JP2017122174A - Liquid curable resin composition, image display device and method for manufacturing image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid curable resin composition that has sufficient adhesion performance as a cured product, has a low dielectric constant and a low shrinkage by curing, and can suppress generation of display unevenness when used as a constituent member of an image display device.SOLUTION: The liquid curable resin composition comprises: a (meth)acrylic resin (A) that has a structural unit derived from at least one monomer selected from the group consisting of a (meth)acrylate having a branched alkyl group and an alkyl methacrylate having a linear alkyl group and also has a (meth)acryloyl group; an acrylic resin (B) that has a structural unit derived from an alkyl acrylate having a linear alkyl group and also has a (meth)acryloyl group; a plasticizer (C); and a photopolymerization initiator (D).SELECTED DRAWING: None

Description

  The present invention relates to a liquid curable resin composition, an image display device using the same, and a method for manufacturing the image display device.

  A liquid crystal display device is illustrated as a typical image display device. A liquid crystal display device includes a liquid crystal cell in which liquid crystal is filled and sealed through a gap of about several microns between a glass substrate having a thickness of about 1 mm on which transparent electrodes, pixel patterns, and the like are formed. The liquid crystal panel which consists of light sources, such as a polarizing plate affixed on and a backlight system, is included.

  Since the polarizing plate constituting this liquid crystal panel is thin and easily damaged, a transparent front plate (protective panel) with a certain space in front of the liquid crystal panel, especially for mobile phones, game machines, digital cameras, and in-vehicle applications. In general, a liquid crystal display device having a structure provided with a) is used.

  In recent years, touch panels have been mounted on mobile phones, game machines, digital cameras, in-vehicle components, notebook computers, desktop computers, personal computer monitors, large liquid crystal monitors, and the like. Such a liquid crystal display device has a laminated structure in which a protective panel, a touch panel, and a liquid crystal panel are laminated in this order, and a certain space is provided between the protective panel and the touch panel, and between the touch panel and the liquid crystal panel. Exists.

  When only the air exists in the space in the liquid crystal display device described above, this space causes light scattering, resulting in a decrease in contrast, luminance, and transmittance, and a decrease in image quality due to double projection. Can happen. As a method for preventing such light scattering, Patent Document 1 discloses a method of filling an oily material in a space between a protective panel and a liquid crystal panel, and Patent Document 2 includes a copolymerization of an acrylic monomer. A method of interposing a sheet between a protective panel and a liquid crystal panel has been proposed.

  In addition, a plasma display panel (PDP), which is one of flat panel displays (FPD), is provided with a space of about 1 to 5 mm from the PDP in order to prevent cracking of the PDP, and a protective panel made of glass or the like having a thickness of about 3 mm. Is provided on the front surface (viewing surface side). As a method for preventing such cracking of the display, light scattering, etc., in Patent Document 3, the space between the protective panel and the plasma display panel, an image display unit such as a liquid crystal panel, and the space between the protective panel and the touch panel are disclosed. There is a method in which an optical film made of a specific resin is interposed in a space and a space between the touch panel and the image display unit (hereinafter collectively referred to as “a space between the protective panel and the image display unit”). Proposed.

JP 05-011239 A JP 2004-125868 A JP 2009-024160 A

  However, the oil-like material used in Patent Document 1 is difficult to seal to prevent leakage, may damage the material used for the liquid crystal panel, and when the protective panel is cracked There is a problem that oily material leaks out.

  On the other hand, optical films (sheets) as disclosed in Patent Documents 2 and 3 do not have the problem of leakage as in the case of using an oil-like material, but display an image such as a liquid crystal display device with a larger size. There is room for improvement when applied to industrial equipment. That is, it is difficult to uniformly produce a large-area optical film corresponding to a large image display device, and even if such an optical film can be produced, the large-area optical film can be uniformly and It is difficult to stack on a display device. If the optical film cannot be uniformly laminated, it may cause display unevenness such as color unevenness.

  As a method for improving the problem that the optical film cannot be uniformly laminated as described above, a method of curing the composition by light irradiation after filling a space with a liquid photocurable resin composition Can be considered. However, in the conventional photocurable resin composition, the cured product of the composition easily stores stress applied from the outside such as thermal expansion and has a low ability to diverge it, so that the stress is concentrated and displayed. There is a problem that unevenness is likely to occur.

  In recent years, with the widespread use of touch panels, higher performance is required for touch panels, and therefore a cured product of a photocurable resin composition is required to have a low dielectric constant. The dielectric constant is related to the responsiveness of the touch panel, and if the dielectric constant is high, malfunction may occur. Furthermore, in order to prevent color unevenness, display unevenness, etc., a low curing shrinkage type liquid curable resin composition is required.

  Therefore, the present invention can be suitably applied to fill the space between the protective panel and the image display unit in the image display device, satisfies the adhesive performance as a cured product, and has a dielectric constant and a curing shrinkage rate. The present invention provides a liquid curable resin composition that is low and capable of suppressing the occurrence of display unevenness when used as a constituent member of an image display device, an image display device using the same, and a method for manufacturing the image display device. Objective.

  As a result of intensive studies, the present inventors have found that a liquid curable resin composition containing a specific component solves the above problems, and has completed the present invention.

That is, the present invention provides the following [1] to [10].
[1] having a structural unit derived from one or more monomers selected from the group consisting of a (meth) acrylate having a branched alkyl group and an alkyl methacrylate having a linear alkyl group, and a (meth) acryloyl group ( ) Acrylic resin (A), a structural unit derived from an alkyl acrylate having a linear alkyl group, an acrylic resin (B) having a (meth) acryloyl group, a plasticizer (C), a photopolymerization initiator ( A liquid curable resin composition containing D).
[2] The viscosity of the acrylic resin (B) at 25 ° C. is lower than the viscosity of the (meth) acrylic resin (A) and higher than the viscosity of the plasticizer (C). Liquid curable resin composition.
[3] The liquid curable composition according to [1] or [2], wherein the content ratio of the (meth) acrylic resin (A) and the acrylic resin (B) is 80/20 mass% to 95/5 mass%. Resin composition.
[4] The liquid curable resin composition according to [1] to [3], wherein the acrylic resin (A) further has a structural unit derived from a polar group-containing monomer.
[5] The liquid according to [4], wherein the polar group-containing monomer is one or more monomers selected from the group consisting of a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, and an acetoacetoxy group-containing monomer. Curable resin composition.
[6] The liquid curable resin composition according to any one of [1] to [5], which contains substantially no organic solvent and has a viscosity at 25 ° C. of 500 to 10,000 mPa · s.
[7] The liquid curable resin composition according to any one of [1] to [6], further containing a monomer copolymerizable with a (meth) acryloyl group as a reactive diluent.
[8] An image display device having a laminated structure including an image display unit, a protection panel, and a resin layer existing between the image display unit and the protection panel, wherein the resin layer includes [1] An image display device comprising a cured product of the liquid curable resin composition according to any one of [7].
[9] An image display device having a laminated structure including an image display unit, a protection panel, a touch panel existing between the image display unit and the protection panel, and a resin layer existing between the touch panel and the protection panel. And the apparatus for image displays which the said resin layer consists of hardened | cured material of the liquid curable resin composition in any one of [1]-[7].
[10] A method for manufacturing an image display device including an image display unit, a protection panel, and a resin layer, wherein the image display unit is between the image display unit and the protection panel. Manufacturing the image display device, comprising the step of interposing the liquid curable resin composition and the step of curing the liquid curable resin composition by light irradiation from the protective panel surface side to form a resin layer. Method.

