TW201939076A - Circular polarizing plate - Google Patents

Abstract

An objective of the present invention is to provide a circular polarizing plate provided with a retardation film including a layer formed by curing a liquid crystal compound, and by the circularly polarizing plate it is possible to suppress a change in color of reflected light from an initial state after it is placed in a high temperature environment in a state of being laminated with a front plate such as cover glass or the likes. The circular polarizing plate of the present invention having a polarizing plate in which a first protective film is laminated on one side of a polarizer and a second protective film is laminated on the other side of the polarizer, and a retardation film including a layer formed by curing a polymerizable liquid crystal compound, and the circular polarizing plate satisfies at least one of condition l and condition 2 below. Condition 1: when the moisture permeability of the first protective film is x (g/m2.24 hr) and the moisture permeability of the second protective film is y (g/m2.24 hr), formula (1) is satisfied; 1/x + 1/y ≥ 0.0030 Formula (1) Condition 2: the moisture content of the polarizing plate is 3.00% or less.

Description

   Circular polarizer   

The present invention relates to a circularly polarizing plate.

In recent years, image display devices represented by organic electroluminescence (hereinafter also referred to as organic EL) display devices are rapidly spreading. An organic EL display device carries a circularly polarizing plate including a polarizer and a phase difference film (λ / 4 plate). By configuring a circular polarizer, the reflection of external light can be prevented and the visibility of the image can be improved.

Due to the rise of organic EL display devices, as the demand for thinner image display devices becomes stronger, thinner circular polarizers are also required. At present, it has been studied to change the "phase retardation film formed from a conventional resin film" to "a phase retardation film formed from a thin-shaped liquid crystal compound as a material" (see, for example, Patent Document 1). A phase difference film using a polymerizable liquid crystal compound is manufactured by coating a polymerizable liquid crystal compound on a substrate and aligning it, and irradiating light as necessary to fix the alignment state.

    [Prior technical literature]         [Patent Literature]    

Patent Document 1: Japanese Patent Application Laid-Open No. 2017-54093

However, if a circularly polarizing plate having a phase difference film formed of a polymerizable liquid crystal compound is placed in a high-temperature environment with a front plate attached, the color of the reflected light in the central portion of the circularly polarizing plate is compared to the initial stage. The state changes, specifically, there is a problem that the reflected light becomes red.

An object of the present invention is to provide a circularly polarizing plate including a phase difference film including a layer hardened by a liquid crystal compound. The circularly polarizing plate can prevent the circularly polarizing plate from being placed in a high temperature environment after being attached to a cover glass or the like. The color of the reflected light changes from the initial state.

[1] A circular polarizing plate, comprising: a polarizing plate, a first protective film on an area layer of a polarizer, and a second protective film on another area layer of the polarizer; and a phase difference film including A layer formed by curing a polymerizable liquid crystal compound; and the circular polarizing plate satisfies at least one of the following conditions 1 and 2.

Condition 1: When the moisture permeability of the first protective film is x (g / m ² ‧ 24 hours), and the moisture permeability of the second protective film is y (g / m ² ‧ 24 hours), the formula (1 ).

1 / x + 1 / y ≧ 0.0030 Equation (1)

Condition 2: The moisture content of the polarizing plate is 3% or less.

[2] The circular polarizing plate according to [1], which satisfies both Condition 1 and Condition 2.

[3] The circular polarizing plate according to [1] or [2], wherein a front plate is provided on a side of the polarizing plate opposite to a side where the phase difference film is laminated.

[4] The circular polarizing plate according to any one of [1] to [3], wherein a thickness of the polarizer is 13 μm or less.

According to the present invention, in a circular polarizing plate having a phase difference film including a layer hardened by a liquid crystal compound, the color phase of reflected light after being placed in a high-temperature environment in a state in which it is bonded to a front panel such as a cover glass can be suppressed. Changes compared to the initial state.

1‧‧‧ polarizing plate

2‧‧‧ phase contrast film

3‧‧‧Organic EL Display Element

4‧‧‧ front panel

10‧‧‧Polarizer

11‧‧‧The first protective film

12‧‧‧ 2nd protective film

13, 14, 16‧‧‧ Adhesive layer

15‧‧‧ Adjacent layer

20, 21‧‧‧ a layer hardened by a polymerizable liquid crystal compound

100, 101, 103‧‧‧ circular polarizers

104, 105‧‧‧ organic EL display devices

FIG. 1 is an example of a schematic cross-sectional view showing a layer configuration of a circularly polarizing plate.

Fig. 2 is an example of a schematic cross-sectional view showing a layer configuration of a circularly polarizing plate.

FIG. 3 is an example of a schematic cross-sectional view showing a layer structure of an organic EL display device.

<Circular polarizer>

The circular polarizing plate of the present invention includes a polarizing plate and a phase difference film. The polarizing plate and the phase difference film can be laminated by, for example, bonding. Examples of the adhesive layer include an adhesive layer or an adhesive layer described later. In the present invention, the polarizing plate means a laminated body composed of a polarizer and protective films attached to both sides of the polarizer, respectively.

An example of the layer configuration of the circular polarizing plate of the present invention will be described below with reference to FIG. 1. In addition, in FIG. 1, the adhesive layers for individually bonding the polarizer 10 and the protective films 11 and 12 are not shown. The circular polarizing plate 100 shown in FIG. 1 (a) has a layer structure in which a polarizing plate 1 and a phase difference film 2 are laminated with an adhesive layer 13 interposed therebetween. The polarizing plate 1 is formed on an area of a polarizer 10. The first protective film 11 includes a second protective film 12 on the other area of the polarizer 10. The phase difference film 2 includes a layer 20 hardened by a polymerizable liquid crystal compound. Furthermore, the circularly polarizing plate 100 has an adhesive layer 14 on a surface of the phase difference film 2 opposite to the polarizing plate 1. The adhesive layer 14 may be an adhesive layer for bonding to an organic EL display element or the like.

The circular polarizing plate 101 shown in FIG. 1 (b) has a layer structure in which a polarizing plate 1 and a phase difference film 2 are laminated with an adhesive layer 13 interposed therebetween. The polarizing plate 1 is formed on an area of a polarizer 10. The first protective film 11 has a second protective film 12 on another area of the polarizer 10. In the circularly polarizing plate 101, the phase difference film 2 has a layer in which a layer 20 hardened from a polymerizable liquid crystal compound and a layer 21 hardened from a polymerizable liquid crystal compound are laminated with an adhesive layer 15 therebetween. Furthermore, the circularly polarizing plate 101 has an adhesive layer 14 on a surface of the phase difference film 2 on the side opposite to the polarizing plate 1. The adhesive layer 14 may be an adhesive layer for bonding to an organic EL display element or the like.

