A multi-level microstructured sound-transmitting polyurethane elastomer and its preparation method and application

Abstract

The present invention discloses a multi-level microstructured sound-transmitting polyurethane elastomer, its preparation method, and application. The polyurethane elastomer comprises, by weight, 50-90 parts of a polyurethane prepolymer, 10-50 parts of an epoxy resin, 10-40 parts of a curing agent, and 5-20 parts of a polar solvent. The polar solvent comprises one or a mixture of polar organic solvents selected from the group consisting of alcohols, ketones, esters, ethers, and thiols. The present invention utilizes the multi-level microstructured sound-transmitting polyurethane elastomer, its preparation method, and application. By rationally regulating the ratio of the polyurethane prepolymer and the epoxy resin, and controlling the ratio of the soft and hard segments to form an orderly migration of polar and non-polar bonds, a multi-level micro-nano protrusion structure can be formed on the surface of the material, achieving both excellent hydrophobicity and good sound transmission performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane materials, in particular to a multi-level microstructure sound-transmitting polyurethane elastomer and a preparation method and application thereof. Background Art

[0002] Waterproofing and antifouling marine equipment has always been a key issue in the field of marine engineering. The marine environment is plagued by a variety of biological and non-biological factors that can adversely affect acoustic equipment and materials. A major issue is the susceptibility of marine acoustic equipment and structures to fouling, which can lead to degradation or even failure of acoustic performance. Therefore, the development of antifouling marine acoustic materials is crucial to ensuring the stable operation of acoustic equipment.

[0003] Traditional antifouling elastomers have limitations in terms of performance and acoustic transparency. Traditional antifouling hydrophobic elastomers are typically made from silicone or fluorine-containing materials. While these materials offer good antifouling properties, they are not ideal waterproof and acoustically transparent materials. Currently, polyurethane is the most commonly used acoustically transparent material. Its impedance is similar to that of seawater. This acoustic impedance matching makes it an ideal acoustically transparent material, effectively transmitting sound energy while minimizing energy loss, giving it significant potential for application in marine engineering. Consequently, polyurethane is widely used in the manufacture of key components such as sonar reflectors, windows, and arrays.

[0004] With the growing demand for sound-permeable materials in the marine engineering field, sound-permeable materials are easily corroded by pollutants and corrosive media in the marine environment, resulting in performance degradation and shortened lifespan. In order to cope with the pollution problem in the marine environment, researchers have begun to pay attention to the waterproof and anti-fouling properties of sound-permeable materials. Materials with waterproof and anti-fouling properties can reduce the adhesion of moisture and pollutants on the surface, maintaining the cleanliness and performance stability of the materials.

[0005] Chinese patent CN108285522A discloses a method for preparing an epoxidized hydroxyl-terminated polybutadiene polyurethane low-surface-energy material. The method involves reacting an aliphatic isocyanate, hydroxyl-terminated polybutadiene, and dibutyltin dilaurate to produce a polyurethane prepolymer. An epoxy resin is then added to the prepolymer and the reaction continues to produce an epoxidized hydroxyl-terminated polybutadiene polyurethane. A diamine curing agent is then added to the epoxidized hydroxyl-terminated polybutadiene polyurethane, mixed, and poured into a mold coated with a release agent. The mixture is then cured in an oven at 80-90°C for 22-24 hours to produce the epoxidized hydroxyl-terminated polybutadiene polyurethane low-surface-energy material. The material has a tensile strength of 10-14 MPa, has Grade 1 adhesion to substrates, and a static water contact angle greater than 90°. It can be used in marine corrosion protection applications.

[0006] Chinese patent CN116063843A discloses a sealing and coating material for deep-sea acoustic transducers and its preparation method. The material constructs a polyurethane-epoxy resin interpenetrating network polymer with controllable chemical bonding. The raw materials include a polyurethane prepolymer, an epoxy resin prepolymer, and a polyurethane curing agent. The polyurethane prepolymer is made from isocyanate, a polyol, and a catalyst. The resulting material exhibits improved water permeability resistance, reduces the viscous modulus of the material's viscoelasticity, minimizes intermolecular friction, and reduces acoustic energy loss, thereby enhancing the material's acoustic transparency.

