CN110000863B

CN110000863B - Method for producing monolithic film

Info

Publication number: CN110000863B
Application number: CN201811548762.XA
Authority: CN
Inventors: 中原亮; 八幡直树
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2017-12-18
Filing date: 2018-12-18
Publication date: 2020-05-12
Anticipated expiration: 2038-12-18
Also published as: CN110000863A; JP2019107764A; KR20190073283A; KR102035432B1; TW201930089A; JP2019107761A; TWI671202B; JP6420511B1

Abstract

A method for producing a monolithic film, comprising a cutting step of cutting a multilayer film having n (n is an integer of 1 or more) adhesive layers to obtain a monolithic film from the multilayer film, wherein the cutting step comprises: and a press-cutting step of cutting the multilayer film by causing a press-cutting blade to enter the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film, wherein when any of the pressure-sensitive adhesive layers is a reference pressure-sensitive adhesive layer in the n pressure-sensitive adhesive layers, the speed V (μm/sec) of the press-cutting blade at the 1 st surface of the multilayer film satisfies the relational expression (1). t/V < 1/omega₁(1) [ in the relational expression (1), t represents the thickness (. mu.m) of the multilayer film,. omega.₁The storage modulus calculated based on the measurement value of dynamic viscoelasticity measurement was 3.0X 10⁵(Pa), and the measured value of the dynamic viscoelasticity measurement is a measured value of the dynamic viscoelasticity measurement by frequency sweep at a temperature of 20 ℃ of the reference pressure-sensitive adhesive layer]。

Description

Method for producing monolithic film

Technical Field

The present invention relates to a method for producing a single sheet film by obtaining a single sheet film from a multilayer film having an adhesive layer, a device for producing the multilayer film, and a method for cutting the multilayer film.

Background

Conventionally, as one of methods for cutting a multilayer film including a polarizing plate and the like, a method of cutting using a press blade (japanese patent application laid-open (jp 2015) -33727 (patent document 1)) has been known. Patent document 1 describes: by using a press-cutting blade having a blade portion with a surface roughness in a specific numerical value range as a press-cutting blade used for cutting a multilayer film, the occurrence of burrs on the cut surface can be suppressed.

Disclosure of Invention

As described in patent document 1, when the multilayer film is cut with a pressure cutting blade, fine irregularities in the form of stripes may be generated in the vicinity of the cut portion on the surface of the multilayer film. When a multilayer film is cut to produce a single film for use in mobile devices such as smartphones, the size of the single film is small and characters and images to be displayed are small, so that a screen is seen from a very short distance, and even minute irregularities are easily noticeable and may easily become a defect in appearance. The present inventors have studied and found that such stripe-like minute irregularities are likely to occur when a multilayer film has a pressure-sensitive adhesive layer. Further, intensive studies have been made, and a method capable of suppressing such stripe-like minute irregularities has been found, thereby completing the present invention.

The invention aims to provide a method and a device for manufacturing a single-piece film and a method for cutting a multilayer film, wherein the generation of stripe-shaped micro concave-convex can be inhibited.

The present invention provides a method and an apparatus for producing a monolithic film and a method for cutting a multilayer film, which are described below.

[ 1] A method for producing a single sheet film,

which comprises a cutting step of cutting a multilayer film having n (n is an integer of 1 or more) adhesive layers to obtain a single film from the multilayer film,

the cutting step includes: a press-cutting step of cutting the multilayer film by causing a press-cutting blade to enter the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film,

in the case where any of the pressure-sensitive adhesive layers of the n pressure-sensitive adhesive layers is used as a reference pressure-sensitive adhesive layer, a velocity V (μm/sec) of the pressure-cutting blade on the 1 st surface of the multilayer film satisfies the following relational expression (1).

t/V＜1/ω₁(1)

[ in the relational expression (1), t represents the thickness (. mu.m) of the multilayer film,. omega.₁The storage modulus calculated based on the measurement value of dynamic viscoelasticity measurement was 3.0X 10⁵(Pa), and the measured value of the dynamic viscoelasticity measurement is a measured value of the dynamic viscoelasticity measurement by frequency sweep at a temperature of 20 ℃ of the reference pressure-sensitive adhesive layer.]

[ 2] the method for producing a monolithic film according to [ 1], wherein,

in the adhesive layer, an adhesive layer having the smallest storage modulus at a temperature of 20 ℃ and an angular frequency of 1,000 rad/sec was used as the reference adhesive layer.

[ 3] the method for producing a monolithic film according to [ 1], wherein,

the multilayer film has a separation film having an outermost layer, and an adhesive layer under the outermost layer exposed at the outermost surface by peeling of the separation film,

and taking the adhesive layer below the outermost layer as the reference adhesive layer.

[ 4] the method for producing a monolithic film according to any one of [ 1] to [ 3], wherein,

the multilayer film has a polarizing plate.

[ 5 ] an apparatus for producing a single sheet film,

which comprises a cutting part for cutting a multilayer film having n (n is an integer of 1 or more) adhesive layers to obtain a single film from the multilayer film,

the cutting unit includes: a press-cutting blade arranged so as to be capable of entering the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film, and a control unit for controlling the operation of the press-cutting blade,

in the case where any one of the pressure-sensitive adhesive layers of the n pressure-sensitive adhesive layers is used as a reference pressure-sensitive adhesive layer, the control unit controls a speed V (μm/sec) of the pressure-cutting blade on the 1 st surface of the multilayer film so as to satisfy the following relational expression (1).

t/V＜1/ω₁(1)

[ 6 ] the apparatus for producing a monolithic film according to [ 5 ], wherein,

[ 7 ] the apparatus for producing a monolithic film according to [ 5 ], wherein,

[ 8 ] the apparatus for producing a monolithic film according to any one of [ 5 ] to [ 7 ], wherein the multilayer film has a polarizing plate.

