Flame-retardant toluene diisocynate derivative as well as preparation method and application thereof

Abstract

The invention relates to a flame-retardant toluene diisocynate derivative and a preparation method and application thereof, and is characterized in that the flame-retardant toluene diisocynate derivative has a structural general formula of CH3-nCln-Ar-(NCO) 2, Ar is a benzene ring, and n is 1-2. The flame-retardant toluene diisocynate derivative is prepared by reacting TDI and chlorine under the action of an initiator, the method is simple, the influence on the physical properties of the foam is small, and the polyurethane flexible foam prepared under the condition that a flame retardant does not need to be added has flame-retardant property and lasting flame-retardant effect, and is more suitable for the field with higher flame-retardant requirements on the polyurethane foam.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane applications, and particularly relates to a flame-retardant toluene diisocyanate derivative, a preparation method thereof, and an application thereof. Background Art

[0002] Polyurethane (PU) foam plastics are the most important variety in polyurethane materials, with a production volume accounting for about 70% of the total. They are widely used in various aspects such as thermal insulation, shock absorption, sound insulation, lightweight structural components, seat cushions, packaging, and automotive interior decoration parts. In recent years, polyurethane foam has developed rapidly, and its production and application scope are expanding rapidly, playing an increasingly important role in the development of various fields of the national economy. Like other organic polymer materials, polyurethane materials are polymers with relatively strong flammability. Especially for flexible foam plastics, due to their low density, large specific surface area, and good thermal insulation properties, they are extremely easy to be ignited and burned. Moreover, once on fire, the combustion is rapid and fierce, not easy to extinguish, and toxic smoke will be generated after combustion, which is extremely likely to cause suffocation and death of personnel.

[0003] In addition, due to the porous structure characteristics of polyurethane flexible foam, it is prone to non-flaming smoldering combustion, which is also a hazard that cannot be ignored for polyurethane flexible foam. In order to avoid the occurrence of fires, the flame-retardant standards for polyurethane foam are continuously improving, which promotes the rapid development of flame-retardant foam technology. Currently, there are three methods to endow polyurethane flexible foam with flame-retardant properties: One is to introduce a flame-retardant structure into the molecular structure of the foam. Polyurethane foam is one of the polymer materials with great difficulty in flame retardancy. Due to the high requirements for foaming process conditions during the production of polyurethane foam, the method of generally adding flame retardants may cause problems such as uneven distribution of the flame retardant and certain influence on the physical properties of the foam, resulting in foam collapse, cracking, powdering, or a significant decrease in its physical and mechanical properties such as resilience, losing the performance advantages it originally had. At the same time, there are also disadvantages such as the exudation of the flame retardant due to long-term storage, which reduces the flame-retardant effect and leads to poor flame-retardant stability. The second is to post-treat polyurethane foam by the impregnation method. It requires a relatively high open-cell rate of the foam and is troublesome to operate. In the case of smaller cell pores, it is very difficult to infiltrate the flame retardant into the interior of the foam. The third is to add a flame retardant to the polyurethane raw materials. Introducing a flame-retardant structure into the molecular structure of the foam can overcome the above defects, making the produced foam easier to meet the flame-retardant index. Therefore, the method of introducing a flame-retardant structure into the molecular structure of the foam is a relatively effective and promising flame-retardant method.

[0004] Substances containing halogen elements have poor combustion performance and have a certain flame-retardant effect. Therefore, through the research on flame-retardant toluene diisocyanate derivatives, introducing a halogen structure with flame-retardant properties into the molecular structure of the foam can play a certain flame-retardant role. Summary of the Invention

[0005] The present invention aims to avoid the deficiencies of the prior art and provides a flame-retardant toluene diisocyanate derivative, its preparation method and applications.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A flame-retardant toluene diisocyanate derivative, characterized in that: the general structural formula of the flame-retardant toluene diisocyanate derivative is: CH 3-n Cl n -Ar-(NCO)2, where Ar is a benzene ring and n is 1-2.

