Amide group-containing polyurethane elastomers, processes for their preparation and uses thereof

Abstract

The application provides an amide-containing polyurethane elastomer and a preparation method and application thereof, and belongs to the field of high polymer materials. The application first provides an amide-containing chain extender, which is prepared from a diamine compound and a compound shown in formula I, a salt or a stereoisomer thereof. Then, the polyurethane elastomer is prepared by using the chain extender, and the polyurethane elastomer has excellent mechanical properties, and the water resistance, solvent resistance and oxidation resistance are significantly improved. In addition, the polyurethane elastomer is prepared by using a solvent-free preparation process, so that the use of organic solvents is avoided, the production environmental protection is improved, and the solvent recovery cost is reduced. Furthermore, the production process is simple, can be applied to large-scale industrial production, has high economic benefits and market competitiveness, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to an amide-containing polyurethane elastomer, its preparation method, and its uses. Background Technology

[0002] Polyurethane elastomers are widely used in footwear materials, coatings, sealants, adhesives, and other fields due to their excellent mechanical properties and processing adaptability. However, traditional polyurethane elastomers are prone to hydrolytic degradation in humid and hot environments, easily swell in highly polar solvents, and are susceptible to oxidation during long-term use, leading to a decline in mechanical properties and durability. Therefore, improving the water resistance, solvent resistance, and oxidation resistance of polyurethane elastomers to extend their service life has become an important research topic in current industrial applications.

[0003] In the synthesis of polyurethane, polyurethane elastomers can be divided into two main categories based on the type of oligomeric polyol: polyester-based and polyether-based. These two types of polyurethane elastomers exhibit significant differences in mechanical properties, solvent resistance, oxidation resistance, and water resistance due to the different soft segments. Polyester-based polyurethane elastomers, due to the strong polarity of the ester groups and the rigidity of the molecular chains, generally exhibit high mechanical strength and abrasion resistance, but their hydrolytic resistance is poor, and they are easily degraded in high-humidity environments. Polyether-based polyurethane elastomers, due to the stability of the ether bonds, have excellent water resistance, but their mechanical strength and oxidation resistance are relatively weaker.

[0004] Currently, the main technical solutions for improving the water resistance, oxidation resistance, and solvent resistance of polyurethane elastomers include the following: (1) using special end-capping agents to modify the end groups of polyurethane; (2) introducing nanofillers (such as nano silica or graphene) to improve the water resistance and oxidation resistance of polyurethane; (3) using aromatic diisocyanates (such as MDI) to replace aliphatic isocyanates to improve the oxidation resistance of polyurethane. However, existing technologies have many limitations. The process operation is complex: the scheme of using specially modified polyesters or end-capping treatment usually requires additional synthesis steps or post-processing, which increases the complexity and cost of the production process; the introduction of nanofillers requires a strict dispersion process to ensure the uniformity of the material, otherwise it may affect the mechanical properties and long-term stability. The scheme of using high-cost raw materials (such as special end-capping agents or nanofillers) or complex modification methods will significantly increase the material cost and affect its economic feasibility in large-scale industrial production. Some modification methods (such as end-capping or the introduction of special fillers) may lead to a decline in the overall performance of the material, making it difficult to meet the specific application requirements and affecting market competitiveness. Using aromatic diisocyanates to improve oxidation resistance may reduce the light stability of the material, limiting its outdoor applications.

[0005] Nonisocyanate polyurethane (NIPU) is a new generation of environmentally friendly polyurethane synthesized by the reaction of cyclic carbonate oligomers and primary amine oligomers. The hydroxycarbamate groups in NIPU can form intramolecular hydrogen bonds, giving it better hydrolysis resistance and mechanical properties than traditional polyurethanes. Currently, the main synthetic routes for NIPU include step-growth polymerization, polycondensation, rearrangement polymerization, and ring-opening polymerization. Among these, polycondensation, rearrangement polymerization, and ring-opening polymerization require the use of toxic substances such as phosgene and azide, which can easily lead to gas release and byproduct formation. Step-growth polymerization suffers from problems such as high reaction temperatures, incomplete reactions, and the large-scale use of organic solvents such as dimethylformamide. Therefore, NIPU preparation is environmentally unfriendly and unsuitable for industrial production.

