CN110961329A - Spraying method of aluminum profile and aluminum profile - Google Patents

Spraying method of aluminum profile and aluminum profile Download PDF

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Publication number
CN110961329A
CN110961329A CN201911148656.7A CN201911148656A CN110961329A CN 110961329 A CN110961329 A CN 110961329A CN 201911148656 A CN201911148656 A CN 201911148656A CN 110961329 A CN110961329 A CN 110961329A
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aluminum profile
coating
spraying
automatic
powder
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CN110961329B (en
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冯海平
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Guangdong Jma Aluminium Profile Factory Group Co ltd
Foshan JMA Aluminium Co Ltd
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Guangdong Jma Aluminium Profile Factory Group Co ltd
Foshan JMA Aluminium Co Ltd
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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
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
    • B05B13/02—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work
    • B05B13/0278—Arrangement or mounting of spray heads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
    • B05B13/02—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work
    • B05B13/04—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work the spray heads being moved during spraying operation
    • B05B13/0405—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work the spray heads being moved during spraying operation with reciprocating or oscillating spray heads
    • B05B13/041—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work the spray heads being moved during spraying operation with reciprocating or oscillating spray heads with spray heads reciprocating along a straight line
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/0255—Discharge apparatus, e.g. electrostatic spray guns spraying and depositing by electrostatic forces only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B05B5/081—Plant for applying liquids or other fluent materials to objects specially adapted for treating particulate materials
    • 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
    • B05D3/10—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 other chemical means
    • B05D3/102—Pretreatment of metallic substrates
    • 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
    • B05D3/12—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 mechanical means
    • 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
    • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
    • B05D5/06—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects
    • B05D5/065—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects having colour interferences or colour shifts or opalescent looking, flip-flop, two tones
    • B05D5/066—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects having colour interferences or colour shifts or opalescent looking, flip-flop, two tones achieved by multilayers
    • 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
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/50—Multilayers
    • B05D7/56—Three layers or more
    • B05D7/58—No clear coat specified
    • B05D7/584—No clear coat specified at least some layers being let to dry, at least partially, before applying the next layer
    • 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
    • B05D2202/00—Metallic substrate
    • B05D2202/20—Metallic substrate based on light metals
    • B05D2202/25—Metallic substrate based on light metals based on Al
    • 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
    • B05D2401/00—Form of the coating product, e.g. solution, water dispersion, powders or the like
    • B05D2401/30—Form of the coating product, e.g. solution, water dispersion, powders or the like the coating being applied in other forms than involving eliminable solvent, diluent or dispersant
    • B05D2401/32—Form of the coating product, e.g. solution, water dispersion, powders or the like the coating being applied in other forms than involving eliminable solvent, diluent or dispersant applied as powders
    • 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
    • B05D2451/00—Type of carrier, type of coating (Multilayers)
    • 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
    • B05D2508/00—Polyesters
    • 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
    • B05D2601/00—Inorganic fillers
    • B05D2601/02—Inorganic fillers used for pigmentation effect, e.g. metallic effect
    • 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
    • B05D2601/00—Inorganic fillers
    • B05D2601/02—Inorganic fillers used for pigmentation effect, e.g. metallic effect
    • B05D2601/10—Other metals

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

The invention discloses an aluminum profile spraying method, which comprises the following steps: carrying out sand blasting, degreasing and passivation treatment on the aluminum profile in sequence; then, spraying the central part of the aluminum profile by using a manual spray gun, and forming a first coating with the thickness of 40-50 mu m at the central part of the aluminum profile; spraying the whole surface of the surface to be sprayed of the aluminum profile once by using an automatic coating system to form a second coating; finally curing the second coating; wherein the thickness of the second coating is 50-110 μm; the thickness of the third coating is gradually changed from the center of the aluminum profile to the periphery of the aluminum profile in a stepped manner. The thickness of the third coating formed by the spraying process is gradually increased from the center to the periphery of the aluminum profile, so that the aluminum profile has a gradually changed appearance effect on the whole, and the decorative performance of the aluminum profile is greatly improved. Meanwhile, the using amount of the powder coating is reduced, and the cost is reduced.

Description

Spraying method of aluminum profile and aluminum profile
Technical Field
The invention relates to the technical field of coatings, in particular to a spraying method of an aluminum profile and the aluminum profile.
