A trifluoromethyl-containing polyurethane material, and methods of making and using the same

Abstract

The application discloses a trifluoromethyl-containing polyurethane material and a preparation method and application thereof. Trifluoromethyl TDI is obtained by introducing trifluoromethyl into TDI, and is polymerized with different double-hydroxyl-containing polymers to prepare a polyurethane material. The mechanical properties of the polyurethane are effectively improved through trifluoromethylation, thereby prolonging the service life of the polyurethane. The polyurethane prepared by the application has higher tensile strength, higher toughness, good uniformity, excellent comprehensive performance, higher reliability and longer service life than TDI, and has important significance and development value for widening the application of the polyurethane material in the fields of aerospace, automobiles, textiles, buildings, medical treatment, intelligent detection and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyurethane materials, and relates to a trifluoromethyl-containing polyurethane material and a preparation method thereof. BACKGROUND

[0002] Solid propellant is the power source of solid rocket and missile launch, and is an important material basis for realizing long-range attack. At the same time, solid propellant is the basic technology, key technology and core technology of rocket, missile and other weapon equipment. The performance of solid propellant directly affects the maneuvering speed and ability of the rocket and missile system, and determines its survivability and combat effectiveness. Among them, composite solid propellant is a dense material that can burn regularly and produce high-temperature and high-pressure gas without relying on atmospheric oxygen, mainly composed of binder, oxidizer and high-performance fuel. In the formula of composite solid propellant, the binder system (including high molecular pre-polymer, curing agent, chain extender and crosslinking agent, etc.) accounts for about 10% of the mass fraction of the whole formula. It is the matrix or continuous phase in the composite solid propellant, which makes other components uniformly dispersed therein, plays the role of adhesion and bearing solid filler components, and provides energy for the propellant as fuel. Therefore, it is different from the general adhesive (adhesive). The latter is a substance that connects two structural components of the same or different materials together through adhesion, also known as glue. The performance of the binder system often directly determines the level of performance of the composite solid propellant, and is an important reference index for the design, process preparation, long-term storage and main symbol for updating of solid propellant formula. Therefore, the binder for composite solid propellant must meet the performance requirements of high energy, low viscosity, low glass transition temperature, excellent mechanical properties and thermal stability, and good compatibility with other components.

[0003] The binder is the basis of the comprehensive performance of the composite solid propellant, and directly determines the mechanical properties, storage performance, combustion performance and insensitivity of the composite solid propellant. The composite solid propellant is subjected to various mechanical and environmental loads in the links of production, transportation, use and long-term storage, so that the inside of the propellant grain is subjected to various periodic stress and strain. If these changes exceed the allowable range of the corresponding performance (such as tensile strength and elongation at break), the composite solid propellant grain may be deformed excessively or even broken, which seriously threatens the safety performance of the propellant in storage and use. The composite solid propellant with excellent mechanical properties can absorb the energy of various mechanical and environmental loads, thereby reducing the risk of damage and sensitivity of the composite solid propellant grain. Therefore, improving the mechanical properties of the propellant is one of the important tasks in the research of composite solid propellant. With the continuous development of new high-performance weapon equipment systems, higher requirements are put forward for the mechanical properties of composite propellant, and further improvement is urgently needed. Among them, the polyurethane (PU) binder is a commonly used binder system in composite propellant.

[0004] Polyurethane is a general term for polymers with urethane bonding groups, which is formed by the combination reaction of isocyanate groups with compounds having active hydrogen such as hydroxyl groups, and was first synthesized by Bayer in 1937. Polyurethane mainly includes two categories of polyester and polyether, and can be made into polyurethane plastics (mainly foam plastics), polyurethane fibers (spandex), polyurethane rubber and elastomers. Polyurethane appeared in the 1930s, and after nearly eight decades of technological development, it has been widely used in national defense, aerospace, light industry, chemical industry, petroleum, textile, transportation, automobile, medical treatment and other fields. Polyurethane has the elasticity of rubber, the strength of plastic and excellent processing performance, and has advantages over other synthetic materials in terms of heat insulation, sound insulation, wear resistance, oil resistance and elasticity. It is the sixth largest plastic after polyethylene, polyvinyl chloride, polypropylene, polystyrene and polyacrylonitrile-butadiene-styrene resin (ABS), and has become an indispensable new material for economic development and people's life.

