JP2013142132A - Laminate, transparent optical member using the same and image display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate produced by laminating different members on both surfaces of an adhesive layer, each member simultaneously satisfying performance required for each of these different members, and a transparent optical member.SOLUTION: In the laminate, the adhesive layer 13 is formed on a transparent substrate 11 in which a printing ink layer 11b is formed. The adhesive layer 13 contains a cured product of an adhesive composition containing a (meth)acrylic adhesive main agent mainly consisting of a (meth)acrylic acid alkyl ester having 1-12C and a hydroxyl-group-containing (meth)acrylic monomer having a hydroxyl group and a polymerizable group copolymerizable with the (meth)acrylic adhesive main agent and/or a (meth) acrylic glycol ether having the polymerizable group. The loss tangent of the adhesive layer at 60°C is 0.1 or more and 0.41 or less, the storage elastic modulus of the adhesive layer at 25°C is 1.0×10, and the adhesive layer has a maximum value of the loss tangent tanδ in the temperature range of -40°C to -10°C.

Description

  The present invention relates to a laminate and an optical member used for an image display device such as a touch panel, a liquid crystal display, and electronic paper, and more specifically, a laminate in which an adhesive layer is laminated on a transparent glass substrate on which a printing ink layer is formed. And a transparent optical member in which the transparent glass substrate and a transparent conductive film on which a metal oxide thin film such as ITO is formed are laminated via the adhesive layer.

  In recent years, information terminal devices such as a touch panel, a liquid crystal display, and electronic paper have been reduced in size and thickness, and a complicated and precise design is performed inside the product. As a transparent optical member arranged on the user's viewing side, a transparent conductive substrate having a transparent substrate such as glass and a conductive thin film such as indium tin oxide (hereinafter also referred to as “ITO”) formed on the surface In general, an optical member obtained by laminating the above with an adhesive layer is used.

  This adhesive layer has one surface that adheres to the ITO film side and the other surface that adheres to the transparent substrate side such as glass. In the transparent substrate, various characters and designs are decorated from the surface. As can be seen, a decorative layer such as a printed layer is often provided on the frame portion other than the image display portion on the back side. Since the decorative layer causes a step on the back surface of the transparent substrate, it is required to suppress the elasticity of the adhesive layer to be low, to generate bubbles at the step, and to improve the step following property of the adhesive layer. Moreover, in order to improve the visibility of an image display part, it is calculated | required that whitening of an adhesion layer is prevented.

As said adhesive layer, the photocurable adhesive composition which has a C1-C12 (meth) acrylic-acid alkylester as a main component is hardened | cured, and the dynamic viscoelastic spectrum of the adhesive layer at a frequency of 1 Hz The loss tangent at 70 ° C. is 0.43 to 0.98, the storage elastic modulus at 70 ° C. is 0.8 × 10 ^{4 to} 3.4 × 10 ⁴ Pa, and the adhesive layer is −40 to −10 ° C. One having a maximum value of loss tangent in the temperature region has been proposed (see Patent Document 1). And (A) an alicyclic hydrocarbon resin, (B) an amorphous saturated polyolefin resin, (C) a resin having an acrylic group, and (D) an initiator that causes a reaction of the resin, (A) Based on 100 parts by mass of the component, the amount of the component (B) is 10 to 200 parts by mass, the amount of the component (C) is 10 to 200 parts by mass, and the amount of the component (D) is 0.1. It is -20 mass parts, and the storage elastic modulus of the adhesion layer is 1.0 * 10 < ³ > Pa or more and 1.0 * 10 < ⁴ > Pa or less in 1 Hz and 80 degreeC (refer patent document 2). .

Special table 2009-155503 gazette JP 2010-072471 A

  However, in the pressure-sensitive adhesive layers described in Patent Documents 1 and 2, the storage elastic modulus is too low, so that troubles that the pressure-sensitive adhesive remains on the blade in post-processing such as slitting or half-cutting occur, or the pressure-sensitive adhesive strength increases. It may be difficult to re-paste. For this reason, moderate elasticity is requested | required as the whole adhesion layer.