[0007] Further, the structural formula of the flame-retardant toluene diisocyanate derivative is:

[0008] A preparation method of a flame-retardant toluene diisocyanate derivative, characterized in that: it includes the following steps: Step 1: Add anhydrous toluene diisocyanate, an initiator and carbon tetrachloride into a reactor, and stir and mix evenly; Step 2: Introduce anhydrous chlorine gas into the reactor, and the tail gas is introduced into an alkali solution absorption device for absorption and destruction. When the chlorine gas fills the reactor, that is, bubbles appear in the alkali solution absorption device, start heating, control the heating temperature to produce reflux, start the reaction, stop heating after the reaction ends, cool down to below 30°C, and stop introducing chlorine gas; Step 3: Introduce nitrogen gas into the reactor to purge the dissolved chlorine gas and hydrogen chloride into the alkali solution absorption device for destruction treatment, and then cool the reactor to room temperature to obtain a reaction mixture; Step 4: Distill off carbon tetrachloride under normal pressure from the reaction mixture for recycling, and subject the remaining liquid to vacuum distillation, and collect the fraction under the conditions of 100-110°C and 7.6 mmHg, which is the target product: the flame-retardant toluene diisocyanate derivative.

[0009] Further, in Step 1, the mass ratio of the toluene diisocyanate to carbon tetrachloride is 6:100 - 15:100, where the purity of the toluene diisocyanate is greater than 99%, and the content of the 2,4 isomer is 80 ± 1%.

[0010] In Step 1, the initiator is azobisisobutyronitrile, and the addition amount is 1-1.5% of the mass of the toluene diisocyanate.

[0011] Further, in Step 2, the reaction time is 6-10h.

[0012] Application of a flame - retardant toluene diisocyanate derivative, characterized in that it is applied to the foaming of polyurethane flexible foam; the specific method is as follows: at an ambient temperature of 22°C to 25°C and a raw material temperature of 22°C to 25°C, polyether polyol, silicone oil, water, and amine catalyst are added to a mixing barrel in proportion and stirred evenly, left standing for 2 - 3 minutes, tin catalyst is added, and then the flame - retardant toluene diisocyanate derivative is added to the mixing barrel. Start the stopwatch, stir rapidly for 5 - 7 seconds, and then quickly pour the mixed material into a foaming box for foaming. After curing, cut it into the required size.

[0013] The polyether polyol, silicone oil, water, amine catalyst, tin catalyst, and flame - retardant toluene diisocyanate derivative are in the following weight parts: Polyether polyol 100 parts; Silicone oil 1 part; Water 4.2 parts; Amine catalyst 0.3 part; Tin catalyst 0.15 part; Flame - retardant toluene diisocyanate derivative 53.3 parts.

[0014] The beneficial effects of the present invention are: preparing the flame - retardant toluene diisocyanate derivative by reacting toluene diisocyanate with chlorine gas. The method is simple, has little impact on the physical properties of the foam, can prepare polyurethane flexible foam with flame - retardant properties without adding flame - retardants, has a long - lasting flame - retardant effect, and is more suitable for fields with higher requirements for the flame - retardancy of polyurethane foam. Specific embodiments

[0015] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0016] Example 1: A preparation method of a flame - retardant toluene diisocyanate derivative, the specific steps are as follows: Step 1: Add 174 g of toluene diisocyanate, 1.74 g of azobisisobutyronitrile, and 1200 g of carbon tetrachloride to a reactor, and stir and mix evenly; Step 2: Introduce chlorine gas into the reactor, and the tail gas is introduced into an alkali solution absorption device for absorption and destruction. After the reactor is filled with chlorine gas (i.e., bubbles appear in the alkali solution absorption device), start heating, control the heating temperature to about 76°C, produce reflux, react for 6.5 h, then stop heating, and stop introducing chlorine gas when the temperature drops below 30°C; Step 3: Introduce nitrogen gas into the reactor, purge the dissolved chlorine gas and hydrogen chloride into the alkali solution absorption device for destruction treatment, and cool to room temperature to obtain a reaction mixture; Step 4: Distill carbon tetrachloride from the reaction mixture under atmospheric pressure for recycling. Subject the remaining liquid to vacuum distillation and collect the fraction under the conditions of 100 - 110 °C and 7.6 mmHg, which is the product: the flame-retardant toluene diisocyanate derivative mixture M1.

