Polyurethane modified coating as well as preparation method and application thereof

Abstract

The invention discloses a polyurethane modified coating and a preparation method and application thereof, and belongs to the technical field of cable trench cover plate coating manufacturing, the polyurethane modified coating comprises a component A and a component B. The volume ratio of the component A to the component B is 1: (0.9-1.1), the component A comprises, by mass, 20-30 parts of polyether amine and 10-20 parts of an amine curing agent, and the component B comprises, by mass, 20-30 parts of polyether amine and 10-20 parts of an amine curing agent; 1-1.5 parts of SiO nanoparticles, 5-7 parts of a phosphorus-nitrogen flame retardant, 0.5-3 parts of a dispersing agent, 3-5 parts of silicon carbide aggregate and 1-2 parts of a fluorinated silane coupling agent; the component B is prepared from the following components in parts by mass: 15 to 20 parts of diphenylmethane diisocyanate, 10 to 20 parts of polyether polyol and 3 to 10 parts of polymethylene polyphenyl polyisocyanate. A large amount of impact energy can be dissipated through rapid stretching, twisting and friction, penetration and tearing are resisted through hardening of the coating, and the high-weather-resistance explosion-proof cable has the advantages of being high in weather resistance, high in explosion-proof performance and excellent in bearing capacity.

Description

Technical Field

[0001] This invention relates to a polyurethane modified coating, its preparation method and application, belonging to the technical field of cable trench cover coating. Background Technology

[0002] Cable trench covers are crucial components used in power, telecommunications, and municipal engineering projects to cover cable trenches. Their main functions are to protect cable lines, facilitate maintenance, maintain road access, and bear a certain load. Existing cable trench covers mostly use traditional concrete or metal materials, which have the following drawbacks: 1. Insufficient blast resistance: Traditional epoxy coatings are brittle (elongation at break <5%), easily cracking under explosive impact (1kg TNT@10m fragmentation rate 100%); polyurea coatings, while flexible, have low hardness (Shore A 80-90) and weak penetration resistance (projectile penetration depth ≥15mm). 2. Lack of load-bearing capacity: A single coating cannot improve the load-bearing capacity of the substrate (concrete cover deflection >5mm under 35kPa load); weak adhesion to metal substrates (adhesion ≤5MPa), leading to peeling under long-term load. 3. Poor weather resistance: intensity decreases by more than 30% after 720 hours of UV aging (GB / T 23987-2009); oil penetration causes expansion (volume change > 5%). Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a polyurethane modified coating, its preparation method and application, which can dissipate a large amount of impact energy through rapid stretching, torsion and friction, and use the coating hardening to resist penetration and tearing, and has the advantages of high weather resistance, high explosion-proof performance and excellent load-bearing capacity.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, the present invention discloses a polyurethane modified coating, comprising component A and component B, wherein the volume ratio of component A to component B is 1:0.9~1.1. Component A, by mass, comprises 20~30 parts of polyether amine, 10~20 parts of amine curing agent, 1~1.5 parts of SiO2 nanoparticles, 5~7 parts of phosphorus-nitrogen flame retardant, 0.5~3 parts of dispersant, 3~5 parts of silicon carbide aggregate, and 1~2 parts of fluorinated silane coupling agent. Component B, by mass, comprises 15~20 parts of diphenylmethane diisocyanate, 10~20 parts of polyether polyol, and 3~10 parts of polymethylene polyphenyl polyisocyanate.

[0006] Secondly, this invention discloses a method for preparing a polyurethane modified coating, comprising the following steps:

[0007] By weight, 20-30 parts of polyetheramine, 10-20 parts of amine curing agent, 1-1.5 parts of SiO2 nanoparticles, 5-7 parts of phosphorus-nitrogen flame retardant, 0.5-3 parts of dispersant, 3-5 parts of silicon carbide aggregate and 1-2 parts of fluorinated silane coupling agent are mixed and dispersed at high speed to obtain component A;

[0008] By mass, 15-20 parts of diphenylmethane diisocyanate and 10-20 parts of polyether polyol were stirred and reacted under nitrogen protection, and then 3-10 parts of polymethylene polyphenyl polyisocyanate were added. After maintaining the temperature for a period of time, component B was obtained.

