Production system and preparation method of polyester powder for coating high-stability zinc-aluminum alloy

Abstract

The invention discloses a preparation method of a high-stability zinc-aluminum alloy coating, which comprises the following steps: S1, putting raw materials for color mixing into a mixer, and stirring to ensure uniform mixing; s2, performing hot melting on the uniformly stirred mixed raw materials through a screw extruder to form a raw material cake; s3, grinding the raw material cake into powder through a precision flour mill; s4, the powder in the step S3 is put into a high-speed mixing binding machine through the binding machine to be bound with metal powder; s5, filtering all the bound powder through a vibrating screen to form polyester powder; and S6, the treated powder is sprayed on a color plate, and drying is conducted. And the situation that large-batch surface quality problems occur in the coating color and quality can be avoided, and the coating color of a finished product can achieve the effects of no color difference and high adhesive force.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material preparation, and in particular to a polyester powder production system and a preparation method for high-stability zinc-aluminum alloy coating. Background Art

[0002] At present, there are two ways to handle raw materials when color coating zinc-aluminum alloy. First, the raw materials are directly poured into the mixer in proportion for mixing, and then transported to the crusher for grinding into polyester powder, and then used for spraying; second, the raw materials are first ground into polyester powder by the crusher, and then poured into the mixing equipment for stirring before spraying. However, in the process of making powder and mixing the existing raw materials through the existing equipment, the polyester powder produced often has defects such as inconsistent surface leveling, color difference, and substandard adhesion, resulting in large-scale surface quality problems of the workpieces produced, and the color accuracy controllability is poor, and the total amount of colors that can be prepared is small. At the same time, when the same product needs to be coated in batches at different stages, the current process is prone to color difference between different batches. Therefore, it is necessary to adjust the combination of existing production equipment and preparation methods, so that when zinc-aluminum alloy is subjected to color coating, accurate finished product color uniformity control can be achieved by replacing or increasing or decreasing different raw materials. Summary of the invention

[0003] In order to solve certain technical problems existing in the prior art, one of the purposes of the present application is to provide a high-stability polyester powder production system for zinc-aluminum alloy coating, which can solve the problem of inconsistent surface leveling of the mixed polyester powder, so that the color control accuracy of the polyester powder mixture for spraying is higher, the sprayable colors are wider, the uniformity after spraying is better, and the adhesion is stronger.

[0004] The second purpose of this application is to provide a method for preparing a high-stability zinc-aluminum alloy coating, which can avoid the occurrence of large-scale surface quality problems in the coating color and quality, so that the finished coating color can achieve the effect of no color difference and strong adhesion.

[0005] In order to solve the above existing technical problems, one of the purposes of this application is achieved by adopting the following technical solution:

[0006] A polyester powder production system for high-stability zinc-aluminum alloy coating, comprising:

[0007] Mixer: The raw materials for color mixing are stirred through the mixer to ensure uniform mixing.

[0008] Screw extruder: melts the mixed raw materials evenly and forms a raw material cake;

[0009] Precision grinding machine: used to grind raw cake into powder;

[0010] Binding machine: The powder is put into a high-speed mixing binding machine to bind with metal powder;

[0011] Vibrating screen: All powders after binding are filtered through a vibrating screen to form polyester powder.

[0012] The second purpose of this application is achieved by the following technical solution:

[0013] A method for preparing a high-stability zinc-aluminum alloy coating, comprising:

[0014] S1. Put the raw materials for color mixing into the mixer and stir to ensure uniform mixing;

[0015] S2, the mixed raw materials are heated and melted by a screw extruder to form a raw material cake;

[0016] S3, grinding the raw material cake into powder by a precision grinding machine;

[0017] S4, putting the powder described in step S3 into a high-speed mixing binding machine to bind with the metal powder through a binding machine;

[0018] S5, filtering all the powder after binding through a vibrating screen to form polyester powder;

[0019] S6. Spray the treated powder onto the color plate and dry it.

[0020] Preferably, the raw materials for color adjustment in step S1 are prepared according to a raw material formula formulated according to the required color number or sample color number received, and each raw material is accurately weighed and prepared according to the formula ratio.

[0021] Preferably, the bonding machine in step S4 uses external hot water as a heat source, and introduces heat into the bonding machine through the inner wall of the bonding machine, thereby heating the powder, and the temperature of the hot water is 10-12° C. higher than the bonding temperature.

[0022] Preferably, the binding temperature of the binding machine is 10-12° C. higher than the glass transition temperature of the resin.

