A polyester polyurethane and a method for preparing the same

Abstract

This invention belongs to the field of polymer synthetic chemistry, specifically disclosing a polyester-type polyurethane and its preparation method. The preparation method includes two steps: (1) using terephthalic acid, monomer M1, and monomer M2 as raw materials, a polyester polyol is synthesized in the presence of a solvent and catalyst A; (2) the obtained polyester polyol is reacted with isocyanate in the presence of catalyst B to obtain a polyester-type polyurethane. This invention introduces a cyclopentane structure into the polyester-type polyurethane molecular chain. Its rigid ring effectively restricts chain segment movement, significantly improving the initial modulus, hardness, and compressive strength of the material; at the same time, the regular cyclopentane units can induce soft segment crystallization, further enhancing tensile strength. In view of the defect of easy hydrolysis in traditional polyester-type polyurethane, the hydrophobic cyclopentane reduces the polarity of the polyester chain segments, effectively reducing water molecule erosion and significantly improving hydrolysis resistance. In addition, the bromine atoms in the molecule endow the material with excellent self-extinguishing properties. The preparation method of this invention is green and environmentally friendly, and easy to operate. It successfully obtains a high-performance polyester-type polyurethane with recyclability, hydrolysis resistance, and self-extinguishing properties, providing a feasible path for the development of multifunctional polymer materials, and has good industrial application prospects and promotion value.

Description

Technical Field

[0001] This invention relates to the field of polymer synthetic chemistry, and in particular to a novel polyester-type polyurethane and its preparation method. Technical Background

[0002] Polyurethane, as a high-performance polymer material, occupies an irreplaceable and vital position in the national economy. Its unique adjustable structure, with its varying degrees of hardness and softness, endows the material with a wide performance range, from thermoplastic elastomers to rigid foams, capable of meeting the demanding requirements of different fields. In the construction industry, rigid polyurethane foam, with its superior thermal insulation performance, has become the preferred energy-saving insulation material; in the automotive industry, polyurethane is widely used in seats, interior parts, and bumpers; in the clothing industry, spandex fibers give fabrics excellent elasticity; and in the electronics and electrical appliance industry, polyurethane potting compounds provide reliable protection for precision components. With the increasing global emphasis on energy conservation, emission reduction, and sustainable development, the application prospects of polyurethane materials in strategic emerging industries such as new energy, lightweighting, and green building are becoming increasingly broad, and its technological innovation continues to drive the transformation and upgrading of related industries.

[0003] Polyester-based polyurethanes, as an important branch of the polyurethane family, occupy a core position in high-performance applications due to their excellent mechanical properties and chemical resistance. Compared with polyether-based polyurethanes, polyester segments endow materials with higher mechanical strength, superior abrasion resistance, and good oil and solvent resistance, making them outstanding in high-load scenarios such as industrial tires, transmission belts, and seals. In the synthetic leather industry, polyester-based polyurethanes can perfectly simulate the texture and feel of natural leather; in the footwear industry, their excellent tear resistance ensures the durability of athletic shoes under high-intensity use. Furthermore, the application of polyester-based polyurethanes in high-end fields such as medical devices and military equipment is constantly expanding. However, these characteristics, which rely on ester bonds, also bring potential challenges to the long-term use of the materials.

[0004] The ester bonds in polyester-based polyurethanes are hydrophilic, easily absorbing moisture from the environment during use, leading to hydrolytic breakage and a rapid decline in the material's mechanical properties, thus limiting its service life. More seriously, the hydrolytic degradation products are typically complex mixtures of carboxylic acids and alcohols, which cannot be recycled using conventional methods and ultimately must be disposed of as waste, resulting in resource waste and environmental pollution. Addressing this industry pain point, this patent proposes an innovative molecular structure design scheme. By introducing specific hydrophobic segments and stabilizing groups, the sensitivity of ester bonds to moisture is significantly reduced without sacrificing the material's excellent mechanical properties. Simultaneously, this design strategy also considers the material's recyclability, enabling the degradation products to be easily converted into reusable raw materials, truly achieving a balance between high performance and green sustainable development in polyester-based polyurethanes. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a recyclable, hydrolysis-resistant, self-extinguishing polyester polyurethane and its preparation method, addressing the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0007] In the first aspect, the present invention uses polyester polyol and isocyanate as raw materials to design a polyester-type polyurethane with cycloalkyl and bromine functional groups in the molecule as shown in Formula I.

