Flame-retardant epoxy resin composite diatomite sound insulation cotton and preparation method thereof

Abstract

The invention relates to the technical field of sound insulation materials, in particular to flame-retardant epoxy resin composite diatomite sound insulation cotton and a preparation method thereof. The flame-retardant epoxy resin composite diatomite sound insulation cotton is prepared from epoxy resin, diatomite, a composite flame retardant, a coupling agent, a curing agent, a diluent, a foaming agent and a charring agent. The composite flame retardant at least comprises ammonium polyphosphate and melamine; the coupling agent is a silane coupling agent or a titanate coupling agent; the curing agent is methyl tetrahydrophthalic anhydride; the diluent is n-butyl glycidyl ether; the foaming agent is azodicarbonamide; the charring agent is pentaerythritol. By optimizing the diatomite modification process and combining physical dispersion and chemical modification means, the compatibility of the diatomite and the epoxy resin is greatly improved, the pain point of filler agglomeration in the traditional process is thoroughly solved, the porous sound insulation potential of the diatomite is fully released, and the sound absorption and sound insulation performance of the material is qualitatively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sound insulation materials, in particular to a flame-retardant epoxy resin composite diatomite sound insulation cotton and a preparation method thereof. BACKGROUND

[0002] With the continuous improvement of sound insulation and safety protection requirements in the fields of construction, transportation, industry and the like, the market demand for flame-retardant sound insulation materials is expanding. Epoxy resin-based foam materials have become one of the mainstream choices in this field due to their good mechanical properties and convenient processing, but there are still many technical shortcomings in the actual application of existing products. Traditional epoxy resin sound insulation materials mostly rely on a single matrix or simple filler composite, and the sound insulation effect is limited, which is difficult to meet the stringent requirements of high-end scenarios on acoustic performance. Some products attempt to introduce diatomite as a sound insulation filler, but due to the difference between the surface polarity of diatomite and epoxy resin, the compatibility between the two is poor, and agglomeration easily occurs, which not only fails to fully utilize the porous sound insulation properties of diatomite, but also damages the internal structural integrity of the material, resulting in a decrease in mechanical properties.

[0003] In terms of flame-retardant performance, existing technologies generally use a single flame retardant or a simple binary composite flame retardant system, which has low flame-retardant efficiency and poor smoke suppression effect, and is prone to produce a large amount of smoke during combustion, and often accompanied by dripping phenomenon, which has serious safety hazards. At the same time, the selection of coupling agents is relatively single, and there is a lack of adaptability design for the composite system, which further exacerbates the problems of uneven distribution of fillers and insufficient interfacial bonding force. In addition, the raw material ratio of existing products lacks scientific demonstration, and the process parameters are not optimized, but are simply superimposed in various technical links, resulting in a clear antagonistic effect between sound insulation, flame retardation and mechanical properties, making it difficult to achieve balanced improvement of comprehensive performance and unable to adapt to the diversified needs in different scenarios. SUMMARY

[0004] The primary object of the present application is to provide a flame-retardant epoxy resin composite diatomite sound insulation cotton and a preparation method thereof.

[0005] A further object of the present application is to provide a flame-retardant epoxy resin composite diatomite sound insulation cotton, which is composed of the following raw materials: epoxy resin, diatomite, composite flame retardant, coupling agent, curing agent, diluent, foaming agent, and carbon-forming agent. The composite flame retardant contains at least ammonium polyphosphate and melamine. The coupling agent is a silane coupling agent or a titanate coupling agent. The curing agent is methyl tetrahydrophthalic anhydride. The diluent is n-butyl glycidyl ether. The foaming agent is azodicarbonamide. The carbon-forming agent is pentaerythritol.

[0006] Preferably, the composite flame retardant further contains aluminum hypophosphite, and the mass ratio of ammonium polyphosphate, melamine and aluminum hypophosphite is 3-4:2-3:1.

[0007] Preferably, the weight parts of each raw material are: epoxy resin 40-55 parts, diatomite 25-40 parts, composite flame retardant 20-30 parts, coupling agent 0.8-2.5 parts, curing agent 12-16 parts, diluent 3-8 parts, foaming agent 2-5 parts, char-forming agent 2-5 parts.

[0008] Preferably, the silane coupling agent is one or both of KH-550 and KH-560; the titanate coupling agent is NDZ-101.

[0009] Preferably, the epoxy resin is E-51 type epoxy resin.

