Preparation method of sound insulation and noise reduction sponge and application thereof in air conditioner

Abstract

This invention relates to the field of polyvinyl alcohol (PVA) sponge technology, and discloses a method for preparing sound-insulating and noise-reducing sponge and its application in air conditioning. The invention involves mixing a surfactant, quaternary ammonium salt-modified cellulose-PVA, sodium bicarbonate, formaldehyde aqueous solution, and sulfuric acid solution, stirring to foam, and then heating and curing to obtain a sound-insulating and noise-reducing sponge. Using PVA as the sponge matrix and grafted cellulose nanocrystals as a reinforcing agent, the foamed sponge material exhibits higher tensile strength and sound absorption coefficient, good mechanical properties, and strong sound absorption, insulation, and noise reduction performance. The polyepoxy quaternary ammonium salt crosslinking agent contains a large number of quaternary ammonium salt groups, which are chemically crosslinked into the PVA sponge matrix, significantly improving the antibacterial and antifungal properties of the sponge material.

Description

Technical Field

[0001] This invention relates to the field of polyvinyl alcohol foam technology, specifically to a method for preparing a sound-insulating and noise-reducing foam and its application in air conditioning. Background Technology

[0002] Air conditioning foam materials primarily function to filter dust, absorb bacteria, and reduce noise, thus reducing dust pollution, sterilizing and preventing mold, and providing sound insulation and noise reduction. The main foam materials used are polyurethane foam, polyethylene foam, and self-adhesive foam. Polyvinyl alcohol (PVA) is inexpensive, readily available, and biodegradable, and can be foamed to produce high-performance foam materials, widely used in sound insulation and heat preservation materials, and drug delivery systems. Patent CN101508747B discloses melamine-modified polyvinyl alcohol formaldehyde foam material, its preparation method, and applications. Using PVA, melamine, formaldehyde, foaming agents, and pore-forming agents as raw materials, the prepared PVA formaldehyde foam material has advantages such as high mechanical strength and good temperature resistance, and can be used as medical sponges and sound insulation materials. However, this foam material does not exhibit good sound insulation, noise reduction, antibacterial, or anti-mold properties. Summary of the Invention

[0003] This invention solves the problems of poor mechanical strength, antibacterial properties, and sound absorption, sound insulation, and noise reduction performance of polyvinyl alcohol sponge.

[0004] Technical solution: A method for preparing sound-insulating and noise-reducing sponge:

[0005] Step A: Add potassium hydroxide to water to adjust the pH to 10-11, add cellulose nanocrystals, stir, then add an aqueous solution of polyvinyl alcohol and a polyepoxy quaternary ammonium salt crosslinking agent. Stir and react at 45-60℃ for 6-12 hours, filter, wash with water and ethanol, and dry to obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol.

[0006] Step B: Add surfactant and quaternary ammonium salt modified cellulose-polyvinyl alcohol to water, heat and stir, then add sodium bicarbonate, formaldehyde aqueous solution and sulfuric acid solution, stir and foam for 10-20 minutes, then heat and cure at 45-65℃ for 2-4 hours, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0007] Preferably, in step A, the mass ratio of cellulose nanocrystals, polyvinyl alcohol, and polyepoxy quaternary ammonium salt crosslinking agent is (5-40):100:(1-6).

[0008] Preferably, the surfactant in step B is OP-10 or Triton X-100.

[0009] Preferably, the preparation method of the polyepoxy quaternary ammonium salt crosslinking agent is as follows:

[0010] (1) Toluene, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3-dimethylamino-1-propanol, and 4-dimethylaminopyridine are added to a reaction vessel. The mixture is heated to 60-85℃ and reacted for 3-5 hours. Then, it is cooled to 20-30℃, and N,N-dicyclohexylcarbodiimide is added. The reaction continues for 12-18 hours. The mixture is then distilled under reduced pressure, washed with water, and the product is recrystallized in ethanol to obtain the tertiary amine precursor. The reaction formula is:

[0011]

[0012] (2) Add ethanol, tertiary amine precursor, epichlorohydrin, and potassium sulfate to a reaction vessel, heat to 50-80℃, stir for 3-6 minutes, distill under reduced pressure, wash with water, and recrystallize the product in a mixed solution of ethanol and ethyl acetate to obtain a polyepoxy quaternary ammonium salt crosslinking agent. The reaction formula is:

[0013]

[0014] Preferably, the molar ratio of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3-dimethylamino-1-propanol, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide is 1:(4.4-5.2):(0.4-0.48):(4.4-5.6).

