A divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight and its application

Abstract

The present invention belongs to the field of new materials, and particularly relates to a divalent hydroxyl-terminated chain extender with controllable dangling chain molecular weight and its application. The dangling chain extender is primarily prepared by stepwise reaction of monohydroxyl polymers of varying molecular weights, diisocyanates, and ternary chain extenders, along with a catalyst, utilizing differential reactivity. The extender can be used as a chain extender in the synthesis of polyurethane materials. The extender exhibits functional group-directed reaction, precise grafting sites, and flexible molecular weight design. Furthermore, the synthetic process is simple and cost-effective. Application of the dangling chain extender in polyurethane microporous elastomer materials can significantly improve the material's damping properties and dynamic-static stiffness ratio, making it suitable for the preparation of sound-absorbing and vibration-damping polyurethane microporous elastomer materials.

Description

Technical Field

[0001] The present invention belongs to the field of new materials, and in particular relates to a divalent terminal hydroxyl chain extender with controllable molecular weight of pendant chains and application thereof. Background Art

[0002] There are many ways to improve the shock-absorbing and damping properties of polyurethane microporous elastomers, including changing the ratio of soft and hard segments in the main chain, IPN interpenetrating network structure, multilayer composite structure, and dangling chain modification. Among them, dangling chain modification can not only improve the compatibility of soft and hard segments, but also form intermolecular hydrogen bonds, which has become a research hotspot in recent years.

[0003] Pendant chain modification refers to the introduction of freely swinging pendants into the main chain structure. The relaxation modes of the pendant motion are more complex and diverse. Although this will cause certain mechanical losses, it can penetrate deep into the hard segment structure, reducing the degree of microphase separation in the material and increasing hysteresis losses, thus giving the material excellent damping properties. Polyurethane materials containing long pendant chains have stronger intermolecular forces than those containing short pendant chains and can form stronger hydrogen bonds, which can significantly increase the damping temperature range of the material and shift it toward higher temperatures. However, current pendant chain modification typically utilizes bulk chain extenders to assemble multiple molecular chains to achieve the purpose of pendant chain introduction. The resulting molecular chain structure has poor regularity and low controllability.

[0004] Therefore, whether a new chain extender can be provided to improve the controllability and modification effect of the dangling chain modification has become one of the urgent problems to be solved by those skilled in the art. Summary of the Invention

[0005] The present invention addresses many deficiencies in the prior art and provides a divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight. The chain extender is mainly prepared by reacting a monohydroxy polymer, a diisocyanate and a ternary chain extender. The chain extender has the characteristics of controllable pendant chain molecular weight, group-oriented reaction, and stable storage. In addition, the chain extender excels in modifying and improving the sound absorption, shock absorption and damping properties of polyurethane microporous elastomer materials, can improve the hydrogen bonding effect and dynamic-static stiffness ratio within the material, and the preparation method is simple and controllable.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A dihydroxyl-terminated chain extender with controllable pendant chain molecular weight, the structural formula of the chain extender is:

[0008]

[0009] The raw material composition of the above chain extender is calculated by weight:

[0010]

[0011]

[0012] The monohydroxy polymer can be one of monohydroxy polydimethylsiloxane, polyethylene glycol monomethyl ether, and ethylene glycol monostearate; more preferably, polyethylene glycol monomethyl ether with a purity greater than 99.5% is used, and specifically polyethylene glycol monomethyl ether with a molecular weight of 200 to 2000 can be used. There are many types to choose from, and the choice can be flexible. The length of the hanging chain mainly depends on the molecular weight of polyethylene glycol monomethyl ether. By reacting it with other compounds in different proportions, a divalent terminal hydroxyl chain extender with hanging chains of different molecular weights is obtained. Polyethylene glycol monomethyl ether contains a large number of ether bonds and a low rotation barrier. While increasing the soft segment content in the material, it can also improve the compatibility of the soft and hard segments of the material and enhance the intermolecular force.