[0005] The current way of introducing fluorine into the structure of polyurethane can be divided into hard segment fluorine modification and soft segment fluorine modification, and there are three main methods. One is to modify the isocyanate monomer, the second is to use fluorine-containing diols as chain extenders, and the third is to modify the soft segment polymer polyol. The most reported is the synthesis and modification of fluorine-containing polyether polyol. From the overall preparation technology of fluorine-containing polyether, there are still problems such as long preparation route, harsh process conditions and high cost. So far, it is still difficult to industrialize. There are few reports on the fluorine modification of polyester polyol. First, the monomers of fluorine-containing diacids and fluorine-containing diols that can be used for polymerization are relatively expensive. Second, the monomer activity is low, the polymer structure and molecular weight are difficult to control, and the batch stability is poor. Only solvent method can be used for preparation, and the removal of subsequent solvents not only increases the complexity of the process and the cost of the product, but also harms the human body and the environment. Therefore, although the performance of fluorine-containing polyester polyurethane elastomer is much better than that of fluorine-containing polyether polyurethane elastomer, it is also difficult to be large-scale industrialized. Although the fluorine content in the polyurethane material is not too high, the tensile strength of the polyurethane material made by fluorine modification of isocyanate monomer is improved while maintaining the original extension performance. At present, common diisocyanates include toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenyl methane diisocyanate (MDI), dicyclohexyl methane diisocyanate (HMDI), hexamethylene diisocyanate (HDI) and the like. Among them, TDI has the characteristics of simple structure, easy modification, multiple modification sites, rich series of derived products, excellent performance and the like.

[0006] Due to the defects of the further improved performance of the TDI made polyurethane elastomer, the uncontrollable reaction rate and the like, the application range is limited, the market share is under the pressure of sharp decline, therefore, it is particularly necessary to modify the TDI by using the fluorine atom, improve the performance of the TDI material, and solve the difficulties faced by the TDI. SUMMARY

[0007] In view of the problems in the prior art, the purpose of the present application is to provide a trifluoromethyl-containing polyurethane material, a preparation method and application thereof, to solve the technical problems of limited improvement of mechanical properties of TDI-based polyurethane materials, narrow application scenarios and the like.

[0008] To solve the above technical problems, the present application adopts the following technical solutions:

[0009] A preparation method of a trifluoromethyl-containing polyurethane material, the reaction equation is:

[0010]

[0011] Among them, is a dihydric alcohol polymer, including HTPB, GAP and HTPE;

[0012] The structural formula of HTPB, GAP and HTPE is as follows:

[0013]

[0014] The present application also includes the following technical features:

[0015] Specifically, the method uses dihydric alcohol polymer and trifluoromethyl TDI as reaction raw materials, and carries out polymerization reaction under stirring of catalyst in organic solvent, and the reaction solvent is extracted, the reaction is loaded into polytetrafluoroethylene mold, degassed at room temperature, and cured.

[0016] Specifically, the catalyst is one of dibutyltin dilaurate, dimethylcyclohexylamine and triphenyl bismuth.

[0017] Specifically, the organic solvent is one of dichloromethane, tetrahydrofuran and ethyl acetate.

[0018] Specifically, the curing reaction temperature is 25-80 DEG C, and the time is 72-120 h.

[0019] Specifically, the molar ratio of dihydric alcohol polymer, trifluoromethyl TDI and catalyst is 1:(0.8-1.2):0.01.

[0020] A trifluoromethyl-containing polyurethane material is prepared by the preparation method of the trifluoromethyl-containing polyurethane material.

[0021] Use of the trifluoromethyl-containing polyurethane material as a binder of composite solid propellant.

[0022] Compared with the prior art, the present application has the following technical effects:

[0023] (I) The present application first modifies the polyurethane by trifluoromethylation, expands the types of polyurethane materials, realizes the simple preparation of polyurethane materials, is compatible with the preparation process of propellants, lays a material foundation for material application.

[0024] (II) The present application is easy to control the curing reaction rate during the curing process, the appearance of the sample strip is flat, the uniformity is good, and the rate is controllable.

[0025] (III) The trifluoromethyl TDI material prepared by the present application has higher tensile strength and elongation at break than TDI material, shows high tensile strength and high toughness, has good uniformity, excellent comprehensive performance, higher reliability and longer service life.

[0026] (IV) The fluorine-containing polyurethane material prepared by the present application can effectively block the penetration of air and water, delay the oxidation of Al powder in the composite propellant, and also can stimulate the pre-combustion heat release reaction on the surface of the aluminum oxide shell. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Dumbbell-shaped sample for mechanical property test.

