CN117736495A - Flame-retardant and high-temperature resistant polyurethane foam material and preparation method thereof - Google Patents

Abstract

The invention discloses a flame-retardant high-temperature-resistant polyurethane foam material and a preparation method thereof, belonging to the technical field of organic polymer synthesis. Firstly, carrying out surface modification on hydroxyapatite to obtain silane grafted hydroxyapatite, and then adding flame-retardant and high-temperature-resistant element boron into the silane grafted hydroxyapatite by boric acid to obtain silicon-boron modified hydroxyapatite, so as to obtain high-temperature-resistant Wen Chuji; then carrying out phosphate modification on starch to obtain phosphate starch, and preparing into an aqueous solution; oxidizing expandable graphite to obtain expanded graphite oxide EGO, and modifying the EGO with cetyltrimethylammonium bromide to prepare an aqueous solution; and preparing an ammonium polyphosphate aqueous solution, and respectively soaking and drying the polyurethane foam added with the high-temperature-resistant auxiliary agent in the three aqueous solutions in sequence to obtain the flame-retardant high-temperature-resistant polyurethane foam material. The invention greatly enhances the physical property stability at high temperature on the basis of not changing the original polyurethane foam structure and mechanical property, and the flame retardance can achieve self-extinguishing after leaving fire.

Description

Flame-retardant and high-temperature-resistant polyurethane foam material and preparation method thereof

Technical field

The invention belongs to the technical field of organic polymer synthesis, and specifically relates to a flame-retardant and high-temperature-resistant polyurethane foam material and a preparation method thereof.

Background technique

Polyurethane foam is a versatile material that is lightweight, high-strength, thermally insulating, soundproofing and weather-resistant. It dates back to the 1940s, when German scientists invented the material and initially applied it in aerospace. Polyurethane foam has excellent thermal insulation properties, which can reduce energy loss and improve the energy efficiency of buildings; it can also effectively block the spread of noise and has excellent performance in many aspects, but it also has some shortcomings in heat resistance and flame retardancy. Here are some common disadvantages: The heat resistance of polyurethane foam is limited by temperature. In high-temperature environments, polyurethane foam may melt, char, or produce toxic fumes. Easy to burn: Although flame retardants can be added to polyurethane foam to improve its flame retardant properties, there is still a risk of burning. In the event of a fire, polyurethane foam may support combustion, producing flames and toxic gases. In summary, the heat-resistant and flame-retardant properties of polyurethane foam have some shortcomings, which need to be paid attention to during use and handling. Where higher thermal and flame retardant properties are required, other alternative materials may need to be considered.

Traditionally, methods to improve the high temperature resistance of polyurethane foam mainly include adding flame retardants and inorganic fillers. Flame retardants such as melamine and DOPO can effectively inhibit the burning of foam at high temperatures, but these flame retardants often have certain toxicity and environmental problems. Another approach is to add inorganic fillers such as silica and expandable graphite. These fillers can increase the thermal stability and resistance to thermal expansion of the foam. However, the main drawback of this method is that the bonding between the inorganic filler and the polyurethane matrix is not strong, causing the filler to leave traces on the foam surface, affecting the appearance and performance of the foam. In addition, traditional methods also have other problems, such as increasing the density of the material, reducing the mechanical properties of the foam, and limiting the application temperature range of the foam.

Contents of the invention

The object of the present invention is to provide a flame-retardant and high-temperature resistant polyurethane foam material and a preparation method thereof. Without changing the structure and mechanical properties of the original polyurethane foam, the stability of its physical properties at high temperatures is greatly enhanced. The flame retardancy can achieve self-extinguishing when leaving fire. The more environmentally friendly diphenylmethane diisocyanate is used in the preparation process. , water, etc. are used as raw materials for foaming, which is suitable for actual production applications.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A high-temperature resistant and hydrolysis-resistant polyurethane foam material, which is composed of the following raw materials in parts by weight: 40-60 parts of polyether polyol, 40-60 parts of polypropylene glycol, and 0-20 parts of polymer polyol (including polyether polyol, The total weight of polypropylene glycol and polymer polyol is 100 parts), 0.4-1.0 parts of amine catalyst, 0.8-1.4 parts of tin catalyst, 0.8-1.2 parts of surfactant, 2.8-3.6 parts of foaming agent, high temperature resistance Filler 1-5 parts, diphenylmethane diisocyanate MDI 60-90 parts, the prepared polyurethane foam is immersed in an aqueous solution containing flame retardant additives to obtain a flame retardant and high temperature resistant polyurethane foam material.

