Development and application technology of polyurethane solid primer for improving polishing effect

Abstract

The application discloses a kind of development and application technology of polyurethane solid color primer for improving polishing effect, it is related to primer field, including the following specific steps: step one, raw material premixing and dispersing, step two, high-speed grinding dispersion, step three, additive addition and paint adjustment, step four, curing agent compounding and filling, in the application, in supercritical CO2 Environment, plasma assisted polydimethylsiloxane is coated to nano calcium carbonate, surface energy is reduced from 32mN / m to 18mN / m, filler particle size fluctuation is reduced from ±15nm to ±3nm after grinding, interface bonding strength is increased by 25%; by mass flow meter automatic feeding hydroxyl acrylic resin, short oil alkyd resin, talcum powder and nano calcium carbonate, production efficiency is improved;High-speed grinding dispersion, the polyurethane prepolymer of step one is ground, stage grinding is carried out using basket sand mill, realize nanoscale uniform dispersion, ensure film density.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of primer, in particular to a kind of development and application technology of polyurethane solid primer for improving polishing effect. BACKGROUND

[0002] As an important transition layer of coating system, the polishing performance of polyurethane solid primer directly affects the adhesion of topcoat and the final film flatness. Traditional formula often has problems such as sandpaper blockage, polishing powder, and deep sand marks. Moreover, during the production of primer, the raw materials such as formula additives in the primer need to be accurately added, which leads to high process requirements. Furthermore, polyurethane is prone to secondary agglomeration during high-speed grinding, which leads to poor primer preparation effect if not handled in time.

[0003] In view of the above, a kind of development and application technology of polyurethane solid primer for improving polishing effect is designed. SUMMARY

[0004] In order to overcome the above-mentioned shortcomings, a kind of development and application technology of polyurethane solid primer for improving polishing effect is provided.

[0005] The present application realizes the above-mentioned purpose through the following technical solutions:

[0006] A kind of development of polyurethane solid primer for improving polishing effect, comprising the following specific steps:

[0007] Step one, raw material premixing and dispersing, including resin system configuration and filler pretreatment, to ensure resin compatibility and uniform dispersion of fillers, laying a foundation for subsequent grinding,

[0008] Among them, the resin system configuration is to mix hydroxy acrylate resin and short oil length alkyd resin, to balance the curing crosslinking network and flexibility by using the polarity difference of the two, and the filler pretreatment is to coat the talc and nano calcium carbonate with plasma assisted polydimethylsiloxane, to reduce the surface energy and improve the interface bonding with the resin;

[0009] Step two, high-speed grinding and dispersing, grinding the polyurethane prepolymer of step one, using basket sand mill for stage grinding, in the initial grinding stage, the speed of sand mill is 6000rpm, and the grinding time is 30min, the slurry fineness is controlled to 25μm, in the fine grinding stage, the slurry fineness is refined to ≤15μm, to realize nano-level uniform dispersion and ensure film density;

[0010] Step three, additive addition and paint conditioning, in the grinding slurry of step two, rheological additives and curing catalysts are added in turn, and aging is carried out at a temperature of 25℃ for 24h, to complete molecular chain stretching, control paint rheological properties and curing rate, and ensure construction tolerance.

[0011] Step four, curing agent compounding and filling, the HDI trimer (NCO 18-22%) prepared in step three is mixed with the hydroxyl component at an equivalent ratio of 1.1:1, the viscosity is adjusted to 200-300 mPa·s at a temperature of 25 DEG C, and the final packaging is carried out under a nitrogen protection environment, so as to ensure that the two components are quickly crosslinked after mixing and to avoid gelation during storage.

[0012] As preferred, in step one, the hydroxyl acrylic resin, short oil alkyd resin, talcum powder and nano calcium carbonate are automatically fed by a mass flow meter, the manual operation is reduced from 18 steps to 5 steps, the batching error is reduced from ±3% to ±0.5%, and the batch stability is improved by 40%.

[0013] As preferred, in step one, the nano calcium carbonate is coated with polydimethylsiloxane in a supercritical CO2 environment (pressure 7.39 MPa, temperature 31.1 DEG C), the surface energy is reduced from 32 mN / m to 18 mN / m, the particle size fluctuation of the filler after grinding is reduced from ±15 nm to ±3 nm (DLS detection), and the interfacial bonding strength is improved by 25%.

