JP6044071B2 - Liquid curable resin composition, method for producing image display device using the same, and image display device - Google Patents

Description

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

  The polarizing plate that makes up this liquid crystal panel is thin and easily scratched. Especially in mobile phones, game consoles, digital cameras, and in-vehicle applications, a transparent front plate (protective panel) with a certain space in front of the liquid crystal panel In general, a liquid crystal display device having a structure provided with a) is used.

  Furthermore, in recent years, touch panels have been mounted on mobile phones, game machines, digital cameras, in-vehicle parts, notebook computers, desktop computers, personal computer monitors, and the like. In the case of such a liquid crystal display device, a protective panel, a touch panel, and a liquid crystal panel are stacked in this order, and a constant structure is provided between the protective panel and the touch panel, and between the touch panel and the liquid crystal panel. There exists a space.

When the space in the above-mentioned liquid crystal display device is air, this space causes light scattering, resulting in a decrease in contrast, brightness, and transmittance, and further a decrease in image quality due to double projection. obtain.
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 discloses a sheet obtained by copolymerizing an acrylic monomer. There have been proposed methods for interposing the film between the protective panel and the liquid crystal panel.

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 and light scattering, Patent Documents 3 and 4 disclose a space between a protective panel and an image display unit such as a plasma display panel or a liquid crystal panel, and a protective panel. An optical film made of a specific resin is used in a space between the touch panel and a space between the touch panel and the image display unit (hereinafter, also collectively referred to as “a space between the protective panel and the image display unit”). An intervening method has been proposed.

JP-A-5-011239 JP 2004-125868 A JP 2004-058376 A JP 2009-024160 A

However, the oil-like material used in Patent Document 1 is difficult to seal to prevent leakage, and may damage the material used for the liquid crystal panel. Furthermore, there is a problem that oil-like material leaks out when the protective panel is broken.
In addition, the optical film made of a resin disclosed in Patent Document 3 has a problem that it becomes cloudy when a short-time wet heat resistance test is performed after application to a display.

  Furthermore, the optical films (sheets) disclosed in Patent Documents 2 and 4 have room for improvement when applied to image display devices such as larger liquid crystal display devices. 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 displayed as a large image. It is difficult to stack on the equipment. If the optical film cannot be laminated uniformly, it may cause problems such as color unevenness.

  The present invention can be suitably applied to fill a space between a protective panel and an image display unit in a large-sized image display device. An object of the present invention is to provide a liquid curable resin composition that can be a cured product having excellent properties and a high elongation rate, a method for producing an image display device using the composition, and an image display device.

In response to the above problems, the present inventors have a liquid curable resin composition containing a specific component that is excellent in transparency and moist heat resistance and has a low curing shrinkage rate, excellent adhesion, and elongation rate. It discovered that it could become a high hardened | cured material.
That is, the present invention provides the following [1] to [4].
[1] (A) silica particles having an average particle diameter of 1 nm to 1 μm;
(B) a polymer having an ethylenically unsaturated bond in the molecule;
(C) a low molecular weight monomer having one ethylenically unsaturated group in the molecule, and (D) a polymerization initiator,
A liquid curable resin composition comprising:
[2] A method of manufacturing an image display device comprising an image display unit and a protection panel,
A step of interposing the liquid curable resin composition according to the above [1] between the image display unit and the protective panel;
And a step of curing the liquid curable resin composition by irradiating light from the protective panel side.
[3] A method for manufacturing an image display device comprising an image display unit, a touch panel, and a protection panel,
A step of interposing the liquid curable resin composition according to the above [1] between the image display unit and the touch panel and / or between the touch panel and the protective panel;
And a step of curing the liquid curable resin composition by irradiating light from the protective panel side.
[4] An image display device manufactured by the manufacturing method according to [2] or [3].

Since the liquid curable resin composition of the present invention is excellent in transparency and moist heat resistance and has a low curing shrinkage rate, an excellent adhesion, and a cured product having a high elongation rate, it can be a protective panel in a large image display device. Can be suitably applied as a material for filling the space between the image display unit and the like.
Further, according to the method for manufacturing an image display device of the present invention, it is possible to reduce the stress applied to the image display unit, to have impact resistance, and to obtain a clear and high-contrast image having no double image. An image display device can be provided.

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 apparatus 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 apparatus of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, 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 addition, “(meth) acrylate” in the present specification means “acrylate” and “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” and its corresponding “methacryl”, and “(meth) acryloyl” means “acryloyl” and its corresponding “methacryloyl” (other synonyms). The same applies to.