The high temperature resistant filler is silicon boron modified hydroxyapatite BSHA. Its preparation process is as follows:

(1) Weigh 5g of nano-hydroxyapatite, add it to a beaker containing 100mL of deionized water and stir for 0.5h to form an aqueous solution. Then add 100mL of 90%wt ethanol solution to another beaker, add 2mL of LKH550 to hydrolyze it for 0.5h, and then The two solutions were mixed and reacted at 40°C for 4 hours to obtain KH550 modified hydroxyapatite.

(2) Filter and wash the NHA obtained after the reaction in step (1), and re-add it to 100 mL of deionized water to obtain an NHA aqueous solution. Weigh 1g of boric acid and add it to the NHA solution. After reacting for 3 hours at 40°C, vacuum filter and After drying, silicon boron modified hydroxyapatite BSHA is obtained.

The preparation process of the flame retardant impregnation solution is as follows:

(1) Preparation of phosphated starch aqueous solution: Prepare phosphated starch P-CS by wet method, weigh 3g of sodium dihydrogen phosphate into a 250mL three-neck flask, add 50mL of deionized water, and disperse with ultrasonic for 0.5h. Add 20g starch to the mixed solution, stir thoroughly, use dilute hydrochloric acid to adjust the pH = 6.5, transfer the three-neck flask to a water bath, reflux and cool, react at 65°C for 0.5h, cool, and neutralize with 1mol/L NaOH to neutrality, washed with absolute ethanol and deionized water, filtered with suction, and dried at 50°C for 24 hours to obtain P-CS. Weigh 10 g of P-CS and add it to a beaker containing 200 mL of deionized water to obtain a 5% wt P-CS aqueous solution.

(2) Prepare expandable graphene oxide EGO by the improved Hummers method. Weigh 0.5g EGO and add it to a beaker filled with 100mL deionized water for ultrasonic dispersion for 1 hour. Then prepare 2% wt 100mL cetyl trimethyl bromide. The ammonium aqueous solution was added to the ultrasonic dispersed EGO aqueous solution and stirred for 2 hours to obtain a modified EGO aqueous solution.

(3) Add 1g-5g of ammonium polyphosphate into a beaker containing 100 mL of deionized water to prepare an aqueous ammonium polyphosphate solution.

The preparation of the high temperature resistant polyurethane foam material includes the following steps:

(1) Add polyether polyol, polypropylene glycol, and polymer polyol into the container in proportion, then add high-temperature-resistant filler, amine catalyst, tin catalyst, surfactant, and foaming agent according to the formula, and rotate at a speed of Stir for 2-3 minutes with a mixer at 1500r/min, and record it as component A;

(2) Add diphenylmethane diisocyanate MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000 r/min, and record it as component B;

(3) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain high-temperature resistant polyurethane foam.

The soaking method of the flame-retardant and high-temperature-resistant polyurethane foam material is as follows:

(1) Dip the foam into the phosphate starch aqueous solution first, squeeze it several times and then immerse it for 0.5h, and then dry the soaked foam at 60°C for 2h;

(2) Then immerse the dried foam into the modified expandable graphene oxide aqueous solution, squeeze repeatedly, then immerse for 0.5h, and dry at 60°C for 2h;

(3) Then immerse the dried foam into the ammonium polyphosphate aqueous solution, squeeze repeatedly and then soak for 0.5 hours, and then dry at 60°C for 2 hours to obtain a flame-retardant and high-temperature resistant polyurethane foam material.

The polyether polyol is a polyether polyol produced by Huntsman Group in the United States.

The polypropylene glycol is polypropylene glycol PPG with Mn=3000 produced by Hai'an Petrochemical Plant in Jiangsu Province;

The polymer polyol is POP-2045 produced by Ningbo Hongyi Chemical Co., Ltd.

