Melamine foam acoustical board with good thermal stability and preparation method of melamine foam acoustical board

Abstract

The invention relates to the technical field of sound-absorbing materials, and discloses a melamine foam sound-absorbing board with good thermal stability and a preparation method thereof, the melamine foam sound-absorbing board comprises a foaming liquid and a tetradecanoic acid and stearic acid eutectic mixture, and the melamine foam sound-absorbing board is prepared by foaming and pressing according to the formula. The preparation method comprises the following steps: S1, preparing a modified melamine-formaldehyde pre-condensation polymer; s2, adding a tetradecanoic acid and stearic acid eutectic mixture into the modified melamine-formaldehyde pre-condensation polymer, and uniformly stirring; s3, preparing foaming liquid; s4, performing microwave foaming; and S5, drying, pressing and forming. The melamine foam acoustic panel prepared by the invention not only has better sound absorption performance at normal temperature, but also keeps stable sound absorption performance at high temperature, and especially better keeps sound absorption performance to high-frequency sound waves. The melamine foam acoustical board disclosed by the invention has good high-temperature sound absorption performance, and the working scene of the melamine foam acoustical board is widened.

Description

Technical Field

[0001] The invention relates to the technical field of sound-absorbing materials, and in particular to a melamine foam sound-absorbing board with good thermal stability and a preparation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] With the rapid development of industrialization and urbanization, noise pollution has become an important factor affecting people's quality of life. Traditional sound-absorbing materials have problems such as high cost, poor sound absorption effect, and insufficient durability. Therefore, it is of great practical significance to develop a new type of sound-absorbing material with low cost, good sound absorption effect and strong durability.

[0004] Melamine foam is a lightweight, porous sound-absorbing material. Its internal three-dimensional mesh structure and high porosity (porosity of more than 99%) can effectively prevent air convection sound transmission. It has been widely studied for its excellent sound absorption performance and good mechanical properties. However, melamine foam is only suitable for working at relatively low temperatures. As the temperature rises, the sound absorption performance of melamine foam will decrease due to structural changes, so it is difficult to maintain stable performance under high temperature conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a melamine foam sound-absorbing board with good thermal stability and a preparation method thereof in view of the defects of the current melamine foam. The sound-absorbing board not only has excellent sound absorption performance but also has excellent thermal stability and durability, and the preparation cost is also low.

[0006] The technical solution of the present invention is as follows:

[0007] A melamine foam sound-absorbing board with good thermal stability comprises a foaming liquid and a eutectic mixture of myristic acid and stearic acid, and is made by foaming and pressing according to the above formula.

[0008] The chemical formula of tetradecanoic acid is C 14 H 28 O2, its English name is Myristic acid. The chemical formula of stearic acid is C 18 H 36 O2, its English name is Stearic acid.

[0009] Preferably, the mass ratio of the myristic acid and stearic acid eutectic mixture is: myristic acid:stearic acid is 6:4 to 7:3.

[0010] According to a preferred embodiment, the foaming liquid comprises a melamine-formaldehyde precondensate, and the melamine-formaldehyde precondensate is mixed with a eutectic mixture of myristic acid and stearic acid in a mass ratio of 20:1-2 to obtain a melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid;

[0011] The foaming liquid comprises the following components in parts by weight:

[0012] 100 parts of melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid, 1.8-3.0 parts of a surfactant, 10-18 parts of a foaming agent, 1.5-2.7 parts of a curing agent, 1.8-2.5 parts of an auxiliary agent and 0-30 parts of water.

[0013] Preferably, the foaming liquid comprises the following components in parts by weight: 100 parts of melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid, 2.5-2.8 parts of a surfactant, 16-17 parts of a foaming agent, 2.5-2.6 parts of a curing agent, 2.3-2.5 parts of an auxiliary agent and 0-30 parts of water.

