JPS59123568A - Coating method - Google Patents

Abstract

PURPOSE:To obtain a paint coated film having excellent surface characteristics without streaking trouble by providing a flow regulating plate in a liquid well in the stage of supplying a coating liquid so as to form the liquid well just before the part where a revolving bar and a continuous traveling web contact. CONSTITUTION:A weir member 6 is held in proximity to a web 2 and a meniscus 10 is formed between the member 6 and the web 2 with the coating liquid 3 which is fed through a liquid feed port 5 and is filled in a liquid well 8. A flow regulating plate 11 is provided in the well 8 by which the vortex in the well 8 is eliminated and the meniscus 10 is stabilized. The generation of a streaking trouble is eliminated even if the liquid 3 having a high color density is used and said liquid is picked up with an applicator roll 1 and is coated on the web 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of applying a coating liquid to a continuously running belt-shaped support (hereinafter referred to as "web"),
More particularly, the present invention relates to an improved bar coating method.

Conventionally, various methods have been proposed as methods for applying a coating liquid to a continuously running web. Generally, the coating process involves the part where the coating liquid is transferred to the web (hereinafter referred to as "
"Application system". ) and a part that measures the coating liquid transferred to the web to the desired coating value (hereinafter referred to as "Measuring System J"), so coating methods are classified according to the differences in application system and counting system. Ta.

Based on differences in coating systems, roller coating methods, dip coating methods, fountain coating methods, etc. have been known, and based on differences in metering systems, air knife coating methods, blade coating methods, bar coating methods, etc. have been known. In addition, extrusion coating methods, beet coating methods, and curtain coating methods are known as methods in which the application and needles are applied in the same area.

- Among these coating methods, the bar coating method transfers excess coating liquid to the web and then scrapes off the excess coating liquid with a bar that is stationary or rotating at a slower circumferential speed in the opposite direction to the web. □It was widely used because it was used to form the desired coating, and it had the feature of being able to apply a thin layer at high speed with a simple device and operation. Although any method can be used as an application system in the bar coating method, the roller coating method, especially the kiss coating method, has been most commonly used to take advantage of its simplicity.

However, in the conventional bar coating method, the application system and measurement system were completely independent, so it was necessary to set conditions for each separately during coating, which was not only complicated but also took up a large amount of space. In short, it had the drawback of being uneconomical in terms of space usage.

Special public Akira! 2-3tj No. 2 discloses a coating method in which a physical space is mechanically created using a wire coating body, a heat-resistant filler, and a thin guide plate in a wire doctor coating section, and a horizontal liquid pool is formed therein. According to this method, the above-mentioned drawbacks can be solved, but in both the conventional method and this improved method, defects on the coated surface that occur during application
It was often observed that defects remained even after measurement by par. That is, even in the method disclosed in Japanese Patent Publication No. 2-3Aj No. 2, scratch failures occur because the web contacts the thin guide plate in a dry state, and a vortex of liquid occurs in the wedge-shaped liquid pool above the web. As a result, streak failure occurred on the coated surface.

On the other hand, Japanese Unexamined Patent Application Publication No. 1997-13-λ2jf'13 proposes a method in which a coating liquid is supplied so that a liquid pool is formed just before the contact area between the parr and the web, and the coating liquid is applied by the parr. It is used as an improved coating method that is easy to operate, does not require a large amount of space, and can form a coating film with excellent surface properties. However, when applying a coating liquid with high color density,
Even when the method proposed in Publication No. 3-22sllJ is used, there are cases in which the disturbance in liquid flow that occurs at the coating portion directly manifests as uneven metering, that is, streak failure on the coating surface.

The present invention improves the drawbacks of the prior art, and is capable of forming a coating film with excellent surface properties that does not cause streak failure even when coating a coating liquid with a high color density, and has a coating film with excellent surface properties. The purpose is to provide a coating method that does not require a large amount of space.

