Method for manufacturing coating liquid discharge nozzle and coated substrate

Abstract

The present invention provides a coating liquid discharge nozzle that can eliminate the thickening of the coating film at the edges, regardless of the coating conditions. [Solution] The coating liquid discharge nozzle of the present invention comprises a manifold for spreading the coating liquid in the width direction of the nozzle, a slit-shaped coating liquid discharge port extending in the width direction, and a slit-shaped flow path connecting the manifold and the coating liquid discharge port, wherein the slit-shaped flow path has a projection whose starting end is at the boundary between the slit-shaped flow path and the manifold, or on the manifold side of the boundary, extending in the direction toward the coating liquid discharge port from the starting end, and whose end does not reach the coating liquid discharge port, and the portion of the projection prevents the inflow of coating liquid from the manifold into the slit-shaped flow path, and the projection is located within a region of 30 mm from each end of the coating liquid discharge port when viewed from a direction perpendicular to the width direction, and is located only within that region.

Description

Technical Field

[0001] The present invention relates to a coating liquid discharge orifice for forming a coating film on a substrate, and particularly to a coating liquid discharge orifice capable of eliminating thickening of the end portion of the coating film under any coating conditions, and a method for manufacturing a substrate with a coating film using the coating liquid discharge orifice.

Background Art

[0002] Coating technologies for forming functional coating films on substrates such as films, metal foils, papers, textiles, non-woven fabrics, and glass are used in various fields such as functional films, paper products, fabric products, film products, batteries, household electrical appliance members, and semiconductor members. Particularly, for applications where film thickness uniformity of the coating film is required, a coating liquid discharge orifice (slot die, slit die) having a manifold, slit-shaped flow paths, and slit-shaped discharge ports inside is preferably used.

[0003] The liquid coating film formed on the substrate by the coating liquid discharge orifice generally undergoes a drying process to remove the solvent and is fixed on the substrate as a solid film. In this drying process, an edge height phenomenon often occurs where the film at the widthwise end of the coating film becomes thick. This is caused by the fact that drying progresses rapidly locally at the end of the coating film, resulting in a surface tension difference between the end of the coating film and the inside thereof, and the coating liquid gathers at the end. Also, in the conveyance process from the coating device to the drying device, the edge of the coating film is deformed into a round shape by surface tension, and the edge height phenomenon may also occur due to the movement of the coating liquid at the outermost end of the coating film to the inside. Such an edge height phenomenon not only causes quality degradation due to non-uniform film thickness but also causes winding collapse due to the film thickness difference when the substrate is in a roll shape. Therefore, suppression of the edge height phenomenon is necessary for production stabilization.

[0004] As a method to suppress this edge-raising phenomenon, Patent Documents 1 and 2 disclose a method in which the width of the slit-shaped flow channel inside the coating liquid discharge nozzle is increased from the manifold toward the discharge port. In this method, since the width of the outlet is wider than the width of the inlet of the slit-shaped flow channel, the coating liquid is distributed so that it spreads outwards at the ends of the slit-shaped flow channel, and the flow rate of the coating liquid discharged from the ends is less than that of the central part. As a result, the thickening of the coating film edges that occurs during drying is offset, and the edge-raising phenomenon can be suppressed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-039807 [Patent Document 2] Japanese Patent Application Publication No. 11-169782 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the methods disclosed in Patent Documents 1 and 2 have the problem that a coating film with a uniform thickness cannot be obtained depending on the degree and location of thickening at the edges of the coating film. For example, under coating conditions where thickening at the edges of the coating film is significant, increasing the expansion ratio of the slit-shaped channel width can greatly reduce the flow rate of the coating liquid discharged from the edges and eliminate the edge-high phenomenon. However, at the same time, the flow rate of the coating liquid decreases over a wide area near the edges of the coating width, resulting in excessive thinning inside the edges of the coating film. Similarly, under coating conditions where thickening at the edges of the coating film occurs slightly inside the outermost edge, increasing the expansion ratio of the slit-shaped channel width can reduce the flow rate of the coating liquid over a wide area at the edges in the coating width direction and eliminate the edge-high phenomenon. However, at the same time, the flow rate of the coating liquid decreases excessively at the outermost edge in the coating width direction, causing the coating film to be intermittently cut and resulting in the drawback of a wavy edge.

