A calixarene-derived hydrazide chain extender and a preparation method and application thereof

Abstract

The present application relates to the technical field of polyurethane elastomer, in particular to a calixarene-derived hydrazide chain extender, a preparation method and application thereof, and the calixarene-derived hydrazide chain extender has a structural formula shown in formula (I). The calixarene-derived hydrazide chain extender introduced in the polyurethane elastomer has multiple hydrogen bonds, compared with traditional hydrazide compounds, it contains a hydrogen bond donor, i.e. phenolic hydroxyl group, which overcomes the poor solubility of traditional hydrazide compounds in low-boiling organic solvents; the solubility of the calixarene-derived hydrazide compound is moderate, and it can be partially dissolved in low-boiling methyl tert-butyl ether, which overcomes the problem that the catalytic activity of traditional amine catalysts is too high and the reaction is uncontrollable; the product prepared by using the calixarene-derived hydrazide compound as a hard segment of the polyurethane elastomer has excellent tensile strength and toughness, and the introduction of rigid calixarene makes the polyurethane elastomer have excellent strength and a higher thermal weight loss temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane elastomers, in particular to a calixarene-derived hydrazide chain extender, a preparation method thereof and an application thereof. BACKGROUND

[0002] Polyurethane elastomers have been widely used in many fields due to their excellent properties of high hardness and high elasticity. With the development of technology and the improvement of market demand, the requirements for the performance of polyurethane elastomers are increasingly diversified and stringent, especially in terms of thermal stability, mechanical properties, solubility, and controllability of reaction.

[0003] At present, a number of patents have been reported on polyurethane elastomers and their chain extenders. For example, Chinese patent CN119955061A discloses a preparation method and application of a bio-based high-strength and high-toughness polyurethane. It uses a bio-based hydrazide derived from 2,5-furandicarboxylic acid dimethyl ester as a chain extender to prepare a bio-based high-strength and high-toughness polyurethane. However, this polyurethane has the problem of insufficient thermal stability, with a thermal weight loss temperature less than 450°C, which limits its application in some fields with high requirements for thermal stability.

[0004] Chinese patent CN119118866A relates to a preparation method of an aliphatic hydrazine chain extender. A series of secondary amine hydrazine chain extenders are synthesized by Michael addition reaction of various aliphatic hydrazines with various α,β-unsaturated carbonyl compounds. The elastomer prepared with this chain extender has good mechanical recovery performance, but further optimization is needed for other properties such as thermal stability and solubility.

[0005] Chinese patent CN117362253A discloses a bio-based polyurethane chain extender and a preparation method thereof. However, this chain extender has the problem of poor solubility in low-boiling organic solvents, and requires a large amount of high-boiling organic solvents such as DMF and DMAc for dissolution and dispersion. The use of a large amount of high-boiling organic solvents not only increases the production cost, but also causes certain pressure on the environment, and also restricts the large-scale development of downstream synthesis applications.

[0006] In addition to hydrazine chain extenders, ordinary small molecule alcohol chain extenders also have obvious defects. The polyurethane products prepared using ordinary small molecule alcohol chain extenders have poor physical strength and cannot meet the requirements of some high-strength application scenarios.

[0007] Primary amine chain extenders also have many problems. The reaction speed of existing primary amine chain extenders is difficult to control, and gelation phenomenon is prone to occur during the reaction, which brings great difficulty to the control of the production process, reduces the production efficiency and the stability of the product quality. Moreover, part of the amine catalysts have great toxicity and poor solubility, which not only threatens the health of the operators, but also affects the uniformity and effect of the reaction.

[0008] In addition, amine chain extenders such as MOCA (4,4'-methylenebis(2-chloroaniline)) can cause oxidative discoloration under high temperature or long time heating. When used as a chain extender to prepare light-colored products, it may have adverse effects on the color of the products, thereby limiting its application in the field of light-colored products.

[0009] In summary, the existing polyurethane elastomers and their chain extenders have problems in thermal stability, mechanical properties, solubility, reaction controllability and color stability to varying degrees, which restricts the application and development of polyurethane elastomers in a wider field. Therefore, it is of great practical significance to develop a polyurethane elastomer with better performance and wider applicability and its chain extender. SUMMARY

[0010] In order to solve the above technical problems in the prior art, the present application provides a calixarene-derived hydrazine chain extender and its preparation method and application.

