JP2009220025A - Extrusion coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a bead state in both end parts in the bead width direction to prevent the bead from running out to be damaged from both ends parts in the bead width direction even when the coating is carried out at high speed or thin film coating is made. <P>SOLUTION: In the extrusion coating apparatus where a coating liquid discharged to a clearance C between a web 22 wound around a backup roller 20 and continuously travelling and the head tip end of an extrusion type coating head 12 for discharging the coating liquid from a slit 16 is cross-linked to form the bead and is applied to the web 22 via the bead and a spacer 24 for regulating the coating width is inserted in both end parts of the slit 16 in the width direction, at least the tip end part 24A of the spacer 24 is formed of a flexible member and the web is coated in a state that the tip end part is projected from the slit tip end and is made to abut on the web surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an extrusion coating apparatus, and more particularly to an extrusion coating apparatus capable of high-speed, thin-layer and stable coating.

  The extrusion coating apparatus spreads the coating liquid supplied to the pocket portion in the slot die in the coating width direction (same as the web width direction) in the pocket portion, and has a slot having a narrow gap communicating with the pocket portion (“ The coating liquid is discharged from the tip. On the other hand, the web to which the coating liquid is applied travels while being wound around a backup roller, and a bead (coating liquid reservoir) of the coating liquid discharged from the slot front end to the lip clearance between the slot die front end and the web. Then, a coating solution is applied to the web through this bead. Further, the coating width of the coating solution applied to the web is regulated by the distance between the spacers inserted at both ends in the slot width direction (same as the web width direction).

  Whether or not a stable bead is formed is very important in stable coating by such an extrusion coating apparatus. Particularly in recent years, in order to improve productivity, it has been required to increase the speed of the coating line (higher web traveling speed) and to reduce the thickness of the coating liquid to be applied. When such high-speed coating and thinning are performed, the bead often breaks from both ends in the bead width direction (same as the web width direction) and breaks down, and the bead state at both ends in the bead width direction. It is important how to stabilize. If the bead at the end in the bead width direction is not stabilized, a film thickness distribution is generated in the width direction of the applied coating film.

  As one method for stabilizing the bead, for example, as disclosed in Patent Document 1, pressure reduction is performed so as to pull the upstream side of the bead in the web traveling direction.

  In addition, there are many inventions that improve the uniformity of film thickness in the width direction of thin film coating by improving the slot die gap distribution in the coating width direction and the lip clearance distribution in the coating width direction with high accuracy. .

  However, in the slot die, when a thin coating is performed with a low viscosity (for example, 10 cP or less) coating solution with a lip clearance set to 300 μm or less, the capillary phenomenon of the lip clearance becomes remarkable. As a result, the coating solution at the coating end portion is wet spread and tends to wet and spread outward (in the web end direction). This wetting and spreading phenomenon has a great influence on the thickness distribution in the coating width direction of the coated film, particularly in the case of thin film coating. As a result, non-uniform performance in the width direction of the finally obtained product and a reduction in the yield of the product effective width are caused.

Patent Document 2 proposes to suppress this wetting and spreading by changing the shape of the spacer that changes the application width of the slot die.
JP 2001-300394 A JP 2001-170542 A

  However, the bead state at both ends in the bead width direction cannot be sufficiently stabilized only by reducing the pressure of the bead as in Patent Document 1.

  Further, as in Patent Document 2, simply changing the shape of the spacer cannot suppress the wetting and spreading of the coating liquid at the coating end portion and cannot improve the film thickness distribution in the coating film width direction.

  That is, wetting spread occurs when the capillary phenomenon of the meniscus at the lip clearance formed between the tip of the slot die and the web supported by the backup roll exceeds the force in the web running direction. This capillary phenomenon is not easily manifested when the liquid viscosity of the coating liquid is high or when the lip clearance is large, but is manifested in thin film coating with a low liquid viscosity and a narrow lip clearance. Therefore, in a thinner coating, the lip clearance of the slot die becomes smaller, the capillary action force becomes larger, and it becomes difficult to sufficiently prevent wetting and spreading only by changing the spacer shape.