[0013] The diisocyanates described are toluene diisocyanate (2,4-TDI) and isophorone diisocyanate, with isophorone diisocyanate being particularly preferred. These diisocyanates exhibit low rigidity, low volatility, low activity, and a smooth and controllable reaction process. The presence of two -NCO groups with approximately a tenfold difference in reactivity facilitates selective, directed reactions. However, they must be maintained under a nitrogen atmosphere to minimize losses from water reactions. Products made from isophorone diisocyanate exhibit excellent optical stability and chemical resistance. Pendant chain extenders based on isophorone diisocyanate are stable for storage.

[0014] The ternary chain extender can be selected from one of 2-amino-1,3-propanediol, 3-amino-1,2-propanediol, and triethanolamine, and after vacuum drying and dehydration, it is dissolved in a solvent and placed under nitrogen protection for standby use. The nitrogen atmosphere is to prevent the polar material from absorbing water again after dehydration. The presence of water will react with isocyanate to produce by-products. Solvent dissolution can reduce the viscosity of the ternary chain extender, create conditions to improve the selectivity of the group reaction as much as possible, and enable the reaction to proceed gently. The above-mentioned ternary chain extender preferably uses 2-amino-1,3-propanediol, which has two hydroxyl groups and one amino group. When reacting with isocyanate groups at room temperature, the amino group's reactivity is far higher than that of the hydroxyl group by a hundred times. 2-amino-1,3-propanediol can still participate in the chain extension reaction of polyurethane normally after ensuring reaction with one amino group. The introduction of dangling chains can improve the compatibility of the soft and hard segments of the material, making the material have a certain strength, and improving the hydrogen bonding effect between molecules within the material and the dynamic and static stiffness ratio.

[0015] The catalyst can be an organotin catalyst, preferably dibutyltin dilaurate. This catalyst can reduce the activation energy, accelerate the reaction rate, and increase the degree of group reactivity without affecting the activity difference between the two -NCO groups of the diisocyanate. Studies have shown that this catalyst can also increase the activity difference between the two -NCO groups, making the reaction more likely to proceed as expected. Its presence in the chain extender, when subsequently prepared through the semi-prepolymer method, can accelerate and thoroughly enhance the overall reaction, resulting in superior product performance.

[0016] The solvent should be one that does not affect the radical reaction, has a low boiling point, and is easily removable later. Furthermore, solvents with boiling points below 100°C, such as acetone, dichloromethane, and trichloroethylene, can be selected. Acetone is preferred as a solvent due to its high volatility and ease of removal. The presence of the solvent significantly reduces the viscosity of the system, allowing for a gentle reaction. Medium-to-high-speed stirring increases the contact opportunities for the reactive groups, creating conditions that enhance the selectivity of the radical reaction and allow for a more thorough reaction.

[0017] Using the above reaction system, under the action of organotin catalyst and at a specific temperature, a variety of ratios can be selected to carry out the reaction. The preferred molar ratio of the characteristic functional groups of the diisocyanate to the monohydroxy polymer is:

[0018] The ratio of -NCO to -OH is 2:1. In this case, the reactivity of the two -NCO groups of the selected diisocyanate with the hydroxyl group differs by nearly 10-fold. At room temperature, the reactivity of -NH2 with -NCO is 100 times higher than that of -OH with -NCO. By leveraging this characteristic functional group reactivity differential, a monohydroxy polymer and diisocyanate undergo a monofunctional group-directed reaction, where -OH reacts with -NCO to form a bond. The remaining primary -NCO in the reaction product further reacts with the -NH2 of the ternary chain extender molecule, yielding a dangling chain extender with hydroxyl groups at both ends and a controllable molecular weight in the middle. Using a semi-prepolymer method, the dangling chain extender can be applied to polyurethane microporous elastomers, resulting in a polyurethane microporous elastomer with a high dangling chain content and a more uniform structure.

