JP2009213976A - Coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating apparatus capable of preventing coating unevenness caused by the vibration of air generated in the secondary side of a position where a coating liquid is applied from a die on a support to reduce the occurrence of product defects. <P>SOLUTION: In the coating apparatus for forming a coating film by discharging the coating liquid from the slot die 18 toward the surface of the continuously traveling long sized support 12 and applying the coating liquid, in the secondary side of the coating position, vibration attenuating member 54 for attenuating the air vibration is provided to face the coating film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a coating apparatus that forms a coating film, and more particularly, to a coating apparatus that discharges a coating liquid from a slot die to a continuously running belt-like support and creates a coating film on the belt-like support. .

  Conventionally, when forming a coating film by applying a coating solution on a transported support, the wide slit (discharge port) provided at the tip of the die is directed toward the surface of the support that is transported continuously. The coating liquid continuously extruded was applied to the support surface with a uniform thickness (see Patent Document 1).

  However, it has been found that if a supply device such as a pump or a piston is used as a method for supplying the coating solution, pulsation occurs in the coating solution, which causes uneven coating.

  In order to solve such problems, there has been proposed a coating apparatus that eliminates coating unevenness by providing a vibration isolation device (pulsation removing device) (see Patent Document 2).

  In addition, in order to suppress the pulsation in the coating liquid caused by using the supply device, the liquid level of the coating solution in the coating solution tank is controlled without using the supply device in the section from the coating solution tank to the die. However, a coating method for supplying a coating solution to the die has been proposed (see Patent Document 3).

  In addition, as the coating speed increases to improve productivity, the amount and speed of air entrained on the support surface increase, and a phenomenon called so-called air entrainment has come to be seen. Has been proposed (see Patent Document 4).

  In addition to this, in order to stabilize the bead of the coating liquid formed between the die and the support body, an air curtain is provided on both sides of the bead so that coating unevenness does not occur over the entire surface of the support body. Or the coating device is proposed (refer patent document 5).

Thus, conventionally, coating unevenness is prevented by suppressing vibration due to liquid feeding, vibration due to reduced pressure, and vibration due to air entrainment.
JP 2002-86041 A JP-A-5-31434 JP 2004-351291 A JP-A-6-238219 JP 2000-167465 A

  However, even if vibration is suppressed as in the prior art, there is a problem that uneven coating tends to occur as the coating film becomes thinner.

  The present invention has been made in view of such circumstances, and prevents the occurrence of coating unevenness due to vibration of air generated on the secondary side of the position where the coating liquid is applied from the die onto the support. An application apparatus capable of reducing the occurrence of defects is provided.

  In order to achieve the above object, the first aspect of the present invention is to apply the coating liquid onto the long support by discharging the coating liquid from the slot die toward the surface of the continuous long support. In the coating apparatus for forming a coating film, a coating apparatus is provided, wherein a vibration damping member for damping air vibration is provided on the secondary side of the coating position so as to face the coating film. To do.

  The present inventor pays attention to air vibration on the secondary side (downstream side) of the application position as a cause of occurrence of coating unevenness, and provides a vibration damping member that attenuates air vibration on the secondary side of the position where the coating liquid is applied. As a result, it was found that air vibration generated on the secondary side of the position where the coating liquid was applied was absorbed by the vibration damping member, and the occurrence of coating unevenness could be suppressed.

  According to the first aspect of the present invention, when the coating film is formed on the elongated support, the coating film is generated by the air vibration generated on the secondary side of the position where the coating liquid is applied. Application unevenness can be suppressed.

  According to a second aspect of the present invention, in the first aspect, the vibration damping member is disposed on the surface of the slot die and on the surface facing the coating film.

  According to the second aspect of the present invention, the vibration of the air generated on the secondary side of the coating position can be attenuated by the vibration damping member, so that the occurrence of coating unevenness due to the swing of the coating film is suppressed. be able to.

  According to a third aspect of the present invention, in any one of the first or second aspects, the vibration damping member is provided in a facility immediately after coating disposed on the secondary side of the coating position.

