Aluminum-plastic film binder for soft package of lithium battery and preparation method of aluminum-plastic film binder

Abstract

The invention relates to the technical field of adhesives, in particular to an aluminum-plastic film adhesive for soft package of a lithium battery and a preparation method of the aluminum-plastic film adhesive, and the aluminum-plastic film adhesive comprises the following components in parts by mass: 100 parts of polyolefin resin, 1-5 parts of borate, 0.5-1 part of borane, 0.5-1 part of boric acid, 0.5-2 parts of allyl diepoxypropyl tripolyisocyanate and 0.1-0.5 part of peroxide initiator. Allyl diepoxypropyl tripolyisocyanate can greatly improve the bonding force of polyolefin resin with PP (polypropylene) and aluminum foil, double bonds of the allyl diepoxypropyl tripolyisocyanate are subjected to grafting reaction with polyolefin under the initiation of an initiator, and the allyl diepoxypropyl tripolyisocyanate is grafted to the polyolefin, so that the adhesion force between the polyolefin resin and the PP and the aluminum foil is improved, and the adhesion force between the polyolefin resin and the PP and the aluminum foil is improved. Meanwhile, epoxy bonds react with boric acid, boric acid ester and borane, and carbonyl and N atoms on allyl diepoxypropyl tripolyisocyanate molecules both improve the polarity of polyolefin, so that the allyl diepoxypropyl tripolyisocyanate molecules can generate weak bonding action with boron atoms and aluminum foil.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, in particular to an aluminum-plastic film adhesive for lithium battery soft packages and a preparation method thereof. Background Art

[0002] The aluminum-plastic film used for lithium battery soft packs is composed of PP, nylon, and aluminum foil. The bonding of PP and aluminum foil is very difficult, mainly because 1) the surface of aluminum foil is smooth and not easy to adhere to objects; the surface of PP is hydrophobic and has low surface energy, which is also difficult to bond; 2) PP has extremely low surface tension and low melting point, making it difficult to combine with other materials.

[0003] In order to achieve effective bonding between PP and aluminum foil, the following methods can be used: 1. Surface treatment: 1) Mechanical grinding: By grinding the PP surface to increase its roughness, the bonding effect is improved. However, this method may not be suitable for all situations and may damage the surface of the material.

[0004] 2) Primer treatment: Apply a layer of primer on the surface of PP, which can produce good bonding effect with both PP and aluminum foil. This method is relatively simple and effective, but it requires the selection of a suitable primer.

[0005] 3) Plasma treatment: Use the high energy of plasma to modify the PP surface and increase its surface energy, thereby enhancing the bonding effect. This method is suitable for large-scale production, but the cost is relatively high.

[0006] 2. Heating and pressing: The PP and aluminum foil coated with glue are glued together according to the bonding position, and heated and pressed to make them tightly bonded together. The heating temperature should be determined according to the different PP and aluminum foils, and should not be too high or too low to avoid affecting the performance of the product or causing loose bonding.

[0007] The adhesives currently used in the industry mainly come from East Asia Synthetics of Japan. With the development of the industry, the bonding strength and electrolyte resistance performance need to be further improved. Summary of the invention

[0008] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an aluminum-plastic film adhesive for lithium battery soft packs and a preparation method thereof.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: An aluminum-plastic film adhesive for lithium battery soft pack, the composition by weight is as follows: 100 parts of polyolefin resin, 1-5 parts of boric acid ester, Borane 0.5-1 part, 0.5-1 part of boric acid, Allyl diepoxypropyl isocyanate 0.5-2 parts, Peroxide initiator 0.1-0.5 parts.

[0010] Furthermore, the polyolefin resin is selected from one of PP, PE, TPO and POE.

[0011] Furthermore, the borate ester is selected from one or more of trimethyl borate, triethyl borate, tributyl borate, triisopropyl borate, and triethanolamine borate.

[0012] Furthermore, the borane is tributylborane.