  In addition, when the lip clearance is small as in the case of thin film, it is particularly susceptible to fluctuations in the thickness and shape of the web (thickness of the undercoat layer, curl due to the undercoat layer, the edge of the support itself, and the bevel due to conveyance). The lip clearance at the end in the coating width direction varies. Also from this, the pins (bead meniscus state) formed at both ends in the bead width direction cannot be stably held only by changing the shape of the spacer.

  The present invention has been made in view of such circumstances, and can stabilize the bead state at both ends in the bead width direction, so that both ends in the bead width direction can be applied to high-speed coating and thinning. An object of the present invention is to provide an extrusion coating apparatus in which a bead breaks and is difficult to break.

  According to a first aspect of the present invention, in order to achieve the above object, the discharged coating liquid is applied to a lip clearance between a web wound around a backup roller and continuously running and a slot die tip for discharging the coating liquid from the slot. In the extrusion coating apparatus in which a bead is formed by cross-linking, a coating liquid is applied to the web through the bead, and spacers for coating width regulation are inserted at both ends in the width direction of the slot. Provided is an extrusion coating apparatus characterized in that at least a tip portion of a spacer is formed of a flexible member, and coating is performed in a state where the tip portion protrudes from the slot tip and is in contact with the web surface. .

  According to the present invention, a spacer that is inserted into both end portions of the slot for restricting the coating width, the spacer having at least a tip portion formed of a flexible member, protrudes from the tip end of the slot and is wound around the backup roller. Since it is made to contact the web surface that is continuously run while being applied, the bead state at both ends in the bead width direction at the start of application and during application can be stabilized. That is, the shape of the spacer is required to have a projection length equivalent to the lip clearance in order to contact the web surface supported by the backup roller while having a thickness equivalent to the gap distance of the slot. The Here, the contact of the tip of the spacer with the web surface is not limited to the case where the spacer is in a straight state, and the tip of the spacer is in contact with the spacer. It also includes that the surface of the leading end of the spacer is in contact with the web surface while being bent in the rotation direction of the roller.

  As a result, the beads are cut off from both ends in the bead width direction and are not easily broken, so that stable coating can be performed even with high-speed coating or thin film coating.

  A second aspect of the present invention is characterized in that, in the first aspect, at least one groove that does not contact the web surface is provided at a tip portion of the spacer.

  Since there is at least one groove that does not contact the web surface at the tip of the spacer, the coating liquid that attempts to wet and spread at the coating edge stops spreading in the groove and does not progress further. Thereby, destabilization of the end part in the bead width direction due to wet spreading can be prevented.

  A third aspect of the present invention is characterized in that, in the first or second aspect, a protruding portion along the running direction of the web is provided at the tip of the spacer.

  According to the third aspect of the present invention, the bead state at both end portions in the bead width direction can be further stabilized by providing the protruding portion along the running direction of the web at the tip of the spacer. It is more preferable that the overhang portion has at least one groove that does not contact the web surface.

  A fourth aspect of the present invention is characterized in that in any one of the first to third aspects, a pressure reducing box is provided for depressurizing the upstream side of the bead in the web traveling direction.

  According to the fourth aspect of the present invention, both the contact of the spacer with the web and the decompression box are provided, and the bead state at both ends in the bead width direction can be further stabilized.

  A fifth aspect according to any one of the first to fourth aspects shows a degree of high-speed coating that particularly exhibits the effects of the present invention.

  A sixth aspect according to any one of the first to fifth aspects is characterized in that the liquid viscosity of the coating liquid applied to the web is 10 cP or less and the lip clearance C is 300 μm or less.

  The sixth aspect defines the viscosity of the coating liquid and the size of the lip clearance C in which the effect of the present invention is particularly exerted. As the action of the spacer in the present invention, from the viewpoint of suppressing the wetting and spreading of the coating liquid at the coating end, it can be considered that the smaller the liquid viscosity and the lip clearance C, the more effective the present invention can be. Not. However, if the lower limit is daringly defined, it has been confirmed that the present invention can be applied at a liquid viscosity of 0.5 cP. Further, it has been confirmed that the present invention can be applied when the lip clearance C is 130 μm.

