Polyurethane elastomer adopting square amide chain extension and preparation method thereof

Abstract

The invention discloses a polyurethane elastomer adopting square amide for chain extension and a preparation method of the polyurethane elastomer, and belongs to the technical field of polyurethane elastomers. A chain extender adopted by the polyurethane elastomer is a mixture of squaramide and micromolecular dihydric alcohol, and the squaramide accounts for 5.0-50.0% of the total mass of the chain extender. Under the recommended proportion of squaramide to dihydric alcohol, compared with a squaramide polyurea elastomer containing equal molar mass chain extension or a dihydric alcohol chain extension polyurethane elastomer, the prepared polyurethane elastomer has the advantages that squaramide serves as a physical cross-linking point to increase the strength, and dihydric alcohol improves the migration of a molecular chain; the synergistic effect of the components improves the mechanical properties, and the polyurethane elastomer is particularly balanced in the aspects of tensile strength, elongation and material toughness.

Description

Technical Field

[0001] The present application belongs to the technical field of polyurethane elastomers, and in particular, relates to a polyurethane elastomer using squaramide chain extension and a preparation method thereof. Background Art

[0002] Polyurethane (PU) is one of the most commonly used polymers with a variety of properties. It can be used as paints, coatings, synthetic rubbers, foams, fibers, adhesives, etc. It is widely used in the automotive industry, construction engineering, and biomedicine. PU is a block copolymer, which is a segmented block structure composed of a hard segment (HS) composed of isocyanate and chain extender and a soft segment (SS) composed of polyol. PU has excellent mechanical properties such as high elongation, toughness, and strain recovery, which is caused by microphase separation caused by the thermodynamic incompatibility between HS and SS. When microphase separation occurs, the HS domains are dispersed in the SS matrix, and the HS are combined together by hydrogen bonds to form microphases, acting as physical crosslinking points in the domains, so its tensile properties are related to the microphase separation structure.

[0003] At present, the structure-property relationship of PU has been extensively studied, and customized properties can be obtained by carefully designing the soft and hard segment structures. Since hydrogen bonds have high directionality and bonding strength, they are conducive to microphase separation and the formation of independent microdomains in the soft and hard segments. In previous studies, it has been confirmed that the introduction of groups with multiple hydrogen bond structures in the main chain or side chain of PU, such as urea bonds, ureidopyrimidone (Upy), hydrazide, etc., to form double hydrogen bonds, quadruple hydrogen bonds and multiple hydrogen bonds, respectively, can significantly improve the microphase separation structure. Previous studies have mainly focused on systems that can form multiple hydrogen bonds, but the synthesis of these polyurethanes or polyurea elastomers is complex, and the solubility of chain extenders containing multiple hydrogen bonds in common polar solvents is low, so they are not suitable for large-scale production and preparation. Summary of the invention

[0004] In view of the above problems existing in the prior art, the purpose of the present application is to provide a polyurethane elastomer using squaramide chain extension. Another purpose of the present application is to provide a method for preparing the polyurethane elastomer.

[0005] In order to solve the above problems, the technical solutions adopted in this application are as follows: In a first aspect, the present application provides a polyurethane elastomer using squaramide chain extension, wherein the chain extender used is a mixture of squaramide and small molecule diols, and the squaramide accounts for 5.0-50.0% of the total mass of the chain extender.

[0006] In the first aspect of the present application, the small molecule diol is one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0007] In a second aspect, the present application provides a method for preparing the above-mentioned polyurethane elastomer, characterized in that a mixture of squaramide and small molecule diol is used as a chain extender, and the squaramide accounts for 5.0-50.0% of the total mass of the chain extender.

[0008] In the second aspect of the present application, the small molecule diol is one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0009] In the second aspect of the present application, the mass of the chain extender accounts for 0.30-4.50% of the mass of the polyurethane.

[0010] In the second aspect of the present application, a catalyst is added to a polyol oligomer, and a measured amount of isocyanate is added dropwise. After the addition is completed, an N,N-dimethylformamide solution in which a chain extender is dissolved is added dropwise, and the solution concentration is 30-70%. After the addition is completed, the reaction is continued for 1-3 hours. The above reaction is carried out at 60-85°C. After the solvent is removed from the solution after the reaction is completed, the polyurethane elastomer is obtained.

[0011] In the second aspect of the present application, the polyol oligomer is at least one of polytetramethylene glycol, polyadipate glycol ester glycol, polycaprolactone diol, and polycarbonate diol, and the molecular weight of the polyol oligomer is 600-4000 g / mol.

[0012] In the second aspect of the present application, when the polyol oligomer is polyadipate diol, the diol monomer in the polyadipate diol is at least one of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and pentanediol.

