JP2017003739A - Hard coat film, polarizing plate, display, and method for manufacturing hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film having a low retardation, causing no interference fringes, and having excellent adhesiveness of a hard coat layer to a substrate and a high hardness.SOLUTION: A hard coat film 110 includes: a substrate 111 obtained by photo-curing a first photopolymerizable composition comprising a first polymerizable compound and a first photopolymerization initiator, in which 40 wt.% or more of the first polymerizable compound is a compound having a urethane skeleton and 2 or 3 (meth)acryloyl groups; and a hard coat layer 112 obtained by photo-curing a second photopolymerizable composition comprising a second polymerizable compound and a second photopolymerization initiator on the substrate 111, in which 50 mass% or more of the second polymerizable compound is a compound having a urethane skeleton and 6 or more (meth)acryloyl groups.SELECTED DRAWING: Figure 1

Description

  The present invention can be used as a protective film in, for example, displays such as liquid crystal displays, plasma displays, electrochromic displays, light emitting diode displays, and electroluminescence (EL) displays, and display components such as touch panels, and functional films. It is related with the hard coat film which can be used as.

  A protective film for a polarizing plate used in a liquid crystal display, an organic EL display, or the like is provided with a resin layer in order to give it various functions. Examples of the resin layer include an antistatic layer for providing an antistatic function, an antireflection layer for suppressing reflection, and a hard coat layer for improving surface hardness. In particular, the hard coat layer is indispensable for a protective film for display use, and may be provided as a lower layer of the antireflection layer as well as being provided alone.

  The hard coat layer is usually formed on a transparent substrate. When the difference in refractive index between the hard coat layer and the substrate increases, the light reflected on the upper surface of the hard coat layer (ie, the display surface) and the lower surface of the hard coat layer (ie, the hard coat layer and the transparent substrate) Interference with the light reflected at the interface between the rainbow and the rainbow color unevenness (interference fringes). This color unevenness becomes a factor that reduces the visibility of the display.

  As one method of reducing interference fringes, a layer (intermediate layer) having a refractive index intermediate between those refractive indexes is provided between the transparent substrate and the hard coat layer, depending on the interface. There is a method for suppressing reflection (see Patent Document 1). Further, as another method of reducing interference fringes, a solvent that can dissolve or swell a transparent substrate is used as a solvent of a coating liquid for forming a hard coat, thereby, between the transparent substrate and the hard coat layer. There is also a method in which a refractive index gradient layer is generated and the refractive index is continuously changed in the thickness direction between the transparent substrate and the hard coat layer (see Patent Document 2).

  However, the method of providing the intermediate layer requires a process for forming the intermediate layer, which increases the manufacturing cost. Further, in the method using a solvent that dissolves or swells the transparent substrate, the solvent evaporates before the refractive index gradient layer having a thickness necessary for eliminating the interference fringes is formed, and it is difficult to suppress the interference fringes. is there. And in order to melt | dissolve or swell a transparent base material, this method had the subject that sufficient hardness of a hard-coat was not obtained.

  By the way, the liquid crystal display utilizes the birefringence of the liquid crystal molecules for display. For this reason, among members constituting the liquid crystal display, those other than the liquid crystal material, the phase difference plate, and the polarizing plate are often designed as having no phase difference. When members other than the liquid crystal material, the phase difference plate, and the polarizing plate have even a slight retardation, the visibility problem peculiar to the liquid crystal display, in particular, the oblique visibility problem becomes remarkable. Therefore, it is desirable that the base material and the coating film used in the liquid crystal display or the like have no phase difference.

  Generally, materials such as triacetyl cellulose (TAC) and polyethylene terephthalate (PET) are used for the base material of the optical film. When such a material is used, a phase difference occurs in the base material due to the properties of the material itself and the manufacturing process of the base material. As described above, when a liquid crystal display having a hard coat substrate having a phase difference is used, the visibility is likely to deteriorate. For this reason, in recent years, attempts have been made to reduce the retardation of the base material (Non-Patent Document 1).

The thickness direction retardation R _th of a film or the like is expressed by the formula (I) and increases in proportion to the film thickness d. Further, the birefringence Δn is represented by the formula (II). From the formula (I), it can be seen that for a substrate having a phase difference, the visibility is improved when the film thickness is reduced.

R _th = Δn × d (I)
Δn = (2π / 45 kT) × {(ND ² +2) ² / ND} × (σ _‖ −σ _⊥ ) × σ (II)
In the above formulas (I) and (II), R _th represents the thickness direction retardation, Δn represents the birefringence, d represents the film thickness, k represents the Boltzmann constant, and T represents the absolute temperature. , ND represents the average refractive index, σ _‖ −σ _⊥ represents the main polarization difference, and σ represents the stress.

  In addition, it is desirable that the coating liquid applied to the base material can form a layer having a small phase difference. In particular, when a thermosetting resin having a large shrinkage is used, the stress σ described in the above formula (II) increases, resulting in a large phase difference.

JP 2000-111706 A JP 2003-131007 A JP 2013-159691 A

Ryo Suzuki, “Development and Trends of Low Birefringence Optical Film”, Monthly Display, Techno Times, April 2012

  An object of the present invention is to provide a hard coat film having low retardation, no interference fringes, excellent adhesion of a hard coat layer to a substrate, and high hardness.

