阅读说明：本技术 一种锂电池铝塑膜外层用胶及其合成方法 (Glue for outer layer of lithium battery aluminum plastic film and synthetic method thereof ) 是由 王玉灿 付洪娥 李致轩 王新 魏田 鲁琴 刘博� 于 2020-12-21 设计创作，主要内容包括：本发明属于高分子材料合成领域,具体涉及一种锂电池铝塑膜外层用胶及其合成方法。将脂肪族二元醇和脂肪族、芳香族二元酸混合进行酯化反应,待产物中羟值：酸值在8～35:1,加入酸酐进行酰化,而后在环氧化合物和催化剂作用下进行开环反应,获得规整的、分子链中各功能结构片段分布更为均匀的、分子量在20000～50000的高分子聚合物。本发明反应条件温和,产品品质、应用性能稳定,产品强度和柔韧性能好,抗拉伸性能优良,具有很好的耐水解性、粘结性和抗冲击性能。本发明制备的外层用胶,可满足锂电池铝塑膜的应用性能要求。(The invention belongs to the field of synthesis of high polymer materials, and particularly relates to a glue for an outer layer of an aluminum plastic film of a lithium battery and a synthesis method thereof. Mixing aliphatic diol with aliphatic and aromatic dibasic acids for esterification, and obtaining the product with a hydroxyl value: and adding acid anhydride to acidify the polymer with the acid value of 8-35: 1, and then performing ring-opening reaction under the action of an epoxy compound and a catalyst to obtain a regular high-molecular polymer with more uniform distribution of functional structural fragments in a molecular chain and the molecular weight of 20000-50000. The invention has the advantages of mild reaction condition, stable product quality and application performance, good product strength and flexibility, excellent tensile resistance, and good hydrolysis resistance, cohesiveness and impact resistance. The outer layer adhesive prepared by the invention can meet the application performance requirements of the aluminum plastic film of the lithium battery.)

1. A synthetic method of a glue polymer for an outer layer of an aluminum plastic film of a lithium battery is characterized by comprising the following steps: mixing aliphatic diol with aliphatic and aromatic dibasic acids for esterification, and obtaining the product with a hydroxyl value: and adding acid anhydride to acidify the polymer with the acid value of 8-35: 1, and then performing ring-opening reaction under the action of an epoxy compound and a catalyst to obtain a regular high-molecular polymer with more uniform distribution of functional structural fragments in a molecular chain and the molecular weight of 20000-50000.

2. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 1, which is characterized in that: mixing aliphatic diol with aliphatic and aromatic dibasic acids, heating to 120-180 ℃ at a speed of 20-50 ℃/h under the action of an antioxidant, carrying out an esterification reaction, carrying out a heat preservation reaction for 1-4 h, then adding anhydride, continuing the reaction for 2-4 h at 180-220 ℃, then controlling the temperature to 80-150 ℃, adding an epoxy compound and a catalyst, and carrying out a ring-opening reaction for 1-5 h at an absolute pressure of 5-40 KPa, thereby obtaining a regular high molecular polymer with more uniform distribution of functional structure segments in a molecular chain and a molecular weight of 20000-50000.

3. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 2, which is characterized in that: after the high molecular polymer is obtained, the reaction system is restored to normal pressure, the solvent is added until the temperature is reduced to the reflux temperature of the solvent, so that the solid materials are completely dissolved until the mass percentage concentration of the polymer in the system is 25-40%.

4. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 2, which is characterized in that: the molar ratio of the aliphatic dibasic alcohol to the aliphatic dibasic acid to the aromatic dibasic acid to the acid anhydride to the epoxy compound is 10-20: 5-10: 4-12: 1: 0.05-0.25.

5. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 1 or 2, which comprises the following steps:

the aliphatic dihydric alcohol is C₂-C₁₂Linear or branched diols of (1); the aliphatic dibasic acid is C₃-C₁₀The fatty dibasic acid of (1); the aromatic dibasic acid is terephthalic acid or isophthalic acid; the acid anhydride is phthalic anhydride or maleic anhydride; the epoxy compound is bisphenol A type, bisphenol F type, bisphenol S type epoxy resin, 1, 4-butanediol diglycidyl ether, glycidyl ether and other epoxy compounds.

6. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 1 or 2, which comprises the following steps: the antioxidant is selected from p-tert-butylphenol, 2, 4-dimethyl-6-tert-butylphenol or tetra (3, 5-di-tert-butyl-4-hydroxyhydrocinnamic acid) pentaerythritol ester, triphenyl phosphite and the like, and the addition amount of the antioxidant is 0.02-0.2% of the mass of the reaction product; the catalyst is selected from zinc isooctanoate, dibutyltin oxide or antimony oxide, and the adding amount of the catalyst is 0.03-0.3% of the mass of the aromatic dibasic acid.

7. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 1 or 2, which comprises the following steps: the ring-opening catalyst is tertiary amine catalyst such as triethylamine, triethanolamine, dimethylethanolamine and the like, and the addition amount of the ring-opening catalyst is 0.5-4% of the mass of the epoxy compound.

8. The method for synthesizing the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 1 or 2, which comprises the following steps: the solvent is a solvent that can dissolve the polyester polyol.

9. The synthesis method of claim 1, wherein the gel polymer for the outer layer of the aluminum plastic film of the lithium battery is obtained by the synthesis method, and is characterized in that: the method of claim 1, wherein the hydroxyl number is controlled by: the acid value is 8-35: 1, and the obtained lithium battery aluminum plastic film outer layer adhesive polymer is regular, more uniform in distribution of functional structure fragments in a molecular chain, and 20000-50000 in molecular weight.

10. The use of the gel polymer for the outer layer of the aluminum plastic film of the lithium battery as claimed in claim 1, wherein: the polymer is mixed with a curing agent through a solution dispersed by a solvent to form a glue layer.

Technical Field

The invention belongs to the field of synthesis of high polymer materials, and particularly relates to a glue for an outer layer of an aluminum plastic film of a lithium battery and a synthesis method thereof.

Background

Since the advent of lithium ion batteries, lithium ion batteries have been rapidly developed for their excellent performance. The packaging of the lithium battery core relates to the requirements of harsh physical and mechanical properties, chemical compatibility, resistance, barrier property, electrochemical reactivity and the like in the using process of the lithium battery core, and the harsh indexes are directly related to the performance of the interlayer adhesive. At present, the commercially available soft package lithium battery aluminum plastic film product is at least three layers, wherein the inner layer base material is a nontoxic polyolefin (PP, PE and the like) layer, the aluminum foil is used as a middle layer, the outer layer is a nylon film, and each layer is compounded by different types of adhesive auxiliaries.

Currently, the aluminum-plastic film of the high-end lithium battery is almost completely monopolized by Japan, and only a few suppliers exist in the world. In order to meet the requirement of domestic lithium battery enterprises for replacing imports, domestic enterprises have engaged in research and development work of aluminum-plastic composite film technology for lithium batteries, but products cannot be accepted by markets due to unstable performance. The performance of the adhesive used for bonding the materials of each layer of the domestic aluminum-plastic film cannot meet the application requirement, and the adhesive is one of the key factors that the domestic aluminum-plastic film is not popularized in a large quantity.

Because the inner and outer base materials are made of different materials (polyolefin, nylon and the like), the materials and the middle layer aluminum foil need to be bonded by different adhesives to be perfectly combined, and the application performances of aluminum plastic film stripping, deep punching, heat resistance and the like can meet the performance requirements.

CN201810805592.2 discloses an invention technology of an aluminum plastic film and a lithium battery, wherein a first adhesive layer (an outer layer of the aluminum plastic film) is formed by a polyurethane adhesive containing a polymer formed by a polyester polyol, a polyisocyanate and an epoxy resin. Wherein, the polyester polyol is prepared by adopting a conventional esterification and polycondensation method, and then is physically mixed with the polyisocyanate and the epoxy resin according to a certain proportion to obtain an adhesive product. The adhesive product prepared by the synthesis process has the advantages that the unit difference formed by the raw materials entering the main chain in the synthesis process is large, and the uniform distribution state cannot be realized, so that the condition that the bonding and hydrolysis resistance cannot reach the standard due to insufficient local bonding force occurs in the application process of the product.