The amine catalyst is triethylenediamine A-33 produced by Momentive Advanced Materials Group in the United States;

The tin catalyst is stannous octoate T-9 produced by Shanghai Aladdin Biochemical Technology Co., Ltd.;

The surfactant is silicone oil 6008 produced by the American Momentive High-Tech Materials Group;

The foaming agent is deionized water;

The diphenylmethane diisocyanate is MDI-8002 produced by Huntsman Group in the United States.

The beneficial effects of the present invention are:

After rationally designing the production formula and process, using non-toxic water as the foaming agent, and using the safer diphenylmethane diisocyanate, the polyurethane sponge has the benefits of health and environmental protection. It has the characteristics of traditional polyurethane sponge and has high strength. , high temperature resistance and good flame retardant effect, that is, it still maintains excellent thermal stability at a temperature of 170°C, and will not suffer from high-temperature cracking during the insole molding process.

When nano-hydroxyapatite is added alone, due to the presence of its hydroxyl group, the foam will become softer than a part of the small molecule polyol, and adding a large amount will cause the foam to easily collapse. However, the present invention performs surface treatment on hydroxyapatite. Modify to obtain silane-grafted hydroxyapatite, and then use boric acid to add the flame-retardant and high-temperature resistant element boron to obtain silicon-boron-modified hydroxyapatite, which is added as a nanofiller to occupy most of its hydroxyl groups and is modified with KH550 Afterwards, it is better combined with the matrix, which not only increases the strength, but also the presence of silicon, boron and phosphorus elements can improve its temperature resistance.

When adding flame retardant fillers using the additive method, EGO has a large specific surface area and is difficult to disperse in the foam system. Ammonium polyphosphate and phosphate starch will aggregate and form nucleation points in the foam, resulting in uneven foaming. The foam collapses or shrinks, and the soaking method will make the flame retardant filler cover the foam, especially the high viscosity and biocompatibility of starch, which has a good first layer coverage effect as a base. In the present invention, starch is first modified by phosphate esterification to obtain phosphate starch. Using phosphate starch as a carbon source can cause the polymer compound to form a dense carbon layer when burned, and the expandable graphite is oxidized to obtain expanded oxidized graphite. Graphite EGO, modified with cetyltrimethylammonium bromide on EGO to make it positively charged. Since phosphate starch is negatively charged in water, it can self-assemble with phosphate starch for better combination, and EGO is used as the gas source, and it expands during combustion to achieve the purpose of flame retardancy; then prepare an aqueous solution of ammonium polyphosphate. Since the aqueous ammonium polyphosphate solution has a negative charge, it can adsorb each other with the EGO on the surface, so that the high-temperature-resistant additives can be added. The polyurethane foam is soaked and dried in three aqueous solutions to obtain a flame-retardant and high-temperature-resistant polyurethane foam material. This method uses hydroxyapatite with good biocompatibility as a high-temperature resistant filler and is non-toxic and harmless. It is similar to the foam produced. It has high strength, and the use of impregnation method greatly enhances the stability of its physical properties at high temperatures without changing the original polyurethane foam structure and mechanical properties. The flame retardancy can achieve self-extinguishing when leaving fire.

Description of drawings

Figure 1 shows the infrared spectrum of silicon boron modified hydroxyapatite;

Figure 2 is the infrared spectrum of phosphate starch;

Figure 3 is a scanning electron microscope image of flame-retardant and high-temperature resistant polyurethane foam.

Detailed ways

In order to make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

Example 1 (1g ammonium polyphosphate 1% solution concentration)

The high temperature resistant filler is silicon boron modified hydroxyapatite BSHA. Its preparation process is as follows:

(1) Weigh 5g of nano-hydroxyapatite, add it to a beaker containing 100mL of deionized water and stir for 0.5h to form an aqueous solution. Then add 100mL of 90%wt ethanol solution to another beaker, add 2mL of LKH550 to hydrolyze it for 0.5h, and then The two solutions were mixed and reacted at 40°C for 4 hours to obtain KH550 modified hydroxyapatite.

(2) Filter and wash the NHA obtained after the reaction in (1), and re-add it to 100 mL of deionized water to obtain an NHA aqueous solution. Weigh 1g of boric acid and add it to the NHA solution. After reacting for 3 hours at 40°C, vacuum filter and dry. Silica boron modified hydroxyapatite BSHA was obtained by drying.