[0014] Preferably, the melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid is modified by a modifier, and the modifier is polytetramethylene ether glycol (PTMEG), tris-(2-hydroxyethyl) isocyanurate (THIEC), nanocellulose crystals (NCC), polyvinyl alcohol (PVA) or diethylene glycol ether, etc., to improve the mechanical properties and pore structure of the foam.

[0015] Preferably, the surfactant is a mixture of anionic surfactant and nonionic surfactant, wherein:

[0016] The anionic surfactant is any one or more of polyether carboxylates, alkylbenzene sulfonates, alkyl sulfonates, succinate ester sulfonates, higher fatty amide sulfonates, fatty acid ester alkyl sulfonates, fatty acid polyoxyethylene ether sulfosuccinic acid monoester disodium, fatty alcohol sulfates, alkyl alcohol polyoxyethylene ether sulfates, fatty alcohol phosphates, and fatty alcohol polyoxyethylene ether phosphates;

[0017] The nonionic surfactant is any one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyethylene glycol fatty acid ester, and polyoxyethylene ether sorbitan fatty acid ester.

[0018] More preferably, the surfactant is a mixture of anionic surfactant and nonionic surfactant, wherein the anionic surfactant is alkylbenzene sulfonate;

[0019] The nonionic surfactant is any one or two of alkylphenol polyoxyethylene ether and polyoxyethylene ether sorbitan fatty acid ester.

[0020] Preferably, the mixing ratio of the anionic surfactant and the nonionic surfactant is: 50-90% anionic surfactant and 10-50% nonionic surfactant.

[0021] Preferably, the foaming agent is a physical foaming agent with a boiling point of 0 to 80°C.

[0022] Preferably, the foaming agent is any one or more of n-pentane, cyclopentane, n-hexane, cyclohexane, petroleum ether, 1,2-dichlorotetrafluoroethane, and 1,2,2-chloro-1,1-difluoroethane. More preferably, the foaming agent is any one or more of n-pentane, 1,2-dichlorotetrafluoroethane, and 1,2,2-trichloro-1,1-difluoroethane. More preferably, the foaming agent is n-hexane, cyclohexane, or n-pentane.

[0023] Preferably, the curing agent is any one or more of formic acid, acetic acid, n-butyric acid, oxalic acid, malonic acid, diacid, glutaric acid, toluenesulfonic acid, acrylic acid, hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. More preferably, the curing agent is sulfuric acid or formic acid.

[0024] Preferably, the auxiliary agent is one or more of a colorant, a fluorescent whitening agent, a UV stabilizer, and an anti-aging agent.

[0025] Another aspect of the present invention provides a method for preparing a melamine foam sound-absorbing board with good thermal stability, which comprises the following steps:

[0026] Step S1: Preparation of modified melamine-formaldehyde precondensate: After melamine, paraformaldehyde and water are reacted in a reactor for a certain period of time, polytetramethylene glycol is added to obtain a modified melamine-formaldehyde precondensate; preferably, the molar ratio of melamine to paraformaldehyde is 1:2-4. The reaction environment is an alkaline environment.

[0027] Step S2: post-treatment of the modified melamine-formaldehyde precondensate: adding 5%-10% by mass of a eutectic mixture of myristic acid and stearic acid to the cooled modified melamine-formaldehyde precondensate and uniformly stirring to obtain a modified melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid;

[0028] Step S3: preparing a foaming liquid: placing the modified melamine-formaldehyde precondensate containing the eutectic mixture of myristic acid and stearic acid prepared in step S2, a surfactant, a foaming agent, a curing agent, an auxiliary agent and water in a reaction kettle and stirring and mixing to obtain a foaming liquid;

[0029] Step S4: Microwave foaming: sending the foaming liquid to a microwave device for foaming using microwave radiation to obtain a foamed material;

[0030] Step S5: post-processing: drying the obtained foamed material in an oven to constant weight, pressing and molding on a machine tool, and cutting and polishing the molded sound-absorbing board as required to meet specific size and shape requirements; thus, the melamine foam sound-absorbing board with good thermal stability of the present application is obtained.