Background
The prior thermosetting powder coating mostly adopts electrostatic powder coating, the coating thickness can reach more than 50 mu m after the coating is sprayed once, the operation is simple and convenient, and the full automation can be realized. The electrostatic powder coating method can be classified into a high-voltage electrostatic powder coating method and a tribo-electrostatic powder coating method, wherein the tribo-electrostatic powder coating method is not mature yet, has strict requirements on the type of the powder coating, and the spray gun needs to be replaced frequently, which results in high cost. The high-voltage electrostatic powder spraying method has low cost and is the most widely applied spraying technology at present.
The principle of high-voltage electrostatic powder spraying is as follows: the high voltage electricity makes the end of the spray gun discharge to ionize the surrounding air, and simultaneously, an electric field is generated between the end and the coated object, the coated object is positively charged through grounding induction, and the powder coating is negatively charged. The powder coating with negative charge flies to the surface of the coated object under the action of the air delivery and the electric field force, and attracts the positive charge of the coated object, thereby realizing coating. However, for aluminum profiles, the positive charge is concentrated at the profile edge locations, more readily attracting negatively charged powder particles. If the coating thickness of the whole decorative surface is not too high in the conventional spraying mode, or the coating thickness of the middle coating is too low, the coating thicknesses of the edge part and the central part are difficult to be compatible.
For the spraying of the aluminum profile, the adopted coatings are all transparent coatings, so the thickness of the coating film becomes an important factor influencing the color development effect of the aluminum profile. The applicant has obtained by means of a coating test: coating with common powder coating, wherein when the coating is larger than 100 mu m, the coating has certain covering power, aluminum profiles cannot be seen, and the whole color is darker; when the thickness of the coating is less than 65 mu m, white aluminum profiles can be seen under visual conditions, the texture is poor, and the overall decorative effect is poor. And each building has the characteristics, and the number of the profiled bars is large, so that the control of the ideal coating thickness is not facilitated.
On the other hand, the size of the aluminum profile is also an important factor influencing the color development effect, and particularly, some aluminum profiles applied to curtain walls and external windows have large length (generally more than 5m), and the color development effect at different positions is difficult to regulate and control (particularly to the external curtain walls). In addition, the aluminum profile decoration effect is also influenced by the aluminum profile surface, pretreatment and spraying operation.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a spraying method for an aluminum profile, wherein the aluminum profile obtained by spraying has a gradient decorative effect and is low in spraying cost.
The invention also aims to provide an aluminum profile which has a gradient decorative effect.
In order to solve the technical problem, the invention provides an aluminum profile spraying method, which comprises the following steps:
(1) carrying out sand blasting treatment on the aluminum profile;
(2) degreasing the aluminum profile subjected to sand blasting;
(3) passivating the degreased aluminum profile;
(4) spraying the central part of the aluminum profile by using a manual spray gun, and forming a first coating with the thickness of 40-50 mu m at the central part of the aluminum profile;
(5) spraying the whole surface of the to-be-sprayed surface of the aluminum profile once by using an automatic coating system to form a second coating;
(6) curing the second coating;
wherein the thickness of the second coating is 50-110 μm; the thickness of the third coating is gradually changed from the center of the aluminum profile to the periphery of the aluminum profile in a stepped manner.
As an improvement of the above technical scheme, in the step (5), the automatic spraying system is a high-voltage electrostatic powder automatic coating system; the electrostatic powder coating system comprises a conveyor belt, an automatic coating machine, a powder supply device and a recovery device; the automatic coating machine is provided with at least two automatic spray guns; the automatic coating machine can move along the axis of the conveying direction of the conveying belt.
As an improvement of the technical scheme, the automatic spray gun is a corona discharge type electrostatic powder spray gun.
As an improvement of the technical scheme, in the step (5), the spraying voltage is 70-80kV, the powder spraying pressure is 0.05-0.2MPa, and the spraying distance is 20-35 cm.
As an improvement of the above technical solution, in the step (4), the hand spray gun is a corona discharge type electrostatic powder spray gun; the spraying voltage is 60-75kV, the spraying pressure is 0.1-0.2MPa, and the spraying distance is 10-20 cm.
As an improvement of the above technical solution, in the step (3), the passivation treatment is a chromium-free passivation treatment.
