JP7097939B2 - Film roll manufacturing method - Google Patents

Description

The present invention relates to a method for producing a film roll.

Conventionally, a method for producing a film such as an easy-adhesive film includes a stretching step of stretching the film and a winding step of winding the stretched film (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2020-023170

In the method as described in Patent Document 1 described above, the wound film shrinks in the direction opposite to the stretched direction. As the film shrinks, the film roll tightens in the radial direction of the film roll. When the film roll is tightened, excessive pressure is applied to a part of the film, which may cause winding marks on the film.

The present invention provides a method for producing a film roll capable of suppressing the generation of winding marks.

The present invention [1] comprises a stretching step of stretching an acrylic resin film at least in a flow direction, a first winding step of winding the stretched film around a first winding core, and the first winding step. Later, the second winding step of winding the film wound around the first winding core around the second winding core is included, and the second winding step has a shrinkage rate of the film in the flow direction. Includes a method of making a film roll, which is started after 0.015% or more and is terminated while it is 0.035% or less.

According to such a method, the second winding step is completed before the shrinkage rate exceeds 0.035%, so that the film is wound around the film before the second winding step, that is, the first winding core. Shrinkage of the film can be suppressed. As a result, the generation of winding marks can be suppressed before the second winding step.

Further, by starting the second winding step after the shrinkage rate becomes 0.015% or more, the film after the second winding step, that is, the film wound around the second winding core shrinks. Can be suppressed. As a result, the occurrence of winding marks can be suppressed after the second winding step.

The present invention [2] includes the method for producing a film roll according to the above [1], wherein the film has a base material made of the acrylic resin and an slippery layer covering the base material.

According to such a method, since the film has an easy-slip layer, it is possible to prevent the films from rubbing against each other and being scratched when the films are wound in the first winding step and the second winding step. can.

According to the method for producing a film roll of the present invention, the generation of winding marks can be suppressed.

FIG. 1 is a cross-sectional view of a film manufactured by a film manufacturing system. FIG. 2 is a schematic configuration diagram of a film manufacturing system. FIG. 3 is an explanatory diagram illustrating rewinding of the film.

1. 1. Film As shown in FIG. 1, in the present embodiment, the film F has a base material S and a film C. The film F may not have the film C and may consist only of the base material S. The film F is used, for example, as a polarizing plate of an image display device such as a mobile device, a car navigation device, a monitor for a personal computer, and a television. Specifically, the film F is used as a protective film that protects the polarizing element of the polarizing plate.

The base material S has a first surface S1 and a second surface S2 in the thickness direction of the base material S. The base material S is made of an acrylic resin. That is, the film F is made of an acrylic resin.

The acrylic resin may be an acrylic resin having a glutaric acid anhydride structure or an acrylic resin having a lactone ring structure. Acrylic resin having a glutaric acid anhydride structure and acrylic resin having a lactone ring structure have high heat resistance, high transparency, and high mechanical strength, so that the polarizing plate has a high degree of polarization and excellent durability. Suitable for manufacturing. Acrylic resins having a glutaric acid anhydride structure are described in JP-A-2006-283013, JP-A-2006-335902, and JP-A-2006-274118. 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. Has been done.

The base material S may contain a thermoplastic resin other than the acrylic resin in addition to the acrylic resin. By containing another thermoplastic resin, it is possible to cancel the birefringence of the acrylic resin and obtain a film having excellent optical isotropic properties. It is also possible to improve the mechanical strength of the film.

Further, the base material S may contain additives such as antioxidants, stabilizers, reinforcing materials, ultraviolet absorbers, flame retardants, antistatic agents, colorants, fillers, plasticizers, lubricants and fillers. ..

The coating film C is arranged on the first surface S1 of the base material S. The coating film C covers the first surface S1 of the base material S. In this embodiment, the coating film C is an easy-to-slip layer. When the film C is an easy-slip layer, the film C suppresses the films F from rubbing against each other and being scratched when the film F is wound in the first winding step and the second winding step described later. Further, when the film C is an easy-to-slip layer, the film C suppresses blocking between the films F. Specifically, the slippery layer contains a binder resin and fine particles.

Examples of the binder resin include thermosetting resins and thermoplastic resins. Examples of the thermosetting resin include urethane resin and epoxy resin. Examples of the thermoplastic resin include acrylic resin and polyester resin. A plurality of types of binder resin can be used in combination.