[0015] Preferably, in (2), the molar ratio of the tertiary amine precursor, epichlorohydrin, and potassium sulfate is 1:(4.4-4.8):(0.1-0.12).

[0016] Technical Effects: The polyepoxy quaternary ammonium salt crosslinking agent of this invention contains multiple epoxy groups, which can undergo ring-opening crosslinking reactions with polyvinyl alcohol and the hydroxyl groups of cellulose nanocrystals, improving the interfacial bonding force between the two and forming a tight and stable crosslinking network. Simultaneously, the molecular chain crosslinking network contains rigid and stable biphenyl structures. Using polyvinyl alcohol as the sponge matrix and grafted cellulose nanocrystals as the reinforcing agent, the foamed sponge material exhibits higher tensile strength and mechanical properties. Furthermore, its sound absorption coefficient reaches 0.675-0.813, demonstrating excellent sound absorption, sound insulation, and noise reduction performance.

[0017] The polyepoxy quaternary ammonium salt crosslinking agent of the present invention contains a large number of quaternary ammonium salt groups, which are chemically crosslinked into the polyvinyl alcohol sponge matrix. It has a strong inhibitory and bactericidal effect on Staphylococcus aureus and Escherichia coli, and significantly improves the antibacterial and antifungal properties of sponge materials. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0019] Polyvinyl alcohol in the specific implementation method is from Henan Youchuang Chemical Products Co., Ltd. Cellulose nanocrystals are from Jiangsu Jufeng Chemical Technology Co., Ltd.

[0020] Example 1

[0021] (1) Add 20 mL of toluene, 5 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 22 mmol of 3-dimethylamino-1-propanol, and 2.4 mol of 4-dimethylaminopyridine to the reaction vessel, heat to 60 °C, react for 5 h, then cool to 20 °C, add 22 mmol of N,N-dicyclohexylcarbodiimide, continue the reaction for 18 h, distill under reduced pressure, wash with water, and recrystallize the product in ethanol to obtain the tertiary amine precursor.

[0022] (2) Add 4 mL of ethanol, 3 mmol of tertiary amine precursor, 13.2 mmol of epichlorohydrin, 0.36 mmol of potassium sulfate and 2 mL of water to a reaction vessel, heat to 50 °C, stir and react for 3 h, distill under reduced pressure, wash with water, and recrystallize the product in a mixed solution of ethanol and ethyl acetate to obtain a polyepoxy quaternary ammonium salt crosslinking agent.

[0023] (3) Add potassium hydroxide to 10 mL of water to adjust the pH to 10, add 0.5 g of cellulose nanocrystals, stir, add 100 mL of aqueous solution containing 10 g of polyvinyl alcohol and 0.1 g of polyepoxy quaternary ammonium salt crosslinking agent, stir and react at 60 °C for 6 h, filter, wash with water and ethanol, dry, and obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol.

[0024] (4) Add 0.6g surfactant OP-10 and 10g quaternary ammonium salt modified cellulose-polyvinyl alcohol to 200mL water, heat and stir, then add 2g sodium bicarbonate, 18mL formaldehyde aqueous solution (mass fraction 37%) and 36mL sulfuric acid solution (mass fraction 50%), stir and foam for 10min, then heat and cure at 45℃ for 4h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0025] Example 2

[0026] (1) Add 25 mL of toluene, 5 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 26 mmol of 3-dimethylamino-1-propanol, and 2 mmol of 4-dimethylaminopyridine to the reaction vessel, heat to 85 °C, react for 3 h, then cool to 30 °C, add 28 mmol of N,N-dicyclohexylcarbodiimide, continue the reaction for 12 h, distill under reduced pressure, wash with water, and recrystallize the product in ethanol to obtain the tertiary amine precursor.

