount of hydrogenated styrene block copolymer used is greatly reduced. At the same time, since it is an elastomer modification, the film has excellent mechanical properties and can effectively withstand various mechanical impacts.

[0099] On this basis, the present invention makes the adhesive into an emulsion adhesive, which reduces the amount of organic solvent used to improve environmental friendliness on the one hand, and uses conventional electrolyte-intolerant adhesives as a supplement in the aqueous phase on the other hand. After actual bonding use, the conventional de-sticking adhesive gradually inactivates to form a cheese-like small-pore adhesive film, which can effectively alleviate the impact force and stress on the tabs in the event of falling, tumbling, friction, etc., and protect the tabs and battery cells from damage.

[0100] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included in the patent protection scope of the present invention.

Claims

1. An impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries, characterized in that: It includes an adhesive layer, a back adhesive layer and a base tape, wherein the adhesive layer and the back adhesive layer are respectively arranged on both sides of the base tape, the adhesive layer is used to bond the battery core, and the back adhesive layer is used to bond the aluminum-plastic film surface; The bonding layer includes a bonding layer adhesive, and the bonding layer adhesive includes a bonding layer organic component, a bonding layer solvent and a bonding layer additive.

2. The impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 1, characterized in that: The back adhesive layer comprises a back adhesive layer adhesive, and the back adhesive layer adhesive comprises a back adhesive layer organic component, a back adhesive layer solvent and a back adhesive layer additive.

3. The impact-resistant acrylic double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 1, characterized in that: The adhesive of the bonding layer presents an oil-in-water phase, and the organic components of the bonding layer include a first resin, a second resin and a third resin, wherein the first resin accounts for 60-90% of the total organic components of the bonding layer, the second resin accounts for 10-30% of the total organic components of the bonding layer, and the third resin accounts for 5-15% of the total organic components of the bonding layer.

4. The impact-resistant acrylic double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 2, characterized in that: The adhesive of the back adhesive layer presents a water-in-oil phase, and the organic components of the back adhesive layer include a first resin and a second resin, wherein the first resin accounts for 80-100% of the total organic components of the back adhesive layer, and the second resin accounts for 0-10% of the total organic components of the back adhesive layer.

5. The impact-resistant acrylic double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 1, characterized in that: The first resin is an electrolyte resistant resin, the second resin is an initial adhesion providing resin, and the third resin is a pore resin.

6. The impact-resistant acrylic double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 2, characterized in that: The adhesive layer solvent includes an oil phase organic solvent and an aqueous phase solvent, and the back adhesive layer solvent includes an oil phase organic solvent; the oil phase organic solvent is a hydrocarbon non-polar or low-polar organic solvent, and the aqueous phase solvent is distilled water.

7. The impact-resistant acrylic double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 2, characterized in that: The adhesive layer additives include a first additive, a second additive and a third additive, and the back adhesive layer additives include a second additive and a third additive; the first additive is an emulsifier, the second additive is an acid-base balancer, and the third additive is an adhesion promoter.

8. A method for preparing an impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries, characterized in that: The steps include: Step S1, preparing adhesive layer glue; Step S2, preparing adhesive solution for the back adhesive layer; Step S3, preparing double-sided hot melt adhesive.

9. The method for preparing the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 8, characterized in that: The step S1 includes the following steps: Step S11, placing the first resin and the second resin in a container, adding an oil phase organic solvent, heating to 50-80° C., ensuring condensation and reflux, stirring at 100-1000 RPM until completely dissolved, cooling to a constant temperature of 30-40° C. and adding the second additive and the third additive, and stirring for more than 10 minutes to obtain an oil phase solution; Step S12, placing the third resin in a container, adding a mixed solvent of distilled water and ethanol, heating to 30-40°C, ensuring condensation and reflux, stirring at a speed of 100-1000 RPM until completely dissolved and set aside to obtain an aqueous phase solution. Step S13, placing the first additive in a container, adding the remaining oil phase solvent in step S11, heating to 30-40° C., ensuring condensation and reflux, stirring at 100-1000 RPM until completely dissolved and set aside; Step S14, respectively adding the first additive and the aqueous phase solution to the oil phase solution, the adding time should be 40-80 minutes, and the first additive and the aqueous phase solution should be added at the same time, the system temperature is controlled at 30-40°C, and the rotation speed is controlled at 100-1000RPM during the adding; Step S15, after the dropwise addition is completed, the temperature is naturally lowered, and the rotation speed is increased to 500-3000 RPM, and stirring is continued for at least 60 minutes to obtain a bonding layer glue solution.

10. The method for preparing the impact-resistant propylene-based double-sided hot-melt adhesive tape for lithium-ion batteries according to claim 8, characterized in that: The step S2 includes the following steps: Place the first resin and the second resin in a container, add an oil phase organic solvent, heat to 50-80°C, ensure condensation reflux, stir at 100-1000RPM until completely dissolved, cool to 30-40°C and add the second additive and the third additive, keep stirring for more than 10 minutes to obtain a back adhesive layer.

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