Flame-retardant modified soundproof cotton and preparation method thereof

Abstract

To solve the problems in the prior art, the application provides a preparation method of a flame-retardant modified sound insulation cotton, comprising the following steps: S1, treating polyester material into a sound insulation cotton semi-finished product through melt-blowing technology; S2, performing flame-retardant treatment on the sound insulation cotton semi-finished product to obtain flame-retardant sound insulation cotton; S3, wrapping the flame-retardant sound insulation cotton in non-woven fabric to obtain a sound insulation cotton pre-product; and S4, stamping the sound insulation cotton pre-product into a design-required shape contour to obtain the flame-retardant modified sound insulation cotton; wherein the flame-retardant treatment comprises: treating a flame retardant into flame-retardant foam; and performing defoaming treatment after the flame-retardant foam is applied on the surface of the sound insulation cotton, so that the front surface and the back surface of the sound insulation cotton semi-finished product are symmetrically coated with a first flame-retardant layer, a second flame-retardant layer and a third flame-retardant layer from inside to outside. The application can realize flame-retardant treatment on fluffy PET sound insulation cotton, and obviously improves the flame-retardant performance of the PET sound insulation cotton on the basis of maintaining the fluffy sound insulation characteristics.

Description

Technical Field

[0001] This invention relates to the field of sound insulation cotton preparation technology, and in particular to a flame-retardant modified sound insulation cotton and its preparation method. Background Technology

[0002] With social progress and people's increasing need for privacy, independent space, and noise isolation, soundproofing products are being used more and more widely, including soundproofing cotton, soundproofing felt, soundproofing panels, soundproof doors and windows, and soundproof glass. They are used in fields such as construction engineering, aerospace, and shipbuilding, and can also be used in public places for living and entertainment.

[0003] Because sound insulation cotton can convert noise vibration energy into the kinetic energy of the fine denier fibers inside the cotton and then convert it into heat energy, thus achieving the function of sound absorption and noise reduction, it is widely used in the automotive manufacturing industry to isolate the impact of engine, car vibration, external noise, etc. on the occupants inside the car and improve the driving and riding comfort of the passengers.

[0004] Polyethylene terephthalate (PET) is a commonly used material for preparing sound insulation cotton in automobiles. However, PET itself is a flammable material, while vehicle safety requirements dictate that sound insulation cotton should be flame-retardant. Therefore, PET needs to be modified to be flame-retardant.

[0005] Existing PET flame retardant modification technologies mainly have the following problems:

[0006] 1. Flame retardants can be blended with PET to form flame retardant PET materials. However, the addition of existing flame retardants generally leads to a decrease in the spinnability of PET. Therefore, it is very difficult to prepare PET fibers or fabrics from flame retardant PET and further prepare PET sound insulation cotton. The process requirements are high and it is not suitable for conventional production enterprises.

[0007] 2. Flame-retardant PET fabrics are obtained by modifying finished PET fabrics to produce flame-retardant fabrics. While this method avoids the spinnability problem, PET molecules themselves have unevenly distributed active functional groups, resulting in generally weak bonding between the flame retardant and the PET fabric fibers. Furthermore, PET sound insulation requires the PET fibers or fabric strips to be in a loose state. This means that when the PET fabric is loosened later, the flame retardant is easily detached, affecting its flame-retardant performance. Additionally, the continuous absorption of vibration during the use of sound insulation also easily leads to the detachment of the flame retardant, further impacting its flame-retardant performance.

[0008] 3. Direct surface treatment of fluffed PET fibers or fabric strips. However, existing surface treatment methods generally require the flame retardant solution to be impregnated into the PET fabric strip through padding. However, the pressure padding treatment of fluffed PET fabric strips will reduce the fluffiness of PET fabric, affecting the sound insulation effect, and the problem of the adhesion between flame retardant and PET fiber has not been fundamentally improved. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides a flame-retardant modified sound insulation cotton, the preparation method of which includes the following steps:

[0010] S1. Polyester material is processed into sound insulation cotton semi-finished product through meltblown technology.

[0011] S2. The semi-finished sound insulation cotton is subjected to flame retardant treatment to obtain flame retardant sound insulation cotton.

[0012] S3. Wrap the flame-retardant sound-absorbing cotton inside a non-woven fabric to obtain a pre-finished sound insulation cotton product.

[0013] S4. The pre-finished sound-absorbing cotton is stamped into the required shape to obtain the flame-retardant modified sound insulation cotton. Step S2's flame-retardant treatment includes:

[0014] S2.1 Montmorillonite, piperazine pyrophosphate, polymeric monomer, and inorganic flame retardant are added to an aqueous solvent to obtain flame retardant finishing liquid A.

[0015] S2.2 Keep the flame retardant finishing liquid A in a circulating and stirring state, and adjust the ambient pressure to negative pressure.

[0016] S2.3 Add component B, which is a compound of initiator and sodium dodecyl sulfonate, to flame retardant finishing liquid A, and heat to 55-60℃.

[0017] S2.4 When the flame retardant finishing liquid A and component B react to form a viscous liquid, stop heating and slowly repressurize under low-speed stirring until the pressure returns to normal to obtain flame retardant treatment liquid C.

[0018] S2.5 The flame retardant treatment liquid C is delivered to a high-speed mixer. The high-speed mixer mixes the flame retardant treatment liquid C with air to obtain flame retardant foam D.

[0019] S2.6 Apply flame-retardant foam D evenly to the surface of the sound insulation cotton semi-finished product according to the preset thickness to obtain foam-treated sound insulation cotton.

[0020] S2.7 After a period of time, the foam-treated sound insulation cotton is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure by applying a microwave field.

[0021] S2.8 symmetrically coats the front and back of the sound insulation cotton semi-finished product with a first flame-retardant layer, a second flame-retardant layer, and a third flame-retardant layer from the inside out to obtain the flame-retardant sound insulation cotton.

[0022] Furthermore, the inorganic flame retardant corresponding to the first flame retardant layer is nano-titanium dioxide. The polymer monomer corresponding to the first flame retardant layer is acrylic acid.

[0023] Furthermore, in the flame-retardant finishing liquid A, based on 100 parts by mass of the aqueous solvent, it includes: 5-10 parts montmorillonite, 15-30 parts piperazine pyrophosphate, 30-60 parts acrylic acid, and 1-5 parts nano titanium dioxide. In the flame-retardant finishing liquid A, based on 100 parts by mass of the aqueous solvent, component B includes: 3-5 parts sodium dodecyl sulfonate and 0.1-0.5 parts initiator.

[0024] Furthermore, the inorganic flame retardants corresponding to the second flame retardant layer are nano-magnesium hydroxide and nano-aluminum hydroxide. The polymer monomer corresponding to the second flame retardant layer is acrylamide.