[Liquid curable resin composition]
The liquid curable resin composition of the present invention (hereinafter also simply referred to as “resin composition”) has (A) silica particles having an average particle diameter of 1 nm to 1 μm, and (B) an ethylenically unsaturated bond in the molecule. A polymer, (C) a low molecular weight monomer having one ethylenically unsaturated group in the molecule, and (D) a polymerization initiator.
In the present invention, the “liquid curable resin composition” means a resin composition that is liquid at 25 ° C. and can be cured by radiation such as light or heat.
In the present invention, “polymer” means a compound having a weight average molecular weight of 1000 or more, and “low molecular weight monomer” means a compound having a weight average molecular weight of less than 1000.
In this specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted using a standard polystyrene calibration curve. Specifically, the weight average molecular weight is the same as the method described in the examples. Means the value measured based on.

Since the liquid curable resin composition of the present invention contains a specific component, when cured, the liquid curable resin composition is excellent in transparency and moist heat resistance, and has a low curing shrinkage rate, excellent adhesion, and high elongation rate. Can be a thing.
In particular, since the resin composition of the present invention contains silica particles having a specific average particle size as the component (A), the cured product has excellent adhesion when cured and has a high elongation rate. Etc. can be suppressed.
In addition, since it contains the component (B), the curing shrinkage rate can be particularly suppressed, and the warpage of the substrate that can occur when cured by light or heat can be suppressed. Can be suitably used to fill a space between the protective panel and the image display unit.
Furthermore, since it contains the component (C), the viscosity of the liquid curable resin composition can be adjusted to an appropriate range, and the space between the protective panel and the image display unit can be uniformly filled. it can.

  According to the knowledge of the present inventors, performance required for a film and a liquid curable resin composition as a material used for filling a space between the protective panel and the image display unit, etc. Is different. Therefore, it is difficult to apply the material in the film as it is to the liquid curable resin composition.

The resin composition of the present invention preferably contains substantially no organic solvent from the viewpoint of workability and suppression of voids (bubbles that can be generated in the curable resin composition).
As used herein, “substantially free of organic solvent” means that no organic solvent is intentionally added, and a trace amount of organic solvent is present as long as the characteristics of the present invention are not significantly deteriorated. Also good. Specifically, the content of the organic solvent may be 1000 ppm or less with respect to the total amount of the resin composition, preferably 500 ppm or less, more preferably 100 ppm or less, and still more preferably no organic solvent. Here, the “organic solvent” means an organic compound having no ethylenically unsaturated group in the molecule, being liquid at 25 ° C., and having a boiling point of 250 ° C. or less at atmospheric pressure.

In addition, the viscosity at 25 ° C. of the resin composition of the present invention is preferably 500 to 25000 mPa · s, more preferably 1000 to 21000 mPa · s, and further preferably 2000 to 15000 mPa · s, from the viewpoint of workability and suppression of voids. It is. If it is 500 mPa * s or more, generation | occurrence | production of a void can fully be suppressed. Moreover, if it is 25000 mPa * s or less, while workability | operativity is favorable, a resin composition can be made into a liquid state at 25 degreeC.
The viscosity at 25 ° C. is a value measured at 0.5 rpm using an E-type viscometer (product name “RE-80L”, manufactured by Toki Sangyo Co., Ltd.) using a 3 ° cone rotor. The value is based on the measurement method described in the example.

The resin composition of the present invention is excellent in viscosity stability, has the above viscosity range even when left for a long time, and has a small viscosity change. The resin composition of the present invention has a change in viscosity when left for 7 days in an environment of 25 ° C./55% RH (relative humidity) (the viscosity of the resin composition after being left and the viscosity of the resin composition before being left). The difference is preferably 100 mPa · s or less, more preferably 60 mPa · s or less, and still more preferably 40 mPa · s or less.
Hereinafter, each component will be described.

