阅读说明：本技术 一种n-p协效腰果酚基阻燃固化剂的制备方法 (Preparation method of N-P synergistic cardanol-based flame-retardant curing agent ) 是由 陈建 周新领 顾奇 于 2020-07-31 设计创作，主要内容包括：本发明公布了一种N-P协效腰果酚基阻燃固化剂的制备方法,具体实施方法为将腰果酚、多聚甲醛和乙二胺混合,保温反应,反应结束后减压蒸馏除去甲醛和水轻组分,然后加入制备得到的［(2-环氧乙烷甲氧基)甲基］-膦酸二乙酯保温反应1-5h,之后加入环氧树脂E51,再加溶剂,最后出料得到产物。通过本发明的制备方法得到的N-P协效腰果酚基阻燃固化剂,阻燃效果好,有较高的极限氧指数,且不含卤素,是环境友好型固化剂,且主原料之一的腰果酚是可再生资源,符合可持续发展的需要。(The invention discloses a preparation method of an N-P synergistic cardanol-based flame-retardant curing agent, which comprises the specific implementation steps of mixing cardanol, paraformaldehyde and ethylenediamine, carrying out heat preservation reaction, carrying out reduced pressure distillation after the reaction is finished to remove formaldehyde and water light components, then adding prepared [ (2-oxiranomethoxy) methyl ] -diethyl phosphonate, carrying out heat preservation reaction for 1-5h, then adding epoxy resin E51, adding a solvent, and finally discharging to obtain a product. The N-P synergistic cardanol-based flame-retardant curing agent prepared by the preparation method disclosed by the invention is good in flame-retardant effect, higher in limited oxygen index, free of halogen and environment-friendly, and cardanol which is one of main raw materials is a renewable resource, so that the requirement of sustainable development is met.)

1. A preparation method of an N-P synergistic cardanol based flame retardant curing agent is characterized by comprising the following steps:

1) according to parts by weight, adding 22.4 parts of sodium hydride into 500 parts of THF under ice bath condition, under the protection of nitrogen, slowly dropwise adding a mixed solution of 46 parts of allyl chloride and 80.7 parts of diethyl hydroxymethylphosphonate while violently stirring, dropwise adding for 2 hours, reacting at room temperature for 24 hours after dropwise adding is finished, filtering, distilling and washing to obtain [ (2-propylene oxide) methyl ] -diethyl phosphonate;

2) adding a catalyst into 20.8 parts of [ (2-propylene oxy) methyl ] -diethyl phosphonate obtained in the step 1), placing the mixture into a reaction kettle, dropwise adding 13.6 parts of 30% hydrogen peroxide solution at 30 ℃ under the protection of nitrogen, dropwise adding for 1h, reacting for 5h after dropwise adding, washing a water layer with dichloromethane, combining the organic phase, washing the organic phase with saturated sodium bicarbonate solution, washing the organic phase with saturated sodium chloride solution and distilled water respectively to be neutral, drying the anhydrous sodium sulfate overnight, filtering and distilling to obtain a phosphorus-containing compound containing an epoxy group;

3) adding 300 parts of cardanol, 60-66 parts of paraformaldehyde and 60-90 parts of ethylenediamine into a reaction kettle, stirring and heating to 80-85 ℃, carrying out heat preservation reaction for 2-3h, vacuumizing to 5-20Kpa for distillation for 30min after the reaction is finished, then cooling to 60 ℃, gradually dropwise adding 11.2-56 parts of the phosphorus-containing compound obtained in the step 2), finishing dropping for 30min, carrying out heat preservation reaction after the dropwise adding is finished, then adding 5-30 parts of epoxy resin E51, carrying out heat preservation, adding 5-50 parts of solvent, and discharging to obtain the N-P synergistic cardanol-based flame retardant curing agent.

2. The preparation method of the N-P synergistic cardanol based flame retardant curing agent according to claim 1, wherein the catalyst in step 2) is dioctadecyl peroxyphosphotungstate or 1-hexyl-3-methylimidazol phosphotungstate.