As shown in FIG. 1, the phase difference film may have one or two layers hardened by a polymerizable liquid crystal compound. The phase difference film may have an alignment film or a base film for aligning the polymerizable liquid crystal compound.

The circular polarizing plate may have a layer other than the layer shown in FIG. 1. Examples of the layers that the circular polarizing plate may further include a front panel and a light-shielding pattern. The front panel may be disposed on the side of the polarizing plate opposite to the layer having the phase difference film. The circular polarizing plate 102 shown in FIG. 2 (a) is one in which the front plate 4 is laminated on the circular polarizing plate 100, and the front plate 4 is laminated on the polarizing plate 1 via an adhesive layer 16. The circular polarizing plate 103 shown in FIG. 2 (b) is one in which the front plate 4 is laminated on the circular polarizing plate 101, and the front plate 4 is laminated on the polarizing plate 1 via an adhesive layer 16.

The light-shielding pattern may be formed on a surface of the front panel on the side of the polarizing plate. The light-shielding pattern is formed on the frame (non-display area) of the image display device, and can prevent users from seeing the wiring of the image display device.

The circularly polarizing plate of the present invention satisfies at least one of the following conditions 1 and 2.

Condition 1: When the moisture permeability of the first protective film is x (g / m ² ‧ 24 hours), and the moisture permeability of the second protective film is y (g / m ² ‧ 24 hours), the formula (1 ).

1 / x + 1 / y ≧ 0.0030 Equation (1)

Condition 2: The moisture content of the polarizing plate is 3.00% or less.

The circularly polarizing plate is capable of preventing the color change of the central portion of the circularly polarizing plate when the circularly polarizing plate is placed in a high-temperature environment by meeting at least one of the above conditions 1 and 2. The circularly polarizing plate preferably satisfies both the conditions 1 and 2 described above.

More specifically, in the formula (1), 1 / x + 1 / y is 0.0030 or more, preferably 0.010 or more, more preferably 0.020 or more, and even more preferably 0.050 or more. The upper limit is not particularly limited, but 1 / x + 1 / y is usually 0.2 or less.

More specifically, the moisture content of the polarizing plate is 3.00% or less, preferably 2.50% or less, and more preferably 2.00% or less. The lower limit is not particularly limited, but the moisture content of the polarizing plate is usually above 0.50%, and may also be above 1.00%. The method for measuring the water content is based on the method described in the examples described later.

The present invention is not limited in any way, but the reason why the reflected light can be prevented from turning red by meeting conditions 1 and 2 is presumed as follows. According to discussions by the inventors, the phenomenon that the reflected light from the central portion of the circularly polarizing plate turns red is caused by a decrease in the phase difference value of the phase difference film. The decrease in the phase difference value of the phase difference film is presumably caused by the water contained in the polarizing plate moving to the phase difference film. Therefore, "the moisture content contained in the polarizing plate is set to a predetermined value or less to reduce the amount of water that can be moved to the phase difference film" or "the moisture permeability of the protective film provided in the polarizing plate is set to a predetermined value or less It is effective to make it difficult for water to move to the phase difference film.

Condition 2 is based on the above-mentioned guess, and by setting the moisture content of the polarizing plate to the above range, it is possible to prevent the reflected light from the circular polarizing plate from turning red. On the other hand, surprisingly, Condition 1 is based on "the prevention of discoloration of the reflected light of the circular polarizer, not only the moisture permeability of the protective film on the side of the polarizer close to the phase difference film, but also the deviation of the polarizer The moisture permeability of the protective film on the far side of the phase difference film is also important. " According to discussions by the present inventors, by making the moisture permeability of the protective film attached to both sides of the polarizing plate selected to meet the above condition 1, the reflected light from the circular polarizing plate can be prevented from turning red.

In the case where the circular polarizing plate of the present invention is heated at 85 ° C for 400 hours, the magnitude of the reduction amount of the phase difference value in the center of the plane (which can be the position of the center of gravity of the circular polarizing plate) ΔRe (nm) is 10 nm or less as Preferably, it is preferably 8 nm or less. The phase difference value is a value at a wavelength of 547 nm. By setting in this range, the color change of the circularly polarizing plate can be made small, and a circularly polarizing plate with good appearance can be obtained.

The shape of the circular polarizing plate of the present invention is not particularly limited. When the circular polarizing plate is substantially rectangular, the length of the long side is preferably 5 cm to 35 cm, more preferably 10 cm to 25 cm, the length of the short side is preferably 5 cm to 25 cm, and 6 cm to 20 cm is preferred. good. As long as it is such a size, it is difficult for water to accumulate.

The so-called "substantially rectangular" means that the circularly polarizing plate has a cut-out shape or a circular shape so that at least one corner portion of the four corners (corner portions) of each main surface becomes an obtuse angle. The shape may have a portion (notch) in which a part of the end surface perpendicular to the main surface is recessed inwardly, or a part of the main surface may have a hollow, oval, or multi-layered shape. Perforated portions of the shape of the corners and these combinations.

<Polarizer>

The polarizing plate of the present invention means a laminated body composed of a polarizer and protective films attached to both sides of the polarizer. The protective film included in the polarizing plate may have a surface treatment layer such as a hard coat layer, an anti-reflection layer, and an antistatic layer described later. The polarizer and the protective film may be laminated by, for example, an adhesive layer or an adhesive layer. The components included in the polarizing plate are described below.

(1) Polarizer

The polarizer provided in the polarizing plate may be an absorptive polarizer having the following properties: it can absorb linearly polarized light having a vibration plane parallel to its absorption axis, and can transmit and have a line orthogonal to the absorption axis (parallel to the transmission axis ) The nature of linearly polarized light on the vibrating surface. As the polarizer included in the first layer, a polarizer in which a dichroic dye is adsorbed and aligned in a uniaxially stretched polyvinyl alcohol-based resin film can be suitably used. The polarizer can be manufactured by a method including the steps of uniaxially stretching a polyvinyl alcohol-based resin film, and adsorbing dichroism by dyeing the polyvinyl alcohol-based resin film with a dichroic dye. A step of dyeing; a step of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed with a crosslinking solution such as an aqueous boric acid solution; and a step of washing with water after the crosslinking solution is treated.

As the polyvinyl alcohol-based resin, a polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, copolymers such as copolymers with other monomers copolymerizable with vinyl acetate. Examples of the monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth) acrylamidoamines having an ammonium group, and the like.

