JP2019101298A - Optical member, display device and method for selecting optical member - Google Patents

Abstract

To provide an optical member having excellent adhesiveness between a light-transmitting substrate and a resin layer and excellent physical properties of the resin layer.SOLUTION: The optical member has a resin layer on a light-transmitting substrate, in which the resin layer comprises a cured product of an ionization radiation curable resin composition as a resin component and a resin intruding from the light-transmitting substrate, and the light-transmitting substrate comprises a swollen region on an interface with the resin layer. The optical member satisfies the following condition 1. Condition 1: A transmission electron image of a cross section of the optical member is captured at a resolution of 100 pixels or more per 5 μm length in a width direction and an analysis area is selected. The analysis area is a region within a square having a length equal to the thickness of the resin layer and a width equal to 20 pixels. An image of the analysis area is gray-scaled into 256 gradations. The analysis area is then divided in the thickness direction by one pixel, and an average gradation in each division area is calculated. The division areas are numbered as 1, 2, 3 to n successively from the light-transmitting substrate side. The assigned numbers are plotted on an X axis and the average gradations in the respective division areas are plotted on a Y-axis. A relational expression between the assigned numbers and the average gradations is calculated by a least square method. The gradient of the relational expression is 0.15 or more.SELECTED DRAWING: None

Description

  The present invention relates to an optical member, a display device, and a method of sorting optical members.

  In a display device such as a liquid crystal display device or an organic EL display device, an optical member is disposed on the surface or inside for the purpose of improving the optical characteristics and the like. These optical members employ a configuration in which a resin layer (hard coat layer) having high hardness is provided on a light transmitting substrate in order to make the optical members resistant to damage during manufacturing and processing.

  However, the optical member in which the hard coat layer is provided on the light transmitting base material may be poor in the adhesion between the light transmitting base material and the hard coat layer. In order to improve the adhesion between the light transmitting substrate and the hard coat layer, for example, the means of Patent Document 1 has been proposed.

  In addition, in the optical member in which the hard coat layer is provided on the light transmitting base material, interference fringes may be generated due to the difference in refractive index between the light transmitting base material and the hard coat layer, and the appearance may be poor. In order to improve the interference fringes of the optical member, for example, the means of Patent Document 2 is proposed.

JP, 2013-174852, A JP 2003-205563 A

  In Patent Document 1, the adhesion between the light transmitting substrate and the hard coat layer is improved by interposing a primer layer between the light transmitting substrate and the hard coat layer. However, the method of Patent Document 1 has a problem that the number of manufacturing steps of the optical member is increased and the productivity is inferior. Further, the means of Patent Document 1 has a problem that interference fringes are easily generated because the interface of the optical member is increased.

Patent Document 2 proposes that a composition containing a solvent for dissolving or swelling a light transmitting substrate is applied to the substrate and dried to form a hard coat layer, thereby suppressing interference fringes. . By means of Patent Document 2, improvement in adhesion between the light transmitting substrate and the hard coat layer can also be expected. However, with the means of Patent Document 2, the suppression of interference fringes may be insufficient.
In addition, when the resin component or the like of the light transmitting base material migrates to the hard coat layer side, there is a possibility that the migration component lowers the physical properties of the hard coat layer. Not.

  The present invention has been made under such circumstances, and is excellent in the adhesion between the light transmitting substrate and the resin layer, as well as the selection of optical members, display devices and optical members excellent in various physical properties of the resin layer. The task is to provide a method.

That is, the present invention provides the following optical members, display devices, and optical member sorting methods of the following [1] to [3].
[1] An optical member having a resin layer on a light transmitting substrate, wherein the resin layer flows as a resin component from a cured product of an ionizing radiation curable resin composition and the light transmitting substrate An optical member containing a resin, wherein the light transmitting substrate has a swelling region at the interface with the resin layer, and satisfies the following condition 1.
<Condition 1>
The transmission electron image of the cross section of the optical member is imaged with a resolution of 100 pixels or more in the number of pixels per 5 μm in the width direction to select an analysis region. The analysis area is an area in a quadrangle in which the length is the thickness of the resin layer and the width is 20 pixels.
The image in the analysis area is grayscaled to 256 tones. The analysis area is divided for each pixel in the thickness direction of the resin layer, and the average gradation of each divided area is calculated. Each divided area is numbered 1, 2, 3 ... n sequentially from the light transmitting base material side, numbered number is numbered with X axis and average gray level of each divided area as Y axis When the relational expression between and the average gradation is calculated by the least square method, the inclination of the relational expression is 0.15 or more.
[2] A display device in which one or more optical members are disposed on the light emitting surface side of a display element, wherein at least one of the optical members is the optical member of the above-mentioned [1].
[3] A method of selecting an optical member having a resin layer containing a cured product of an ionizing radiation curable resin composition on a light transmitting substrate, wherein the resin layer is an ionizing radiation curable resin as a resin component. Containing the cured product of the composition and the resin flowing from the light transmitting substrate, the light transmitting substrate having a swelling region at the interface with the resin layer, and satisfying the above condition 1 Method of sorting optical members.

The optical member and the display device of the present invention are excellent in the adhesion between the light transmitting substrate and the resin layer, and are excellent in various physical properties of the resin layer.
In addition, the method for sorting optical members according to the present invention is excellent in the adhesion between the light transmitting substrate and the resin layer, and the image analysis of the optical members excellent in various physical properties of the resin layer without conducting many inspections. It is possible to sort only objectively and accurately, and to efficiently deliver superior quality optical members.