  According to the present invention, it can be suitably applied to fill a space between a protective panel and an image display unit or the like in an image display device, satisfies the adhesive performance as a cured product, and has a dielectric constant and a curing shrinkage rate. Therefore, it is possible to provide a liquid curable resin composition that is low and capable of suppressing the occurrence of display unevenness even when used in an image display device, an image display device using the same, and a method for manufacturing the image display device.

It is side surface sectional drawing which shows typically one Embodiment of the liquid crystal display device which is an example of the image display device of this invention. It is side surface sectional drawing which shows typically the liquid crystal display device which mounts the touchscreen which is one Embodiment of the liquid crystal display device which is an example of the image display device of this invention. It is side surface sectional drawing which shows typically the test piece for the adhesive force measurement of the hardened | cured material of a liquid curable resin composition.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings depending on cases, but the present invention is not limited to the embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  In this specification, “(meth) acrylate” means at least one of “acrylate” and “methacrylate” corresponding thereto. The same applies to other similar expressions such as “(meth) acryloyl”.

In this specification, the value of the glass transition temperature (Tg) is a value calculated using the FOX equation.
(FOX type)
1 / Tg = W ₁ / Tg ₁ + W ₂ / Tg ₂ +... + W _i / Tg _i +... + W _n / Tg _n
In the FOX formula, n represents the number of types of monomers constituting the target copolymer. Tgi (K) represents the glass transition temperature of the homopolymer of each monomer (i = 1, 2,... N). Furthermore, _{W i,} each monomer (i = 1,2, ··· n) indicates the mass fraction of _{a W 1 + W 2 + ... +} W i + ... W n = 1.

In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values measured using gel permeation chromatography (GPC) and polystyrene as a standard substance. The GPC conditions are shown below.
Measuring instrument: HLC-8320GPC (trade name, manufactured by Tosoh Corporation)
・ Analytical column: TSKgel SuperMultipore HZ-H (3 tubes) (trade name, manufactured by Tosoh Corporation)
Guard column: TSK guard column SuperMP (HZ) -H (trade name, manufactured by Tosoh Corporation)
・ Eluent: THF
・ Measurement temperature: 25 ℃

  In this specification, the viscosity is a value measured based on JIS Z 8803, and specifically, measured at 25 ° C. using an E-type viscometer (trade name “PE-80L” manufactured by Toki Sangyo). It is the value. The calibration of the viscometer can be performed based on JIS Z 8809-JS14000.

[Liquid curable resin composition]
The liquid curable resin composition of this embodiment includes a structural unit derived from one or more monomers selected from the group consisting of (meth) acrylates having a branched alkyl group and alkyl methacrylates having a linear alkyl group; A (meth) acrylic resin (A) having a (meth) acryloyl group, a structural unit derived from an alkyl acrylate having a linear alkyl group, an acrylic resin (B) having a (meth) acryloyl group, and a plasticizer ( A liquid curable resin composition containing C) and a photopolymerization initiator (D). Hereinafter, each component contained in the liquid curable resin composition will be described.

<(Meth) acrylic resin (A)>
The (meth) acrylic resin (A) according to this embodiment is a monomer containing at least one monomer selected from the group consisting of (meth) acrylates having a branched alkyl group and alkyl methacrylates having a linear alkyl group. It is a (meth) acrylic resin obtained by polymerizing components, and has a (meth) acryloyl group at the side chain and / or terminal.

  The monomer component constituting the main chain of the (meth) acrylic resin (A) is at least one selected from the group consisting of alkyl (meth) acrylates having a branched alkyl group and alkyl methacrylates having a linear alkyl group. The monomer is preferably contained in an amount of 99.9% by mass or less, more preferably 30.0 to 99.5% by mass, and further preferably 40.0 to 95% by mass, based on the total monomer components.

  The branched alkyl group preferably has 8 to 24 carbon atoms. Examples of the alkyl (meth) acrylate having a branched alkyl group having 8 to 24 carbon atoms include 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, isomistyryl (meth) acrylate, and 2-propylheptyl (meth) acrylate. , Isooctyl (meth) acrylate, isononyl (meth) acrylate, isoundecyl (meth) acrylate, isododecyl (meth) acrylate, isotridecyl (meth) acrylate, isopentadecyl (meth) acrylate, isohexadecyl (meth) acrylate, isoheptadecyl (meta) ) Acrylate, isostearyl (meth) acrylate, decyltetradecanyl (meth) acrylate, and the like. These can be used individually by 1 type or in combination of 2 or more types.

  The Tg of the alkyl (meth) acrylate homopolymer having a branched alkyl group is preferably -80 to 20 ° C, more preferably -70 to -10 ° C. When the Tg of the homopolymer is −80 ° C. or higher, the strength of the cured product of the liquid curable resin composition is easily improved, and when it is 20 ° C. or lower, the elasticity of the cured product of the liquid curable resin composition is lowered. Unevenness is less likely to occur.

  The content of the alkyl (meth) acrylate having a branched alkyl group is preferably 99.9% by mass or less, more preferably, based on all monomer components constituting the main chain of the (meth) acrylic resin (A). Is 30.0 to 99.5 mass%, more preferably 40.0 to 95 mass%.

  The linear alkyl group preferably has 4 to 24 carbon atoms. Examples of the methacrylate having a linear alkyl group having 4 to 24 carbon atoms include n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, Examples include n-decyl methacrylate, n-undecyl methacrylate, n-dodecyl methacrylate (lauryl methacrylate), n-tridecyl methacrylate, and n-stearyl methacrylate. These can be used alone or in combination of two or more.

  The Tg of the homopolymer of alkyl methacrylate having a linear alkyl group is preferably -80 to 20 ° C, more preferably -70 to -10 ° C. When the Tg of the homopolymer is −80 ° C. or higher, the strength of the cured product of the liquid curable resin composition is easily improved, and when it is 20 ° C. or lower, the elasticity of the cured product of the liquid curable resin composition is low. Therefore, display unevenness is less likely to occur.

