A highly conductive halogen-free flame-retardant polyurethane sponge and its preparation method and application

Abstract

This application relates to the field of sponge materials, and particularly to a highly conductive halogen-free flame-retardant polyurethane sponge and its preparation method and application. The highly conductive halogen-free flame-retardant polyurethane sponge, in parts by mass, comprises the following raw materials: 40-50 parts of polyether polyol, 20-30 parts of polypropylene glycol, 5-15 parts of polytetrahydrofuran ether, 50-70 parts of polyisocyanate, 1-4 parts of deionized water, 5-15 parts of modified functional particles, 5-10 parts of flame retardant, 5-10 parts of epoxy block copolymer, 1-2 parts of catalyst, and 5-15 parts of auxiliary agent. The polyurethane sponge prepared in this application can, on the premise of ensuring excellent electrical conductivity and flame retardancy, simultaneously retain good waterproof, mechanical, temperature and aging resistance properties, greatly improving the application performance of the polyurethane sponge, avoiding the loss of properties such as waterproof and mechanical properties caused by the addition of functional fillers, and having very excellent market application prospects.

Description

Technical Field

[0001] This application relates to the field of sponge materials, and particularly to a highly conductive halogen-free flame-retardant polyurethane sponge and its preparation method and application. Background Art

[0002] As a new type of functional material, conductive polyurethane sponge has received extensive attention in recent years. This material combines the softness of polyurethane sponge and the electrical properties of conductive fillers, making it have broad application prospects in the fields of electronic devices, electromagnetic interference (EMI) shielding, electrostatic discharge (ESD) protection, sensor devices, and smart textiles.

[0003] Polyurethane sponge is a porous material formed by the complex chemical reaction of polyisocyanate and polyol. It has excellent compression and rebound performance, sound absorption, heat preservation, and good mechanical strength. However, unmodified polyurethane sponge itself does not have conductivity, which limits its application in the electronics industry. To endow polyurethane sponge with conductivity, a common practice is to add various conductive fillers during the preparation process, such as carbon black, graphite, metal powder, graphene, carbon nanotubes (CNTs), conductive polymers such as polyaniline (PANI), etc. These raw materials form a conductive network in the polyurethane matrix, thus realizing the effective transmission of charge.

[0004] However, in the prior art, there are still some technical problems with polyurethane sponge. For example, the uniform dispersion of conductive raw materials or flame-retardant raw materials in the polyurethane matrix is a major difficulty. The agglomeration of fillers will not only reduce the conductivity and flame retardancy, but may also weaken the mechanical properties of the sponge; and while pursuing high conductivity and flame retardancy, how to maintain the mechanical strength, elasticity, and durability of the sponge becomes a key issue; the functional fillers contained in the sponge often damage the original characteristics of the sponge; the performance stability of conductive polyurethane sponge under different environmental conditions, such as in a relatively humid environment, is also a research focus, especially whether it can maintain its own stability under extreme conditions.

[0005] Therefore, to solve the above problems, this application provides a highly conductive halogen-free flame-retardant polyurethane sponge and its preparation method. The polyurethane sponge prepared in this application can, on the premise of ensuring excellent conductive performance and flame retardant performance, simultaneously retain good waterproof, mechanical, and temperature and aging resistance properties, greatly improving the application performance of polyurethane sponge, avoiding the loss of waterproof, mechanical and other aspects of performance caused by the addition of functional fillers, and having very excellent market application prospects. Summary of the Invention

[0006] To solve the above problems, the first aspect of the present application provides a highly conductive halogen-free flame-retardant polyurethane sponge. By mass, the raw materials include: 40-50 parts of polyether polyol, 20-30 parts of polypropylene glycol, 5-15 parts of polytetrahydrofuran ether, 50-70 parts of polyisocyanate, 1-4 parts of deionized water, 5-15 parts of modified functional particles, 5-10 parts of flame retardant, 5-10 parts of epoxy block copolymer, 1-2 parts of catalyst, and 5-15 parts of auxiliary agent.

[0007] As a preferred solution, the mass ratio of the polyether polyol, polypropylene glycol, polytetrahydrofuran ether and polyisocyanate is (4-4.5):(2-2.5):(1-1.5):(5.5-6.5).

[0008] As a preferred solution, the mass ratio of the polyether polyol, polypropylene glycol, polytetrahydrofuran ether and polyisocyanate is (4.2-4.5):(2.2-2.5):(1-1.2):(5.8-6.4).

[0009] As a preferred solution, the mass ratio of the polyether polyol, modified functional particles and epoxy block copolymer is (4-4.5):(1-1.4):(0.6-1).

[0010] As a preferred solution, the polyether polyol is at least one of polyoxypropylene polyol, polyoxypropylene / ethylene oxide copolymer polyol, glycerol-based polyether polyol, and tetrahydrofuran-oxypropylene copolymer polyol.