[0013] In the second aspect of the present application, the catalyst is stannous octoate, and the amount used is 0.005% of the mass of the polyol oligomer.

[0014] In the second aspect of the present application, the isocyanate used is at least one of IPDI, HDI, XDI, HMDI, TDI, and MDI.

[0015] Compared with the prior art, the beneficial effects of the present application are at least: At the recommended ratio of styrene amide to diol, relative to styrene amide polyurea elastomers containing the same molar mass of chain extension or diol-extended polyurethane elastomers, in the polyurethane elastomer prepared in the present application, styrene amide acts as a physical cross-linking point to increase the strength, while diol improves the migration of the molecular chain, and their synergistic effect jointly improves the mechanical properties, and the polyurethane elastomer is balanced especially in terms of tensile strength, elongation and material toughness.

[0016] The remaining advantages of the present application will be partially explained in the following description, and some will be obvious from the description, or can be learned through the implementation of the embodiments of the present application. DETAILED DESCRIPTION

[0017] To make the purpose, technical scheme and beneficial effect of the content of the present application clearer, each embodiment of the present application will be described in detail below. However, the embodiments described below are exemplary and are only used to explain the content of the present application, and cannot be interpreted as limiting the content of the present application. It can be understood by those of ordinary skill in the art that in each embodiment of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation mode of the present application should not be construed as any limitation, and the various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0018] This application adopts a new structural unit, squaramide (3,4-diamino-3-cyclobutene-1,2-dione, CAS No.: 5231-89-0), which is used in combination with a general diol chain extender. Within a certain ratio range, the prepared polyurethane elastomer is superior to the polyurethane using squaramide or diol alone. Squaramide is a class of cyclobutene derivatives with a rigid conformation. Its molecular structure contains two close NH hydrogen bond donors and two C=O hydrogen bond acceptors. It has unique physical and chemical properties and is widely used in the fields of organic catalysis, molecular recognition and self-assembly. From the perspective of molecular structure, squaramide is similar to urea bond. Both can provide hydrogen bonds through NH as hydrogen bond donors and can also accept hydrogen bonds through O atoms as hydrogen bond acceptors. However, unlike the urea group, the four-membered ring structure of squaramide expands its range of accepting and providing hydrogen bonds. The distance between its two sets of NH bonds is 2.8Å, which has greater advantages in forming hydrogen bonds. In addition, the cyclobutenedione system in the squaramide unit can form a resonance structure with two positive charges. According to the Hückel aromaticity rule, it has aromaticity, and the aromaticity of the squaramide will be enhanced after forming a stable hydrogen bond complex.

[0019] The present application provides a polyurethane elastomer using squaramide to extend the chain, wherein the chain extender used is a mixture of squaramide and small molecule diols.

[0020] The present application provides a method for preparing the above-mentioned polyurethane elastomer using squarylamide chain extension. In specific implementation, the preparation method can be implemented according to the steps described in the following Examples 1, 2, 3 and 4.

[0021] Example 1 Polytetramethylene glycol with Mw=2000 was selected as the soft segment, 1,4-butanediol and squarylamide were mixed for chain extension, IPDI was selected for isocyanate, and the molar ratio of polydiol, chain extender and isocyanate was 1:0.5:1.5. The specific feed ratio is shown in Table 1.

[0022] Table 1 Feed ratio of Example 1 and control sample

[0023] 100g of polytetrahydrofuran polyether was dehydrated at 120℃ for 2h, cooled to 40℃, and then 5mg of stannous octoate was added. 16.67g of IPDI was added dropwise at 65℃. After the addition was completed, 0.56g of squaramide and 1.80g of 1,4-butanediol were dissolved in N,N-dimethylformamide (DMF) solution, and the solution concentration was 35%. After the addition was completed, the temperature was raised to 85℃ and the reaction was continued for 1.5h. After the solvent was removed from the solution after the reaction was completed, the polyurethane elastomer of Example 1 containing squaramide chain extension was obtained.

[0024] In the above steps, 2.25 g of 1,4-butanediol or 2.80 g of squaramide was used as the chain extender, and the same reaction steps were followed to obtain control sample 1a and control sample 1b, respectively.

[0025] The mechanical properties of the polyurethane elastomer were tested by cutting into standard dumbbell-shaped test samples with a gauge length of 20 mm, a width of 4 mm, and a total length of 75 mm. The tensile speed was set to 250 ± 50 mm / min to obtain the tensile strength and elongation. The stress-strain curve was then integrated to obtain the tensile toughness, that is, tensile toughness = (breaking load * original cross-sectional area of ​​the sample) / (elongation of the sample after breaking). Example 1 Tensile strength 15.3 MPa, elongation 1200%, toughness 23.89 MJ / m 3 ; The tensile strength of the control sample 1a is 4.3MPa, the elongation is 830%, and the toughness is 4.56MJ / m 3 ; The tensile strength of the control sample 1b is 8.5MPa, the elongation is 750%, and the toughness is 8.76MJ / m 3 .