[0006] Further research is needed to explore how to leverage the performance-enhancing effect of hydrogen bonds in non-isocyanate polyurethanes while addressing issues such as harsh reaction conditions, environmental unfriendliness, and unsuitability for industrial production in the preparation of non-isocyanate polyurethanes. Summary of the Invention

[0007] The purpose of this invention is to provide an amide-containing polyurethane elastomer, its preparation method, and its uses.

[0008] This invention provides an amide-containing chain extender, which is prepared from diamine compounds and compounds of Formula I, their salts, or their stereoisomers as raw materials:

[0009]

[0010] Wherein, R is selected from hydrogen, halogen, substituted or substituted C1-C4 alkyl; the substituents of the alkyl are independently selected from halogen and C1-C4 alkoxy groups.

[0011] Furthermore, the equivalence ratio of the diamine compound and the compound shown in Formula I, its salt or its stereoisomer is 1:(2-3).

[0012] Furthermore, R is selected from hydrogen, C1-C4 alkyl, fluorine, chlorine, bromine, -CH2F, -CH2Cl, -CH2OCH3;

[0013] Preferably, the compound represented by Formula I is ethylene carbonate.

[0014] Furthermore, the diamine compound is selected from one or more combinations of aliphatic diamine compounds or aromatic diamine compounds;

[0015] Preferably, the diamine compound is selected from one or more combinations of ethylenediamine, propylenediamine, butanediamine, hexamethylenediamine, diethyltoluenediamine, m-phenylenediamine, and p-phenylenediamine.

[0016] The present invention also provides a method for preparing the aforementioned chain extender, which includes the following steps:

[0017] (1) Melt the compound shown in Formula I, its salt or its stereoisomer, and then add a diamine compound to react;

[0018] (2) After the reaction is complete, the product is dried under reduced pressure to obtain the chain extender;

[0019] Preferably,

[0020] In step (1), the melting temperature is 60–80°C;

[0021] And / or, in step (1), the diamine compound is added by dripping or adding in batches;

[0022] And / or, in step (1), the reaction is to add a diamine compound and react at the melting temperature for 1 to 5 hours, and then raise the temperature to 100 to 120°C and hold for 5 to 10 hours;

[0023] And / or, in step (2), the reduced pressure drying is first distilled under reduced pressure at 90-120℃ for 1-3 hours, and then vacuum dried at 60-80℃ for 12-24 hours.

[0024] The present invention also provides the use of the aforementioned chain extender in the preparation of polyurethane elastomers.

[0025] The present invention also provides a polyurethane elastomer, which is prepared from diol, isocyanate, the aforementioned chain extender and catalyst as raw materials;

[0026] Preferably, the molar ratio of the diol, isocyanate, and the aforementioned chain extender is 10:(18-24):(8-14); the mass of the catalyst is 0.05-0.15 wt% of the total mass of the diol, isocyanate, and the aforementioned chain extender.

[0027] Furthermore,

[0028] The diol is selected from one or more combinations of polyether diols or polyester diols;

[0029] And / or, the isocyanate is selected from one or more combinations of diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate;

[0030] And / or, the catalyst is selected from one or more combinations of stannous octoate, zinc diethylhexanoate, and dibutyltin dilaurate;

[0031] Preferably,

[0032] The molecular weight of the diol is 500-2000;

[0033] More preferably,

[0034] The diol is selected from polytetrahydrofuran PTMG-2000 or polycaprolactone PCL-2000;

[0035] And / or, the isocyanate is selected from 4,4'-dicyclohexylmethane diisocyanate or diphenylmethane-4,4'-diisocyanate;

[0036] And / or, the catalyst is selected from dibutyltin dilaurate.

[0037] The present invention also provides a method for preparing the aforementioned polyurethane elastomer, which includes the following steps:

[0038] (1) Add the aforementioned chain extender to the diol and melt it;

[0039] (2) After melting, isocyanate and catalyst are added to react, and polyurethane elastomer is obtained after the reaction.

