Preparation method of efficient fireproof and flame-retardant coating for wires and cables

Abstract

The invention discloses a preparation method of an efficient fireproof and flame-retardant coating for wires and cables, and belongs to the technical field of wire and cable coatings. Aiming at the defects of low flame-retardant efficiency, poor high-temperature-resistant stability and insufficient environmental protection property of the existing coating, performance breakthrough is realized through an innovative formula and process design. The flame-retardant coating comprises the following components in parts by weight: 30-40 parts of acrylate resin, 20-30 parts of a composite flame-retardant system (compounded by modified magnesium hydroxide, ammonium polyphosphate and pentaerythritol phosphate according to a ratio of 5: 3: 2), 1.5-3 parts of a high-temperature-resistant modified component, 4-6 parts of an environment-friendly coalescing agent (compounded by polyethylene glycol monomethyl ether and tributyl citrate according to a ratio of 1: 1), other auxiliaries and deionized water. The preparation method comprises the steps of raw material pretreatment, stepped stirring and mixing, and grinding by a sand mill. The flame-retardant grade of the prepared coating reaches grade A, the coating is free of cracking and falling at the high temperature of 1300 DEG C, VOC is smaller than or equal to 10 g / L, no heavy metal is detected, meanwhile, the adhesive force reaches grade 1, the flexibility is larger than or equal to 0.8 mm, the problem that multiple properties are difficult to consider in the prior art is solved, and the coating is suitable for coating of various high-low voltage electric wires and cables.

Description

Technical Field

[0001] This invention relates to the field of wire and cable coating technology, specifically to a method for preparing a highly efficient fire-retardant coating for wires and cables. Background Technology

[0002] Existing fire-retardant coatings for wires and cables have the following shortcomings, making it difficult to meet the current requirements for high safety and high stability in wire and cable applications: 1. The flame retardant efficiency is relatively low, and most of them rely on a single type of flame retardant (such as halogenated, phosphorus-based or inorganic flame retardants). In order to achieve the ideal flame retardant effect, a large amount needs to be added, which leads to abnormal viscosity of the coating, reduced film-forming properties, and also reduces the flexibility of wires and cables.

[0003] 2. Poor high-temperature stability. In high-temperature environments (such as above 800℃), the coating is prone to decomposition and peeling, and cannot maintain the flame-retardant barrier for a long time, making it difficult to cope with the continuous high-temperature conditions in a fire.

[0004] 3. Insufficient environmental performance: Some coatings use flame retardants or film-forming aids containing heavy metals or halogenated compounds, which are prone to releasing harmful substances during production, use and disposal, failing to meet the current environmental protection policy requirements for low pollution and no harm. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a highly efficient fire-retardant coating for wires and cables. The aim is to solve the problem that existing coatings are difficult to balance in terms of flame retardancy, high temperature resistance, and environmental friendliness through innovative component design and process optimization.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a highly efficient fire-retardant coating for wires and cables. Through a three-component formulation design and synergistic process, it achieves an integrated approach of "highly efficient flame retardancy, high-temperature stability, and environmentally friendly non-toxicity." Compared with existing technologies, it possesses the following unique innovations: Composite Flame Retardant System Design: A ternary composite system of "inorganic flame retardant - organic flame retardant - synergist" is adopted. The inorganic flame retardant is modified magnesium hydroxide (surface-treated with a silane coupling agent), the organic flame retardant is ammonium polyphosphate (degree of polymerization ≥1000), and the synergist is pentaerythritol phosphate, with a mass ratio of 5:3:2. This system significantly improves flame retardant efficiency through gas-phase flame retardancy (endothermic decomposition of the organic flame retardant), condensed-phase flame retardancy (formation of an insulating layer by the inorganic flame retardant), and the char-promoting effect of the synergist. Furthermore, the total amount of flame retardant added is reduced by 20%-30% compared to existing technologies, avoiding any impact on the film-forming properties of the coating.

[0007] High-temperature resistant modifier introduction: Add 0.5%-1% nano-silicon carbide and 1%-2% epoxy resin modifier to the coating system. Nano-silicon carbide can fill the internal pores of the coating and improve the density of the coating. Epoxy resin modifier can form a cross-linked network with the base material, enhance the structural stability of the coating at high temperatures, and enable the coating to maintain its integrity and not decompose or fall off at 1300℃.