In the present specification, "(meth) acrylic acid" means at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth) acrylfluorenyl" and "(meth) acrylate".

The saponification degree of polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, aldehyde-modified polyvinyl formal (poly (vinyl formal)) or polyvinyl acetal (poly (vinyl acetal)) may be used. The average degree of polymerization of the polyvinyl alcohol resin is usually 1000 to 10,000, and preferably 1500 to 5000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

A film formed of such a polyvinyl alcohol-based resin is used as an original film of a polarizer. The method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a conventional method is used. The thickness of the polyvinyl alcohol-based original film is not particularly limited, but in order to reduce the thickness of the polarizer to 15 μm or less, it is preferable to use 5 to 35 μm. It is preferably 20 μm or less.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic pigment. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the crosslinking treatment. In addition, uniaxial stretching may be performed in these plural stages.

In uniaxial stretching, uniaxial stretching may be performed between rollers having different peripheral speeds, or uniaxial stretching may be performed using a hot roller. The uniaxial stretching may be dry stretching in the air, or wet stretching in which a polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent or water. The stretching ratio is usually 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of dipping the film in an aqueous solution containing a dichroic dye is used. The dichroic pigments use iodine or a dichroic organic dye. The polyvinyl alcohol-based resin film is preferably immersed in water before being dyed.

For the cross-linking treatment after dichroic dyeing, a method of dipping a dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid is generally adopted. When iodine is used as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide.

The thickness of the polarizer is usually 30 μm or less, preferably 15 μm or less, more preferably 13 μm or less, more preferably 10 μm or less, and particularly preferably 8 μm or less. In particular, if the thickness of the polarizer is set to 15 μm or less, the moisture content of the polarizer per unit area is reduced, which is advantageous. The thickness of the polarizer is usually 2 μm or more, and preferably 3 μm or more.

As for a polarizer, for example, as described in Japanese Patent Application Laid-Open No. 2016-170368, a dichroic pigment can be aligned in a cured film polymerized from a liquid crystal compound. As the dichroic pigment, those having an absorption in a wavelength range of 380 to 800 nm can be used, and an organic dye is preferably used. Examples of the dichroic pigment include azo compounds. The liquid crystal compound is a liquid crystal compound which can be polymerized in an aligned state, and may have a polymerizable group in a molecule. Moreover, as described in WO2011 / 024891, a polarizer can be formed from a dichroic pigment having liquid crystallinity.

(2) Protective film

Based on polarizers, the moisture permeability of the protective film (first protective film) on the far side of the phase difference film is preferably 500 g / m ² ‧ 24 hours or less, and more preferably 200 g / m ² ‧ 24 hours or less It is more preferably 100 g / m ² ‧ 24 hours or less, and 50 g / m ² ‧ 24 hours or less. The lower limit is not particularly limited, but usually exceeds 0 g / m ² ‧ 24 hours.

Based on the polarizer, the moisture permeability of the protective film (second protective film) closer to the phase difference film is preferably 500 g / m ² ‧ 24 hours or less, and more preferably 200 g / m ² ‧ 24 hours or less It is more preferably 100 g / m ² ‧ 24 hours or less, and 50 g / m ² ‧ 24 hours or less. The lower limit is not particularly limited, but usually exceeds 0 g / m ² ‧ 24 hours.

The first protective film and the second protective film may have the same moisture permeability or different moisture permeability. The moisture permeability can be measured under the conditions of a temperature of 40 ° C and a relative humidity of 90% in accordance with the moisture permeability test (Dish method) of JIS Z0208.

The protective film laminated on both sides of the polarizer may be a film made of a thermoplastic resin having translucency (preferably optically transparent). The thermoplastic resin may be, for example, a chain-like polyolefin resin (poly Polypropylene resins such as acrylic resins, cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as triethyl cellulose and diethyl cellulose; such as polyparaphthalein Polyester resins such as ethylene glycol and polybutylene terephthalate; polycarbonate resins; (meth) acrylic resins such as methyl methacrylate resins; polystyrene resins; poly Vinyl chloride resin; Acrylonitrile-butadiene-styrene resin; Acrylonitrile-styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resins; modified polyphenylene ether resins; polyfluorene resins; polyether resins; polyarylate resins; polyamide resins; polyimide resins; polyimide resins Wait.

The chain polyolefin resins include, for example, polyethylene resins (polyethylene resins that are homopolymers of ethylene, or copolymers mainly composed of ethylene), and polypropylene resins (polypropylenes that are homopolymers of propylene). In addition to a homopolymer of a chain olefin such as a resin or a copolymer mainly composed of propylene), a copolymer composed of two or more kinds of chain olefins may also be mentioned.

Cyclic polyolefin resin is a generic term for a resin polymerized by using a cyclic olefin as a polymerization unit, and examples thereof include Japanese Patent Laid-Open No. 1-240517, Japanese Patent Laid-Open No. 3-14882, and Japanese Patent Laid-Open No. 3-122137. Resin described in bulletins and the like. Specific examples of the cyclic polyolefin-based resin include a ring-opened (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a copolymer of a cyclic olefin and a chain olefin such as ethylene or propylene (which Representative examples are random copolymers), graft polymers modified with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as the cyclic olefin is applicable.

The polyester resin is a resin having an ester bond in addition to the cellulose ester resin described below, and is generally a polycondensate of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol. Typical examples of the polyester-based resin include polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

The (meth) acrylic resin refers to a resin containing a compound having a (meth) acrylfluorenyl group as a main constituent monomer. Specific examples of the (meth) acrylic resin include, for example, poly (meth) acrylate such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic copolymer; methyl methacrylate- (Meth) acrylate copolymer; methyl methacrylate-acrylate- (meth) acrylate copolymer; methyl (meth) acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and Copolymers of compounds having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth) acrylate copolymer, etc.). It is preferable to use a polymer containing poly (meth) acrylic acid C _1-6 alkyl ester such as poly (meth) acrylate as a main component, and more preferably to use a polymer containing methyl methacrylate as a main component (50 to 100). % By weight, preferably 70 to 100% by weight) of a methyl methacrylate resin.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, these copolymers or those in which a part of the hydroxyl group is modified by other substituents can also be listed. Among these, cellulose triacetate (that is, triethyl cellulose) is particularly preferred.

Polycarbonate-based resins are engineering plastics composed of "polymers in which monomer units are bonded through carbonate groups".

