Polyurethane modified low-temperature adaptive protective earplug material and preparation process thereof

Abstract

The invention discloses a polyurethane modified low-temperature adaptive protective earplug material and a preparation process thereof, and belongs to the technical field of earplug materials. The earplug material comprises a component A, a component B, a component C and a component D, wherein the component A is prepared from isocyanate, 2-hydroxyethyl disulfide and octafluoro-1, 6-hexanediol; the component B comprises polyether polyol, perfluoropolyether glycol, polysiloxane, a foaming agent, a foam stabilizer, a dynamic cross-linking agent and a catalyst. 2-hydroxyethyl disulfide and octafluoro-1, 6-hexanediol are used for partially modifying a hard section of a polyurethane material, and perfluoropolyether glycol, polysiloxane and polyether polyol are grafted, so that the hardness of the earplug material at a low temperature is reduced through synergism of all the components, and the earplug material has low-temperature flexibility, tear resistance, hydrophobicity and pollution resistance; and low-temperature embrittlement can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of earplug materials, in particular to a polyurethane-modified low-temperature adaptable protective earplug material and a preparation process thereof. Background Art

[0002] As a key piece of equipment for combating the hazards of noise, protective earplugs have irreplaceable practical value in numerous scenarios, including industrial manufacturing, construction, aerospace, military operations, polar expeditions, and cold storage operations. In recent years, with the increasing number of operations in extreme environments, such as power transmission and transformation projects in high-latitude regions, the construction and maintenance of Antarctic research stations, and the operation of low-temperature cold chain logistics, more stringent requirements have been placed on the adaptability of protective earplug materials to low-temperature environments. In these scenarios, ambient temperatures are often far below the normal range, requiring protective earplug materials to maintain excellent protective performance while being able to withstand the various adverse effects of low temperatures, ensuring reliable hearing protection for users under extreme conditions.

[0003] Existing protective earplug materials primarily include silicone, standard polyurethane, polyvinyl chloride (PVC), and polyolefin foam. While their performance meets basic requirements at room temperature (20-30°C), they exhibit significant deficiencies at low temperatures (-10°C to -50°C). These deficiencies are manifested in the following ways: 1) Inferior mechanical properties. Standard polyurethane materials, due to strong hydrogen bonding between polar groups such as urea and urethane groups within their molecular chains, hinder molecular chain motion at low temperatures. Their glass transition temperature (Tg) is typically between -20°C and -10°C. When the ambient temperature falls below Tg, the material transitions from a highly elastic state to a glassy state, experiencing a sharp increase in hardness (Shore A hardness from 30-40 at room temperature to 80-90 at low temperatures), and a drop in elastic recovery to below 30%. This hardening phenomenon prevents the earplug from conforming closely to the ear canal contour, rendering it ineffective for protection. While silicone materials have a lower Tg (-60°C to -40°C), their compression set significantly increases at low temperatures, leading to relaxation after just one to two hours of wear, reducing sound insulation. 2) Low-temperature brittleness and shortened service life. Polyolefin foam materials (such as EVA) exhibit obvious brittle fracture below -20°C. Even slight external forces (such as ear canal compression) can cause cracks, with a crack growth rate 5-8 times that at room temperature. This reduces the service life from 30-50 cycles at room temperature to 5-10 cycles. 3) Extreme low-temperature environments present unique challenges. In scenarios such as polar expeditions (-40°C to -50°C) and high-altitude flight (stratospheric temperatures of -55°C), the flaws of existing materials are further amplified. After two hours at -40°C, the tensile strength of ordinary polyurethane earplugs drops from 3.5MPa to 1.2MPa, and the elongation at break drops from 400% to 50%.

[0004] Prior art CN116874737A discloses a slow-rebound, low-temperature noise-reducing earplug, primarily addressing the technical issues of polyurethane earplugs being too hard, hardening at low temperatures, and poor stretching and tearing after washing. However, the earplug is primarily made of hydrophilic polyether material, which lacks hydrophobicity and tends to crystallize and harden at low temperatures.

[0005] It can be seen that the existing technology has not solved the technical problems of low-temperature earplugs becoming hard, easily freezing, and easily breaking in low-temperature environments. It is urgent to develop a new earplug material suitable for low-temperature environments. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a polyurethane-modified low-temperature adaptable protective earplug material and a preparation process thereof. The earplug prepared from the material has suitable flexibility and hydrophobicity (icephobicity) in a low-temperature environment, and resists fracture-reorganization buffering stress at low temperatures, thereby avoiding brittle cracking.

