CN115850641B - A kind of flame retardant modified polyurethane material and its synthesis method - Google Patents

Abstract

The invention relates to the technical field of polyurethane, and discloses a flame-retardant modified polyurethane material and a synthesis method thereof. The flame-retardant modified polyurethane material includes 50-70 parts of polyether diol, 10-15 parts of toluene-2,4-diisocyanate, 5-10 parts of dibutyltin dilaurate, and 3-6 parts of a small-molecule flame-retardant cross-linking agent. By preparing a small-molecule flame-retardant cross-linking agent containing phosphaphenanthrene flame-retardant functional functional groups and hydroxyl active functional groups in the structure, a small-molecule flame-retardant cross-linking agent is added to the polyurethane material process. The flame retardant crosslinking agent makes the prepared polyurethane material structure rich in phosphaphenanthrene flame retardant functional groups, which effectively enhances the flame retardant performance of the polyurethane material. At the same time, the use of the crosslinking agent increases the crosslinking density of the molecular chain of the polyurethane material and improves the density of the polyurethane material, thereby effectively enhancing the mechanical properties such as impact strength and heat resistance of the polyurethane material.

Description

A kind of flame retardant modified polyurethane material and its synthesis method

technical field

The invention relates to the technical field of polyurethane, in particular to a flame-retardant modified polyurethane material and a synthesis method thereof.

Background technique

Polyurethane is a synthetic polymer material containing urethane groups in its main chain structure. With the continuous development of material science, the application range of polyurethane is gradually widening. Especially in the field of building materials, building exterior wall insulation boards made of polyurethane are becoming more and more popular. However, in recent years, urban high-rise building fires have occurred frequently, which has led to continuous improvement of people's requirements for the flame retardancy of building materials. In order to meet market demand, polyurethane materials are required to have good flame retardancy. As a building material, the temperature resistance and mechanical properties of polyurethane also need to be strengthened to a certain extent.

The Chinese patent with the application number CN202010294313.8 discloses a flame-retardant polyurethane material and its preparation method. Starting from the structural design of polyurethane, a nitrogen-containing heterocyclic structure is introduced into its molecular structure, which effectively improves the flame-retardant and heat-resistant performance of polyurethane material products. At the same time, the introduction of an aromatic heterocyclic structure into the polyurethane structure effectively improves the rigidity and toughness of the material. Therefore, by using different raw materials to prepare polyurethane, polyurethane can be given excellent performance. Strong, simple ingredients and beneficial to the actual production of raw materials to prepare polyurethane, on the one hand can enhance the various functions of polyurethane, on the other hand is also conducive to the further application of polyurethane materials.

Contents of the invention

The object of the present invention is to provide a flame-retardant modified polyurethane material and its synthesis method. By designing the polyurethane molecular chain and introducing a small-molecule flame-retardant crosslinking agent with flame-retardant functionality, it not only solves the problem of poor flame-retardant properties of polyurethane materials, but also enhances the heat resistance and mechanical properties of polyurethane materials.

The purpose of the present invention can be achieved through the following technical solutions:

A flame-retardant modified polyurethane material, comprising the following raw materials in parts by weight: 50-70 parts of polyether diol, 10-15 parts of toluene-2,4-diisocyanate, 5-10 parts of dibutyltin dilaurate, and 3-6 parts of small molecule flame-retardant crosslinking agent;

The structural formula of the small molecule flame retardant crosslinking agent is as follows:

Further, the synthesis method of the small molecule flame retardant crosslinking agent comprises the following steps:

1. Mix diphenyldichlorosilane and 1,4-dioxane, add 1,3-diglycidyl ether glycerol, stir well, place the system at 70-80°C, keep warm for 4-12h, wait until the gas is exhausted, distill under reduced pressure to remove low boilers, pour out the product, separate the solid by suction filtration, wash with deionized water, and dry in vacuum to obtain the intermediate;

Ⅱ. Dissolve the intermediate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in an organic solvent, mechanically stir evenly, blow nitrogen gas to remove the air in the system, and raise the temperature of the system to react. After the product is cooled to room temperature, the product is placed in a precipitant to precipitate 2-4 times to obtain a small molecule flame retardant crosslinking agent.

Through the above technical scheme, the structure of diphenyldichlorosilane contains Si-Cl bonds, which can react with the hydroxyl functional groups in the glycerol structure of 1,3-diglycidyl ether to generate intermediates rich in epoxy groups. The hydroxyl group produced by the ring opening of the epoxy group can participate in the polymerization process of polyurethane, that is, the small molecule flame retardant crosslinking agent.

Further, in step I, the molar ratio of diphenyldichlorosilane to 1,3-diglycidyl ether glycerol is 1:2-3.

Further, in step I, the temperature during vacuum drying is 50-60° C., and the time is 2-6 hours.

Further, in step II, the organic solvent is any one of tetrahydrofuran, N,N-dimethylformamide, and N,N-dimethylacetamide.

Further, in step II, the temperature of the reaction is 80-90° C., and the reaction is stirred for 6-18 hours under the protection of nitrogen.

Further, in step II, the precipitation agent is methanol.