[0011] As a preferred solution, the functionality of the polyether polyol is 3.

[0012] As a preferred solution, the weight-average molecular weight of the polyether polyol is 4500-7000 g / mol.

[0013] As a preferred solution, the weight-average molecular weight of the polyether polyol is 5000-6000 g / mol.

[0014] As a preferred solution, the weight-average molecular weight of the polypropylene glycol is 2000-3000 g / mol.

[0015] As a preferred solution, the polytetrahydrofuran ether is polytetrahydrofuran diol.

[0016] As a preferred solution, the weight-average molecular weight of the polytetrahydrofuran ether is 1000-1500 g / mol.

[0017] As a preferred embodiment, the polyisocyanate is at least one of toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, cyclohexane diisocyanate, and benzylidene diisocyanate.

[0018] As a preferred embodiment, the polyisocyanate is 2,4'-diphenylmethane diisocyanate.

[0019] As a preferred embodiment, the method for preparing the modified functional particles comprises the following steps: S1: Mix expandable graphite and titanium dioxide and add them to water. Add calcium petroleum sulfonate and succinic anhydride, heat to 60-70 °C, ultrasonically disperse evenly, and then stir and react at a speed of 60-120 r / min for 2-3 h. Dropwise add 3-aminopropyltriethoxysilane 0.5 h before the reaction to obtain pretreated particles; S2: Mix the pretreated particles and trimellitic acid and add them to a DMF solution, stir evenly and ultrasonically disperse for 10-15 min to obtain a mixed solution. Then, dropwise add a DMF solution containing copper acetate to the mixed solution. The dropping temperature is 50-60 °C, and stirring is carried out at a speed of 200-300 r / min during the dropping process. The dropping time is 1-1.5 h. After the dropping is completed, transfer the reaction to a high-pressure reactor, heat to 120-130 °C, and keep the temperature for reaction for 14-20 h; S3: After the reaction is completed, add triethanolamine, mix and stir for 0.5-1 h, centrifuge and filter the product, wash with methanol, and carry out vacuum drying at 80-90 °C for multiple cycles. After completion, it is obtained.

[0020] As a preferred embodiment, the mass ratio of the expandable graphite, titanium dioxide, calcium petroleum sulfonate, succinic anhydride, and 3-aminopropyltriethoxysilane is (2-3):(0.5-1):(0.4-0.8):(1-1.5):(0.1-0.3).

[0021] As a preferred embodiment, the mass ratio of the expandable graphite, titanium dioxide, calcium petroleum sulfonate, succinic anhydride, and 3-aminopropyltriethoxysilane is (2-2.5):(0.6-0.8):(0.4-0.6):(1.2-1.4):(0.2-0.3).

[0022] As a preferred embodiment, the average particle size of the titanium dioxide is 10-30 nm.

[0023] As a preferred embodiment, the average particle size of the expandable graphite is 4-8 μm.

[0024] As a preferred embodiment, the mass ratio of the pretreated particles, trimellitic acid, copper acetate, and triethanolamine is (3.5-4):(0.4-0.8):(1.2-2):(0.4-0.6).

[0025] In this application, the addition of the above-mentioned modified functional particles can ensure that the polyurethane sponge has excellent electrical conductivity and flame retardancy, while having good waterproof, anti-aging and mechanical properties, effectively solving the problem of performance deficiency in the existing technology. The added modified functional particles can form a composite connection structure of nano-semiconductor particles, framework particle structure and expanded graphite interlayer structure. The existence of this structure can be connected through coordination and hydrogen bonding after surface group modification, while greatly enhancing the connection strength between them, providing a great convenient space for the formation of the electron connection path, thereby greatly increasing the flow path length and flow speed of electrons in the sponge system. Moreover, it can also enhance the connection strength between the expandable graphite and the organic sponge through the connection effect of the groups on the particle surface and the organic sponge, avoiding the migration of conductive particles, so as to ensure that the electrical conductivity and flame retardancy of the expandable graphite do not decrease due to the detachment of the filler during long-term use.

[0026] On the other hand, the added modified functional particles can play a good linear supporting role under external force through their stable composite structure and their connection function with the organic sponge system. Especially during stretching, the connection between the particles and the sponge system greatly improves its strength; and the composite structure of the modified functional particles can form a good rough peak-valley structure on the surface of the organic sponge through its low surface energy and high-roughness surface. This structure and the hydrophobic property of the framework particles can greatly reduce the formation speed of the hydration layer on the surface of the organic sponge, and can produce a local adsorption effect during the contact with water molecules in a short time. Before adsorption saturation, it can greatly increase the penetration resistance of water molecules to the organic sponge, increase the penetration path length, and thus improve the waterproof performance. And its stable composite structure can effectively adsorb active molecules and groups inside the organic sponge system, thereby greatly removing the reactive molecules in the internal system of the sponge, and then avoiding the aging reaction affected by temperature and moisture during long-term use, and thus obtaining excellent anti-aging performance.