[0007] The present invention is achieved through the following technical solutions: In a first aspect, a polyurethane-modified low-temperature adaptive protective earplug material is provided, which comprises the following components, calculated by weight: component A: 80-100 parts of isocyanate, 2-5 parts of 2-hydroxyethyl disulfide, and 2-5 parts of octafluoro-1,6-hexanediol; component B: 30-40 parts of polyether polyol, 40-50 parts of perfluoropolyether diol, 20-30 parts of polysiloxane, 0.1-1 part of foaming agent, 0.1-1.5 parts of foam stabilizer, 0.1-1 part of dynamic cross-linking agent, and 0.01-1 part of catalyst.

[0008] The isocyanate is at least one selected from p-phenylene diisocyanate, toluene diisocyanate, and 4,4'-diisocyanate diphenylmethane.

[0009] The dynamic cross-linking agent is selected from at least one of 3,3'-disulfide-1,2-propylene glycol (CAS: 4807-52-7) and hydroxy-triethylene glycol-disulfide bond-triethylene glycol-ethanol (CAS: 5663-81-7).

[0010] The polyether polyol is selected from at least one of polycaprolactone triol (PLACCE1305), polycaprolactone diol (PCL2000), polytetramethylene ether diol (PTMG2000), and polyoxypropylene ether diol (PPG220).

[0011] The molecular weight of the perfluoropolyether diol is 1000-10000 Da.

[0012] The foaming agent is selected from at least one of formic acid, acetic acid and water.

[0013] The foam stabilizer is selected from at least one of an organic silicon surfactant and a quaternary ammonium surfactant. Further, the organic silicon surfactant is selected from at least one of L-580 and B-8002.

[0014] The catalyst is selected from at least one of a tertiary amine catalyst and an organic tin compound, and the tertiary amine catalyst is further selected from at least one of α,ω-triethyldiamine, pentamethyldiethyltriamine and pentamethyldipropyltriamine.

[0015] In a second aspect, a method for preparing a polyurethane-modified low-temperature adaptable protective earplug material is provided. The specific method is as follows: S1: Weigh 80-100 parts of isocyanate, 2-5 parts of 2-hydroxyethyl disulfide, and 2-5 parts of octafluoro-1,6-hexanediol by mass and mix them to form component A.

[0016] S2: Weigh 30-40 parts of polyether polyol, 40-50 parts of perfluoropolyether diol, 20-30 parts of polysiloxane, 0.1-1 part of foaming agent, 0.1-1.5 parts of foam stabilizer, 0.1-1 part of dynamic crosslinking agent, and 0.01-1 part of catalyst by mass, and mix them evenly to form component B.

[0017] S3: Add component A to a reactor, control the temperature at 75-85°C, stir and react for 0.2-2h, then cool to 40-50°C to obtain a polyurethane modified prepolymer.

[0018] S4: Component B is added to a reactor containing a polyurethane-modified prepolymer, stirred for 5 minutes, heated to 70-80° C., maintained at the temperature and stirred for 3-10 hours, and the reaction is completed to obtain an earplug material.

[0019] Beneficial effects

[0020] The present invention provides a polyurethane-modified low-temperature adaptable protective earplug material and a preparation method thereof. The earplug prepared from the material has low-temperature flexibility, tear resistance, hydrophobicity, and stain resistance.

[0021] Isocyanate, 2-hydroxyethyl disulfide and octafluoro-1,6-hexanediol are added to the earplug material, and a modified polyurethane modified prepolymer is obtained by a prepolymerization method. 2-Hydroxyethyl disulfide introduces a disulfide bond into the polyurethane modified prepolymer, which can effectively reduce the rigidity of the hard segment of the polyurethane material and improve the self-healing property of the polyurethane material. Octafluoro-1,6-hexanediol is introduced into the polyurethane formed by polyisocyanate, which reduces the rigidity while improving the hydrophobicity, thereby preventing the earplug material from tearing due to water vapor freezing in a low-temperature environment.