<(A) component: silica particles having an average particle diameter of 1 nm to 1 μm>
The component (A) is silica particles having an average particle diameter of 1 nm to 1 μm.
If the average particle size is less than 1 nm, the viscosity of the resin composition tends to be too high, which is not preferable. On the other hand, when the average particle size exceeds 1 μm, the transparency and elongation of the cured product are lowered, and the silica particles tend to settle over time, which is not preferable.
Although the average particle diameter of the silica particles is 1 nm to 1 μm, from the above viewpoint, it is preferably 5 nm to 0.8 μm, more preferably 10 nm to 0.6 μm, and from the viewpoint of further improving the elongation of the cured product, More preferably, they are 0.1 micrometer-0.6 micrometer, More preferably, they are 0.2 micrometer-0.6 micrometer.
In the present invention, the “average particle diameter” means the particle diameter (median diameter D ₅₀ ) at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

In the present invention, the silica particles are particles having a SiO ₂ content of usually 95% by mass or more, preferably 99% by mass or more, more preferably 99.9% by mass or more, and still more preferably 100% by mass. Means.
Examples of silica particles having an average particle diameter of 1 nm to 1 μm include “SO-E1”, “SO-E2”, “SO-E3”, “SO-C1”, “SO-C2”, and “SO-C3”. (Above, manufactured by Admatechs, all are trade names), “AEROSIL 150”, “AEROSIL 200”, “AEROSIL 300”, “AEROSIL 380”, “AEROSIL R972”, “AEROSIL R974”, “AEROSIL R812” (above , Manufactured by Nippon Aerosil Co., Ltd., all of which are trade names).

The content of the component (A) in the resin composition of the present invention is preferably relative to the total amount of all components in the resin composition from the viewpoints of curability and the curing shrinkage, adhesion, and elongation of the cured product. Is 1 to 40% by mass, more preferably 2 to 37% by mass, still more preferably 4 to 35% by mass, and more preferably 8 to 35% by mass from the viewpoint of improving the adhesion and elongation of the cured product. More preferably, it is 15 to 35% by mass.
If content of (A) is 1 mass% or more, the adhesiveness of hardened | cured material can be made favorable and elongation rate can be improved. Moreover, if it is 40 mass% or less, while sclerosis | hardenability will become favorable, the cure shrinkage rate of hardened | cured material can be reduced.

<(B) component: a polymer having an ethylenically unsaturated bond in the molecule>
The component (B) is a polymer having an ethylenically unsaturated bond in the molecule, and the polymer has a weight average molecular weight of 1,000 or more.
The weight average molecular weight of the component (B) is preferably 1,000 to 40,000, more preferably 3,000 to 30,000, still more preferably 5, from the viewpoints of curability, wet heat resistance and workability. 000 to 20,000, and more preferably 6,000 to 10,000.
When the weight average molecular weight is 1,000 or more, sufficient curability is obtained, and the wet heat resistance of the cured product is excellent. On the other hand, if it is 40,000 or less, the workability is also good.

Examples of the polymer having an ethylenically unsaturated bond in the molecule as the component (B) include a urethane polymer having a (meth) acryloyl group, a polyester oligomer having a (meth) acryloyl group, and polyethylene glycol mono (meth). Examples include acrylate, polyethylene glycol di (meth) acrylate, polyprolene glycol mono (meth) acrylate, and polyprolene glycol di (meth) acrylate.
Among these, a urethane polymer having a (meth) acryloyl group is preferable from the viewpoint of toughness and adhesiveness of a cured product of the resin composition.

  The urethane polymer having the (meth) acryloyl group is, for example, a compound obtained by reacting (b1) a diol compound and (b2) a compound having an isocyanate group (hereinafter also referred to as “urethane polymer”), And (b3) monohydroxy (meth) acrylate, or (b4) a monocarboxylic acid having a (meth) acryloyl group or a monoisocyanate compound having a (meth) acryloyl group.

(B1) Examples of the diol compound include polyether diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyolefin diols such as polybutadiene diol, polyisoprene diol, hydrogenated polybutadiene diol, and hydrogenated polyisoprene diol; polyester diol , Polycaprolactone diol, silicone diol, diethylene glycol and the like.
Among these, polyether diol is preferable from the viewpoints of stress and impact relaxation, transparency, adhesiveness, and compatibility with other components.

  (B2) Examples of the compound having an isocyanate group include a diisocyanate compound represented by the following general formula (2). In addition, as a (b2) component, you may use together the polyisocyanate compound more than trifunctional with the diisocyanate compound represented by following General formula (2).

(In formula (2), X represents a divalent organic group.)