[0027] As a preferred solution, the flame retardant is a composition of ammonium polyphosphate and zinc borate.

[0028] As a preferred solution, the mass ratio of ammonium polyphosphate to zinc borate is (4 - 8):(2 - 4).

[0029] As a preferred solution, the mass ratio of ammonium polyphosphate to zinc borate is (6 - 8):(2 - 3).

[0030] As a preferred solution, the epoxy block copolymer is a block copolymer of ethylene oxide and propylene oxide.

[0031] As a preferred embodiment, the epoxy block copolymer is a composition of an epoxy block copolymer with a weight average molecular weight of 1000 - 2000 g / mol and an epoxy block copolymer with a weight average molecular weight of 4000 - 5000 g / mol.

[0032] As a preferred embodiment, the mass ratio of the epoxy block copolymer with a weight average molecular weight of 1000 - 2000 g / mol to the epoxy block copolymer with a weight average molecular weight of 4000 - 5000 g / mol is (1 - 1.5):(3 - 4).

[0033] In this application, through the compounding effect of the above-mentioned epoxy block copolymer and the added polyol raw material, the waterproof, mechanical and aging resistance properties of the polyurethane sponge are greatly improved. The added epoxy block copolymer can preferentially form a double-layer film-wrapped structure composed of different molecular weight phases with the added modified functional particles. The existence of this structure can greatly improve the dispersion and flow effect of the modified functional particles in the polyol system after adding the polyol system, and thus effectively avoid the agglomeration phenomenon of the modified functional particles inside the sponge system during the mixing stage; moreover, the added epoxy block copolymer can improve the spreading effect of the modified functional particles in the sponge reaction system through the guiding effect of its molecular chain, so that the modified functional particles not only have a good adsorption effect with the polyurethane sponge system, but also can play a good embedding effect. On the other hand, different lengths of molecular chains can play a good guiding role for the modified functional particles in the polyol system to different degrees, thereby enhancing the internal three-dimensional network construction strength of the polyurethane sponge system while increasing the exposed area of the modified functional particles on the sponge surface and inside the pores, and further significantly enhancing the flame retardancy, waterproof and aging resistance properties of the polyurethane sponge.

[0034] As a preferred embodiment, the catalyst is at least one of dibutyltin dilaurate, triethylenediamine, triethylene diamine, liquid alcohols, ethylenediamine, triethylamine, trioctylamine.

[0035] As a preferred embodiment, the auxiliary agents at least include an auxiliary foaming agent and a surfactant.

[0036] As a preferred embodiment, the auxiliary foaming agent is any one of cyclopentane, supercritical carbon dioxide, sodium bicarbonate.

[0037] As a preferred embodiment, the surfactant is at least one of lauryl alcohol polyoxyethylene ether, cetearyl alcohol polyoxyethylene ether, sodium dodecylbenzenesulfonate, alkyl glycoside, betaine.

[0038] As a preferred embodiment, the mass ratio of the foaming agent to the surfactant is (0.5 - 2):(6 - 10).

[0039] The second aspect of the present application provides a method for preparing the above-mentioned highly conductive halogen-free flame-retardant polyurethane sponge, including the following specific steps: S1: The modified functional particles and the epoxy block are taken out together after being mixed in a high-speed mixer at 200-300 rpm for 30-40 min, and then they are mixed with polyether polyol, polypropylene glycol, polytetrahydrofuran ether, deionized water, flame retardant, catalyst and auxiliary agent, and stirred at a speed of 60-120 rpm for 20-40 min to be evenly mixed; S2: Add polyisocyanate and stir at 1500-2000 rpm for 3-5 min, place the stirred mixture into a sponge mold, control the mold temperature at 30-35 °C, keep warm for 20-25 h, and after completion, wash and cut to obtain the product.

[0040] The third aspect of the present application provides an application of the above-mentioned highly conductive halogen-free flame-retardant polyurethane sponge in electronic devices, electromagnetic interference shielding, electrostatic discharge protection, sensor devices and smart textiles.

[0041] The beneficial effects of the present application are as follows:

[0042] 1. The highly conductive halogen-free flame-retardant polyurethane sponge provided in the present application can, on the premise of ensuring excellent electrical conductivity and flame retardancy, simultaneously retain good waterproof, mechanical, temperature and aging resistance properties, greatly improving the application performance of the polyurethane sponge, avoiding the loss of properties such as waterproof and mechanical properties caused by the addition of functional fillers, and having a very excellent market application prospect.

[0043] 2. The highly conductive halogen-free flame-retardant polyurethane sponge provided in the present application, the added modified functional particles can form a composite connection structure of nano-semiconductor particles, framework particle structure and expandable graphite interlayer structure. The existence of this structure can be connected through coordination and hydrogen bonds after surface group modification, greatly enhancing the connection strength between them, providing a great convenient space for the formation of the electron connection path, thus greatly increasing the flow path length and flow speed of electrons in the sponge system, and also enhancing the connection strength between the expandable graphite and the organic sponge through the connection of the groups on the particle surface and the organic sponge, avoiding the migration of conductive particles, and ensuring that the electrical conductivity and flame retardancy of the expandable graphite do not decrease due to the detachment of the filler during long-term use.

