CN112574442A

CN112574442A - Film roll and method for producing same

Info

Publication number: CN112574442A
Application number: CN202010999680.8A
Authority: CN
Inventors: 中江叶月; 南条崇
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2019-09-27
Filing date: 2020-09-22
Publication date: 2021-03-30
Anticipated expiration: 2040-09-22
Also published as: CN112574442B; KR20210037525A; JP2021056302A; TWI751598B; JP7427897B2; KR102444730B1; TW202114848A

Abstract

The problem of the present invention is to provide a film roll having excellent blocking resistance and roll offset resistance even in the case of a film having a low elastic modulus, and a method for producing the same. The film roll of the present invention is a film roll having knurled sections at least at both ends in the width direction of the film, wherein the knurled sections are defined as a section a, a section on the back side of the film facing the section a is defined as a section B, and the film surface other than the sections a and B, on which knurling has not been performed, is defined as a surface C, and the static friction coefficients of the sections a and B are defined as a and B, respectively, and satisfies the following relational expressions (1) and (2): the static friction coefficient between the surfaces C of formula (1) < the static friction coefficient between the site a and the site B; formula (2) a < b.

Description

Film roll and method for producing same

Technical Field

The present invention relates to a film roll and a method for producing the same, and more particularly, to a film roll having excellent blocking resistance and roll offset resistance even in the case of a film having a low elastic modulus, and a method for producing the same.

Background

In general, a liquid crystal display device includes various films containing a thermoplastic resin (hereinafter, also referred to as a thermoplastic resin film).

In general, the film used for the polarizing plate is supplied as a roll of a long and wide film, a so-called film roll. In such a film roll, film blocking may occur due to film thickness unevenness, or roll shifting may occur due to impact or the like.

As means for solving such a problem, for example, patent document 1 discloses: a technique of attaching a film called a protective film to an optical film to prevent blocking of the optical film and to increase an apparent thickness to prevent roll shifting. However, in this technique, when a step of bonding the protective film and the optical film is used, a step of peeling is required, and productivity is not high.

Therefore, as another means for preventing blocking and roll shifting with good productivity, for example, patent document 2 discloses: the film end is knurled and then wound up to obtain a film roll in which blocking and roll shifting are prevented.

However, in recent years, films used for polarizing plates are required to have a large area and a thin film. In addition, it is desired to protect a protective film of a polarizing plate, a retardation film for adjusting retardation, and the like from changing physical properties and optical properties due to changes in environment, and conventionally, a fiber material such as cellulose triacetate (generically called TAC) has been mainly used, but a film containing a material excellent in water resistance such as a cycloolefin resin or an acrylic resin has been used as the protective film or the retardation film. Further, although it is strongly required to make the film thin and make the polarizing plate thin, a film having a low elastic modulus containing the cycloolefin resin or the acrylic resin is required to have a low winding tension, and as a result, the film tends to be soft-wound and tends to be easily subjected to roll misalignment.

In such a case, a technique that is extremely difficult is required to form a film having a wide width and a long film roll used in a liquid crystal display device, and the problem of blocking or roll shifting may not be solved only by the knurling process.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2019-61031

Patent document 2: japanese patent No. 5266611

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide a film roll having excellent blocking resistance and roll offset resistance even in the case of a film having a low elastic modulus, and a method for producing the same.

Means for solving the problems

In order to solve the above problems, the present inventors have found that, in the course of examining the causes of the problems and the like: a film roll having excellent blocking resistance and roll offset resistance even when a film having a low elastic modulus is obtained by controlling the static friction coefficient of at least the knurled portions at both ends of the film and the portions of the back surface of the film facing the knurled portions, thereby increasing the frictional force of the knurled portions where the films are in contact with each other when the film roll is produced, and thereby suppressing the occurrence of blocking and roll offset.

That is, the above-described problem of the present invention is solved by the following means.

1. A film roll having a knurled portion at least at both ends in the width direction of the film,

the knurled section is defined as a region A, a region on the back side of the film facing the region A is defined as a region B, and a film surface other than the region A and the region B on which knurling was not performed is defined as a surface C,

when the static friction coefficients of the portion A and the portion B are respectively set as a and B,

satisfies the following relational expressions (1) and (2),

the coefficient of static friction between the surfaces C of formula (1) < coefficient of static friction between the site A and the site B

Formula (2) a < b.

2. The film roll according to item 1, wherein a and b satisfy the following relational expression (3),

formula (3)0.3< a/b < 0.8.

3. The film roll according to claim 1 or 2, wherein the width of the film is in the range of 1.3 to 3.0 m.

4. The film roll according to any one of items 1 to 3, wherein the film has a film thickness in a range of 10 to 45 μm.

5. The film roll according to any one of items 1 to 4, wherein the film contains a cycloolefin-based resin or an acrylic resin.

6. A method for producing a film roll according to any one of items 1 to 5, comprising a step of performing a surface modification treatment on at least the site A or the site B.

7. The method of manufacturing a film roll according to item 6, wherein the surface modification treatment is performed only at the site B.

8. The method of manufacturing a film roll according to item 6, wherein the surface modification treatment is performed at both the site a and the site B.

9. The method of manufacturing a film roll according to any one of items 6 to 8, wherein the knurled portion is formed by laser knurling.

ADVANTAGEOUS EFFECTS OF INVENTION

The means of the present invention can provide a film roll having excellent blocking resistance and roll offset resistance even in the case of a film having a low elastic modulus, and a method for producing the same.

The mechanism of expression or action of the effect of the present invention is not clearly understood, but is presumed as follows.

As a result of intensive studies for solving the above-mentioned problems, the present invention has been made in view of the above-mentioned problems, and has as a result that the frictional force of a knurled portion, in which films are in contact with each other when a film roll is produced, can be made higher than the film surface C by controlling the static friction coefficients of a portion of the film, specifically, a knurled portion (portion a) at both end portions, a portion (portion B) on the back side of the film facing the knurled portion, and a film surface (surface C) other than the portion a and the portion B, on which knurling is not performed, so as to satisfy relational expressions (1) and (2). From this, it is presumed that even a film having a low elastic modulus can further suppress the occurrence of blocking and roll shifting than the means of forming only the knurled portion.

Drawings

FIG. 1: schematic view of a film roll obtained by performing knurling and surface modification treatment and winding

FIG. 2: conceptual diagram for explaining knurling processing mode

FIG. 3: schematic view showing method for manufacturing film by solution casting method

FIG. 4: outline drawing of film production line

FIG. 5: top view of a coiling device

Detailed description of the invention

The film roll of the present invention has knurled sections at least at both ends in the width direction of the film, and satisfies relational expressions (1) and (2) when the knurled sections are defined as a section a, a section on the back side of the film facing the section a as a section B, and the film surface other than the sections a and B on which knurling has not been performed is defined as a surface C, and the static friction coefficients of the sections a and B are defined as a and B, respectively. This feature is a feature common to or corresponding to the following embodiments.

In the embodiment of the present invention, in view of the effect expression of the present invention, it is preferable that a and b satisfy the relational expression (3) and prevent a roll shift of a film roll formed by further enlarging the area and thinning the film.

Further, the width of the film is preferably in the range of 1.3 to 3.0m, and the thickness of the film is preferably in the range of 10 to 45 μm, from the viewpoint of providing a film for a polarizing plate which is suitable for increasing the area and making the film thinner.

The film contains a cycloolefin resin or an acrylic resin, and is preferable from the viewpoint of suppressing changes in physical properties and optical properties due to changes in the environment of the protective film and the retardation film which protect the polarizing plate.

The method for producing a film roll of the present invention comprises a step of performing a surface modification treatment on at least a portion a of the knurled portion and a portion B which is a portion on the back side of the film opposite to the portion a.

The surface modification treatment is preferably performed only at the site B, from the viewpoint of producing a film roll with good productivity.

The surface modification treatment is performed at both the site a and the site B, and is a preferable production method from the viewpoint of further improving the static friction coefficient.

The knurling portion is formed by laser knurling, which is a preferable manufacturing method from the viewpoint of preventing film breakage when a convex portion is formed in a thermoplastic resin film of a thin film.

The present invention and its constituent elements, and specific embodiments and forms of the present invention will be described in detail below. In the present application, "to" is used in the sense of including numerical values described before and after the "to" as the lower limit value and the upper limit value.

Outline of film roll of the present invention

The film roll of the invention is a film roll having knurling processing parts at least at two ends of the film in the width direction, the knurling processing parts are a part A, a part on the film back side opposite to the part A is a part B, the film surface which is not knurled except the part A and the part B is a surface C, and the static friction coefficients of the part A and the part B are respectively a and B, the film roll satisfies the following relational expressions (1) and (2),

Formula (2) a < b

The present invention is characterized in that the static friction coefficient of a part of the film, specifically, a knurled section a at both ends, a section B on the back surface of the film facing the knurled section, and a film surface C other than the section a and the section B, which is not knurled, is controlled so as to satisfy the relational expressions (1) and (2), and the frictional force of the knurled sections where the films are brought into contact with each other when the film is wound is higher than the film surface C, thereby suppressing the occurrence of blocking and roll shifting.

In the present invention, in order to control the static friction coefficient, it is preferable to perform a surface modification treatment at least at a portion a of the knurled portion or a portion B which is a portion on the back side of the film facing the portion a. The surface modification treatment used here imparts the static friction coefficient to each of the site a and the site B so as to satisfy the relational expressions (1) and (2).

In general, "surface modification treatment" is known as a technique of providing a film for improving adhesion between a coating material and the film before coating, for example, or providing a functional layer for improving adhesion between functional layers when the functional layers are laminated. However, when this technique is applied to the production of a film roll, the film surfaces are likely to adhere to each other, and blocking or the like occurs, and thus it is difficult to directly use this technique in the production of a film roll.

In the present invention, the surface modification treatment is not performed on the film surface C except for the portion a of the knurled portion and the portion B which is the portion on the back side of the film facing the portion a, and the adhesiveness to the surface C which is the main portion of the film is not affected, and the "blocking due to adhesion" can be avoided.

In general, it is known that the frictional force of a film depends on the actual contact area and the cohesive force (bonding force) of objects to each other, and on how much the film is in contact with the objects when in contact therewith. The knurls have a convex shape, but the area of the convex is usually 5% or less of the film surface, so the actual contact area is small. Therefore, the friction force is known to be lower than the film surface C.

In the present invention, it is preferable to perform a surface modification treatment in order to increase the static friction coefficient at least at the portion a of the knurled portion or at the portion B which is a portion on the back side of the film facing the portion a. By this surface modification treatment, the cohesive force (binding force) is made higher than the other film surface C, and the friction force at the knurled portion of the film roll can be increased, and as a result, a film roll in which blocking and roll shifting are less likely to occur is formed.

The "coefficient of static FRICTION" of the present invention is measured, for example, by a static FRICTION measuring device (FRICTION TESTER TR, Toyo Seiki Seisaku-Sho Ltd.).

In the relational expression (1) of the present invention, the static friction coefficient between the surfaces C and the static friction coefficient between the site a and the site B are measured by the following method.

The measurement conditions were as follows: the film (knurled part (part A), part (part B) on the back side of the film opposite to the part A, and non-knurled part (surface C)) was used, and the parts were superposed and passed under a load of 0.166g/mm²、0.83g/mm²And 1.66g/mm²The coefficient of static friction between the surfaces C and between the areas A and B was determined. The value was set as the average of the static friction coefficients under the 3 loads.

In relation to the relational expression (2), when the static friction coefficient between the knurled sections (sections a) is represented by a and the static friction coefficient between the sections (sections B) on the back surface side of the film, which face the sections a, is represented by B, the relationships a and B are measured. By making the static friction coefficient B of the portion B higher than the static friction coefficient a of the portion a, an improvement in the friction force can be expected.

The relationship between a and b further satisfies the following relational expression (3), and is preferable from the viewpoint of preventing the roll shift of the film roll obtained by further enlarging the area and thinning the film.

Formula (3)0.3< a/b <0.8

In the formula (3), if the value is more than 0.3, the friction coefficient a of the knurled portion increases, and the roll displacement is less likely to occur. This is because when the difference between the friction coefficients of the portion a and the portion B is large, the difference is easily affected by a surface having a small friction coefficient, and the difference between the friction coefficients of the portion a and the portion B does not become excessively large by adjusting the value of the friction coefficient a of the portion a, and the roll misalignment is less likely to occur.

When the amount is less than 0.8, the friction coefficient B of the portion B on the back side of the film facing the portion a is not excessively small, and the effect of improving the blocking resistance is easily maintained by suppressing the blocking at the periphery of the knurled portion.

[ 1] knurling section

The knurled portion of the present invention means a portion having knurls at least both ends in the width direction of the film. The film can be divided into: a portion A as the knurled portion, a portion B as a portion on the back side of the film facing the portion A, and a surface C as a surface of the film other than the portion A and the portion B on which knurling processing is not performed.

Here, the "opposed portion" refers to a portion located at a position symmetrical to the portion a through the film on the back surface side of the film when the knurled portion on the front surface side of the film is the portion a.

< knurling processing >

Fig. 1 is a schematic cross-sectional view of a film roll obtained by knurling, preferably, performing a surface modifying treatment, and winding the film roll.

In fig. 1(a), the film 1 obtained by film formation is wound up by a Near roll 2 and a touch roll 3 and taken up as a film roll 10. The portion a is a knurled portion, and is knurled by a knurling means not shown. The portion B is a portion on the back side of the film facing the portion a, and in the case of (a), it is preferable to perform surface modification treatment for controlling the static friction coefficient.

