Common problems of coating machine

1. How to change the coating machine scraper?
Scraper for waste cleaning: the scraper blade is made of steel, and the position of the blade and the coating roller should be adjusted to prevent damage to the coating.
The scraper is made of organic material, which should be in contact with the coating roller as much as possible, with obvious effect.
Comma roll: servo motor knife adjustment, roller bearing is at the lowest position, spacer is padded between the comma roll and the coating roll to carefully touch, and all fixed parts are loosened. Manually adjust the cutter to prevent the removal after the rolling surface contacts.
2. What kind of glue is good for coating machine? What is the quality of glue?
The glue can't be used to see. The most important thing is to see whether there are particles, sedimentation (which is normal in fact), oil stains, etc. The strength and firmness can be measured only after "trial production in advance". However, the proportion of mixed water (fluidity), coating film thickness (too thin or too thick), drying time, air humidity, ambient temperature and characteristics of the adhesive material will affect the results.
3. What is the reason for the instability of the back clearance of the lithium battery coating machine?
1 Check whether the sensor of the coating machine will be close to the copper foil or aluminum foil due to the color after drying - adjust the sensor sensing parameters
2 Check whether the parameters of the coater are correct within the operating range of the coater
4. What is the role of the guide roller in the coater?
It has the function of stability and transmission
5. What are the key control parameters of large coater?
Unit speed
Coating unit tension
Length of drying equipment
Drying equipment characteristics
Coating thickness
Parameters related to coating curing process
wait...
6. What does NCR coater do?
No Carbon Required paper: one side of the paper is coated with microcapsule (CB), which contains pigment, and the other side is coated with color developing agent (CF surface). When used, the CB surface must correspond to the CF surface. When the paper is pressed, the microcapsule on the CB surface breaks, and the pigment escapes and reacts with the color developing agent on the CF surface to produce color. This principle is used to achieve the replication effect.
NCR coating machine is used for coating non-carbon carbon carbon paper.
7. Is the belt conveyor and coating machine a kind of equipment?
The coater and belt conveyor are actually a kind of equipment, but the coater is a large belt conveyor
8. What industry does the coater belong to?
It belongs to prepress equipment in packaging and printing industry.
Design principle and operation basis of polar coating machine
1、 Coating process foundation
1. Working principle of roller coating
Figure 3.1B shows the coating working principle of our coater. The working principle of our coater consists of two processes:
(1) Thickness setting process of clockwise roll
(2) Reverse roll coating transfer process
Fig. 3.1B Three-roll coating
(1) Clockwise roller coating and its coating window:
First introduce the terminology in coating technology - coating window
Any coating form (method) has a scope of application. It can be applied without defects within a certain operating condition (range), that is, evenly coating a thin layer of fluid onto the support body. The scope of this coating operation is called the coating window in the coating technology.
In our coating machine, it is controlled by adjusting the metering gap between the two coating rollers with the same rotation direction and the metering roller in the clockwise roller coating process, and the required thickness of coating is formed on the coating roller. Our coating method is a special form of clockwise roller, that is, one of the measuring rollers does not rotate, that is, the speed is zero, and the section of the measuring roller is made into a comma shape, also known as a comma scraper. Our coating thickness can be adjusted by changing the distance between the comma scraper and the coating roller.
In our special clockwise roller coating form, when the operation is improper, the knife edge position deviates from the working position, and the coating parameters and slurry parameters are not within a certain range, the vertical strip defect may occur, which is called vertical strip, and its apparent phenomenon is like lamp core flannelette.
In the figure: gap/roll diameter ratio H/R, capillary standard number Ca= μ U/ σ
Where: H is the gap between the two rollers, R is the equivalent radius of the two rollers, μ— Fluid viscosity, U - surface linear velocity of roller, σ— The surface tension of the fluid.
In the figure, the uniform coating area at the lower part of the curve is H - the gap between the two rollers, R - the equivalent radius of the two rollers, μ— Fluid viscosity, U - surface linear velocity of roller, σ— The surface tension of the fluid.
When their relationship satisfies the conditions in the figure, that is, the capillary quasi-number Ca= μ U/ σ When the gap/roll diameter ratio H/R is large in a small range, uniform coating can be carried out, and the coating conditions enter the coating window.
In polar coating, the slurry viscosity is relatively large, so the coating speed is limited, and can only be applied at a lower speed. In addition, if the roller diameter has been determined, a larger gap is conducive to uniform coating.
(2) Reversing roller coating and its coating window
In our polar coating machine, the slurry coating on the coating roll is transferred to the copper foil or aluminum foil wrapped on the back roll in the opposite direction of rotation in the gap area of the bright roll. Therefore, the coating process must also meet the law of reverse stick coating.
Coating window of reverse roller coating
The reverse roller coating window is shown in Figure 3.14.