[0013] Furthermore, the peroxide initiator is selected from at least one of a bis-25 initiator and a TBEC initiator, wherein the bis-25 initiator is also known as DBPH (2,5-dimethyl-2,5-peroxy)hexane).

[0014] A method for preparing an aluminum-plastic film adhesive for a lithium battery soft package, the preparation method being as follows: The binder is obtained by mixing a polyolefin resin, a boric acid ester, borane, boric acid, allyl diglycidyl isocyanurate and a peroxide initiator and extruding and granulating the mixture at 150° C.

[0015] The beneficial effects of the technical solution of the present invention are: The allyl diepoxypropyl isocyanate in the present invention can greatly improve the adhesion between polyolefin resin and PP and aluminum foil. Under the initiation of an initiator, the double bonds of the allyl diepoxypropyl isocyanate undergo a grafting reaction with the polyolefin, and the allyl diepoxypropyl isocyanate is grafted onto the polyolefin. At the same time, the epoxy bond reacts with boric acid, boric ester and borane. The carbonyl group and N atom on the allyl diepoxypropyl isocyanate molecule both improve the polarity of the polyolefin, and can produce a weak bond with the boron atom and the aluminum foil. The allyl diepoxypropyl isocyanate plays a bridge role between the polyolefin and the borane. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with specific implementation methods and description.

[0017] The polyolefin resin in the present invention is PE resin Sumitomo CB1001.

[0018] An aluminum-plastic film adhesive for lithium battery soft pack, the composition by weight is as follows: 100 parts of polyolefin resin, 1-5 parts of boric acid ester, Borane 0.5-1 part, 0.5-1 part of boric acid, Allyl diepoxypropyl isocyanate 0.5-2 parts, Peroxide initiator 0.1-0.5 parts.

[0019] Allyl diepoxypropyl isocyanate, namely T1, has the structural formula:

[0020] Among them, the polyolefin resin is selected from one of PP, PE, TPO and POE.

[0021] Wherein, the boric acid ester is selected from one or more of trimethyl borate, triethyl borate, tributyl borate, triisopropyl borate and triethanolamine borate.

[0022] Wherein, the borane is tributylborane.

[0023] The peroxide initiator is selected from at least one of a bis-25 initiator and a TBEC initiator, wherein the bis-25 initiator is also known as DBPH (2,5-dimethyl-2,5-peroxy)hexane).

[0024] The preparation method of the aluminum-plastic film adhesive for lithium battery soft pack in the present invention is as follows: polyolefin resin, boric acid ester, borane, boric acid, allyl diepoxypropyl isocyanate and peroxide initiator are mixed and extruded and granulated at 150° C. to obtain the adhesive. Example

[0025] Use PE resin Sumitomo CB1001, 100 parts, double 25 initiator 0.3 parts, the rest as shown in the table below, extrusion granulation at 150℃ extruder, dissolve the particles with cyclohexane, apply on PP, dry, heat-bond with PP at 100℃, tear at 180℃ on a tensile machine to obtain the adhesion of PP; apply on aluminum foil, dry, heat-bond with aluminum foil at 100℃, tear at 180℃ on a tensile machine to obtain the adhesion of aluminum foil; apply on PP, dry, heat-bond with aluminum foil at 100℃, soak in electrolyte for 48 hours, observe whether aluminum foil and PP are separated. See Table 1 for details.

