JP2006076033A - Lamination method and laminated film obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamination method of at least two films for preventing lamination failure without inducing the occurrence of a curl in a laminated film wherein a protective film is laminated on a thin functional film increased in demand every year, and the laminated film reduced in lamination failure and curl. <P>SOLUTION: When at least two or more films are laminated as shown by Fig. 1, at least one film 2 is passed through a mechanism 5 for eliminating the slackening of the film in a TD direction without applying tension exceeding 20 N/m to the film. By this method, the lamination failure and curl of the film can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for laminating two or more films, or a laminated film. More specifically, the present invention relates to a laminating method that can be suitably used for a thinned film or the like, or a laminating film obtained by this method.

  With recent spread of portable information devices, thin monitors, etc., miniaturization, weight reduction, and thinning of devices have become important issues. As means for solving this problem, a method of thinning various functional films to be used may be used. Thinning the film is not only a solution to this problem, but is also advantageous from the viewpoint of environmental conservation, such as reducing the amount of raw materials used and further reducing the amount of waste at the time of disposal. For this reason, the demand for thin films is increasing.

  However, such a thin functional film is very difficult to handle. In particular, it is very difficult to bond two or more films comprising one or more of these films.

  For example, when there is a partial slack in the film, if the laminate roll is used as it is, poor lamination such as folding wrinkles and air biting will occur. On the other hand, in order not to cause these laminating defects, when the film is bonded after increasing the tension applied to the film and eliminating the slackness, the film stretched by the tension at the time of bonding shrinks after bonding, Curling occurs on the film. When this curl occurs, workability is lowered when the laminate film is secondarily processed, or the yield is reduced because the laminate film cannot be processed well, which is a serious problem. In particular, as the film thickness decreases, the occurrence of curling becomes more prominent, and it becomes more difficult to achieve both poor lamination and curl.

  As a method of improving curling, when laminating a molten resin on the top surface of a base material made mainly of paper, water treatment is applied to the base material from the surface opposite to the laminated surface of the base material. A method is known for preventing curling of a laminated sheet after the lamination process (see, for example, Patent Document 1). However, this method cannot be used when laminating plastic films.

  In addition, in a plate heater type laminating apparatus, a method is known in which a discharge path is inclined with respect to a guide path leading to the laminating apparatus (see, for example, Patent Document 2). However, this method can prevent curling with “identification cards” and “medical examination tickets” that are laminated with heat, but functional films such as optical films for liquid crystals that require thinning in particular. However, when heat is applied, changes in optical characteristics (such as phase difference and polarization characteristics) occur, so heat cannot be applied. For example, it is considered difficult to prevent curling in such applications.

As described above, although there is a demand for a thin film, there is currently no effective way to achieve both lamination failure and curl prevention. For this reason, the workability at the time of secondary processing is reduced or the yield is inevitably reduced, and improvement has been demanded.
JP-A-8-216223 JP 2004-74581 A

  It is an object of the present invention to provide a method for laminating two or more films that prevents laminating failure without inducing the occurrence of curling, and to provide a laminated film with reduced laminating failure and curl. And

  The inventors of the present invention have completed the present invention as a result of intensive studies for solving the problems in the prior art and achieving the object. That is, in the present invention, when two or more films are laminated, at least one or more films are passed through a mechanism for eliminating the slack in the TD direction of the film, and a tension exceeding 20 N / m is not applied. In addition to the method (Claim 1), the laminating method (Claim 2), in which the mechanism for eliminating the slackness of the film in the TD direction is a structure in which the shape of the surface is deformed following the slackness of the film in the TD direction. A laminating method characterized in that the structure in which the shape of the surface is deformed following the slack in the TD direction of the film is a roll whose shape is deformed in accordance with the slack in the TD direction of the film (claim 3). A roll whose surface shape is deformed following the slackness in the TD direction of the film is formed by a plurality of small rolls that can move the position of the rotation axis independently in the TD direction. Laminating method (claim 4), characterized in that a roll, a configuration with.

  In addition, when laminating two or more films, a laminate obtained by laminating at least one film through a mechanism that eliminates slack in the TD direction of the film and without applying a tension exceeding 20 N / m. Film (Claim 5), in addition, the laminate film (Claim 6), wherein the mechanism for eliminating the slack in the TD direction of the film is a structure in which the shape of the surface is deformed following the slack in the TD direction of the film, Furthermore, the structure in which the shape of the surface deforms following the slackness in the TD direction of the film is a laminate film in which the shape of the surface deforms following the slackness in the TD direction of the film (Claim 7), the TD of the film A roll whose surface shape is deformed following the slack of the direction is formed by a plurality of small rolls that can move the position of the rotation axis side by side in the TD direction. And having a structure of the laminated film (Claim 8) is a roll.

  According to these laminating methods or these laminating films, it is possible to prevent a laminating failure without inducing the occurrence of curling.