  According to the third aspect of the present invention, since the vibration of air generated in a wide area on the secondary side of the coating position can be attenuated by the vibration damping member, coating unevenness caused by the vibration of the coating film is also suppressed. can do.

  Invention of Claim 4 in any one of Claims 1-3 WHEREIN: The said immediately after application | coating is a drying apparatus which has a casing, The said vibration damping member is the inner surface of the said casing, and opposes the said application surface. It is arrange | positioned at the inner surface which carries out.

  According to the fourth aspect of the present invention, the vibration of the air generated particularly above the coating film in the region on the secondary side of the coating position can be attenuated by the vibration damping member. Uneven coating caused by vibration of the coating film already formed on the support can also be suppressed.

  A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the vibration damping member has a sound absorption coefficient of 10% or more with respect to air vibration of less than 1000 Hz.

  According to the fifth aspect of the present invention, since the vibration damping member capable of efficiently absorbing and attenuating the vibration of the air that causes the coating unevenness in the coating film is disposed, the coating unevenness caused by the air vibration can be reduced. Occurrence can be suppressed.

  A sixth aspect of the present invention provides the thickness of the coating film formed on the long support, wherein the clearance between the slot die and the long support is D in any one of the first to fifth aspects. When t is t, t / D is less than 0.3.

  According to the invention described in claim 6, even when the coating liquid is discharged from a position very close to the long support to form a very thin coating film on the long support, A coating film free from coating unevenness can be formed by suppressing coating unevenness due to vibration.

  According to the coating apparatus of the present invention, when a coating film is formed on a continuous long running support, a coating film free from coating unevenness can be formed on the long support.

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

  FIG. 1 is a conceptual diagram showing an example of a coating film forming line 10 incorporating a coating apparatus according to the present invention.

  The coating film forming line 10 is applied on the web 12, a feeding device 14 that feeds the web 12 wound in a roll shape, a coating device that includes a backup roll 16 and a slot die 18 for coating the web 12 with a coating solution. A drying device (equipment immediately after coating) 22 for drying the formed coating film (hereinafter also referred to as a coating layer) 22 and a web 12 (also used in the following description including those in which the coating film 20 is formed) run. And a take-up device 32 that winds up the product 30 produced by coating and drying.

  Guide rollers 34 and 36 are provided in the drying device 22, and the coated web 12 is dried by running on the transport path formed by the guide rollers 34 and 36. In addition, it is preferable to use an infrared heater for the heating devices 40, 42, and 44 provided in the drying device 22.

  In addition, by arranging the plurality of guide rolls 34 and 36 in the drying device 22, the length of the casing 22a can be freely determined without being restricted in transportation. When the guide rolls 34, 36 are heated by the heating devices 40, 42, 44 and the temperature becomes high, it is desirable to control the temperature using the guide rolls 34, 36 as jacket rolls.

  In order to further dry the coated web 12 which has been dried by the drying device 22, it is preferable to provide a hot air drying device 38 on the secondary side (downstream side). While being supported by the roll 24, the coated web 12 is sent to the hot air drying device 38 and further dried. After that, the product 30 is wound up by the winding device 32 while being supported by the rolls 26 and 28. The rolls 24, 26, and 28 may be free rolls or drive rolls.

  As the hot air drying device 38, various drying devices used as conventional techniques can be used. For example, a roller transport dryer system that supports the non-application surface side with a roll and blows air from the air nozzle on the application surface side, and air nozzles arranged on both the application surface side and the non-application surface side It is a type of non-contact type air floating coating dryer method and a non-contact type drying method in which the web 12 is floated by blowing the wind, that is, the web 12 is dried without contacting with a roll or the like. It is possible to use a drying device such as a string-winding type that is used well and efficiently dried. Any type of drying apparatus is common in that dried air is supplied to the surface of the coating film to dry the coating film.

  As the material of the web 12, resin films such as PE (polyethylene), PET (polyethylene terephthalate), and TAC (cellulose triacetate), paper, metal foil, and the like can be used. Examples of the coating liquid include those containing discotic liquid crystals used in the production of optical compensation sheets and those containing silver halide grains used in photosensitive materials for heat development. It is not limited. In the present invention, it is preferable to use a coating solution having a composition ratio of the organic solvent of 50% by mass or more.