[ 9 ] A method for cutting a multilayer film,

which is a cutting method for cutting a multilayer film having n (n is an integer of 1 or more) adhesive layers,

the cutting method comprises the following steps: a press-cutting step of cutting the multilayer film by causing a press-cutting blade to enter the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film,

in the case where any of the n pressure-sensitive adhesive layers is used as a reference pressure-sensitive adhesive layer, the speed V (μm/sec) of the pressure-cutting blade on the 1 st surface of the multilayer film satisfies the following relational expression (1).

t/V＜1/ω₁(1)

[ 10 ] the method for cutting a multilayer film according to [ 9 ], wherein,

[ 11 ] the method for cutting a multilayer film according to [ 9 ], wherein,

[ 12 ] the method for cutting a multilayer film according to any one of [ 9 ] to [ 11 ], wherein the multilayer film has a polarizing plate.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description, which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1(a) -1(c) are schematic views schematically showing an example of a cutting step for obtaining a single film from a multilayer film.

Fig. 2(a) -2(b) are schematic diagrams schematically showing an example of a cutting step for obtaining a single film from a multilayer film.

Fig. 3(a) -3(c) are schematic views schematically showing an example of a cutting step for obtaining a single sheet from a multilayer film.

Fig. 4 is a cross-sectional view schematically showing a cutting device having a press cutting blade.

Fig. 5 is a sectional view (a), (b) a perspective view from below, and (c) a bottom view showing an example of the pressure cutting blade member.

Fig. 6(a) -6(c) are schematic diagrams showing the cutting operation by the pressure cutting blade.

Fig. 7 is a bottom view of the pressure cutting blade member different from fig. 5.

Fig. 8 is a conceptual diagram illustrating stripe-like minute irregularities generated in the vicinity of a cut surface of a multilayer film surface.

Fig. 9 is a schematic cross-sectional view schematically showing an example of a specific layer structure of the multilayer film.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scale is appropriately adjusted to facilitate understanding of each component, and the scale of each component shown in the drawings does not necessarily coincide with the scale of the actual component.

[ method for producing Single sheet film ]

The method for manufacturing a monolithic film according to the present embodiment includes: and a cutting step of cutting the multilayer film having n (n is an integer of 1 or more) adhesive layers to obtain a single film from the multilayer film. The cutting step includes: and a press-cutting step of cutting the multilayer film by inserting a press-cutting blade into the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film.

In the press-cutting step, when any of the n pressure-sensitive adhesive layers is used as a reference pressure-sensitive adhesive layer, the speed V (μm/sec) of the press-cutting blade on the 1 st surface of the multilayer film satisfies the following relational expression (1).

t/V＜1/ω₁(1)

In the above relational expression (1), t represents the thickness (. mu.m) of the multilayer film, and ω₁The storage modulus calculated based on the measurement value of dynamic viscoelasticity measurement was 3.0X 10⁵(Pa), and the measured value of the dynamic viscoelasticity measurement is a measured value of the dynamic viscoelasticity measurement by frequency sweep at a temperature of 20 ℃ of the reference pressure-sensitive adhesive layer.

By making the speed V (μm/sec) of the press-cutting blade on the 1 st surface of the multilayer film satisfy the above relational expression (1), it is possible to suppress the occurrence of minute irregularities in the reference adhesive layer in the press-cutting step, and as a result, it is possible to suppress the occurrence of stripe-like minute irregularities in the vicinity of the cut surface of the multilayer film. The reference pressure-sensitive adhesive layer is preferably a pressure-sensitive adhesive layer in which fine irregularities are likely to occur in the press-cutting step. The details of the method for selecting the reference adhesive layer will be described later.

The present inventors have found that the viscoelastic properties of the pressure-sensitive adhesive layer in the die-cutting step are related to the susceptibility to fine irregularities in the pressure-sensitive adhesive layer. The minute irregularities generated in the pressure-sensitive adhesive layer cause minute irregularities generated on the surface of the multilayer film. The viscoelastic properties of the pressure-sensitive adhesive layer in the pressure-cutting step depend on the speed of passage of the pressure-sensitive adhesive layer through the pressure-sensitive adhesive blade. Intensive studies were conducted on the basis of the following assumptions, so as to find the above-mentioned relational expression (1): if the estimated time t/V required for the press blade to pass through the 1 st surface of the multilayer film until reaching the 2 nd surface is sufficiently short in relation to the passing speed, the viscoelastic properties of the adhesive layer maintain appropriate properties,it is difficult to generate fine irregularities in the pressure-sensitive adhesive layer, and as a result, it is difficult to generate fine irregularities also in the vicinity of the cut surface of the multilayer film. The speed V (μm/sec) is a speed of the pressure-cutting blade on the 1 st surface of the multilayer film, but since the speed of the pressure-cutting blade in the multilayer film can be controlled so as to be substantially the same, it can be considered that the time required for the pressure-cutting blade to pass through the 1 st surface of the multilayer film and reach the 2 nd surface substantially coincides with the estimated time t/V. Generally, the estimated time t/V is set to be less than 9.0X 10^－3(second), it is preferably less than 2.5X 10 in suppressing the generation of fine irregularities on the surface of the multilayer film^－3(seconds). In general, the estimated time t/V is 1.0X 10^－4(second) or more.

From the viewpoint of further suppressing the occurrence of fine irregularities in the pressure-sensitive adhesive layer, it is preferable that, in the press-cutting step, when any one of the pressure-sensitive adhesive layers of the n layers is used as the reference pressure-sensitive adhesive layer, the speed V (μm/sec) of the press-cutting blade on the 1 st surface of the multilayer film satisfies the above relational expression (1), and more preferably satisfies the following relational expression (2).

t/V＜1/ω₂(2)

In the above relational expression (2), t represents the thickness (. mu.m), ω, of the multilayer film in the same manner as in the relational expression (1)₂The storage modulus calculated based on the measurement value of the dynamic viscoelasticity measurement was 6.0X 10⁵(Pa), and the measured value of the dynamic viscoelasticity measurement is a measured value of the dynamic viscoelasticity measurement by frequency sweep at a temperature of 20 ℃ of the reference pressure-sensitive adhesive layer.