[0019] The preparation method of the above-mentioned divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight comprises the following specific steps:

[0020] (1) Add the monohydroxy polymer into a three-necked flask, heat and evacuate, stir for 2 hours to remove impurities and purify, then fill with nitrogen to release the pressure for protection;

[0021] (2) The three-necked flask was repeatedly filled with nitrogen and baked, and diisocyanate, solvent and catalyst were added, and a certain amount of monohydroxy polymer was slowly added dropwise with a micro syringe pump at a high speed and a certain temperature to react;

[0022] (3) Slowly drip the product obtained in step (2) into the flask containing the ternary chain extender using a microsyringe pump. After a period of reaction, remove the solvent and place the mixture in a vacuum oven at 50°C for 7 days before use.

[0023] More specific reaction steps are as follows:

[0024] Step (1), adding the monohydroxy polymer (AR) in the formula amount into a three-necked furnace with a stirring paddle and a thermocouple, heating to 110 ° C, evacuating to -0.096 MPa, stirring at medium speed for 2 h to fully remove the very small amount of water and small molecules in the material, and then filling with N2 to cool to room temperature for use;

[0025] Step (2), the three-necked flask is repeatedly filled with nitrogen and baked, and then the diisocyanate, 10-20 parts of solvent and catalyst in the three-necked flask are added, preheated to 40-70 ° C, and the monohydroxy polymer is added dropwise at a stirring speed of 600 r / min using a micro syringe pump at a dropping speed of 0.5-2 mL / min. The addition is completed within 1.5-2 h. After the addition is completed, the system is heated to 80 ° C and the reaction is continued for 2 h;

[0026] Step (3), slowly dissolving the ternary chain extender in the formula amount with 20-30 parts of solvent, heating to 25-50°C after fully dissolving for 4-6 hours, and adding the product in step (2) dropwise into the container containing the above-mentioned ternary chain extender with a microinjection pump at a dropping speed of 0.5-2mL / min, and completing the dropping within 2-3 hours; after the dropwise addition is completed, changing the temperature to 50°C and continuing the reaction for 4 hours to obtain a solvent-containing hanging chain extender; using a rotary evaporator to evacuate the above-mentioned product to -0.096MPa at 50°C and rotary evaporate for 1-3 hours to remove the solvent, and placing it in a vacuum oven at 50°C in a vacuum environment for 7 days to obtain a divalent terminal hydroxyl chain extender with controllable hanging chain molecular weight.

[0027] Adopt above-mentioned preparation method, preferably slowly inject with microinjection pump, provide more collision reaction opportunities to the group with high reactive activity in system, while ensuring efficiency, reduce rate of addition as much as possible, extend reaction time, can make system reaction degree more thorough.Reaction need be carried out at a certain temperature, and the reaction temperature selected by experiment is when ensuring group normal reaction and efficiency, keeps the activity difference of corresponding group as much as possible, and the higher the temperature, the smaller the activity difference.The present invention makes real-time Fourier transform infrared spectrum judgment with the product under different reaction time, and then reflects whether system reaction is sufficient under this length, finally determines the reaction time after above-mentioned optimization.Combining the above-mentioned method, can expand the sequential reaction order that group brings because of reactive activity with external reaction condition, can reduce system viscosity again, increase group collision chance.

[0028] The controllability of the synthesis process and molecular weight of the dihydroxyl-terminated chain extender was demonstrated through gel permeation chromatography and proton nuclear magnetic resonance spectroscopy. The peak damping value and dynamic-static stiffness ratio of the polyurethane microcellular elastomer modified with these dangling chains were significantly improved compared to the unmodified polyurethane. These results demonstrate that the dangling chain extender exhibits a positive feedback effect on the damping properties of the polyurethane microcellular elastomer when applied to the material.