[0011] The technical scheme for solving the above technical problems of the present application is as follows:

[0012] The first aspect of the present application is to provide a calixarene-derived hydrazine chain extender having the structural formula shown in formula (I):

[0013]

[0014] (I)

[0015] wherein n=0, 1, 2; R is selected from a hydrogen atom or a tertiary hydrocarbon group; and R2 is selected from a hydrogen atom or CH2CONHNH2.

[0016] On the basis of the above technical scheme, the present application can also be improved as follows:

[0017] Further, it is selected from the following structural formula:

[0018]

[0019] (I-1)

[0020]

[0021] (I-2)

[0022]

[0023] (I-3).

[0024] When R is a hydrogen atom, the calix[4]arene derivative hydrazine chain extender represented by formula (I-1) comprises the following two structures:

[0025] ,

[0026] .

[0027] When R is a hydrogen atom, the calix[5]arene derivative hydrazine chain extender represented by formula (I-2) comprises the following two structures:

[0028] ,

[0029] .

[0030] When R is a hydrogen atom, the calix[6]arene derivative hydrazine chain extender represented by formula (I-3) comprises the following three structures:

[0031] ,

[0032] ,

[0033] .

[0034] Further, the calixarene derivative hydrazine chain extender described above is prepared by the following method: under the protection of an inert atmosphere, calixarene is reacted with ethyl chloroacetate under the action of a base to obtain compound one, and then hydrazinolysis reaction of compound one with hydrazine hydrate is carried out to obtain the calixarene derivative hydrazine chain extender.

[0035] Further, the compound one has a structural formula represented by formula (II):

[0036]

[0037] (II)

[0038] wherein R1 is selected from a hydrogen atom or CH2COOEt.

[0039] The second aspect of the present application is to provide a preparation method of the calixarene derivative hydrazine chain extender described above, comprising the following steps:

[0040] S1, under the protection of nitrogen, nucleophilic substitution reaction of calixarene with ethyl chloroacetate under the action of a base, after the reaction is completed, water washing and extraction are carried out to obtain compound one;

[0041] S2, under nitrogen protection, hydrazinolysis reaction of compound one and hydrazine hydrate, after the reaction, water washing, suction filtration and drying to obtain the calixarene derived hydrazide chain extender.

[0042] When R is a hydrogen atom, the reaction formula for preparing the calixarene derived hydrazide chain extender is as follows:

[0043] .

[0044] After the first step reaction, water washing and extraction are used to remove the base and high boiling point DMF (N, N-dimethylformamide, used as a solvent for dissolving calixarene).

[0045] Further, in step S1, the molar ratio of the calixarene to ethyl chloroacetate is 1: (2-2.2).

[0046] Another aspect of the present application is to provide a polyurethane elastomer prepared by using the above calixarene derived hydrazide chain extender.

[0047] Further, the polyurethane elastomer is prepared by using polycaprolactone polyol, naphthalene diisocyanate (NDI) and calixarene derived hydrazide chain extender as raw materials, and by a prepolymerization-chain extension method.

[0048] Further, the molecular weight of the polycaprolactone polyol is 1000-3000.

[0049] Further, the molecular weight of the polycaprolactone polyol is 2000.

[0050] Compared with the prior art, the present application has the following technical effects:

[0051] The present application designs and synthesizes a series of calixarene derived hydrazide chain extenders with different sizes through hydrogen bonding engineering, and then uses polycaprolactone polyol, naphthalene diisocyanate and different chain extenders as raw materials to synthesize a series of polyurethane elastomers with different chain extender structures through a prepolymerization-chain extension method.

[0052] The calixarene derived hydrazide chain extender introduced in the present application has multiple hydrogen bonds, and compared with traditional hydrazide compounds, it contains a phenolic hydroxyl group as a hydrogen bond donor, overcoming the poor solubility of traditional hydrazide compounds in low boiling point organic solvents; the calixarene derived hydrazide compound has moderate solubility and can be partially dissolved in low boiling point MTBE (methyl tert-butyl ether), and the low boiling point solvent is easy to volatilize, solving the cumbersome steps of handling high boiling point solvents in the later stage.