[0007] Therefore, the present invention provides a coating liquid discharge nozzle that can eliminate the thickening of the coating film at the edges, regardless of the coating conditions. [Means for solving the problem]

[0008] [1] The coating liquid discharge nozzle of the present invention solves the above problems, It has a manifold that spreads the coating liquid in the width direction of the nozzle, a slit-shaped coating liquid discharge port that extends in the width direction, and a slit-shaped flow path that connects the manifold and the coating liquid discharge port, Within the slit-shaped channel described above, there is a projection whose starting end is at the boundary between the slit-shaped channel and the manifold, or is on the manifold side of the boundary, extends in the direction toward the coating liquid discharge port from the starting end, and whose end does not reach the coating liquid discharge port, and the portion of the projection is such that it obstructs the inflow of coating liquid from the manifold into the slit-shaped channel. The above-mentioned protrusions are located within a region of 30 mm from each end of the coating liquid discharge port when viewed from a direction perpendicular to the width direction, and are located only within that region.

[0009] Furthermore, the coating liquid discharge nozzle of the present invention is preferably in any of the following embodiments [2] to [5]. [2] The coating nozzle of [1], wherein a plurality of the above-mentioned protrusions are arranged in the width direction within each of the above-mentioned regions. [3] The coating nozzle according to [2], wherein the widths of the multiple protrusions differ within each of the above-mentioned regions. [4] The coating nozzle according to [2] or [3], wherein the distance from the end of the plurality of protrusions to the coating nozzle is different in each of the above regions. [5] A coating nozzle according to any of the above [1] to [4], further comprising: a pre-manifold located upstream of the above manifold in the direction of coating discharge, which spreads the coating in the width direction of the nozzle; and a slit-shaped intermediate slit-shaped flow path connecting the above manifold and the pre-manifold.

[0010] [6] The present invention also provides a method for manufacturing a coated substrate, comprising the steps of applying a coating film onto a substrate using any of the coating liquid discharge nozzles described in [1] to [5] above, and drying the coating film to form a coating on the substrate.

[0011] In this application, "width direction of the coating liquid discharge nozzle" and "width direction of coating" refer to the direction indicated by the symbol WD in Figure 1, and may be simply referred to as "width direction" in this application. [Effects of the Invention]

[0012] According to the coating liquid discharge nozzle of the present invention, the projection prevents the inflow of the coating liquid from the manifold into the slit-shaped flow path, thereby reducing the flow rate of the coating liquid discharged from the discharge nozzle at any position in the coating width direction. As a result, regardless of the coating conditions, the flow rate of the coating liquid can be adjusted according to the shape of the thickening at the edges of the coated film, eliminating the edge-heavy phenomenon and enabling the acquisition of a coated film with a uniform film thickness across its entire width.

[0013] Furthermore, according to a preferred embodiment of the present invention, the amount of reduction in the flow rate of the coating liquid and the affected area can be more easily controlled by changing the width of the protrusion and the distance from the end of the protrusion to the outlet. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic diagram of the coating liquid discharge nozzle according to Embodiment 1 of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of the internal flow path of the coating liquid discharge nozzle shown in Figure 1, viewed from the X direction. [Figure 3] Figure 3 is a schematic diagram showing the distribution of the flow rate Q of the coating liquid discharged from the outlet. [Figure 4] Figure 4 is a detailed, enlarged view of the protrusion shown in Figure 2. [Figure 5] Figure 5 is a detailed, enlarged view of the projection of the coating liquid discharge nozzle according to Embodiment 2 of the present invention. [Figure 6] Figure 6 is a schematic diagram of the coating liquid discharge nozzle according to Embodiment 3 of the present invention. [Figure 7] Figure 7 is a detailed view showing an example of the shape of the protrusion. [Figure 8] Figure 8 is a graph showing the measurement results of the film thickness for Example 1 and Comparative Example 1. [Modes for carrying out the invention]

[0015] Preferred embodiments of the present invention will be described below. The following description illustrates embodiments of the invention, and the present invention is not construed as being limited thereto, and various modifications can be made without departing from the object and effects of the present invention.

[0016] [Embodiment 1] FIG. 1 is a schematic view of a coating liquid discharge nozzle 100 according to Embodiment 1 of the present invention. The coating liquid discharge nozzle 100 is composed of a block 11 and a block 12. The block 12 is provided with a coating liquid supply port 1 and a manifold 2 for expanding the coating liquid in the width direction WD. A shim 13 is interposed between the block 11 and the block 12. The shim 13 has a portion forming a slit-shaped flow path 3 and a portion communicating the slit-shaped flow path 3 with the manifold 2 cut out. Among the cutouts of the shim 13, the "portion communicating the slit-shaped flow path 3 with the manifold 2" is a portion overlapping the manifold 2 when viewed from the X direction in a state where the block 12 and the shim 13 are combined, and the other portion is the slit-shaped flow path 3. In the following description, the "portion communicating the slit-shaped flow path 3 with the manifold 2" is treated as a part of the manifold 2.