[0040] Preferably,

[0041] In step (1), the diol is a diol obtained by removing water under vacuum at 80-120°C;

[0042] And / or, in step (1), the temperature when the aforementioned chain extender is added is 80-120°C;

[0043] And / or, in step (1), the melting temperature is 80–160°C;

[0044] And / or, in step (2), the temperature of the reaction is 80-160°C.

[0045] The present invention also provides the use of the aforementioned polyurethane elastomer in the preparation of substrates for automotive parts, chemically resistant materials, and flexible electronic materials.

[0046] This invention not only draws on the role of hydrogen bonding in improving the properties of polyurethane elastomers in non-isocyanate polyurethanes, but also solves the problems of harsh reaction conditions, environmental unfriendliness, and unsuitability for industrial production in the preparation of non-isocyanate polyurethanes.

[0047] Specifically, the present invention achieves the following beneficial effects:

[0048] (1) Improved the water resistance of polyurethane elastomers

[0049] The amide groups are highly polar and can form a stable intermolecular network through hydrogen bonding, reducing the erosion of the polyurethane structure by water molecules and improving hydrolysis resistance. In humid environments, the hydrolysis rate of the polyurethane elastomer of this invention is significantly reduced, extending its service life.

[0050] (2) Improved solvent resistance of polyurethane elastomers

[0051] Because amide groups can increase the crosslinking density of polyurethane and improve the overall stability of the material, they enhance its resistance to polar solvents and reduce the swelling rate. The tensile strength retention rate of the material of this invention in both polar and non-polar solvents is significantly higher than that of traditional polyurethane elastomers.

[0052] (3) Improved oxidation resistance of polyurethane elastomers

[0053] Compared with traditional polyurethane elastomers, the polyurethane elastomer of this invention exhibits better retention and fewer cracks during thermo-oxidative aging.

[0054] (4) Improved the mechanical properties of polyurethane elastomers

[0055] The introduction of amide groups improves the compatibility of the polyurethane hard segments, resulting in higher strength, modulus, and wear resistance. While maintaining high toughness, the elongation at break and resilience are optimized, making it suitable for high-performance elastomer applications.

[0056] (5) Green environmental protection and economic feasibility

[0057] The solvent-free preparation process avoids the use of organic solvents, improving the environmental friendliness of production and reducing solvent recovery costs. The production process is simple, suitable for large-scale industrial production, and offers high economic benefits and market competitiveness.

[0058] In summary, this invention provides an amide-containing chain extender. Polyurethane elastomers prepared using this chain extender exhibit excellent mechanical properties, while their water resistance, solvent resistance, and oxidation resistance are significantly improved. Furthermore, this invention employs a solvent-free preparation process for the polyurethane elastomers, avoiding the use of organic solvents, improving the environmental friendliness of production, and reducing solvent recovery costs. Moreover, the production process of this invention is simple, suitable for large-scale industrial production, and possesses high economic benefits and market competitiveness, showing promising application prospects.

[0059] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0060] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Detailed Implementation

[0061] The raw materials and equipment used in the specific embodiments of the present invention are all known products, obtained by purchasing commercially available products.

[0062] In this invention, tetrahydrofuran PTMG-2000 is polytetrahydrofuran (PTMG) with an average molecular weight of approximately 2000; polycaprolactone PCL-2000 is polycaprolactone with an average molecular weight of approximately 2000; HMDI is 4,4'-dicyclohexylmethane diisocyanate; MDI is diphenylmethane-4,4'-diisocyanate; BDO ​​is 1,4-butanediol; and DBTDL is dibutyltin dilaurate.

[0063] Example 1: Preparation of the amide-containing polyurethane elastomer of the present invention

[0064] 1) Preparation of propylenediamine chain extender

[0065] Weigh 2.1 equivalents of ethylene carbonate into a reaction flask, heat to 60°C, and after it melts, add 1 equivalent of 1,3-propanediamine dropwise using a constant pressure dropping funnel over a period of 2 hours. After the addition is complete, react for about 2 hours, then heat to 100°C, and after the system melts, continue stirring for 8 hours. Then, remove unreacted monomers by vacuum distillation at 110°C for 3 hours. Finally, transfer the product to a 60°C oven and vacuum dry for 12 hours to obtain the target product (propanediamine chain extender).