  The content of the alkyl methacrylate having a linear alkyl group is preferably 99.9% by mass or less, more preferably 30%, based on all monomer components constituting the main chain of the (meth) acrylic resin (A). It is 0.0-99.5 mass%, More preferably, it is 40.0-95.0 mass%.

  In this embodiment, the alkyl (meth) acrylate having a branched alkyl group and the alkyl methacrylate having a linear alkyl group can be used in combination in a timely manner.

  The (meth) acryloyl group that the (meth) acrylic resin (A) has in the side chain and / or terminal includes, for example, a (meth) acrylic resin having a hydroxyl group, an amino group, or a carboxyl group, and a (meth) acryloyl group-containing isocyanate. You may introduce | transduce by making a compound react.

  Examples of the (meth) acryloyl group-containing isocyanate compound include 2-isocyanate ethyl methacrylate, 2-isocyanate ethyl acrylate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, and the like. These can be used alone or in combination of two or more. Among these, 2-isocyanate ethyl methacrylate is preferable from the viewpoints of photocurability, versatility, and cost.

  The compounding amount of the (meth) acryloyl group-containing isocyanate compound is preferably 0.1 to 10% by mass, and 0.5 to 5% by mass with respect to 100% by mass of the (meth) acrylic resin before introducing the (meth) acryloyl group. % Is more preferable. When the amount of the (meth) acryloyl group-containing isocyanate compound is 0.1% by mass or more, the strength of the cured product of the liquid curable resin composition is easily improved, and when it is 10% by mass or less, the liquid curable resin composition. The elastic modulus of the cured product becomes low, and display unevenness hardly occurs.

  As a method of reacting a (meth) acrylic resin having a hydroxyl group, amino group or carboxyl group at the side chain and / or terminal and a (meth) acryloyl group-containing isocyanate compound, for example, an organic tin catalyst such as dibutyltin dilaurate Below, there is a method of reacting at room temperature (25 ° C.) to 80 ° C. for 2 hours to 10 hours in an inert gas atmosphere.

  The (meth) acrylic resin (A) may further have a structural unit derived from a polar group-containing monomer. That is, the monomer component constituting the main chain of the (meth) acrylic resin (A) can further contain a polar group-containing monomer. The content of the polar group-containing monomer is preferably 0.1 to 20% by mass based on all monomer components, and is 0.5% by mass or more from the viewpoint of increasing the adhesive force and cohesive force of the cured product. More preferably, it is more preferably 1% by mass or more. On the other hand, if the amount of the polar group-containing monomer is too large, the cured product of the liquid curable resin composition becomes hard and the viscosity increases, so the content of the polar group-containing monomer is 18% by mass or less. Is more preferable, and it is still more preferable that it is 15 mass% or less.

  Examples of the polar group-containing monomer include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, and an acetoacetoxy group-containing monomer.

  As the carboxyl group-containing monomer, a compound having a polymerizable group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a carboxyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. These can be used alone or in combination of two or more. Among these, as the carboxyl group-containing monomer, acrylic acid and methacrylic acid are preferable, and acrylic acid is more preferable.

  As the hydroxyl group-containing monomer, a compound having a polymerizable group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a hydroxyl group can be used without particular limitation. Examples of hydroxyl group-containing monomers include 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( Hydroxyalkyl (meth) acrylates such as (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate; hydroxyalkylcycloalkanes such as (4-hydroxymethylcyclohexyl) methyl (meth) acrylate (Meth) acrylate; hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monobi Ether and the like. These can be used alone or in combination of two or more.

  As the nitrogen atom-containing monomer, a compound having a polymerizable group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and an amide group or a nitrile group can be used without particular limitation. Examples of amide group-containing monomers include dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, isopropyl (meth) acrylamide, hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, and the like. It is done. Examples of the nitrile group-containing monomer include (meth) acrylonitrile. These can be used alone or in combination of two or more.

  As the acetoacetoxy group-containing monomer, a monomer having a polymerizable group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and an acetoacetoxy group can be used without particular limitation. Examples of acetoacetoxy group-containing monomers include acetoacetoxyethyl (meth) acrylate, acetoacetoxypropyl (meth) acrylate, acetoacetoxybutyl (meth) acrylate, acetoacetoxypentyl (meth) acrylate, acetoacetoxyhexyl (meth) acrylate, etc. Is mentioned. These can be used alone or in combination of two or more.

  Among these polar group-containing monomers, from the viewpoint of easy introduction of (meth) acryloyl groups into the side chain and / or terminal of (meth) acrylic resin (A), and resistance to ITO electrode corrosion, etc. Containing monomers are preferred.

  Although the weight average molecular weight of (meth) acrylic resin (A) is not specifically limited, 4000-100000 are preferable, 6000-80000 are more preferable, 10000-50000 are still more preferable. When the weight average molecular weight of the (meth) acrylic resin (A) is 4000 or more, the strength of the cured product of the liquid curable resin composition is hardly lowered, and when it is 100,000 or less, the viscosity of the liquid curable resin composition increases. It is difficult to handle the liquid curable resin composition easily.

  From the viewpoint of workability, the viscosity of the (meth) acrylic resin (A) is preferably from 100,000 to 800,000 mPa · s, more preferably from 150,000 to 500,000 mPa · s, and even more preferably from 200,000 to 300,000.

  The content of the (meth) acrylic resin (A) is adjusted to a viscosity that is easy to handle as a liquid curable resin composition while maintaining the strength of the cured product of the liquid curable resin composition. 30 to 90% by mass is preferable and 45 to 80% by mass is more preferable based on the total amount of the object. When the content of the (meth) acrylic resin (A) is 30% by mass or more, the strength of the cured product of the liquid curable resin composition is hardly lowered, and when it is 90% by mass or less, the viscosity of the liquid curable resin composition. Is difficult to rise, and the liquid curable resin composition can be easily handled.

<Acrylic resin (B)>
The acrylic resin (B) according to this embodiment is an acrylic resin obtained by polymerizing a monomer component containing an alkyl acrylate having a linear alkyl group, and has a (meth) acryloyl group at the side chain and / or the terminal. Have.

  The monomer component constituting the main chain of the acrylic resin (B) is one or more monomers selected from the group consisting of alkyl acrylates having a linear alkyl group, based on the total monomer components, 99.9% by mass. It is preferable to include the following, more preferably 30.0 to 99.5% by mass, still more preferably 40.0 to 95% by mass.

  It is preferable that carbon number of a linear alkyl group is 8-24. Examples of the acrylate having a linear alkyl group having 8 to 24 carbon atoms include n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-undecyl acrylate, n-dodecyl acrylate (lauryl acrylate), n -Tridecyl acrylate, n-stearyl acrylate, etc. are mentioned. These can be used alone or in combination of two or more.

  The Tg of the homopolymer of alkyl methacrylate having a linear alkyl group is preferably -80 to 20 ° C, more preferably -70 to -10 ° C. If the Tg of the homopolymer is −80 ° C. or higher, the strength of the cured product of the liquid curable resin composition is easily improved, and if it is 20 ° C. or lower, the elasticity of the cured product of the liquid curable resin composition is reduced. Display unevenness is less likely to occur.

