CN117210100A - Powder coating and preparation method and application thereof - Google Patents

Abstract

The invention relates to a powder coating, a preparation method and application thereof, wherein the powder coating comprises the following components in parts by weight: 50-100 parts of matrix resin, 2-25 parts of curing agent, 0.5-8 parts of composite curing accelerator and 0.1-5 parts of nano filler; the composite curing accelerator comprises nano rubber particles and a liquid tertiary amine catalyst loaded on the nano rubber particles. The powder coating provided by the invention applies the more efficient liquid tertiary amine catalyst to a solid powder coating system, so that the selection range of the curing accelerator for the powder coating is expanded; and the powder coating has the advantages of short curing time and low curing temperature, and the coating formed after curing has good impact strength, adhesive force, solvent resistance, acid resistance, alkali resistance, moist heat resistance and neutral salt fog resistance, and is suitable for coating heat-sensitive substrates such as wood, engineering plastics, glass, paper and the like.

Description

A kind of powder coating and its preparation method and application

Technical field

The invention belongs to the technical field of coating compositions, and specifically relates to a powder coating and its preparation method and application.

Background technique

Powder coating is a solid powder environmentally friendly coating that does not contain any organic solvents. However, powder coatings have the problem of high curing temperatures. Therefore, low-temperature curing powder coatings have become a research hotspot in the coatings industry in recent years. However, under low-temperature curing conditions, powder coatings The coating formed after curing of the paint has problems such as impact strength, flexural strength, adhesion and other physical and chemical properties that cannot meet the performance requirements, which hinders its further application. Therefore, it is of great significance to prepare powder coatings with low curing temperature and excellent comprehensive properties.

When preparing low-temperature curing powder coatings in the prior art, the main method is to add highly active resins or curing accelerators. CN116041676A discloses a polyester resin for low-temperature curing powder coatings cured at 160°C and a preparation method thereof. CN115109259A discloses a low-temperature curable polyester resin and a preparation method thereof. However, such high-activity low-temperature curing resins are all The functional group system has poor physical and chemical properties such as coating flexibility after low-temperature curing. CN106398482A discloses a low-temperature curing powder coating prepared with 2-phenylimidazoline as a curing accelerator. In order to adapt to the processing method of the low-temperature curing powder coating, the invention uses a solid accelerator, and a larger amount of curing accelerator is added. And the catalytic efficiency is low.

In existing low-temperature curing powder coatings, it is common that the catalytic efficiency of the curing accelerator in the powder coating is low. After the low-temperature curing powder coating is cured, the impact strength, adhesion and other physical and chemical properties of the coating are poor. A new method with short curing time and high curing temperature needs to be developed. Low, and the powder coating has good physical and chemical properties such as impact strength and adhesion after low-temperature curing.

Contents of the invention

In view of the shortcomings of the existing technology, the object of the present invention is to provide a powder coating and its preparation method and application. Through the selection and regulation of the dosage of each component of the powder coating, the powder coating has lower curing temperature, short curing time, and the coating after low-temperature curing has excellent impact strength, adhesion and other physical and chemical properties.

To achieve this goal, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a powder coating, which includes the following components in parts by weight: 50-100 parts by weight of matrix resin, 2-25 parts by weight of curing agent, 0.5-8 parts by weight of composite curing accelerator, and Nano filler 0.1-5 parts by weight; the composite curing accelerator includes nano rubber particles and a liquid tertiary amine catalyst loaded on the nano rubber particles.

The powder coating provided by the invention can fully absorb mid-wave infrared, and the composite curing accelerator in the powder coating can promote the curing of the powder coating, reduce the curing temperature of the powder coating, shorten the curing time, and at the same time improve the formation of the powder coating after curing. The flexibility and adhesion of the coating; the nanofiller can improve the adhesion of the coating formed after the powder coating is cured, and can also regulate the rheology of the powder coating. By adsorbing the liquid tertiary amine catalyst in the composite curing accelerator to nano-rubber particles, the present invention can apply a more efficient liquid tertiary amine catalyst to the solid powder coating system. The other components of the powder coating cooperate with each other in specific proportions, so that the coating formed after curing the powder coating has good impact strength, adhesion, solvent resistance, acid resistance, alkali resistance, moisture and heat resistance and neutral resistance. Salt spray.

The matrix resin is 50-100 parts by weight, for example, it can be 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight or 100 parts by weight, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

The curing agent is 2-25 parts by weight, for example, it can be 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 24 parts by weight or 25 parts by weight, as well as specific points between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific points included in the range. .

