CN111763351B

CN111763351B - A kind of reactive phosphaphenanthrene/phosphite double base flame retardant, its preparation method and application

Info

Publication number: CN111763351B
Application number: CN202010390988.2A
Authority: CN
Inventors: 许博; 王晶玉; 毕晓露; 王向东; 赵建明
Original assignee: Beijing Technology and Business University
Current assignee: Beijing Technology and Business University
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2021-08-31
Anticipated expiration: 2040-05-09
Also published as: CN111763351A

Abstract

The invention discloses a reactive phosphaphenanthrene/phosphite double-base flame retardant, a preparation method and application of a composite system in flame-retardant rigid polyurethane foam, and belongs to the technical field of flame-retardant materials. The invention adopts dialdehyde compound, organic phosphite and DOPO to synthesize a flame retardant with double-base synergistic effect, which is an environment-friendly flame retardant with high efficiency and high thermal stability, and its composite system can promote rigid polyurethane foam When burning, it quickly forms charcoal and forms a continuous and dense charcoal layer, which effectively reduces the heat release and makes the rigid polyurethane foam with excellent flame retardant properties.

Description

Reactive phosphaphenanthrene/phosphite ester biradical flame retardant, preparation method and application thereof

Technical Field

The invention belongs to the technical field of flame-retardant materials, and particularly relates to a reactive phosphaphenanthrene/phosphite ester biradical flame retardant, a preparation method thereof and application of a complex system in flame-retardant rigid polyurethane foam.

Background

The hard polyurethane foam has excellent physical and mechanical properties, electrical properties, mechanical properties, acid and alkali resistance and strong bonding force with various materials, so the hard polyurethane foam is widely used in the fields of automobile industry, household appliance industry, building industry and the like. However, the polyurethane material is flammable in air and decomposes to generate a large amount of toxic smoke, which may cause fire and cause casualties and great economic loss, etc., thereby limiting the further development of polyurethane foam. At present, the flame retardant most commonly applied to polyurethane foam is mainly a phosphorus-containing additive flame retardant such as phosphite flame retardant, the flame retardant is mainly used for improving the flame retardant performance of the polyurethane foam through gas-phase flame retardance, but most of the flame retardant is liquid and has the defects of poor heat resistance, easy precipitation and the like, and when the flame retardant is singly used, the prepared polyurethane material has poor stability.

In recent years, researchers have been working on designing and developing flame retardants with good flame retardant efficiency and little influence on the performance of the base material, and have been working on obtaining a good flame retardant effect of the base material with a low addition amount. Among them, the double-base synergistic flame retardant has received much attention from researchers, and its research results are published in many journals such as Macromolecules, polymers, Polymer Degradation and Stability, and Journal of Applied Polymer Science. In addition, the environment-friendly flame retardant is 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and has higher reactivity and good flame retardant effect, so that the preparation of the novel high-efficiency phosphaphenanthrene derivative flame retardant by taking the DOPO as a raw material becomes a research hotspot in the flame retardant field in recent years.

The phosphite flame retardant and the DOPO play a flame retardant role simultaneously in a physical blending mode, so certain disadvantages are undoubtedly brought: the polarity of phosphite ester is greatly different from that of a polymer matrix, the phosphite ester is easy to agglomerate, the problem of poor compatibility is easy to occur, meanwhile, the organic small molecular flame retardant is easy to migrate, and in addition, the mechanical property of the material is reduced due to the fact that the addition amount is too large. Therefore, the phosphite ester and the phosphaphenanthrene group are combined in one molecular unit through chemical bonds to form a reactive phosphaphenanthrene/phosphite ester double-base flame retardant, which not only solves the problems, but also enhances the double-base synergistic effect of the phosphite ester and the phosphaphenanthrene, and improves the flame retardant efficiency.

