Research, development and application technology of polyurethane solid color primer for improving polishing effect

Abstract

The invention discloses a research and development and application technology of a polyurethane solid color primer capable of improving a polishing effect, and relates to the field of primer, and the research and development and application technology comprises the following specific steps: step 1, premixing and dispersing raw materials, step 2, grinding and dispersing at a high speed, step 3, adding an auxiliary agent and mixing paint, and step 4, compounding and filling a curing agent. The nano calcium carbonate is subjected to plasma-assisted polydimethylsiloxane coating, the surface energy is reduced from 32 mN / m to 18 mN / m, the particle size fluctuation of the ground filler is reduced from + / -15 nm to + / -3 nm, and the interface bonding strength is improved by 25%; the hydroxy acrylic resin, the short oil alkyd resin, the talcum powder and the nano calcium carbonate are automatically fed through the mass flow meter, so that the production efficiency is improved; and 2, high-speed grinding and dispersing: grinding the polyurethane prepolymer in the step 1, and performing staged grinding by adopting a basket type sand mill to realize nanoscale uniform dispersion and ensure the compactness of the paint film.

Description

Technical Field

[0001] The present invention relates to the field of primers, and in particular to a research and development and application technology of a polyurethane solid color primer with improved polishing effect. Background Art

[0002] As a crucial transition layer in a coating system, the sandability of a solid-color polyurethane primer directly impacts topcoat adhesion and the smoothness of the final coating. Traditional formulations often suffer from issues such as sandpaper clogging, sanding dusting, and coarse, deep sand marks. Furthermore, the production process requires precise addition of ingredients such as formulation additives, leading to demanding manufacturing processes. Furthermore, polyurethane is prone to secondary agglomeration during high-speed grinding, which, if not promptly addressed, can lead to poor primer preparation.

[0003] In summary, a research and development and application technology of polyurethane solid color primer with improved polishing effect is designed. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention provides a research and development and application technology of a polyurethane solid color primer with improved polishing effect.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions: The research and development of a polyurethane solid color primer with improved polishing effect includes the following specific steps: Step 1: Premixing and dispersing raw materials, including resin system configuration and filler pretreatment, to ensure resin compatibility and uniform dispersion of fillers, laying the foundation for subsequent grinding. The resin system configuration involves mixing hydroxyl acrylic resin with short-oil alkyd resin, utilizing the polarity difference between the two to achieve a balance between the cured cross-linking network and flexibility. The filler pretreatment involves plasma-assisted polydimethylsiloxane coating of talc and nano-calcium carbonate to reduce surface energy and enhance interfacial bonding with the resin. Step 2: Grind and disperse the polyurethane prepolymer prepared in step 1 at high speed. Grind the prepolymer in stages using a basket sand mill. In the initial grinding stage, the speed of the sand mill is 6000 rpm, and the grinding time is 30 minutes. The slurry fineness is controlled to 25 μm. In the fine grinding stage, the slurry fineness is controlled to ≤15 μm, achieving nano-level uniform dispersion and ensuring the density of the paint film. Step 3: Adding additives and mixing paint: Add rheological additives and curing catalysts to the grinding slurry in step 2 in sequence, and mature it at 25°C for 24 hours to complete the stretching of the molecular chains, regulate the rheological properties and curing rate of the paint, and ensure the construction tolerance; Step 4: Compounding and filling the curing agent: Mix the HDI trimer (NCO% 18-22%) prepared in step 3 with the hydroxyl component in an equivalent ratio of 1.1:1. Adjust the viscosity to 200-300 mPa·s at 25°C. Curing is carried out under nitrogen protection and finally packaged to ensure rapid crosslinking of the two components after mixing to avoid gelation during storage.

[0006] Preferably, in step 1, hydroxy acrylic resin, short oil alkyd resin, talc and nano calcium carbonate are automatically fed by a mass flow meter, the manual operation steps are reduced from 18 to 5, the ingredient error is reduced from ±3% to ±0.5%, and the batch stability is improved by 40%.

[0007] Preferably, in the step 1, the nano-calcium carbonate is subjected to plasma-assisted polydimethylsiloxane coating in a supercritical CO2 environment (pressure of 7.39 MPa, temperature of 31.1°C), the surface energy is reduced from 32 mN / m to 18 mN / m, the filler particle size fluctuation after grinding is reduced from ±15 nm to ±3 nm (DLS detection), and the interface bonding strength is increased by 25%.