  According to the first aspect of the present invention, it is obtained by photocuring a first photopolymerizable composition containing a first polymerizable compound and a first photopolymerization initiator, and 40 mass of the first polymerizable compound. % Of the second photopolymerizable composition containing a base material which is a compound containing a urethane skeleton and two or three (meth) acryloyl groups, a second polymerizable compound and a second photopolymerization initiator. Obtained by photocuring on the base material, 50% by mass or more of the second polymerizable compound comprises a hard coat layer that is a compound containing a urethane skeleton and six or more acryloyl groups. A coated film is provided.

  In this hard coat film, the base material may have a thickness of 20 to 100 μm. The hard coat layer may have a thickness of 2 to 15 μm.

  According to the 2nd side surface of this invention, the polarizing plate provided with the hard coat film which concerns on a 1st side surface is provided.

  According to the 3rd side surface of this invention, the display provided with the hard coat film which concerns on a 1st side surface is provided.

  According to the fourth aspect of the present invention, the first photopolymerizable composition containing the first polymerizable compound and the first photopolymerization initiator is applied on a support to form a first coating film. 40% by mass or more of the first polymerizable compound is a compound containing a urethane skeleton and two or three (meth) acryloyl groups, and the first coating film is photocured to form the support. And applying a second photopolymerizable composition containing a second polymerizable compound and a second photopolymerization initiator on the substrate to form a second coating film. A step in which 50% by mass or more of the second polymerizable compound is a compound containing a urethane skeleton and six or more acryloyl groups, and the second coating film is photocured to form the group A step of obtaining a hard coat layer supported by a material, and before forming the second coating film or the second coating film. After curing, the production method of the hard coat film including a step of removing the substrate from the support is provided.

  In this production method, the first coating film may be photocured in an oxygen-containing atmosphere, and the second coating film may be photocured in an inert atmosphere.

  According to the present invention, there is provided a hard coat film having low retardation, no interference fringes, excellent adhesion of the hard coat layer to the substrate, and high hardness.

Sectional drawing which shows the hard coat film which concerns on 1 aspect roughly. Sectional drawing which shows an example of a polarizing plate roughly. Sectional drawing which shows an example of a display roughly.

<Hard coat film>
As a result of intensive studies, the present inventors have adopted the following configuration for a hard coat film provided with a hard coat layer on one side or both sides of the base material, resulting in low retardation and no occurrence of interference fringes. It was found that a hard coat film having excellent hardness and a high hardness can be realized. Hereinafter, this will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a hard coat film according to one embodiment.
The hard coat film 110 includes a base material 111 and a hard coat layer 112. The hard coat layer 112 is formed on one surface of the substrate 111. The hard coat layer 112 may be formed on both surfaces of the substrate 111.

[Base material]
As the base material 111, what is obtained by photocuring the 1st photopolymerizable composition containing the 1st polymeric compound and the 1st photoinitiator is used. When photocuring is used, a substrate with low retardation is obtained.

  The first photopolymerizable composition is a resin whose main component is a resin that is cured through a crosslinking reaction when irradiated with active rays such as ultraviolet rays. The first photopolymerizable composition is, for example, an ultraviolet curable resin.

  The first polymerizable compound includes a compound containing a urethane skeleton and two or three (meth) acryloyl groups. Here, the “(meth) acryloyl group” implies an acryloyl group and a methacryloyl group. Hereinafter, a compound containing a urethane skeleton and two or three (meth) acryloyl groups is referred to as a “first compound”.

  When the first compound having a urethane skeleton is used, a base film having high toughness can be obtained. In addition, as described above, the first compound includes two or three (meth) acryloyl groups. In the case where there is one (meth) acryloyl group, the base material 111 cannot be obtained because it is not three-dimensionally cross-linked even if polymerized. When the number of (meth) acryloyl groups is 4 or more, the crosslinking density becomes too high, and the obtained coating film is not flexible and easily cracks.

  As the first compound, for example, Shikou (registered trademark) UV-7000B (manufactured by Nippon Synthetic Chemical Industry) or UF-8001G (manufactured by Kyoeisha Chemical Co., Ltd.) can be used.

  The first compound preferably has an aromatic ring or alicyclic structure. When such a first compound is used, a substrate having a relatively high strength is obtained.

  The first polymerizable compound may contain only one type of the first compound or may contain two or more types.

  The proportion of the first compound in the first polymerizable compound is 40% by mass or more. This ratio is preferably 50% by mass or more. When this ratio is small, high hardness cannot be achieved.

  The first polymerizable compound can further contain a compound other than the first compound. As a compound other than the first compound, for example, a compound that does not have a urethane skeleton and has a (meth) acryloyl group can be used. As such a compound, for example, a compound containing only one (meth) acryloyl group such as acryloylmorpholine can be used.

  As the first photopolymerization initiator, for example, those generally known as ultraviolet polymerization initiators can be used. For example, a surface curable polymerization initiator, an internal curable polymerization initiator, or a combination thereof can be used as the first photopolymerization initiator.