[0026] Example 2 Polybutylene adipate diol with Mw=4000 was selected as the soft segment, 1,4-butanediol and squarylamide were mixed for chain extension, TDI and HDI were mixed for isocyanate, and the molar ratio of polydiol, chain extender and isocyanate was 1:1.5:2.5. The specific feed ratio is shown in Table 2.

[0027] Table 2 Feed ratio of Example 2 and control sample

[0028] 100g of polybutylene adipate diol was dehydrated at 120℃ for 2h, cooled to 40℃, and then 5mg of stannous octoate was added. Mixed isocyanate (8.71g of TDI mixed with 2.10g of HDI) was added dropwise at 65℃. After the addition was completed, N,N-dimethylformamide (DMF) solution in which 1.40g of squaramide and 2.25g of 1,4-butanediol were dissolved was added dropwise, and the solution concentration was 38%. After the addition was completed, the temperature was raised to 85℃ and the reaction was continued for 1.5h. After the solvent was removed from the solution after the reaction was completed, the polyurethane elastomer of Example 2 containing squaramide chain extension was obtained.

[0029] In the above steps, 3.38 g of 1,4-butanediol or 4.20 g of squaramide was used as the chain extender, and the same reaction steps were followed to obtain control sample 2a and control sample 2b, respectively.

[0030] Referring to the method of Example 1, the mechanical properties of the polyurethane elastomer were tested. Example 2 had a tensile strength of 76.8 MPa, an elongation of 1500%, and a toughness of 149.9 MJ / m 3 ; The tensile strength of the control sample 2a is 24.3MPa, the elongation is 770%, and the toughness is 24.56MJ / m 3 ; The tensile strength of the control sample 2b is 48.5MPa, the elongation is 440%, and the toughness is 38.76MJ / m 3 .

[0031] Example 3 Polycaprolactone diol with Mw=1000 was selected as the soft segment, ethylene glycol and squaramide were mixed for chain extension, MDI was selected as isocyanate, and the molar ratio of polydiol, chain extender and isocyanate was 1:0.3:1.3. The specific feed ratio is shown in Table 3.

[0032] Table 3 Feed ratio of Example 3 and control sample

[0033] 100g polycaprolactone diol was dehydrated at 120℃ for 2h, cooled to 40℃, and then 5mg stannous octoate was added. 35.53g MDI was added dropwise at 65℃. After the addition was completed, 0.34g squaramide and 1.68g ethylene glycol were dissolved in N,N-dimethylformamide (DMF) solution, and the solution concentration was 35%. After the addition was completed, the temperature was raised to 85℃ and the reaction was continued for 1.5h. After the solvent was removed from the solution after the reaction was completed, the polyurethane elastomer of Example 3 containing squaramide chain extension was obtained.

[0034] In the above steps, 1.86 g of ethylene glycol or 3.36 g of squaramide was used as the chain extender, and the same reaction steps were followed to obtain control sample 3a and control sample 3b, respectively.

[0035] Referring to the method of Example 1, the mechanical properties of the polyurethane elastomer were tested. Example 3 had a tensile strength of 35.3 MPa, an elongation of 680%, and a toughness of 89.3 MJ / m 3 ; The tensile strength of the control sample 3a is 14.6MPa, the elongation is 830%, and the toughness is 54.56MJ / m 3 ; The tensile strength of the control sample 3b is 38.5MPa, the elongation is 350%, and the toughness is 38.76MJ / m 3 .

[0036] Example 4 Polyadipate diol (i.e., polydiol, polyester diol) with Mw=2000 is selected as the soft segment, wherein the diol is a mixed alcohol of 1,4-butanediol, ethylene glycol, and pentanediol, and the mass ratio of 1,4-butanediol, ethylene glycol, and pentanediol is 85:10:5; 1,4-butanediol and squaramide are mixed for chain extension, IPDI is selected for isocyanate, and the molar ratio of polydiol, chain extender, and isocyanate is 1:1:2. The specific feed ratio is shown in Table 4.

[0037] Table 4 Feed ratio of Example 4 and control sample

[0038] 100g of polyester diol was dehydrated at 120℃ for 2h, cooled to 40℃, and then 5mg of stannous octoate was added. 22.23g of IPDI was added dropwise at 65℃. After the addition was completed, N,N-dimethylformamide (DMF) solution in which 2.24g of squaramide and 2.70g of ethylene glycol were dissolved was added dropwise, and the solution concentration was 35%. After the addition was completed, the temperature was raised to 85℃ and the reaction was continued for 1.5h. After the solvent was removed from the solution after the reaction was completed, the polyurethane elastomer of Example 4 containing squaramide chain extension was obtained.