[0029] The specific application process is:

[0030] 100 parts of polycaprolactone diol 2000 were heated to 110°C and -0.096 MPa to remove impurities for 2 hours, and then 25-35 parts of naphthalene diisocyanate were added. The mixture was reacted at 90°C in a three-necked flask for 2 hours to obtain an NDI-based prepolymer with a certain free isocyanate content as component A.

[0031] According to the above steps, a divalent terminal hydroxyl chain extender with controllable molecular weight of the hanging chain is synthesized. The components thereof are calculated by weight: 7-12 parts of the hanging chain extender, 0.3-2 parts of the foaming agent, preferably deionized water, and 0.1-0.5 parts of the foaming agent, which can be one of sodium dodecylbenzenesulfonate and Span 80. The three substances are fully mixed and emulsified at 3000 rpm for 1 hour for use as component B.

[0032] 100 parts of component A and 10-16 parts of component B were quickly mixed at 70-100°C, mixed for 20-50 seconds under mechanical stirring at 2000 rpm, and then quickly poured into a mold for compression molding for 1 hour. The modified polyurethane microporous elastomer was obtained after being taken out and placed in a 100°C forced air oven for vulcanization for 24 hours.

[0033] In summary, the dangling chain extender with controllable molecular weight synthesized by the present invention has a well-organized structure and can normally participate in the chain extension reaction of polyurethane prepolymers. The final reaction product has a more uniform structure compared to methods that introduce bulky chain extenders into the dangling chains. The dangling chains have controllable molecular weight and polar groups, resulting in high material strength and application in a variety of sound absorption and vibration damping applications, including home appliances, automobiles, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the H-NMR spectrum of the dangling chain extender 350 prepared in Example 3;

[0035] Figure 2 This is the SEM image of the polyurethane microporous elastomer synthesized using the linear chain extender prepared in Example 6;

[0036] Figure 3 This is the SEM image of the polyurethane microporous elastomer synthesized with the dangling chain extender prepared in Example 9. DETAILED DESCRIPTION

[0037] The following will further illustrate this invention with reference to specific implementation examples. The following implementation examples are intended only to provide a complete and clear explanation of the invention. The examples described are only partial implementation examples of the invention and are not intended to be exhaustive. All other implementation examples created based on this invention fall within the scope of protection of this invention.

[0038] Example 1

[0039] A divalent terminal hydroxyl chain extender material with controllable pendant chain molecular weight, wherein the components thereof are calculated in parts by weight:

[0040] Hanging chain synthesis:

[0041]

[0042] The synthesis steps are:

[0043] (1) Add 200 polyethylene glycol monomethyl ether into a three-necked flask, heat to 110°C and evacuate to -0.096 MPa, stir for 2 h to remove water and other small molecular substances, then fill with nitrogen to release the pressure for protection;

[0044] (2) After the three-necked flask was repeatedly filled with nitrogen and baked, isophorone diisocyanate, acetone and dibutyltin dilaurate were added and heated to 60°C. The polyethylene glycol monomethyl ether 200 treated in the above synthesis step (1) was slowly added dropwise at 500 rpm and 60°C with a micro syringe pump at a dropping speed of 0.5-2 mL / min. After the addition was completed, the mixture was reacted for 4 hours, and then the temperature was raised to 80°C and the reaction was continued for 2 hours to obtain product 1;

[0045] (3) After repeatedly filling the three-necked flask with nitrogen and baking, 2-amino-1,3-propanediol and acetone were added. After the solid particles were fully dissolved, the system was heated to 35°C and the product 1 was slowly added dropwise at a rate of 0.5-2 mL / min using a microsyringe pump. After reacting for 2-4 hours, the solvent was removed and the product was placed in a vacuum oven at 50°C for 7 days before use. Finally, the dangling chain extender 200 was obtained.