As an improvement of the technical scheme, in the steps (4) and (5), powder coating is adopted for spraying; the powder coating is a transparent coating:
as an improvement of the technical scheme, in the steps (4) and (5), powder coating is adopted for spraying; the powder coating is mainly prepared from the following raw materials in percentage by weight:
65-75% of polyester resin, 4-10% of curing agent, 0.5-2% of flatting agent, 0.5-3% of defoaming agent, 5-15% of pigment and 5-10% of filler.
As an improvement of the technical scheme, the powder coating is mainly prepared from the following raw materials in percentage by weight:
65-75% of polyester resin, 4-10% of curing agent, 1-2% of flatting agent, 0.5-3% of defoaming agent, 4-10% of carbon black, 2-10% of iron oxide red and 5-10% of barium sulfate.
Correspondingly, the invention also provides an aluminum profile which is coated by adopting the spraying method.
The implementation of the invention has the following beneficial effects:
1. the method comprises the steps of firstly spraying the central part of the aluminum profile to form a first coating with the thickness of 40-50 mu m, and then completely spraying the surface to be sprayed of the aluminum profile once by adopting an automatic coating system to form a second coating; the spraying process enables the thickness of the second coating to be gradually increased from the center of the aluminum profile to the periphery, so that the aluminum profile has a gradually changed appearance effect on the whole, and the decorative performance of the aluminum profile is greatly improved. Meanwhile, the using amount of the powder coating is reduced, and the cost is reduced.
2. The aluminum profile is subjected to sand blasting before spraying, so that the defects of scratching, polishing marks, extruding lines and the like on the surface of the aluminum base material are eliminated, the flatness of the surface to be sprayed is improved, and the defects of black marks and the like are avoided after spraying.
3. According to the invention, the aluminum profile is subjected to chromium-free passivation treatment before spraying, so that a passivation film on the surface of the aluminum profile is in a colorless state, and the sprayed aluminum profile is ensured to have a gradient effect.
Drawings
FIG. 1 is a flow chart of a method for spraying an aluminum profile according to the present invention;
FIG. 2 is a schematic view of the automated spray system of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below.
Referring to fig. 1, the invention provides an aluminum profile spraying method, which comprises the following steps:
s1: carrying out sand blasting treatment on the aluminum profile;
the surface of the aluminum profile generally has some scratches, such as scratches and scratches generated in the transportation and moving processes; such as grinding marks, extrusion line marks and the like generated in the processing process. These scratches, if not properly treated, can form black marks of varying depth after later spraying, which can affect the decorative effect.
Therefore, the invention adopts sand blasting treatment, eliminates the defects of scratching, polishing printing or extruding lines and the like of the surface to be sprayed of the aluminum profile base material, ensures that the surface to be sprayed is smooth and uniform and has no flaws, thereby achieving the aim of not influencing the decorative effect.
S2: degreasing the aluminum profile subjected to sand blasting;
specifically, S2 includes:
s21: degreasing the aluminum profile subjected to sand blasting;
specifically, degreasing fluid is adopted to clean the aluminum profile subjected to sand blasting. Specifically, degreasing may be performed by acid washing or alkali washing.
S22: and (5) washing the degreased aluminum profile.
S3: passivating the degreased aluminum profile;
specifically, S3 includes:
s31: passivating the degreased aluminum profile;
specifically, the aluminum profile is cleaned by adopting a passivation solution, so that the purpose of passivation is achieved.
Preferably, the aluminum profile is cleaned by adopting a passivation solution without Cr so as to achieve the purpose of passivation.
It should be noted that, when the traditional yellow 6-valent chromium passivator or green 3-valent chromium passivator is used for the aluminum material spraying pretreatment, the passivation film on the surface of the aluminum profile is yellow or light green, and the gradual color effect of the semitransparent coating is not obvious due to the passivation film. The aluminum profile spraying pretreatment adopts chromium-free passivation, and a passivation film on the surface of the aluminum profile is colorless, so that the surface color of the aluminum profile is not changed, and the gradient color effect after spraying is not affected.
S32: washing the passivated aluminum profile with water;
s33: and drying the aluminum profile after washing.