  Examples of the surface curable polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1- [4- (2-hydroxyethoxy) -phenyl. ] Like α-hydroxy ketones such as 2-hydroxy-2-methyl-1-propan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one An α-aminoketone with a high molar extinction coefficient can be used. Of these, 1-hydroxycyclohexyl phenyl ketone is preferable in that it is less colored. 1-hydroxycyclohexyl phenyl ketone is commercially available, for example, as IRGACURE® 184 from BASF.

  Examples of the internally curable polymerization initiator include acylphosphine oxides such as bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and 2-benzyl-2-dimethylamino-1- (4- An α-aminoketone having an absorption region in the h-line such as morpholinophenyl) -butanone-1 can be used.

  In addition to the above, among the compounds of acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, or thioxanthones, they have performance as surface curable or internal curable initiators. If it is, it can select suitably.

  In the first photopolymerizable composition, the amount of the first polymerization initiator based on the first polymerizable compound is preferably in the range of 0.5 to 15% by mass. If the first polymerization initiator is too much or too little, the hardness of the substrate 111 tends to be low. In particular, when the first polymerization initiator is too much, the coating film may be colored.

  The first photopolymerizable composition can further contain a photosensitizer. As the photosensitizer, for example, n-butylamine, triethylamine, or poly-n-butylphosphine can be used. In the first photopolymerizable composition, the amount of the photosensitizer based on the first polymerization initiator is preferably in the range of 10 to 50% by mass.

  The first photopolymerizable composition can further contain a solvent such as an organic solvent. The solvent may be any solvent as long as it can dissolve other components of the first photopolymerizable composition. As the solvent, for example, methyl ethyl ketone can be used.

  In addition, when a solvent with a high boiling point is used, leveling property (uniform coating property) will improve. Further, when the coating film is thick, the solvent tends to remain in the coating film. Therefore, in selecting the solvent, the balance between the former and the latter is taken into consideration.

  The base material 111 has a thickness of 20 to 100 μm, for example. The thickness of the substrate 111 is preferably in the range of 30 to 70 μm.

[Hard coat layer]
The hard coat layer 112 is formed by photocuring a second photopolymerizable composition containing a second polymerizable compound and a second photopolymerization initiator on the substrate 111. When photocuring is used, a low retardation hard coat layer is obtained.

  Similar to the first polymerizable composition, the second photopolymerizable composition is a resin whose main component is a resin that is cured through a crosslinking reaction when irradiated with active rays such as ultraviolet rays. The second photopolymerizable composition is, for example, an ultraviolet curable resin.

  As described above, the second polymerizable compound includes a compound containing a urethane skeleton and six or more acryloyl groups. Hereinafter, a compound containing a urethane skeleton and six or more acryloyl groups is referred to as a “second compound”.

  The second compound may have an aromatic ring or an alicyclic structure. When the second photopolymerizable composition containing such a second compound is used, the heat resistance and hardness of the hard coat layer 112 are improved.

  As the second compound, for example, UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) can be used. The second polymerizable compound may contain only one kind of the second compound or may contain two or more kinds.

  The proportion of the second compound in the second polymerizable compound is 50% by mass or more. This ratio is preferably 60% by mass or more. When this ratio is small, high hardness cannot be achieved.

  The second polymerizable compound can further contain a compound other than the second compound. As a compound other than the second compound, for example, a compound that does not have a urethane skeleton and has two or more (meth) acryloyl groups can be used. As such a compound, for example, a compound containing three (meth) acryloyl groups such as pentaerythritol triacrylate can be used.

  The proportion of the compound other than the second compound in the second polymerizable compound is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 40% by mass. When this ratio is small, the effect of using a compound other than the second compound does not appear remarkably. Moreover, when this ratio is increased, the hardness of the hard coat film 110 is lowered.

  As the second photopolymerization initiator, for example, those generally known as ultraviolet polymerization initiators can be used. For example, what was demonstrated about the 1st photoinitiator can be used as a 2nd photoinitiator.

  In the second photopolymerizable composition, the amount of the second polymerization initiator based on the second polymerizable compound is preferably in the range of 0.5 to 15% by mass. If the amount of the second polymerization initiator is too small, the hardness of the hard coat becomes low due to insufficient curing. Moreover, when there are too many 2nd polymerization initiators, there exists a possibility that a coating film may color.

  The second photopolymerizable composition can further contain a photosensitizer. As a photosensitizer, what was demonstrated as a photosensitizer of a 1st photopolymerizable composition can be used, for example. In the second photopolymerizable composition, the amount of the photosensitizer based on the second photopolymerization initiator is preferably in the range of 10 to 50% by mass.

  The second photopolymerizable composition can further contain a solvent such as an organic solvent. The solvent may be any solvent as long as it can dissolve other components of the second photopolymerizable composition. As the solvent, for example, methyl isobutyl ketone can be used.

  The second photopolymerizable composition can further comprise a polymer. When a polymer is contained in the second photopolymerizable composition, shrinkage during curing is alleviated and curling can be reduced. In the second photopolymerizable composition, the amount of the polymer based on the second polymerizable compound is preferably 50% by mass or less.