[0025] Furthermore, in the flame-retardant finishing liquid A, based on 100 parts by mass of the aqueous solvent, it includes: 3-8 parts montmorillonite, 25-35 parts piperazine pyrophosphate, 30-40 parts acrylamide, 10-15 parts nano magnesium hydroxide, and 10-15 parts nano aluminum hydroxide. In the flame-retardant finishing liquid A, based on 100 parts by mass of the aqueous solvent, component B includes: 5-7 parts sodium dodecyl sulfonate and 0.5-1.0 parts initiator.

[0026] Furthermore, the inorganic flame retardant corresponding to the third flame retardant layer is melamine. The polymer monomer corresponding to the third flame retardant layer is acrylamide.

[0027] Furthermore, in the flame-retardant finishing liquid A, based on 100 parts by mass of the aqueous solvent, it includes: 1-3 parts montmorillonite, 10-15 parts piperazine pyrophosphate, 30-40 parts acrylamide, and 20-25 parts melamine. In the flame-retardant finishing liquid A, based on 100 parts by mass of the aqueous solvent, component B includes: 5-7 parts sodium dodecyl sulfonate and 0.1-0.3 parts initiator.

[0028] Furthermore, the preset thickness of the first flame-retardant layer coated with flame-retardant foam D is 4±0.1cm.

[0029] The preset thickness of the second flame-retardant layer coated with flame-retardant foam D is 2±0.1cm.

[0030] The preset thickness of the third flame-retardant layer coated with flame-retardant foam D is 4±0.1cm.

[0031] Furthermore, the third flame-retardant layer is externally coated with a water-resistant layer, which is a copolymer of acrylamide and vinyltrimethoxysilane.

[0032] Furthermore, the method for preparing the water-resistant layer includes:

[0033] First, by mass, 100 parts anhydrous ethanol, 50 parts water, 20-30 parts acrylamide, 10-20 parts vinyltrimethoxysilane, 0.5-0.8 parts azobisisobutyronitrile, and 10-12 parts sodium dodecyl sulfonate are combined to form reaction solution E.

[0034] Then, under negative pressure, stir slowly at low speed for 5-10 minutes, heat to 60-65℃, and maintain negative pressure and low-speed stirring. After 10-15 minutes, heat to 70-75℃, and maintain negative pressure and low-speed stirring until the system becomes a viscous liquid. Stop heating, and slowly repressurize under low-speed stirring until atmospheric pressure is restored to obtain mixture F.

[0035] Next, the mixture F is sent to a high-speed mixer, where it is mixed with air to obtain waterproof foam G.

[0036] Then, waterproof foam G is evenly applied to the outside of flame-retardant sound insulation cotton, with a coating thickness of 3±0.1cm, to obtain waterproof pre-product H.

[0037] Finally, the waterproof pre-product H is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure with an external microwave field to obtain waterproof, flame-retardant, and sound-insulating cotton.

[0038] This invention has at least one of the following beneficial effects:

[0039] 1. This invention can achieve flame retardant treatment of fluffy PET sound insulation cotton, and significantly improve the flame retardant performance of PET sound insulation cotton while maintaining its fluffy sound insulation properties.

[0040] 2. The flame-retardant system of this invention does not significantly alter the sound insulation performance of PET sound insulation cotton after modification.

[0041] 3. This invention provides a waterproof treatment for flame-retardant PET sound insulation cotton, which effectively improves its waterproof performance, avoids the impact of water absorption on the adhesion of the flame retardant agent, and has minimal impact on the flame-retardant performance of the PET sound insulation cotton. Attached Figure Description

[0042] Figure 1 The diagram shown is a structural schematic of the flame-retardant modified PET sound insulation cotton of the present invention.

[0043] Figure 2 The figure shows the TG test results curves of the blank sample and the sample of Example 1 of this invention;

[0044] Figure 3 The figure shows the HRR results of the cone measurement test for the blank sample and the sample of Example 1 of this invention. Detailed Implementation

[0045] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0046] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0047] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0048] The flame-retardant modified sound insulation cotton of the present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementation methods can be combined with each other.

[0049] This invention provides an exemplary flame-retardant modified sound insulation cotton, which is prepared through the following steps:

[0050] S1. Polyester material is processed into sound insulation cotton semi-finished product through meltblown technology.

[0051] S2. The semi-finished sound insulation cotton is subjected to flame retardant treatment to obtain flame retardant sound insulation cotton.

[0052] S3. Wrap the flame-retardant sound-absorbing cotton inside a non-woven fabric to obtain a pre-finished sound insulation cotton product.

[0053] S4. The pre-finished sound-absorbing cotton is stamped into the required shape to obtain the flame-retardant modified sound insulation cotton. Step S2's flame-retardant treatment includes:

[0054] S2.1 Montmorillonite, piperazine pyrophosphate, polymeric monomer, and inorganic flame retardant are added to an aqueous solvent to obtain flame retardant finishing liquid A.

[0055] S2.2 Keep the flame retardant finishing liquid A in a circulating and stirring state, and adjust the ambient pressure to negative pressure.

[0056] S2.3 Add component B, which is a compound of initiator and sodium dodecyl sulfonate, to flame retardant finishing liquid A, and heat to 55-60℃.

[0057] S2.4 When the flame retardant finishing liquid A and component B react to form a viscous liquid, stop heating and slowly repressurize under low-speed stirring until the pressure returns to normal to obtain flame retardant treatment liquid C.

[0058] S2.5 The flame retardant treatment liquid C is delivered to a high-speed mixer. The high-speed mixer mixes the flame retardant treatment liquid C with air to obtain flame retardant foam D.

[0059] S2.6 Apply flame-retardant foam D evenly to the surface of the sound insulation cotton semi-finished product according to the preset thickness to obtain foam-treated sound insulation cotton.

[0060] S2.7 After a period of time, the foam-treated sound insulation cotton is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure by applying a microwave field.

[0061] S2.8 symmetrically coats the front and back of the sound insulation cotton semi-finished product with a first flame-retardant layer, a second flame-retardant layer, and a third flame-retardant layer from the inside out to obtain the flame-retardant sound insulation cotton.

[0062] Compared to existing technologies, such as Figure 1 As shown, this invention first prepares a fluffy sound-insulating cotton semi-finished product 1 from finished PET meltblown fabric. Then, a flame retardant is mixed with acrylic acid or acrylamide to form a gel. The flame retardant is then firmly attached to the surface of the PET fibers of the sound-insulating cotton semi-finished product 1 by encapsulating it with the gel, forming a first flame retardant layer 2, a second flame retardant layer 3, and a third flame retardant layer 4. Simultaneously, this invention adds sodium dodecyl sulfonate to stir the flame retardant gel into a foam state using a high-speed mixer. The flame retardant gel is then coated onto the surface of the PET fabric by coating the foam. Since a high-speed mixer is needed during foam formation, the distribution of the flame retardant in the foam is relatively uniform. Furthermore, the coating thickness can be controlled by adjusting the foam thickness (either through spraying during the foam application process or by using a scraper of a certain height, such as 4cm, for smoothing). Therefore, the amount of flame retardant adhering to the PET fabric surface is uniform and controllable. On the other hand, when the present invention performs surface treatment on PET fabric, there is no need to perform rolling mill treatment, so the fluffy PET fabric will not be rolled into a compact state, and the sound insulation effect of PET sound insulation cotton will not be significantly changed.

