阅读说明：本技术 一种两涂一烤的粉末涂料及其制备方法 (Powder coating with two coating layers and one baking layer and preparation method thereof ) 是由 凌垄灏 巴旭民 陈武 黄崇瑶 施晓杰 叶赛男 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种两涂一烤的粉末涂料,包括底层粉末涂料和面层粉末涂料,所述底层粉末涂料包括以下重量百分比的原料：聚酯树脂30％-40％、环氧树脂30-40％、颜料10-20％、防腐填料15-25％、膨润土0.2％-0.5％、助剂1％-5％；及占上述原料总重量2～4‰的纳米氧化硅；所述面层粉末涂料包括以下原料：聚酯树脂、固化剂、颜料、填料、脱气蜡、助剂,及占聚酯树脂、固化剂、颜料、填料、脱气蜡、助剂总重量2～4‰的气相白炭黑；其不含VOC,绿色环保；可采用两涂一烤工艺进行施工,所得到的涂层的边角覆盖率高,防腐性能好,所喷涂的产品使用寿命长,且涂层表面平整,光泽度高,产品外观良好。(The invention discloses a two-coating one-baking powder coating, which comprises a bottom layer powder coating and a top layer powder coating, wherein the bottom layer powder coating comprises the following raw materials in percentage by weight: 30-40% of polyester resin, 30-40% of epoxy resin, 10-20% of pigment, 15-25% of anticorrosive filler, 0.2-0.5% of bentonite and 1-5% of auxiliary agent; and nano silicon oxide accounting for 2-4 per mill of the total weight of the raw materials; the surface powder coating comprises the following raw materials: polyester resin, a curing agent, pigment, filler, degassed wax, an auxiliary agent and fumed silica accounting for 2-4 per mill of the total weight of the polyester resin, the curing agent, the pigment, the filler, the degassed wax and the auxiliary agent; it does not contain VOC, and is green and environment-friendly; the coating can be constructed by adopting a two-coating one-baking process, the obtained coating has high corner coverage rate and good corrosion resistance, the sprayed product has long service life, the surface of the coating is smooth, the glossiness is high, and the product has good appearance.)

1. The powder coating with two coating layers and one baking layer is characterized by comprising a bottom layer powder coating and a top layer powder coating, wherein the bottom layer powder coating comprises the following raw materials in percentage by weight: 30-40% of polyester resin, 30-40% of epoxy resin, 10-20% of pigment, 15-25% of anticorrosive filler, 0.2-0.5% of bentonite and 1-5% of auxiliary agent; and nano silicon oxide accounting for 2-4 per mill of the total weight of the polyester resin, the epoxy resin, the pigment, the anticorrosive filler, the bentonite and the auxiliary agent.

2. The two-coat one-bake powder coating of claim 1, wherein the top powder coating comprises the following raw materials in weight percent: 60-65% of polyester resin, 4-5% of curing agent, 8-18% of pigment, 15-25% of filler, 1-2% of degassed wax and 1-5% of auxiliary agent; and fumed silica which accounts for 2-4 per mill of the total weight of the polyester resin, the curing agent, the pigment, the filler, the degassed wax and the auxiliary agent.

3. The two-coat one-bake powder coating of claim 1, wherein the polyester resin in the primer powder coating is a hybrid epoxy-curing polyester resin.

4. The two-coat one-bake powder coating of claim 1 or 2, wherein the polyester resin in the top coat powder coating is an outdoor type TGIC cured polyester resin.

5. The two-coating one-baking powder coating according to claim 1 or 2, wherein the auxiliary agent in the bottom layer powder coating and the top layer coating is any one or more of a degassing agent and a leveling agent.

6. A two-coat one-bake powder coating according to claim 1 or 2, wherein the anti-corrosive filler in the primer powder coating is any one or more of zinc phosphate, modified zinc phosphate, and aluminum tripolyphosphate.

7. A two-coat one-bake powder coating according to claim 1 or 2, wherein the curing agent in the top coat powder coating is TGIC curing agent.