  The second photopolymerizable composition may further contain an additive for imparting antifouling properties, slipperiness, defect prevention, or improving particle dispersibility. As such an additive, for example, polyether-modified polymethylalkylsiloxane, polyether-modified polydimethylsiloxane, fluorine-modified polymer, acrylic copolymer, polyester-modified acrylic-containing polydimethylsiloxane, or silicon-modified polyacryl is used. be able to. In the second photopolymerizable composition, the amount of the additive based on the second polymerizable compound is preferably 5% by mass or less.

  The second photopolymerizable composition may further contain inorganic fine particles or organic fine particles for the purpose of preventing blocking, improving hardness, imparting antiglare properties, imparting antistatic properties, or adjusting the refractive index.

  Examples of the inorganic fine particles include fine particles composed of oxides such as silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, tin oxide, and antimony pentoxide, and composite oxide such as antimony-doped tin oxide and phosphorus-doped tin oxide. Fine particles made of a material can be used. As the inorganic fine particles, fine particles comprising calcium carbonate, talc, clay, kaolin, calcium silicate, aluminum silicate, magnesium silicate, or calcium phosphate can also be used.

  Examples of the organic fine particles include polymethyl methacrylate acrylate resin powder, acrylic-styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene powder, polycarbonate powder, melamine resin powder, and polyolefin resin powder. Can be used.

  The average particle diameter of these fine particles is preferably in the range of 5 nm to 20 μm, and more preferably in the range of 10 nm to 10 μm. These fine particles may be used alone or in combination of two or more.

  The hard coat layer 112 is thinner than the base material 111. The hard coat layer 112 has a thickness of 2 to 15 μm, for example. The thickness of the hard coat layer 112 is preferably in the range of 3 to 10 μm.

  The hard coat layer 112 has a refractive index substantially equal to that of the base material 111. Therefore, the interface between the hard coat layer 112 and the base material 111 has a low reflectance, and therefore interference fringes are hardly generated. Further, the hard coat layer 112 is excellent in adhesion to the base material 111.

[Functional layer]
The hard coat film 110 may further include a functional layer on the hard coat layer 112. The functional layer is, for example, a layer having antireflection performance, antistatic performance, antifouling performance, antiglare performance, electromagnetic wave shielding performance, infrared absorption performance, ultraviolet absorption performance, or color correction performance. The functional layer may be a single layer or a plurality of layers. For example, the antireflection layer may be a single low-refractive index layer or a laminate in which low-refractive index layers and high-refractive index layers are alternately stacked. The functional layer may have a plurality of functions in one layer, for example, an antireflection layer having antifouling performance.

[Method for producing hard coat film]
The hard coat film 110 is manufactured by the following method, for example.
First, a 1st photopolymerizable composition is apply | coated on a support body, and a 1st coating film is formed.

  As the support, for example, a roll-shaped metal body or a polyethylene terephthalate (PET) film) can be used. After applying the first photopolymerizable composition, the support is not deformed in steps such as drying and light irradiation, and can easily peel off the substrate formed by curing the coating film by light irradiation. If it is a thing, it will not specifically limit.

  A well-known method can be used for application | coating to the support body of a 1st photopolymerizable composition. For example, bar coating, dip coating, spin coating, flow coating, spray coating, roll coating, gravure roll coating, air doctor coating, blade coating, wire doctor coating, knife coating, reverse A coating method, a transfer roll coating method, a micro gravure coating method, a kiss coating method, a cast coating method, a slot orifice coating method, a calendar coating method, or a die coating method can be used.

  Next, a 1st coating film is dried as needed. Subsequently, the first coating film is irradiated with light such as ultraviolet rays to cause photocuring of the first coating film. Thereby, the base material 111 supported by the support body is obtained.

The light source used for photocuring is not particularly limited as long as it is a light source that generates light such as ultraviolet rays. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or an electrodeless discharge tube can be used. The irradiation amount is set to 100 to 800 mJ / cm ² , for example.

  Subsequently, a 2nd photopolymerizable composition is apply | coated on the base material 111, and a 2nd coating film is formed. For the application of the second photopolymerizable composition to the substrate 111, for example, the method described for the application of the first photopolymerizable composition to the support can be used.

Next, the second coating film is dried as necessary. Subsequently, the second coating film is irradiated with light such as ultraviolet rays to cause photocuring of the second coating film. Thereby, the hard coat layer 112 supported by the base material 111 is obtained. As a light source used for photocuring of a 2nd coating film, what was demonstrated regarding photocuring of a 1st coating film can be used, for example. The irradiation amount is set to 150 to 500 mJ / cm ² , for example.

  Then, the base material 111 is peeled from the support. Thereby, the hard coat film 110 is obtained.

  In addition, you may perform peeling from the support body of the base material 111 before forming a 2nd coating film. In the above-described method, the hard coat layer 112 is provided only on one side of the base material 111, but the hard coat layer 112 may be provided on both sides of the base material 111.

  In this method, it is preferable to perform photocuring of the first coating film in an oxygen-containing atmosphere such as an air atmosphere, and to perform photocuring of the second coating film in an inert atmosphere such as a nitrogen atmosphere. Since oxygen inhibits photocuring, in the first coating film photocured in an oxygen-containing atmosphere, at least a part of the first photopolymerizable composition located on the surface remains uncured. That is, the second coating film can be formed in a state where a relatively large number of unreacted functional groups are present on the surface of the substrate 111. Therefore, the adhesion of the hard coat layer 112 to the substrate 111 can be further enhanced.