The region B is preferably in the range of 50 to 120% of the knurled width of the knurled section (region A), and is subjected to a surface modification treatment for controlling the static friction coefficient. More preferably 80 to 120%, still more preferably 90 to 110%, and particularly preferably 100 to 110%.

When the width of the portion B subjected to the surface modification treatment is 50% or more with respect to the width of the knurled portion (portion a), the effect of the present invention can be effectively exhibited, and when the width is within 120%, the effect of the present invention can be exhibited in the case where there is production unevenness.

Fig. 1(B) is a perspective view showing a film roll having a knurled portion a and a portion B which is a portion on the back side of the film facing the portion a.

The film roll 10 of the present invention is a film roll having knurled portions (portions a) at least at both ends in the film width direction, and preferably, surface modification treatment is performed at least at the knurled portions (portions a) and at a portion (portion B) on the film back side opposite thereto in order to control the static friction coefficient. Therefore, as an embodiment of the present invention, there are: (1) a mode of applying surface modification treatment only to the knurled part (part A); (2) a mode of applying surface modification treatment to only a part (part B) on the back side of the film opposite to the knurling processing part (part A); and (3) a mode of applying surface modification treatment to both the knurled part (part a) and the part (part B) on the back side of the film opposite to the knurled part.

Here, the term "knurling processing" means "embossing processing in which a concave-convex portion is formed on a film surface". Conventionally, there are a variety of knurling means, but these are roughly classified into the following two types: a "heating and pressing manner" in which pressing is performed while heating a metal roller (also referred to as an engraved ring) having a convex shape; and a "laser system" in which a film is heated and deformed by selectively applying a wavelength absorbed by the film with a laser or the like. In the "heating and pressing method", the shape of the convex portion is changed by changing the material of a counter roll (generally called a back roll).

Fig. 2 is a conceptual diagram illustrating various knurling processing modes.

Fig. 2(a) is a schematic view showing a "heating and pressing method" in which a metal roller is heated and pressed by embossing rings 4 having a convex shape formed on the metal roller, and in some cases, the rear roller is a metal roller 5. By using a metal back roll, the stress generated when the engraved ring 4 is pressed into the film 1 forms a convex portion (knurling) 8 in a shape as shown in fig. 2(b) toward the inside of the film and the periphery of the engraved ring.

The "knurled portion" in the present invention means a portion to which the above-described convex portion shape is imparted (formed).

The heating temperature is preferably selected from a temperature range of not lower than the glass transition temperature and not higher than the melting point of the thermoplastic resin.

The engraved ring 4 is made of carbon steel, stainless steel, ceramic coating, HCr plating, or the like, and is not particularly limited, and the width of the projection forming portion is about 5 to 30mm, and the pitch of the projections in the width direction and the length direction is about 0.5 to 5mm and the height of the projections is about 0.3 to 3mm in the shape of the stamp.

Fig. 2(c) shows the "heating and pressing method", but the rear roller may be the rubber roller 6. By using rubber as the rear roller, the convex portion (knurling) 8 is formed on the back surface side of the film in the shape as shown in fig. 2(d) toward the rubber roller side by the stress generated when the engraved ring 4 is pressed into the film 1.

Fig. 2(e) shows the "laser method", in which the film at the portion irradiated with the laser beam 7 is thermally deformed to form a convex portion (knurling) 8 in the shape shown in fig. 2 (f).

The knurling of the present invention is preferably performed by a laser method from the viewpoints of ease of molding, prevention of breakage, and the like.

In the laser method, when a thermoplastic resin film is irradiated with a laser, the thermoplastic resin film is locally thermally melted or ablated at a spot where the laser is irradiated. Therefore, a dimple is formed at the spot where the laser is irradiated, and the dimple becomes the center portion of the convex portion. In addition, a part or the whole of the material of the thermoplastic resin film thermally melted by the irradiation of the laser light is fluidized, and a protrusion portion which becomes a peripheral portion of the convex portion is formed around the spot irradiated with the laser light. When the convex portion is formed by the laser beam in this way, even in a thermoplastic resin film having a small thickness, the thermoplastic resin film can be prevented from being broken when the convex portion is formed. Further, even if the thermoplastic resin film is bent, the convex portion is less likely to be broken. This is presumably because, for example, in the case where the convex portion is formed by laser light, unnecessary pressing is not applied to the thermoplastic resin film, and residual stress is less likely to remain in the thermoplastic resin film, as compared with the case of the embossing treatment.

In the present invention, the laser method is preferably used, but although the convex portion is formed stably by the laser method, the friction tends to be low because the convex portion is formed in a small area. However, by using the surface modification treatment of the present invention, it is possible to obtain a film roll having high rib bursting resistance and roll offset resistance by increasing the frictional force of the knurled portion while maintaining a stable convex portion. Here, "rib (gauge band)" also means "black band" and refers to a portion where the thickness of the film becomes thick due to unevenness of the film thickness and adhesion of the films to each other when the film roll is produced, and a part of the rolled film roll looks dark visually.

In the case where the embossed structure including the convex portions is provided to both ends of the film in the width direction to improve the handling properties of the film, the width of the embossed structure region is preferably 2mm or more, more preferably 4mm or more, particularly preferably 5mm or more, and preferably 100mm or less, more preferably 80mm or less, and particularly preferably 60mm or less.

The height H (mum) of the knurled section is preferably in the range of 0.05 to 0.3 times the film thickness H, and the width W is preferably in the range of 0.005 to 0.02 times the film width L.

In this case, the height of the knurled section is preferably 1.5 to 30 μm, more preferably 2 to 20 μm, on average, from the film surface.

Further, the knurled portions may be formed on both surfaces of the film. In this case, the height H1+ H2(μm) of the knurled sections on both sides is preferably in the range of 0.05 to 0.3 times the film thickness H, and the width W is preferably in the range of 0.005 to 0.02 times the film width L. For example, when the film thickness is 40 μm, the height h1+ h2(μm) of the knurled section is preferably in the range of 2 to 12 μm, and the width of the knurled section is preferably in the range of 5 to 30 mm.

The shape of the uneven structure and the arrangement thereof in the uneven structure region may be any shape and arrangement according to the purpose of use. By controlling the trajectory of the laser beam applied to the film surface, the concave-convex structure having a desired shape can be drawn by the laser beam. Examples of the shape (shape when viewed from a direction perpendicular to the film surface) of each uneven structure include a dot shape, a linear shape, a circular shape, an elliptical shape, a polygonal shape, and the like. The arrangement of the concave-convex structure may be, for example: a certain regular arrangement along the length and width directions of the film; or a random configuration.

As the laser device used in the present invention, various types of devices used in processing of a film can be used. Examples of the laser device used include: ArF excimer laser device, KrF excimer laser device, XeCl excimer laser device, YAG laser device (especially third harmonic wave or fourth harmonic wave), YLF or YVO₄A solid-state laser device (particularly, a third harmonic wave or a fourth harmonic wave), a Ti: S laser device, a semiconductor laser device, a fiber laser device, and a carbon dioxide gas laser device. Among these laser devices, a carbon dioxide gas laser device is preferable from the viewpoint of efficiently obtaining a relatively low cost and an output suitable for film processing.

The center wavelength of the wavelength range of the laser light in the laser irradiation is not particularly limited, and may be any wavelength used for processing a film. For example, a laser having a center wavelength of any value in the range of 9 to 12 μm can be used. In particular, when a carbon dioxide gas laser device is used as the laser device, a laser beam having a wavelength of about 10.6 μm (for example, 10.5 to 10.7 μm) as a center wavelength and a laser beam having a wavelength of about 9.3 μm (for example, 9.2 to 9.4 μm) as a center wavelength can be used, and particularly when a laser beam having a wavelength of 9.3 μm is used, the formation of the knurls of the film containing the hydrocarbon-containing polymer can be particularly favorably performed.

The output of the laser beam is preferably 1W or more, more preferably 5W or more, further preferably 15W or more, preferably 120W or less, more preferably 100W or less, further preferably 80W or less, and further preferably 70W or less.

By knurling using a laser method, a film having an uneven structure with little height variation can be manufactured. The height of the uneven structure is a height difference between the highest portion of the uneven structure formed on the surface of the film and the surface of the film. The height of the uneven structure can be measured using an interference type surface shape measuring apparatus ("new view 7200" manufactured by ZYGO corporation). For example, when the film is wound as a roll, the height variation of the uneven structure is preferably ± 20% or less, and more preferably ± 15% or less. By setting the height variation of the uneven structure to such a low value, the occurrence of scratches and blocking due to friction between films in a film roll can be effectively reduced.

< preferred example of knurling Using laser System >

Carbon dioxide gas laser apparatus: the output of the laser device was 20W, the center wavelength of the emission wavelength was 10.59 μm, and the emission wavelength range was adjusted to. + -. 0.01 μm or less around the center wavelength.

Formation of knurled portions: the widths of the concave and convex regions were 15mm, respectively, and the linear velocity of the transport film was adjusted to 10 m/min.

Irradiating the film with laser light by: the collimated beam emitted from the carbon dioxide gas laser device was reflected by a 2-piece galvanometer mirror, and focused on the surface of the transported film via an f θ lens (focal length 200 mm). The focal position is moved in the film plane direction by controlling the angle of the galvanometer mirror, thereby controlling the locus of irradiating the laser light on the film surface.

The trajectory of the laser light irradiation is controlled so as to draw a plurality of circles in the concave-convex area on the film surface, thereby forming a concave-convex structure having a shape corresponding to a circle. The diameter of each circle was set to 2.5mm, and the circles were arranged so as to form 5 rows extending in the film longitudinal direction in the concave-convex region having a width of 15 mm. The laser irradiation allows the speed of forming the uneven structure to be adjusted, and the uneven structure having a height of about 10 μm is formed as the knurled portion of the present invention.

< surface modification treatment >

In the present invention, it is preferable that at least a portion a which is a knurled portion or a portion B which is a portion on the back side of the film facing the portion a be subjected to a surface modifying treatment to control the static friction coefficient.

The surface modification treatment of the present invention is to activate the energy of the film surface, so-called surface energy. If the activation can be carried out, an effect can be expected, and in the case of plasma treatment or corona treatment, for example, the activation can be easily carried out and the modification can be carried out only in a desired portion. For example, the surface of the film may be modified by a method such as treatment with a chemical agent or polishing. Tong (Chinese character of 'tong')By increasing the surface energy, the friction force with the film can be increased and the roll can be prevented from being deviated when the film roll is produced. In the present invention, "activation of surface energy" means that the surface is nearly hydrophilic, that is, defined as that the surface free energy is increased by 10mJ/m before and after the surface modification treatment²The above.

In the present invention, the surface modification is preferably performed by plasma treatment, and in the case of plasma treatment, it is easy to treat only a part of the film width. Further, since the energy for activating the substrate is high, the substrate can be used in a state where the treatment time is short. Since the treatment time varies depending on the film, an appropriate treatment time is set depending on the type of film.

The corona treatment can modify the surface, but is affected by charging, and therefore requires a static elimination step.

The surface modification treatment is carried out, as described above, at least in the following manner: a mode of applying surface modification treatment only to the knurled part (part A); a mode of applying surface modification treatment to only a part (part B) on the back side of the film opposite to the knurling processing part (part A); and a mode of applying surface modification treatment to both the knurled part (part A) and the part (part B) on the back side of the film opposite to the knurled part. Among them, from the viewpoint of installation and effect of the apparatus, it is preferable that: a mode of applying a surface modification treatment to only a portion (portion B) on the back side of the film; and a mode of applying surface modification treatment to both the knurled part (part A) and the part (part B) on the back side of the film opposite to the knurled part.

Specific examples of the surface modification treatment include: corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, saponification treatment, glow treatment, ozone treatment, electron beam treatment, and the like. In particular, from the viewpoint of productivity, corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, and saponification treatment are preferable, and plasma treatment is particularly preferable.

Corona treatment and plasma treatment are treatments in which the surface of a film is subjected to discharge treatment to impart functional groups (for example, carboxyl groups, hydroxyl groups, acryloyl groups, amide groups, and the like) to improve the wettability of the surface of the film. The corona treatment is usually performed under atmospheric pressure (in air), and the plasma treatment is usually performed under an atmosphere of nitrogen, helium, neon, argon, xenon, carbon dioxide, nitrous oxide, hydrogen, ammonia, or the like, but an "atmospheric pressure plasma treatment" performed under atmospheric pressure may be employed.

The "corona discharge treatment" is a method of applying a high frequency and high voltage between electrodes insulated from a dielectric to generate a corona, and passing a base material film between the dielectric and the electrodes to treat the surface of the base material film. This improves the adhesiveness of the surface of the base film. Examples of the material of the electrode include ceramics and aluminum. The distance between the electrode and the dielectric is preferably 1 to 5mm, and more preferably 1 to 3 mm.

The corona output intensity is preferably 0.2-3 kW, and more preferably 0.5-1.5 kW. It is preferable to set the corona output intensity to 0.2kW or more, from the viewpoint of facilitating stabilization of corona discharge and imparting stable adhesive force to the surface of the film. By setting the corona output intensity to 2.0kW or less, the film is less likely to be scratched. The electron irradiation amount in the corona discharge treatment can be set to 100-1000W/m²·min。

The "plasma treatment" is a treatment of activating the surface of the film by performing plasma discharge under a gas atmosphere such as an inert gas or oxygen generated under reduced pressure or atmospheric pressure. In order to efficiently perform production by conveyance using a roller, plasma treatment under atmospheric pressure is preferable.