< cutting step >

Fig. 1 to 3 are schematic views each schematically showing an example of a cutting step of cutting a multilayer film to obtain a single film from the multilayer film. In fig. 1 to 3, broken lines indicate cutting lines in the cutting step. In the example shown in fig. 1, a long multilayer film 10a is cut in a direction orthogonal to the longitudinal direction by a cutting blade having a straight cutting edge (fig. 1(a)) to obtain a multi-layer film 10b which is cut into pieces (fig. 1(b)), and then the multi-layer film 10b which is cut into pieces is cut in the longitudinal direction of the original multilayer film 10a by a cutting blade having a straight cutting edge (fig. 1(b)), thereby obtaining a single-piece film 11 having a desired size (fig. 1 (c)).

In the example shown in fig. 2, a long multilayer film 10a is punched out and cut with a die-shaped press blade (fig. 2(a)), and a single film 11 having a desired size is obtained (fig. 2 (b)).

In the example shown in fig. 3, a long multilayer film 10a is cut in a direction orthogonal to the longitudinal direction by a press blade having a straight cutting edge (fig. 3 a) to obtain a multi-layer film 10c which is formed into small pieces (fig. 3 b), and then a single-piece film 11 having a desired size is punched out by a die-shaped press blade (fig. 3 c).

The cutting direction in the cutting step shown in fig. 1 to 3 is not particularly limited, and when a multilayer film having orientation characteristics is cut, the cutting direction is determined so as to obtain a single sheet film 11 having desired orientation characteristics.

In each of the examples shown in fig. 1 to 3, 1 or more single films are obtained from the multilayer film by cutting 1 or more times. The number of cutting in the cutting step is not limited. In addition, although the case where all the cutting in the cutting step is the press-cutting step has been described above, any cutting is not limited as long as it is the press-cutting step, and the cutting step may be a cutting step including cutting by a laser, cutting by rotation of a circular blade, or the like, in addition to the press-cutting step. That is, the obtained single sheet film may be a single sheet film including a cut surface in the press-cutting step. In the case where the press-cutting step is used, stripe-like fine irregularities are likely to be generated in the vicinity of the cut portion on the surface of the multilayer film, but in the present embodiment, even if all the cutting steps are performed in the press-cutting step, the generation of such stripe-like fine irregularities can be suppressed.

< Press cutting Process >

Fig. 4 is a schematic view schematically showing a cutting device having a press blade. The press-cutting step according to the present embodiment can be performed by the cutting device 20 shown in fig. 4. The cutting device 20 includes: a press-cutting blade member 21 having a press-cutting blade, a control unit 24 for controlling the vertical movement of the press-cutting blade member 21, and a mounting table 23 on which the multilayer film 10 is mounted and on which the blade plate 22 is provided. The multilayer film 10 is placed on the placement table 23 in contact with the blade plate 22. In the multilayer film 10 placed on the placing table 23, a surface in contact with the blade plate 22 is a 2 nd surface 102, and an upper surface opposite to the 2 nd surface 102 is a 1 st surface 101. In the press-cutting step, the press-cutting blade member 21 is moved downward, whereby the press-cutting blade enters the multilayer film 10 from the 1 st surface 101 toward the 2 nd surface 102 of the multilayer film 10. Thereafter, the cutting blade member 21 is moved upward, whereby the cutting blade is separated from the multilayer film 10. The multilayer film 10 is cut by the vertical movement of the cutter member 21.

Fig. 5(a) is a sectional view showing in detail a pressure cutting blade member 21a as an example of the pressure cutting blade member 21 shown in fig. 4. Fig. 5(b) is a perspective view from the bottom of the pressure cutting blade member 21a, and a sectional view a-a in fig. 5(b) corresponds to fig. 5 (a). Fig. 5(c) shows a bottom view of the pressure cutting blade member 21 a. The pressure cutting blade member 21a includes: a press-cutting blade 211a having a linear blade portion, a holding portion 213a for holding the press-cutting blade 211a, and an elastic body 212a disposed below the holding portion 213 a. The lowermost surface of the elastic body 212a is located at the same position as the edge portion of the press-cutting blade 211a or below the edge portion of the press-cutting blade 211 a.

Fig. 6(a) to (c) are schematic diagrams showing the cutting operation by the pressure cutting blade 211a when the multilayer film 10 is cut by the cutting device including the pressure cutting blade member 21a shown in fig. 5(a) to (c). In the cutting operation, the pressure cutting blade member 21a moves downward (fig. 6(a)), and the lowermost surface of the elastic body 212a of the pressure cutting blade member 21a comes into contact with the 1 st surface 101 of the multilayer film 10 (fig. 6 (b)). Thereafter, the press blade member 21a further moves downward, whereby the elastic body 212a contracts on the 1 st surface 101 of the multilayer film 10, and only the press blade 211a enters the multilayer film 10 from the 1 st surface 101 of the multilayer film 10 and continues to enter until reaching the blade plate 22 (fig. 6 (c)). When the press-cutting blade 211a reaches the blade support plate 22, the moving direction of the press-cutting blade member 21 is switched to the upward direction, and the press-cutting blade 211a is pulled out from the multilayer film 10. By the above cutting operation, the multilayer film 10 is cut in the stacking direction.

The press blade 211a of the press blade member 21a is not limited to the press blade capable of linearly cutting the multilayer film 10 as shown in fig. 5(a) to (c), and may be designed so that desired cutting becomes possible. A die-like press-cutting blade capable of punching out a rectangular single film from the multilayer film 10 may be used. Fig. 7 is a bottom view of an example of a die-shaped blade member including a die-shaped blade. The pressure-cutting blade member 21b shown in fig. 7 includes a pressure-cutting blade 211b, a holding member, and an elastic body 212b, and has the same configuration as the pressure-cutting blade member 21a shown in fig. 5 except that the shape of the pressure-cutting blade 211b is different, and the multilayer film 10 can be cut by the same method.