[0009] Component A and component B are mixed at a volume ratio of 1:0.9~1.1 to obtain a polyurethane modified coating.

[0010] The high-speed dispersion temperature is 20~30℃, the stirring speed is 2000rpm, and the stirring time is 60min.

[0011] After high-speed dispersion, the fineness is ≤20μm.

[0012] The stirring speed was 120 r / min, the stirring temperature was 75℃, and the stirring time was 2 h.

[0013] The temperature was kept constant at 75℃ for 1 hour.

[0014] Thirdly, this invention discloses an application of a polyurethane modified coating, wherein the polyurethane modified coating is sprayed onto the surface of a cable trench cover substrate and cured at room temperature to form a polyurethane modified coating.

[0015] Spraying pressure ≥2000psi, room temperature curing time 7d, polyurethane modified coating thickness 1.0mm, surface drying ≤15s, adhesion ≥9Mpa, deflection ≤2mm under 35kPa load.

[0016] The beneficial effects of this invention are as follows: This invention provides a polyurethane modified coating, its preparation method, and its application, comprising component A and component B. Component A includes SiO2 nanoparticles and silicon carbide aggregate, while component B includes diphenylmethane diisocyanate and polyether polyol. By block copolymerizing the hard segment microcrystalline region (diphenylmethane diisocyanate) with the soft segment high elasticity (polyether polyol), a high strain rate sensitive response (strain rate sensitivity index β=0.38) is achieved through the hard segment microcrystalline region, resolving the contradiction between explosion resistance and flexibility. The high elasticity of the soft segment improves tensile energy absorption (elongation at break > 200%). Furthermore, the addition of SiO2 nanoparticles (KIC=4.2 MPa·m¹ / ²) inhibits cracking, achieving nano-interface anchoring, and the silicon carbide aggregate achieves aggregate stress dispersion. Through the above-mentioned "high strain rate sensitive response molecular design + nano-interface anchoring +..." The combined effect of aggregate stress dispersion can dissipate a large amount of impact energy through rapid stretching, torsion and friction. The coating hardens to resist penetration and tearing, and has the advantages of high weather resistance, high explosion-proof performance and excellent load-bearing capacity. Attached Figure Description

[0017] Figure 1 This is a TEM image of the polyurethane modified coating in this invention;

[0018] Figure 2 This is a SEM image of the polyurethane modified coating in this invention;

[0019] Figure 3 This is a graph of the wall pressure signal in the explosion-proof test of this invention. Detailed Implementation

[0020] The present invention will be further described below. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0021] Example 1

[0022] This invention discloses a polyurethane modified coating, comprising component A and component B, wherein the volume ratio of component A to component B is 1:1. By mass, component A comprises 25 parts of polyether amine, 20 parts of amine curing agent, 1 part of SiO2 nanoparticles, 7 parts of phosphorus-nitrogen flame retardant, 1 part of dispersant, 3 parts of silicon carbide aggregate, and 1 part of fluorinated silane coupling agent. By mass, component B comprises 18 parts of diphenylmethane diisocyanate (MDI), 13 parts of polyether polyol, and 8 parts of polymethylene polyphenyl polyisocyanate (crude MDI). In this invention, the amine curing agent is diethyltoluenediamine or dimethylthiotoluenediamine, and the dispersant is an alkylammonium salt solution of a polycarboxylic acid or an aqueous solution of a polyether-modified styrene-maleic anhydride copolymer.

