WO2015119049A1 - Method for conveying film and method for producing optical film - Google Patents

Abstract

Provided is a method for continuously conveying a joined film, which includes a first film (10) and a second film (20) joined to a longitudinal terminal end thereof, by means of one or more drive rolls (40) along a conveying path including the one or more drive rolls, wherein the first film and/or the second film is an optical film having a Charpy impact strength of less than 200 kJ/m², and the one or more drive rolls are all suction rolls.

Description

Film conveying method and optical film manufacturing method

The present invention relates to a film transport method, and more particularly to a method of continuously transporting a connection film formed by connecting a plurality of films including an optical film having relatively low toughness by a drive roll along a transport path. . The present invention also relates to a method for producing an optical film using the transport method.

A method of continuously feeding a film while continuously feeding the film through a predetermined conveyance path and contacting a plurality of rolls is a general film conveyance method, and is a film wound in a roll shape. It is also a common practice in the production of various optical films to roll out the film from the roll and perform rewinding and stretching of the film and pasting with other films during the conveyance.

The various rolls used in the transporting process include a free roll that supports only one side of the film and a nip roll that is arranged on both sides of the film and supports the film from both sides. Among these, the nip roll is the tension of the film. It is one of the rolls that greatly affects the adjustment, driving for film conveyance, pressing on the film, and prevention of air bubbles, wrinkles and unevenness.

For example, Japanese Patent Application Laid-Open No. 2005-035147 (Patent Document 1) discloses a method of forming a film by pressing a melt-extruded resin with a nip roll. JP-A-11-048271 (Patent Document 2) further discloses JP-A-2006-339287 (Patent Document 3) in order to prevent unevenness of the web (film) generated during drying in the tenter. ) Discloses the use of nip rolls as means for applying pressure from both sides of the web (film) for defoaming gas that enters the member during film bonding.

In the above-described continuous film transport method, when a target film is first passed through a predetermined transport path, a lead film is connected in advance to the leading end of the film, and first the lead film is continuously passed through the transport path. In general, the film is conveyed and subsequently the target film is conveyed. Similarly, when the transport process is temporarily stopped, the lead film is stopped in a state in which the lead film is connected to the end of the film in preparation for the subsequent re-operation. Generally, the conveyance of the target film is started by connecting to the end of the film. Furthermore, the films may be connected to each other in order to continuously transport the film, such as adding the same type of film or switching to a different type of film. As described above, the connection between the films is frequently used in the continuous conveyance process of the film.

Examples of methods for connecting films include heat sealing as disclosed in Japanese Patent Application Laid-Open No. 2010-008509 (Patent Document 4), and methods of connecting films with a tape. Japanese Patent Application Laid-Open No. 08-208083 (Patent Document 5) discloses a method of joining a plurality of original fabric rolls with a turret.

JP 2005-035147 A Japanese Patent Laid-Open No. 11-048271 JP 2006-339287 A JP 2010-008509 A Japanese Patent Application Laid-Open No. 08-208083

In recent years, low-power consumption, low-voltage operation, lightweight and thin image display devices (for example, liquid crystal display devices) are widely used in information display devices such as mobile phones, personal digital assistants, computer monitors, and televisions. It has been. Such an information display device is required to be further thinned depending on applications, and various optical films constituting the information display device are also required to be thin.

Regarding the material of the optical film used, various design changes have been proposed for the purpose of improving performance.For example, if a polarizing plate used in a liquid crystal display device is taken as an example, as a protective film bonded to the polarizing film, Triacetyl cellulose films have been widely used in the past, but recently, from the viewpoint of transparency and heat resistance, thin glass, acrylic and norbornene resin films are also being used.

However, due to the thinning and diversification of optical films, problems with inferior toughness have arisen, such as cracking during handling in the process. For example, when connecting films to each other, no matter what connection method is used, a slight shift or overlap between films occurs, or a connecting tape is affixed on the film. Unevenness is inevitable. For this reason, when the connection part of a film passes between nip rolls, a pressure is applied to the slight convex part, and a crack, a crack (crack) may arise in a film, and it may lead to a fracture of a film. In particular, these problems are likely to occur in a fragile film with low flexibility.

When the film is cracked, cracked or broken, the portion is discarded as a defective portion, so that the yield of the film is reduced and the manufacturing efficiency is reduced due to the removal operation of the defective portion and preparation for restarting the process. Further, when the film is cracked or broken, the inside of the process may be contaminated by the scattered film fragments.

An object of the present invention is a method for transporting a connecting film formed by connecting a plurality of films including an optical film having a relatively low toughness (flexibility), and the connecting film, particularly a connecting portion of the film is cracked. Another object of the present invention is to provide a method capable of continuously conveying a film without causing problems such as breakage. Another object of the present invention is a method for producing an optical film by using the above-mentioned transport method, and the optical film, in particular, a continuous portion without causing problems such as cracks, cracks and breaks in the connecting portion of the film. Another object of the present invention is to provide a method capable of manufacturing the optical film.

The present invention provides the following film transport method and optical film manufacturing method.
[1] A method of continuously transporting a connecting film including a first film and a second film connected to a longitudinal end thereof along the transport path including one or more driving rolls by the one or more driving rolls. Because
At least one of the first film and the second film is an optical film having a Charpy impact strength of less than 200 kJ / m ² ,
The conveying method, wherein the one or more drive rolls are all suction rolls.

[2] The transport method according to [1], wherein one of the first film and the second film is the optical film, and the other is a lead film having a Charpy impact strength of 200 kJ / m ² or more.

[3] The first film and the second film are both optical films,
The transport method according to [1], wherein the first film and the second film are the same type of optical film.

[4] At least the second film is the optical film,
The transport method according to any one of [1] to [3], wherein the connection film further includes a third film connected to a longitudinal end of the second film.

[5] The transport method according to any one of [1] to [4], wherein the optical film includes a base film and a coating layer laminated thereon.

[6] A step of producing an optical film having a Charpy impact strength of less than 200 kJ / m ² ;
A step of continuously transporting the first film and a connecting film including the second film connected to the longitudinal end thereof by the one or more drive rolls along a transport path including one or more drive rolls;
Including
At least one of the first film and the second film is the optical film,
The method for producing an optical film, wherein the one or more drive rolls are all suction rolls.
[7] The manufacturing method according to [6], wherein the optical film is selected from the group consisting of a single-layer optical film, a multilayer optical film, a stretched optical film, and an optical film having a coating layer.

[8] producing a second optical film from the first optical film;
A step of continuously transporting the first film and a connecting film including the second film connected to the longitudinal end thereof by the one or more drive rolls along a transport path including one or more drive rolls;
Including
At least one of the first film and the second film has the Charpy impact strength of less than 200 kJ / m ² or the first optical film or Charpy impact strength of less than 200 kJ / m ² or the second optical film. A film,
The method for producing an optical film, wherein the one or more drive rolls are all suction rolls.

[9] The manufacturing method according to [8], wherein the second optical film is selected from the group consisting of a single-layer optical film, a multilayer optical film, a stretched optical film, and an optical film having a coating layer.

According to the method of the present invention, a connecting film including an optical film having a relatively low toughness, that is, a relatively low flexibility and a brittleness, in particular, without causing problems such as cracks, cracks and fractures in the connecting portion. Thus, the connecting film can be conveyed. Thereby, while being able to improve the stability of various manufacturing processes using the optical film including the process which conveys the said connection film, and the said conveyance process, manufacturing efficiency, and work efficiency, the yield fall of the optical film by said malfunction And the yield of products manufactured using an optical film can be improved.

It is a schematic diagram which shows an example of the conveying apparatus used for the conveying method of the film which concerns on this invention, and the manufacturing method of an optical film. It is a top view which shows an example of a connection film typically.

<Film Conveying Method and Optical Film Manufacturing Method>
In the film transport method of the present invention, a long connecting film including a first film and a second film connected to a longitudinal end thereof is moved along a transport path including one or more driving rolls constructed by a transport device. (Through a transport path) and a method of transporting continuously by the one or more drive rolls. At least one of the first film and the second film is an optical film having relatively small flexibility and being brittle and having a Charpy impact strength of less than 200 kJ / m ² .