[0044] 3. A highly conductive halogen-free flame-retardant polyurethane sponge provided in the present application. The added modified functional particles can play a good linear supporting role under external forces through their stable composite structure and their connection function with the organic sponge system. Especially during stretching, the connection between the particles and the sponge system greatly improves its strength. The composite structure of the modified functional particles can form a good rough peak-valley structure on the surface of the organic sponge through its low surface energy and high-roughness surface. The hydrophobic properties of this structure and the framework particles can greatly reduce the formation rate of the hydration layer on the surface of the organic sponge, and can generate a local adsorption effect during the contact process with water molecules in a short time. Before adsorption saturation, it can greatly increase the penetration resistance of water molecules to the organic sponge, increase the penetration path length, and thus improve the waterproof performance.

[0045] 4. A highly conductive halogen-free flame-retardant polyurethane sponge provided in the present application. Through the compounding effect of the epoxy block and the added polyol raw materials, the waterproof, mechanical, and aging resistance properties of the polyurethane sponge are greatly improved. The added epoxy block can preferentially form a double-layer film-wrapping structure composed of different molecular weight phases with the added modified functional particles. The existence of this structure can greatly improve the dispersion and flow effect of the modified functional particles in its system after adding the polyol system, and thus effectively avoid the agglomeration phenomenon of the modified functional particles inside the sponge system during the mixing stage. Moreover, the added epoxy block can improve the laying effect of the modified functional particles in the sponge reaction system through the guiding effect of its molecular chain, so that the modified functional particles not only have a good adsorption effect with the polyurethane sponge system, but also can play a good embedding effect. Detailed implementation mode

[0046] The technical solutions in the above-mentioned invention content of the present application will be further described and demonstrated below in the form of specific implementation examples. And the following examples are only actual examples for explaining and interpreting the content of the technical solutions in the specification, and should not limit the scope of the claims to be protected by the present application. All technical products based on the technical solutions described in the invention content of the present application should be covered within the scope to be protected by the present application.

[0047] In the following examples, unless otherwise specified, the raw materials are commercially available products that can be obtained, or can be prepared by methods well-known to those skilled in the art.

[0048] Example 1

[0049] Example 1 provides a highly conductive halogen-free flame-retardant polyurethane sponge. In parts by mass, the raw materials include: 42.5 parts of polyether polyol, 24.4 parts of polypropylene glycol, 11.5 parts of polytetrahydrofuran ether, 63.5 parts of polyisocyanate, 2.4 parts of deionized water, 12.5 parts of modified functional particles, 8.5 parts of flame retardant, 8.8 parts of epoxy block copolymer, 1.8 parts of catalyst, and 8.2 parts of auxiliary agent.

[0050] The polyether polyol is polyoxypropylene triol with a functionality of 3 and a weight-average molecular weight of 5000 g / mol, purchased from the corresponding molecular weight product sold by Suzhou Senfeida Chemical Co., Ltd.

[0051] The polypropylene glycol has a weight-average molecular weight of 2000 g / mol and is purchased from the corresponding molecular weight product sold by Jiangsu Haian Petrochemical; the polytetrahydrofuran ether is polytetrahydrofuran diol with a weight-average molecular weight of 1100 g / mol and is purchased from the corresponding molecular weight product sold by Shandong Deyitai New Materials Co., Ltd.

[0052] The polyisocyanate is 2,4'-diphenylmethane diisocyanate.

[0053] The preparation method of the modified functional particles includes the following steps. In parts by mass: S1: Mix 2.36 parts of expandable graphite and 0.72 parts of titanium dioxide, add them to 120 parts of deionized water, add 0.45 parts of calcium petroleum sulfonate and 1.28 parts of succinic anhydride, heat to 65°C, disperse evenly by ultrasonic wave, and then stir and react at a speed of 100 r / min for 3 h. Dropwise add 0.28 parts of 3-aminopropyltriethoxysilane in the first 0.5 h before the reaction to obtain pretreated particles; S2: Mix 3.8 parts of pretreated particles and 0.65 parts of trimellitic acid, add them to 80 parts of DMF solution, stir evenly and disperse by ultrasonic wave for 15 min to obtain a mixed solution. Then, dropwise add the DMF solution (a total of 20 parts) containing 1.75 parts of copper acetate to the mixed solution. The dropping temperature is 60°C, and stirring is carried out at a speed of 200 r / min during the dropping process. The dropping time is 1 h. After the dropping is completed, transfer the reaction to a high-pressure reactor, heat to 125°C, and keep the temperature for reaction for 16 h; S3: After the reaction is completed, add 0.58 parts of triethanolamine, mix and stir for 1 h. Centrifuge and filter the product, wash it with methanol, and carry out the vacuum drying cycle at 80°C for 3 times. After completion, the product is obtained.

