Diamine chain extender for two-component polyurethane resins and method for its preparation
By using a simple and efficient "one-pot two-step" synthesis route, a structurally symmetrical diamine chain extender is generated, which solves the health risks and performance bottlenecks of existing diamine chain extenders, and improves the tensile strength and tear resistance of high-performance polyurethane materials. The process is simple and safe.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU JICUI PHOTOSENSITIVE ELECTRONIC MATERIAL RES INST CO LTD
- Filing Date
- 2026-02-26
- Publication Date
- 2026-06-02
AI Technical Summary
Existing diamine chain extenders pose health risks and performance bottlenecks in high-end elastomer applications. They are difficult to maintain high tensile strength and tear resistance under long-term dynamic loads, and their synthesis routes are complex and environmentally unfriendly.
A simple and efficient "one-pot two-step" synthesis route is adopted, which utilizes isocyanate and dihydroxy compound to generate terminal isocyanate group prepolymer, and then reacts with dihydrazide to generate structurally symmetrical diamine chain extender, avoiding high-risk raw materials and with mild reaction conditions.
The prepared diamine chain extender has a highly symmetrical molecular structure and can form a high-density hydrogen bond network, which significantly improves the tensile strength, elongation at break and tear resistance of polyurethane materials. The process is simple and safe.
Smart Images
Figure CN122127253A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer material synthesis technology, and particularly relates to a diamine chain extender for two-component polyurethane resin and its preparation method. Background Technology
[0002] Chain extenders are key additives in the synthesis of high-performance polymers, especially polyurethane materials. Their role is to connect prepolymer molecular chains, significantly improving the molecular weight, hardness, tensile strength, modulus, and heat distortion temperature of the final product. Among numerous chain extenders, aromatic diamines containing amide bonds and symmetrical structures have become a research hotspot due to their ability to impart excellent rigidity, heat resistance, and dimensional stability to materials. Currently, widely used industrial diamine chain extenders such as MOCA (3,3'-dichloro-4,4'-diaminodiphenylmethane) exhibit excellent performance, but pose potential health risks and environmental pressures. In high-end elastomer applications, such as high-performance footwear, where extreme requirements for abrasion resistance, mechanical strength, and fatigue resistance are present, existing polyurethane systems based on traditional diamine chain extenders like MOCA often face performance bottlenecks. Although these chain extenders can form basic urea bond structures, the density of hydrogen bond networks that can be formed in their molecular backbone is limited, and their action mode is singular. This results in insufficient phase separation and poor structural regularity in the polymer's hard segment microregions, making it difficult to support materials maintaining ultra-high tensile strength, excellent tear resistance, and low permanent deformation under long-term dynamic loads. To overcome this limitation, there is an urgent need to design a new type of diamine chain extender whose molecular structure is rich in both amide and urea bonds, and which can construct a high-density, multi-layered and uniformly distributed hydrogen bond physical cross-linking network in the polymer matrix through a highly symmetrical aromatic skeleton arrangement.
[0003] In recent years, researchers have developed various novel diamine chain extenders in search of safer and more environmentally friendly alternatives. However, existing synthetic routes often involve highly toxic raw materials (such as phosgene), complex reaction steps, or asymmetrical product structures leading to uneven dispersion in the polymer matrix, affecting the uniformity of material properties. Therefore, developing a new method for preparing diamine chain extenders that uses safe raw materials, has a simple process, and can be efficiently achieved is of great significance for promoting the application of high-performance and environmentally friendly polymer materials. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a diamine chain extender for two-component polyurethane resins.
[0005] The present invention also provides a method for preparing a diamine chain extender for a two-component polyurethane resin.
[0006] Based on the high reactivity of isocyanates, this invention presents a concise and efficient one-pot, two-step synthetic route. First, a prepolymer with terminal isocyanate groups is generated by reacting a dihydroxy compound with excess diisocyanate. This intermediate has a well-defined structure and high reactivity. Then, the active amino groups at both ends of a dihydrazide molecule react with the terminal isocyanate groups of the prepolymer, achieving chain extension and amino group capping in one step, ultimately generating a highly symmetrical target diamine chain extender. This method avoids the use of hazardous raw materials, operates under mild reaction conditions, and provides an ideal chain extender choice for the preparation of high-performance polymers.