[0008] Preferably, in step 2, ethyl orthosilicate is directly added to the polyurethane prepolymer (NCO content 12-15%), and a SiO2 network is generated in situ by a sol-gel method, thereby increasing the nano-dispersion uniformity from 72% to 95% and the impact strength from 65 kg·cm to 82 kg·cm.

[0009] Preferably, in the step three, 28kHz ultrasound is applied during the aging stage, and the energy density of the ultrasound is ≥50J / cm³. Micro-jets are used to break up soft agglomerates, the secondary agglomeration rate of nanoparticles is reduced by 60%, and the roughness Ra of the paint film is reduced from 3μm to 1.8μm.

[0010] Preferably, in step 4, a photoinitiator is added before curing, and the film is first pre-cured by UV for 10 seconds, followed by thermal curing at 60°C for 30 minutes. The surface drying time is shortened from 25 minutes to 8 minutes, making it suitable for high-speed coating on automated production lines.

[0011] A polyurethane solid color primer with improved polishing effect as described in any of the above items is used in automobile manufacturing, offshore wind power towers or drone shells.

[0012] The beneficial effects of the present invention are: in the research and development and application technology of the polyurethane solid color primer with improved polishing effect: 1. In a supercritical CO2 environment, plasma-assisted polydimethylsiloxane coating of nano-calcium carbonate was performed, and the surface energy was reduced from 32mN / m to 18mN / m. The particle size fluctuation of the filler after grinding was reduced from ±15nm to ±3nm, and the interface bonding strength was increased by 25%; 2. Automatically feed hydroxyl acrylic resin, short oil alkyd resin, talcum powder and nano calcium carbonate through mass flow meter, thus improving production efficiency; 3. Grind and disperse the polyurethane prepolymer in step 1 at high speed, using a basket sand mill to grind in stages to achieve nano-level uniform dispersion and ensure the density of the paint film; 4. Add rheological additives and curing catalysts to the grinding slurry in step 2, and mature it at 25°C for 24 hours to complete the stretching of the molecular chains, regulate the rheological properties and curing rate of the paint, and ensure the construction tolerance. 5. Photoinitiator is added before curing. It first undergoes UV pre-curing for 10 seconds, and then enters thermal curing at 60°C for 30 minutes. The surface drying time is shortened from 25 minutes to 8 minutes, making it suitable for high-speed coating on automated assembly lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 It is a step diagram of the present invention. DETAILED DESCRIPTION

[0014] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0015] like Figure 1 As shown, the development of a polyurethane solid color primer with improved polishing effect includes the following specific steps: Step 1: Premixing and dispersing raw materials, including resin system configuration and filler pretreatment, to ensure resin compatibility and uniform dispersion of fillers, laying the foundation for subsequent grinding. The resin system configuration involves mixing hydroxyl acrylic resin with short-oil alkyd resin, utilizing the polarity difference between the two to achieve a balance between the cured cross-linking network and flexibility. The filler pretreatment involves plasma-assisted polydimethylsiloxane coating of talc and nano-calcium carbonate to reduce surface energy and enhance interfacial bonding with the resin. In step 1, hydroxylated acrylic resin, short-oil alkyd resin, talc, and nano-calcium carbonate are automatically fed via a mass flow meter, reducing the number of manual steps from 18 to 5, reducing the batching error from ±3% to ±0.5%, and improving batch stability by 40%. In step 1, nano-calcium carbonate was coated with plasma-assisted polydimethylsiloxane in a supercritical CO2 environment (pressure of 7.39 MPa and temperature of 31.1°C). The surface energy was reduced from 32 mN / m to 18 mN / m, and the particle size fluctuation after grinding was reduced from ±15 nm to ±3 nm (DLS measurement). The interfacial bonding strength was increased by 25%. Step 2: Grind and disperse the polyurethane prepolymer prepared in step 1 at high speed. Grind the prepolymer in stages using a basket sand mill. In the initial grinding stage, the speed of the sand mill is 6000 rpm, and the grinding time is 30 minutes. The slurry fineness is controlled to 25 μm. In the fine grinding stage, the slurry fineness is controlled to ≤15 μm, achieving nano-level uniform dispersion and ensuring the density of the paint film. In step 2, ethyl orthosilicate was directly added to the polyurethane prepolymer (NCO content 12-15%) to generate an in-situ SiO2 network via a sol-gel method. The nano-dispersion uniformity was increased from 72% to 95%, and the impact strength was increased from 65kg·cm to 82kg·cm. Step 3: Adding additives and mixing paint: Add rheological additives and curing catalysts to the grinding slurry in step 2 in sequence, and mature it at 25°C for 24 hours to complete the stretching of the molecular chains, regulate the rheological properties and curing rate of the paint, and ensure the construction tolerance; In step 3, 28kHz ultrasound is applied during the curing stage with an energy density of ≥50J / cm³. Micro-jet is used to break up soft agglomerates, reducing the secondary agglomeration rate of nanoparticles by 60% and the paint film roughness Ra from 3μm to 1.8μm. Step 4: Compounding and filling the curing agent: Mix the HDI trimer (NCO% 18-22%) prepared in step 3 with the hydroxyl component in an equivalent ratio of 1.1:1. Adjust the viscosity to 200-300 mPa·s at 25°C. Curing is carried out under nitrogen protection and finally packaged to ensure rapid crosslinking of the two components after mixing to avoid gelation during storage. In step 4, a photoinitiator is added before curing. First, it undergoes UV pre-curing for 10 seconds, and then enters thermal curing at a temperature of 60°C for 30 minutes. The surface drying time is shortened from 25 minutes to 8 minutes, making it suitable for high-speed coating on automated assembly lines. Specific embodiment one:

