Environment-friendly coating and preparation method thereof

Abstract

The invention discloses an environment-friendly coating which is prepared from the following raw materials in parts by weight: 40-60 parts of modified vegetable oil emulsion, 10-15 parts of a nano photocatalyst, 5-8 parts of plant fiber filler, 3-5 parts of a biomass calcium agent and 1.8-2.5 parts of a synergistic aid. The preparation method of the environment-friendly coating comprises the following steps: S1, plant fiber pretreatment; s2, carrying out antioxidant modification on the emulsion; s3, gradient grinding; and S4, curing. According to the environment-friendly coating, the oxidation chain reaction of soybean oil is blocked through tea polyphenol grafting, the free radical capture rate is high, aging is delayed, meanwhile, zero toxicity release and zero formaldehyde generation of the environment-friendly coating are achieved, and meanwhile the hardness defect of bio-based emulsion is effectively overcome through the soybean oil-tea polyphenol grafting technology; shell powder is used for loading TiO2 to form electron-hole pairs, so that formaldehyde can be purified for a long time; plant fibers are added and matched with shell powder and nano TiO2 to form a ternary reinforcing system, so that the crack resistance of a coating film is enhanced; the activity of natural components is protected through low-temperature grinding, and the retention rate of tea polyphenol is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint technology, in particular to an environment-friendly paint and a preparation method thereof. BACKGROUND

[0002] Paint is a material which can be coated on the surface of an object by a certain construction method, and a continuous film is formed after drying or curing, which has the function of protection, decoration or other special functions for the coated object. It is usually prepared by using resin, or oil, or emulsion as the main component, adding or not adding pigments, fillers, and corresponding additives, and using organic solvents or water.

[0003] The traditional solvent-based paint on the market contains benzene / formaldehyde, pollutes the environment and harms health, and some paints have insufficient coating strength after brushing, which is prone to cracking. Therefore, an environment-friendly paint and a preparation method thereof are proposed to solve the above problems. SUMMARY

[0004] The present application aims to provide an environment-friendly paint and a preparation method thereof to solve the problems in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: an environment-friendly paint is composed of the following raw materials by weight: modified vegetable oil emulsion 40-60 parts, nano photocatalyst 10-15 parts, plant fiber filler 5-8 parts, biomass calcium agent 3-5 parts, and synergistic additive 1.8-2.5 parts.

[0006] Preferably, the modified vegetable oil emulsion is prepared by reacting soybean oil with tea polyphenol at 60±2°C under nitrogen protection, and the grafting rate is 35-42%.

[0007] Preferably, the nano photocatalyst comprises a core-shell structure of nano TiO2 and porous shell powder, wherein the specific surface area of the shell powder is ≥18 m 2 / g, the pore volume is 0.85±0.05 cm 3 / g, and the TiO2 loading is 12-15 wt%.

[0008] Preferably, the preparation method of the nano photocatalyst comprises: ultrasonic treatment of the shell powder in 0.1M citric acid for 30 min, and then hydrothermal reaction with TiOSO4 solution at 120°C for 4h, so that TiO2 is deposited in the pores of the shell powder in the form of anatase.

[0009] Preferably, the plant fiber filler is bamboo fiber treated with 5wt% NaOH solution, and the crystallinity is reduced to 43-46%, the length distribution is 50-80μm, and the aspect ratio is >18.

[0010] Preferably, the biomass calcium agent is porous shell powder, and the specific surface area is ≥15 m2 / g, pore volume 0.8-1.2 cm 3 / g, CaCO3 content ≥95wt%.

[0011] Preferably, the synergistic aid comprises: tea polyphenol with catechin content ≥60% 0.8-1.2 parts, polyether modified polysiloxane leveling agent 0.5-0.8 parts, phosphate ester dispersant 0.5-0.7 parts.

[0012] The preparation method of the environment-friendly paint comprises the following steps:

[0013] S1, plant fiber pretreatment: bamboo fiber is treated in 5wt% NaOH solution at 90℃ for 2h, washed to neutral, and then broken to D50≤50μm;

[0014] S2, emulsion antioxidant modification: soybean oil emulsion is reacted with tea polyphenol under nitrogen protection at 60±2℃ for 2h, the nitrogen flow is 1.5-2L / min, and the oxygen content of the reaction system is ≤50ppm;

[0015] S3, gradient grinding:

[0016] Coarse grinding: the plant fiber, shell powder composite TiO2 and deionized water are mixed in a mass ratio of 1:3, zirconium beads φ1.2mm, linear speed 6-8m / s, and ground to D50≤35μm;

[0017] Fine grinding: the modified emulsion is added, zirconium beads φ0.8mm, linear speed 9.5±0.3m / s, outlet temperature ≤45℃, and ground to a fineness ≤12μm;

[0018] S4, curing: the synergistic aid is added, defoaming is performed at a low speed of 500±10rpm for 35±1min, the curing temperature is raised to 55℃, and the viscosity is reduced to 4 cups 75±3s.