  FIG. 2 is a schematic view showing an embodiment of a coating apparatus according to the present invention.

  As shown in FIG. 2, the coating apparatus according to the present embodiment mainly includes a slot die 18 and a drying device 22.

  Inside the slot die 18, a manifold 46 and a slit 48 connected thereto are provided. The coating liquid is diffused in the width direction by the manifold 46, and then discharged from the tip end portion of the slot die 18 toward the web 12 traveling through the slit 48.

  The coating liquid discharged from the tip of the slot die 18 forms a coating film 20 on the web 12 while forming a bead 50 with the web 12. Then, the slot die 18 discharges the coating liquid while moving along the web 12 while discharging the coating liquid, thereby forming the coating film 20 on the web 12.

  Of the tapered lip surface of the slot die 18, the surface on the secondary side (downstream side as viewed from the web running) of the coating position where the coating liquid is discharged from the slit 48 and facing the coating film 20 Is provided with a vibration damping member 52. The vibration damping member 52 attenuates air vibration generated on the secondary side of the position where the coating liquid is discharged, thereby preventing the air vibration from being reflected on the surface of the slot die 18 and transmitted to the coating film 20.

  Here, the wet film thickness t of the coating film 20 formed on the web 12 is preferably 10 μm or less. The reason is that if it exceeds 10 μm, it is not necessary to consider the occurrence of coating unevenness on the coating film due to air vibration. That is, the present invention is particularly effective in suppressing coating unevenness that occurs when the wet film thickness t is a thin film of 10 μm or less. In the present invention, the wet film thickness means the total coating thickness applied to the web 12 during coating.

  Further, the value t / D obtained by dividing the wet film thickness t by the clearance D which is the distance between the web 12 and the tip of the slot die 18 is preferably less than 0.3. The reason is that when it is 0.3 or more, it is not necessary to consider the occurrence of coating unevenness on the coating film due to air vibration. That is, the present invention is particularly effective in suppressing coating unevenness that occurs when t / D is less than 0.3. The t / D value is more preferably 0.05 or more and 0.2 or less.

FIG. 3 is a modification of the present embodiment, which is an example in which a vibration damping member is provided in the facility immediately after coating disposed on the secondary side of the coating position, and is a case of a drying apparatus as the facility immediately after coating.
FIG. 3 is a schematic cross-sectional view of the drying device 22.

  The drying device 22 has a casing 22a, and is configured so that the web 12 coated with the coating film 20 is dried while traveling.

  A vibration damping member 54 is provided on the inner surface of the casing 22a of the drying device 22 and on the inner surface facing the surface of the coating film 20. The vibration attenuating member 54 attenuates air vibration generated in a wide area on the secondary side of the application position that is not limited to the vicinity of the slot die 18, and this air vibration is reflected by the inner surface of the casing 22 a and transmitted to the coating film 20. To prevent that.

  In addition, it is preferable that the sound absorption rate of the vibration damping members 52 and 54 is 10% or more with respect to the air vibration of less than 1000 Hz. The reason is that if it is less than 10%, it is difficult to sufficiently obtain the effect of damping air vibration. The sound absorption rate is more preferably 50% or more and 100% or less. Here, the sound absorption rate refers to the sound absorption rate of the reverberation chamber method measured by the reverberation chamber method.

  The material of the vibration damping members 52 and 54 is preferably urethane rubber, ethylene / propylene rubber, ceramics, aluminum or the like, but more preferably aluminum.

  As shown in FIG. 1, the drying device 22 is covered with a casing 22 a, and other than the entrance / exit of the drying device 22 is hermetically sealed so that the atmosphere in the drying device 22 does not absorb or exhaust air. Thereby, when drying the coating film 20, it becomes possible to prevent the turbulence of the wind near the coating surface. The drying device 22 is preferably disposed as close as possible to the coating position in order to prevent uneven drying of the coating film 20 due to the occurrence of natural convection immediately after the coating liquid is applied. Specifically, it is more preferable that the distance L1 between the inlet of the drying device 22 and the application position is 2 m or less, and most preferable that the distance L1 is 0.7 m or less.