Regarding the phase difference value of the protective film, it is also useful to control it to a value suitable for an image display device such as a liquid crystal display device. For example, in a liquid crystal display device in a lateral electric field effect display technology (IPS) mode, it is preferable to use a film having a phase difference value of substantially zero as a protective film. The fact that the phase difference value is substantially zero means that the in-plane phase difference value Re (550) at a wavelength of 550 nm is 10 nm or less, and the absolute value of the phase difference value Rth in the thickness direction at a wavelength of 550 nm is 10 nm or less. The absolute value of the phase difference value Rth in the thickness direction at a wavelength of 480 to 750 nm is preferably 15 nm or less. In addition, in order to improve the visibility of the image when the user is wearing polarized sunglasses, etc., the in-plane phase difference value Re (550) at a wavelength of 550 nm can also be set to 70 to 140 nm.

For example, according to the mode of the liquid crystal display device, the protective film may be subjected to stretching and / or shrinking processing, etc., so as to give a suitable phase difference. For example, for the purpose of viewing angle compensation, a phase difference layer (or film) having a single-layer or multi-layer structure can be used as a protective film.

The thickness of the protective film is usually 1 to 100 μm, but from the viewpoints of strength and handleability, it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and even more preferably 15 to 40 μm.

The protective films attached to both sides of the polarizer may be made of the same kind of thermoplastic resin, or they may be made of different kinds of thermoplastic resin. In addition, the thicknesses may be the same or different. Furthermore, they may have the same phase difference characteristics, or they may have different phase difference characteristics.

As described above, at least one of the protective films may be provided with a hard coat layer, an anti-glare layer, a light diffusion layer, an anti-reflection layer, a low refractive index layer, Surface treatment layer (coating) such as antistatic layer and antifouling layer. The thickness of the protective film includes the thickness of the surface treatment layer.

The protective film may be bonded to the polarizer via, for example, an adhesive layer or an adhesive layer. As the adhesive for forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and a water-based adhesive and an active energy ray-curable adhesive are preferred. As the adhesive layer, the latter can be used.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, and a water-based two-liquid urethane-based emulsion adhesive. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. As the polyvinyl alcohol-based resin, in addition to a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate, which is a homopolymer of vinyl acetate, vinyl acetate and a copolymer of vinyl acetate A polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of another polymerized monomer, or a modified polyvinyl alcohol-based polymer in which these hydroxyl groups are partially modified. The water-based adhesive may include a crosslinking agent such as an aldehyde compound (glyoxal, etc.), an epoxy compound, a melamine-based compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When using a water-based adhesive, it is preferable to perform a drying step to remove water contained in the water-based adhesive after bonding the polarizer and the protective film. After the drying step, an aging step can be set, for example, at a temperature of 20 to 45 ° C.

The above-mentioned active energy ray-curable adhesive refers to an adhesive containing a curable compound that is cured by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and an ultraviolet-curable adhesive is preferred.

The curable compound may be a cation polymerizable curable compound or a radical polymerizable curable compound. Examples of the cationically polymerizable curable compound include epoxy compounds (compounds having one or two or more epoxy groups in the molecule), and oxetane compounds (having one or two in the molecule). More than one oxetane ring compound), or combinations thereof. Examples of the radically polymerizable sclerosing compound include (meth) acrylic compounds (compounds having one or two (meth) acrylfluorenyloxy groups in the molecule), and radically polymerizable double bonds. Other vinyl compounds, or combinations thereof. A cationically polymerizable curable compound and a radical polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further contains a cationic polymerization initiator and / or a radical polymerization initiator that starts the curing reaction of the curable compound.

When the polarizer and the protective film are bonded, in order to improve the adhesion, a surface activation treatment may be performed on at least one of the bonding surfaces. Examples of surface activation treatments include dry methods such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionization active line treatment (ultraviolet treatment, electron beam treatment, etc.) Treatment: such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, anchor coating (Anchor Coat) treatment and other wet treatment. These surface activation treatments may be performed alone or in combination of two or more.

When the protective film is laminated on both sides of the polarizer, the adhesive used to attach the protective film may be the same kind of adhesive, or it may be a different kind of adhesive.

<Phase difference film>

The phase difference film has a layer composed of a composition containing a polymerizable liquid crystal compound. The layer composed of a composition containing a polymerizable liquid crystal compound, specifically, means a layer hardened by a polymerizable liquid crystal compound. In this specification, a layer giving a phase difference of λ / 2, a layer giving a phase difference of λ / 4 (positive A layer), and a positive C layer may be collectively referred to as a phase difference layer. Furthermore, the phase difference film may include a substrate and an alignment film described later.

The layer hardened by the polymerizable liquid crystal compound is formed on, for example, an alignment film provided on a substrate. The aforementioned substrate has a function of supporting the alignment film, and may be formed into a long substrate. The substrate has a function as a release support, and can support a phase difference layer for transfer. Furthermore, it is preferable that the surface has a degree of peeling adhesion. Examples of the substrate include a resin film exemplified as a material of the protective film.

The thickness of the substrate is not particularly limited, but is preferably set to a range of, for example, 20 μm to 200 μm. When the thickness of the substrate is 20 μm or more, strength is imparted. On the other hand, when the thickness is 200 μm or less, when the substrate is subjected to a cutting process to form a sheet-like substrate, it is possible to suppress an increase in processing dust and abrasion of the cutting blade.

In addition, the substrate may be subjected to various anti-blocking treatments. Examples of the anti-caking treatment include easy adhesion treatment, treatment of kneading fillers, and embossing (rolling treatment). By implementing such an anti-blocking treatment on the substrate, when the substrate is wound, the substrates can be effectively prevented from adhering to each other, so-called blocking, and an optical film can be produced in a highly productive manner.

A layer hardened by a polymerizable liquid crystal compound is formed on a substrate through an alignment film. That is, the substrate and the alignment film are laminated in this order, and a layer system hardened by a liquid crystal compound is laminated on the alignment film.

In addition, the alignment film is not limited to a vertical alignment film, but may be an alignment film in which the molecular axis of the polymerizable liquid crystal compound is horizontally aligned, or an alignment film in which the molecular axis of the polymerizable liquid crystal compound is inclined. . The alignment film preferably has solvent resistance that does not dissolve due to application of a composition including a polymerizable liquid crystal compound described later, and heat resistance during heat treatment for removing the solvent or the alignment liquid crystal compound. . Examples of the alignment film include an alignment film containing an alignment polymer, a groove alignment film that forms a concave-convex pattern or a plurality of grooves on the photo-alignment film and the surface and is aligned. The thickness of the alignment film is usually in a range of 10 nm to 10000 nm, preferably in a range of 10 nm to 1000 nm, more preferably 500 nm or less, and even more preferably in a range of 10 nm to 200 nm.