[0054] The average particle size of titanium dioxide is 25 nm.

[0055] The average particle size of expandable graphite is 8.6 μm, purchased from LingShou County Chengnuo Mineral Products Co., Ltd., and is ground twice.

[0056] The flame retardant is a composition of ammonium polyphosphate and zinc borate, and the mass ratio of ammonium polyphosphate to zinc borate is 6:2.5.

[0057] The epoxy block copolymer is a block copolymer of ethylene oxide and propylene oxide. The epoxy block copolymer is a composition of BASF L42 (weight average molecular weight 1600 g / mol) and BASF L85 (weight average molecular weight 4600 g / mol), and the mass ratio of the two is 1.2:3.5.

[0058] The catalyst is dibutyltin dilaurate.

[0059] The auxiliary agents are a co-blowing agent and a surfactant, and the mass ratio of the two is 1.1:7.1.

[0060] The surfactant is polyoxyethylene lauryl ether, purchased as the MOA-4 product sold by Hai'an Guoyun Chemical Industry.

[0061] The co-blowing agent is cyclopentane.

[0062] In the second aspect of this example, a method for preparing the above-mentioned highly conductive halogen-free flame-retardant polyurethane sponge is provided, including the following specific steps: S1: The modified functional particles and the epoxy block copolymer are mixed in a high-speed mixer at 250 rpm for 40 min and then taken out together. Then, they are mixed with polyether polyol, polypropylene glycol, polytetrahydrofuran ether, deionized water, flame retardant, catalyst, and auxiliary agents, and stirred at 100 rpm for 35 min to mix evenly; S2: Polyisocyanate is added and stirred at 1800 rpm for 4 min. The stirred mixture is placed into a sponge mold, the mold temperature is controlled at 32.5 °C, and it is kept warm for 22 h. After completion, it is washed and cut to obtain the product.

[0063] Example 2

[0064] In the first aspect of Example 2, a highly conductive halogen-free flame-retardant polyurethane sponge is provided. Calculated by mass, the raw materials include: 40 parts of polyether polyol, 25 parts of polypropylene glycol, 10 parts of polytetrahydrofuran ether, 64.5 parts of polyisocyanate, 2.2 parts of deionized water, 10 parts of modified functional particles, 8.5 parts of flame retardant, 6.5 parts of epoxy block copolymer, 1.65 parts of catalyst, and 8.2 parts of auxiliary agents.

[0065] The polyether polyol is polyoxypropylene triol, with a functionality of 3 and a weight average molecular weight of 5000 g / mol, purchased as the corresponding molecular weight product sold by Suzhou Senfeida Chemical Co., Ltd.

[0066] The polypropylene glycol has a weight average molecular weight of 2000 g / mol, purchased as the corresponding molecular weight product sold by Jiangsu Hai'an Petrochemical Industry; the polytetrahydrofuran ether is polytetrahydrofuran diol, with a weight average molecular weight of 1100 g / mol, purchased as the corresponding molecular weight product sold by Shandong Deyitai New Materials Co., Ltd.

[0067] The polyisocyanate is 2,4'-diphenylmethane diisocyanate.

[0068] The preparation method of the modified functional particles comprises the following steps, by mass: S1: Mix 2.36 parts of expandable graphite and 0.72 part of titanium dioxide and add them to 120 parts of deionized water. Add 0.45 part of calcium petroleum sulfonate and 1.28 parts of succinic anhydride, heat to 65°C, ultrasonically disperse evenly, and then stir and react at a speed of 100 r / min for 3 h. Dropwise add 0.28 part of 3-aminopropyltriethoxysilane in the first 0.5 h before the reaction to obtain pretreated particles; S2: Mix 3.8 parts of the pretreated particles and 0.65 part of trimellitic acid and add them to 80 parts of DMF solution, stir evenly and ultrasonically disperse for 15 min to obtain a mixed solution. Then, dropwise add the DMF solution (20 parts in total) containing 1.75 parts of copper acetate to the mixed solution at a dropping temperature of 60°C, with stirring at a speed of 200 r / min during the dropping, and the dropping time is 1 h. After the dropping is completed, transfer the reaction to a high-pressure reactor, heat to 125°C, and keep the temperature for reaction for 16 h; S3: After the reaction is completed, add 0.58 part of triethanolamine, mix and stir for 1 h, centrifuge and filter the product, wash with methanol and carry out vacuum drying at 80°C in a cycle of 3 times. After completion, the product is obtained.

[0069] The average particle size of titanium dioxide is 25 nm.

[0070] The average particle size of expandable graphite is 8.6 μm. It is purchased from Chengnuo Mineral Products Co., Ltd., Lingshou County and is ground twice.

