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CN-122011247-A - Hindered amine light stabilizer grafted modified polymer, preparation method and application thereof

CN122011247ACN 122011247 ACN122011247 ACN 122011247ACN-122011247-A

Abstract

The invention discloses a hindered amine light stabilizer grafted modified polymer and a preparation method and application thereof. The modified polymer comprises a polymer backbone containing unsaturated carbon-carbon double bonds, and hindered amine light stabilizer structural units grafted to the backbone. The two are connected through a chemical bond formed by a connecting group containing a beta-ketoester structure, one end of the connecting group is connected with a main chain through a carbon-carbon bond, and the other end of the connecting group is connected with a hindered amine unit through an ester bond. The preparation method comprises the steps of firstly carrying out transesterification on hindered amine containing hydroxyl and an acetoacetate compound to prepare a hindered amine intermediate, and then carrying out addition or alkylation reaction on the intermediate and a polymer matrix under the action of an alkaline catalyst to complete grafting. The invention realizes the high molecular of the light stabilizer through chemical bonding, thoroughly solves the defects of easy migration and poor extraction resistance of the traditional hindered amine, and has long-acting ageing resistance due to the retention rate of the hindered amine of more than 70% after solvent extraction of the obtained weather-resistant polyolefin composition. The method has the advantages of simple process, mild reaction conditions and wide application range, and can be widely applied to the field of weather-resistant modification of polyolefin materials.

Inventors

  • ZHANG SHENG
  • Lv Qiaolian
  • LIU DECUI
  • XIAO XIONG
  • ZHOU XINYI

Assignees

  • 北京化工大学

Dates

Publication Date
20260512
Application Date
20260327

Claims (10)

  1. 1. A hindered amine light stabilizer graft modified polymer, comprising a polymer backbone structural unit and a hindered amine light stabilizer structural unit grafted to the polymer backbone, wherein the hindered amine light stabilizer structural unit is chemically bonded to the polymer backbone by a β -ketoester structure containing linking group comprising the structural fragment: wherein one end of the connecting group is connected with the polymer main chain through a carbon-carbon bond, and the other end is connected with the hindered amine light stabilizer structural unit through an ester bond.
  2. 2. The hindered amine light stabilizer graft-modified polymer of claim 1, wherein the hindered amine light stabilizer structural unit comprises a hindered amine compound having a hydroxyl group, preferably at least one from the group consisting of 2, 6-tetramethyl-4-piperidinol and 1,2, 6-pentamethyl-4-piperidinol.
  3. 3. A hindered amine light stabilizer graft-modified polymer according to any of claims 1-2, characterized in that the polymer backbone is a polymer containing structural units of unsaturated carbon-carbon double bonds, such as one or more of Polyethylene (PE), polybutadiene (PB) or polyisoprene, ethylene-propylene-diene monomer terpolymer (EPDM), styrene-butadiene-styrene block copolymer (SBS) and maleic anhydride grafted polyolefin (PO-g-MAH), preferably self-terminating acrylate polybutadiene.
  4. 4. A method for preparing the hindered amine light stabilizer graft modified polymer according to any one of claims 1 to 3, comprising the following steps: the first step of intermediate synthesis, namely performing ester exchange reaction on a hindered amine compound containing hydroxyl and an acetoacetate compound to prepare a hindered amine intermediate with a side chain containing an acetoacetate group; and a second grafting reaction, namely mixing the hindered amine intermediate obtained in the step (1) with a polymer matrix containing unsaturated carbon-carbon double bonds in the presence of a basic catalyst, and heating for reaction to enable the hindered amine intermediate to be grafted on the polymer matrix through an addition or alkylation reaction.
  5. 5. The process according to claim 4, wherein the acetoacetate compound in the step (1) is selected from the group consisting of methyl acetoacetate, ethyl acetoacetate and t-butyl acetoacetate.
  6. 6. The process according to claim 4, wherein step (1) is carried out in the presence of a Lewis acid catalyst selected from the group consisting of tetrabutyl titanate, dibutyltin oxide and p-toluenesulfonic acid, with concomitant removal of by-product alcohol.
  7. 7. The method according to claim 4, wherein the basic catalyst in the step (2) is an organic strong base or a complex system of the organic strong base and a Lewis acid. The organic strong base is selected from one or more of 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU), 1, 5-diazabicyclo [4.3.0] non-5-ene (DBN), 1,5, 7-triazabicyclo [4.4.0] dec-5-ene (TBD), tetramethylguanidine (TMG) or potassium tert-butoxide.
  8. 8. The process according to claim 4, wherein the grafting reaction temperature in the step (2) is 80 to 140℃and the reaction time is 2 to 12 h.
  9. 9. The method according to claim 4, wherein the molar ratio of the hindered amine intermediate to the double bonds in the polymer matrix in the step (2) is 0.5:1 to 2:1, and the amount of the basic catalyst is 0.5 to 10% of the molar amount of the hindered amine intermediate.
  10. 10. A weatherable polyolefin composition comprising the modified polymer of claims 1-3, wherein the composition has a hindered amine functionality retention of greater than 70% after solvent extraction.

