JP2000288448A - Coating method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the chipping of a film due to a non-coating part by applying a specific quantity of water on the non-coating part of an applicator roll so that the non-coating part does not come in direct contact with the film. SOLUTION: Ion exchanged water or pure water stored in a water storage tank 10 is fed to a sponge pat 7 by a micropump 9 to apply the water of 1-20 g/m2 coating weight on the non-coating part of the applicator roll 1 so that the non-coating part 5 of the applicator roll 1 does not come in direct contact with the film of a polyester based resin such as polyethylene terephthalate, polybutylene terephthalate or the film of a polyamide based resin such as nylon 6, nylon 66, nylon 12. As a result, the chipping of the film 2 due to the non- coating part 5 is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method and an apparatus therefor, and more particularly to a coating method for coating a running plastic film with an applicator roll rotating in a direction opposite to the running direction of the film. The present invention relates to a coating method and an apparatus for reducing or preventing the edge portion of the coating from being cut off.

[0002]

2. Description of the Related Art A plastic film may be subjected to a coating process for the purpose of imparting functionality, for example, easy adhesion, easy slip, gas barrier property, moisture proof property, antistatic property, ink receiving property, and the like. Widely used. As a coater used for this processing, for example, a reverse coater and a kiss roll coater are known. The applicator rolls of these coaters have both a coated portion and an uncoated portion polished with an abrasive such as chromium oxide to finish the surface without defects. Also, the uncoated portion of the applicator roll usually has a slightly smaller diameter than the coated portion.

[0003]

However, in the study of the coating process by the present inventor, the following has become clear.
In the coating process, the edge portion of the film which comes into contact with the coating portion of the applicator roll is deformed by running tension to follow the shape of the non-coating portion, and comes into direct contact with the non-coating portion. Since the non-coating portion does not have the coating solution, it cannot enjoy the lubricating action of the coating solution, and a part of the surface of the contacting film edge portion, particularly the protrusion, comes to be cut off. There is a tendency that a defect occurs on the surface of the portion and the protrusion is scraped. This tendency becomes more remarkable when the applicator roll is a roll that rotates in the direction opposite to the running direction of the film, that is, a reverse roll, or when the film is thicker, the film tension is higher, and the running speed of the film is lower. The shavings of the film lead to an increase in foreign substances entrained in the film product roll, and further, for example, in the case of magnetic recording applications, it causes spots or dropouts of application of the magnetic paint,
In addition, even for general use, the degree of cleanliness in the processing step is hindered, which causes insufficient product quality to be obtained. The present inventor has further studied diligently to reduce or prevent the abrasion of the film due to the uncoated portion, and as a result, the present invention has been achieved.

[0004]

Means for Solving the Problems That is, the present invention provides: When coating a running plastic film with an applicator roll rotating in a direction opposite to the running direction of the film, a coating method for preventing the uncoated portion of the applicator roll and the film from coming into direct contact with each other, 1. A coating method characterized by applying water in an amount of 1 to 20 g / m ² to an uncoated portion of an applicator roll so that the uncoated portion does not come into direct contact with the film; Apparatus for coating a running plastic film with a coating liquid by an applicator roll rotating in a direction opposite to the running direction of the film, wherein the coating means is provided with means for preventing a film from directly contacting an uncoated portion of the applicator roll. A coating device wherein the means for preventing the uncoated portion of the applicator roll from coming into direct contact with the film is a means for applying water in an amount of 1 to 20 g / m ² to the uncoated portion. .

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a relationship between an applicator roll of a coater, a water application unit, and a film in one embodiment of the present invention. FIG. 2 is a partial front view of FIG.

In FIGS. 1 and 2, 1 is an applicator roll (reverse applicator roll), 2 is a running film, 3 is water application means, 4 is a coated portion of roll 1, 5 is a non-coated portion of roll 1, and 6 is a film. The upper coating or bead, 7 is a sponge pad, 8 is a pad holder, 9 is a micropump, 10 is a water storage tank, and 11 is a pickup roll.

[0007] In the present invention, water is applied to the water storage tank 1.
The ion-exchanged water or pure water stored at 0 is supplied to the sponge pad 7 by the micropump 9 and applied to the non-coating portion of the applicator roll, and the water application amount is 1 to 20 g / m ^2. Required, and particularly preferably ² to 12 g / m ² .