[0031] Furthermore, in some embodiments of the present application, in the above step S2, the mass ratio of myristic acid to stearic acid is between 6:4 and 7:3; preferably 7:3. Under this ratio, the melting point of the eutectic mixture is about 45°C. The temperature of the foaming liquid needs to be maintained at 45°C-50°C during stirring. Prevent saponification reaction caused by the high temperature alkaline environment when adding the eutectic. When adding the eutectic, add a regulator to make the reaction environment return to neutral or slightly acidic.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. A melamine foam sound-absorbing board with good thermal stability, which improves the sound absorption performance: the introduction of the eutectic mixture can improve the pore structure of the melamine foam, thereby enhancing its ability to absorb sound waves; at room temperature, its sound absorption coefficient is improved;

[0034] 2. A melamine foam sound-absorbing board with good thermal stability. The addition of the eutectic mixture of tetradecanoic acid and stearic acid improves the heat resistance of the melamine foam, and can maintain its performance in a high temperature environment, and is suitable for use in sound-absorbing applications that require high temperature resistance; especially the sound absorption ability for high-frequency (greater than 500Hz) sound waves at high temperatures;

[0035] 3. A melamine foam sound-absorbing board with good thermal stability and excellent comprehensive performance. Environmental protection: the eutectic mixture is non-toxic and non-corrosive, meets national environmental protection standards, and is suitable for use in places with high environmental requirements, such as hospitals and schools; moisture-proof and mildew-proof: the characteristics of the eutectic mixture make the sound-absorbing board perform well in a humid environment, can effectively prevent mildew and decay, and extend its service life. DETAILED DESCRIPTION

[0036] The specific embodiments listed in the present invention are only examples of the present invention, and the present invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of the present invention. Therefore, the equal transformations and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturers are not specified for all reagents or instruments, they are all conventional products that can be purchased commercially. In order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details. In other embodiments, the methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the purport of the present invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art. Unless otherwise specified, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0038] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0039] Example 1

[0040] The present application provides a melamine foam sound-absorbing board with good thermal stability, which is prepared by the following method:

[0041] Step S1: Preparation of modified melamine-formaldehyde precondensate: Add 200 kg of water into a reaction kettle and heat to 100° C., then add 600 kg of melamine and 340 kg of paraformaldehyde in a molar ratio of 1:2.5, adjust the pH to weak alkalinity (pH 9.0-9.5) with NaOH solution, and maintain the reaction at 100° C.; after one hour of reaction, add 160 kg of polytetramethylene glycol to continue the reaction to obtain a melamine-formaldehyde precondensate modified by a modifier.

[0042] Step S2: Preparation of foaming liquid: 1300kg of the prepared modified melamine-formaldehyde precondensate, 36kg of mixed surfactant (18kg of sodium alkylbenzene sulfonate and 18kg of alkylphenol polyoxyethylene ether), 221kg of n-pentane as a foaming agent, 33kg of formic acid as a curing agent, 33kg of an auxiliary agent and 0-30 parts by weight of water (the amount of water added is determined according to the viscosity of the kettle material at 25°C before adding water, and the viscosity of the material in the kettle after adding water is usually required to be about 8000cP) are placed in a reaction kettle, and stirred and mixed at a rate of 800r / min to obtain a foaming liquid.

[0043] Step S3: Microwave foaming: sending the foaming liquid to a microwave device for microwave radiation foaming for 60 minutes to obtain a foaming material;

[0044] Step S4: Post-treatment: The obtained foamed material is sent to a drying furnace at 200° C. and dried for 300 min to constant weight, and then pressed into shape by hot pressing and bonding on a machine tool, and then formed by cold air to obtain a sound-absorbing board with a thickness of 40 mm.