  In addition, since the adhesive layer is in contact with the ITO film, a configuration for preventing the corrosion of the ITO film is necessary, and it is necessary to eliminate the acid causing the corrosion as much as possible. It is difficult to maintain moderate elasticity.

  Thus, in a system such as glass / adhesive layer / ITO base material, different chemical properties may be required depending on the adhesion target, and an adhesive layer that simultaneously satisfies the conflicting requirements is required.

  The present invention has been made in view of the above circumstances, and the object is to provide a laminate that simultaneously satisfies the performance required for each of these different members when different members are laminated on both sides of the adhesive layer. And providing a transparent optical member.

  The present inventor has conducted extensive research to solve the above problems, and has a step by polymerizing a hydrophilic monomer in the (meth) acrylic adhesive main agent to appropriately adjust the overall elasticity. In addition to being able to prevent whitening of the adhesive layer, it can prevent troubles that the adhesive remains on the blade during post-processing such as slitting and half-cutting, Corrosion can also be prevented, and it has been found that the respective adhesive performances to different adherends can be satisfied at the same time, and the present invention has been completed. Specifically, the present invention provides the following.

(1) The present invention is a laminate in which an adhesive layer is formed on a transparent substrate on which a printing ink layer is formed, and the adhesive layer is a (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms. A (meth) acrylic pressure-sensitive adhesive main component having a main component, a polymerizable group copolymerizable with the (meth) acrylic pressure-sensitive adhesive main component and a hydroxyl group-containing (meth) acrylic monomer having a hydroxyl group and / or the polymerizable group A loss tangent tanδ (60 ° C.) at 60 ° C. of the pressure-sensitive adhesive layer is 0.1 or more and 0.41 or less. The adhesive modulus E ′ (25 ° C.) at 25 ° C. of the adhesive layer is 1.0 × 10 ⁵ Pa or more and less than 1.0 × 10 ⁷ Pa, and the adhesive layer has a temperature of −40 ° C. to −10 ° C. Maximum loss tangent tan δ in the region It is a laminate having a value.

  (2) Moreover, this invention is a laminated body as described in (1) whose said adhesive layer is an energy-beam curable adhesive and a thermosetting adhesive.

  (3) Moreover, this invention is a transparent conductive group in which the metal oxide layer is formed in the said transparent base material and the surface through the said adhesion layer in the laminated body as described in (1) or (2). The adhesive layer is a transparent optical member that does not substantially contain an acid component.

  (4) Moreover, this invention is an image display apparatus with which the transparent optical member as described in (3) is arrange | positioned at the surface side of a display.

  According to the present invention, in addition to having a high step following property with respect to the transparent substrate on which the printing ink layer is formed, and preventing whitening of the adhesive layer, the adhesive is used in post-processing such as slits and half-cuts. Can prevent troubles remaining on the blade, and also prevent corrosion of the ITO film, thereby providing a transparent optical member that simultaneously satisfies the respective adhesive performances to different adherends.

It is a schematic sectional drawing of the transparent optical member which concerns on embodiment of this invention. It is a schematic sectional drawing of the image display apparatus using the said transparent optical member. It is a schematic sectional drawing of the adhesive sheet obtained in the manufacture process of the said transparent optical member. It is a figure which shows the loss tangent and storage elastic modulus in an Example and a comparative example.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

<Laminated body>
In the laminate of the present invention, an adhesive layer is formed on a transparent substrate on which a printing ink layer is formed.

[Transparent substrate]
The transparent substrate may be any material as long as it is used on the surface of the image display device, and may be glass or a transparent film.

  The printing ink layer is formed on at least a part of the periphery on the transparent substrate. The printing ink layer has a thickness of about 100 μm at the maximum. Therefore, the pressure-sensitive adhesive layer is required to have followability with respect to the level difference of the transparent substrate 11 generated by the printing ink layer.

[Adhesive layer]
The pressure-sensitive adhesive layer is composed of a (meth) acrylic pressure-sensitive adhesive main component mainly composed of (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms, a polymerizable group copolymerizable with this (meth) acrylic pressure-sensitive adhesive main agent, and It contains a cured product of a pressure-sensitive adhesive composition containing a hydroxyl group-containing (meth) acrylic monomer having a hydroxyl group and / or (meth) acrylic acid glycol ether having a polymerizable group.