The drive roll means a rotatable roll that gives a driving force for film conveyance, and simply plays a role of supporting a traveling film, and a guide roll (free roll) that cannot give a driving force for film conveyance. Is also not included in the drive roll. As the driving roll, the above-described nip roll is typical, but in the present invention, a suction roll (suction roll) is used for all of the one or more driving rolls, and the conveyance path does not include the nip roll.

The suction roll is a rotatable roll having a large number of suction holes formed on the outer peripheral surface and capable of adsorbing a film that contacts the outer peripheral surface by sucking air from the suction holes. Unlike the nip roll, the suction roll supports only one side of the passing film. However, since the above-described adsorption can prevent slippage between the film and the roll, the rotational driving force of the roll is transmitted to the adsorbed film. Thus, the film can be conveyed while maintaining an appropriate film tension.

The suction roll is not particularly limited, but for example, a metal such as stainless steel or a ceramic one can be used. In order to prevent the film surface from being scratched or sucked, a film in which the contact surface with the film is coated with nickel mesh, rubber, urethane resin or the like may be used.

As described above, since the film connecting portion of the connecting film has some unevenness, when a nip roll that presses the film from above and below is used as a driving roll, pressure is applied to the convex portion when the connecting portion passes between the nip rolls. It may cause cracks, cracks (cracks), and breaks in the connecting part. If all of the drive rolls are suction rolls, no pressing load is applied to the convex portions of the connecting portions, so that the above-described problems can be effectively prevented.

FIG. 1 is a schematic diagram showing an example of a transport device used in a film transport method and an optical film manufacturing method according to the present invention. FIG. 2 is a top view schematically showing an example of the connection film, and shows the connection film shown in FIG. 1 in an enlarged manner.

Referring to FIG. 1, an embodiment of a film transport method according to the present invention will be described. FIG. 1 shows a state in which a connecting film in which a long first film 10 and a long second film 20 are connected is continuously transported along a transport path of a transport device. In the transport apparatus shown in FIG. 1, the transport path is such that the film (second film 20 in the example of FIG. 1) is continuously fed out by its rotation; a guide roll 60 that supports the traveling film from one side; a drive roll The suction roll 40 is included. Although not shown in the drawing, a winding device for winding the film is usually provided at the downstream end of the transport path, and the film that has passed through the transport path is sequentially wound into a film roll. In FIG. 1, solid line arrows indicate the film conveyance direction or the rotation direction of the feeding device.

The connection film can be conveyed, for example, as follows. First, the long first film 10 conveyed in advance is passed through the conveyance path, and continuous conveyance is started using the rotational driving force of the suction roll 40. The long first film 10 is usually prepared as a film roll wound in a roll shape. The film roll is set in a feeding device (the feeding device 50 or another feeding device different from this), and the first film 10 is continuously fed out from the feeding device and is continuously conveyed. The first film 10 may be an optical film having a Charpy impact strength of less than 200 kJ / m ² or may be another film such as the lead film described above.

When the conveyance of the first film 10 is approaching the end, the longitudinal end of this film and the longitudinal start of another second film 20 prepared in advance and set in the feeding device 50 are connected to form a film connecting portion. Form. The long second film 20 is also usually prepared as a film roll wound in a roll shape. The second film 20 may be an optical film having a Charpy impact strength of less than 200 kJ / m ² , or may be another film such as the lead film described above. However, when the first film 10 is another film, the second film 20 is an optical film. Switching between film rolls (paper splicing) can also be performed using a turret.

After connecting the 1st film 10 and the 2nd film 20, a film (connection film) is conveyed using the rotational driving force of the suction roll 40 continuously.

The present invention also relates to a method for producing an optical film using the film transport method. That is, with reference to FIG. 1, the manufacturing method of the optical film which concerns on this invention is the following process in one embodiment:
Producing an optical film having a Charpy impact strength of less than 200 kJ / m ² ;
A step of continuously transporting the first film and the connection film including the second film connected to the longitudinal end thereof along the transport path including the one or more drive rolls by the one or more drive rolls;
including.

Here, at least one of the first film and the second film in the transporting step is an optical film having a Charpy impact strength of less than 200 kJ / m ² manufactured in the manufacturing step. The one or more drive rolls included in the transport path are all suction rolls 40 as in the film transport method according to the present invention.

The optical film can be a single layer optical film, a multilayer optical film, a stretched optical film, an optical film having a coating layer, etc., as will be described later.

Moreover, the manufacturing method of the optical film which concerns on this invention is the following process in other embodiment:
Producing a second optical film from the first optical film;
A step of continuously transporting the first film and the connection film including the second film connected to the longitudinal end thereof along the transport path including the one or more drive rolls by the one or more drive rolls;
including.

Here, at least one of the first film and the second film in the transporting step is the first optical film or the second optical film manufactured in the manufacturing step and has a Charpy impact strength of 200 kJ. / M ² is an optical film. The one or more drive rolls included in the transport path are all suction rolls 40 as in the film transport method according to the present invention.

The first optical film and the second optical film may be a single layer optical film, a multilayer optical film, a stretched optical film, an optical film having a coating layer, etc., as will be described later.

In one example of the method for producing an optical film according to the present invention, the first optical film has a Charpy impact strength of less than 200 kJ / m ² and the second optical film is a multilayer optical film. In another example of the method for producing an optical film according to the present invention, the second optical film is a stretched optical film or an optical film having a coating layer, and has a Charpy impact strength of less than 200 kJ / m ² .

The following description relates to both the film transport method and the optical film manufacturing method according to the present invention.

In the example shown in FIGS. 1 and 2, the films are connected using the connecting tape 30, but the present invention is not limited to this, and other methods such as heat sealing can be used as a matter of course. It is. When the connecting tape 30 is used, the convex portion generated in the film connecting portion is likely to be larger than the connection by heat sealing. Therefore, the method of the present invention is particularly effective when applied to a connecting film using the connecting tape 30.

The connecting tape 30 can be a single-sided adhesive tape. The base material of the single-sided adhesive tape is, for example, a polyester resin such as polyethylene terephthalate; a cellulose resin such as cellulose; paper (Japanese paper or the like); aluminum; a nonwoven fabric; polytetrafluoroethylene, polyvinyl chloride, or polyvinylidene chloride. Such as chlorine-containing resin, polycarbonate resin, polyurethane resin, ABS resin, polystyrene resin, polyolefin resin such as polyethylene and polypropylene, polyacetal resin, polylactic acid, polyimide resin, polyamide resin, etc. be able to. Adhesive layer of single-sided adhesive tape is acrylic, epoxy, polyurethane, synthetic rubber, EVA, silicone, vinyl chloride, chloroprene rubber, cyanoacrylate, isocyanate, polyvinyl alcohol, melamine resin It can consist of

When forming the film connecting portion using the connecting tape 30, after cutting the end portion of each film so that the end surface of the first film 10 and the end surface of the second film 20 are parallel to each other. It is preferable to perform bonding with the connecting tape 30. Manual cutting may be sufficient as the cutting | disconnection of an edge part, and the subsequent bonding, and you may carry out automatically using an apparatus. In the latter case, for example, the apparatus and method described in JP2011-154371A can be employed.

The transport path for transporting the connecting film may include two or more suction rolls 40. The film transport speed when the connected film is continuously transported along the transport path is, for example, in the range of 2 to 120 m / min, and preferably in the range of 10 to 50 m / min.

In order to effectively transmit the rotational driving force of the suction roll 40 to the connection film adsorbed thereto, it is preferable to increase the contact area between the outer peripheral surface of the suction roll 40 and the connection film. For this reason, it is preferable that the conveyance direction of a connection film changes 10 degrees or more, further 30 degrees or more, and still more 40 degrees or more, when passing the suction roll 40. FIG. With reference to FIG. 1, the angle refers to the conveyance direction before the film conveyance direction is changed by the suction roll 40 (the conveyance direction immediately before passing through the suction roll 40), and after the film conveyance direction is changed by the suction roll 40. Means the angle θ formed by the transport direction (the transport direction immediately after passing through the suction roll 40).