The object of the present invention is to provide a method for applying a coating liquid to a web by supplying the coating liquid so that a liquid pool is formed immediately before the contact portion between a rotating par and a continuously running web. This is achieved by a coating method characterized by providing a rectifying plate within the liquid pool.

Hereinafter, the content of the present invention will be explained in more detail in comparison with the prior art based on the attached diagram F1.

FIG. 1 is a schematic diagram of a par coating device disclosed in Japanese Unexamined Patent Publication No. 53-2λj'13.

In Figure 1, / is a wire parr or a groove cutting parr,
It is rotated in the same direction as the webco, which is continuously running. ≠ is a par support member that is provided over the entire length of the par, and has the function of preventing deflection of the par and also as a liquid supply device for supplying the coating liquid 3 to the par.

That is, the coatings e and 3 are supplied from the liquid supply port j provided on the par support member≠ into the liquid supply guide groove 7 formed between the weir member t, and are picked up by the rotating par and applied to the web 2. However, at this time, the coating liquid 3 is measured at the contact area between the WEBCO and Parl, and only the desired amount is applied to the WEBCO, and the rest flows down and forms a pool with the newly supplied coating G3. r is formed. Therefore, in a steady state, the coating liquid 3 is applied to the webcoat via the liquid pool. It's liquid like this 1
When coating liquid 3 was applied to web 2 from 9r, it was surprisingly observed that the surface properties of the coating film were improved compared to the conventional method. Moreover, since the par/ has both the function of transferring and applying the coating liquid onto the web and the function of measuring the desired amount of coating liquid, the entire device can be made compact and space can be used effectively. This makes setting and operating various conditions easier. However, as mentioned above, the turbulence of the liquid flow in the liquid pool and the inside of the liquid pool results in uneven measurement at the wire parl at the coating area, and when applying a coating liquid with high color density, the coating surface In some cases, this became apparent as a streak failure.

In FIG. 2 showing an embodiment of the present invention, the weir member 6 is placed close to the web λ, and the coating liquid 3 sent from the liquid supply port j and filled in the liquid pool g (...) between the weir member t and the webco. A meniscus 10 is formed between them.In the liquid pool g, a rectifying plate/
By providing /, excessive flow in the liquid pool r is eliminated, the meniscus 10 becomes stable, and streak failures do not occur even when a coating liquid with high color density is applied.

It is also possible to provide a large number of them. Further, as shown in FIG. 2, it may be provided in a suspended structure within the liquid pool g, or as shown in FIG. 3, it may be provided in an integrated structure with a weir member or the like.

As the material of the current plate, hard materials such as metal, plastic, and porcelain are generally used. Regarding compatibility with the coating liquid, it can be adopted without particular consideration. The thickness of the rectifier plate can be increased from about 100 μm to an unlimited thickness depending on the size of the liquid pool, but is preferably from 0.5 m to 3 m. It is convenient to handle if the number is about n. The width of the baffle plate needs to be equal to or larger than the web width, and it is desirable for the width of the baffle plate to be equal to the entire width of the coater in order to stabilize the flow of the liquid.

In the liquid pool, it is preferable that the current plate be located approximately at the center of the liquid pool in the direction in which the web travels, and it may be provided approximately vertically, but it may also be provided at an intentional inclination.

In the present invention, the coating liquid used is not particularly limited, and a water or organic solvent liquid of a polymer compound, an aqueous pigment dispersion, a colloidal solution, etc. can be used. Further, the physical properties of the coating liquid are not particularly limited, but a low viscosity is suitable, and a coating liquid with a viscosity of 10 ocp or less, particularly 6 ocp or less is suitable. Although surface tension is not particularly limited,
Particularly favorable results are obtained when jOdyne/α or less. In the present invention, a coating liquid with a high concentration generally refers to the above-mentioned coating liquid colored with a dye.

FIG. 3 shows an embodiment of the present invention in which the webcoat is pressed down from above by a web pressing roll 12 at the position of the weir member O in order to maintain the meniscus 10'c stably. The outer surface/3 of the weir member is also selectively coated with ii properties.