FIG. 6 is a view showing a change in average gradation of the resin layer of the optical member of Example 1. It is a figure which shows the change of the average gradation of the resin layer of the optical member of the comparative example 1. FIG.

[Optical member]
The optical member of the present invention is an optical member having a resin layer on a light transmitting substrate, and the resin layer is a resin component which is a cured product of an ionizing radiation curable resin composition and the light transmitting group. The light transmitting base material includes a resin flowing from a material, and the light transmitting base material has a swelling region at the interface with the resin layer, and satisfies the following condition 1.

<Condition 1>
The transmission electron image of the cross section of the optical member is imaged with a resolution of 100 pixels or more in the number of pixels per 5 μm in the width direction to select an analysis region. The analysis area is an area in a quadrangle in which the length is the thickness of the resin layer and the width is 20 pixels.
The image in the analysis area is grayscaled to 256 tones. The analysis area is divided for each pixel in the thickness direction of the resin layer, and the average gradation of each divided area is calculated. Each divided area is numbered 1, 2, 3 ... n sequentially from the light transmitting base material side, numbered number is numbered with X axis and average gray level of each divided area as Y axis When the relational expression between and the average gradation is calculated by the least square method, the inclination of the relational expression is 0.15 or more.

<< Condition 1 >>
The technical significance of condition 1 will be described below.
First, satisfying the condition 1 indicates that the lightness of the analysis area tends to increase as it goes from the light transmitting substrate side to the surface side of the resin layer.
Since the material constituting the optical member transmits most of the electrons, when capturing a transmission electron image of a cross section of the optical member, the cross section of the optical member is dyed with a dye in advance. Under the present circumstances, the location where crosslinking density is high tends to be difficult to be dyed, and the location where crosslinking density is low tends to be easily dyed. In addition, since the amount of electrons transmitted through the stained portion decreases, the lightness of the captured image decreases.
Therefore, satisfying condition 1 means that the crosslink density of the resin layer increases as it goes from the light transmitting substrate side to the surface side of the resin layer, and a state in which the resin layer is difficult to be dyed is formed. I mean. And, as the crosslink density of the resin layer increases from the light transmitting base side of the resin layer toward the surface side, it means that the resin of the light transmitting base flows into the resin layer. This means that the decrease in the original scratch resistance of the resin layer is suppressed.
As described above, when the condition 1 is satisfied, the decrease in the abrasion resistance of the resin layer can be suppressed.
On the other hand, not satisfying the condition 1 means that the crosslink density of the resin layer decreases as going from the light transmitting substrate side of the resin layer to the surface side, or the light transmitting substrate side and the surface side of the resin layer Means that the crosslink density of Therefore, when the condition 1 is not satisfied, the scratch resistance of the resin layer is reduced.

Under the condition 1, the inclination of the relational expression is preferably 0.17 or more, more preferably 0.20 or more, and still more preferably 0.22 or more.
If the inclination of the above-mentioned relational expression is too large, the composition (≒ physical properties) changes rapidly in the thickness direction of the resin layer, which may cause an unexpected influence over time based on the physical property difference. Therefore, the slope of the above formula is preferably 1.00 or less, more preferably 0.60 or less, and still more preferably 0.40 or less.
Condition 1 is an average value of 20 samples.

The standard deviation of the slope of the 20 samples is preferably 0.30 or less. Moreover, it is preferable that the absolute value of the skewness of the said inclination of 20 samples is 2.0 or less.
The slope may not have a normal distribution, but at least the range of the standard deviation and skewness described herein does not inhibit the effect of the present invention. The reason why the gradient may not be a normal distribution may be considered as follows.
When the resin layer coating liquid is applied to a light transmitting substrate and dried, the drying air may not be completely laminar flow, so the drying conditions differ depending on the in-plane position. When the resin layer coating solution contains non-dissolvable components such as particles, the ratio of the non-dissolvable components varies depending on the position of the resin layer, and therefore the in-plane drying conditions further differ. Furthermore, the drying rate of the coating varies non-linearly, not linearly, due to these factors. It is considered that due to such a cause, the slope may not be normally distributed.

<< Preparation of sample for measurement >>
When imaging with a transmission electron image of the cross section of the optical member under condition 1, it is preferable to use a measurement sample processed and dyed in the following manner (1) to (3).
(1) In order to make it possible to cut the optical member into a thin film, a laminated member in which the auxiliary member is bonded to the optical member is obtained. For example, a transparent plate is bonded to both surfaces of the optical member via an adhesive to obtain a laminated member. As the adhesive, for example, a momentary adhesive (trade name Aron Alpha EXTRA Stick manufactured by Toa Gosei Co., Ltd.) can be used, and as the transparent plate, for example, a vinyl chloride resin plate (product number "manufactured by Crown Group Inc." Vinyl chloride B5 transparent underlayment CR-ST 51 ") can be used.
(2) The laminated member obtained in (1) is cut with a diamond knife in the direction parallel to the thickness direction. The width of the cut laminated member (the length in the direction orthogonal to the thickness direction of the laminated member) is preferably 20 to 130 nm, more preferably 25 to 100 nm, and still more preferably 30 to 80 nm.
(3) In a glass container having a capacity of 20 cc, the crystal of osmium tetraoxide and the cut laminated member obtained in (2) are charged, and the periphery of the lid of the container is sealed with a sealing film. The laminated member after cutting is left to stand for 0.5 to 2 hours to obtain a sample for measurement. The amount of the crystal of osmium tetroxide, 0.3 mm ³ is a standard amount, it may be 0.1 to 1.0 mm ^3. As the sealing film, for example, a trade name "Parafilm PM996" manufactured by LSS can be used.