  As described above, according to the extrusion coating apparatus of the present invention, the bead state at both ends in the bead width direction can be stabilized. The bead breaks from both ends, making it difficult to break. As a result, stable coating can be performed even when coating is speeded up or thinned.

  Hereinafter, preferred embodiments of an extrusion coating apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view of the extrusion coating apparatus 10 of the present invention as seen from above, and FIG. 2 is a side sectional view.

  As shown in these drawings, the slot die 12 has a pocket portion 14 and a narrow slot 16 communicating with the pocket portion 14 formed in the head, and a coating liquid discharge port at the tip of the slot 16 is formed at the tip of the head. An opening is formed in the substantially flat edge surface 18. The slot gap D is preferably in the range of 0.05 mm to 0.5 mm (see FIG. 2).

  On the other hand, the backup roller 20 is disposed close to the edge surface 18 of the slot die 12, and the web 22 to which the coating liquid L is applied is wound around and supported by the backup roller 20 and continuously travels in the direction of the arrow. The lip clearance C between the die edge surface 18 and the backup roller 20 is usually set in the range of 30 μm to 300 μm, and is appropriately set depending on the coating thickness, coating speed, physical properties (viscosity, etc.) of the coating liquid L, and the like. The As a result, the coating liquid L discharged from the slot 16 is bridged between the edge surface 18 and the web 22 to form a bead L1 (coating liquid pool, see FIG. 2), and the coating liquid L is passed through the bead L1. Is applied to the web 22. In addition, although the shape of the corner | angular part of the engine surface 18 and the engine surface 18 is shown in the curved R shape in FIG. 3, the edge surface 18 is made into a planar shape and a corner | angular part is not round like FIG. You may form in a sharp shape. The same applies to FIGS. 4 to 10 described below.

  Further, the coating width A of the coating liquid L applied to the web 22 is the distance between the pair of spacers 24 inserted at both ends in the width direction of the slot 16 (same as the web width direction) as shown in FIG. Regulated by (distance). The spacer 24 protrudes from the end of the slot 16 and comes into contact with the surface of the web 22 wound around the backup roller 20.

  As a material of the spacer 24, it is necessary that at least the tip 24A is a flexible material. Specifically, such as rubber, Teflon (registered trademark), triacetyl cellulose (TAC), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN) are not easily denatured with a solvent and have a certain degree of bending. Any material having a flexible property may be used. In addition, when rubber is used, it is preferable to perform coating such as urethane coating, Teflon (registered trademark), silicon coating, etc. so as to improve the slipperiness and wear resistance against contact with the web 22. . Further, it is possible to use a rubber material that is improved in slipping property and wear resistance by kneading Teflon (registered trademark), molybdenum, oil, or the like.

  About the shape and protrusion length of this spacer 24, the following aspects can be employ | adopted preferably.

  FIG. 3 shows a case of a rectangular plate-like spacer 24. 4 and 5 show the relationship between the rectangular plate-like spacer 24 and the lip clearance C. FIG. 4 shows the case where the protrusion length d (see FIG. 3) at which the spacer 24 protrudes from the slot tip is the same. It is. FIG. 5 shows the case where the spacer 24 is in contact with the web surface in such a manner that the protrusion length d from which the spacer 24 protrudes from the end of the slot is longer than the lip clearance C and is bent in the rotation direction of the backup roller 20. It is. In the case of FIG. 5, it is preferable that the bent tip portion has the same thickness as the lip clearance C.

  FIG. 6 shows a case where the outside of the tip end portion of the rectangular plate-like spacer 24 is cut into a triangular shape to reduce the contact area between the tip end of the spacer 24 and the web 22. FIG. 7 shows an L-shaped spacer 24 formed by forming an overhanging portion 24 </ b> A along the running direction of the web 22 at the tip of the spacer 24. In this case, the overhanging portion 24 </ b> A preferably overhangs downstream of the web 22 in the traveling direction. FIG. 8 shows a spacer 24 in which a T-shaped projecting portion 24 </ b> A along the running direction of the web 22 is provided at the distal end portion of the spacer 24. The thickness of the overhanging portion 24A in FIGS. 7 and 8 is preferably equal to the lip clearance C as shown in FIG. Further, FIG. 10 is a view in which a taper is formed on the lower surface side (the upstream side in the web running direction) of the front end of the spacer 24 of FIG.