The composite curing accelerator is 0.5-8 parts by weight, for example, it can be 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, or 7 parts by weight parts or 8 parts by weight, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

The nanofiller is 0.1-5 parts by weight, for example, it can be 0.1 part by weight, 0.5 part by weight, 1 part by weight, 1.5 part by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight or 5 parts by weight, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

As a preferred technical solution, the matrix resin includes a combination of a first resin and a second resin.

Preferably, based on the mass of the matrix resin being 100%, the mass of the second resin is ≤50%, for example, it can be 0, 5%, 10%, 15%, 20%, 25%, 30%, 35 %, 40%, 45% or 50%, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

Preferably, the first resin includes a combination of low viscosity epoxy resin and high viscosity epoxy resin.

The high viscosity epoxy resin of the present invention is beneficial to the dispersion of nano rubber particles, and can improve the physical and chemical properties of the coating formed after the powder coating is cured. At the same time, the good dispersion of the nano rubber particles can also promote the dispersion of the liquid tertiary amine catalyst; low The viscosity epoxy resin has more reactive functional groups, which can improve the activity of the powder coating and promote the curing of the powder coating.

Preferably, based on the mass of the first resin being 100%, the mass of the low viscosity epoxy resin is 10-30%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20% %, 22%, 24%, 26%, 28% or 30%, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific points included in the range. value.

Preferably, the low-viscosity epoxy resin includes any one or a combination of at least two of the first bisphenol A-type epoxy resin, bisphenol F-type epoxy resin or novolac epoxy resin.

Preferably, the high viscosity epoxy resin includes a second bisphenol A type epoxy resin.

Preferably, the melt viscosity of the first bisphenol A-type epoxy resin and the novolac epoxy resin at 150°C is each independently 300-4000mPa.s, for example, it can be 300mPa.s or 500mPa. s, 800mPa.s, 1000mPa.s, 1300mPa.s, 1500mPa.s, 2000mPa.s, 2200mPa.s, 2600mPa.s, 2800mPa.s, 3000mPa.s, 3200mPa.s, 3400mPa.s, 3600mPa.s, 3800mPa.s or 4000mPa.s, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the melt viscosity of the high-viscosity epoxy resin at 150°C is 6000-13000mPa.s, for example, it can be 6000mPa.s, 7000mPa.s, 8000mPa.s, 9000mPa.s, 10000mPa.s, 11000mPa. s, 12000mPa.s or 13000mPa.s, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the second resin includes any one or a combination of at least two of carboxyl polyester resin, hydroxyl polyester resin or carboxyl acrylic resin.

In the powder coating provided by the present invention, the second resin has a higher functional group content, which can promote the solidification of the powder coating and increase the cross-linking density.

Preferably, the acid value of the carboxyl polyester resin is 50-70 mg KOH/g, for example, it can be 50 mg KOH/g, 52 mg KOH/g, 54 mg KOH/g, 56 mg KOH/g, 58 mg KOH/g, 60 mg KOH /g, 62mg KOH/g, 64mg KOH/g, 66mg KOH/g, 68mg KOH/g or 70mg KOH/g, as well as specific point values between the above points. For the sake of space and conciseness, the present invention The specific point values included in the stated range are not intended to be exhaustive.

Preferably, the hydroxyl value of the hydroxyl polyester resin is 100-220 mg KOH/g, for example, it can be 100 mg KOH/g, 110 mg KOH/g, 120 mg KOH/g, 130 mg KOH/g, 140 mg KOH/g, 150 mg KOH /g, 160mg KOH/g, 170mg KOH/g, 180mg KOH/g, 190mg KOH/g, 200mg KOH/g, 210mg KOH/g or 220mg KOH/g, and specific point values between the above points, limited to For the sake of space and conciseness, the present invention does not exhaustively list the specific point values included in the stated range.

Preferably, the acid value of the carboxyl acrylic resin is 140-200 mg KOH/g, for example, it can be 140 mg KOH/g, 150 mg KOH/g, 160 mg KOH/g, 170 mg KOH/g, 180 mg KOH/g, 190 mg KOH/g. g or 200 mg KOH/g, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the curing agent includes triglycidyl isocyanurate, substituted dicyandiamide, blocked polyisocyanate, dodecanedioic acid, dicarboxylic acid dihydrazide, acid anhydride, novolac resin, and phenolic hydroxyl resin. Or any one or a combination of at least two of the hydroxyalkyl amides.

Preferably, the nano-rubber particles include any one or a combination of at least two of nano-nitrile powder rubber particles, nano-carboxy nitrile powder rubber particles, nano-butadiene powder rubber particles or core-shell nano-rubber particles, Nano nitrile powder rubber particles are further preferred.