<< Imaging of transmission electron image >>
Under the condition 1, it is preferable to capture a transmission electron image (STEM photograph) under the following conditions using the measurement sample prepared as described above. Under the following imaging conditions, "the resolution for displaying the number of pixels around 5 μm in the width direction with 100 pixels or more" means that the resolution for displaying the number of pixels around 5 μm in the length direction with 100 pixels or more It also means that
<Imaging condition>
-Mode: STEM transmission-Acceleration voltage: 30kV
・ Photographing magnification: 10,000 times ・ Resolution: Resolution to display the number of pixels per 5 μm in width direction with 100 pixels or more

Under the condition 1, a predetermined analysis area is analyzed under a predetermined condition for the transmission electron image captured as described above. If the resolution of the imaging condition is high resolution such as the above condition (resolution that displays the number of pixels per 5 μm in the width direction at 100 pixels or more), the analysis area can be divided finely, so Regardless of the relationship, the slope of the relational expression calculated from condition 1 can be made constant.
The analysis area is an area in a quadrangle in which the length is the thickness of the resin layer and the width is 1⁄5 of the thickness of the resin layer. When the resin layer contains particles, the portion not containing particles is determined as an analysis region.
In addition, FIG. 1 is a figure which shows the change of the average gradation of the resin layer of the optical member of Example 1, and FIG. 2 is a figure which shows the change of the average gradation of the resin layer of the optical member of Comparative Example 1. In FIG. 1 and FIG. 2, the horizontal axis represents the numbering of the divided areas in order from the light transmitting substrate side, and the vertical axis represents the average gradation of each divided area.

<Light transmitting base material>
Examples of the light transmitting substrate include polyesters such as polyethylene terephthalate and polyethylene naphthalate; acrylics; celluloses such as triacetyl cellulose (TAC), cellulose diacetate, and cellulose acetate butyrate; polyamides; polyimides; polyether sulfones; polysulfones; Polypropylene: Polymethylpentene; Polyvinyl chloride; Polyvinyl acetal; Polyether ketone; Polycarbonate; Polyurethane; Polyurethane; Plastic film made of resin such as amorphous olefin (Cyclo-Olefin-Polymer: COP).

The thickness of the light transmitting substrate is preferably 5 to 300 μm, and more preferably 30 to 200 μm.
On the surface of the light transmitting substrate, in addition to physical treatments such as corona discharge treatment and oxidation treatment, application of a paint called an anchor agent or a primer may be performed in advance to improve adhesion.

The light transmitting substrate has a swelling region at the interface with the resin layer described later.
The swollen region is formed by impregnating a component of the resin layer forming coating liquid when forming the resin layer on the light transmitting substrate. Then, by forming the swollen region, the light transmitting substrate and the resin layer are strongly connected, and the adhesion between the light transmitting substrate and the resin layer can be easily improved. In addition, when there is a difference in the refractive index between the light transmitting base and the resin layer, a swelling region is formed in the light transmitting base to suppress the generation of interference fringes based on the difference in the refractive index. it can.
Furthermore, the formation of the swollen region means that the component of the light transmitting substrate is easily eluted to the resin layer side. Therefore, by using a light transmitting substrate having a swelling region formed therein, and by adjusting the composition of the resin layer forming coating solution, the drying temperature of the coating solution, and the drying time as described later. , Condition 1 can easily be satisfied.

The glass transition temperature of the resin forming the light transmitting substrate is 100 from the viewpoint of suppressing a large amount of the resin forming the light transmitting substrate from flowing into the resin layer in the process of drying the resin layer coating liquid. C. or higher is preferable, 105.degree. C. or higher is more preferable, and 110.degree. C. or higher is more preferable.
The light transmitting substrate having a predetermined glass transition temperature can be produced, for example, by melt-extruding a raw material of a thermoplastic resin having a predetermined glass transition temperature to form a film, and subjecting the film to a stretching process. More specifically, a light transmitting substrate having a predetermined glass transition temperature can be produced by the method described in JP-A-2017-177499.

The swelling region can be formed by selecting a monomer and a solvent of the resin layer forming coating solution according to the type of the light transmitting substrate to be used.
As a light transmissive base material which tends to form a swelling area | region, a cellulose base material and an acryl base material are mentioned. In particular, the acrylic base material is more suitable in that the amount of the light transmitting base material eluted to the resin layer side can be easily adjusted and the condition 1 can be easily satisfied. In addition, the acrylic substrate is also preferable in that it is excellent in light transmittance and optical isotropy.
In the present specification, "acrylic" means acrylic and / or methacrylic.

The acrylic binder constituting the acrylic base material, which is an example of the light transmitting base material, is preferably obtained by polymerizing one or two or more kinds of (meth) acrylic acid alkyl ester in combination, and more specifically, Preference is given to those obtained using methyl) methyl acrylate.
Moreover, as an acrylic binder, it is described, for example, in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, JP-A-2005-146084 and the like. The ones of Furthermore, as the acrylic binder, an acrylic binder having a ring structure such as an acrylic having a lactone ring structure or an acrylic having an imido ring structure may be used.

  The acrylic substrate may contain a binder component other than the acrylic binder, but the proportion of the acrylic binder in the total binder is preferably 80% by mass or more, and more preferably 90% by mass or more.