[0066] 2) Preparation of polyurethane elastomers

[0067] In the raw materials for preparing polyurethane elastomers, the molar proportions of polytetrahydrofuran (PTMG-2000), propylenediamine chain extender, and HMDI are: 10 parts PTMG-2000, 10 parts propylenediamine chain extender, and 20 parts HMDI. The mass of the catalyst DBTDL is 0.1 wt% of the total mass of PTMG-2000, propylenediamine chain extender, and HMDI.

[0068] Ten parts of polytetrahydrofuran PTMG-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, the temperature was lowered to 100°C and 10 parts of propylenediamine chain extender were added. After melting, 20 parts of HMDI and 0.1 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until the viscosity increased to the point where it could not be stirred (about 2-5 minutes). After cooling, the target product (a polyurethane elastomer containing amide groups) was obtained.

[0069] Example 2: Preparation of the amide-containing polyurethane elastomer of the present invention

[0070] 1) Preparation of hexamethylenediamine chain extender

[0071] Weigh 2.1 equivalents of ethylene carbonate into a reaction flask, heat to 60°C, and after it melts, add 1 equivalent of 1,6-hexanediamine dropwise using a constant pressure dropping funnel over a period of 2 hours. After the addition is complete, the viscosity of the system increases after about 1 hour of reaction, changing from a fluid to a solid state. Heat to 100°C, and after the system melts, continue stirring for 8 hours. Remove unreacted monomers by vacuum distillation at 110°C for 3 hours, and then transfer the product to a 60°C oven for vacuum drying for 24 hours to obtain the target product (hexanediamine chain extender).

[0072] 2) Preparation of polyurethane elastomers

[0073] In the raw materials for preparing polyurethane elastomers, the molar proportions of polytetrahydrofuran (PTMG-2000), hexamethylenediamine chain extender, and HMDI are: 10 parts PTMG-2000, 14 parts hexamethylenediamine chain extender, and 24 parts HMDI. The mass of the catalyst DBTDL is 0.1 wt% of the total mass of PTMG-2000, hexamethylenediamine chain extender, and HMDI.

[0074] 10 parts of polytetrahydrofuran PTMG-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, the temperature was lowered to 100°C and 14 parts of hexamethylenediamine chain extender were added. After melting, 24 parts of HMDI and 0.1 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until no further stirring was possible (about 2-5 minutes). After cooling, the target product (amide-containing polyurethane elastomer) was obtained.

[0075] Example 3: Preparation of the amide-containing polyurethane elastomer of the present invention

[0076] 1) Preparation of diethyltoluene diamine chain extender

[0077] Weigh 2.1 equivalents of ethylene carbonate into a reaction flask, heat to 60°C, and after it melts, add 1 equivalent of 3,5-diethyl-2,6-diaminotoluene in three portions over 2 hours. After the addition is complete, react for about 2 hours, then heat to 100°C and maintain the temperature for 6 hours. Remove unreacted monomers by vacuum distillation at 110°C for 3 hours, and then transfer the product to a 60°C oven for vacuum drying for 12 hours to obtain the target product (diethyltoluene diamino chain extender).

[0078] 2) Preparation of polyurethane elastomers

[0079] In the raw materials for preparing polyurethane elastomers, the molar proportions of polytetrahydrofuran (PTMG-2000), diethyltoluene diamine chain extender, and HMDI are: 10 parts PTMG-2000, 10 parts diethyltoluene diamine chain extender, and 20 parts HMDI. The mass of the catalyst DBTDL is 0.1 wt% of the total mass of PTMG-2000, diethyltoluene diamine chain extender, and HMDI.

[0080] Ten parts of polytetrahydrofuran PTMG-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, ten parts of diethyltoluene diamine chain extender were added at 100°C. The temperature was raised to 150°C. After the diethyltoluene diamine chain extender melted, 20 parts of HMDI and 0.1 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until the viscosity increased to the point where it could not be stirred (2-5 min). After cooling, the target product (amide-containing polyurethane elastomer) was obtained.