Examples of the divalent organic group represented by X in the general formula (2) include an aliphatic group having 1 to 20 carbon atoms, an alicyclic group having 5 to 20 carbon atoms, unsubstituted or 1 to 1 carbon atoms. And arylene groups such as a phenylene group or a naphthylene group which may be substituted with 5 lower alkyl groups.
Among these, from the viewpoint of further improving transparency, an aliphatic group having 1 to 20 carbon atoms or an alicyclic group having 5 to 20 carbon atoms is preferable, and an alicyclic group having 5 to 20 carbon atoms is more preferable.
In addition, as said C1-C20 aliphatic group, it is preferable that it is a C1-C20 aliphatic hydrocarbon group.

  Examples of the diisocyanate compound represented by the general formula (2) include diphenylmethane-2,4′-diisocyanate; 3,2′-, 3,3′-, 4,2′-, 4,3′-, 5,2'-, 5,3'-, 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate; 3,2'-, 3,3'-, 4,2'- 4,3'-, 5,2'-, 5,3'-, 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate; 3,2'-, 3,3 ' -, 4,2'-, 4,3'-, 5,2'-, 5,3'-, 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate; diphenylmethane-4 , 4′-diisocyanate; diphenylmethane-3,3′-diisocyanate; diphenyl such as diphenylmethane-3,4′-diisocyanate Diphenyl ether-4,4′-diisocyanate; benzophenone-4,4′-diisocyanate; diphenylsulfone-4,4′-diisocyanate; tolylene-2,4-diisocyanate; tolylene-2 , 6-diisocyanate; m-xylylene diisocyanate; p-xylylene diisocyanate; 1,5-naphthalene diisocyanate; 4,4 '-[2,2bis (4-phenoxyphenyl) propane] diisocyanate; aroma such as tolylene diisocyanate Hexamethylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; isophorone diisocyanate; 4,4'- Cyclohexyl diisocyanate; trans-cyclohexane-1,4-diisocyanate; hydrogenated m- xylylene diisocyanate, aliphatic or alicyclic diisocyanates such as lysine diisocyanate.

Among these, from the viewpoint of further improving transparency, X in the general formula (2) is an aliphatic group having an aliphatic group having 1 to 20 carbon atoms or an alicyclic group having 5 to 20 carbon atoms. Or an alicyclic diisocyanate compound is preferable.
In addition, these diisocyanate compounds can be used individually or in combination of 2 or more types.

Moreover, it is preferable to use what was stabilized with the blocking agent from a viewpoint of avoiding a secular change for the diisocyanate compound represented by the said General formula (2).
The blocking agent is not particularly limited, and examples thereof include alcohols such as hydroxy acrylate and butanol, phenol, and oxime.

  The blending ratio when the component (b1) and the component (b2) are reacted is appropriately adjusted depending on whether the number average molecular weight of the urethane polymer to be generated and the terminal of the urethane polymer to be generated are a hydroxyl group or an isocyanate group. Is done.

  When the end of the urethane polymer is an isocyanate group, the ratio of the number of isocyanate groups to the number of hydroxyl groups [number of isocyanate groups / number of hydroxyl groups] is preferably adjusted to be 1.01 or more, and the viewpoint of increasing the number average molecular weight Is preferably adjusted to less than 2. By setting such a ratio, a urethane polymer whose terminal is an isocyanate group can be obtained.

  When the end of the urethane polymer is an isocyanate group, (b3) a compound capable of reacting with an isocyanate group such as a monohydroxy (meth) acrylate compound is used as a compound for introducing the (meth) acryloyl skeleton. Can do.

  (B3) Examples of the monohydroxy (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 1,4-cyclohexanedimethanol mono (Meth) acrylate, caprolactone or alkylene oxide adduct of each of the above (meth) acrylates, glycerin di (meth) acrylate, trimethylol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate , Ditrimethylolpropane tri (meth) acrylate, and 2-acryloxyethanol. These compounds can be used alone or in combination of two or more.

  On the other hand, when the terminal of the urethane polymer is a hydroxyl group, the blending ratio is preferably adjusted so that the ratio of the number of hydroxyl groups to the number of isocyanate groups (number of hydroxyl groups / isocyanate groups) is 1.01 or more. It is preferable to adjust to less than 2 from the viewpoint of increasing.

  When the terminal of the urethane polymer is a hydroxyl group, (b4) a monocarboxylic acid having a (meth) acryloyl group or a monoisocyanate having a (meth) acryloyl group as a compound for introducing a (meth) acryloyl skeleton A compound capable of reacting with a hydroxyl group such as a compound can be used.