Disclosure of Invention

Aiming at the problems existing at present, the invention provides a novel environmentally-friendly phosphaphenanthrene/phosphite ester biradical flame retardant with biradical synergistic effect, a preparation method thereof and application of a complex system in flame-retardant rigid polyurethane foam. The reactive phosphaphenanthrene/phosphite ester biradical flame retardant has good thermal stability, and the complex system containing the phosphaphenanthrene/phosphite ester biradical flame retardant has higher flame retardant efficiency and can obviously improve the flame retardant property of hard polyurethane foam.

The flame retardant with different flame retardant mechanisms is selected, and the flame retardant is compounded to generate a good synergistic effect, so that a more obvious flame retardant effect is obtained, and the safety performance of the product is improved. The phosphaphenanthrene/phosphite ester double-base flame retardant has both hydroxyl group and flame retardant group, and in the reaction process with isocyanate group in polyurethane, the phosphaphenanthrene group and phosphite ester group are connected to the main chain of the molecular structure of polyurethane to hinder the combustion. In addition, Expandable Graphite (EG) forms a vermicular carbon layer on the surface of a matrix after being decomposed by heat, thereby playing an excellent condensed phase blocking role. The two reaction processes are continuously carried out, so that a compact phosphoric acid compound protective layer is formed on the outer surface of the flame-retardant RPUF carbon layer, and the compactness of the surface carbon layer is improved to isolate oxygen and heat.

The invention adopts the following technical scheme:

a reactive phosphaphenanthrene/phosphite diester-based flame retardant has a general structural formula shown as the following formula:

wherein R and R' are both alkyl or aryl.

The invention also discloses a synthetic method of the reactive phosphaphenanthrene/phosphite ester biradical flame retardant, and the synthetic route is as follows:

(1)

(2)

the specific preparation method comprises the following steps:

(1) adding a dialdehyde compound and an organic solvent into a reaction vessel, stirring and dissolving the dialdehyde compound and the organic solvent at 50 ℃, and then adding a certain amount of basic catalyst into the solution; b. dropping organic phosphite ester solution dissolved in proper amount of organic solvent into flask at certain speed, and raising the temperature of the system to react for certain time after dropping.

(2) Then adding DOPO into the reaction system obtained in the step (1) to continue the reaction for 8 to 12 hours. After the reaction is finished, cooling to room temperature, and carrying out reduced pressure distillation and drying to obtain the reactive phosphaphenanthrene/phosphite ester biradical flame retardant.

In the above technical scheme, preferably, the molar ratio of the dialdehyde compound and the organic phosphite ester in the step (1) is 1:1-1:3, preferably 1:1-1: 1.5; the dialdehyde compound is one of terephthalaldehyde, malonaldehyde, succinaldehyde, 3-diphenyl glutaraldehyde, hexanedial and heptanedial;

preferably, the organic solvent in the steps (1) a and (b) is one or more of methanol, ethanol, propanol, diethyl ether and dipropylene glycol dimethyl ether; the dosage of the organic solvent is as follows: 5-30ml (more preferably 7-20ml) of solvent per 1g of dialdehyde compound in a and 5-50ml (more preferably 10-35ml) of solvent per 1g of organic phosphite in b;

preferably, the basic catalyst in the step (1) is one of triethylamine, sodium ethoxide, sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, pyridine, 4-dimethylaminopyridine and N, N-diisopropylethylamine; the catalyst is used in such an amount that the molar ratio of organophosphite to catalyst is from 1:1 to 1:3, more preferably from 1:1 to 1: 2.5;

preferably, the organic phosphite in the step (1) is one of dimethyl phosphite, diethyl phosphite, di-n-propyl phosphite, diphenyl phosphite and dibenzyl phosphite; the dropping speed of the organic phosphite ester solution is 0.2-5ml/min, and more preferably 0.5-3 ml/min; after the organic phosphite ester solution is dripped, the system is heated to a certain temperature and reacts for a certain time: raising the temperature to 60-120 ℃ for reaction for 5-15h, more preferably 70-90 ℃ for reaction for 10-15 h;

preferably, the molar ratio of DOPO in step (2) to organophosphite in step (1) is from 1:1 to 1:3, preferably from 1:1 to 1: 1.5.