[0028] Figure 2 Comparison chart of adhesive films for example 1 and comparative example 1. DETAILED DESCRIPTION

[0029] The application provides a trifluoromethyl-containing polyurethane material and a preparation method and application thereof, wherein fluorine atoms have strong electronegativity, high C-F bond energy (540 kJ / mol), the smallest van der Waals radius except hydrogen, and shielding and protection effects of fluorine on carbon chains, which endow fluorine-containing polymers with superior thermal stability, weather resistance and chemical inertness, and unique low surface free energy, low friction coefficient, low refractive index, low dielectric constant and low power factor, and the low surface energy and low friction coefficient of the fluorine-containing polymers also make the fluorine-containing polymers have outstanding hydrophobic and oleophobic properties and anti-adhesion properties. The introduction of fluorine-containing groups into polyurethane can combine the excellent mechanical properties and two-phase microstructure characteristics of polyurethane, and greatly improve the surface properties and overall properties of polyurethane. This is mainly because: ① the C-F bond has special properties, which can affect the physical and chemical properties of organic molecules; ② the C-F bond has high strength, so the metabolism of fluorinated active sites is inhibited; ③ the strong electronegativity of fluorine will greatly affect the properties of other functional groups in the molecule. Compared with conventional polyurethane, the fluorine-containing polyurethane can improve the levels of heat resistance, water resistance, radiation resistance, chemical resistance and low friction coefficient and other aspects of the new structure on the premise of maintaining the original properties of polyurethane, thereby greatly expanding the application field of the new structure polyurethane, especially in some high-end military and medical industries. At the same time, the introduction of fluorine atoms can increase the intermolecular forces of polyurethane chains and improve the mechanical properties of the material, providing a new idea for improving the mechanical properties and stability of composite propellants.

[0030] The preparation method of the trifluoromethyl-containing polyurethane material provided by the application is as follows:

[0031]

[0032] Among them, The dihydric alcohol polymer includes HTPB, GAP and HTPE;

[0033] The structures of HTPB, GAP and HTPE are as follows:

[0034]

[0035] The method uses dihydric alcohol polymer and trifluoromethyl TDI as reaction raw materials, and performs polymerization reaction in an organic solvent under stirring of a small amount of catalyst, the reaction solvent is extracted and dried, the reaction material is loaded into a polytetrafluoroethylene mold, degassing is performed at room temperature for 20 minutes, and then the material is cured at a certain temperature for a certain time, demolding is performed, and dumbbell-shaped samples are cut for mechanical property testing.

[0036] The catalyst is one of dibutyltin dilaurate, dimethylcyclohexylamine and triphenyl bismuth;

[0037] The organic solvent is one of dichloromethane, tetrahydrofuran and ethyl acetate;

[0038] The curing reaction temperature is 25-80 DEG C, and the time is 72-120 h.

[0039] The molar ratio of dihydric alcohol polymer, trifluoromethyl TDI and catalyst is 1:(0.8-1.2):0.01.

[0040] Application of trifluoromethyl-containing polyurethane material as binder of composite solid propellant.

[0041] The synthesis method of the raw material trifluoromethyl TDI is as follows: trifluoromethyl DNT is used as the reaction raw material, under the action of transition metal catalyst and ligand, one-step reaction is carried out with isocyanate base raw material under certain conditions, and trifluoromethyl TDI is obtained by recrystallization and distillation. The reaction equation is as follows:

[0042]

[0043] Specifically, the following steps are included: under nitrogen protection, trifluoromethyl DNT, isocyanate base raw material, transition metal catalyst and ligand and base are added into a reaction container, vacuum is extracted and nitrogen is filled three times; a syringe is used to add solvent, oil bath heating is carried out, after reaction, cooling is carried out at room temperature, TLC monitoring is carried out, vacuum filtration is carried out, and TDI product is obtained by distillation separation. The transition metal catalyst is any one of Pd(acac)2, Pd(OAc)2, Pd2(dba)3, Pd(TFA)2, Pd2(allyl)2Cl2, Ni(COD)2 and NiCl2(PCy3)2. The ligand is any one of BrettPhos, IPr, IMes, SIMes, XPhos, RuPhos, DPPF, PCy3 and BINAP. The isocyanate base raw material is one of NaOCN, KOCN, AgOCN and NH4OCN. The solvent is any one of toluene, xylene, dioxane and trifluorotoluene. The base is any one of potassium tert-butoxide, lithium tert-butoxide, sodium ethoxide, anhydrous potassium phosphate, potassium carbonate, cesium carbonate, potassium acetate, potassium tert-pentanoate and cesium fluoride. The reaction temperature is 80-150 DEG C, and the time is 12-48 h. The mass ratio of isocyanate base raw material, catalyst and ligand is 1:(0.01-0.5):(0.01-0.8). Preferably, the synthesis method of trifluoromethyl TDI includes: under nitrogen protection, 0.5 mmol of trifluoromethyl DNT, 2 mmol of NaOCN, 10 mol% of Pd2(allyl)2Cl2, 25 mol% of RuPhos, 1.5 mmol of potassium acetate are added, vacuum is extracted and nitrogen is filled three times; a syringe is used to add 3 mL of dioxane, oil bath heating is carried out to 150 DEG C, and reaction is carried out for 24 h; cooling is carried out at room temperature, TLC monitoring is carried out, vacuum filtration is carried out, and light yellow solid trifluoromethyl TDI is obtained by distillation separation.