  The traveling speed of the web 12 is preferably a speed that reaches the drying device 22 within 3 seconds after application by the slot die 18. Specifically, the traveling speed of the web 12 is preferably set to 40 m / min to 200 m / min.

  Since unevenness of the coating film is particularly likely to occur at the initial stage of drying, the drying device 22 dries or condenses (in the case of condensation drying) 70% by mass or more of the organic solvent in the coating liquid, and collects the remaining coating. It is preferable to dry the organic solvent in the liquid with a hot air dryer 38. What mass% of the organic solvent in the coating solution is to be dried may be determined by comprehensively determining the influence on the drying unevenness of the coating film 20, production efficiency, and the like.

  In addition, the form of the drying apparatus 22 which is a drying apparatus is not limited to what was illustrated. In addition, conventional members are used for a delivery device, a roll, a winding device, etc. used in a coating / drying line incorporating a drying device to which the coating film drying method and apparatus of the present invention is applied, Those explanations are omitted.

  In addition, a dust removal facility (not shown) may be installed on the upstream side of the coating apparatus, or pretreatment or the like may be performed on the surface of the web 12. For optical films and the like that require high quality with almost no dust, a high-quality coated and dried film can be obtained by simultaneously adopting these.

  The present invention relates to an optical functional film sheet such as an optical compensation sheet, a solvent undercoat of a film for a photosensitive material, a photothermographic material, a functional film containing finely structured particles such as nanoparticles, a photographic film, and a photographic print. It is preferably used for the production of paper, magnetic recording tape, adhesive tape, pressure-sensitive recording paper, offset plate material, battery and the like.

  According to the coating apparatus according to the present embodiment described above, when the coating liquid 20 is formed on the web 12 by discharging the coating liquid from the slot die 18 onto the continuously running web 12, the coating film 20 on the web 12 is formed. Since the vibration damping members 52 and 54 are disposed at various positions facing each other, external vibration is directly transmitted to the coating film 20, or the vibration is reflected on the inner surface of the slot die 18 and the casing 22a. Can be prevented.

  The present invention is not limited to the above-described embodiment, and various changes can be made.

  For example, in the above embodiment, the drying device 22 is described as an example of the equipment immediately after coating, but the present invention is not limited to this, and the web 12 is transported to the inside surrounded by a casing having an inlet and an outlet. Anything can be used as long as it can be applied.

  Below, the Example of the coating device of this invention is described. In this embodiment, in the optical compensation sheet production line, a drying device surrounded by a casing for preventing the flow of air near the coating surface is disposed immediately after the slot die for coating the liquid crystal coating liquid. The effect of preventing coating unevenness when a vibration damping member was provided in at least one of the drying apparatus and the drying apparatus was examined.

Example 1
The optical compensation sheet production line is performed, for example, by the following steps.
1) Transparent film (web) delivery process;
2) A step of forming an alignment film forming resin layer in which a coating liquid containing an alignment film forming resin is applied to the surface of the transparent film and dried;
3) A rubbing step in which an alignment film is formed on the transparent film by subjecting the surface of the resin layer to a rubbing treatment on the transparent film having the alignment film forming resin layer formed on the surface;
4) A liquid crystal discotic compound coating step in which a coating liquid containing a liquid crystal discotic compound is coated on the alignment film;
5) A drying step of drying the coating film and evaporating the solvent in the coating film;
6) A liquid crystal layer forming step of forming the discotic nematic phase liquid crystal layer by heating the coating film to a discotic nematic phase forming temperature;
7) The liquid crystal layer is solidified (that is, solidified by rapid cooling after the liquid crystal layer is formed, or when a liquid crystalline discotic compound having a crosslinkable functional group is used, the liquid crystal layer is irradiated with light (or heated). Cross-linking step);
8) A winding process for winding the transparent film on which the alignment film and the liquid crystal layer are formed.