The resin used for the alignment film is not particularly limited as long as it is a resin used as a material of a conventional alignment film, and conventionally known monofunctional or polyfunctional (meth) acrylate monomers can be polymerized. A hardened product obtained by curing under an initiator. Specifically, as the (meth) acrylate-based monomer, 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono 2-ethylhexyl ether acrylate, and diethyl acrylate can be exemplified. Glycol monophenyl ether, tetraethylene glycol monophenyl ether, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isoamyl acrylate, isoamyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofuran methyl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofuran methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, methacrylic acid Cyclohexyl, methacrylate, urethane acrylate, and the like. The resin may be one of these types or a mixture of two or more types.

The type of the polymerizable liquid crystal compound used in this embodiment is not particularly limited, and can be classified into a rod-like type (rod-like liquid crystal compound) and a disk-like type (disk-like liquid crystal compound, disk-like liquid crystal) from its shape. Compound). Moreover, there are a low molecular type and a high molecular type, respectively. In addition, in general, a polymer means a polymer having a degree of polymerization of 100 or more (Polymer Physics, Phase Transition Kinetics, Masai Doi, 2 pages, Iwanami Bookstore, 1992).

Any polymerizable liquid crystal compound can be used in this embodiment. Furthermore, two or more rod-shaped liquid crystal compounds, two or more disk-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disk-shaped liquid crystal compound can be used.

In addition, as for the rod-shaped liquid crystal compound, for example, those described in claim 1 of Japanese Patent Application Publication No. 11-513019 or paragraphs [0026] to [0098] of Japanese Patent Application Publication No. 2005-289980 can be suitably used. As for the discotic liquid crystal compound, for example, paragraphs [0020] to [0067] of Japanese Patent Laid-Open No. 2007-108732, or paragraphs [0013] to [0108] of Japanese Patent Laid-Open No. 2010-244038 can be suitably used. Recorder.

The polymerizable liquid crystal compound may be used in combination of two or more kinds. In this case, at least one species has two or more polymerizable groups in the molecule. That is, the layer hardened by the polymerizable liquid crystal compound is preferably a layer in which a liquid crystal compound having a polymerizable group is fixed by polymerization. In this case, it is no longer necessary to display liquid crystal properties after layer formation.

The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. The polymerizable group is preferably a functional group capable of performing an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a cyclic polymerizable group. More specifically, examples of the polymerizable group include (meth) acrylfluorenyl, vinyl, styryl, and allyl. Among them, a (meth) acrylfluorenyl group is preferred. Further, (meth) acrylfluorenyl means a concept including both a methacrylfluorenyl group and an acrylfluorenyl group.

The layer hardened from the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound on, for example, an alignment film as described later. The said composition may contain components other than the said polymerizable liquid crystal compound. For example, the aforementioned composition preferably contains a polymerization initiator. The polymerization initiator used can be selected according to the form of the polymerization reaction, such as a thermal polymerization initiator and a photopolymerization initiator. Examples of the photopolymerization initiator include α-carbonyl compounds, Acyloin ether, α-hydrocarbon-substituted aromatic compounds, polynuclear quinone compounds, triarylimidazole dimers, and p-aminophenyl groups. A combination of ketones and the like. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, and more preferably 0.5 to 5% by mass relative to the total solids content in the coating liquid.

From the viewpoint of the uniformity of the coating film and the strength of the film, the polymerizable monomer may be contained in the composition. Examples of the polymerizable monomer include radically polymerizable and cationically polymerizable compounds. Among them, a polyfunctional radical polymerizable monomer is preferred.

The polymerizable monomer is preferably one which can be copolymerized with the polymerizable liquid crystal compound. Specific examples of the polymerizable monomer include those described in paragraphs [0018] to [0020] in Japanese Patent Application Laid-Open No. 2002-296423. The use amount of the polymerizable monomer is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass relative to the total mass of the polymerizable liquid crystal compound.

From the viewpoint of the uniformity of the coating film and the strength of the film, a surfactant may be contained in the composition. Examples of the surfactant include conventionally known compounds. Among them, a fluorine-based compound is particularly preferred. Specifically, examples of the surfactant include compounds described in paragraphs [0028] to [0056] in Japanese Patent Application Laid-Open No. 2001-330725, and paragraphs [0069] to [0069] in Japanese Patent Application No. 2003-295212. 0126] The compound as described.

A solvent may be contained in the composition, and an organic solvent is preferably used. Examples of the organic solvent include amidine (e.g., N, N-dimethylformamide), fluorene (e.g., dimethylformamide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), halogen Alkanes (e.g. chloroform, dichloromethane), esters (e.g. methyl acetate, ethyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxy) Ethane). Of these, haloalkanes and ketones are preferred. In addition, two or more kinds of organic solvents may be used in combination.

In addition, the aforementioned composition may include various kinds of alignment agents, for example, vertical alignment accelerators such as polarizer interface-side vertical alignment agents, air interface-side vertical alignment agents, and horizontal alignment agents on polarizer interface-side and air-interface-side horizontal alignment agents. Horizontal alignment promoter. Furthermore, the composition may contain, in addition to the above-mentioned components, an adhesion improver, a plasticizer, a polymer, and the like.

In this embodiment, the thickness of the phase difference layer is preferably 0.5 μm or more. The thickness of the phase difference layer is preferably 10 μm or less, and more preferably 5 μrm or less. In addition, the above upper limit and lower limit may be arbitrarily combined. When the thickness of the phase difference layer is at least the aforementioned lower limit, sufficient durability can be obtained. If the thickness of the phase difference layer is below the aforementioned upper limit value, it will contribute to the thinning of the circular polarizing plate. Regarding the thickness of the phase difference layer, it can be adjusted to obtain the desired phase difference value of the layer giving a phase difference of λ / 4, the layer giving a phase difference of λ / 2 or the positive C layer, and the phase in the thickness direction. Difference.