[0014] As preferred, in step two, tetraethyl orthosilicate is directly added to the polyurethane prepolymer (NCO content 12-15%), and SiO2 network is generated in situ by sol-gel method, the nano dispersion uniformity is improved from 72% to 95%, and the impact strength is increased from 65 kg·cm to 82 kg·cm.

[0015] As preferred, in step three, 28 kHz ultrasonic waves are applied during the maturation stage, the energy density of the ultrasonic waves is ≥50 J / cm³, the soft agglomerates are broken by micro-jets, the secondary agglomeration rate of the nanoparticles is reduced by 60%, and the film roughness Ra is reduced from 3 μm to 1.8 μm.

[0016] As preferred, in step four, a photoinitiator is added before curing, the coating is first pre-cured by UV for 10 seconds, and then is heat-cured at a temperature of 60 DEG C for 30 minutes, so that the surface dry time is shortened from 25 min to 8 min, and the coating is suitable for high-speed coating in an automatic assembly line.

[0017] A polyurethane solid color primer for improving polishing effect according to any one of the above, which is applied to automobile manufacturing, offshore wind tower or unmanned aerial vehicle shell.

[0018] The polyurethane solid color primer for improving polishing effect has the following advantages in the research and application technology:

[0019] 1. In a supercritical CO2 environment, plasma-assisted polydimethylsiloxane coating of nano-calcium carbonate reduced the surface energy from 32 mN / m to 18 mN / m, and after grinding, the filler particle size fluctuation decreased from ±15 nm to ±3 nm, while the interfacial bonding strength was improved by 25%.

[0020] 2. Automatic feeding of hydroxyl acrylic resin, short-oil alkyd resin, talc powder and nano calcium carbonate by mass flow meter improves production efficiency;

[0021] 3. High-speed grinding and dispersion: The polyurethane prepolymer from step one is ground in stages using a basket mill to achieve uniform dispersion at the nanoscale and ensure the density of the paint film.

[0022] 4. In the grinding slurry of step two, add rheology modifier and curing catalyst in sequence, and cure at 25°C for 24 hours to complete the molecular chain expansion, regulate the rheological properties and curing rate of the paint, and ensure the tolerance of construction.

[0023] 5. A photoinitiator is added before curing. It first undergoes UV pre-curing for 10 seconds, followed by heat curing at 60℃ for 30 minutes. The surface drying time is reduced from 25 minutes to 8 minutes, making it suitable for high-speed coating on automated production lines. Attached Figure Description

[0024] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0025] Figure 1 This is a flowchart illustrating the steps of the present invention. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0027] like Figure 1 As shown, the development of a polyurethane solid color primer to improve sanding effect includes the following specific steps:

[0028] Step 1: Raw material premixing and dispersion, including resin system preparation and filler pretreatment, to ensure resin compatibility and uniform filler dispersion, laying the foundation for subsequent grinding.

[0029] 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 crosslinking network and flexibility. The filler pretreatment involves plasma-assisted polydimethylsiloxane coating of talc powder and nano-calcium carbonate to reduce surface energy and enhance interfacial bonding with the resin.

[0030] In step one, the hydroxy acrylic resin, short oil alkyd resin, talcum powder and nano calcium carbonate are automatically fed by mass flow meter, the manual operation is reduced from 18 steps to 5 steps, the batching error is reduced from ±3% to ±0.5%, and the batch stability is improved by 40%;

[0031] In step one, in the supercritical CO2 environment (pressure 7.39 MPa, temperature 31.1℃), the nano calcium carbonate is coated with plasma assisted polydimethylsiloxane, the surface energy is reduced from 32 mN / m to 18 mN / m, the particle size fluctuation of the filler after grinding is reduced from ±15 nm to ±3 nm (DLS detection), and the interfacial bonding strength is improved by 25%;

[0032] In step two, high-speed grinding dispersion is carried out on the polyurethane prepolymer of step one, and the basket sand mill is used for staged grinding. In the initial grinding stage, the speed of the sand mill is 6000 rpm, and the grinding time is 30 min. The slurry fineness is controlled to 25 μm. In the fine grinding stage, the slurry fineness is refined to ≤15 μm, realizing nano-level uniform dispersion and ensuring the compactness of the paint film;