[0010] A preparation method of the flame-retardant epoxy resin composite diatomite sound insulation cotton comprises the following steps: (1) Raw material pretreatment: dry diatomite, crush and sieve, mix the composite flame retardant and the char-forming agent, and grind; (2) Modification treatment: mix the pretreated diatomite and the coupling agent, and perform surface modification by stirring or ultrasonic-assisted stirring to obtain modified diatomite; (3) Matrix mixing: warm the epoxy resin, add the diluent and stir uniformly, then add the modified diatomite, the composite flame retardant and the char-forming agent, warm and increase the stirring speed to continuously stir to obtain a composite matrix slurry; (4) Foaming forming: after the composite matrix slurry is cooled, the curing agent and the foaming agent are added, stirred quickly, then poured into a mold, and constant-temperature standing and foaming are performed to form a foam blank; (5) Curing and shaping: the foam blank is placed in an oven together with the mold, and after stepwise warming and curing, cooling to room temperature is performed, and the product is demolded.

[0011] Preferably, in step (1), the diatomite drying temperature is 105-110°C, the drying time is 2-3h, and after crushing, the diatomite is sieved through a 200-mesh sieve; the particle size of the composite flame retardant and the char-forming agent after grinding is ≤50μm.

[0012] Preferably, in step (2), when ultrasonic-assisted stirring is performed, the ultrasonic power is 300-350W, the stirring temperature is 60-70°C, and the stirring time is 30-50min; when high-speed stirring is performed, the stirring speed is 800-900r / min, and the stirring time is 30-35min.

[0013] Preferably, in step (3), the initial warming temperature of the epoxy resin is 60-70°C, the temperature is increased to 80-90°C after the filler is added, the stirring speed is 1000-1500r / min, and the stirring time is 60-90min.

[0014] Preferably, in step (4), the composite matrix slurry is cooled to 50-60 DEG C, the mold temperature is kept at 60-70 DEG C, and the standing foaming time is 20-30 min; in step (5), the step-by-step heating and curing is as follows: first heating to 120-130 DEG C and curing for 1.5-2.5 h, and then heating to 150-160 DEG C and curing for 1-2 h.

[0015] Compared with the prior art, the present application has the following advantages: 1. The present application optimizes the diatomite modification process, combines physical dispersion with chemical modification means, greatly improves the compatibility of diatomite and epoxy resin, completely solves the pain point of filler agglomeration in traditional processes, fully releases the porous sound insulation potential of diatomite, and greatly improves the sound absorption and sound insulation performance of the material.

[0016] 2. The present application reasonably matches different types of flame retardants to form a synergistic effect, not only significantly improves the flame retardant efficiency and durability, but also effectively inhibits the generation of smoke during the combustion process, eliminates the dripping phenomenon, realizes more comprehensive safety protection, and solves the problems of single and low efficiency of the existing flame retardant system.

[0017] 3. The present application can adapt to the use requirements of various types of coupling agents, and scientifically defines the raw material ratio range to ensure that the material can maintain stable and excellent performance in different application scenarios, especially can meet the extreme demands of high sound insulation and high flame retardation.

[0018] 4. The present application realizes the synergistic improvement of sound insulation performance, flame retardation performance and mechanical performance through deep synergistic optimization of each process link such as matrix mixing, foaming molding and curing, avoids the sacrifice of other performances caused by single performance optimization, and forms an integrated technical solution.

[0019] 5. The product of the present application has excellent comprehensive performance and wide application scenarios, which can be used not only for ordinary building sound insulation, but also for safety protection in special scenes such as transportation and industry, and has good popularization prospect and market value. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] Embodiment 1: Raw material ratio: epoxy resin E-5150 parts, diatomite 30 parts, composite flame retardant ammonium polyphosphate APP and melamine MCA mass ratio 3 to 120 parts, silane coupling agent KH-550 1 part, curing agent methyl tetrahydrophthalic anhydride 12 parts, diluent n-butyl glycidyl ether 4 parts, foaming agent azodicarbonamide 2 parts, char-forming agent pentaerythritol 3 parts.

[0022] Preparation step: Raw material pretreatment: diatomite was dried in a 105°C oven for 2h to remove moisture, and after cooling to room temperature, it was crushed to pass through a 200 mesh sieve for use; the composite flame retardant and char-forming agent were mixed uniformly and ground to a particle size of ≤50μm for use. Drying treatment can avoid the influence of moisture on the subsequent mixing and foaming effect, and crushing and sieving can ensure uniform filler particles and improve the dispersion effect.