[0063] Furthermore, existing surface treatment technologies rely primarily on van der Waals forces to adhere the flame retardant treatment liquid to the PET fabric fibers before drying. Therefore, between the time the PET fabric leaves the flame retardant-impregnated device and the drying device, the flame retardant treatment liquid continuously drips due to its own weight and mechanical vibration. This affects the production environment and causes uncontrollable increases in the deviation of the flame retardant adhesion amount, impacting the flame retardant stability of the PET fabric. For example, some fabrics or areas may have sufficient flame retardant adhesion and meet the flame retardant requirements, while other fabrics or areas may have significant flame retardant detachment, resulting in substandard flame retardant performance. This leads to different combustion results for the same batch of fabrics or even the same fabric itself, due to different ignition points, making the flame retardant effect uncontrollable. In contrast, the foam of this invention has a very low self-weight and a large specific surface area. Therefore, the adhesion of the flame retardant foam to the PET fabric is much stronger than that of existing flame retardant finishing liquids. Consequently, it is difficult for the flame retardant foam to detach from the PET fabric between application and drying, resulting in a significantly lower deviation in the flame retardant adhesion amount compared to existing technologies, thus significantly improving flame retardant stability.

[0064] Furthermore, the flame retardant foam of this invention contains monomers that can form gels. Therefore, many solvent-insoluble flame retardant particles or molecules can be encapsulated / adhered to the gel molecules, and the gel applies external force to stably adhere to the PET fiber surface of the PET fabric. This allows for the mixing of various flame retardants with different solubilities, or the use of amounts exceeding the solubility of the flame retardant in the solvent, while still ensuring that the insoluble portion of the flame retardant remains stably adhered to the PET fiber surface. In contrast, existing technologies often require mixing and compounding flame retardants with the same solubility; otherwise, it is impossible to process the flame retardant into a homogeneous flame retardant finishing solution, making it difficult to apply solvent-insoluble flame retardants to the surface of PET fabrics, especially the inner fiber surface, through flame retardant finishing solution surface treatment.

[0065] Furthermore, due to the gel structure of the foam of this invention, the foam has a stronger adsorption capacity on the surface of PET fabric. In addition to van der Waals forces, the foam molecules also exhibit hydrogen bonding between themselves, making it difficult for the foam to slip or detach during the transfer of the PET fabric. This allows for more flexible production line design, enabling the transfer of flame-retardant foam-treated PET fabric along the conveyor belt to involve both ascending and descending strokes. Conventional non-gel foams, on the other hand, can typically only be moved horizontally, and the transfer process cannot be too long. Otherwise, during ascending or descending transport, or during prolonged horizontal movement, foam slippage or lateral displacement is likely to occur, leading to uncontrollable changes in the distribution of flame-retardant foam on the PET fabric surface, or even the detachment of flame-retardant foam, ultimately affecting the flame-retardant stability of the resulting PET fabric.

[0066] This invention provides an exemplary first flame-retardant layer, wherein the inorganic flame retardant corresponding to the first flame-retardant layer is nano-titanium dioxide. The polymer monomer corresponding to the first flame-retardant layer is acrylic acid.

[0067] The present invention provides an exemplary flame retardant finishing liquid A for the first flame retardant layer, which comprises, based on 100 parts by mass of water solvent, 5-10 parts of montmorillonite, 15-30 parts of piperazine pyrophosphate, 30-60 parts of acrylic acid, and 1-5 parts of nano titanium dioxide.

[0068] The present invention provides a component B of a first flame retardant layer, which, based on 100 parts by mass of the aqueous solvent in the flame retardant finishing liquid A of the first flame retardant layer, comprises: 3-5 parts of sodium dodecyl sulfonate and 0.1-0.5 parts of initiator.

[0069] This invention provides an exemplary second flame-retardant layer, wherein the inorganic flame retardant corresponding to the second flame-retardant layer is nano-magnesium hydroxide and nano-aluminum hydroxide. The polymeric monomer corresponding to the second flame-retardant layer is acrylamide.

[0070] The present invention provides an exemplary flame retardant finishing liquid A for a second flame retardant layer, comprising, based on 100 parts by weight of water solvent: 3-8 parts montmorillonite, 25-35 parts piperazine pyrophosphate, 30-40 parts acrylamide, 10-15 parts nano magnesium hydroxide, and 10-15 parts nano aluminum hydroxide.

[0071] The present invention provides an exemplary component B of a second flame retardant layer, wherein, based on 100 parts by mass of the water solvent in the flame retardant finishing liquid A of the second flame retardant layer, component B comprises: 5-7 parts of sodium dodecyl sulfonate and 0.5-1.0 parts of initiator.

[0072] This invention provides an exemplary third flame-retardant layer, wherein the inorganic flame retardant corresponding to the third flame-retardant layer is melamine, and the polymeric monomer corresponding to the third flame-retardant layer is acrylamide.

[0073] The present invention provides an exemplary flame retardant finishing liquid A for a third flame retardant layer, comprising, based on 100 parts by weight of water solvent: 1-3 parts montmorillonite, 10-15 parts piperazine pyrophosphate, 30-40 parts acrylamide, and 20-25 parts melamine.

[0074] The present invention provides an exemplary component B of the third flame retardant layer, which, based on 100 parts by mass of the aqueous solvent in the flame retardant finishing liquid A of the third flame retardant layer, comprises: 5-7 parts of sodium dodecyl sulfonate and 0.1-0.3 parts of initiator.

[0075] First, the combustion of PET and most polymers is primarily an oxidation reaction of molecular chains. That is, under the initiation of oxygen free radicals, long molecular chains decompose into short molecular chains or small molecules, which are further oxidized into gaseous molecules such as carbon monoxide, carbon dioxide, and water, which then volatilize. The main purpose of flame retardant treatment for polymers is to block the process of polymer chain oxidation and breakage.

[0076] After research, the applicant found that the flame-retardant layer provided in this invention consists of three layers composed of different flame retardants and gel polymers, and the flame-retardant mechanisms of the three layers are different:

[0077] The outermost third flame-retardant layer mainly relies on the large amount of non-flammable small molecule gas generated by the thermal decomposition of melamine and acrylamide hydrogel for flame retardancy. The large amount of instantaneously generated non-flammable small molecule gas rapidly dilutes the oxygen content in the environment at the hot spot, reducing the total amount of oxygen free radicals in the environment at the hot spot, thereby rapidly stopping the oxidation chain breaking reaction of PET molecular chains. During the process, piperazine pyrophosphate and montmorillonite can promote the formation of part of the expanded carbon layer, initially blocking oxygen free radicals from penetrating into the interior of the PET fabric. Overall, it significantly improves the self-extinguishing property of PET fabric.