  When laminating a thin film such as a functional film that has been demanded in recent years, it is possible to prevent poor lamination without inducing the occurrence of curling.

  For example, a thin functional film may be sold in the form of a roll wound after laminating a protective film on the functional film. Lamination failure can be prevented without inducing the occurrence. At this time, since there are few lamination defects in the laminate film and curling is less likely to occur, an improvement in yield and workability during secondary processing can be expected.

  The structure of the present invention is characterized in that when two or more films are laminated, at least one or more films are passed through a mechanism for eliminating the slackness in the TD direction of the film, and no tension exceeding 20 N / m is applied. Lamination method. Here, the MD direction means the direction in which the film flows in each part, while the TD direction means the direction perpendicular to the MD direction in the film plane.

  Hereinafter, one embodiment in the case of bonding two films (a first film and a second film) will be described as an example (a schematic structure of this example is shown in FIG. 1). However, the present invention is not limited to the shape of the components described in this example, the relative arrangement thereof, and the like.

  The first film and the second film to be laminated may be the same film or different films, and various types of film thickness, surface properties, constituent materials, and the like can be used. For example, when a second film (hereinafter described as a protective film) is laminated on a first film (hereinafter described as a functional film) and then sold in the form of a roll. In consideration of recent market demands, etc., the first film (functional film) 2 has a thickness of about 10 to 150 μm, and preferably 12 to 80 μm as a thin functional film that has been required in recent years. A publicly known plastic film formed by a melt extrusion method, a solvent casting method, or the like of about 15 to 50 μm can be used. That is, for example, polyester, polycarbonate, polyarylate, polysulfone, polyethersulfone, vinyl chloride, acrylonitrile, styrene, polyolefin, substituted norbornene, cellulose, polyimide, polyvinyl alcohol, polyurethane And plastic films such as acrylic and acrylic. Moreover, it is not limited to the single material obtained from the already illustrated material, The film by a mixed material may be sufficient, and a film single layer product or a laminated product may be sufficient. In the case of a laminated product, a plurality of films may be bonded together via an adhesive layer. Furthermore, various types of undercoating, surface treatment, heating, orientation, etc. for the purpose of adding high functionality, such as improved adhesion strength, improved barrier properties, improved solvent resistance, improved surface properties, and development of retardation, Or the composite film which performed the process of adding an additive at the time of film forming may be used.

  Similarly, as the second film (protective film) 7, a film having a thickness of 5 μm to 100 μm is generally used. The materials generally used for the second film are olefin plastics, vinyl plastics such as polyvinyl chloride and polyacrylonitrile, polyester plastics such as polyethylene terephthalate and polybutylene terephthalate, polyurethane plastics, acrylic plastics, and bisphenol A. A plastic such as polycarbonate containing bisphenol component or a plastic that can be used for the first film can also be suitably used. Moreover, it is not limited to the single film obtained from the already illustrated material, The film by a mixed material may be sufficient, and a film single layer product or a laminated product may be sufficient. Furthermore, various types of undercoating and surface treatment, processing such as heating and orientation, etc. for the purpose of adding high functionality, such as improved adhesion strength, improved barrier properties, improved solvent resistance, improved surface properties, and imparted tackiness, Or the composite film which gave the process of adding an additive at the time of film forming may be used. When the second film is used as a protective film for the first film, the second film is removed before or after being processed as a final product, so that the film can be formed at a low cost. It is preferably obtained by an extrusion method. A film stretched uniaxially or biaxially can also be suitably used.

  The first film fed out from the first film feed unit 1 and the second film fed out from the second film feed unit 6 are provided with the first film processing unit 3 and the second film processing unit 8 according to the necessity for high function addition or the like. The mechanism to eliminate slack in the TD direction of the film after processing (surface treatment by coating, vapor deposition, corona discharge, etc., imparting orientation by stretching, surface treatment by printing, embossing, etc.) The laminate part 11 is pasted through 5 and 10. In addition, when nothing is processed about each film, the apparatus of each film processing part 3 and 8 may be abbreviate | omitted. Further, in this example, the tension applied to each film is measured by the tension pickup rolls 4 and 9, and adjusted to be 20 N / m or less. In general, the tension in the MD direction often increases, and it is necessary to control the tension in the MD direction in particular. For example, when there is a mechanism for increasing the tension in the TD direction, the tension in the TD direction is also increased. It is preferable to adjust so that it may become 20 N / m or less. By increasing the tension, it becomes easier to prevent poor lamination, but if it exceeds 20 N / m, curling tends to occur, which is not preferable.

