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CN-121975073-A - Modified styrene block copolymer and preparation method and application thereof

CN121975073ACN 121975073 ACN121975073 ACN 121975073ACN-121975073-A

Abstract

The invention relates to a modified styrene block copolymer, a preparation method and application thereof, wherein the modified styrene block copolymer is a semi-hydrogenated styrene block copolymer modified by epoxy functional groups, the hydrogenation degree of the semi-hydrogenated styrene block copolymer is 60-90%, and the content of the epoxy functional groups of the semi-hydrogenated styrene block copolymer is 5-15 mol% based on the molar content of conjugated diene blocks. The epoxy modified styrene-conjugated diene block copolymer (ESBC) is adopted to replace the traditional SBC rubber, the partial hydrogenation structure of ESBC improves the stability and ageing resistance of the material, and a certain content of epoxy functional groups strengthens the compatibility and adhesive property of ESBC and polar materials. The hot melt adhesive prepared by ESBC has excellent bonding strength, thermal stability and electrolyte resistance, and has great application value in the field of lithium battery bonding.

Inventors

  • WANG CHENGUANG
  • ZHAO SHUAI
  • LIU DONG
  • JIANG XIANGBAO
  • JIN YONGHUI
  • WU ZHAORUI
  • Ge Jiejie
  • ZHANG YINGYING

Assignees

  • 浙江众立合成材料科技股份有限公司

Dates

Publication Date
20260505
Application Date
20260123

Claims (10)

  1. 1. The modified styrene block copolymer is characterized in that the modified styrene block copolymer is a semi-hydrogenated styrene block copolymer modified by epoxy functional groups, the hydrogenation degree of the semi-hydrogenated styrene block copolymer is 60-90%, and the content of the epoxy functional groups of the modified styrene block copolymer is 5-15 mol% based on the molar content of conjugated diene blocks.
  2. 2. The modified styrene block copolymer according to claim 1, wherein the weight average molecular weight of the semi-hydrogenated styrene block copolymer is 5X 10 4 ～20×10 4 , the styrene block content is 15 to 40 wt% based on the total weight of the copolymer, and the vinyl structure content is 40 to 60 wt%, based on 100% of the total mass of conjugated diene in the copolymer.
  3. 3. The modified styrene block copolymer according to claim 2, wherein the weight average molecular weight of the semi-hydrogenated styrene block copolymer is 10 x 10 4 ～15×10 4 , and the styrene block content is 20 to 30 wt% based on the total weight of the copolymer.
  4. 4. A process for preparing the modified styrenic block copolymer of claim 1, comprising the steps of: s1 preparation of semi-hydrogenated styrene Block copolymer Adding solvent, styrene and initiator into a polymerization kettle to prepare a styrene block, then adding a polarity regulator and conjugated diene monomer to obtain a styrene-conjugated diene block, and then adding styrene for reaction to terminate; S2 epoxidation reaction And (3) dropwise adding organic peroxy acid into the glue solution of the semi-hydrogenated styrene block copolymer, controlling the reaction temperature to be 10-50 ℃, stirring for reaction, adjusting the pH value of a system, washing with water to be neutral, settling the reaction solution, and drying the precipitate to constant weight to obtain the modified styrene block copolymer.
  5. 5. The process according to claim 4, wherein in step S1, the conjugated diene block is a butadiene homo-block, an isoprene homo-block or a butadiene-isoprene copolymer block.
  6. 6. The preparation method of the styrene-conjugated diene block according to claim 4, wherein conjugated diene monomers in the styrene-conjugated diene block are added in a gradient manner twice, the mass ratio of the two monomer additions is 9:1-6:4, the polarity regulator is ditetrahydrofurfuryl propane, the polarity regulator is added in a gradient manner twice, and the mass ratio of the first part of polarity regulator to the second part of polarity regulator is 3:1-1:1.
  7. 7. The preparation method according to claim 4, wherein the catalyst is a composite catalyst prepared by combining a group VIIIB metal compound and a metal compound, wherein the group VIIIB metal compound is selected from one of cobalt octoate, cobalt decanoate, cobalt carboxylate, cobalt neodecanoate, cobalt ethylhexanoate, nickel octoate, nickel decanoate, nickel acetylacetonate, and nickel carboxylate, and the metal compound is selected from one of trimethylaluminum, triethylaluminum, trioctylaluminum, triisobutylaluminum, and potassium borohydride.
  8. 8. The method according to claim 4, wherein in step S2, the organic peroxyacid is 3-chloroperoxybenzoic acid.
  9. 9. Use of the modified styrene block copolymer of claim 1 for the preparation of a hot melt adhesive for a new energy battery.
  10. 10. The application of the hot melt adhesive according to claim 9, wherein the hot melt adhesive comprises, by weight, 10-30 parts of SEBS rubber, 1-5 parts of maleic anhydride modified SEBS rubber, 5-20 parts of modified styrene block copolymer, 20-40 parts of naphthenic oil, 15-30 parts of tackifying resin and 0.5-2 parts of antioxidant.