[0019] Preferably, the gradient grinding adopts a double sand mill series system: the power density of the front-stage sand mill is ≥3.2kW / m 3 , and the cooling liquid temperature of the rear-stage sand mill is 5±1℃.

[0020] Compared with the prior art, the environment-friendly paint has the beneficial effects that the tea polyphenol is used to graft and block the soybean oil oxidation chain reaction, the free radical capture rate is high, the aging is delayed, the environment-friendly paint is zero toxicity release and zero formaldehyde generation, the soybean oil-tea polyphenol grafting technology effectively solves the hardness defect of the bio-based emulsion, the shell powder loaded TiO2 forms an electron-hole pair to realize persistent purification of formaldehyde, the plant fiber is added to form a ternary reinforcing system with the shell powder and nano TiO2 to enhance the crack resistance of the coating film, and the low-temperature grinding protects the activity of the natural components, and the tea polyphenol retention rate is high. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0022] Embodiment one

[0023] The present application provides a technical solution: an environment-friendly paint, which is composed of the following raw materials by weight:

[0024] 40-60 parts of modified vegetable oil emulsion, the modified vegetable oil emulsion is prepared by reacting soybean oil with tea polyphenol at 60±2°C under nitrogen protection, with a grafting rate of 35-42%, experiments show that when the grafting rate is less than 35%, the weather resistance suddenly decreases (QUV 500h gloss retention <80%), and when the grafting rate is greater than 42%, the emulsion gels;

[0025] Tea polyphenol-soybean oil grafting mechanism

[0026]

[0027] FTIR evidence: 1745cm -1 ester bond peak enhancement, 1260cm -1 phenolic ether bond new peak;

[0028] DSC evidence: after grafting, the glass transition temperature Tg increases from -42°C to -28°C (improving the rigidity of the coating);

[0029] Free radical capture effect (ESR spectrum verification)

[0030] System Radical concentration Half-life (min) Capture rate Ordinary soybean emulsion 1263±85 18.2 - Grafted emulsion of the present invention 92±7 3.5 92.7％

[0031] Compared with simply using ordinary soybean emulsion completely, the grafted emulsion of the present application has a higher free radical capture rate, and can also reduce the manufacturing cost;

[0032] 10-15 parts of nano photocatalyst, the nano photocatalyst comprises a core-shell structure of nano TiO2 and porous shell powder, wherein the specific surface area of the shell powder is ≥18m 2 / g, the pore volume is 0.85±0.05cm 3 / g, BET test shows that the TiO2 loading amount in this range is optimal (loading amount <12% is insufficient for purification, and >15% is blocked in the channel), the TiO2 loading amount is 12-15wt%, and the preparation method of the nano photocatalyst comprises the following steps: ultrasonic treatment of the shell powder in 0.1M citric acid for 30min, and hydrothermal reaction with TiOSO4 solution at 120°C for 4h, so that the TiO2 is deposited in the shell powder channel in the form of anatase;

[0033] Mechanism of shell powder loading nano-TiO2

[0034]

[0035] BET data: TiO2 dispersion improved 3.2 times after loading (specific surface area from 45→143 m 2 / g);

[0036] Photocatalytic efficiency: formaldehyde degradation rate constant k = 0.056 min -1 (Comparative physical mixing k = 0.019 min -1 );

[0037] Plant fiber filler 5-8 parts, plant fiber filler is bamboo fiber treated with 5wt% NaOH solution, crystallinity reduced to 43-46%, length distribution 50-80μm, aspect ratio > 18;

[0038] Biomass calcium agent 3-5 parts, biomass calcium agent is porous shell powder, specific surface area ≥ 15 m 2 / g, pore volume 0.8-1.2 cm 3 / g, CaCO3 content ≥ 95wt%;

[0039] Synergistic aid 1.8-2.5 parts, synergistic aid contains: tea polyphenol with catechin content ≥ 60% 0.8-1.2 parts, polyether modified polysiloxane leveling agent 0.5-0.8 parts, phosphate ester dispersant 0.5-0.7 parts.

[0040] Example two

[0041] Preparation method of environment-friendly coating, comprising the following steps:

[0042] S1, plant fiber pretreatment: bamboo fiber is treated in 5wt% NaOH solution at 90℃ for 2h, washed to neutral, then broken to D50≤50μm;

[0043] S2, emulsion antioxidant modification: soybean oil emulsion and tea polyphenol are reacted under nitrogen protection at 60±2℃ for 2h, nitrogen flow 1.5-2L / min, oxygen content of reaction system ≤50ppm;

[0044] S3, gradient grinding:

[0045] Coarse grinding: plant fiber, shell powder composite TiO2 and deionized water are mixed in a mass ratio of 1:3, zirconium beads φ1.2mm, linear speed 6-8m / s, ground to D50≤35μm;

[0046] Refining: Add modified emulsion, zirconium beads φ0.8mm, linear speed 9.5±0.3m / s, energy input critical point, less than 9.2m / s fineness>15μm, higher than 9.8m / s cause fiber fracture, outlet temperature≤45℃, grind to fineness≤12μm;

[0047] Gradient grinding adopts a double sand mill series system: the power density of the front-stage sand mill≥3.2kW / m 3 , and the cooling liquid temperature of the rear-stage sand mill is 5±1℃;

[0048] S4, aging: add synergistic additives, 500±10rpm low-speed stirring defoaming 35±1min, aging temperature rises to 55℃, viscosity drops to 75±3s.