S4: spraying the central part of the aluminum profile by using a manual spray gun, and forming a first coating with the thickness of 40-50 mu m at the central part of the aluminum profile;
specifically, the manual spray gun is a corona discharge type electrostatic powder spray gun. The hand spray gun is a corona discharge type electrostatic powder spray gun; the spraying voltage is 60-75kV, the powder spraying pressure is 0.1-0.2MPa, the spraying distance is 5-15cm, and when the spraying distance is more than 15cm, the spraying range is too wide, and a gradual change effect cannot be formed; when the spraying distance is less than 5cm, the first coating at the central part is too thick, and the gradual change effect cannot be formed. Preferably, the spraying distance is 5-10 cm.
S5: spraying the whole surface of the to-be-sprayed surface of the aluminum profile once by using an automatic coating system to form a second coating;
specifically, the automatic spraying system is a high-voltage electrostatic powder automatic coating system; referring to fig. 2, the electrostatic powder coating system includes a conveyor 1, an automatic coating machine 2, a powder supply device 3, and a recovery device 4; the automatic coating machine is provided with at least two automatic spray guns 21; the automatic coating machine 2 can only move along the axis of the conveyor belt in the conveying direction.
Specifically, the automatic spray gun is a corona discharge type electrostatic powder spray gun. The parameters of the automatic spraying process are as follows: the spraying voltage is 70-80kV, the spraying pressure is 0.05-0.2MPa, and the spraying distance is 15-20 cm; when the spraying distance is more than 20cm, the thickness of the coating at the edge of the aluminum profile is too high, and a gradually-changed decorative effect cannot be formed; when the spraying distance is less than 15cm, the thickness of the center of the aluminum profile becomes larger, and the gradually-changed decorative effect cannot be achieved.
The first coating formed by manual spraying and the coating formed by automatic spraying are combined to form a second coating; the overall thickness of the second coating is controlled to be 50-110 mu m; the thickness of the aluminum profile is changed from the center of the aluminum profile to the periphery in a uniform and incremental manner or in a gradient and incremental manner; thereby make the aluminium alloy wholly have the effect of gradual change of colour, promoted the decorative effect of aluminium alloy by a wide margin.
It should be noted that, the traditional high-voltage electrostatic powder automatic coating system mainly realizes spraying by the action of an electric field and an air flow. The positive charges of the aluminum profile are mainly concentrated in the edge area, so that the powder coating particles with negative charges are more easily attracted, the thickness of the edge coating is larger than that of the center coating, and the thickness difference is larger, so that when only an automatic spray gun is used for spraying, the thickness of the edge coating or the thickness of the middle coating of the whole decorative surface is not too high, the thickness of the edge coating or the middle coating is too low, the coatings of the edge part and the middle part are difficult to be considered, the coatings can not be saved, and the gradient color decorative effect can be generated. The current common means is that the whole decorative surface adopts a thicker coating, so that the whole aluminum profile is dark; or an overall thinner coating is adopted, so that the original color of the profile is realized; both solutions have poor decorative effect. Moreover, the coating is limited by a spraying process, so that when the traditional high-voltage electrostatic powder automatic coating system is adopted for spraying, a coating with the thickness of 40-150 mu m can be formed by single spraying; therefore, when a thick coating is used, multiple spraying operations are required, resulting in a large amount of waste of powder coating.
Aiming at the problems, the invention firstly adopts a handheld spray gun to spray the central part of the aluminum profile to form a first coating, and then adopts an automatic coating system to carry out automatic spraying once to form a second coating; through first coating and the superposition of second coating formed thickness by aluminium alloy central authorities to the even third coating that increases gradually all around to make the aluminium alloy have the outward appearance effect of gradual change, and need not carry out secondary automatic spraying, saved powder coating, the cost is reduced. Meanwhile, by controlling the spraying parameters, the problem that the thickness difference between the thickness edge and the center of the traditional automatic spraying system is larger is effectively solved, and a coating with controllable thickness is formed.
It should be noted that the size and shape of the aluminum profiles are different, and the sprayed decoration is different. For some aluminum profiles (such as curtain walls and the like) applied to special occasions, the to-be-sprayed surfaces of the profiles are wider, the overall length is longer (the width of the sprayed surface is 10-100mm, and the length of the profile is generally more than 5m), and the requirements on the decorative effect are high. The inventor of the present invention found through research that the color development effect of the profile is very difficult to control, and even if the thickness of the coating film on the surface of the profile is completely the same through a certain means, the color development effect is relatively deviated under the sunlight irradiation effect, and the color development difference of different parts is very large. The technical scheme provided by the invention can effectively control the color development effect of the large-scale section bar and obtain the decorative effect with great aesthetic feeling. The results of the invention have been well verified in the Beijing Asia Provisioning headquarters.