  The (meth) acryloyl group that the acrylic resin (B) has in the side chain and / or the terminal is obtained by, for example, reacting an acrylic resin having a hydroxyl group, an amino group, or a carboxyl group with a (meth) acryloyl group-containing isocyanate compound. May be introduced.

  As the (meth) acryloyl group-containing isocyanate compound, the compounds exemplified in the (meth) acrylic resin (A) can be used.

  The compounding amount of the (meth) acryloyl group-containing isocyanate compound is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, with respect to 100% by mass of the acrylic resin before introducing the (meth) acryloyl group. preferable. When the amount of the (meth) acryloyl group-containing isocyanate compound is 0.1% by mass or more, the strength of the cured product of the liquid curable resin composition is easily improved, and when it is 10% by mass or less, the liquid curable resin composition. The elasticity of the cured product becomes low, and display unevenness hardly occurs.

  As a method of reacting an acrylic resin having a hydroxyl group, an amino group or a carboxyl group at the side chain and / or terminal with a (meth) acryloyl group-containing isocyanate compound, for example, under an organic tin catalyst such as dibutyltin dilaurate, There is a method of reacting at room temperature (25 ° C.) to 80 ° C. for 2 hours to 10 hours in an inert gas atmosphere.

  The monomer component constituting the main chain of the acrylic resin (B) can further contain a polar group-containing monomer. The content of the polar group-containing monomer is preferably 0.1 to 20% by mass based on all monomer components, and is 0.5% by mass or more from the viewpoint of increasing the adhesive force and cohesive force of the cured product. More preferably, it is more preferably 1% by mass or more. On the other hand, if the amount of the polar group-containing monomer is too large, the cured product of the liquid curable resin composition becomes hard and the viscosity increases, so the content of the polar group-containing monomer is 18% by mass or less. Is more preferable, and it is still more preferable that it is 15 mass% or less.

  Examples of the polar group-containing monomer include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, or an acetoacetyl group-containing monomer, and each of the compounds exemplified in the (meth) acrylic resin (A) is used. Can do.

  Among these polar group-containing monomers, a hydroxyl group-containing monomer is used from the viewpoint of easily introducing a (meth) acryloyl group into the side chain and / or terminal of the acrylic resin (B), having corrosion resistance against ITO electrodes, and the like. preferable.

  Although the weight average molecular weight of an acrylic resin (B) is not specifically limited, 4000-100000 are preferable, 6000-80000 are more preferable, 10000-50000 are still more preferable. When the weight average molecular weight of the acrylic resin (B) is 4000 or more, the strength of the cured product of the liquid curable resin composition is hardly lowered, and when it is 100000 or less, the viscosity of the liquid curable resin composition is hardly increased and is liquid. It becomes easy to handle the curable resin composition.

  The viscosity of the acrylic resin (B) is preferably 10000 to 80000 mPa · s, more preferably 15000 to 50000 mPa · s, and further preferably 20000 to 35000 from the viewpoint of workability.

  The content ratio of the (meth) acrylic resin (A) and the acrylic resin (B) is preferably 80/20% by mass to 95/5% by mass, and 85/15% by mass to 95/5% by mass. It is more preferable. When the content ratio of the acrylic resin (B) is 5% by mass or more, the viscosity of the liquid curable resin composition becomes low, and the liquid curable resin composition becomes easy to handle, and when it is 20% by mass or less, the liquid curable property. It becomes easy to reduce the dielectric constant of the resin composition.

<Plasticizer (C)>
The plasticizer (C) according to this embodiment is a component that substantially does not have a (meth) acryloyl group and is liquid at 25 ° C. From the viewpoint of volatility and workability, the weight average molecular weight of the plasticizer (C) is preferably 350 to 30000, more preferably 400 to 20000, and still more preferably 1000 to 15000.

  From the viewpoint of workability, the viscosity of the plasticizer (C) is preferably 8000 mPa · s or less, more preferably 5000 mPa · s or less, and still more preferably 3000 mPa · s or less. The lower limit of the viscosity of the plasticizer (C) is not particularly limited, and may be 500 mPa · s or more.

  In the liquid curable resin composition of the present embodiment, the viscosity of the acrylic resin (B) at 25 ° C. is lower than the viscosity of the (meth) acrylic resin (A) and the viscosity of the plasticizer (C). High is preferred. That is, (meth) acrylic resin (A), acrylic resin (B) and plasticizer (C) have a viscosity relationship at 25 ° C. of (meth) acrylic resin (A)> acrylic resin (B)> plasticizer (C It is preferable that

  Examples of the plasticizer (C) include butadiene rubber, isoprene rubber, silicon rubber, styrene butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, urethane rubber, acrylic resin, chlorosulfonated polyethylene rubber, fluorine rubber, Hydrogenated nitrile rubber, liquid liquid of epichlorohydrin rubber, poly α-olefin such as polybutene, hydrogenated α-olefin oligomer such as hydrogenated polybutene, polyvinyl oligomer such as atactic polypropylene; aromatic oligomer such as biphenyl and triphenyl Hydrogenated polyene oligomers such as hydrogenated liquid polybutadiene; paraffinic oligomers such as paraffin oil and chlorinated paraffin oil; cycloparaffinic oligomers such as naphthene oil; dimethyl phthalate, diethyl phthalate , Dibutyl phthalate, di- (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, di (heptyl, nonyl, undecyl) Phthalic acid derivatives such as phthalate, benzyl phthalate, butyl benzyl phthalate, dinonyl phthalate, dicyclohexyl phthalate; isophthalic acid derivatives such as dimethyl isophthalate, di- (2-ethylhexyl) isophthalate, diisooctyl isophthalate; di- (2 Tetrahydrophthalic acid derivatives such as -ethylhexyl) tetrahydrophthalate, di-n-octyltetrahydrophthalate, diisodecyltetrahydrophthalate; -Adipic acid derivatives such as butyl adipate, di (2-ethylhexyl) adipate, diisodecyl adipate, diisononyl adipate; azelaic acid derivatives such as di- (2-ethylhexyl) azelate, diisooctyl azelate, di-n-hexyl azelate Sebacic acid derivatives such as di-n-butyl sebacate and di- (2-ethylhexyl) sebacate; maleic acid derivatives such as di-n-butyl malate, dimethyl malate, diethyl maleate and di- (2-ethylhexyl) malate; -Fumaric acid derivatives such as n-butyl fumarate and di- (2-ethylhexyl) fumarate; tri- (2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, triisodecyl trimellitate, triisooctyltri Melitate, chicken Trimellitic acid derivatives such as n-hexyl trimellitate and triisononyl trimellitate; pyromellitic acid derivatives such as tetra- (2-ethylhexyl) pyromellitate and tetra-n-octyl pyromellitate; triethyl citrate, tri- Citric acid derivatives such as n-butyl citrate, acetyl triethyl citrate, acetyl tri- (2-ethylhexyl) citrate; monomethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, di- ( Itaconic acid derivatives such as 2-ethylhexyl) itaconate; oleic acid derivatives such as butyl oleate, glyceryl monooleate, diethylene glycol monooleate; methyl acetyl ricinolate, butyl acetyl ricinolate, glycerin Ricinoleic acid derivatives such as rumonoricinoleate and diethylene glycol monoricinoleate; stearic acid derivatives such as n-butyl stearate, glycerin monostearate and diethylene glycol distearate; diethylene glycol monolaurate, diethylene glycol dipelargonate, pentaerythritol fatty acid ester, etc. Other fatty acid derivatives of: triethyl phosphate, tributyl phosphate, tri- (2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris (chloroethyl) phosphate Phosphoric acid derivatives such as diethylene glycol dibenzoate, dipropylene glycol Glycol derivatives such as dibenzoate, triethylene glycol dibenzoate, triethylene glycol di- (2-ethylbutyrate), triethylene glycol di- (2-ethylhexoate), dibutylmethylene bisthioglycolate; glycerol monoacetate And glycerin derivatives such as glycerol triacetate and glycerol tributyrate, and epoxy derivatives such as epoxidized soybean oil, diisodecyl epoxyhexahydrophthalate, epoxy triglyceride, octyl epoxidized oleate, and decyl epoxidized oleate. These compounds can be used alone or in combination of two or more.