[0078] The second flame-retardant layer in the middle layer involves the thermal decomposition of polyacrylamide, magnesium hydroxide, and aluminum hydroxide during heating, generating a large number of non-flammable small molecules, such as nitrogen dioxide, nitrogen, and water molecules. On the one hand, the evaporation of water molecules can remove a large amount of heat; on the other hand, the large number of non-flammable small molecules dilutes the total amount of oxygen around the hot spot, thereby reducing the content of oxygen free radicals. At the same time, when montmorillonite and piperazine pyrophosphate are heated, they promote the formation of a relatively stable expanding heat-insulating carbon layer between polyacrylamide and PET molecular chains, further hindering the inward penetration of heat and oxygen free radicals, and preventing more PET main molecular chains from participating in the oxidation chain-splitting reaction. During this process, the aluminum oxide and magnesium oxide generated from the decomposition of magnesium hydroxide and aluminum hydroxide participate in the carbon layer formation process, improving the quality and stability of the carbon layer.

[0079] The innermost flame-retardant layer, when heated, is mainly composed of montmorillonite and piperazine pyrophosphate, which promote the formation of a stable, expandable, heat-insulating carbon layer between polyacrylic acid and PET molecular chains. The addition of titanium dioxide significantly improves the quality, heat insulation, and stability of the carbon layer. The formation of a large amount of heat-insulating and stable expandable carbon layer can effectively block the infiltration of heat, oxygen free radicals, and combustible small molecules, preventing more PET main molecular chains from participating in the oxidation reaction. On the other hand, it can also play a certain structural support role, so that the igniter is supported and isolated by the expandable carbon layer at a relatively far position from the main body of the PET fabric, reducing the possibility of the igniter further contacting the inner layer of the PET fabric.

[0080] The three-layer flame-retardant design of this invention creates a synergistic effect among the three layers, significantly improving the flame-retardant performance of PET sound insulation cotton by releasing non-flammable small molecule gases, forming an insulating carbon layer, and carrying away heat.

[0081] Furthermore, through comparative research, the applicant discovered that sodium dodecyl sulfonate, as the foaming agent, not only provides a good foaming effect, but also, although sodium dodecyl sulfonate itself is flammable, in the flame retardant system of this patent, sodium dodecyl sulfonate has a good promoting effect on the formation of the carbon layer. Therefore, it has an unexpected synergistic effect on the flame retardant performance of the flame retardant system of this invention, which is manifested in a certain improvement in the quality of residual char and a certain reduction in the vertical burning damage length.

[0082] This invention provides an exemplary method for preparing a first flame-retardant layer, a second flame-retardant layer, and a third flame-retardant layer, comprising:

[0083] The preset thickness of the first flame-retardant layer coated with flame-retardant foam D is 4±0.1cm.

[0084] The preset thickness of the second flame-retardant layer coated with flame-retardant foam D is 2±0.1cm.

[0085] The preset thickness of the third flame-retardant layer coated with flame-retardant foam D is 4±0.1cm.

[0086] By controlling the coating thickness, the flame-retardant effect of the PET fabric modified by this invention can be optimized.

[0087] The present invention exemplarily coats a water-resistant layer on the outside of a third flame-retardant layer, the water-resistant layer being a copolymer of acrylamide and vinyltrimethoxysilane.

[0088] This invention provides an exemplary method for preparing a water-resistant layer, comprising:

[0089] First, by mass, 100 parts anhydrous ethanol, 50 parts water, 20-30 parts acrylamide, 10-20 parts vinyltrimethoxysilane, 0.5-0.8 parts azobisisobutyronitrile, and 10-12 parts sodium dodecyl sulfonate are combined to form reaction solution E.

[0090] Then, under negative pressure, stir slowly at low speed for 5-10 minutes, heat to 60-65℃, and maintain negative pressure and low-speed stirring. After 10-15 minutes, heat to 70-75℃, and maintain negative pressure and low-speed stirring until the system becomes a viscous liquid. Stop heating, and slowly repressurize under low-speed stirring until atmospheric pressure is restored to obtain mixture F.

[0091] Next, the mixture F is sent to a high-speed mixer, where it is mixed with air to obtain waterproof foam G.

[0092] Then, waterproof foam G is evenly applied to the outside of flame-retardant sound insulation cotton, with a total coating thickness of 3±0.1cm, to obtain waterproof pre-product H.

[0093] Finally, the waterproof pre-product H is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure with an external microwave field to obtain waterproof, flame-retardant, and sound-insulating cotton.

[0094] Because this invention requires the use of gel molecules to stabilize undissolved flame retardant particles or molecules, and the gel is directly exposed to the external environment, it will absorb moisture and swell when the humidity is high or there is standing water, leading to gel rupture. This releases or causes the flame retardant encapsulated or adhered within the gel to detach, affecting its flame retardant performance. Conversely, in low-humidity environments, the gel will gradually dehydrate and solidify, affecting the flexibility of the PET sound insulation cotton and thus its sound insulation performance.

[0095] like Figure 1 As shown, spraying a waterproof layer 5 onto the outside of the third flame-retardant layer 4 can effectively avoid the above-mentioned problems, preventing the exchange of moisture in the gel within the flame-retardant layer with the external environment, thereby effectively reducing changes in the gelation structure caused by changes in the external environment. However, existing waterproof layers have poor flame-retardant properties and are flammable, which affects the flame-retardant properties of PET fabrics. Furthermore, waterproof layers are generally rigid, which significantly affects the flexibility of PET fabrics, thus obviously reducing the sound insulation effect.

[0096] Through research, the applicant has developed a method using an acrylamide and vinyltrimethoxysilane copolymer gel, as described in this invention, to coat the flame-retardant layer with a waterproof gel. The vinyltrimethoxysilane in this waterproof gel provides excellent water resistance, significantly increasing the contact angle between the copolymer surface and water molecules. Furthermore, the gel-like state formed by acrylamide exhibits good compatibility and adhesion to the flame-retardant layer, while also providing some flame-retardant properties and giving the copolymer good flexibility, effectively overcoming the problems existing in prior art waterproofing treatments.

[0097] In addition, the applicant unexpectedly discovered that vinyltrimethoxysilane, which is originally flammable, did not significantly reduce the flame retardant properties of the flame-retardant modified PET sound insulation cotton of the present invention when added to the flame retardant system of the present invention. It can achieve a similar flame retardant effect to the flame-retardant modified PET sound insulation cotton of the present invention that has not undergone waterproof modification.

[0098] To more clearly illustrate the technical structure and effects of this patent, the following description, in conjunction with specific embodiments, comparative examples, and specific experimental data, will further explain this patent.

[0099] Fabric weight gain test:

[0100] W = (M2 - M1) / M1 * 100%; where: M1 is the mass of the PET fabric before treatment, and M2 is the mass of the PET fabric after treatment.