Examples of the monocarboxylic acid having a (meth) acryloyl group include (meth) acrylic acid.
Moreover, as a monoisocyanate compound which has a (meth) acryloyl group, 2-isocyanate ethyl (meth) acrylate etc. are mentioned, for example.

In addition, the urethane polymer which has a (meth) acryloyl group can also be manufactured by methods other than the above. As other methods for producing a urethane polymer having a (meth) acryloyl group, for example, (b1) a diol compound and (b3) monohydroxy (meth) acrylate are mixed in a predetermined amount, and the temperature is raised to a predetermined temperature. After that, (b2) a predetermined amount of the compound having an isocyanate group is added to the mixture of the component (b1) and the component (b3) over a predetermined time and allowed to react.
In addition, (B) a polymer having an ethylenically unsaturated bond in the molecule is obtained by using a known method using the above-described components, for example, the presence of a polymerization inhibitor such as p-methoxyphenol and a catalyst such as dibutyltin dilaurate. It can manufacture by the method of making the above-mentioned component react under.

The average number of functional groups in the component (B) is preferably 0.3 to 2.0, more preferably 0.4 to 1.5, more preferably from the viewpoint of adjusting the viscosity of the resin composition and further reducing the curing shrinkage rate. Preferably, it is 0.5 to 1.0, and preferably from 0.3 to 2.0, more preferably from 0.4 to 1.5, still more preferably from the viewpoint of improving the adhesion and elongation of the cured product. It is 0.5-1.0, More preferably, it is 0.6-1.0.
Here, the “number of functional groups” indicates the number of functional groups ((meth) acryloyl groups) in one molecule of the component (B), and the “average number of functional groups” indicates the functionality per molecule in the entire component (B). The average value of the radix is shown. The average number of functional groups can be calculated from the number of moles of each component when the component (B) is synthesized. In addition, the average number of functional groups can be calculated from the integrated value of ¹ H-NMR of the component (B).

When the average number of functional groups is less than 1.0, the resin composition has an ethylenically unsaturated bond in the molecule together with a polymer having an ethylenically unsaturated bond in the molecule as component (B). Except not, the polymer which has the same structure as (B) component is also contained. The polymer plays a role as a plasticizer in the resin composition, and adjusts the viscosity of the resin composition to an appropriate range.
Here, in the present invention, when a polymer having no ethylenically unsaturated bond is also produced during the synthesis of a polymer having an ethylenically unsaturated bond, the polymer having an ethylenically unsaturated bond and the ethylenically unsaturated bond A mixture of polymers having no bond is also used as component (B).

The content of the component (B) in the resin composition of the present invention is preferably 30 to 92% by mass with respect to the total amount of all components in the resin composition, from the viewpoints of curability, adhesion, and cure shrinkage. More preferably, it is 40-88 mass%, More preferably, it is 50-85 mass%.
When the content of the component (B) is 30% by mass or more, the curability becomes good and the curing shrinkage of the cured product can be kept low. Moreover, if it is 92 mass% or less, content of other components other than (B) can fully be ensured, and the adhesiveness etc. of hardened | cured material can be improved.

<(C) component: low molecular weight monomer having one ethylenically unsaturated group in the molecule>
The component (C) is a low molecular weight monomer having one ethylenically unsaturated group in the molecule, and the weight average molecular weight of the low molecular weight monomer is less than 1,000.
The weight average molecular weight of (C) component becomes like this. Preferably it is 80-1000, More preferably, it is 100-800, More preferably, it is 120-700.

  The low molecular weight monomer having one ethylenically unsaturated group in the molecule as the component (C) is preferably liquid at room temperature (25 ° C.) and is represented by the following general formula (3). Alkyl (meth) acrylate (hereinafter also referred to as “(C1) component”) and a compound having a (meth) acryl group and a hydroxyl group or an ether bond in the molecule (hereinafter also referred to as “(C2) component”). Is more preferable.

In the general formula (3), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 4 to 20 carbon atoms. R ² is preferably an alkyl group having 6 to 18 carbon atoms, more preferably an alkyl group having 8 to 16 carbon atoms, from the viewpoint of imparting more flexibility.

((C1) component)
Examples of the alkyl (meth) acrylate represented by the general formula (3) include n-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, and n-pentyl (meth) acrylate. , N-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-hexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (Meth) acrylate etc. are mentioned. These compounds can be used alone or in combination of two or more.