  The mechanism for eliminating the slack in the TD direction of the film used in the present invention preferably has a structure in which the shape of the surface deforms following the slack in the TD direction of the film, and further the slack in the TD direction of the film. A roll whose surface shape is deformed following the above is preferable. The structure and roll of which the shape of the surface is deformed are, for example, a roll having a mechanism for automatically adjusting the slack in the TD direction by air pressure, water pressure or hydraulic pressure, an air float type turn bar (floating conveyance roll), soft such as sponge It can be realized as a roll with a surface. As an example of a roll having a mechanism that automatically adjusts slack in the TD direction by air pressure, water pressure, or hydraulic pressure, there are a roll in which a plurality of small rolls that can independently move the position of the rotating shaft are aligned in the TD direction. Can be mentioned. In this roll, the partial slack, that is, the fluctuation in partial tension, is absorbed as the reciprocating motion of the small roll by the roll's own weight and the air pressure, water pressure, or hydraulic pressure applied to the small roll.

  As a method for laminating the film used in the present invention, any method may be used as long as it is a known laminating method, but generally, a method by pressurization with two rolls is used. At this time, one or both of the rolls may have a heating function, and the material of the roll is not limited.

  The laminate film 12 bonded by the laminate unit 11 may be subjected to post-processing such as an end slit in the laminate film processing unit 13 or may be wound up by the laminate film winding unit 14 or the like.

  Hereinafter, the present invention will be described in accordance with specific examples and comparative examples, but the present invention is not limited to these examples.

(Evaluation of laminating failure (hereinafter may be abbreviated as “lamination failure”))
In the line, the state when the first film and the second film entered the laminate roll and the bonded state after passing through the laminate roll were visually observed. When abnormality such as wrinkles, creases, and air entrainment was observed, it was judged as NG.

(Evaluation of curl amount of film)
One A4 size sample was cut out from both ends and the center of the film width direction so that the flow direction (MD direction) of the laminated film was the long side. The maximum height when this was placed in a concave shape on a horizontal table was measured immediately after cutting and 30 minutes after cutting. Immediately after that, if both were 30 mm or less after 30 minutes, ◯, only if immediately after 30 mm or less, Δ, and if exceeding 30 mm immediately after cutting, it was marked as x. In addition, it was set as x also about the case where a sample rounds in a cylinder shape.

(Evaluation of tension)
LM-PC manufactured by Mitsubishi Electric Corporation, which is detected by a LX-TC015 type slight displacement tension detector (equivalent to tension pickup rolls 4 and 9 in FIG. 1) installed in the line. Values displayed on the mold tension meter were visually read, and values (unit: N / m) divided by the width of the first film or the second film were used as the respective tensions.

Example 1
A polycarbonate film having a thickness of 19 μm was used as the first film, and a polyethylene film having a thickness of 50 μm was used as the second film. Bonding is a multi-tension roll (manufactured by Oji Engineering Co., Ltd., segment length 100 mm, 12 segments, hereinafter referred to as MT roll) as a mechanism for eliminating slack in the TD direction of the film immediately before the laminate roll in the pass line of the second film. The first film was applied with a tension of 76 N / m, and the second film was applied with a tension of 12 N / m. At this time, the occurrence of defective lamination was not observed. Further, when the curl amount of this laminate film was measured, the evaluation result was “◯”. Various evaluation results are summarized in Table 1.

(Example 2)
Two types of films were bonded in the same manner as in Example 1 except that a 35 μm thick ZEONOR film was used as the first film and a tension of 98 N / m was applied. At this time, the occurrence of defective lamination was not observed. Further, when the curl amount of this laminate film was measured, the evaluation result was “◯”. Various evaluation results are summarized in Table 1.

(Comparative Example 1)
Two types of films were bonded in the same manner as in Example 1 except that no MT roll was used. At this time, wrinkles were generated when the second film entered the laminating roll, and the laminating film showed poor laminating, and the evaluation was NG. Further, when the curl amount of this laminate film was measured, the evaluation result was “◯”. Various evaluation results are summarized in Table 1.

(Comparative Example 2)
Two types of films were bonded in the same manner as in Example 2 except that no MT roll was used. At this time, wrinkles were generated when the second film entered the nip roll, and a laminate failure was observed in the laminate film, and the evaluation was NG. Further, when the curl amount of this laminate film was measured, the evaluation result was “◯”. Various evaluation results are summarized in Table 1.

(Comparative Example 3)
Two types of films were bonded in the same manner as in Example 1 except that the tension of the second film was 30 N / m. At this time, the occurrence of defective lamination was not observed. Moreover, when the curl amount was measured for this laminate film, the evaluation results were Δ to ×. Various evaluation results are summarized in Table 1.

(Comparative Example 4)
Two types of films were bonded in the same manner as in Example 2 except that the tension of the second film was 30 N / m. At this time, the occurrence of defective lamination was not observed. Moreover, when the curl amount was measured for this laminate film, the evaluation results were Δ to ×. Various evaluation results are summarized in Table 1.