Description

Hindered amine light stabilizer grafted modified polymer, preparation method and application thereof Technical Field The invention belongs to the technical field of polymer material assistants and modification, and particularly relates to a method for grafting a Hindered Amine Light Stabilizer (HALS) onto a polymer main chain by using active methylene chemistry, and a migration-resistant long-acting weather-resistant polymer material prepared by the method. Background Polyolefin-based plastics, such as polyethylene and polypropylene, are the most widely used plastic materials at present. However, in outdoor environments, these materials are susceptible to uv radiation, and photo-oxidative degradation occurs, resulting in reduced mechanical properties, color change or chalking. In order to extend its useful life, it is often necessary to add Hindered Amine Light Stabilizers (HALS). Major problems faced by current HALS technology include: 1. Physical migration, the poor compatibility of conventional low molecular weight HALS (e.g., HALS 770) with the polymer matrix, tends to migrate to the surface of the material over time, forming a "bloom" which not only affects the appearance of the material, but also results in a loss of protective efficacy. 2. Volatilizing and extracting, namely, the micromolecular HALS is easy to volatilize or be extracted and lost under the conditions of high-temperature processing or long-term contact with solvent/water. 3. The prior art has the defect that at present, the method for fixing HALS by chemical grafting mostly adopts free radical grafting initiated by peroxide. The method is violent in reaction, is easy to cause fracture (degradation) or uncontrollable crosslinking (gelation) of a polymer main chain, and seriously damages the basic mechanical property of the material. Therefore, it is an urgent need in the art to develop a novel HALS grafting technique that is mild in reaction conditions, high in grafting efficiency, and non-damaging to the polymer backbone. Disclosure of Invention The invention aims to solve the problems of easy migration and easy loss of the existing HALS and provides a hindered amine light stabilizer grafted modified polymer and a mild grafting method based on Michael addition or alkylation reaction of active methylene and unsaturated bonds. The invention provides a hindered amine light stabilizer grafted modified polymer which is characterized by comprising a polymer main chain structural unit and a hindered amine light stabilizer structural unit grafted on the polymer main chain, wherein the hindered amine light stabilizer structural unit is preferably connected with the polymer main chain through a connecting group containing a beta-ketoester structure by forming a chemical bond, and the connecting group comprises the following structural fragments: preferably, one end of the linking group is linked to the polymer backbone via a carbon-carbon bond and the other end is linked to the hindered amine light stabilizer structural unit via an ester bond. Preferably, the hindered amine light stabilizer graft modified polymer is characterized in that the hindered amine light stabilizer structural unit comprises a hindered amine compound of a hydroxyl group, preferably at least one of 2, 6-tetramethyl-4-piperidinol and 1,2, 6-pentamethyl-4-piperidinol. Preferably, the polymer backbone is a polymer containing structural units of unsaturated carbon-carbon double bonds, such as one or more of Polyethylene (PE), polybutadiene (PB) or polyisoprene, ethylene-propylene-diene monomer terpolymer (EPDM), styrene-butadiene-styrene block copolymer (SBS) and maleic anhydride grafted polyolefin (PO-g-MAH) with terminal double bonds, preferably a self-terminating acrylate polybutadiene. The invention provides a preparation method of a hindered amine light stabilizer grafted modified polymer, which comprises the following two steps: step one, synthesis of hindered amine functionalized intermediate (transesterification reaction) A hindered amine compound (such as 2, 6-tetramethyl-4-piperidinol) containing hydroxyl is subjected to transesterification with an acetoacetate compound (such as methyl acetoacetate) to prepare a hindered amine intermediate (hereinafter referred to as HALS-AcAc) containing an acetoacetate group (active methylene) in a side chain. The reaction scheme is as follows: Step two, polymer grafting reaction (base catalyzed addition) Nucleophilic addition of a polymer matrix containing unsaturated double bonds in the presence of a strong organic base catalyst (e.g., DBU) using the active methylene groups in the HALS-AcAc intermediate prepared in step one, thereby anchoring the HALS structure to the polymer chain in the form of chemical bonds. The reaction scheme is as follows: Preferably, the acetoacetate compound in step one is selected from methyl acetoacetate, ethyl acetoacetate or t-butyl acetoacetate. Preferably, step one is carried out in the presence of