  It is preferable that the pressure-sensitive adhesive composition does not substantially contain an acid component. When the acid component is contained, the transparent conductive substrate can be corroded when the transparent substrate and the transparent conductive substrate having the metal oxide layer formed on the surface are laminated via the adhesive layer. Therefore, it is not preferable. Examples of such an acid component include carboxylic acid. On the other hand, as a composition that does not substantially contain an acid component, a (meth) acrylic pressure-sensitive adhesive main agent mainly composed of (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms, and this (meth) acrylic pressure-sensitive adhesive main agent And a hydroxyl group-containing (meth) acrylic monomer having a polymerizable group and a hydroxyl group and / or a (meth) acrylic acid glycol ether having the polymerizable group, and the above (meth) acrylic pressure-sensitive adhesive main agent, Examples thereof include a pressure-sensitive adhesive obtained by copolymerization with the hydroxyl group-containing (meth) acrylic monomer and / or the (meth) acrylic acid glycol ether.

  Here, “not containing substantially” means that the carboxyl group content in the (meth) acrylic polymer is less than 25 ppm. In this invention, corrosion of a transparent conductive base material can be effectively prevented by not containing 25 ppm or more of carboxyl groups in the (meth) acrylic polymer. In addition, content of the carboxyl group in a (meth) acrylic-type polymer can be measured with a nuclear magnetic resonance apparatus (NMR). Specifically, a carboxyl group and a silylating agent are reacted, and a peak derived from the silylated product is measured by 1H-NMR (600 MHz) (lower limit of quantification: 25 ppm).

((Meth) acrylic adhesive main agent)
The said (meth) acrylic-type adhesive main ingredient has a C1-C12 (meth) acrylic-acid alkylester as a main component. Here, the main component means that the copolymerization ratio is 51% by mass or more, and preferably 65% by mass or more. Adhesiveness suitable for a to-be-adhered member can be provided by making a C1-C12 (meth) acrylic-acid alkylester into a main component. In this specification, acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid.

  Specific examples of the (meth) acrylic acid alkyl ester having a (meth) alkyl side chain having 1 to 12 carbon atoms include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec -Butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n- Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-he Sill methacrylate, cyclohexyl methacrylate, n- octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate and the like. These can be used alone or in combination of two or more.

  Among them, (meth) acrylic acid alkyl ester having a (meth) alkyl side chain having 4 to 9 carbon atoms is preferable. By using a (meth) acrylic acid alkyl ester having a (meth) alkyl side chain with a carbon number within the range, a suitable flexibility can be imparted to the adhesive layer, and a printing ink layer is formed at least at a part of the periphery. The level | step difference followable | trackability with respect to the transparent base material which can be improved can be improved. In particular, 2-ethylhexyl (meth) acrylate, n-butyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate are excellent in durability, transparency, coating suitability, etc., and low in cost. It is more preferable at this point.

(Hydroxyl group-containing (meth) acrylic monomer)
The (meth) acrylic polymer may contain a hydroxyl group-containing (meth) acrylic monomer having a polymerizable group and a hydroxyl group copolymerizable with the (meth) acrylic acid ester.

  Examples of the hydroxyl group-containing (meth) acrylic monomer having a polymerizable group and a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-chloro-2. -Hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, caprolactone-modified (meth) acrylate, polyethylene glycol acrylate, polypropylene glycol (meth) acrylate and the like.

(Glycol ether)
The (meth) acrylic polymer may contain (meth) acrylic acid glycol ether having a polymerizable group copolymerizable with the (meth) acrylic acid ester. There may be any number of polymerizable groups.

  Examples of (meth) acrylic acid glycol ether having a polymerizable group at one end include methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate and the like. Examples of the (meth) acrylic acid glycol ether having a polymerizable group at both ends include dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, and the like.