In the present invention, as the plastic film, a film of a polyester resin such as polyethylene terephthalate or polybutylene terephthalate, a film of a polyamide resin such as nylon 6, nylon 66 or nylon 12, polyethylene, polypropylene, polymethylpentene And the like, and a film of each resin blend, and the like. Among these films, it is preferable to use a polyester resin film.

The polyester resin is a crystalline linear polyester comprising a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, and the like. . Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are particularly preferred.

The glycol component includes ethylene glycol, propylene glycol, 1,3-propanediol, 1,6 hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, bisphenol A, 1,4-cyclohexanedimethanol, polyethylene glycol. , Polytetramethylene glycol and the like. Of these, ethylene glycol is particularly preferred.

The polyester resin can be produced by a conventional method, and its average molecular weight is preferably 10,000 or more. In polyester, as a lubricant, silica, alumina, kaolin, calcium carbonate,
It is preferable to contain fine particles such as titanium oxide, graphite, carbon black, crosslinked silicone resin, melamine resin, crosslinked polystyrene, and crosslinked acrylic resin.
If desired, an antioxidant, an antistatic agent, a colorant, a pigment, a fluorescent brightener, a plasticizer, a cross-linking agent, a lubricant, an ultraviolet absorber, and the like can be added.

In the present invention, the plastic film can be produced by conventionally known methods and conditions or by methods and conditions accumulated in the art. For example, it can be produced by melt-extruding the polyester, quenching and solidifying it to form an unstretched film, and stretching and heat-setting the unstretched film. The stretching treatment is performed at least in a uniaxial direction, but is preferably performed in a biaxial direction.
Stretching is usually performed at a temperature equal to or higher than the secondary transition point of the polyester.
It is performed at a magnification of 2 times or more, preferably 3 times or more in each direction.

In the present invention, in the process of producing such a plastic film, particularly a polyester resin film, it is preferable to apply the aqueous coating solution, and then perform drying and stretching treatment. More preferably, an aqueous coating solution is applied to a vertically stretched film, and stretched in the horizontal direction after drying or while drying. If necessary, the film is further stretched in the machine direction or the transverse direction, and further heat-treated to obtain a laminated film. The thickness of the plastic film, especially the polyester film is 2 to 30
The thickness is preferably 0 μm, but the effect is particularly large for a medium-thick or thick product having a thickness of 50 to 300 μm or more.

In the present invention, the aqueous coating solution is applied to at least one surface of a plastic film (base film) using a coater such as a reverse coater or a kiss roll coater, which has an applicator roll that rotates in the reverse direction with respect to the film traveling direction. The effect is great, but the effect is also exhibited by a coater such as a gravure coater in which the peripheral direction of the film rotates in the same direction as the film traveling direction, or a coater without a rotating body such as a die coater. The wet coating amount is 1 to 20 g / m ² , particularly 2 to 12 g / m ² .
g / m ² is preferred. After application, the film is preferably stretched in the horizontal direction while drying, but if necessary, further stretched in the vertical direction and / or
Alternatively, the film is stretched in the transverse direction again and heat-treated. The coating layer thickness after drying and stretching is 0.005 to 3 μm, particularly 0.015 to
1 μm is preferred. The film speed at the coating section is 5
The speed is 300 m / min, but the effect is large at a low speed of 5 to 80 m / min.

As a coating agent, as a binder component,
For example, an aqueous coating liquid using a polyester resin, a polyurethane resin, an acrylic resin, an epoxy resin, a vinyl resin, an acrylic-modified polyester, a polyether, a water-soluble resin, or the like can be used. In addition to the binder in the aqueous coating liquid, for example, a filler, a surfactant, an antioxidant, an antistatic agent, a coloring agent, a pigment, a fluorescent brightener, a plasticizer,
A crosslinking agent, a lubricant, an ultraviolet absorber, and the like can be added.

The solid content of the aqueous coating solution is usually 1 to 30 watts.
Although it is t%, it is particularly desirable to be 2 to 20 wt%. The aqueous coating composition may contain a small amount of an organic solvent.

[0017]

Example 1 A coating agent obtained by adding a surfactant to a water-soluble polyester-based binder component was applied to a film having a film thickness of 100 μm formed at a speed of 30 m / min. In-line coating with an applicator roll rotating in the reverse direction. At that time, when measures were taken to prevent the film from being scraped at the uncoated portion of the applicator roll by a water application method, a good state of the scraping was obtained, and a good film product roll free of entrained foreign substances could be obtained. Table 1 shows the results.