[0023] Preferably, the heat preservation time of the binding machine is 3-5 minutes.

[0024] Preferably, the stirring speed of the binding machine is 300-500 r / min.

[0025] Preferably, the temperature of the cooling medium used to cool the binding powder in the binding machine is 18-20° C., and the stirring speed of the binding machine during the cooling process is half of the binding speed.

[0026] Preferably, after the raw material cake in step S3 is ground into powder, the color is preliminarily checked to ensure that it meets the predetermined requirements, and then the powder is placed in a high-speed mixing device to be bound with the metal powder.

[0027] Preferably, the powder particles ground by the precision grinding mill have a fineness of D50 standard.

[0028] Preferably, the stirring speed of the mixer is 150-200 rpm, and the stirring time is 5-8 min.

[0029] Preferably, the polyester powder used for spraying has a particle fineness of D50 standard.

[0030] Preferably, the raw material powder is 1-10% of the metal powder to be bound.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The combination of a mixer, a screw extruder and a precision grinder replaces manual stirring to avoid the problem of uneven stirring, thereby improving production efficiency and the stability of the color of the finished coating. By first hot-melting the raw materials into cakes and then grinding the powder cakes to bind them, it is possible to avoid the phenomenon of dust flying before the raw materials are mixed, improve environmental hygiene and safety, ensure the accuracy of the raw materials, and effectively solve the problem that the color of the finished product is difficult to compare with the required color in advance during the color coating of the existing zinc-aluminum alloy, so that the color control is more precise, the coating colors that can be produced are wider, and the fineness of the zinc-aluminum alloy polyester powder for spraying is more uniform, which effectively solves the problem of inconsistent surface leveling of the existing polyester powder, so that the zinc-aluminum alloy polyester powder for spraying no longer has the problem of color difference, and the color control accuracy of the polyester powder mixture for spraying is higher, the sprayable colors are wider, the uniformity after spraying is better, the adhesion is stronger, and the defects such as substandard adhesion will not occur due to the coarseness of the particles, so that the surface of the produced workpieces will no longer have large-scale surface quality problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a process flow chart of the present invention;

[0034] Figure 2 It is a structural schematic diagram of the mixer in the present invention;

[0035] Figure 3 It is a structural schematic diagram of the screw extruder in the present invention;

[0036] Figure 4 It is a structural schematic diagram of the precision grinding mill in the present invention;

[0037] Figure 5 It is a structural schematic diagram of the binding machine in the present invention;

[0038] Figure 6 It is a schematic diagram of the structure of the vibrating screen in the present invention;

[0039] In the figure: 1. mixer; 2. screw extruder; 3. precision grinding machine; 4. binding machine; 5. vibrating screen. DETAILED DESCRIPTION

[0040] Below, the present application is further described in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0041] In the description of the present application, it should be understood that the terms "up", "down", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0042] The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0043] Embodiment 1:

[0044] like Figure 1 As shown, a polyester powder production system for high-stability zinc-aluminum alloy coating includes a mixer 1: the raw material for color adjustment is stirred through the mixer 1 to ensure uniform mixing, a screw extruder 2: the stirred mixed raw material is hot-melted to form a raw material cake; a precision grinder 3: used to grind the raw material cake into powder; a binding machine 4: the powder is put into the high-speed mixing binding machine 4 to be bound with the metal powder; a vibrating screen 5: all the powder after binding is filtered through the vibrating screen 5 to form polyester powder.

[0045] The raw materials for coloring, after being evenly mixed by the mixer 1, are directly melted by the screw extruder 2 to form raw material cakes, which can make the mixing of different raw materials more even and achieve the purpose of preliminary coloring. At the same time, by preparing the raw material cakes, it is more convenient to transport, avoids the phenomenon of dust flying, and improves environmental hygiene and safety. The raw material cakes are ground into powder by the precision grinder 3 and then bound by the binding machine 4.

[0046] Before spraying, after the raw material cake is formed by hot melting through the screw extruder 2, the color difference can be preliminarily compared, which solves the problem that the powdered mixed material cannot be compared with the color card. When a problem occurs, it can be adjusted in time, which effectively solves the problem that the finished product color is difficult to compare with the required color in the existing zinc-aluminum alloy during color coating, making the color control more accurate and the coating color that can be produced wider. Before the mixed powder after binding is used as the polyester powder for spraying, all the powder after binding is filtered through the vibrating screen 5, so that the fineness of the zinc-aluminum alloy polyester powder for spraying is more uniform, which effectively solves the problem of inconsistent surface leveling of the existing polyester powder, so that the zinc-aluminum alloy polyester powder for spraying no longer has the problem of color difference, and will not cause defects such as adhesion failure due to the coarseness of the particles, so that the surface of the produced workpiece no longer has large-scale surface quality problems, and the combination of the mixer 1, the screw extruder 2 and the precision mill 3 replaces manual stirring to avoid the problem of uneven stirring, thereby improving production efficiency and the stability of the color of the finished product coating.

