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CN-122011308-A - Multifunctional phosphorus-containing phenolic curing agent, preparation method and heat-resistant flame-retardant epoxy resin thereof

CN122011308ACN 122011308 ACN122011308 ACN 122011308ACN-122011308-A

Abstract

The invention relates to the technical field of epoxy resin curing agents and functional epoxy resins, and discloses a phosphorus-containing phenolic aldehyde multifunctional curing agent, a preparation method and heat-resistant flame-retardant epoxy resin thereof, which specifically comprise the steps of preparing modified phenolic amine by taking DOPO type phenol monomers containing flexible ether chains, phenol, paraformaldehyde and triethylene tetramine as raw materials based on a Mannich reaction mechanism; based on nucleophilic substitution reaction mechanism of amino-chlorine, modified phenolic amine and chloropropyl heptaisobutyl POSS are subjected to reactive recombination to obtain the phosphorus-containing phenolic aldehyde multifunctional curing agent, and the curing agent is used for carrying out curing reaction on epoxy resin, so that the prepared epoxy resin cured product has high heat resistance, excellent strength and toughness balance and efficient phosphorus-silicon-nitrogen synergistic intrinsic flame retardant property.

Inventors

  • XING JUN
  • XING HAORAN

Assignees

  • 安庆天赢新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260326

Claims (8)

  1. 1. The preparation method of the phosphorus-containing phenolic aldehyde multifunctional curing agent is characterized by comprising the following steps of: (a) Preparing modified phenolic amine, namely mixing DOPO type phenol monomer containing flexible ether chain, phenol, paraformaldehyde and triethylene tetramine according to the molar ratio of (0.2-0.4): (0.6-0.8): 1:1, stirring and refluxing in absolute ethanol solvent under the protection of nitrogen for 4-6 hours at 80+/-2 ℃, and carrying out post-treatment to obtain the modified phenolic amine; (b) The POSS grafting reaction is carried out by mixing modified phenolic amine obtained in step (a) with chloropropyl heptaisobutyl POSS according to mass ratio of 1 (0.05-0.15), nucleophilic substitution reaction of amino-chlorine, stirring reaction for 10-14h at 60+ -2 ℃ under nitrogen protection in anhydrous tetrahydrofuran solvent, and post-treatment to obtain the phosphorus-containing phenolic aldehyde multifunctional curing agent; The DOPO type phenol monomer containing the flexible ether chain has the chemical structural formula: 。
  2. 2. the method for preparing the phosphorus-containing phenolic aldehyde multifunctional curing agent according to claim 1, wherein the method for preparing the DOPO type phenol monomer containing the flexible ether chain is as follows: based on the mechanism of the addition reaction of hydroxyl-isocyanate groups, the acrylate-based monomer containing flexible ether chains is obtained by the addition reaction of 1 molar equivalent of a polyethylene glycol monomer and 2.01-2.05 molar equivalents of isocyanate ethyl acrylate, wherein the polyethylene glycol monomer is one of triethylene glycol, tetraethylene glycol, pentaethylene glycol and hexaethylene glycol; Based on the Kabachnik-Fields reaction mechanism, carrying out condensation reaction on1 molar equivalent of 4-hydroxybenzylamine, 0.95-0.99 molar equivalent of DOPO and 0.95-0.99 molar equivalent of paraformaldehyde to obtain DOPO type phenol monomer containing secondary amine groups; Based on the addition reaction mechanism of the acrylate group-secondary amine group, the DOPO type phenol monomer containing the flexible ether chain is obtained through the addition reaction of 1 molar equivalent of the acrylate group monomer containing the flexible ether chain and 2.01-2.05 molar equivalents of the DOPO type phenol monomer containing the secondary amine group.
  3. 3. The method for preparing a multifunctional curing agent for phosphorus-containing phenolic aldehyde according to claim 2, wherein when the multi-glycol monomer is tetraethylene glycol, the prepared DOPO type phenol monomer containing flexible ether chain has the chemical structural formula: 。
  4. 4. the multifunctional phosphorus-containing phenolic curing agent prepared by the method according to any one of claims 1 to 3, wherein the amine value of the multifunctional phosphorus-containing phenolic curing agent is 330-380mgKOH/g.
  5. 5. The heat-resistant flame-retardant epoxy resin is characterized in that the heat-resistant flame-retardant epoxy resin is prepared by curing bisphenol A epoxy resin by the phosphorus-containing phenolic aldehyde multifunctional curing agent in claim 4.
  6. 6. The heat-resistant flame-retardant epoxy resin according to claim 5, wherein the heat-resistant flame-retardant epoxy resin has the formula: 75-90 parts by weight of bisphenol A epoxy resin; 3-8 parts by weight of a diluent; 30-40 parts by weight of a phosphorus-containing phenolic aldehyde multifunctional curing agent; 0.2-0.7 parts by weight of a curing accelerator.
  7. 7. The heat and flame resistant epoxy resin of claim 6, wherein said bisphenol a epoxy resin is type E-51.
  8. 8. The method for preparing a heat-resistant flame-retardant epoxy resin according to any one of claims 5 to 7, comprising the steps of: Adding a diluent into bisphenol A epoxy resin according to a formula of heat-resistant flame-retardant epoxy resin, stirring and mixing for 5-15min at a rotating speed of 400-600r/min, adding a phosphorus-containing phenolic aldehyde multifunctional curing agent and a curing accelerator, stirring and mixing for 5-15min at a rotating speed of 800-1200r/min, ensuring that the material temperature is not more than 30 ℃ in the mixing process, vacuumizing and defoaming at a low speed, and obtaining epoxy slurry; Pouring the epoxy slurry into a polytetrafluoroethylene mould coated with a release agent, curing by adopting a stepped heating curing process, namely curing for 0.8-1.2h at 75-85 ℃, then heating to 110-125 ℃ and curing for 0.8-1.2h, finally curing for 0.5-1.2h at 130-150 ℃, cooling and demolding to obtain the heat-resistant flame-retardant epoxy resin.