CN201911243738.X discloses a polyurethane adhesive for battery flexible packaging, wherein a component A of a main agent adopts polyacrylate polyol modified by a nitrogen vinyl compound, and a curing agent adopts aromatic polyisocyanate. Wherein, the main agent A component comprises the following raw materials: ethyl acetate, butyl acrylate, methyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, nitrogen vinyl pyrrolidone and azobisisobutyronitrile. Based on the structural characteristics of the main agent, the macromolecular compound has outstanding flexibility but obviously lacks rigidity strength, and the bonding strength of the adhesive under a high-temperature environment is weaker than that of an adhesive product with an aromatic structure in a main chain.

In the chemical reaction, the epoxy group may undergo a ring-opening reaction with the carboxyl group or the hydroxyl group to obtain a pendant hydroxyl group while forming an ester bond or an ether bond. In contrast, the reactivity of the carboxyl group and the epoxy group is higher, and the reaction temperature is lower, so that the reaction speed of the two groups is difficult to control in the reaction process, and if the material distribution is not uniform, the conditions of too wide molecular weight distribution and nonuniform molecular distribution are easy to occur, and even the problem of difficult dissolution in the subsequent reaction or treatment process is caused.

Disclosure of Invention

The invention aims to provide a synthesis method of an outer layer adhesive of an aluminum plastic film of a lithium battery.

In order to achieve the purpose, the invention adopts the technical scheme that:

a synthesis method of a glue polymer for an outer layer of a lithium battery aluminum plastic film is characterized in that aliphatic dihydric alcohol and aliphatic and aromatic dibasic acid are mixed for esterification reaction, and when the hydroxyl value in a product is as follows: adding acid anhydride for acylation when the acid value is 8-35: 1, so that the molecular structure of the esterified product is more regular and the molecular weight of the intermediate product is increased; and then carrying out ring-opening reaction under the action of an epoxy compound and a catalyst to obtain a regular high-molecular polymer with more uniform distribution of functional structural fragments in a molecular chain and a molecular weight of 20000-50000.

Further, mixing aliphatic diol with aliphatic and aromatic dibasic acids, heating to 120-180 ℃ at a speed of 20-50 ℃/h to perform esterification reaction under the action of an antioxidant, and performing heat preservation reaction for 1-4 h to obtain a product with a hydroxyl value: and (3) adding acid anhydride into the mixture, continuously reacting for 2-4 hours at 180-220 ℃, controlling the temperature to 80-150 ℃, adding an epoxy compound and a catalyst, and performing ring-opening reaction for 1-5 hours under the absolute pressure of 5-40 KPa to obtain a regular high-molecular polymer with more uniform distribution of functional structure fragments in a molecular chain and the molecular weight of 20000-50000.

After the high molecular polymer is obtained, the reaction system is restored to normal pressure, the solvent is added until the temperature is reduced to the reflux temperature of the solvent, so that the solid materials are completely dissolved until the mass percentage concentration of the polymer in the system is 25-40%.

The molar ratio of the aliphatic dibasic alcohol to the aliphatic dibasic acid to the aromatic dibasic acid to the acid anhydride to the epoxy compound is 10-20: 5-10: 4-12: 1: 0.05-0.25.

And further mixing aliphatic diol and aliphatic and aromatic dibasic acids in an esterification kettle, adding an antioxidant, stirring under the protection of nitrogen, heating to 150-170 ℃ at the speed of 30-50 ℃/h for esterification reaction, and carrying out heat preservation reaction for 2-3 h, wherein the hydroxyl value in the product is as follows: and (3) adding acid anhydride, continuing to react for 2-3 h at 190-210 ℃, transferring to a pressure reduction reaction kettle, controlling the temperature to 110-130 ℃, adding an epoxy compound and a catalyst, and performing ring opening reaction for 2-3 h under the absolute pressure of 20-30 KPa to obtain the high molecular polymer with the target molecular weight of 20000-50000. Wherein the molar ratio of the aliphatic dibasic alcohol to the aliphatic dibasic acid to the aromatic dibasic acid to the acid anhydride to the epoxy compound is 13-18: 6-9: 6-10: 1: 0.1-0.2.

