JPH02222748A - Web coating device - Google Patents

Abstract

PURPOSE:To form a coated film having uniform thickness and surface state by constituting an evacuated chamber so that the crossing angle of the respective tangential lines in the advancing direction of a web in both a bead gap part and a web introducing port into the evacuated chamber is regulated to a specified angle or below. CONSTITUTION:A coater 1 and a web supporting means 3 are provided to the mutually nearly opposed positions while pinching a continuously traveling web 2. An evacuated chambers 4 is provided to the lower side of the coater 1 and the bead gap part B of the web 2. The evacuated chamber 4 is constituted so that the crossing angle theta of the respective tangential lines in the advancing direction of the web 2 in both the bead gap part B and a web introducing port 4a into the evacuated chamber 4 is regulated to <=145 deg.. As a result, the bead gap part is unaffected by the air flow introduced into the evacuated chamber. Thereby a coated film having uniform thickness and surface state can be formed.

Description

Detailed Description of the Invention [Industrial Application Field] This invention involves continuously running a web (strip-like flexible support) and uniformly applying one or more coating liquids on the surface of the web (strip-shaped flexible support). This relates to a device that coats a thick film.

[Conventional technology]

Conventionally, as a web coating device, a coater and a web support means are disposed at positions substantially facing each other across a continuously running web, and a conveyor roller conveys the web in multiple stages before and after the support means. Web coating devices equipped with groups are known. That is, a coater is provided near the surface of a continuously running web, and coating is performed by transferring the coating liquid gushing out from the coater onto the web surface via a bead gap.

In the case of single-sided coating, the coated layer is gelled using a cooling means such as a cold air zone, and then transported out. In the case of double-sided coating, the already coated surface is supported by a gas blower that can float and support the web. The other side is coated in the same way, gelled, and transported.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, a vacuum chamber is usually used to suck the bead (coating liquid cross-linked from the coater onto the web surface) downward and stabilize it, but the air flow inside the vacuum chamber is This may affect the coating condition and cause uneven coating. This is because not only is the relationship between the behavior of airflow in the reduced-pressure area in the reduced-pressure chamber and coating unevenness unclear, but also there is no means to control or adjust the airflow.

As a result of precise analysis of the airflow state in the vacuum chamber, the inventor found that the above coating unevenness is caused by the air flowing in from the web inlet of the vacuum chamber, which hardly diffuses after entering the chamber, and reaches the bead gap and forms a bead. He discovered that the cause of the problem was destabilization of the molecule, and completed this invention.

In view of the above points, the main object of the present invention is to provide a web coating device in which the airflow flowing into the vacuum chamber does not affect the bead gap portion.

Means for Solving Problem C] In order to achieve the above object, the first aspect of the present invention is to arrange a coater and a web support means at positions substantially facing each other across a continuously running web. and in a web coating apparatus equipped with a vacuum chamber below a bead gap between the coater and the web, an intersection angle between tangents in the traveling direction of the web at the bead gap portion and the web introduction port to the vacuum chamber is 1456 or less. The decompression chamber is configured in such a way that the direction of the airflow flowing in from the web inlet is not directed directly toward the bead gap, and the airflow that reaches the bead gap is significantly attenuated.

A second aspect of the invention is to arrange a coater and a web supporting means at positions substantially facing each other across a continuously running web, and to provide a decompression chamber below the bead gap between the coater and the web. In the web coating apparatus equipped with the above, a resistance plate is provided in the reduced pressure region of the reduced pressure chamber to prevent the airflow from proceeding toward the bead gap,
It is designed so that almost all airflow flowing from the web introduction port and heading towards the bead gap can be blocked. Note that the shape of this resistance plate is not limited as long as it obstructs the airflow to the bead gap portion.

〔Example〕

The present invention will be described below based on embodiments shown in the accompanying drawings.

Figure 1 shows the decompression chamber where the angle at which the tangent to the traveling direction of each web intersects at the bead gap and the web inlet is 1.
FIG. 2 is a sectional view of a part of the coater of the apparatus of the present invention configured to have an angle of 45° or less. FIG. 3 is a cross-sectional view of a part of the coater, FIG. 3 is a cross-sectional view showing another example of a gas ejector, and FIG. 4 is a cross-sectional view showing an example of a gas ejector using a porous body.

In the figure, reference numeral 1 denotes a coater, and the coater 1 is disposed so as to closely face the continuously running web 2 with a small bead gap B therebetween. The coater 1 has a gushing slit 1a
, lb, and the coating liquid gushing out from the slits la and lb can be transferred to the surface 2a of the web 2 via the bead gap B to perform two-layer coating. The web 2 has a length of several hundred meters to several kilometers and is made of a plastic film such as polyethylene terephthalate or cellulose triacetate, or a web for photosensitive materials such as paper. Thus, the web 2 is applied with a constant tension and speed by a drive/transport system (not shown), and is conveyed into the introduction section D1 while continuously running.

