CN109365237B - Powder coating curing method - Google Patents
Powder coating curing method Download PDFInfo
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- CN109365237B CN109365237B CN201811258480.6A CN201811258480A CN109365237B CN 109365237 B CN109365237 B CN 109365237B CN 201811258480 A CN201811258480 A CN 201811258480A CN 109365237 B CN109365237 B CN 109365237B
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- Prior art keywords
- powder coating
- radiation
- curing
- coating
- melting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
- B05D1/12—Applying particulate materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
- B05D3/061—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using U.V.
- B05D3/065—After-treatment
- B05D3/067—Curing or cross-linking the coating
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Paints Or Removers (AREA)
Abstract
The invention relates to the technical field of coating curing, in particular to a powder coating curing method, which comprises the steps of irradiating the powder coating which is preheated by adopting near-infrared rays at normal temperature in the step (2) for 2s, combining UV radiation with the preheated powder coating, increasing heat, irradiating and curing under the UV radiation after melting and leveling, and controlling the UV radiation dose before and after melting to ensure that the glossiness (60 ℃) of a cured and formed coating is stabilized between 95 and 105 percent, thereby reducing the amplitude and the preparation difficulty of a specific coating.
Description
Technical Field
The invention relates to the technical field of paint curing, in particular to a powder paint curing method.
Background
In the metal coating, the decorative or functional surface coating formed by spraying the powder coating is widely applied. The method has high efficiency and better environmental protection performance; meanwhile, a great deal of development and research are carried out on the powder coating, so that the powder coating capable of meeting various requirements is available, and the raw material cost of spraying treatment is reduced. At present, the powder coating curing method is as follows: firstly, melting the powder sprayed on the surface of the substrate by heating to a temperature higher than the glass transition temperature or the melting point temperature of the powder coating, and then realizing a cooling and curing process, such as a convection furnace, an infrared radiator or a combination of the convection furnace and the infrared radiator as a heat source to realize thermosetting treatment; in this process, the powder coating is usually heated at 140-.
In view of this, researchers have studied the curing method of powder paint after spraying on the surface of a substrate, for example, the curing method of powder paint of patent No. ZL99813212.8, which uses near infrared range ray (NIR ray) radiation to cure the powder paint, realizes the curing process by reaching the surface temperature of the powder sprayed substrate by radiation within a certain time, and controlling the content of barium sulfate and/or alumina, carbon black, etc., so that the curing time can reach 5s under the same radiation condition as compared with the existing curing method. Then applying the powder coating composition to the surface of the substrate as in the powder coating preparation method of patent No. 200580019828.0; irradiating the applied powder coating composition with high energy radiation at near ambient temperature; increasing the temperature to plasticize, melt and level the powder coating composition particles to a molten coating and/or to solidify the molten coating; by varying the UV-irradiation time and intensity, control of the coating gloss to any level is achieved. Therefore, the prior art has made a great deal of research on the control condition of the gloss level of the coating by controlling the curing time and the energy in the curing process; however, in the curing process, indexes such as color, luster, hardness and toughness of the coating are seriously affected, and under which conditions the coating is cured, the stability of performance indexes is realized, so that the generation of the coating with stable glossiness and performance indexes can be ensured, the control difficulty of parameter indexes in the curing process can be reduced, the construction is convenient, and the method becomes a key point for the research of the current powder coating curing treatment.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a powder coating curing method.
The method is realized by the following technical scheme:
a method of curing a powder coating comprising the steps of:
(1) spraying the powder coating on the surface of a base material by a spray gun machine;
(2) irradiating the powder coating by adopting near-infrared rays with the intensity distribution within the wavelength range of 800-900nm for 2s in a normal-temperature environment, then irradiating the powder coating by adopting UV radiation, increasing the temperature to melt and level the powder coating to form a molten coating, and curing under the irradiation of the UV radiation;
wherein, before melting, the irradiation dose of the UV radiation is 200-230mJ/cm2(ii) a After melting, the UV radiation irradiation dose is adjusted to 35-45mJ/cm2。
According to the method, the gloss of the surface of the prepared coating can be maintained to be stable, so that the color and the physical and chemical performance indexes of the coating cannot be changed in the operating process within the technical parameter index range of the operation of the operating method according to the operating method, the processing is stable, and the processing difficulty is reduced; and in the treatment process, DIN67530 is adopted to determine the gloss of the coating at 60 degrees, which shows that the control of the UV radiation dose range and the UV radiation dose in the curing process effectively maintains the gloss of the prepared coating at 95-105% at 60 degrees, greatly reduces the gloss change range and improves the gloss stability of the prepared coating.
In addition, the method realizes preheating by irradiating the powder coating preheated by UV radiation for 2s at normal temperature in the step (2), increases heat, enables the powder coating to be irradiated and cured under the UV radiation after melting and leveling, controls the UV radiation dose before and after melting, enables the glossiness (60 ℃) of the cured and formed coating to be stabilized between 95 and 105 percent, reduces amplitude, and reduces the preparation difficulty of a specific coating; meanwhile, the coating flexibility and the pendulum hardness were measured by the double pendulum method described in Yuying, hong Kong paint science and technology industries of Jiangsu, Changzhou, 2013016 "method and review for measuring hardness of coating film by pendulum method". It follows that the dose of UV radiation applied prior to melting is preferably 210-220mJ/cm2. More preferably 225mJ/cm2. After melting, the UV radiation is irradiated with a dose of preferably 40mJ/cm2. The flexibility reaches more than 8, and the hardness of the swing rod reaches more than 230; especially for preheating the substrate to 10-30 ℃ above normal temperature before spraying the powder coating. The time for increasing heat can be effectively reduced, and simultaneously, the hardness after the coating is formed is improved, so that the hardness can reach more than 250 under the same condition.