In the figure, velocity ratio=Vm/Va, capillary standard number Ca= μ U/ σ，
Where, Vm - surface speed of back roll, Va - surface speed of coating roll, μ— Fluid viscosity, U - surface linear velocity of roller, σ— Surface tension of fluid
The stable area in Figure 3.14 is the reverse roller coating window. It can be seen that the reverse roller coating window is relatively small.
The defects in the vertical strip area in the figure are similar to those in the vertical strip coating in Figure 3.7.
See Fig. 3.13 for the phenomenon of gushing in the figure. This phenomenon will occur when the coating speed is relatively high and the gap is relatively large during the coating process of the pole piece. That is, the slurry cannot be transferred to the substrate and flows to the lower tray. This is one of the reasons why the coating speed of high viscosity slurry is limited
Figure 3.13
In the process of reverse roller coating, if the gap between the two rollers is relatively small, the capillary number is low enough, that is, in the case of relatively small viscosity or speed, the flow is relatively stable within a relatively wide speed ratio range. Good coating apparent quality can be obtained. If the gap is relatively large, air entrainment will easily occur when the coating speed is high, and there are many tiny bubbles on the coating surface.
Sometimes, in order to increase the output and increase the coating speed, air entrainment may occur. In order to eliminate this problem, the operation method of reducing the gap is adopted. Too small gap makes the coating roll and back roll squeeze each other, which additionally increases the load of motor and reducer, causing abnormal wear. This is also the second reason why the transfer coating speed of the slurry in the reverse roller is limited.
II
1. Drying process basis
Relationship between coating and drying
The drying process and the coating process are independent and interrelated.
The nature of the coating affects the design and operation of the drying process
Coating speed, coating thickness - determine drying length
The coating has leveling process during drying
Therefore, whether a coating machine can accurately use the best coating and drying process in the design process and balance the relationship between them will ultimately affect the comprehensive technical performance of the coating machine.
2. Drying method of pole piece
There are many ways to dry polar plates, and the current applications are as follows:
(1) Characteristics and application of far infrared radiation drying
Far-infrared drying is to use far-infrared emission elements to radiate heat energy to the surface of the dry object, so as to evaporate and vaporize the liquid for drying. characteristic:
Its drying speed mainly depends on the radiation temperature, high temperature and fast drying speed.
Its advantage is that the equipment is relatively simple, so it is applied in the relatively low-grade coating machine.
Its disadvantages are low drying efficiency, uneven drying and easy to produce drying defects.
(2) Drying characteristics and application of heat transfer drum
Hot drum drying means that the back of the drying object is close to the surface of the heated drum, and the heat energy is transferred to the drying object through conduction to make the liquid evaporate and vaporize for drying. The characteristics are:
The drying rate depends on the temperature of the hot drum
The equipment is bulky,
It is usually used for drying paper and cloth, so it is rarely used in the extreme coating machine.
(3) Characteristics and application of double-side air supply floating drying
Floating drying is to set a specially designed air nozzle on both sides of the drying sheet to send a high-speed jet of air, which acts vertically on the drying sheet under the effect of air flow and wall attachment. Under the effect of air flow, the drying sheet is floating for drying. Conditions and characteristics of forming floating drying:
Set air nozzles on both sides of the drying sheet
Nozzle design can produce wall-attached effect
Enough high injection wind speed
The flaky dry material is floating during drying
Capable of double-sided drying with high drying efficiency
Its disadvantages are:
High power consumption of double-sided air supply
The structure of drying equipment is complex and huge
Floating drying is widely used in the drying of paper coaters. Paper is a permeable material. The moisture (solvent) in the wet coating can penetrate into the back, so it can be dried on both sides, with the advantage of high drying efficiency. However, the base material of the lithium-ion battery electrode is copper foil and aluminum foil. The solvent of the slurry cannot penetrate into the back to dry, and the drying process only occurs on the side of the coating slurry. Therefore, the advantages of floating drying can not be brought into play in the polar drying, but will cause waste of drying energy (heating, air supply). Therefore, the equipment structure of Hirano in Japan is complex and expensive, and the energy consumption is large, and the equipment operation cost is high.
The pole coating machine produced by some domestic companies imitates the double-sided air supply of the Japanese coating machine in form, but their nozzle structure can not produce wall-attached effect, and the wind speed of the nozzle is not enough to hold the dry pole, and can not form a floating state at all. This kind of double-sided air supply which blindly imitates floating drying does not have the advantages of floating drying, but instead brings the disadvantage of high energy consumption.
(4) Conventional convection hot air drying
Convection drying is a traditional drying technology. The heated dry air is sent into the drying tunnel, and the heat energy in the dry air is transferred to the dried object by convection of the air, so that the liquid evaporates and vaporizes for drying. Its advantage is that the equipment is simple. Its disadvantage is low drying efficiency. In modern drying equipment, it is gradually replaced by high efficiency hot air impact drying.