((C2) component)
Examples of the compound having a (meth) acryl group and a hydroxyl group or an ether bond in the molecule include 2-hydroxyethyl (meth) acrylate, 1-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Hydroxypropyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-hydroxybutyl (meth) Hydroxyl-containing (meth) acrylates such as acrylate; Hydroxyl-containing (meth) acrylamides such as hydroxyethyl (meth) acrylamide; Polyethylene glycol mono (meth) acrylates such as diethylene glycol and triethylene glycol Polypropylene glycol mono (meth) acrylates such as dipropylene glycol and tripropylene glycol; Polybutylene glycol mono (meth) acrylates such as dibutylene glycol and tributylene glycol; Morpholine group-containing (meth) acrylates such as acryloylmorpholine Can be mentioned.
Among these, from the viewpoint of wet heat reliability and workability during coating, a hydroxyl group-containing (meth) acrylate and a morpholine group-containing (meth) acrylate are preferable, and 4-hydroxybutyl acrylate and acryloylmorpholine are more preferable.
These compounds may be used alone or in combination of two or more.

The content of the component (C) in the resin composition of the present invention is preferably 3 to 25% by mass, more preferably 5 to 23% by mass, and still more preferably 8%, based on the total amount of all components in the resin composition. It is -20 mass%, More preferably, it is 10-18 mass%.
When the content of the component (C) is 3% by mass or more, the resin composition can have an appropriate viscosity, workability during coating can be improved, and the curing shrinkage rate can be lowered. can do. Moreover, if it is 25 mass% or less, a cure shrinkage rate will not become high.

  When the component (C1) and the component (C2) are used in combination as the component (C), the content ratio of the component (C1) is the total amount of the component (C) from the viewpoint of reducing the transparency of the cured product and the deformation of the cured product. Among them, the content is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, and still more preferably 70 to 85% by mass. Moreover, the content ratio of the component (C2) in that case is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and further preferably 15 to 30% in the total amount of the component (C) from the same viewpoint. % By mass.

<(D) component: Polymerization initiator>
As (D) polymerization initiator used in the present invention, either (D1) photopolymerization initiator or (D2) thermal polymerization initiator can be used, and these may be used in combination.

  In the present invention, as the photopolymerization initiator (D1), for example, known photopolymerization initiators such as benzophenone series, anthraquinone series, benzoin series, sulfonium salts, diazonium salts and onium salts can be used. These are particularly sensitive to ultraviolet rays.

  (D1) Specific examples of the photopolymerization initiator include benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N-tetraethyl-4,4′-diaminobenzophenone, 4- Methoxy-4′-dimethylaminobenzophenone, α-hydroxyisobutylphenone, 2-ethylanthraquinone, t-butylanthraquinone, 1,4-dimethylanthraquinone, 1-chloroanthraquinone, 2,3-dichloroanthraquinone, 3-chloro-2- Methyl anthraquinone, 1,2-benzoanthraquinone, 2-phenylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy- 1, 2 Aromatic ketone compounds such as diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin compounds such as benzoin, methylbenzoin and ethylbenzoin, benzoin methyl ether, benzoin ethyl ether, Benzoin ether compounds such as benzoin isobutyl ether and benzoin phenyl ether, benzyl, 2,2-diethoxyacetophenone, benzyldimethyl ketal, ester compounds of β- (acridin-9-yl) acrylic acid, 9-phenylacridine, 9-pyridyl Acridine, acridine compounds such as 1,7-diacridinoheptane, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxy) Phenyl ) Imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxy) Phenyl) -4,5-diphenylimidazole dimer, 2,4-di (p-methoxyphenyl) 5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer 2,4,5-triarylimidazole dimers such as 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole dimer, 2-benzyl-2-dimethylamino-1- (4 -Morpholinophenyl) -1-butanone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propane, bis (2,4,6-to Methylbenzoyl) - phenyl phosphine oxide, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), and the like.

  In particular, photopolymerization initiators that improve transparency without coloring the curable resin composition include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one. , Α-hydroxyalkylenone compounds such as 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, bis (2,4,6- Acylphosphine such as trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide Oxide compounds, oligo (2-hydroxy-2-methyl-1- (4- (1-methylbi ) Phenyl) propanone) and a combination thereof are preferred.

Moreover, as a photoinitiator for producing a thick film, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl Acylphosphine oxide compounds such as -pentylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide are preferred.
These (D1) photopolymerization initiators may be used alone or in combination of two or more.