[0022] The earplug material incorporates perfluoropolyether diol (a fluorocarbon chain structure that resists crystallization at low temperatures and maintains flexibility) and polydimethylsiloxane (the siloxane chain segment offers excellent flexibility and does not harden at low temperatures). The fluorinated components (octafluoro-1,6-hexanediol and perfluoropolyether diol) and the siloxane component (polydimethylsiloxane) synergistically enhance the material's low-temperature stability. The fluorinated groups lower the freezing point, while the siloxane segments exhibit excellent frost resistance, preventing the molecular chains from freezing or crystallizing at low temperatures. The fluorinated components (octafluoro-1,6-hexanediol and perfluoropolyether diol) impart low surface energy to the material, enhancing its hydrophobicity (reducing the adsorption of ear canal secretions) and improving its anti-fouling properties. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The described embodiments are only some preferred embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] In the examples, the experimental methods used are conventional or common methods in the art unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0025] The raw materials used in the embodiments and comparative examples are now described as follows: 4,4'-Diisocyanatodiphenylmethane: purchased from Wuhan Jushun Chemical Co., Ltd.

[0026] Perfluoropolyether diol (1500 Da) was purchased from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd.

[0027] Octafluoro-1,6-hexanediol was purchased from Hubei Nona Technology Co., Ltd.

[0028] 2-Hydroxyethyl disulfide: purchased from Shanghai Kuokun Biotechnology Co., Ltd.

[0029] Polydimethylsiloxane (D-61430) was purchased from Tianjin Xiens Biochemical Technology Co., Ltd.

[0030] 3,3'-dithiobis-1,2-propanediol: purchased from Zhengzhou Huiju Chemical Co., Ltd.; Foam stabilizer L580: Green Union (Jining) Chemical Technology Co., Ltd.

[0031] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0032] Example 1

[0033] Provided is a method for preparing a polyurethane-modified low-temperature adaptable protective earplug material, the specific method being as follows: S1: Weigh 90 parts by mass of 4,4'-diisocyanatodiphenylmethane (isocyanate), 3 parts by mass of 2-hydroxyethyl disulfide, and 3 parts by mass of octafluoro-1,6-hexanediol, and mix them to form component A.

[0034] S2: Weigh 35 parts of polytetramethylene ether glycol (polyether polyol), 40 parts of perfluoropolyether glycol, 30 parts of polydimethylsiloxane (polysiloxane), 0.5 parts of water (foaming agent), 0.6 parts of L580 (foam stabilizer), 1 part of 3,3'-disulfide-1,2-propylene glycol (dynamic crosslinking agent), and 0.5 parts of α,ω-triethylenediamine (catalyst) by mass, and mix them evenly to form component B.

[0035] S3: Component A was added to a reactor, the temperature was controlled at 80° C., and the reaction was stirred at 1000 rpm for 0.5 h, and then the temperature was lowered to 40° C. to obtain a polyurethane modified prepolymer.

[0036] S4: Component B was added to the reactor containing the polyurethane modified prepolymer, stirred at 1500 rpm for 5 min, heated to 70° C., maintained at the temperature and stirred for 5 h. After the reaction was completed, the earplug material was obtained.

[0037] Example 2-3 The preparation method of Example 2-3 is the same as that of Example 1, except that the amount of each component is adjusted.

[0038] Comparative Examples 1-6 Comparative Examples 1-6 were prepared in the same manner as Example 1, with the only difference being that the components or amounts were adjusted.

[0039] Table 1 Components and mass parts of Examples 1-3 and Comparative Examples 1-6

[0040] Performance verification test of Examples 1-3 and Comparative Examples 1-6 The tensile strength, elongation at break, and Shore A hardness of the earphone materials of Examples 1-3 and Comparative Examples 1-6 at -40°C, as well as the hydrophobicity at room temperature were tested.

[0041] The test was carried out in accordance with the provisions of GB / T1040.1-2018 "Determination of Tensile Properties of Plastics" to determine the elongation at break.

[0042] The test is carried out in accordance with the provisions of GB / T531-2008 "Test method for Shore A hardness of vulcanized rubber" to determine the Shore A hardness.

[0043] The test is carried out in accordance with the provisions of GB / T30693 "Test method for hydrophobicity of plastics" to measure the contact angle between the material and water.

[0044] Table 2 Performance verification test of Examples 1-3 and Comparative Examples 1-6

[0045] It can be seen from the data in the above table that, under the condition of -40°C, the earplug materials described in Examples 1-3 have a tensile strength of 9.1-9.6 MPa, an elongation at break of 398-432%, and a Shore A hardness of 30-32 HA.