[0007] A diamine chain extender for two-component polyurethane resin, characterized in that:
[0008]
[0009] In this context, R1 is a characteristic structural unit of diol, R2 is a characteristic structural unit of diisocyanate, and R3 is a characteristic structural unit of dihydrazide.
[0010] A method for preparing the diamine chain extender for a two-component polyurethane resin according to claim 1, characterized in that it includes the following steps:
[0011] (1) A dihydroxy compound, diisocyanate, and catalyst were dissolved in a good solvent at a molar ratio of 1:2.05~2.5:0.003~0.006 and reacted at 80~100 °C for 1~3 h to prepare a terminal isocyanate-based prepolymer;
[0012] (2) The dihydrazide and the terminal isocyanate prepolymer obtained in step (1) are reacted at 80-100 °C for 3-5 h in a molar ratio of 1:2-2.2 to obtain a reaction solution. After the reaction is completed, the reaction solution is cooled and poured into a precipitant to precipitate and wash. Finally, the diamine chain extender is obtained by vacuum drying.
[0013] Further, the dihydroxy compound is one or more of 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, N,N'-bis(2-hydroxyethyl)terephthalamide, N,N'-bis(2-hydroxyethyl)oxalamide, hydroquinone dihydroxyethyl ether, neopentyl glycol, and bisphenol A bis(2-hydroxyethyl) ether.
[0014] Further, the diisocyanate is one or more of 2,4-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and terephthalic diisocyanate.
[0015] Furthermore, the catalyst is one or more of the following: stannous octoate, dibutyltin dilaurate, triethylenediamine, tetramethylbutylenediamine, triethylenediamine, bismuth 2-ethylhexanoate, bismuth neodecanoate, zirconium neodecanoate, and zirconium 2-ethylhexanoate.
[0016] Furthermore, the good solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, toluene, tetrahydrofuran, ethyl acetate, butanone, n-hexane, and dimethyl carbonate.
[0017] Further, the dihydrazide is one or more of oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, and terephthalic acid dihydrazide.
[0018] Furthermore, the precipitant is one or more of deionized water, methanol, ethanol, isopropanol, and petroleum ether.
[0019] Furthermore, the vacuum drying temperature is 70~90℃, and the time is 12~24h.
[0020] The beneficial effects of this invention are:
[0021] 1. Based on the high reactivity of isocyanates, this invention designs a simple and efficient "one-pot two-step" synthetic route. First, a prepolymer with terminal isocyanate groups is generated by reacting a dihydroxy compound with excess diisocyanate. This intermediate has a well-defined structure and high reactivity. Then, the active amino groups at both ends of the dihydrazide molecule react with the terminal isocyanate groups of the prepolymer to achieve chain extension and amino group capping in one step, ultimately generating a highly symmetrical target diamine chain extender. This method avoids the use of hazardous raw materials, has mild reaction conditions, and provides an ideal choice of chain extender for the preparation of high-performance polymers.
[0022] 2. The preparation method of the diamine chain extender for two-component polyurethane resin involved in this invention has the characteristics of simple process route, mild reaction conditions, safe operation and good repeatability.
[0023] 3. The diamine chain extender for two-component polyurethane resin prepared in this invention has a highly symmetrical molecular structure and contains strongly polar amide and urea bonds, which can form strong hydrogen bonds with the polymer matrix (such as polyurethane prepolymer) to be chain extended, thereby significantly improving the tensile strength, elongation at break and tear strength of polyurethane materials, and has broad market application prospects. Attached Figure Description
[0024] Figure 1 The image shows the hydrogen NMR spectrum of the product in Example 2. Detailed Implementation
[0025] Example 1: A diamine chain extender for two-component polyurethane resin, characterized in that:
[0026]
[0027] In this context, R1 is a characteristic structural unit of diol, R2 is a characteristic structural unit of diisocyanate, and R3 is a characteristic structural unit of dihydrazide.
[0028] Example 2: A method for preparing the diamine chain extender for a two-component polyurethane resin according to claim 1: comprising the following steps: dissolving a dihydroxy compound, a diisocyanate, and a catalyst in a good solvent at a molar ratio of 1:2.05:0.003 and reacting at 80 °C for 1 h to prepare a terminal isocyanate-based prepolymer; the dihydroxy compound is 1,4-butanediol, the diisocyanate is 2,4-diphenylmethane diisocyanate, the catalyst is stannous octoate, and the good solvent is N,N-dimethylformamide.