The invention also provides a halogen-free composite flame-retardant system containing the phosphaphenanthrene/phosphite ester biradical flame retardant, and the components of the composite system comprise: the phosphaphenanthrene/phosphite double-base flame retardant and expandable graphite.

In the above technical scheme, preferably, the phosphaphenanthrene/phosphite double-base flame retardant in the complex system: the mass ratio of the expandable graphite is 3:1-1: 1.

The invention also provides flame-retardant rigid polyurethane foam, and the preparation method comprises the following steps:

(1) mixing polyether polyol, water, a foaming agent, a foam stabilizer, a catalyst and the halogen-free composite flame retardant, and mechanically stirring for 3-5 min at normal temperature until the raw materials are uniformly mixed;

(2) and adding the polyisocyanate into the system, stirring, pouring into a prepared mould for natural foaming, and curing the foam to obtain the flame-retardant rigid polyurethane foam.

The mass ratio of the polyisocyanate to the polyether polyol in the step (1) is 1-1.6: 1.

The invention has the beneficial effects that:

1. the reactive phosphaphenanthrene/phosphite ester biradical flame retardant combines a phosphaphenanthrene group and an organic phosphite ester in the same molecular unit through chemical bonds to form a biradical synergistic effect, and the phosphaphenanthrene group and the phosphite ester group are connected to a main chain of a polyurethane molecular structure through reaction to hinder the combustion of the polyurethane molecular structure, so that the flame retardant efficiency is improved.

2. The reactive phosphaphenanthrene/phosphite ester biradical flame retardant has high thermal stability, moisture absorption resistance and matrix compatibility, is an efficient and high-thermal-stability environment-friendly flame retardant, and a composite system of the reactive phosphaphenanthrene/phosphite ester biradical flame retardant can promote hard polyurethane foam to quickly form carbon during combustion, form a continuous, complete and compact carbon layer, effectively reduce the release of heat and enable the hard polyurethane foam to have excellent flame retardant property.

3. The efficient and environment-friendly flame-retardant rigid polyurethane foam plastic prepared by the phosphaphenanthrene/phosphite double-base flame retardant and the composite system thereof has the advantages of sufficient raw material sources, low cost, simple preparation method, easily controlled industrial conditions and suitability for industrial production.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a nuclear magnetic resonance carbon spectrum of a phosphaphenanthrene/phosphite biradical flame retardant prepared in example 1;

FIG. 2 is an IR spectrum of a phosphaphenanthrene/phosphite biradical flame retardant prepared in example 1;

fig. 3 is a photograph of carbon residue after cone calorimetry testing of the flame retarded RPUF in example 1.

Detailed Description

The present invention will be described in further detail with reference to examples and the accompanying tables, but the embodiments of the present invention are not limited thereto.

Example 1

Adding 21.48g of terephthalaldehyde and 120ml of ethanol into a reaction vessel, stirring and dissolving the terephthalaldehyde at 50 ℃, and then adding 24ml of triethylamine into the solution; dissolving 22.10g diethyl phosphite in 300ml ethanol, after combustion, dripping the diethyl phosphite solution into the flask at the speed of 1ml/min, and after the dripping is finished, raising the temperature of the system to 90 ℃ for reaction for 8 h; then 34.56g of DOPO was added to the reaction system for 15 hours; after the reaction is finished, cooling to room temperature, and carrying out reduced pressure distillation and drying to obtain a reactive phosphaphenanthrene/phosphite ester biradical flame retardant; adding 72 parts of polyether polyol, 48 parts of phosphaphenanthrene/phosphite double-base flame retardant, 22 parts of expandable graphite, 0.9 part of water, 9 parts of foaming agent, 2.2 parts of foam stabilizer and 2.8 parts of catalyst into a 600mL plastic beaker, stirring for 3-5 min by using an electric stirrer until the raw materials are uniformly mixed, then quickly adding 108 parts of polyisocyanate into the beaker, simultaneously quickly stirring for 10s by using the electric stirrer, then quickly pouring the obtained mixture into a prepared mould for natural foaming, and obtaining the flame-retardant rigid polyurethane foam after foam curing.