3 is a web support means, and the web support means 3 supports the web 2.
This is to wrap around the coater 1,
It is provided at a position facing the coater 1 with the web 2 in between. The web support means 3 may include a support roller 3' that supports the web 2 in contact with it as shown in FIG. 1, or a gas jet that floats and supports the web 2 without contact as shown in FIG. In other words, the support roller 3' shown in the first diagram can convey the web 2 without contacting and supporting the back surface of the web 2 (the surface opposite to the coated surface facing the coater 1). On the other hand, the gas ejector 3'' shown in the second figure has a large number of micro ejection holes F on its outer shell surface, and directs the gas inside the ejector 3'' toward the back surface 2a of the web 2. The web 2 coated by the coater 1 can be floated and conveyed using the static pressure of the gas. 'a and 3#a, respectively, and the holding surface 3/a
The web 2 is curved along the 3''a section and passed through the bead gear 718 section.

4 is a decompression chamber, and this chamber 4 is equipped with a bead gear 718.
The bead gear 718 is provided at the lower side of the web 2 to stabilize the state in which the coating liquid is transferred to the surface 2a of the web 2 by appropriately sucking the bead of the bead gear 718.

The decompression chamber 4 in FIG. 1 has an angle ( intersection angle) θ
is configured such that the angle is 145° or less. The intersection angle θ
The value of will depend on the positional relationship between the coater 1 and the support roller 3', but it should be at least 145° or less, or 1 if possible due to the device configuration.
It is desirable that the angle be about 0.05° or less. This means that the airflow R flowing in from the web introduction port 4a of the decompression chamber 4 will mostly proceed in the tangential direction of the expanding web introduction port 4a, but by setting the intersection angle θ = 145° or less, it will flow into the bead gap B. This is to prevent the inflowing gas from moving in a straight line, resulting in a significant attenuation of the traveling speed, and to ensure that only a small portion of the inflowing gas can reach the bead gap B.

It goes without saying that the web support means 3 may be constituted by a floating support type gas ejector 3'' as described above.

In FIG. 2, reference numeral 5 denotes a resistance plate provided in the decompression chamber 4, and the resistance plate 5 is for preventing the airflow from proceeding toward the bead gap B within the depressurization region G of the decompression chamber 4. The resistance plate 5 connects the inside of the vacuum chamber 4 to the web inlet 4.
It is almost partitioned into two chambers, the a side and the bead gap 1B side, and is configured so that the airflow R flowing in from the inlet 4a collides with each other, so that almost all of the airflow R can be prevented from proceeding to the bead gap B side. .

Similar to FIG. 1, the decompression chamber 4 is configured such that the angle θ at which the bead gap B of the web 2 and the tangent at each of the web introduction ports 4a intersect in the decompression region G is 145@ or less. The mounting position of the resistance plate 5 is chamber 4.
Although it depends on the structure of
It is desirable that the angle be 5° or less. In this case, the inflow gas leaking from the gap between the resistance plate 5 and the web 2 is θ' = 145
If it is less than 0.0°, it will not be possible to proceed straight to the bead gap B, the traveling speed will be significantly attenuated, and moreover, only a small portion of the inflowing gas will be able to reach the bead gap B.

It should be noted that the web support means 3 may be constituted by a contact type support roller 3' instead of the gas ejector 3'', as described above.

6.6- is a conveyance roller, and the conveyance roller 6.6 is provided in one or more stages before the web support means 3, and is configured to stabilize the running of the web 2 by contacting and supporting the web 2. There is.

The web 2 is carried into the introduction section D1 while being supported in contact with the conveying roller 6. The coating liquid gushing out from the gushing slits la and lb coats the surface 2a in two layers. At this time, the vacuum chamber 4 appropriately suctions the bead of the bead gear 718 and directs the coating liquid to the web 2 side. The air R flowing in from the web introduction port 4a of the decompression chamber 4 becomes a high-speed airflow and travels inside the decompression chamber 4, but in the case of Fig. 1, the angle θ is 145' or less. Therefore, most of it is attenuated without directly colliding with the bead gap B.

In the case of FIG. 2, a resistance plate 5 is placed inside the decompression chamber 4.
Since the air R flowing in from the web introduction port 4a collides with the resistance plate 5 and is attenuated, the airflow further leaking from the gap between the resistance plate 5 and the web 2 must also diffuse and curve. , the bead gap B is rarely reached.

Next, the web 2 is conveyed in a cold air zone (not shown in FIGS. 1 and 2) while receiving cold air from small holes, and is cooled to around 10°C, and in the case of single-sided coating, a drying process is performed. It is carried out as a regular product, and in the case of double-sided coating/spreading, it is carried to a second coater (not shown). Then, the web 2 that has been uniformly coated on both sides is led out from the lead-out section D2 and conveyed to a cooling/drying process, and the double-sided coating process is completed.

