JP7522012B2 - Film manufacturing system and film manufacturing method - Google Patents

Description

The present invention relates to a film manufacturing system and a film manufacturing method.

Conventionally, a film manufacturing apparatus is known that includes a melt extrusion film-forming apparatus that melt-extrudes an acrylic resin to form a film, a coater that applies an easy-adhesion composition to one side of the obtained acrylic film, a stretching device (sequential biaxial stretching device or simultaneous biaxial stretching device), and a winding device (see, for example, Patent Document 1).

JP 2020-023170 A

In a film manufacturing apparatus such as that described in Patent Document 1, if an uncoated portion where the adhesive composition is not applied occurs, there is a demand to detect the uncoated portion.

The present invention provides a film manufacturing system and a film manufacturing method that can detect uncoated areas.

The present invention [1] includes a film manufacturing system that includes a molding device that molds molten resin into a sheet-shaped substrate, a coating device that applies a coating liquid to the surface of the molded substrate, a stretching device that stretches the substrate to which the coating liquid has been applied, and a temperature measuring device that measures the temperature of the surface of the substrate moving from the coating device to the stretching device across the entire width of the substrate.

With this configuration, the coated portion of the surface of the molded substrate, to which the coating liquid has been applied, is cooled by the coating liquid. On the other hand, if an uncoated portion, to which no coating liquid has been applied, occurs on the surface of the molded substrate, the uncoated portion is not cooled. Therefore, the temperature of the uncoated portion becomes higher than the temperature of the coated portion.

Therefore, by using a temperature measuring device to measure the surface temperature of the substrate going from the coating device to the stretching device across the entire width of the substrate, it is possible to detect uncoated areas where the temperature is higher than that of the coated areas.

The present invention [2] includes the film manufacturing system of [1] above, in which the temperature measuring device is an infrared thermography device.

With this configuration, uncoated areas can be visually detected using an infrared thermography device.

The present invention [3] includes the film manufacturing system of [1] or [2] above, further comprising a storage device that stores a log of the temperatures measured by the temperature measuring device.

With this configuration, uncoated areas can be identified by checking the log.

The present invention [4] includes a method for producing a film, which includes a forming step of forming a molten resin into a sheet-shaped substrate, a coating step of applying a coating liquid to the surface of the formed substrate, a stretching step of stretching the substrate coated with the coating liquid, and a detection step of detecting the uncoated portion having a higher temperature than the coated portion when a coated portion coated with the coating liquid and an uncoated portion not coated with the coating liquid are formed on the surface of the substrate by measuring the temperature of the substrate surface over the entire width direction of the substrate after the coating step and before the stretching step.

This method makes it possible to detect uncoated areas.

The present invention [5] includes the method for producing a film according to the above [4], in which the temperature of the coating liquid is at least 10°C lower than the temperature of the substrate before the coating liquid is applied.

This method makes it possible to reliably detect uncoated areas based on the temperature difference between the substrate before the coating liquid is applied and the coating liquid.

The film manufacturing system and film manufacturing method of the present invention make it possible to detect uncoated areas.

FIG. 1 is a cross-sectional view of a film produced by a film production system. FIG. 2 is a schematic diagram of a film production system. Fig. 3A is a block diagram of an infrared thermography device, and Fig. 3B is an explanatory diagram for explaining a temperature distribution image obtained by the infrared thermography device. FIG. 4 is an explanatory diagram for explaining the modified example.

1. Overview of Film Production System An overview of a film F production system 1 will be described.

As shown in FIG. 1, the film F includes a substrate S and a coating C. The substrate S has a first surface S1 and a second surface S2 in the thickness direction of the substrate S. The coating C is disposed on the first surface S1 of the substrate S. The coating C covers the first surface S1 of the substrate S. The coating C may be an easy-adhesion layer. When the coating C is an easy-adhesion layer, the film F is an easy-adhesion film. The easy-adhesion film is used in the polarizing plate of an image display device such as a mobile device, a car navigation device, a computer monitor, or a television. More specifically, the easy-adhesion film is used as a protective film that protects the polarizer of the polarizing plate. The easy-adhesion film is bonded to the polarizer via an adhesive layer. The easy-adhesion film is bonded to the polarizer via the easy-adhesion layer.

As shown in FIG. 2, the film F manufacturing system 1 includes a molding device 2, a first stretching device 4A, a coating device 3, a second stretching device 4B as an example of a stretching device, a slitting device 5, a knurling device 6, and a winding device 7.

(1) Molding Apparatus The molding apparatus 2 molds (molding step) a molten thermoplastic resin into a sheet-shaped substrate S. In this embodiment, the molding apparatus is an extrusion molding apparatus.