[0017] With block 11, block 12, and shim 13 assembled, the slit-shaped channel 3 communicates with the manifold 2, and the opening of the coating liquid discharge nozzle 100 communicating with the slit-shaped channel 3 becomes the coating liquid discharge port 4. In Figure 1, block 11 and shim 13 are shown separated to explain the internal structure, but in reality they are tightly fixed together by fastening bolts (not shown). Furthermore, shim 13 is provided with protrusions 5 on the inside of the slit-shaped channel 3, near both ends in the coating width direction WD. The protrusions 5 start from the end of the manifold 2 (the "part connecting the slit-shaped channel 3 and the manifold 2" which is treated as part of the manifold 2) and extend toward the discharge port 4, but their ends do not reach the discharge port 4 and end in the middle of the slit-shaped channel 3. Since the thickness of the protrusions 5 is approximately the same as the gap in the slit-shaped channel 3, i.e., the thickness of shim 13, the inflow of coating liquid from the manifold 2 to the slit-shaped channel 3 is obstructed in the part where the protrusions 5 are located. On the other hand, when viewed from the X direction, the manifold 2 is in communication with the width direction WD on the back side of the projection 5, so the projection 5 does not obstruct the spread of the coating liquid in the width direction WD within the manifold 2.

[0018] Figure 2 is a schematic cross-sectional view of the internal flow path of the coating liquid discharge nozzle 100 in Figure 1, viewed from the X direction, and the arrows in Figure 2 indicate the flow of the coating liquid. The coating liquid supplied from the supply port 1 spreads in the width direction in the manifold 2 and is discharged from the discharge port 4 through the slit-shaped flow path 3. At this time, the inflow of the coating liquid is obstructed in the part of the slit-shaped flow path 3 where there is a projection 5, but downstream of the end of the projection 5 in the slit-shaped flow path 3, the coating liquid flows in by going around the projection 5, so the coating liquid is discharged from the discharge port 4 over the entire width direction. However, in the part where there is a projection 5, the coating liquid can only flow in by going around from the surroundings, so the flow rate of the coating liquid discharged from the discharge port 4 is less than in the part without a projection 5.

[0019] In the configurations shown in Figures 1 and 2, the projection 5 starts from the upper end of the manifold 2, but the starting end of the projection 5 only needs to be at the boundary between the slit-shaped channel 3 and the manifold 2, or on the manifold 2 side of the boundary. If the projection 5 starts from the boundary or on the manifold 2 side of the boundary, the inflow of the coating liquid from the manifold 2 to the slit-shaped channel 3 can be obstructed at the portion of the projection 5 that is located there.

[0020] Figure 3 shows a schematic diagram of the flow rate Q of the coating liquid discharged from the discharge port 4. The vertical axis of the graph represents the flow rate Q per unit width, and the horizontal axis Y represents the position in the width direction of the coating liquid discharge nozzle 100. The flow rate Q decreases in and around the area where the protrusion 5 is located. As a result, the coating film becomes thinner in the area where the protrusion 5 is located. This can be used to measure in advance the distance D from the edge of the coating film in the area where the coating film becomes thicker under coating conditions where the edge-heavy phenomenon occurs during the drying process. Then, as shown in Figure 2, if the protrusion 5 is positioned at a distance D from the end of the discharge port 4, the decrease in flow rate Q due to the protrusion 5 and the thickening of the coating film during the drying process cancel each other out, eliminating the edge-heavy phenomenon. Here, distance D refers to the distance from the end of the discharge port 4 to the center in the width direction of the end of the protrusion 5.

[0021] According to the coating liquid discharge nozzle of the present invention, regardless of where in the coating width direction the coating film thickens, the edge-raising phenomenon can be eliminated by changing the position of the projection 5. In particular, under coating conditions where the pre-drying film thickness is large and the coating film thickening occurs inside the 10 mm position from the edge (towards the center in the width direction), the methods of Patent Document 1 and Patent Document 2 are difficult to address, making the method of the present invention effective. Here, the position where the coating film thickening occurs is within 30 mm from the edge, even under coating conditions where the pre-drying film thickness is particularly large (hundreds of μm to several mm), so it is preferable to provide the projection 5 only within 30 mm from both ends of the discharge nozzle 4.