Example 2

22.47g of terephthalaldehyde and 150ml of propanol were added to a reaction vessel and dissolved with stirring at 50 ℃ and then 20ml of sodium ethoxide was added to the solution; 26.42g of di-n-propyl phosphite is dissolved in 300ml of propanol, after combustion, the di-n-propyl phosphite solution is dripped into a flask at the speed of 1.5ml/min, and after dripping is finished, the system is raised to 90 ℃ for reaction for 10 hours; 38.88g of DOPO were subsequently added to the reaction system for 12 h; after the reaction is finished, cooling to room temperature, and carrying out reduced pressure distillation and drying to obtain a reactive phosphaphenanthrene/phosphite ester biradical flame retardant; according to the mass percent, 80 parts of polyether polyol, 40 parts of phosphaphenanthrene/phosphite double-base flame retardant, 20 parts of expandable graphite, 0.6 part of water, 10 parts of foaming agent, 2.5 parts of foam stabilizer and 2.5 parts of catalyst are added into a 600mL plastic beaker, stirred for 3-5 min by an electric stirrer until the raw materials are uniformly mixed, then 120 parts of polyisocyanate is rapidly added into the beaker, and simultaneously rapidly stirred for 10s by the electric stirrer, then the obtained mixture is rapidly poured into a prepared mould for natural foaming, and after foam curing, the flame-retardant rigid polyurethane foam can be obtained.

Example 3

11.53g of adipaldehyde and 100ml of diethyl ether are added to a reaction vessel and dissolved with stirring at 50 ℃ and then 18ml of N, N-diisopropylethylamine is added to the solution; 37.47g of diphenyl phosphite is dissolved in 350ml of diethyl ether, after combustion, the diphenyl phosphite solution is dripped into a flask at the speed of 2ml/min, and after the dripping is finished, the system is raised to 90 ℃ for reaction for 12 hours; subsequently, 41.04g of DOPO was added to the reaction system for 15 hours; after the reaction is finished, cooling to room temperature, and carrying out reduced pressure distillation and drying to obtain a reactive phosphaphenanthrene/phosphite ester biradical flame retardant; according to the mass, 70 parts of polyether polyol, 30 parts of phosphaphenanthrene/phosphite double-base flame retardant, 20 parts of expandable graphite, 0.8 part of water, 8 parts of foaming agent, 3 parts of foam stabilizer and 2 parts of catalyst are added into a 600mL plastic beaker in proportion, an electric stirrer is used for stirring for 3-5 min until the raw materials are uniformly mixed, 105 parts of polyisocyanate is quickly added into the beaker, the electric stirrer is used for quickly stirring for 10s, the obtained mixed material is quickly poured into a prepared mould for natural foaming, and the flame-retardant rigid polyurethane foam can be obtained after foam curing.

Comparative example

The flame retardant rigid polyurethane foam prepared from the phosphaphenanthrene/phosphite bis-based flame retardant and expandable graphite of example 1 was tested for flame retardant properties and pure RPUF was used as a control for comparison with the flame retardant sample of example 1. The specific test results are shown in table 1 and fig. 3.

Table 1 shows the cone calorimetry test results of example 1 and the control, wherein RPUF is the cone calorimetry test result of the control, and PDEP/EG/RPUF is the cone calorimetry test result of example 1. FIG. 3 is a photomicrograph of carbon residue after cone calorimetry testing of example 1.

TABLE 1 Cone calorimetry test results for the control and example 1

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several equivalent substitutions or obvious modifications, which are equivalent in performance or use, should be considered to fall within the scope of the present invention without departing from the spirit of the invention.