  The copolymerization ratio (mass ratio) of the (meth) acrylic acid alkyl ester as the main component and the hydroxyl group-containing (meth) acrylic monomer and / or (meth) acrylic glycol ether as the accessory component is (meth) acrylic acid. The alkyl ester is not particularly limited as long as it is a main component, and can be appropriately set so as to exhibit a desired adhesive strength. From the viewpoint of durability, adhesiveness, optical properties, etc., an acrylate ester / hydroxyl group-containing monomer = It is preferable that it is 99 / 1-70 / 30. The copolymerization ratio can be measured with a nuclear magnetic resonance apparatus (NMR).

  The mass average molecular weight (Mw) of the (meth) acrylic polymer is not particularly limited, but is preferably in the range of 300,000 to 1,500,000, more preferably 500,000 to 1,300,000 from the viewpoint of durability. Is within the range. In addition, the said mass mean molecular weight is a polystyrene conversion value by gel permeation chromatography (GPC).

(Loss tangent)
The loss tangent (hereinafter also referred to as “tan δ (60 ° C.)”) of the adhesive layer at 60 ° C. is preferably 0.1 or more and 0.41 or less, and preferably 0.33 or more and 0.35 or less. More preferred. tan δ is one of the parameters that reflect the viscosity of the adhesive layer and show the stress relaxation behavior (deformation delay when force is applied). For example, tan δ is a dynamic viscoelasticity measurement method (attachment mode: compression mode, frequency) based on JIS K7244-1 using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments as a measuring device. 1 Hz, temperature: −50 to 150 ° C., temperature rise temperature: 5 ° C./min). In the present invention, the adhesive layer has moderate viscoelasticity, so that it has high step following ability with respect to the transparent base material on which the printing ink layer is formed at least at a part of the periphery, and has a slit, a half cut, etc. Loss tangent tan δ was used as an index for the purpose of preventing troubles in which the adhesive remains on the blade during post-processing. When the value of tan δ is lower than the above range, the adhesive has high fluidity, and it becomes difficult to follow the shrinkage of the glass substrate at a high temperature, and the adhesive force is reduced. It is not preferable at the point which may become. If the value of tan δ is higher than the above range, it is not preferable in that the adhesive may have low fluidity at high temperatures, and the stress applied to the deformation of the TAC substrate cannot be relaxed, resulting in failure to obtain durability.

  The adhesive layer has a maximum value of loss tangent tan δ in the temperature range of −40 ° C. to −10 ° C. Since it has a maximum value in this temperature region, there are obtained advantages such as excellent drop impact resistance and excellent workability at room temperature.

(Storage modulus)
The storage elastic modulus E ′ (25 ° C.) at 25 ° C. of the adhesive layer is preferably 1.0 × 10 ⁵ Pa or more and less than 1.0 × 10 ⁷ Pa, and 2.9 × 10 ⁵ Pa or more 6 It is preferably less than 0.0 × 10 ⁵ Pa. If the storage elastic modulus is less than 1.0 × 10 ⁵ Pa, the elasticity of the adhesive layer as a whole will be insufficient, and there may be a problem that the adhesive remains on the blade during post-processing such as slitting and half-cutting. This is not preferable because the adhesive property and the adhesive strength are increased and it may be difficult to reattach. When the storage elastic modulus exceeds 1.0 × 10 ⁷ Pa, the elasticity of the entire pressure-sensitive adhesive layer is too high, and as a result, a level difference suitable for a transparent substrate on which a printing ink layer is formed at least at a part of the periphery is obtained. It is not preferable in that it may not have the property.

  In addition, the storage elastic modulus E ′ in the present invention is one of dynamic mechanical properties, and by applying strain or stress that changes (vibrates) with time to a sample, and detecting the stress or strain generated thereby, The value stored in the sample among the values obtained by the method for measuring the mechanical properties of the sample. Similarly to the loss tangent, the storage elastic modulus E ′ is also measured using a solid viscoelasticity analyzer RSA-III and a dynamic viscoelasticity measurement method in accordance with JIS K7244-1 (attachment mode: compression mode, frequency: 1 Hz, temperature: −50 to 150 ° C., temperature rising temperature: 5 ° C./min).