  In addition, the acrylic substrate may contain organic fine particles. When the acrylic substrate contains organic particles, the interface is likely to be uneven when the components of the acrylic substrate are eluted, and adhesion with the resin layer can be made better.

As the organic fine particles, rubber elastic particles including a layer exhibiting rubber elasticity are preferably used. The rubber elastic body particles may be particles consisting only of a layer exhibiting rubber elasticity, or particles of a multilayer structure having other layers together with a layer exhibiting rubber elasticity. When the organic fine particles are rubber elastic particles, the bendability of the acrylic substrate is improved, and the generation of a crack due to a solvent or the like can be easily suppressed.
Moreover, as said organic fine particle, the thing of the core-shell structure which consists of a nucleus and a shell is used preferably.

  The material of the organic fine particles is preferably transparent, and examples thereof include olefin-based elastic polymers, diene-based elastic polymers, styrene-diene-based elastic copolymers, and acrylic-based elastic polymers. Among them, acrylic elastic polymers which can suppress internal haze to improve transparency are preferable.

  The organic fine particles preferably have an average particle diameter of 10 to 400 nm, more preferably 50 to 300 nm. By setting the average particle diameter to 10 nm or more, the propagation of micro cracks generated in the acrylic substrate can be easily suppressed, and by setting the average particle diameter to 400 nm or less, an increase in haze can be suppressed.

  The content of the organic fine particles in the acrylic substrate is preferably a ratio of 25 to 45% by mass of the total solid content of the acrylic substrate. By containing the organic fine particles in this proportion, it is possible to easily suppress the propagation of micro cracks generated in the acrylic substrate, and it is possible to suppress the rise of the internal haze.

<Resin layer>
The resin layer is formed by applying, drying, and curing a resin layer forming coating solution containing an ionizing radiation curable resin composition, a solvent, and the like by a known coating method such as gravure coating or bar coating. It can be formed.

<< ionizing radiation curable resin composition >>
The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as "ionizing radiation curable compound"). Examples of the ionizing radiation curable functional group include ethylenic unsaturated bond groups such as (meth) acryloyl group, vinyl group and allyl group, and epoxy group and oxetanyl group.
Note that ionizing radiation means any of electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules, and usually, ultraviolet light (UV) or electron beam (EB) is used, and others, It is also possible to use charged particle beams such as electromagnetic waves such as X-rays and γ-rays, α-rays and ion beams.

As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferable, and a compound having a (meth) acryloyl group is more preferable. The ionizing radiation curable compound is preferably a polyfunctional ionizing radiation curable compound having two or more ionizing radiation curable functional groups. Among these ionizing radiation curable compounds, polyfunctional (meth) acrylate compounds having two or more (meth) acryloyl groups are preferable.
As the ionizing radiation curable compound, any of monomers and oligomers can be used.

The ionizing radiation curable compound preferably includes a monomer having three or more ionizing radiation curable functional groups, and more preferably includes a (meth) acrylate-based monomer having three or more (meth) acryloyl groups.
The monomer having three or more ionizing radiation curable functional groups swells the light transmitting substrate appropriately, and elutes the resin of the light transmitting substrate into the resin layer, and increases the crosslink density of the resin layer Can. For this reason, when the ionizing radiation curable compound contains a monomer having three or more ionizing radiation curable functional groups, the adhesion between the light transmitting substrate and the resin layer can be easily improved, and the interference unevenness of the optical member can be obtained. This can be easily suppressed, the abrasion resistance of the resin layer can be easily improved, and condition 1 can be easily satisfied.
The monomer having three or more ionizing radiation curable functional groups preferably has a functional group number of 3 to 5, and more preferably 3 to 4 from the viewpoint of the balance of the effects described above.

In addition, it is preferable to use an ionizing radiation curable oligomer in combination with a monomer having three or more ionizing radiation curable functional groups as the ionizing radiation curable compound. By using the ionizing radiation curable oligomer, it is possible to suppress excessive elution of the resin of the light transmitting substrate, and it becomes easy to adjust the compatibility of the resin eluted from the light transmitting substrate in the resin layer. , Condition 1 can be easily satisfied. From the viewpoint of enhancing the scratch resistance of the resin layer, the above-mentioned oligomer preferably has three or more ionizing radiation curable functional groups.
The mass ratio of the monomer having three or more ionizing radiation curable functional groups to the ionizing radiation curable oligomer is preferably 3: 7 to 7: 3, and more preferably 4: 6 to 6: 4. .
The total amount of the ionizing radiation curable oligomer and the monomer having three or more ionizing radiation curable functional groups is preferably 75% by mass or more of the total amount of the ionizing radiation curable compound, and is 90% by mass or more. Is more preferably 99% by mass or more, and still more preferably 100% by mass.

  In addition, a monomer having two or less ionizing radiation curable functional groups tends to cause excessive elution of the resin component in the light transmitting substrate, and condition 1 is caused by the resin component eluted in a large amount in the resin layer. It may be difficult to satisfy the condition, or the scratch resistance of the resin layer may be reduced. For this reason, it is preferable that it is 25 mass% or less of the whole quantity of an ionizing radiation curable compound, and, as for the monomer whose number of ionizing radiation curable functional groups is two or less, it is more preferable that it is 10 mass% or less. It is more preferably at most%, still more preferably at most 0% by mass.