[0008]

[0009] Where n is selected from any integer between 10 and 500;

[0010] R1 is selected from any one of Formula II;

[0011]

[0012] R2 is selected from any one of Formula III;

[0013]

[0014] Among them, option a

[0015] Any integer from 1 and 2;

[0016] x and y are any integers from 5 to 50;

[0017] The polyester-type polyurethane of this invention contains a cyclopentane structure in its molecular structure, which hinders the internal rotation of polyester segments and increases the rigidity of the molecular chain; it also increases the initial modulus, hardness, and compressive strength of the material. Simultaneously, the regular cyclopentane structure induces soft segment crystallization, thereby enhancing tensile strength. A disadvantage of polyester-type polyurethane is its susceptibility to hydrolysis (ester groups break after absorbing water). Cyclopentane is a hydrophobic methylene structure; its introduction reduces the polarity of the polyester segments, decreasing the erosion and penetration of water molecules, thus improving the material's hydrolysis resistance. Furthermore, the bromine atom imparts excellent self-extinguishing properties to the material. The preparation method described in this invention is green, environmentally friendly, and simple to operate, yielding recyclable, hydrolysis-resistant, and self-extinguishing polyester-type polyurethane. This provides a feasible path for developing high-performance polyurethane materials and possesses good application prospects and promotional value.

[0018] In a second aspect, the present invention discloses a method for preparing polyester-type polyurethane as shown in Formula I in the first aspect above.

[0019] The preparation method includes the following steps: (1) Synthesis of polyester polyol: terephthalic acid, monomer M1, monomer M2, solvent, and catalyst A are prepared.

[0020] (2) Polyester-type polyurethane: Polyester polyol, isocyanate and catalyst B are reacted.

[0021] Wherein, the single M2 is selected from any one of δ-valerolactone, ε-caprolactone, and L-lactide, and the structural formula of M1 is shown in Formula IV.

[0022]

[0023] In step (1), the molar ratio of monomer M1, monomer M2, terephthalic acid, and catalyst A is (1-50):(1-50):1:(0.1-2), the reaction temperature is 0-150℃, and the reaction time is 1 min-1440 min.

[0024] The solvent is any one of tetrahydrofuran, dichloromethane, chloroform, toluene, and N,N-dimethylformamide.

[0025] The catalyst is any one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, diphenyl phosphate, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,3-dimethoxyimidazol-2-ylene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0026] The isocyanate is any one of diphenylmethane diisocyanate, hexamethylene diisocyanate, 4,4-diisocyanate dicyclohexylmethane, isophorone diisocyanate, and toluene-2,4-diisocyanate.

[0027] Wherein, catalyst B is any one of stannous octoate, bismuth neodecanoate, dibutyltin dilaurate, bismuth isooctanoate, bismuth laurylate, and bismuth naphthenate.

[0028] In step (2), the reaction temperature is 10-150℃ and the reaction time is 1-24h.

[0029] Thirdly, the present invention discloses the application of the polyester-type polyurethane shown in Formula I above in the preparation of chemically recyclable materials.

[0030] In this invention, the polyester-type polyurethane is depolymerized into monomers under certain conditions, thereby achieving closed-loop chemical recycling of polyurethane; the monomers include monomer M1 and monomer M2.

[0031] The depolymerization conditions are as follows: under vacuum, at 70–200°C, with magnesium chloride as a catalyst, the polyester polyurethane is reacted for 4–24 hours.

[0032] Furthermore, monomers M1 and M2 were obtained by column chromatography, with recoveries of 80%–99% for M1 and 80%–99% for M2.

[0033] Beneficial effects:

[0034] (1) The polyester polyurethane provided by the present invention has both excellent rigidity and toughness, achieving a good balance between the two. The cyclopentane unit introduced into its molecular structure can effectively hinder the internal rotation of polyester chain segments, enhance the overall rigidity of the molecular chain, thereby improving the initial modulus, hardness and compressive strength of the material; at the same time, the regular cyclopentane structure helps to induce soft segment crystallization, further improving the tensile strength of the material.

