Double-layer coating die head and coating method thereof

Abstract

The present invention relates to a double-layer coating die head and a coating method thereof, belonging to the technical field of coating, the double-layer coating die head comprises an upper die, a middle die, a separation block, a lower die, an upper gasket, and a lower gasket, the upper die covers the middle die, the upper gasket is laid in the contact gap between the upper die and the middle die, the separation block is located between the middle die and the lower die, and the lower gasket is laid in the contact gap between the separation block and the lower die. The coating method is that the lower slurry is first attached to the foil material, and the upper slurry is attached to the lower slurry to form a double-layer coating. Due to the introduction of the separation block, the upper and lower flow channels of the present invention are forced to separate, the lower slurry first contacts the atmosphere, the liquid pressure is equal to the atmospheric pressure, and then contacts the upper slurry in the lip foil gap of the upper flow channel. At this time, due to the intervention of atmospheric pressure, the pressure of the lower flow channel is no longer disturbed by the upper flow channel, so that the pressures of the upper and lower flow channels are independent and do not interfere with each other.

Description

Technical Field

[0001] The invention relates to a double-layer coating die head and a coating method thereof, belonging to the technical field of coating. Background Art

[0002] As a precise wet coating technology, the coating die extrude the slurry onto the substrate along the gap of the coating die under a certain pressure and flow rate.

[0003] The current double-layer coating die consists of an upper die, a middle die, a lower die, and a gasket sandwiched between the dies. An upper gasket is set between the upper die and the middle die to form an upper slit; a lower gasket is sandwiched between the middle die and the lower die to form a lower slit, wherein the height of the gasket determines the height of the upper and lower slits. The slurry is squeezed and sprayed from the upper and lower slits onto the substrate to form two layers of slurry.

[0004] The utility model patent with patent application number 202321152108.3 discloses a double-layer coating die head, which belongs to the technical field of coating machines, including: an upper die head, a middle die head and a lower die head arranged in sequence, a first slurry flow channel is formed between the upper die head and the middle die head, and a second slurry flow channel is formed between the middle die head and the lower die head; the first interception block is slidably arranged in the upper die head, and the first adjustment mechanism drives the first interception block to extend into or retract into the first slurry flow channel to adjust the slurry flow in the first slurry flow channel; the second interception block is slidably arranged in the middle die head or the lower die head, and the second adjustment mechanism drives the second interception block to extend into or retract into the second slurry flow channel to adjust the slurry flow in the second slurry flow channel; the first adjustment mechanism and the second adjustment mechanism are arranged to respectively control the movement of the first interception block and the second interception block, and the flow rate of the slurry of the upper gasket and the lower gasket is controlled, so as to realize the adjustment of the double-layer thickness of the coating separately, so as to ensure that the coating thickness remains uniform.

[0005] When using the existing coating die head, there are the following defects that cannot be overcome for the time being:

[0006] (1) The physical movement formed by the upper and lower slurry layers, foil and lip of the above-mentioned coating die (utility model patent with patent application number 202321152108.3) is continuous and integrated. When the viscosity or flow rate difference between the upper and lower slurry layers is too large, the pressure of the layer of slurry with high viscosity and large flow rate at the lip of the die is high, while the pressure of the layer of slurry with low viscosity and low flow rate at the lip of the die is low, which can easily cause mixing of the slurry and lead to coating defects.

[0007] (2) When the viscosity or flow rate of the upper and lower layers of the slurry in the above-mentioned coating die head (utility model patent with patent application number 202321152108.3) is too different, due to the continuity and integrity, the shape of the coating beads of the upper and lower layers of the slurry is unstable, resulting in pressure fluctuations, which affects the coating consistency.