[0039] In the above steps, 4.51 g of 1,4-butanediol or 5.60 g of squaramide was used as the chain extender, and the same reaction steps were followed to obtain control sample 4a and control sample 4b, respectively.

[0040] Referring to the method of Example 1, the mechanical properties of the polyurethane elastomer were tested. Example 4 had a tensile strength of 85.3 MPa, an elongation of 660%, and a toughness of 119.3 MJ / m 3 ; The tensile strength of the control sample 3a is 35.6MPa, the elongation is 830%, and the toughness is 74.56MJ / m 3 ; The tensile strength of the control sample 3b is 68.5MPa, the elongation is 380%, and the toughness is 68.76MJ / m 3 .

[0041] In the present application, the catalyst may also be other conventional polyurethane elastomer catalysts, and the amount used is also the conventional amount.

[0042] It can be understood that the specific parameters of each step in Examples 1 to 4 above should not constitute any limitation on the specific implementation of the present application. Each embodiment describes how to prepare a polyurethane elastomer by styrene amide chain extension to obtain the styrene amide chain-extended polyurethane elastomer of the present application. The implementation details involved are preferred examples. The specific parameters can also refer to the following range to select specific values ​​within the range.

[0043] In the present application, the small molecule diol can be one of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or a combination of two or more thereof. The recommended ratio of small molecule diol to squaramide is that squaramide accounts for 5.0-50.0% of the total mass of chain extender, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%. The mass of chain extender accounts for 0.30-4.50% of the mass of polyurethane, such as 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%.

[0044] In the present application, the polyol oligomer is at least one of polytetrahydrofuran diol, polyadipate diol, polycaprolactone diol, and polycarbonate diol, and the molecular weight can be 600-4000 g / mol, such as 600 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, and 4000 g / mol. When the polyol oligomer is polyadipate diol, the diol monomer in the polyadipate diol is at least one of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and pentanediol. The isocyanate used is at least one of IPDI, HDI, XDI, HMDI, TDI, and MDI.

[0045] In the present application, the N,N-dimethylformamide solution of the chain extender has a solution concentration of 30-70%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%. After the chain extender is added dropwise, the reaction is continued for 1-3 hours, which can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours. The elastomer preparation process is carried out at 60-85°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C.

Claims

1. A polyurethane elastomer using squarylamide chain extension, characterized in that: The chain extender used is a mixture of squaramide and small molecule diol, and the squaramide accounts for 5.0-50.0% of the total weight of the chain extender.

2. The polyurethane elastomer using squarylamide chain extension according to claim 1, characterized in that: The small molecule diol is one or more of ethylene glycol, 1,4-butanediol and 1,6-hexanediol.

3. A method for preparing a polyurethane elastomer, characterized in that: A mixture of squaramide and small molecule diol is used as the chain extender, and the squaramide accounts for 5.0-50.0% of the total mass of the chain extender.

4. The method for preparing a polyurethane elastomer according to claim 3, characterized in that: The small molecule diol is one or more of ethylene glycol, 1,4-butanediol and 1,6-hexanediol.

5. The method for preparing a polyurethane elastomer according to claim 3, characterized in that: The mass of chain extender accounts for 0.30~4.50% of the mass of polyurethane.

6. The method for preparing a polyurethane elastomer according to any one of claims 3 to 5, characterized in that: A catalyst is added to the polyol oligomer, and a measured amount of isocyanate is added dropwise. After the addition is completed, an N,N-dimethylformamide solution in which a chain extender is dissolved is added dropwise, and the solution concentration is 30-70%. After the addition is completed, the reaction is continued for 1-3 hours. The above reaction is carried out at 60-85° C. After the solvent is removed from the solution after the reaction is completed, the polyurethane elastomer is obtained.

7. The method for preparing a polyurethane elastomer according to claim 6, characterized in that: The polyol oligomer is at least one of polytetrahydrofuran diol, polyadipate diol, polycaprolactone diol and polycarbonate diol, and the molecular weight of the polyol oligomer is 600-4000 g / mol.

8. The method for preparing a polyurethane elastomer according to claim 7, characterized in that: When the polyol oligomer is polyadipate diol, the diol monomer in the polyadipate diol is at least one of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol and pentanediol.

9. The method for preparing a polyurethane elastomer according to claim 6, characterized in that: The catalyst is stannous octoate, and its usage accounts for 0.005% of the mass of the polyol oligomer.

10. The method for preparing a polyurethane elastomer according to claim 6, characterized in that: The isocyanate used is at least one of IPDI, HDI, XDI, HMDI, TDI and MDI.

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