Examples of the fine particles include oxides, carbonates, silicates, silicate minerals, and phosphates. Examples of the oxide include silicon oxide (silica), titanium oxide (titania), aluminum oxide (alumina) and zirconium oxide (zirconia). Examples of the carbonate include calcium carbonate. Examples of the silicate include calcium silicate, aluminum silicate and magnesium silicate. Silicate minerals include, for example, talc and kaolin. Examples of the phosphate include calcium phosphate. When the film F is used as a protective film for a stator, the fine particles are preferably an oxide, more preferably silicon oxide. A plurality of types of fine particles can be used in combination.

The average primary particle diameter of the fine particles is, for example, smaller than the thickness of the coating film C. Since the average primary particle diameter of the fine particles is smaller than the thickness of the coating film C, it is possible to prevent the fine particles from falling off from the coating film C. The average primary particle diameter of the fine particles is, for example, 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less, more preferably 80 nm or less, more preferably 60 nm or less, and more preferably 50 nm or less.

The average primary particle diameter of the fine particles is, for example, 10 nm or more, preferably 15 nm or more, and more preferably 20 nm or more. When the average primary particle diameter of the fine particles is at least the above-mentioned lower limit value, blocking can be suppressed when the film F is wound.

The fine particles are contained in the coating film C in an amount of, for example, 5% by mass or more, preferably 10% by mass or more, for example, 30% by mass or less, preferably 20% by mass or less.

The easy-slip layer may be an easy-adhesive layer. When the easy-slip layer is an easy-adhesive layer, the film F is an easy-adhesive layer and is adhered to a polarizing element.

The thickness of the slippery layer is, for example, 300 nm or less, preferably 250 nm or less, for example, 100 nm or more, preferably 150 nm or more.

The thickness of the film F is, for example, less than 60 μm, preferably 40 μm or less, and for example, 20 μm or more, preferably 30 μm or more.

The width of the film F is, for example, 3.00 m or less, preferably 1.50 m or less, and for example, 1.00 m or more.

2. 2. Film manufacturing system As shown in FIG. 2, in the present embodiment, the film F manufacturing system 1 includes an extrusion molding device 2, a first stretching device 4A, a coating device 3, a second stretching device 4B, and the like. It includes a slit processing device 5, a knurling processing device 6, and a winding device 7.

(1) Extrusion molding device The extrusion molding device 2 extrudes the base material S (extrusion molding step). The base material S extruded from the extrusion molding apparatus 2 has a sheet shape.

(2) First Stretching Device The first stretching device 4A heats the base material S and then stretches the base material S in the flow direction MD of the base material S (first stretching step).

(3) Coating device The coating device 3 applies a coating liquid to the first surface S1 of the base material S (coating step). The first surface S1 of the base material S may be subjected to surface treatment such as corona treatment and plasma treatment after the extrusion molding step and before the coating step.

Examples of the coating device 3 include a bar coater, a gravure coater, and a kiss coater.

When producing a film F having an easy-slip layer, the coating liquid is a resin composition for forming the easy-slip layer. The coating liquid contains a resin component, the above-mentioned fine particles, and a dispersion medium.

The resin component forms the above-mentioned binder resin film by the stretching step described later. When the binder resin is a urethane resin, examples of the resin component include an aqueous urethane resin. Examples of the water-based urethane resin include a non-reactive water-based urethane resin which is an emulsion of a urethane resin, and for example, a reaction-type water-based urethane resin which is an emulsion of a urethane resin in which an isocyanate group is protected with 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 the dispersion medium include water, for example, alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone.

(4) Second Stretching Device The second stretching device 4B dries the coating liquid applied to the base material S. As a result, the coating liquid becomes the above-mentioned film C. Further, the second stretching device 4B heats the base material S on which the coating film C is formed and then stretches the base material S in the width direction TD of the base material S (second stretching step). The width direction TD is orthogonal to the flow direction MD. By the second stretching step, the base material S on which the film C is formed is stretched, and the above-mentioned film F is obtained.

(5) Slit processing device The slit processing device 5 cuts the film F to the above width (slit step).