[0071] The flame retardant is a composition of ammonium polyphosphate and zinc borate, and the mass ratio of ammonium polyphosphate to zinc borate is 6:2.5.

[0072] The epoxy block copolymer is a block copolymer of ethylene oxide and propylene oxide. The epoxy block copolymer is a composition of BASF L42 (weight average molecular weight 1600 g / mol) and BASF L85 (weight average molecular weight 4600 g / mol), and the mass ratio of the two is 1.2:3.5.

[0073] The catalyst is dibutyltin dilaurate.

[0074] The auxiliary agent is a combination of an auxiliary foaming agent and a surfactant, and the mass ratio of the two is 1.1:7.1.

[0075] The surfactant is polyoxyethylene lauryl ether, purchased from the MOA-4 product sold by Guoyun Chemical Industry, Haian.

[0076] The auxiliary foaming agent is cyclopentane.

[0077] In the second aspect of this embodiment, a preparation method of the above-mentioned highly conductive halogen-free flame-retardant polyurethane sponge is provided, including the following specific steps: S1: The modified functional particles and the epoxy block are taken out together after being mixed in a high-speed mixer at 250 rpm for 40 min, and then they are mixed with polyether polyol, polypropylene glycol, polytetrahydrofuran ether, deionized water, flame retardant, catalyst and auxiliary agent, and stirred at a speed of 100 rpm for 35 min to be evenly mixed; S2: Add polyisocyanate and stir at a speed of 1800 rpm for 4 min, place the stirred mixture into a sponge mold, control the mold temperature at 32.5 °C, keep warm for 22 h, and after completion, wash and cut to obtain the product.

[0078] Comparative Example 1

[0079] The specific implementation manner of this comparative example is basically the same as that of Example 1, the difference is only that: the polyether polyol is polyoxypropylene glycol, with a functionality of 2 and a weight average molecular weight of 4000 g / mol, purchased from the corresponding molecular weight product sold by Suzhou Senfeida Chemical Co., Ltd.

[0080] Comparative Example 2

[0081] The specific implementation manner of this comparative example is basically the same as that of Example 1, the difference is only that: for the highly conductive halogen-free flame-retardant polyurethane sponge, by mass, the raw materials include: 60.5 parts of polyether polyol, 10.8 parts of polypropylene glycol, 3.5 parts of polytetrahydrofuran ether, 63.5 parts of polyisocyanate, 2.4 parts of deionized water, 12.5 parts of modified functional particles, 8.5 parts of flame retardant, 8.8 parts of epoxy block, 1.8 parts of catalyst, and 8.2 parts of auxiliary agent.

[0082] Comparative Example 3

[0083] The specific implementation manner of this comparative example is basically the same as that of Example 1, the difference is only that: the weight average molecular weight of polypropylene glycol is 4000 g / mol, purchased from the corresponding molecular weight product sold by Hai'an Petrochemical in Jiangsu Province; the polytetrahydrofuran ether is polytetrahydrofuran diol, with a weight average molecular weight of 2000 g / mol, purchased from the corresponding molecular weight product sold by Shandong Deyitai New Materials Co., Ltd.

[0084] Comparative Example 4

[0085] The specific implementation manner of this comparative example is basically the same as that of Example 1, the difference is only that: for the highly conductive halogen-free flame-retardant polyurethane sponge, by mass, the raw materials include: 42.5 parts of polyether polyol, 24.4 parts of polypropylene glycol, 11.5 parts of polytetrahydrofuran ether, 63.5 parts of polyisocyanate, 2.4 parts of deionized water, 5.5 parts of modified functional particles, 8.5 parts of flame retardant, 2.4 parts of epoxy block, 1.8 parts of catalyst, and 8.2 parts of auxiliary agent.

[0086] Comparative Example 5

[0087] The specific implementation manner of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified functional particles includes the following steps, by mass: S1: Mix 4.86 parts of expandable graphite and 0.22 parts of titanium dioxide, add them to 120 parts of deionized water, add 0.25 parts of calcium petroleum sulfonate and 1.18 parts of succinic anhydride, heat to 65°C, ultrasonically disperse evenly, and then stir and react at a speed of 100 r / min for 3 h. 0.22 parts of 3-aminopropyltriethoxysilane is added dropwise 0.5 h before the reaction to obtain pretreated particles; S2: Mix 3.8 parts of the pretreated particles and 0.65 parts of trimellitic acid, add them to 80 parts of DMF solution, stir evenly and ultrasonically disperse for 15 min to obtain a mixed solution. Then, the DMF solution (a total of 20 parts) containing 1.75 parts of copper acetate is added dropwise to the mixed solution. The dropping temperature is 60°C, and stirring is carried out at a speed of 200 r / min during the dropping. The dropping time is 1 h. After the dropping is completed, the reaction is transferred to a high-pressure reactor, heated to 125°C, and kept warm and reacted for 16 h; S3: After the reaction is completed, 0.58 parts of triethanolamine is added, mixed and stirred for 1 h. The product is centrifuged and filtered, and the methanol washing and 80°C vacuum drying are cycled 3 times. After completion, it is obtained.

