Fireproof industrial coating and preparation method thereof

Abstract

The invention relates to a fireproof industrial coating and a preparation method thereof, and belongs to the field of coatings. The coating is prepared from the following components in parts by weight: 40 to 50 parts of epoxy resin, 8 to 12 parts of tetrabromo phthalic anhydride (TBPA), 15 to 20 parts of organic polyborosilazane (PSNB), 10 to 15 parts of pentaerythritol, 6 to 8 parts of melamine, 3 to 5 parts of modified nano silicon dioxide, 8 to 10 parts of epoxy curing agent DDS and 3 to 4 parts of auxiliaries. By adopting a TBPA and PSNB synergistic flame-retardant system, a dual protection mechanism of'initial carbon layer barrier-high-temperature ceramic reinforcement 'is constructed, and the interface bonding force is enhanced by combining with silane coupling agent modified nano silicon dioxide, so that the mechanical property of the coating is effectively improved. Tests show that the fire endurance of the coating reaches 180-205 minutes, the impact strength is 7.5-9.5 kJ / m < 2 >, the performance bottleneck of the traditional fireproof coating is broken through, and the coating has both intumescent efficient heat insulation and non-intumescent structural stability.

Description

Technical Field

[0001] The present invention relates to the field of coatings, in particular to a fire-retardant industrial coating and a preparation method thereof. Background Art

[0002] Current fire-retardant industrial coating technology is primarily divided into two main systems: intumescent and non-intumescent. These systems exhibit fundamental contradictions in their fire-retardant mechanisms and mechanical properties. Intumescent fire-retardant coatings, exemplified by the ammonium polyphosphate (APP)-pentaerythritol (PER)-melamine (MEL) ternary system, achieve fire protection by foaming at high temperatures to form a carbonaceous insulating layer. Their fire-retardant performance is significantly superior, with typical products achieving a fire resistance limit of over 120 minutes, and halogen-free formulations achieving a smoke toxicity rating of F1. However, the intumescent layer's porous carbon structure results in an impact strength of less than 5 MPa, making it susceptible to microcracks under long-term exposure. Furthermore, adhesion to the steel substrate relies on physical adsorption, with bond strength decreasing by over 40% after 1000 hours in salt spray testing. Furthermore, intumescent coatings exhibit significant thermal cycling sensitivity, exhibiting delamination after 50 cycles of heating and cooling between -40°C and 80°C, resulting in a 35% reduction in overall protective effectiveness. Non-expanding fire-retardant coatings use silicate materials as their core and form a ceramic protective layer through high-temperature melting. This type of coating has the advantage of high adhesion, with the bonding strength between the coating and the steel substrate reaching over 8MPa, and a service life of over 20 years in marine atmospheric environments. However, its maximum fire resistance limit is only 90 minutes, which cannot meet the stringent fire protection requirements of super-high-rise buildings; at the same time, the thermal conductivity of the ceramic layer is as high as 0.35W / m·K, which is much higher than the 0.22W / m·K of the intumescent coating, limiting its actual thermal insulation effect. In addition, the minimum coating thickness of non-expanding coatings must reach 20mm, resulting in a 30%-50% increase in the load per unit area, making it less suitable for scenarios requiring lightweighting.

[0003] The root of the above problems lies in the essential conflict between the fire protection mechanism and mechanical properties. The structural contradiction of the expansion system is that the fire protection efficiency depends on the rapid expansion of the carbon layer at high temperature, but the expansion process is inevitably accompanied by the destruction of the coating's main structure; the inherent brittleness of non-expanding coatings makes it unable to withstand the strain caused by structural deformation. Conventional flame retardants (such as aluminum hydroxide) improve the fire resistance, but their hygroscopicity leads to a decrease in the adhesion of the coating, further exacerbating the performance contradiction. This technical dilemma has caused the existing technical system to reach its performance limit. It is urgent to achieve the synergistic effect of flame retardant components and mechanical reinforcement components through molecular design and establish a technical paradigm for new fire retardant coatings. Summary of the Invention

[0004] To solve the above problems, the present invention provides a fire-retardant industrial coating, which comprises, by mass: 40-50 parts of epoxy resin, 8-12 parts of tetrabromophthalic anhydride (TBPA), 15-20 parts of organic polyborosilazane (PSNB), 10-15 parts of pentaerythritol, 6-8 parts of melamine, 3-5 parts of modified nano-silica, 8-10 parts of epoxy curing agent DDS, and 3-4 parts of additives.