[0008] In summary, there is an urgent need to make targeted improvements to the coating die design, which is of great significance for improving battery performance. Summary of the invention

[0009] In order to solve the above problems, the present invention discloses a double-layer coating die head and a coating method thereof, and the specific technical scheme thereof is as follows:

[0010] A double-layer coating die head comprises an upper die (1), a middle die (2), a separation block (3), a lower die (4), an upper gasket (5), and a lower gasket (6); a concave groove is provided in the middle of the separation block (3) facing the coating side, which is called an upper lip overflow storage tank;

[0011] The middle mold (2) is provided with an upper distribution cavity (2-2) and an upper feed channel (2-1) connected to the upper distribution cavity (2-2); the upper mold (1) covers the middle mold (2); the upper gasket (5) is laid in the contact gap between the upper mold (1) and the middle mold (2); and the gap from the upper distribution cavity (2-2) to the upper lip (5-2) between the upper mold (1) and the middle mold (2) forms an upper flow-blocking channel (5-1);

[0012] The lower mold (4) is provided with a lower distribution cavity (4-2) and a lower feed channel (4-1) connected to the lower distribution cavity (4-2); the separation block (3) is located between the middle mold (2) and the lower mold (4); the lower gasket (6) is laid in the contact gap between the separation block (3) and the lower mold (4); and a lower flow-blocking channel (6-1) is formed from the lower distribution cavity (4-2) to the gap between the lower lip (6-2) between the separation block (3) and the lower mold (4);

[0013] The upper distribution cavity (2-2) and the lower distribution cavity (4-2) are both distributed transversely and do not penetrate the corresponding groove bodies at both ends of the middle mold (2) and the lower mold (4).

[0014] Furthermore, the upper surface of the upper mold (1) located at the upper lip (5-2) gradually changes to a pointed shape in a straight line toward the edge.

[0015] Furthermore, the upper flow-blocking channel (5-1) is arranged obliquely, and the lower flow-blocking channel (6-1) is arranged horizontally.

[0016] Furthermore, the upper portion of the separation block (3) facing the coating side is arranged to be inclined inward from top to bottom, and the side of the middle mold (2) facing the coating side is also inclined inward from top to bottom and aligned with the inclined surface of the separation block (3);

[0017] The lower part of the separation block (3) facing the coating side is arranged to be inclined inward from bottom to top, and the lower mold (4) is provided with a rectangular edge on the side facing the coating, and the edge of the rectangular edge is aligned with the lower edge of the separation block (3).

[0018] Furthermore, the pointed edges of the upper mold (1) and the middle mold (2) facing the coating side, the edge of the lower mold (4) on the coating side, and the upper and lower bevel edges of the separation block (3) are all located on the roller surface of a round roller.

[0019] Furthermore, the backs of the upper mold (1), the middle mold (2), the separation block (3) and the lower mold (4) are provided with two or more adjustment plates (8) symmetrically arranged along their length direction, the adjustment plates (8) are fixedly connected to the separation block (3) and the lower mold (4) by fixing bolts, and the adjustment plates (8) are connected to the middle mold (2) by adjusting bolts;

[0020] A staggered lip limiting device (9) is provided at the ends of the middle mold (2) and the separation block (3), and the staggered lip limiting device (9) is connected to the middle mold (2) and the separation block (3) via a plurality of bolts. The staggered lip limiting device (9) is also provided with a long strip-shaped limiting hole, and a positioning pin (10) is provided in the limiting hole. The positioning pin (10) passes through the staggered lip limiting device (9) and is connected to the middle mold (2).

[0021] Furthermore, the connection between the upper mold (1) and the middle mold (2), the connection between the middle mold (2) and the separation block (3), and the connection between the separation block (3) and the lower mold (4) are all countersunk connections, and the connection between the upper mold (1) and the middle mold (2), the connection between the middle mold (2) and the separation block (3), and the connection between the separation block (3) and the lower mold (4) are all perforated from top to bottom in the order of the upper mold (1), the middle mold (2), the separation block (3), and the lower mold (4), and the perforations of the connection between the middle mold (2) and the separation block (3), and the connection between the separation block (3) and the lower mold (4) are all arranged as strip holes.

[0022] Furthermore, the connection between the staggered lip limiting device (9) and the middle mold (2) and the separation block (3) is a countersunk hole connection, and the connecting countersunk hole between the staggered lip limiting device (9) and the middle mold (2) is a strip hole.