To achieve this gradient decorative effect, the powder coating needs to be selected. Specifically, in the present invention, the powder coating adopted in steps S4 and S5 is mainly prepared from the following raw materials by weight: 65-75% of polyester resin, 4-10% of curing agent, 0.5-2% of flatting agent, 0.5-3% of defoaming agent, 5-15% of pigment and 5-10% of filler. The powder coating is transparent after spraying and is easy to adopt high pressure
Specifically, the polyester resin adopted by the invention is medium-hydroxyl polyester resin, and the acid value of the polyester resin is 100-300 mgKOH/g; preferably, the acid value is 150-250 mgKOH/g.
Specifically, the curing agent is TGIC or polyisocyanate, but not limited thereto. Preferably, TGIC is selected.
Specifically, the pigment is one or more of titanium white, vanadium yellow, carbon black or iron red; preferably, carbon black and iron oxide red are selected, and the decorative effect is better.
Specifically, the filler is one or more of calcium carbonate, barium sulfate and silicon dioxide; preferably, barium sulfate is used.
Preferably, the powder coating is prepared from the following raw materials in percentage by weight: 65-75% of polyester resin, 4-10% of curing agent, 1-2% of flatting agent, 0.5-3% of defoaming agent, 4-10% of carbon black, 2-10% of iron oxide red and 5-10% of barium sulfate.
S6: curing the third coating;
specifically, the aluminum profile is heated in a curing furnace to cure the third coating; wherein the curing temperature is 200-210 ℃, and the curing time is 8-12 minutes.
Correspondingly, the invention also discloses an aluminum profile which is coated by adopting the spraying method.
The invention is further illustrated by the following specific examples:
example 1
The embodiment provides an aluminum profile, and a spraying method thereof is as follows:
(1) carrying out sand blasting treatment on the aluminum profile;
wherein the width of the surface to be sprayed of the aluminum profile is 38mm, and the length is 6 m;
(2) degreasing the aluminum profile subjected to sand blasting;
(3) carrying out chromium-free passivation treatment on the degreased aluminum profile;
(4) spraying the central part of the aluminum profile by using a manual spray gun, and forming a first coating with the thickness of 45 mu m at the central part of the aluminum profile; wherein, a corona discharge type electrostatic powder spray gun is adopted for spraying, the spraying voltage is 70kV, the powder spraying pressure is 0.1MPa, and the spraying distance is 12 cm.
(5) Spraying the whole surface of the to-be-sprayed surface of the aluminum profile once by using an automatic coating system to form a second coating; wherein the automatic coating system is a high-voltage electrostatic powder automatic coating system; the automatic powder coating machine comprises a conveyor belt, an automatic coating machine, a powder supply device and a recovery device; the automatic coating machine is provided with four automatic spray guns which are arranged in a row. The spraying voltage is 75kV, the spraying pressure is 0.08MPa, and the spraying distance is 28 cm.
(6) Curing the second coating; wherein the curing temperature is 200 ℃ and the curing time is 10 min.
Wherein the thickness of the second coating is 50-100 μm; the thickness of the third coating is gradually changed from the center of the aluminum profile to the periphery of the aluminum profile in a stepped manner.
Wherein, the formula of the powder coating is as follows: 70% of polyester resin, 6% of TGIC curing agent, 1.5% of flatting agent, 0.5% of defoaming agent, 8% of carbon black, 6% of iron oxide red and 8% of barium sulfate.
Example 2
The embodiment provides an aluminum profile, and a spraying method thereof is as follows:
(1) carrying out sand blasting treatment on the aluminum profile;
the width of the surface to be sprayed of the aluminum profile is 12mm, and the length of the surface to be sprayed of the aluminum profile is 50 cm;
(2) degreasing the aluminum profile subjected to sand blasting;
(3) carrying out chromium-free passivation treatment on the degreased aluminum profile;
(4) spraying the central part of the aluminum profile by using a manual spray gun, and forming a first coating with the thickness of 40 mu m at the central part of the aluminum profile; wherein, a corona discharge type electrostatic powder spray gun is adopted for spraying, the spraying voltage is 65kV, the powder spraying pressure is 0.15MPa, and the spraying distance is 12 cm.