[0007] Current polyurethane-based acoustically transparent materials lack both acoustic transparency and waterproof and antifouling properties. Furthermore, existing acoustically transparent elastomers primarily enhance antifouling properties by adding anti-biofouling agents or using fungicides. However, most antifouling agents are toxic, and the use of harmful compounds in antifouling coatings for ships is internationally prohibited. Therefore, there is an urgent need to develop a polyurethane acoustically transparent material with both waterproof and antifouling properties. Summary of the Invention

[0008] The purpose of the present invention is to provide a multi-level microstructured sound-transmitting polyurethane elastomer and its preparation method and application, so as to solve the above-mentioned problems of using antifouling agents to increase the antifouling properties of polyurethane materials and the inability of polyurethane materials to take into account both sound transmission properties and waterproof and antifouling properties.

[0009] To achieve the above objectives, the first aspect of the present invention provides a multi-level microstructure sound-transmitting polyurethane elastomer, which includes 50 to 90 parts of polyurethane prepolymer, 10 to 50 parts of epoxy resin, 10 to 40 parts of curing agent and 5 to 20 parts of polar solvent in parts by weight.

[0010] Preferably, the NCO / OH value R in the polyurethane prepolymer is 1.4.

[0011] Preferably, the polyurethane prepolymer comprises 50-70 parts by weight of hydroxy-terminated polybutadiene, 1-5 parts by weight of catalyst and 20-40 parts by weight of isocyanate.

[0012] Preferably, the catalyst is one or more of an organotin catalyst, an organobismuth catalyst and an organoferron catalyst.

[0013] Preferably, the catalyst is dibutyltin dilaurate.

[0014] Preferably, the isocyanate is a mixture of dimer diisocyanate and one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate.

[0015] Preferably, the epoxy resin is bisphenol A epoxy resin.

[0016] Preferably, the curing agent is one or a mixture of 4,4'-diamino-3,3'-dichlorodiphenylmethane, 3,5-dimethylthiotoluenediamine or diethyltoluenediamine.

[0017] Preferably, the polar solvent includes one or a mixture of alcohol organic solvents, ketone polar organic solvents, ester polar organic solvents, ether polar organic solvents, and thiol polar organic solvents.

[0018] Preferably, the alcohol polar organic solvent is one or a mixture of methanol, ethanol, and n-butanol.

[0019] Preferably, the ketone polar organic solvent is acetone, butanone or a mixture of several thereof.

[0020] Preferably, the ester polar organic solvent is one or a mixture of methyl formate, dimethyl carbonate, and ethyl acetate.

[0021] Preferably, the ether polar organic solvent is one or a mixture of diethyl ether, isopropyl ether, n-butyl ether, and diphenyl ether.

[0022] Preferably, the mercaptan polar organic solvent is one or a mixture of methyl mercaptan, ethyl mercaptan, and ethanedithiol.

[0023] A second aspect of the present invention provides a method for preparing a multi-level microstructured sound-transmitting polyurethane elastomer, comprising the following steps:

[0024] (1) Preparation of polyurethane prepolymer

[0025] The polyurethane prepolymer was obtained by heating hydroxy-terminated polybutadiene, catalyst and isocyanate at 80°C for 4 hours, and the -NCO content was determined by titration, with the NCO / OH value R being fixed at 1.4.

[0026] (2) Preparation of polyurethane / epoxy resin system solution

[0027] Add epoxy resin to the polyurethane prepolymer and continue heating at 100°C for 2 hours to obtain a polyurethane / epoxy resin system solution, i.e., component A;

[0028] (3) Add the curing agent to the solvent with a mass ratio of curing agent to solvent of 1:1 and completely dissolve it, i.e. component B;

[0029] (4) Mix components A and B evenly in a polar solvent, cast into shape, and dry and solidify in an oven to obtain a polyurethane elastomer.

[0030] Preferably, the mass ratio of component A to component B in step (4) is (1-5):(1-5).