The tension of the film when the first film 10 transported in advance is continuously transported along the transport path, and the tension of the film when the connected film is transported continuously along the transport path are, for example, 20 -1500 N / m, preferably 50-1000 N / m, more preferably 70-700 N / m. When the tension of the film is in such a range, it is possible to stabilize the conveyance of the film, and this may occur due to the occurrence of wrinkles or scratches due to the sliding of the film or the occurrence of the wrinkles or scratches. Breakage of the film can be prevented. Since at least one of the first film and the second film constituting the connection film provided for the method according to the present invention is a film having relatively small flexibility and brittleness, the tension of the film is set in the above range. Is effective in preventing the occurrence of wrinkles or scratches and the breakage of the film.

The diameter of the suction roll 40 is, for example, 100 to 900 mm, and preferably 200 to 400 mm. When the diameter of the suction roll 40 is in such a range, the tension of the film can be adjusted appropriately, thereby causing wrinkles or scratches due to slipping of the film, or the occurrence of wrinkles or scratches. Thus, breakage of the film that may occur can be prevented. Since at least one of the first film and the second film constituting the connecting film provided for the method according to the present invention is a film having a relatively small flexibility and a brittleness, the diameter of the suction roll 40 is within the above range. It is effective to prevent the generation of wrinkles or scratches and the breakage of the film.

The diameter of the suction hole of the suction roll 40 is, for example, 0.1 to 10 mm, preferably 0.5 to 5 mm. When the diameter of the suction hole is in such a range, the tension of the film can be adjusted appropriately, which may be caused by the occurrence of wrinkles or scratches due to the sliding of the film or the occurrence of the wrinkles or scratches. It is possible to prevent the film from being broken. Since at least one of the first film and the second film constituting the connection film provided for the method according to the present invention is a film having relatively small flexibility and brittleness, the diameter of the suction hole is in the above range. This is effective in preventing the occurrence of wrinkles or scratches and the breakage of the film. Moreover, when the diameter of the suction hole is in the above range, it is possible to prevent the suction hole from being left on the surface of the film to be conveyed.

The suction pressure of the suction roll 40 is, for example, 1 to 100 kPa, preferably 2 to 30 kPa. When the suction pressure of the suction roll 40 is within such a range, the tension of the film can be adjusted appropriately, thereby causing wrinkles or scratches due to slipping of the film, and the occurrence of the wrinkles or scratches. It is possible to prevent breakage of the film that may be caused. Since at least one of the first film and the second film constituting the connection film provided for the method according to the present invention is a film having relatively small flexibility and brittleness, the suction pressure of the suction roll 40 is in the above range. It is effective in preventing the occurrence of wrinkles or scratches and the breakage of the film. Moreover, when the suction pressure of the suction roll 40 is within the above range, it is possible to prevent the suction holes from being left on the surface of the film being conveyed.

The film transport method of the present invention can be applied to a process of continuously transporting a connecting film including at least a part of an optical film and any manufacturing process using an optical film including the transport process. Specific examples include a step of simply transporting the optical film, a step of applying some kind of treatment (for example, coating treatment or stretching treatment) to the optical film, and a step of bonding the optical film to another member (film or the like). In addition, Patent Document 4, Patent Document 5, JP 2011-154371 A, International Publication No. 09/128384, International Publication No. 12/160966, JP 2009-276754 A, JP 2012-061837 A. It can also be applied to the processes described in the publication.

<Connecting film>
As described above, the connection film includes the first film 10 and the second film 20 connected to the end in the longitudinal direction. The connection film may include a third film connected to the end of the second film 20 in the longitudinal direction, a fourth film connected to the end of the third film in the longitudinal direction, if necessary.

At least one of the first film 10 and the second film 20 is an optical film having a Charpy impact strength of less than 200 kJ / m ² . When an optical film is used for only one film, the other film can be the lead film described above. When the first film 10 is a lead film and the second film 20 is an optical film, for example, the lead film is first passed through the transport path (or previously passed through the transport path), and the optical film is terminated at the end. For example, when the film is continuously conveyed. When the first film 10 is an optical film and the second film 20 is a lead film, for example, when the transport process is temporarily stopped, the lead film is placed at the end of the optical film in preparation for a subsequent restart. For example, when the lead film is connected and the transport process is stopped in a state where the lead film exists in the transport path. In this case, a new optical film is connected to the end of the lead film and the transport process is restarted.

Both the first film 10 and the second film 20 may be optical films. In this case, these optical films may be different optical films or the same kind of optical films. The same kind of optical film means the same (functions, configurations, and specifications are the same) except that the film rolls prepared for conveyance are different.

As a specific configuration in the case where the connecting film includes the third film, the first film / second film / third film are lead film / optical film / lead film, lead film / optical film / optical film, optical film / Examples thereof include an optical film / lead film and an optical film / optical film / optical film.

“Charpy impact strength” in the present invention refers to the impact absorption energy of plastics stipulated in JIS K 7111: 2006 “Plastics-Determination of Charpy impact properties-Part 1: Uninstrumented impact test” It is a value of shock absorption energy measured in accordance with a Charpy impact test. In this Charpy impact test, the energy required for a hammer (pendulum) for punching a test piece to punch (break) the test piece in the width direction perpendicular to its length direction is taken as shock absorption energy. The JIS standard defines a case where a notched test piece is used and a case where a notched test piece is used, but since the present invention is intended for a film, the notched test piece is adopted.

Describing a specific measurement procedure based on the JIS standard, first, a test piece having a width of about 10 mm and a length of about 82 mm is punched or cut out from the film. At this time, as a test piece, a first test piece having a length direction (direction of 82 mm on one side) as a mechanical extrusion direction (MD) of the film and a length direction (82 mm on a side) perpendicular to MD (TD). Two types of second test specimens, each having a direction of 2), are prepared in order to test each of a case in which a hammer is hit from one side of the film and a case in which it is hit from the other side. Next, to prevent the specimen from moving due to the impact of punching with a hammer, both ends of the specimen in the long side direction are fixed to the support base, and the energy required to break the specimen with the Charpy impact tester (impact absorption energy) Measure. It means that a test piece, ie, a film, is hard to break, so that this shock absorption energy is large. At this time, since the first test piece having the MD of the film in the length direction is broken along the direction orthogonal to the MD, that is, along the TD, the impact absorption energy of TD is given and the TD of the film is set to the length direction. Since the 2nd test piece fractures along MD, it gives impact absorption energy of MD.

In the present invention, “an optical film having a Charpy impact strength of less than 200 kJ / m ² ” means the impact absorption energy in MD and TD when a hammer is hit from one side of the film, measured by the above method. It is defined as an optical film in which at least one of the value and the value of impact absorption energy in MD and TD when a hammer is hit from the other side of the film is less than 200 kJ / m ² . Of course, all the values of the impact absorption energy of MD and TD when the hammer is hit from one side of the film, and the values of the impact absorption energy of MD and TD when the hammer is hit from the other side of the film Optical films having a <200 kJ / m ² can also be advantageously targeted. As the Charpy impact strength of the optical film is smaller, cracks, cracks, and breaks are more likely to occur, so the merit of applying the method of the present invention is great. If the Charpy impact strength of the optical film is less than 190 kJ / m ² , the effect of the present invention is greater, and if it is less than 180 kJ / m ² , the effect is even greater.

As a material constituting the lead film, conventionally known materials can be used, but the lead film is preferably a tough film having a Charpy impact strength of 200 kJ / m ² or more. When a lead film having a Charpy impact strength of 200 kJ / m ² or more is used, it is difficult to break, so that handling properties when used as a connecting film itself are improved. In addition, the connection film can be made less susceptible to cracks, cracks and breaks. Here, “Charpy impact strength is 200 kJ / m ² or more” means the value of impact absorption energy in MD and TD when a hammer is hit from one side of the film, measured by the above method, and It means that all the values of the impact absorption energy in MD and TD when hitting a hammer from the other side of the film are 200 kJ / m ² or more.