[0016] Automobile manufacturing field: new energy vehicle battery shell coating 1. Preparation plan and optimization technology Step 1 (raw material premixing and dispersion): Hydroxylated acrylic resin (hydroxyl value 125mgKOH / g) and short-oil alkyd resin (fluorine content 8%) are compounded in a ratio of 6:4 to balance rigidity and toughness through polarity differences.

[0017] Nano-calcium carbonate coated with PDMS (surface energy 18 mN / m) via supercritical CO2 plasma increased interfacial bonding strength by 25%. The mass flow meter feeding error was reduced from ±3% to ±0.5%, and batch stability was improved by 40%.

[0018] Step 4 (curing agent compounding): UV pre-curing (time is 10s) + 60℃ thermal curing, the surface drying time is shortened from 25min to 8min, suitable for 12m / min production line speed.

[0019] 2. Performance improvement data comparison Performance indicators Traditional primer Optimized primer Improvement 40% KOH corrosion resistance time No abnormality within 72 hours 500h no abnormality +594% Stone impact resistance (5J impact) Level 3 (slight shedding) Level 0 (no damage) Fully meet the standards Adhesion after salt spray 3.8MPa 5.6MPa +47% Painting line speed 8m / min 12m / min +50% Specific embodiment two:

[0020] Offshore wind turbine tower protection: 16MW offshore wind turbine project 1. Preparation plan and optimization technology Step 2 (high-speed grinding and dispersion): In-situ generation of a SiO2 network (3% addition of ethyl orthosilicate) increased impact strength from 65 kg·cm to 82 kg·cm. The friction coefficient of a graphene / boron nitride composite filler (5% addition) was reduced to 0.15.

[0021] Step 4 (curing process): Light-heat dual curing shortens the recoating interval from 72h to 4h, adapting to the intertidal zone construction window.

[0022] 2. Performance improvement data comparison Performance indicators Traditional epoxy system Optimizing polyurethane systems Improvement 5-year gloss retention (ISO 2813) 68% 89% +31% Resistance to cyclic corrosion cycles (ISO 20340) 15 cycles 25 cycles +67% Single tower painting working hours 120h 78h -35% Maintenance cycle 3 years 8 years +167% Specific embodiment three:

[0023] Drone Shell Painting: DJI Inspire 4 Industrial-Grade Drone 1. Preparation plan and optimization technology Step 3 (addition of additives and paint mixing): 28kHz ultrasonic treatment (energy density 55J / cm³) reduced the secondary aggregation rate of nanoparticles by 60% and the roughness Ra from 3μm to 1.8μm. The flexible curing agent (Tg = -40°C) passed the -30°C cold shock test.

[0024] In step 1 (filler structure), flaky mica powder (diameter-to-thickness ratio 50:1) is compounded with nano-CaCO3, and the polishing efficiency is 22.5 g / min when the film thickness is 45 μm.