[0008] Environmentally friendly film-forming aids are selected: abandoning traditional benzene- and ester-containing film-forming aids, we use an environmentally friendly aid that is a compound of polyethylene glycol monomethyl ether and tributyl citrate in a 1:1 mass ratio. This aid does not release volatile organic compounds (VOCs) and has good compatibility with the components of the coating. It can improve the smoothness of the coating film and meets the EU RoHS environmental standards.

[0009] (II) Composition of Coating Raw Materials By weight, the raw materials for coatings include: Base material: 30-40 parts of acrylic resin; Composite flame retardant system: 10-15 parts modified magnesium hydroxide, 6-9 parts ammonium polyphosphate, and 4-6 parts pentaerythritol phosphate; High-temperature resistant modifying components: 0.5-1 parts of nano-silicon carbide, 1-2 parts of epoxy resin modifier; Film-forming aids: 2-3 parts polyethylene glycol monomethyl ether, 2-3 parts tributyl citrate; Other additives: dispersant (sodium polycarboxylate) 0.3-0.5 parts, defoamer (silicone) 0.2-0.4 parts, thickener (hydroxyethyl cellulose) 0.1-0.3 parts; Solvent: 25-35 parts deionized water.

[0010] (III) Preparation Method and Steps Raw material pretreatment: Place modified magnesium hydroxide, ammonium polyphosphate, and pentaerythritol phosphate in a drying oven and dry at 80-100℃ for 2-3 hours to remove moisture; add nano-silicon carbide to deionized water and ultrasonically disperse for 30-40 minutes to form a nano-silicon carbide dispersion for later use.

[0011] Base material mixing: Add acrylate resin and deionized water (60% of the total water volume) to the reactor, set the stirring speed to 500-600 r / min, and stir for 15-20 minutes to fully dissolve the base material.

[0012] Addition of flame retardant system and modified components: First, add the pretreated composite flame retardant system components to the reactor, increase the stirring speed to 800-1000 r / min, and stir for 30-40 minutes; then add nano silicon carbide dispersion and epoxy resin modifier, and continue stirring for 20-25 minutes to ensure that each component is evenly dispersed.

[0013] Additives and grinding: Add dispersant, defoamer, thickener and remaining deionized water in sequence, stir for 10-15 minutes, transfer the mixture to a sand mill and grind until the particle size is ≤50μm for 1-1.5 hours.

[0014] Film-forming aid addition and adjustment: Return the ground material to the reactor, add polyethylene glycol monomethyl ether and tributyl citrate, adjust the stirring speed to 600-700 r / min, and stir for 15-20 minutes; test the viscosity of the coating. If the viscosity does not meet the requirements (standard viscosity is 80-100s, Ford cup method), adjust it to the standard range by adding or subtracting thickener or deionized water to obtain a high-efficiency fire-retardant coating for wires and cables.

[0015] In summary, due to the adoption of the above-mentioned technologies, the beneficial effects of this invention are: 1. Higher flame retardant efficiency: Through the synergistic effect of the ternary composite flame retardant system, the flame retardant rating of the coating can reach Class A while reducing the amount of flame retardant added, thus solving the problem that existing coatings cannot achieve both "high flame retardancy and low additives".

[0016] 2. Enhanced high-temperature stability: The introduction of nano-silicon carbide and epoxy resin modifiers enables the coating to maintain structural stability at 1300℃, filling the technological gap of existing coatings that are prone to failure at high temperatures.

[0017] 3. Superior environmental performance: It uses film-forming aids and flame-retardant components that are free of VOCs and heavy metals. No harmful substances are released during the production and use process, which meets the current environmental protection policies and market demand for green coatings. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention, making other features, objects, and advantages of the invention more apparent. The illustrative embodiments of the invention illustrated in the drawings and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a diagram of the method of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific context of the specification.

[0022] This invention provides a method for preparing a highly efficient fire-retardant coating for wires and cables, comprising: Example 1

[0023] The raw material composition by weight is as follows: 35 parts acrylate resin, 12 parts modified magnesium hydroxide, 7 parts ammonium polyphosphate, 5 parts pentaerythritol phosphate, 0.8 parts nano silicon carbide, 1.5 parts epoxy resin modifier, 2.5 parts polyethylene glycol monomethyl ether, 2.5 parts tributyl citrate, 0.4 parts sodium polycarboxylate, 0.3 parts silicone defoamer, 0.2 parts hydroxyethyl cellulose, and 30 parts deionized water.