  Among these plasticizers (C), from the viewpoint of compatibility with the (meth) acrylic resin (A) and the acrylic resin (B), an acrylic resin plasticizer that is a resin of the same type is preferable. Acrylic resin plasticizers can be synthesized using various (meth) acrylate compounds. For example, the monomer components exemplified in the synthesis of (meth) acrylic resin (A) and acrylic resin (B) are polymerized. May also be synthesized. From the viewpoint of compatibility with the (meth) acrylic resin (A) and the acrylic resin (B), the monomer component constituting the acrylic resin plasticizer can be used alone or in combination of two or more. .

  The content of the plasticizer (C) is preferably 3 to 3, based on the total amount of the liquid curable resin composition, from the viewpoint of adjusting the viscosity of the liquid curable resin composition and the elastic modulus of the cured product to an appropriate range. It is 40 mass%, More preferably, it is 5-35 mass%. When the content of the plasticizer (C) is 3% by mass or more, the viscosity of the liquid curable resin composition becomes low, and the liquid curable resin composition becomes easy to handle, and when it is 40% by mass or less It becomes easy to improve the intensity | strength of the hardened | cured material of an adhesive resin composition.

<Photopolymerization initiator (D)>
The photopolymerization initiator (D) is not particularly limited as long as it initiates photopolymerization, and a commonly used photopolymerization initiator can be used. Examples of the photopolymerization initiator (D) include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, and photoactive oxime light. Polymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, acylphosphine oxide photopolymerization initiator, etc. Can be used.

  Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one (product) Name “Irgacure 651” (manufactured by BASF), anisole methyl ether and the like. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (trade name “Irgacure 184”, manufactured by BASF), 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (trade name “Irgacure 2959”, manufactured by BASF), 2-hydroxy-2-methyl-1-phenyl- Propan-1-one (trade name “Darocur 1173”, manufactured by BASF), methoxyacetophenone, and the like. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. These can be used individually by 1 type or in combination of 2 or more types.

  Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like are included. These can be used individually by 1 type or in combination of 2 or more types.

  Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis ( 2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine Oxides, bis (2-mes Xylbenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropane-1- Yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis ( , 6-Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6- Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, Bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,3,5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine Oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethoxybenzoyl-2,4 6-Trimethylbenzoyl-n-butylphosphineoxy Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,4 6-trimethylbenzoyl) phosphine oxide] decane, tri (2-methylbenzoyl) phosphine oxide and the like. These can be used individually by 1 type or in combination of 2 or more types.

  0.01-5 mass% is preferable with respect to 100 mass% of liquid curable resin compositions, and, as for content of a photoinitiator (D), 0.05-3 mass% is more preferable.

  When the usage-amount of a photoinitiator (D) is less than 0.01 mass%, a polymerization reaction may become inadequate. On the other hand, when the usage-amount of a photoinitiator (D) exceeds 5 mass%, a photoinitiator may absorb an ultraviolet-ray and an ultraviolet-ray may not reach an inside. In this case, the cohesive force of the cured product of the liquid curable resin composition is lowered, and the strength is lowered. In addition, a photoinitiator (D) can be used individually by 1 type or in combination of 2 or more types.

  The liquid curable resin composition of the present embodiment preferably contains substantially no organic solvent (solvent) from the viewpoint of improving wet heat resistance and suppressing the generation of bubbles in the cured product. Here, “substantially does not contain an organic solvent” means that no organic solvent is intentionally added, and does not significantly deteriorate the characteristics after photocuring of the liquid curable resin composition of the present embodiment. If present, a trace amount of organic solvent may be present. Specifically, the content of the organic solvent in the resin composition may be 1000 ppm or less, preferably 500 ppm or less, more preferably 100 ppm or less, and still more preferably an organic solvent with respect to the total amount of the resin composition. Does not contain at all. In the present invention, the “organic solvent” means an organic compound that does not have a (meth) acryloyl group, is liquid at 25 ° C., and has a boiling point of 250 ° C. or less at atmospheric pressure.

  You may mix | blend the reactive diluent for viscosity adjustment with the liquid curable resin composition of this embodiment. The reactive diluent is a monomer copolymerizable with a (meth) acryloyl group. For example, various (meth) acrylates, methyl (meth) acrylates, ethyl (meth) acrylates exemplified by the monomer components described above, n -Butyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, isoamyl (meth) Acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-undecyl acrylate, n-dodecyl acrylate (lauryl acrylate), n-tridecyl acrylate, phenoxyethyl (meth) acrylate , Benzyl (meth) acrylate, cyclohexyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate, terpene (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) Acrylic acid ester monomers such as tetrahydrofurfuryl acrylate and 2-methoxyethyl acrylate; Vinyl monomers such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene, N-vinylcaprolactam, and N-vinylpyrrolidone; ) Polyethylene glycols such as polyethylene glycol acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate Examples thereof include a silyl ester monomer; a fluorine-containing (meth) acrylate; a silicone (meth) acrylate; an amino group-containing monomer; an imide group-containing monomer; a vinyl ether monomer; and a silane monomer containing a silicon atom.

  Examples of silane monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like. These can be used alone or in combination of two or more.