The plasma treatment can modify the surface of the base material layer in various ways by changing the kind of gas. Therefore, when the surface of the base material layer is activated, the type of gas can be selected as appropriate. Examples of the types of gases include: nitrogen, oxygen, argon, helium, acrylic acid, hydroxyalkyl, CF₄、CHF₃C₂F₆And the like fluorine-based compounds.

The plasma output is preferably 0.2-3 kW. The linear velocity (moving velocity) is preferably 3 to 70 m/min, more preferably 3 to 50 m/min. The frequency is preferably 3 to 30kHz, and more preferably 5 to 20 kHz.

As a specific condition of the plasma treatment, an atmospheric pressure plasma jet treatment was performed by passing the film through an atmospheric pressure plasma jet apparatus using the atmospheric pressure plasma jet apparatus.

The composition of the mixed gas (reaction gas) used in the atmospheric pressure plasma treatment is shown by the following example. The air pressure was 1.013X 10⁵Pa。

Nitrogen: 99.98% by volume

Oxygen: 0.02% by volume

Flow rate of mixed gas: 2m³/min

The ultraviolet ray in the "ultraviolet treatment" generally means an electromagnetic wave having a wavelength of 10 to 400nm, but in the case of the ultraviolet irradiation treatment, it is preferable to use an ultraviolet ray of 210 to 375 nm.

The irradiation with ultraviolet rays is preferably performed in such a manner that the irradiated film is not damaged, and the irradiation intensity and the irradiation time are set.

The ultraviolet irradiation can be suitably used for batch processing or continuous processing, and can be suitably selected depending on the shape of the substrate or support to be used. For example, UV ozone cleaner UV-1 manufactured by SAMCO, ultraviolet baking furnace manufactured by EYEGRAPHICS, and the like can be used. The time required for the ultraviolet irradiation also depends on the composition and concentration of the substrate or the barrier layer to be used, and is usually 0.1 second to 60 minutes, preferably 0.5 second to 30 minutes.

The "saponification treatment" is generally carried out by immersing the substrate in a sodium hydroxide solution of a certain concentration at a certain temperature for a certain period of time. For example, for the optical film of the present invention, the film is immersed in a 2mol/L sodium hydroxide solution at 60 ℃ for 90 seconds.

[ 2] film roll

The film roll in the present invention means a film wound into a roll.

[ 2.1 ] thermoplastic resin

The thermoplastic resin material used in the film of the present invention is not particularly limited as long as it can be handled as a film roll after film formation. For example, as the thermoplastic resin used for the polarizing plate, there can be suitably used: cellulose ester resins such as cellulose Triacetate (TAC), Cellulose Acetate Propionate (CAP), and cellulose Diacetate (DAC), cyclic olefin resins such as cycloolefin polymer (COP) (hereinafter also referred to as cycloolefin resins), polypropylene resins such as polypropylene (PP), acrylic resins such as polymethyl methacrylate (PMMA), and polyester resins such as polyethylene terephthalate (PET).

In particular, in a film having a low elastic modulus, for example, a resin having a low elastic modulus of less than 3.0GPa, since roll shift is likely to occur when a film roll is formed, the static friction coefficient is controlled so as to satisfy relational expressions (1) and (2) of the present invention, and thus the present invention can be effectively applied to a film roll using a cycloolefin polymer (COP) or polymethyl methacrylate (PMMA), which is a film having a low elastic modulus, as a thermoplastic resin.

Furthermore, the effect of the invention is of increased value at the thin film area. The film thickness of the thin film is preferably 5 to 80 μm, more preferably 10 to 50 μm, and still more preferably 10 to 45 μm. When the film thickness is less than 10 μm, the rigidity of the film roll is low, and it is difficult to maintain the roll shape. When the film thickness is more than 80 μm, the mass increases, and thus it is difficult to produce a long roll of film.

[ 2.1.1 ] cycloolefin resin

The cycloolefin-based resin contained in the film roll of the present invention is preferably: a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and a copolymerizable monomer other than the cycloolefin monomer.

The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton, and more preferably a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2).

[ chemical formula 1]

General formula (A-1)

In the general formula (A-1), R¹～R⁴Each independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. P represents an integer of 0 to 2. However, R¹～R⁴Not all of which represent hydrogen atoms, R¹And R²Not simultaneously representing a hydrogen atom, R³And R⁴Not simultaneously represent a hydrogen atom.

As R in the general formula (A-1)¹～R⁴The hydrocarbon group having 1 to 30 carbon atoms is preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, for example. Examples of such linking groups include: and 2-valent polar groups such as carbonyl group, imino group, ether bond, silyl ether bond, thioether bond, and the like. Examples of the hydrocarbon group having 1 to 30 carbon atoms include: methyl, ethyl, propyl, butyl and the like.

R in the general formula (A-1)¹～R⁴Examples of the polar group include: carboxyl, hydroxyl, alkoxy, alkoxycarbonyl, aryloxycarbonyl, amino, amido, and cyano. Among them, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferable, and from the viewpoint of ensuring solubility in solution film formation, an alkoxycarbonyl group and an aryloxycarbonyl group are preferable.

P in the general formula (A-1) is preferably 1 or 2 from the viewpoint of improving the heat resistance of the optical film. This is because when P is 1 or 2, the volume of the obtained polymer increases and the glass transition temperature tends to increase.

[ chemical formula 2]

General formula (A-2)

In the general formula (A-2), R⁵Represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. R⁶Represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom). P represents an integer of 0 to 2.

R in the formula (A-1)⁵Preferably a hydrocarbon group having 1 to 5 carbon atoms, more preferably 1 carbon atom-3 hydrocarbyl groups.

R in the formula (A-2)⁶The compound preferably represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, and an aryloxycarbonyl group, and more preferably an alkoxycarbonyl group and an aryloxycarbonyl group from the viewpoint of ensuring solubility in solution film formation.

P in the general formula (a-2) preferably represents 1 or 2 from the viewpoint of improving the heat resistance of the optical film. This is because when P represents 1 or 2, the volume of the obtained polymer increases and the glass transition temperature tends to increase.

The cycloolefin monomer having a structure represented by the general formula (A-2) is preferable from the viewpoint of improving solubility in an organic solvent. In general, the crystallinity of an organic compound is reduced by symmetry breaking, and thus the solubility in an organic solvent is improved. R in the formula (A-2)⁵And R⁶Since substitution is made only at a single ring-constituting carbon atom with respect to the axis of symmetry of the molecule, the symmetry of the molecule is low, that is, the cycloolefin monomer having the structure represented by the general formula (a-2) has high solubility, and thus it is suitable for the case of producing an optical film by a solution casting method.

The content ratio of the cycloolefin monomer having the structure represented by the general formula (a-2) in the polymer of the cycloolefin monomer is, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol% with respect to the total amount of all the cycloolefin monomers constituting the cycloolefin resin. When the cycloolefin monomer having the structure represented by the general formula (a-2) is contained to some extent or more, the orientation of the resin is improved, and thus the retardation (retardation) value is liable to increase.

Specific examples of the cycloolefin monomers having a structure represented by the general formula (A-1) are shown below as exemplified compounds 1 to 14, and specific examples of the cycloolefin monomers having a structure represented by the general formula (A-2) are shown below as exemplified compounds 15 to 34.

[ chemical formula 3]

Examples of the copolymerizable monomer copolymerizable with the cycloolefin monomer include: a copolymerizable monomer copolymerizable with the cycloolefin monomer by ring-opening polymerization, a copolymerizable monomer copolymerizable with the cycloolefin monomer by addition polymerization, and the like.

Examples of the ring-opening copolymerizable comonomer include: cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

Examples of the addition-copolymerizable monomer include: unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth) acrylic esters. Examples of the unsaturated double bond-containing compound include: an olefin compound having 2 to 12 carbon atoms (preferably 2 to 8 carbon atoms), examples of which include: ethylene, propylene, and butylene, and the like. Examples of the vinyl cyclic hydrocarbon monomer include: vinyl cyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of the (meth) acrylate include: alkyl (meth) acrylates having 1 to 20 carbon atoms such as methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate.

The content of the cycloolefin monomer in the copolymer comprising the cycloolefin monomer and the copolymerizable monomer is, for example, 20 to 80 mol%, preferably 30 to 70 mol%, based on the total of all monomers constituting the copolymer.

The cycloolefin resin is a polymer obtained by polymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the general formula (a-1) or (a-2), as described above, and examples thereof include the following.

(1) Ring-opened polymer of cycloolefin monomer

(2) Ring-opened copolymer of cycloolefin monomer and copolymerizable monomer ring-opening copolymerizable therewith

(3) Hydrogenation product of the Ring-opened (co) polymer of (1) or (2)

(4) The ring-opened (co) polymer (1) or (2) is cyclized by Friedel Crafts reaction and then hydrogenated to obtain a (co) polymer

(5) Saturated copolymers of cycloolefin monomers and compounds containing unsaturated double bonds

(6) Addition copolymer of cycloolefin monomer and vinyl cyclic hydrocarbon monomer and hydrogenated product thereof

(7) Alternating copolymers of cycloolefin monomers and (meth) acrylates

The polymers (1) to (7) can be obtained by known methods, for example, the methods described in Japanese patent laid-open Nos. 2008-107534 and 2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization of the above-mentioned (2) can be, for example, those described in paragraphs 0019 to 0024 of Japanese patent application laid-open No. 2008-107534. The catalysts used for the hydrogenation of (3) and (6) can be, for example, those described in paragraphs 0025 to 0028 of Japanese patent application laid-open No. 2008-107534. The acidic compound used in the Friedel Crafts reaction of (4) can be used, for example, as described in paragraph 0029 of Japanese patent application laid-open No. 2008-107534. The catalysts used in the addition polymerizations of (5) to (7) can be, for example, those described in paragraphs 0058 to 0063 of Japanese patent application laid-open No. 2005-227606. The alternating copolymerization reaction of (7) can be carried out, for example, by the method described in paragraphs 0071 and 0072 of Japanese patent laid-open publication No. 2005-227606.

Among these, the polymers (1) to (3) and (5) are preferable, and the polymers (3) and (5) are more preferable. That is, the cycloolefin resin preferably contains at least one of the structural unit represented by the following general formula (B-1) and the structural unit represented by the following general formula (B-2), more preferably contains only the structural unit represented by the general formula (B-2), or contains both the structural unit represented by the general formula (B-1) and the structural unit represented by the general formula (B-2), from the viewpoint of improving the glass transition temperature and the light transmittance of the cycloolefin resin obtained. The structural unit represented by the general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the general formula (A-1), and the structural unit represented by the general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the general formula (A-2).

[ chemical formula 4]

General formula (B-1)

In the general formula (B-1), X represents-CH ═ CH-or-CH₂CH₂-。R¹～R⁴And p is independently from R of the formula (A-1)¹～R⁴And p are synonymous.

[ chemical formula 5]

General formula (B-2)

In the general formula (B-2), X represents-CH ═ CH-or-CH₂CH₂-。R⁵～R⁶And p is independently from R of the formula (A-2)⁵～R⁶And p are synonymous.

The cycloolefin resin of the present invention may be a commercially available product. Examples of commercially available products of cycloolefin resins include: ARTON (ARTON) G (e.g., G7810, etc.), ARTON F, ARTON R (e.g., R4500, R4900, R5000, etc.), and ARTONR X manufactured by JSR (ltd.).

The intrinsic viscosity [. eta. ] inh of the cycloolefin resin is preferably 0.2 to 5cm in the measurement at 30 DEG C³A concentration of 0.3 to 3cm³A concentration of 0.4 to 1.5cm³/g。

The cycloolefin resin preferably has a number average molecular weight (Mn) of 8000 to 100000, more preferably 10000 to 80000, and further preferably 12000 to 50000. The weight average molecular weight (Mw) of the cycloolefin resin is preferably 20000 to 300000, more preferably 30000 to 250000, and further preferably 40000 to 200000. The number average molecular weight and the weight average molecular weight of the cycloolefin resin can be measured in terms of polystyrene by Gel Permeation Chromatography (GPC).

< gel permeation chromatography >

Solvent: methylene dichloride

Column: shodex K806, K805, K803G (used for 3 connections made by Showa Denko K.K.)

Column temperature: 25 deg.C

Sample concentration: 0.1% by mass

A detector: RI Model 504 (manufactured by GL SCIENCE Co., Ltd.)

A pump: l6000 (manufactured by Hitachi institute, Ltd.)

Flow rate: 1.0ml/min

And (3) correcting a curve: calibration curves prepared from 13 samples of standard polystyrene STK standard polystyrene (TOSOH, manufactured by TOSOH) having Mw ranging from 500 to 2800000 were used. The 13 samples are preferably used at approximately equal intervals.

When the intrinsic viscosity [ η ] inh, the number average molecular weight and the weight average molecular weight are within the above ranges, the cycloolefin resin is excellent in heat resistance, water resistance, chemical resistance, mechanical properties and moldability into a film.

The glass transition temperature (Tg) of the cycloolefin resin is usually 110 ℃ or higher, preferably 110 to 350 ℃, more preferably 120 to 250 ℃, and still more preferably 120 to 220 ℃. When the Tg is 110 ℃ or higher, deformation under high temperature conditions is easily suppressed. On the other hand, when Tg is 350 ℃ or less, molding becomes easy, and deterioration of the resin due to heat during molding is easily suppressed.

The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, relative to the film.

[ 2.1.2 ] acrylic resin

The acrylic resin of the present invention is a polymer of an acrylic acid ester or a methacrylic acid ester, and also includes a copolymer with another monomer.