[0035] (2) This polyester polyurethane also exhibits excellent hydrolysis resistance. As a hydrophobic methylene structure, the introduction of cyclopentane reduces the polarity of the polyester chain segments, effectively inhibiting the erosion and penetration of water molecules, thereby significantly improving the stability of the material in a humid environment and overcoming the shortcomings of traditional polyester polyurethanes that are prone to hydrolytic degradation due to water absorption by ester groups.

[0036] (3) This material also possesses excellent self-extinguishing properties. During high-temperature combustion, due to the low bond energy of the C-Br bond, it preferentially breaks and releases hydrogen bromide (HBr). HBr can capture high-energy free radicals generated in the combustion chain reaction, interrupting the combustion chain reaction and causing the flame to extinguish rapidly. Therefore, the oxygen index of the material is significantly improved, exhibiting flame-retardant or non-combustible properties in air.

[0037] (4) The polyester polyurethane provided by the present invention can be completely degraded and recycled to the initial monomer by a simple, efficient and highly recyclable depolymerization method, realizing the closed-loop chemical recycling of polyurethane materials and providing a new technical path for the recycling research of polyurethane. Attached Figure Description

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0039] Figure 1 The polyester polyol of Example 1 1 H NMR image

[0040] Figure 2 Polyester-type polyurethane of Example 1 1 H NMR image Detailed Implementation

[0041] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0042] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0043] In the following embodiments, the products were analyzed using a 400MHz Bruker nuclear magnetic resonance instrument. 1 1H NMR measurement: Take 6 mg of polyamide sample into an NMR tube, add deuterated chloroform, shake until completely dissolved, and then measure the sample.

[0044] The molecular weight and molecular weight distribution index of the samples were obtained by gel permeation chromatography with chloroform as the mobile phase and a flow rate of 0.7 mL / min.

[0045] Example

[0046] Example 1

[0047] 2.0 mmol monomer M1, 2.0 mmol δ-valerol, 0.1 mmol terephthalic acid, 0.1 mmol 17-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 2 mL toluene were placed in a reaction flask and reacted at 25 °C for 12 h. After the reaction was completed, the reactants were dissolved in dichloromethane and then added dropwise to ice-cold methanol to precipitate the product. The precipitate was filtered and dried in a vacuum drying oven to obtain the polyester polyol.

[0048] The obtained 1 mmol polyester polyol was reacted with 2 mmol isophorone diisocyanate at 70 °C for 4 h; then 0.05 mmol stannous octoate and 1 mmol butanediol were added and reacted at 70 °C for 6 h to obtain polyester polyurethane.

[0049] Example 2

[0050] 2.0 mmol monomer M1, 1.0 mmol ε-caprolactone, 0.1 mmol terephthalic acid, 0.08 mmol 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1 mL tetrahydrofuran were placed in a reaction flask and reacted at 25 °C for 12 h. After the reaction was completed, the reactants were dissolved in dichloromethane and then added dropwise to ice-cold methanol to precipitate the product. The precipitate was filtered and dried in a vacuum drying oven to obtain the polyester polyol.

[0051] The obtained 1 mmol polyester polyol was reacted with 2 mmol diphenylmethane diisocyanate at 90 °C for 2 h; then 0.05 mmol bismuth neodecanoate and 1 mmol butanediol were added and reacted at 90 °C for 6 h to obtain polyester polyurethane.

[0052] Example 3

[0053] 3.0 mmol of monomer M1, 3.0 mmol of L-lactide, 0.1 mmol of terephthalic acid, 0.05 mmol of 1,3-dimethyltrimethylimidazol-2-ylene, and 2 mL of chloroform were placed in a reaction flask and reacted at 25 °C for 24 h. After the reaction was completed, the reactants were dissolved in dichloromethane and then added dropwise to ice-cold methanol to precipitate the product. The precipitate was filtered and dried in a vacuum drying oven to obtain the polyester polyol.

[0054] The obtained 1 mmol polyester polyol was reacted with 2 mmol hexamethylene diisocyanate at 70 °C for 2 h; then 0.05 mmol bismuth neodecanoate and 1 mmol butanediol were added and reacted at 90 °C for 12 h to obtain polyester polyurethane.