[0023] The double-layer coating method based on the above double-layer coating die head comprises the following steps:

[0024] Step 1: Setting a continuous production line, with the backing roller close to the upper lip (5-2) and the lower lip (6-2), and the upper lip (5-2) and the lower lip (6-2) are arranged around the backing roller;

[0025] Step 2: transporting the upper slurry and the lower slurry to their respective upper distribution chambers (2-2) and lower distribution chambers (4-2) through the upper feed channel (2-1) and the lower feed channel (4-1), adjusting the slurry until there are no bubbles in the slurry and the slurry can be discharged stably;

[0026] Step 3: The foil to be coated is conveyed forward through the surface of the backing roller;

[0027] Step 4: The lower layer slurry is extruded from the lower lip (6-2) and attached to the surface of the foil. The foil is pulled and moved by the back roller. When it passes through the upper lip (5-2), the upper layer slurry is attached to the lower layer slurry to form a double-layer coating.

[0028] Furthermore, in step 4, after the lower slurry is attached to the surface of the foil, the lower slurry first contacts the atmosphere, and the liquid pressure is equal to the atmospheric pressure. Then, at the upper lip (5-2) of the upper flow-blocking channel (5-1), the lower slurry layer on the surface of the foil contacts the upper slurry, forming a back roller-foil-lower slurry-upper slurry structure. At this time, due to the intervention of the atmospheric pressure between the upper lip (5-2) and the lower lip (6-2), the liquid pressure that originally connected the lower slurry and the upper slurry is disconnected, and the pressure of the lower channel is no longer affected by the upper channel, so that the pressures of the upper and lower channels are independent and do not interfere with each other.

[0029] The beneficial effects of the present invention are:

[0030] (1) The present invention provides a double-layer coating die head, which is composed of an upper die, a middle die, a lower die, a separation block, an upper gasket, and a lower gasket. The upper die, the upper gasket, and the middle die constitute an upper flow channel; the separation block, the lower gasket, and the lower die constitute a lower flow channel. The upper slurry flows in the upper flow channel, and the lower slurry flows in the lower flow channel. The lower slurry is attached to the moving foil, and the upper slurry is attached to the lower slurry, forming a double-layer coating. Due to the introduction of the separation block, the upper flow channel and the lower flow channel are forced to separate, and the lower slurry first contacts the atmosphere, and the liquid pressure is equal to the atmospheric pressure. Then, it contacts the upper slurry in the gap between the lip foil of the upper flow channel. At this time, due to the intervention of atmospheric pressure, the pressure of the lower flow channel is no longer affected by the upper flow channel, so that the pressures of the upper and lower flow channels are independent and do not interfere with each other.

[0031] (2) Compared with the existing design, the double-layer coating die head design proposed in the present invention introduces a separation block to achieve forced separation of the upper and lower coated slurries in a physical state between the foil and the lip, thereby solving the coating defects caused by pressure interference when the viscosity or flow rate difference between the upper and lower layers of slurry is too large, and improving the coating stability and consistency.

[0032] (3) The double-layer coating die head design proposed in the present invention mechanically connects two independent die heads through a separation block within the space of one coating die head (conventional bolt connection is optional), which simplifies the mechanical design, reduces the number of equipment in the coating production process and the complexity of installation.

[0033] (4) Based on the diversification of the functions of the double-layer die head at the end of use, and the huge difference in the viscosity of the upper and lower coating slurries, the coating thickness is greatly different. By raising the thickness of the separation block, the distance between the upper and lower layer lips is increased. This solves the pressure interference phenomenon caused by the upper and lower layer lips being too close. Pressure interference has a great impact on the consistency of the thickness of the upper and lower layers of coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the overall outline of the present invention,

[0035] Figure 2 is a lateral view of the present invention,

[0036] Figure 3 This is a diagram showing the simulation monitoring results of the upper and lower flow channel inlet pressures of the present invention.

[0037] Figure 4 It is the overall appearance diagram of the present invention,

[0038] Figure 5 Schematic diagram of the positions of the adjustment plate and the staggered lip limiting device of the present invention,

[0039] Figure 6 It is a position diagram of the strip holes designed for the connection between the separation block and the lower die of the present invention,

[0040] Figure 7 This is a bar hole position diagram designed for connecting the middle mold and the separation block of the present invention.