In the present invention, the process of increasing the temperature is heated by radiation of an infrared radiator, or may be heated by other heating methods.
Detailed Description
The technical solution of the present invention is further defined below with reference to the specific embodiments, but the scope of the claims is not limited to the description.
The test pieces of examples 1 to 9 were prepared in the following manner:
preparing a powder coating: 30kg of epoxy resin, 8kg of polyethylene resin, 8kg of pigment, 3kg of polydimethylsiloxane, 7kg of vinyl triamine and 0.2kg of photoinitiator.
Extruding the powder coating at the extrusion temperature of 80-95 ℃ by adopting a double-screw extruder, tabletting, cooling, crushing, and grinding to a particle size range suitable for spraying to obtain the coating.
The powder coatings prepared in the examples were sprayed onto metal substrate test pieces by means of an electrostatic spray gun to a coating film thickness of between 60 and 65 μm. Irradiating the powder coating by adopting near-infrared rays with the intensity distribution within the wavelength range of 800-900nm for 2s in a normal temperature environment, and then irradiating the powder coating by adopting UV radiation, so that the powder coating is melted and leveled by increasing the temperature to form a molten coating; in the process of increasing the temperature, an infrared radiator is adopted to radiate and heat to 130-140 ℃, powder coating melting is completed within 3min, the powder coating is solidified under the irradiation of UV radiation, different UV radiation irradiation doses are controlled, different test pieces are prepared, and the test pieces are subjected to the detection of physical and chemical indexes, wherein the results are shown in the following table 1:
TABLE 1
As can be seen from the data display results in Table 1, the control of the UV radiation dose before and after melting and the UV radiation dose after melting is helpful for improving the gloss stability range of the coating, optimizing the hardness of the coating and improving the physical and chemical index performance of the coating.
Further, the present investigators exchange the UV doses of the foregoing examples 6 and 1 before melting to prepare test pieces, and determine the 60 ° gloss and the pendulum hardness according to the foregoing methods, and as a result, the gloss is 36.4% and the hardness is about 100, which means that the UV doses before melting and after melting are not matched reasonably, and the prepared coating effect and the physicochemical index parameters are also affected to a great extent.
In addition, the present investigators, based on the test piece preparation and treatment methods of examples 4 and 7, further heat the surface of the substrate to 10-30 ℃ higher than the normal temperature, spray the powder coating on the surface, treat the surface according to the curing methods of examples 4 and 7, and detect the physical and chemical indexes, as shown in the following table 2:
TABLE 2
The data in table 2 show that, for the change of the base material temperature, the gloss stability and the hardness enhancement of the swing rod of the test piece irradiated by the UV dose before and after the different melting have different influences; however, it is found by comparison that the temperature change tends to increase within the range of 10 to 30 ℃ and the change of the physical and chemical index tends to be more stable, and therefore, the temperature increase treatment of the substrate surface is preferably 10 to 30 ℃.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (7)
1. A method of curing a powder coating comprising the steps of:
(1) spraying the powder coating on the surface of a base material by a spray gun machine;
(2) irradiating the powder coating by adopting near-infrared rays with the intensity distribution within the wavelength range of 800-900nm for 2s in a normal-temperature environment, then irradiating the powder coating by adopting UV radiation, increasing the temperature to melt and level the powder coating to form a molten coating, and curing under the irradiation of the UV radiation;
wherein, before melting, the irradiation dose of the UV radiation is 200-230mJ/cm2(ii) a After melting, the UV radiation irradiation dose is adjusted to 35-45mJ/cm2。
2. The method for curing powder coating according to claim 1, wherein the irradiation dose of UV radiation before melting is 210-220mJ/cm2。
3. The method of curing powder coatings according to claim 1, wherein said UV radiation is applied before melting at a dose of 225mJ/cm2。
4. The powder coating curing method of claim 1, wherein after melting, the UV radiation irradiation dose is adjusted to 40mJ/cm2。
5. A method for curing powder coatings according to claim 1, characterised in that the substrate is preheated to a temperature 10-30 ℃ above ambient temperature before the powder coating is sprayed.
6. A method for curing powder coatings as claimed in claim 1, characterised in that the temperature increase is by radiant heating using an infrared radiator.
7. A powder coating cured by the powder coating curing method as claimed in any one of claims 1 to 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811258480.6A CN109365237B (en) | 2018-10-26 | 2018-10-26 | Powder coating curing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811258480.6A CN109365237B (en) | 2018-10-26 | 2018-10-26 | Powder coating curing method |
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| CN109365237A CN109365237A (en) | 2019-02-22 |
| CN109365237B true CN109365237B (en) | 2021-07-30 |
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| CN201811258480.6A Active CN109365237B (en) | 2018-10-26 | 2018-10-26 | Powder coating curing method |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1950157A (en) * | 2004-05-12 | 2007-04-18 | 纳幕尔杜邦公司 | Pulsed heating process for curing substrates with near infrared radiation |
| CN1969020A (en) * | 2004-06-15 | 2007-05-23 | 纳幕尔杜邦公司 | Process for the preparation of powder coatings |
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2018
- 2018-10-26 CN CN201811258480.6A patent/CN109365237B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1950157A (en) * | 2004-05-12 | 2007-04-18 | 纳幕尔杜邦公司 | Pulsed heating process for curing substrates with near infrared radiation |
| CN1969020A (en) * | 2004-06-15 | 2007-05-23 | 纳幕尔杜邦公司 | Process for the preparation of powder coatings |
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| CN109365237A (en) | 2019-02-22 |
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