[0033] In step two, tetraethyl orthosilicate is directly added to the polyurethane prepolymer (NCO content 12-15%), and SiO2 network is generated in situ by sol-gel method. The nano dispersion uniformity is improved from 72% to 95%, and the impact strength is increased from 65 kg·cm to 82 kg·cm;

[0034] In step three, additives are added and the paint is adjusted. In the grinding slurry of step two, rheological additives and curing catalysts are added in sequence, and aging is carried out at 25℃ for 24 h to complete molecular chain stretching, control the rheological properties and curing rate of the paint, and ensure the construction tolerance;

[0035] In step three, 28 kHz ultrasonic waves are applied during the aging stage, with an energy density ≥50 J / cm³. The soft agglomerates are broken by micro-jets, the secondary agglomeration rate of nanoparticles is reduced by 60%, and the paint film roughness Ra is reduced from 3 μm to 1.8 μm;

[0036] In step four, the HDI trimer (NCO% 18-22%) prepared in step three is mixed with the hydroxyl component in an equivalent ratio of 1.1:1, the viscosity is adjusted to 200-300 mPa·s at 25℃, and the final packaging is carried out under nitrogen protection to ensure rapid crosslinking after mixing of the two components and avoid gelation during storage;

[0037] In step four, a photoinitiator is added before curing. First, UV pre-curing is carried out for 10 seconds, and then thermal curing is carried out at 60℃ for 30 minutes. The surface drying time is shortened from 25 min to 8 min, which is suitable for high-speed coating on automatic assembly line. Embodiment One:

[0038] Automobile manufacturing field: new energy vehicle battery shell coating

[0039] 1. Preparation scheme and optimization technology

[0040] Step one (raw material premixing and dispersion):

[0041] Hydroxy acrylic resin (hydroxyl value 125 mgKOH / g) and short oil alkyd resin (fluorine content 8%) are compounded at a ratio of 6:4 to balance rigidity and toughness through polarity difference.

[0042] Nano calcium carbonate is coated with PDMS (surface energy 18 mN / m) by supercritical CO2 plasma, and the interfacial bonding strength is increased by 25%. The mass flow meter feeding error is reduced from ±3% to ±0.5%, and the batch stability is increased by 40%.

[0043] Step four (curing agent compounding):

[0044] UV pre-curing (time 10s) + 60°C thermal curing, the surface drying time is shortened from 25min to 8min, and it is suitable for 12m / min assembly line speed.

[0045] 2. Performance improvement data comparison

[0046] Performance index Traditional primer Optimized primer Improvement range Resistance to 40% KOH corrosion time 72h no abnormality 500h no abnormality +594% Stone chip resistance (5J impact) 3 levels (light peeling) 0 level (no damage) Fully qualified Salt spray adhesion 3.8MPa 5.6MPa +47% Coating line speed 8m / min 12m / min +50% Embodiment Two:

[0047] Offshore wind tower protection: 16MW offshore wind turbine project

[0048] 1. Preparation scheme and optimization technology

[0049] Step two (high-speed grinding dispersion):

[0050] In-situ generated SiO2 network (3% tetraethyl orthosilicate added), impact strength increased from 65 kg·cm to 82 kg·cm. Graphene / boron nitride composite filler (added 5%) friction coefficient reduced to 0.15.

[0051] Step four (curing process): light-heat dual curing makes the coating interval from 72h to 4h, suitable for intertidal construction window.

[0052] 2. Performance improvement data comparison

[0053] Performance index Traditional epoxy system Optimized polyurethane system Improvement range 5-year gloss retention rate (ISO 2813) 68% 89% +31% Resistance to cyclic corrosion period (ISO 20340) 15 cycles 25 cycles +67% Single tower cylinder coating time 120h 78h -35% Maintenance cycle 3 years 8 years +167% Embodiment Three:

[0054] Unmanned aerial vehicle shell coating: DJI Inspire 4 industry level unmanned aerial vehicle

[0055] 1. Preparation scheme and optimization technology

[0056] Step three (addition of auxiliary and paint conditioning):

[0057] 28 kHz ultrasonic treatment (energy density 55 J / cm³), nano secondary agglomeration rate reduced by 60%, roughness Ra reduced from 3 μm to 1.8 μm. Flexible curing agent (Tg = -40℃) passed -30℃ cold impact test.