[0027] (2) Add 4 mL of ethanol, 3 mmol of tertiary amine precursor, 14.4 mmol of epichlorohydrin, 0.3 mmol of potassium sulfate and 2 mL of water to a reaction vessel, heat to 80 °C, stir and react for 6 h, distill under reduced pressure, wash with water, and recrystallize the product in a mixed solution of ethanol and ethyl acetate to obtain a polyepoxy quaternary ammonium salt crosslinking agent.

[0028] (3) Add potassium hydroxide to 20 mL of water to adjust the pH to 10, add 1.5 g of cellulose nanocrystals, stir, add 100 mL of aqueous solution containing 10 g of polyvinyl alcohol and 0.25 g of polyepoxy quaternary ammonium salt crosslinking agent, stir and react at 45 °C for 12 h, filter, wash with water and ethanol, dry, and obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol.

[0029] (4) Add 2g of surfactant Triton X-100 and 10g of quaternary ammonium salt modified cellulose-polyvinyl alcohol to 200mL of water, heat and stir, then add 2g of sodium bicarbonate, 15mL of formaldehyde aqueous solution (mass fraction 37%) and 32mL of sulfuric acid solution (mass fraction 50%), stir and foam for 20min, then heat and cure at 65℃ for 2h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0030] Example 3

[0031] (1) Add potassium hydroxide to 40 mL of water to adjust the pH to 10, add 2.8 g of cellulose nanocrystals, stir, add 100 mL of aqueous solution containing 10 g of polyvinyl alcohol and 0.4 g of polyepoxy quaternary ammonium salt crosslinking agent (prepared according to the method of Example 1), stir and react at 50 °C for 8 h, filter, wash with water and ethanol, dry, and obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol.

[0032] (2) Add 0.6g surfactant OP-10 and 10g quaternary ammonium salt modified cellulose-polyvinyl alcohol to 200mL of water, heat and stir, then add 6g sodium bicarbonate, 22mL formaldehyde aqueous solution (mass fraction 37%) and 36mL sulfuric acid solution (mass fraction 50%), stir and foam for 20min, then heat and cure at 45℃ for 3h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0033] Example 4

[0034] (1) Add potassium hydroxide to 40 mL of water to adjust the pH to 11, add 4 g of cellulose nanocrystals, stir, add 100 mL of aqueous solution containing 10 g of polyvinyl alcohol and 0.6 g of polyepoxy quaternary ammonium salt crosslinking agent (prepared according to the method of Example 1), stir and react at 45 °C for 12 h, filter, wash with water and ethanol, dry, and obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol.

[0035] (2) Add 0.8g surfactant OP-10 and 10g quaternary ammonium salt modified cellulose-polyvinyl alcohol to 200mL of water, heat and stir, then add 4g sodium bicarbonate, 16mL formaldehyde aqueous solution (mass fraction 37%) and 30mL sulfuric acid solution (mass fraction 50%), stir and foam for 10min, then heat and cure at 60℃ for 4h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0036] Comparative Example 1

[0037] (1) Add 0.6g surfactant OP-10 and 10g polyvinyl alcohol to 200mL of water, heat and stir, then add 2g sodium bicarbonate, 18mL formaldehyde aqueous solution (mass fraction 37%) and 36mL sulfuric acid solution (mass fraction 50%), stir and foam for 10min, then heat and cure at 45℃ for 4h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0038] Comparative Example 2

[0039] (1) Mix 0.5g of cellulose nanocrystals and 10g of polyvinyl alcohol to obtain a cellulose-polyvinyl alcohol blend.

[0040] (2) Add 0.6g surfactant OP-10 and 10g cellulose-polyvinyl alcohol blend to 200mL water, heat and stir, then add 2g sodium bicarbonate, 18mL formaldehyde aqueous solution (mass fraction 37%) and 36mL sulfuric acid solution (mass fraction 50%), stir and foam for 10min, then heat and cure at 45℃ for 4h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0041] Comparative Example 3

[0042] (1) Add potassium hydroxide to 10 mL of water to adjust the pH to 10, add 100 mL of aqueous solution containing 10 g of polyvinyl alcohol and 0.1 g of polyepoxy quaternary ammonium salt crosslinking agent (prepared according to the method of Example 1), stir and react at 60 °C for 6 h, filter, wash with water and ethanol, and dry to obtain quaternary ammonium salt modified polyvinyl alcohol.