3. The method for preparing an N-P synergistic cardanol based flame retardant curing agent according to claim 1, characterized in that the phosphorus-containing compound in step 2) and step 3) is [ (2-oxiranemethoxy) methyl ] -phosphonic acid diethyl ester.

4. The preparation method of the N-P synergistic cardanol based flame retardant curing agent according to claim 1, characterized in that after the phosphorus-containing compound is dropped in step 3), the temperature of the heat preservation reaction is 40-80 ℃.

5. The preparation method of the N-P synergistic cardanol based flame retardant curing agent according to claim 1, characterized in that after the phosphorus-containing compound is dropped in step 3), the reaction time is kept for 1-5 h.

6. The method for preparing an N-P synergistic cardanol based flame retardant curing agent according to claim 1, wherein the solvent in step 3) is xylene, N-butanol or isobutanol.

Technical Field

The invention belongs to the technical field of chemical synthesis of high polymer materials, and particularly relates to a preparation method of an N-P synergistic cardanol-based flame-retardant curing agent.

Background

In recent years, with the increasing awareness of fire protection, new challenges have been presented to the application of epoxy resins. Because the epoxy resin has low oxygen index and belongs to flammable substances, the application of the epoxy resin is greatly limited, the flame retardant property of the epoxy resin is improved, and the epoxy resin has very important significance for reducing fire hazard.

Cardanol is oily liquid extracted from natural cashew shell oil, belongs to green and environment-friendly industrial raw materials, a benzene ring structure enables the cashew shell oil to have high-temperature resistance, and a C15 straight chain containing unsaturated double bonds in the meta-position of the benzene ring can enhance the toughness of a system and provide excellent hydrophobicity and self-drying property, so that the cardanol is a research hotspot in recent years due to the fact that the cardanol is rich in source, low in price, excellent in performance and reproducible.

The nitrogen-containing flame retardant is a representative flame retardant in halogen-free flame retardants, and has the advantages of low corrosivity, low toxicity, high flame retardant efficiency, good compatibility with thermosetting materials, high decomposition temperature, suitability for processing and the like, so the nitrogen-containing flame retardant becomes a popular flame retardant. The nitrogen-based flame retardants are also classified into additive type and reactive type. The additive type flame retardant has the same disadvantages as the additive type organic phosphorus flame retardant, and also has the disadvantage of obviously increasing the viscosity of the system.

Among halogen-free flame retardants, the organophosphorus group belongs to another important class of flame retardants. The organophosphorus flame retardants can be classified into reactive type and additive type. The additive flame-retardant epoxy resin is prepared by adding a flame retardant into an epoxy resin curing agent, so that the flame-retardant effect is achieved, however, the additive flame retardant has the problems of large addition amount, poor compatibility with an epoxy matrix, easy migration and the like, and the application of the method for preparing the flame-retardant epoxy resin is limited.

The reactive flame retardant introduces a group containing a flame retardant element into a curing agent through reaction, so that the problems caused by physical addition are solved, however, the problems of high raw material price, complex and fussy preparation process and the like exist in the existing patents; the curing agent disclosed in patent CN108424513 is solid at normal temperature and is inconvenient to use.

The nitrogen-phosphorus synergistic flame retardant containing cardanol base synthesized by patent CN109232976A needs to be combined with phenolic resin through reaction, and then the phenolic resin obtained through reaction is subjected to foaming reaction with a curing agent and a foaming agent to obtain phenolic foam. The phosphorus content is extremely low under the condition that the adding amount is not too much, the improvement on the flame retardant performance is limited, and the limit oxygen index is lower than that of the common phenolic foam even under the condition that the using amount is less. Meanwhile, catalysts are used in the synthesis and use processes of the flame retardant, the post-treatment is troublesome, and the flame retardant is combined with phenolic resin in advance during use, so that the flame retardant is complicated.

The phosphorus-containing compound with the epoxy group used in the patent is directly connected to the curing agent through epoxy ring opening in the preparation process, and the reaction condition of the epoxy ring opening is simple, the temperature requirement is lower, and no catalyst is needed. The product with higher phosphorus content can be obtained, the flame retardant property is obviously improved, and the use is convenient. Meanwhile, the reactive flame-retardant curing agent has higher product stability and stable long-term storage performance.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method of an N-P synergistic cardanol based flame retardant curing agent.