FIG. 3 also shows an example in which a weir plate /≠ is also provided on the downstream side of the application bar / to form a liquid pool /j to prevent the generation of bubble streaks due to the inclusion of air bubbles.

Fig. J shows an embodiment in which a bar/6 is used for the smearing section, and in this case, the rotation direction of the smearing bar can be either forward or backward relative to the direction of movement of the webco.

As shown in FIGS. 2 to 2, the position of the liquid supply port j can be appropriately selected from front, rear, left, right, top and bottom with respect to the rectifying plate // and the liquid reservoir 1r.

The web used in the present invention includes paper, plastic film, metal, resin coated paper, synthetic paper, and the like. The material of the plastic film is, for example,
Polyolefins such as polyethylene, polypropylene, etc., vinyl Mf bodies such as polyvinyl acetate, polydevinized vinyl, polystyrene, etc.

Polyamides such as 2-nylon and 6-nylon, polyethylene terephthalate, polyesters such as polyethylene/-2.6-naphthalate, polycarbonate), cellulose acetates such as cellulose triacetate and cellulose diacetate, and the like are used. Furthermore, polyolefins such as polyethylene are typically used as materials for resin coated paper, but the material is not necessarily limited thereto.

The thickness of the web is also not particularly limited, but O0θ/man~
/, Omm can be handled and is advantageous in terms of versatility.

Bars used in the present invention include wire bars and grooved bars.

When a wire bar is used in the present invention, the appropriate diameter of the bar is 4 yr (m, :z 5772 m, preferably tmm ~ / 67 nl).If the diameter is defined as dog, there will be no vertical streaks on the coating film. It is easy to occur and is not desirable.

Also, for Yang Zeng whose diameter is smaller than this (but this caused some difficulties in manufacturing, the diameter of the wire is 0.07 ~ /, Oy
nm, preferably 0.07 to 0.3 mm.

If it is larger than this, the amount of coating will be too large and the high speed thin I
It is not appropriate to use the nail-like bar coating method for f# coating, and if it is smaller than this, it will be difficult to wind the wire to make a wire bar, and problems will arise in terms of strength.

Metal is used as the material for the wire, but it is corrosion resistant and
Stainless steel is most suitable from the viewpoint of wear resistance, strength, etc. This wire can also be plated on its surface to further improve wear resistance. Hard chrome metal is especially suitable.

In addition, when using a groove cutter in the present invention, the pitch of the grooves is o, l, o, smm, preferably 0°~
θ, J m of 772 is suitable, and a cross-sectional shape approximating a sine curve is particularly suitable. However, the cross-sectional shape is not necessarily limited to this, and other cross-sectional shapes can also be used. In general, there is a certain correspondence between groove cutting pars and wire pars.
It is said that when the area per unit length of the space below the line connecting the tops of the convex portions in each cross section is equal, it is suitable for applying the same amount under the same conditions.

Therefore, based on such a correspondence relationship, it is possible to select an appropriate grooving par from the knowledge regarding the wire par.

As for the material of the par, metal is preferable in terms of corrosion resistance and strength, and stainless steel is particularly suitable.

Metals, especially stainless steel, are suitable for the material of the housing groove cutter in terms of corrosion resistance, strength, and wear resistance.

Since the parr rotates at high speed, the par support member must be made of a material that has low frictional resistance with the parr (wire in the case of a wire parr). Examples of the material of the par support member preferably used in the present invention include fluororesin, polyacetal resin, polyethylene resin, polystyrene resin, etc. Among these, Teflon (trade name of Upont Co., Ltd., USA 1) is a preferred material. Polytetrafluoroethylene, known for its
A polyacetal resin known under the trade name of DuPo Kuri Co., Ltd. (USA) is particularly suitable in terms of M friction coefficient and strength. Furthermore, it is also possible to use these plastic materials to which fillers such as glass fiber, graphite, and molybdenum disulfide are added. Furthermore, after the par support member is made of a metal material, the surface thereof is coated or pasted with the above-mentioned plastic material,
The coefficient of friction between the ball and the ball may be reduced. Or,
It is also possible to use various metal materials impregnated with the aforementioned plastic materials, such as aluminum impregnated with polytetrafluoroethylene, for the par support member.