[0005] Preferably, the epoxy resin is one or more of bisphenol A epoxy resin E-51, bisphenol F epoxy resin F-44 or novolac epoxy resin F-51.

[0006] Preferably, the auxiliary agent is 0.5-1.0 part of a dispersant, 0.1-0.3 part of a defoaming agent, 0.5-1.0 part of a wetting agent, 1.0-1.5 parts of an anti-settling agent, and 0.5-1.0 part of an ultraviolet absorber.

[0007] Preferably, the dispersant is one or more of BYK-163, BYK-190 or EFKA-4010, the defoamer is one or more of BYK-052, Foamaster NXZ or Emultrol DFMAFO-1, the wetting agent is one or more of BYK-345, WSS-713 or Tego Wet 500, the anti-settling agent is one or more of DISPARLON 6900-20X or BENTONE 34, and the ultraviolet absorber is one or more of Tinuvin 292 or UV-360.

[0008] A method for preparing a fire-retardant industrial coating comprises the following steps:

[0009] (1) After mixing epoxy resin and tetrabromophthalic anhydride (TBPA), stirring and reacting at high temperature to form a homogeneous system;

[0010] (2) adding organopolyborosilazane (PSNB), pentaerythritol, and melamine to the homogenous system in sequence, and shearing and stirring to obtain a flame retardant base material;

[0011] (3) After surface modification of the nano-silica, the nano-silica is added to the flame retardant base material in batches and shearing and stirring are continued;

[0012] (4) premixing the epoxy curing agent DDS with the auxiliary agent and adding the mixture to the base material twice to adjust the viscosity of the system to obtain the curing agent;

[0013] (5) The flame retardant base material and the curing agent are mixed evenly to obtain a finished coating.

[0014] Preferably, in step (1), the high temperature is 80-100° C., the stirring time is 1-2 hours, and the stirring speed is 300-500 r / min.

[0015] Preferably, in step (2), the shear stirring speed is 800-1000 r / min, the stirring time is 45-60 minutes, and the addition interval of PSNB, pentaerythritol and melamine is 5 minutes.

[0016] Preferably, in step (3), the surface modification uses silane coupling agent KH-560, the addition amount of which is 3% of the mass of nano-SiO2, and the modification process includes ultrasonic dispersion for 30 minutes (frequency 40kHz) and adding the flame retardant base material three times (each time with an interval of 10 minutes).

[0017] Preferably, in step (4), the diluent is C12-C14 glycidyl ether, the viscosity adjustment range is 900-1100 mPa·s, and when DDS is added in two times, the first addition amount is 50% of the total mass.

[0018] Preferably, it is characterized in that: in step (5), the mixing temperature is 50°C, the stirring speed is 300r / min, the mixing time is 20 minutes, and then it is allowed to stand and degas at 40°C for 1 hour.

[0019] Beneficial effects:

[0020] Through innovative component design and process optimization, the present invention has successfully broken through the technical bottlenecks of traditional fire-retardant industrial coatings in fire retardant properties and mechanical properties, and achieved a synergistic improvement in multiple key performances.

[0021] Its core advantages are reflected in the following aspects:

[0022] First, a synergistic flame retardant system of TBPA and PSNB is employed. The rapid carbonization of the brominated flame retardant forms an initial porous barrier, which, combined with the SiO2-B2O3 glassy network generated by the organic polyborosilazane at high temperatures, creates a dual protection mechanism of "initial carbon layer barrier followed by high-temperature ceramic reinforcement." This significantly extends the fire resistance limit and overcomes the technical limitations of traditional intumescent and non-intumescent coatings.