8. A method of preparing a two-coat one-bake powder coating according to any of claims 1-7, comprising the steps of:

(1) uniformly mixing polyester resin, epoxy resin, pigment, anticorrosive filler, bentonite and an auxiliary agent according to the formula amount, then carrying out melt extrusion, crushing extruded materials after tabletting, crushing crushed tablets by a mill, adding nano-alumina according to the formula amount in the crushing process, and sieving to obtain a bottom layer powder coating;

(2) uniformly mixing the polyester resin, the curing agent, the pigment, the filler, the degassed wax and the auxiliary agent according to the formula amount, then carrying out melt extrusion, crushing the extruded material after tabletting, crushing the crushed material sheet by a mill, adding the fumed silica according to the formula amount in the crushing process, and sieving to obtain the surface layer powder coating.

9. A method of preparing a two-coat one-bake powder coating according to claim 8, wherein in steps (1) and (2), the melt extrusion conditions are: the temperature of the feeding section is 25-35 ℃, the temperature of the melting section is 105-115 ℃, and the temperature of the discharging section is 95-105 ℃.

10. A coating formed from the two-coat one-bake powder coating of any one of claims 1-7.

Technical Field

The invention belongs to the technical field of powder coatings, and particularly relates to a powder coating with two coatings and one baking and a preparation method thereof.

Background

The paint has a mature two-coating one-baking process during construction, but the paint belongs to flammable and explosive products, a solvent is volatilized in the using process, the environment is polluted, meanwhile, the physical health of constructors is damaged, the production efficiency of the paint is low, and the paint cannot be recycled.

The powder coating has a mature two-coating and two-baking process during construction, namely two-time spraying and two-time baking, so that the energy consumption is high and the production efficiency is low.

Disclosure of Invention

In order to solve the technical problems, the invention provides a two-coating one-baking powder coating which can be constructed by adopting a two-coating one-baking process, does not contain VOC, is simple to construct and is green and environment-friendly.

The technical scheme adopted by the invention is as follows:

the two-coating one-baking powder coating comprises a bottom layer powder coating and a top layer powder coating, wherein the bottom layer powder coating comprises the following raw materials in percentage by weight: 30-40% of polyester resin, 30-40% of epoxy resin, 10-20% of pigment, 15-25% of anticorrosive filler, 0.2-0.5% of bentonite and 1-5% of auxiliary agent; and nano silicon oxide accounting for 2-4 per mill of the total weight of the polyester resin, the epoxy resin, the pigment, the anticorrosive filler, the bentonite and the auxiliary agent.

The surface powder coating comprises the following raw materials in percentage by weight: 60-65% of polyester resin, 4-5% of curing agent, 8-18% of pigment, 15-25% of filler, 1-2% of degassed wax and 1-5% of auxiliary agent; and fumed silica which accounts for 2-4 per mill of the total weight of the polyester resin, the curing agent, the pigment, the filler, the degassed wax and the auxiliary agent.

The polyester resin in the bottom powder coating is mixed epoxy curing polyester resin.

The polyester resin in the surface layer powder coating is outdoor TGIC curing polyester resin.

The auxiliary agents in the bottom layer powder coating and the surface layer powder coating are any one or more of degassing agent and flatting agent.

The pigment in the bottom layer powder coating and the surface layer powder coating is any one or more of titanium dioxide, carbon black, phthalocyanine green, phthalocyanine blue, ultramarine, iron oxide red, iron oxide yellow, isoindolinone and bismuth vanadate series yellow, Diketopyrrolopyrrole (DPP), quinacridone (di) ketone and beta-hydroxynaphthoic acid red.

The anticorrosive filler in the bottom layer powder coating is any one or more of zinc phosphate, modified zinc phosphate and aluminum tripolyphosphate.

The curing agent in the surface layer powder coating is TGIC curing agent.

The filler in the surface layer powder coating is any one or more of high-light barium and precipitated barium.