[0041] Figure 8 is a schematic structural diagram of the staggered lip limiting device of the present invention,

[0042] List of figure marks: 1—upper mold, 2—middle mold, 3—separation block, 4—lower mold, 5—upper gasket, 6—lower gasket, 7—back roller, 2-1—upper feed channel, 2-2—upper distribution cavity, 4-1—lower feed channel, 4-2—lower distribution cavity, 5-1—upper flow-blocking channel, 5-2—upper lip, 6-1—lower flow-blocking channel, 6-2—lower lip, 8—adjustment plate, 9—lip limit device, 10—locating pin, 11—limiting hole, 12—strip hole. DETAILED DESCRIPTION

[0043] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0044] Combined with Figure 1-2 It can be seen that the structure of the present invention is as follows: it includes an upper mold 1, a middle mold 2, a separation block 3, a lower mold 4, an upper gasket 5, and a lower gasket 6. The middle mold 2 is provided with an upper distribution cavity 2-2 and an upper feed channel 2-1 connected to the upper distribution cavity 2-2. The upper mold 1 covers the middle mold 2. The upper gasket 5 is laid in the contact gap between the upper mold 1 and the middle mold 2. From the upper distribution cavity 2-2 to the upper lip 5 between the upper mold 1 and the middle mold 2, -2 forms an upper flow-blocking channel 5-1; the lower mold 4 is provided with a lower distribution cavity 4-2 and a lower feed channel 4-1 connected to the lower distribution cavity 4-2, the separation block 3 is located between the middle mold 2 and the lower mold 4, the lower gasket 6 is laid in the contact gap between the separation block 3 and the lower mold 4, and the gap from the lower distribution cavity 4-2 to the lower lip 6-2 between the separation block 3 and the lower mold 4 forms the lower flow-blocking channel 6-1.

[0045] The upper distribution cavity 2-2 and the lower distribution cavity 4-2 are both horizontally distributed and do not penetrate the corresponding grooves at both ends of the middle mold 2 and the lower mold 4. The upper distribution cavity 2-2 and the lower distribution cavity 4-2 are the accommodating spaces for the upper slurry and the lower slurry to realize the flow control of the slurry.

[0046] The upper surface of the upper die 1 at the upper lip 5-2 gradually changes to a pointed shape toward the edge straight line, so that the upper slurry can be quickly extruded at the end of the upper flow-blocking channel 5-1 and evenly coated on the surface of the lower slurry layer on the foil surface.

[0047] The upper flow-blocking channel 5-1 is arranged obliquely, and the lower flow-blocking channel 6-1 is arranged horizontally. The separation block 3 is located at the upper part of the coating side and is arranged to be inclined inward from top to middle, and the middle mold 2 is also inclined inward from top to bottom on the coating side, and is aligned with the inclined surface of the separation block 3. The separation block 3 is located at the lower part of the coating side and is arranged to be inclined inward from bottom to top, and the lower mold 4 is provided with a rectangular edge on the coating side, and the edge of the rectangular edge is aligned with the lower edge of the separation block 3. The lower layer slurry in the layer-blocking flow channel 6-1 can also be squeezed out smoothly at the lip position and evenly coated on the foil surface. And the middle part of the separation block 3 is a horizontally through rectangular channel to facilitate the circulation of atmospheric pressure. See Figure 3 The separation block structure has been numerically simulated for fluids. During normal coating, the pressures of the upper and lower flow channels are independent of each other, do not interfere with each other, and have stable pressure distribution. The results of the on-site coating experiment show that changing the upper lip foil gap or the upper inlet flow rate only affects the pressure of the upper flow channel or the upper film thickness, while the pressure and film thickness of the lower flow channel are not affected. In addition, stable and high-quality coating can be achieved when there is a huge difference in the coating thickness or slurry viscosity between the upper and lower layers. It can be seen that the separation block is effective in isolating the interference of the upper and lower flow channels.

[0048] The pointed edge of the coating side of the upper die 1, the edge of the coating side of the lower die 4, the upper bevel edge and the lower bevel edge of the middle die 2 are all located on the roller surface of a round roller. The round roller is the back roller when working. When the back roller rotates to convey the foil, the upper lip 5-2 and the lower lip 6-2 are close to the back roller.