(5) Characteristics and application of circulating hot air impact drying
The hot air impact drying technology is an efficient drying technology developed by using the principle of air jet hydrodynamics. The dry air is sprayed to the surface of the dried object at high speed through the specially designed air nozzle, which prevents the dry still air layer from being destroyed under the impact on the surface of the dried object, thus speeding up the drying process and greatly improving the drying efficiency. The conditions for forming impact drying are:
With jet air nozzle (can be air nozzle, slot or round hole)
The form, arrangement, structure and quantity of nozzle shall be optimized
The injection speed at the injection port is large enough to destroy the static air layer on the dry surface
The characteristics of circulating hot air impact drying are:
Drying speed is related to temperature and drying air volume. The drying speed can be increased by partially circulating dry air supply, and the heat utilization of dry air can be greatly improved. Therefore, the circulating hot air impact drying has the characteristics of high efficiency and energy saving. The drying efficiency of the optimized impact drying is twice as high as that of the ordinary hot air drying. It is especially suitable for drying sheet or strip materials, so it is widely used in film drying. In addition, the drying speed can be improved by increasing the air supply volume, which can avoid the cracking and drying malady that may be caused by high temperature drying.
At present, the hot air drying for the coating machine produced by some manufacturers also uses the air nozzle to supply air, which is similar to the impact drying in form, but the structural design of the air nozzle and the air volume and wind speed can not play an impact effect. The drying process is still convection drying, and the drying efficiency is not high.
3. Basic process of hot air drying
The drying of the coated slurry consists of the following two heat and mass transfer processes:
(1) Evaporation and vaporization process of surface liquid
The wet coating absorbs the heat of the dry air through the heat exchange with the dry hot air. The liquid on the surface of the coating constantly evaporates into steam and enters the air, and the steam is taken away by the dry air.
When the liquid content of wet coating is high (above the critical moisture content), the speed of surface vaporization depends on the following factors:
Surface air flow velocity
Humidity of dry air
Temperature of dry air
When the coating is dried to the critical moisture content, the vaporization rate of the surface depends on the diffusion rate of the liquid inside the coating.
(2) Internal liquid diffusion process
Because of the vaporization on the coating surface, the concentration of the liquid on the coating surface becomes smaller, and the liquid inside the coating continuously diffuses to the surface.
4. Stage of drying process
The drying process of materials is divided into the following stages:
(1)
Transition stage: the coated coating enters the drying oven, and the temperature of the film gradually decreases due to the vaporization and heat absorption of solvent or water. There is leveling process.
(2)
Characteristics of constant rate drying stage:
① There is enough water or solvent on the coating surface,
② The drying rate is controlled by the external conditions - gasification rate.
③ Constant drying rate
④ Most of the water or flux is vaporized at this stage.
⑤ The surface temperature of the coating is equal to the wet bulb temperature of the dry air
(3) Drying stage:
① Drying speed is controlled by internal diffusion speed
② Decrease in drying rate
③ The coating temperature rises and the drying time is long
Drying control (7.5)
Basic parameters of drying control in the constant speed drying stage:
Dry bulb temperature of dry air
Moisture content in air (solvent content)
Air velocity
4. The drying defects of the pole piece are cracked
9. How to operate the automatic coater?
Operation method:
(1) First, plug the power plug of the PUMP into the power socket at the back of the coater.
(2) Insert the coating machine plug into the 110V power socket, and then press the [POWER] key.
(3) Set the rotational speed and time of rotation. This model is a two-stage accelerating Spin Coating, with the first acceleration on the right and the second acceleration on the left.
(4) Depending on the base material of different sizes, different rotary turntables can be replaced for hiking.
(5) Press the [PUMP] key, at this time, the rotary table will absorb the substrate, and then evenly and slowly spread the photoresist from the center of the substrate to an appropriate amount in a spiral manner. When doing the photoresist coating action, you can first use nitrogen to blow the surrounding of the rotary table and the substrate clean.
(6) Cover the protective cover of the coater to prevent the photoresist from splashing out of the coater.
(7) Press the [START] key, and the coater will start coating.
(8) After coating, open the protection, press the [PUMP] key to rotate the turntable to release the substrate, and then the substrate can be taken out.
10. The coating machine uses solvent-based oil glue. Is it good for electric heating or hot air drying? Which one has high safety performance?
Start the circulating air at the same time of electric heating. Generally, the coating machine has a recovery unit to recover the solvent polluted by oil. Heating is drying, circulating air is an important parameter to determine adhesion, and the recycling machine is used to control your solvent residue.
It depends on the setting of coating parameters, the heating oven of the machine itself and the quality of the recycling machine.
11. What is the coating amount?
Coating refers to the method of coating paste polymer, melt polymer or polymer melt on paper, cloth and plastic film to produce composite materials (films). The amount should refer to the weight of the coating, such as glue.
12. What is coated paper?
Coated paper, commonly known as coated paper, has many kinds and can be used for printing various color prints. The types of coated paper are as follows:
1. One-sided coated paper: coated and calendered on one side