[0024] The preparation steps were strictly carried out in accordance with the above "(III) Preparation Method Steps", including drying temperature of 90℃, drying time of 2.5 hours, ultrasonic dispersion of nano-silicon carbide for 35 minutes, mixing and stirring speed of base material of 550 r / min for 18 minutes, stirring speed of 900 r / min for 35 minutes after adding flame retardant system, and grinding time of sand mill for 1.2 hours.

[0025] Performance test results The performance of the coating prepared in Example 1 was tested, and the results are as follows: Flame retardant performance: According to GB / T19216.21-2003 standard, the flame retardant rating of the coated wires and cables reaches Class A, with a burning time of ≤30s and no dripping.

[0026] High temperature resistance: After being kept at a constant temperature of 1300℃ in a muffle furnace for three hours, the coating did not crack or peel off and could still completely cover the wires and cables.

[0027] Environmental performance: Tested according to GB / T27860-2011 standard, VOC content ≤10g / L, no heavy metals (lead, mercury, cadmium, hexavalent chromium) detected, meeting environmental protection requirements.

[0028] Mechanical properties: The coating adhesion reaches level 1 (cross-cut test) and the flexibility reaches 1mm (bending test), meeting the bending requirements of wires and cables during use. Example 2

[0029] The raw material composition by mass parts is as follows: 30 parts acrylate resin, 10 parts modified magnesium hydroxide, 6 parts ammonium polyphosphate, 4 parts pentaerythritol phosphate, 0.5 parts nano silicon carbide, 1 part epoxy resin modifier, 2 parts polyethylene glycol monomethyl ether, 2 parts tributyl citrate, 0.3 parts sodium polycarboxylate, 0.2 parts organosilicon defoamer, 0.1 parts hydroxyethyl cellulose, and 25 parts deionized water.

[0030] In the preparation steps, the drying temperature is 80℃ and the drying time is 2 hours; the nano-silicon carbide is ultrasonically dispersed for 30 minutes; the base material is mixed and stirred at a speed of 500 r / min for 15 minutes; after the flame retardant system is added, the stirring speed is 800 r / min for 30 minutes; and the grinding time in a sand mill is 1 hour.

[0031] Performance test results: Flame retardant performance: Flame retardant rating A, burning time 28s, no dripping; High temperature resistance: After being kept at 1300℃ for three hours, the coating showed no cracking or slight discoloration and remained completely intact. Environmental performance: VOC content 8g / L, no heavy metals detected; Mechanical properties: Adhesion grade 1, flexibility 1mm. Example 3

[0032] The raw material composition by mass parts is as follows: 40 parts acrylate resin, 15 parts modified magnesium hydroxide, 9 parts ammonium polyphosphate, 6 parts pentaerythritol phosphate, 1 part nano silicon carbide, 2 parts epoxy resin modifier, 3 parts polyethylene glycol monomethyl ether, 3 parts tributyl citrate, 0.5 parts sodium polycarboxylate, 0.4 parts organosilicon defoamer, 0.3 parts hydroxyethyl cellulose, and 35 parts deionized water.

[0033] In the preparation steps, the drying temperature is 100℃ and the drying time is 3 hours; the nano-silicon carbide is ultrasonically dispersed for 40 minutes; the base material is mixed and stirred at a speed of 600 r / min for 20 minutes; after the flame retardant system is added, the stirring speed is 1000 r / min for 40 minutes; and the grinding time in a sand mill is 1.5 hours.

[0034] Performance test results: Flame retardant performance: Flame retardant rating A, burning time 25s, no dripping; High temperature resistance: After being kept at 1300℃ for three hours, the coating showed no change and remained completely covered; Environmental performance: VOC content 9g / L, no heavy metals detected; Mechanical properties: Adhesion grade 1, flexibility 0.8mm.

[0035] Example 4 (Specific Scenario Adaptation: Cable Coating for Rail Transit) (a) Raw material composition (by mass parts) The composite flame-retardant system consists of 38 parts acrylate resin, 14 parts modified magnesium hydroxide, 8.4 parts ammonium polyphosphate, and 5.6 parts pentaerythritol phosphate, maintaining a mass ratio of 5:3:2. The high-temperature resistant modifying components include 0.9 parts nano-silicon carbide and 1.8 parts epoxy resin modifier, with a mass ratio of 1:2. The film-forming aid is a 1:1 mixture of 2.8 parts polyethylene glycol monomethyl ether and 2.8 parts tributyl citrate. Other additives include 0.45 parts sodium polycarboxylate, 0.35 parts silicone defoamer, and 0.25 parts hydroxyethyl cellulose. The solvent is 32 parts deionized water. Additionally, 0.2 parts benzotriazole UV absorber are added to suit the outdoor exposure scenarios of rail transit cables.