The lead film can be a resin film, and as a resin material capable of achieving the Charpy impact strength in the above range, for example, a polyester resin such as polyethylene terephthalate; a polyvinyl chloride resin such as polyvinyl chloride; Examples thereof include polyolefin resins such as polyethylene and polypropylene. The Charpy impact strength of the lead film is more preferably 250 kJ / m ² or more, and further preferably 300 kJ / m ² or more.

<Optical film>
Next, optical films that can be used in the present invention will be described.

(1) Single-layer optical film and production method thereof The single-layer optical film is not particularly limited as long as it has translucency (preferably transparency), and may be a film made of an organic material or an inorganic material. It may be a film. A suitable example of a film made of an inorganic material is a film made of a glass material from the viewpoint of transparency. Examples of the film made of a glass material include glass films described in JP 2012-247785 A, International Publication No. 12/090693, JP 08-283041 A, and the like.

Examples of the film made of an organic material include various thermoplastic resin films. Specific examples of the thermoplastic resin include, for example, a polyolefin resin such as a chain polyolefin resin and a cyclic polyolefin resin (such as a norbornene resin); a polyester resin such as polyethylene terephthalate; and a methyl methacrylate resin. (Meth) acrylic resins; cellulose resins such as cellulose triacetate and cellulose diacetate; polycarbonate resins; polyvinyl alcohol resins; polyvinyl acetate resins; polyarylate resins; polystyrene resins; Polysulfone resins; polyamide resins; polyimide resins; and mixtures and copolymers thereof.

In this specification, “(meth) acryl” means at least one selected from acrylic and methacrylic. The same applies to cases such as “(meth) acryloyl” and “(meth) acrylate”.

The optical film can contain various additives as required. Specific examples of additives include fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, ultraviolet absorbers, infrared absorbers, antistatic agents, antioxidants, rubber elastic particles, lubricants, and the like.

The ultraviolet absorber is a compound that absorbs ultraviolet rays having a wavelength of 400 nm or less. For example, when the optical film is used as a protective film for a polyvinyl alcohol polarizing film, the durability of the polarizing plate in which the protective film is bonded to the polarizing film can be improved by adding an ultraviolet absorber.

As the UV absorber, a benzophenone UV absorber, a benzotriazole UV absorber, an acrylonitrile UV absorber, or the like can be used. As a specific example, 2,2′-methylenebis [4- (1, 1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol]; 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol; 2,2′-dihydroxy-4,4′-dimethoxybenzophenone; 2,2 ′, 4 4,4'-tetrahydroxybenzophenone. Among these, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] is one of preferable ultraviolet absorbers. One.

The blending amount of the ultraviolet absorber is preferably selected so that the light transmittance at a wavelength of 370 nm or less of the optical film is preferably 10% or less, more preferably 5% or less, and further preferably 2% or less. Examples of the method of containing the ultraviolet absorber include a method in which the ultraviolet absorber is pre-blended into a resin and pelletized, and this is molded into a film by melt extrusion or the like. And a method of adding an agent.

An infrared absorber is a compound that absorbs infrared rays having a wavelength of 800 nm or more. For example, a nitroso compound and a metal complex thereof; a cyanine compound; a squarylium compound; a thiol nickel complex compound; a phthalocyanine compound; a naphthalocyanine compound; a triarylmethane compound; an imonium compound; Anthraquinone compounds; amino compounds; aminium salt compounds; carbon blacks; indium tin oxide; antimony tin oxides; oxides, carbides or borides of metals belonging to groups 4A, 5A or 6A of the periodic table Can do. The infrared absorber is preferably selected so that it can absorb the entire infrared ray (light having a wavelength in the range of about 800 to 1100 nm), and two or more types may be used in combination. The blending amount of the infrared absorber is preferably selected so that, for example, the light transmittance at a wavelength of 800 nm or more of the optical film is 10% or less.

When the optical film is a thermoplastic resin film, particularly a (meth) acrylic resin film, it is preferable to add rubber elastic particles in order to improve the film forming property. Rubber elastic particles are particles including a layer exhibiting rubber elasticity. The rubber elastic particles may be particles composed of only a layer exhibiting rubber elasticity, or may be particles having a multilayer structure having other layers together with a layer exhibiting rubber elasticity. Examples of rubber elastic bodies include olefin-based elastic polymers, diene-based elastic polymers, styrene-diene-based elastic copolymers, and acrylic-based elastic polymers. Of these, acrylic elastic polymers are preferably used from the viewpoints of surface hardness, light resistance and transparency of the optical film.

The acrylic elastic polymer can be composed of a polymer mainly composed of alkyl acrylate. The polymer mainly composed of alkyl acrylate may be a homopolymer of alkyl acrylate, or a copolymer of 50% by weight or more of alkyl acrylate and 50% by weight or less of other monomers. May be. As the alkyl acrylate, an alkyl acrylate having 4 to 8 carbon atoms is usually used. Examples of copolymerization of monomers other than alkyl acrylate include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; styrene monomers such as styrene and alkyl styrene; acrylonitrile and methacrylo Monofunctional monomers such as unsaturated nitriles such as nitriles, and alkenyl esters of unsaturated carboxylic acids such as allyl (meth) acrylate and methallyl (meth) acrylate; dibasic acids such as diallyl maleate And polyfunctional monomers such as unsaturated carboxylic acid diesters of glycols such as alkylene glycol di (meth) acrylate.

The rubber elastic particles containing the acrylic elastic polymer are preferably multi-layered particles having an acrylic elastic polymer layer. Specifically, a two-layer structure having a hard polymer layer mainly composed of alkyl methacrylate on the outside of the acrylic elastic body, or a hard body mainly composed of alkyl methacrylate inside the acrylic elastic body. The thing of the 3 layer structure which has a polymer layer is mentioned. The polymer mainly composed of alkyl methacrylate constituting the hard polymer layer formed outside or inside the acrylic elastic body is preferably a polymer mainly composed of methyl methacrylate. Acrylic rubber elastic particles having a multilayer structure can be produced by a method described in, for example, Japanese Patent Publication No. 55-027576.

When a lubricant is added to the optical film, especially in the case of a (meth) acrylic resin film, the slipperiness of the surface of the optical film is improved, and the film roll is tightened. The appearance can be improved. When the lubricant and the rubber elastic body particles are used in combination, the effect of improving slipperiness can be further enhanced. As the lubricant, there are a stearic acid compound, a (meth) acrylic compound, an ester compound, etc. Among them, a stearic acid compound is preferably used.

The thickness of the single-layer optical film is usually about 2 to 300 μm, preferably 200 μm or less, more preferably 150 μm or less.

The single-layer optical film can be produced by an arbitrary method such as a melt extrusion method or a solvent casting method. For example, in the case of the melt extrusion method, a method of forming a film in a state in which a melt-extruded resin (thermoplastic resin) is sandwiched between two metal rolls is preferably employed. In this case, the metal roll is preferably a mirror roll, whereby an optical film having excellent surface smoothness can be obtained.

(2) Multilayer optical film and method for producing the same The optical film may be a multilayer optical film having a multilayer structure of two layers, three layers or more. Although the structure of a multilayer optical film is not specifically limited, For example, the following embodiment can be illustrated.

[A] A multilayer optical film of the same type, but coextruded by combining layers made of different resins (for example, a first layer made of (meth) acrylic resin and a different (meth) acrylic resin) A multilayer optical film comprising a second layer,
[B] A multilayer optical film (for example, a multilayer optical film including a first layer made of (meth) acrylic resin and a second layer made of polystyrene resin) coextruded by combining layers made of different resins.
[C] A multilayer optical film made of the same type (or the same) resin but coextruded by combining layers having different types and contents of additives,
[D] a multilayer optical film in which the above-mentioned single-layer optical film or multilayer optical film is laminated by extrusion lamination,
[E] A multilayer optical film obtained by laminating the above-described single-layer optical film via an adhesive or a pressure-sensitive adhesive, or a single-layer optical film and a multilayer optical film, or a multilayer optical film and a multilayer optical film with an adhesive or pressure-sensitive adhesive. Multi-layer optical film bonded through.