(6) Knurling apparatus The knurling apparatus 6 forms knurls at both ends of the film F cut to a predetermined width in the width direction (knurling step). Knar is formed by a laser. Knar may be formed by heated embossed rolls.

(7) Winding device The winding device 7 winds the film F on which the knurls are formed on the first winding core W1 (first winding step). When the first winding step is completed, the first film roll R1 can be obtained.

The diameter of the first winding core W1 is, for example, 10 cm or more, preferably 15.24 cm or more, and for example, 30 cm or less, preferably 27.94 cm or less. When the diameter of the first winding core W1 is at least the above lower limit value, the occurrence of winding marks can be further suppressed.

When the first winding step is completed, the temperature of the film F wound around the first winding core W1 is, for example, 30 ° C. or lower, preferably 25 ° C. or lower, for example, 20 ° C. or higher, preferably 20 ° C. or higher. , 22 ° C or higher.

The film F wound around the first winding core W1 contracts in the direction opposite to the stretching direction of the film F. As a result, the film roll R1 is tightened in the radial direction of the film roll R1. When the film roll R1 is tightened, excessive pressure may be applied to a part of the film F. If a certain period of time elapses in this state, the film F may have winding marks.

The shrinkage rate of the film F wound around the first winding core W1 is, for example, 0.01% or more, preferably 0.015% or more, for example, 0. It is 05% or less, preferably 0.035% or less.

The shrinkage rate of the film F can be measured by the method described in Examples described later.

3. 3. In the film rewinding method, as shown in FIG. 3, after the first winding step, the film F wound around the first winding core W1 is wound around the second winding core W2 (the first winding core W2). 2 winding process). As a result, the film F tightened by shrinkage is released to obtain a second film roll R2. The first film roll R1 is stored between the first winding step and the second winding step. No other process intervenes between the first winding process and the second winding process.

Here, the second winding step starts after the shrinkage rate of the film F in the flow direction MD becomes 0.015% or more, and ends while it is 0.035% or less.

By ending the second winding step before the shrinkage rate exceeds 0.035%, the shrinkage of the film F before the second winding step, that is, the film F wound around the first winding core W1 is suppressed. It can be suppressed. As a result, the generation of winding marks can be suppressed before the second winding step.

Further, by starting the second winding step after the shrinkage rate becomes 0.015% or more, the film F after the second winding step, that is, the film wound on the second winding core W2. The contraction of F can be suppressed. As a result, the occurrence of winding marks can be suppressed after the second winding step.

The period during which the shrinkage rate is 0.015% or more and 0.035% or less is specifically between 3 hours and 24 hours after the completion of the first winding step.

The second winding step is preferably started after the shrinkage rate is 0.018% or more, and is terminated while the shrinkage rate is 0.025% or less. As a result, the film roll R2 can be brought closer to a perfect circle when viewed from the width direction TD. In other words, the film F can be wound more uniformly on the second winding core W2. Therefore, it is possible to further suppress the excessive pressure applied to a part of the film F. As a result, the occurrence of winding marks can be further suppressed.

Further, the second winding step is preferably completed while the shrinkage rate is 0.02% or less. This makes it possible to reduce the waiting time between the first winding process and the second winding process.

When the second winding step is started, the temperature of the film F wound around the first winding core W1 is, for example, 30 ° C. or lower, preferably 25 ° C. or lower, for example, 20 ° C. or higher, preferably 20 ° C. or higher. Is 22 ° C. or higher.

The winding length of the film F in the second winding step is, for example, 8000 m or less, preferably 7000 m or less. When the winding length of the film F is not more than the above upper limit value, the occurrence of winding marks can be further suppressed.

The winding length of the film F in the second winding step is, for example, 5000 m or more, preferably 6000 m or more.

In the present embodiment, the winding length of the film F in the second winding step is the same as the winding length of the film F in the first winding step. The winding length of the film F in the second winding step may be shorter than the winding length of the film F in the first winding step.

The winding speed of the film F in the second winding step is, for example, 125 m / min or less. When the winding speed of the film F in the second winding step is not more than the above upper limit value, it is possible to prevent excessive air from being entrained between the films F. The winding speed of the film F in the second winding step is, for example, 50 m / min or more, preferably 80 m / min or more. When the winding speed of the film F in the second winding step is equal to or higher than the above lower limit value, it is possible to prevent the shrinkage rate of the film F from exceeding the above upper limit value during the second winding step.