The preparation process of flame retardant impregnation solution is as follows:

(1) Preparation of phosphated starch aqueous solution: Prepare phosphated starch P-CS by wet method, weigh 3g of sodium dihydrogen phosphate into a 250mL three-neck flask, add 50mL of deionized water, and disperse with ultrasonic for 0.5h. Add 20g starch to the mixed solution, stir thoroughly, use dilute hydrochloric acid to adjust the pH = 6.5, transfer the three-neck flask to a water bath, reflux and cool, react at 65°C for 0.5h, cool, and neutralize with 1mol/L NaOH to neutrality, washed with absolute ethanol and deionized water, filtered with suction, and dried at 50°C for 24 hours to obtain P-CS.

Weigh 10 g of P-CS and add it to a beaker containing 200 mL of deionized water to obtain a 5% wt P-CS aqueous solution.

(2) Prepare expandable graphene oxide EGO by the improved Hummers method. Weigh 0.5g EGO and add it to a beaker filled with 100mL deionized water for ultrasonic dispersion for 1 hour. Then prepare 2% wt 100mL cetyl trimethyl bromide. The ammonium aqueous solution was added to the ultrasonic dispersed EGO aqueous solution and stirred for 2 hours to obtain a modified EGO aqueous solution.

(3) Add 1g of ammonium polyphosphate into a beaker containing 100 mL of deionized water to prepare an aqueous solution of ammonium polyphosphate.

The preparation of high temperature resistant polyurethane foam materials includes the following steps:

(1)Weighing AQUAPUR 40 parts, PPG 40 parts, POP 20 parts, A-330.4 parts, T-90.8 parts, L-600 20.8 parts, deionized water 3.2 parts, BSHA 3 parts, MDI 70 parts

(2) will Add AQUAPUR, PPG, and PPG into the container in proportion, then add BSHA, A-33, T-9, L-6002, and deionized water according to the formula, and stir for 2-3 minutes with a mixer rotating at 1500r/min, recorded as Component A;

(3) Add MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000r/min, and record it as component B;

(4) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain high-temperature resistant polyurethane foam.

The soaking method of the flame-retardant and high-temperature-resistant polyurethane foam material is as follows:

(1) Dip the foam into the phosphate starch aqueous solution first, squeeze it several times and then immerse it for 0.5h, and then dry the soaked foam at 60°C for 2h;

(2) Then immerse the dried foam into the modified expandable graphene oxide aqueous solution, squeeze repeatedly, then immerse for 0.5h, and dry at 60°C for 2h;

(3) Then immerse the dried foam into the ammonium polyphosphate aqueous solution, squeeze repeatedly and then soak for 0.5 hours, and then dry at 60°C for 2 hours to obtain a flame-retardant and high-temperature resistant polyurethane foam material.

Example 2 (3g ammonium polyphosphate, solution concentration is 3%)

(1) The high temperature resistant filler is silicon boron modified hydroxyapatite BSHA: Simultaneous Example 1.

(2) Preparation of flame retardant impregnation solution: At the same time as Example 1, increase the amount of ammonium polyphosphate to 3 g, and the solution concentration is 3%.

(3) Preparation of high temperature resistant polyurethane foam materials: Simultaneous Example 1.

(4) Preparation of flame-retardant and high-temperature-resistant polyurethane foam materials: Simultaneous Example 1.

Example 3 (5g ammonium polyphosphate, solution concentration is 5%)

(1) The high temperature resistant filler is silicon boron modified hydroxyapatite BSHA: Simultaneous Example 1.

(2) Preparation of flame retardant impregnation solution: At the same time as Example 1, and increase the amount of ammonium polyphosphate to 5g, and the solution concentration is 5%.

(3) Preparation of high temperature resistant polyurethane foam materials: Simultaneous Example 1.

(4) Preparation of flame-retardant and high-temperature-resistant polyurethane foam materials: Simultaneous Example 1.

Comparative Example 1 (blank group, no high temperature resistant filler added and no immersion in flame retardant solution)

Preparation of polyurethane foam materials:

(1)Weighing AQUAPUR 40 parts, PPG 40 parts, POP 20 parts, A-330.4 parts, T-90.8 parts, L-600 20.8 parts, deionized water 3.2 parts, MDI 70 parts.