The phase difference film may be one including one layer hardened by a polymerizable liquid crystal compound, or one including two or more layers hardened by a polymerizable liquid crystal compound. When the phase difference film includes two layers hardened by a polymerizable liquid crystal compound, the two layers are referred to as "a layer giving a phase difference of λ / 4 and a positive C layer" or "a layer giving a phase difference of λ / 4 and A layer with a phase difference of λ / 2 is preferred. When the phase difference film includes two layers hardened by a polymerizable liquid crystal compound, the layers hardened by the polymerizable liquid crystal compound can be individually made on an alignment film, and laminated through an adhesive layer or an adhesive layer. Both, thereby manufacturing a phase difference film. After both layers are laminated, the substrate and the alignment film can be peeled off. The thickness of the phase difference film is preferably 3 to 30 μm, and more preferably 5 to 25 μm.

<Adhesive layer>

The adhesive layer may include an adhesive composition containing a (meth) acrylic-based, rubber-based, urethane-based, ester-based, silicone-based, or polyvinyl ether-based resin as a main component. Made up. Among these, an adhesive composition using a (meth) acrylic resin excellent in transparency, weather resistance, and heat resistance as a base polymer is preferred. The adhesive composition may be an active energy ray hardening type or a thermosetting type. The thickness of the adhesive layer is usually 3 to 30 μm, preferably 3 to 25 μm.

As the (meth) acrylic resin (base polymer) used in the adhesive composition, for example, butyl (meth) acrylate, ethyl (meth) acrylate, and isooctyl (meth) acrylate can be suitably used. A polymer or copolymer of one or two or more (meth) acrylates such as 2-ethylhexyl (meth) acrylate and the like. In the base polymer, a polar monomer is preferably copolymerized. Examples of the polar monomer include (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, and N, N- (meth) acrylate Monomers having a carboxyl group, a hydroxyl group, an amino group, an amine group, an epoxy group, and the like, such as dimethylaminoethyl ester and glycidyl (meth) acrylate.

The adhesive composition may include only the above-mentioned base polymer, but usually further contains a crosslinking agent. Examples of the cross-linking agent include: a metal ion having a valence of two or more, and a carboxylic acid metal salt formed with a carboxyl group; a polyamine compound, and a amide bond formed with a carboxyl group; a polyepoxide compound or a polyhydric alcohol Those who form an ester bond with a carboxyl group; those who are polyisocyanate compounds and form a amide bond with a carboxyl group. Among them, a polyisocyanate compound is preferred.

<Front panel>

The front panel is arranged on the viewing side of the polarizing plate. The front panel may be laminated on the polarizing plate via an adhesive layer. Examples of the adhesive layer include the aforementioned adhesive layer and adhesive layer. As shown in FIGS. 2 (a) and 2 (b), the front panel 4 may be laminated on the first protective film 11 of the polarizing plate 1 via an adhesive layer 16.

When a circular polarizing plate is laminated with a front panel, the reflected light from the circular polarizing plate is easily discolored to red. It is presumed that most of the front panel has low moisture permeability, and the moisture contained in the polarizing plate is likely to accumulate. Therefore, the circular polarizing plate of the present invention exhibits a significant effect when it has a front panel.

Examples of the front panel include a hard coat layer on at least one side of glass and a resin film. As the glass, for example, high-penetration glass and tempered glass can be used. In particular, when a thin transparent surface material is used, chemically strengthened glass is preferred. The thickness of the glass can be set to, for example, 100 μm to 5 mm.

The front panel including a hard coating layer on at least one side of the resin film is not as hard as existing glass, and may have flexible characteristics. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

The resin film may be a film made of a polymer such as a cycloolefin derivative and a cellulose having a unit containing a cycloolefin monomer such as norbornene or a polycyclic norbornene monomer. (Diethyl cellulose, triethyl cellulose, cellulose acetate butyrate, isobutyl cellulose, propyl cellulose, butyl cellulose, acetyl cellulose, ethylene-vinyl acetate copolymer, Polycycloolefin, polyester, polystyrene, polyimide, polyetherimide, polyacrylic acid, polyimide, polyimide, imine, polyether, polyimide, polyethylene, polypropylene, polyimide Methylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyetherfluorene, polymethylmethacrylate, polyethylene terephthalate Diester, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, epoxy resin, etc. The resin film can be unstretched, uniaxially or biaxially stretched. These polymers can be used singly or in combination of two or more kinds. For the resin film, it is preferred to be a polymer having excellent transparency and heat resistance. Fluorene amine imine film or polyimide film, uniaxially or biaxially stretched polyester film; cycloolefin derivative film, polymethacrylic acid film with excellent transparency and heat resistance, which can also support large-scale film Methyl ester films; and triethyl cellulose and isobutyl cellulose films with transparency and optical anisotropy. The thickness of the resin film may be 5 to 200 μm, and preferably 20 to 100 μm.

The hard coat layer can be formed by hardening a hard coat composition containing a reactive material that forms a crosslinked structure by irradiation with light or thermal energy. The hard coat layer can be formed by hardening a hard coat composition containing both a photocurable (meth) acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photo-curable (meth) acrylate monomer may include a group selected from the group consisting of an epoxy (meth) acrylate, a urethane (meth) acrylate, and a polyester (meth) acrylate. More than one of them. The epoxy (meth) acrylate is obtained by reacting an epoxy compound with a carboxylic acid having a (meth) acrylfluorenyl group.

The hard coat composition may further include one or more members selected from the group consisting of a solvent, a photoinitiator, and an additive. The additive may include one or more members selected from the group consisting of inorganic nano particles, a leveling agent, and a stabilizer. In addition, each component generally used in the technical field may further include, for example, an antioxidant, a UV absorber, Surfactants, lubricants, antifoulants, etc.

<Shading pattern>

The shading pattern may be provided as at least a part of a bezel or housing of a front panel or a display device suitable for the front panel. The light-shielding pattern may be formed on the display element side of the front panel. The light-shielding pattern can hide each wiring of the display device to prevent users from seeing the wiring. The color and / or material of the light-shielding pattern is not particularly limited, and may be formed of resin materials having various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. In addition, a shape may be given to the light-shielding pattern to prevent air bubbles from entering due to a step between the light-shielding pattern and the display portion and visual recognition of the boundary portion. For example, in the aforementioned light-shielding pattern, an inclination angle formed between the light-shielding pattern and the front panel on which the light-shielding pattern is formed may be 0.1 ° to 25 °.

<Manufacturing method of circular polarizing plate>

The manufacturing method of the circularly polarizing plate will be described by taking the circularly polarizing plate 100 shown in FIG. 1 (a) as an example. The circular polarizing plate 100 can be manufactured by laminating a polarizing plate 1 and a phase difference film 2 with an adhesive layer 13 therebetween.