[0017] Upon sampling and analysis, the molar ratio of monochloride to dichloride in M1 is 3.95:1.

[0018] Use M1 as the isocyanate component for foaming as follows: At an ambient temperature of 22 °C - 25 °C and a raw material temperature of 22 °C - 25 °C, add polyether polyol, silicone oil, water, and amine catalyst in proportion to a mixing barrel, stir evenly, let stand for 2 - 3 minutes, and then add tin catalyst. Then add a certain amount of TDI to the mixing barrel, start the stopwatch, stir rapidly for 5 - 7 seconds, and quickly pour the mixed material into a foaming box for foaming. After curing, cut it into the required size.

[0019] The feeding amounts of the above components are by weight: Polyether 3010: 100 parts; Silicone oil L580: 1 part; Catalyst A - 33 (a liquid catalyst containing 33% triethylenediamine): 0.3 part; Water: 4.2 parts; Catalyst T - 9 (stannous octoate): 0.15 part; M1: 53.3 parts.

[0020] When using toluene diisocyanate as the isocyanate component according to the above formula, the oxygen index of the obtained polyurethane flexible foam is 18%. When M1 is the isocyanate component, the oxygen index of the obtained polyurethane flexible foam is 26%. Other foam mechanical properties are similar.

[0021] Example 2: A preparation method of a flame-retardant toluene diisocyanate derivative, the specific steps are as follows: Step 1: Add 174 g of toluene diisocyanate, 2.60 g of azobisisobutyronitrile, and 2600 g of carbon tetrachloride to a reactor, and stir and mix evenly; Step 2: Pass chlorine gas into the reactor, and pass the tail gas into an alkali solution absorption device for absorption and destruction. After the chlorine gas fills the reactor (i.e., bubbles appear in the alkali solution absorption device), start heating, control the heating temperature to about 76 °C, reflux occurs, and after reacting for 10 h, stop heating, and stop passing chlorine gas when the temperature drops below 30 °C; Step 3: Pass nitrogen gas into the reactor to purge the dissolved chlorine gas and hydrogen chloride into the alkali solution for destruction treatment, and cool to room temperature to obtain a reaction mixture; Step 4: Distill off carbon tetrachloride under atmospheric pressure for recycling, and subject the remaining liquid to vacuum distillation. Collect the fraction under the conditions of 100 - 110 °C and 7.6 mmHg, and the product is the flame-retardant toluene diisocyanate derivative mixture M2.

[0022] Upon sampling and analysis, the molar ratio of the monochloride to the dichloride in M2 is 1:1.

[0023] Use M2 as the isocyanate component for foaming, and the method is the same as in Example 1.

[0024] When using toluene diisocyanate as the isocyanate component, the oxygen index of the obtained polyurethane flexible foam is 18%. When using M2 as the isocyanate component, the oxygen index of the obtained polyurethane flexible foam is 30%. Other foam mechanical properties are similar.

[0025] Example 3: A preparation method of a flame-retardant toluene diisocyanate derivative, and the specific steps are as follows: Step 1: Add 174 g of toluene diisocyanate, 2.10 g of azobisisobutyronitrile, and 1800 g of carbon tetrachloride into a reactor, and stir and mix evenly; Step 2: Introduce chlorine gas into the reactor, and the tail gas is introduced into an alkali solution absorption device for absorption and destruction. After the reactor is filled with chlorine gas (i.e., bubbles appear in the alkali solution absorption device), start heating, control the heating temperature to about 76 °C, produce reflux, and after reacting for 8.5 h, stop heating, and stop introducing chlorine gas when the temperature drops below 30 °C; Step 3: Introduce nitrogen gas into the reactor to purge the dissolved chlorine gas and hydrogen chloride into the alkali solution for destruction treatment, and cool to room temperature to obtain a reaction mixture; Step 4: Distill off carbon tetrachloride under atmospheric pressure for recycling, and subject the remaining liquid to vacuum distillation. Collect the fraction under the conditions of 100 - 110 °C and 7.6 mmHg, and the product is the flame-retardant toluene diisocyanate derivative mixture M3.