[0044] The following gives specific embodiments of the present application, it is to be noted that the present application is not limited to the following specific embodiments, any equivalent transformation made on the basis of the technical scheme of the present application falls within the protection scope of the present application.

[0045] Example 1:

[0046] The present embodiment provides a kind of trifluoromethyl-containing polyurethane material and preparation method thereof, 15g HTPB is added into 100mL beaker, 1.21g trifluoromethyl TDI and 10mL dichloromethane or tetrahydrofuran or ethyl acetate are dissolved, 0.0015g dibutyltin dilaurate or dimethylcyclohexylamine or triphenyl bismuth is added, stirring 15min, vacuum removal solvent and bubble, the reaction is poured into polytetrafluoroethylene mold, vacuum exhaust 30min, then in 70 ℃ oven curing 3 days.After demolding, the dumbbell-shaped sample is cut according to GB / T 528-2009 for mechanical property test.

[0047] Example 2:

[0048] The present embodiment provides a kind of trifluoromethyl-containing polyurethane material and preparation method thereof, 15g HTPB is added into 100mL beaker, 1.21g trifluoromethyl TDI and 10mL dichloromethane or tetrahydrofuran or ethyl acetate are dissolved, 0.0015g dibutyltin dilaurate or dimethylcyclohexylamine or triphenyl bismuth is added, stirring 15min, vacuum removal solvent and bubble, the reaction is poured into polytetrafluoroethylene mold, vacuum exhaust 30min, then in 70 ℃ oven curing 3 days.After demolding, the dumbbell-shaped sample is cut according to GB / T 528-2009 for mechanical property test.

[0049] Example 3:

[0050] The present embodiment provides a kind of trifluoromethyl-containing polyurethane material and preparation method thereof, 15g HTPB is added into 100mL beaker, 1.21g trifluoromethyl TDI and 10mL dichloromethane or tetrahydrofuran or ethyl acetate are dissolved, 0.0015g dibutyltin dilaurate or dimethylcyclohexylamine or triphenyl bismuth is added, stirring 15min, vacuum removal solvent and bubble, the reaction is poured into polytetrafluoroethylene mold, vacuum exhaust 30min, then in 70 ℃ oven curing 3 days.After demolding, the dumbbell-shaped sample is cut according to GB / T 528-2009 for mechanical property test.

[0051] Comparative Example 1:

[0052] Into a 100 mL beaker, 15 g HTPB, 0.87 g TDI and 10 mL dichloromethane or tetrahydrofuran or ethyl acetate were added for dissolution, 0.0015 g dibutyl tin dilaurate or dimethyl cyclohexylamine or triphenyl bismuth was added, stirred for 15 min, vacuumed to remove solvent and bubbles, the reactants were poured into a polytetrafluoroethylene mold, vacuumed and degassed for 30 min, then cured in a 70 °C oven for 3 days. After demolding, the dumbbell-shaped sample was cut with a cutting knife for mechanical property testing according to GB / T 528-2009.

[0053] Comparative Example 2:

[0054] Into a 100 mL beaker, 15 g HTPB, 0.96 g 4-FTDI and 10 mL dichloromethane or tetrahydrofuran or ethyl acetate were added for dissolution, 0.0015 g dibutyl tin dilaurate or dimethyl cyclohexylamine or triphenyl bismuth was added, stirred for 15 min, vacuumed to remove solvent and bubbles, the reactants were poured into a polytetrafluoroethylene mold, vacuumed and degassed for 30 min, then cured in a 70 °C oven for 3 days. After demolding, the dumbbell-shaped sample was cut with a cutting knife for mechanical property testing according to GB / T 528-2009.

[0055] Comparative Example 3:

[0056] Into a 100 mL beaker, 15 g GAP, 1.14 g TDI and 10 mL dichloromethane or tetrahydrofuran or ethyl acetate were added for dissolution, 0.0015 g dibutyl tin dilaurate or dimethyl cyclohexylamine or triphenyl bismuth was added, stirred for 15 min, vacuumed to remove solvent and bubbles, the reactants were poured into a polytetrafluoroethylene mold, vacuumed and degassed for 30 min, then cured in a 50 °C oven for 5 days. After demolding, the dumbbell-shaped sample was cut with a cutting knife for mechanical property testing according to GB / T 528-2009.