[0081] Example 4: Preparation of the amide-containing polyurethane elastomer of the present invention

[0082] 1) Preparation of propylenediamine chain extender

[0083] Weigh 2.1 equivalents of ethylene carbonate into a reaction flask, heat to 60°C, and after it melts, add 1 equivalent of 1,3-propanediamine dropwise using a constant pressure dropping funnel over a period of 1 hour. After the addition is complete, react for about 2 hours, then heat to 100°C and continue stirring for 8 hours after the system melts. Remove unreacted monomers by vacuum distillation at 120°C for 2 hours, and then transfer the product to a 60°C oven for vacuum drying for 12 hours to obtain the target product (propanediamine chain extender).

[0084] 2) Preparation of polyurethane elastomers

[0085] In the raw materials for preparing polyurethane elastomers, the molar proportions of polycaprolactone (PCL-2000), propylene glycol chain extender, and HMDI are: 10 parts PCL-2000, 12 parts propylene glycol chain extender, and 22 parts HMDI. The mass of the catalyst DBTDL is 0.1 wt% of the total mass of PCL-2000, propylene glycol chain extender, and HMDI.

[0086] 10 parts of polycaprolactone PCL-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, the temperature was lowered to 100°C and 12 parts of propylene diamine chain extender were added. After melting, 22 parts of HMDI and 0.1 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until the viscosity increased to the point where it could not be stirred (about 2-5 minutes). After cooling, the target product (a polyurethane elastomer containing amide groups) was obtained.

[0087] Example 5: Preparation of the amide-containing polyurethane elastomer of the present invention

[0088] 1) Preparation of propylenediamine chain extender

[0089] Weigh 2.3 equivalents of ethylene carbonate into a reaction flask, heat to 60°C, and after it melts, add 1 equivalent of 1,3-propanediamine dropwise using a constant pressure dropping funnel over a period of 1.5 hours. After the addition is complete, react for about 3 hours, then heat to 100°C and continue stirring for 6 hours after the system melts. Remove unreacted monomers by vacuum distillation at 120°C for 2 hours, and then transfer the product to a 60°C oven for vacuum drying for 12 hours to obtain the target product (propanediamine chain extender).

[0090] 2) Preparation of polyurethane elastomers

[0091] The molar proportions of polytetrahydrofuran (PTMG-2000), propylenediamine chain extender, and MDI in the raw materials for preparing polyurethane elastomers are as follows: PTMG-2000 10 parts, propylenediamine chain extender 8 parts, and MDI 18 parts. The mass of the catalyst DBTDL is 0.06 wt% of the total mass of PTMG-2000, propylenediamine chain extender, and MDI.

[0092] Ten parts of polytetrahydrofuran PTMG-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, the temperature was lowered to 100°C and eight parts of propylenediamine chain extender were added. After melting, 18 parts of MDI and 0.06 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until the viscosity increased to the point where it could not be stirred (about 2-5 minutes). After cooling, the target product (a polyurethane elastomer containing amide groups) was obtained.

[0093] Comparative Example 1: Preparation of Polyurethane Elastomer

[0094] In the raw materials for preparing polyurethane elastomers, the molar proportions of polytetrahydrofuran (PTMG-2000), chain extender BDO, and HMDI are: 10 parts PTMG-2000, 10 parts BDO, and 20 parts HMDI. The mass of catalyst DBTDL is 0.1 wt% of the total mass of PTMG-2000, BDO, and HMDI.

[0095] Ten parts of polytetrahydrofuran PTMG-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, 10 parts of BDO were added. After melting, 20 parts of HMDI and 0.1 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until the viscosity increased to the point where it could not be stirred (about 2-5 minutes). After cooling, the target product (polyurethane elastomer) was obtained.

[0096] Comparative Example 2: Preparation of Polyurethane Elastomer

[0097] In the raw materials for preparing polyurethane elastomers, the molar proportions of polycaprolactone (PCL-2000), chain extender BDO, and HMDI are: 10 parts PCL-2000, 10 parts BDO, and 20 parts HMDI. The mass of the catalyst DBTDL is 0.1 wt% of the total mass of PCL-2000, BDO, and HMDI.