(2) will Add AQUAPUR, PPG, and PPG into the container in proportion, then add BSHA, A-33, T-9, L-6002, and deionized water according to the formula, and stir for 2-3 minutes with a mixer rotating at 1500r/min, recorded as Component A;

(3) Add MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000r/min, and record it as component B;

(4) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain the polyurethane foam material.

Comparative Example 2 (only P-CS soaking)

Preparation of polyurethane foam materials:

(1)Weighing AQUAPUR 40 parts, PPG 40 parts, POP 20 parts, A-330.4 parts, T-90.8 parts, L-600 20.8 parts, deionized water 3.2 parts, BSHA 3 parts, MDI 70 parts.

(2) will Add AQUAPUR, PPG, and PPG into the container in proportion, then add BSHA, A-33, T-9, L-6002, and deionized water according to the formula, and stir for 2-3 minutes with a mixer rotating at 1500r/min, recorded as Component A;

(3) Add MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000r/min, and record it as component B;

(4) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain high-temperature resistant polyurethane foam.

Preparation of flame retardant and high temperature resistant polyurethane foam materials:

(1) Preparation of phosphated starch aqueous solution: Prepare phosphated starch P-CS by wet method, weigh 3g of sodium dihydrogen phosphate into a 250mL three-neck flask, add 50mL of deionized water, and disperse with ultrasonic for 0.5h. Add 20g starch to the mixed solution, stir thoroughly, use dilute hydrochloric acid to adjust the pH = 6.5, transfer the three-neck flask to a water bath, reflux and cool, react at 65°C for 0.5h, cool, and neutralize with 1mol/L NaOH to neutrality, washed with absolute ethanol and deionized water, filtered with suction, and dried at 50°C for 24 hours to obtain P-CS.

Weigh 10 g of P-CS and add it to a beaker containing 200 mL of deionized water to obtain a 5% wt P-CS aqueous solution.

(2) Dip the foam into the phosphate starch aqueous solution, squeeze it several times and then immerse it for 0.5 hours. Then dry the soaked foam at 60°C for 2 hours to obtain a flame-retardant polyurethane foam.

Comparative Example 3 (only soaking P-CS and modified EGO)

Preparation of polyurethane foam materials:

(1)Weighing AQUAPUR 40 parts, PPG 40 parts, POP 20 parts, A-330.4 parts, T-90.8 parts, L-600 20.8 parts, deionized water 3.2 parts, BSHA 3 parts, MDI 70 parts.

(2) will Add AQUAPUR, PPG, and PPG into the container in proportion, then add BSHA, A-33, T-9, L-6002, and deionized water according to the formula, and stir for 2-3 minutes with a mixer rotating at 1500r/min, recorded as Component A;

(3) Add MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000r/min, and record it as component B;

(4) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain high-temperature resistant polyurethane foam.

Preparation of flame retardant and high temperature resistant polyurethane foam materials:

(1) Preparation of phosphated starch aqueous solution: Prepare phosphated starch P-CS by wet method, weigh 3g of sodium dihydrogen phosphate into a 250mL three-neck flask, add 50mL of deionized water, and disperse with ultrasonic for 0.5h. Add 20g starch to the mixed solution, stir thoroughly, use dilute hydrochloric acid to adjust the pH = 6.5, transfer the three-neck flask to a water bath, reflux and cool, react at 65°C for 0.5h, cool, and neutralize with 1mol/L NaOH to neutrality, washed with absolute ethanol and deionized water, filtered with suction, and dried at 50°C for 24 hours to obtain P-CS.

Weigh 10 g of P-CS and add it to a beaker containing 200 mL of deionized water to obtain a 5% wt P-CS aqueous solution.

(2) Prepare expandable graphene oxide EGO by the improved Hummers method. Weigh 0.5g EGO and add it to a beaker filled with 100mL deionized water for ultrasonic dispersion for 1 hour. Then prepare 2% wt 100mL cetyl trimethyl bromide. The ammonium aqueous solution was added to the ultrasonic dispersed EGO aqueous solution and stirred for 2 hours to obtain a modified EGO aqueous solution.