[0023] Secondly, after being modified with a coupling agent, nano-silica significantly enhances the interfacial bonding between the coating and the substrate through chemical bonding and gradient dispersion processes, significantly improving impact strength and effectively resisting mechanical damage. At the same time, adhesion is significantly enhanced, ensuring a strong bond between the coating and the substrate, solving the pain point of brittle cracking of traditional intumescent coatings.

[0024] Furthermore, by optimizing the epoxy resin type and regulating the curing process, a dense three-dimensional cross-linked network is constructed, significantly reducing thermal conductivity. This allows the coating to combine the high thermal insulation performance of an intumescent coating with the structural stability of a non-intumescent coating. Regarding process innovation, the unique "five-step synergistic method" achieves precise control of component dispersion and viscosity, significantly reducing coating thickness and shortening the curing cycle. Regarding environmental adaptability, the addition of UV absorbers and anti-settling agents significantly improves the coating's weathering and corrosion resistance, ensuring stable long-term performance.

[0025] This technology breaks through the performance limits of traditional fire retardant coatings through the synergy of molecular design and process, providing a revolutionary solution for the fire protection field that combines high-efficiency fire protection, high strength and toughness, and long-life protection. DETAILED DESCRIPTION

[0026] Example 1

[0027] Components (parts by mass): 145 parts of epoxy resin E-5, 8 parts of TBPA, 15 parts of PSNB, 10 parts of pentaerythritol, 6 parts of melamine, 3 parts of modified nano-SiO2, 8 parts of DDS curing agent, additives: 30.5 parts of dispersant BYK-16, 20.1 parts of defoaming agent BYK-05, 0.5 parts of wetting agent BYK-345, 1.0 parts of anti-settling agent DISPARLON 6900-20X, and 20.9 parts of ultraviolet absorber Tinuvin 29.

[0028] Preparation method: add epoxy resin E-51 and TBPA into a reactor, heat to 80°C, and stir at 300r / min for 1 hour to form a homogeneous system; add PSNB, pentaerythritol, and melamine in sequence, and shear stir at 800r / min for 45 minutes; mix nano-SiO2 and silane coupling agent KH-560, ultrasonically disperse for 30 minutes (40kHz), and add flame retardant base material three times, each time with an interval of 10 minutes; premix DDS curing agent and additives, add C12-C14 glycidyl ether diluent to adjust the viscosity to 900mPa·s (50% of the total amount of DDS is added for the first time), and the remaining 50% is added later; finally, mix the flame retardant base material and curing agent, stir at 50°C for 20 minutes, and stand at 40°C for degassing for 1 hour to obtain the finished coating.

[0029] Example 2

[0030] Components (parts by mass): 150 parts of epoxy resin F-51, 12 parts of TBPA, 20 parts of PSNB, 15 parts of pentaerythritol, 8 parts of melamine, 5 parts of modified nano-SiO2, 10 parts of DDS curing agent, additives: 1.0 parts of dispersant EFKA-4010, 0.3 parts of defoaming agent FoamasterNXZ, 1.0 parts of wetting agent TegoWet500, 1.2 parts of anti-settling agent BENTONE34, and 0.5 parts of ultraviolet absorber UV-360.

[0031] Preparation method: Epoxy resin F-51 and TBPA are heated to 100°C and stirred at 500 r / min for 2 hours to form a prepolymer; PSNB, pentaerythritol, and melamine are added in sequence and sheared and stirred at 1000 r / min for 60 minutes; nano-SiO2 is treated with KH-560 and then added to the flame retardant base material in three times, with an interval of 10 minutes each time, and the viscosity is adjusted to 1100 mPa·s; DDS curing agent and additives are premixed and added in two times (50% for the first time), and the remaining part is added; the flame retardant base material and curing agent are stirred at 60°C for 30 minutes, degassed, and then allowed to stand.

[0032] Example 3

[0033] Components (parts by mass): 145 parts of epoxy resin E-5, 10 parts of TBPA, 20 parts of PSNB, 12 parts of pentaerythritol, 7 parts of melamine, 4 parts of modified nano-SiO2, 9 parts of DDS curing agent, additives: dispersant BYK-190 0.8 parts, defoamer Emultrol DFMAFO-10.2 parts, wetting agent WSS-713 0.7 parts, anti-settling agent DISPARLON 6900-20X 1.3 parts, ultraviolet absorber UV-360 0.5 parts.