[0023] Modification treatment: the pretreated diatomite was added to a high-speed mixer, the speed was 800r / min, the coupling agent KH-550 was added, and stirring was carried out at room temperature for 30min to complete the modification of the diatomite surface and obtain modified diatomite. This step modifies the diatomite with a silane coupling agent to preliminarily improve the compatibility of the diatomite with the epoxy resin and effectively alleviate the agglomeration problem of diatomite commonly existing in the prior art, laying a foundation for uniform dispersion of subsequent components.

[0024] Matrix mixing: epoxy resin E-51 was added to a stirred tank, the temperature was raised to 60°C, the speed was 500r / min, the diluent was added and stirred for 10min until the system was uniform; then the modified diatomite, composite flame retardant and char-forming agent were added, the temperature was raised to 80°C, the speed was increased to 1000r / min, and stirring was continued for 60min to obtain a uniform composite matrix slurry. This step uses a step-by-step mixing method, first reduces the viscosity of the epoxy resin by diluent, and then adds various fillers to ensure uniform dispersion of each component and avoid local agglomeration of the flame retardant and diatomite.

[0025] Foaming and molding: the composite matrix slurry was cooled to 50°C, the curing agent and foaming agent were added, and rapid stirring was carried out for 20min, then the slurry was injected into a mold, the mold temperature was kept at 60°C, and the foam blank was formed by standing for 30min. Controlling the cooling temperature can avoid premature decomposition of the foaming agent caused by high temperature, and standing for foaming can ensure uniform pore size of the foam.

[0026] Curing and shaping: the foam blank was placed in a constant temperature oven together with the mold, the temperature was raised to 120°C and cured for 2h, then the temperature was raised to 150°C and kept for 1h, and after completion, it was cooled to room temperature and demolded to obtain the flame-retardant epoxy resin composite diatomite sound insulation cotton. Step-by-step temperature rising and curing can ensure that the matrix is fully crosslinked and cured, improving the mechanical properties and dimensional stability of the product.

[0027] Example 2: Raw material ratio: epoxy resin E-5150 parts, diatomite 30 parts, composite flame retardant APP and MCA mass ratio 3:120 parts, silane coupling agent KH-560 1.5 parts, curing agent methyl tetrahydrophthalic anhydride 12 parts, diluent n-butyl glycidyl ether 4 parts, foaming agent azodicarbonamide 2 parts, char-forming agent pentaerythritol 3 parts.

[0028] Preparation step: Raw material pretreatment: the same as example 1, after drying the diatomite, sieve through 200 mesh screen, mix and grind the composite flame retardant and the char-forming agent to particle size ≤50 μm.

[0029] Modification treatment: add the pretreated diatomite into deionized water to make a suspension with mass fraction of 20%, ultrasonic dispersion for 20 min (power 300 W, frequency 40 kHz); then add silane coupling agent KH-560, heat to 60℃, high-speed stirring at 1000 r / min for 40 min, while continuously ultrasonic auxiliary; after the reaction is completed, filter, dry the filter cake in an oven at 110℃ for 3 h, crush after cooling and sieve through 200 mesh screen to obtain high dispersibility modified diatomite. Ultrasonic auxiliary can effectively destroy the diatomite agglomerates, increase the specific surface area and improve the coupling agent grafting efficiency; and KH-560 contains epoxy groups, which has better compatibility with epoxy resin, compared with the modification method of example 1, can significantly improve the interfacial bonding force between diatomite and the matrix.

[0030] Matrix mixing: the same as example 1, heat the epoxy resin to 60℃, add the diluent, then add the modified diatomite and other fillers, stir at 80℃ and 1000 r / min for 60 min. Relying on the optimized modified diatomite, the filler dispersibility is better and the system uniformity is significantly improved.

[0031] Foaming molding: the same as example 1, add the curing agent and foaming agent at 50℃, stir for 20 min, then pour into the mold, keep the mold temperature at 60℃, and stand for 30 min.

[0032] Curing and shaping: the same as example 1, cure at 120℃ for 2 h, then heat to 150℃ and keep for 1 h, and cool and demold after cooling.

[0033] Example 3: Based on the optimized modification process of example 2, the binary composite flame retardant system used in example 2 still has room for improvement in terms of flame retardant efficiency and smoke suppression effect, and there is a slight risk of dripping during combustion. Therefore, this example upgrades the composite flame retardant system by introducing aluminum hypophosphite AP as a synergistic flame retardant, adjusting the component ratio to construct a ternary synergistic flame retardant system, aiming to improve the flame retardant durability, smoke suppression effect and anti-dripping performance, and verify the rationality of the flame retardant dosage range, breaking through the limitation of single flame retardant system and low efficiency in the prior art.