(5) Spraying the whole surface of the to-be-sprayed surface of the aluminum profile once by using an automatic coating system to form a second coating; the first coating and the second coating are superposed to form a third coating; wherein the automatic coating system is a high-voltage electrostatic powder automatic coating system; the automatic powder coating machine comprises a conveyor belt, an automatic coating machine, a powder supply device and a recovery device; the automatic coating machine is provided with four automatic spray guns which are arranged in a row. The spraying voltage is 75kV, the powder spraying pressure is 0.1MPa, and the spraying distance is 32 cm.
(6) Curing the third coating; wherein the curing temperature is 210 ℃ and the curing time is 9 min.
Wherein the thickness of the third coating is 50-110 μm; the thickness of the third coating is gradually changed from the center of the aluminum profile to the periphery of the aluminum profile in a stepped manner.
Wherein, the formula of the powder coating is as follows: 72% of polyester resin, 7% of TGIC curing agent, 2% of flatting agent, 1% of defoaming agent, 7% of carbon black, 5% of iron oxide red and 6% of barium sulfate.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. An aluminum profile spraying method is characterized by comprising the following steps:
(1) carrying out sand blasting treatment on the aluminum profile;
(2) degreasing the aluminum profile subjected to sand blasting;
(3) passivating the degreased aluminum profile;
(4) spraying the central part of the aluminum profile by using a manual spray gun, and forming a first coating with the thickness of 40-50 mu m at the central part of the aluminum profile;
(5) spraying the whole surface of the to-be-sprayed surface of the aluminum profile once by using an automatic coating system to form a second coating;
(6) curing the second coating;
wherein the thickness of the second coating is 50-110 μm; the thickness of the second coating is gradually changed from the center of the aluminum profile to the periphery of the aluminum profile in a stepped mode.
2. The aluminum profile spraying method according to claim 1, wherein in the step (5), the automatic spraying system is a high-voltage electrostatic powder automatic coating system; the electrostatic powder coating system comprises a conveyor belt, an automatic coating machine, a powder supply device and a recovery device; the automatic coating machine is provided with at least two automatic spray guns; the automatic coating machine can move along the axis of the conveying direction of the conveying belt.
3. The aluminum profile spraying method as recited in claim 2, wherein the automatic spray gun is a corona discharge type electrostatic powder spray gun.
4. The aluminum profile spraying method according to claim 1 or 3, wherein in the step (5), the spraying voltage is 70-80kV, the powder spraying pressure is 0.05-0.2MPa, and the spraying distance is 20-35 cm.
5. The aluminum profile spraying method according to claim 1, wherein in the step (4), the hand spray gun is a corona discharge type electrostatic powder spray gun; the spraying voltage is 60-75kV, the spraying pressure is 0.1-0.2MPa, and the spraying distance is 10-20 cm.
6. The aluminum profile spraying method as claimed in claim 1, wherein in the step (3), the passivation treatment is a chromium-free passivation treatment.
7. The aluminum profile spraying method according to claim 1, wherein in the steps (4) and (5), powder coating is adopted for spraying; the powder coating is a transparent coating.
8. The aluminum profile spraying method according to claim 1, wherein in the steps (4) and (5), powder coating is adopted for spraying; the powder coating is mainly prepared from the following raw materials in percentage by weight:
65-75% of polyester resin, 4-10% of curing agent, 0.5-2% of flatting agent, 0.5-3% of defoaming agent, 5-15% of pigment and 5-10% of filler.
9. The aluminum profile spraying method as claimed in claim 7, wherein the powder coating is mainly prepared from the following raw materials in percentage by weight:
65-75% of polyester resin, 4-10% of curing agent, 1-2% of flatting agent, 0.5-3% of defoaming agent, 4-10% of carbon black, 2-10% of iron oxide red and 5-10% of barium sulfate.
10. An aluminum profile coated by the spray coating method according to any one of claims 1 to 9.
CN201911148656.7A 2019-11-21 2019-11-21 Spraying method of aluminum profile and aluminum profile Active CN110961329B (en)

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