[0034] Preparation method: Epoxy resin E-51 and TBPA were stirred at 80°C for 1 hour to form a homogeneous system; PSNB, pentaerythritol, and melamine were added in sequence, and shear stirring was performed at 900r / min for 50 minutes; nano-SiO2 was treated with KH-560 and then added to the flame retardant base material in three times, with an interval of 10 minutes each time, and the viscosity was adjusted to 1000mPa·s; DDS curing agent and additives were premixed and added in two times (50% for the first time), and the remaining part was added; the flame retardant base material and curing agent were stirred at 50°C for 20 minutes, and then allowed to stand at 40°C for 1 hour for degassing.

[0035] Example 4

[0036] Components (parts by mass): 448 parts of epoxy resin F-4, 10 parts of TBPA, 16 parts of PSNB, 10 parts of pentaerythritol, 8 parts of melamine, 3 parts of modified nano-SiO2, 8 parts of DDS curing agent, additives: 0.6 parts + 0.4 parts of dispersant BYK-163 and EFKA-4010, 0.1 parts + 0.2 parts of defoamer BYK-052 and FoamasterNXZ, 0.6 parts of wetting agent BYK-345, 1.4 parts of anti-settling agent BENTONE, and 0.5 parts of UV absorber Tinuvin 292.

[0037] Preparation method: Epoxy resin F-44 and TBPA are stirred at 90°C for 1.5 hours to form a transparent solution; PSNB, pentaerythritol, and melamine are added in sequence, and shear stirring is performed at 850r / min for 55 minutes; nano-SiO2 is treated with KH-560 and then added to the flame retardant base material in three batches, and the shear rate is increased to 950r / min; DDS curing agent and additives are premixed and added in two batches (50% for the first time), and the remaining part is added; the flame retardant base material and curing agent are stirred at 50°C for 20 minutes, and then allowed to stand at 40°C for degassing for 1 hour.

[0038] Example 5

[0039] Components (parts by mass): 142 parts of epoxy resin F-5, 12 parts of TBPA, 15 parts of PSNB, 15 parts of pentaerythritol, 6 parts of melamine, 5 parts of modified nano-SiO2, 10 parts of DDS curing agent, additives: dispersant BYK-190 0.7 parts, defoamer Emultrol DFMAFO-10.15 parts, wetting agent WSS-713 0.5 parts, anti-settling agent DISPARLON 6900-20X 1.0 parts, ultraviolet absorber UV-360 0.85 parts.

[0040] Preparation method: Epoxy resin F-51 and TBPA are stirred at high speed (500r / min) at 100°C for 2 hours to form a highly cross-linked prepolymer; PSNB, pentaerythritol, and melamine are added in sequence, and shear stirring is performed at 1000r / min for 60 minutes; nano-SiO2 is treated with KH-560 and then added to the flame retardant base material in three times, with an interval of 10 minutes each time, and the viscosity is adjusted to 1100mPa·s; DDS curing agent and auxiliary agent are premixed and added in two times (50% for the first time), and the remaining part is added; the flame retardant base material and curing agent are stirred at 60°C for 30 minutes, degassed, and then allowed to stand.

[0041] Comparative Example 1

[0042] The difference from Example 1 is that TBPA was not added, and the preparation steps were modified accordingly.

[0043] Comparative Example 2

[0044] The difference from Example 1 is that no PSNB is added, and the preparation steps are modified accordingly.

[0045] Comparative Example 3

[0046] The difference from Example 1 is that no TBPA was added, the amount of PSNB added was 23 parts, and the preparation steps were modified accordingly.

[0047] Comparative Example 4

[0048] The difference from Example 1 is that no PSNB was added, the amount of TBPA added was 23 parts, and the preparation steps were modified accordingly.

[0049] Comparative Example 5

[0050] The difference from Example 1 is that the added amounts of TBPA and PSNB are 3 parts and 20 parts, respectively.