[0034] Raw material ratio: epoxy resin E-51 45 parts, diatomite 35 parts, composite flame retardant APP, MCA and AP in a mass ratio of 4:2:1 25 parts, silane coupling agent KH-560 1.5 parts, curing agent methyl tetrahydrophthalic anhydride 14 parts, diluent n-butyl glycidyl ether 5 parts, foaming agent azodicarbonamide 3 parts, carbon agent pentaerythritol 2 parts.

[0035] Preparation step: Raw material pretreatment: after drying, diatomite is passed through a 200-mesh sieve, and the composite flame retardant APP, MCA, AP and carbon agent are mixed and ground to a particle size of ≤50 μm, ensuring uniform dispersion of the three flame retardants and avoiding excessive or insufficient local flame retardant concentration affecting the flame retardant effect.

[0036] Modification treatment: the same as example 2, using ultrasonic assisted composite modification with KH-560 to prepare modified diatomite. The optimized modification process is continued to ensure the dispersion of the filler and provide a guarantee for the full combination of the flame retardant and the matrix.

[0037] Matrix mixing: epoxy resin E-51 is added to the stirred tank, heated to 65°C, and the diluent is stirred for 10 min; then the modified diatomite, composite flame retardant and carbon agent are added, the temperature is raised to 85°C, the stirring speed is increased to 1200 r / min, and the stirring is continued for 70 min to ensure that the flame retardant and the matrix are fully combined. Compared with example 2, the amount of flame retardant is increased and the components are more complex, so the stirring temperature and speed are moderately increased and the stirring time is extended to adapt to the dispersion needs of high proportion of flame retardant, avoiding the problem of uneven flame retardant performance caused by flame retardant agglomeration.

[0038] Foaming: the composite matrix slurry is cooled to 55°C, the curing agent and foaming agent are added, and the mixture is quickly stirred for 25 min, then poured into a mold with a temperature of 65°C, and left to foam for 25 min to form a foam blank. By adjusting the mold temperature and foaming time, the foaming characteristics of the high flame retardant content system are adapted to ensure uniform foam pore size.

[0039] Curing and shaping: the foam blank is placed in an oven, heated to 125°C for 1.5 h, then heated to 155°C for 1.5 h, cooled and demolded to obtain sound insulation cotton with more excellent flame retardant performance. By adjusting the curing temperature and time, the curing needs of the high flame retardant content system are matched to ensure that the matrix is fully cured and the mechanical properties and flame retardant stability are improved.

[0040] Example 4: Based on the optimized flame-retardant system and modification process of Example 3, both Example 2 and Example 3 use silane coupling agents, while the selection of coupling agents in the prior art is relatively single, and the adaptability of different types of coupling agents to the composite system is not clear. In view of this situation, this example selects titanium ester coupling agent NDZ-101 to replace silane coupling agent, adjusts the dosage range at the same time, verifies the influence of different types of coupling agents on the comprehensive performance of the material, expands the selection protection range of raw materials, and further improves the adaptability of the technical scheme.

[0041] Raw material ratio: 55 parts of epoxy resin E-5155, 25 parts of diatomite, 122 parts of composite flame retardant APP, MCA and AP with a mass ratio of 4:2:1, 0.8 parts of titanium ester coupling agent NDZ-101, 13 parts of curing agent methyl tetrahydrophthalic anhydride, 3 parts of diluent n-butyl glycidyl ether, 2 parts of foaming agent azodicarbonamide, and 3 parts of charring agent pentaerythritol.

[0042] Preparation steps: Raw material pretreatment: the same as Example 3, after drying, the diatomite is sieved through a 200-mesh screen, and the composite flame retardant and the charring agent are mixed and ground to a particle size of ≤50 μm.

[0043] Modification treatment: add the diatomite into a high-speed mixer, heat to 70°C, rotate at 900 r / min, add the titanium ester coupling agent NDZ-101, stir for 35 min to complete the modification; then add a small amount of diluent and continue to stir for 10 min to further improve the compatibility of the modified diatomite and the epoxy resin. There are differences in the reaction characteristics of the titanium ester coupling agent and the silane coupling agent, this step adjusts the modification temperature and stirring time to adapt to the grafting requirements of the titanium ester coupling agent, which can further improve the interfacial bonding strength of the filler and the matrix compared with the silane coupling agent modification, and verifies the adaptability of the coupling agent dosage of 0.8 parts.