[0101] Flame retardant performance test:

[0102] 1. Oxygen Index: Tested according to GB / T 5454-1997 "Test for Burning Performance of Textiles - Oxygen Index Method", unit of measurement: %.

[0103] 2. Vertical burning: Tested according to GB / T 5454-1997 "Vertical Method for Testing the Burning Performance of Textiles".

[0104] 3. Cone calorimetry: Tested according to ISO 5660-2002 "Tests on reaction to fire", and the heat release rate curve was recorded.

[0105] 4. TG analysis: Thermogravimetric analysis was performed using a thermogravimetric analyzer in an air environment with a heating rate of 10℃ / min.

[0106] Waterproof performance test:

[0107] Immerse the PET fabric in water for 1 hour and observe the changes in the fabric before and after immersion. Place the PET fabric in a vacuum drying oven and dry it at a low temperature of 40°C for 1 hour, and observe the changes in the fabric before and after drying. Test the main flame retardant properties of the fabric before immersion treatment and after drying treatment.

[0108] Sound insulation performance test: The sound insulation performance is tested using an impedance tube.

[0109] Example 1

[0110] A flame-retardant modified sound-insulating cotton is prepared by the following method:

[0111] S1. Polyester material is processed into sound insulation cotton semi-finished product through meltblown technology.

[0112] S2. The semi-finished sound insulation cotton is subjected to flame retardant treatment to obtain flame retardant sound insulation cotton.

[0113] S3. Wrap the flame-retardant sound-absorbing cotton inside a non-woven fabric to obtain a pre-finished sound insulation cotton product.

[0114] S4. The pre-finished sound-absorbing cotton is stamped into the required shape to obtain the flame-retardant modified sound-insulating cotton. Wherein:

[0115] The flame retardant treatment in step S2 includes:

[0116] S2.1 Montmorillonite, piperazine pyrophosphate, polymeric monomer, and inorganic flame retardant are added to an aqueous solvent to obtain flame retardant finishing liquid A.

[0117] S2.2 Keep the flame retardant finishing liquid A in a circulating and stirring state, and adjust the ambient pressure to negative pressure.

[0118] S2.3 Add component B, which is a compound of initiator and sodium dodecyl sulfonate, to flame retardant finishing liquid A, and heat to 60°C.

[0119] S2.4 When the flame retardant finishing liquid A and component B react to form a viscous liquid, stop heating and slowly repressurize under low-speed stirring until the pressure returns to normal to obtain flame retardant treatment liquid C.

[0120] S2.5 The flame retardant treatment liquid C is delivered to a high-speed mixer. The high-speed mixer mixes the flame retardant treatment liquid C with air to obtain flame retardant foam D.

[0121] S2.6 Apply flame-retardant foam D evenly to the surface of the sound insulation cotton semi-finished product according to the preset thickness to obtain foam-treated sound insulation cotton.

[0122] S2.7 After a period of time, the foam-treated sound insulation cotton is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure by applying a microwave field.

[0123] S2.8 symmetrically coats the front and back of the sound insulation cotton semi-finished product with a first flame-retardant layer, a second flame-retardant layer, and a third flame-retardant layer from the inside out to obtain the flame-retardant sound insulation cotton.

[0124] The inorganic flame retardant corresponding to the first flame retardant layer is nano-titanium dioxide. The polymer monomer corresponding to the first flame retardant layer is acrylic acid. The flame retardant finishing liquid A of the first flame retardant layer, based on 100 parts by mass of the water solvent, includes: 8 parts montmorillonite, 20 parts piperazine pyrophosphate, 40 parts acrylic acid, and 3 parts nano-titanium dioxide. Component B of the first flame retardant layer, based on 100 parts by mass of the water solvent in the flame retardant finishing liquid A of the first flame retardant layer, includes: 4 parts sodium dodecyl sulfonate and 0.3 parts initiator.

[0125] The preset thickness of the first flame-retardant layer coated with flame-retardant foam D is 4±0.1cm.

[0126] The inorganic flame retardants corresponding to the second flame retardant layer are nano-magnesium hydroxide and nano-aluminum hydroxide. The polymer monomer corresponding to the second flame retardant layer is acrylamide. The flame retardant finishing liquid A of the second flame retardant layer, based on 100 parts by mass of the water solvent, includes: 6 parts montmorillonite, 30 parts piperazine pyrophosphate, 35 parts acrylamide, 13 parts nano-magnesium hydroxide, and 12 parts nano-aluminum hydroxide. Component B of the second flame retardant layer, based on 100 parts by mass of the water solvent in the flame retardant finishing liquid A of the second flame retardant layer, includes: 6 parts sodium dodecyl sulfonate and 0.8 parts initiator.

[0127] The preset thickness of the second flame-retardant layer coated with flame-retardant foam D is 2±0.1cm.

[0128] The inorganic flame retardant for the third flame retardant layer is melamine. The polymer monomer for the third flame retardant layer is acrylamide. The flame retardant finishing liquid A for the third flame retardant layer, based on 100 parts by mass of the water solvent, includes: 2 parts montmorillonite, 12 parts piperazine pyrophosphate, 35 parts acrylamide, and 23 parts melamine. Component B for the third flame retardant layer, based on 100 parts by mass of the water solvent in the flame retardant finishing liquid A, includes: 6 parts sodium dodecyl sulfonate and 0.2 parts initiator.

[0129] The preset thickness of the third flame-retardant layer, coated with flame-retardant foam D, is 4±0.1cm.

[0130] Example 2

[0131] Based on Example 1, a water-resistant layer is coated on the outside of the third flame-retardant layer. The water-resistant layer is a copolymer of acrylamide and vinyltrimethoxysilane. The method for preparing the water-resistant layer includes:

[0132] First, by mass, 100 parts anhydrous ethanol, 50 parts water, 25 parts acrylamide, 15 parts vinyltrimethoxysilane, 0.7 parts azobisisobutyronitrile, and 11 parts sodium dodecyl sulfonate are combined to form reaction solution E.

[0133] Then, under negative pressure, the mixture is slowly stirred at low speed for 8 minutes, heated to 65°C, and the negative pressure and low-speed stirring are maintained. After 12 minutes, the mixture is heated to 75°C, and the negative pressure and low-speed stirring are maintained until the system becomes a viscous liquid. Heating is then stopped, and the system is slowly repressurized under low-speed stirring until it returns to normal pressure to obtain mixture F.

[0134] Next, the mixture F is sent to a high-speed mixer, where it is mixed with air to obtain waterproof foam G.

[0135] Then, waterproof foam G is evenly applied to the outside of flame-retardant sound insulation cotton, with a total coating thickness of 3±0.1cm, to obtain waterproof pre-product H.

[0136] Finally, the waterproof pre-product H is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure with an external microwave field to obtain waterproof, flame-retardant, and sound-insulating cotton.