  The liquid curable resin composition of this embodiment can reduce the addition amount of the reaction diluent for viscosity adjustment by containing (meth) acrylic resin (A) and acrylic resin (B). Yes, the curing shrinkage of the cured product of the liquid curable resin composition can be reduced.

  The addition amount of the reactive diluent is preferably 30% by mass or less, and more preferably 20% by mass or less, based on the total amount of the liquid curable resin composition. When the addition amount of the reactive diluent exceeds 30% by mass with respect to the total amount of the liquid curable resin composition, the curing shrinkage of the cured product becomes large, which easily causes display unevenness.

  The liquid curable resin composition of the present embodiment can further contain other additives as long as the effects of the present invention are not impaired. Other additives include stabilizers such as triphenyl phosphite, 1,4-bis (3-mercaptobutyryloxy) butane, 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3 , 5-triazine-2,4,6 (1H, 3H, 5H) -trione, thiol compounds such as pentaerythritol tetrakis (3-mercaptobutyrate), and the like. By blending the thiol compound, the curing can proceed sufficiently even when the protective panel or the like has a portion provided with a light shielding portion.

  The viscosity at 25 ° C. of the liquid curable resin composition of the present embodiment is preferably 500 to 10000 mPa · s, more preferably 1000 to 7000 mPa · s, and still more preferably 3000 to 6000 mPa · s. When the viscosity is less than 500 mPa · s, it is difficult to control the coating thickness, and when it exceeds 10,000 mPa · s, the handling property is deteriorated.

  The dielectric constant at 25 ° C. and 100 kHz of the cured product of the liquid curable resin composition of the present embodiment is preferably 3.5 or less, and more preferably 3.0 or less. When the dielectric constant exceeds 3.5, when the cured product of the liquid curable resin composition is used for the image display device on which the touch panel is mounted, the touch panel may malfunction.

  The storage elastic modulus at 25 ° C. of the cured product of the liquid curable resin composition of the present embodiment is preferably 1000 Pa to 6000 Pa, and more preferably 2500 Pa to 4000 Pa. If the storage elastic modulus is less than 1000 Pa, the strength of the cured product is weak, and if it exceeds 6000 Pa, display unevenness tends to occur.

  The tan δ (loss elastic modulus / storage elastic modulus) that is the ratio of the storage elastic modulus and the loss elastic modulus at 25 ° C. of the cured product of the liquid curable resin composition of the present embodiment is 0.2 to 1.0. Preferably, it is 0.5-1.0. If tan δ is less than 0.2, display unevenness tends to occur, and if it exceeds 1.0, the strength of the cured product becomes weak.

  The cure shrinkage at 25 ° C. of the cured product of the liquid curable resin composition of the present embodiment is preferably 2.0% or less, and more preferably 1.5% or less. If the curing shrinkage rate exceeds 2.0%, display unevenness tends to occur.

[Image display device]
Hereinafter, a liquid crystal display device which is an example of an image display device that can be manufactured using the liquid curable resin composition of the present embodiment will be described.

  The image display device of the present embodiment can take an aspect having a laminated structure including an image display unit, a protection panel, and a resin layer existing between the image display unit and the protection panel. The image display device according to the present embodiment includes an image display unit, a protection panel, a touch panel that exists between the image display unit and the protection panel, and a resin layer that exists between the touch panel and the protection panel. The aspect which has the laminated structure containing can be taken. In the image display device of the present embodiment, the resin layer is made of a cured product of the liquid curable resin composition of the present embodiment described above.

  FIG. 1 is a side sectional view schematically showing an embodiment of a liquid crystal display device which is an example of an image display device of the present invention. The liquid crystal display device shown in FIG. 1 includes an image display unit 1 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 10, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. The transparent resin layer 32 provided on the upper surface of 20 and the transparent protective substrate (protective panel) 40 provided on the surface thereof. In addition, the transparent resin layer 32 is comprised from the hardening body of the liquid curable resin composition of this embodiment.

  FIG. 2 is a side cross-sectional view schematically showing a liquid crystal display device equipped with a touch panel, which is an embodiment of a liquid crystal display device which is an example of the image display device of the present invention. The liquid crystal display device shown in FIG. 2 includes an image display unit 1 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 10, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. 20, a transparent resin layer 32 provided on the top surface, a touch panel 30 provided on the top surface of the transparent resin layer 32, a transparent resin layer 31 provided on the top surface of the touch panel 30, and a transparent protective substrate provided on the surface thereof 40.

  In the liquid crystal display device of FIG. 2, a transparent resin layer is interposed between the image display unit 1 and the touch panel 30 and between the touch panel 30 and the transparent protective substrate 40. It suffices to intervene in at least one of these. When the touch panel is on-cell, the touch panel and the liquid crystal display cell are integrated. As a specific example, the liquid crystal display cell 10 of the liquid crystal display device of FIG. 1 may be replaced with an on-cell.

  Since the liquid crystal display device shown in FIGS. 1 and 2 includes the cured product of the liquid curable resin composition of the present embodiment as the transparent resin layer 31 or 32, the liquid crystal display device has impact resistance and has no double image and is clear. A high contrast image can be obtained.

  The liquid crystal display cell 10 can be made of a liquid crystal material well known in the art. Also, depending on the control method of the liquid crystal material, it is classified into TN (Twisted Nematic) method, STN (Super-twisted nematic) method, VA (Vertical Alignment) method, IPS (In-Place-Switching) method, etc. In the form, a liquid crystal display cell using any control method may be used.

  As the polarizing plates 20 and 22, a polarizing plate common in this technical field can be used. The surface of the polarizing plate may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the polarizing plate or on both sides thereof. Moreover, as the touch panel 30, what is generally used in this technical field can be used.

  The transparent resin layer 31 or 32 can be formed with a thickness of 0.02 mm to 3 mm, for example. In particular, the liquid curable resin composition of the present embodiment is easy to form a thick film, and is suitable for forming the transparent resin layer 31 or 32 having a thickness of 0.1 mm or more.

  As the transparent protective substrate 40, a general optical transparent substrate can be used. Examples of the transparent protective substrate include inorganic plates such as glass plates and quartz plates, resin plates such as acrylic plates and polycarbonate plates, and resin sheets such as thick polyester sheets. Among these, when high surface hardness is required, a glass plate and an acrylic plate are preferable, and a glass plate is more preferable. The surface of the transparent protective substrate 40 may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the transparent protective substrate or on both sides. Further, the transparent protective substrate can be used in combination of a plurality of substrates.

  Although there is no restriction | limiting in particular in the structure as the backlight system 50, Generally, it is comprised from illumination means, such as reflection means, such as a reflecting plate, and a lamp. As these reflecting means and illuminating means, well-known means / configuration applied in a normal image display device can be applied.

[Method for Manufacturing Image Display Device]
The image display apparatus using the liquid curable resin composition of the present embodiment as shown in FIGS. 1 and 2 can be manufactured by the following method.