The multilayer optical film co-extruded in the above [a] to [c] can be produced in the same manner as the single-layer optical film except that the resin composition forming each layer is multilayer co-extruded.

The multilayer optical film of [d] may be a laminate of the same type of film, or may be a laminate of different types of films. The multilayer optical film of [d] above is obtained by laminating and laminating another optical film from a certain side in the process on the melt-extruded optical film, pressing and bonding, cooling, and rolling it with a winder It can be produced by winding. Alternatively, the optical film is fed out from one side in the process, the resin layer is melt-extruded thereon, and another optical film is fed out from the other side in the process, laminated on the resin layer, and added in the same manner. It can be produced by pressing and bonding, cooling, and winding into a roll with a winder. Corona treatment, ozone treatment, anchor coating treatment, adhesive coating treatment on any or all of the layers to be laminated prior to or simultaneously with the lamination in order to improve the adhesion strength between the laminated films. In some cases, it is preferable to appropriately perform the adhesion improving treatment by such a method. The number of layers to be laminated is not particularly limited, and a necessary layer may be appropriately laminated, or the above-described treatment may be performed as necessary at the time of lamination.

The multilayer optical film of [e] above is a combination of layers made of the same type of resin (including the same resin and different resins) when single-layer optical films are bonded together. Alternatively, a combination of different resin layers may be used. Moreover, as above-mentioned, the combination of a single layer optical film and a multilayer optical film, and the combination of a multilayer optical film and a multilayer optical film may be sufficient. An example of the multilayer optical film of [e] is one in which a thermoplastic resin film is bonded to at least one surface of a polarizing film via an adhesive or a pressure-sensitive adhesive. The polarizing film can be a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film to give a predetermined polarizing property.

As the adhesive, a water-based adhesive or a solventless adhesive can be used. The water-based adhesive is, for example, an adhesive component such as a water-soluble crosslinkable epoxy resin or a hydrophilic urethane resin dissolved in water, or the adhesive component dispersed in water. Can do.

Solventless adhesives do not contain a significant amount of solvent, and contain a curable component (monomer or oligomer) that is reactively cured by heating or irradiation with active energy rays (eg, ultraviolet rays, visible light, electron beams, X-rays, etc.). And an adhesive layer is formed by curing the curable component, and typically includes the curable component and a polymerization initiator.

Examples of the curable component include epoxy resins, urethane resins, cyanoacrylate resins, (meth) acrylamide resins, and the like.

Further, as the pressure-sensitive adhesive, for example, a pressure-sensitive adhesive composition containing a base polymer such as a (meth) acrylic resin, a silicone-based resin, a polyester-based resin, a polyurethane-based resin, or a polyether-based resin, and a crosslinking agent is used. Can do. The pressure-sensitive adhesive composition can further contain an additive such as an antistatic agent. The pressure-sensitive adhesive composition is preferably one in which the reaction with the crosslinking agent has sufficiently progressed by aging. The aging conditions are not particularly limited. For example, aging can be performed for several hours to several days in an environment of a temperature of 23 ° C. and a relative humidity of 65%.

The optical film may be obtained by subjecting the thermoplastic resin film produced as described above to a stretching treatment. A stretching process may be required to obtain an optical film having desired optical properties. Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include a machine flow direction (MD) of an unstretched film, a direction orthogonal to the machine flow direction (TD), and a direction oblique to the machine flow direction (MD). Biaxial stretching may be simultaneous biaxial stretching in which stretching is performed simultaneously in two stretching directions, or sequential biaxial stretching in which stretching is performed in a predetermined direction and then stretching in another direction.

For the stretching process, for example, two or more pairs of nip rolls with increased peripheral speed on the outlet side are used to stretch in the longitudinal direction (machine flow direction: MD), or the both ends of the unstretched film are gripped with a chuck and machine flow is performed. It is performed by spreading in a direction (TD) orthogonal to the direction.

The draw ratio by the drawing treatment is preferably more than 0 to 300%, more preferably 100 to 250%. If the draw ratio exceeds 300%, the film thickness becomes too thin and breaks easily, or the handleability decreases. The draw ratio is the following formula:
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)
More demanded.

Further, in order to impart desired optical properties, a heat shrinkable film may be bonded to a thermoplastic resin film in place of or along with the stretching process, and a process of shrinking the thermoplastic resin film may be performed.

(3) Optical film which has a coating layer By providing a coating layer to an optical film, the specific function according to the kind of coating layer can be provided. Examples of an optical film having a coating layer include, for example: [a] an optical film having a hard coat layer for preventing scratches on the surface,
[B] an optical film having an antistatic layer,
[C] an optical film having an antireflection layer,
[D] an optical film having an antifouling layer;
[E] an optical film having an antiglare layer for improving visibility, preventing reflection of external light, and reducing moire due to interference between a prism sheet and a color filter,
It is. As the base film on which the coating layer as described above is laminated, a single-layer optical film or a multilayer optical film such as the above-described thermoplastic resin film can be used.

Also, as the base film, a multilayer optical film having a coating layer obtained by laminating an optical film obtained by laminating a coating layer on a single layer or a multilayer optical film with another single layer optical film or a multilayer optical film can also be used.

In particular, when a coating layer is provided on a (meth) acrylic resin film, the Charpy impact strength of the optical film may be extremely smaller than before the coating layer is provided, and thus an optical film having a small Charpy impact strength. On the other hand, the present invention is preferably applied.

(Hard coat layer)
The hard coat layer has a function of increasing the surface hardness of the optical film and is provided for the purpose of preventing scratches on the surface. The hard coat layer is a pencil hardness test as defined in JIS K 5600-5-4: 1999 “Paint General Test Method—Part 5: Mechanical Properties of Coating Film—Section 4: Scratch Hardness (Pencil Method)” An optical film having a hard coat layer is measured by placing it on a glass plate), and it is preferable to show a value of 2H or higher. The material for forming the hard coat layer is generally cured by heat or light. For example, organic hard coat materials such as organic silicone, melamine, epoxy, (meth) acrylic, urethane (meth) acrylate, and inorganic hardcoat materials such as silicon dioxide can be used. Among these, when the base film on which the hard coat layer is laminated is a (meth) acrylic resin film, the adhesive strength to the film is good and the productivity is excellent. A polyfunctional or polyfunctional (meth) acrylate hard coat material is preferred.

The hard coat layer contains various fillers for the purpose of adjusting the refractive index, improving the flexural modulus, stabilizing the volume shrinkage, and improving heat resistance, antistatic properties, antiglare properties, etc., if desired. can do. The hard coat layer can also contain additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent.

(Antistatic layer)
The antistatic layer is provided for the purpose of imparting conductivity to the surface of the optical film and suppressing the influence of static electricity. For the formation of the antistatic layer, for example, a method of applying a resin composition containing a conductive substance (antistatic agent) to the base film can be employed. For example, an antistatic hard coat layer can be formed by allowing an antistatic agent to coexist in the hard coat material used for forming the hard coat layer described above.

(Antireflection layer)
The antireflection layer is a layer for preventing reflection of external light, and is provided directly on the surface (surface exposed to the outside) of the optical film or via another layer such as a hard coat layer. The optical film having the antireflection layer preferably has a reflectance of 2% or less at an incident angle of 5 ° with respect to light having a wavelength of 430 to 700 nm, and particularly has a reflectance of 1 at the same incident angle with respect to light having a wavelength of 550 nm. % Or less is preferable.

The thickness of the antireflection layer can be about 0.01 to 1 μm, preferably 0.02 to 0.5 μm. The antireflection layer is formed from a low refractive index layer having a refractive index smaller than the refractive index of the layer (base film, hard coat layer, etc.) on which it is provided, specifically a refractive index of 1.30 to 1.45. Or a plurality of low refractive index layers made of inorganic compounds and high refractive index layers made of inorganic compounds alternately stacked.