Therefore, the acrylic resin of the present invention also includes a methacrylic resin. The resin is not particularly limited, but is preferably a resin having a methyl methacrylate unit content of 50 to 99 mass% and a monomer unit content copolymerizable therewith of 1 to 50 mass%.

Examples of other units constituting the acrylic resin formed by copolymerization include: alkyl methacrylate having an alkyl group of 2 to 18 carbon atoms, alkyl acrylate having an alkyl group of 1 to 18 carbon atoms, isobornyl methacrylate, hydroxyalkyl acrylate such as 2-hydroxyethyl acrylate, acrylamide such as acrylic acid or methacrylic acid, α, β -unsaturated acid such as acryloylmorpholine or N-hydroxyphenyl methacrylamide, 2-valent carboxylic acid having an unsaturated group such as N-vinylpyrrolidone, maleic acid, fumaric acid or itaconic acid, aromatic vinyl compound such as styrene or α -methylstyrene, α, β -unsaturated nitrile such as acrylonitrile or methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutarimide or glutaric anhydride.

As copolymerizable monomers forming the units other than glutarimide and glutaric anhydride among the units, monomers corresponding to the units are mentioned. Namely, there can be mentioned: alkyl methacrylate having an alkyl group of 2 to 18 carbon atoms, alkyl acrylate having an alkyl group of 1 to 18 carbon atoms, isobornyl methacrylate, hydroxyalkyl acrylate such as 2-hydroxyethyl acrylate, acrylamide such as α, β -unsaturated acid such as acrylic acid or methacrylic acid, acryloylmorpholine, N-hydroxyphenylmethacrylamide, unsaturated group-containing 2-valent carboxylic acid such as N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid, aromatic vinyl compound such as styrene or α -methylstyrene, α, β -unsaturated nitrile such as acrylonitrile or methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, and the like.

Furthermore, a glutarimide unit can be formed, for example, by reacting a 1-stage amine (imidizing agent) with an intermediate polymer having a (meth) acrylate unit and imidizing the reaction product (see Japanese patent application laid-open publication No. 2011-26563).

The glutaric anhydride unit can be formed, for example, by heating an intermediate polymer having a (meth) acrylate ester unit (see japanese patent No. 4961164).

The acrylic resin of the present invention particularly preferably contains, in the constituent unit, from the viewpoint of mechanical strength: isobornyl methacrylate, acryloylmorpholine, N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride or glutarimide.

The acrylic resin of the present invention has a weight average molecular weight (Mw) in the range of preferably 5 to 100 ten thousand, more preferably 10 to 100 ten thousand, and particularly preferably 20 to 80 ten thousand, from the viewpoints of controlling dimensional changes according to changes in the ambient temperature and humidity atmosphere, and improving releasability from a metal support, drying properties of an organic solvent, heat resistance, and mechanical strength during film production.

When the amount is 5 ten thousand or more, the heat resistance and mechanical strength are excellent, and when the amount is 100 ten thousand or less, the releasability from the metal support and the drying property of the organic solvent are excellent.

The method for producing the acrylic resin of the present invention is not particularly limited, and the following methods can be used: any of known methods such as suspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization. Here, as the polymerization initiator, a general peroxide-based or azo-based initiator may be used, and further, a redox-based initiator may be used. The polymerization temperature may be in the range of 30 to 100 ℃ in the case of suspension or emulsion polymerization, or in the range of 80 to 160 ℃ in the case of bulk or solution polymerization. In order to control the reduced viscosity of the obtained copolymer, polymerization may be carried out using an alkyl mercaptan or the like as a chain transfer agent.

The glass transition temperature Tg of the acrylic resin is preferably in the range of 80 to 120 ℃ from the viewpoint of maintaining the mechanical strength of the film.

As the acrylic resin of the present invention, commercially available ones can be used. Examples thereof include: DELPET60N, 80N, 980N, SR8200 (manufactured by Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88, EMB-143, EMB-159, EMB-160, EMB-161, EMB-218, EMB-229, EMB-270, and EMB-273 (manufactured by MITSUISHI RAYON Co., Ltd.), KT75, TX400S, and IPX012 (manufactured by electrochemistry Industries Co., Ltd.). It is also possible to use 2 or more kinds of acrylic resins in combination.

The acrylic resin of the present invention preferably contains an additive, and as an example of the additive, acrylic particles (rubber elastomer particles) described in international publication No. 2010/001668 are preferably contained to improve the mechanical strength of the film and to adjust the dimensional change rate. Examples of commercially available products of such multilayer-structured acrylic granular composites include: "METABLENW-341" manufactured by MITSUBISHI RAYON, "KANEACE" manufactured by KANEKA, "PARALOID" manufactured by KURE CA, "ACRYLOID" manufactured by ROHM AND HAAS, "STAFYROID" manufactured by AICA, CHEMISNOWMR-2G, MS-300X (manufactured by SOKAI CHEMICAL CO., LTD.) AND "PARAPETSA" manufactured by KURAY, AND these can be used alone or in combination of 2 or more.

The acrylic particles have a volume average particle diameter of 0.35 μm or less, preferably 0.01 to 0.35 μm, and more preferably 0.05 to 0.30 μm. When the particle size is not less than a certain value, the film is easily stretched by heating, and when the particle size is not more than a certain value, the transparency of the obtained film is not easily impaired.

The film of the present invention preferably has a flexural modulus of elasticity (JIS K7171) of 1500MPa or less from the viewpoint of flexibility. The flexural modulus is more preferably 1300MPa or less, and still more preferably 1200MPa or less. The flexural modulus varies depending on the type, amount, etc. of the acrylic resin and the rubber elastomer particles in the film, and for example, the flexural modulus generally decreases as the content of the rubber elastomer particles increases. In addition, when a copolymer of an alkyl methacrylate and an alkyl acrylate is used as the acrylic resin, the flexural modulus is generally smaller than when a homopolymer of an alkyl methacrylate is used.

[ 2.1.3 ] cellulose ester resin

In the film roll of the present invention, a cellulose ester resin is preferably used.

The cellulose ester used in the present invention is a cellulose acylate resin in which a part or all of hydrogen atoms of hydroxyl groups (-OH) at positions 2, 3 and 6 in a glucose unit bonded to β -1,4 constituting cellulose are substituted with acyl groups.

The cellulose ester to be used is not particularly limited, but is preferably an ester of a linear or branched carboxylic acid having about 2 to 22 carbon atoms. The carboxylic acid constituting the ester may be an aliphatic carboxylic acid, may form a ring, or may be an aromatic carboxylic acid. Examples thereof include: cellulose ester in which the hydrogen atom of the hydroxyl group of cellulose is substituted with an acyl group having 2 to 22 carbon atoms such as acetyl, propionyl, butyryl, isobutyryl, valeryl, tert-valeryl, hexanoyl, octanoyl, lauroyl, stearoyl, and the like. The carboxylic acid (acyl group) constituting the ester may have a substituent. The carboxylic acid constituting the ester is particularly preferably a lower fatty acid having 6 or less carbon atoms, and more preferably a lower fatty acid having 3 or less carbon atoms. The acyl group in the cellulose ester may be a single kind or a combination of plural kinds.

Specific examples of preferred cellulose esters include, in addition to cellulose acetates such as cellulose Diacetate (DAC) and cellulose Triacetate (TAC): and mixed fatty acid esters of cellulose having a propionate group or a butyrate group bonded thereto in addition to an acetyl group, such as Cellulose Acetate Propionate (CAP), cellulose acetate butyrate, and cellulose acetate propionate butyrate. These cellulose esters may be used singly or in combination of plural kinds.

(kind of acyl group. degree of substitution)

By adjusting the kind and substitution degree of acyl groups in the cellulose ester, the humidity variation of the phase difference can be controlled within a desired range, and the uniformity of the film thickness can be improved.

The smaller the degree of substitution of the acyl group in the cellulose ester, the higher the retardation expression ability, and thus the film can be made thinner. On the other hand, too small a degree of substitution with an acyl group is not preferable because there is a risk of deterioration in durability.

On the other hand, as the degree of substitution of acyl groups in cellulose ester is larger, retardation is less exhibited, and therefore, it is necessary to increase the stretching ratio in film formation. Further, since Rt humidity fluctuation, which is a phase retardation (phase difference) in the thickness direction, is generated by the coordination of water molecules to the carbonyl groups of cellulose, Rt humidity fluctuation tends to deteriorate as the degree of substitution of acyl groups increases, that is, as the number of carbonyl groups in cellulose increases.

In the cellulose ester, the total degree of substitution is preferably 2.1 to 2.5. By setting the range, the uniformity of the film thickness can be improved while suppressing environmental variation (particularly variation of Rt due to humidity). From the viewpoint of improving the casting property and the stretchability in film formation and further improving the uniformity of the film thickness, more preferably from 2.2 to 2.45.

More specifically, the cellulose ester satisfies both the following formulae (a) and (b). Wherein X is the degree of substitution of acetyl and Y is the degree of substitution of propionyl or butyryl or mixtures thereof.

Formula (a): x + Y is more than or equal to 2.1 and less than or equal to 2.5

Formula (b): y is more than or equal to 0 and less than or equal to 1.5

The cellulose ester is more preferably cellulose acetate (Y ═ 0) or Cellulose Acetate Propionate (CAP) (Y; propionyl, Y >0), and still more preferably cellulose acetate having Y ═ 0, from the viewpoint of reducing unevenness in film thickness. From the viewpoint of achieving the desired range of phase difference expression, Rt humidity fluctuation, and film thickness unevenness, cellulose acetate used is particularly preferably cellulose Diacetate (DAC) of 2.1. ltoreq. X.ltoreq.2.5, and more preferably 2.15. ltoreq. X.ltoreq.2.45. Furthermore, in the case where Y >0, it is particularly preferable to use 0.95. ltoreq. X.ltoreq.2.25, 0.1. ltoreq. Y.ltoreq.1.2, 2.15. ltoreq. X + Y.ltoreq.2.45 in Cellulose Acetate Propionate (CAP).

By using the cellulose acetate or cellulose acetate propionate, a film roll having excellent phase retardation, mechanical strength, and environmental fluctuation can be obtained.

The degree of substitution with acyl groups means the average number of acyl groups per 1 glucose unit, and means that some of the hydrogen atoms of the hydroxyl groups at positions 2, 3 and 6 of 1 glucose unit are substituted with acyl groups. Therefore, the maximum substitution degree is 3.0, and in this case, all of the hydrogen atoms of the hydroxyl groups at the 2-, 3-and 6-positions are substituted by acyl groups. These acyl groups may be substituted on the average at the 2-, 3-and 6-positions of the glucose unit, or may be substituted in a distributed manner. The degree of substitution was determined by the method defined in ASTM-D817-96.

Cellulose acetates having different degrees of substitution may be used in combination in order to obtain desired optical characteristics. The mixing ratio of different cellulose acetates is not particularly limited.

The number average molecular weight (Mn) of the cellulose ester is 2X 10⁴～3×10⁵Further within a range of 2X 10⁴～1.2×10⁵Further within the range of 4X 10⁴～8×10⁴In the case of (3), the mechanical strength of the obtained film roll is preferably improved.

The number average molecular weight Mn of the cellulose ester was calculated by measurement using Gel Permeation Chromatography (GPC) based on the measurement conditions described above.

The weight average molecular weight (Mw) of the cellulose ester is 2X 10⁴～1×10⁶Further within a range of 2X 10⁴～1.2×10⁵Further within the range of 4X 10⁴～8×10⁴In the case of (3), the mechanical strength of the obtained film roll is preferably improved.

The cellulose as a raw material of the cellulose ester is not particularly limited, and cotton linter, wood pulp, and kenaf may be mentioned. The cellulose esters obtained from these can be used by mixing them at an arbitrary ratio.

Cellulose esters such as cellulose acetate and cellulose acetate propionate can be produced by a known method. In general, a raw material cellulose, a predetermined organic acid (e.g., acetic acid, propionic acid), an acid anhydride (e.g., acetic anhydride, propionic anhydride), and a catalyst (e.g., sulfuric acid) are mixed to esterify the cellulose, and the mixture is reacted to obtain a triester of cellulose. In triesters, the three hydroxyl groups of the glucose unit are replaced by the acyl-oxygens of organic acids.

When two kinds of organic acids are used simultaneously, cellulose esters of mixed ester type, such as cellulose acetate propionate and cellulose acetate butyrate, can be produced. Next, a cellulose ester resin having a desired degree of substitution with acyl groups is synthesized by hydrolyzing a triester of cellulose. Then, the cellulose ester resin is obtained through the steps of filtration, precipitation, washing with water, dehydration, drying and the like. Specifically, the synthesis can be carried out by the method described in Japanese patent laid-open No. Hei 10-45804.

[ 2.1.4 ] other additives

The film roll of the present invention may contain the following substances as other additives in addition to the thermoplastic resin.

(a) Plasticizer

The film roll of the present invention preferably contains at least 1 kind of plasticizer for the purpose of imparting processability to a polarizer protective film or the like, for example. The plasticizer is preferably used singly or in combination of 2 or more.

Among the plasticizers, at least 1 kind of plasticizer selected from the group consisting of sugar esters, polyesters and styrene compounds is preferably contained from the viewpoint of being able to achieve both effective control of moisture permeability and compatibility with a base resin such as cellulose esters.