[0053] Existing amine compounds, due to their good solubility and high nucleophilicity of nitrogen atoms, exhibit rapid reaction rates when used as chain extenders, leading to difficulties in controlling the reaction rate. The calixarene-derived acylhydrazine chain extender provided by this invention reduces the nucleophilicity of the nitrogen atom of the acylhydrazine by introducing an electron-withdrawing acyl group, while the introduction of a phenolic hydroxyl group makes its solubility superior to that of traditional acylhydrazine chain extenders. This results in moderate solubility and stable reaction, overcoming the problems of high activity and difficult reaction control of traditional amine catalysts. The moderate solubility eliminates the need for high-boiling-point organic solvents while also maintaining the advantages of moderate and controllable reaction activity.

[0054] Products prepared using calixarene-derived hydrazide chain extenders provided by this invention as hard segments of polyurethane elastomers exhibit excellent tensile strength and toughness. Meanwhile, the introduction of rigid calixarenes gives the polyurethane elastomers excellent strength and high thermal weight loss temperature. Detailed Implementation

[0055] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be presented in conjunction with preferred embodiments, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the present invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0056] Example 1

[0057] Preparation of chain extenders derived from calix[4]arene (n=0, R=tert-butyl) hydrazides:

[0058] S1. Under nitrogen protection, 0.30 mol of cup[4] aromatic hydrocarbon and 0.63 mol of ethyl chloride were subjected to nucleophilic substitution reaction under the action of alkali to obtain compound one. After the reaction was completed, the compound was washed with water and extracted to remove the alkali and high-boiling-point DMF.

[0059] S2. Under nitrogen protection, compound 1 was reacted with 0.60 mol of hydrazine hydrate in a hydrazinolysis reaction. After the reaction, the mixture was washed with water and filtered repeatedly. The filter cake was then heated to 75°C. o Drying in an oven at C for 24 h yields cup[4] aromatic hydrazide chain extenders.

[0060] Example 2

[0061] Preparation of calix[4]arene (n=0, R=H) derived hydrazide chain extender:

[0062] S1, under nitrogen protection, 0.30 mol calix[4]arene was subjected to nucleophilic substitution reaction with 0.63 mol ethyl chloroacetate under the action of base to obtain compound one, after the reaction, the base was removed by water washing and extraction, and high-boiling DMF;

[0063] S2, under nitrogen protection, compound one was subjected to hydrazinolysis reaction with 0.60 mol hydrazine hydrate, after the reaction, the filter cake was washed with water for multiple times, and filtered, and the filter cake was dried at 75 o C oven for 24 h to obtain calix[4]arene derived hydrazide chain extender.

[0064] Example 3

[0065] Preparation of calix[5]arene (n=1, R=t-butyl) derived hydrazide chain extender:

[0066] Calix[5]arene was used instead of calix[4]arene in Example 1, and the rest was the same as Example 1, which will not be repeated here.

[0067] Example 4

[0068] Preparation of calix[5]arene (n=1, R=H) derived hydrazide chain extender:

[0069] Calix[5]arene was used instead of calix[4]arene in Example 1, and the rest was the same as Example 1, which will not be repeated here.

[0070] Example 5

[0071] Preparation of calix[6]arene (n=2, R=t-butyl) derived hydrazide chain extender:

[0072] Calix[6]arene was used instead of calix[4]arene in Example 1, and the rest was the same as Example 1, which will not be repeated here.

[0073] Example 6

[0074] Preparation of calix[6]arene (n=2, R=H) derived hydrazide chain extender:

[0075] Calix[6]arene was used instead of calix[4]arene in Example 1, and the rest was the same as Example 1, which will not be repeated here.

[0076] Example 7

[0077] Synthesis of polyurethane elastomer PCL-1:

[0078] Under nitrogen protection, 100.00 g (50 mmol) of PCL 220CPT vacuum-dried, 21.02 g (100 mmol) of NDI, 0.50 g of dibutyltin dilaurate (0.5% mass fraction of PCL 220CPT) and 10 mL of DMF were first mixed and heated to 80°C, and stirred for 2 h to obtain a prepolymer; then the temperature was cooled to 50°C, 39.65 g (50 mmol) of the calix[4]arene-derived hydrazide chain extender prepared in Example 1 was dissolved in 20 mL of MTBE and slowly added to the above-prepared prepolymer (NCO% = 3.5%), and stirred for 30 min;

[0079] The polymer solution prepared above was poured into a polytetrafluoroethylene mold, degassed in a vacuum oven, and then the solvent was volatilized on a horizontal hot stage at 80°C for 24 h to obtain a pre-cured product; after demolding, the product was dried at 60°C under a vacuum degree of 10 -4 Pa for 72 h, and finally a polyurethane elastomer PCL-1 sheet with a thickness of 2 mm was obtained.