[0044] Matrix mixing: the same as Example 3, the epoxy resin is heated to 65°C and then the diluent, modified diatomite, composite flame retardant and charring agent are added, and stirred at 85°C and 1200 r / min for 70 min. Relying on the optimized mixing process of Example 3, the titanium ester coupling agent modified diatomite is fully combined with the flame retardant and the matrix.

[0045] Foaming molding: the same as Example 3, add the curing agent and foaming agent at 55°C, stir for 25 min, then pour into the mold, keep the mold temperature at 65°C, and stand for 25 min.

[0046] Curing and shaping: the same as Example 3, cure at 125°C for 1.5 h, then heat to 155°C for 1.5 h, and cool and demold after cooling.

[0047] Example 5: Raw material ratio: epoxy resin E-5140 parts, diatomite 40 parts, composite flame retardant APP, MCA and AP in a mass ratio of 3:2:130 parts, silane coupling agent KH-560 2.5 parts, curing agent methyl tetrahydrophthalic anhydride 16 parts, diluent n-butyl glycidyl ether 8 parts, foaming agent azodicarbonamide 5 parts, char-forming agent pentaerythritol 5 parts.

[0048] Preparation steps: Raw material pretreatment: diatomite is dried and passed through a 200 mesh sieve, and the composite flame retardant and the char-forming agent are mixed and ground to a particle size of ≤40 μm. A finer particle size is used to adapt to the dispersion needs of high filler content systems and to avoid performance degradation caused by filler agglomeration.

[0049] Modification treatment: The same ultrasonic assisted modification method as in Example 2 is used, with the ultrasonic power adjusted to 350 W, the frequency 40 kHz, the coupling agent dosage increased to 2.5 parts, and the stirring time extended to 50 min, to ensure that the high proportion of diatomite is fully modified and to solve the dispersion problem under high filler content.

[0050] Matrix mixing: Add epoxy resin E-51 to the stirred tank, heat to 70°C, add 8 parts of diluent (the amount is the upper limit of the ratio) to reduce the viscosity of the high filler system, and stir for 15 min; then add modified diatomite, composite flame retardant, and char-forming agent, heat to 90°C, increase the speed to 1500 r / min, and continue stirring for 90 min to ensure uniform dispersion of the system. Compared with the previous examples, this example increases the stirring temperature, speed, and time to adapt to the viscous system with high filler and high flame retardant content, effectively solving the problem of mixing uniformity under the limit ratio.

[0051] Foaming: Cool the composite matrix slurry to 60°C, add curing agent and foaming agent, the curing agent amount is the upper limit of 16 parts to match the curing needs of the low epoxy content system, and the foaming agent amount is the upper limit of 5 parts to ensure the foaming ratio of the high filler system, stir quickly for 30 min, inject into the mold, keep the mold temperature at 70°C, and let stand for 20 min to form a foam blank. By adjusting the foaming temperature, time and mold temperature, the foaming characteristics of the limit ratio system are adapted to ensure uniform foam structure and avoid under-foaming or over-foaming.

[0052] Curing and shaping: Place the foam blank in an oven, heat to 130°C for 2.5 h, then heat to 160°C for 2 h, cool and demold to obtain a product that meets the high sound insulation and high flame retardation requirements. By adjusting the curing process parameters, extending the curing time and increasing the curing temperature, the high proportion of additive system is fully cured to ensure the stability of the mechanical properties and flame retardation properties of the product.

[0053] Comparative Example 1: Raw material ratio: epoxy resin E-5180 parts, composite flame retardant APP and MCA mass ratio 3 to 120 parts, silane coupling agent KH-550 1 part, curing agent methyl tetrahydrophthalic anhydride 12 parts, diluent n-butyl glycidyl ether 4 parts, foaming agent azodicarbonamide 2 parts, carbon agent pentaerythritol 3 parts.

[0054] The present comparative example is a typical scheme of the existing epoxy resin flame-retardant foam material, does not contain diatomite component, corresponds to the flame-retardant sound insulation material without adding diatomite in the prior art, and is used for comparing and verifying the necessity of diatomite as a core sound insulation filler.

[0055] Preparation steps: except that the diatomite pretreatment and modification steps are not needed, the remaining steps are the same as those in Example 1.