[0043] (2) Add 0.6g surfactant OP-10 and 10g quaternary ammonium salt modified polyvinyl alcohol to 200mL water, heat and stir, then add 2g sodium bicarbonate, 18mL formaldehyde aqueous solution (mass fraction 37%) and 36mL sulfuric acid solution (mass fraction 50%), stir and foam for 10min, then heat and cure at 45℃ for 4h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0044] Comparative Example 4

[0045] (1) Add 3 mL of ethanol, 3 mmol of N,N,N',N'-tetramethylethylenediamine, 6.6 mmol of epichlorohydrin, 0.18 mmol of potassium sulfate, and 1.5 mL of water to a reaction vessel. Heat to 50 °C and stir for 3 h. Distill under reduced pressure, wash with water, and recrystallize the product in a mixed solution of ethanol and ethyl acetate to obtain an epoxy quaternary ammonium salt crosslinking agent. The structural formula is...

[0046] (2) Add potassium hydroxide to 10 mL of water to adjust the pH to 10, add 0.5 g of cellulose nanocrystals, stir, add 100 mL of aqueous solution containing 10 g of polyvinyl alcohol and 0.1 g of polyepoxy quaternary ammonium salt crosslinking agent, stir and react at 60 °C for 6 h, filter, wash with water and ethanol, dry, and obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol.

[0047] (3) Add 0.6g surfactant OP-10 and 10g quaternary ammonium salt modified cellulose-polyvinyl alcohol to 200mL water, heat and stir, then add 2g sodium bicarbonate, 18mL formaldehyde aqueous solution (mass fraction 37%) and 36mL sulfuric acid solution (mass fraction 50%), stir and foam for 10min, then heat and cure at 45℃ for 4h, wash with water and dry to obtain sound insulation and noise reduction sponge.

[0048] The sponge was prepared into specimens according to GB / T 6344-2008 standard, and its tensile strength was tested using a universal testing machine. The sound absorption coefficient of the sponge was tested according to GB / T 18696.1-2004 standard.

[0049] The antibacterial properties of the sponge were tested using the shaking bottle method. 5 mL of a 10% concentration was taken. 6 A suspension of Staphylococcus aureus or Escherichia coli at CFU / mL was added to a test tube, along with 0.1g of sponge (the sponge in Comparative Example 1 served as a blank control). The tube was shaken at 25°C for 3 hours at a frequency of 200 rpm. Then, phosphate buffer solution was added for a 10-fold serial dilution. 0.2mL of the diluted bacterial solution was spread onto an agar plate and incubated at 37°C for 24 hours in a constant temperature and humidity incubator. After incubation, colony counts were performed, and the inhibition rate was calculated.

[0050] Inhibition rate = (number of colonies in blank control sample - number of colonies in experimental sample) ÷ number of colonies in blank control sample × 100%.

[0051] Table 1. Sponge Performance Test

[0052]

[0053] After testing, the sound absorption coefficient of the sound-absorbing and noise-reducing sponges prepared in Examples 1-4 reached 0.675-0.813, and the tensile strength reached 57.1-78.2 MPa, exhibiting excellent sound absorption, noise reduction, and tensile strength. Furthermore, they demonstrated high antibacterial rates against Staphylococcus aureus and Escherichia coli, demonstrating excellent antibacterial performance. This is mainly because the polyepoxy quaternary ammonium salt crosslinking agent contains multiple epoxy groups, which can undergo ring-opening crosslinking reactions with polyvinyl alcohol and the hydroxyl groups of cellulose nanocrystals, improving the interfacial bonding force between the two and forming a stable crosslinking network. Simultaneously, the molecular chain crosslinking network contains rigid and stable biphenyl structures. Using polyvinyl alcohol as the sponge matrix and grafted cellulose nanocrystals as the reinforcing agent, the foamed sponge material has higher tensile strength and mechanical properties. Moreover, the polyepoxy quaternary ammonium salt crosslinking agent contains a large number of quaternary ammonium salt groups, which have a strong inhibitory and bactericidal effect on Staphylococcus aureus and Escherichia coli, significantly improving the antibacterial performance of the sponge material.

[0054] Comparative Example 1 did not include cellulose nanocrystals and polyepoxy quaternary ammonium salt crosslinking agents, resulting in sponge material with lower mechanical strength and poorer antibacterial properties.