A kind of synthetic method of flame-retardant modified polyurethane material is specifically as follows:

Put vacuum-dehydrated polyether diol and toluene-2,4-diisocyanate into the reactor and mix well, add dibutyltin dilaurate dropwise, raise the temperature of the system to 60-70°C, and react for 4-6h under the protection of nitrogen, put the small molecule flame-retardant crosslinking agent and the remaining dibutyltin dilaurate into the system, and continue the reaction for 2-3h.

Beneficial effects of the present invention:

(1) The present invention participates in the polymerization process of polyurethane by preparing a small-molecule flame-retardant cross-linking agent. Under the action of the cross-linking agent, the cross-linking density of the polyurethane molecular chain is greatly increased, thereby improving the density of the polyurethane material. On the one hand, the increase in density is beneficial to enhance the heat resistance of the polyurethane material. On the other hand, the increase in density can make the polyurethane material have higher impact resistance, which is beneficial to the further application of the polyurethane material.

(2) The structure of the small-molecule flame-retardant cross-linking agent prepared by the present invention contains abundant phosphaphenanthrene functional flame-retardant functional groups and hydroxyl functional groups. Since the combustion of the phosphaphenanthrene group can generate phosphorus oxyacids that can catalyze carbon formation, it can promote the formation of a carbon layer on the surface of the polyurethane material and prevent the combustion from continuing. Therefore, adding a small amount of small-molecule flame-retardant cross-linking agent can make the polyurethane material have excellent flame-retardant performance and cross-linking density. Moreover, the small-molecule flame-retardant cross-linking agent contains silicon elements, and inorganic materials such as silicon dioxide generated by combustion can be attached. On the carbon layer, the strength of the carbon layer is enhanced to avoid the collapse of the carbon layer and the decrease in the flame retardant performance of the polyurethane material. In addition, the presence of the flame retardant in the polyurethane structure in the form of chemical crosslinking can avoid the poor compatibility between the flame retardant and polyurethane and the phenomenon of precipitation.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work.

Fig. 1 is an infrared spectrogram of a small molecule flame retardant crosslinking agent in an example of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

In the following examples, the synthetic method of the small molecule flame retardant crosslinking agent is:

1. Mix 10g of diphenyldichlorosilane and 1,4-dioxane, add 18g of 1,3-diglycidyl ether glycerol, stir well, place the system at 75°C, keep it warm for 8h, wait until the gas is exhausted, distill under reduced pressure to remove low boilers, pour out the product, separate the solid by suction filtration, wash with deionized water, and vacuum dry at 50°C for 4h to obtain an intermediate;

Ⅱ. Dissolve 5g of the intermediate and 16g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in tetrahydrofuran, mechanically stir evenly, blow nitrogen to remove the air in the system, raise the temperature of the system to 90°C, stir for 12 hours under the protection of nitrogen, wait for the product to cool to room temperature, and place the product in methanol precipitant for three times of precipitation to obtain a small molecule flame retardant crosslinking agent. The structure is as follows:

Figure 1 is the infrared spectrogram of a small molecule flame retardant crosslinking agent, in which 3456cm ^-1 is the characteristic absorption peak of hydroxyl, 2859cm ^-1 is the stretching vibration peak of PO, 1284cm ^-1 is the stretching vibration peak of P=O, 1031cm ^-1 is the stretching vibration peak of Si-O, and 803cm ^-1 is the absorption vibration peak of benzene ring.

Example 1

Preparation of Flame Retardant Modified Polyurethane Material

Put 50 parts of vacuum dehydrated polyether diol and 10 parts of toluene-2,4-diisocyanate into the reactor and mix well, add 3 parts of dibutyltin dilaurate dropwise, raise the temperature of the system to 60°C, and react for 4 hours under the protection of nitrogen, put 3 parts of small molecule flame retardant crosslinking agent and 2 parts of dibutyltin dilaurate into the system, and continue the reaction for 2 hours.

Example 2

Preparation of Flame Retardant Modified Polyurethane Material

55 parts of polyether glycol and 12 toluene-2,4-diisisochexide are mixed with 55 parts of polyether glycol and 12 parts of tolitorne. After the reaction is 2h, after the reaction is over, the product will be cooled to room temperature and the dismissal will be retarded with flame -retardant polyurethane materials.

Example 3

Preparation of Flame Retardant Modified Polyurethane Material

Put 60 parts of vacuum dehydrated polyether diol and 14 parts of toluene-2,4-diisocyanate into the reactor and mix well, add 5.5 parts of dibutyltin dilaurate dropwise, raise the temperature of the system to 65°C, and react for 5 hours under the protection of nitrogen, put 5 parts of small molecule flame retardant crosslinking agent and 3 parts of dibutyltin dilaurate into the system, and continue the reaction for 3 hours.

Example 4

Preparation of Flame Retardant Modified Polyurethane Material

Put 70 parts of vacuum dehydrated polyether diol and 15 parts of toluene-2,4-diisocyanate into the reactor and mix well, add 6 parts of dibutyltin dilaurate dropwise, raise the temperature of the system to 70°C, and react for 6 hours under the protection of nitrogen, put 6 parts of small molecule flame retardant cross-linking agent and 4 parts of dibutyltin dilaurate into the system, and continue the reaction for 3 hours.