[0022] Furthermore, with the coating liquid discharge nozzle of the present invention, regardless of the degree or extent of thickness of the coated film, the edge-raising phenomenon can be eliminated by changing the shape of the projection 5. Figure 4 is a detailed enlarged view of the projection 5 in Figure 2. For example, increasing the width W of the projection 5 can increase the decrease A of the flow rate Q in Figure 3. Also, increasing the distance L from the end of the projection 5 to the discharge port 4 in Figure 4 can widen the range B of the flow rate reduction while decreasing the decrease A of the flow rate Q in Figure 3. In other words, by changing the width W of the projection 5 and the distance L from the end of the projection 5 to the discharge port 4, the edge-raising phenomenon of any shape can be eliminated.

[0023] For example, if you want to eliminate a steeply shaped edge rise phenomenon, that is, if you want to increase the amount A of the decrease in flow rate Q in Figure 3 while narrowing the range B of the decrease in flow rate Q, you can increase the width W of the projection 5 while decreasing the distance L from the end of the projection 5 to the outlet 4. As another example, if you want to eliminate a gently shaped edge rise phenomenon, that is, if you want to decrease the amount A of the decrease in flow rate Q in Figure 3 while widening the range B of the decrease in flow rate Q, you can decrease the width W of the projection 5 while increasing the distance L from the end of the projection 5 to the outlet 4.

[0024] [Embodiment 2] Figure 5 is an enlarged detail view of the projections 5a and 5b of the coating liquid discharge nozzle 101 of Embodiment 2 of the present invention. It is the same as the coating liquid discharge nozzle 100 in Figure 1, except that there are two projections at each end in the coating width direction. By providing multiple projections as in the coating liquid discharge nozzle 101 of Figure 5, the discharge flow rate can be adjusted over a wider range than when there is only one projection. In particular, when the thickening of the coating film due to the edge-raising phenomenon occurs over a wide range and the degree of thickening is small, it is preferable to provide multiple projections 5 to increase the range B of the decrease in flow rate Q in Figure 3, and further increase the distances La and Lb from the ends of the projections 5a and 5b to the discharge port 4 to keep the amount of decrease A of the flow rate Q in Figure 3 small. Here, the widths Wa and Wb of the projections 5a and 5b and the distances La and Lb from the ends of the projections 5a and 5b to the discharge port 4 may be different for each of the multiple projections, and the dimensions should be determined according to the shape of the thickened coating film.

[0025] Even when multiple protrusions are provided at the ends in the coating width direction, it is preferable that the protrusions be provided only within 30 mm of both ends of the discharge port.

[0026] [Embodiment 3] Figure 6 is a schematic diagram of a coating liquid discharge nozzle 102 according to Embodiment 3 of the present invention. In the coating liquid discharge nozzle 102 of Figure 6, a pre-manifold 6 is provided further upstream of the manifold 2. The manifold 2 and the pre-manifold 6 are connected by an intermediate slit flow path 7, and the coating liquid supply port 1 is also connected to the pre-manifold 6. The coating liquid supplied from the coating liquid supply port 1 in Figure 6 is spread in two stages by the pre-manifold 6 and the manifold 2, and is discharged from the discharge port 4 through the slit flow path 3. By using a coating liquid discharge nozzle with such a multi-stage manifold, the coating liquid spreads more uniformly in the width direction, and a coating film with excellent uniformity of film thickness can be obtained. In the above coating liquid discharge nozzle 102, in order to eliminate the edge height phenomenon using the projection of the present invention, it is preferable to provide a projection 5 at least at the boundary between the slit flow path 3 closest to the discharge port 4 and the manifold 2. Although additional protrusions may be provided at the boundary between the upstream manifold 6 and the intermediate slit channel 7, the coating liquid passing through the intermediate slit channel 7 is spread out again in the width direction and homogenized in the manifold 2, so the flow rate adjustment effect of the additional protrusions is small.

[0027] In the embodiments described above, the shape of the projection 5 is shown as rectangular, but it is not limited to this. Any shape is acceptable as long as it prevents the inflow of the coating liquid into the slit-shaped channel 3 and allows the coating liquid to merge between the end of the projection 5 and the discharge port 4. For example, if the projection has a triangular end as shown in Figure 7(a) or a circular end as shown in Figure 7(b), the coating liquid will merge easily at the end of the projection and will not accumulate. Also, if the projection is trapezoidal as shown in Figure 7(c) or inclined as shown in Figure 7(d), the flow of the coating liquid that wraps around the left and right sides of the projection will be asymmetrical, which can eliminate the edge elevation phenomenon even with complex shapes. [Examples]

[0028] Specific examples of the present invention and comparative examples different from the present invention are shown below. However, the present invention is not limited to the examples shown below, and various modifications are possible without departing from the purpose and effects of the present invention.