[0045] Example 2

[0046] The present application provides a melamine foam sound-absorbing board with good thermal stability, which is prepared by the following method:

[0047] Step S1: Preparation of modified melamine-formaldehyde precondensate: Add 200 kg of water into a reaction kettle and heat to 100° C., then add 600 kg of melamine and 340 kg of polyformaldehyde (based on the molecular weight of formaldehyde) in a molar ratio of 1:2.5, adjust the pH to weak alkalinity (pH 9.0-9.5) with a NaOH solution, and maintain the reaction at 100° C.; after one hour of reaction, add 160 kg of polytetramethylene glycol to continue the reaction to obtain a melamine-formaldehyde precondensate modified by a modifier.

[0048] Step S2: Post-treatment of modified melamine-formaldehyde precondensate: Cool the melamine-formaldehyde precondensate modified by the modifier to about 50°C, add 68 kg of a eutectic mixture of myristic acid and stearic acid (myristic acid and stearic acid are mixed in a mass ratio of 7:3), increase the stirring speed and stir for 40 minutes to obtain a modified melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid.

[0049] Step S3: Preparation of foaming liquid: 1300 kg of the modified melamine-formaldehyde precondensate containing the eutectic mixture of myristic acid and stearic acid after post-treatment in step S2, 36 kg of mixed surfactants (18 kg of sodium alkylbenzene sulfonate and 18 kg of alkylphenol polyoxyethylene ether), 221 kg of n-pentane as a foaming agent, 33 kg of formic acid as a curing agent, 33 kg of an auxiliary agent and 0 to 30 parts by weight of water (the amount of water added is determined according to the viscosity of the kettle material at 25°C before water is added, and the viscosity of the material in the kettle after water is added is usually required to be about 8000 cP) are placed in a reactor, stirred and mixed at a rate of 800 r / min to obtain a foaming liquid.

[0050] Step S4: Microwave foaming: sending the foaming liquid to a microwave device for microwave radiation foaming for 60 minutes to obtain a foaming material;

[0051] Step S5: Post-processing: The obtained foamed material is sent to a drying furnace at 200° C. and dried for 300 min to constant weight, and then pressed into shape by hot pressing and bonding on a machine tool, and then formed by cold air to obtain a sound-absorbing board with a thickness of 40 mm.

[0052] The sound absorption performance of the melamine foam sound-absorbing panels prepared in Example 1 and Example 2 was measured under different test environments. The test environment conditions and test results are shown in Table 1 below:

[0053] Table 1 Sound absorption performance test environmental conditions and test results

[0054]

[0055] According to the test results in Table 1, it can be seen that the sound absorption coefficients of the melamine foam sound-absorbing board at 26°C and 40°C without adding the eutectic mixture of myristic acid and stearic acid in Example 1 can be seen that the sound absorption coefficient of the melamine foam sound-absorbing board without adding the eutectic mixture of myristic acid and stearic acid decreases after the temperature rises, and the sound absorption performance decreases, especially for sound waves above 500Hz, the sound absorption coefficient decreases significantly; it can be seen that the melamine foam sound-absorbing board without adding the eutectic mixture of myristic acid and stearic acid has a significant performance decline under high temperature conditions.

[0056] By comparing the performance of the melamine foam sound-absorbing board with the eutectic mixture of tetradecanoic acid and stearic acid added in Example 1 and Example 2 at 26°C, it can be seen that even at room temperature, the sound absorption coefficient of the sound-absorbing board of Example 2 is greater than that of Example 1, especially for sound waves with a frequency lower than 1000 Hz. It can be seen that the addition of the eutectic mixture of tetradecanoic acid and stearic acid improves the structure of the melamine foam sound-absorbing board itself and improves the sound absorption performance of the melamine foam sound-absorbing board at room temperature.

[0057] By comparing the performance of the melamine foam sound-absorbing board of Example 1 and Example 2 at 40°C, it can be seen that the sound absorption coefficient of the melamine foam sound-absorbing board of Example 2 is higher than that of Example 1, especially for sound waves above 1000 Hz, the melamine foam sound-absorbing board of Example 2 does not produce the significant performance decline phenomenon of Example 1; and can continue to maintain a stable high sound absorption coefficient; it can be seen that the melamine foam sound-absorbing board prepared in the present application has stable high-temperature sound absorption performance.