[0025] 2. Performance improvement data comparison Performance indicators Competitor A DJI Custom Formula Improvement Film thickness / weight ratio (μm / kg) 60 / 0.48 45 / 0.32 -25% / -33% Drop resistance height (GB / T 2423) 3J qualified 8J no damage +167% Low temperature flexibility (-30℃) Cracking No abnormalities Completely resolved VOC emissions 350g / L 250g / L -29% In summary, the application of the polyurethane solid color primer with improved polishing effect is summarized as follows: Technology Module Automobile Manufacturing Offshore wind power drone shell Common improvement directions Surface energy regulation PDMS coating enhances chemical corrosion resistance Graphene reduces friction coefficient Mica powder optimization and lightweighting Interface bonding strength increased by 20-25% Curing efficiency Light-heat curing shortens surface drying time Shorten the recoating interval to 4 hours Low temperature toughness adapts to extreme environments Production efficiency increased by 30-50% Dispersion uniformity <![CDATA[SiO2 network anti-permeation]]> In-situ generation of corrosion-resistant structures Ultrasonic treatment to reduce roughness Nano-dispersion uniformity> 95% Environmental protection Reduce VOC by 18% Extend maintenance cycles and reduce paint consumption 30% replacement of bio-based raw materials Reduce carbon footprint across all sectors by 20-40% Through precise resin system design, nano-scale filler dispersion and intelligent curing process, this polyurethane solid color primer has achieved comprehensive improvements in wear resistance, corrosion resistance, construction efficiency and environmental protection in the fields of automobiles, wind power and drones.

[0026] The above is based on the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical idea of ​​this invention.

Claims

1. Research and development of a polyurethane solid color primer with improved polishing effect, characterized by: The specific steps include: Step 1: Premixing and dispersing raw materials, including resin system configuration and filler pretreatment, to ensure resin compatibility and uniform dispersion of fillers. The resin system configuration is to mix hydroxy acrylic resin with short oil alkyd resin, and the filler pretreatment is to coat talc powder and nano calcium carbonate with plasma-assisted polydimethylsiloxane. Step 2: Grinding and dispersing at high speed: Grind the polyurethane prepolymer prepared in step 1 in stages using a basket sand mill. In the initial grinding stage, the sand mill speed is 6000 rpm, the grinding time is 30 minutes, and the slurry fineness is controlled to 25 μm. In the fine grinding stage, the slurry fineness is controlled to ≤15 μm. Step 3: Adding additives and mixing paint: add rheological additives and curing catalysts to the grinding slurry in step 2 in sequence, and mature at 25°C for 24 hours; Step 4: Compounding and filling the curing agent: Mix the HDI trimer (NCO% 18-22%) prepared in step 3 with the hydroxyl component in an equivalent ratio of 1.1:

1. Adjust the viscosity to 200-300 mPa·s at 25°C, cure under nitrogen protection, and finally package.

2. The research and development of the polyurethane solid color primer with improved polishing effect according to claim 1, characterized in that: In the step 1, the hydroxy acrylic resin, the short oil alkyd resin, the talc powder and the nano calcium carbonate are automatically fed through a mass flow meter.

3. The research and development of the polyurethane solid color primer with improved polishing effect according to claim 1, characterized in that: In the step 1, the nano-calcium carbonate is subjected to plasma-assisted polydimethylsiloxane coating in a supercritical CO2 environment (pressure of 7.39 MPa, temperature of 31.1°C).

4. The research and development of the polyurethane solid color primer with improved polishing effect according to claim 1, characterized in that: In the second step, ethyl orthosilicate is directly added to the polyurethane prepolymer (NCO content 12-15%) to generate a SiO2 network in situ through a sol-gel method.

5. The research and development of the polyurethane solid color primer with improved polishing effect according to claim 1, characterized in that: In the step 3, 28kHz ultrasonic waves are applied during the aging stage, and the energy density of the ultrasonic waves is ≥50J / cm³.

6. The research and development of the polyurethane solid color primer with improved polishing effect according to claim 1, characterized in that: In the step 4, a photoinitiator is added before curing, and the film is first pre-cured by UV for 10 seconds, and then thermally cured at 60° C. for 30 minutes.

7. A polyurethane solid color primer with improved polishing effect according to any one of claims 1 to 6, characterized in that: Used in automobile manufacturing, offshore wind power towers or drone casings.

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