Description

Modified styrene block copolymer and preparation method and application thereof Technical Field The invention belongs to the technical field of lithium battery adhesion, and particularly relates to a modified styrene block copolymer, a preparation method and application thereof. Background With the vigorous development of new energy industry, the lithium ion battery has been applied in various fields such as 3C consumer electronics, electric automobile and energy storage system in large scale due to the remarkable characteristics of compact structure, high energy density, light weight design, long cycle life and the like. In the production process of the lithium battery, the adhesive is used as a key functional auxiliary material, and the performance of the adhesive is directly related to the safety stability, the operation reliability and the comprehensive cycle life of the battery. The Styrene Block Copolymer (SBC) type hot melt pressure sensitive adhesive material is widely applied to key process links such as pole piece protection, battery core fixing, winding core termination, aluminum plastic film flanging, 5G electronic component adhesion and the like of a lithium battery, and the adhesion reliability of the material becomes an important factor for restricting the further improvement of the battery performance. The SBC type hot-melt pressure-sensitive adhesive material has the advantages of environmental protection, high viscoelasticity, high adhesive strength and excellent electrolyte resistance, but has poor high temperature resistance, water resistance and ageing resistance due to the fact that the molecular chain of the SBC type hot-melt pressure-sensitive adhesive material contains unsaturated double bonds and has lower polarity, so that the SBC type hot-melt pressure-sensitive adhesive material is limited to be further applied to lithium batteries. Chinese patent CN115851165A discloses a laminated hot melt adhesive applied to a soft package battery and a preparation method thereof, which uses cold-resistant toughening agent and low temperature resistant tackifying resin, effectively overcomes the problem of narrow high and low temperature resistant range interval of conventional hot melt adhesives, but has insufficient adhesive property to polar materials and weak peel strength. The development of the hot melt adhesive which has excellent high and low temperature resistance, water resistance and ageing resistance, good adhesion to polar base materials and good electrolyte resistance has great significance and wide application prospect. Disclosure of Invention In order to overcome the defects in the prior art, the invention provides a modified styrene block copolymer (ESBC), a preparation method and application thereof, which greatly improve the bonding strength of SBC hot melt adhesives and give consideration to high temperature resistance and electrolyte resistance. In order to achieve the aim of the invention, the invention adopts the following technical scheme: The modified styrene block copolymer is a semi-hydrogenated styrene block copolymer modified by epoxy functional groups, the hydrogenation degree of the semi-hydrogenated styrene block copolymer is 60-90%, and the content of the epoxy functional groups of the modified styrene block copolymer is 5-15 mol% based on the molar content of the conjugated diene block. The structural formula before and after the reaction is as follows: The introduction of the epoxy functional group can effectively improve the adhesion of the SBC resin to the polar substrate and the affinity with other components, and meanwhile, the semi-hydrogenated structural design also ensures that ESBC has good wet heat aging resistance and electrolyte resistance. Preferably, the weight average molecular weight of the semi-hydrogenated styrene block copolymer is 5 multiplied by 10 4～20×104, the styrene block content is 15-40 wt% of the total weight of the copolymer, and the vinyl structure content is 40-60 wt%, based on 100% of the total mass of conjugated diene in the copolymer. Too low a molecular weight can result in insufficient cohesive strength of the SBC, which can affect adhesion, and too high a molecular weight can increase processing and coating difficulties. Because the epoxidation reaction preferentially occurs in the 1,4 structure, the cross-linking side reaction in the epoxy modification process can be effectively avoided by the 1,2 structure with a certain content, and further mild regulation and control of the reaction are realized. Preferably, the weight average molecular weight of the semi-hydrogenated styrene block copolymer is 10×10 4～15×104, and the styrene block content is 20-30 wt% of the total weight of the copolymer. The preferable range has the technical effects that when the molecular weight is lower than 10 multiplied by 10 4, the SBC cohesive strength is insufficient, so that the holding power of the hot melt adhesive is reduced, when the mole