Incidentally, the measurement of the entangled foreign matter was carried out under a fluorescent lamp by measuring a diameter of 2 mm when viewed from directly above the product roll surface.
The above protrusions were measured over the entire circumference of the roll, and the value obtained by dividing by the surface area excluding the end face of the product roll was used.

Evaluation of abrasion resistance state A black long fiber cloth was brought into contact with the uncoated portion of the applicator roll for one minute, and the amount of powder was visually determined. 1: no shavings adhered 2: no shavings adhered visually 3: no shavings were seen, but no problem 4: no shavings were observed, problematic level 5: no shavings Levels that are seen in large quantities and are problematic

Evaluation of state of film-coated portion (bead) The length of the portion where the width of the film-coated portion (bead) changed was measured and evaluated according to the following criteria. 1: constant width over the entire area 2: level at which the portion within 5 mm from the coating edge narrows (a level that does not fit into the product) 3: level at which the coating area edge narrows by about 5 to 15 mm (the level does not fit into the product) Level) 4: A level that is about 15 to 30 m thinner from the coat edge (a level at which the product barely enters) 5: A level that is thinner than the coat edge by 30 mm or more (a level that completely enters the product)

[0021]

Comparative Example 1 A coating agent obtained by adding a surfactant to a water-soluble polyester-based binder component was applied at a speed of 30 m / min to a film having a thickness of 100 μm at a peripheral speed of about 1.2 times the film speed. In-line coating was performed with a counter-rotating applicator roll. that time,
The uncoated portion of the applicator roll was polished with Cr oxide powder to form a film. As a result, the amount of foreign matter entangled tended to be larger than in Example 1, and a sufficient product level could not be obtained, especially on the edge side. Table 1 shows the results.

[0022]

Comparative Example 2 A coating agent obtained by adding a surfactant to a water-soluble polyester-based binder component was applied to a film having a thickness of 100 μm formed at a speed of 30 m / min at a peripheral speed of about 1.2 times the film speed. In-line coating was performed with a counter-rotating applicator roll. that time,
When the uncoated portion of the applicator roll was not polished with Cr oxide powder and formed into a film, the entrapped foreign matter tended to be larger than that in Comparative Example 1 particularly at the edge portion, and a sufficient product level could not be obtained. Table 1 shows the results.

[0023]

[Table 1]

[0024]

The film obtained by the coating method and the coating apparatus according to the present invention reduces the amount of film scraping in the non-coated part compared to a film coated by polishing the non-coated part of a conventional applicator roll with abrasive powder. Thus, the amount of foreign substances entangled in the film product was reduced, and this was effective in supplying a cleaner film product roll.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of a water application device for preventing shaving.

FIG. 2 is a partial front view of FIG.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) (72) Inventor: Tamotsu Kuroe 1357 Nanjo, Anpachi-cho, Anpachi-gun, Gifu Prefecture Teijin Limited Gifu Office (72) Invention Person: Hiroshi Tokuda 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture Teijin Limited Sagamihara Research Center

Claims (6)

[Claims] 1. A coating method for coating a running plastic film with a coating liquid using an applicator roll rotating in a direction opposite to the running direction of the film so that the uncoated portion of the applicator roll does not directly contact the film. Water is applied to the uncoated portion of the applicator roll in an amount of 1 to 20 g /
A coating method characterized by applying an amount of m ² so that the uncoated portion does not come into direct contact with the film. 2. The coating method according to claim 1, wherein water is applied in an amount of ² to 12 g / m ² . 3. The coating method according to claim 1, wherein water is applied to an uncoated portion of the applicator roll by a sponge pad. 4. An apparatus for coating a traveling plastic film with a coating liquid by an applicator roll rotating in a direction opposite to a traveling direction of the film.
A coating apparatus provided with a means for preventing the uncoated portion of the applicator roll from coming into direct contact with the film, wherein the means for preventing the non-coated portion of the applicator roll from coming into direct contact with the film is provided with water. Coating means, which is means for applying an amount of ２０20 g / m ² . 5. The coating apparatus according to claim 4, wherein the coating amount is ² to 12 g / m ² . 6. The coating apparatus according to claim 4, wherein water is applied to an uncoated portion of the applicator roll by a sponge pad.