[0137] Comparative Example 1

[0138] The remaining steps are the same as in Example 1, except that the three flame-retardant layers all use the flame-retardant finishing liquid A and component B of the first flame-retardant layer in Example 1, and the flame-retardant foam D is repeatedly applied until the total thickness of the flame-retardant foam D is 10 cm, which is the same as the total thickness of the flame-retardant foam D of the three flame-retardant layers in Example 1.

[0139] Comparative Example 2

[0140] The remaining steps are the same as in Example 1, except that the three flame-retardant layers all use the flame-retardant finishing liquid A and component B of the second flame-retardant layer in Example 1, and the flame-retardant foam D is repeatedly applied until the total thickness of the flame-retardant foam D is 10 cm, which is the same as the total thickness of the flame-retardant foam D of the three flame-retardant layers in Example 1.

[0141] Comparative Example 3

[0142] The remaining steps are the same as in Example 1, except that the three flame-retardant layers all use the flame-retardant finishing liquid A and component B of the third flame-retardant layer in Example 1, and the flame-retardant foam D is repeatedly applied until the total thickness of the flame-retardant foam D is 10 cm, which is the same as the total thickness of the flame-retardant foam D of the three flame-retardant layers in Example 1.

[0143] Comparative Example 4

[0144] The remaining steps are the same as in Example 1, except that the amounts of piperazine pyrophosphate and montmorillonite added in each flame-retardant layer are opposite.

[0145] Comparative Example 5

[0146] The remaining steps are the same as in Example 1, except that in step S2.1, montmorillonite is not added, but instead piperazine pyrophosphate of the same mass as montmorillonite is added.

[0147] Comparative Example 6

[0148] The remaining steps are the same as in Example 1, except that piperazine pyrophosphate is not added in step S2.1, but is replaced with montmorillonite of the same mass as piperazine pyrophosphate.

[0149] Comparative Example 7

[0150] The remaining steps are the same as in Example 1, except that step 2 is performed by padding.

[0151] Comparative Example 8

[0152] The remaining steps are the same as in Example 1, except that sodium dodecyl sulfonate is replaced with an equimolar amount of sodium fatty alcohol polyoxyethylene ether sulfate.

[0153] Comparative Example 9

[0154] The remaining steps are the same as in Example 1, except that the polymer monomer of the first flame retardant layer is replaced by acrylamide instead of acrylic acid.

[0155] Comparative Example 10

[0156] The remaining steps are the same as in Example 1, except that the polymer monomers of the second and third flame-retardant layers are replaced with acrylic acid instead of acrylamide.

[0157] Comparative Example 11

[0158] The remaining methods and steps are the same as in Example 1, except that the innermost layer is the third flame-retardant layer in Example 1, the middle layer is the second flame-retardant layer in Example 1, and the outermost layer is the first flame-retardant layer in Example 1.

[0159] Comparative Example 12

[0160] The remaining methods and steps are the same as in Example 1, except that the innermost layer is the second flame-retardant layer in Example 1, the middle layer is the first flame-retardant layer in Example 1, and the outermost layer is the third flame-retardant layer in Example 1.

[0161] Comparative Example 13

[0162] The remaining methods and steps are the same as in Example 1, except that the innermost layer is the second flame-retardant layer in Example 1, the middle layer is the third flame-retardant layer in Example 1, and the outermost layer is the first flame-retardant layer in Example 1.

[0163] Comparative Example 14

[0164] The remaining steps are the same as in Example 1, except that only a water-resistant layer is used to treat the PET fabric, and the three flame-retardant layers are not used to treat the PET fabric.

[0165] Comparative Example 15

[0166] The remaining steps are the same as in Example 1, except that the waterproof layer contains only vinyltrimethoxysilane.

[0167] The results of oxygen index and vertical combustion tests on Examples 1, 2, and Comparative Examples 1 to 15 are shown in Table 1. The blank sample was untreated meltblown PET sound insulation cotton.

[0168] Table 1. Results of oxygen index and vertical combustion tests for blank samples, Example 1, Example 2, and Comparative Examples 1 to 15.

[0169]

[0170] As can be seen from the table above:

[0171] 1. By converting the flame retardant into flame retardant foam and then applying it to PET fabric, the weight gain of the fabric can be stabilized. That is, with the same foam composition, by fixing the coating thickness of the foam, the total amount of modifier adhering to the fabric can be basically controlled. As shown in Table 1, under the flame retardant foam of this application, the weight gain of PET sound insulation cotton is basically 25.2% while the overall coating height is controlled to be about 10cm.

[0172] 2. The flame retardants used in this invention are all available through market sales, eliminating the need for companies to conduct additional flame retardant preparation work, and possessing excellent scalability and industrial production capabilities. This invention, through the specific compounding of existing flame retardants and the design of its specific flame-retardant layer, achieves a superior flame-retardant modification effect on PET fabrics compared to existing technologies that use only one or a combination of flame retardants alone. Furthermore, experiments have shown that using a single uniform flame-retardant layer of this invention, changing the order of the three flame-retardant layers, or altering the selection of gel monomers in the three flame-retardant layers all lead to varying degrees of decrease in the flame-retardant performance of the modified fabric. This is especially true when using only the third flame-retardant layer, where the flame-retardant performance drops to the point of dripping. In other words, only within the flame-retardant composition system defined by this invention can the synergistic flame-retardant effect of this invention be achieved, resulting in a superior flame-retardant modification effect on PET fabrics.

[0173] 3. The combined use of montmorillonite and piperazine pyrophosphate in flame retardants has a synergistic effect. Compared with the use of montmorillonite or piperazine pyrophosphate alone, or the substitution of the amount of montmorillonite and piperazine pyrophosphate, the combined use of montmorillonite and piperazine pyrophosphate in a specific ratio in this invention can significantly enhance the flame retardant properties of PET fabrics.

[0174] 4. Compared with other surfactants of the same type, sodium dodecyl sulfonate has an additional effect on the flame retardant system of this application, which improves the flame retardant performance.

[0175] 5. Under the flame-retardant system of this invention, the waterproof modification method of this invention for flame-retardant modified PET fabrics does not significantly reduce the flame-retardant properties of the flame-retardant modified PET fabrics; the resulting PET fabrics still possess good flame-retardant properties. However, when the waterproof modification method of this invention is used alone to treat PET fabrics, their flame-retardant properties show a significant decrease, not only in the oxygen index but also in complete burning within a shorter time. That is, under the flame-retardant system of this invention, a certain synergistic enhancing effect can be achieved with the reagents in the waterproof modification method of this invention, effectively offsetting the flame-retardant degradation effect caused by the waterproof modification reagents.

[0176] 6. In the flame-retardant system of this invention, using only vinyltrimethoxysilane for waterproofing does not cause a significant decrease in flame-retardant performance. However, vinyltrimethoxysilane is known to be flammable. For example, in Comparative Example 14, even when copolymerized with the flame retardant acrylamide, the flame-retardant performance of the modified PET still decreases. Therefore, it can be considered that in the flame-retardant system of this invention, vinyltrimethoxysilane and the flame-retardant system of this invention have a synergistic effect, effectively increasing the flame-retardant performance of the flame-retardant system of this invention, thus offsetting the decrease in flame-retardant performance that vinyltrimethoxysilane itself should cause.