(3) Dip the foam into the phosphate starch aqueous solution, squeeze it for 0.5 hours several times, and then dry the soaked foam at 60°C for 2 hours; then immerse the dried foam into the ammonium polyphosphate aqueous solution, and repeat After extrusion, it was soaked for 0.5h, and then dried at 60°C for 2h to obtain a flame-retardant and high-temperature resistant polyurethane foam material.

Comparative Example 4 (add 1 part of high temperature resistant filler)

Preparation of polyurethane foam materials:

(1)Weighing AQUAPUR 40 parts, PPG 40 parts, POP 20 parts, A-330.4 parts, T-90.8 parts, L-600 20.8 parts, deionized water 3.2 parts, BSHA 1 part, MDI 70 parts.

(2) will Add AQUAPUR, PPG, and PPG into the container in proportion, then add BSHA, A-33, T-9, L-6002, and deionized water according to the formula, and stir for 2-3 minutes with a mixer rotating at 1500r/min, recorded as Component A;

(3) Add MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000r/min, and record it as component B;

(4) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain high-temperature resistant polyurethane foam.

Comparative Example 5 (add 5 parts of high temperature resistant filler)

Preparation of polyurethane foam materials:

(1)Weighing AQUAPUR 40 parts, PPG 40 parts, POP 20 parts, A-330.4 parts, T-90.8 parts, L-600 20.8 parts, deionized water 3.2 parts, BSHA 5 parts, MDI 70 parts.

(2) will Add AQUAPUR, PPG, and PPG into the container in proportion, then add BSHA, A-33, T-9, L-6002, and deionized water according to the formula, and stir for 2-3 minutes with a mixer rotating at 1500r/min, recorded as Component A;

(3) Add MDI into another container in proportion, stir for 10-30 seconds with a mixer rotating at 1000r/min, and record it as component B;

(4) Increase the speed of component A to 2500-3000r/min, then pour component B into the container containing component A, and stir for 10-15 seconds with a high-speed mixer. When the system turns white, pour the system into In the mold, control the mold temperature to 25±0.5°C and cut after 24-72 hours to obtain high-temperature resistant polyurethane foam.

Performance Testing

The sponges obtained in Examples 1-3 and Comparative Examples 1-5 were cut into different sizes. According to the national standards GB/T24451-2020 "Slow rebound soft polyurethane foam" and GBT 6344-2008 "Soft foam polymerization" Determination of tensile strength and elongation at break of materials", GBT 10807-2006 "Determination of hardness of soft foam polymeric materials (indentation method)" GB/T 9640-2008 "GB/T 9640-2008 Soft and rigid foams According to the requirements of "Accelerated Aging Test Method for Polymeric Materials", the foam density and tear strength of sponge products are tested, and the tensile strength, elongation at break, compression permanent deformation of the sponge and the thermal storage of the three (170℃, 140h treatment ) and then test the rate of change. The test results of the sponge obtained are shown in Table 1.

Table 1 Performance testing of finished polyurethane foam products

The data in Table 1 shows that the change rate of the physical and mechanical properties of the flame-retardant and high-temperature-resistant polyurethane foam material (Examples 1-3) according to the present invention does not exceed 5% after being treated in a thermal environment of 170°C. The high-temperature resistance of foams No. 1, 4, and 5 in the ratio has been greatly improved. It can be seen that as the amount of modified HA increased from 1 part to 5 parts, its strength gradually increased, but the elongation at break The length gradually decreases because HA particles are added as fillers to the polyurethane foam system, which can provide additional strength and support, and they have good affinity and can form good interfacial adhesion with polyurethane molecules. This adhesion can strengthen the bond between hydroxyapatite and polyurethane foam and improve the comprehensive mechanical properties of the material. The chemical composition of HA is mainly calcium, phosphorus, oxygen, hydroxyl and other elements. The combination of phosphate and hydroxyl forms a stable calcium phosphate structure. This structure has good chemical stability under high temperature conditions and is not prone to decomposition, dissolution or oxidation reactions. The crystal structure of hydroxyapatite is stable, showing a hexagonal crystal system, and has a high degree of crystallinity. Its crystal structure contains a large number of Ca-O bonds and P-O bonds. These bonds have high strength and can maintain stability at high temperatures. The surface energy of HA modified by silicon boron is increased and it has better compatibility with polyurethane foam. The addition of boric acid can react with the nitrogen in the polyurethane foam to form boric acid amine to further improve the heat resistance and flame retardancy.