As the press-cutting

edges

211a, 211b, Thomson edges (Japanese: トムソン edges) are preferably used. The thomson blade may be a thomson blade having a resin-processed surface. The

elastic bodies

212a and 212b are not limited as long as they can be shrunk on the surface of the multilayer film and can hold the multilayer film 10 together with the blade plate 22 during cutting to fix the multilayer film, and a porous material such as urethane foam, a soft material such as urethane rubber, or the like is preferably used.

In the cutting device according to the present embodiment, the control unit 24 controls the downward movement speed of the pressure cutting blade member 21 so that the speed V (μm/sec) of the pressure cutting blade on the 1 st surface of the multilayer film satisfies the relational expression (1).

< other working procedures >

The method for producing a monolithic film according to the present embodiment may include steps other than the cutting step described above, and examples thereof include: a multilayer film manufacturing step of manufacturing a multilayer film, an unwinding step of unwinding a multilayer film wound in a roll, a conveying step of conveying a multilayer film or a single film, a drying step of drying a multilayer film or a single film, and the like.

< multilayer film >

The multilayer film is not particularly limited if it has an adhesive layer. The multilayer film is, for example, an optical laminate film. This is because, in the case of an optical laminated film, even a minute unevenness is likely to cause a problem in appearance. The thickness of the multilayer film is, for example, 5 to 3000 μm, preferably 20 to 500 μm. The layer structure of the multilayer film is preferably a layer structure in which the adhesive layer is not exposed on the outermost surface, so that dirt is less likely to adhere to the adhesive layer in the cutting step.

When the multilayer film has an adhesive layer, if the multilayer film is cut with a pressure-cutting blade, stripe-like fine irregularities are likely to occur in the vicinity of the cut surface of the multilayer film, but the occurrence of such fine irregularities can be suppressed by the method for producing a monolithic film according to the present embodiment. More specifically, the minute irregularities are generally stripe-shaped ridges extending in a direction substantially parallel to the cut surface, and are often generated on the 2 nd surface in contact with the blade plate. The mechanism of generating the fine unevenness is not clear, but one conceivable mechanism is: the entry of the pressure-cutting blade causes different shear stresses in each layer, and the adhesive layer is locally deformed due to the difference in shear stresses acting on the two layers in contact with the adhesive layer. Such local deformation is presumed to be caused by the fact that the adhesive layer is softer than the other layers.

Fig. 8 is a conceptual diagram illustrating stripe-like minute irregularities generated in the vicinity of a cut surface on the surface of a multilayer film. The mechanism of generation of fine irregularities described using fig. 8 is one conceivable mechanism, and the fine irregularities suppressed by the method of producing a monolithic film according to the present embodiment are not limited to the irregularities generated by such a mechanism, nor to the fine irregularities schematically shown in fig. 8. In fig. 8, the multilayer film 10 to be cut is assumed to be a multilayer film including a layer 101, a pressure-sensitive adhesive layer 102, and a layer 103. When the pressure-cutting blade 211 is inserted into the multilayer film 10, different shear stresses are generated in each layer, and the pressure-sensitive adhesive layer 102 is softer than the

adjacent layers

101 and 103, so that the local part in the vicinity of the cut surface of the pressure-sensitive adhesive layer 102 slightly bulges due to the difference in shear stress acting on the two

layers

101 and 103, thereby forming the ridges 102 a. Since the ridges 102a of the adhesive layer 102, the layer 103 adjacent to the adhesive layer 102 may slightly swell to form the ridges 103 a. In this manner, the ridges 102a formed on the adhesive layer 102 and the ridges 103a formed on the layer 103 cause stripe-like irregularities that are visually recognizable in appearance.

(adhesive layer)

The pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive composition containing a resin such as a (meth) acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin as a main component. Among them, an adhesive composition containing a (meth) acrylic resin as a base polymer excellent in transparency, weather resistance, heat resistance and the like is suitable. The adhesive composition may be an active energy ray-curable type or a heat-curable type.

As the (meth) acrylic resin (base polymer) used in the adhesive composition, for example, a polymer or copolymer in which 1 or 2 or more kinds of (meth) acrylic esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are used as monomers is suitably used. It is preferred to copolymerize the polar monomer with the base polymer. Examples of the polar monomer include: monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

The adhesive composition may be an adhesive composition containing only the above-mentioned base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include: a metal ion having a valence of 2 or more, which forms a metal carboxylate with a carboxyl group; polyamine compounds forming amide bonds with carboxyl groups; polyepoxy compounds and polyhydric alcohols forming ester bonds with carboxyl groups; and a polyisocyanate compound forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.

The active energy ray-curable adhesive composition means: the pressure-sensitive adhesive composition has a property of being cured by irradiation with an active energy ray such as an ultraviolet ray or an electron beam, has an adhesive property even before irradiation with an active energy ray and can be bonded to an adherend such as a film, and has a property of being cured by irradiation with an active energy ray and capable of adjusting the bonding force. The active energy ray-curable adhesive composition is preferably an ultraviolet-curable adhesive composition. The active energy ray-curable adhesive composition further contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. Further, a photopolymerization initiator, a photosensitizer and the like may be contained as necessary.

The adhesive composition may contain additives such as fine particles, beads (resin beads, glass beads, and the like), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powders, other inorganic powders, and the like), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, preservatives, and photopolymerization initiators for imparting light scattering properties.

The organic solvent diluted solution of the adhesive composition may be applied to a substrate and dried to form the adhesive composition. In the case of using an active energy ray-curable pressure-sensitive adhesive composition, a cured product having a desired degree of curing can be formed by irradiating the formed pressure-sensitive adhesive layer with an active energy ray.

The thickness of the adhesive layer may be, for example, 1 to 40 μm. When the thickness of the pressure-sensitive adhesive layer is 1 to 40 μm, the stripe-like fine irregularities are likely to be generated by the press-cutting step, but according to the method for producing a monolithic film of the present embodiment, even when the thickness of the pressure-sensitive adhesive layer is 1 to 40 μm, the generation of the stripe-like fine irregularities can be suppressed.