[0098] Ten parts of polycaprolactone PCL-2000 (0.1 mol) were added to a three-necked flask. After removing water at 120°C under vacuum for 2 hours, 10 parts of BDO were added. After melting, 20 parts of HMDI and 0.1 wt% of DBTDL were added. The temperature was raised to 160°C and stirred until the viscosity increased to the point where it could not be stirred (about 2-5 minutes). After cooling, the target product (polyurethane elastomer) was obtained.

[0099] The following specific experimental examples demonstrate the beneficial effects of the present invention.

[0100] Performance testing of polyurethane elastomers in Test Example 1, Examples 1-5 and Comparative Examples 1-2

[0101] The polyurethane elastomers of Examples 1-5 and Comparative Examples 1-2 were subjected to the following tests:

[0102] 1) Tensile strength and elongation at break test: The tensile properties of dumbbell-shaped polyurethane elastomer specimens were measured according to ASTM D412 standard.

[0103] 2) Double 85 test: After storing dumbbell-shaped polyurethane elastomer samples in a double 85 environment (humidity: 85%, temperature: 85℃) for 7 days, the tensile properties are tested according to ASTM D412 standard.

[0104] 3) Thermo-oxidative aging test: Dumbbell-shaped polyurethane elastomer specimens were placed in a 100°C hot air circulating oven and exposed for 7 days according to ASTM D573 standard for thermo-oxidative aging test. After the test, the tensile properties were tested according to ASTM D412 standard.

[0105] 4) Solvent Resistance Test: Following ASTM D412, evaluate the change in tensile properties of polyurethane elastomer samples after solvent immersion. Solvent selection: ① Polar solvents: methanol, acetone; ② Non-polar solvents: toluene. Immersion test: Tensile properties are tested after immersion at 25℃±2℃ for 5 days.

[0106] The tensile strength retention rate under each test condition is calculated using the following formula:

[0107]

[0108] Table 1. Performance test results of polyurethane elastomers in Examples 1-5 and Comparative Examples 1-2

[0109]

[0110]

[0111] Note: / indicates that the test piece is damaged and performance cannot be tested.

[0112] The results in Table 1 show that:

[0113] (1) Compared with the comparative example, the polyurethane elastomers containing amide groups prepared in the examples have higher hydrogen bonding effects and their mechanical strength is improved. Among them, the polyurethane elastomers prepared in Examples 3 and 4 have higher tensile strength.

[0114] (2) Under high temperature and high humidity conditions, the tensile strength retention rate of the polyurethane elastomer prepared using BDO as a chain extender in the comparative example decreased rapidly, while the tensile strength retention rate of the polyurethane elastomer containing amide groups prepared in the examples was high, especially the polyurethane elastomer prepared in Example 3. This indicates that the polyurethane elastomers prepared in the examples have good water resistance.

[0115] (3) During thermo-oxidative aging, the tensile strength retention rate of the polyurethane elastomer prepared in the comparative example decreased rapidly, while the tensile strength retention rate of the polyurethane elastomer containing amide groups prepared in the examples was high, especially the polyurethane elastomer prepared in Example 3. This indicates that the polyurethane elastomers prepared in the examples have good oxidation resistance.

[0116] (4) Compared with the comparative examples, the polyurethane elastomers containing amide groups prepared in the examples showed significantly better solvent resistance in both polar and non-polar solvents. Among them, the polyurethane elastomer prepared in Example 3 (containing aromatic amine chain extender) exhibited a high tensile strength retention rate. This indicates that the polyurethane elastomers prepared in the examples have good solvent resistance.

[0117] The above results indicate that polyurethane elastomers prepared using conventional chain extenders exhibit poor mechanical properties, as well as poor water resistance, solvent resistance, and oxidation resistance, resulting in rapid performance degradation after aging. The polyurethane elastomers prepared using chain extenders containing amide groups in this invention not only show significantly improved mechanical properties but also significantly enhanced water resistance, solvent resistance, and oxidation resistance. Among these, the polyurethane elastomer prepared in Example 3 demonstrates the best overall performance.