  As a trifunctional or higher functional (meth) acrylate-based monomer which is a typical example of a monomer having three or more ionizing radiation curable functional groups, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetramer Examples include (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol tetra (meth) acrylate, isocyanuric acid-modified tri (meth) acrylate and the like. The (meth) acrylate-based monomer described above may have a part of the molecular skeleton modified, and may be modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol or the like. Things can also be used.

Moreover, as a (meth) acrylate type oligomer which has three or more ionizing radiation curable functional groups, acrylate type such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate and the like Polymer etc. are mentioned.
Urethane (meth) acrylates are obtained, for example, by the reaction of polyhydric alcohols and organic diisocyanates with hydroxy (meth) acrylates.

When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains an additive such as a photopolymerization initiator or a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones and the like.
The photopolymerization accelerator can reduce the polymerization inhibition by air at the time of curing and can accelerate the curing rate, and is selected from, for example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. One or more may be mentioned.

<< Particles >>
The resin layer may contain particles.
The particles are used, for example, to impart antiglare properties. As the particles, either organic particles or inorganic particles can be used. Further, the shape of the particles may be spherical, disk-like, rugby ball-like, indeterminate or the like. The particles may be in any form of hollow particles, porous particles and solid particles.

As organic particles, particles composed of polymethyl methacrylate, polyacryl-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluorine resin, polyester resin, etc. It can be mentioned.
Examples of the inorganic particles include particles made of silica, alumina, zirconia, titania and the like.
Among the above-mentioned particles, organic particles are preferable from the viewpoint of easiness of dispersion control, and among them, polyacryl-styrene copolymer particles are preferable. The polyacryl-styrene copolymer particles are good in that control of the internal haze and aggregation / dispersion is easy because control of the degree of refractive index and hydrophilicity is easy.

The average particle diameter of the particles is preferably 1 to 8 μm, and more preferably 1.5 to 5 μm.
In addition, the average particle diameter of particle | grains is computable, for example by the operation | work of the following (1)-(3).
(1) A transmission observation image is taken with an optical microscope of the optical member of the present invention. The magnification is preferably 500 to 2,000 times.
(2) Arbitrary 10 particles are extracted from the observation image, the long diameter and the short diameter of each particle are measured, and the particle diameter of each particle is calculated from the average of the long diameter and the short diameter. The major diameter is the longest diameter on the screen of the individual particles. Further, the minor axis is a line segment perpendicular to the middle point of the line segment that constitutes the major axis, and refers to the distance between two points where the orthogonal segment intersects the particle.
(3) The same operation is performed five times on the observation image of another screen of the same sample, and the value obtained from the number average of the particle sizes of 50 particles in total is taken as the average particle size of the large particles.

  The content of the particles is preferably 0.2 to 15.0% by mass, and more preferably 0.5 to 10.0% by mass, of the total solid content forming the resin layer, and 1.0 It is further more preferable that it is -6.0 mass%.

<< Particles >>
Fine particles may be contained in the resin layer.
The fine particles have a role of, for example, adjusting the viscosity of the resin layer coating solution or suppressing the above-described particles from settling in the resin layer.
The fine particles preferably have an average primary particle size of 200 nm or less. The fine particles are preferably inorganic fine particles, and more preferably silica fine particles.

<< Additives >>
In the resin layer, additives such as an ultraviolet light absorber, an antistatic agent, an antifouling agent, an antifogging agent, and a leveling agent may be contained as long as the effects of the present invention are not impaired.

<< solvent >>
In the resin layer forming coating solution, usually, a solvent is used to adjust the viscosity or to make each component soluble or dispersible. In addition, in order to easily satisfy the condition (1), it is preferable to select the solvent in consideration of the permeability of the solvent to the light transmitting substrate.
Specifically, the solvent is, for example, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone etc.), ethers (dioxane, tetrahydrofuran etc.), aliphatic hydrocarbons (hexane etc.), alicyclic hydrocarbons (Cyclohexane etc.), aromatic hydrocarbons (toluene, xylene etc.), halogenated carbons (dichloromethane, dichloroethane etc.), esters (methyl acetate, ethyl acetate, butyl acetate etc.), alcohols (butanol, cyclohexanol etc.) And cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), etc., and mixtures thereof may be used.

If the drying of the solvent is too slow, the resin component eluted from the light transmitting substrate into the resin layer may excessively advance to the vicinity of the surface of the resin layer, leading to a decrease in the scratch resistance of the resin layer. Therefore, the relative evaporation rate of the solvent (the relative evaporation rate when the evaporation rate of n-butyl acetate is 100) is preferably 180 or more, more preferably 200 or more.
On the other hand, when the relative evaporation rate of the solvent is too fast, the resin component eluted in the resin layer from the light transmitting substrate stays on the light transmitting substrate side of the resin layer, and the composition in the thickness direction of the resin layer (≒ physical properties) Changes rapidly, and may cause unexpected effects over time based on the physical property difference. Therefore, the relative evaporation rate of the solvent is preferably 300 or less, more preferably 250 or less.
In the case of a mixed solvent, the relative evaporation rate of the mixed solvent can be calculated by summing the values obtained by multiplying the relative evaporation rates of the respective solvents by the mass proportions of the respective solvents. For example, the relative evaporation rate of the solvent in which the solvent having the relative evaporation rate 170 and the solvent having the relative evaporation rate 200 are mixed at 1: 1 is 185.
As an example of relative evaporation rates, methyl ethyl ketone (MEK) is 370, toluene is 200, methyl isobutyl ketone (MIBK) is 160, isopropyl alcohol (IPA) is 150, and cyclohexanone is 32.