The adhesive layer may have a storage modulus of 0.15 to 1MPa at a temperature of 20 ℃ and an angular frequency of 1,000 rad/sec. In the case where the pressure-sensitive adhesive layer has such a storage modulus, fine irregularities are likely to occur in many cases when the pressure-sensitive adhesive layer is softer than other layers, but according to the method for producing a monolithic film of the present embodiment, even when the storage modulus of the pressure-sensitive adhesive layer at 20 ℃ is 0.15 to 1MPa, the occurrence of fine irregularities can be suppressed.

The storage modulus of the pressure-sensitive adhesive layer can be measured using a commercially available viscoelasticity measuring apparatus, for example, a viscoelasticity measuring apparatus "DYNAMIC ANALYZER RDA II" manufactured by REMOMETRIC.

Examples of the method for adjusting the storage modulus to the above range include: an active energy ray-curable adhesive composition (preferably an ultraviolet-curable adhesive composition) is formed by adding an oligomer, specifically, a urethane (meth) acrylate oligomer, to an adhesive composition containing a base polymer or further containing a crosslinking agent. More preferably, the adhesive layer is moderately cured by irradiation with active energy rays.

(reference adhesive layer)

The multilayer film used in or produced by the method for producing a monolithic film according to the present embodiment has n (n is an integer of 1 or more) adhesive layers. When the pressure-sensitive adhesive layer included in the multilayer film is 1 layer, the speed of the pressure-cutting blade is controlled so as to satisfy the above relational expression (1) with the pressure-sensitive adhesive layer as a reference pressure-sensitive adhesive layer. When a plurality of adhesive layers are included in the multilayer film, it is preferable to use an adhesive layer that is likely to cause unevenness in the press-cutting step as a reference adhesive layer. The inventors of the present invention have found that the pressure-sensitive adhesive layers exemplified in i) and ii) below are likely to have irregularities in the press-cutting step, and are further exemplified as reference pressure-sensitive adhesive layers.

i) An adhesive layer having a minimum storage modulus at a temperature of 20℃,

ii) in the constitution of a multi-layer film having a separation film of the outermost layer and an adhesive layer under the outermost layer exposed on the outermost surface by peeling of the separation film, the adhesive layer under the outermost layer.

In the method for producing a single sheet film according to the present embodiment, even when any one of the n pressure-sensitive adhesive layers is used as the reference pressure-sensitive adhesive layer, the speed of the pressure-cutting blade preferably satisfies the relational expression (1).

(layer constitution example of multilayer film)

Fig. 9 is a schematic cross-sectional view schematically showing an example of a specific layer configuration of a multilayer film used in the method for producing a monolithic film according to the present embodiment or produced. The multilayer film 10d has laminated thereon: a polarizing plate 100 including a polarizing plate (not shown in fig. 9), a protective film 60 laminated on one surface thereof, a 1 st adhesive layer 31 laminated on the other surface thereof, and a releasable separation film 70 for temporarily protecting the 1 st adhesive layer 31 on the outer surface of the 1 st adhesive layer 31. On the other hand, the surface on the protective film 60 side (the surface to which the protective film 60 is attached) and the surface on the 1 st adhesive layer 31 side (the surface to which the 1 st adhesive layer 31 is attached) of the polarizing plate 100 may be, for example: protective films, other optical films, or surfaces of layers attached to the films.

The protective film 60 may be laminated by bonding one surface thereof to the polarizing plate 100 and by leaving the other surface thereof to be non-adhesive. As such a pellicle film 60, a so-called self-adhesive pellicle film can be cited. The self-adhesive pellicle is, for example, a resin film including a non-adhesive resin layer 61 formed of a non-adhesive resin and an adhesive resin layer 62 formed of a self-adhesive resin. Examples of the self-adhesive pellicle include "TORETEC" (manufactured by tomi film processing corporation). In addition, there can be mentioned: the polarizing plate 100 includes a resin film (base film) 61 and a 2 nd pressure-sensitive adhesive layer 62 laminated thereon, and the laminated protective film is bonded to the polarizing plate 100 through the pressure-sensitive adhesive layer. In the case of a pellicle 60 having a 2 nd adhesive layer 62, it will generally have a higher storage modulus than that of the 1 st adhesive layer.

The polarizing plate 100 is a polarizing element including at least a polarizer and the 1 st adhesive layer 31, and usually further includes a protective film attached to one surface or both surfaces of the polarizer. The polarizing plate 100 may further include, in addition to the protective film: other optical films such as films having optical functions different from those of the polarizing plate, and layers added to films such as optical layers. Various optical films including a protective film may be bonded to each other with an adhesive layer or an adhesive layer interposed therebetween. The polarizing plate 100 may or may not include an adhesive layer. When the adhesive layer is included, the adhesive layer included in the polarizing plate 100 is one of n adhesive layers included in the multilayer film.

The thickness of the polarizing plate 100 is usually 20 to 200. mu.m, preferably 30 to 150. mu.m, more preferably 40 to 120. mu.m, and still more preferably 50 to 100. mu.m.

The multilayer film 10d may be a multilayer film produced by a so-called roll-to-roll method in which, for a raw material film that is unwound from a roll and conveyed, another raw material film that is likewise unwound from a roll is laminated, and the obtained long laminated film is wound into a roll, or may be a multilayer film obtained by cutting the multilayer film. In the method for producing a single sheet film according to the present embodiment, the multilayer film 10d is cut in the cutting step to produce a single sheet film.

When the multilayer film 10d includes both the 1 st pressure-sensitive adhesive layer 31 and the 2 nd pressure-sensitive adhesive layer 62 as pressure-sensitive adhesive layers, the 1 st pressure-sensitive adhesive layer 31 on which the releasable separation film 70 is laminated is generally likely to have minute irregularities in the press-cutting step. This is thought to be due to: the separation film 70 is once peeled or deviated by the shear stress, and the displacement of the adhesive layer is fixed.