The aliphatic dihydric alcohol is C₂-C₁₂Linear or branched diols of (1); preferably aliphatic diols such as ethylene glycol, 1, 3-butanediol, 2-methyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-2, 4-pentanediol, 3-methyl-1, 3-butanediol, 2, 5-dimethyl-2, 5-hexanediol, 1, 2-propanediol, 1, 2-butanediol, 2, 3-butanediol, 1, 2-octanediol, 1, 2-pentanediol, 1, 2-hexanediol; further preferred is ethylene glycol, 1, 3-butanediol, 2-methyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-2, 4-pentanediol, 3-methyl-1, 3-butanediol or 2, 5-dimethyl-2, 5-hexanediol.

The aliphatic dibasic acid is C₃-C₁₀The fatty dibasic acid of (1); preferably a fatty dibasic acid such as 1, 3-malonic acid, 1, 4-succinic acid, 1, 5-glutaric acid, 1, 6-adipic acid, 1, 7-pimelic acid or 1, 8-suberic acid; further preferred is 1, 4-succinic acid, 1, 5-glutaric acid, 1, 6-adipic acid or 1, 7-pimelic acid.

The aromatic dibasic acid is terephthalic acid or isophthalic acid.

The acid anhydride is phthalic anhydride or maleic anhydride.

The epoxy compound is bisphenol A type, bisphenol F type, bisphenol S type epoxy resin, 1, 4-butanediol diglycidyl ether, glycidyl ether and other epoxy compounds.

The antioxidant is selected from p-tert-butylphenol, 2, 4-dimethyl-6-tert-butylphenol or tetra (3, 5-di-tert-butyl-4-hydroxyhydrocinnamic acid) pentaerythritol ester, triphenyl phosphite and the like, and the addition amount is 0.02-0.2% of the mass of the reaction mass, and the preferable addition amount is 0.05-0.15%; the catalyst is selected from zinc isooctanoate, dibutyltin oxide or antimony oxide, the addition amount of the zinc isooctanoate, dibutyltin oxide or antimony oxide is 0.03-0.3% of the mass of the aromatic dibasic acid, and the preferable addition amount is 0.05-0.2%. Wherein the mass of the reactant is the sum of the mass of the aliphatic dibasic alcohol, the aliphatic dibasic acid and the aromatic dibasic acid.

The ring-opening catalyst is tertiary amine catalyst such as triethylamine, triethanolamine, dimethylethanolamine and the like, and the addition amount is 0.5-4% of the mass of the epoxy compound, and the preferable addition amount is 1-3%.

The solvent is a solvent that can dissolve the polyester polyol. The solvent is selected from acetone, ethyl acetate, butyl acetate and other common solvents which can dissolve polyester polyol.

The synthesis method is used for obtaining the adhesive polymer for the outer layer of the lithium battery aluminum-plastic film, the hydroxyl value and the acid value are controlled to be 8-35: 1 according to the synthesis method, and the regular adhesive polymer for the outer layer of the lithium battery aluminum-plastic film, which is more uniform in distribution of functional structure fragments in a molecular chain and has the molecular weight of 20000-50000, is obtained.

The functional structure segments in the molecular chain are distributed more uniformly, namely, in the molecular chain of the esterified substance, two dibasic acids are arranged by the segments which are separated by dihydric alcohol and are similar to the segments of the random binary copolymer, and subsequent acylation reaction and ring-opening reaction form the high molecular chain on the basis of the esterified substance, so that compared with the ternary or even polynary random copolymer prepared by a one-time feeding method, the functional structure segments in the high molecular product prepared by the invention are distributed in a disordered manner, and the structural segments in the high molecular product are more uniform, and the process reproducibility and the product performance stability are better.

The application of the glue polymer for the outer layer of the aluminum plastic film of the lithium battery is characterized in that the glue polymer is formed by mixing a solution dispersed by a solvent and a curing agent.

According to the application of the adhesive for the outer layer of the aluminum-plastic film of the lithium battery, the polymer solution with the molecular weight of 20000-50000 and the curing agent are mixed and then coated on the surface of the matrix aluminum foil, and after drying, an adhesive layer is formed and thermally coated and bonded with the nylon layer.