(Adhesive layer thickness)
Since the thickness of the printing ink layer formed on the back surface of the glass substrate is about 60 μm at the maximum, the thickness of the adhesive layer is preferably 100 μm or more and 500 μm or less. If the thickness is less than 100 μm, it may not be possible to follow the step on the transparent substrate caused by the printing ink layer, which is not preferable. On the other hand, if the thickness exceeds 500 μm, it may adversely affect optical characteristics such as light transmittance, which is not preferable.

<Transparent optical member>
FIG. 1 shows an example of the configuration of a transparent optical member 1 according to the present invention. In the transparent optical member 1 according to the present invention, the transparent base material 11 in which the printing ink layer 11b is formed on a part of the periphery of the glass base material 11a, and the transparent conductive base material 13 contain the pressure-sensitive adhesive composition. It forms through the adhesion layer 12 to do. The transparent conductive base material 13 includes a base material 13a, a first metal oxide layer 13b formed on one surface of the base material 13a, and a second metal oxide layer formed on the other surface of the base material 13a. 13c.

  The substrate 13a may be any material as long as a conductive film such as an ITO film or a zinc oxide (AZO: Al-Zn-O) film is formed on a film substrate such as a polyester film or a glass substrate. It may be something like this. The thickness of the film substrate 12a is preferably 25 μm to 250 μm. If it is less than 25 μm, it is not preferable because it is a thin film and its workability is poor and its durability is insufficient. If it exceeds 250 μm, it is not preferable in terms of cost, and since it is a thick film, the light transmittance is decreased, which is not preferable as an optical member.

The first metal oxide layer 13b corresponds to a sensor in the X-axis direction, and the second metal oxide layer 13c corresponds to a sensor in the Y-axis direction. Examples of the metal oxide include ZnO, TiO ₂ , CeO ₂ , Sb ₂ O ₅ , SnO ₂ , Y ₂ O ₃ , La ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ , Nb ₂ O _5, etc. Not as long. The film thickness of the metal oxide layers 13b and 13c is preferably 10 to 200 nm. When the thickness is less than 10 nm, a missing portion is generated as an electrode due to coating unevenness at the time of layer formation, which is not preferable in that an appropriate current collecting effect may not be obtained. If it exceeds 200 nm, it is not preferable in that the cost increases.

  A metal electrode for current collection is formed on a part of the metal oxide layers 13b and 13c. The printing ink layer 11b and the metal electrode are preferably formed at substantially the same position as viewed from the surface of the transparent substrate 11. Thereby, the metal electrode formed on the metal oxide layers 13b and 13c can be hidden, and when the transparent optical member 1 is used for the image display device 2, the design of the information terminal device is enhanced.

<Image display device>
FIG. 2 shows an example of the configuration of the image display device 2 according to the present invention. On the outermost surface of the image display device 2, the transparent optical member 1 is formed in the order of a transparent substrate 11, an adhesive layer 12, and a transparent conductive substrate 13. A display layer 15 is laminated on the back surface of the transparent optical member 1 via an adhesive layer 14. The adhesive layer 14 may have the same composition and film thickness as the adhesive layer 12, or may have a different composition and film thickness.

<The manufacturing method of the transparent optical member 1>
The transparent optical member 1 of the present invention is manufactured by the following method.
1. Production of Adhesive Sheet 20 The production process of the adhesive sheet 20 will be described with reference to FIG. The pressure-sensitive adhesive composition is applied onto a release film (PET separator) 21 and sufficiently dried, then laminated with a release film (PET separator) 22 and irradiated with energy rays to cure the photocuring component. Thereafter, the pressure-sensitive adhesive sheet 20 including the pressure-sensitive adhesive layer 12 is obtained by aging for a predetermined time to cure the thermosetting component. Moreover, the adhesive sheet (not shown) which consists of the peeling film 21 / adhesion layer 14 / release film 22 by which the peeling film 21 and the peeling film 22 were laminated | stacked through the adhesion layer 14 by the same method is also obtained.