[0057] Comparative Example 4:

[0058] Into a 100 mL beaker, 15 g GAP, 1.26 g 4-FTDI and 10 mL dichloromethane or tetrahydrofuran or ethyl acetate were added for dissolution, 0.0015 g dibutyl tin dilaurate or dimethyl cyclohexylamine or triphenyl bismuth was added, stirred for 15 min, vacuumed to remove solvent and bubbles, the reactants were poured into a polytetrafluoroethylene mold, vacuumed and degassed for 30 min, then cured in a 50 °C oven for 5 days. After demolding, the dumbbell-shaped sample was cut with a cutting knife for mechanical property testing according to GB / T 528-2009.

[0059] Comparative Example 5:

[0060] Into a 100 mL beaker, 15 g HTPE, 1.15 g TDI and 10 mL dichloromethane or tetrahydrofuran or ethyl acetate were added for dissolution, 0.0015 g dibutyl tin dilaurate or dimethylcyclohexylamine or triphenyl bismuth was added, stirred for 15 min, vacuumed to remove solvent and bubbles, the reaction was poured into a polytetrafluoroethylene mold, vacuumed for 30 min, and then cured in a 50 °C oven for 5 days. After demolding, the dumbbell-shaped sample was cut with a cutting knife and the mechanical properties were tested according to GB / T 528-2009.

[0061] Comparative Example 6:

[0062] Into a 100 mL beaker, 15 g HTPE, 1.27 g 4-FTDI and 10 mL dichloromethane or tetrahydrofuran or ethyl acetate were added for dissolution, 0.0015 g dibutyl tin dilaurate or dimethylcyclohexylamine or triphenyl bismuth was added, stirred for 15 min, vacuumed to remove solvent and bubbles, the reaction was poured into a polytetrafluoroethylene mold, vacuumed for 30 min, and then cured in a 50 °C oven for 5 days. After demolding, the dumbbell-shaped sample was cut with a cutting knife and the mechanical properties were tested according to GB / T 528-2009.

[0063] Mechanical property test

[0064] The CMT 6303 electronic universal testing machine was used to test the mechanical properties of the cut sample, the test standard was GB / T 528-2009, the sample was dumbbell-shaped, as shown in Figure 1 , the test section size was 25 mm*6 mm*2 mm. The specific mechanical property results are shown in Table 1 below. Figure 2 The film comparison of Example 1 (left) and Comparative Example 1 (right) shows that the polyurethane prepared based on trifluoromethyl TDI is smoother and more uniform, and is not easy to produce bubbles, indicating that the polymerization process is more stable and the rate is controllable.

[0065] Table 1 Mechanical property results

[0066]

Claims

1. A process for the preparation of a trifluoromethyl-containing polyurethane material, characterized in that, The reaction equation is: wherein, are dihydric alcohol polymers including HTPB, GAP and HTPE; The structural formula of HTPB, GAP and HTPE is as follows:

2. The method of making a trifluoromethyl-containing polyurethane material of claim 1, wherein, The method uses dihydric alcohol polymer and trifluoromethyl TDI as reaction raw materials, carries out polymerization reaction in organic solvent under stirring of catalyst, extracts dry reaction solvent, loads the reaction into polytetrafluoroethylene mold, degasses at room temperature, carries out solidification reaction, and demolds.

3. The method of making a trifluoromethyl-containing polyurethane material of claim 2, wherein, The catalyst is one of dibutyl tin dilaurate, dimethylcyclohexylamine and triphenyl bismuth.

4. The method of making a trifluoromethyl-containing polyurethane material of claim 2, wherein, The organic solvent is one of dichloromethane, tetrahydrofuran and ethyl acetate.

5. The method of making a trifluoromethyl-containing polyurethane material of claim 2, wherein, The solidification reaction temperature is 25-80 DEG C, and the time is 72-120h.

6. The method of making a trifluoromethyl-containing polyurethane material of claim 2, wherein, The molar ratio of dihydric alcohol polymer, trifluoromethyl TDI and catalyst is 1:(0.8-1.2):0.

01.

7. A trifluoromethyl-containing polyurethane material, characterized in that, The preparation method of the trifluoromethyl-containing polyurethane material is prepared by the preparation method of any one of claims 1-6.

8. The trifluoromethyl-containing polyurethane material of claim 7 as an adhesive of composite solid propellant.

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