The plasticizer has a molecular weight of preferably 15000 or less, more preferably 10000 or less, from the viewpoint of achieving both improvement in moist heat resistance and compatibility with a base resin such as cellulose ester. When the compound having a molecular weight of 10000 or less is a polymer, the weight average molecular weight (Mw) is preferably 10000 or less. The weight average molecular weight (Mw) is preferably in the range of 100 to 10000, more preferably in the range of 400 to 8000.

In particular, in order to obtain the effects of the present invention, the compound having a molecular weight of 1500 or less is preferably contained in an amount of 6 to 40 parts by mass, more preferably 10 to 20 parts by mass, based on 100 parts by mass of the base resin. The content of the compound in the above range is preferable because effective control of moisture permeability and compatibility with the base resin can be achieved at the same time.

Sugar esters

The roll of film of the present invention may contain a sugar ester compound for preventing hydrolysis. Specifically, as the sugar ester compound, a sugar ester having at least 1 of 1 to 12 pyranose structures or furanose structures and esterified in whole or in part of OH groups of the structures can be used.

Polyester

The film roll of the present invention preferably contains polyester.

The polyester is not particularly limited, and for example, there can be used: a polymer (polyester polyol) which is obtained by a condensation reaction of a dicarboxylic acid or an ester-forming derivative thereof with a diol and has a hydroxyl group at the terminal, or a polymer (terminal-sealing polyester) in which the hydroxyl group at the terminal of the polyester polyol is sealed with a monocarboxylic acid. The ester-forming derivative herein refers to an esterified product of a dicarboxylic acid, a dicarboxylic acid chloride, and an acid anhydride of a dicarboxylic acid.

Styrene compound

In the film roll of the present invention, a styrene compound is used in addition to or instead of the above-mentioned sugar ester and polyester for the purpose of improving the water resistance of the film.

The styrenic compound may be a homopolymer of the styrenic monomer or a copolymer of the styrenic monomer and a comonomer other than the styrenic monomer. In order to provide a molecular structure with a steric hindrance of at least a certain level, the styrene compound preferably contains constituent units derived from a styrene monomer in an amount of 30 to 100 mol%, more preferably 50 to 100 mol%.

Examples of styrenic monomers include: styrenes; alkyl-substituted styrenes such as alpha-methylstyrene, beta-methylstyrene, and p-methylstyrene; halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene; hydroxystyrenes such as p-hydroxystyrene, α -methylparabenole, 2-methyl-4-hydroxystyrene, and 3, 4-dihydroxystyrene; vinyl benzyl alcohols; alkoxy-substituted styrenes such as p-methoxystyrene, p-tert-butoxystyrene, and m-tert-butoxystyrene; vinyl benzoic acids such as 3-vinyl benzoic acid and 4-vinyl benzoic acid; 4-vinylbenzyl acetate; 4-acetoxystyrene; amide styrenes such as 2-butylamide styrene, 4-methylamide styrene, and p-sulfonamide styrene; aminostyrenes such as 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, vinylbenzyldimethylamine and the like; nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; vinyl phenyl acetonitrile; arylstyrenes such as phenylstyrene, indenes, and the like. The styrene monomer may be one or a combination of two or more.

(b) Optional ingredients

The film roll of the present invention may comprise: antioxidant, colorant, ultraviolet absorber, delustering agent, acrylic acid particles, hydrogen-bonding solvent, ionic surfactant, and the like. These components may be added in the range of 0.01 to 20 parts by mass per 100 parts by mass of the base resin.

Antioxidant

In the roll of film of the present invention, a conventionally known antioxidant can be used. In particular, it is possible to preferably use: lactones, sulfur compounds, phenols, double bonds, hindered amines, and phosphorus compounds.

These antioxidants and the like may be added in an amount of 0.05 to 20% by mass, preferably 0.1 to 1% by mass, based on the resin as the main raw material of the film. These antioxidants and the like can obtain a synergistic effect by using a combination of several different kinds of compounds as compared with the case of using only 1 kind. For example, a combination of lactones, phosphorus, phenols and double bond compounds is preferably used.

Colorant

The film roll of the present invention preferably contains a colorant to adjust the color within a range not to impair the effects of the present invention. The colorant is a dye or a pigment, and in the present invention, it is a substance having an effect of changing the color tone of the liquid crystal screen to a blue color tone or a substance capable of adjusting the yellow index and reducing the haze.

As the colorant, various dyes and pigments, anthraquinone dyes, azo dyes, phthalocyanine pigments, and the like are effective.

Ultraviolet absorbent

The film roll of the present invention preferably contains an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function, from the viewpoint of being usable on the side of a polarizing plate to be observed with naked eyes and the side of a rear lamp.

The ultraviolet absorber is not particularly limited, and examples thereof include ultraviolet absorbers such as benzotriazoles, 2-hydroxybenzophenones, and salicylates. Examples thereof include: triazoles such as 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2-2-hydroxy-3, 5-bis (. alpha.,. alpha. -dimethylbenzyl) phenyl-2H-benzotriazole and 2- (3, 5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, and benzophenones such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone and 2, 2' -dihydroxy-4-methoxybenzophenone.

The ultraviolet absorber may be used alone in 1 kind or in combination of 2 or more kinds.

The amount of the ultraviolet absorber used varies depending on the kind of the ultraviolet absorber, the use conditions, and the like, and is usually 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on the base resin.

Matting agent

In the film roll of the present invention, fine particles (matting agent) for imparting slidability to the film roll are preferably added. In particular, the addition is effective from the viewpoint of improving the slidability of the surface C of the present invention, improving the slidability at the time of winding, and preventing the occurrence of scratches and blocking.

The matting agent may be either an inorganic compound or an organic compound as long as it does not impair the transparency of the obtained roll of film and has heat resistance at the time of melting. These matting agents may be used singly or in combination of 2 or more.

By using particles having different particle diameters and shapes (for example, needle-like particles and spherical particles) in combination, transparency and sliding properties can be achieved at the same time.

Among these, silica having excellent transparency (haze) is particularly preferably used because of its refractive index close to that of the cycloolefin resin, acrylic resin, or cellulose ester resin.

Specific examples of silica include: commercially available products having trade names such as AEROSIL (registered trademark) 200V, AEROSIL (registered trademark) R972V, AEROSIL (registered trademark) R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (manufactured by JEROSIL CORPORATION), SEAHOSTAR (registered trademark) KEP-10, SEAHOSTAR (registered trademark) KEP-30, SEAHOSTAR (registered trademark) KEP-50 (manufactured by NIP SHOKUBA, Inc., SYLOPHOBIC (registered trademark) 100 (manufactured by FUSHISILIA CORPORATION), NIPSIL (registered trademark) E220A (manufactured by SILICA, Japan), ADMAFINE (registered trademark) SO (manufactured by ADMATECHS, Inc.), and the like.

As the shape of the particles, there can be used, without limitation: amorphous, needle-like, flat, spherical, etc., and particularly when spherical particles are used, the transparency of the obtained film roll can be improved.

Since light is scattered and transparency is deteriorated in the vicinity of the wavelength of visible light, the size of the particles is preferably smaller than the wavelength of visible light, and more preferably 1/2 or less. When the particle size is too small, the sliding property may not be improved, and therefore, the range of 80nm to 180nm is particularly preferable. In the case where the particles are aggregates of 1-order particles, the size of the particles refers to the size of the aggregates. In addition, when the particle is not spherical, it means a diameter of a circle corresponding to a projected area thereof.

The matting agent is added in an amount of 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on the base resin.

[ 2.2 ] method for producing film roll

The method for producing a film roll of the present invention includes a step of performing a surface modification treatment at least at the site a or the site B.

Further, the surface modification treatment is preferably performed only at the site B, and is preferably performed at both the site a and the site B.

As described above, the knurled portion is preferably formed by laser knurling (laser method).

Since the above items are all the ones described in item [ 1], a method for producing the film itself will be described here.

As the film roll manufacturing method of the present invention, a general inflation method, T die method, calendering method, slitting method, casting method, emulsification method, hot press method can be used for film formation of the film, but from the viewpoints of suppression of coloring, suppression of foreign matter defects, suppression of optical defects such as die lines (die lines), and the like, the film formation method is preferably a solution casting film formation method and a melt casting film formation method, and particularly more preferably the solution casting method can obtain a uniform surface.

Solution casting film-making method

In the case of film formation by a solution casting method, the method for producing a film roll of the present invention preferably includes: a step of dissolving the thermoplastic resin and the additive in a solvent to prepare a dope (dissolving step; dope preparing step); a step of casting a dope onto a continuously moving endless metal support (casting step); a step (solvent evaporation step) of drying the dope cast as a web; a step of peeling the metal support (peeling step); a step of drying, stretching, and width holding (stretching, width holding, and drying step); and a step (winding step) of winding the completed film into a roll shape. As the thermoplastic resin, a cycloolefin resin or an acrylic resin is particularly preferably used.

Fig. 3 is a view schematically showing an example of a dope preparation step, a casting step, and a drying step (solvent evaporation step) in the solution casting film-forming method.

The large aggregates were removed by filter a44 through charging tank a41 and sent to holding tank a 42. Then, various additive solutions were added to the main dope dissolving tank 1 through the stock tank a 42.

Then, the main dope was filtered through the main filter A3, and the additive-added solution was added on-line through a 16.

In most cases, the main dope contains about 10 to 50 mass% of returned chips.

The returned scrap is a finely divided film, and is a film material cut from both sides of the film, which is generated when the film is formed, or a film material that is out of specification due to scratches or the like is used.

Further, as a raw material of the resin used for the dope preparation, a resin obtained by granulating a cellulose ester as a matrix resin and other additives in advance can be preferably used.

Hereinafter, each step will be explained.

1) Dissolution step (dopant preparation step)

Hereinafter, as an embodiment of the present invention, a case where a cycloolefin resin (hereinafter, also referred to as COP) is used as a thermoplastic resin will be described as an example of the dissolving step, but the present invention is not limited thereto.

The process comprises the following steps: a step of dissolving the COP and optionally other compounds in a solvent mainly containing a good solvent for the COP while stirring the COP and other compounds in a dissolution tank to form a dope; or a step of mixing a solution of another compound, as the case may be, with the COP solution to form a dope as a main solution.

When the concentration of COP in the dope is high, the drying load after casting to the metal support can be reduced, but when the concentration of COP is too high, the load at the time of filtration increases, and the filtration accuracy deteriorates. The concentration of both components is preferably 10 to 35% by mass, and more preferably 15 to 30% by mass.

The solvent used for doping may be used singly or in combination of 2 or more, and when a good solvent and a poor solvent for COP are used in a mixture, the solvent is preferable in terms of production efficiency, and when a large amount of the good solvent is used, the solvent is preferable in terms of solubility of COP.

The mixing ratio of the good solvent and the poor solvent is preferably in the range of 70 to 98% by mass and 2 to 30% by mass. As the good solvent and the poor solvent, a solvent in which the COP used is dissolved alone is defined as a good solvent, and a solvent which is swelled or not dissolved alone is defined as a poor solvent. Therefore, the good solvent and the poor solvent change depending on the average substitution degree of COP.

The good solvent used in the present invention is not particularly limited, and examples thereof include organic halides such as methylene chloride, dioxolane, acetone, methyl acetate, methyl acetoacetate, and the like. Particularly preferred are methylene chloride and methyl acetate.

The poor solvent used in the present invention is not particularly limited, and for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, and the like are preferably used. The dope preferably contains 0.01 to 2 mass% of water.

In addition, as the solvent used for dissolving the COP, a solvent obtained by drying and removing from the film in the film forming step may be recovered and reused.

The recovery solvent may contain a trace amount of additives added to COP, such as a plasticizer, an ultraviolet absorber, a polymer, a monomer component, and the like, but even if these are contained, they can be preferably reused, and if necessary, they can be purified and reused.

As a method for dissolving COP in the preparation of the above-described dope, a general method can be used. Specifically, it is preferable that: a process carried out at atmospheric pressure; a method performed below the boiling point of the main solvent; in the method of pressurizing at a temperature equal to or higher than the boiling point of the main solvent, when heating and pressurizing are combined, heating may be performed to a temperature equal to or higher than the boiling point at normal pressure.

A method of dissolving the solvent by stirring while heating at a temperature not lower than the boiling point of the solvent under normal pressure and in a range where the solvent does not boil under pressure is also preferable because the generation of gel and a lump of undissolved matter called lumps is prevented.

Further, a method of mixing COP with a poor solvent to wet or swell the COP, and then adding a good solvent to dissolve the COP may be preferably used.

The pressurization can be performed by a method of pressurizing an inert gas such as a nitrogen gas or a method of raising the vapor pressure of the solvent by heating. The heating is preferably performed from the outside, for example, a jacket type, which is easy to control the temperature is preferable.

When the heating temperature of the addition solvent is high, it is preferable from the viewpoint of solubility of COP, but when the heating temperature is too high, the required pressure becomes large, and productivity deteriorates.

The preferable heating temperature is 45 to 120 ℃, more preferably 60 to 110 ℃, and further preferably 70 to 105 ℃. Further, the pressure is adjusted in such a manner that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method is also preferably used, and thus COP can be dissolved in a solvent such as methyl acetate.

Next, the COP solution (dope in solution or after dissolution) is preferably filtered through an appropriate filter medium such as filter paper.

As the filter medium, it is preferable that the absolute filtration accuracy is low in order to remove insoluble substances and the like, but when the absolute filtration accuracy is too low, there is a problem that clogging of the filter medium is likely to occur. Therefore, a filter having an absolute filtration accuracy of 0.008mm or less is preferable, a filter having an absolute filtration accuracy of 0.001 to 0.008mm is more preferable, and a filter having an absolute filtration accuracy of 0.003 to 0.006mm is even more preferable.