[0031] More preferably, the mass ratio of component A to component B in step (4) is 1:1.

[0032] Preferably, in step (4), components A and B are mixed evenly in a polar solvent, vacuum degassed for 2 minutes, and quickly poured into a mold to ensure that the elastomer is uniform and has no obvious bubbles. The mixture is then placed in an oven at 80° C. and cured for 20 hours to obtain a polyurethane elastomer.

[0033] A third aspect of the present invention provides an application of a multi-level microstructured sound-transmitting polyurethane elastomer, and an application of the polyurethane elastomer in waterproof, anti-fouling and sound-transmitting materials for marine equipment.

[0034] Therefore, the present invention adopts a multi-level microstructured sound-transmitting polyurethane elastomer of the above structure and its preparation method and application, which have the following beneficial effects:

[0035] (1) The present invention rationally regulates the ratio of polyurethane prepolymer and epoxy resin, controls the ratio of soft and hard segments to form an orderly migration of polar bonds and non-polar bonds, and can form a multi-level micro-nano protrusion structure on the surface of the material, which has both excellent hydrophobicity and good sound transmission performance.

[0036] (2) The microstructure of the surface of the polyurethane elastomer prepared by the present invention is similar to the bionic microstructure of biological epidermis, which makes the elastomer hydrophobic. At the same time, the microstructure increases the contact area between the material and sound waves, improves the absorption and scattering effects of sound waves, and thus improves the sound transmission performance. The prepared elastomer has both waterproof and antifouling properties and sound transmission properties, and is expected to play an important role in the field of waterproof, antifouling and sound transmission of marine equipment.

[0037] (3) The hydrophobic micro-nanostructured polyurethane elastomer prepared by the present invention has a density close to that of seawater, combining excellent hydrophobic and antifouling properties with good sound transmission, overcoming the limitations of traditional materials. This new elastomer has good durability and can withstand the influence of common external factors while maintaining stable hydrophobic properties. HTPB-type polyurethane and epoxy resin are relatively environmentally friendly materials, with no volatile organic compound emissions and no substances harmful to human health. It has broad application prospects in the field of antifouling and sound transmission.

[0038] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is an atomic force microscope scan of the elastomer prepared in Example 1;

[0040] Figure 2 Static water contact angle of the elastomer prepared for Example 1. DETAILED DESCRIPTION

[0041] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the present invention is not limited to this embodiment.

[0042] The components of the multi-level microstructured sound-transmitting polyurethane elastomers of Examples 1-5 are shown in Table 1. The catalyst used in Examples 1-5 is dibutyltin dilaurate, the epoxy resin is bisphenol A epoxy resin, and the curing agent is 4,4'-diamino-3,3'-dichlorodiphenylmethane.

[0043]

[0044] The preparation method of a multi-level microstructured sound-transmitting polyurethane elastomer comprises the following steps:

[0045] (1) Preparation of polyurethane prepolymer

[0046] The polyurethane prepolymer was obtained by heating hydroxy-terminated polybutadiene, catalyst and isocyanate at 80°C for 4 hours, and the -NCO content was determined by titration, with the NCO / OH value R being fixed at 1.4.

[0047] (2) Preparation of polyurethane / epoxy resin system solution

[0048] Add epoxy resin to the polyurethane prepolymer and continue heating at 100°C for 2 hours to obtain a polyurethane / epoxy resin system solution, i.e., component A;

[0049] (3) Add the curing agent to the solvent, the solvent is N, N-dimethylformamide, the mass ratio of curing agent to solvent is 1:1, and completely dissolve, namely component B;

[0050] (4) Mix components A and B evenly in a polar solvent with a mass ratio of component A to component B of 1:1. Vacuum degassing for 2 minutes, quickly pour into a mold to ensure that the elastomer is uniform and has no obvious bubbles, and place in an oven at 80°C for 20 hours to cure to obtain a polyurethane elastomer.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that in step (4), components A and B are directly mixed evenly, and a polyurethane elastomer is obtained after pouring and curing without adding a polar solvent.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that in step (4), components A and B are evenly mixed in dichloromethane, and a polyurethane elastomer is obtained after pouring and curing, and the added solvent is a non-polar solvent.