When the multilayer film 10d is cut by the cutting device shown in fig. 4, the protective film 60 side may be set as the 1 st surface and the separation film 70 side may be set as the 2 nd surface, and the multilayer film may be cut by being placed on the placing table 23 so that the separation film 70 comes into contact with the blade plate 22; the separation film 70 side may be the 1 st surface, the seed film 60 side may be the 2 nd surface, and the resin film 61 constituting the seed film 60 may be placed on the placing table 23 so as to be in contact with the blade plate 22 and cut. With the method for producing a single sheet film according to the present embodiment, even when the multilayer film 10d is placed in any direction, the occurrence of minute unevenness in stripes due to the press-cutting step can be suppressed.

The shape of the uncut multilayer film 10d is not particularly limited, and is typically a long strip (tape). The length in the longitudinal direction and the length in the width direction of the uncut multilayer film 10d are not particularly limited, and usually, the length in the longitudinal direction of the multilayer film 10d is 100 to 20,000m, and the length in the width direction is 1,000 to 1,500 mm. The multilayer film 10d may be subjected to a press-cutting step after being cut into small pieces of the multilayer film 10 d. In this case, the shape of the small multilayer film 10d is not particularly limited, and preferably has a square shape having long sides and short sides, typically a rectangular shape. The length of the long side and the short side is not particularly limited, and for example, the length of the long side is 900mm or less and the length of the short side is 800mm or less.

The size, shape, and cut-out angle of the monolithic film are not particularly limited. The monolithic film is preferably square in shape, more preferably square in shape with long sides and short sides. The square shape is preferably rectangular. When the single sheet film is rectangular, the length of the long side is, for example, 50mm to 300mm, preferably 70mm to 200 mm. The length of the short side is, for example, 30mm to 200mm, preferably 40mm to 100 mm. The smaller the size of the single sheet film, the more likely the minute irregularities generated on the surface of the single sheet film near the cut surface in the press-cutting step become apparent defects, but according to the method for producing a single sheet film of the present embodiment, even when the size of the single sheet film is small, the generation of minute irregularities can be prevented.

(1) Polarizing plate

The polarizing plate is an absorption-type polarizing plate having a property of absorbing linearly polarized light having a plane of vibration parallel to an absorption axis thereof and transmitting linearly polarized light having a plane of vibration orthogonal to the absorption axis (parallel to a transmission axis), and a polarizing film in which a dichroic dye is adsorbed and oriented to a polyvinyl alcohol-based resin film can be suitably used. The polarizing plate can be manufactured by, for example, a method including the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing the polyvinyl alcohol resin film with a dichroic dye to allow the polyvinyl alcohol resin film to adsorb the dichroic dye; treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution.

The thickness of the polarizing plate is preferably 50 μm or less, and more preferably 30 μm or less. It is advantageous to reduce the thickness of the polarizing plate 100, and even the thickness of the image display device, to 30 μm or less. The thickness of the polarizing plate is usually 2 μm or more (for example, 5 μm or more).

(2) Protective film

The protective film that can be laminated on one side or both sides of the polarizing plate may be a film formed of a light-transmitting (preferably optically transparent) thermoplastic resin such as: polyolefin-based resins such as chain polyolefin-based resins (polypropylene-based resins, etc.) and cyclic polyolefin-based resins (norbornene-based resins, etc.); cellulose resins such as cellulose triacetate and cellulose diacetate; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; a polycarbonate-based resin; (meth) acrylic resins such as methyl methacrylate resins; a polystyrene-based resin; a polyvinyl chloride resin; acrylonitrile-butadiene-styrene resins; acrylonitrile-styrene resins; polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; modified polyphenylene ether resin; a polysulfone-based resin; a polyether sulfone-based resin; a polyarylate-based resin; a polyamide imide resin; polyimide resins, and the like. Among them, polyolefin-based resins and cellulose-based resins are preferably used. In the present specification, "(meth) acrylic resin" means at least 1 selected from acrylic resins and methacrylic resins. The same applies to other terms in which "(methyl)" is assigned.

The thickness of the protective film is usually 1 to 100 μm, but is preferably 5 to 60 μm, and more preferably 5 to 50 μm from the viewpoint of strength, workability, and the like.

At least one of the protective films may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an optical diffusion layer, a retardation layer (a retardation layer having a retardation value of 1/4 wavelength, or the like), an antireflection layer, an antistatic layer, or an antifouling layer, or an optical layer on the outer surface (the surface opposite to the polarizing plate).

The protective film may be bonded to the polarizing plate via an adhesive layer, for example. As the adhesive for forming the adhesive layer, an aqueous adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and an aqueous adhesive or an active energy ray-curable adhesive is preferable.

(3) Other optical films

The polarizing plate 100 may include other optical films than polarizers and protective films, and typical examples thereof are a brightness enhancement film and a retardation film. In the case where the polarizing plate 100 includes other optical films, the protective film 60 may be laminated on the surface of the optical film.

(4) 1 st adhesive layer

The 1 st adhesive layer 31 is an adhesive layer disposed on the outermost surface of the polarizing plate 100, and may be used for bonding a multilayer film to an image display element (for example, a liquid crystal cell) or other optical members. The thickness of the 1 st adhesive layer 31 may be 1 to 40 μm, but is preferably 3 to 25 μm (for example, 3 to 20 μm, or more preferably 3 to 15 μm) from the viewpoint of making the polarizing plate 100 thin and from the viewpoint of suppressing dimensional change of the polarizing plate 100 while maintaining good processability. As for the material of the 1 st adhesive layer 31, the description in the adhesive layer described above is directly applied.