The material of the filter medium is not particularly limited, and a common filter medium can be used, and a filter medium made of plastic such as polypropylene or TEFLON (registered trademark), or a filter medium made of metal such as stainless steel is preferable because fibers are not detached.

Impurities contained in the COP of the raw material, particularly, bright foreign substances are preferably removed and reduced by filtration.

The bright spot foreign matter is a spot (foreign matter) where 2 polarizing plates are arranged in a crossed nicols state, a film or the like is arranged therebetween, light is irradiated from one polarizing plate side, and light leakage from the opposite side can be observed when observed from the other polarizing plate side, and it is preferable that the number of bright spots having a diameter of 0.01mm or more is 200/cm²The following. More preferably 100/cm²Hereinafter, more preferably 50 pieces/cm²More preferably 0 to 10/cm²The following. Preferably, the number of bright spots of 0.01mm or less is also small.

Filtration of the dope can be carried out by a usual method, and a method of heating at a temperature of not less than the boiling point of the solvent under normal pressure and in a range where the solvent does not boil under pressure and simultaneously carrying out filtration is preferable because the rise in the filtration pressure difference (also referred to as differential pressure) before and after filtration is small.

The preferable temperature is 45-120 ℃, more preferably 45-70 ℃, and further preferably 45-55 ℃.

Preferably, the filtration pressure is low. The filtration pressure is preferably 1.6MPa or less, more preferably 1.2MPa or less, and still more preferably 1.0MPa or less.

2) Casting step

Next, the dope is cast (cast) on a metal support. That is, in this step, the dope is fed to the pressure die a30 by a liquid feeding pump (for example, a pressure type fixed-displacement gear pump), and the dope is cast from the gap of the pressure die at a casting position on a metal support such as a continuously running endless metal belt a31, for example, a stainless steel belt or a rotating metal drum.

A press die capable of adjusting the slit shape of the metal gate portion of the die to easily make the film thickness uniform is preferable. The pressurizing die head may be a clothes hanger type die head, a T die head, or the like. Preferably, the surface of the metal support is specular. In order to increase the film forming speed, 2 or more press dies may be provided on the metal support, and the dope amount may be divided and stacked. Further, it is also preferable to obtain a roll of a laminate structure by a co-casting method in which a plurality of dopes are cast simultaneously.

The casting width is preferably 1.3m or more from the viewpoint of productivity. More preferably 1.3 to 4.0 m. If the thickness is more than 4.0m, streaks may occur in the production process or stability may be lowered in the subsequent conveyance process. From the viewpoint of transportation and productivity, it is more preferably 1.3 to 3.0 m.

The metal support in the casting (casting) step preferably has a mirror surface, and a stainless steel belt or a drum having a surface plated with a casting is preferably used as the metal support.

The surface temperature of the metal support in the casting step is preferably from-50 ℃ to a temperature lower than the boiling point of the solvent, and when the temperature is high, the drying rate of the web becomes high, but when the temperature is too high, the web may be foamed or the planarity may be deteriorated.

The support temperature is preferably 0 to 55 ℃, and more preferably 22 to 50 ℃. Alternatively, the web is gelled by cooling and is peeled from the drum in a state containing a large amount of residual solvent, which is also a preferable method.

The method of controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of bringing warm water into contact with the inside of the metal support. When warm water is used, heat is efficiently transferred, and therefore, the time required for the temperature of the metal support to be constant is short, which is preferable. In the case of using warm air, air having a temperature higher than the target temperature may be used.

3) Solvent evaporation procedure

This step is a step of heating a web (dope is cast on a casting support, and the dope film formed is referred to as a web) on the casting support to evaporate the solvent.

For the evaporation of the solvent, there are a method of blowing air from the web side and/or a method of conducting heat from the back side of the support body by liquid, a method of conducting heat from the front and back sides by radiant heat, and the like, and the back side liquid heat conduction method is preferable because it has good drying efficiency. Further, a method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 35 to 100 ℃. In order to maintain the temperature in the atmosphere of 35 to 100 ℃, it is preferable to blow warm air at the temperature on the upper surface of the web or to heat the web by means of infrared rays or the like.

From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable that the web is peeled from the support within 30 to 120 seconds.

4) Peeling step

Next, the web was peeled from the metal support. That is, this step is a step of peeling off a web obtained by evaporating a solvent on a metal support at a peeling position. The peeled web is sent to the next step.

The temperature at the peeling position on the metal support is preferably in the range of-50 to 40 ℃, more preferably in the range of 10 to 40 ℃, and still more preferably in the range of 15 to 30 ℃.

The amount of the solvent remaining at the time of peeling the web on the metal support at the time of peeling is appropriately adjusted depending on the strength of the drying condition, the length of the metal support, and the like. In order to make the film exhibit good planarity, the amount of the residual solvent when the web is peeled from the metal support is preferably 10 to 150 mass%. When peeling is performed at a high residual solvent content, the web is too soft, and the planarity is impaired during peeling, and creases and longitudinal streaks are likely to occur due to the peeling tension, and therefore the residual solvent content during peeling is determined to have both economical speed and quality. More preferably 20 to 40% by mass or 60 to 130% by mass, and particularly preferably 20 to 30% by mass or 70 to 120% by mass.

In the present invention, the residual solvent amount is defined by the following formula.

Residual solvent amount (% by mass) { (M-N)/N } × 100

M is the mass of a sample collected at any time during or after the production of the web or film, and N is the mass of M after heating at 115 ℃ for 1 hour.

The peeling tension when peeling the metal support and the film is preferably 300N/m or less. More preferably, the amount of the inorganic filler is in the range of 196 to 245N/m, and when wrinkles are likely to occur during peeling, peeling is preferably performed with a tension of 190N/m or less. Preferably, the peeling is performed at a peeling tension of 300N/m or less.

5) Drying, stretching and width holding step

(drying)

In the film drying step, the web is preferably peeled off from the metal support and further dried so that the residual solvent amount is 1 mass% or less, more preferably 0.1 mass% or less, and particularly preferably 0 to 0.01 mass% or less.

In the film drying step, generally used are: a roll drying system (a system in which a web is dried by alternately passing through a plurality of rolls arranged above and below), and a system in which drying is performed while conveying the web by a tenter system. For example, after the peeling, the web is dried by using a drying device 35 that alternately passes through a plurality of rollers in the drying device and transports the web, and/or a tenter stretching device 34 that clamps both ends of the web by clips and transports the web.

The means for drying the web is not particularly limited, and generally, it can be carried out by hot air, infrared rays, heated rolls, microwaves, and the like, and from the viewpoint of simplicity, it is preferably carried out by hot air. When drying is too fast, the planarity of the film is easily impaired. Drying at high temperature may be started from a residual solvent content of 8% by mass or less. Generally, the drying is carried out in the range of approximately 30 to 250 ℃. Particularly, it is preferable to dry the mixture at 35 to 200 ℃. The drying temperature is preferably raised in stages.

In the case of using a tenter stretching device, it is preferable to use: the device can independently control the clamping length (the distance from the clamping start to the clamping end) of the film by the left and right clamping means of the tenter. In addition, in the tenter process, it is preferable to intentionally create regions having different temperatures in order to improve planarity.

Further, it is preferable to provide a neutral region between the different temperature regions in such a manner that the respective regions do not interfere.

(stretching width holding)

Next, the web peeled from the metal support is preferably subjected to stretching treatment in at least one direction. The orientation of the molecules within the film can be controlled by the stretching process. In order to obtain the phase retardation values Ro and Rt targeted in the present invention, it is preferable to adopt the film of the present invention and further perform the refractive index control by controlling the transport tension and the stretching operation. For example, the phase retardation value can be changed by decreasing or increasing the tension in the longitudinal direction.

As a specific stretching method, biaxial stretching or uniaxial stretching may be successively or simultaneously performed in the longitudinal direction (film-forming direction; casting direction; MD direction) of the web and the width direction (TD direction) which is a direction orthogonal in the plane of the web. A biaxially stretched film biaxially stretched in the casting direction (MD direction) and the width direction (TD direction) is preferable, but the film of the present invention may be a uniaxially stretched film or an unstretched film. The stretching operation may be performed in a plurality of stages. In the case of biaxial stretching, the biaxial stretching may be performed simultaneously or may be performed in stages. In this case, the stepwise property means that, for example, stretching in different stretching directions may be performed sequentially, or stretching in the same direction may be divided into a plurality of stages and stretching in different directions may be added to any of the stages.

For example, the following stretching step may be performed:

stretching in the casting direction → stretching in the width direction → stretching in the casting direction

Stretching in the width direction → stretching in the casting direction

The simultaneous biaxial stretching also includes stretching in one direction and contracting by relaxing the tension in the other direction.

The stretching ratios in the biaxial directions perpendicular to each other are preferably in the range of 0.8 to 1.5 times in the final casting direction and 1.1 to 2.5 times in the width direction, more preferably 0.8 to 1.2 times in the final casting direction and 1.2 to 2.0 times in the width direction.

The stretching temperature is preferably in the range of Tg to Tg +60 ℃ of the resin constituting the film. In general, the stretching temperature is preferably 120 to 200 ℃ and more preferably 120 to 180 ℃.

The stretching is preferably performed with a residual solvent in the web at the time of stretching of 20 to 0%, more preferably 15 to 0%. For example, it is preferable to conduct stretching at 135 ℃ with a residual solvent of 8% or stretching at 155 ℃ with a residual solvent of 11%. Or preferably at 155 ℃ with 2% residual solvent, or preferably at 160 ℃ with less than 1% residual solvent.

The method of stretching the web is not particularly limited. Examples thereof include: a method of imparting a peripheral speed difference to a plurality of rolls, and stretching in the longitudinal direction therebetween with the use of the roll peripheral speed difference; a method of fixing both ends of a web by clips and staples, expanding the gap between the clips and the staples in the proceeding direction, and stretching the web in the longitudinal direction; a method of stretching in the transverse direction by expanding in the transverse direction as well; or a method of stretching in both the vertical and horizontal directions by simultaneously expanding the horizontal and vertical directions. Of course, these methods may be used in combination. Among them, stretching in the width direction (transverse direction) by a tenter system in which both ends of the web are nipped by clips or the like is particularly preferable.

In the case of the so-called tenter method, when the nip portion is driven by a linear driving method, smooth stretching can be performed and the risk of breakage or the like can be reduced, which is preferable.

The width holding or transverse stretching in the film forming step is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

When the slow axis or the fast axis of the film of the present invention is present in the film surface and the angle formed with the film forming direction is θ 1, θ 1 is preferably-1 ° or more and +1 ° or less, more preferably-0.5 ° or more and +0.5 ° or less.

The θ 1 can be defined as an orientation angle, and the θ 1 can be measured by using an automatic birefringence meter KOBRA-21ADH (manufactured by prince measuring instruments). θ 1 satisfies each of the relationships contributing to: obtaining high brightness in the display image; suppressing or preventing light leakage; a color liquid crystal display device can obtain faithful color reproduction.

6) Coiling step

Finally, the obtained web (finished film) is wound up to obtain a film roll. More specifically, in the step of winding the web as a film by the winder a37 after the residual solvent amount in the web becomes 2 mass% or less, a film having good dimensional stability can be obtained by setting the residual solvent amount to 0.4 mass% or less. In particular, it is preferable to wind the steel sheet in the range of 0.00 to 0.10 mass%.

The winding method may be a commonly used method, and examples thereof include: a constant torque method, a constant tension method, a taper tension method, a programmed tension control method in which the internal stress is constant, and the like, which may be optionally used.

Before winding, the ends of the finished product are cut and trimmed to prevent sticking and scratching during winding, and the film may be knurled and surface modified at both ends.

In the nip portion between the film and the clips at both ends of the film, the film is generally deformed and cannot be used as a product, and therefore, the film is cut off. When the material is not deteriorated by heat, it is recovered and reused.

The film roll of the present invention is preferably a long film, more specifically, about 100m to 10000m, and is usually supplied in a roll form. The width of the protective film is preferably 1.3 to 4m, more preferably 1.4 to 4m, and still more preferably 2 to 3m, in accordance with the demand for the liquid crystal display device to be increased in size and production efficiency.

Details of the method for winding up the film

The film after the knurling treatment and the surface modification treatment is preferably wound by the following winding method.

The winding method preferably includes the steps of: a direct winding step of winding the film around a winding core so that side edges of the film are aligned; and a swing winding step of, after the direct winding step, periodically vibrating the film or the winding core in the film width direction so that the side edge is periodically offset in a certain range with respect to the film width direction, and winding the film around the winding core.

In particular, it is preferable that the direct winding step is switched to the swing winding step when the roll length of the film reaches a predetermined switching roll length in a range of 10 to 30% with respect to the total roll length of the film.

The film winding apparatus preferably includes: a film winding unit that rotates a winding core and winds a film around the winding core; a swinging unit configured to oscillate the film or the winding core in the film width direction in conjunction with winding of the film so that the film is periodically wound on the winding core in a swinging manner that the film is shifted within a predetermined range in the film width direction; a switching section that switches winding of the film from the direct winding to the swing winding when a roll length of the film reaches a predetermined switching roll length.

The following describes the swing winding.