When the light transmitting substrate is an acrylic substrate, it is preferable to select a solvent which appropriately swells or dissolves the acrylic substrate, since the acrylic substrate tends to be swollen or dissolved by the solvent.
As such solvents, alcohols are preferable, and in each of the other solvent types, solvents having a larger carbon number tend to be favorable, and among these, solvents having a high evaporation rate tend to be favorable. For example, isopropyl alcohol for alcohols, methyl ethyl ketone for ketones, toluene for aromatic hydrocarbons, and mixed solvents of these may be used.

  The content ratio of the solvent in the resin layer forming coating solution is not particularly limited, but 50 to 200 parts by mass is preferable and 70 to 120 parts by mass with respect to 100 parts by mass of the solid content of the resin layer forming coating solution More preferable.

Further, from the viewpoint of controlling the drying time of the solvent to easily satisfy the condition 1, it is preferable to control the drying conditions when forming the resin layer. The drying conditions can be controlled by the drying temperature, the drying time and the wind speed in the dryer.
The drying temperature is preferably 60 to 120 ° C, more preferably 100 to 120 ° C. The drying time is preferably 40 to 100 seconds, more preferably 50 to 70 seconds. The drying speed is preferably 5 to 50 m / s, more preferably 12 to 20 m / s.

The thickness of the resin layer is preferably 2 to 10 μm, more preferably 3 to 8 μm, from the viewpoint of the balance between curl suppression, mechanical strength, abrasion resistance and toughness, and 3.5 to 5. More preferably, it is 0 μm. If the thickness of the resin layer is too thick, it is not preferable because the drying of the solvent is delayed.
The thickness of the resin layer can be calculated, for example, by measuring the thickness of 20 points from the image of the cross section taken using a scanning transmission electron microscope (STEM), and calculating the average value of the values of 20 points.

  The optical member may be an antireflective layer, an antifouling layer, or an electrification layer on the side of the light transmitting substrate having the resin layer and / or the side of the light transmitting substrate having the resin layer on the opposite side. You may have functional layers, such as a prevention layer.

<Size, shape etc>
The optical member may be sheet-like or roll-like.
Further, the size of each sheet is not particularly limited, but in general, the size is about 2 to 500 inches diagonally. The width and length of the roll are not particularly limited, but in general, the width is about 500 to 3000 mm and the length is about 500 to 5000 m.
Further, the shape of each leaf is not particularly limited, and may be, for example, a polygon (triangle, quadrangle, pentagon, etc.) or a circle, or a random irregular shape.

<Optical properties>
The optical member preferably has a total light transmittance (JIS K7361-1: 1997) and a haze (JIS K 7136: 2000) in the following ranges.
The total light transmittance is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more.
The haze is preferably 0.5 to 20.0%, more preferably 1.0 to 15.0%, and still more preferably 1.5 to 10.0%.

[Display device]
The display device of the present invention is a display device in which one or more optical members are disposed on the light emitting surface side of the display element, and at least one of the optical members is the optical member of the present invention described above.
The display device of the present invention is preferably disposed on the outermost surface of the display device so that the resin layer of the optical member of the present invention described above faces the opposite side to the display element.

As a display element which comprises a display apparatus, a liquid crystal display element, a plasma display element, an organic electroluminescent display element etc. are mentioned.
The specific configuration of the display element is not particularly limited. For example, in the case of a liquid crystal display element, it has a basic configuration having a lower glass substrate, a lower transparent electrode, a liquid crystal layer, an upper transparent electrode, a color filter and an upper glass substrate in order. The upper transparent electrode is patterned at high density.

The display device of the present invention may have a touch panel on the display element, and the optical member of the present invention may be disposed as a component of the touch panel.
Examples of the touch panel include a capacitive touch panel, a resistive touch panel, an optical touch panel, an ultrasonic touch panel, and an electromagnetic induction touch panel.

[Method of sorting optical members]
The method for selecting an optical member according to the present invention is a method for selecting an optical member having a resin layer containing a cured product of an ionizing radiation curable resin composition on a light transmitting substrate, wherein the resin layer comprises a resin component And a cured product of the ionizing radiation curable resin composition and the resin flowing from the light transmitting substrate, wherein the light transmitting substrate has a swelling region at the interface with the resin layer, And what sorts the following conditions 1 is sorted out.
<Condition 1>
The transmission electron image of the cross section of the optical member is imaged with a resolution of 100 pixels or more in the number of pixels per 5 μm in the width direction to select an analysis region. The analysis area is an area in a quadrangle in which the length is the thickness of the resin layer and the width is 20 pixels.
The image in the analysis area is grayscaled to 256 tones. The analysis area is divided for each pixel in the thickness direction of the resin layer, and the average gradation of each divided area is calculated. Each divided area is numbered 1, 2, 3 ... n sequentially from the light transmitting base material side, numbered number is numbered with X axis and average gray level of each divided area as Y axis When the relational expression between and the average gradation is calculated by the least square method, the inclination of the relational expression is 0.15 or more.

The determination condition for selecting the optical member of the present invention is that the above condition 1 is satisfied.
In the method for sorting optical members according to the present invention, it is possible to select optical members excellent in the various physical properties of the resin layer as well as having excellent adhesion between the light transmitting substrate and the resin layer without carrying out various inspections. And quality control of optical members can be performed efficiently.
The determination condition 1 preferably satisfies the preferable numerical range of the condition 1 described for the optical member of the present invention.

  EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the invention thereto. In addition, "part" is a mass reference | standard unless there is particular notice.

1. Physical Property Measurement and Evaluation of Optical Member The physical property measurement and evaluation of the optical members of Examples and Comparative Examples were performed as follows. The results are shown in Table 1 grade.

1-1. Calculation of Slope of Relational Expression of Determination Condition 1 of Swelled Region A transmission electron image (STEM photograph) of the measurement sample was taken under the following conditions using the measurement sample prepared as described below. The scanning transmission electron microscope (STEM) uses a product name “S-4800 (TYPE 2)” manufactured by Hitachi High-Technologies Corp. The photographed photograph is visually observed, and a swelling region is formed as “A”. The thing in which the swelling area | region was not formed was made into "C."
<Imaging condition>
-Mode: STEM transmission-Acceleration voltage: 30kV
・ Photographing magnification: 10,000 times ・ Resolution: Resolution that displays the number of pixels per 5 μm in the width direction with 500 pixels

Next, with respect to the captured image, an image of an area in a rectangle having a length of 20 nm and a thickness of a resin layer was gray-scaled to 256 tones.
Next, the analysis area was divided into each pixel in the thickness direction of the resin layer, and the average gradation of each divided area was calculated.
Next, each divided area is numbered 1, 2, 3 ... n sequentially from the light transmitting base material side, and the numbered number is numbered with the X-axis and the average gradation of each divided area as the Y-axis. The relationship between the number and the average tone was calculated by the least squares method, and the slope of the relationship was obtained. The slopes of 20 samples were calculated, and the average value of 20 samples was taken as the slope of the example and the comparative example.

<Preparation of sample for measurement>
The measurement sample which processed and dyed the optical member of the Example and the comparative example in the way of following (1)-(3) was produced.
(1) A vinyl chloride resin board (product made by Crown Group, Inc., product number "Vinyl chloride B5 transparent underlayment" through an adhesive (trade name Aron Alpha EXTRA Stick manufactured by Toa Gosei Co., Ltd.) on both sides of the optical members of Examples and Comparative Examples CR-ST 51 ") was laminated to obtain a laminated member.
(2) The laminated member obtained in (1) is parallel to the thickness direction of the laminated member so that the width (length in the direction orthogonal to the thickness direction of the laminated member) of the laminated member obtained by cutting is 30 to 80 nm It was cut with a diamond knife in the direction.
(3) In a glass container with a capacity of 20 cc, the 0.3 mm ³ crystal of osmium tetraoxide and the cut laminated member obtained in (2) are charged, and a sealed film (a product made by LSS Co., Ltd.) The periphery of the lid of the container was sealed with the name "Parafilm PM996"), and left at room temperature under normal pressure for 1 hour to dye the cut laminated member, thereby obtaining a measurement sample.

1-2. Adhesion UV carbon arc light type light resistance and weather resistance tester according to JIS B7751 (trade name "FAL-AU · B" manufactured by Suga Test Instruments Co., Ltd., light source: UV carbon arc lamp, irradiance: 500 W / m ² The optical members of Examples and Comparative Examples were placed in a black panel temperature of 63 ° C. and treated for 200 hours, and then adhesion was evaluated. Specifically, a cut was made using a cutter knife from the resin layer side of the optical member after the above-mentioned processing to form 100 squares of 1 mm × 1 mm in size. The operation of sticking and peeling off the cut surface with the brand name “Sellotape (registered trademark) No. 405” manufactured by Nichiban Co., Ltd. was performed five times, and the adhesion was evaluated according to the following criteria according to the number of remaining squares.
AA: Remaining number 100
A: Remaining number 75 or more and less than 100 B: Remaining number 50 or more and less than 75 C: Remaining number 25 or more and less than 50 D: Remaining number less than 25

1-3. Scratch resistance The optical members of the examples and comparative examples were fixed on a glass plate, and the # 0000 steel wool was pressed against the surface of the fixed optical member on the resin layer side, at a speed of 90 to 100 mm / s, The width of 70-80 mm was rubbed back and forth 10 times. Subsequently, a black tape was attached to the surface of the acrylic substrate opposite to the resin layer to prepare a flaw evaluation sample. The sample was observed visually from the resin layer side of the sample under illumination of a three-wavelength fluorescent tube, and the 50 mm of the center excluding the left and right ends of the sample was regarded as an effective area, and the scratches were generated in the effective area. It evaluated by.
A: A scratch is not observed in any of a bright room environment and a dark room environment when a load of pressing steel wool is 700 g.
B: When a load of pressing steel wool is 700 g, scratches are observed in a dark room environment but not observed in a light room environment.
C: A scratch is observed in a light room environment and a dark room environment when a load of pressing steel wool is 700 g, but when a load is 500 g, a scratch is observed in any of a light room environment and a dark room environment What is not.
D: When no load was observed in a light room environment but no damage was observed in a dark room environment when the load applied to the steel wool was 500 g.

2. Production of Optical Member [Example 1]
On a 40 μm thick acrylic substrate (glass transition temperature of 115 ° C., 91.5% total light transmittance, 0.8% haze of PMMA resin that constitutes the substrate), the resin layer forming coating solution 1 of the following formulation is applied After drying for 60 seconds at a drying temperature of 110 ° C and a wind speed of 15 m / s, ultraviolet light is irradiated under a nitrogen atmosphere (oxygen concentration 200 ppm or less) so that the integrated light quantity is 100 mJ / cm ² to form a resin layer. The optical member of Example 1 was obtained. The film thickness of the resin layer was 4.0 μm.