[Features of hard coat film]
The hard coat film 110 has low retardation, no interference fringes, excellent adhesion of the hard coat layer 112 to the substrate 111, and high hardness. The hard coat film 110 typically has the following characteristics.

In this hard coat film 110, the tensile strength of the base material 111 is typically 40 N / mm ² or more, and the tensile elongation represented by the following formula (III) is 10% or more.
Tensile elongation = (L ₁ −L ₀ ) / L ₀ (III)
Here, in the above formula (III), L ₀ represents the length of the base material 111 before pulling, and L ₁ represents the length of the base material 111 at the time of fracture.

The hard coat film 110 typically has a thickness direction retardation R _th represented by the above formula (IV) of 1 nm or less.

R _th = {(N _x + N _y ) / 2−N _z } × d (IV)
Here, N _x is the refractive index in the X direction defined in the plane of the hard coat film 110, N _y is the refractive index in the Y direction that is in the plane of the hard coat film 110 and perpendicular to the X direction, and N _z is the hard index. It is the refractive index in the thickness direction of the coat film 110. N _x and N _y satisfy the relationship represented by N _x ≧ N _y , and the X direction corresponds to the slow axis. D is the thickness of the hard coat film 110.

  The hard coat film 110 typically has a scratch hardness of 3H or more. Here, the scratch hardness is a value obtained by a pencil method defined in JIS K5600-5-4: 1999 (ISO / DIS 15184: 1996).

<Polarizing plate>
The hard coat film 110 described above can be used, for example, as a protective film for a polarizing plate.

  FIG. 2 is a cross-sectional view schematically showing an example of a polarizing plate. The polarizing plate 10 includes a hard coat film 110, a protective film 120, and a polarizing layer 130.

  The hard coat film 110 serves as a protective film for protecting the polarizing layer 130. The hard coat film 110 is disposed so that the hard coat layer 112 faces the polarizing layer 130 with the substrate 111 interposed therebetween.

  The protective film 120 faces the hard coat film 110 with the polarizing layer 130 interposed therebetween. The protective film 120 is a transparent resin layer having low retardation, low moisture permeability, and high strength.

  The protective film 120 is, for example, a triacetylene cellulose (TAC) film or a polyethylene terephthalate (PET) film. As the protective film 120, the hard coat film 110 described with reference to FIG.

  The polarizing layer 130 is a layer having a function as a polarizer. The polarizing layer 130 includes, for example, a layer obtained by adsorbing iodine or an iodine compound to polyvinyl alcohol and stretching it in one direction.

  Since the polarizing plate 10 includes the hard coat film 110 described above, interference fringes caused by the hard coat layer and the like are not generated, and the hard coat layer itself has low retardation. Therefore, the polarizing plate 10 is excellent in optical characteristics.

  Moreover, the hard coat film 110 is excellent in the adhesion of the hard coat layer to the substrate and has a high hardness. Therefore, the polarizing plate 10 is excellent in mechanical strength.

<Display>
The hard coat film 110 described above can be used, for example, as a protective layer for protecting the display screen.

FIG. 3 is a cross-sectional view schematically showing an example of a display.
A display 1 shown in FIG. 3 is a transmissive liquid crystal display. The display 1 includes a display panel 20, a pair of polarizing plates 10, and a backlight unit 30.

  The display panel 20 is a liquid crystal display panel. The display panel 20 includes a pair of substrates 210 and 220 and a liquid crystal layer 230 sandwiched therebetween. The substrate 210 is, for example, an active matrix substrate. The substrate 220 is, for example, a color filter substrate.

  The backlight unit 30 is installed so as to face the substrate 210. The backlight unit 30 illuminates the display panel 20 from the back side.

  The polarizing plate 10 has the structure described with reference to FIG. The polarizing plate 10 is affixed on the front surface and the back surface of the display panel 20 so that the protective films 120 face the display panel 20. In addition, about the polarizing plate 10 located between the display panel 20 and the backlight unit 30, you may install the protective film 120 instead of the hard coat film 110. FIG.

  Since the display 1 includes the hard coat film 110 described above, interference fringes caused by the hard coat layer and the like are not generated, and the hard coat layer itself has low retardation. Therefore, the display 1 is excellent in display quality.

  Moreover, the hard coat film 110 is excellent in the adhesion of the hard coat layer to the substrate and has a high hardness. Therefore, the display 1 is excellent in the mechanical strength of the screen.

  Here, an example in which the hard coat film 110 is used in a transmissive liquid crystal display is shown, but the hard coat film 110 may be other displays such as a transflective liquid crystal display, a reflective liquid crystal display, and an organic EL display. May be used.

  Moreover, you may use the hard coat film 110 in articles | goods other than a display. For example, the hard coat film 110 may be used as a protective film for a touch panel.

  Hereinafter, examples will be described. However, the present invention is not limited to the following examples.

<Evaluation method>
First, the evaluation method of the hard coat film mentioned later is demonstrated.