[0046] Example 2

[0047] A divalent terminal hydroxyl chain extender material with controllable pendant chain molecular weight, wherein the components thereof are calculated in parts by weight:

[0048] Hanging chain synthesis:

[0049]

[0050] The synthesis steps were carried out according to the steps in Example 1, with the following adjustments: polyethylene glycol monomethyl ether 200 was changed to polyethylene glycol monomethyl ether 350, the total molar ratio of each component remained unchanged, the dosage was adjusted as above, and the other specific operation steps were the same as in Example 1, and finally the dangling chain extender 350 was obtained.

[0051] Example 3

[0052] A divalent terminal hydroxyl chain extender material with controllable pendant chain molecular weight, wherein the components thereof are calculated in parts by weight:

[0053] Hanging chain synthesis:

[0054]

[0055] The synthesis steps are as follows: follow the steps in Example 1, except that the following adjustments are made: polyethylene glycol monomethyl ether 200 is changed to polyethylene glycol monomethyl ether 550, the total molar ratio of each component remains unchanged, the dosage is adjusted as above, and the other specific operation steps are the same as in Example 1, and finally the dangling chain extender 550 is obtained.

[0056] Example 4

[0057] A divalent terminal hydroxyl chain extender material with controllable pendant chain molecular weight, wherein the components thereof are calculated in parts by weight:

[0058] Hanging chain synthesis:

[0059]

[0060] The synthesis steps are as follows: follow the steps in Example 1, except for the following adjustments:

[0061] Polyethylene glycol monomethyl ether 200 was replaced with polyethylene glycol monomethyl ether 1000, the total molar ratio of each component remained unchanged, and the dosage was adjusted as above. In the synthesis step (2), polyethylene glycol monomethyl ether 1000 was initially added dropwise, and the temperature of the initial system was raised to 70°C. In the step (3), the product of step (2) was added dropwise, and the initial temperature of the system was raised to 40°C. The other specific operating steps were the same as in Example 1, and finally, the dangling chain extender 1000 was obtained.

[0062] Example 5

[0063] A divalent terminal hydroxyl chain extender material with controllable pendant chain molecular weight, wherein the components thereof are calculated in parts by weight:

[0064]

[0065]

[0066] The synthesis steps are as follows: proceed according to the steps in Example 1, with the following adjustments. Polyethylene glycol monomethyl ether 200 is replaced with polyethylene glycol monomethyl ether 1000, the total molar ratio of each component remains unchanged, and the dosage is adjusted as above. In the synthesis step (2), the polyethylene glycol monomethyl ether 1000 is initially added dropwise, and the temperature of the initial system is raised to 70°C. In step (3), the product of step (2) is added dropwise, and the initial temperature of the system is raised to 45°C. The other specific operation steps are the same as in Example 1, and finally, the dangling chain extender 2000 is obtained.

[0067] Application Example 6

[0068] The polyurethane microporous elastomer is synthesized from a divalent terminal hydroxyl chain extender material with controllable molecular weight of the pendant chain, and the components thereof are calculated in parts by weight:

[0069] Synthesis of NDI-based prepolymers:

[0070] 100 parts of polycaprolactone diol 2000

[0071] 30 parts of naphthalene diisocyanate

[0072] Synthesis of polyurethane microcellular elastomer:

[0073]

[0074] The experimental steps are:

[0075] Step (1) 100 parts of polycaprolactone diol 2000 were heated to 110° C. and -0.096 MPa to remove impurities for 2 hours, and then 30 parts of naphthalene diisocyanate were added. The mixture was reacted in a three-necked flask at 90° C. for 2 hours to obtain an NDI-based prepolymer with a certain free isocyanate content as component A.

[0076] The components of step (2) are calculated by weight: 5-10 parts of a linear chain extender, preferably 1,4-butanediol; 0.3-2 parts of a foaming agent, preferably deionized water; and 0.1-0.5 parts of a foaming agent, preferably Span 80. The three substances are fully mixed and emulsified at 3000 rpm for 1 hour for use as component B.