Examples of thermoplastic resins include acrylic resins, polyolefin resins, cyclic polyolefin resins, polyester resins, polycarbonate resins, polystyrene resins, polyamide resins, polyimide resins, and acetate resins (diacetyl cellulose, triacetyl cellulose, etc.).

When manufacturing an easily adhesive film to be used as a protective film for a polarizer, the material of the substrate S is preferably an acrylic resin.

Furthermore, when manufacturing an easily adhesive film to be used as a protective film for a polarizer, the acrylic resin may be an acrylic resin having a glutaric anhydride structure or an acrylic resin having a lactone ring structure. Acrylic resins having a glutaric anhydride structure and acrylic resins having a lactone ring structure have high heat resistance, high transparency, and high mechanical strength, and are therefore suitable for manufacturing polarizing plates with a high degree of polarization and excellent durability. Acrylic resins having a glutaric anhydride structure are described in JP 2006-283013 A, JP 2006-335902 A, and JP 2006-274118 A. Acrylic resins having a lactone ring structure are described in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005-146084.

In addition to the acrylic resin, the substrate S may contain a thermoplastic resin other than the acrylic resin. By containing the other thermoplastic resin, the birefringence of the acrylic resin can be countered, and an easily adhesive film with excellent optical isotropy can be obtained. The mechanical strength of the easily adhesive film can also be improved.

The substrate S may contain additives such as antioxidants, stabilizers, reinforcing materials, UV absorbers, flame retardants, antistatic agents, colorants, fillers, plasticizers, lubricants, and fillers.

(2) First Stretching Device The first stretching device 4A heats the substrate S and then stretches the substrate S in the machine direction MD.

(3) Coating Device The coating device 3 applies a coating liquid to the first surface S1 of the substrate S formed by the molding process (coating process). Examples of the coating device include a bar coater, a gravure coater, and a kiss coater. Note that the first surface S1 of the substrate S may be subjected to a surface treatment such as a corona treatment or a plasma treatment after the molding process and before the coating process.

When producing an easily adhesive film, the coating liquid is an easily adhesive composition for forming an easily adhesive layer.

The easy-adhesion layer contains a binder resin and fine particles.

Examples of binder resins include thermosetting resins such as urethane resins and epoxy resins, and thermoplastic resins such as acrylic resins and polyester resins. When the adhesive film is used as a protective film for a polarizer, the binder resin is preferably a thermosetting resin. Multiple types of binder resins can be used in combination.

Examples of the fine particles include oxides such as silicon oxide (silica), titanium oxide (titania), aluminum oxide (alumina), and zirconium oxide (zirconia); carbonates such as calcium carbonate; silicates such as calcium silicate, aluminum silicate, and magnesium silicate; silicate minerals such as talc and kaolin; and phosphates such as calcium phosphate. When the easy-adhesion film is used as a protective film for a polarizer, the fine particles are preferably oxides, and more preferably silicon oxide. Multiple types of fine particles can be used in combination.

The coating liquid (easy-adhesion composition) contains a resin component, the above-mentioned fine particles, and a dispersion medium.

The resin component forms a coating (easy-adhesion layer) of the binder resin described above by the stretching process described below. When the binder resin is a urethane resin, the resin component may be, for example, a water-based urethane resin. Examples of the water-based urethane resin include a non-reactive water-based urethane resin that is an emulsion of a urethane resin, and a reactive water-based urethane resin that is an emulsion of a urethane resin in which the isocyanate group is protected by a blocking agent. When the binder resin is a urethane resin, the coating liquid may contain a urethane curing catalyst (such as triethylamine) and an isocyanate monomer.

Examples of dispersion media include water, alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone.

(4) Second Stretching Device The second stretching device 4B stretches the substrate coated with the coating liquid (stretching process). More specifically, the second stretching device 4B dries the coating liquid applied to the substrate S. This causes the coating liquid to become the above-mentioned coating C. The second stretching device 4B also heats the substrate S on which the coating C has been formed, and then stretches the substrate S in the width direction TD. The width direction TD is perpendicular to the machine direction MD. In the stretching process, the substrate S on which the coating C has been formed is stretched, and the above-mentioned film F is obtained.

(5) Slitting Device The slitting device 5 cuts the film F to a predetermined width.

(6) Knurling Device The knurling device 6 forms knurls on both widthwise ends of the film F cut to a predetermined width. The knurls are formed by a laser. The knurls may also be formed by a heated embossing roll.

(7) Winding Device The winding device 7 winds up the film F on which the knurls have been formed.

2. Details of the Film Manufacturing System The film manufacturing system 1 further includes an infrared thermography device 8 as an example of a temperature measuring device.