As shown in fig. 4, the film line B10 includes: a film-producing apparatus B11 and a take-up apparatus B12. The film manufacturing apparatus B11 manufactured a film B13 by a solution film forming method. In the solution film-forming method, first, a dope is prepared using a raw material. And, the prepared dope was cast on a ring support and a cast film was formed. When the casting film becomes self-supporting, the casting film is peeled from the ring support. The casting film obtained by peeling is dried by hot air or the like to form a film B13. The resultant film B13 was fed to a winding apparatus B12 via a knurling imparting roller B15. The knurling application roller B15 forms fine irregularities on both side edge portions (ear portions) in the width direction of the film B13 by embossing or the like. The height of the irregularities formed by the knurling roller is preferably in the range of 0.5 to 20 μm.

As shown in fig. 4 and 5, the winding apparatus B12 includes: a winding shaft B19, a core holder B20, a core B21, a turret B22, guide rollers B23, B24, a tension adjusting roller B25, an encoder B27, a swing portion B29, a winding motor B30, a controller B31, and a tension adjusting portion B32. The film size to be wound in the winding apparatus B12 is not particularly limited, and for example, a film having a total winding length in the range of 2000 to 10000m and a width in the range of 500 to 2500mm is preferable.

As shown in fig. 5, the take-up shaft B19 is mounted to the turret B22 by a cantilever support mechanism. The cantilever support mechanism is a mechanism that supports only one end of the winding shaft B19. The winding shaft B19 is attached to the winding core B21. The core B21 is held at both ends by a core holder B20 of the winding shaft B19. The winding core holder B20 is attached so as to be slidable in the axial direction (Y direction) of the winding shaft B19 and not rotatable about the winding shaft B19. One end of the winding shaft B19 is connected to a winding motor B30, which is configured to rotate the winding shaft B19. By this rotation, the winding core B21 is also rotated, and the film B13 can be wound around the winding core B21. By winding the film B13, a film roll B38 was obtained in which the film B13 was wound into a roll shape.

A shaft mechanism B28 is attached to the mounting end of the take-up shaft B19 of the turret B22. The shaft mechanism B28 reciprocates the core holder B20 in the axial direction on the take-up shaft B19. The shaft mechanism B28, the winding shaft B19, and the winding core holder B20 form a swing portion B29. The swinging section B29 is operated, and the winding core holder B20 is reciprocated in the Y direction on the winding shaft B19 by the shaft mechanism B28, so that the position of the side edge B13a of the film B13 at the time of lamination is shifted within the range of the amplitude Wo, and the film B13 can be wound in a swinging manner. Without operating the swing portion B29, direct winding in an aligned state at both side edges of the film B13 may be provided. The switching between the direct winding and the swing winding is performed by the controller B31.

Here, in the wobbling winding, the wobbling width Wo as the amplitude thereof may be arbitrarily set, and the amplitude Wo is preferably in the range of 10 to 30mm, and in the above range, the amplitude Wo may be gradually increased or decreased after being increased, in addition to being fixed at a constant value.

Guide rollers B23, B24, and dancer roller B25 guide film B13 from film manufacturing apparatus B11 in the conveying direction (X direction). The dancer roller B25 also adjusts the winding tension of the film B13 by moving the film B13 in the vertical direction (Z direction) by the shaft mechanism B26. The shaft mechanism B26 and the dancer roller B25 form a dancer B32. The encoder B27 transmits an encoder pulse signal to the controller B31 when the guide roller B24 rotates at a certain rotation angle. The guide roll B24 may be provided with a tension sensor for measuring the winding tension of the film B13.

The controller B31 controls the driving of the swing portion B29, the take-up motor B30, and the tension adjusting portion B32. The controller B31 includes: a winding information input unit B39, a LUT storage B40, a switching roll length determination unit B41, a roll length measurement unit B42, and a switching determination unit B43. To the winding information input portion B39, there are input: winding information such as the total winding length, thickness, width of the film B13, the outer diameter of the winding core B21, and winding tension.

In the LUT storage B40, the winding information includes: the roll length of the film B13 when switching from direct winding to swing winding (switching roll length). The switching roll length is preferably set in advance in a range of 10 to 30% of the total roll length of the film B13, and more preferably in a range of 15 to 25% of the total length of the film B13.

The timing of switching from direct winding to swing winding is more preferably set to a range in which the winding length is 15 to 25% of the total winding length.

When the winding length is 10% or more of the total winding length, the surface pressure can be more reliably prevented from being abruptly reduced at the start of winding the film B13, compared to the case where the switching is performed at less than 10%. Therefore, the occurrence of winding looseness and winding displacement of the film roll B38 can be more reliably prevented. Further, when switching is performed after the roll length exceeds 30% with respect to the total roll length, the stress in the circumferential direction of the film B13 is separated from the negative region and then the film B is wound by direct winding, so that the film roll B38 is more likely to cause ear portions to extend than when switching is performed at 30% or less. Therefore, by switching from the direct winding to the swing winding when the winding length is 30% or less with respect to the total winding length, it is possible to more reliably prevent the occurrence of the ear portion extension than in the case of switching after exceeding 30%.

The switching roll length determining unit B41 determines the switching roll length corresponding to the input winding information, based on the winding information stored in the LUT storage B40 and the winding information input to the winding information input unit B39. The roll length measuring unit B42 measures the roll length of the film B13 wound around the winding core B21 based on the encoder pulse signal from the encoder B27.

The switching determination unit B43 determines whether or not the roll length measured by the roll length measuring unit B42 exceeds the switched roll length determined by the switched roll length determination unit B41. When it is determined that the roll length exceeds the switching roll length, a swing winding start signal is sent to the swing portion B29. Upon receiving the swing winding start signal, the swing portion B29 changes the direct winding of the film B13 from the winding of the film B13 with the side edge B13a of the film aligned to the swing winding of the film B13 with the position of the side edge B13a shifted within the range of the amplitude Wo.

Melt casting film-making method

The film roll of the present invention can be formed into a film by a melt casting method.

The "melt film-forming method" refers to a method of heating and melting a composition containing a thermoplastic resin and the additive to a temperature at which fluidity is exhibited, and then casting a melt containing the thermoplastic resin that is flowable. As the thermoplastic resin, cellulose ester is particularly preferably used.

As a molding method by heating and melting, in detail, there are: melt extrusion molding, press molding, inflation molding, injection molding, blow molding, stretch molding, and the like. Among these molding methods, a melt extrusion method is preferred from the viewpoint of mechanical strength, surface accuracy, and the like. In general, a plurality of raw materials used in the method of melt extrusion are preferably kneaded and granulated in advance.

The granulation can be carried out by known methods, for example, by: the dried cellulose ester, plasticizer, and other additives are supplied to an extruder through a feeder, kneaded using a single-shaft or twin-shaft extruder, extruded from a die in a strand form, water-cooled or air-cooled, and cut.

The additives may be mixed before being supplied to the extruder, or may be supplied separately from each other by a feeder.

For uniform mixing, small amounts of additives such as particles and antioxidants are preferably mixed in advance.

The extruder is preferably processed at as low a temperature as possible, because the extruder can pellet the resin so as not to deteriorate (decrease in molecular weight, coloration, gel formation, etc.) by suppressing the shear force. For example, in the case of a twin-screw extruder, it is preferable to use a deep groove type screw and rotate it in the same direction. From the viewpoint of kneading uniformity, the type of the mesh is preferred.

Using the particles obtained in the above manner, film formation is performed. Of course, the powder of the raw material may be supplied to the extruder as it is by a feeder without being granulated, and film formation may be performed as it is.

The melt temperature when the pellets are extruded using a single-shaft or twin-shaft type extruder is set to a temperature range of 200 to 300 ℃, filtered by a leaf-disk type filter or the like to remove foreign matter, cast in a film form from a T-die, and the film is nipped between a cooling roll and an elastic contact roll and solidified on the cooling roll.

When the raw material is introduced into the extruder from the supply hopper, it is preferably introduced under vacuum or reduced pressure in an inert gas atmosphere to prevent oxidative decomposition or the like.

The extrusion flow rate is preferably stably performed by introducing a gear pump or the like. Further, as the filter used for removing the foreign matter, a stainless steel fiber sintered filter is preferably used. The sintered stainless steel fiber filter is obtained by compressing a stainless steel fiber body in a complex state, sintering the contact points, and integrating them, and the filtration accuracy can be adjusted by changing the density according to the thickness and the amount of compression of the fiber.

Additives such as a plasticizer and particles may be previously mixed with the resin or may be kneaded in the middle of the extruder. For uniform addition, a mixing device such as a static mixer is preferably used.

When the film is nipped between the cooling roll and the elastic contact roll, the film temperature on the contact roll side is preferably set to a temperature range of Tg to (Tg +110) DEG C of the film. For the roller having an elastic surface used for such a purpose, a known roller can be used.

The elastic contact roller is also called a pressing rotator. As the elastic contact roller, commercially available ones can be used.

When the film is peeled from the cooling roll, the tension is preferably controlled to prevent deformation of the film.

In addition, the film obtained in the above-described manner is preferably stretched by the above-described stretching operation after passing through the step of contacting a cooling roll.

As a method of stretching, a known roll stretcher, tenter, or the like can be preferably used. The specific conditions are the same as in the case of the solution casting method.

Finally, the film roll of the present invention is obtained by winding the film obtained as described above, as in the case of the solution casting method.

Use of [ 3] film

The film taken out from the film roll of the present invention is preferably used as a protective film of a polarizing plate or the like as an optical film, and can be used in various optical measuring devices, display devices such as liquid crystal display devices and organic electroluminescence display devices.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the examples, the expression "part(s)" or "%" is used, and unless otherwise specified, it means "part(s) by mass" or "% by mass".

< production of roll of film >

(example 1)

Synthesis of Cyclic polyolefin Polymer P-1

100 parts by mass of purified toluene and 100 parts by mass of norbornene carboxylic acid methyl ester were put into a reaction vessel. Next, 25 mmol% (based on the mass of the monomer) of ethyl hexanoate-Ni dissolved in toluene, 0.225 mol% (based on the mass of the monomer) of tris (pentafluorophenyl) boron and 0.25 mol% (based on the mass of the monomer) of triethylaluminum dissolved in toluene were charged into the reaction vessel. The reaction was carried out for 18 hours while stirring at room temperature. After the reaction, the reaction mixture was poured into an excess amount of ethanol to form a polymer precipitate. The polymer (P-1) obtained by purifying the precipitate was dried at 65 ℃ for 24 hours by vacuum drying.

Preparation of dopant D-1

The following composition was put into a mixing tank, stirred to dissolve the components, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a dope.

Cyclic polyolefin polymer P-1150 parts by mass

380 parts by mass of methylene chloride

70 parts by mass of methanol

Next, the following composition containing the cyclic polyolefin solution (dope) prepared by the above method was put into a dispersion machine to prepare a fine particle dispersion liquid (M-1).

4 parts by mass of fine particles (AEROSIL R812: manufactured by AEROSIL CORPORATION, Japan, average primary particle diameter: 7nm, apparent specific gravity: 50g/L)

76 parts by mass of methylene chloride

10 parts by mass of methanol

10 parts by mass of a cyclic polyolefin solution (dope D-1)

100 parts by mass of the cyclic polyolefin solution and 0.75 part by mass of the fine particle dispersion were mixed to prepare a dope for film formation. The dope was cast at a width of 1800mm through a film forming line, dried on a metal support to have self-supporting properties, and then peeled as a web and introduced into a tenter.

The residual solvent of the web is 5-15% by mass when introduced into the tenter. The tenter was transported with a stretching ratio of 20% in the width direction and an internal temperature of 160 ℃. The film roll was then dried, cut and adjusted to a width of 2000mm and a film thickness of 40 μm.

Knurling process

The laser beam is irradiated to form a knurled portion (portion A).

The knurling width at both ends was set to 15mm from the film end. The linear velocity of the transport film was set to 10 m/min.

As a laser device, a carbon dioxide gas laser device was used, and the output of the laser device was set to 20W, the center wavelength of the emission wavelength was set to 9.4 μm, and the emission wavelength range was set to. + -. 0.01 μm or less around the center wavelength.

Irradiating the film with laser light by: the collimated beam emitted from the carbon dioxide gas laser device was reflected by a 2-piece galvanometer mirror, and focused to the surface of the transported film via an f θ lens (focal length 200 mm). By controlling the angle of the galvanometer mirror, the focal position is moved in the film plane direction, thereby controlling the trajectory of the laser light irradiated onto the film surface.

Surface modification treatment: atmospheric pressure plasma processing procedure

AGP-500 was prepared by a spring motor on the back side (part B) of the knurled part (part A) of the film, and was sprayed at 0.5 kW. The spraying was performed in such a manner that the distance from the probe emitting the atmospheric pressure plasma to the film was 5 mm. The setting position is set so that the jetted atmospheric pressure plasma can jet a width of 110% of the width of the knurled part on the back side of the film opposite to the knurled part.

Coiling process

And winding the film obtained by the knurling. The winding was carried out at an initial tension of 150N, a taper of 70% and a corner of 25%.

Using TR, the average air layer thickness contained in the film roll was suppressed to 1.0 μm.

The winding was carried out with a winding length of 4000m and a width of 1.5 m.

Through the above steps, the film roll of example 1 was prepared.

Comparative example 1

A roll of comparative example 1 was produced in the same manner as the production of the roll of example 1, except that the atmospheric pressure plasma treatment step was not included.

Comparative example 2

A roll of film of comparative example 2 was produced in the same manner as the production of the roll of film of example 1, except that the atmospheric pressure plasma treatment process was performed in the following manner.

Atmospheric pressure plasma processing procedure

10 spring Motor systems AGP-500 were placed across the width of the film, spraying at 1.0 kW. The spraying was performed in such a manner that the distance from the probe emitting the atmospheric pressure plasma to the film was 10 mm. The atmospheric pressure plasma to be injected is set so as to diffuse over the entire surface of the film width.