  FIG. 11A shows a general spacer having a rectangular shape, and W1 is a spacer width. FIG. 11B shows a V-shaped groove 24 </ b> C formed on the coating inner side (center side in the slot width direction) of the front end surface of the rectangular spacer 24 having a larger width than that in FIG. W2 is the distance from the spacer end on the inner side of the application to the groove 24C, W3 is the width of the groove 24C (the width of the upper end of the groove), and W4 is the distance from the groove 24C to the spacer end on the outer side of the application. Therefore, W2 + W3 + W4 is W1 of the entire width of the spacer.

  FIG. 11C shows a V-shaped groove 24 </ b> C formed on the coating inner side (center side in the slot width direction) of the front end surface of the rectangular spacer 24. W2, W3, and W4 are the same as those in FIG. As a result, the coating solution that is about to wet and spread at the coating end portion stops spreading in the grooves 24C, and does not progress further. Thereby, destabilization of the end part in the bead width direction due to wet spreading can be prevented. In FIG. 11, the example of the V-shaped groove 24C and the concave groove 24C has been described, but the shape is not particularly limited as long as it is a groove. In FIG. 11, the groove is formed on the front end surface 24B of the rectangular plate-like spacer 24, but the groove may be formed on the front end surface 24B of the spacer having an overhanging FIG. 24B as shown in FIGS.

  Further, as shown in FIG. 2, a decompression box 26 is provided below the bead L1 to decompress the upstream side of the bead L1 in the web traveling direction. The decompression box 26 is formed in a box shape, and the upper surface of the box is opened in a long shape in the web width direction. A sealed space 28 is formed by the lip one surface 12A of the slot die 12 and the surface of the web 22 supported by the backup roller 20. The decompression box 26 is connected to a pipe 30 connected to a vacuum device (not shown), and depressurizes the sealed space 28 by driving the vacuum device. The degree of vacuum is preferably in the range of 0.01 to 2.0 kPa. Although not shown, it is preferable to provide a buffer tank (not shown) between the decompression box 26 and the vacuum device so that the degree of decompression in the sealed space 28 does not fluctuate.

  Next, the operation of the extrusion coating apparatus 10 configured as described above will be described.

  The coating liquid L supplied to the pocket portion 14 in the slot die 12 spreads in the coating width direction (same as the web width direction) in the pocket portion 14, and ascends the slot 16 whose coating width is regulated by the pair of spacers 24. Then, it is discharged from the slot tip. As a result, the coating liquid L is cross-linked to the lip clearance C between the edge surface 18 of the slot die 12 and the web 22, and a bead L1 (coating liquid pool) is formed.

  In such application, the bead L1 may be broken from both ends in the bead width direction (same as the web width direction), and the bead L1 may be broken. In particular, the bead L1 is easily collapsed when the discharge amount of the coating liquid L discharged from the slot 16 is small as in thin film coating. For example, when a low viscosity (10 cPC or less) coating solution is applied at high speed with a thin film having a lip clearance of, for example, 300 μm or less, the wetting and spreading of the coating solution at the coating end increases, and the beads at both ends in the bead width direction It is difficult to stabilize. Thereby, the film thickness distribution in the width direction of the coating film is generated.

  Therefore, in the present invention, the spacer 24 is protruded from the tip of the slot 16 and is brought into contact with the surface of the web 22. As a result, both end portions in the bead width direction are stably held by contacting the spacer 24, and the wetting and spreading of the coating liquid at the coating end portion is suppressed. As a result, the bead state at both end portions in the bead width direction is stabilized, so that the bead is cut off from both end portions in the bead width direction and is not easily broken even when the coating speed is increased or the film thickness is reduced. Therefore, stable coating can be performed for high-speed coating and thinning. In this case, wetting and spreading of the coating liquid can be further suppressed by forming a V-shaped or concave groove 24 </ b> C on the front end surface of the spacer 24.