[Thickness direction retardation R _th ]
The thickness direction retardation R _th of the hard coat film was determined by the following method. That is, using a spectroscopic ellipsometer M220 (manufactured by JASCO Corp.), retardation Δ (λ) was measured from a direction inclined by 45 ° with respect to the normal direction of the substrate on which the hard coat layer was formed. Then, R _th was calculated from the three-dimensional refractive index obtained using this value, using the above formula (IV). The measurement wavelength of the spectroscopic ellipsometer was 590 nm.

[Tensile properties]
The tensile properties of the substrate were examined by the following method. First, the base material was cut into a size of 100 mm × 15 mm to obtain a strip-shaped sample. About this sample, the measurement using Shimadzu Corporation company-made small tabletop testing machine EZ-L was performed. Here, the distance between chucks at the start of measurement was 50 mm, and the tensile speed was 5 mm / min. The tensile elongation was calculated using the above formula (III).

[Interference fringes]
The back surface of the hard coat film, that is, the surface not provided with the hard coat layer was rubbed with sandpaper, and then a matte black paint was applied to this surface. And the surface of the hard coat film was illuminated with a fluorescent lamp (three-wave fluorescent lamp) from the front, and visually observed. And it evaluated on the following references | standards.

A: No interference fringes are observed.
○: Almost no interference fringes are observed.
Δ: Slight interference fringes are observed.
X: Remarkable interference fringes are observed.

[Scratch hardness]
The scratch hardness of the hard coat film was measured by a pencil method defined in JIS K5600-5-4: 1999 (ISO / DIS 15184: 1996).

[Adhesion]
The adhesion of the hard coat layer to the substrate was evaluated by a cross-cut method defined in JIS K5600-5-6: 1999 (ISO 2409: 1992). Here, a part of the hard coat layer was divided into 10 × 10 thin pieces arranged in a grid pattern. And the number of the flakes which produced peeling was evaluated in light of the following references | standards.

○: Peeling could not be confirmed.
Δ: 20 or less flakes were peeled off.
X: More than 20 flakes were peeled off.

<Synthesis of urethane>
Next, a method for synthesizing the urethane used in the production of the hard coat film will be described.

[Urethane U1]
31.5 parts by mass of isophorone diisocyanate and 0.1 parts by mass of dibutyltin dilaurate were charged into a reaction vessel equipped with a condenser, a stirrer, and a thermometer. These mixed liquids were kept at 50 ° C., and 68.4 parts by mass of ε-caprolactone 1 mol-modified 2-hydroxyethyl acrylate was added dropwise over 1 hour. Subsequently, these mixed liquids were stirred at 90 ° C. for 10 hours to react them.

  During this reaction, the amount of isocyanate remaining in the liquid was measured by Fourier transform infrared spectroscopy (FT-IR) in order to confirm the progress of the urethanization reaction. At the end of 10 hours of stirring, the isocyanate was zero.

  As described above, 99.9 parts by mass of urethane acrylate (hereinafter referred to as urethane U1) represented by the following chemical formula was obtained. In the following chemical formula, A represents an acryloyloxy group.

[Urethane U2]
23.1 parts by mass of isophorone diisocyanate and 0.1 parts by mass of dibutyltin dilaurate were charged into a reaction vessel equipped with a condenser, a stirrer, and a thermometer. These mixed liquids were kept at 50 ° C., and 76.8 parts by mass of ε-caprolactone 2 mol-modified 2-hydroxyethyl acrylate was added dropwise over 1 hour. Subsequently, these mixed liquids were stirred at 90 ° C. for 10 hours to react them.

  During this reaction, the amount of isocyanate remaining in the liquid was measured by Fourier transform infrared spectroscopy (FT-IR) in order to confirm the progress of the urethanization reaction. At the end of 10 hours of stirring, the isocyanate was zero.

  As described above, 99.9 parts by mass of urethane acrylate (hereinafter referred to as urethane U2) represented by the following chemical formula was obtained. In the following chemical formula, A represents an acryloyloxy group.

<Manufacture of hard coat film>
Hard coat films were produced by the method described below, and the performance of each hard coat film was evaluated.

[Hard coat film HCF1]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Urethane U1 57.14 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF Corp.) 2.86 parts by mass Methyl ethyl ketone 40.00 parts by mass This coating solution was used as a PET film Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.) Further, it was applied by a bar coating method so that the cured film thickness was 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 80 N / mm ² and a tensile elongation of 10%. That is, this base material had good tensile properties.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

  The hard coat film HCF1 obtained as described above did not generate interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 4H, and the phase difference R _th was 0.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF2]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Purple light (registered trademark) UV-7000B (manufactured by Nippon Synthetic Chemical Industry) 60.00 parts by mass ACMO (registered trademark; manufactured by KJ Chemicals) 25.71 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 29 parts by mass Methyl ethyl ketone 10.00 parts by mass This coating solution was applied to Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.), which is a PET film, by a bar coating method so that the cured film thickness becomes 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 75 N / mm ² and a tensile elongation of 15%. That is, this base material had good tensile properties.

  Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF2 obtained as described above did not produce interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 4H, and the phase difference R _th was 1 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF3]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Urethane U1 28.57 parts by weight Shimitsu (registered trademark) UV-7000B (manufactured by Nippon Synthetic Chemical Industry) 28.57 parts by weight Irgacure (registered trademark) 184 (manufactured by BASF) 2.86 parts by weight Methyl ethyl ketone 40.00 parts by weight Part This coating solution was applied to Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.), which is a PET film, by a bar coating method so that the cured film thickness becomes 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 60 N / mm ² and a tensile elongation of 15%. That is, this base material had good tensile properties.

  Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF3 obtained as described above did not produce interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 3H, and the phase difference R _th was 0.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF4]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Urethane U1 51.43 parts by mass UF8001G (manufactured by Kyoeisha Chemical Co., Ltd.) 5.71 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 2.86 parts by mass Methyl ethyl ketone 40.00 parts by mass It was applied to a certain Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.) so as to have a cured film thickness of 40 μm by a bar coating method. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 80 N / mm ² and a tensile elongation of 10%. That is, this base material had good tensile properties.

  Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF4 obtained as described above did not generate interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 3H, and the phase difference R _th was 0.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF5]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Urethane U2 28.57 parts by mass ACMO (registered trademark; manufactured by KJ Chemicals) 28.57 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 2.86 parts by mass Methyl ethyl ketone 40.00 parts by mass It was applied to Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.), which is a PET film, by a bar coating method so that the cured film thickness becomes 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 50 N / mm ² and a tensile elongation of 10%. That is, this base material had good tensile properties.

  Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF5 obtained as described above did not generate interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 3H, and the phase difference R _th was 0.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF6]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Epoxy ester 3002A (manufactured by Kyoeisha Chemical Co., Ltd.) 57.14 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 2.86 parts by mass Methyl ethyl ketone 40.00 parts by mass This coating solution was used as Lumirror T60 (thickness) as a PET film. 75 μm; manufactured by Toray Industries, Inc.) by a bar coating method so that the cured film thickness was 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 30 N / mm ² and a tensile elongation of 20%. That is, this base material had low strength.

  Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF6 obtained as described above did not produce interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the phase difference R _th was 0.5 nm, and the retardation was low. However, the scratch hardness was H and the hardness was low.

[Hard coat film HCF7]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Urethane U1 17.14 parts by weight Aronix (registered trademark) M6100 (manufactured by Toagosei Co., Ltd.) 40.00 parts by weight Irgacure (registered trademark) 184 (manufactured by BASF) 2.86 parts by weight Methyl ethyl ketone 40.00 parts by weight Was applied to Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.), which is a PET film, by a bar coating method so that the cured film thickness becomes 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 25 N / mm ² and a tensile elongation of 20%. That is, this base material had low strength.

  Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF7 obtained as described above did not produce interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the phase difference R _th was 0.5 nm, and the retardation was low. However, the scratch hardness was 2H, and the hardness was low.

[Hard coat film HCF8]
A hard coat film was produced by the method described below.

First, a coating solution having the following composition was prepared.
Urethane acrylate UA306I (manufactured by Kyoeisha Chemical Co., Ltd.) 36.36 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 2.86 parts by mass Methyl ethyl ketone 40.00 parts by mass 75 μm; manufactured by Toray Industries, Inc.) by a bar coating method so that the cured film thickness was 40 μm. After the coating film was dried, it was irradiated with 300 mJ / cm ² of ultraviolet rays by a high-pressure mercury lamp in an air atmosphere. Thereby, the coating film was photocured. Thereafter, the coating film was peeled off from the PET film, but cracks were generated and could not be peeled off as a substrate.

[Hard coat film HCF9]
A hard coat film was produced by the method described below.

First, a TAC film having a thickness of 40 μm was prepared as a substrate.
Next, a hard coat layer was formed on the substrate by the same method as described for the hard coat film HCF1.

  The hard coat film HCF9 obtained as described above produced interference fringes, and the adhesion of the hard coat layer to the substrate was insufficient.

Further, the phase difference R _th was 15 nm, and the scratch hardness was 2H. That is, the hard coat film HCF9 had high retardation and low hardness.

  Table 1 summarizes the evaluation results and the like of the hard coat films HCF1 to HCF9.

[Hard coat film HCF10]
A hard coat film was produced by the method described below.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) 25.45 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 10.91 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

  The hard coat film HCF10 obtained as described above did not generate interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 4H, and the phase difference R _th was 0.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF11]
A hard coat film was produced by the method described below.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) 36.36 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Irgacure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass 60.00 parts by mass of methyl isobutyl ketone This coating solution was applied onto the above base material by a bar coating method so that the cured film thickness was 5 μm. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

  The hard coat film HCF11 obtained as described above did not produce interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 4H, and the phase difference R _th was 1.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF12]
A hard coat film was produced by the method described below.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-510H (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

  The hard coat film HCF12 obtained as described above did not generate interference fringes and had good adhesion to the base material of the hard coat layer.

Further, the scratch hardness was 5H, and the phase difference R _th was 1.0 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

[Hard coat film HCF13]
A hard coat film was produced by the method described below.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) 14.54 mass parts Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 21.82 mass parts Irgacure (registered trademark) 184 (manufactured by BASF Corporation) 1.82 mass parts Iruga Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

The hard coat film HCF13 obtained as described above did not produce interference fringes and had good adhesion to the base material of the hard coat layer. The phase difference R _th was 0.5, which was a low value, but the scratch hardness was 2H, which was low.