[0023] Table 1 Functions of each component in polyurethane modified coatings

[0024]

[0025] This invention also discloses a method for preparing a polyurethane modified coating, comprising the following steps:

[0026] Step 1: By weight, 25 parts of polyetheramine, 20 parts of amine curing agent, 1 part of SiO2 nanoparticles, 7 parts of phosphorus-nitrogen flame retardant, 1 part of dispersant, 3 parts of silicon carbide aggregate, and 1 part of fluorinated silane coupling agent are mixed and then dispersed at high speed to obtain component A. The high-speed dispersion temperature is 20~30℃, the stirring rate is 2000rpm, the stirring time is 60min, and the fineness after high-speed dispersion is ≤20μm (GB / T 1724-2019).

[0027] Step 2: By weight, 18 parts of diphenylmethane diisocyanate, 13 parts of polyether polyol, and 8 parts of polymethylene polyphenyl polyisocyanate were stirred and reacted under nitrogen protection. Then, 3-10 parts of polymethylene polyphenyl polyisocyanate were added, and the mixture was kept at a constant temperature for a period of time to obtain component B. The stirring speed was 120 r / min, the stirring temperature was 75℃, and the stirring time was 2 h. The constant temperature was maintained at 75℃ for 1 h, and the NCO content was 16 ± 0.5%.

[0028] Step 3: Mix component A and component B at a volume ratio of 1:1 to obtain a polyurethane modified coating.

[0029] This invention discloses the application of a polyurethane modified coating, which is sprayed onto the surface of a cable trench cover substrate (this invention requires one coat, while traditional coatings require three coats). The cable trench cover is made of fiberglass composite material, and the polyurethane modified coating is formed after room temperature curing. The spraying pressure is ≥2000psi, the room temperature curing time is 7 days, the thickness of the polyurethane modified coating is 1.0mm, the surface drying time is ≤15s, the adhesion is ≥9MPa (pull-off test), and the deflection under a 35kPa load is ≤2mm.

[0030] The polyurethane-modified coating of this invention was subjected to Hopkinson bar testing (strain rate 1000 s⁻¹): the dynamic yield strength of this coating was 185 MPa, and the energy absorption rate was 35.2 J / cm³; the dynamic yield strength of conventional polyurea was 92 MPa, and the energy absorption rate was 18.7 J / cm³. Furthermore, the polyurethane-modified coating of this invention was subjected to an explosion test (GJB 150.18-2009), and the wall pressure signal curve of the explosion test is shown below. Figure 3 As shown: 12kg TNT@2m without penetration, substrate without cracks (ordinary coating substrate is broken).

[0031] This invention achieves a strain rate sensitivity index β=0.38 through block copolymerization of hard segment microcrystalline region (MDI) and soft segment highly elastic (polyether polyol): thus resolving the contradiction between explosion resistance and flexibility. Figure 1 As shown, the coating interface information indicates that the hard segment microcrystalline region size is 50~100nm. The high elasticity of the soft segment improves tensile energy absorption (elongation at break > 200%), and the addition of SiO2 nanoparticles inhibits fracture cracking (KIC = 4.2 MPa·m¹ / ²), achieving nano-interface anchoring and enhancing interfacial bonding. Figure 2 As shown, nanoparticles anchor the pores of the substrate, and carbon nanotube nanomaterials, corresponding to the nanomaterials in the table, fill the coating-substrate interface to form a mechanical interlock. Adhesion (9.2 MPa) ≥ 9 MPa (GB / T 5210-2006) and oleophobicity (contact angle 115°) are achieved, reducing oil penetration by 98%. Silicon carbide aggregates achieve stress dispersion, forming microscopic support points that distribute concentrated loads into surface loads (substrate deflection ≤ 2 mm at 35 kPa).

[0032] This invention achieves high blast resistance (withstanding the impact of a 12kg TNT explosion at 2.2m, a 500% improvement over traditional coatings) through the combined effects of "high strain rate sensitive response molecular design + nano-interface anchoring + aggregate stress dispersion"; excellent load-bearing capacity (substrate deflection ≤2mm under 35kPa load, a 60% improvement); and high durability (15 years maintenance-free (salt spray life >5000h)). It can be applied to explosion-proof areas of substations, cable trenches in high-salt and high-humidity areas, and heavy-duty chemical passages.