[0056] Comparative Example 2: Raw material ratio: epoxy resin E-5150 parts, unmodified diatomite 30 parts, single flame retardant APP 20 parts, silane coupling agent KH-550 1 part, curing agent methyl tetrahydrophthalic anhydride 12 parts, diluent n-butyl glycidyl ether 4 parts, foaming agent azodicarbonamide 2 parts, carbon agent pentaerythritol 3 parts.

[0057] The present comparative example is a simple combination of the existing diatomite modified epoxy resin technology and the single flame retardant technology, does not use the diatomite modification process and the composite flame retardant system of the present application, and is used for comparing and verifying the technical value of the core technical features of the present application.

[0058] Preparation steps: except that the diatomite is not modified and is directly dried and then added, the remaining steps are the same as those in Example 1.

[0059] Comparative Example 3: Raw material ratio: epoxy resin E-5130 parts, diatomite 45 parts, composite flame retardant APP and MCA mass ratio 3 to 135 parts, silane coupling agent KH-550 0.3 parts, curing agent methyl tetrahydrophthalic anhydride 7 parts, diluent n-butyl glycidyl ether 1 part, foaming agent azodicarbonamide 0.5 parts.

[0060] The raw material dosages of the present comparative example all exceed the protection range of the raw material ratio of the present application, and do not contain carbon agent, correspond to the unreasonable scheme of the ratio design in the prior art, and are used for comparing and verifying the scientific nature of the raw material ratio range of the present application.

[0061] Preparation steps: the same as those in Example 1.

[0062] Comparative Example 4: Raw material ratio: the same as that in Example 2. Although the raw material ratio of the present comparative example is consistent with that in Example 2, the existing conventional preparation process is used, the ultrasonic assisted modification is not introduced, and the process parameters deviate from the optimization range of the present application, and are used for comparing and verifying the necessity of the process parameter optimization of the present application.

[0063] Preparation steps: except that the modification treatment is not assisted by ultrasound, only stirring at room temperature for 40 min, and the matrix mixing temperature is 50℃ and the curing temperature is 100℃, the rest of the steps are the same as those in Example 2.

[0064] Comparative Example 5: Raw material ratio: the same as Example 3. The raw material ratio of this comparative example is consistent with that of Example 3, but the simple superposition method of diatomite modification and flame retardant addition in the prior art is used, and the synergy of each process step is not optimized (the modification treatment uses single stirring modification of Example 1, and the matrix mixing uses the process parameters of Example 1). The technical advantages of the integrated optimization scheme of the present application are verified for comparison and illustration that the present application is not a simple superposition of the prior art.

[0065] Preparation steps: the modification treatment is the same as that in Example 1, the matrix mixing is the same as that in Example 1, and the foaming molding and curing are the same as those in Example 3.

[0066] The products prepared in the above Examples 1-5 and Comparative Examples 1-5 are comprehensively tested, and typical performance data of similar products in the prior art (including single epoxy resin flame-retardant foam, unoptimized diatomite composite sound insulation material, and simple combination products in the prior art) are collected as reference. The test items include sound insulation performance (sound absorption coefficient, sound insulation quantity), flame retardant performance (oxygen index OI, vertical burning grade UL94, smoke density grade SDR), and mechanical performance (tensile strength, compressive strength), which comprehensively evaluate the comprehensive performance of the products and provide reliable data support for verifying the advantages of the technical scheme of the present application. All tests are entrusted to a third-party testing institution with qualifications, and the test process strictly follows the corresponding standard specifications, and the test results are true and reliable.

[0067] Test standards and methods: (1) Sound absorption coefficient: tested according to GB / T18696.2-2002 "Acoustics-Determination of sound absorption coefficient by the impedance tube method-Part 2: Transfer function method", test frequency 125-4000Hz, average sound absorption coefficient is taken; Sound insulation quantity: tested according to GB / T19889.3-2005 "Acoustics-Determination of sound absorption coefficient by the impedance tube method-Part 2: Transfer function method", test frequency 100-3150Hz, average sound absorption coefficient is taken; (2) Oxygen index OI: tested according to GB / T2406.2-2009 "Plastics-Determination of the flammability of plastics-Part 2: Burning behaviour in test flames-Method B: 23℃±2℃ test environment"; (3) Vertical burning rating: tested according to UL94-2013 "Standard Test Methods for Flame Retardant Properties of Plastics", the thickness of the test sample is 10 mm, and the burning rating is rated as V-0, V-1, V-2, and no rating; (4) Smoke density rating SDR: tested according to GB / T8323.2-2022 "Plastics - Determination of the Smoke Density - Part 2: Single Compartment Method", the test time is 4 min, and the maximum smoke density rating is taken; (5) Tensile strength: tested according to GB / T1040.1-2006 "Determination of the Tensile Properties of Plastics - Part 1: General Principles", the test speed is 5 mm / min, and the sample is dumbbell-shaped; (6) Compressive strength: tested according to GB / T8813-2022 "Determination of the Compressive Properties of Rigid Foamed Plastics", the test speed is 2 mm / min, and the compressive strength at a compression deformation of 10% is taken.