[0026] Upon sampling and analysis, the molar ratio of the monochloride to the dichloride in M3 is 1.24:1.

[0027] Use M3 as the isocyanate component for foaming, and the method is the same as in Example 1.

[0028] When using toluene diisocyanate as the isocyanate component, the oxygen index of the obtained polyurethane flexible foam is 18%. When using M3 as the isocyanate component, the oxygen index of the obtained polyurethane flexible foam is 29%. Other foam mechanical properties are similar.

[0029] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flame retardant toluene diisocyanate derivative, characterized in that: The general structural formula of flame retardant toluene diisocyanate derivatives is: CH 3-n Cl n -Ar-(NCO)2, wherein Ar is a benzene ring and n is 1-2.

2. A flame retardant toluene diisocyanate derivative according to claim 1, characterized in that: The structural formula of the flame retardant toluene diisocyanate derivative is:

3. A method for preparing a flame retardant toluene diisocyanate derivative according to claim 1 or 2, characterized in that: The following steps are involved: Step 1: Add water-free toluene diisocyanate, initiator and carbon tetrachloride into a reactor and stir to mix evenly; Step 2: introducing chlorine gas without water into the reactor, and introducing the tail gas into the alkali liquid absorption device for absorption and destruction. When the chlorine gas fills the reactor, i.e. bubbles appear in the alkali liquid absorption device, heating is started, and the heating temperature is controlled to generate reflux to start the reaction. After the reaction is completed, heating is stopped, the temperature is lowered to below 30°C, and the introduction of chlorine gas is stopped; Step 3: introducing nitrogen into the reactor to purge the dissolved chlorine and hydrogen chloride into an alkali solution absorption device for destruction treatment, and then cooling the reactor to room temperature to obtain a reaction mixture; Step 4: Evaporate the carbon tetrachloride from the reaction mixture under normal pressure for recycling, and distill the remaining liquid under reduced pressure. Collect the fraction under 100-110°C and 7.6 mmHg to obtain the target product: flame-retardant toluene diisocyanate derivative.

4. The method for preparing a flame retardant toluene diisocyanate derivative according to claim 3, characterized in that: In step 1, the mass ratio of toluene diisocyanate to carbon tetrachloride is 6:100-15:100, wherein the purity of toluene diisocyanate is greater than 99%, and the content of 2,4-isomer is 80±1%.

5. The method for preparing a flame retardant toluene diisocyanate derivative according to claim 3, characterized in that: In step 1, the initiator is azobisisobutyronitrile, and the added amount is 1-1.5% of the mass of toluene diisocyanate.

6. The method for preparing a flame retardant toluene diisocyanate derivative according to claim 3, characterized in that: In step 2, the reaction time is 6-10 hours.

7. The use of a flame retardant toluene diisocyanate derivative according to claim 1, characterized in that: Applicable to the foaming of polyurethane soft foam; the specific method is as follows: under the ambient temperature of 22℃~25℃ and the raw material temperature of 22℃~25℃, add polyether polyol, silicone oil, water and amine catalyst in proportion to a mixing barrel and stir evenly, let it stand for 2~3 minutes, add tin catalyst, and then add flame-retardant toluene diisocyanate derivative to the mixing barrel, press the stopwatch to time, stir quickly for 5~7 seconds, quickly pour the mixed material into the foaming box for foaming, and cut it into required size after ripening.

8. The use of a flame retardant toluene diisocyanate derivative as claimed in claim 7, characterized in that: The polyether polyol, silicone oil, water, amine catalyst, tin catalyst, and flame retardant toluene diisocyanate derivative are as follows in parts by weight: 100 parts of polyether polyol; 1 part silicone oil; 4.2 parts water; 0.3 parts of amine catalyst; 0.15 parts of tin catalyst; 53.3 parts of flame retardant toluene diisocyanate derivative.

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