The material for forming the low refractive index layer is not particularly limited as long as it has a low refractive index. For example, a resin material such as an ultraviolet curable (meth) acrylic resin; a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin; a sol-gel material containing an alkoxysilane can be used. Such a low refractive index layer may be formed by applying a polymer that has been polymerized, or may be formed by applying in the state of a monomer or oligomer that becomes a precursor, and then polymerizing and curing. Moreover, it is preferable that each material contains the compound which has a fluorine atom in a molecule | numerator, in order to provide antifouling property.

As the sol-gel material for forming the low refractive index layer, a material having a fluorine atom in the molecule is preferably used. A typical example of a sol-gel material having a fluorine atom in the molecule is perfluoroalkylalkoxysilane. The perfluoroalkylalkoxysilane is, for example, the following formula:
CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃
Wherein R represents an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 0 to 12. Of these, compounds in which n is 2 to 6 in the above formula are preferred.

Specific examples of perfluoroalkylalkoxysilanes include the following compounds.

3,3,3-trifluoropropyltrimethoxysilane,
3,3,3-trifluoropropyltriethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyltrimethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyltriethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltrimethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltriethoxysilane and the like.

The low refractive index layer can be composed of a cured product of a thermosetting fluorine-containing compound or an active energy ray-curable fluorine-containing compound. This cured product preferably has a dynamic friction coefficient in the range of 0.03 to 0.15, and preferably has a contact angle with water in the range of 90 to 120 °. As the curable fluorine-containing compound, a polyfluoroalkyl group-containing silane compound (for example, the above-mentioned 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10) , 10-heptadecafluorodecyltriethoxysilane, etc.), and fluorine-containing polymers having a crosslinkable functional group.

The fluorine-containing polymer having a crosslinkable functional group is obtained by copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or by copolymerizing a fluorine-containing monomer and a monomer having a functional group, and then polymer. It can be produced by a method of adding a compound having a crosslinkable functional group to the functional group therein.

Examples of the fluorine-containing monomer used here include fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, and others ( Examples thereof include partially or fully fluorinated alkyl ester derivatives of (meth) acrylic acid and completely or partially fluorinated vinyl ethers.

Monomers having a crosslinkable functional group or compounds having a crosslinkable functional group include monomers having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; monomers having a carboxyl group such as acrylic acid and methacrylic acid; Examples thereof include monomers having a hydroxyl group such as hydroxyalkyl methacrylate; monomers having an alkenyl group such as allyl acrylate and allyl methacrylate; monomers having an amino group; monomers having a sulfonic acid group.

The material for forming the low refractive index layer can improve scratch resistance, and therefore includes a sol in which fine particles of inorganic compounds such as silica, alumina, titania, zirconia, and magnesium fluoride are dispersed in an alcohol solvent. It can also consist of things. The inorganic compound fine particles used for this purpose are preferably those having a smaller refractive index from the viewpoint of antireflection properties. Such inorganic compound fine particles may have voids, and silica hollow fine particles are particularly preferable. The average particle size of the hollow fine particles is preferably in the range of 5 to 2000 nm, and more preferably in the range of 20 to 100 nm. The average particle diameter here is a number average particle diameter obtained by observation with a transmission electron microscope.

(Anti-fouling layer)
The antifouling layer is provided for imparting water repellency, oil repellency, sweat resistance, antifouling properties and the like. A suitable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, and high molecular compounds thereof. As a method for forming the antifouling layer, a physical vapor deposition method, a chemical vapor deposition method, a wet coating method, or the like typified by vapor deposition or sputtering can be used depending on the material to be formed. The average thickness of the antifouling layer is usually about 1 to 50 nm, preferably 3 to 35 nm.

(Anti-glare layer)
An optical film in which an antiglare layer is laminated on a base film is called an antiglare film. That is, the antiglare film consists of a base film and an antiglare layer. The antiglare layer is a layer having a fine uneven shape on the surface, and is preferably formed using the hard coat material described above.

The antiglare layer having a fine uneven shape on the surface is 1) a method of forming a coating film containing fine particles on a base film and providing unevenness based on the fine particles, and 2) containing or not containing fine particles. After the coating film is formed on the base film, it can be formed by a method (also called an embossing method) of transferring the uneven shape by pressing against a roll having an uneven shape on the surface.

In the above method 1), an antiglare layer is formed by applying a curable resin composition containing a curable transparent resin and fine particles on a substrate film, and curing the coating layer by irradiation with light such as ultraviolet rays or heating. Can be formed. The curable transparent resin is preferably selected from materials that have high hardness (hard coat). As such a curable transparent resin, a photocurable resin such as an ultraviolet curable resin, a thermosetting resin, an electron beam curable resin, and the like can be used. However, productivity, hardness of the obtained antiglare layer, etc. From the viewpoint, a photocurable resin is preferably used. More preferred is an ultraviolet curable resin. When using a photocurable resin, the curable resin composition further includes a photopolymerization initiator.

As the photocurable resin, polyfunctional (meth) acrylate is generally used. Specific examples thereof include tri-methylolpropane di- or tri- (meth) acrylate; pentaerythritol tri- or tetra- (meth) acrylate; reaction of (meth) acrylate having at least one hydroxyl group in the molecule with diisocyanate. The product includes polyfunctional urethane (meth) acrylate and the like. These polyfunctional (meth) acrylates can be used alone or in combination of two or more as required.

Also, a mixture of polyfunctional urethane (meth) acrylate, polyol (meth) acrylate, and (meth) acrylic polymer having an alkyl group containing two or more hydroxyl groups can be used as the photocurable resin. The polyfunctional urethane (meth) acrylate constituting this photocurable resin is produced using, for example, (meth) acrylic acid and / or (meth) acrylic acid ester, polyol, and diisocyanate. Specifically, by preparing hydroxy (meth) acrylate having at least one hydroxyl group in the molecule from (meth) acrylic acid and / or (meth) acrylic acid ester and polyol, and reacting it with diisocyanate, A polyfunctional urethane (meth) acrylate can be produced. The polyfunctional urethane (meth) acrylate thus produced is also the photocurable resin itself listed above. In the production thereof, (meth) acrylic acid and / or (meth) acrylic acid ester may be used singly or in combination of two or more, respectively, and polyol and diisocyanate are similarly used. One type may be used, or two or more types may be used in combination.

(Meth) acrylic acid ester which is one raw material of polyfunctional urethane (meth) acrylate can be a linear or cyclic alkyl ester of (meth) acrylic acid. Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, alkyl (meth) acrylate such as butyl (meth) acrylate, and cyclohexyl (meth). Examples include cycloalkyl (meth) acrylates such as acrylates.

Polyol, which is another raw material for polyfunctional urethane (meth) acrylate, is a compound having at least two hydroxyl groups in the molecule. For example, ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9- Nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol ester of hydroxypivalic acid, cyclohexanedimethylol, , 4-cyclohexanediol, spiroglycol, tricyclodecane dimethylol, hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene oxide-added bisphenol A, trimethylol ethane, trimethylol propylene , Glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, can be exemplified dipentaerythritol, tripentaerythritol, and the like glucose compound.

Diisocyanate, which is yet another raw material of polyfunctional urethane (meth) acrylate, is a compound having two isocyanato groups (—NCO) in the molecule, and uses various aromatic, aliphatic or alicyclic diisocyanates. be able to. Specific examples include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3′-dimethyl-4,4 ′. -Diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and of these, a nuclear hydrogenated diisocyanate having an aromatic ring.

The polyol (meth) acrylate constituting the above-described photocurable resin together with the polyfunctional urethane (meth) acrylate is a (meth) acrylate of a compound having at least two hydroxyl groups in the molecule (that is, polyol). Specific examples thereof include pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. Etc. A polyol (meth) acrylate may be used individually by 1 type, and may use 2 or more types together. The polyol (meth) acrylate preferably comprises pentaerythritol triacrylate and / or pentaerythritol tetraacrylate.