2. Bonding of transparent substrate 11 and transparent conductive substrate 13 (1) The adhesive sheet 20 is punched to produce an adhesive sheet (not shown) cut into a desired size and shape.
(2) One release film 21 of the pressure-sensitive adhesive sheet subjected to punching is peeled off, and the pressure-sensitive adhesive surface is bonded to the transparent substrate 11.
(3) The other release film 22 of the punched pressure-sensitive adhesive sheet is peeled off, and the pressure-sensitive adhesive surface is bonded to the transparent conductive substrate 13. The transparent optical member 1 can be obtained through the above steps.
Alternatively, the transparent optical member 1 can be obtained also by the following method.
(4) One peeling film 21 of the pressure-sensitive adhesive sheet subjected to punching is peeled off, and the pressure-sensitive adhesive surface is bonded to the transparent conductive substrate 13.
(5) The other release film 22 of the punched pressure-sensitive adhesive sheet is peeled off, and the pressure-sensitive adhesive surface is bonded to the transparent substrate 11.

<Method for Manufacturing Image Display Device 2>
The image display device 2 of the present invention is manufactured by the following method.
(1) First, a pressure sensitive adhesive sheet (not shown) composed of the release film 21 / adhesive layer 14 / release film 22 is punched to produce an adhesive sheet (not shown) cut into a desired size and shape. One release film 21 of the pressure-sensitive adhesive sheet subjected to punching is peeled off, and the pressure-sensitive adhesive surface is bonded to the display layer 15.
(2) Subsequently, the other release film 22 of the pressure-sensitive adhesive sheet subjected to the punching process is peeled, and the pressure-sensitive adhesive surface is bonded to the transparent conductive base material 13 side of the transparent optical member 1 to thereby provide the image display device of the present invention. 2 can be manufactured.
Alternatively, the image display device 2 can also be obtained by the following method.
(3) First, a pressure sensitive adhesive sheet (not shown) composed of the release film 21 / adhesive layer 14 / release film 22 is punched to produce an adhesive sheet (not shown) having a desired size and shape. One release film 21 of the pressure-sensitive adhesive sheet subjected to punching is peeled off, and the pressure-sensitive adhesive surface is bonded to the transparent conductive substrate 13 side of the transparent optical member 1.
(4) Subsequently, the other release film 22 of the pressure-sensitive adhesive sheet subjected to the punching process is peeled, and the pressure-sensitive adhesive surface is bonded to the display layer 15.

  The energy rays are not particularly limited, and examples thereof include microwaves, infrared rays, visible rays, ultraviolet rays, X rays, γ rays and the like. Among these, ultraviolet rays that are particularly easy to handle and can obtain relatively high energy are more preferable.

As the energy ray, light in a wavelength region of 200 to 450 nm is preferable, and light in a wavelength region of 300 to 450 nm is more preferable. The light source is not particularly limited, and for example, a high pressure mercury lamp, an ultra high pressure mercury lamp, a carbon arc lamp, a mercury vapor arc, a fluorescent lamp, an argon glow lamp, a halogen lamp, an incandescent lamp, a low pressure mercury lamp, a flash UV lamp, deep UV A lamp, a xenon lamp, a tungsten filament lamp, sunlight, etc. are mentioned. With these light sources, integrated light quantity 0.3~1J / cm ^2, preferably by irradiation with light such that the range of 0.5~0.8J / cm ^2, to cure the adhesive layer 12 Can do. If the integrated light quantity is less than 0.3 J / cm ² , the adhesive layer 12 may be insufficiently cured, and if it exceeds 1 J / cm ² , the base material and the adhesive may be deformed or deteriorated. It is not preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

カッコ内は、アクリル系粘着剤主剤の固形分１００質量部に対する固形分換算での質量部数である。

The value in parentheses is the number of parts by mass in terms of solid content with respect to 100 parts by mass of solid content of the acrylic pressure-sensitive adhesive main agent.