[0088] Comparative Example 6

[0089] The specific implementation manner of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified functional particles includes the following steps, by mass: S1: Mix 2.36 parts of expandable graphite and 0.72 parts of titanium dioxide, add them to 120 parts of deionized water, add 0.45 parts of calcium petroleum sulfonate and 1.28 parts of succinic anhydride, heat to 65°C, ultrasonically disperse evenly, and then stir and react at a speed of 100 r / min for 3 h. 0.28 parts of 3-aminopropyltriethoxysilane is added dropwise 0.5 h before the reaction to obtain pretreated particles; S2: Mix 6.5 parts of the pretreated particles and 0.35 parts of trimellitic acid, add them to 80 parts of DMF solution, stir evenly and ultrasonically disperse for 15 min to obtain a mixed solution. Then, the DMF solution (a total of 20 parts) containing 1.18 parts of copper acetate is added dropwise to the mixed solution. The dropping temperature is 60°C, and stirring is carried out at a speed of 200 r / min during the dropping. The dropping time is 1 h. After the dropping is completed, the reaction is transferred to a high-pressure reactor, heated to 125°C, and kept warm and reacted for 16 h; S3: After the reaction is completed, 0.31 parts of triethanolamine is added, mixed and stirred for 1 h. The product is centrifuged and filtered, and the methanol washing and 80°C vacuum drying are cycled 3 times. After completion, it is obtained.

[0090] Comparative Example 7

[0091] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the average particle size of titanium dioxide is 50 nm; the average particle size of expandable graphite is 12 μm.

[0092] Comparative Example 8

[0093] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the epoxy block copolymer is a block copolymer of ethylene oxide and propylene oxide, and the epoxy block copolymer is a composition of BASF L42 (weight average molecular weight 1600 g / mol) and BASF L85 (weight average molecular weight 4600 g / mol), and the mass ratio of the two is 1:1.

[0094] Performance Evaluation

[0095] 1. Conductivity test: The surface resistance of the polyurethane sponges prepared in the examples and comparative examples was tested. Conditions: temperature 25°C, relative humidity 50%. The surface of the polyurethane sponge was tested using a surface resistance meter, and the test value was the average of 10 tests and recorded in Table 1.

[0096] 2. Flame retardancy test: The polyurethane sponges prepared in the examples and comparative examples were tested for flame retardancy with reference to the standard GB / T8624-2012, and the flame retardancy grade results were recorded in Table 1.

[0097] 3. Mechanical test: The polyurethane sponges prepared in the examples and comparative examples were tested for tensile strength and elongation at break with reference to the standard GB / T10654-2001, and the test value was the average of 10 tests and recorded in Table 1.

[0098] 4. Waterproof test: Samples of 2 cm×2 cm×1 cm were prepared from the polyurethane sponges in the examples and comparative examples, and the surface water contact angle was tested using the sessile drop method. The size of the test water droplet was 2.5 μL, the test time was 10 s, the water contact angle at 10 s was calculated, and the test was continued until the water droplet was completely immersed in the polyurethane sponge, and the immersion time (s) was recorded. The test value was the average of 10 tests and recorded in Table 1.

[0099] 5. Aging resistance test: The polyurethane sponges prepared in the examples and comparative examples were placed in a constant temperature and humidity chamber at a temperature of 63°C and a relative humidity of 75% for 6 months, and their mechanical properties were tested again through Performance Test 3. If the performance data of their tensile strength and elongation at break both maintained 90% (including 90%) or more of the original values, it was recorded as qualified, otherwise it was unqualified. Each group was tested 50 times, and the aging resistance qualification rate % = number of qualified samples / 50 × 100%. The test value was the average of 10 tests and recorded in Table 1.

[0100] Table 1 Performance Test Results Table

[0101]

[0102] It can be seen from the data results of the embodiments and comparative examples of the present application and Table 1 that Embodiments 1 and 2 of the present application have obvious advantages over Comparative Examples 1-8 in terms of conductivity (antistatic), flame retardancy, mechanical properties, waterproofness, aging resistance, etc. This is mainly due to the combined action of the modified functional particles, epoxy block and polyol composition defined in the present application; while Comparative Examples 1-8 have obvious disadvantages in the above performances because they do not adopt the correct technical solution defined in the present application, which further proves the necessity of the technical solution defined in the present application for the technical effects and technical problems to be solved in the present application.