[0047] Embodiment 2:

[0048] The second purpose of this application is achieved by the following technical solution:

[0049] like Figure 1 As shown, a method for preparing a high-stability zinc-aluminum alloy coating comprises:

[0050] S1, put the raw materials for color mixing into the mixer 1 and stir to ensure uniform mixing;

[0051] S2, the mixed raw materials are heated and melted by a screw extruder 2 to form a raw material cake;

[0052] S3, grinding the raw material cake into powder by precision grinding machine 3;

[0053] S4, putting the powder described in step S3 into the high-speed mixing binding machine 4 to bind with the metal powder through the binding machine 4;

[0054] S5, filtering all the powder after binding through a vibrating screen 5 to form polyester powder;

[0055] S6. Spray the treated powder onto the color plate and dry it.

[0056] Each raw material is accurately weighed and prepared according to the formula ratio. After each material is accurately weighed, the parameters are strictly controlled and poured into the mixing tank of the mixer 1 for sufficient stirring to ensure uniform mixing. The uniformly mixed raw materials are then directly connected to the feed port of the screw extruder 2 through a conveying pipeline, etc. The raw materials are hot-melted by the screw extruder 2 to form a raw material cake and cooled, thereby forming a raw material cake with uniform color, which is convenient for preliminary determination of the color check of the mixture. Among them, the size, weight and other parameters of the raw material cake can be controlled according to demand. During preparation, the raw materials are mixed and stirred and then hot-melted into a cake, so that the raw materials can achieve the purpose of uniform color fusion. Then, after the raw material cake is ground into powder by a precision grinder 3, the particle uniformity can be higher, the surface self-leveling degree in the later stage is better, and there will be no color unevenness. The particle size of different raw materials is evenly controlled, and there will be no problem of difficult control of the coarseness of the mixed powder due to different raw materials or different grinding batches. After the raw material cake is ground into powder, the color is checked again to ensure that it meets the predetermined requirements. Then, the powder is placed in a high-speed mixing device to bind with the metal powder. After the binding is completed, all the powder is filtered through a vibrating screen 5. Finally, the processed powder is sprayed on the color plate and dried. This can make the later spraying more uniform, avoid defects such as color difference and substandard adhesion, ensure the surface quality of the sprayed workpiece, avoid large-scale surface quality problems, and the color accuracy is highly controllable. The total amount of colors that can be prepared is large, and there is no need to worry about the problem of color adjustment and actual color difference causing similar colors to be difficult to accurately spray and form. When treating the surface of zinc-aluminum alloy substrates, various quality indicators can reach an excellent level, and the same effect can be achieved when spraying other products.

[0057] In the existing spraying process, when different batches are sprayed, it is easy to have color difference between the two sprayings. This is because different raw materials have different densities and are difficult to store after mixing. They can only be timely adjusted according to the existing situation. By preparing them in the form of raw material cakes, different batches of products can be more stable when the final color is formed. After the style is determined, they can be stored in batches, and the storage of raw material cakes is more convenient. There will be no color difference after storage due to different raw material quality. When different batches need to be sprayed, you only need to take different raw material cakes and bind them with metal powder in the same proportion to ensure that the color of the final product will not be different due to different batches.

[0058] A further improvement is that the raw materials for color matching in step S1 are prepared according to the raw material formula formulated by the required color number or sample color number received, and each raw material is accurately weighed and mixed according to the formula ratio.

[0059] A raw material formula is formulated according to the received color number or sample color number, and each raw material is accurately weighed and modulated according to the formula ratio. After the preparation is carried out according to the above method, the color number can be restored to a higher degree, the uncontrollable factors are reduced, and the preparation method is simpler and more convenient.

[0060] As a further improvement, the bonding machine 4 in step S4 uses external hot water as a heat source, and introduces heat into the bonding machine through the inner wall of the bonding machine, thereby heating the powder, and the temperature of the hot water is 10-12° C. higher than the bonding temperature.