It can be seen from Examples 1-3 that the flame retardant performance of the foam after soaking is related to the concentration of ammonium polyphosphate impregnation liquid. The best effect is when the concentration of ammonium polyphosphate reaches 5%. It cooperates with phosphate starch and EGO to achieve flame retardancy. The effect is that when burning, you can see that a carbon layer quickly forms on its surface, cutting off oxygen and extinguishing the flame. Compared with the comparative example, it can be seen that when used alone or both of them are used, they can only achieve the effect of delaying the burning time, but have poor self-extinguishing effect. In summary, it is proved that BSHA plays a high-temperature reinforcing effect on polyurethane sponge, making it The sponge is basically unchanged at high temperatures, and the soaked sponge can quickly form a dense carbon layer when burned, which is quickly flame-retardant. The synergy of the two provides a better effect.

In Figure 1, HA has characteristic vibration peaks of the phosphate group, including PO antisymmetric stretching vibration peaks at 1099cm ^-1 and 1041cm ^-1 , PO stretching vibration peaks at 962cm ^-1 , and PO stretching vibration peaks at 603cm ^-1 and 566cm ^-1 OPO bending vibration peak. The peaks at 3569cm ^-1 and 1637cm ^-1 are the characteristic vibration peaks of the hydroxyl group, and the broad peak at 3450cm ^-1 represents the presence of a certain amount of crystal water in the product. The new peak formed at 1340cm ^-1 is due to the successful grafting of surface KH550 by the formation of Si-OC bonds between KH550 and hydroxyl groups through silanol bonds, while the peak at around 750cm ^-1 strengthens the existence of surface BN bonds, surface boric acid and KH550 Amino reaction above. In summary, the surface silicon-boron modified hydroxyapatite was successfully synthesized.

In Figure 2, the successful synthesis of P-CS lies in the absorption peak at 933cm ^-1 and the absorption peak from 1400cm ^-1 to 1150cm ^-1 . The absorption peak at 933cm ^-1 is the characteristic peak of POC, so sodium dihydrogen phosphate can be judged The esterification reaction was successfully carried out with the hydroxyl groups on the starch. Multiple small peaks appeared between 1400cm ^-1 and 1150cm ^-1 , which are characteristic peaks of P=N, which can prove that P=N double bonds and POC were introduced into the starch, and esterification The reaction only adds phosphate groups to its original structure to achieve the effect of phosphate esterification.

In Figure 3, (a) shows the morphology of the foam cells after adding BSHA. It can be seen that the foam has a good opening rate, the pore diameter is between 100 and 200 microns, the cell membrane wall is thin, and the cells are The gap is smaller. (b) The picture shows the foam soaked in phosphate starch aqueous solution and dried. It can be seen that the starch has a large amount of adhesion and can penetrate into the foam. (c) The picture shows the foam after being soaked in EGO. It can be seen that there are obvious wrinkles on the surface of the foam, and the adsorption is good. It can basically cover the foam surface. It can expand rapidly when burning and release gas to achieve the flame retardant effect. . The picture (d) shows the foam after soaking in three flame retardant solutions. It can be seen that the phosphate starch is distributed on the foam, and the degree of EGO attached to the foam is high. In the attached picture, it can be seen that the P element is distributed throughout the foam. The surface ammonium polyphosphate can form electrostatic self-assembly with the modified EGO, making it more tightly combined.

From the macroscopic performance test in Table 1, it can be seen that BSHA, which is closely combined with the polyurethane matrix at high temperatures, can enhance structural stability. During combustion, P-CS, EGO, and ammonium polyphosphate cooperate with each other to achieve a synergistic flame retardant effect.

The above are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the patentable scope of the present invention shall fall within the scope of the present invention.