[0046] 1) Compared with Comparative Example 1, Example 1 adds 2-hydroxyethyl disulfide, which has a disulfide bond, to Component A for prepolymerization. This effectively improves the brittleness of the hard segment (isocyanate segment) in the polyurethane material under low-temperature conditions, significantly improving low-temperature flexibility and reducing brittle fracture. Comparative Example 2, which does not add octafluoro-1,6-hexanediol compared to Example 1, strengthens intermolecular forces and increases hardness at low temperatures. This shows that octafluoro-1,6-hexanediol can reduce intermolecular forces (such as hydrogen bonds) and enhance low-temperature fluidity. Comparing Example 1 with Comparative Examples 1-3, octafluoro-1,6-hexanediol and 2-hydroxyethyl disulfide synergistically enhance the molecular fluidity of the polyurethane material at low temperatures, thereby reducing hardness and improving elongation at break.

[0047] 2) Compared with Comparative Example 4, Example 1 adds perfluoropolyether diol, which has excellent low-temperature fluidity and hydrophobicity, increasing the low-temperature flexibility and hydrophobicity (anti-icing) of the material prepared in Example 1. Compared with Comparative Example 5, Example 1 adds polydimethylsiloxane, a silicone material with high flexibility and surface smoothness, which can reduce the hardness of the material in Example 1 and improve the comfort of earplugs made from this material. Comparative Example 6 does not add polydimethylsiloxane and perfluoropolyether diol, resulting in the earplug material lacking hydrophobic properties and high hardness, making it unsuitable for earplugs required for low-temperature environments. Comparison of Example 1 with Comparative Examples 4, 5, and 6 shows that polydimethylsiloxane and perfluoropolyether diol can synergistically improve the low-temperature flexibility and hydrophobicity of polyurethane materials.

[0048] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A polyurethane-modified low-temperature adaptable protective earplug material, characterized in that: Calculated by weight, it includes the following components: Component A: 80-100 parts of isocyanate, 2-5 parts of 2-hydroxyethyl disulfide, and 2-5 parts of octafluoro-1,6-hexanediol; Component B: 30-40 parts of polyether polyol, 40-50 parts of perfluoropolyether diol, 20-30 parts of polysiloxane, 0.1-1 part of foaming agent, 0.1-1.5 parts of foam stabilizer, 0.1-1 part of dynamic crosslinking agent, and 0.01-1 part of catalyst.

2. The polyurethane modified low-temperature adaptable protective earplug material according to claim 1, characterized in that: The isocyanate is selected from at least one of p-phenylene diisocyanate, toluene diisocyanate, and 4,4'-diisocyanate diphenylmethane.

3. The polyurethane modified low-temperature adaptable protective earplug material according to claim 1, characterized in that: The dynamic cross-linking agent is selected from at least one of 3,3'-disulfide-bis-1,2-propylene glycol, hydroxyl-triethylene glycol-disulfide bond-triethylene glycol-ethanol.

4. The polyurethane modified low-temperature adaptable protective earplug material according to claim 1, characterized in that: The polyether polyol is selected from at least one of polycaprolactone triol, polycaprolactone diol, polytetramethylene ether diol, and polyoxypropylene ether diol.

5. The polyurethane modified low-temperature adaptable protective earplug material according to claim 1, characterized in that: The molecular weight of the perfluoropolyether diol is 1000-10000 Da.

6. The polyurethane modified low-temperature adaptable protective earplug material according to claim 1, characterized in that: The foam stabilizer is selected from at least one of an organic silicon surfactant and a quaternary ammonium salt surfactant.

7. The polyurethane modified low-temperature adaptable protective earplug material according to claim 1, characterized in that: The catalyst is selected from at least one of a tertiary amine catalyst and an organic tin compound.

8. The method for preparing the polyurethane-modified low-temperature adaptable protective earplug material according to any one of claims 1 to 7, characterized in that: S1: Weigh 80-100 parts of isocyanate, 2-5 parts of 2-hydroxyethyl disulfide, and 2-5 parts of octafluoro-1,6-hexanediol by mass and mix them to form component A; S2: Weigh 30-40 parts of polyether polyol, 40-50 parts of perfluoropolyether diol, 20-30 parts of polysiloxane, 0.1-1 part of foaming agent, 0.1-1.5 parts of foam stabilizer, 0.1-1 part of dynamic crosslinking agent, and 0.01-1 part of catalyst by mass, and mix them uniformly to form component B; S3: Add component A to a reactor, control the temperature at 75-85° C., stir and react for 0.2-2 hours, then cool to 40-50° C. to obtain a polyurethane modified prepolymer; S4: Add component B to the reactor containing the polyurethane modified prepolymer, stir, heat to 70-80°C, maintain the temperature and stir for 3-10 hours, and then complete the reaction to obtain the earplug material.

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