Preferably, the core-shell nano-rubber particles include butadiene core-shell rubber particles and/or acrylic core-shell rubber particles. In the present invention, the core-shell nano-rubber particles are commercially available products. For example, the butadiene core-shell rubber particles can be purchased from KanenaMZ120 of Jongyon Chemical.

Preferably, the particle size of the nano-rubber particles is 50-500nm, for example, it can be 50nm, 60nm, 70nm, 80nm, 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm. , and the specific point values between the above-mentioned point values. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

Preferably, the liquid tertiary amine catalyst includes any one of linear alkyl tertiary amines, triethanolamine, triethylenediamine, dimethylaminomethylphenol or tris(dimethylaminomethyl)phenol or A combination of at least two.

Preferably, the linear alkyl-containing tertiary amine includes dodecyldimethyltertiary amine, cetyldimethyltertiary amine, tetradecyldimethyltertiary amine or octadecyldimethylamine. Any one or a combination of at least two tertiary amines.

Preferably, the mass ratio of the nano rubber particles and the liquid tertiary amine catalyst is (4-15):1, for example, it can be 4:1, 5:1, 6:1, 7:1, 8:1. , 9:1, 10:1, 11:1, 12:1, 13:1, 14:1 or 15:1, etc.

Preferably, the nanofiller includes any one or a combination of at least two of nanoboehmite, nanocellulose or nanosilica.

Preferably, the composite curing accelerator is prepared by the following method, which method includes: mixing the nano-rubber particles and the liquid tertiary amine catalyst, and the liquid tertiary amine catalyst is adsorbed on the nano-rubber particles. Above, the composite curing accelerator is obtained.

Preferably, the mixing time is 20-60s, for example, it can be 20s, 22s, 24s, 26s, 28s, 30s, 32s, 34s, 36s, 38s, 40s, 44s, 48s, 50s, 52s, 54s, 56s, 58s or 60s, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the mixing temperature is 20-35°C, for example, it can be 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C or 35°C, and between the above points Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the powder coating also includes 0.1-0.5 parts by weight of degassing agent, for example, it can be 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight or 0.5 parts by weight, and between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the degassing agent includes benzoin.

Preferably, the powder coating also includes 0.2-1 parts by weight of leveling agent, for example, it can be 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, or 0.8 parts by weight. part, 0. part by weight or 1 part by weight, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

Preferably, the leveling agent includes any one or a combination of at least two of acrylic polymer leveling agents.

Preferably, the powder coating also includes 0.1-0.5 parts by weight of pigment, for example, it can be 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight or 0.5 part by weight, and any specific value between the above points. Point values, due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

Preferably, the pigment includes any one or a combination of at least two of rutile titanium dioxide, iron yellow, phthalocyanine blue, phthalocyanine green, iron oxide red or ultramarine blue.

Preferably, the curing temperature of the powder coating is 125-135°C.

Preferably, the curing method of the powder coating includes infrared curing.

Preferably, the infrared curing power is 5-20kW/m ² , for example, it can be 5kW/m ² , 8kW/m ² , 10kW/m ² , 12kW/m ² , 14kW/m ² , 16kW/m ² , 18kW/m ² or 20kW/m ² , as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the range.

Preferably, the infrared curing time is 3-8 min, for example, it can be 3 min, 4 min, 5 min, 6 min, 7 min or 8 min, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, this article The invention is not intended to exhaustively list the specific points included in the stated range.

In a second aspect, the present invention provides a method for preparing a powder coating as described in the first aspect. The preparation method includes: mixing a matrix resin, a curing agent, a composite curing accelerator and a nanofiller, followed by melting and extruding, and then sequentially Carry out tableting, cooling, crushing and screening to obtain the powder coating.

Preferably, the mixed materials also include degassing agents, leveling agents and pigments.

Preferably, the melt extrusion temperature is 80-110°C, for example, it can be 80°C, 85°C, 88°C, 90°C, 95°C, 98°C, 100°C, 102°C, 105°C, 108°C or 110°C. °C, as well as specific point values between the above points. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the specific point values included in the stated range.

Preferably, the particle size is 10-100 μm (such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc.), further preferably 20-80 μm (such as 20 μm, 30 μm, 40 μm, etc.) , 50μm, 60μm, 70μm or 80μm, etc.).

Preferably, the mesh size of the screening mesh is 140-200 mesh, for example, it can be 140 mesh, 170 mesh, 180 mesh or 200 mesh.