[0049] The upper mold, upper gasket and middle mold of the present invention constitute the upper runner; the separation block, lower gasket and lower mold constitute the lower runner. The upper slurry flows in the upper runner, and the lower slurry flows in the lower runner. The lower slurry is attached to the moving foil, and the upper slurry is attached to the lower slurry to form a double-layer coating. Due to the introduction of the separation block, the upper runner and the lower runner are forced to separate, the lower slurry first contacts the atmosphere, and the liquid pressure is equal to the atmospheric pressure, and then contacts the upper slurry in the lip foil gap of the upper runner. At this time, due to the intervention of atmospheric pressure, the pressure of the lower runner is no longer affected by the upper runner, so that the pressures of the upper and lower runners are independent and do not interfere with each other.

[0050] The working process of the present invention is:

[0051] Step 1: Set up a continuous production line, with the backing roller 7 close to the upper lip 5-2 and the lower lip 6-2, and the upper lip 5-2 and the lower lip 6-2 are distributed around the backing roller 7;

[0052] Step 2: The upper slurry and the lower slurry are respectively transported to the upper distribution chamber 2-2 and the lower distribution chamber 4-2 through the upper feed channel 2-1 and the lower feed channel 4-1, and the slurry is adjusted until there are no bubbles and the slurry can be discharged stably;

[0053] Step 3: The foil to be coated is conveyed forward through the surface of the backing roller;

[0054] Step 4: The lower slurry is extruded from the lower lip 6-2 and attached to the surface of the foil. The lower slurry first contacts the atmosphere, and the liquid pressure is equal to the atmospheric pressure. Then, at the upper lip 5-2 of the upper flow-blocking channel 5-1, the lower slurry layer on the foil surface contacts the upper slurry, forming a back roller-foil-lower slurry-upper slurry structure. The foil back roller is pulled and moved. When passing through the upper lip 5-2, the upper slurry is attached to the lower slurry. At this time, due to the intervention of the atmospheric pressure between the upper lip 5-2 and the lower lip 6-2, the liquid pressure that originally connected the lower slurry and the upper slurry is disconnected, and the pressure of the lower channel is no longer affected by the upper channel, so that the pressures of the upper and lower channels are independent and do not interfere with each other, forming a double-layer coating.

[0055] Finally, the interface between the two layers of slurry is relatively clear and will not mix. It will maintain its free nature and enter the oven all the way, with distinct layers after drying.

[0056] Compared with the existing design, the die head design proposed in the present invention introduces a separation block, which realizes the forced separation of the upper and lower coated slurries in the physical state between the foil and the lip, solves the pressure interference and slurry mixing problems when the viscosity or flow rate difference between the upper and lower layers of slurry is too large, and improves the coating stability and consistency.

[0057] The following describes how the patent adjusts the front-to-back distance between the upper lip and the lower lip:

[0058] The structure of the adjustment plate 8 is shown in the attached Figure 5 The backs of the upper mold 1, the middle mold 2, the separation block 3 and the lower mold 4 are provided with two or more adjustment plates 8 symmetrically arranged along their length directions. The adjustment plates 8 are fixedly connected to the separation block 3 and the lower mold 4 by fixing bolts, and the adjustment plates 8 are connected to the middle mold 2 by adjusting bolts.

[0059] The structure of the staggered lip limiting device 9 is shown in the attached Figure 5 , 6 and 8, in order to see the internal structure clearly, Figure 6 and 8 The staggered lip limit device 9 is a perspective view, the staggered lip limit device 9 is set at the end of the middle mold 2 and the separation block 3, the staggered lip limit device 9 is connected to the middle mold 2 and the separation block 3 through a plurality of bolts, and the staggered lip limit device 9 is also provided with a long strip of limiting holes 11, and a positioning pin 10 is set in the limiting hole, and the positioning pin 10 passes through the staggered lip limit device 9 and is connected to the middle mold 2.