[0029] A reaction solution was obtained by reacting diacylhydrazide and terminal isocyanate-based prepolymer at a molar ratio of 1:2 at 80 °C for 3 h. After the reaction, the reaction solution was cooled, poured into a precipitant to precipitate, washed, and finally dried under vacuum to obtain a diamine chain extender. The diacylhydrazide was oxalic acid diacylhydrazide, the precipitant was deionized water, and the vacuum drying temperature was 70 °C for 12 h.
[0030] The NMR characterization of the product in Example 2 is as follows:
[0031] 1 H NMR (400MHz, DMSO-d6) δ8.76 (s, 1H), 7.97 (s, 1H), 7.02-7.19(d,1H), 4.02 (s, 2H), 3.13-3.58 (m, 1H), 2.63-2.92 (m, 1H), 2.41-2.57 (s, 1H), 0.74-1.34 (m, 2H).
[0032] Example 3: A method for preparing the diamine chain extender for a two-component polyurethane resin according to claim 1: comprising the following steps: dissolving a dihydroxy compound, a diisocyanate, and a catalyst in a good solvent at a molar ratio of 1:2.3:0.004 and reacting at 90 °C for 2 h to prepare a terminal isocyanate-based prepolymer; the dihydroxy compound is 1,6-hexanediol. The diisocyanate is toluene-2,4-diisocyanate. The catalyst is dibutyltin dilaurate. The good solvent is dimethyl sulfoxide.
[0033] A dihydrazide was reacted with a terminal isocyanate-based prepolymer at a molar ratio of 1:2.1 at 90 °C for 4 h to obtain a reaction solution. After the reaction was completed, the reaction solution was cooled, poured into a precipitant to precipitate, washed, and finally dried under vacuum to obtain a diamine chain extender. The dihydrazide was malonyl hydrazide. The precipitant was methanol. The vacuum drying temperature was 80 °C for 18 h.
[0034] The NMR characterization of the product in Example 3 is as follows:
[0035] 1 H NMR (400MHz, DMSO-d6) δ8.87-9.12 (d, 1H), 7.69 (s, 1H), 6.02 (s,1H), 4.26 (s, 2H), 3.43-3.51 (m, 1H), 3.9 (m, 2H), 1.43-1.55 (m, 2H).
[0036] Example 4: A method for preparing the diamine chain extender for a two-component polyurethane resin according to claim 1, comprising the following steps: dissolving a dihydroxy compound, a diisocyanate, and a catalyst in a good solvent at a molar ratio of 1:2.5:0.006 and reacting at 100 °C for 3 h to prepare a terminal isocyanate-based prepolymer; the dihydroxy compound is 1,4-cyclohexanediethanol. The diisocyanate is hexamethylene diisocyanate. The catalyst is triethylenediamine. The good solvent is toluene.
[0037] A diacylhydrazide was reacted with a terminal isocyanate prepolymer at a molar ratio of 1:2.2 at 100 °C for 5 h to obtain a reaction solution. After the reaction was completed, the reaction solution was cooled, poured into a precipitant to precipitate, washed, and finally dried under vacuum to obtain a diamine chain extender. The diacylhydrazide was succinic diacylhydrazide. The precipitant was ethanol. The vacuum drying temperature was 90 °C and the time was 24 h.
[0038] The NMR characterization of the product in Example 4 is as follows:
[0039] 1 H NMR (400MHz, DMSO-d6) δ8.89 (s, 1H), 8.18 (s, 1H), 7.69 (s, 1H), 6.46 (s, 1H), 4.55 (t, 2H), 4.10 (s, 2H), 3.4-3.49 (m, 1H), 3.9 (m, 2H),1.74-1.92 (m, 2H).
[0040] Example 5: Referring to Example 2, the dihydroxy compound is one or more of 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediethanol, N,N'-bis(2-hydroxyethyl)terephthalamide, N,N'-bis(2-hydroxyethyl)oxalamide, hydroquinone dihydroxyethyl ether, neopentyl glycol, and bisphenol A bis(2-hydroxyethyl) ether. The diisocyanate is one or more of 2,4-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and terephthalic diisocyanate. The catalyst is one or more of stannous octoate, dibutyltin dilaurate, triethylenediamine, tetramethylbutylenediamine, triethylenediamine, bismuth 2-ethylhexanoate, bismuth neodecanoate, zirconium neodecanoate, and zirconium 2-ethylhexanoate. The good solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, toluene, tetrahydrofuran, ethyl acetate, butanone, n-hexane, and dimethyl carbonate. The dihydrazide is one or more of oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, and terephthalic acid dihydrazide. The precipitant is one or more of deionized water, methanol, ethanol, isopropanol, and petroleum ether.