Furthermore, the (meth) acrylic polymer having an alkyl group containing two or more hydroxyl groups, which constitutes a photocurable resin together with these polyfunctional urethane (meth) acrylates and polyol (meth) acrylates, has hydroxyl groups in one constituent unit. It has an alkyl group containing 2 or more. Examples thereof include a polymer containing 2,3-dihydroxypropyl (meth) acrylate as a constituent unit, and a polymer containing 2-hydroxyethyl (meth) acrylate as a constituent unit together with 2,3-dihydroxypropyl (meth) acrylate. .

As described above, by using a (meth) acrylic photocurable resin as exemplified, adhesion to the base film is improved, mechanical strength is improved, and surface scratches can be effectively prevented. An antiglare film can be obtained.

As the fine particles, those having an average particle size of 0.5 to 5 μm and a refractive index difference from the curable transparent resin after curing of 0.02 to 0.2 are preferably used. By using fine particles having an average particle diameter and a refractive index difference within these ranges, haze can be effectively expressed. The average particle diameter of the fine particles can be obtained by a dynamic light scattering method or the like. The average particle diameter in this case is a weight average particle diameter.

The fine particles can be organic fine particles or inorganic fine particles. As the organic fine particles, resin particles are generally used. For example, crosslinked poly (meth) acrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, polyimide particles. Etc. As the inorganic fine particles, silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate and the like can be used.

As the photopolymerization initiator, various types such as acetophenone series, benzophenone series, benzoin ether series, amine series, and phosphine oxide series can be used. Examples of compounds classified as acetophenone photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone (also known as benzyldimethyl ketal), 2,2-diethoxyacetophenone, 1- (4-isopropylphenyl) There are -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino-1- (4-methylthiophenyl) propan-1-one, and the like. Examples of compounds classified as benzophenone photopolymerization initiators include benzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, and the like. Examples of compounds classified as benzoin ether photopolymerization initiators include benzoin methyl ether and benzoin propyl ether. Examples of compounds classified as amine photopolymerization initiators include N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone (also known as Michler's ketone). Examples of phosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide. In addition, xanthone compounds and thioxant compounds can also be used as photopolymerization initiators.

These photopolymerization initiators are commercially available. Examples of typical commercial products are "Irgacure 907" and "Irgacure 184" sold by Swiss Ciba, and "Lucirin TPO" sold by BASF Germany. is there.

The curable resin composition can contain a solvent as needed. As a solvent, arbitrary organic solvents which can melt | dissolve each component which comprises curable resin composition, such as ethyl acetate and butyl acetate, for example can be used. Two or more organic solvents can be mixed and used.

Moreover, the curable resin composition may contain a leveling agent, and examples thereof include a fluorine-based or silicone-based leveling agent. Examples of silicone leveling agents include reactive silicone, polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane. Among the silicone leveling agents, preferred are reactive silicone and siloxane leveling agents. When a leveling agent made of reactive silicone is used, slipperiness is imparted to the surface of the antiglare layer, and excellent scratch resistance can be maintained for a long period of time. Further, if a siloxane leveling agent is used, film formability can be improved.

On the other hand, in the case of forming an antiglare layer having a fine surface uneven shape by the above method 2) (embossing method), a mold having a fine uneven shape is used and the shape of the mold is set on the base film. It may be transferred to the resin layer formed in the above. In the case of forming a fine surface uneven shape by the embossing method, the resin layer to which the uneven shape is transferred may or may not contain fine particles. The resin constituting the resin layer is preferably a photocurable resin as exemplified in the method 1), and more preferably an ultraviolet curable resin. However, a visible light curable resin that can be cured with visible light having a wavelength longer than that of ultraviolet rays can be used by appropriately selecting a photopolymerization initiator instead of the ultraviolet curable resin.

In the embossing method, a curable resin composition containing a photo-curable resin such as an ultraviolet curable resin is applied on a base film, and the applied layer is cured while being pressed against an uneven surface of the mold. The uneven surface is transferred to the coating layer. More specifically, in a state where the curable resin composition is applied onto the base film and the coating layer is in close contact with the uneven surface of the mold, the coating layer is irradiated with light such as ultraviolet rays from the base film side. Next, the uneven shape of the mold is transferred to the antiglare layer by peeling the optical film having the cured coating layer (antiglare layer) from the mold.

The thickness of the antiglare layer is not particularly limited, but is generally 2 to 30 μm, preferably 3 μm or more, and preferably 20 μm or less. If the antiglare layer is too thin, sufficient hardness cannot be obtained, and the surface tends to be easily scratched. On the other hand, if it is too thick, the film is prone to cracking, or the film is curled due to curing shrinkage of the antiglare layer. Tend to decrease.

The haze value of the antiglare film is preferably in the range of 1 to 50%. If the haze value is too small, sufficient antiglare performance cannot be obtained, and external light is likely to be reflected on the screen when applied to an image display device. On the other hand, if the haze value is too large, the reflection of external light can be reduced, but the black display screen is reduced. The haze value is a ratio of the diffuse transmittance to the total light transmittance, and is measured according to JIS K 7136: 2000 “How to determine haze of plastic-transparent material”.

When the coating layer is provided on the optical film as described above, the coating width of the coating layer may be the entire width of the optical film, or uncoated portions may be provided at both ends in the width direction. The width of the uncoated part at each end can be about 0.05 to 20% of the total film width. If the width of the uncoated portion is 0.05% or more, curling (ear standing) of the film end due to curing shrinkage of the coated layer can be suppressed, and film transport and film connection (paper splicing) are facilitated. On the other hand, when the width of the uncoated part is less than 0.05%, curling tends to occur at the film end, and in some cases, curling with a height of 10 mm or more from the horizontal part of the film may occur. However, even if such curling occurs, according to the present invention, it is possible to carry the film without causing film breakage or the like.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
(A) Preparation of (meth) acrylic resin film As a (meth) acrylic resin, a copolymer of methyl methacrylate / methyl acrylate (weight ratio 96/4) was prepared. As rubber elastic particles, the innermost layer is made of a hard polymer obtained by copolymerizing methyl methacrylate with a small amount of allyl methacrylate, and the intermediate layer is mainly composed of butyl acrylate. An elastic particle having a three-layer structure consisting of a soft polymer obtained by copolymerizing allyl acid, and an outermost layer comprising a hard polymer obtained by copolymerizing a small amount of ethyl acrylate with methyl methacrylate. Acrylic elastic polymer particles having an average particle diameter of about 250 nm when not having a particle diameter were prepared.

The (meth) acrylic resin and rubber elastic particles are blended in a weight ratio of 70/30, and 0.05 parts by weight of a lubricant (stearic acid) and about 1.0 parts per 100 parts by weight in total. Pellets containing a part by weight of a benzotriazole-based ultraviolet absorber were put into a 65 mmφ single screw extruder and extruded from a T die having a set temperature of 275 ° C. Both sides of the extruded film-like molten resin are sandwiched and cooled by two polishing rolls having a mirror surface temperature set at 45 ° C., and a long (meth) acrylic resin film having a thickness of 80 μm is obtained as a film roll. It was.

(B) Production of antiglare film Antiglare comprising (meth) acrylate ultraviolet curable resin, photopolymerization initiator, resin fine particles and solvent on one side of (meth) acrylic resin film produced in (A) above. After coating and drying the layer forming coating solution, the coating layer side is irradiated with ultraviolet rays to cure the coating layer, and an antiglare layer with irregularities is formed on the surface of the (meth) acrylic resin film A long antiglare film was prepared. The obtained anti-glare film was wound around a 6 inch (about 15 cm) diameter core to form a film roll. When the haze value of the antiglare film was measured using a haze meter, it was 1.5%. The antiglare film had a thickness of 89 μm.