  Furthermore, as another aspect of the present invention, an overhanging portion 24B along the running direction of the web 22 is provided at the tip of the spacer 24 to form an L-shaped or T-shaped spacer 24, whereby the bead width direction. It is possible to further stabilize the bead state at both ends of the.

  In addition, in this Embodiment, although the preferable aspect of the front-end | tip part shape of the spacer 24 was shown, it does not limit to this and all the shapes which do not deviate from the meaning of this invention are included.

  Next, an embodiment of the extrusion coating apparatus of the present invention will be described.

  In the test of the example, the tip of the spacer 24 made of a flexible member was protruded from the tip of the slot and brought into contact with the web surface.

[Spacers used in the examples]
Example 1 ... The rectangular spacer 24 in FIG. 11A, and the width W1 of the spacer 24 is 2 mm. “1” corresponds to the item “shape” in Tables 12 to 14.

  Example 2 ... The rectangular spacer 24 in FIG. 11A, and the width W1 of the spacer 24 is 1 mm. “2” corresponds to the item “shape” in Tables 12 to 14.

  Example 3 As shown in FIG. 11C, the spacer 24 has a concave groove 24C on the tip surface 24B. The width W2 from the application inner side to the groove is 2 mm, the groove width W3 is 3 mm, and from the groove to the outer side of the application. The width W4 is 5mm. “3” corresponds to the item “shape” in Tables 12 to 14.

  Example 4 As shown in FIG. 11B, a spacer 24 having a V-shaped groove on the tip surface 24B has a width W2 from the inside of the coating to the groove of 2 mm, a groove width (upper end width) W3 of 3 mm, and a groove. The width W4 from the coating to the outside is 5 mm. “4” corresponds to the item “shape” in Tables 12 to 14.

  Example 5 As shown in FIG. 11C, the spacer 24 has a concave groove 24C on the tip surface 24B. The width W2 from the inner side of the coating to the groove is 2 mm, the width W3 is 3 mm, and the groove to the outer side of the coating. The width W4 is 95mm. “5” corresponds to the item “shape” in Tables 12 to 14.

  Example 6: As shown in FIG. 11B, a spacer 24 having a V-shaped groove on the tip surface 24B has a width W2 from the inside of the coating to the groove of 2 mm, a groove width (upper end width) W3 of 3 mm, and a groove. The width W4 from the coating to the outside of the coating is 95 mm. “6” corresponds to the item “shape” in Tables 12 to 14.

[Coating solution]
As the coating solution, a coating solution for an antireflection film was used. The refractive index of this coating solution is 1.42, and MEK-ST (average particle size of 10 nm to 20 nm) is added to 93 g of a 6% by weight methyl ethyl ketone solution (JN-7228, manufactured by JSR Corporation) of a thermally crosslinkable fluoropolymer. Then, 8 g of a methyl ethyl ketone dispersion of a solid content concentration of 30% by weight of SiO2 sol (manufactured by Nissan Chemical Co., Ltd.), 94 g of methyl ethyl ketone and 6 g of cyclohexanone were added and stirred, and then filtered through a polypropylene filter (PPE-01) having a pore size of 1 μm. Thus, a coating solution for the low refractive index layer was prepared.

  A coating solution having a viscosity of 0.5 cP and a surface tension of 23 dyn was basically used. In a test for examining the influence of the viscosity and the surface tension, the viscosity and the surface tension were changed as follows. That is, when changing the viscosity of the coating solution, the ratio of methyl ethyl ketone and cyclohexanone was changed, or a monomer-based thickener was added later for adjustment.

  Spacers 24 were inserted into both ends of the slot to set the coating width to three levels of 1300, 1480, and 1500 mm.

  As a comparative example, the spacer was made to be flush with the slot tip as in the prior art.