[0080] Example 8

[0081] Synthesis of polyurethane elastomer PCL-2:

[0082] The synthesis of polyurethane elastomer PCL-2 was carried out using the calix[4]arene-derived hydrazide chain extender prepared in Example 2, and the rest was the same as Example 7, which will not be repeated here.

[0083] Example 9

[0084] Synthesis of polyurethane elastomer PCL-3:

[0085] The synthesis of polyurethane elastomer PCL-3 was carried out using the calix[5]arene-derived hydrazide chain extender prepared in Example 3, and the rest was the same as Example 7, which will not be repeated here.

[0086] Example 10

[0087] Synthesis of polyurethane elastomer PCL-4:

[0088] The synthesis of polyurethane elastomer PCL-4 was carried out using the calix[5]arene-derived hydrazide chain extender prepared in Example 4, and the rest was the same as Example 7, which will not be repeated here.

[0089] Example 11

[0090] Synthesis of polyurethane elastomer PCL-5:

[0091] The synthesis of polyurethane elastomer PCL-5 was carried out using the calix[6]arene derived hydrazide type chain extender prepared in Example 5, the rest was the same as Example 7, which will not be repeated here.

[0092] Example 12

[0093] Synthesis of polyurethane elastomer PCL-6:

[0094] The synthesis of polyurethane elastomer PCL-6 was carried out using the calix[6]arene derived hydrazide type chain extender prepared in Example 6, the rest was the same as Example 7, which will not be repeated here.

[0095] Comparative Example 1

[0096] Synthesis of polyurethane elastomer PCL-7:

[0097] First, 100.00 g (50 mmol) of PCL 220CPT (2000 molecular weight polycaprolactone polyol produced by Daicel Corporation), 21.07 g (100 mmol) of NDI (naphthalene diisocyanate), 0.50 g of dibutyltin dilaurate (0.5% mass fraction of PCL220CPT) and 10 mL of DMF were mixed and heated to 80°C, and stirred for 2 h to obtain a prepolymer; then the temperature was cooled to 50°C, and the chain extender 5.81 g (50 mmol) of 1,4-cyclohexanediol was dissolved in 10 mL of DMF and slowly added to the above prepared prepolymer (NCO% = 3.5%), and stirred for 30 min;

[0098] The obtained polymer solution was poured into a polytetrafluoroethylene mold, degassed in a vacuum oven, and then the solvent was volatilized on a 80°C horizontal hot stage for 24 h to obtain a pre-cured product; after demolding, the product was dried at 60°C, 10 -4 Pa, for 72 h, and finally a polyurethane elastomer PCL-7 sheet with a thickness of 2 mm was obtained.

[0099] Comparative Example 2

[0100] Synthesis of polyurethane elastomer PCL-8:

[0101] 4,4'-Methylenebis(2-chloroaniline), i.e. MOCA, was used as a chain extender, the rest was the same as Comparative Example 1, which will not be repeated here.

[0102] Comparative Example 3

[0103] Synthesis of polyurethane elastomer PCL-9:

[0104] p-Phenylene dihydroxyethyl ether was used as a chain extender, the rest was the same as Comparative Example 1, which will not be repeated here.

[0105] Comparative Example 4

[0106] Synthesis of polyurethane elastomer PCL-10:

[0107] Using 1,4-butanediol as chain extender, the rest is the same as Comparative Example 1, which will not be repeated here.

[0108] Comparative Example 5

[0109] Synthesis of polyurethane elastomer PCL-11:

[0110] Using 4,4'-methylenebis(2,6-diisopropylaniline), namely M-DIPA, as a chain extender, the rest is the same as Comparative Example 1, which will not be repeated here.

[0111] Comparative Example 6

[0112] Synthesis of polyurethane elastomer PCL-12:

[0113] Using adipic acid dihydrazide as a chain extender, the rest is the same as Comparative Example 1, which will not be repeated here.