<Example 1>
100 parts by mass of acrylic adhesive main agent (trade name “SK2975”, weight average molecular weight: 400,000, solid content: 42%, manufactured by Soken Chemical Co., Ltd.) and 4-hydroxybutyl acrylate (solid content: 100%, Osaka Organic Chemistry) 6.72 parts by mass of polyethylene glycol diacrylate (trade name “A-600”, solid content: 100%, Shin-Nakamura Chemical Co., Ltd.) 3.024 parts by mass and butyl acrylate (solid content: 100%) , Manufactured by Nippon Shokubai Co., Ltd.) and 10.08 parts by mass of isocyanate curing agent (trade name “Y-75”, hexamethylene diisocyanate curing agent, solid content: 75%, manufactured by Soken Chemical Co., Ltd.) , Silane coupling agent (trade name “A50”, solid content: 50%, manufactured by Soken Chemical Co., Ltd.) 0.25 part by mass, energy ray curing initiator (trade name: Irgacure 127, BASF Corporation) ) And 0.4 part by weight, a mixed solvent of toluene and methyl ethyl ketone (trade name: KT-11, weight ratio 1: 1, was DIC Graphics Co., Ltd.) was dissolved in 25 parts by weight to obtain an adhesive composition.

The film thickness of this adhesive composition was 175 g / m ² (when dried) on the release surface side of a release film (PET separator, trade name: Therapy BX9A (RX), film thickness: 38 μm, manufactured by Toray Film Processing Co., Ltd.). After coating and drying sufficiently, a release film (PET separator, trade name: Therapeutic MFA (RX), film thickness: 38 μm, manufactured by Toray Film Processing Co., Ltd.) is laminated, and the therapeutic BX9A (RX) Ultraviolet rays (VPS-6 (using H bulb), 700 mJ / cm ² × 1 time, manufactured by Fusion Co., Ltd.) were irradiated from the side. Then, the adhesive sheet 20 was obtained by aging at 25 ° C. for 4 days.

  After the pressure-sensitive adhesive sheet 20 is cut into a predetermined size, one release film is peeled off, and the pressure-sensitive adhesive surface is bonded to the transparent substrate 11. Then, the other release film is peeled off, and the pressure-sensitive adhesive surface is peeled off from the transparent conductive substrate 13. The optically transparent member of Example 1 was obtained.

<Example 2>
Without using 4-hydroxybutyl acrylate, 0.84 parts by mass of ethyl carbitol acrylate (trade name “V # 190”, monoacrylate containing glycol ether, solid content: 10%, manufactured by Osaka Organic Chemical Co., Ltd.) A transparent optical member of Example 2 was obtained in the same manner as in Example 1 except that the amount of butyl acrylate was 15.96 parts by mass.

<Example 3>
In the same manner as in Example 1, except that 1.68 parts by mass of the ethyl carbitol acrylate was used without using the 4-hydroxybutyl acrylate, and the amount of the butyl acrylate was 15.12 parts by mass. A transparent optical member of Example 3 was obtained.

<Comparative Example 1>
The transparent optical member of Comparative Example 1 was prepared in the same manner as in Example 1 except that the 4-hydroxybutyl acrylate, the polyethylene glycol diacrylate, the butyl acrylate, and the energy beam curing initiator were not used. Obtained.

<Comparative example 2>
The transparent optical fiber of Comparative Example 2 was prepared in the same manner as in Example 1 except that the amount of butyl acrylate was changed to 16.8 parts by mass without using 4-hydroxybutyl acrylate and polyethylene glycol diacrylate. A member was obtained.

<Measurement of viscoelasticity of adhesive layer>
The viscoelasticity of the adhesive layer was examined using storage elastic modulus E ′ and loss tangent tan δ as parameters. The storage elastic modulus E ′ and loss tangent tan δ are measured using a dynamic viscoelasticity measurement method (attachment mode: compression) in accordance with JIS K7244-1 using a solid viscoelasticity analyzer RSA-III manufactured by TA Instruments. Mode, frequency: 1 Hz, temperature: -50 to 150 degrees, temperature increase rate: 5 degrees / minute). The results are shown in FIG.