[0033] Example 2

[0034] This embodiment is the same as Embodiment 1, except that the volume ratio of component A to component B is 1:1. By mass, component A includes 20 parts of polyether amine, 15 parts of amine curing agent, 1 part of SiO2 nanoparticles, 5 parts of phosphorus-nitrogen flame retardant, 3 parts of dispersant, 4 parts of silicon carbide aggregate, and 1 part of fluorinated silane coupling agent. By mass, component B includes 15 parts of diphenylmethane diisocyanate (MDI), 10 parts of polyether polyol, and 10 parts of polymethylene polyphenyl polyisocyanate (crude MDI).

[0035] Example 3

[0036] This embodiment is the same as Embodiment 1, except that the volume ratio of component A to component B is 1:1. By mass, component A includes 30 parts of polyether amine, 10 parts of amine curing agent, 1.5 parts of SiO2 nanoparticles, 6 parts of phosphorus-nitrogen flame retardant, 0.5 parts of dispersant, 5 parts of silicon carbide aggregate, and 2 parts of fluorinated silane coupling agent. By mass, component B includes 20 parts of diphenylmethane diisocyanate (MDI), 20 parts of polyether polyol, and 3 parts of polymethylene polyphenyl polyisocyanate (crude MDI).

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A polyurethane-modified coating, characterized in that: The product comprises component A and component B, wherein the volume ratio of component A to component B is 1:0.9~1.

1. Component A, by mass, comprises 20~30 parts of polyetheramine, 10~20 parts of amine curing agent, 1~1.5 parts of SiO2 nanoparticles, 5~7 parts of phosphorus-nitrogen flame retardant, 0.5~3 parts of dispersant, 3~5 parts of silicon carbide aggregate, and 1~2 parts of fluorinated silane coupling agent. By weight, component B comprises 15-20 parts of diphenylmethane diisocyanate, 10-20 parts of polyether polyol, and 3-10 parts of polymethylene polyphenyl polyisocyanate.

2. A method for preparing a polyurethane modified coating, characterized in that: Includes the following steps: By weight, 20-30 parts of polyetheramine, 10-20 parts of amine curing agent, 1-1.5 parts of SiO2 nanoparticles, 5-7 parts of phosphorus-nitrogen flame retardant, 0.5-3 parts of dispersant, 3-5 parts of silicon carbide aggregate and 1-2 parts of fluorinated silane coupling agent are mixed and dispersed at high speed to obtain component A; By mass, 15-20 parts of diphenylmethane diisocyanate and 10-20 parts of polyether polyol were stirred and reacted under nitrogen protection, and then 3-10 parts of polymethylene polyphenyl polyisocyanate were added. After maintaining the temperature for a period of time, component B was obtained. Component A and component B are mixed at a volume ratio of 1:0.9~1.1 to obtain a polyurethane modified coating.

3. The method for preparing the polyurethane modified coating according to claim 2, characterized in that: The high-speed dispersion temperature is 20~30℃, the stirring speed is 2000rpm, and the stirring time is 60min.

4. The method for preparing the polyurethane modified coating according to claim 3, characterized in that: After high-speed dispersion, the fineness is ≤20μm.

5. The method for preparing polyurethane modified coating according to claim 2, characterized in that: The stirring speed was 120 r / min, the stirring temperature was 75℃, and the stirring time was 2 h.

6. The method for preparing the polyurethane modified coating according to claim 2, characterized in that: The temperature was kept constant at 75℃ for 1 hour.

7. An application of a polyurethane modified coating, characterized in that: The polyurethane modified coating of claim 1 is sprayed onto the surface of the cable trench cover substrate and cured at room temperature to form a polyurethane modified coating.

8. The application of the polyurethane modified coating according to claim 7, characterized in that: Spraying pressure ≥2000psi, room temperature curing time 7d, polyurethane modified coating thickness 1.0mm, surface drying ≤15s, adhesion ≥9Mpa, deflection ≤2mm under 35kPa load.

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