In a third aspect, the present invention provides a powder coating as described in the first aspect for coating a heat-sensitive substrate.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The powder coating provided by the present invention can apply the liquid tertiary amine catalyst of traditional epoxy resin to the solid powder coating, promote the dispersion of the liquid tertiary amine catalyst, and improve the catalytic efficiency of the liquid tertiary amine catalyst and expand The selection range of curing accelerators for powder coatings has been expanded;

(2) The powder coating provided by the present invention has low curing temperature and short curing time. After low-temperature curing, the surface of the coating has high smoothness and no pinholes. The curing temperature is 125-135°C. The coating formed after curing It has good impact strength, impact performance of 100-120cm, adhesion of level 0, solvent resistance test without loss of light and softening for 100 times, acid resistance test without blistering and shedding for 240h, and alkali resistance test without blistering and shedding for 240h. , there is no loss of gloss and blistering after 1000h of moisture and heat resistance test, and no rust spots and blistering after 1000h of neutral salt spray resistance test.

Detailed ways

In order to facilitate understanding of the present invention, the following examples are enumerated. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

The sources of some components in the examples and comparative examples are as follows:

(1) Low viscosity epoxy resin:

a. Bisphenol A epoxy resin: HY902 purchased from Anhui Hengyuan, melt viscosity at 150°C is 2000mPa.s;

KD-211E purchased from Guodu Chemical has a melt viscosity of 300 mPa.s at 150°C;

b. Novolac epoxy resin: KD-211D and KD-211H purchased from Guodu Chemical Industry, the melt viscosity at 150°C is 2000mPa.s and 4000mPa.s respectively;

(2) High-viscosity bisphenol A-type epoxy resin: NPES-904H, NPES-904F and NPES-904HP purchased from Nanya, with melt viscosity at 150°C of 6000mPa.s, 9000mPa.s and 13000mPa.s respectively;

(3) Carboxy polyester resin: purchased from Allnex Resin 1545, with an acid value of 70 mg KOH/g;

(4) Carboxy acrylic resin: purchased from G152, with an acid value of 155 mg KOH/g;

(5) Hydroxy polyester resin: purchased from P1413, with a hydroxyl value of 100 mg KOH/g;

(6) Nano nitrile powder rubber particles: VP401 purchased from Yanshan Petrochemical, with a particle size of 80-120nm;

(7) Nano carboxyl nitrile powder rubber particles: VP501 purchased from Yanshan Petrochemical, with a particle size of 80-120nm;

(8) Butadiene core-shell rubber particles: kanena MZ120 purchased from Zhongyuan Chemical, with a particle size of 100-200nm;

(9) Nanoboehmite: purchased from Xuancheng Chengjingrui New Materials Co., Ltd., with a particle size of 10-15nm;

(10) Nano silicon oxide: purchased from Xuancheng Chengjingrui New Materials Co., Ltd., D50 is 30nm;

(11) Leveling agent: GLP588 purchased from Ningbo Nanhai Chemical Co., Ltd.;

(12) Substituted dicyandiamide: XB2632 purchased from Ciba;

(13) Blocked polyisocyanate: Degussa EP-BF 1320.

Preparation Example 1

A composite curing accelerator A, including nano nitrile powder rubber particles VP401 and cetyl dimethyl tertiary amine loaded thereon. The preparation method of the composite curing accelerator A includes: adding 7.5 parts by weight of nano nitrile After the powder rubber particles VP401 and 0.5 parts by weight of cetyldimethyl tertiary amine were mixed in a high-speed mixer at 24000r/min for 30 seconds, the cetyldimethyl tertiary amine was adsorbed on the nano-nitrile powder rubber particles VP401. Above, the composite curing accelerator A is obtained.

Preparation Example 2

A composite curing accelerator B, including nano carboxyl nitrile powder rubber particles VP501 and octadecyldimethyl tertiary amine loaded thereon. The preparation method of the composite curing accelerator B includes: adding 4 parts by weight of nano carboxyl Nitrile powder rubber particles VP501 and 1 part by weight of octadecyldimethyl tertiary amine were mixed by a high-speed mixer at 24000r/min for 30 seconds. The octadecyldimethyl tertiary amine was adsorbed on the nanocarboxyl nitrile powder. On the rubber particles VP501, the composite curing accelerator B was obtained.

Preparation Example 3

A composite curing accelerator C, including nano carboxyl nitrile powder rubber particles VP501 and tetradecyl dimethyl tertiary amine loaded thereon. The preparation method of the composite curing accelerator C includes: adding 12 parts by weight of nano carboxyl Nitrile powder rubber particles VP501 and 1 part by weight of tetradecyldimethyl tertiary amine were mixed by a high-speed mixer at 24000r/min for 30 seconds. The tetradecyldimethyl tertiary amine was adsorbed on the nanocarboxyl nitrile powder. On the rubber particles VP501, the composite curing accelerator C is obtained.