[0055] Comparative Example 3

[0056] The difference from Example 1 is that the NCO / OH value R of the polyurethane elastomer in step (1) is 3.5.

[0057] Test Example 1

[0058] The properties of the polyurethane elastomers of Examples 1 to 5 and Comparative Examples 1 to 3 were tested. The test results are shown in Table 2.

[0059]

[0060] Test Example 2

[0061] The elastomer prepared in Example 1 was tested by atomic force microscope scanning. Figure 1 The micro-convex structure on the surface of the elastomer can be seen from Figure 1 It can be seen that the elastomer prepared in Example 1 has a static water contact angle of 102°, and has low surface energy characteristics.

[0062] Therefore, the present invention adopts a multi-level microstructured sound-transmitting polyurethane elastomer with the above structure, as well as its preparation method and application. By reasonably regulating the ratio of polyurethane prepolymer and epoxy resin, controlling the ratio of soft and hard segments to form an orderly migration of polar bonds and non-polar bonds, a multi-level micro-nano protrusion structure can be formed on the surface of the material, which has both excellent hydrophobicity and good sound transmission performance.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multi-level microstructured sound-transmitting polyurethane elastomer, characterized by: The polyurethane elastomer comprises 50-90 parts of polyurethane prepolymer, 10-50 parts of epoxy resin, 10-40 parts of curing agent and 5-20 parts of polar solvent in parts by weight; The polyurethane prepolymer comprises 50-70 parts by weight of hydroxyl-terminated polybutadiene, 1-5 parts by weight of a catalyst, and 20-40 parts by weight of an isocyanate, wherein the NCO / OH value R of the polyurethane prepolymer is 1.4; The polar solvent includes one or a mixture of alcohol polar organic solvents, ketone polar organic solvents, ester polar organic solvents, ether polar organic solvents, and thiol polar organic solvents.

2. The multi-level microstructured sound-transmitting polyurethane elastomer according to claim 1, characterized in that: The epoxy resin is bisphenol A type epoxy resin.

3. The multi-level microstructured sound-transmitting polyurethane elastomer according to claim 1, characterized in that: The curing agent is one or a mixture of 4,4'-diamino-3,3'-dichlorodiphenylmethane, 3,5-dimethylthiotoluenediamine or diethyltoluenediamine.

4. The method for preparing a multi-level microstructured sound-transmitting polyurethane elastomer according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Preparation of polyurethane prepolymer The polyurethane prepolymer was obtained by heating hydroxy-terminated polybutadiene, catalyst and isocyanate at 80°C for 4 hours, and the -NCO content was determined by titration, with the NCO / OH value R being fixed at 1.

4. (2) Preparation of polyurethane / epoxy resin system solution Add epoxy resin to the polyurethane prepolymer and continue heating at 100°C for 2 hours to obtain a polyurethane / epoxy resin system solution, i.e., component A; (3) Add the curing agent to the solvent with a mass ratio of curing agent to solvent of 1:1 and completely dissolve it, i.e. component B; (4) Mix components A and B evenly in a polar solvent, cast into shape, and dry and solidify in an oven to obtain a polyurethane elastomer.

5. The method for preparing a multi-level microstructured sound-transmitting polyurethane elastomer according to claim 4, characterized in that: The mass ratio of component A to component B in step (4) is (1~5):(1~5).

6. The method for preparing a multi-level microstructured sound-transmitting polyurethane elastomer according to claim 4, characterized in that: In step (4), components A and B are mixed evenly in a polar solvent, vacuum degassed for 2 minutes, and quickly poured into a mold to ensure that the elastomer is uniform and has no obvious bubbles. The elastomer is then cured in an oven at 80°C for 20 hours to obtain a polyurethane elastomer.

7. Use of the multi-level microstructured sound-transmitting polyurethane elastomer according to any one of claims 1 to 3, characterized in that: Application of polyurethane elastomers in waterproof, anti-fouling and sound-permeable materials for marine equipment.

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