[0118] In summary, this invention provides an amide-containing chain extender. Polyurethane elastomers prepared using this chain extender exhibit excellent mechanical properties, while their water resistance, solvent resistance, and oxidation resistance are significantly improved. Furthermore, this invention employs a solvent-free preparation process for the polyurethane elastomers, avoiding the use of organic solvents, improving the environmental friendliness of production, and reducing solvent recovery costs. Moreover, the production process of this invention is simple, suitable for large-scale industrial production, and possesses high economic benefits and market competitiveness, showing promising application prospects.

Claims

1. A polyurethane elastomer, characterized in that: It is prepared from diols, isocyanates, chain extenders and catalysts; The preparation method includes the following steps: (1) Add a chain extender to the diol and melt it; (2) After melting, isocyanate and catalyst are added to react, and polyurethane elastomer is obtained after the reaction; The chain extender is prepared from diamine compounds and compounds of Formula I, their salts, or their stereoisomers as raw materials. Formula I The preparation method of the chain extender includes the following steps: (1) Melt the compound shown in Formula I, its salt or its stereoisomer, and then add a diamine compound to react; (2) After the reaction is completed, the product is dried under reduced pressure to obtain the chain extender; In step (1), the diamine compound is added by dripping or adding it in batches; The diamine compound is selected from one or more combinations of propylenediamine, hexamethylenediamine, and diethyltoluenediamine; the compound represented by Formula I is ethylene carbonate.

2. The polyurethane elastomer according to claim 1, characterized in that: The molar ratio of the diol, isocyanate, and chain extender is 10:(18~24):(8~14); the mass of the catalyst is 0.05~0.15wt% of the total mass of the diol, isocyanate, and chain extender.

3. The polyurethane elastomer according to claim 2, characterized in that: The diol is selected from one or more combinations of polyether diols or polyester diols; And / or, the isocyanate is selected from one or more combinations of diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; And / or, the catalyst is selected from one or more combinations of stannous octoate, zinc diethylhexanoate, and dibutyltin dilaurate.

4. The polyurethane elastomer according to claim 3, characterized in that: The molecular weight of the diol is 500-2000.

5. The polyurethane elastomer according to claim 4, characterized in that: The diol is selected from polytetrahydrofuran PTMG-2000 or polycaprolactone PCL-2000; And / or, the isocyanate is selected from 4,4'-dicyclohexylmethane diisocyanate or diphenylmethane-4,4'-diisocyanate; And / or, the catalyst is selected from dibutyltin dilaurate.

6. The polyurethane elastomer according to claim 1, characterized in that: The equivalent ratio of the diamine compound and the compound shown in Formula I, its salt or its stereoisomer is 1:(2~3).

7. The polyurethane elastomer according to claim 1, characterized in that: In step (1), the melting temperature is 60~80℃; And / or, in step (1), the reaction is to add a diamine compound and react at the melting temperature for 1-5 h, then raise the temperature to 100-120°C and hold for 5-10 h; And / or, in step (2), the reduced pressure drying is first distilled under reduced pressure at 90-120℃ for 1-3 hours, and then vacuum dried at 60-80℃ for 12-24 hours.

8. The method for preparing the polyurethane elastomer according to any one of claims 1 to 7, characterized in that: It includes the following steps: (1) Add a chain extender to the diol and melt it; (2) After melting, isocyanate and catalyst are added to react, and polyurethane elastomer is obtained after the reaction.

9. The preparation method according to claim 8, characterized in that: In step (1), the diol is a diol obtained by removing water under vacuum at 80~120℃; And / or, in step (1), the temperature when the chain extender is added is 80~120℃; And / or, in step (1), the melting temperature is 80~160℃; And / or, in step (2), the temperature of the reaction is 80-160°C.

10. Use of the polyurethane elastomer according to any one of claims 1 to 7 in the preparation of substrates for automotive parts, chemically resistant materials, and flexible electronic materials.

Images