[0058] Step one (filler architecture), flaky mica powder (aspect ratio 50:1) and nano CaCO3 are compounded, polishing efficiency 22.5 g / min when film thickness is 45 μm.

[0059] 2. Performance improvement data comparison

[0060] Performance index Competitor A DJI customized formula Improvement range Film thickness / weight ratio (μm / kg) 60 / 0.48 45 / 0.32 -25% / -33% Drop height resistance (GB / T 2423) 3J qualified 8J no damage +167% Low temperature bending property (-30℃) Cracking No abnormality Fully solved VOC emission 350g / L 250g / L -29%

[0061] In summary, the application of the improved polishing effect polyurethane solid color primer is summarized as follows:

[0062] Technical module Automobile manufacturing Offshore wind power Drone shell Common improvement direction Surface energy regulation PDMS coating to enhance chemical corrosion resistance Graphene to reduce friction coefficient Mica powder to optimize lightweight Interface bonding strength improved by 20-25% Curing efficiency Light-thermal curing to shorten the surface drying time Shorten the interval between coating to 4h Low temperature toughness to adapt to extreme environment Production efficiency improved by 30-50% Dispersion uniformity SiO2 network resistant to permeation In-situ generation of corrosion-resistant structure Ultrasonic treatment to reduce roughness Nanometer dispersion uniformity >95% Environmental protection Reduce VOC by 18% Prolong the maintenance cycle and reduce the consumption of paint Bio-based raw materials replace 30% Carbon footprint reduction in all fields by 20-40%

[0063] Through precise resin system design, nano filler dispersion and intelligent curing process, the polyurethane solid color primer realizes the overall improvement of wear resistance, corrosion resistance, construction efficiency and environmental protection in the fields of automobile, wind power and unmanned aerial vehicle.

[0064] According to the above disclosure, related personnel can make various changes and modifications without deviating from the technical idea of the present application.

Claims

1. The development of a polyurethane solid color primer for improving sanding effect, characterized in that: The specific steps include the following: Step 1: Raw material premixing and dispersion, including resin system preparation and filler pretreatment, to ensure resin compatibility and uniform filler dispersion. The resin system configuration involves mixing hydroxyl acrylic resin with short-oil alkyd resin, and the filler pretreatment involves plasma-assisted polydimethylsiloxane coating of talc powder and nano-calcium carbonate. Step 2: High-speed grinding and dispersion. The polyurethane prepolymer from Step 1 is ground using a basket mill in stages. In the initial grinding stage, the mill speed is 6000 rpm and the grinding time is 30 min to control the fineness of the slurry to 25 μm. In the fine grinding stage, the slurry fineness is refined to ≤15 μm. Step 3: Additives and paint mixing. In the grinding slurry of Step 2, add rheology modifier and curing catalyst in sequence, and cure at 25°C for 24 hours. Step 4: Curing agent compounding and filling. The HDI trimer obtained in step 3 is mixed with the hydroxyl component at an equivalent ratio of 1.1:

1. The viscosity is adjusted to 200-300 mPa·s at 25°C and cured under nitrogen protection before final packaging. In step one, hydroxyl acrylic resin, short-oil alkyd resin, talc powder and nano calcium carbonate are automatically fed by a mass flow meter. In step one, nano-calcium carbonate is coated with polydimethylsiloxane under plasma-assisted conditions in a supercritical CO2 environment with a pressure of 7.39 MPa and a temperature of 31.1 °C. In step two, tetraethyl orthosilicate is directly added to the polyurethane prepolymer to generate a SiO2 network in situ via the sol-gel method. In step four, a photoinitiator was added before curing. First, it underwent UV pre-curing for 10 seconds, followed by thermal curing at 60°C for 30 minutes.

2. The development of the polyurethane solid color primer for improving sanding effect according to claim 1, characterized in that: In step three, 28kHz ultrasound is applied during the curing stage, with an ultrasound energy density ≥50J / cm³.

3. A polyurethane solid-color primer for improving sanding effect according to claim 1 or 2, characterized in that: Applications include automobile manufacturing, offshore wind turbine towers, and drone shells.

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