[0026] Table 1 As can be seen from Table 1, triethanolamine borate can improve the adhesion between resin and PP and aluminum foil. The reason is that under heating conditions, the ester bond of triethanolamine borate can remove the ammonia molecule to generate a transition state of monomolecular boric acid, which reacts with polyolefins and aluminum foil to combine together. Tributylborane can also improve the adhesion with PP and aluminum foil, but the amplitude is smaller. The reason is that tributylborane can generate a transition state of monomolecular boric acid when it meets water, which further reacts with PP and aluminum foil. Since water is required and tributylborane has a boiling point of 200°C, it is easy to volatilize and lose, so the effect is limited. Boric acid can greatly improve the adhesion with aluminum foil, but it cannot improve the adhesion with PP. The main reason is that boric acid is a solid, which is a state of aggregation of a large number of boric acid molecules. It is difficult to react evenly with PP and polyolefins, but it can concentrate acid corrosion on the surface of aluminum foil, which has a better effect. T1 can greatly improve the adhesion between polyolefin resin and PP and aluminum foil. The reason is that under the initiator, the double bond of T1 undergoes a grafting reaction with polyolefin, and T1 is grafted onto polyolefin. At the same time, the epoxy bond reacts with boric acid, boric ester, and borane. The carbonyl group and N atom on the T1 molecule increase the polarity of polyolefin, and can produce weak bonds with boron atoms and aluminum foil. T1 plays a bridge role between polyolefin and borane. However, excessive T1 will increase the polarity of polyolefin, and at the same time, the unreacted T1 small molecules will increase, affecting the bonding effect and electrolyte resistance. 0.5-2 parts is appropriate.

[0027] Example 2 Use PE resin Sumitomo CB1001, 100 parts, double 25 initiator 0.3 parts, the rest as shown in the table below, extrusion granulation at 150℃ extruder, dissolve the particles with cyclohexane, apply on PP, dry, heat-bond with PP at 100℃, tear at 180℃ on a tensile machine to obtain the adhesion of PP; apply on aluminum foil, dry, heat-bond with aluminum foil at 100℃, tear at 180℃ on a tensile machine to obtain the adhesion of aluminum foil; apply on PP, dry, heat-bond with aluminum foil at 100℃, soak in electrolyte for 48 hours, observe whether aluminum foil and PP are separated. See Table 2 for details.

[0028] Table 2 Example

[0029] Use PE resin Sumitomo CB1001, 100 parts, double 25 initiator 0.3 parts, the rest as shown in the table below, extrusion granulation at 150℃ extruder, dissolve the particles with cyclohexane, apply on PP, dry, heat-bond with PP at 100℃, tear at 180℃ on a tensile machine to obtain the adhesion of PP; apply on aluminum foil, dry, heat-bond with aluminum foil at 100℃, tear at 180℃ on a tensile machine to obtain the adhesion of aluminum foil; apply on PP, dry, heat-bond with aluminum foil at 100℃, soak in electrolyte for 48 hours, observe whether aluminum foil and PP are separated. See Table 3 for details.

[0030] Table 3 In addition, it should be understood that although this specification is described according to implementation methods, not every implementation method contains only one independent claim scheme. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An aluminum-plastic film adhesive for lithium battery soft pack, characterized in that: Its mass composition is as follows: 100 parts of polyolefin resin, 1-5 parts of boric acid ester, Borane 0.5-1 part, 0.5-1 part of boric acid, Allyl diepoxypropyl isocyanate 0.5-2 parts, Peroxide initiator 0.1-0.5 parts.

2. The aluminum-plastic film adhesive for lithium battery soft package according to claim 1, characterized in that: The polyolefin resin is selected from one of PP, PE, TPO and POE.

3. The aluminum-plastic film adhesive for lithium battery soft package according to claim 1, characterized in that: The borate ester is selected from one or more of trimethyl borate, triethyl borate, tributyl borate, triisopropyl borate and triethanolamine borate.

4. The aluminum-plastic film adhesive for lithium battery soft package according to claim 1, characterized in that: The borane is tributylborane.

5. The aluminum-plastic film adhesive for lithium battery soft package according to claim 1, characterized in that: The peroxide initiator is selected from one of Bis-25 initiator and TBEC initiator.

6. A method for preparing an aluminum-plastic film adhesive for a lithium battery soft package according to any one of claims 1 to 5, characterized in that: The preparation method is as follows: The binder is obtained by mixing a polyolefin resin, a boric acid ester, borane, boric acid, allyl diglycidyl isocyanurate and a peroxide initiator and extruding and granulating the mixture at 150° C.

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