The preparation method of the N-P synergistic cardanol-based flame retardant curing agent is characterized by comprising the following steps:

1) according to parts by weight, adding 22.4 parts of sodium hydride into 500 parts of THF under ice bath condition, under the protection of nitrogen, slowly dropwise adding a mixed solution of 46 parts of allyl chloride and 80.7 parts of diethyl hydroxymethylphosphonate while violently stirring, dropwise adding for 2 hours, reacting at room temperature for 24 hours after dropwise adding is finished, filtering, distilling and washing to obtain [ (2-propylene oxide) methyl ] -diethyl phosphonate;

2) adding a catalyst into 20.8 parts of [ (2-propylene oxy) methyl ] -diethyl phosphonate obtained in the step 1), putting the mixture into a reaction kettle, dropwise adding 13.6 parts of 30% hydrogen peroxide solution at 30 ℃ under the protection of nitrogen, dropwise adding for 1h, reacting for 5h after dropwise adding, washing a water layer by dichloromethane, combining the organic phase, washing the organic phase by a saturated sodium bicarbonate solution, washing the organic phase by a saturated sodium chloride solution and distilled water respectively to be neutral, drying the organic phase over anhydrous sodium sulfate overnight, filtering and distilling to obtain a phosphorus-containing compound;

3) adding 300 parts of cardanol, 60-66 parts of paraformaldehyde and 60-90 parts of ethylenediamine into a reaction kettle, stirring and heating to 80-85 ℃, carrying out heat preservation reaction for 2-3h, vacuumizing to 5-20Kpa for distilling for 30min after the reaction is finished, then cooling to 60 ℃, gradually dropwise adding 11.2-56 parts of the phosphorus-containing compound obtained in the step 2), carrying out heat preservation reaction after the dropwise adding is finished for 30min, then adding 5-30 parts of epoxy resin E51, carrying out heat preservation, adding 5-50 parts of solvent, and discharging to obtain the N-P synergistic cardanol-based flame retardant curing agent.

The preparation method of the N-P synergistic cardanol based flame retardant curing agent is characterized in that in the step 2), the catalyst is dioctadecyl peroxyphosphotungstate or 1-hexyl-3-methylimidazol phosphotungstate.

The preparation method of the N-P synergistic cardanol based flame retardant curing agent is characterized in that in the step 2) and the step 3), the phosphorus-containing compound is [ (2-oxirane methoxy) methyl ] -diethyl phosphonate.

The preparation method of the N-P synergistic cardanol-based flame retardant curing agent is characterized in that after the phosphorus-containing compound is dropwise added in the step 3), the temperature of the heat preservation reaction is 40-80 ℃.

The preparation method of the N-P synergistic cardanol-based flame retardant curing agent is characterized in that after the phosphorus-containing compound is dropwise added in the step 3), the reaction time is kept for 1-5 hours.

The preparation method of the N-P synergistic cardanol-based flame retardant curing agent is characterized in that a solvent in the step 3) is xylene, N-butanol or isobutanol.

The invention has the advantages and positive effects that:

1) the N-P synergistic cardanol-based flame-retardant curing agent provided by the invention is good in flame-retardant effect, higher in limited oxygen index, free of halogen and belongs to a halogen-free environment-friendly curing agent.

2) The N-P synergistic cardanol-based flame-retardant curing agent provided by the invention takes cardanol as one of main raw materials, belongs to renewable resources, and meets the requirements of sustainable development.

3) The N-P synergistic cardanol-based flame-retardant curing agent provided by the invention is used for connecting a phosphorus-containing compound to the curing agent through epoxy ring opening, the epoxy ring opening reaction condition is simple, the requirement on temperature is low, a catalyst is not needed, and the product stability is good.

When the N-P synergistic cardanol-based flame-retardant curing agent is prepared, the reaction formula is as follows:

step 1), 2):

step 3):

Detailed Description

The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.