(5) Separation membrane

The separation film 70 is a film that is temporarily attached to protect the surface of the 1 st pressure-sensitive adhesive layer 31 until the 1 st pressure-sensitive adhesive layer 31 is bonded to an image display element (for example, a liquid crystal cell) or another optical member. The separation film 70 is generally made of a thermoplastic resin film having one surface subjected to a release treatment, and the release-treated surface is bonded to the 1 st pressure-sensitive adhesive layer 31. The thermoplastic resin constituting the separation film 70 may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, or the like. A separation film similar to that described above may be previously attached to the surface of the 3 rd pressure-sensitive adhesive layer 32 in order to temporarily attach and protect the surface until an optical film such as the brightness enhancement film 50 is bonded thereto. The thickness of the separation membrane 70 is, for example, 10 to 100 μm. When the storage modulus of the 1 st pressure-sensitive adhesive layer 31 is 0.15 to 1MPa, if the thickness of the separation membrane directly contacting the 1 st pressure-sensitive adhesive layer 31 is 50 μm or less, the 1 st pressure-sensitive adhesive layer 31 often has minute irregularities in the press-cutting step, and therefore the method of the present invention is preferably applied.

(6) Protective film

The pellicle 60 includes a resin film 61, and a non-adhesive resin layer 62 or a 2 nd adhesive layer 62 laminated thereon. The protective film 60 is a film for protecting the surface of the polarizing plate 100, and is usually peeled off and removed together with the adhesive resin layer 62 or the 2 nd adhesive layer 62 included therein after the polarizing plate with the protective film is attached to, for example, an image display element or other optical member.

The resin constituting the resin film 61 may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate and polyethylene naphthalate, a thermoplastic resin such as a polycarbonate-based resin, or the like. Polyester resins such as polyethylene terephthalate are preferred. The resin film 61 may have a single-layer structure or a multilayer structure, but is preferably a single-layer structure from the viewpoint of ease of production, production cost, and the like. The 2 nd adhesive layer 62 is described with reference to the 1 st adhesive layer 31.

[ manufacturing apparatus of Single sheet film ]

The apparatus for manufacturing a single sheet film according to the present embodiment includes: and a cut portion for cutting the multilayer film having the adhesive layer to obtain a single film from the multilayer film. The cutting part is provided with: a press-cutting blade capable of entering the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film. The cutting unit is directly applied to the explanation of the above-described cutting device in the method for producing a single sheet film. As for the multilayer film, the description of the above multilayer film in the production method of a single sheet film is directly applied.

The apparatus for producing a single sheet film according to the present embodiment may include components other than the cutting section, and examples thereof include: a multilayer film manufacturing section for manufacturing a multilayer film, an unwinding section for unwinding a multilayer film wound in a roll, a conveying section for conveying a multilayer film or a single film, a drying section for drying a multilayer film or a single film, and the like.

[ method of cutting multilayer film ]

The method for cutting a multilayer film according to the present embodiment includes: and a press-cutting step of cutting the multilayer film by inserting a press-cutting blade into the multilayer film from the 1 st surface of the multilayer film toward the 2 nd surface of the multilayer film. The cutting method is directly applied to the description of the above-described cutting step in the production method of a single sheet film.

Examples

The present invention will be described in further detail with reference to examples, but the present invention is not limited to these examples.

[ multilayer film A ]

As the multilayer film a to be cut, a rectangular cycloolefin polymer (COP) polarizing plate with a seed film (SRD341 mass reel) having a thickness of 185 μm and a long side length of 300mm × a short side length of 210mm was used. The COP polarizing plate with a protective film had a structure in which a protective film (58 μm), a TAC film (25 μm) as a protective film, a PVA film (12 μm) as a polarizer, a COP film (23 μm), a 1 st adhesive layer (20 μm), and a PET film (38 μm) as a separation film were laminated from above. One side of the protective film is adhesive, the other side is non-adhesive, and the adhesive side is attached to the TAC film in a grounding mode.

The 1 st adhesive layer had a storage modulus of 0.34MPa at a temperature of 20 ℃ and an angular frequency of 1,000 rad/sec. With respect to the multilayer film a, the 1 st adhesive layer is a reference adhesive layer. The reference adhesive layer (1 st adhesive layer) was subjected to DYNAMIC viscoelastic property measurement by frequency sweep at a temperature of 20 ℃ using a viscoelastic measuring device "DYNAMIC analog and rubber RDA II" manufactured by REOMETRIC corporation, and the storage modulus was found to be 3.0 × 10 based on the measurement value⁵Frequency omega of (Pa)₁The result was 1.20X 10²(1/sec). In addition, the storage modulus was also derived based on the measured value and showed 6.0X 10⁵Frequency omega of (Pa)₂The result was 6.03X 10²(1/sec).

[ multilayer film B ]

The multilayer film B has the same configuration as the multilayer film a except that a pressure-sensitive adhesive composition different from the pressure-sensitive adhesive composition constituting the 1 st pressure-sensitive adhesive layer of the multilayer film a is used as the pressure-sensitive adhesive composition constituting the 1 st pressure-sensitive adhesive layer, the thickness of the 1 st pressure-sensitive adhesive layer is 15 μm, and the thickness of the multilayer film B is 180 μm. The 1 st adhesive layer had a storage modulus of 0.65MPa at a temperature of 20 ℃ and an angular frequency of 1,000 rad/sec. For multilayer film B, the 1 st adhesive layer was used as the reference adhesive layer. The reference adhesive layer was subjected to DYNAMIC viscoelastic property measurement by frequency sweep at 20 ℃ using a viscoelastic measuring device "DYNAMIC ANALYZER RDA II" manufactured by REMOMETRIC corporation, and the storage modulus was found to be 3.0X 10 based on the measurement value⁵Frequency omega of (Pa)₁The result was 1.62X 10 (1/sec). In addition, the storage modulus was also derived based on the measured value and showed 6.0X 10⁵Frequency omega of (Pa)₂The result was 1.38X 10²(1/sec).

[ example 1]

(cutting test)

A cutting test was performed using the cutting apparatus shown in fig. 4 including the pressure cutting blade member 21a shown in fig. 5. As the cutting blade 211a of the cutting blade member 21a, a Thomson blade (manufactured by Ottra Seisakusho K.K.) having a length of 614mm in the longitudinal direction was used.

First, the multilayer film a is placed on the placement table 23 so as to be in contact with the blade plate 22. At this time, the PET film (58 μm) constituting the pellicle was placed on the upper side, and the PET film (38 μm) as a separation film was placed on the lower side. Then, the press blade 211a was moved to the multilayer film A so that the speed of the press blade on the surface of the seed film became 7.6X 10⁴The sheet was cut in a direction perpendicular to the absorption axis to bisect the COP polarizing plate with a seed film (μm/sec).