[0051] Fire resistance testing is conducted in accordance with GB / T9978-2008, "Test Methods for Fire Resistance of Building Components," by simulating an actual fire environment to evaluate the coating's load-bearing protection capabilities at elevated temperatures. A horizontal fire resistance test furnace was used to heat standard steel beam specimens (300mm×150mm×10mm, coating dry film thickness 3±0.5mm) to (800±50)°C at a heating rate of (5±1)°C / min. The time from exposure to fire to loss of load-bearing capacity (deflection exceeding span L / 20) was recorded. The specimens were then cured for 28 days to ensure complete coating cure. Temperature changes were monitored via thermocouples, and specimen deformation was recorded in real time via displacement sensors.

[0052] The adhesion test adopts the standard GB / T5210-2006 "Adhesion test for paints and varnishes by pull-off method" to quantify the bonding strength between the coating and the steel substrate by the pull-off method. The test uses a pull-off instrument (range ≥10MPa) to test steel test panels (150mm×75mm×3mm, coating dry film thickness 3±0.5mm) that have been cured for 28 days. The surface of the specimen must be treated with a grid to form a checkerboard grid with a spacing of 1mm (deep to the substrate) to ensure that the interface between the coating and the substrate is completely exposed. During the test, the pulling head is loaded vertically at a rate of (5±1)mm / min until the coating is completely peeled off. The maximum load value is calculated using the formula "adhesion = maximum load / grid area".

[0053] Impact strength testing is conducted in accordance with ASTM D256-2020, "Plastics, Test Method for Impact Properties," using a pendulum impact test to assess the coating's resistance to mechanical damage. A 125mm diameter, 3mm thick steel specimen (coating dry film thickness 3±0.5mm) was used, with the pendulum energy set to 0.5J or 1.0J. After the specimen was secured to the testing machine base, the pendulum was released from a fixed height and impacted the center of the specimen, observing for cracks or delamination of the coating.

[0054] Thermal conductivity was determined according to ASTM C518-2019 "Test method for steady-state thermal conductivity", using a heat flow meter to measure the thermal insulation performance of the coating. The test used a cylindrical specimen (100 mm in diameter, 20 mm in thickness, and a coating dry film thickness of 3 ± 0.5 mm). A constant heat flux (0.5 W / cm2) was applied to the hot surface of the specimen in a constant temperature chamber (23 ± 2 °C). 2 By measuring the heat flux density (Q), the temperature difference between the two sides of the specimen (ΔT) and the thickness (d), the heat conduction capacity is calculated according to the formula "thermal conductivity coefficient λ = (Q×d) / (A×ΔT)".

[0055] The test results are shown in the following table:

[0056]

[0057] Comparison of the test results of Example 1 with Comparative Examples 1-5 shows that the present invention achieves a breakthrough in fire resistance and mechanical properties through multi-level synergy between components. Example 1 has a core advantage of a fire resistance limit of 180 minutes, while its fire resistance limit of Comparative Example 1 (missing TBPA) drops sharply to 120 minutes, revealing the key role of brominated flame retardant TBPA in carbon layer formation and free radical capture; while the fire resistance limit of Comparative Example 2 (missing PSNB) is 142 minutes, indicating that the organic polyborosilazane PSNB significantly improves the structural stability of the ceramic layer by generating a SiO2-B2O3 glassy network. When TBPA and PSNB work synergistically (such as in Example 1), the two contribute to the dual protection of initial carbon layer barrier and high-temperature ceramic reinforcement, and their synergistic effect increases the fire resistance limit by 27%-33% compared to a single flame retardant system.

[0058] In Example 1, the modification of nanosilica (using a KH-560 coupling agent) demonstrated a dual benefit: chemical bonding enhanced the interfacial adhesion between the coating and the substrate (7.2 MPa), while nanoscale dispersion hindered crack propagation, resulting in an impact strength of 7.5 kJ / m². In contrast, in Comparative Example 3 (unmodified nanoparticles), adhesion dropped to 6.8 MPa due to agglomeration, demonstrating the necessity of surface modification. Furthermore, the choice of epoxy resin type (e.g., F-51 was used in Example 5) and the phased addition of the curing agent DDS (initial 50%) optimized the crosslinking network density, further enhancing the coating's compactness and thermal stability, resulting in a fire resistance limit exceeding 205 minutes.