[Experiment example]

In the apparatus of the present application shown in FIG. 1, when the angle θ was changed and the coating performance was compared, the results shown in Table 1 were obtained.

Table 1 The embodiments described above are not limited to this. For example, the gas ejector has a continuous curved surface as its outer surface in the floating support part in order to maintain high static pressure in the gap with the web, and Any material may be used as long as it can eject gas and satisfies the conditions of the present invention. That is, the portion through which gas passes from the inside of the gas ejector to the outside does not need to be a through hole, and a gas ejector having another configuration may be provided. For example, the shape of the gas ejector may be semi-cylindrical or elliptical, or it may have a shape in which only the outer surface of the floating support part has curvature and the rest is flat, as shown in Figure 3. good. There are no particular restrictions on the material that constitutes the web-closing surface of the gas ejector (any material can be used as long as it can withstand the internal pressure of the hollow part, but brass steel or stainless steel with hard chrome plating on the surface is preferable). When providing a through hole as in this case, a plastic material such as Bakelite or acrylic resin can also be used in view of ease of drilling.

On the other hand, the major role of the part that allows the gas supplied inside the gas ejector to pass to the outside is to allow the gas to pass through and to provide pressure loss. As long as this condition is met, any type of through hole may be used, and in the case of a through hole, the shape may be a round hole, a polygonal hole, a slit, etc., or a porous material such as sintered metal as shown in Part 4. The body P may constitute the outer shell of the gas ejector of the floating support section.

Furthermore, instead of making the gas ejector hollow, it is also possible to construct the entire part from the gas inlet to the outer surface of the floating support part from a porous body as described above. The gas used for floating support of the gas ejector includes N2 gas, air, etc.
Any material can be used as long as it does not pose a safety problem, but air is most commonly used.

〔Effect of the invention〕

As described above, the present invention provides a coater and a web supporting means that are arranged at positions substantially facing each other across a continuously running web, and that the coater and the web are placed under a portion of the bead gear 71 where the web is closest to each other. In a web coating apparatus equipped with a chamber, the vacuum chamber is formed with an angle θ of 145'.
Since the configuration is as follows, the airflow flowing in from the web inlet of the chamber is not directed toward the bead gap, but most of it is attenuated, and does not directly collide with the bead gap.

In addition, a coater and a web support means are disposed at positions substantially facing each other, sandwiching a continuously running web, and a vacuum chamber is provided below the bead gap where the coater and the web are closest to each other. The device has a configuration in which a resistance plate is installed in the decompression chamber to prevent the airflow from proceeding toward the bead gap, thereby blocking the airflow flowing in from the web inlet and reducing the airflow reaching the bead gap to almost zero. can do.

As described above, with any of the inventions, it is possible to prevent the bead from becoming unstable due to airflow collision, and the constancy of the coating conditions can be maintained. As a result, a coating film with uniform thickness and surface condition can be obtained, which is highly effective in improving the quality of the web and stabilizing production.

[Brief explanation of the drawing]

Figure 1 shows the decompression chamber where the angle at which the tangent to the traveling direction of each web intersects at the bead gap and the web inlet is 1.
FIG. 2 is a sectional view of a part of the coater of the apparatus of the present invention configured to have an angle of 45° or less, and FIG. 3 is a sectional view showing another example of a gas ejector, and FIG. 4 is a sectional view showing an example of a gas ejector using a porous body. 1--Coater la, lb...-Gushing slit 2-web 3-web support means 3'--Support roller (contact type web support means) 3''--
Gas blower (levitating web support means) 3'a, 3"a-
... Web holding surface 4 - Decompression chamber 4a - Web inlet 5 - Resistance plate 6 - Conveyance roller D, - Introduction part D2 - Output part G - Decompression region R - Flowing current L - - Coating liquid B...Bead gap F-/micro ejection hole P-/porous body

Claims (2)

[Claims] (1) A web coating apparatus in which a coater and a web supporting means are disposed at positions substantially facing each other across a continuously running web, and a vacuum chamber is provided below the bead gap between the coater and the web, The web coating apparatus is characterized in that the vacuum chamber is configured such that an intersection angle between tangents in the traveling direction of the web at the bead gap portion and the web introduction port to the vacuum chamber is 145° or less. (2) In a web coating device, a coater and a web support means are disposed at positions substantially facing each other across a continuously running web, and a vacuum chamber is provided below the bead gap between the coater and the web, A web coating apparatus characterized in that a resistance plate is provided in the reduced pressure region of the reduced pressure chamber to prevent the airflow from proceeding toward the bead gap.