Further, the obtained polymer and a commercially available polyisocyanate curing agent are mixed according to the molar ratio of the hydroxyl value of the solute to NCO of 1: 2-6, then the mixture is coated on the surface of an aluminum foil, the thickness of a dried adhesive layer is preferably 3-7 mu m, then hot covering and bonding operation of a nylon layer and adhering and curing operation of an inner layer film are carried out, and finally a qualified product of the lithium battery aluminum plastic film with the punching depth of more than 6mm, no delamination and no whitening is obtained.

The invention simultaneously esterifies the dihydric alcohol and the dibasic acid, and generates an esterified substance with average molecular weight of about 2000-3000 after esterification, and compared with a polycondensate with large molecular weight, the molecular composition and the unit distribution are relatively more balanced. The terminal hydroxyl of the esterified compound and acid anhydride are subjected to acylation reaction, and a large amount of terminal hydroxyl generated by the esterified compound is utilized, so that the molecular weight of the product is multiplied, and the macromolecular compound with a regular structure can be obtained. And finally, under the vacuum condition, the side hydroxyl group is obtained while ester bond or ether bond is generated by the ring-opening reaction of the epoxy compound and the epoxy group in the chemical reaction. In contrast, the reactivity of the carboxyl and the epoxy group is higher, and the required reaction temperature is lower, so that the reaction speed of the two groups is difficult to control in the reaction process, and if the material distribution is uneven, the conditions of too wide molecular weight distribution and uneven molecular distribution are easily caused, and even the problem that the product cannot be completely dissolved in the subsequent dissolving process is caused.

When the high molecular polymer is generated, a part of side hydroxyl groups are correspondingly generated, the high molecular product with the structure can be more balanced in mechanical property after reacting with a polyisocyanate curing agent, has certain flexibility and mechanical strength, and can form a firmer net-shaped three-dimensional structure, so that the quality and the using effect of the adhesive product are ensured, and various performance test requirements of the lithium battery aluminum plastic film are met.

The invention adopts acid anhydride to carry out acylation reaction, utilizes a large amount of terminal hydroxyl groups generated by esterification to realize the purposes of controlling the molecular weight of reactants and making the fragment structure of the reactants more regular, and then carries out ring-opening reaction with epoxy compounds under the vacuum condition, and simultaneously, in the chemical reaction, epoxy groups can carry out ring-opening reaction with carboxyl or hydroxyl to obtain side hydroxyl groups while generating ester bonds or ether bonds. In contrast, the reactivity of the carboxyl and the epoxy group is higher, and the required reaction temperature is lower, so that the reaction speed of the two groups is difficult to control in the reaction process, and if the material distribution is uneven, the conditions of too wide molecular weight distribution and uneven molecular distribution are easily caused, and even the problem that the product cannot be completely dissolved in the subsequent dissolving process is caused.

The invention has the following advantages: in the invention, the ratio of alcohol to acid in the raw materials is optimized to ensure that the hydroxyl value in the esterified material is far larger than the acid value after esterification, so that the method is favorable for smooth subsequent acylation reaction to realize the aim of continuous regular increase of molecular weight, and is also favorable for controlling the ring-opening reaction of epoxy groups and hydroxyl groups, thereby easily obtaining a high molecular product with target molecular weight and ensuring the stability and repeatability of the product synthesis process.

Meanwhile, the invention has simple and easy-to-control operation process, reasonable molecular weight distribution, stable product quality and application performance, good flexibility and tensile resistance, and has better hydrolysis resistance, caking property and impact resistance. The adhesive product prepared by the invention can completely meet the application performance requirement of the aluminum plastic film of the lithium battery on the outer layer adhesive.

Detailed Description

The present invention is further illustrated in detail by the following examples. The invention is in no way limited thereto.