(evaluation of occurrence of stripe-like unevenness)

A cutting test was performed using 5 samples, and the presence or absence of the occurrence of stripe-like irregularities in the vicinity of the cut surface of the bisected cut piece was evaluated with respect to the 5 samples by visual observation. The evaluation results are shown in table 1.

[ example 2]

In the cutting test, the speed of the press blade 211a on the surface of the seed film was set to 1.2X 10 in the multilayer film A⁵A cutting test was performed in the same manner as in example 1 except for the mode of μm/sec, and the presence or absence of occurrence of stripe-like irregularities was evaluated. The evaluation results are shown in table 1.

[ example 3]

In the cutting test, in addition to using the multilayer film B in place of the multilayer film a, the press blade 211a was set to a speed of 2.1 × 10 on the surface of the seed film to the multilayer film B⁴A cutting test was performed in the same manner as in example 1 except for the mode of μm/sec, and the presence or absence of occurrence of stripe-like irregularities was evaluated. The evaluation results are shown in table 1.

[ example 4]

In the cutting test, the speed of the press blade 211a on the surface of the seed film was set to 7.6X 10 in the multilayer film B⁴A cutting test was performed in the same manner as in example 3 except for the mode of μm/sec, and the presence or absence of occurrence of stripe-like irregularities was evaluated. The evaluation results are shown in table 1.

Comparative example 1

In the cutting test, the speed of the press blade 211a on the surface of the seed film was set to 6.6X 10 in the multilayer film A³A cutting test was performed in the same manner as in example 1 except for the mode of μm/sec, and the presence or absence of occurrence of stripe-like irregularities was evaluated. The evaluation results are shown in table 1.

Comparative example 2

In the cutting test, the speed of the press blade 211a on the surface of the seed film was set to 2.1X 10 in the multilayer film A⁴A cutting test was performed in the same manner as in example 1 except for the mode of μm/sec, and the presence or absence of occurrence of stripe-like irregularities was evaluated. The evaluation results are shown in table 1.

The embodiments of the present invention have been described in an illustrative rather than a restrictive sense in all respects. The scope of the present invention is indicated by the claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Description of the symbols

10. 10a, 10b, 10c, 10d multilayer film

11 single sheet film

20 cutting device

21. 21a, 21b crush-cutting blade member

22-blade bearing plate

23 stage

31 st adhesive layer

60 protective film

61 resin film

62 nd 2 adhesive layer

70 separation membrane

100 polarizing plate

101 1 st surface

102 No. 2 surface

211a, 211b cutting edge

212a, 212b elastomer

213a holding part.

Claims

1. A method for manufacturing a monolithic film, comprising the steps of,

the method comprises a cutting step of cutting a multilayer film having n pressure-sensitive adhesive layers, wherein n is an integer of 1 or more,

when any one of the n pressure-sensitive adhesive layers is used as a reference pressure-sensitive adhesive layer, the speed V of the pressure-cutting blade on the 1 st surface of the multilayer film satisfies the following relational expression (1),

t/V＜1/ω₁(1)

in the relational expression (1), t represents the thickness of the multilayer film, ω₁The storage modulus calculated based on the measurement value of dynamic viscoelasticity measurement was 3.0X 10⁵A frequency at Pa, the measurement value of the dynamic viscoelasticity measurement being a measurement value of the dynamic viscoelasticity measurement by frequency sweep at a temperature of 20 ℃ of the reference adhesive layer,

wherein the velocity V is in units of μm/sec, the thickness is in units of μm, and the frequency is in units of 1/sec.

2. The method for manufacturing a monolithic film according to claim 1,

the adhesive layer having the smallest storage modulus at a temperature of 20 ℃ and an angular frequency of 1,000 rad/sec among the adhesive layers was used as the reference adhesive layer.

3. The method for manufacturing a monolithic film according to claim 1,

4. The method for producing a monolithic film according to any one of claims 1 to 3,

the multilayer film has a polarizing plate.

5. The method for producing a monolithic film according to any one of claims 1 to 3,

the thickness of the reference adhesive layer is 1-20 μm.

6. The method for producing a monolithic film according to any one of claims 1 to 3,

the pressure cutting edge is a Thomson edge.

7. A manufacturing apparatus for a single sheet of film,

the adhesive film has a cut portion for cutting a multilayer film having n adhesive layers, wherein n is an integer of 1 or more,

the control unit controls a speed V of the pressure-cutting blade on the 1 st surface of the multilayer film so as to satisfy the following relational expression (1) when any one of the n pressure-sensitive adhesive layers is used as a reference pressure-sensitive adhesive layer,

t/V＜1/ω₁(1)

8. The manufacturing apparatus of a monolithic film according to claim 7,

9. The manufacturing apparatus of a monolithic film according to claim 7,

10. The manufacturing apparatus of a monolithic film according to any one of claims 7 to 9,

the multilayer film has a polarizing plate.

11. The manufacturing apparatus of a monolithic film according to any one of claims 7 to 9,

the thickness of the reference adhesive layer is 1-20 μm.

12. The manufacturing apparatus of a monolithic film according to any one of claims 7 to 9,

the pressure cutting edge is a Thomson edge.

13. A method for cutting a multilayer film,

the cutting method is used for cutting a multilayer film with n layers of adhesive layers, wherein n is an integer more than 1,

t/V＜1/ω₁(1)

14. The cutting method of a multilayer film according to claim 13,

15. The cutting method of a multilayer film according to claim 13,

16. The method for cutting a multilayer film according to any one of claims 13 to 15,

the multilayer film has a polarizing plate.

17. The method for cutting a multilayer film according to any one of claims 13 to 15,

the thickness of the reference adhesive layer is 1-20 μm.

18. The method for cutting a multilayer film according to any one of claims 13 to 15,

the pressure cutting edge is a Thomson edge.