[0058] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A melamine foam sound-absorbing board with good thermal stability, characterized in that: Includes foaming liquid, and a eutectic mixture of myristic acid and stearic acid.

2. The melamine foam sound-absorbing board with good thermal stability according to claim 1, characterized in that: The myristic acid and stearic acid eutectic mixture is a mixture of myristic acid and stearic acid, and the mass ratio of myristic acid to stearic acid is 6:4 to 7:

3.

3. The melamine foam sound-absorbing board with good thermal stability according to claim 1, characterized in that: The foaming liquid comprises a melamine-formaldehyde precondensate, wherein the melamine-formaldehyde precondensate is mixed with a eutectic mixture of myristic acid and stearic acid in a mass ratio of 20:(1-2) to form a melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid; The foaming liquid specifically includes the following components in parts by weight: 100 parts of melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid, 1.8-3.0 parts of a surfactant, 10-18 parts of a foaming agent, 1.5-2.7 parts of a curing agent, 1.8-2.5 parts of an auxiliary agent and 0-30 parts of water.

4. The melamine foam sound-absorbing board with good thermal stability according to claim 3, characterized in that: The foaming liquid comprises the following components in parts by weight: 100 parts of melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid, 2.5-2.8 parts of a surfactant, 16-17 parts of a foaming agent, 2.5-2.6 parts of a curing agent, 2.3-2.5 parts of an auxiliary agent and 0-30 parts of water.

5. The melamine foam sound-absorbing board with good thermal stability according to claim 4, characterized in that: The melamine-formaldehyde precondensate is a product of the reaction of melamine and paraformaldehyde in water, and the molar ratio of melamine to paraformaldehyde is 1:2-4.

6. The melamine foam sound-absorbing board with good thermal stability according to claim 4, characterized in that: The melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid is modified by a modifier, and the modifier is polytetramethylene ether glycol (PTMEG), tris-(2-hydroxyethyl) isocyanurate (THIEC), nanocellulose crystals (NCC), polyvinyl alcohol (PVA) or diethylene glycol ether.

7. The melamine foam sound-absorbing board with good thermal stability according to claim 3, characterized in that: The surfactant is a mixture of anionic surfactant and nonionic surfactant.

8. The melamine foam sound-absorbing board with good thermal stability according to claim 3, characterized in that: The foaming agent is a physical foaming agent with a boiling point of 0 to 80°C.

9. A method for preparing a melamine foam sound-absorbing board with good thermal stability, characterized in that: The steps include: Step S1: Preparation of modified melamine-formaldehyde precondensate: reacting melamine, paraformaldehyde and water in a reactor; adding a modifier after the reaction to obtain a modified melamine-formaldehyde precondensate; Step S2: post-treatment of the modified melamine-formaldehyde precondensate: adding 5%-10% by mass of a eutectic mixture of myristic acid and stearic acid to the cooled modified melamine-formaldehyde precondensate and stirring evenly to obtain a modified melamine-formaldehyde precondensate containing a eutectic mixture of myristic acid and stearic acid; Step S3: preparing a foaming liquid: placing the modified melamine-formaldehyde precondensate containing the eutectic mixture of myristic acid and stearic acid prepared in step S2, a surfactant, a foaming agent, a curing agent, an auxiliary agent and water in a reaction kettle and stirring and mixing to obtain a foaming liquid; Step S4: Microwave foaming: sending the foaming liquid to a microwave device for foaming using microwave radiation to obtain a foamed material; Step S5: post-processing: drying the obtained foamed material in an oven to constant weight, pressing and molding on a machine tool, and cutting and polishing the molded sound-absorbing board according to requirements to obtain the melamine foam sound-absorbing board with good thermal stability of the present application.

10. The method for preparing a melamine foam sound-absorbing board with good thermal stability according to claim 9, characterized in that: In the step S2, the temperature of the foaming liquid is maintained at 45°C-50°C during stirring.

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