Example 1

461.1g of 99 percent of 1, 2-propylene glycol, 407.3g of 99 percent of 1, 7-pimelic acid and 422.5g of 99 percent of terephthalic acid are added into a 2.5L esterification kettle, 1.3g of triphenyl phosphite and 0.4g of antimony oxide are added, the reaction system is replaced by nitrogen, the temperature is raised to 90 ℃, when solid materials are melted, stirring is started, heating to 170 ℃ of esterification reaction at the speed of 40 ℃/h, carrying out heat preservation reaction for 2h, then adding 34.6g of 99% maleic anhydride, heating to 200 ℃, continuing to react for 3 hours, transferring the reaction materials to a decompression reaction kettle, controlling the temperature to 130 ℃, adding 21.2g of bisphenol A epoxy resin E44 and 0.4g of triethanolamine, carrying out ring-opening reaction for 3 hours under the absolute pressure of 20KPa, when the stirring power of the reaction kettle reaches 63-65W, the pressure of the reaction kettle is recovered to normal pressure by nitrogen, and the reaction is stopped, so that the high molecular polymer with the molecular weight of 45000 is obtained. The material was slowly forced into a 5L dissolution kettle containing 2011g of ethyl acetate with nitrogen until the temperature reached the solvent reflux temperature and the solid material was completely dissolved to obtain a solution product with a mass percent concentration of 35%.

Example 2

Adding 429.9g of 99% of ethylene glycol, 384.0g of 99% of 1, 5-glutaric acid and 482.9g of 99% of isophthalic acid into a 2.5L esterification kettle, adding 0.9g of tetra (3, 5-di-tert-butyl-4-hydroxyhydrocinnamic acid) pentaerythritol ester and 0.7g of zinc isooctanoate, replacing a reaction system with nitrogen, heating to 90 ℃, starting stirring after solid materials are melted, heating to the esterification reaction temperature of 180 ℃ at the speed of 30 ℃/h, carrying out heat preservation reaction for 3h, adding 59.8g of 99% of phthalic anhydride, heating to 210 ℃, continuing to react for 4h, transferring the reaction materials to a reduced pressure reaction kettle, controlling the temperature to 110 ℃, adding 10.8g of 1, 4-butanediol diglycidyl ether and 0.3g of dimethylethanolamine, carrying out ring-opening reaction for 4h under the absolute pressure of 30KPa, and recovering the pressure of the reaction kettle to normal pressure by nitrogen when the stirring power of the reaction kettle reaches 63-65W, the reaction was terminated to obtain a high molecular weight polymer having a molecular weight of 38000. The material was slowly forced into a 5L dissolution vessel containing 1634g of butyl acetate with nitrogen until the temperature reached the solvent reflux temperature and the solid material was completely dissolved to give a 40% strength by mass solution product.

Comparative example 1

461.1g of 99% of 1, 2-propylene glycol, 407.3g of 99% of 1, 7-pimelic acid, 422.5g of 99% of terephthalic acid and 34.6g of 99% of maleic anhydride are added into a 2.5L esterification kettle, then 1.3g of triphenyl phosphite and 0.4g of antimony oxide are added, after a reaction system is replaced by nitrogen, the temperature is raised to 90 ℃ until solid materials are melted, stirring is started, the temperature is raised to 200 ℃ at the speed of 40 ℃/h, esterification reaction is carried out for 5h, the reaction materials are transferred to a reduced pressure reaction kettle, the temperature is controlled to 130 ℃, 21.2g of bisphenol A epoxy resin E44 and 0.4g of triethanolamine are added, ring opening reaction is carried out for 3h under the absolute pressure of 20KPa, when the stirring power of the reaction kettle reaches 63-65W, the pressure of the reaction kettle is restored to normal pressure by nitrogen, the reaction is stopped, and the high molecular weight polymer with the molecular weight of 21000 is obtained. The material was slowly forced into a 5L dissolution vessel containing 2273g of ethyl acetate with nitrogen until the temperature reached the reflux temperature of the solvent and the solid material was completely dissolved to give a 35% strength by mass solution product.

Comparative example 2

Adding 429.9g of 99% of ethylene glycol, 384.0g of 99% of 1, 5-glutaric acid, 482.9g of 99% of isophthalic acid and 59.8g of 99% of phthalic anhydride into a 2.5L esterification kettle, adding 0.9g of tetra (3, 5-di-tert-butyl-4-hydroxyhydrocinnamic acid) pentaerythritol ester and 0.7g of zinc isooctanoate, replacing the reaction system with nitrogen, heating to 90 ℃, starting stirring after solid materials are melted, heating to the esterification reaction temperature of 210 ℃ at the speed of 30 ℃/h, carrying out heat preservation reaction for 7h, transferring the reaction materials to a reduced pressure reaction kettle, controlling the temperature to 110 ℃, adding 10.8g of 1, 4-butanediol diglycidyl ether and 0.3g of dimethylethanolamine, carrying out ring-opening reaction for 4h under the absolute pressure of 30KPa, when the stirring power of the reaction kettle reaches 63-65W, recovering the pressure of the reaction kettle to normal pressure by using nitrogen, stopping the reaction, a high-molecular polymer having a molecular weight of 17000 was obtained. The material was slowly forced into a 5L dissolution kettle containing 1805g of butyl acetate with nitrogen until the temperature reached the solvent reflux temperature and the solid material was completely dissolved to obtain a solution product with a mass percent concentration of 40%.