According to the present invention, it is possible to easily form a coating film with excellent surface properties, and since the application part and the measuring part are integrated, space is saved and the operation is easy, which is a novel effect. is obtained.

Examples will be given below in order to make the effects of the present invention more clear.

Example 1 A coating liquid having the composition and physical properties shown in Table 1 was applied to the surface of an aluminum web having a thickness of 300 μm and a width of soomyn using a wire coater coating device shown in FIGS. 10X Hiroo, change to 7B/min 31. It was applied at a coating amount of cc/m2.

Table 7 Here, the wire bar was made of stainless steel 57nl and rotated at a circumferential speed equal to the coating speed. Polytetrafluoroethylene was used for the support member. In Figure 2, the current plate is joomm.
A stainless steel plate with a width of 2 mm thick and a height of 711 Om was used in a suspended structure.

When the coating surface thus obtained was inspected, it was found that weak streaks occurred when the conventional wire bar coating device shown in Fig. 1 was used, but when the wire bar coating device based on the present invention shown in GI In those cases, the surface quality was good and no streak failures occurred.

Example 2 A coating liquid having the composition and physical properties shown in Table 2 was applied to the surface of a polyethylene terephthalate film having a thickness of 100 μm and a width of 100 mm using a wire bar coating device shown in FIGS. 1 and 3 at a total coating speed of 20 .170. AOX 10
,100m/min/2 cc/m
It was applied in a coating amount of 2.

Here, stainless steel is used as the wire par and wire, and the diameters are Amm and 0.15mm, respectively.
It was rotated at circumferential speeds of 20, 50%, and 100% of the coating speed. Moreover, polytetrafluoroethylene was used as the par support member.

In Figure 3, the rectifier plate has a width of 1200 mm and a width of 3 mm.
A stainless steel flat plate with a thickness and height of zsmm was used as a stationary type at the bottom of the liquid pool. In addition, stainless steel was used as the weir member, and polytetrafluoroethylene was pasted on the surface to make it liquid repellent.

When the coating surface thus obtained was inspected, it was found that weak streaks occurred when using the conventional wire bar coating device shown in FIG. When used, the surface quality was good and no streak defects Vi occurred.

As described above, according to the present invention, the rectifying plate prevents the flow in the liquid pool, so even if a coating liquid with high color density is used, a coating with good surface quality without streaking failure can be achieved. membrane can be obtained.

The present invention is not limited to the embodiments and drawings, and can be applied and implemented in a wide range of ways.

[Brief explanation of the drawing]

λ/ is a schematic diagram of a conventional bar coating device, and FIG. 2 is a schematic diagram of a bar coating device showing an embodiment of the present invention. Third
Both the figures and the figures are mechanical diagrams of a bar coating device showing another embodiment of the present invention. /... Applicator roll 2... Web 3... Application liquid≠... Par support member j... Liquid supply port 6... Weir member g... Liquid pool //... Current plate Patent Applicant Fuji Photo Film Co., Ltd. Figure 1 Procedural Amendments Dear Commissioner of the Patent Office 1, Indication of Case 1981 Patent Application λ Rizit
1 No. 2, Title of the invention Coating method 3, Relationship with the person making the amendment Patent applicant Location 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (520) Fuji Photo Film Co., Ltd. 4, Subject of amendment ``Invention'' in the description Column 5, “Detailed explanation of

Claims (1)

[Claims] In a method of applying a coating liquid to the web by supplying the coating liquid so that a liquid pool is formed just before the contact portion between a rotating bar and a continuously running web, a rectifying plate is provided in the liquid pool. A coating method characterized by providing