[0077] Step (3) Rapidly mix 100 parts of component A and 10-16 parts of component B at 70-100° C., mix for 20-50 seconds under mechanical stirring at 2000 rpm, then quickly pour into a mold and press mold for 1 hour. Take out and place in a 100° C. forced air oven for vulcanization for 24 hours to obtain a modified polyurethane microporous elastomer.

[0078] Application Example 7

[0079] The polyurethane microporous elastomer is synthesized from a divalent terminal hydroxyl chain extender material with controllable molecular weight of the pendant chain, and the components thereof are calculated in parts by weight:

[0080] Synthesis of NDI-based prepolymers:

[0081] 100 parts of polycaprolactone diol 2000

[0082] 30 parts of naphthalene diisocyanate

[0083] Synthesis of polyurethane microcellular elastomer:

[0084]

[0085] The synthesis steps were as described in Application Example 6, with the following adjustments: the linear chain extender was replaced with an equimolar amount of dangling chain extender 200, while the amounts of the remaining components remained unchanged. The variables were controlled and the control was rigorous to ensure experimental rigor.

[0086] Application Example 8

[0087] The polyurethane microporous elastomer is synthesized from a divalent terminal hydroxyl chain extender material with controllable molecular weight of the pendant chain, and the components thereof are calculated in parts by weight:

[0088] Synthesis of NDI-based prepolymers:

[0089] 100 parts of polycaprolactone diol 2000

[0090] 30 parts of naphthalene diisocyanate

[0091] Synthesis of polyurethane microcellular elastomer:

[0092]

[0093] The synthesis steps are as follows: Follow the steps in Application Example 6, with the following adjustments: Replace the linear chain extender with an equimolar amount of pendant chain extender 350, and keep the remaining components unchanged. Control variables and strictly control to ensure the rigor of the experiment.

[0094] Application Example 9

[0095] The polyurethane microporous elastomer is synthesized from a divalent terminal hydroxyl chain extender material with controllable molecular weight of the pendant chain, and the components thereof are calculated in parts by weight:

[0096] Synthesis of NDI-based prepolymers:

[0097] 100 parts of polycaprolactone diol 2000

[0098] 30 parts of naphthalene diisocyanate

[0099] Synthesis of polyurethane microcellular elastomer:

[0100]

[0101] The synthesis steps are as follows: Follow the steps in Application Example 6, with the following adjustments: Replace the linear chain extender with an equimolar amount of pendant chain extender 550, and keep the remaining components unchanged. Control variables and strictly control to ensure the rigor of the experiment.

[0102] Application Example 10

[0103] The polyurethane microporous elastomer is synthesized from a divalent terminal hydroxyl chain extender material with controllable molecular weight of the pendant chain, and the components thereof are calculated in parts by weight:

[0104] Synthesis of NDI-based prepolymers:

[0105] 100 parts of polycaprolactone diol 2000

[0106] 30 parts of naphthalene diisocyanate

[0107] Synthesis of polyurethane microcellular elastomer:

[0108]

[0109]

[0110] The synthesis steps were as described in Application Example 6, with the following adjustments: the linear chain extender was replaced with an equimolar amount of dangling chain extender 1000, while the amounts of the remaining components remained unchanged. The variables were controlled and the control was rigorous to ensure experimental rigor.

[0111] Application Example 11

[0112] The polyurethane microporous elastomer is synthesized from a divalent terminal hydroxyl chain extender material with controllable molecular weight of the pendant chain, and the components thereof are calculated in parts by weight:

[0113] Synthesis of NDI-based prepolymers:

[0114] 100 parts of polycaprolactone diol 2000

[0115] 30 parts of naphthalene diisocyanate

[0116] Synthesis of polyurethane microcellular elastomer:

[0117]

[0118] The synthesis steps are as follows: Follow the steps in Application Example 6, with the following adjustments: Replace the linear chain extender with an equimolar amount of pendant chain extender 2000, and keep the remaining components unchanged in the same amount. Control variables and strictly control to ensure the rigor of the experiment.