[0177] To further demonstrate the beneficial effects of the modifier system of this application, the applicant conducted thermogravimetric analysis and cone calorimetry on the blank sample and the sample obtained in Example 1. The test results are as follows: Figure 2 and Figure 3 As shown.

[0178] like Figure 2 As shown, unmodified PET fabric has poor carbonization properties, with a residual char mass of approximately 10%. This means that the main molecular chain of PET easily decomposes into small molecule gases. On the one hand, it cannot form an insulating carbon layer, thus failing to effectively prevent the penetration of oxygen free radicals and heat. On the other hand, the generated small molecule gases may promote the combustion reaction, making the PET fabric itself flammable. This is evident in the flame retardant test, where the oxygen index of the blank PET sample was only 18.2. This means that PET fabric in environments with oxygen content exceeding 18.2% can sustain the combustion reaction. Therefore, in a vertical combustion test in an air environment, the PET blank sample was completely destroyed. After flame retardant modification according to this invention, as shown... Figure 2 As shown in the curve of Example 1, the char formation of the modified PET fabric was significantly improved, and the char residue rate increased to about 35%. Combined with the oxygen index and the performance in vertical combustion, it can be determined that the flame retardant of the present invention can promote the formation of an inflatable heat-insulating carbon layer with good thermal stability in the main chain of PET fabric, which can effectively isolate the heat-contacting surface from the rest of the fabric surface, thereby achieving effective flame retardancy of PET fabric.

[0179] In addition, the initial thermal decomposition temperature T of the modified PET fabric 5％ and the main chain thermal decomposition temperature T 50％ All parameters decreased. The decrease in initial thermal decomposition temperature was mainly due to the thermal decomposition of the flame retardant in the modified PET fabric at a certain temperature, which began to form small molecule gases. The decrease in main chain thermal decomposition temperature mainly came from the flame retardant promoting the degradation of the PET molecular main chain to form a heat-insulating carbon layer. The increase in final char content means that under the action of the flame retardant system of this invention, the PET fabric can generate a heat-insulating carbon layer with good thermal stability, which can effectively isolate heat and the internal and external transfer of small molecules, thus playing a good role in improving flame retardant performance.

[0180] like Figure 3 As shown, the heat release rate of unmodified PET fabric is highly concentrated, and the PHRR can reach 420 kW / m. 2 Around 100°C, and after the flame-retardant modification of the present invention, the heat release rate of PET fabric is relatively slow, with a PHRR of 418.23 kW / m² for unmodified PET fabric. 2 It decreased to 173.59 kW / m² after modification. 2The decrease reached 58.49%. It can be seen that the PET fabric modified by the flame retardant system of this invention has a smoother heat transfer after being heated, and the heat release peak is significantly reduced, which is beneficial to improving the self-extinguishing property of the fabric in the actual environment, and it exhibits self-extinguishing upon removal of the flame in vertical combustion.

[0181] Sound insulation performance is the main focus of PET sound insulation cotton. Therefore, in order to verify the effect of flame retardant modification on the sound insulation effect of PET fabric, the applicant conducted sound insulation effect tests on blank samples, samples of Example 1, Example 2, and Comparative Example 7. The test results are shown in Table 2.

[0182] Table 2. Test results of sound insulation effect of blank sample, Example 1, Example 2, and Comparative Example 7.

[0183]

[0184] As can be seen, although the sound insulation effect of PET sound insulation cotton decreases after modification with the flame-retardant system of this invention, the decrease is not severe and does not affect the performance of the modified fabric as a sound insulation material. After waterproof modification, although the sound insulation effect decreases further, the largest decrease occurs in the high-frequency sound wave range. However, the environmental noise during automobile operation is mainly concentrated in the mid-to-low frequency range. In the mid-to-low frequency range, the PET fabric modified with the waterproof system of this invention still has good sound insulation performance and meets the design requirements.

[0185] However, while traditional padding modification significantly improves the flame retardant properties of PET fabrics, it also noticeably increases their stiffness, significantly reduces their fluffiness and flexibility, and severely compromises their sound insulation performance. The possible reasons are: 1. The padding process results in a very high weight gain, leading to a large amount of flame retardant and gel molecules adhering to the fiber surface and between fibers. This reduces the independent slippage ability of the fibers, meaning a decrease in the independent movement between PET fibers and their ability to absorb sound wave vibrations, thus significantly reducing sound insulation performance. 2. The high-pressure compression process of the rolling mill transforms the originally fluffy PET sound insulation cotton into a dense PET fabric mass, further reducing the independent slippage ability between PET fiber chains, thus further contributing to the significant decrease in sound insulation performance.

[0186] Furthermore, if the waterproof layer is entirely made of vinyltrimethoxysilane, the polymer of vinyltrimethoxysilane is relatively hard, which significantly reduces the flexibility of the PET sound insulation cotton, severely affecting its sound insulation performance. However, by using the copolymer of acrylamide and vinyltrimethoxysilane of this invention, the waterproof layer becomes a waterproof gel, ensuring the flexibility of the PET sound insulation cotton. Therefore, although the sound insulation performance of the modified sound insulation cotton is slightly reduced, it still meets the usage requirements.

[0187] To verify the effect of waterproof modification on the performance of PET fabrics, the applicant conducted waterproof performance tests on the samples from Examples 1 and 2, and the results are shown in Table 3.

[0188] Table 3. Waterproof performance test results for Examples 1 and 2.

[0189]

[0190] As shown in the table, when unmodified flame-retardant PET fabrics are soaked in water, the gel molecules continuously absorb water molecules, resulting in gel swelling. When the gel absorbs enough water molecules, the spacing between the gel molecular chains becomes too large, and a large number of hydrogen bonds break, thus destroying the gel structure. In the tests, this manifests as a noticeable swelling and poorly viscous colloid on the surface of the modified fabric after soaking. Insoluble substances are clearly visible in the soaking water, indicating that the flame retardant, originally encapsulated and adhered to by the gel, is released into the soaking water due to the swelling and rupture of the gel. Finally, the fabric weight gain after drying is significantly reduced, indicating that a large number of gel molecules and flame retardant have detached from the fabric surface. Because the release of flame retardant during the swelling process is uncontrollable, the flame-retardant performance of the flame-retardant modified PET fabrics after soaking also shows an unstable decline. Table 3 shows a set of test results with relative averages, in which most samples showed molten droplets in the vertical burning test.