(Test 1)
In Test 1, the coating conditions of the coating amount, the coating liquid viscosity, the coating speed, the lip clearance (shown as “Lip CL” in Tables 12 to 14), and the decompression value of the decompression box were changed. In this embodiment, the protrusion length d of the spacer 24 from the slot tip is set to 1000 μm, which is larger than the lip clearance C, and the tip of the spacer 24 comes into contact with the web surface so as to bend in the rotation direction of the backup roller 20. (See FIG. 5).

  As a comparative example, a rectangular spacer 24 with a W1 of 2 mm shown in FIG. 11A is made to be flush with the slot tip as in the conventional case. That is, the spacer tip does not protrude from the slot tip.

  Then, the wetting and spreading length of the coating solution with respect to the set prescribed coating width was measured. Moreover, the film thickness distribution of the coating film width direction was evaluated by measuring the reflectance distribution in the width direction of the obtained coating film. The reflectance distribution was calculated using (maximum value−minimum value) / average value of reflectance.

  The results of Test 1 are shown in Table 12.

  As a result, in Comparative Examples 1 to 4, the wetting spread of the coating liquid at the coating end is as large as 6 to 15 mm, and as a result, the film thickness distribution in the coating film width direction is as large as 5.7 to 9.5%. The film thickness distribution of 1% or less, which is a target value for producing an optical film, could not be achieved (x evaluation).

  On the other hand, in Examples 1 to 28, the wetting spread of the coating solution at the coating end is very small as 1 mm to 2 mm. As a result, the film thickness distribution in the coating film width direction is 0.5% to 1.0 mm. %, And the target film thickness distribution of 1% or less was achieved (circle evaluation).

(Test 2)
In Test 2, the “shape 1” spacer 24 used in Example 1 was used, and the test was performed based on the coating conditions of Example 3 except that the protrusion length d of the spacer 24 was changed. The film thickness distribution of the coating film was examined. The result is shown in Table 13.

  As can be seen from FIG. 13, in the case of Comparative Example 5 where the protrusion length d of the spacer is minus 50 μm and is immersed in the slot from the tip of the slot, the wetting spread of the coating liquid is formed over the spacer 24. Therefore, it has been difficult to suppress wetting and spreading. The same was true for Comparative Example 6 in which the tip of the spacer 24 and the tip of the slot 16 were flush.

  As a result, in Comparative Example 5, the wetting spread of the coating liquid was as large as 10 mm, and the film thickness distribution of the coating film was as large as 7%, which was evaluated as x. Further, in Comparative 6, the wet spread of the coating solution was as large as 7 mm, and the film thickness distribution of the coating film was as large as 6%, which was evaluated as x.

  Further, as in Comparative Example 7, when the protruding length d of the spacer is 50 μm and the tip of the spacer 24 is not in contact with the web surface, in other words, the tip 24 of the spacer 24 has a thickness of 50 μm and the lip clearance C When it was smaller than 130 μm, the wetting spread of the coating solution could not be sufficiently reduced to 4 mm. As a result, the film thickness distribution of the coating film was as high as 3% and was evaluated as Δ. As described above, in Comparative Examples 5 to 7 performed under the condition where the tip of the spacer 24 does not contact the web surface, the target film thickness distribution of 1% or less could not be achieved.

  On the other hand, in the case of Examples 29 to 32 in which the protrusion length d of the spacer is larger than the lip clearance C and the spacer is bent in the rotation direction of the backup roller 20 and contacts the web surface, The wetting spread was as small as 1 mm, and the film thickness distribution was 0.50 to 0.55 mm, achieving 1% or less of the target. In Examples 29 to 32, the thickness of the bent portion was 130 μm, which is the same as the lip clearance C.

(Test 3)
Test 3 uses the “shape 1” spacer used in Example 1, mainly when the lip lip clearance C is increased from 130 μm to 320 μm, and the liquid viscosity of the coating liquid is increased from 0.5 cP to 12 cP. The influence on the wetting spread of the coating liquid and the film thickness distribution was investigated.

  The result is shown in Table 14.