(example 2)

Production of rubber particle B-1

In a reactor equipped with a reflux condenser having a capacity of 60 liters, 38.2 liters of ion-exchanged water and 111.6g of sodium dioctylsulfosuccinate were charged and stirred at a rotation speed of 250rpm, and the temperature was raised to 75 ℃ under a nitrogen atmosphere, thereby obtaining a state in which the influence of oxygen was not substantially present. 0.36g of Ammonium Persulfate (APS) was charged, and after stirring for 5 minutes, a monomer mixture (c1) containing 1657g of Methyl Methacrylate (MMA), 21.6g of Butyl Acrylate (BA) and 1.68g of allyl methacrylate (ALMA) was added thereto together, and after detection of an exothermic peak, the mixture was kept for further 20 minutes to complete polymerization of the innermost hard layer.

Next, 3.48g of Ammonium Persulfate (APS) was charged, and after stirring for 5 minutes, 1961g of Butyl Acrylate (BA), 346g of Methyl Methacrylate (MMA), and 264.0g of allyl methacrylate (ALMA) (BA/MMA mass ratio) of the monomer mixture (a1) was continuously added over 120 minutes, and after the addition was completed, the polymerization of the soft layer was completed by further holding for 120 minutes.

Next, 1.32g of Ammonium Persulfate (APS) was charged, and after stirring for 5 minutes, a monomer mixture (b1) containing 2106g of Methyl Methacrylate (MMA) and 201.6g of Butyl Acrylate (BA) was continuously added over 20 minutes, and after the end of the addition, the polymerization of the hard layer 1 was completed by further holding for 20 minutes.

Subsequently, 1.32g of Ammonium Persulfate (APS) was charged, 5 minutes thereafter, 3148g of a monomer mixture (b2) comprising Methyl Methacrylate (MMA), 201.6g of Butyl Acrylate (BA) and 10.1g of n-octyl mercaptan (n-OM) was continuously added over 20 minutes, and the mixture was held for further 20 minutes after the completion of the addition. Then, the temperature was raised to 95 ℃ for 60 minutes to complete the polymerization of the hard layer 2.

The average particle size of the polymer latex obtained in a small amount was 0.10 μm as a result of measurement by an absorbance method. The remaining latex was poured into a3 mass% sodium sulfate warm water solution to be salted out and coagulated, followed by repeated dehydration and washing, and then dried to obtain acrylic acid particles having a 4-layer structure. The rubber particles B-1 obtained had an average particle diameter of 200nm and a glass transition temperature (Tg) of-30 ℃.

< production of roll of film >

After 22.6 parts by mass of the rubber particles and 400 parts by mass of methylene chloride were mixed by stirring with a dissolver for 50 minutes, they were dispersed at 1500rpm using a maidauda disperser (manufactured by atlantic machine corporation) to obtain a rubber particle dispersion liquid. Then, the rubber particle dispersion was left in the storage tank for 6 hours, and was constantly stirred during storage.

(preparation of dope)

Subsequently, a dope having the following composition was prepared. First, methylene chloride and ethanol were put into a pressure dissolution tank. Next, in a pressure dissolution tank, while stirring, 85/15 (methyl methacrylate (MMA)/N-Phenylmaleimide (PMI)) was charged, and an acrylic resin (described as polymethyl methacrylate: PMMA) having a glass transition temperature (Tg) of 120 ℃ and a weight average molecular weight of 200 ten thousand was charged. Next, the prepared rubber particle dispersion was charged, heated to 60 ℃, and completely dissolved while being stirred. The temperature was raised from room temperature at 5 ℃/min, dissolved in 30 minutes, and then lowered at 3 ℃/min. The obtained solution was filtered through a filter having a filtration accuracy of 30 μm to obtain a dope.

(composition of dopants)

88 parts by mass of acrylic resin (PMMA)

Methylene chloride 70 parts by mass

50 parts by mass of ethanol

400 parts by mass of a rubber particle dispersion

Next, the dope was uniformly cast onto a stainless steel belt support at a temperature of 31 ℃ and a width of 1800mm using an endless belt casting apparatus. The temperature of the stainless steel belt was controlled to 28 ℃. The conveying speed of the stainless steel belt was set to 20 m/min.

The subsequent steps prepare the roll of film of example 2 in the same manner as the preparation of the roll of film of example 1.

(example 3)

A film roll was prepared in the same manner except that a knurled portion was formed under the following knurling processing conditions in the preparation of the film roll of example 1.

The knurling process was performed in the following manner.

Knurling condition

Processing temperature: 250 deg.C

Processing pressure: 0.5MPa

Knurling opposite roller: metal rear roller

(example 4)

In the production of the film roll of example 1, plasma treatment was performed on both surfaces of the knurled portion (portion a) and the opposing film back surface portion (portion B) by the (atmospheric pressure plasma treatment step).

(example 5)

In the production of the film roll of example 1, the dopant metal support was dried to have self-supporting properties, and then, the film was separated as a web, conveyed while transferring the surface shape by using a surface shape transfer roller (a transfer roller having an arithmetic average roughness R a of 1.2 μm) at the film portion, and then, plasma-treated at the knurled portion (portion a) by the above-described "atmospheric pressure plasma treatment step".

(example 6)

(preparation of Fine particle-containing additive solution)

4 parts by mass of fine particles (AEROSILR812, manufactured by AEROSIL Co., Ltd., primary average particle diameter: 7nm, apparent specific gravity 50g/L)

48 parts by mass of methylene chloride

48 parts by mass of ethanol

After the above was stirred and mixed by a dissolver for 50 minutes, dispersion was performed by a high pressure emulsifier (Manton Gorlin).

Further, the dispersion is performed by an attritor in such a manner that the particle diameter of the secondary particles is a given size.

This was filtered through FINEMET NF manufactured by Nippon Seikaga K.K., to prepare a fine particle-added solution.

Preparation of dopant CAP-1

Cellulose acetate propionate (CAP: degree of substitution of acetyl X, degree of substitution of propionyl Y: X + Y: 2.45/Y: 1.0) 100 parts by mass

Dichloromethane 200 parts by mass

10 parts by mass of ethanol

3 parts by mass of particulate additive solution

Next, the dope P-1 was uniformly cast on a stainless steel belt support at a temperature of 33 ℃ and a width of 1800mm using an endless belt casting apparatus. The temperature of the stainless steel belt was controlled to 30 ℃.

On the stainless steel tape support, the solvent was evaporated until the amount of the residual solvent in the film cast (cast) was 75%, and then, peeling was performed from the stainless steel tape support at a peeling tension of 130N/m.

The Cellulose Acetate Propionate (CAP) film obtained by peeling was stretched by 20% in the width direction using a tenter while being heated at 160 ℃. Subsequently, the drying zone is conveyed by a plurality of rollers while drying is completed. The drying temperature was set at 130 ℃ and the conveying tension was set at 100N/m. After drying, the sheet was cut to 2000mm in width, and knurling was performed on both ends of the sheet to 15mm in width, and the sheet was wound into a roll in the same manner as in the production of the roll of the sheet in example 1, through the atmospheric pressure plasma treatment step.

(example 7)

A film roll was prepared in the same manner except that the film was cut and made into a 1.3m wide film roll in the preparation of the film roll of example 1.

(example 8)

A film roll was produced in the same manner except that the stretching ratio was set to 60% in the production of the film roll of example 1 and a film roll having a width of 2500mm was produced.

(example 9)

A film roll was produced in the same manner except that the casting dope amount was adjusted and the film thickness was set to 20 μm in the production of the film roll of example 1.

(example 10)

A film roll was produced in the same manner except that the casting dope amount was adjusted and the film thickness was set to 15 μm in the production of the film roll of example 1.

(example 11)

A film roll was prepared in the same manner except that the modification of the back surface was performed not by plasma treatment but by the following procedure in the preparation of the film roll of example 1.

Corona discharge treatment

The roll is subjected to a corona discharge treatment at point B. The distance from the dielectric in the corona discharge was set to 2mm, and the electron ejection amount was set to 500W/m²/min。

(example 12)

A film roll was produced in the same manner as in the production of the film roll of example 1, except that the fine particle dispersion used in example 1 was changed to the fine particle dispersion described below.

8 parts by mass of fine particles (AEROSILR 812: manufactured by AEROSIL CORPORATION, Japan, primary average particle diameter: 7nm, apparent specific gravity: 50g/L)

72 parts by mass of methylene chloride

10 parts by mass of methanol

10 parts by mass of a cyclic polyolefin solution (dope D-1)

(example 13)

A film roll was produced in the same manner as in the production of the film roll of example 4, except that the fine particle dispersion used in example 1 was changed to the fine particle dispersion described below.

2 parts by mass of fine particles (AEROSILR 812: manufactured by AEROSIL CORPORATION, Japan, primary average particle diameter: 7nm, apparent specific gravity: 50g/L)

78 parts by mass of methylene chloride

10 parts by mass of methanol

10 parts by mass of a cyclic polyolefin solution (dope D-1)

Evaluation

< measurement of static Friction coefficient >

A part of each of the prepared film rolls was cut out, and the static friction coefficient was measured by the following measuring machine.

Static friction tester: eastern sperm mechanism FRICTION TESTER TR

Friction measurement conditions: the prepared film (knurled part (part A), non-knurled part (surface C) and surface-modified part (part A or part B) were superposed on each other, and the load was 0.166g/mm²、0.83g/mm²And 1.66g/mm²The coefficient of static friction was measured. The values were set as the average of the static friction coefficients under the respective 3 kinds of loads.

In the table, for a/B, the measurement was performed in the same manner with the position a set as the upper side and the position B set as the lower side.

In table 1, the case where relational expressions (1) and (2) of the present invention are satisfied is described as o, and the case where the relational expressions are not satisfied is described as x.

< evaluation of Rib >

The rib (gauge band) is a band-shaped protrusion that is generated on the surface of the film roll and is parallel to the circumferential direction of the film roll. The sticking of the films to each other due to the thick portions of the films, blocking, and the like, overlap each other every turn to generate a rib. When the web is subjected to rib forming, marks are left on the surface of the film, and the quality of the film or the optical properties of the film tend to be lowered.

For the evaluation, whether or not the rib was generated and the degree thereof were confirmed by visual evaluation.

< evaluation of roll offset >

As a roll offset evaluation, the film roll obtained was subjected to a vibration test.

The vibration test was performed in such a manner that the film roll was immediately subjected to an impact of 8G.

After the impact is applied, the film roll is checked, and if there is a portion that is deviated by 5mm or more from the initial winding position, it is determined as "there is a roll deviation".

The composition and evaluation results of the above film roll are shown in table 1.

As is apparent from table 1, in the film rolls of examples 1 to 13 of the present invention, the static friction coefficient was controlled so as to satisfy the relational expressions (1) and (2) as the relationship between the static friction coefficients of the respective portions, whereby film rolls having excellent blocking (rib) resistance and roll offset resistance as compared with the film rolls of the comparative examples were obtained. Further, as is clear from comparison between example 1 and example 12, and between example 4 and example 13, the blocking resistance and the rolling offset resistance can be further improved by controlling the static friction coefficient so as to satisfy the formula (3).

Description of the symbols

1 film

2 approach roll

3 touch roller

4 ring with carved patterns

5 Metal rear roller

6 rubber rear roller

7 laser

8 convex part (knurling)

10 film roll

A site A

B site B

C face C

A1 dissolving kettle

A2, A5, A11 and A14 liquid feeding pumps

A3, A6, A12 and A15 filter

A4, A13 storage tank

A8, A16 catheter

A10 additive is with cauldron of feeding

A20 confluence pipe

A21 mixer

A30 die head

A31 Metal support

A32 Web

A33 peeling position

A34 tenter device

A35 roller drying device

A36 roller

A37 coiler

A41 storage tank

A43 pump

A44 filter

B10 film production line

B11 film manufacturing device

B12 coiling device

B13 film

B15 knurling section

B19 coiling shaft

B20 roll core holder

B21 roll core

B22 turret

Guide rollers B23 and B24

B25 dancer roll

B26 axle mechanism

B27 encoder

B28 axle mechanism

B29 swing part

B30 coiling motor

B31 controller

B32 tension adjusting part

B39 winding information input unit

B40 LUT memory section

B41 switching roll length determining unit

Length measuring part for roll B42

B43 switching determination unit

Claims

1. A film roll having a knurled portion at least at both ends in the width direction of the film, wherein,

satisfies the following relational expressions (1) and (2),

Formula (2) a < b.

2. The film roll according to claim 1,

a and b satisfy the following relational expression (3),

formula (3)0.3< a/b < 0.8.

3. The roll of film according to claim 1 or claim 2,

the width of the film is in the range of 1.3-3.0 m.

4. The film roll according to any one of claim 1 to claim 3,

the film thickness of the film is within the range of 10-45 [ mu ] m.

5. The film roll according to any one of claim 1 to claim 4,

the film contains a cyclic olefin resin or an acrylic resin.

6. A method for producing a film roll according to any one of claims 1 to 5, wherein,

the manufacturing method comprises a step of performing surface modification treatment on at least the site A or the site B.

7. The method of manufacturing a film roll according to claim 6,

the surface modification treatment is performed only at the site B.

8. The method of manufacturing a film roll according to claim 6,

the surface modification treatment is performed at both the site a and the site B.

9. The method for manufacturing a film roll according to any one of claims 6 to 8,

the knurled portion is formed by laser knurling.