Preparation Example 4

A composite curing accelerator D, including nanocarboxylated nitrile powder rubber particles VP501 and triethanolamine loaded thereon. The preparation method of the composite curing accelerator D includes: adding 10 parts by weight of nanocarboxylated nitrile powdered rubber particles VP501 and After 1 part by weight of triethanolamine was mixed with a high-speed mixer at a speed of 24,000 r/min for 30 seconds, the triethanolamine was adsorbed on the nanocarboxylic nitrile powder rubber particles VP501 to obtain the composite curing accelerator D.

Preparation Example 5

A composite curing accelerator E includes butadiene core-shell rubber particles and cetyldimethyl tertiary amine loaded thereon. The preparation method of the composite curing accelerator E includes: adding 9 parts by weight of butadiene After the olefin core-shell type rubber particles and 1 part by weight of cetyldimethyl tertiary amine were mixed in a high-speed mixer at 24000r/min for 30 seconds, the cetyldimethyl tertiary amine was adsorbed on the butadiene core and shell. type rubber particles, the composite curing accelerator E is obtained.

Preparation Example 6

A composite curing accelerator F, including nano nitrile powder rubber particles VP401 and cetyl dimethyl tertiary amine loaded thereon. The preparation method of the composite curing accelerator F includes: adding 3 parts by weight of nano nitrile After the powder rubber particles VP401 and 1 part by weight of cetyldimethyl tertiary amine were mixed in a high-speed mixer at 24000r/min for 30 seconds, the cetyldimethyl tertiary amine was adsorbed on the nano-nitrile powder rubber particles VP401. Above, the composite curing accelerator F is obtained.

Preparation Comparative Example 1

A composite curing accelerator G, including nanocarboxylated nitrile powder rubber particles VP501 and 2-isopropylimidazole loaded thereon. The preparation method of the composite curing accelerator G includes: adding 12 parts by weight of nanocarboxylated nitrile powder After rubber particles VP501 and 1 part by weight of 2-isopropylimidazole were mixed in a high-speed mixer at a speed of 24,000 r/min for 30 seconds, 2-isopropylimidazole was adsorbed on the nanocarboxylic nitrile powder rubber particles VP501 to obtain the composite Curing accelerator G.

Preparation Comparative Example 2

A composite curing accelerator H. The preparation method of the composite curing accelerator H includes: mixing 12 parts by weight of nano titanium dioxide and 1 part by weight of tetradecyldimethyl tertiary amine through a high-speed mixer at a speed of 24000 r/min. After mixing for 30 seconds, the composite curing accelerator H was obtained.

Example 1

A powder coating, which includes the following components in parts by weight: 35 parts by weight of bisphenol A epoxy resin NPES-904HP, 15 parts by weight of bisphenol A epoxy resin HY9022, 2 parts by weight of substituted dicyandiamide, 8 parts by weight of composite curing accelerator A, 0.1 part by weight of nanoboehmite, 0.1 part by weight of benzoin, 0.2 parts by weight of leveling agent GLP5888 and 0.1 part by weight of iron yellow.

The preparation method of the powder coating includes: mixing the above components, melting and extruding with a twin-screw at 90°C, sequentially pressing, cooling, and pulverizing until the particle size is 10-100 μm and passing through a 180-mesh screen to obtain the powder coating.

Example 2

A powder coating, which includes the following components in parts by weight: 35 parts by weight of bisphenol A epoxy resin NPES-904HP, 15 parts by weight of bisphenol A epoxy resin HY9022, 30 parts by weight of carboxyl polyester resin, 3 parts by weight of triglycidyl isocyanurate, 0.5 parts by weight of composite curing accelerator B, 1 part by weight of nanoboehmite, 0.2 parts by weight of benzoin, 0.5 parts by weight of leveling agent GLP5888 and 0.2 parts by weight of iron yellow.

The only difference between the preparation method of the powder coating and Example 1 is that the components of the powder coating are the components provided in this example, and other process parameters and steps are the same as those in Example 1.

Example 3

A powder coating, the powder coating includes the following components in parts by weight: 40 parts by weight of bisphenol A epoxy resin NPES-904F, 10 parts by weight of bisphenol A epoxy resin HY902, 50 parts by weight of carboxyl acrylic resin, substituted 1 part by weight of dicyandiamide, 2 parts by weight of triglycidyl isocyanurate, 8 parts by weight of composite curing accelerator C, 3 parts by weight of nanoboehmite, 0.2 parts by weight of benzoin, 0.5 parts by weight of leveling agent GLP5888 and Iron yellow 0.2 parts by weight.

The only difference between the preparation method of the powder coating and Example 1 is that the components of the powder coating are the components provided in this example, and other process parameters and steps are the same as those in Example 1.