  As can be seen from FIG. 14, in Examples 33 to 43, even when the lip lip clearance C is changed from 130 μm to 320 μm and the liquid viscosity is changed from 0.5 cP to 12 cP, the wetting spread of the coating liquid Was as small as 1 mm. As a result, the film thickness distribution of the coating film was 0.5% to 0.7%, and the target was achieved.

  Further, even in Comparative Example 7 in which the tip of the spacer 24 is not in contact with the web surface and the liquid viscosity is as small as 0.5 cP, if the lip clearance C is 320 μm and the thick coating condition is 300 μm or more, the wetting spread The film thickness distribution was a pass evaluation.

  Further, even in Comparative Example 8 in which the spacer 24 is not in contact with the web surface and the lip clearance C is 300 μm, when the liquid viscosity of the coating liquid is 12 cP and 10 cP or more, the wetting spread and the film thickness distribution Was a pass evaluation.

  That is, when the lip clearance C is larger than 300 μm, there is no difference from the present invention in the wetting spread and the film thickness distribution even if the tip of the spacer 24 is not in contact with the web surface. This is thought to be due to the fact that the lip lip clearance C is wide so that capillary action is unlikely to occur. The same result was obtained when the liquid viscosity of the coating solution exceeded 10 cP, and there was no difference from the present invention in the wetting spread and film thickness distribution even when the tip of the spacer 24 was not in contact with the web surface.

  Therefore, the extrusion coating apparatus of the present invention can cope with a wide range from a low liquid viscosity to a high liquid viscosity of the coating liquid and from a thin film coating having a small lip clearance C to a thick coating coating. And it turns out that this invention exhibits a further effect especially in the thin-film application | coating with a lip clearance C of 300 micrometers or less, and the low-viscosity coating liquid with a liquid viscosity of 10 cP or less.

The top view which looked at the extrusion coating apparatus of this invention from the top Side sectional view of the extrusion coating apparatus of the present invention Partially enlarged view showing spacer protruding from slot The perspective view which shows the one aspect | mode of the protrusion state of a spacer The perspective view which shows another aspect of the protrusion state of a spacer The perspective view which shows another aspect of the shape of a spacer The perspective view which shows the aspect which has an overhang | projection part in the shape of a spacer The perspective view which shows another aspect which has an overhang | projection part in the shape of a spacer Explanatory drawing which shows the relationship between the thickness of the spacer which has a bending part, and a lip clearance Explanatory drawing in which a taper is formed on the lower surface of the tip of the spacer Explanatory drawing explaining the various aspects in the front-end | tip part of a spacer Table for explaining Test 1 of Example Table for explaining Test 2 of Example Table for explaining Test 3 of Example

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Extrusion coating device, 12 ... Slot die, 14 ... Pocket part, 16 ... Slot, 18 ... Edge surface of slot die tip, 20 ... Backup roller, 22 ... Web, 24 ... Spacer, 26 ... Decompression box, L ... Coating liquid, L1 ... Bead

Claims (6)

A bead is formed by bridging the discharged coating liquid to the lip clearance between the web that is wound around the backup roller and continuously running and the tip of the slot die that discharges the coating liquid from the slot, and is applied via the bead. In the extrusion coating apparatus in which a liquid is applied to the web and spacers for application width regulation are inserted at both ends in the width direction of the slot.
An extrusion coating apparatus, wherein at least a tip portion of the spacer is formed of a flexible member, and coating is performed in a state where the tip portion protrudes from the slot tip and is in contact with the web surface.   The extrusion coating apparatus according to claim 1, wherein at least one groove that does not contact the web surface is provided at a tip of the spacer.   3. The extrusion coating apparatus according to claim 1, further comprising an overhanging portion along a running direction of the web at a tip portion of the spacer.   The extrusion coating apparatus according to any one of claims 1 to 3, further comprising a decompression box that decompresses the upstream side of the bead in the web traveling direction.   The extrusion coating apparatus according to any one of claims 1 to 4, wherein the coating speed is 5 m / min or more and 100 m / min or less.   6. The extrusion coating apparatus according to claim 1, wherein the coating liquid applied to the web has a liquid viscosity of 10 cP or less and the lip clearance C is 300 μm or less.

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