The infrared thermography device 8 measures the temperature of the first surface S1 of the substrate S traveling from the coating device 3 to the second stretching device 4B over the entire substrate S in the width direction TD. In other words, the infrared thermography device 8 measures the temperature of the first surface S1 of the substrate S over the entire substrate S in the width direction TD after the coating process and before the stretching process. In more detail, as shown in FIG. 3A, the infrared thermography device 8 includes an infrared camera 81, a control device 82, and a monitor 83.

The infrared camera 81 captures an image of the first surface S1 of the substrate S traveling from the coating device 3 to the second stretching device 4B. The infrared camera 81 captures an image of the entire substrate S in the width direction TD.

The control device 82 converts the infrared radiation energy incident on the infrared camera 81 into temperature and creates a temperature distribution image. As a result, the infrared thermography device 8 measures the temperature of the first surface S1 of the substrate S over the entire substrate S in the width direction TD. The control device 82 has a memory 84 as an example of a storage device. In other words, the film manufacturing system 1 is equipped with a memory 84. The memory 84 stores a log of the temperatures converted by the control device 82. In other words, the memory 84 stores a log of the temperatures measured by the infrared thermography device 8. As a result, the point where the uncoated portion P2 (see FIG. 3B) occurred can be identified by checking the log stored in the memory 84.

The monitor 83 displays the temperature distribution image created by the control device 82. As shown in FIG. 3B, when a coated portion P1 to which the coating liquid is applied and an uncoated portion P2 to which the coating liquid is not applied are formed on the first surface S1 of the substrate S, the uncoated portion P2 is displayed in the temperature distribution image as having a higher temperature than the coated portion P1.

More specifically, the temperature of the coating fluid is lower than the temperature of the substrate S before the coating fluid is applied. Therefore, the coated portion P1 is cooled by the coating fluid, while the uncoated portion P2 is not cooled. Therefore, the temperature of the uncoated portion P2 is higher than the temperature of the coated portion P1.

In this case, the worker looks at the temperature distribution image and detects the uncoated portion P2 that has a higher temperature than the coated portion P1 (detection process). This allows the uncoated portion P2 to be detected.

The temperature of the coating liquid is, for example, 10°C or more, preferably 30°C or more, lower than the temperature of the substrate S before the coating liquid is applied. When the temperature difference between the coating liquid and the substrate S is equal to or greater than the above-mentioned lower limit, the uncoated portion P2 can be detected more reliably. The upper limit of the temperature difference between the coating liquid and the substrate S is not limited.

3. Modifications (1) The control device 82 may determine the presence or absence of the uncoated portion P2 by using software.

(2) The temperature measuring device is not limited to an infrared thermography device. For example, the temperature of the substrate S in the entire width direction may be measured using multiple infrared temperature sensors.

(3) As shown in FIG. 4, the film manufacturing system 1 may include a smoothing roller 100 downstream of the coating device 3 in the machine direction MD. The smoothing roller 100 spreads the coating liquid applied to the substrate S in the width direction TD. When an uncoated portion P2 having a width below the detection limit of the infrared thermography device 8 occurs, the smoothing roller 100 applies the coating liquid to the uncoated portion P2 by spreading the coating liquid applied to the substrate S in the width direction TD. This makes it possible to eliminate the uncoated portion P2.

REFERENCE SIGNS LIST 1 Film manufacturing system 2 Molding device 3 Coating device 4B Second stretching device 8 Infrared thermography device 84 Memory F Film P1 Coated portion P2 Uncoated portion S Substrate S1 First surface

Claims (5)

A molding device that molds a molten resin into a sheet-shaped substrate;
A coating device that applies a coating liquid to a surface of the molded substrate;
A stretching device that stretches the base material coated with the coating liquid;
a temperature measuring device that measures the temperature of the surface of the substrate from the coating device to the stretching device across the entire width direction of the substrate. The film manufacturing system of claim 1, wherein the temperature measuring device is an infrared thermography device. The film manufacturing system according to claim 1 or 2, further comprising a storage device that stores a log of the temperatures measured by the temperature measuring device. A molding step of molding the molten resin into a sheet-shaped substrate;
A coating step of applying a coating liquid to a surface of the molded substrate;
a stretching step of stretching the substrate to which the coating liquid has been applied;
a detection step of measuring the temperature of the surface of the substrate over the entire width direction of the substrate after the coating step and before the stretching step, thereby detecting the uncoated portion having a higher temperature than the coated portion when a coated portion to which the coating liquid is applied and an uncoated portion to which the coating liquid is not applied are formed on the surface of the substrate. The method for producing a film according to claim 4, wherein the temperature of the coating liquid is at least 10°C lower than the temperature of the substrate before the coating liquid is applied.

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