[0068] The test results are shown in Table 1 below: Table 1:

[0069] The test results are analyzed as follows: The performance of each embodiment shows obvious progressive optimization effect, and the overall performance is excellent. After optimizing the modification method of diatomite in Example 2 based on Example 1, the average sound absorption coefficient is increased by 12.9%, the tensile strength is increased by 25%, and the smoke density rating is reduced by 6.7%. It can be seen that the modification process using ultrasonic assisted and adaptive coupling agent can effectively improve the dispersion of fillers and the interfacial bonding force, and improve the smoke suppression effect, solving the problem of insufficient single room temperature stirring modification.

[0070] In Example 3, based on the optimization of the modification process in Example 2, the aluminum hypophosphite AP is introduced to construct a ternary synergistic flame retardant system, the oxygen index is increased by 10.8%, the smoke density rating is reduced by 16.7%, and the flame retardant without dripping V-0 level is achieved, which significantly improves the flame retardant performance and smoke suppression effect, breaking through the limitation of low efficiency of binary composite flame retardant system. After replacing the titanate coupling agent NDZ-101 in Example 4, the performance remains excellent, the average sound absorption coefficient is 0.67, the oxygen index is 34.1%, and the tensile strength is 3.2 MPa, which verifies the good adaptability of the technical scheme to different types of coupling agents, and expands the raw material selection space.

[0071] In Example 5, the limit value of the raw material ratio protection range is used, the average sound absorption coefficient reaches 0.73, the weighted sound insulation quantity reaches 48 dB, and the oxygen index reaches 38.5%, which are better than the previous examples, indicating that the raw material ratio and process parameters of the present application can well adapt to the extreme demand scenarios of high sound insulation and high flame retardant, and the ratio protection range is scientific and reasonable, and the process adaptability is strong.

[0072] The comprehensive performance of each embodiment of the present application is significantly better than each comparative example. Comparative example 1, as a diatomite-free scheme, has an average sound absorption coefficient and a weighted sound insulation quantity far lower than the embodiments of the present application, being 43.5%-52.1% and 33.3%-41.7% lower, respectively, and a smoke density grade 33.3%-66.7% higher, fully demonstrating the importance of diatomite as a core sound insulation filler, and the present application effectively improves the problem of insufficient sound insulation performance by introducing diatomite and optimizing its dispersibility.

[0073] Comparative example 2 is a simple combination scheme that does not use the core technology of the present application, using unmodified diatomite and a single flame retardant, with an oxygen index of only 27.5%, no clear combustion grade, and a tensile strength of only 2.1 MPa, far inferior to the embodiments of the present application, indicating that the diatomite modification process and the composite flame retardant system of the present application are carefully optimized and designed, and are not simply stacked technologies, and can achieve a breakthrough in performance, solving the problem of performance antagonism.

[0074] Comparative example 3 has a raw material usage exceeding the ratio protection range of the present application and does not contain a charring agent, with a tensile strength and a compressive strength of only 1.8 MPa and 0.8 MPa, far lower than the embodiments of the present application, being 31.0%-38.9% and 44.4%-56.3% lower, respectively, verifying the scientificity and rationality of the raw material ratio range of the present application, and unreasonable ratio design can lead to a decrease in product performance.

[0075] Comparative example 4 uses a conventional process that is not optimized, without ultrasonic auxiliary modification and with process parameters deviating from the optimized range of the present application, and its performance is inferior to that of example 2, with an average sound absorption coefficient 21.4% lower, an oxygen index 6.6% lower, and a tensile strength 28.6% lower, indicating that the process parameter optimization of the present application is of great significance, and conventional processes cannot meet the needs of high dispersibility and multiple performance synergistic improvement.

[0076] Comparative example 5 is a simple stacking scheme without optimized process synergy, and its performance is still inferior to that of example 3, with an average sound absorption coefficient 23.5% lower and a smoke density grade 48.6% higher, further indicating that the technical solution of the present application is an integrated solution formed by deep adaptation and synergistic optimization of each process link, and can achieve a more optimal comprehensive performance level.