The Charpy impact strength of the obtained antiglare film was measured by the following procedure. First, a rectangular test piece having a width of 10 mm and a length of 82 mm was cut out from the antiglare film. As a test piece, a test piece for measuring shock absorption energy in MD, and a test piece for measuring shock absorption energy in TD, when a hammer is hit from the antiglare layer side, A total of 4 pieces were cut out, 2 pieces each for testing with the case of hitting from the opposite side. Then, both ends in the long side direction of the test piece are fixed to the support so that the test piece does not move due to impact when punched with a hammer, and according to the above measurement procedure, a Charpy impact tester (Hammer Weighing) manufactured by Yasuda Seiki Seisakusho Co., Ltd. 1.0J), the hammer is struck from the antiglare layer side so that the longitudinal direction of the blade edge is parallel to the width direction at the center in the length direction of the test piece, and the energy required for breaking the film (impact absorption energy) ) Was measured. As a result, the impact absorption energy of TD was 17 kJ / m ² , and the impact absorption energy of MD was 19 kJ / m ² . Note that the antiglare layer side impact absorption energy of the TD and MD when irradiated with a hammer from the opposite side were respectively ^{8kJ / m 2, 11kJ / m} 2. Moreover, when the antiglare film was folded in half with a finger so that the antiglare layer side was convex, the antiglare film was broken.

(C) Transport of connecting film A lead film (polyethylene terephthalate film with a thickness of 38 μm) is connected to the end of the antiglare film prepared in (B) above in the longitudinal direction, and a film made of polytetrafluoroethylene with a thickness of 60 μm is used as a base material. The connecting film formed by using the single-sided adhesive tape is continuously conveyed using the rotational driving force of the suction roll at a conveying speed of 1 to 40 m / min through the conveying path including the suction roll. . A suction roll having a diameter of 300 mm and a suction hole diameter of 3 mm was used. The suction pressure of the suction roll is 5 to 25 kPa, and the angle θ (see FIG. 1) formed by the transport direction immediately before the film passes through the suction roll and the transport direction immediately after passing through the suction roll is 90 ° or more. The tension was adjusted in the range of 70 to 500 N / m. Even when the connecting portion passed through the suction roll, the connecting film was not cracked, cracked or broken, and the connecting film could be continuously conveyed without any problem.

<Comparative Example 1>
When the connecting film was continuously transported in the same manner as in (C) of Example 1 except that the connecting film was passed through a transport path including a nip roll made of a rubber roll instead of a suction roll, the connecting portion passed through the nip roll. When this occurs, the connecting portion breaks.

<Example 2>
An optical film was prepared in which a hard coat layer having a thickness of 4 μm was laminated on a triacetyl cellulose having a thickness of 25 μm. About this optical film, Charpy impact strength was measured by the same measuring method as above. As a result, the impact absorption energy of TD and MD when irradiated with a hammer from the hard coat layer side, were respectively ^{145kJ / m 2, 138kJ / m} 2. Note that the hard coat layer side impact absorption energy of the TD and MD when irradiated with a hammer from the opposite side were respectively ^{186kJ / m 2, 134kJ / m} 2. Further, when the optical film was folded in half with a finger so that the hard coat layer side was convex, the optical film was broken.

The connected film was continuously conveyed in the same manner as in Example 1 except that this optical film was used. Even when the connecting portion passed through the suction roll, the connecting film was not cracked, cracked or broken, and the connecting film could be continuously conveyed without any problem.

<Comparative example 2>
The connection film was continuously conveyed in the same manner as in Example 2 except that the connection film was passed through a conveyance path including a nip roll made of a rubber roll instead of the suction roll. When the connection portion passed through the nip roll, the connection film was connected. The part broke.

<Reference Example 1>
About the (meth) acrylic-type resin film produced by (A) of the said Example 1, the Charpy impact strength was measured with the same measuring method as the above. As a result, the same results were obtained when the hammer was hit from one side of the film and when hit from the other side, and the impact absorption energy of TD and MD were 228 kJ / m ² and 214 kJ /, respectively. m ² . Moreover, even if this film was folded in half with a finger, the film did not break.

Except for using this (meth) acrylic resin film, the connection film was continuously conveyed in the same manner as in Comparative Example 1, and the connection film (including the connection part was included), including when the connection part passed through the nip roll. .) Was not cracked, cracked or broken.

<Reference Example 2>
The Charpy impact strength of the triacetyl cellulose film having a thickness of 25 μm was measured by the same measurement method as above. As a result, the same results were obtained when the hammer was hit from one side of the film and when hit from the other side, and the impact absorption energy of TD and MD was 588 kJ / m ² , 455 kJ / respectively. m ² . Moreover, even if this film was folded in half with a finger, the film did not break.

When the connection film was continuously conveyed in the same manner as in Comparative Example 1 except that this triacetylcellulose film was used, the connection film (including the connection part) was included even when the connection part passed through the nip roll. No cracks, cracks or breaks occurred.

<Reference Example 3>
For a polyethylene terephthalate film having a thickness of 38 μm, Charpy impact strength was measured by the same measurement method as above. As a result, the same result was obtained when the hammer was hit from one side of the film and when the hammer was hit from the other side. For both TD and MD, the impact absorption energy was the upper limit that can be measured ( 2593 kJ / m ² ). Moreover, even if this film was folded in half with a finger, the film did not break.

Except for using this polyethylene terephthalate film, the connection film was continuously conveyed in the same manner as in Comparative Example 1, and the connection film (including the connection part) was cracked even when the connection part passed through the nip roll. No cracks or breaks occurred.

<Reference Example 4>
For a polypropylene film having a thickness of 60 μm, Charpy impact strength was measured by the same measurement method as above. As a result, the same result was obtained when the hammer was hit from one side of the film and when the hammer was hit from the other side. For both TD and MD, the impact absorption energy was the upper limit that can be measured ( 1642 kJ / m ² ). Moreover, even if this film was folded in half with a finger, the film did not break.

When the connection film was continuously conveyed in the same manner as in Comparative Example 1 except that this polypropylene film was used, the connection film cracked into the connection film (including the connection part), including when the connection part passed through the nip roll. Cracks and fractures did not occur.

10 first film, 20 second film, 30 connecting tape, 40 suction roll, 50 feeding device, 60 guide roll.

Claims (9)

1. A method of continuously transporting a connecting film including a first film and a second film connected to a longitudinal end thereof by the one or more driving rolls along a transport path including one or more driving rolls. ,
   At least one of the first film and the second film is an optical film having a Charpy impact strength of less than 200 kJ / m ² ,
   The conveying method, wherein the one or more drive rolls are all suction rolls.
2. 2. The transport method according to claim 1, wherein one of the first film and the second film is the optical film, and the other is a lead film having a Charpy impact strength of 200 kJ / m ² or more.
3. Both the first film and the second film are the optical films,
   The transport method according to claim 1, wherein the first film and the second film are the same type of optical film.
4. At least the second film is the optical film,
   The conveying method according to any one of claims 1 to 3, wherein the connection film further includes a third film connected to a longitudinal end of the second film.
5. The transport method according to any one of claims 1 to 4, wherein the optical film includes a base film and a coating layer laminated thereon.
6. Producing an optical film having a Charpy impact strength of less than 200 kJ / m ² ;
   A step of continuously transporting the first film and a connecting film including the second film connected to the longitudinal end thereof by the one or more drive rolls along a transport path including one or more drive rolls;
   Including
   At least one of the first film and the second film is the optical film,
   The method for producing an optical film, wherein the one or more drive rolls are all suction rolls.
7. The manufacturing method according to claim 6, wherein the optical film is selected from the group consisting of a single-layer optical film, a multilayer optical film, a stretched optical film, and an optical film having a coating layer.
8. Producing a second optical film from the first optical film;
   A step of continuously transporting the first film and a connecting film including the second film connected to the longitudinal end thereof by the one or more drive rolls along a transport path including one or more drive rolls;
   Including
   At least one of the first film and the second film has the Charpy impact strength of less than 200 kJ / m ² or the first optical film or Charpy impact strength of less than 200 kJ / m ² or the second optical film. A film,
   The method for producing an optical film, wherein the one or more drive rolls are all suction rolls.
9. The manufacturing method according to claim 8, wherein the second optical film is selected from the group consisting of a single-layer optical film, a multilayer optical film, a stretched optical film, and an optical film having a coating layer.

Images