Claims

1. a reactive phosphaphenanthrene/phosphite double-base flame retardant, the general structural formula of which is shown in the following formula:

wherein R and R' are both alkyl or aryl groups.

2. a preparation method of phosphaphenanthrene/phosphite double base flame retardant according to claim 1, is characterized in that, comprises the steps:

(1) a. Add the dialdehyde compound and organic solvent into the reaction vessel, and stir and dissolve it at 50°C, then add a certain amount of basic catalyst to the solution; b. Dissolve the organic solvent in an appropriate amount of organic solvent The phosphite solution is added dropwise to the flask at a certain speed, and after the dropping is completed, the system is raised to a certain temperature and reacted for a certain period of time;

(2) Then DOPO was added to the reaction system obtained in step (1) and continued to react for 8-12 h. After the reaction was completed, it was cooled to room temperature, and a reactive phosphaphenanthrene/phosphite double base was obtained by distillation under reduced pressure and drying. flame retardant.

3. the preparation method of phosphaphenanthrene/phosphite double base flame retardant according to claim 2, is characterized in that: the mol ratio of the dialdehyde compound described in the step (1) and organic phosphite is 1:1-1:3; the dialdehyde compound is one of terephthalaldehyde, malondialdehyde, succinaldehyde, 3,3-diphenylglutaraldehyde, adipaldehyde, and heptanedialdehyde. kind.

4. the preparation method of phosphaphenanthrene/phosphite double base flame retardant according to claim 2, is characterized in that: the organic solvent described in step (1) a, b is selected from methanol, ethanol, propanol , one or more combinations in dipropylene glycol dimethyl ether; consumption of organic solvent: 5-30ml solvent/1g dialdehyde compound in a, 5-50ml solvent/1g organic phosphite in b.

5. the preparation method of phosphaphenanthrene/phosphite double base flame retardant according to claim 2, is characterized in that: the basic catalyst described in step (1) is triethylamine, sodium ethoxide, hydroxide A kind of in sodium, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, pyridine, 4-dimethylaminopyridine, N,N-diisopropylethylamine; The mol ratio of organic phosphite and catalyst is 1: 1-1:3.

6. the preparation method of phosphaphenanthrene/phosphite double base flame retardant according to claim 2, is characterized in that: the organic phosphite described in step (1) is dimethyl phosphite, phosphorous acid One of diethyl ester, di-n-propyl phosphite, diphenyl phosphite and dibenzyl phosphite; the dropping rate of the organic phosphite solution is 0.2-5ml/min; the dropwise addition of the organic phosphite solution is completed Then, the temperature of the system was raised to 60-120° C. for 5-15 hours.

7. the preparation method of phosphaphenanthrene/phosphite double base flame retardant according to claim 2, is characterized in that: DOPO described in step (2) and organic phosphorous acid described in step (1) The molar ratio of the ester is 1:1-1:3.

8. A halogen-free composite flame retardant system, characterized in that, comprising the reactive phosphaphenanthrene/phosphite double-base flame retardant as claimed in claim 1 or prepared by any method of claim 2-7 phosphaphenanthrene/phosphite double base flame retardant and expandable graphite.

9. a kind of halogen-free composite flame retardant system according to claim 8, is characterized in that, the mass ratio of described phosphaphenanthrene/phosphite double base flame retardant and expandable graphite is 3:1-1 :1.

10. A flame-retardant rigid polyurethane foam, characterized in that, obtained by adopting the halogen-free composite flame-retardant system as claimed in claim 9, and the concrete preparation method is as follows:

(1) Mix the polyether polyol, water, foaming agent, foam stabilizer, catalyst and halogen-free composite flame retardant, and stir mechanically at normal temperature until the raw materials are evenly mixed;

(2) adding polyisocyanate to above-mentioned system, the mass ratio of described polyisocyanate and polyether polyol in step (1) is 1-1.6:1, pour into mould after stirring and foam naturally, and immediately after foaming A flame retardant rigid polyurethane foam is obtained.