  The manufacturing method of the optical compensation sheet was continuously performed continuously from the step of sending out the long transparent film to the step of winding up the obtained optical compensation sheet. On one side of a long transparent film of triacetyl cellulose (Fujitack, manufactured by Fuji Photo Film Co., Ltd., thickness: 100 μm, width: 500 mm), a long-chain alkyl-modified poval (MP-203, Kuraray Co., Ltd.) In addition, POVAL is a registered trademark 5% by weight solution and dried at 90 ° C. for 4 minutes to form an alignment film forming resin layer having a thickness of 2.0 μm. The conveyance speed of the film was 50 m / min.

When the triacetyl cellulose film has a refractive index in two orthogonal directions in the film plane of nx, ny, a refractive index in the thickness direction nz, and a thickness of the film d,
(Nx−ny) × d = 16 nm,
{(Nx-ny) / 2-nz} × d = 75 nm. Further, when forming the alignment layer forming resin layer, a coating / drying line equipped with a drying device (equipment immediately after coating) (with heating device (◯), inlet temperature 25 ° C., outlet temperature 21 ° C.) 22 is used. It was done.

  Subsequently, the obtained film having the alignment layer forming resin layer was rubbed on the surface of the resin layer while continuously conveying it at 50 m / min to form an alignment layer. In the rubbing treatment, the rubbing roller was rotated at 300 rpm, and then the resulting alignment film was dedusted.

Next, while continuously transporting the obtained film having the alignment film at a speed of 50 m / min, the coating speed is 50 m / min and the coating amount is 6.5 cc / m ² on the alignment film. A liquid crystal layer coating solution was formed by applying a liquid crystal layer coating solution from a slot die, and then passed through a drying device and a hot air drying device. The hot air dryer was adjusted to 130 ° C. After 3 seconds from the coating, it entered a drying device, and after 3 seconds, it entered a hot air drying device. The hot air dryer passed in about 3 minutes.

  The coating solution for the liquid crystal layer used was prepared by adding a photopolymerization initiator (trade name: Irgacure 907, Ciba Geigy Japan) to a mixture of the discotic compounds TE- (1) and TE- (2) shown below having a weight ratio of 4: 1. A 1% by mass mixture was added to 40% by weight methyl ethyl ketone and prepared.

  The wet film thickness t of the liquid crystal layer was 6.5 μm, and the distance D between the web 12 and the tip of the slot die 18 was 65 μm. The t / D value was 0.1.

  Furthermore, vibration damping members made of aluminum and having a sound absorption coefficient of 50% were arranged at positions A (drying device) and B (secondary side of slot die application position) shown in FIG. The peak value of the frequency of air generated near the coating film was 400 Hz.

  Subsequently, the alignment film and the liquid crystal layer were applied, and the surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp while the film was continuously conveyed at 50 m / min. That is, the film that passed through the heating zone was irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) to crosslink the liquid crystal layer.

(Example 2)
The experiment was performed under the same conditions as in Example 1 except that the vibration damping member was installed only at A shown in FIG.

(Example 3)
An experiment was performed under the same conditions as in Example 1 except that the vibration damping member was installed only at B shown in FIG.

Example 4
The vibration damping member is installed in the position A shown in FIG. 4 only, the distance D between the alignment film and the slot die is 30 μm, and the t / D value is 0.2. Experiments were performed according to conditions.

(Example 5)
The experiment was performed under the same conditions as in Example 1, except that the vibration damping member was installed only at A shown in FIG. 4 and the material of the vibration damping member was urethane rubber having a sound absorption rate of 5%. .

(Example 6)
The experiment was performed under the same conditions as in Example 1 except that the vibration damping member was installed only at A shown in FIG. 4 and the material of the vibration damping member was ethylene / propylene rubber having a sound absorption rate of 10%. went.

(Comparative Example 1)
The experiment was performed under the same conditions as in Example 1 except that the installation position of the vibration damping member was only C (the slot die coating position primary side) shown in FIG.

(Comparative Example 2)
An experiment was performed under the same conditions as in Example 1 except that the vibration damping member was installed only at D shown in FIG.

(Comparative Example 3)
The experiment was performed under the same conditions as in Example 1 except that the vibration damping member was installed only at E shown in FIG.

(Comparative Example 4)
An experiment was performed under the same conditions as in Example 1 except that the vibration damping member was installed only at F shown in FIG.