[0061] It can effectively reduce the damage of the stirring paddle to the metal pigment and better maintain the characteristics of the metal pigment. The hot water temperature directly affects the heating rate of the material in the bonding machine. If the hot water temperature is too low, the heating rate is slow, the production efficiency is low, and the time and degree of damage to the metal pigment are increased; if the hot water temperature is too high, the material temperature is too high and it is easy to be adsorbed on the inner wall of the bonding machine. Generally, the hot water temperature is set to be about 10°C higher than the bonding temperature, which can speed up the material heating without causing the material to be adsorbed on the inner wall of the bonding machine.

[0062] As a further improvement, the binding temperature of the binding machine 4 is 10-12° C. higher than the glass transition temperature of the resin.

[0063] When setting the bonding temperature of the material, it mainly depends on the state of the powder coating. If the powder coating has a high bonding property at a certain temperature, it is easy to bond with the metal pigment, and at the same time, the powder coating will not bond with each other, then the current temperature can be used as the bonding temperature of the powder coating. However, in the production process, it is generally set to be 10°C higher than the glass transition temperature of the resin as the bonding temperature, and then the bonding temperature is adjusted through stability testing to make the powder coating at the optimal bonding temperature. According to the coating metal amount 3-4 shown in Table 1, increasing the bonding temperature can improve the bonding stability and reduce the color difference of the metal powder coating under different spraying conditions. Table 1 shows the metal effect of the coating at different bonding temperatures.

[0064] Table: 1

[0065]

[0066] Description of coating stability: Two different spraying conditions were selected, namely 50KV·0.1MPA and 50KV·0.3MPA, with other spraying parameters being the same, and then the metallic effects of the two coatings were compared.

[0067] A further improvement is that the stirring speed of the binding machine 4 is 300-500 r / min.

[0068] The high stirring speed makes the stirring blade have high shear force, which breaks the metal pigment, making the metal pigment particle size smaller and the glittering degree lower. In order to protect the metal pigment, the stirring speed of the binding machine 4 is about 350r / min, which can reduce the stirring time of the metal pigment and add the metal pigment when the material temperature is close to the bonding temperature; for metal pigments whose metal effect is less affected by the change of particle size or metal pigments that are resistant to shear, they can be added to the bonding machine together with the powder coating.

[0069] A further improvement is that the heat preservation time of the binding machine 4 is 3-5 minutes.

[0070] When setting the heat preservation time of the binding machine 4, if the powder coating has adhesive properties, the degree of adhesion between the powder coating and the metal raw material is greatly affected by the bonding time. Too short a bonding time makes many free metal raw materials not bonded to the powder coating. Within a certain time range, the delay of the bonding time can increase the degree and amount of adhesion between the powder coating and the metal raw material. If it exceeds a certain time, the delay of the bonding time has little effect on promoting the combination of the powder coating and the metal raw material. According to experiments and production experience, the heat preservation time is set at 3-5 minutes, which can make the powder coating and the metal pigment fully bonded together.

[0071] A further improvement is that the temperature of the cooling medium used to cool the binding powder in the binding machine 4 is 18-20° C.; the stirring speed of the binding machine 4 during the cooling process is half of the binding speed.

[0072] When the bonding of powder coating and metal raw materials reaches a dynamic balance, it is no longer possible to bond more powder coating and metal pigment together, which means that the bonding is saturated and the temperature needs to be lowered to make the two firmly bond together. The temperature of the cooling medium plays a decisive role in the cooling time. If the water temperature is low, the cooling time is short, which reduces the damage of the stirring paddle to the already bonded powder coating and metal raw materials during the cooling process, and can also improve production efficiency. However, the temperature cannot be too low. Since the inner wall of the bonding machine is made of metal, it is easy for the water vapor in the air to liquefy and adsorb on the inner wall of the bonding machine due to too low temperature, causing the powder coating to be damp. It is generally recommended to set the cooling medium to 18-20℃, among which the cooling medium is water, which has lower cost. During the cooling process, the stirring paddle is still in motion. If the speed is too low, it is easy to cause the powder coating that has not yet cooled to bond together. If the speed is too high, it will cause slow cooling and low production efficiency. It is generally set to half of the bonding speed.

[0073] A further improvement is that after the raw material cake in step S3 is ground into powder, the color is preliminarily checked to ensure that it meets the predetermined requirements, and then the powder is placed in a high-speed mixing device to be bound with the metal powder.