[0059] The synergistic mechanism among the components is demonstrated by the rapid carbonization of TBPA forming a porous initial barrier, the borosilicate glass phase of PSNB penetrating it to form a dense ceramic layer, nano-silica acting as a rigid filler to strengthen the interfacial bond, and the epoxy resin-curing agent system securing the spatial arrangement of the components through a three-dimensional network. This multi-stage protection system of "carbon layer buffering-ceramic reinforcement-nano-reinforcement" maintains the efficient thermal insulation properties of intumescent coatings while overcoming their brittleness, while retaining the high adhesion characteristics of non-intumescent coatings, resulting in a fire-retardant coating with excellent overall performance.

[0060] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A fire retardant industrial coating, characterized in that: The composition comprises, by mass, 40-50 parts of epoxy resin, 8-12 parts of tetrabromophthalic anhydride (TBPA), 15-20 parts of organic polyborosilazane (PSNB), 10-15 parts of pentaerythritol, 6-8 parts of melamine, 3-5 parts of modified nano-silica, 8-10 parts of epoxy curing agent DDS, and 3-4 parts of auxiliary agent.

2. The fire retardant industrial coating according to claim 1, characterized in that: The epoxy resin is one or more of bisphenol A epoxy resin E-51, bisphenol F epoxy resin F-44 or novolac epoxy resin F-51.

3. The fire retardant industrial coating according to claim 1, characterized in that The auxiliary agents include 0.5-1.0 parts of dispersant, 0.1-0.3 parts of defoaming agent, 0.5-1.0 parts of wetting agent, 1.0-1.5 parts of anti-settling agent and 0.5-1.0 parts of ultraviolet absorber.

4. The fire retardant industrial coating according to claim 2, characterized in that The dispersant is one or more of BYK-163, BYK-190 or EFKA-4010, the defoamer is one or more of BYK-052, Foamaster NXZ or Emultrol DFMAFO-1, the wetting agent is one or more of BYK-345, WSS-713 or Tego Wet 500, the anti-settling agent is one or more of DISPARLON 6900-20X or BENTONE 34, and the ultraviolet absorber is one or more of Tinuvin 292 or UV-360.

5. The method for preparing the fire-retardant industrial coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) After mixing epoxy resin and tetrabromophthalic anhydride (TBPA), stirring and reacting at high temperature to form a homogeneous system; (2) adding organopolyborosilazane (PSNB), pentaerythritol, and melamine to the homogenous system in sequence, and shearing and stirring to obtain a flame retardant base material; (3) After surface modification of the nano-silica, the nano-silica is added to the flame retardant base material in batches and shearing and stirring are continued; (4) premixing the epoxy curing agent DDS with the auxiliary agent and adding the mixture to the base material twice to adjust the viscosity of the system to obtain the curing agent; (5) The flame retardant base material and the curing agent are mixed evenly to obtain a finished coating.

6. The preparation method according to claim 5, characterized in that: In step (1), the high temperature is 80-100° C., the stirring time is 1-2 hours, and the stirring speed is 300-500 r / min.

7. The preparation method according to claim 5, characterized in that: In step (2), the shear stirring speed is 800-1000 r / min, the stirring time is 45-60 minutes, and the addition interval of PSNB, pentaerythritol and melamine is 5 minutes.

8. The preparation method according to claim 5, characterized in that: In step (3), the surface modification uses silane coupling agent KH-560, the addition amount of which is 3% of the mass of nano-SiO2. The modification process includes ultrasonic dispersion for 30 minutes (frequency 40kHz) and adding flame retardant base material three times (each time with an interval of 10 minutes).

9. The preparation method according to claim 5, characterized in that: In step (4), the diluent is C12-C14 glycidyl ether, the viscosity adjustment range is 900-1100 mPa·s, and when DDS is added in two times, the first addition amount is 50% of the total mass.

10. The preparation method according to claim 5, characterized in that: In step (5), the mixing temperature is 50° C., the stirring speed is 300 r / min, the mixing time is 20 minutes, and then the mixture is allowed to stand at 40° C. for 1 hour for degassing.

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