Example 4

A powder coating, which includes the following components by weight: 45 parts by weight of bisphenol A epoxy resin NPES-904F, 5 parts by weight of novolac epoxy resin KD-211D, and 40 parts by weight of hydroxyl polyester resin parts by weight, 13 parts by weight of phenolic hydroxyl resin, 12 parts by weight of blocked polyisocyanate, 6 parts by weight of composite curing accelerator D, 5 parts by weight of nano-silica, 0.5 parts by weight of benzoin, 1 parts by weight of leveling agent GLP5881 and 0.5 parts by weight of iron yellow .

The difference between the preparation method of the powder coating and Example 1 is only that the components of the powder coating are the components provided in this example, and other process parameters and steps are the same as those in Example 1.

Example 5

A powder coating, which includes the following components by weight: 40 parts by weight of bisphenol A epoxy resin NPES-904H, 10 parts by weight of novolac epoxy resin KD-211H, and 40 parts by weight of hydroxyl polyester resin 1.5 parts by weight of substituted dicyandiamide, 12 parts by weight of blocked polyisocyanate, 5 parts by weight of composite curing accelerator E, 3 parts by weight of nano-silica, 0.3 parts by weight of benzoin, 0.5 parts by weight of leveling agent GLP5888 and iron yellow 0.3 parts by weight.

The only difference between the preparation method of the powder coating and Example 1 is that the components of the powder coating are the components provided in this example, and other process parameters and steps are the same as those in Example 1.

Example 6

A powder coating and its preparation method, the only difference from Example 3 is that in this example, the composite curing accelerator C is 12 parts by weight, and other raw materials, process parameters and steps are the same as Example 3.

Example 7

A powder coating and its preparation method. The only difference between it and Example 3 is that in this example, the bisphenol A type epoxy tree NPES-904F is 50 parts by weight and bisphenol A type epoxy tree HY902 is not added. Other raw materials , process parameters and steps are the same as those in Example 3.

Example 8

A powder coating and its preparation method, which differs from Example 3 only in that equal amounts of composite curing accelerator C are replaced by composite curing accelerator F. Other raw materials, process parameters and steps are the same as in Example 3.

Comparative example 1

A powder coating and its preparation method, which differs from Example 2 only in that equal amounts of composite curing accelerator B are replaced by composite curing accelerator G. Other raw materials, process parameters and steps are the same as in Example 2.

Comparative example 2

A powder coating and its preparation method, which differs from Example 3 only in that equal amounts of composite curing accelerator C are replaced by composite curing accelerator H. Other raw materials, process parameters and steps are the same as in Example 3.

Comparative example 3

A powder coating, the powder coating includes the following components in parts by weight: 40 parts by weight of bisphenol A epoxy resin NPES-904F, 10 parts by weight of bisphenol A epoxy resin HY902, 50 parts by weight of carboxyl acrylic resin, substituted 1 part by weight of dicyandiamide, 2 parts by weight of triglycidyl isocyanurate, 7.4 parts by weight of nanocarboxylated nitrile powder rubber particles VP501, 0.6 parts by weight of tetradecyldimethyltertiary amine, 3 parts by weight of nanoboehmite parts by weight, 0.2 parts by weight of benzoin, 0.5 parts by weight of leveling agent GLP5888 and 0.2 parts by weight of iron yellow.

The difference between the preparation method of the powder coating and Example 3 is only that the components of the powder coating are the components provided in this comparative example, and other process parameters and steps are the same as in Example 3.

The powder coatings provided in Examples 1-8 and Comparative Examples 1-3 were coated on the glass fiber reinforced composite material substrate using a high-voltage electrostatic method, and then infrared curing was performed. The curing power was 20kW/m ² ; The curing time is 5 minutes, and the coating is obtained. The performance of the coating is tested according to the following method. The test results are shown in Table 1:

(1) Use DSC (Manufacturer: TAInstruments, Model: Q1000) to measure the curing degree and curing temperature of the coating. The specific operations are as follows:

a. Coating curing degree test: The total heat released when the uncured powder coating is completely cured is ΔH ₀ (J/g) and the remaining reaction heat when it is not fully cured is _ΔHR (J/g). Layer solidification degree solidification degree a=(ΔH _{0 -ΔHR} )/ΔH ₀ ;

b. Curing temperature: The curing temperature of the powder coating is obtained by conducting a non-isothermal temperature rise test on the uncured powder coating through DSC;

(2) Coating thickness: tested according to GB/T 1764;