[0029] [Common Implementation Conditions] A simulated experiment was conducted to form a coated film on a 0.7 mm thick glass substrate using a coating nozzle composed of two blocks and one shim, similar to Figure 1. The coating width of the coating nozzle was 100 mm, the thickness of the shim (i.e., the gap between the slit-shaped channels) was 0.5 mm, and the length of the slit-shaped channels in the flow direction was 19 mm. The coating liquid used was Unilube (registered trademark) (product number 75DE-2620, viscosity 47 Pa·s) manufactured by NOF Corporation. The coating speed was 17 mm / s, and the coating liquid discharge flow rate was adjusted with a syringe pump to achieve a film thickness of 700 μm before drying. Three minutes after coating, the film thickness of the coated film on the glass substrate was measured in the width direction using a multi-color laser coaxial displacement meter CL-3000 manufactured by Keyence Corporation. In this simulated experiment, the coated film was not dried.

[0030] [Comparative Example 1] First, as Comparative Example 1 of an embodiment different from the present invention, coating was performed using a coating liquid discharge nozzle without protrusions. The measurement results of the film thickness at the widthwise edge are shown by a dashed line in Figure 8. At a position 10 mm from the edge of the coated film, a thick film area was formed due to the flow of the coating liquid caused by surface tension, and the edge-raising phenomenon occurred.

[0031] [Example 1] Next, coating was performed using the coating liquid discharge nozzle 100 of the present invention shown in Figure 1. In Figures 2 and 4, the distance D from the widthwise end to the projection 5 was 10 mm, the width W of the projection 5 in Figure 4 was 1 mm, and the distance L from the end of the projection 5 to the discharge nozzle 4 was 5 mm. The shape of the projection 5 was derived using fluid simulation (Siemens, STAR-CCM+(registered trademark)) based on the results of Comparative Example 1. The measurement results of the coating film thickness in Example 1 are also shown by a solid line in Figure 8. No thick film portion was formed at the widthwise end, and the edge height phenomenon that occurred in Comparative Example 1 was eliminated. [Industrial applicability]

[0032] The coating liquid discharge nozzle of the present invention can be widely applied to various applications such as functional films, paper products, fabric products, membrane products, batteries, electrical appliance components, and semiconductor components. [Explanation of symbols]

[0033] 1. Coating liquid supply port 2 Manifold 3. Slit-shaped channel 4 outlet 5, 5a, 5b protrusions 6. Pre-stage manifold 7. Intermediate slit channel Blocks 11 and 12 13 Sims 100-102 Coating liquid discharge nozzle of the present invention A. Decrease in the flow rate of the coating solution B. Range of reduction in coating liquid flow rate D Distance from the end of the discharge port L, La, Lb: Distance from the end of the projection to the discharge port. Q: Flow rate of the coating solution W, Wa, Wb width of the protrusions Y-width position

Claims

1. A nozzle for applying a coating liquid to a substrate, A manifold for spreading the coating liquid in the width direction of the nozzle, A slit-shaped coating liquid discharge port extending in the width direction, It has a slit-shaped flow path that connects the manifold and the coating liquid discharge port, Within the slit-shaped channel, there is a projection whose starting end is at the boundary between the slit-shaped channel and the manifold, or is on the manifold side of the boundary, extends in the direction toward the coating liquid discharge port from the starting end, and whose end does not reach the coating liquid discharge port, and the portion of the projection is for preventing the inflow of coating liquid from the manifold into the slit-shaped channel. The aforementioned protrusions are located within a region of 30 mm from each end of the coating liquid discharge port, as viewed from a direction perpendicular to the width direction, and are located only within that region. Coating fluid discharge spout.

2. The coating liquid discharge nozzle according to claim 1, wherein a plurality of the protrusions are arranged in the width direction within each of the aforementioned regions.

3. The coating liquid discharge nozzle according to claim 2, wherein the widths of the plurality of protrusions are different within each of the aforementioned regions.

4. The coating nozzle according to claim 2, wherein the distance from the end of each of the multiple protrusions to the coating nozzle is different in each of the aforementioned regions.

5. A pre-manifold located upstream of the aforementioned manifold in the direction of coating liquid discharge, which spreads the coating liquid in the width direction of the nozzle, The manifold and the preceding manifold further have a slit-shaped intermediate slit-shaped flow path that connects them, A coating liquid discharge nozzle according to claim 1.

6. A method for manufacturing a coated substrate, comprising the steps of: applying a coating film onto a substrate using a coating liquid discharge nozzle according to any one of claims 1 to 5; and drying the coating film to form a coating on the substrate.

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