[0119] Chain extenders of different molecular weights are composed of Examples 1-5. Gel permeation chromatography (GPC) tests were performed to verify the molecular weight control of the product synthesis of the present invention. The results are shown in the following table. The actual molecular weight is close to the theoretical design value, proving that the reaction proceeds as expected.

[0120] Table 1 GPC test of dihydroxyl-terminated pendant chain extenders with different molecular weights

[0121]

[0122] Example 3 was selected and tested for hydrogen nuclear magnetic resonance spectroscopy. The results are as follows: Figure 1 The 350 H NMR spectrum of the dangling chain extender shows characteristic peaks near the fixed chemical shifts of the corresponding characteristic functional groups. Combining the two data together proves that the dangling chain extender was successfully synthesized.

[0123] Through the above table and Figure 1 The actual molecular weight of the dangling chain extender is close to the theoretical molecular weight, and the hydrogen atoms from the carbamate and urea groups formed by the reaction exhibit distinct characteristic peaks in the H-NMR spectrum. These two data points confirm that the experiment met expectations and demonstrates the ability to produce a dihydroxyl-terminated chain extender material with controllable dangling chain molecular weight. This dangling chain extender boasts controllable molecular weight and precise structure, a simple manufacturing process, and low cost. Its application in polyurethane microporous elastomers can improve the material's sound absorption and vibration damping properties, and has broad application prospects.

[0124] Application Example 6 is a polyurethane microporous elastomer synthesized using a common linear chain extender, i.e., the main chain system synthesized ultimately does not contain dangling chains. Application Examples 7-11 are polyurethane microporous elastomers synthesized using dangling chain extenders of different molecular weights.

[0125] The samples of Examples 6-11 were subjected to dynamic mechanical properties testing, dynamic-static stiffness ratio testing, and electron microscopy testing, as in Application Examples 6 and 9, to characterize the effects of different molecular weights of dangling chains on the damping properties and cell morphology of the polyurethane microcellular elastomer. The test results are summarized below.

[0126] Table 2 Damping properties of polyurethane microporous elastomers synthesized with linear chain extenders and dangling chain extenders of different molecular weights

[0127]

[0128] The experimental data above demonstrates that the polyurethane microporous elastomers modified with dangling chain extenders (Application Examples 7-11) exhibit higher peak damping values ​​and dynamic-static stiffness ratios than those synthesized with linear chain extenders. This demonstrates that the addition of dangling chain extenders to polyurethane microporous elastomers significantly improves their damping performance. Specifically, their application enhances their sound insulation, cushioning, and shock absorption properties. These materials can be used in cushioning and shock-absorbing polyurethane microporous elastomer panels and sound insulation materials, imparting excellent damping properties.

[0129] Depend on Figure 2 and 3 It can be seen that the addition of the dangling chain extender increases the molecular weight of the molecular chains within the system. Under the same reaction conditions, the bubbles in the material are more uniform and smaller than those in the polyurethane microporous elastomer synthesized with a linear chain extender. The presence of a large number of bubbles makes the material's stress response hysteresis more pronounced, exerting a positive feedback effect on the material's damping performance.

[0130] The various technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the various technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should all be considered to be within the scope of this specification. The description of the above implementation cases can be used to help understand the principles and methods of the present invention. However, the above implementation cases are not exclusive and should not be construed as limiting the present invention. At the same time, for those skilled in the art, according to the principles and methods of the present invention, flexible changes can be made in the specific implementation methods and application scopes.

Claims

1. A divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight, characterized in that: The structural formula is as follows: , where n is 4-45.