[0060] See also Figure 6 and 7 The connection between the upper mold 1 and the middle mold 2, the connection between the middle mold 2 and the separation block 3, and the connection between the separation block 3 and the lower mold 4 are all countersunk connections, and the connection between the upper mold 1 and the middle mold 2, the connection between the middle mold 2 and the separation block 3, and the connection between the separation block 3 and the lower mold 4 are all perforated from top to bottom in the order of the upper mold 1, the middle mold 2, the separation block 3 and the lower mold 4, and the connection perforations between the middle mold 2 and the separation block 3, and the separation block 3 and the lower mold 4 are all arranged as strip holes 12.

[0061] See also Figure 8, the connection between the staggered lip limit device 9 and the middle mold 2 and the separation block 3 is a countersunk hole connection, and the connection countersunk hole between the staggered lip limit device 9 and the middle mold 2 is a strip hole 12. Usually the distance that the upper mold and the middle mold can move forward and backward is 3mm. The positioning pin 10 is fixed to the middle mold 2, and the staggered lip limit device 9 is fixed to the separation block 3. The staggered lip limit device 9 is a rectangular plate with two fixed connection holes, two strip holes, and one limiting hole 11. The two strip holes and one limiting hole 11 are located at the end of the middle mold 2, and the two fixed connection holes are located at the end of the separation block. The staggered lip limit device 9 is fixedly connected to the separation block by passing a connecting piece through the two fixed connection holes. The two strip holes are connected to the middle mold 2 through a connecting piece, and a positioning pin 10 passing through a limiting hole 11 is also connected to the middle mold 2. When the upper mold 1 and the middle mold 2 move as a whole along the separation block 3, the connecting pieces and the positioning pin 10 in the two strip holes and the limiting hole 11 move in their respective strip holes and the limiting hole 11, and the moving stroke of the positioning pin 10 is the length of the limiting hole 11. Usually, the moving length is within 3 mm.

[0062] The specific lip correction method is as follows:

[0063] Adjust the clamping hole to the waist hole, and the distance between the two centers of the waist hole is 2.0 mm. During the initial installation, the die head uses the back fixing block to align the back. Later, adjust the front and rear distance of the lip according to the actual coating process.

[0064] Due to the gap between the upper and lower lips, the two single-layer die heads can be considered to be superimposed when coating at the same time. At the same time, in order to prevent the excess slurry on the upper layer from dripping directly onto the lip of the lower die when coating the upper die, the function of the lip liquid storage tank is also considered.

[0065] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0066] With the above-mentioned ideal embodiments of the present invention as inspiration, through the above-mentioned description content, relevant personnel can make various changes and modifications without departing from the scope of the technical idea of ​​the present invention.

Claims

1. A double-layer coating die head, characterized in that: It comprises an upper die (1), a middle die (2), a separation block (3), a lower die (4), an upper gasket (5), and a lower gasket (6); a concave groove is provided in the middle of the separation block (3) facing the coating side, which is called an upper lip overflow storage tank; The middle mold (2) is provided with an upper distribution cavity (2-2) and an upper feed channel (2-1) connected to the upper distribution cavity (2-2); the upper mold (1) covers the middle mold (2); the upper gasket (5) is laid in the contact gap between the upper mold (1) and the middle mold (2); and the gap from the upper distribution cavity (2-2) to the upper lip (5-2) between the upper mold (1) and the middle mold (2) forms an upper flow-blocking channel (5-1); The lower mold (4) is provided with a lower distribution cavity (4-2) and a lower feed channel (4-1) connected to the lower distribution cavity (4-2); the separation block (3) is located between the middle mold (2) and the lower mold (4); the lower gasket (6) is laid in the contact gap between the separation block (3) and the lower mold (4); and a lower flow-blocking channel (6-1) is formed from the lower distribution cavity (4-2) to the gap between the lower lip (6-2) between the separation block (3) and the lower mold (4); The upper distribution cavity (2-2) and the lower distribution cavity (4-2) are both distributed transversely and do not penetrate the corresponding groove bodies at both ends of the middle mold (2) and the lower mold (4); The upper surface of the upper mold (1) located at the upper lip (5-2) gradually changes to a pointed shape toward the edge straight line; The upper flow-blocking channel (5-1) is arranged obliquely, and the lower flow-blocking channel (6-1) is arranged horizontally; The upper portion of the separation block (3) facing the coating side is arranged to be inclined inward from top to bottom, and the side of the middle mold (2) facing the coating side is also inclined inward from top to bottom and aligned with the inclined surface of the separation block (3); The lower part of the separation block (3) facing the coating is arranged to be inclined inward from bottom to top, and the lower mold (4) is provided with a rectangular edge on the side facing the coating, and the edge of the rectangular edge is aligned with the lower edge of the separation block (3); The pointed edges of the upper mold (1) and the middle mold (2) facing the coating side, the edge of the lower mold (4) on the coating side, and the upper and lower bevel edges of the separation block (3) are all located on the roller surface of a round roller; The middle part of the separation block (3) is a transversely penetrating rectangular channel, which facilitates the circulation of atmospheric pressure.