[0077] Overall, the present application achieves synergistic improvement in sound insulation, flame retardation, and mechanical performance by optimizing the diatomite modification process, constructing a synergistic flame retardant system, expanding the raw material ratio range and process adaptability, and each technical link cooperates and synergizes, with the product having a significant comprehensive performance advantage, good application value, and good prospects for popularization.

[0078] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details and do not limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to provide the best illustration of the application principles and their practical application, so that those skilled in the art can well understand and utilize the application.

Claims

1. A flame-retardant epoxy resin composite diatomaceous earth sound insulation cotton, characterized in that, It is composed of the following raw materials: epoxy resin, diatomaceous earth, composite flame retardant, coupling agent, curing agent, diluent, foaming agent, and charring agent; the composite flame retardant contains at least ammonium polyphosphate and melamine; the coupling agent is a silane coupling agent or a titanate coupling agent; the curing agent is methyltetrahydrophthalic anhydride; the diluent is n-butyl glycidyl ether; the foaming agent is azodicarbonamide; and the charring agent is pentaerythritol.

2. The flame-retardant epoxy resin composite diatomaceous earth sound insulation cotton according to claim 1, characterized in that, The composite flame retardant also contains aluminum hypophosphite, and the mass ratio of ammonium polyphosphate, melamine and aluminum hypophosphite is 3-4:2-3:

1.

3. The flame-retardant epoxy resin composite diatomaceous earth sound insulation cotton according to claim 1, characterized in that, The weight parts of each raw material are as follows: epoxy resin 40-55 parts, diatomaceous earth 25-40 parts, composite flame retardant 20-30 parts, coupling agent 0.8-2.5 parts, curing agent 12-16 parts, diluent 3-8 parts, foaming agent 2-5 parts, and charring agent 2-5 parts.

4. The flame-retardant epoxy resin composite diatomaceous earth sound insulation cotton according to claim 1, characterized in that, The silane coupling agent is one or both of KH-550 and KH-560; the titanate coupling agent is NDZ-101.

5. The flame-retardant epoxy resin composite diatomaceous earth sound insulation cotton according to claim 1, characterized in that, The epoxy resin is type E-51 epoxy resin.

6. A method for preparing flame-retardant epoxy resin composite diatomaceous earth sound insulation cotton as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Raw material pretreatment: After drying the diatomaceous earth, crush it and sieve it. Mix the composite flame retardant and the charring agent evenly and then grind them. (2) Modification treatment: The pretreated diatomaceous earth is mixed with a coupling agent and surface modified by stirring or ultrasonic-assisted stirring to obtain modified diatomaceous earth; (3) Matrix mixing: After heating the epoxy resin, add the diluent and stir evenly. Then add the modified diatomaceous earth, composite flame retardant and charring agent. Heat and increase the speed to continue stirring to obtain composite matrix slurry. (4) Foaming molding: After cooling the composite matrix slurry, add curing agent and foaming agent, stir quickly and pour into mold, keep at constant temperature to foam, and form foam blank; (5) Curing and shaping: Place the foam blank together with the mold into the oven, heat it step by step to cure it, cool it to room temperature, and demold to obtain the product.

7. The preparation method according to claim 6, characterized in that, In step (1), the diatomaceous earth is dried at a temperature of 105-110℃ for 2-3 hours and then pulverized and passed through a 200-mesh sieve; the composite flame retardant and charring agent are ground to a particle size of ≤50μm.

8. The preparation method according to claim 6, characterized in that, In step (2), when ultrasonic-assisted stirring is performed, the ultrasonic power is 300-350W, the stirring temperature is 60-70℃, and the stirring time is 30-50min; when high-speed stirring is performed, the stirring speed is 800-900r / min, and the stirring time is 30-35min.

9. The preparation method according to claim 6, characterized in that, In step (3), the initial temperature of the epoxy resin is 60-70℃, and after adding the filler, the temperature is raised to 80-90℃. The stirring speed is 1000-1500r / min, and the stirring time is 60-90min.

10. The preparation method according to claim 6, characterized in that, In step (4), the composite matrix slurry is cooled to 50-60℃, the mold temperature is maintained at 60-70℃, and the standing foaming time is 20-30min; in step (5), the step-by-step heating and curing is as follows: first heat to 120-130℃ and cure for 1.5-2.5h, then heat to 150-160℃ and keep warm for 1-2h.

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