(Comparative Example 5)
The two films were bonded in the same manner as in Example 1 except that the tension of the second film was 30 N / m and no MT roll was used. At this time, the occurrence of defective lamination was not observed. Moreover, when the curl amount was measured for this laminate film, the evaluation results were Δ to ×. Various evaluation results are summarized in Table 1.

(Comparative Example 6)
The two films were bonded in the same manner as in Example 2 except that the tension of the second film was 30 N / m and no MT roll was used. At this time, the occurrence of defective lamination was not observed. Moreover, when the curl amount was measured for this laminate film, the evaluation results were Δ to ×. Various evaluation results are summarized in Table 1.

(Comparative Example 7)
Two types of films were bonded in the same manner as in Example 1 except that an expander roll (UE flat expander manufactured by Yu Giken Co., Ltd., hereinafter referred to as EXP roll) was used instead of the MT roll. At this time, wrinkles were generated when the second film entered the laminate roll, and the laminate film was found to have poor lamination, and the evaluation was NG. Furthermore, scratches were observed due to the EXP roll following and not rotating. Further, when the curl amount of this laminate film was measured, the evaluation result was “◯”. Various evaluation results are summarized in Table 1.

(Comparative Example 8)
Two types of films were bonded in the same manner as in Example 2 except that an EXP roll was used instead of the MT roll. At this time, wrinkles were generated when the second film entered the laminate roll, and the laminate film was found to have poor lamination, and the evaluation was NG. Furthermore, scratches were observed due to the EXP roll following and not rotating. Further, when the curl amount of this laminate film was measured, the evaluation result was “◯”. Various evaluation results are summarized in Table 1.

(Comparative Example 9)
Two kinds of films were bonded in the same manner as in Comparative Example 3 except that an EXP roll was used instead of the MT roll. At this time, no defective lamination was observed, but scratches were observed due to the EXP roll following and not rotating. Moreover, when the curl amount was measured for this laminate film, the evaluation results were Δ to ×. Various evaluation results are summarized in Table 1.

(Comparative Example 10)
Two types of films were bonded in the same manner as in Comparative Example 4 except that an EXP roll was used instead of the MT roll. At this time, no defective lamination was observed, but scratches were observed due to the EXP roll following and not rotating. Moreover, when the curl amount was measured for this laminate film, the evaluation results were Δ to ×. Various evaluation results are summarized in Table 1.

As shown in Table 1, when two or more films are laminated, at least one film (second film in the above example) is passed through a mechanism (for example, an MT roll) that eliminates slack in the TD direction of the film, Moreover, it was possible to prevent defective lamination without inducing the occurrence of curling only when laminating with the first film without applying a tension exceeding 20 N / m. On the other hand, when these conditions were not satisfied, poor lamination occurred or curl occurred. When the EXP roll was used, scratches due to the EXP roll following and not rotating occurred at the same time.

One embodiment for bonding two types of films

Explanation of symbols

GR guide roll 1 1st film delivery part 2 1st film 3 1st film processing part 4 Tension pickup roll 5 Mechanism 6 which eliminates slack of TD direction of film 6 2nd film delivery part 7 2nd film 8 2nd film processing part 9 Tension pickup roll 10 Mechanism for eliminating slack in TD direction of film 11 Laminating unit 12 Laminating film 13 Laminating film processing unit 14 Laminating film winding unit

Claims (8)

  A laminating method characterized in that, when two or more films are laminated, at least one or more films are passed through a mechanism that eliminates slack in the TD direction of the film, and a tension exceeding 20 N / m is not applied.   The laminating method according to claim 1, wherein the mechanism for eliminating the slack in the TD direction of the film is a structure in which the shape of the surface is deformed following the slack in the TD direction of the film.   The laminate according to claim 2, wherein the structure in which the shape of the surface deforms following the slack in the TD direction of the film is a roll whose shape changes in accordance with the slack in the TD direction of the film. Method.   The roll whose surface shape is deformed following the slackness of the film in the TD direction is a roll in which a plurality of small rolls whose position of the rotation axis is independently movable are arranged in the TD direction. The laminating method according to claim 3.   A laminate film obtained by laminating at least one film through a mechanism for eliminating sag in the TD direction of the film and laminating without applying a tension exceeding 20 N / m when two or more films are laminated.   6. The laminate film according to claim 5, wherein the mechanism for eliminating the slack in the TD direction of the film is a structure in which the shape of the surface is deformed following the slack in the TD direction of the film.   The laminate according to claim 6, wherein the structure in which the shape of the surface is deformed following the slack in the TD direction of the film is a roll whose shape is deformed in accordance with the slack in the TD direction of the film. the film.   The roll whose surface shape is deformed following the slackness of the film in the TD direction is a roll in which a plurality of small rolls whose position of the rotation axis is independently movable are arranged in the TD direction. The laminate film according to claim 7.