2. The double-layer coating die head according to claim 1, characterized in that: The backs of the upper mold (1), the middle mold (2), the separation block (3) and the lower mold (4) are provided with two or more adjustment plates (8) symmetrically arranged along their length direction; the adjustment plates (8) are fixedly connected to the separation block (3) and the lower mold (4) by fixing bolts; and the adjustment plates (8) are connected to the middle mold (2) by adjusting bolts; A staggered lip limiting device (9) is provided at the ends of the middle mold (2) and the separation block (3), and the staggered lip limiting device (9) is connected to the middle mold (2) and the separation block (3) via a plurality of bolts. The staggered lip limiting device (9) is also provided with a long strip-shaped limiting hole, and a positioning pin (10) is provided in the limiting hole. The positioning pin (10) passes through the staggered lip limiting device (9) and is connected to the middle mold (2).

3. The double-layer coating die head according to claim 1, characterized in that: The connection between the upper mold (1) and the middle mold (2), the connection between the middle mold (2) and the separation block (3), and the connection between the separation block (3) and the lower mold (4) are all countersunk connections, and the connection between the upper mold (1) and the middle mold (2), the connection between the middle mold (2) and the separation block (3), and the connection between the separation block (3) and the lower mold (4) are all perforated from top to bottom in the order of the upper mold (1), the middle mold (2), the separation block (3), and the lower mold (4), and the perforations of the connection between the middle mold (2) and the separation block (3), and the connection between the separation block (3) and the lower mold (4) are all arranged as strip holes.

4. The double-layer coating die head according to claim 2, characterized in that: The connection between the staggered lip limiting device (9) and the middle mold (2) and the separation block (3) is a countersunk hole connection, and the connecting countersunk hole between the staggered lip limiting device (9) and the middle mold (2) is a strip hole.

5. A double-layer coating method based on the double-layer coating die head according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Setting a continuous production line, with the backing roller close to the upper lip (5-2) and the lower lip (6-2), and the upper lip (5-2) and the lower lip (6-2) are arranged around the backing roller; Step 2: transporting the upper slurry and the lower slurry to their respective upper distribution chambers (2-2) and lower distribution chambers (4-2) through the upper feed channel (2-1) and the lower feed channel (4-1), adjusting the slurry until there are no bubbles in the slurry and the slurry can be discharged stably; Step 3: The foil to be coated is conveyed forward through the surface of the backing roller; Step 4: The lower layer slurry is extruded from the lower lip (6-2) and attached to the surface of the foil. The foil is pulled and moved by the back roller. When it passes through the upper lip (5-2), the upper layer slurry is attached to the lower layer slurry to form a double-layer coating.

6. The double-layer coating method of the double-layer coating die head according to claim 5, characterized in that: In the step 4, after the lower slurry is attached to the surface of the foil, the lower slurry first contacts the atmosphere, and the liquid pressure is equal to the atmospheric pressure. Then, at the upper lip (5-2) of the upper flow-blocking channel (5-1), the lower slurry layer on the surface of the foil contacts the upper slurry, forming a back roller-foil-lower slurry-upper slurry structure. At this time, due to the intervention of the atmospheric pressure between the upper lip (5-2) and the lower lip (6-2), the liquid pressure that originally connected the lower slurry and the upper slurry is disconnected, and the pressure of the lower channel is no longer affected by the upper channel, so that the pressures of the upper and lower channels are independent and do not interfere with each other.

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