[0055] Comparative Example 2 involved blending polyvinyl alcohol and cellulose nanocrystals into foam. The two materials exhibited low interfacial bonding and poor compatibility, failing to form a stable cross-linked network and lacking rigid and stable biphenyl structures. This resulted in low tensile strength and poor antibacterial properties of the sponge.

[0056] Comparative Example 3 did not contain cellulose nanocrystals, and the tensile strength of the sponge material was lower than that of Example 1.

[0057] The epoxy quaternary ammonium salt crosslinking agent in Comparative Example 4 has fewer epoxy groups and insufficient crosslinking sites, which prevents the formation of a stable crosslinking network between polyvinyl alcohol and cellulose nanocrystals. At the same time, the molecular chain crosslinking network does not contain rigid and stable biphenyl structures, resulting in the tensile strength of the sponge material being lower than that in Example 1.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for preparing a sound-insulating and noise-reducing sponge, characterized in that, The preparation method includes the following steps: Step A: Add potassium hydroxide and cellulose nanocrystals to water, stir, then add an aqueous solution of polyvinyl alcohol and a polyepoxy quaternary ammonium salt crosslinking agent. After stirring and reacting, filter, wash, and dry to obtain quaternary ammonium salt modified cellulose-polyvinyl alcohol. The structural formula of the polyepoxy quaternary ammonium salt crosslinking agent is as follows: Step B: Add surfactant and quaternary ammonium salt modified cellulose-polyvinyl alcohol to water, heat and stir, then add sodium bicarbonate, formaldehyde aqueous solution and sulfuric acid solution, stir to foam, heat to cure and shape, wash and dry to obtain sound insulation and noise reduction sponge.

2. The method for preparing sound-insulating and noise-reducing sponge according to claim 1, characterized in that, In step A, potassium hydroxide is added to adjust the pH of the water to 10-11.

3. The method for preparing sound-insulating and noise-reducing sponge according to claim 1, characterized in that, The reaction temperature in step A is 45-60℃, and the reaction time is 6-12h.

4. The method for preparing sound-insulating and noise-reducing sponge according to claim 1, characterized in that, In step A, the mass ratio of cellulose nanocrystals, polyvinyl alcohol, and polyepoxy quaternary ammonium salt crosslinking agent is (5-40):100:(1-6).

5. The method for preparing sound-insulating and noise-reducing sponge according to claim 4, characterized in that, The preparation method of the polyepoxy quaternary ammonium salt crosslinking agent is as follows: (1) Add toluene, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3-dimethylamino-1-propanol, and 4-dimethylaminopyridine to a reaction vessel, heat to 60-85℃, react for 3-5 h, then cool to 20-30℃, add N,N-dicyclohexylcarbodiimide, continue the reaction for 12-18 h, distill under reduced pressure, wash, recrystallize to obtain the tertiary amine precursor; (2) Add ethanol, tertiary amine precursor, epichlorohydrin, potassium sulfate and water to the reaction vessel, heat to 50-80℃, stir for 3-6 minutes, distill under reduced pressure, wash and recrystallize to obtain polyepoxy quaternary ammonium salt crosslinking agent.

6. The method for preparing sound-insulating and noise-reducing sponge according to claim 5, characterized in that, The molar ratio of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3-dimethylamino-1-propanol, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide in (1) is 1:(4.4-5.2):(0.4-0.48):(4.4-5.6).

7. The method for preparing sound-insulating and noise-reducing sponge according to claim 5, characterized in that, The molar ratio of the tertiary amine precursor, epichlorohydrin, and potassium sulfate in (2) is 1:(4.4-4.8):(0.1-0.12).

8. The method for preparing sound-insulating and noise-reducing sponge according to claim 1, characterized in that, In step B, the stirring and foaming time is 10-20 minutes, and the heating and curing temperature is 45-65℃ for 2-4 hours.

9. The method for preparing sound-insulating and noise-reducing sponge according to claim 1, characterized in that, The surfactant used in step B is OP-10 or Triton X-100.

10. The application of a sound-insulating and noise-reducing sponge obtained by the preparation method according to any one of claims 1-9 in air conditioning.

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