(Comparative Example 5)
The experiment was performed under the same conditions as in Example 1 except that the vibration damping member was not arranged.

<Summary>
The above results are summarized in Table 1. Here, in Table 1, as for coating unevenness characteristics, ◎ indicates that an optical film having no particularly uneven coating and having particularly good quality was obtained, and ○ indicates that an optical film having no coating unevenness and having good quality was obtained. The symbol Δ indicates that an optical film having a good quality was obtained although there was some coating unevenness, and the symbol X indicates that an optical film having a poor quality with many coating unevenness was obtained.

  In Example 1 in which the vibration damping member is installed at the positions A and B shown in FIG. 4, it can be seen that an optical film of ◎ with no coating unevenness and the highest quality is obtained.

  Further, in Example 2 or 3 in which the vibration damping member is installed at either one of the positions A or B shown in FIG. 4, an optical film having an excellent quality evaluation of ○ is inferior to the case of Example 1. It turns out that it is obtained.

  In Example 4, when the vibration damping member is installed at the position A shown in FIG. 4, even when the clearance D is narrower than in the other examples, the quality evaluation without coating unevenness is an excellent orientation. It can be seen that an optical film having a film is obtained.

  In Example 5, when a vibration damping member was installed at position A shown in FIG. 4 and a vibration damping member made of urethane rubber having a sound absorption rate of 5% was used, an optical film having some coating unevenness was obtained. However, it was an improvement of Δ and was a pass line.

  In Example 6, the vibration damping member was installed at the position A shown in FIG. 4 and a vibration damping member made of ethylene / propylene rubber having a sound absorption rate of 10% was used. It can be seen that an excellent optical film can be obtained.

  In Comparative Examples 1-4, when the vibration damping member made of aluminum having a sound absorption coefficient of 50% is installed at each of the positions C to F shown in FIG. It can be seen that only optical films with inferior quality with coating unevenness can be obtained.

  In Comparative Example 5, when no vibration damping member is provided, it is a quality evaluation of x, and it can be seen that only an optical film inferior in quality with coating unevenness can be obtained.

  As described above, when an aluminum vibration damping member having a sound absorption coefficient of 50% is installed at positions A and B shown in FIG. 4, the optical film with the highest quality is obtained, while the vibration member is shown in FIG. It was found that only defective films with uneven coating could be obtained when installed at positions C to F or when no vibration damping member was provided. And in the coating device which concerns on this invention, in order to obtain the optical film excellent in the quality without a coating nonuniformity, it has confirmed that the vibration damping member was playing the important role.

The conceptual diagram which shows an example of the coating film formation line incorporating the coating device which concerns on this invention Schematic which shows embodiment of the coating device which concerns on this Embodiment Schematic cross-sectional view of the drying device in the present embodiment Schematic explaining the installation position of the vibration damping member

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Coating film formation line, 12 ... Web, 18 ... Slot die, 20 ... Coating film, 22 ... Drying device (equipment immediately after coating), 50 ... Bead, 52, 54 ... Vibration damping member

Claims (6)

In a coating apparatus that discharges a coating liquid from a slot die toward the surface of a long support that continuously runs, and forms a coating film by applying the coating liquid on the long support.
A coating apparatus, wherein a vibration damping member for damping air vibration is provided on the secondary side of the coating position so as to face the coating film.   The coating apparatus according to claim 1, wherein the vibration damping member is disposed on a surface of the slot die and on a surface facing the coating film.   3. The coating apparatus according to claim 1, wherein the vibration damping member is provided in a facility immediately after coating disposed on the secondary side of the coating position.   The said equipment just after application | coating is a drying apparatus which has a casing, The said vibration damping member is arrange | positioned at the inner surface of the said casing, and the inner surface facing the said coating surface. The coating apparatus of any one of Claims.   5. The coating apparatus according to claim 1, wherein the vibration attenuating member has a sound absorption rate of 10% or more with respect to air vibration of less than 1000 Hz.   When the clearance between the slot die and the long support is D, and the thickness of the coating film formed on the long support is t, t / D is less than 0.3. It exists, The coating device of any one of Claims 1-5 characterized by the above-mentioned.

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