<Resin layer forming coating solution 1>
・ 50 parts of multifunctional acrylate monomer (1: 1 mixture of trifunctional acrylate monomer and tetrafunctional acrylate monomer)
· Trifunctional urethane acrylate oligomer 25 parts · Tetrafunctional urethane acrylate oligomer 25 parts · Particles 4 parts (spherical polyacryl-styrene copolymer, average particle diameter 3.5μm)
· Silica fine particles 2.5 parts (average primary particle diameter 12 nm)
・ Photopolymerization initiator 8 parts (manufactured by BASF, Irgacure 184)
Silicone leveling agent 0.1 part Solvent 1 (toluene, relative evaporation rate 200) 50 parts Solvent 2 (IPA, relative evaporation rate 150) 25 parts Solvent 3 (MEK, relative evaporation rate 370) 25 parts

Example 2
An optical member of Example 2 was obtained in the same manner as Example 1 except that the film thickness of the resin layer was changed to 4.5 μm.

Comparative Example 1
The resin layer forming coating solution 2 of the following formulation is applied on the same acrylic substrate as in Example 1 and dried at a drying temperature of 90 ° C. and a wind speed of 10 m / s for 60 seconds, and then ultraviolet light is in a nitrogen atmosphere (oxygen concentration 200 ppm or less) The resin layer was formed by irradiation so that the integrated light amount would be 100 mJ / cm ² below, and an optical member of Comparative Example 1 was obtained. The film thickness of the resin layer was 5.5 μm.

<Resin layer forming coating solution 2>
· Bi-functional acrylate monomer 35 parts · 10 multifunctional acrylate monomers 25 parts · tri-functional urethane acrylate oligomer 20 parts · tetra-functional urethane acrylate oligomer 20 parts · particles 1.2 parts (spherical polyacrylic-styrene copolymer, average particles 3.8 μm in diameter)
· Particles 3.5 parts (spherical polyacryl-styrene copolymer, average particle size 2.0 μm)
· Silica fine particles 0.5 part (average primary particle diameter 12 nm)
・ Photopolymerization initiator 8 parts (manufactured by BASF, Irgacure 184)
Silicone leveling agent 0.1 part Solvent 1 (toluene, relative evaporation rate 200) 63 parts Solvent 2 (IPA, relative evaporation rate 150) 25 parts Solvent 3 (cyclohexanone, relative evaporation rate 32) 10 parts 4 (MIBK, relative evaporation rate 160) 2 parts

  From the results in Table 1, it can be confirmed that the optical member satisfying the condition 1 is excellent in the adhesion between the light transmitting substrate and the resin layer and does not impair the physical properties of the resin layer.

  The optical member of the present invention is useful in that it has excellent adhesion to the resin layer and does not impair various physical properties of the resin layer.

Claims (6)

An optical member having a resin layer on a light transmitting substrate,
The resin layer contains, as a resin component, a cured product of an ionizing radiation curable resin composition and a resin flowing from the light transmitting substrate, and the light transmitting substrate swells at the interface with the resin layer An optical member having an area and satisfying the following condition 1:
<Condition 1>
The transmission electron image of the cross section of the optical member is imaged with a resolution of 100 pixels or more in the number of pixels per 5 μm in the width direction to select an analysis region. The analysis area is an area in a quadrangle in which the length is the thickness of the resin layer and the width is 20 pixels.
The image in the analysis area is grayscaled to 256 tones. The analysis area is divided for each pixel in the thickness direction of the resin layer, and the average gradation of each divided area is calculated. Each divided area is numbered 1, 2, 3 ... n sequentially from the light transmitting base material side, numbered number is numbered with X axis and average gray level of each divided area as Y axis When the relational expression between and the average gradation is calculated by the least square method, the inclination of the relational expression is 0.15 or more.   The optical member according to claim 1, wherein the light transmitting substrate is an acrylic substrate.   The optical member according to claim 1, wherein the resin layer contains particles.   A display device in which one or more optical members are disposed on the light emitting surface side of a display element, wherein at least one of the optical members is an optical member according to any one of claims 1 to 3. .   The display device according to claim 4, wherein the resin layer of the optical member is disposed on the outermost surface of the display device so as to face the opposite side to the display element. A method of selecting an optical member having a resin layer containing a cured product of an ionizing radiation curable resin composition on a light transmitting substrate,
The resin layer contains, as a resin component, a cured product of an ionizing radiation curable resin composition and a resin flowing from the light transmitting substrate, and the light transmitting substrate swells at the interface with the resin layer A method of selecting an optical member, comprising an area and selecting one satisfying the following condition 1
<Condition 1>
The transmission electron image of the cross section of the optical member is imaged with a resolution of 100 pixels or more in the number of pixels per 5 μm in the width direction to select an analysis region. The analysis area is an area in a quadrangle in which the length is the thickness of the resin layer and the width is 20 pixels.
The image in the analysis area is grayscaled to 256 tones. The analysis area is divided for each pixel in the thickness direction 1 of the resin layer, and the average gradation of each divided area is calculated. Each divided area is numbered 1, 2, 3 ... n sequentially from the light transmitting base material side, numbered number is numbered with X axis and average gray level of each divided area as Y axis When the relational expression between and the average gradation is calculated by the least square method, the inclination of the relational expression is 0.15 or more.