The invention also provides a preparation method of the two-coating one-baking powder coating, which comprises the following steps:

(1) uniformly mixing polyester resin, epoxy resin, pigment, anticorrosive filler, bentonite and an auxiliary agent according to the formula amount, then carrying out melt extrusion, crushing extruded materials after tabletting, crushing crushed tablets by a mill, adding nano-alumina according to the formula amount in the crushing process, and sieving to obtain a bottom layer powder coating, wherein the average particle size of the bottom layer powder coating is controlled to be 30-40 micrometers;

(2) uniformly mixing the polyester resin, the curing agent, the pigment, the filler, the degassed wax and the auxiliary agent according to the formula amount, then carrying out melt extrusion, crushing the extruded material after tabletting, crushing the crushed material sheet by a mill, adding the fumed silica according to the formula amount in the crushing process, and sieving to obtain the surface layer powder coating, wherein the average particle size is controlled to be 30-40 micrometers.

In the step (1) and the step (2), the melt extrusion conditions are as follows: the temperature of the feeding section is 25-35 ℃, the temperature of the melting section is 105-115 ℃, and the temperature of the discharging section is 95-105 ℃; preferably, the temperature of the feeding section is 30 ℃, the temperature of the melting section is 110 ℃, and the temperature of the discharging section is 100 ℃.

The invention also provides a coating formed by the two-coating one-baking powder coating, the coating has high corner coverage rate and good corrosion resistance, the sprayed product has long service life, the surface of the coating is smooth, the glossiness is high, the appearance effect of the product is better, and the coating can be applied to the fields of engineering machinery and the like.

The construction method of the two-coating one-baking powder coating comprises the following steps: pre-treating a substrate → spraying a bottom powder coating → spraying a surface powder coating → curing.

The substrate pretreatment mode comprises the following steps: chemical treatment means or physical treatment means.

The chemical treatment mode comprises a phosphorization treatment or a treatment using silane.

The physical treatment mode comprises sand blasting, shot blasting or grinding treatment.

The curing conditions are as follows: keeping the temperature at 160-220 ℃ for 15-20 min, preferably keeping the temperature at 200 ℃ for 15 min. Due to the differences of the structure, the size, the wall thickness and the like of the construction workpiece, the curing temperature needs to be adjusted in the range according to specific conditions on site to ensure that the coating is completely cured, but the minimum temperature is not lower than 160 ℃, and the maximum temperature is not higher than 220 ℃.

According to the invention, bentonite is added in the formula of the bottom powder coating of the two-coating one-baking powder coating, so that the viscosity of the bottom powder coating is increased, and the possibility of the bottom powder coating migrating to a surface layer can be effectively reduced in the final curing process; the corner coverage rate is improved, and the service life of the product is prolonged by matching with the addition of the anticorrosive filler in the formula; and when the bottom layer powder coating is prepared, the nano aluminum oxide is added in the process of crushing the material sheet to improve the electrification performance of the bottom powder and improve the powder loading amount when the surface layer powder coating is sprayed.

According to the formula of the surface layer powder coating with two-coating one-baking powder coating, the degassing wax is added to reduce the viscosity of the surface layer powder coating, so that degassing of the bottom layer powder coating during final curing is facilitated, a viscosity difference is formed between the bottom layer powder coating and the bottom layer powder coating, the bottom layer powder coating is prevented from migrating into the surface layer powder coating during curing, and the appearance of the coating is improved; when the surface powder coating is prepared, the fumed silica is added in the process of crushing the sheet, and the fumed silica and the degassed wax in the formula of the surface powder coating generate a synergistic effect to reduce the electrification of the surface powder coating, so that a potential difference is formed between the surface powder coating and the bottom powder coating, and the surface powder coating is effectively powdered.

Compared with the prior art, the two-coating one-baking powder coating provided by the invention has the following advantages:

(1) compared with paint, the powder coating does not contain VOC, and belongs to green environment-friendly coating

(2) The surface powder can be directly sprayed after the bottom powder is sprayed, so that the pre-curing link after the bottom powder is sprayed is omitted, and energy conservation and consumption reduction are realized;

(3) the coating formed by the construction of the two-coating one-baking process has high corner coverage rate and good corrosion resistance, and the sprayed product has long service life, smooth surface, high glossiness and better appearance effect, and can be applied to the fields of engineering machinery and the like;

(4) can be recycled and has high utilization rate.