  First, an image display apparatus including an image display unit and a protection panel as shown in FIG. 1 interposes the liquid curable resin composition of the present embodiment between the image display unit and the protection panel. A step (hereinafter also referred to as “step (1a)”), a step of irradiating light from the protective panel surface side to cure the liquid curable resin composition, and forming a transparent resin layer (hereinafter referred to as “step (2a)”. ) "))).

  Further, the image display device including the image display unit, the touch panel, and the protection panel as shown in FIG. 2 is provided between the image display unit and the touch panel and / or between the touch panel and the protection panel. And a step of interposing the liquid curable resin composition of the present embodiment (hereinafter also referred to as “step (1b)”), the liquid curable resin composition is cured by irradiating light from the protective panel surface side, and transparent It can be manufactured through a step of forming a resin layer (hereinafter also referred to as “step (2b)”).

  In the steps (1a) and (1b), as a method of interposing the liquid curable resin composition of the present embodiment between the image display unit and the protective panel, for example, using a dispenser, the image display unit or After applying the resin composition on the protective panel, the method of pasting at a vacuum (reduced pressure) or atmospheric pressure, the resin composition between the image display unit and the protective panel arranged at a certain interval Examples include a casting method. In addition, when casting the liquid curable resin composition of this embodiment, you may form a dam around an image display unit and a protection panel.

The light irradiation in the steps (2a) and (2b) is performed by irradiating active energy rays such as ultraviolet rays, electron beams, α rays, and β rays. For example, an ultraviolet irradiation device (product name, manufactured by Eye Graphics Co., Ltd.) "US5-X0401"). In addition, the liquid curable resin composition of this embodiment can obtain hardened | cured material with an exposure amount of 1000 mJ / cm < ² > or more, and the exposure amount is preferably 2000-10000 mJ / cm < ² >. The exposure amount refers to a value obtained by multiplying the illuminance measured by an ultraviolet irradiation device (trade name “UV-M02 (receiver: UV-36)” manufactured by Oak Co., Ltd.) or the like with the irradiation time (seconds). .

  Examples of the light source for ultraviolet irradiation include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, and an LED lamp. Among these, a high pressure mercury lamp and a metal halide lamp are preferable. In the case of light irradiation, irradiation from the protective panel surface side and irradiation from the side surface may be used in combination. Moreover, hardening can also be accelerated | stimulated by heating the laminated body containing a curable resin composition simultaneously with light irradiation.

  As described above, the liquid crystal display device that is one of the image display devices that can be manufactured by using the liquid curable resin composition of the present embodiment has been described. The image display device that can be manufactured by using the composition is not limited to this. For example, the present invention can be applied to a plasma display (PDP), a cathode ray tube (CRT), a field emission display (FED), an organic EL display, a 3D display, electronic paper, and the like. In particular, when the image display device is 10 inches or larger, it is more preferable to produce a transparent resin layer using the liquid curable resin composition of the present embodiment.

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

<(Meth) acrylic resin (A)>
A monomer component constituting the main chain shown in Table 1 is blended to synthesize a (meth) acrylic resin, and then reacted with 2-isocyanatoethyl methacrylate to form a (meth) acrylic resin (A1) having a methacryloyl group in the side chain. ) To (A6) were synthesized. Table 1 shows the viscosity and the weight average molecular weight (Mw) of (A1) to (A6).

<Acrylic resin (B)>
After synthesizing an acrylic resin by blending monomer components constituting the main chain shown in Table 2, acrylic resins (B1) to (B4) having a methacryloyl group in the side chain by reacting with (2-isocyanatoethyl methacrylate) Table 2 shows the viscosity and Mw of (B1) to (B4).

<Plasticizer (C)>
Monomer components constituting the main chain shown in Table 2 were blended to synthesize acrylic resin plasticizers (C1) and (C2). Table 2 shows the viscosity and Mw of (C1) and (C2).

<(Meth) acrylic resin (E)>
Monomer components constituting the main chain shown in Table 2 were blended to synthesize (meth) acrylic resins (E1) and (E2). (E1) and (E2) are (meth) acrylic resins having no methacryloyl group. Table 2 shows the viscosity and Mw of (E1) and (E2).

  The synthesis of the (meth) acrylic resin (A), acrylic resin (B), plasticizer (C) and (meth) acrylic resin (E) is a known production method such as various radical polymerizations such as solution polymerization and bulk polymerization. Was appropriately selected. Moreover, the viscosity and Mw of these resin were measured by the method mentioned above.

  In Tables 1 and 2, ISTA is isostearyl acrylate (manufactured by Osaka Organic Chemical Industry), DTD-A is 2-decyltetradecanyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.), and IDMA is isodecyl methacrylate (Kyoeisha Chemical Co., Ltd.). BMA is butyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.), LMA is lauryl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.), BA is butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.), and LA is lauryl acrylate (manufactured by Osaka Organic Chemical Industries, Ltd.). ), OA is octyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), HEMA is 2-hydroxyethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), ACMO is acryloylmorpholine (manufactured by Kojin Co., Ltd.), MOI is 2-isocyanate Ethyl methacrylate (made by Showa Denko KK) is shown.

<Examples 1-9 and Comparative Examples 1-4>
Each component was mix | blended with the compounding ratio (mass part) shown in Table 3, and it mixed for 30 minutes at 90 degreeC, and prepared the liquid curable resin composition of Examples 1-9. Moreover, each component was mix | blended with the compounding ratio (mass part) shown in Table 4, and it mixed for 30 minutes at 90 degreeC, and prepared the liquid curable resin composition of Comparative Examples 1-4.

  In Tables 3 and 4, TPO is a photopolymerization initiator (D), indicates 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (BASF), LA (lauryl acrylate) and ACMO (acryloylmorpholine). ) Is a reactive diluent.

  About the liquid curable resin composition and hardened | cured material obtained by each Example and each comparative example, the test shown below was done and each characteristic was evaluated. The results are shown in Table 5.

(viscosity)
Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., trade name “RE-80L”, cone angle: 3 degrees), each example and each comparative example were prepared under the condition of a rotation speed of 1.0 rpm. The viscosity (mPa · s) at 25 ° C. of the liquid curable resin composition was measured.

(Dielectric constant)
The liquid curable resin composition prepared in each Example and each Comparative Example was dropped onto a PET film (trade name “KX-4”, manufactured by Nipper Co., Ltd.) whose surface was release-treated, and the resin composition Another PET film was laminated so that the film thickness after curing was 1 mm. Then, from one PET film side, the resin composition is cured by irradiating with an ultraviolet ray having an exposure amount of 6000 mJ / cm ² using an ultraviolet ray irradiation device (eye graphics Co., Ltd., trade name “US5-X0401”). Cured product.