[0055] Example 3

[0056] 3.0 mmol of monomer M1, 3.0 mmol of L-lactide, 0.1 mmol of terephthalic acid, 0.05 mmol of 1,3-dimethyltrimethylimidazol-2-ylene, and 2 mL of chloroform were placed in a reaction flask and reacted at 25 °C for 24 h. After the reaction was completed, the reactants were dissolved in dichloromethane and then added dropwise to ice-cold methanol to precipitate the product. The precipitate was filtered and dried in a vacuum drying oven to obtain the polyester polyol.

[0057] The obtained 1 mmol polyester polyol was reacted with 2 mmol hexamethylene diisocyanate at 70 °C for 2 h; then 0.05 mmol bismuth neodecanoate and 1 mmol butanediol were added and reacted at 90 °C for 12 h to obtain polyester polyurethane.

[0058] Example 4

[0059] 5.0 mmol of monomer M1, 5.0 mmol of δ-valerolactone, 0.1 mmol of terephthalic acid, 0.2 mmol of 1,3-dimethyltrimethylimidazol-2-ylene, and 5 mL of chlorotoluene were placed in a reaction flask and reacted at 80 °C for 12 h. After the reaction was completed, the reactants were dissolved in dichloromethane and then added dropwise to ice-cold methanol to precipitate the product. The precipitate was filtered and dried in a vacuum drying oven to obtain the polyester polyol.

[0060] The obtained 1 mmol polyester polyol was reacted with 2 mmol of 4,4-diisocyanate dicyclohexylmethane at 50 °C for 1 h; then 0.05 mmol of dibutyltin dilaurate and 1 mmol of butanediol were added and reacted at 80 °C for 12 h to obtain polyester polyurethane.

[0061] Example 5

[0062] 100 mg of the polyester polyurethane prepared in Example 1 and 1 mg of magnesium chloride were added to a reaction tube and reacted at 150 °C under vacuum for 12 h. The reaction product was then separated by column chromatography (petroleum ether / ethyl acetate = 10 / 1 to 5 / 1) to obtain monomer M1 and δ-valerolactone. The recovery rate of monomer M1 was 92% and the recovery rate of δ-valerolactone was 91%.

[0063] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A polyester-type polyurethane as shown in Formula I; in, n is any integer from 10 to 500; R1 is selected from any one of Formula II; R2 is selected from any one of Formula III; Where 'a' is any integer selected from 1 and 2; x and y are any integers from 5 to 50.

2. The method for preparing the polyester-type polyurethane as described in claim 1, characterized in that, The process includes the following steps: (1) Synthesis of polyester polyol: terephthalic acid, monomer M1, monomer M2, solvent, and catalyst A are prepared. (2) Polyester-type polyurethane: Polyester polyol, isocyanate and catalyst B are reacted.

3. The preparation method according to claim 2, characterized in that, The single M2 is selected from any one of δ-valerolactone, ε-caprolactone, and L-lactide, and the structural formula of M1 is shown in Formula IV.

4. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of monomer M1, monomer M2, terephthalic acid, and catalyst A is (1-50):(1-50):1:(0.1-2), the reaction temperature is 0-150℃, and the reaction time is 1 min-1440 min.

5. The preparation method according to claim 2, characterized in that, The solvent is any one of tetrahydrofuran, dichloromethane, chloroform, toluene, and N,N-dimethylformamide.

6. The preparation method according to claim 2, characterized in that, The catalyst is any one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, diphenyl phosphate, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,3-dimethoxyimidazol-2-ylene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

7. The preparation method according to claim 2, characterized in that, The isocyanate is any one of diphenylmethane diisocyanate, hexamethylene diisocyanate, 4,4-diisocyanate dicyclohexylmethane, isophorone diisocyanate, and toluene-2,4-diisocyanate.

8. The preparation method according to claim 2, characterized in that, Catalyst B is any one of stannous octoate, bismuth neodecanoate, dibutyltin dilaurate, bismuth isooctanoate, bismuth laurylate, and bismuth naphthenate.

9. The preparation method according to claim 2, characterized in that, The reaction temperature in step (2) is 10-150℃ and the reaction time is 1-24h.

10. The use of the polyester-type polyurethane of claim 1 in the preparation of chemically recyclable materials.

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