(3) Adhesion: According to the GB/T 9286-2021 test, a cutting knife is used to cut the surface of the coating to form a grid pattern. The cutting edge of the coating is completely smooth and is level 0; there is a small amount of coating peeling off at the intersection of the cuts, which is affected The cross-cutting area is less than 5%, which is Level 1; there is coating peeling off at the intersection of the cuts or along the edges of the cuts, and the affected cross-cutting area is greater than 5% and less than 15%, which is Level 2;

(4) Impact performance: According to the GB/T 1732 test, record the height of the weight falling on the test plate, and observe whether there are cracks, peeling, etc. in the coating;

(5) Solvent resistance: According to the GB/T 23989-2009 test, wipe 100 times with MEK to observe whether the coating has lost luster and softened;

(6) Acid resistance: According to the GB/T 9274-1988 test, use 3wt% HCl to soak for 240h and observe whether the coating has blistering and falling off;

(7) Alkali resistance: According to the test of GB/T 9274-1988, soak in 5wt% NaOH for 240h and observe whether the coating has blistering and falling off;

(8) Moisture and heat resistance: According to the GB/T 1740-2007 test, treat the coating for 1000 hours at a temperature of 47°C and a relative humidity of 96%, and observe whether the coating has loss of gloss and bubbling;

(9) Neutral salt spray resistance, according to the GB/T 1771-2007 test, use a sodium chloride aqueous solution with a mass concentration of 50g/L for 1000h, and observe whether the coating has rust spots and blistering.

Table 1

It can be seen from the test data in Table 1 that the powder coating provided by the present invention has a fast curing speed and a low curing temperature. The cured coating has good impact strength, adhesion, solvent resistance, acid resistance, alkali resistance, and moisture and heat resistance. and resistant to neutral salt spray. From the comparison between Example 6 and Example 3, it can be seen that if the composite curing accelerator is added in too much amount, the nano-rubber particles will agglomerate, and their dispersion in the powder coating will become poor. The liquid tertiary amine catalyst in the powder coating will The dispersion of the powder coating becomes worse, causing the curing temperature of the powder coating to increase, the curing speed to slow down, and the impact strength and adhesion of the coating to become worse; from the comparison between Example 7 and Example 3, it can be seen that the low viscosity epoxy resin It can improve the activity of powder coatings and promote the curing of powder coatings. Removing low-viscosity epoxy resin will cause the curing temperature of powder coatings to increase and the degree of curing to decrease. The solvent resistance, acid resistance, alkali resistance, and moisture and heat resistance of the coating will be reduced. and salt spray resistance becomes worse; from the comparison between Example 8 and Example 3, it can be seen that the mass ratio of nano rubber particles to liquid tertiary amine catalyst is too small, which will cause the nano rubber particles to be unable to fully adsorb and disperse the liquid tertiary amine catalyst. , causing the curing temperature of the powder coating to increase, the curing speed to slow down, and the adhesion of the coating to deteriorate.

From the comparison between Example 2 and Comparative Example 1, it can be seen that the liquid tertiary amine catalyst has higher catalytic efficiency than 2-isopropylimidazole, which can effectively shorten the curing time of the powder coating and lower the curing temperature. The formed coating has excellent physical and chemical properties.

From the comparison between Example 3 and Comparative Example 2, it can be seen that the use of nano-rubber particles can adsorb liquid tertiary amine catalysts on the surface without affecting its performance in powder coatings. However, after replacing it with nano-titanium dioxide, nano-titanium dioxide has no effect on liquid tertiary amine catalysts. The adsorption performance of amine catalysts is poor, and the liquid tertiary amine catalyst cannot be completely adsorbed and dispersed, causing the nano titanium dioxide and the liquid tertiary amine catalyst to stick to each other and agglomerate, unable to effectively exert their catalytic effect, resulting in poor coating performance and powder coating The curing temperature increases and the curing speed slows down.

From the comparison between Example 3 and Comparative Example 3, it can be seen that when nano rubber particles and liquid tertiary amine catalysts are directly added, the liquid tertiary amine catalyst cannot be evenly dispersed in the powder coating, causing the curing temperature of the powder coating to increase and the curing speed to increase. Slows down and coating performance deteriorates.