Next, the PET film is peeled off, and the cured product is bonded to a circular aluminum electrode having an outer diameter of 56 mm and a thickness of 1.2 mm, and then the other surface of the cured product is copper having an outer diameter of 54 mm and a thickness of 80 μm. The foil was laminated to prepare a test piece for measuring the dielectric constant. Next, the terminal is brought into contact with the substantially central portion of the test piece, and the capacitance (C) is measured at 25 ° C. and at a frequency of 100 kHz using a dielectric constant measuring apparatus (product name “LCR meter E4980” manufactured by Agilent Technologies). Then, the dielectric constant ε _r was obtained by substituting into the following equation. Here, ε ₀ is the dielectric constant of vacuum, and d is the thickness of the adhesive layer.
C = ε ₀ × ε _r × (18 mm × 18 mm) / d

(Storage modulus and tan δ)
The cured product was cut into 10 mm × 10 mm, and using a rheometer (trade name “MCR-301” manufactured by Anton Paar Co., Ltd.) under the conditions of 1 Hz and 25 ° C., the storage elastic modulus was measured using PP08. The loss modulus was measured. Further, the loss tangent (tan δ) was calculated from the ratio between the storage elastic modulus and the loss elastic modulus (loss elastic modulus / storage elastic modulus).

(Curing shrinkage)
The liquid curable resin composition was added to the marked line of the graduated cylinder, the weight was measured, and the specific gravity of the liquid curable resin composition was measured. Next, the liquid curable resin composition is cured by irradiating with an ultraviolet ray having an exposure amount of 6000 mJ / cm ² using an ultraviolet ray irradiation apparatus (eye graphics Co., Ltd., trade name “US5-X0401”). A cured product of × 10 mm × 1 mm was prepared, the weight in water was measured, and the specific gravity of the cured product of the liquid curable resin composition was measured. Using these measured values, the cure shrinkage rate was calculated by the following formula.
Curing shrinkage (%) = ((specific gravity of cured product−specific gravity of resin composition) / specific gravity of cured product) × 100

(Adhesion)
First, two glass slides S1112 (manufactured by Matsunami Glass Industry Co., Ltd.) were prepared as slide glass S1112 (manufactured by Matsunami Glass Industry Co., Ltd.). Next, as shown in FIG. 3, after the liquid curable resin composition is dropped onto the slide glass 62, the upper surface of the slide glass 64 is adjusted while adjusting the liquid curable resin composition to have an outer diameter of 10 mm and a thickness of 150 μm. And curing the liquid curable resin composition by irradiating with an ultraviolet ray with an exposure amount of 6000 mJ / cm ² using an ultraviolet irradiation device (product name “US5-X0401” manufactured by Eye Graphics Co., Ltd.). The object 60 was formed and the test piece of the structure shown in FIG. 3 was produced.

  About the said test piece, the slide glass 64 was pulled up with the speed | rate of 10 mm / min in the state which fixed the slide glass 62 using AUTOGRAPH EZ-TEST EZ-S (made by Shimadzu Corporation), and the shear strength was measured. And shear strength was made into the adhesive force of the hardened | cured material 60 of a liquid curable resin composition.

  Since the liquid curable resin compositions of Examples 1 to 9 have a low dielectric constant of the cured product, the touch panel can be prevented from malfunctioning when used in an image display device equipped with a touch panel, and the storage elasticity of the cured product. The rate and the cure shrinkage rate are low and tan δ is high, so that it is possible to suppress the occurrence of display unevenness.

  On the other hand, the liquid curable resin composition of Comparative Example 1 has a large storage elastic modulus and cure shrinkage of the cured product, and display unevenness is likely to occur. Since the liquid curable resin composition of Comparative Example 2 has a high dielectric constant, the touch panel is likely to malfunction when used in an image display device equipped with a touch panel. The liquid curable resin compositions of Comparative Examples 3 and 4 have low adhesion of the cured product, and the resin layer is easily peeled off or the substrate is easily displaced.

  The cured product of the liquid curable resin composition of the present invention has excellent adhesion, has a low dielectric constant and curing shrinkage, and suppresses the occurrence of display unevenness when used as a component of an image display device. be able to. Therefore, the liquid curable resin composition of the present invention can be suitably used as a constituent member for filling a space between a protective panel and an image display unit in an image display device such as a liquid crystal display device.

  DESCRIPTION OF SYMBOLS 1 ... Image display unit, 10 ... Liquid crystal display cell, 20, 22 ... Polarizing plate, 30 ... Touch panel, 31, 32 ... Transparent resin layer, 40 ... Protection panel, 50 ... Backlight system, 60 ... Hardened | cured material, 62, 64 ... slide glass.

Claims (10)

A (meth) acrylic resin having a structural unit derived from one or more monomers selected from the group consisting of a (meth) acrylate having a branched alkyl group and an alkyl methacrylate having a linear alkyl group, and a (meth) acryloyl group (A) and
An acrylic resin (B) having a structural unit derived from an alkyl acrylate having a linear alkyl group and a (meth) acryloyl group;
A plasticizer (C);
A photopolymerization initiator (D);
A liquid curable resin composition containing   The liquid curing according to claim 1, wherein the viscosity of the acrylic resin (B) at 25 ° C is lower than the viscosity of the (meth) acrylic resin (A) and higher than the viscosity of the plasticizer (C). Resin composition.   The liquid curable resin composition of Claim 1 or 2 whose content rate of the said (meth) acrylic resin (A) and the said acrylic resin (B) is 80/20 mass%-95/5 mass%.   The liquid curable resin composition according to any one of claims 1 to 3, wherein the acrylic resin (A) further has a structural unit derived from a polar group-containing monomer.   The liquid curability according to claim 4, wherein the polar group-containing monomer is one or more monomers selected from the group consisting of a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, and an acetoacetoxy group-containing monomer. Resin composition.   The liquid curable resin composition as described in any one of Claims 1-5 which does not contain an organic solvent substantially and whose viscosity in 25 degreeC is 500-10000 mPa * s.   The liquid curable resin composition as described in any one of Claims 1-6 which further contains the monomer copolymerizable with a (meth) acryloyl group as a reactive diluent. An image display device having a laminated structure including an image display unit, a protection panel, and a resin layer present between the image display unit and the protection panel,
The image display apparatus which the said resin layer consists of the hardened | cured material of the liquid curable resin composition as described in any one of Claims 1-7. An image display having a laminated structure including an image display unit, a protection panel, a touch panel existing between the image display unit and the protection panel, and a resin layer existing between the touch panel and the protection panel Device for
The image display apparatus which the said resin layer consists of the hardened | cured material of the liquid curable resin composition as described in any one of Claims 1-7. A method for manufacturing an image display device comprising an image display unit, a protective panel, and a resin layer,
A step of interposing the liquid curable resin composition according to any one of claims 1 to 7 between the image display unit and the protective panel;
Irradiating light from the protective panel surface side, curing the liquid curable resin composition, and forming the resin layer;
A method for manufacturing an image display device.

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