[0191] The flame-retardant modified PET fabric, modified by this invention for waterproofing, exhibits significantly improved waterproofing performance with minimal weight gain after immersion. This is because the waterproof layer effectively prevents the exchange of moisture between the inside and outside of the gel molecules. On one hand, it effectively prevents water molecules from escaping from the original gel, thus preventing the gel layer from solidifying and affecting the fabric's flexibility. On the other hand, the waterproof layer significantly inhibits the water absorption capacity of the fabric's gel layer, effectively preventing the gel layer from swelling due to water absorption. Therefore, during testing, even after immersion for 1 hour, the flame-retardant modified PET fabric did not show significant weight gain, indicating that the gel layer did not exhibit any obvious swelling problem. The flame-retardant properties after drying did not change significantly compared to before the immersion treatment, meaning that the immersion treatment did not alter the flame-retardant properties of the flame-retardant modified PET fabric.

[0192] It is evident that while unmodified PET fabric possesses excellent flame-retardant properties, its waterproofing ability is poor. Therefore, it can be used as sound insulation material within layers that already possess waterproofing capabilities. Modified flame-retardant PET fabric, on the other hand, exhibits excellent waterproof and flame-retardant properties, making it suitable for areas requiring waterproofing during daily use, such as sound insulation linings and floor mats in vehicles.

[0193] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A flame-retardant modified sound-insulating cotton, the preparation method of which includes the following steps: S1. Polyester material is processed into semi-finished sound insulation cotton using meltblown technology; S2. The semi-finished sound insulation cotton is subjected to flame retardant treatment to obtain flame retardant sound insulation cotton; S3. Wrap the flame-retardant sound insulation cotton in non-woven fabric to obtain a pre-finished sound insulation cotton product; S4. The pre-finished sound insulation cotton is stamped into the required design outline to obtain the flame-retardant modified sound insulation cotton; characterized in that, The flame retardant treatment in step S2 includes: S2.1 Montmorillonite, piperazine pyrophosphate, polymeric monomers, and other flame retardants are added to an aqueous solvent to obtain flame retardant finishing liquid A; S2.2 Keep the flame retardant finishing liquid A in a circulating and stirring state, and adjust the ambient pressure to negative pressure; S2.3 Add component B, which is a compound of initiator and sodium dodecyl sulfonate, to flame retardant finishing liquid A, and heat to 55-60℃; S2.4 When the flame retardant finishing liquid A and component B react until the system becomes a viscous liquid, stop heating and slowly repressurize under low-speed stirring until the pressure is restored to normal to obtain flame retardant treatment liquid C; S2.5 The flame retardant treatment liquid C is delivered to a high-speed mixer. The high-speed mixer mixes the flame retardant treatment liquid C with air to obtain flame retardant foam D. S2.6 Apply flame-retardant foam D evenly to the surface of the sound insulation cotton semi-finished product according to the preset thickness to obtain foam-treated sound insulation cotton; S2.7 After a period of time, the foam-treated sound insulation cotton is transported to a vacuum drying equipment for vacuum defoaming and heated by an external microwave field under negative pressure. S2.8 The sound insulation cotton semi-finished product is symmetrically coated with a first flame retardant layer, a second flame retardant layer and a third flame retardant layer from the inside out on the front and back sides to obtain the flame retardant sound insulation cotton; The other flame retardants corresponding to the first flame retardant layer are: nano titanium dioxide; the polymer monomer corresponding to the first flame retardant layer is: acrylic acid; the flame retardant finishing liquid A, based on 100 parts by mass of water solvent, includes: 5-10 parts of montmorillonite, 15-30 parts of piperazine pyrophosphate, 30-60 parts of acrylic acid, and 1-5 parts of nano titanium dioxide. Other flame retardants corresponding to the second flame retardant layer are: nano magnesium hydroxide and nano aluminum hydroxide; the polymer monomer corresponding to the second flame retardant layer is: acrylamide; the flame retardant finishing liquid A, based on 100 parts by mass of water solvent, includes: 3-8 parts montmorillonite, 25-35 parts piperazine pyrophosphate, 30-40 parts acrylamide, 10-15 parts nano magnesium hydroxide, and 10-15 parts nano aluminum hydroxide. The other flame retardants corresponding to the third flame retardant layer are: melamine; the polymer monomer corresponding to the third flame retardant layer is: acrylamide; the flame retardant finishing liquid A, based on 100 parts by mass of water solvent, includes: 1-3 parts montmorillonite, 10-15 parts piperazine pyrophosphate, 30-40 parts acrylamide, and 20-25 parts melamine.

2. The flame-retardant modified sound insulation cotton according to claim 1, characterized in that, In the flame retardant finishing liquid A of the first flame retardant layer, based on 100 parts by mass of the water solvent, component B includes: 3-5 parts of sodium dodecyl sulfonate and 0.1-0.5 parts of initiator.

3. The flame-retardant modified sound insulation cotton according to claim 1, characterized in that, In the flame retardant finishing liquid A of the second flame retardant layer, based on 100 parts by mass of the water solvent, component B includes: 5-7 parts of sodium dodecyl sulfonate and 0.5-1.0 parts of initiator.

4. The flame-retardant modified sound-insulating cotton according to claim 1, characterized in that, In the flame-retardant finishing liquid A of the third flame-retardant layer, based on 100 parts by mass of the water solvent, component B includes: 5-7 parts of sodium dodecyl sulfonate and 0.1-0.3 parts of initiator.

5. The flame-retardant modified sound-insulating cotton according to claim 1, characterized in that, The preset thickness of the first flame-retardant layer coated with flame-retardant foam D is 4±0.1cm; The preset thickness of the second flame-retardant layer coated with flame-retardant foam D is 2±0.1cm; The preset thickness of the third flame-retardant layer coated with flame-retardant foam D is 4±0.1cm.

6. The flame-retardant modified sound insulation cotton according to claim 1, characterized in that, The third flame-retardant layer is externally coated with a water-resistant layer, which is a copolymer of acrylamide and vinyltrimethoxysilane.

7. The flame-retardant modified sound-insulating cotton according to claim 6, characterized in that, The method for preparing the water-resistant layer includes: First, by mass, 100 parts anhydrous ethanol, 50 parts water, 20-30 parts acrylamide, 10-20 parts vinyltrimethoxysilane, 0.5-0.8 parts azobisisobutyronitrile, and 10-12 parts sodium dodecyl sulfonate are combined to form reaction solution E. Then, under negative pressure, stir slowly at low speed for 5-10 minutes, heat to 60-65℃, and maintain negative pressure and low speed stirring; after 10-15 minutes, heat to 70-75℃, and maintain negative pressure and low speed stirring until the system becomes a viscous liquid. Then stop heating, slowly repressurize under low speed stirring, and obtain the mixture F after restoring normal pressure. Next, the mixture F is fed to a high-speed mixer, where it is mixed with air to obtain waterproof foam G. Then, the waterproof foam G is evenly applied to the outside of the flame-retardant sound insulation cotton, with a coating thickness of 3±0.1cm, to obtain the waterproof pre-product H; Finally, the waterproof pre-product H is transported to a vacuum drying equipment for vacuum defoaming, and then heated and reacted under negative pressure with an external microwave field to obtain waterproof, flame-retardant, and sound-insulating cotton.

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