2. The divalent terminal hydroxyl chain extender with controllable dangling chain molecular weight according to claim 1, characterized in that: The raw material composition of the above chain extender is calculated by weight: 80-120 parts of monohydroxy polymer, 50-80 parts of diisocyanate, 20-40 parts of ternary chain extender, 0.05-0.3 parts of catalyst, 20-50 parts of solvent; The monohydroxy polymer is polyethylene glycol monomethyl ether; the diisocyanate is isophorone diisocyanate; the ternary chain extender is 2-amino-1,3-propylene glycol; the catalyst is selected from an organic tin catalyst; and the solvent is selected from one of acetone, dichloromethane, and trichloroethylene.

3. The divalent terminal hydroxyl chain extender with controllable dangling chain molecular weight according to claim 2, characterized in that: The monohydroxy polymer is selected from polyethylene glycol monomethyl ether with a molecular weight of 200-2000; the catalyst is selected from dibutyltin dilaurate; and the solvent is selected from acetone.

4. The divalent terminal hydroxyl chain extender with controllable dangling chain molecular weight according to claim 2 or 3, characterized in that: The characteristic functional group molar ratio of diisocyanate to monohydroxy polymer is: -NCO:-OH=2:

1.

5. The method for preparing the divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight according to claim 1, characterized in that: The specific steps are as follows: (1) Add the monohydroxy polymer into a three-necked flask, heat and evacuate, stir for 2 h to remove impurities and purify, then fill with nitrogen to release the pressure for protection; (2) The three-necked flask is repeatedly filled with nitrogen and baked, and diisocyanate, solvent and catalyst are added. A certain amount of monohydroxy polymer is slowly dripped into the flask at a high speed and a certain temperature using a micro syringe pump to react; (3) The product obtained in step (2) is slowly dripped into the flask containing the ternary chain extender using a micro syringe pump. After a period of reaction, the solvent is removed and the flask is placed in a vacuum oven at 50°C for 7 days to obtain a divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight. The monohydroxy polymer is polyethylene glycol monomethyl ether; the diisocyanate is isophorone diisocyanate; and the ternary chain extender is 2-amino-1,3-propylene glycol.

6. The method for preparing a divalent terminal hydroxyl chain extender with controllable dangling chain molecular weight according to claim 5, characterized in that: The specific steps are as follows: Step (1) adding the monohydroxy polymer in the formula amount into a three-necked furnace with a stirring blade and a thermocouple, heating to 110°C, evacuating to -0.096 MPa, stirring at a medium speed for 2 h to fully remove the very small amount of water and small molecules in the material, and then filling with N2 to cool to room temperature for use; Step (2), repeatedly filling the three-necked flask with nitrogen and baking it, then adding the formulated amount of diisocyanate, 10-20 parts of solvent and catalyst into the three-necked flask, preheating it to 40-70 ° C, and adding the above-mentioned monohydroxy polymer dropwise into it at a stirring speed of 600 r / min using a micro syringe pump at a dropping speed of 0.5-2 mL / min. The dropping is completed within 1.5-2 h. After the dropping is completed, the system is heated to 80 ° C and the reaction is continued for 2 h; Step (3), slowly dissolving the ternary chain extender in the formula amount with 20-30 parts of solvent, heating to 25-50 ° C after fully dissolving for 4-6 hours, and adding the product in step (2) dropwise into the container containing the above-mentioned ternary chain extender by a microinjection pump at a dropping speed of 0.5-2 mL / min, and completing the dropping within 2-3 hours; after the dropwise addition is completed, the temperature is changed to 50-65 ° C and the reaction is continued for 4 hours to obtain a solvent-containing hanging chain extender; using a rotary evaporator to evacuate the above-mentioned product to -0.096 MPa at 50 ° C and rotary evaporate for 1-3 hours to remove the solvent, and placing it in a vacuum oven at 50 ° C in a vacuum environment for 7 days to obtain a divalent terminal hydroxyl chain extender with controllable hanging chain molecular weight.

7. Use of the divalent terminal hydroxyl chain extender with controllable pendant chain molecular weight according to claim 1 in the preparation of polyurethane microporous elastomer materials.

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