4. Modification Example (1) The film F manufacturing system 1 does not have to include the first stretching device 4A. The base material S coated with the coating liquid may be stretched (biaxial simultaneous stretching) in the flow direction MD and the width direction TD by the second stretching device 4B.

(2) The film F manufacturing system 1 may include a masking film feeding device for feeding out the masking film and a bonding device for bonding the fed out masking film to the film F, instead of the narling processing device 6.

Next, the present invention will be described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples. In addition, specific numerical values such as physical property values and parameters used in the following description are the upper limit values such as physical property values and parameters described in the above-mentioned "mode for carrying out the invention". It can be replaced with a number defined as "less than or equal to" or "less than" or a lower limit (a number defined as "greater than or equal to").

1. 1. Examples and Comparative Examples (1) Example 1
Using the film manufacturing apparatus shown in FIG. 2, an easy-to-slip layer (binder resin: urethane resin, fine particles) was formed on the surface of a substrate made of polymethylmethacrylate (acrylic resin having a glutaric acid anhydride structure) containing a glutarimide ring. : A film (width: 1.49 m, thickness: 40 μm) having silica (particle size: 80 nm or less), silica content: 15% by mass, thickness: 200 nm) was produced and wound around a first winding core (width: 1.49 m, thickness: 40 μm). 1st take-up process). As a result, a first film roll (winding length: 8000 m) was obtained.

Next, the first film roll was stored for about 8 hours. Next, the entire film wound around the first core was wound around the second core (second winding step). As a result, a second film roll (winding length: 8000 m) was obtained. The shrinkage rate of the test piece cut out from the first film roll was 0.02% at the end of the second winding step.

The shrinkage rate was measured by a method for measuring the shrinkage rate, which will be described later. The winding speed in the second winding step was 125 m / min.

(2) Examples 2, 3 and Comparative Examples 1, 2
A second film roll was obtained in the same manner as in Example 1 except that the time for storing the first film roll was adjusted and the second winding step was performed. Table 1 shows the shrinkage rate at the end of the second winding step.

(3) Example 4
A second film roll was obtained in the same manner as in Example 1 except that a film having only a base material made of an acrylic resin and no slippery layer was used.

2. 2. How to measure the shrinkage rate To measure the shrinkage rate of the film, first, immediately after the first winding process is completed, a rectangular test piece from the first film roll (length in the flow direction: 20 cm, length in the width direction). : 5 cm) was cut out.

Next, the length (L ₀ ) in the longitudinal direction of the test piece was measured immediately before putting it in the constant temperature bath.

Next, the test piece was suspended in a constant temperature bath so that the longitudinal direction of the test piece was oriented in the vertical direction, a weight of 20 g was hung from the lower end of the test piece, and a load was applied vertically downward. In this state, the test piece was allowed to stand in a constant temperature bath for a predetermined time (in the case of each of the above-mentioned Examples and Comparative Examples, until the end time of the second winding step). The temperature inside the constant temperature bath was maintained at 22 ° C. and the relative humidity was 55%.

Next, the moving distance of the weight was measured using a laser displacement meter. The length (L) in the longitudinal direction of the test piece was calculated from the moving distance, and the shrinkage rate of the film was calculated based on the following formula.

Equation: Shrinkage rate = (L ₀ −L) / L ₀ × 100
3. 3. Evaluation (1) Film appearance For the film rolls of each example and each comparative example, the number of winding marks and the number of scratches were measured using an in-line visual inspection device. The results are shown in Table 1.

(2) Roundness The roundness of the film rolls of each example and each comparative example was measured using a laser displacement meter. The results are shown in Table 1.

F film S base material W1 first winding core W2 second winding core

Claims (2)

A stretching step of stretching the acrylic resin film at least in the flow direction,
The first winding step of winding the stretched film around the first winding core, and
After the first winding step, the second winding step of winding the film wound around the first winding core around the second winding core is included.
The second winding step is a method for producing a film roll, which is started after the shrinkage ratio of the film in the flow direction is 0.015% or more and is finished while it is 0.035% or less. The method for producing a film roll according to claim 1, wherein the film has a base material made of the acrylic resin and an easy-slip layer covering the base material.

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