Detailed Description

The present invention will be described in detail with reference to examples.

The anticorrosive fillers, leveling agents and degassing agents used in the examples and comparative examples are zinc phosphate, acrylic ester and benzoin respectively.

The mixed epoxy curing polyester resin is purchased from Anhui Shenjian New Material GmbH; outdoor TGIC cured polyester resin was purchased from Anhuishen Sword New materials GmbH; the epoxy resin is E-12; other respective starting materials are commercially available unless otherwise specified.

Example 1

The two-coating one-baking powder coating comprises a bottom layer powder coating and a top layer powder coating, wherein the bottom layer powder coating comprises the following raw materials in percentage by weight: 33% of mixed epoxy curing polyester resin, 33% of epoxy resin, 15% of titanium dioxide, 0.1% of carbon black, 17% of anticorrosive filler, 0.4% of bentonite, 1% of leveling agent and 0.5% of degassing agent; and nano alumina accounting for 3 per mill of the total weight of the polyester resin, the epoxy resin, the titanium dioxide, the carbon black, the anticorrosive filler, the bentonite, the flatting agent and the degassing agent;

the surface powder coating comprises the following raw materials in percentage by weight: 60% of outdoor TGIC curing polyester resin, 4.5% of TGIC curing agent, 15% of titanium dioxide, 0.1% of carbon black, 18% of high-light barium, 1% of degassed wax, 1% of leveling agent and 0.4% of degassing agent; and fumed silica which accounts for 3 per mill of the total weight of the polyester resin, the TGIC curing agent, the titanium dioxide, the carbon black, the high-light barium, the degassing wax, the flatting agent and the degassing agent.

The preparation method of the bottom layer powder coating comprises the following steps: adding polyester resin, epoxy resin, titanium dioxide, carbon black, anticorrosive filler, bentonite, a leveling agent and a degassing agent according to the formula ratio, fully mixing on a mixer, and then performing melt extrusion through an extruder, wherein the melt extrusion conditions are as follows: the temperature of the feeding section is 30 ℃, the temperature of the melting section is 110 ℃, and the temperature of the discharging section is 100 ℃; and tabletting the extruded material, crushing, grinding the crushed material sheet by a mill, adding nano alumina with the formula amount in the crushing process, and sieving to obtain the bottom layer powder coating, wherein the average particle size of the bottom layer powder coating is controlled to be 30-40 micrometers.

The preparation method of the surface powder coating comprises the following steps: adding polyester resin, TGIC curing agent, titanium dioxide, carbon black, high light barium, degassing wax, flatting agent and degassing agent according to the formula ratio, fully mixing on a mixer, and then performing melt extrusion through an extruder, wherein the melt extrusion conditions are as follows: the temperature of the feeding section is 30 ℃, the temperature of the melting section is 110 ℃, and the temperature of the discharging section is 100 ℃; and tabletting the extruded material, crushing, grinding the crushed material sheet by a grinding machine, adding the fumed silica with the formula amount in the crushing process, and sieving to obtain the surface layer powder coating, wherein the average particle size of the surface layer powder coating is controlled to be 30-40 micrometers.

Comparative example 1

The two-coating one-baking powder coating comprises a bottom layer powder coating and a top layer powder coating, wherein the bottom layer powder coating comprises the following raw materials in percentage by weight: 33.2 percent of mixed epoxy curing polyester resin, 33.2 percent of epoxy resin, 15 percent of titanium dioxide, 0.1 percent of carbon black, 17 percent of anticorrosive filler, 1 percent of flatting agent and 0.5 percent of degassing agent; and nano aluminum oxide accounting for 3 per mill of the total weight of the polyester resin, the epoxy resin, the titanium dioxide, the carbon black, the anticorrosive filler, the leveling agent and the degassing agent; the formulation and preparation method of the finish powder coating are the same as in example 1.