Claims (5)

1. A flame retardant, high temperature resistant polyurethane foam material, characterized in that: dipping the high-temperature-resistant polyurethane foam material into a solution containing a flame retardant auxiliary agent to obtain the flame retardant high-temperature-resistant polyurethane foam material; the high-temperature-resistant polyurethane foam material comprises the following raw materials in parts by weight: 40-60 parts of polyether polyol, 40-60 parts of polypropylene glycol, 0-20 parts of polymer polyol, 0.4-1.0 part of amine catalyst, 0.8-1.4 parts of tin catalyst, 0.8-1.2 parts of surfactant, 2.8-3.6 parts of foaming agent, 1-5 parts of high temperature resistant filler and 60-90 parts of diphenylmethane diisocyanate; wherein the sum of the parts by weight of the polyether polyol, the polypropylene glycol and the polymer polyol is 100 parts.

2. The flame retardant, high temperature resistant polyurethane foam of claim 1, wherein: the high-temperature resistant filler is silicon-boron modified hydroxyapatite, and the preparation method comprises the following steps:

(1) Adding 5g of nano hydroxyapatite into 100mL of deionized water, and stirring for 0.5h to obtain a solution A; adding 2mL KH550 into 100mL ethanol solution with concentration of 90wt.% and hydrolyzing for 0.5h to obtain solution B; mixing the solution A and the solution B, and reacting for 4 hours at 40 ℃ to obtain KH550 modified hydroxyapatite;

(2) Dissolving KH550 modified hydroxyapatite in deionized water, adding boric acid, and reacting at 40 ℃ for 3 hours to obtain silicon-boron modified hydroxyapatite.

3. The flame retardant, high temperature resistant polyurethane foam of claim 1, wherein: the solution containing the flame retardant auxiliary is a phosphate starch solution, a modified EGO solution and an ammonium polyphosphate solution; the preparation method comprises the following steps:

preparation of a phosphated starch solution: dissolving 3g of sodium dihydrogen phosphate in 50mL of deionized water, carrying out ultrasonic treatment for 0.5h, adding 20g of starch, fully stirring, adjusting pH=6.5 by using dilute hydrochloric acid, reacting for 0.5h at 65 ℃, cooling, neutralizing to neutrality by using 1mol/L NaOH solution, washing by using absolute ethyl alcohol and deionized water, carrying out suction filtration, drying at 50 ℃ for 24h to obtain phosphorylated starch, and preparing 5wt.% of phosphorylated starch solution by using deionized water;

preparation of modified EGO solution: preparing expandable graphene oxide EGO by a modified Hummers method; adding 0.5g of EGO into 100mL of deionized water, performing ultrasonic dispersion for 1h, adding 100mL of 2wt.% cetyltrimethylammonium bromide solution, and stirring for 2h to obtain a modified EGO solution;

preparation of ammonium polyphosphate solution: 1-5g of ammonium polyphosphate was dissolved in 100mL of deionized water to obtain an ammonium polyphosphate solution.

4. The flame retardant, high temperature resistant polyurethane foam of claim 1, wherein: the preparation of the high temperature resistant polyurethane foam material comprises the following steps:

(1) Mixing polyether polyol, polypropylene glycol, polymer polyol, high-temperature-resistant filler, amine catalyst, tin catalyst, surfactant and foaming agent, stirring at 1500r/min for 2-3min, and marking as component A;

(2) Diphenylmethane diisocyanate was stirred 1030 s at a speed of 1000r/min, noted as component B;

(3) And (3) increasing the rotating speed of the component A to 2500-3000r/min, adding the component B, stirring for 10-15s, pouring into a mould, controlling the temperature of the mould to be 25+/-0.5 ℃, and cutting after 24-72h to obtain the high-temperature-resistant polyurethane foam material.

5. A method of making the flame retardant, high temperature resistant polyurethane foam of any one of claims 1-4, wherein: the method comprises the following steps:

(1) Immersing the high-temperature-resistant polyurethane foam material in a phosphate starch solution for 0.5h, and drying at 60 ℃ for 2h;

(2) Immersing the foam material dried in the step (1) in a modified EGO solution for 0.5h, and drying at 60 ℃ for 2h;

(3) And (3) immersing the foam material dried in the step (2) in an ammonium polyphosphate solution for 0.5h and drying at 60 ℃ for 2h to obtain the flame-retardant high-temperature-resistant polyurethane foam material.