Claims

1. A high-conductivity halogen-free flame-retardant polyurethane sponge, characterized in that: By mass parts, the raw materials include: 40 - 50 parts of polyether polyol, 20 - 30 parts of polypropylene glycol, 5 - 15 parts of polytetrahydrofuran ether, 50 - 70 parts of polyisocyanate, 1 - 4 parts of deionized water, 5 - 15 parts of modified functional particles, 5 - 10 parts of flame retardant, 5 - 10 parts of epoxy block copolymer, 1 - 2 parts of catalyst, and 5 - 15 parts of auxiliary agent; The polyether polyol is at least one of polyoxypropylene polyol, polyoxypropylene / ethylene oxide copolymer polyol, glycerol - based polyether polyol, and tetrahydrofuran - propylene oxide copolymer polyol; The functionality of the polyether polyol is 3, and the weight - average molecular weight is 4500 - 7000 g / mol; The weight - average molecular weight of the polypropylene glycol is 2000 - 3000 g / mol; the weight - average molecular weight of the polytetrahydrofuran ether is 1000 - 1500 g / mol; The polyisocyanate is at least one of toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, cyclohexane diisocyanate, and xylylene diisocyanate; The preparation method of the modified functional particles includes: S1: Mix expandable graphite and titanium dioxide and add them into water. Add calcium petroleum sulfonate and succinic anhydride, heat to 60 - 70 °C, ultrasonically disperse evenly, and then stir - react at a speed of 60 - 120 r / min for 2 - 3 h. Drop - add 3 - aminopropyltriethoxysilane 0.5 h before the reaction to obtain pretreated particles; S2: Mix the pretreated particles and trimellitic acid and add them into the DMF solution, stir evenly and ultrasonically disperse for 10 - 15 min to obtain a mixed solution. Then drop - add the DMF solution containing copper acetate into the mixed solution. The dropping temperature is 50 - 60 °C, and stirring is carried out at a speed of 200 - 300 r / min during dropping. The dropping time is 1 - 1.5 h. After dropping, transfer the reaction to an autoclave, heat to 120 - 130 °C, and keep the temperature for reaction for 14 - 20 h; S3: After the reaction is completed, add triethanolamine, mix and stir for 0.5 - 1 h. Centrifuge and filter the product, wash it with methanol, and carry out vacuum drying at 80 - 90 °C for multiple cycles. After completion, it is obtained; The mass ratio of expandable graphite, titanium dioxide, calcium petroleum sulfonate, succinic anhydride, and 3 - aminopropyltriethoxysilane is (2 - 3):(0.5 - 1):(0.4 - 0.8):(1 - 1.5):(0.1 - 0.3); The mass ratio of pretreated particles, trimellitic acid, copper acetate, and triethanolamine is (3.5 - 4):(0.4 - 0.8):(1.2 - 2):(0.4 - 0.6); The flame retardant is a composition obtained by compounding ammonium polyphosphate and zinc borate with a mass ratio of (4 - 8):(2 - 4); The average particle size of titanium dioxide is 10 - 30 nm; the average particle size of expandable graphite is 4 - 8 μm; The epoxy block copolymer is a composition obtained by compounding ethylene oxide with a weight - average molecular weight of 1000 - 2000 g / mol and propylene oxide with a weight - average molecular weight of 4000 - 5000 g / mol in a mass ratio of (1 - 1.5):(3 - 4); The auxiliaries include a co - compounded auxiliary foaming agent and surfactant with a mass ratio of (0.5~2):(6~10).

2. The highly conductive halogen-free flame-retardant polyurethane sponge according to claim 1, wherein: The mass ratio of the polyether polyol, polypropylene glycol, polytetrahydrofuran ether and polyisocyanate is (4~4.5):(2~2.5):(1~1.5):(5.5~6.5).

3. The highly conductive halogen-free flame-retardant polyurethane sponge according to claim 2, wherein: The polytetrahydrofuran ether is polytetrahydrofuran diol.

4. The highly conductive halogen-free flame-retardant polyurethane sponge according to claim 3, characterized in that: The polyisocyanate is 2,4'-diphenylmethane diisocyanate.

5. A method for preparing a highly conductive halogen-free flame-retardant polyurethane sponge according to any one of claims 1 to 4, characterized in that: It includes the following specific steps: S1: The modified functional particles and epoxy block are taken out together after being mixed in a high - speed mixer at 200~300 rpm for 30~40 min. Then they are mixed with polyether polyol, polypropylene glycol, polytetrahydrofuran ether, deionized water, flame retardant, catalyst and auxiliaries, and stirred at 60~120 rpm for 20~40 min to be uniformly mixed; S2: Polyisocyanate is added and stirred at 1500~2000 rpm for 3~5 min. The stirred mixture is placed into a sponge mold, the mold temperature is controlled at 30~35 °C, and heat - insulated for 20~25 h. After completion, it is washed and cut to obtain the product.

6. Application of the high - conductivity halogen - free flame - retardant polyurethane sponge according to any one of claims 1~4 in electronic devices, electromagnetic interference shielding, electrostatic discharge protection, sensor devices and intelligent textiles.

Images