The polarizing plate 1 can be manufactured by laminating the polarizer 10 and the protective films 11 and 12 separately via an adhesive layer. The polarizing plate can be manufactured by preparing a long member and cutting it into a predetermined shape after laminating each member with a roll to roll, or cutting each member into a predetermined one. Fit after shape. After the polarizer 10 is bonded to the protective films 11 and 12, a heating step and a humidity adjustment step can be set to adjust the moisture content of the polarizing plate. Next, an adhesive layer 13 formed on the release film is laminated on the protective film 12.

The phase difference film 2 can be manufactured, for example, as described below. An alignment film is formed on the substrate, and a coating liquid containing a polymerizable liquid crystal compound is applied on the alignment film. When the polymerizable liquid crystal compound is aligned, the active energy ray is irradiated to harden the polymerizable liquid crystal compound. An adhesive layer 14 formed on the release film is laminated on a layer hardened by the polymerizable liquid crystal compound. Next, the substrate and / or the alignment film are peeled off. As for the phase difference film 2, it can be manufactured by preparing a long member and cutting it into a predetermined shape after laminating the respective members from a roll to a roll, or by cutting each member into a predetermined shape and pasting it. Together.

Then, the release film laminated on the adhesive layer 13 is peeled off, and the phase difference film 2 and the polarizing plate 1 are bonded together via the adhesive layer 13 to produce a circular polarizing plate 100.

<Use>

The circular polarizing plate can be used in various display devices. The display device means a device having a display element, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the display device include a liquid crystal display device, an organic EL display device, an inorganic electroluminescence (hereinafter also referred to as an inorganic EL) display device, an electron emission display device (such as an electric field emission display device (also referred to as a FED), and a surface electric field emission display Device (also known as SED)), electronic paper (display device using electronic ink or electrophoretic elements, plasma display device, projection display device (e.g., Grating Light Valve (also known as GLV) display device, A display device with a digital micromirror device (also known as a DMD), a piezoelectric ceramic display, and the like. The liquid crystal display device also includes any of a transmissive liquid crystal display device and a semi-transmissive liquid crystal display device. These display devices can be display devices that display two-dimensional images or stereoscopic display devices that display three-dimensional images. Circular polarizers can be particularly effectively used in organic EL display devices or inorganic EL display devices.

In FIGS. 3 (a) and (b), the organic EL display devices 104 and 105 have the following layer structure: The circular polarizing plate is laminated on the organic layer through the adhesive layer 14 laminated on the phase difference film 20. EL display element 3.

    [Example]    

(1) Method for measuring film thickness

Measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) Method for measuring moisture permeability

The measurement of the moisture permeability of the protective film was performed in accordance with the moisture permeability test (Dish method) of JIS Z0208. The measurement conditions were performed at a temperature of 40 ° C and a relative humidity of 90%.

(3) Method for measuring phase difference

The measurement was performed using a phase difference measuring device KOBRA-PR (manufactured by Oji Measurement Co., Ltd.).

(4) Method for measuring moisture content of polarizing plate

The moisture content of the polarizing plate is calculated according to the dry weight method. The weight W1 of the polarizing plate after drying at 105 ° C for 2 hours and the weight W0 of the polarizing plate before drying were measured. This equivalent value was substituted into the following formula to calculate the moisture content of the polarizing plate.

Moisture content of polarizing plate [%] = {(W0-W1) ÷ W0} × 100

<Production of Polarizer A>

A polyvinyl alcohol film (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) with a thickness of 20 μm is uniaxially stretched to about 4 times by dry stretching, and then immersed in a tensioned state at 40 ° C. After 40 seconds of pure water, it was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.052 / 5.7 / 100 at 28 ° C. for 30 seconds to perform a dyeing treatment. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Subsequently, it was washed with pure water at 8 ° C for 15 seconds, and maintained at a tension of 300N at 60 ° C and 50 seconds, followed by drying at 75 ° C and 20 seconds to obtain iodine adsorption and alignment in a polyvinyl alcohol film. A polarizing film with a thickness of 8 μm.

<Production of Polarizer B>

A polyvinyl alcohol film with a thickness of 30 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) was used instead of a polyvinyl alcohol film with a thickness of 20 μm. A polarizer (B) with a thickness of 13 μm formed by iodine adsorption and alignment in the vinyl alcohol film.

<Production of Polarizer C>

A polyvinyl alcohol film with a thickness of 60 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) was used instead of a polyvinyl alcohol film with a thickness of 20 μm. A polarizer (C) having a thickness of 23 μm formed by iodine adsorption and alignment in the vinyl alcohol film.

<Production of Polarizer D>

A polyvinyl alcohol film with a thickness of 75 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) was used instead of a polyvinyl alcohol film with a thickness of 20 μm. A polarizer (D) with a thickness of 28 μm formed by iodine adsorption and alignment in the vinyl alcohol film.

<Preparation of water-based adhesive>

With respect to 100 parts by weight of water, 3 parts by weight of carboxyl-modified polyvinyl alcohol [purchased from Kuraray Co., Ltd., trade name "KL-318"] was dissolved, and 1.5 parts by weight of water solution was added as a water-soluble ring. Polyamine epoxy-based additive of oxyresin [purchased from Taoka Chemical Industry Co., Ltd., trade name "Sumirez (registered trademark) 650 (30)", 30% by weight solid solution in water] to prepare an aqueous adhesive.

<Preparation of Adhesive Layer>

Adhesive layer A: An acrylic adhesive layer having a thickness of 25 μm is prepared on a release film.

Adhesive layer B: An acrylic adhesive layer having a thickness of 5 μm is prepared on a release film.

Adhesive layer C: An acrylic adhesive layer having a thickness of 20 μm was prepared on a release film.

<Preparation of protective film>

Prepare the following protective films.

Protective film A: a norbornene-based resin film having a thickness of 20 μm.

Protective film B: a norbornene-based resin film having a hard coat layer formed on one side, and the thickness of the protective film B is 52 μm.

Protective film C: A TAC film with a hard coat layer formed on one side, and the thickness of the protective film C is 31 μm.

Protective film D: a norbornene-based resin film having a hard coat layer formed on one surface thereof, and the thickness of the protective film D is 29 μm.

Protective film E: TAC film with a thickness of 40 μm.

Protective film F: a norbornene-based resin film having a thickness of 13 μm.

Protective film G: TAC film with a thickness of 25 μm.

Protective film H: TAC film with a thickness of 20 μm.

<Production of Phase Difference Film>

5 parts (weight average molecular weight: 30,000) of the photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) were mixed as ingredients, and the obtained mixture was stirred at 80 ° C. for 1 hour to obtain a composition for forming an alignment film. .