The preparation method of the bottom layer powder coating comprises the following steps: adding the polyester resin, the epoxy resin, the titanium dioxide, the carbon black, the anticorrosive filler, the leveling agent and the degassing agent according to the formula ratio, fully mixing on a mixer, and then performing melt extrusion through an extruder, wherein the melt extrusion conditions are as follows: the temperature of the feeding section is 30 ℃, the temperature of the melting section is 110 ℃, and the temperature of the discharging section is 100 ℃; and tabletting the extruded material, crushing, grinding the crushed material sheet by a mill, adding nano alumina with the formula amount in the crushing process, and sieving to obtain the bottom layer powder coating, wherein the average particle size of the bottom layer powder coating is controlled to be 30-40 micrometers.

Comparative example 2

The rest is the same as the example 1, except that the formulation of the bottom layer powder coating does not contain 3 per mill of nano alumina of the total weight of polyester resin, epoxy resin, titanium dioxide, carbon black, anticorrosive filler, bentonite, flatting agent and degassing agent; the formula of the surface powder coating does not contain fumed silica which accounts for 3 per mill of the total weight of polyester resin, TGIC curing agent, titanium dioxide, carbon black, high-light barium, degassed wax, flatting agent and degassing agent.

Comparative example 3

The rest is the same as the example 1, except that the surface layer powder coating comprises the following raw materials in percentage by weight: 60% of outdoor TGIC curing polyester resin, 4.5% of TGIC curing agent, 15% of titanium dioxide, 0.1% of carbon black, 19% of high-light barium, 1% of leveling agent, 0.4% of degassing agent and 3 per mill of fumed silica of the total weight of the raw materials.

Comparative example 4

The rest is the same as the example 1, except that the surface layer powder coating comprises the following raw materials in percentage by weight: 50% of outdoor TGIC curing polyester resin, 3.8% of TGIC curing agent, 15% of titanium dioxide, 0.1% of carbon black, 28.7% of high-light barium, 1% of degassed wax, 1% of flatting agent, 0.4% of degassing agent and fumed silica accounting for 3 per mill of the total weight of the raw materials.

Comparative example 5

The rest is the same as the example 1, except that the surface layer powder coating comprises the following raw materials in percentage by weight: 70 percent of outdoor TGIC curing polyester resin, 5.3 percent of TGIC curing agent, 15 percent of titanium dioxide, 0.1 percent of carbon black, 7.2 percent of high-light barium, 1 percent of degassed wax, 1 percent of flatting agent, 0.4 percent of degasifying agent and 3 per mill of fumed silica of the total weight of the raw materials.

The powder coatings in example 1 and comparative examples 1-5 were applied to the surface of a steel plate of 150mm × 75mm by the following method, respectively, of polishing the steel plate → spraying the powder coating for the bottom layer → spraying the powder coating for the top layer → curing at 200 ℃ for 15min, the amounts of the powder coating for the bottom layer and the powder coating for the top layer being 10g and 15g, respectively; the properties of the resulting coating are shown in table 1.

TABLE 1

It can be seen from table 1 that the bentonite is added in the formulation of the bottom powder coating, so that the viscosity of the bottom powder coating is increased, the corner coverage rate is improved, the corrosion of the corners is slowed down, and the service life of the product is prolonged. When the bottom layer powder coating is prepared, the nano aluminum oxide is added in the process of crushing the material sheet, and meanwhile, when the surface layer powder coating is prepared, the gas-phase white carbon black is added in the process of crushing the material sheet, so that the thickness of the coating can be improved, and the gloss and corner coverage rate of a sample plate are improved. The addition of the degassing wax in the formula of the surface layer powder coating can reduce the viscosity of the surface layer coating, is beneficial to degassing of the bottom layer powder coating during final curing, and simultaneously forms a viscosity difference with the bottom layer coating to prevent the bottom layer powder coating from migrating into the surface layer powder coating during curing, thereby improving the gloss of the coating. The polyester content in the flour exceeds the recommended range, and certain influence is exerted on the appearance and the corner coverage rate of a coating film.

The above detailed description of a two-coat one-bake powder coating and the method of making the same, with reference to the examples, is illustrative and not restrictive, and several examples are set forth with the limits of the invention, so that variations and modifications may be made without departing from the general inventive concept and, therefore, fall within the scope of the invention.