[0041] Performance testing
[0042] The chain extenders prepared in Examples 2-4 above were used to prepare formulations with comparative examples (commercially available MOCA as Comparative Example 1, polyetheramine D230 as Comparative Example 2, and PACM as Comparative Example 3), as shown in Table 1. These formulations were used to cure the same polyurethane prepolymer formulations. Corresponding mechanical property test strips were 3D printed, cleaned, and cured. The mechanical properties of the resulting polyurethane elastomers were tested, and the results are shown in Tables 1 and 2.
[0043] Table 1 Formulation Composition
[0044] Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 End-capped polyurethane acrylate 70% 70% 70% 70% 70% 70% HEA 15% 15% 15% 15% 15% 15% ACMO 10% 10% 10% 10% 10% 10% IBOA 5% 5% 5% 5% 5% 5% Chain extender Example 2 Product Example 3 Product Example 4 Product Comparative Example 1 Product Comparative Example 2 Product Comparative Example 3 Product
[0045] Table 2 Mechanical Properties
[0046] sample Tensile strength (MPa) Elongation at break (%) Tear resistance (kN / m) Example 2 31.2 500 49 Example 3 32.5 480 50 Example 4 29.8 375 42 Comparative Example 1 18.5 252 22 Comparative Example 2 16.7 358 20 Comparative Example 3 21 303 21
[0047] As shown in the table above, the chain extender prepared by this invention surpasses traditional MOCA, polyetheramine D230, and PACM in tensile strength, while maintaining higher elongation at break and tear resistance, demonstrating excellent comprehensive mechanical properties. The products prepared in Examples 2-4 also exhibit good reinforcing effects, proving the universality of the method of this invention.
[0048] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A diamine chain extender for two-component polyurethane resins, characterized in that: In this context, R1 is a characteristic structural unit of diol, R2 is a characteristic structural unit of diisocyanate, and R3 is a characteristic structural unit of dihydrazide.
2. A method for preparing the diamine chain extender for the two-component polyurethane resin according to claim 1, characterized in that, Includes the following steps: (1) A dihydroxy compound, diisocyanate, and catalyst were dissolved in a good solvent at a molar ratio of 1:2.05~2.5:0.003~0.006 and reacted at 80~100 °C for 1~3 h to prepare a terminal isocyanate-based prepolymer; (2) The dihydrazide and the terminal isocyanate prepolymer obtained in step (1) are reacted at 80-100 °C for 3-5 h in a molar ratio of 1:2.05-2.2 to obtain a reaction solution. After the reaction is completed, the reaction solution is cooled and poured into a precipitant to precipitate and washed. Finally, the diamine chain extender is obtained by vacuum drying.
3. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The dihydroxy compound is one or more of 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, N,N'-bis(2-hydroxyethyl)terephthalamide, N,N'-bis(2-hydroxyethyl)oxalamide, hydroquinone dihydroxyethyl ether, neopentyl glycol, and bisphenol A bis(2-hydroxyethyl) ether.
4. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The diisocyanate is one or more of 2,4-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and terephthalic diisocyanate.
5. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The catalyst is one or more of the following: stannous octoate, dibutyltin dilaurate, triethylenediamine, tetramethylbutylenediamine, triethylenediamine, bismuth 2-ethylhexanoate, bismuth neodecanoate, zirconium neodecanoate, and zirconium 2-ethylhexanoate.
6. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The good solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, toluene, tetrahydrofuran, ethyl acetate, butanone, n-hexane, and dimethyl carbonate.
7. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The dihydrazide is one or more of oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, and terephthalic acid dihydrazide.
8. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The precipitant is one or more of deionized water, methanol, ethanol, isopropanol, and petroleum ether.
9. The method for preparing the diamine chain extender for two-component polyurethane resin according to claim 2, characterized in that, The vacuum drying temperature is 70~90℃, and the time is 12~24h.