Comparative example 1

Preparation of polyurethane material

55 parts of polyether glycols and 12 toluene-2,4-bentisocyanate were mixed with 55 parts of polyether glycol in the reactor. After the reaction is 2h, after the reaction is over, the product will be cooled to room temperature and the dismissal will be retarded with flame -retardant polyurethane materials.

performance testing

With reference to the national standard GB/T 1043.2-2018, use the JBW-300B impact testing machine to test the impact performance of the polyurethane materials prepared in Example 1-Example 4 and Comparative Example 1 of the present invention; refer to the national standard GB/T 2406-2009, use the JF-3 type limiting oxygen index instrument to test the limiting oxygen index of the polyurethane materials prepared in Example 1-Example 4 and Comparative Example 1 of the present invention; take 0.5g of the inventive examples 1-Example 4 and Comparative Example 1 Prepare the polyurethane material, place it in a SAT200 thermogravimetric analyzer, set the heating rate at 10°C/min, raise the temperature from 25°C to 600°C under the protection of nitrogen, record the initial decomposition temperature, and evaluate the heat resistance performance. The test results are shown in the table below:

It can be seen from the table that the polyurethane materials prepared in Examples 1-4 of the present invention have relatively high impact strength and limiting oxygen index values, so they have relatively strong impact resistance and flame retardancy. In addition, the initial decomposition temperature is high, indicating that they have strong heat resistance. However, the polyurethane materials prepared in Comparative Example 1 have a low limiting oxygen index. It is presumed that pentaerythritol without flame retardant function is used as a crosslinking agent, so the flame retardant performance is poor.

With reference to the national standard GB/T 2048-1996, the UL-94 vertical combustion test was carried out on the polyurethane material prepared in Example 1-Example 4 of the present invention and Comparative Example 1, and the test results are shown in the following table:

It can be seen from the table that the polyurethane material prepared in Example 1-Example 4 of the present invention has a flame retardant grade of V-0 and has excellent flame retardant performance, while the polyurethane material prepared in Comparative Example 1 has a flame retardant grade of V-2, so the flame retardant performance is poor.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with this embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

The above content is only an example and description of the concept of the present invention. Those skilled in the art make various modifications or supplements to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, all should belong to the protection scope of the present invention.

Claims (8)

1. The flame-retardant modified polyurethane material is characterized by comprising the following raw materials in parts by weight: 50-70 parts of polyether glycol, 10-15 parts of toluene-2, 4-diisocyanate, 5-10 parts of dibutyltin dilaurate and 3-6 parts of small-molecule flame retardant cross-linking agent;

the structural formula of the small molecule flame retardant cross-linking agent is shown as follows:

2. the flame-retardant modified polyurethane material according to claim 1, wherein the synthesis method of the small molecule flame-retardant cross-linking agent comprises the following steps:

mixing diphenyl dichlorosilane with 1, 4-dioxane, adding 1, 3-diglycidyl ether glycerol, stirring uniformly, placing the system at 70-80 ℃ for 4-12 hours, removing low-boiling substances after gas is exhausted, distilling under reduced pressure, pouring out the product, filtering to separate solid, washing with deionized water, and vacuum drying to obtain an intermediate;

II, dissolving the intermediate and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in an organic solvent, mechanically stirring uniformly, introducing nitrogen to remove air in the system, raising the temperature of the system for reaction, cooling the product to room temperature, and placing the product in a precipitator for precipitation for 2-4 times to obtain the micromolecular flame-retardant cross-linking agent.

3. The flame retardant modified polyurethane material of claim 2, wherein in step i, the molar ratio of diphenyldichlorosilane to 1, 3-diglycidyl ether glycerin is 1:2-3.

4. The flame retardant modified polyurethane material of claim 2, wherein in step i, the temperature is 50-60 ℃ and the time is 2-6 hours during vacuum drying.

5. The flame-retardant modified polyurethane material according to claim 2, wherein in the step ii, the organic solvent is any one of tetrahydrofuran, N-dimethylformamide, and N, N-dimethylacetamide.

6. The flame retardant modified polyurethane material of claim 2, wherein in step ii, the reaction temperature is 80-90 ℃, and the reaction is stirred for 6-18 hours under nitrogen protection.

7. The flame retardant modified polyurethane material of claim 2, wherein in step ii, the precipitant is methanol.

8. A method for synthesizing the flame-retardant modified polyurethane material according to claim 1, which is characterized in that the method specifically comprises the following steps:

adding polyether glycol dehydrated in vacuum and toluene-2, 4-diisocyanate into a reactor, uniformly mixing, dripping part of dibutyltin dilaurate, raising the temperature of the system to 60-70 ℃, reacting for 4-6 hours under the protection of nitrogen, adding a micromolecular flame retardant cross-linking agent and the rest dibutyltin dilaurate into the system, continuously reacting for 2-3 hours, cooling the product to room temperature after the reaction is finished, and discharging to obtain the flame retardant modified polyurethane material.