[0114] Comparative Example 7

[0115] Synthesis of polyurethane elastomer PCL-13:

[0116] Using furan-2,5-dicarboxylic acid dihydrazide as a chain extender, the rest is the same as Comparative Example 1, which will not be repeated here.

[0117] Comparative Example 8

[0118] Synthesis of polyurethane elastomer PCL-14:

[0119] Using phthalic acid dihydrazide as a chain extender, the rest is the same as Comparative Example 1, which will not be repeated here.

[0120] Comparative Example 9

[0121] Synthesis of polyurethane elastomer PCL-15:

[0122] Using pyridine-2,6-dicarboxylic acid dihydrazide as a chain extender, the rest is the same as Comparative Example 1, which will not be repeated here.

[0123] Performance test

[0124] Hardness: Refer to standard GB / T 531-1999.

[0125] Tensile strength: Refer to standard GB / T 528-1998, sample width 6mm, thickness 2mm, tensile rate 200mm / min, multiple tests and average value.

[0126] Resilience: Refer to standard GB / T 1681-2009.

[0127] Compression set: tested according to GB / T7759-1996.

[0128] Thermogravimetric analysis (TGA): tested by TGA-50 thermogravimetric analyzer of Shimadzu Corporation, temperature range from room temperature to 600℃, heating rate of 10 ℃ / min, atmosphere protection flow rate of 30 mL / min.

[0129] The polyurethane elastomers of Examples 7-12 and Comparative Examples 1-9 were tested for performance according to the above performance test standards, and the performance test results are shown in Table 1.

[0130] Table 1 Performance test data of polyurethane elastomers of Examples 7-12 and Comparative Examples 1-9

[0131]

[0132] The polyurethane elastomer product has the advantages of high strength and high toughness. The introduction of the rigid calixarene structure makes the elastomer have a high thermal decomposition temperature. In summary, the calixarene-derived hydrazine chain extender is expected to be applied to elastomer products with high added value.

[0133] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A calixarene-derived hydrazide-based chain extender, characterized by, A compound having a structural formula as shown in formula (I): （I） Wherein, n=0, 1, 2; R is selected from a hydrogen atom; R2 is selected from CH2CONHNH2.

2. A calixarene-derived hydrazide-based chain extender, characterized by, A compound having a structural formula as shown in formula (II): Wherein, R is a hydrogen atom.

3. A calixarene-derived hydrazide-based chain extender, characterized in that, Any one of the following structural formulae: （I-1） （I-2） （I-3） Wherein, R is selected from a hydrogen atom; R2 is selected from CH2CONHNH2.

4. A method for preparing the calixarene-derived hydrazide-based chain extender according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: S1. Under nitrogen protection, a nucleophilic substitution reaction is carried out between a calixarene and ethyl chloroacetate under the action of a base, and after the reaction is completed, water washing and extraction are carried out to obtain a compound one; S2. Under nitrogen protection, a hydrazinolysis reaction is carried out between the compound one and hydrazine hydrate, and after the reaction is completed, water washing, suction filtration and drying are carried out to obtain the calixarene-derived hydrazide chain extender. The compound one has a structural formula as shown in formula (II): (II) Wherein, R1 is selected from a hydrogen atom or CH2COOEt.

5. The method of claim 4, wherein the calixarene-derived hydrazide-based chain extender is prepared by the reaction of a calixarene derivative of formula (1) with hydrazine hydrate in the presence of a solvent. In step S1, the molar ratio of the calixarene to ethyl chloroacetate is 1: (2-2.2).

6. A polyurethane elastomer characterized by, The polyurethane elastomer is prepared by using the calixarene-derived hydrazide chain extender of claim 1 or 2 or 3.

7. The polyurethane elastomer according to claim 6, wherein The polyurethane elastomer is prepared by using polycaprolactone polyol, naphthalene diisocyanate and the calixarene-derived hydrazide chain extender as raw materials, and by using a prepolymerization-chain extension method.

8. The polyurethane elastomer according to claim 7, characterized in that, The polycaprolactone polyol has a molecular weight of 1000-3000.

9. The polyurethane elastomer according to claim 8, wherein, The polycaprolactone polyol has a molecular weight of 2000.

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