<Evaluation of step filling by decoration>
It was evaluated whether or not the level difference caused by the printing ink layer was appropriately followed. This evaluation was performed as follows. The transparent optical members of Examples and Comparative Examples were put into an autoclave apparatus and processed at 60 ° C., 0.5 MPa, for 30 minutes. The results are shown in Table 2. If the transparent substrate on which the printing ink layer is formed has an appropriate level followability, “○” is indicated, and the transparent substrate on which the printing ink layer is formed does not have an appropriate level following capability. The case was set to “x”.

<Evaluation of whitening prevention>
The whitening prevention property was evaluated as follows. The optically transparent members of Examples and Comparative Examples were put into a constant temperature layer of 80 ° C. and 90% RH for 100 hours, and the haze of the optical members immediately after the lapse of 100 hours was measured using a Nippon Denshoku turbidity measuring apparatus NDH-2000. . The results are shown in Table 2. An optical member having a haze of less than 0.5% was designated as “◯”, and an optical member having a haze of 0.5% or more was designated as “x”.

  A pressure-sensitive adhesive layer comprising a main component of an acrylic pressure-sensitive adhesive mainly comprising an alkyl acrylate ester having 1 to 12 carbon atoms, a hydroxyl group-containing acrylic monomer having a polymerizable group and a hydroxyl group copolymerizable with the acrylic pressure-sensitive adhesive main agent, and / or Or when containing the hardened | cured material of the adhesive composition containing the acrylic acid glycol ether which has the said polymeric group, the loss tangent tan-delta (60 degreeC) in 60 degreeC of the adhesion layer and the storage elastic modulus E '(25 degreeC) 25 ° C.) is within an appropriate range, and the adhesive layer has a maximum value of loss tangent tan δ in a temperature range of −40 ° C. to −10 ° C. It was also confirmed that the workability of post-processing such as slits and half cuts was excellent (Examples 1 to 3).

  On the other hand, when the (meth) acrylic monomer copolymerizable with the acrylic adhesive main agent is not contained, an appropriate loss tangent tan δ (60 ° C.) cannot be obtained, and there is a possibility that the step due to decoration cannot be filled appropriately. Was confirmed (Comparative Example 1). Even when a (meth) acrylic monomer copolymerizable with the acrylic pressure-sensitive adhesive main agent is contained, when this (meth) acrylic monomer is a hydrophobic material, an appropriate loss tangent tan δ (60 ° C.) is obtained. It was not obtained, and it was confirmed that not only the step due to decoration could not be filled properly, but also the whitening prevention property was inferior (Comparative Example 2).

DESCRIPTION OF SYMBOLS 1 Transparent optical member 2 Image display apparatus 11 Transparent base material 12 Adhesive layer 13 Transparent conductive base material 14 2nd adhesive layer 15 Display layer

Claims (4)

A laminate in which an adhesive layer is formed on a transparent substrate on which a printing ink layer is formed,
The pressure-sensitive adhesive layer is a (meth) acrylic pressure-sensitive adhesive main component mainly composed of (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms, and a polymerizable group copolymerizable with this (meth) acrylic pressure-sensitive adhesive main agent. And a cured product of a pressure-sensitive adhesive composition containing a hydroxyl group-containing (meth) acrylic monomer having a hydroxyl group and / or (meth) acrylic acid glycol ether having the polymerizable group,
Loss tangent tan δ (60 ° C.) at 60 ° C. of the adhesive layer is 0.1 or more and 0.41 or less,
The storage elastic modulus E ′ (25 ° C.) at 25 ° C. of the adhesive layer is 1.0 × 10 ⁵ Pa or more and less than 1.0 × 10 ⁷ Pa,
The adhesive layer is a laminate having a maximum value of loss tangent tan δ in a temperature range of −40 ° C. to −10 ° C.   The laminate according to claim 1, wherein the adhesive layer is an energy ray curable and thermosetting adhesive.   The transparent base material and a transparent conductive base material on which a metal oxide layer is formed are laminated via the adhesive layer in the laminate according to claim 1 or 2, wherein the adhesive layer is an acid. A transparent optical member containing substantially no components.   An image display device in which the transparent optical member according to claim 3 is arranged on the surface side of the display.

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