[0049] Example three

[0050] Pre-disperse 6.5 parts of bamboo fiber powder and 4 parts of shell powder in 50 parts of deionized water, 55 parts of soybean oil emulsion+1 part of tea polyphenol, generate brown viscous liquid under nitrogen at 60℃, add 12 parts of nano TiO2 and pre-dispersed slurry, sand mill to fineness 12.5μm, add 1 part of water-based polyurethane leveling agent, detect viscosity after 500rpm aging (coating 4 cup: 85s).

[0051] The prepared environment-friendly paint is tested according to the national standard GB24408-2020, and the test results are as follows

[0052] Performance index The present invention National standard GB24408-2020 VOC content 18g / L ≤50g / L Scrubbability >10000 times ≥5000 times 24h water absorption rate 3.2％ ≤10％ QUV aging gloss retention rate 92％(1000h) 80％(600h) Formaldehyde purification rate 91.5％ -

[0053] From the above table, the present application has: environmental protection, high content of bio-based+zero heavy metal; functionality: high hardness+91.5% formaldehyde purification rate; economy: can effectively reduce the production cost. The present application provides a solution for the field of environment-friendly paint, which has the advantages of "green, high performance and low cost".

[0054] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An environmentally friendly coating characterized in that The modified vegetable oil emulsion is prepared from the following raw materials by weight: 40-60 parts of modified vegetable oil emulsion, 10-15 parts of nano photocatalyst, 5-8 parts of plant fiber filler, 3-5 parts of biomass calcium agent, and 1.8-2.5 parts of synergistic auxiliary agent.

2. The eco-friendly coating according to claim 1, characterized in that: The modified vegetable oil emulsion is prepared from soybean oil and tea polyphenol under nitrogen protection at 60±2℃, with a grafting rate of 35-42%.

3. The eco-friendly coating according to claim 1, characterized in that: The nano-photocatalyst comprises a core-shell structure of nano-TiO2 and porous shell powder, wherein the specific surface area of the shell powder is ≥18 m 2 / g, the pore volume is 0.85±0.05 cm 3 / g, and the TiO2 loading is 12-15 wt%.

4. The eco-friendly coating according to claim 3, characterized in that: The preparation method of the nano photocatalyst comprises the following steps: ultrasonic treatment of shell powder in 0.1M citric acid for 30min, and hydrothermal reaction with TiOSO4 solution at 120℃ for 4h, so that TiO2 is deposited in the shell powder channel in the form of anatase.

5. The eco-friendly paint according to claim 1, characterized by: The plant fiber filler is bamboo fiber treated with 5wt% NaOH solution, with a crystallinity of 43-46%, a length distribution of 50-80μm, and an aspect ratio of >18.

6. The eco-friendly paint according to claim 1, characterized by: The biomass calcium agent is porous shell powder, specific surface area ≥ 15 m 2 / g, pore volume 0.8-1.2 cm 3 / g, CaCO3 content ≥ 95 wt%.

7. The eco-friendly paint according to claim 1, characterized by: The synergistic auxiliary agent comprises: 0.8-1.2 parts of tea polyphenol with a catechin content of ≥60%, 0.5-0.8 parts of polyether modified polysiloxane leveling agent, and 0.5-0.7 parts of phosphate ester dispersant.

8. The method of claim 1-7, wherein the environmentally friendly coating is prepared by The method comprises the following steps: S1, plant fiber pretreatment: bamboo fiber is treated in 5wt% NaOH solution at 90℃ for 2h, washed to neutral, and then broken to D50≤50μm; S2, emulsion antioxidant modification: soybean oil emulsion is reacted with tea polyphenol under nitrogen protection at 60±2℃ for 2h, with a nitrogen flow of 1.5-2L / min, and an oxygen content of the reaction system of ≤50ppm; S3, gradient grinding: Coarse grinding: plant fiber, shell powder composite TiO2, and deionized water are mixed in a mass ratio of 1:3, zirconium beads φ1.2mm, linear speed 6-8m / s, and ground to D50≤35μm; Fine grinding: modified emulsion is added, zirconium beads φ0.8mm, linear speed 9.5±0.3m / s, outlet temperature ≤45℃, and ground to a fineness of ≤12μm; S4, aging: synergistic auxiliary agent is added, defoaming is performed at a low speed of 500±10rpm for 35±1min, the aging temperature is raised to 55℃, and the viscosity is reduced to 4 cups 75±3s.

9. The method for preparing the environmentally friendly coating according to claim 8, characterized in that: The gradient grinding adopts a double sand mill series system: the power density of the front-stage sand mill is ≥3.2 kW / m 3 , and the cooling liquid temperature of the rear-stage sand mill is 5±1℃.

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