[0074] After the raw material cake in step S3 is ground into powder, the color is preliminarily checked to ensure that it meets the predetermined requirements. Then, the powder is placed in a high-speed mixing device to bind with the metal powder. This can make the color more controllable and avoid problems caused by color difference after a large amount of raw material cake is prepared. Adjustments can be made conveniently and in a timely manner, and the powder with problems can be put into the mixer 1 again for use.

[0075] A further improvement is that the powder particles ground by the precision grinder 3 have a particle fineness of D50 standard; and the polyester powder particles used for spraying have a particle fineness of D50 standard.

[0076] That is, the particle size corresponding to the cumulative particle size distribution percentage of powder particles reaches 50%. Its physical meaning is that particles with a particle size larger than it account for 50%, and particles with a particle size smaller than it also account for 50%. D50 is also called the median diameter or median particle size. D50 is often used to indicate the average particle size of powder.

[0077] As a further improvement, the stirring speed of the mixer 1 is 150-200 rpm, and the stirring time is 5-8 min, so that the raw materials can be mixed evenly.

[0078] Wherein, the raw material powder is 1-10% of the metal powder to be bound.

[0079] Generally, there is an effective range for the feeding amount of the bonding machine. Too much or too little will affect the bonding stability. If there is too much material, the powder in the upper part of the bonding machine cannot be stirred by the stirring paddle, making it impossible to mix and disperse the upper and lower powders, resulting in uneven overall color. If the material is too little, after the material is heated, the material is easy to adhere to the inner wall of the bonding machine, resulting in uneven dispersion of the metal pigment and powder coating, increasing instability. Therefore, the input amount of raw powder is 1-10% of the metal powder to be bound, which can reduce the difference between each cylinder of metal powder coating bonded, and can effectively reduce the color difference between batches.

[0080] The above-mentioned implementation modes are only preferred implementation modes of the present application and cannot be used to limit the scope of protection of the present application. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present application shall fall within the scope of protection required by the present application.

Claims

1. A polyester powder production system for high stability zinc-aluminum alloy coating, characterized by: include Mixer (1): The raw materials for color mixing are stirred through the mixer (1) to ensure uniform mixing. Screw extruder (2): heat-melts the mixed raw materials evenly stirred to form a raw material cake; Precision mill (3): used to grind raw material cake into powder; Binding machine (4): The powder is placed in a high-speed mixing binding machine (4) to be bound with the metal powder; Vibrating screen (5): All powders after binding are filtered through the vibrating screen (5) to form polyester powder.

2. A method for preparing a high-stability zinc-aluminum alloy coating, characterized in that: The device according to claim 1, wherein the preparation method comprises S1. Put the raw materials for color mixing into a mixer (1) and stir to ensure uniform mixing; S2, passing the uniformly stirred mixed raw materials through a screw extruder (2) to heat-melt and form a raw material cake; S3, grinding the raw material cake into powder by a precision grinding machine (3); S4, placing the powder described in step S3 into a high-speed mixing binding machine (4) to bind with the metal powder through a binding machine (4); S5, filtering all the powder after binding through a vibrating screen (5) to form polyester powder; S6. Spray the treated powder onto the color plate and dry it.

3. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 2, characterized in that: The raw materials for color matching in step S1 are prepared according to the raw material formula formulated according to the required color number or sample color number received, and each raw material is accurately weighed and mixed according to the formula ratio.

4. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 2, characterized in that: The bonding machine (4) in step S4 uses external hot water as a heat source and introduces heat into the bonding machine through the inner wall of the bonding machine, thereby heating the powder. The temperature of the hot water is 10-12° C. higher than the bonding temperature.

5. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 4, characterized in that: The binding temperature of the binding machine (4) is 10 to 12° C. higher than the glass transition temperature of the resin.

6. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 5, characterized in that: The heat preservation time of the binding machine (4) is 3-5 minutes.

7. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 7, characterized in that: The temperature of the cooling medium used to cool the binding powder in the binding machine (4) is 18-20° C., and the stirring speed of the binding machine (4) during the cooling process is half of the binding speed.

8. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 2, characterized in that: After the raw material cake in step S3 is ground into powder, the color is preliminarily checked to ensure that it meets the predetermined requirements, and then the powder is placed in a high-speed mixing device to be bound with the metal powder.

9. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 2, characterized in that: The powder particles ground by the precision grinding machine (3) have a particle fineness of D50 standard.

10. The method for preparing a high-stability zinc-aluminum alloy coating according to claim 2, characterized in that: The stirring speed of the mixer (1) is 150-200 rpm, and the stirring time is 5-8 min.

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