[0036] (II) Adjustment of preparation steps In the raw material pretreatment stage, the ultrasonic dispersion time of nano-silicon carbide is extended to 45 minutes to improve its dispersion stability in coatings and meet the needs of long-term outdoor use.

[0037] The grinding time of the sand mill is set to 1.4 hours, and the particle size of the coating is controlled to be ≤40μm. The weather resistance of the coating is enhanced by finer particle size.

[0038] In the final stage of coating mixing, add the UV absorber and stir at 650 rpm for 15 minutes to ensure uniform dispersion of the absorber.

[0039] Performance test results (focusing on weather resistance) In terms of basic performance, the coating achieves a flame retardant rating of Class A with a burning time of 26 seconds; after being kept at a constant temperature of 1300℃ for three hours, the coating showed no cracking or peeling; the VOC content is 9.5g / L, meeting environmental protection requirements. In weather resistance testing, after 1000 hours of xenon lamp aging, the coating showed no chalking or discoloration, its adhesion remained at Level 1, and its flexibility reached 1mm, fully meeting the weather resistance requirements for outdoor use of rail transit cables.

Claims

1. A method for preparing a highly efficient fire-retardant coating for wires and cables, characterized in that, The process includes raw material preparation and stepwise mixing and grinding steps. The raw materials, by mass parts, include: 30-40 parts of acrylate resin, 20-30 parts of composite flame retardant system, 1.5-3 parts of high-temperature resistant modifier, 4-6 parts of film-forming aid, 0.6-1.2 parts of other additives, and 25-35 parts of deionized water. The composite flame retardant system is composed of modified magnesium hydroxide, ammonium polyphosphate, and pentaerythritol phosphate in a mass ratio of 5:3:

2. The high-temperature resistant modifier includes nano-silicon carbide and epoxy resin modifier in a mass ratio of 1:(2-4). The film-forming aid is a compound of polyethylene glycol monomethyl ether and tributyl citrate in a mass ratio of 1:

1.

2. The method for preparing a high-efficiency fire-retardant coating for wires and cables according to claim 1, characterized in that, In the composite flame retardant system, the modified magnesium hydroxide is magnesium hydroxide surface-treated with a silane coupling agent, and the degree of polymerization of ammonium polyphosphate is ≥1000.

3. The method for preparing a high-efficiency fire-retardant coating for wires and cables according to claim 1, characterized in that, In the high-temperature resistant modified component, the amount of nano-silicon carbide added is 0.5-1 parts, and the amount of epoxy resin modifier added is 1-2 parts.

4. The method for preparing a high-efficiency fire-retardant coating for wires and cables according to claim 1, characterized in that, The other additives include dispersants, defoamers, and thickeners; wherein the dispersant is sodium polycarboxylate, added at 0.3-0.5 parts; the defoamer is an organosilicon, added at 0.2-0.4 parts; and the thickener is hydroxyethyl cellulose, added at 0.1-0.3 parts.

5. The method for preparing a high-efficiency fire-retardant coating for wires and cables according to claim 1, characterized in that, The raw material pretreatment steps are as follows: modified magnesium hydroxide, ammonium polyphosphate, and pentaerythritol phosphate are dried at 80-100℃ for 2-3 hours; nano-silicon carbide is added to deionized water and ultrasonically dispersed for 30-40 minutes to form a dispersion.

6. The method for preparing a high-efficiency fire-retardant coating for wires and cables according to claim 1, characterized in that, The stepwise mixing step includes: S1: Base material mixing: Add acrylate resin and 60% of the total water volume of deionized water to the reactor, and stir at 500-600 r / min for 15-20 minutes; S2: Mixing flame retardant and modified components: Add the pretreated composite flame retardant system, stir at 800-1000 r / min for 30-40 minutes, then add nano silicon carbide dispersion and epoxy resin modifier, and continue stirring for 20-25 minutes; S3: Mixing of additives and film-forming agents: Add other additives and the remaining deionized water, stir for 10-15 minutes, then grind with a sand mill until the particle size is ≤50μm, then add the film-forming agent, and stir at 600-700r / min for 15-20 minutes.

7. The method for preparing a high-efficiency fire-retardant coating for wires and cables according to claim 6, characterized in that, The grinding time of the sand mill is 1-1.5 hours. After grinding, the viscosity of the coating is adjusted to 80-100s by adding or subtracting thickener or deionized water (Ford Cup 4 method).

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