1.0 part of a leveling agent (F-556; manufactured by DIC Corporation) and a polymerization initiator were added to a mixture in which the polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B shown below were mixed at a mass ratio of 90:10. 6 parts of 2-dimethylamino-2-benzyl-1- (4-morpholinylbenzyl) butan-1-one ("Irgacure 369 (Irg369)", manufactured by BASF Japan Co., Ltd.).

Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the composition for forming a phase difference layer was obtained by stirring at 80 ° C for 1 hour.

The polymerizable liquid crystal compound A is produced by a method described in Japanese Patent Application Laid-Open No. 2010-31223. The polymerizable liquid crystal compound B is produced by a method described in Japanese Patent Application Laid-Open No. 2009-173893. The respective molecular structures are shown below.

[Polymerizable liquid crystal compound A]

[Polymerizable liquid crystal compound B]

[Production of a laminate including a substrate, an alignment film, and a layer hardened by a polymerizable liquid crystal compound]

The base material was subjected to a corona treatment on a 50 μm-thick cyclic polyolefin-based film [trade name “ZF-14-50” manufactured by Zeon Corporation of Japan]. The composition for forming an alignment film was applied to the surface subjected to the corona treatment using a rod coater. The coating film of the composition for forming an alignment film was dried at 80 ° C. for 1 minute. Using a polarized UV irradiation device [trade name "SPOT CURE SP-9" of Ushio Denki Co., Ltd.], at a wavelength of 313nm of the cumulative light amount: 100mJ / cm ² , the polarized UV was irradiated at an axis angle of 45 ° to Coating film to obtain alignment film.

Subsequently, the composition for forming a phase difference layer was coated on an alignment film using a bar coater, and dried at 120 ° C. for 1 minute. By using a high-pressure mercury lamp [Ushio Electric Co., Ltd.'s trade name: "Unicure VB-15201BY-A"], the dried coating film is irradiated with ultraviolet light (under a nitrogen atmosphere, the accumulated light amount at a wavelength of 365 nm: 500 mJ / cm ² ) Polymerizing a polymerizable liquid crystal compound. Thereby, a laminated body including a substrate, an alignment film, and a layer hardened by a polymerizable liquid crystal compound is obtained.

The in-plane phase difference value Re (λ) of the layer hardened by the polymerizable liquid crystal compound manufactured according to the above method is used for bonding the laminated body to glass via an adhesive, and the cyclic polyolefin system to be used as a base material. After the film was peeled off, the measurement was performed using a measuring machine [Oji Measurement Co., Ltd., trade name "KOBRA-WPR"]. The measurement results of the phase difference values Re (λ) at each wavelength were Re (450) = 121 nm, Re (550) = 142 nm, and Re (650) = 146 nm. The layer system hardened by the polymerizable liquid crystal compound functions as a bit. Function of phase contrast film. Based on these values, Re (450) / Re (550) = 0.85 and Re (650) / Re (550) = 1.03.

<Preparation of the front panel>

A glass plate having a thickness of 0.4 mm manufactured by Corning was prepared.

[Example 1]

The protective film B is bonded to one surface of the polarizer A through the water-based adhesive, and the protective film A is bonded to the other surface through the water-based adhesive. A drying process is performed to produce a polarizing plate. The moisture content of the polarizer is 1.11%.

An adhesive layer B is laminated on the protective film A of the polarizing plate, and the release film is peeled off. The laminated body is laminated on the exposed adhesive layer B so that the layer hardened by the polymerizable liquid crystal compound becomes a bonding surface, and then the substrate is peeled off. Thereby, a circular polarizing plate composed of the protective film B / the polarizer A / the protective film A / the adhesive layer B / the phase difference film was produced.

[Examples 2 to 4, Comparative Examples 1 to 2]

A circularly polarizing plate was produced in the same manner except that the moisture content of the polarizer, the protective film, and the polarizing plate was changed to those shown in Table 1 below. In addition, the moisture content of the polarizing plate is adjusted by adjusting the drying temperature and the drying time.

<Heat resistance test>

An adhesive layer A is laminated on the phase difference film of the produced circular polarizing plate. The release film was peeled, and the circularly polarizing plate was laminated | stacked on the glass plate via the exposed adhesive layer A. Furthermore, an adhesive layer C is laminated on a protective film (first protective film) on the polarizing plate opposite to the phase difference film side. The release film was peeled, and a front panel was laminated on the exposed adhesive layer C. Thereby, an evaluation sample composed of a glass plate (front panel) / adhesive layer C / circular polarizing plate / adhesive layer A / glass plate was prepared.

The sample for evaluation was put into an oven at 85 ° C for 400 hours. The in-plane phase difference value of the circular polarizing plate before and after the measurement was measured, and the difference ΔRe was calculated. Moreover, the phase difference value of the center part in the surface of a circularly polarizing plate was measured. The wavelength at which the phase difference in the plane was measured was 547 nm. The above results are shown in Table 1. In the circular polarizing plate of the embodiment, the degree of phase difference reduction was small, and the reflected light after the heat resistance test was not colored. On the other hand, in the circular polarizing plate of the comparative example, the degree of phase difference reduction was large, and the reflected light was colored red.

    [Industrial availability]    

According to the present invention, in a circular polarizing plate having a phase difference film including a layer hardened by a liquid crystal compound, it is possible to suppress the reflected light compared to the initial reflected light when the circular polarizing plate is placed in a high temperature environment with the cover glass attached. Color changes are useful.

Claims (4)

A circular polarizing plate includes: a polarizing plate having a first protective film on one area layer of a polarizer and a second protective film on another area layer of the polarizer; and a phase difference film including a polymerizable liquid crystal A layer hardened by a compound; wherein the circularly polarizing plate meets at least one of the following conditions 1 and 2; condition 1: the moisture permeability of the aforementioned first protective film is x (g / m ² ‧ 24 hours) When the moisture permeability of the aforementioned second protective film is y (g / m ² ‧ 24 hours), the formula (1) is satisfied; 1 / x + 1 / y ≧ 0.0030 Formula (1) Condition 2: Moisture content of the aforementioned polarizing plate It is 3.00% or less.     The circular polarizing plate as described in item 1 of the scope of patent application meets both conditions 1 and 2.         The circular polarizing plate according to item 1 or 2 of the scope of patent application, wherein the polarizing plate is provided with a front panel on the side opposite to the side where the phase difference film is laminated.         The circular polarizing plate according to any one of claims 1 to 3, wherein the thickness of the polarizer is 13 μm or less.