Description

Multifunctional phosphorus-containing phenolic curing agent, preparation method and heat-resistant flame-retardant epoxy resin thereof Technical Field The invention relates to the technical field of epoxy resin curing agents and functional epoxy resins, in particular to a phosphorus-containing phenolic aldehyde multifunctional curing agent, a preparation method and heat-resistant flame-retardant epoxy resin thereof. Background Epoxy resins are widely used in the fields of adhesives, paints, electronic packaging, engineering composite materials, civil engineering materials, and the like due to their excellent adhesive strength, low cure shrinkage, high mechanical strength, good electrical insulation and processability. The structure and performance of the curing agent, which is used as a core component of the epoxy curing system, directly determine the quality of the final cured product. Wherein, the phenolic amine curing agent prepared by Mannich reaction of phenols, aldehydes and lower aliphatic amine is one of the epoxy resin curing agent varieties widely used at present. The phenolic hydroxyl introduced in the molecular structure of the phenolic amine curing agent can obviously activate the curing reaction, endow the phenolic amine curing agent with the rapid curing capability in a low-temperature and humid environment, effectively reduce the construction difficulty and cost, and meanwhile, the phenolic skeleton structure introduced in the phenolic amine curing agent can obviously improve the rigidity and the thermal stability of an epoxy crosslinking network and overcome the defects of strong volatility, large irritation, high toxicity and the like of the traditional low-grade aliphatic amine curing agent (ethylenediamine, diethylenetriamine, triethylenetetramine and the like). However, the existing phenolic amine curing agent contains a large amount of rigid benzene rings in the molecular structure, so that the cured product has high crosslinking density and poor molecular chain flexibility. The high-rigidity structure causes the cured product to have the problems of large brittleness, insufficient flexibility, fatigue resistance, poor shock resistance and the like, and is extremely easy to generate crack growth when suffering from external force impact or long-term vibration load, thereby seriously restricting the service life and the reliability of the cured product in the high-end field. In the prior art, although the toughening of the epoxy cured product is reported by introducing a flexible chain segment into a phenolic aldehyde amine curing agent, the mechanical strength (such as tensile strength) and heat resistance of the epoxy cured product can be obviously reduced by simply introducing the flexible chain segment although the impact toughness can be improved, and the synergistic balance of the mechanical property and the heat resistance is difficult to realize. In addition, the molecular skeleton of bisphenol A type universal epoxy resin is rich in carbon-hydrogen bond, belongs to inflammable materials, and is easy to release a large amount of smoke and toxic gas during combustion. The main flame retardant modification means at present is a physical blending method, namely, a flame retardant is added into a resin matrix, although the technology is simple, the flame retardant is easy to migrate and separate out in the processing or using process, so that the flame retardant effect is attenuated, and the mechanical property and heat resistance of the resin matrix can be deteriorated due to the filling of a large amount of flame retardant, so that the high-end application requirements can not be met. Disclosure of Invention According to the invention, through a molecular structure design and a flexibility-rigidity cooperative regulation strategy, a multifunctional phenolic amine type curing agent grafted with a flexible ether chain, a flame-retardant DOPO group and a nano reinforced POSS structure is developed, and the curing agent is utilized to carry out a curing reaction on epoxy resin, so that the prepared epoxy resin cured product has high heat resistance, excellent strength and toughness balance and efficient phosphorus-silicon-nitrogen cooperative intrinsic flame retardant property. The preparation method of the phosphorus-containing phenolic aldehyde multifunctional curing agent comprises the following steps: (a) Preparing modified phenolic amine, namely mixing DOPO type phenol monomer containing flexible ether chain, phenol, paraformaldehyde and triethylene tetramine according to the molar ratio of (0.2-0.4): (0.6-0.8): 1:1, stirring and refluxing in absolute ethanol solvent under the protection of nitrogen for 4-6 hours at 80+/-2 ℃, and carrying out post-treatment to obtain the modified phenolic amine; (b) The POSS grafting reaction is carried out by mixing modified phenolic amine obtained in step (a) with chloropropyl heptaisobutyl POSS according to mass ratio of 1 (0.05-0.15), nucleop