The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above embodiments, but the present invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above detailed process equipment and process flow. process can be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacement of raw materials of the product of the present invention, addition of auxiliary ingredients, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. A powder coating, characterized in that the powder coating includes the following components in parts by weight: 50-100 parts by weight of matrix resin, 2-25 parts by weight of curing agent, 0.5-8 parts by weight of composite curing accelerator and nanometer Filler 0.1-5 parts by weight; The composite curing accelerator includes nano-rubber particles and a liquid tertiary amine catalyst loaded on the nano-rubber particles. 2. The powder coating according to claim 1, wherein the matrix resin includes a combination of a first resin and a second resin; Preferably, based on the mass of the matrix resin being 100%, the mass of the second resin is ≤50%; Preferably, the first resin includes a combination of low viscosity epoxy resin and high viscosity epoxy resin; Preferably, based on the mass of the first resin being 100%, the mass of the low viscosity epoxy resin is 10-30%; Preferably, the low-viscosity epoxy resin includes any one or a combination of at least two of the first bisphenol A-type epoxy resin, bisphenol F-type epoxy resin or novolac epoxy resin; Preferably, the high viscosity epoxy resin includes a second bisphenol A-type epoxy resin; Preferably, the melt viscosity of the first bisphenol A-type epoxy resin and the novolac epoxy resin at 150°C is each independently 300-4000 mPa.s; Preferably, the melt viscosity of the high-viscosity epoxy resin at 150°C is 6000-13000 mPa.s; Preferably, the second resin includes any one or a combination of at least two of carboxyl polyester resin, hydroxyl polyester resin or carboxyl acrylic resin; Preferably, the acid value of the carboxyl polyester resin is 50-70 mg KOH/g; Preferably, the hydroxyl value of the hydroxyl polyester resin is 100-220 mg KOH/g; Preferably, the acid value of the carboxy acrylic resin is 140-200 mg KOH/g. 3. The powder coating according to claim 1 or 2, characterized in that the curing agent includes triglycidyl isocyanurate, substituted dicyandiamide, blocked polyisocyanate, dodecanedioic acid, dicarboxylic acid Any one or a combination of at least two of acid dihydrazide, acid anhydride, novolac resin, phenolic hydroxyl resin or hydroxyalkyl amide. 4. The powder coating according to any one of claims 1 to 3, characterized in that the nano rubber particles include nano nitrile powder rubber particles, nano carboxyl nitrile powder rubber particles, nano styrene butadiene powder rubber particles or Any one or a combination of at least two types of core-shell nano-rubber particles, preferably nano-nitrile powder rubber particles; Preferably, the core-shell nano-rubber particles include butadiene core-shell rubber particles and/or acrylic core-shell rubber particles; Preferably, the particle size of the nano-rubber particles is 50-500 nm; Preferably, the liquid tertiary amine catalyst includes any one of linear alkyl tertiary amines, triethanolamine, triethylenediamine, dimethylaminomethylphenol or tris(dimethylaminomethyl)phenol or A combination of at least two; Preferably, the linear alkyl-containing tertiary amine includes dodecyldimethyltertiary amine, cetyldimethyltertiary amine, tetradecyldimethyltertiary amine or octadecyldimethylamine. Any one or a combination of at least two tertiary amines; Preferably, the mass ratio of the nano-rubber particles and the liquid tertiary amine catalyst is (4-15):1; Preferably, the nanofiller includes any one or a combination of at least two of nanoboehmite, nanocellulose or nanosilica. 5. The powder coating according to any one of claims 1 to 4, characterized in that the composite curing accelerator is prepared by the following method, which method includes: combining the nano rubber particles and the liquid tertiary amine The liquid tertiary amine catalyst is mixed, and the liquid tertiary amine catalyst is adsorbed on the nano rubber particles to obtain the composite curing accelerator; Preferably, the mixing time is 20-60s; Preferably, the mixing temperature is 20-35°C. 6. The powder coating according to any one of claims 1 to 5, characterized in that the powder coating further includes 0.1-0.5 parts by weight of degassing agent, 0.2-1 parts by weight of leveling agent and 0.1 parts by weight of pigment. -0.5 parts by weight. 7. The powder coating according to claim 6, wherein the degassing agent includes benzoin; Preferably, the leveling agent includes any one or a combination of at least two of acrylic polymer leveling agents; Preferably, the pigment includes any one or a combination of at least two of rutile titanium dioxide, iron yellow, phthalocyanine blue, phthalocyanine green, iron oxide red or ultramarine blue. 8. A preparation method of powder coating according to any one of claims 1 to 7, characterized in that the preparation method includes: mixing matrix resin, curing agent, composite curing accelerator and nano filler and then melting and extruding out, and then perform tableting, cooling, crushing and screening in sequence to obtain the powder coating. 9. The preparation method according to claim 8, characterized in that the mixed materials further include a degassing agent, a leveling agent and a pigment; Preferably, the melt extrusion temperature is 80-110°C; Preferably, the particle size is 10-100 μm through the crushing, and more preferably 20-80 μm; Preferably, the mesh size of the screening mesh is 140-200 mesh. 10. The powder coating according to any one of claims 1 to 7 is used for coating heat-sensitive substrates.