Comparative example 3

461.1g of 99 percent of 1, 2-propylene glycol, 407.3g of 99 percent of 1, 7-pimelic acid, 422.5g of 99 percent of terephthalic acid and 34.6g of 99 percent of maleic anhydride are added into a 2.5L esterification kettle, then 1.3g of triphenyl phosphite and 0.4g of antimony oxide are added, after a reaction system is replaced by nitrogen, the temperature is raised to 90 ℃, when solid materials are melted, stirring is started, the temperature is raised to the esterification reaction temperature of 200 ℃ at the speed of 40 ℃/h, esterification reaction is carried out for 5h, then polycondensation reaction is carried out for 3h under the absolute pressure of 60Pa, when the stirring power of the reaction kettle reaches 63-65W, the pressure of the reaction kettle is restored to normal pressure by nitrogen, and the reaction is stopped, so that the high molecular polymer with the molecular weight of 29000 is obtained. The material was slowly forced into a 5L dissolution vessel containing 2203g of ethyl acetate with nitrogen until the temperature reached the reflux temperature of the solvent and the solid material was completely dissolved to give a 35% strength by mass solution product.

Mixing the product with a commercially available polyisocyanate curing agent according to the molar ratio of the hydroxyl value of a solute to NCO of 1:2.5, coating the mixture on the surface of an aluminum foil, wherein the thickness of a dried adhesive layer is 5 mu m, then carrying out hot coating and bonding operation on a nylon layer, coating and curing operation on an inner layer film, and finally carrying out application performance tests such as deep drawing and stripping, wherein the test data are shown in the following table 1.

Evaluation method:

1. and (3) testing the peel strength: referring to the standard of GB-T2791-1995 adhesive T peel strength test method for flexible materials, an aluminum-plastic film sample is cut into a strip shape of 15mm multiplied by 20cm, one ends of a nylon layer and an aluminum foil layer which are not glued are symmetrically clamped on an upper clamp and a lower clamp of a universal testing machine respectively, the clamped parts cannot slide so as to ensure that the applied tensile force is uniformly distributed on the width of the sample, and the testing machine is started to separate the upper clamp and the lower clamp at the speed of 100 +/-10 mm/min. The peel length of the sample is at least 125 mm.

2. And (3) testing the punching depth performance: a double-pit deep punching die is adopted, the pit depth is 6mm, and the distance between the two pits is 1 mm. Whether the outer layer film edge has the abnormal phenomena of layering, whitening and the like after deep drawing.

3. Moisture and heat resistance: and (3) placing the aluminum plastic film sample qualified in the deep drawing into a constant temperature and humidity box, placing for 168 hours at the conditions of 85 ℃ and 85% humidity, and observing whether the corner of the outer layer film has abnormal phenomena such as layering, bubbling, white marks and the like.

The test data are shown in the following table:

TABLE 1 evaluation table of sample application properties

Therefore, according to the invention, through the design of the product structure, the distribution of molecular composition and functional structural units is relatively more balanced, and a macromolecular compound with a more regular structure can be obtained, so that the synthesized macromolecular adhesive product has stable application performance, good flexibility, excellent tensile resistance, better hydrolysis resistance, better cohesiveness and better impact resistance. The obtained product can completely meet the application performance requirement of the lithium battery aluminum plastic film on the outer layer adhesive. In the comparative example, due to the simultaneous esterification reaction of the acid anhydride and the alkyd, the functional structure segments in the final molecular chain are not uniformly distributed, and the polymer product cannot show the optimal application performance such as adhesion, humidity resistance and the like, and cannot meet the application performance requirement of the lithium battery aluminum plastic film.