[Hard coat film HCF14]
A hard coat film was produced by the method described below.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) 7.27 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 29.09 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

The hard coat film HCF14 obtained as described above did not generate interference fringes and had good adhesion to the base material layer of the hard coat layer. Although the phase difference R _th was as low as 0.5, the pencil hardness was 2H, which was low.

[Hard coat film HCF15]
A hard coat film was produced by the method described below.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Urethane acrylate AT-600 (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

The hard coat film HCF15 obtained as described above did not produce interference fringes and had good adhesion to the base material layer of the hard coat layer. Further, the phase difference R _th was as low as 0.5, but the scratch hardness was H and the hardness was low.

[Hard coat film HCF16]
A hard coat film was produced by the method described below. In addition, each process in manufacture of a hard coat film was performed in air | atmosphere.

  First, a substrate was formed by the same method as described for the hard coat film HCF1.

Next, a coating solution having the following composition was prepared.
Light acrylate DPE-6A (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

The hard coat film HCF16 obtained as described above did not produce interference fringes and had good adhesion to the base material layer of the hard coat layer. Moreover, although the phase difference _Rth was as low as 0.5 and good, the scratch hardness was H and the hardness was low.

  Table 2 summarizes the evaluation results and the like of the hard coat films HCF1 and HCF10 to HCF16.

[Hard coat film HCF17]
A hard coat film was produced by the method described below. This hard coat film is produced in a nitrogen atmosphere over the period from the start of application of the coating liquid for forming the substrate to the completion of light irradiation until the hard coat layer is formed. It was.

First, a coating solution having the following composition was prepared.
Urethane U1 57.14 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF Corp.) 2.86 parts by mass Methyl ethyl ketone 40.00 parts by mass This coating solution was used as a PET film Lumirror T60 (thickness 75 μm; manufactured by Toray Industries, Inc.) Further, it was applied by a bar coating method so that the cured film thickness was 40 μm. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. Thereby, the coating film was photocured. Then, the coating film was peeled from the PET film to obtain a substrate.
This base material had a tensile strength of 80 N / mm ² and a tensile elongation of 10%. That is, this base material had good tensile properties.

Next, a coating solution having the following composition was prepared.
Urethane acrylate UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Light acrylate PE-3A (manufactured by Kyoeisha Chemical Co., Ltd.) 18.18 parts by mass Irgacure (registered trademark) 184 (manufactured by BASF) 1.82 parts by mass Cure (registered trademark) TPO (manufactured by BASF) 1.82 parts by mass Methyl isobutyl ketone 60.00 parts by mass This coating solution is applied onto the substrate so that the cured film thickness becomes 5 μm by the bar coating method. did. After drying the coating film, it was irradiated with 300 mJ / cm ² of ultraviolet light by a high-pressure mercury lamp in a nitrogen atmosphere. This obtained the hard-coat layer formed by photocuring a coating film.

  The hard coat film HCF17 obtained as described above did not generate interference fringes, but the adhesion of the hard coat layer to the substrate was low as compared with the hard coat film HCF1.

Further, the scratch hardness was 4H, and the phase difference R _th was 0.5 nm. That is, a hard coat film having high hardness and low retardation could be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Display, 10 ... Polarizing plate, 20 ... Display panel, 30 ... Backlight unit, 110 ... Hard coat film, 111 ... Base material, 112 ... Hard coat layer, 120 ... Protective film, 130 ... Polarizing layer, 210 ... Substrate 220 ... substrate, 230 ... liquid crystal layer.

Claims (7)

It is obtained by photocuring a first photopolymerizable composition containing a first polymerizable compound and a first photopolymerization initiator, and 40% by mass or more of the first polymerizable compound is a urethane skeleton and 2 or 3 A base material that is a compound containing two (meth) acryloyl groups;
It is obtained by photocuring a second photopolymerizable composition containing a second polymerizable compound and a second photopolymerization initiator on the substrate, and 50% by mass or more of the second polymerizable compound is: A hard coat film comprising a hard coat layer which is a compound containing a urethane skeleton and six or more (meth) acryloyl groups.   The hard coat film according to claim 1, wherein the substrate has a thickness of 20 to 100 μm.   The hard coat film according to claim 1, wherein the hard coat layer has a thickness of 2 to 15 μm.   A polarizing plate comprising the hard coat film according to claim 1.   A display comprising the hard coat film according to any one of claims 1 to 3. A step of coating a first photopolymerizable composition containing a first polymerizable compound and a first photopolymerization initiator on a support to form a first coating film, wherein the first polymerizable compound 40% by mass or more is a process including a urethane skeleton and two or three (meth) acryloyl groups;
Photocuring the first coating film to obtain a substrate supported by the support;
Applying a second photopolymerizable composition containing a second polymerizable compound and a second photopolymerization initiator on the substrate to form a second coating film, wherein the second polymerizable compound 50% by mass or more of is a compound containing a urethane skeleton and six or more (meth) acryloyl groups;
Photocuring the second coating film to obtain a hard coat layer supported by the substrate;
A method for producing a hard coat film, comprising a step of peeling the substrate from the support before forming the second coating film or after photocuring the second coating film.   The method for producing a hard coat film according to claim 6, wherein photocuring of the first coating film is performed in an oxygen-containing atmosphere, and photocuring of the second coating film is performed in an inert atmosphere.