(D2) The thermal polymerization initiator is an initiator that generates radicals by heat.
(D2) Specific examples of the thermal polymerization initiator include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxy Ethyl) peroxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, t-hexylperoxypivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionylperoxide Organic peroxides such as lauroyl peroxide and diacetyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis ( Cyclohexane-1-carbonyl), 2,2′-azobis (2,4-dimethylva Relonitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate), 4,4′-azobis (4-cyanovale) Rick acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and the like.
These (D2) thermal polymerization initiators may be used alone or in combination of two or more.

The content of the polymerization initiator (D) in the resin composition of the present invention is preferably 0.01 to 5% by mass, more preferably 0.02 to 3% by mass, based on the total amount of all components in the resin composition. %, And more preferably 0.03 to 2% by mass.
In addition, when using (D1) photoinitiator as (D) component, Preferably content of (D1) photoinitiator is 0.1 with respect to the total amount of all the components in a resin composition. -5 mass%, more preferably 0.2-3 mass%, still more preferably 0.3-2 mass%.
On the other hand, when (D2) thermal polymerization initiator is used as component (D), the content of (D2) thermal polymerization initiator is preferably 0.01 relative to the total amount of all components in the resin composition. ˜1% by mass.
In addition, when using together (D1) photoinitiator and (D2) thermal polymerization initiator, it is preferable to use in said range, respectively.

[Curing reaction of liquid curable resin composition]
The curing reaction can be performed by a curing reaction by irradiation with active energy rays, a curing reaction by heat, or a combination thereof. Active energy rays refer to ultraviolet rays, electron beams, α rays, β rays, γ rays and the like. These methods can also be used for the synthesis of the (B) acrylic polymer.

  In the case of curing by applying or casting a curable resin composition, it may be difficult to heat because the high temperature resistance of the deflecting plate used in the liquid crystal panel is low. In this case, it is preferable to use a photopolymerization initiator (D1) that can be polymerized by light.

The curing shrinkage rate when the resin composition of the present invention is cured is preferably less than 1.8% from the viewpoint of further suppressing the warpage of a substrate such as a protective panel or an image display unit.
If the curing shrinkage rate is less than 1.8%, warpage that may occur in the image display unit can be sufficiently suppressed, and occurrence of problems such as color unevenness when used in an image display device can be prevented. it can.
In addition, the value of the cure shrinkage rate of the said hardened | cured material means the value measured by the method as described in an Example.

The light transmittance at a wavelength of 400 nm at a film thickness of 175 μm of the cured product of the resin composition of the present invention is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more.
The haze of the cured product is preferably 1.0% or less, more preferably 0.7% or less, and still more preferably 0.4% or less.
In addition, the value of the light transmittance and haze of the said hardened | cured material means the value measured by the method as described in an Example.

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

  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.

  According to the liquid crystal display device shown in FIGS. 1 and 2, since the cured product of the curable resin composition of the present invention is provided as the transparent resin layer 31 or 32, it has impact resistance, has no double image, and is clear and has a contrast. High image quality can be obtained.

  The liquid crystal display cell 10 can be made of a liquid crystal material well known in the art. Further, according to the control method of the liquid crystal material, it is classified into a TN (Twisted Nematic) method, a STN (Super-twisted nematic) method, a VA (Virtual Alignment) method, an IPS (In-Place-Switching) method, etc. Then, it may be a liquid crystal display cell using any control method.

As the polarizing plates 20 and 22, a polarizing plate common in this technical field can be used.
The surfaces of these polarizing plates 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 invention is effective for thick films, and can be suitably used when the transparent resin layer 31 or 32 of 0.1 mm or more is formed.

As the transparent protective substrate 40, a general optical transparent substrate can be used. Examples of the transparent 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. 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 surface treatment such as antireflection, antifouling, and hard coat. This surface treatment may be performed on only one side or both sides of the transparent protective substrate. Further, the transparent protective substrate can be used in combination of a plurality of substrates.

  The configuration of the backlight system 50 is not limited, but generally includes a reflecting means such as a reflector and an illuminating means such as a lamp. As these reflecting means and illuminating means, known means used in ordinary image display devices can be applied.

[Method for Manufacturing Image Display Device]
The image display apparatus as shown in FIGS. 1 and 2 using the liquid curable resin composition of the present invention can be manufactured, for example, 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 invention between the image display unit and the protection panel. Through a step (hereinafter also referred to as “step (1a)”) and a step of irradiating light from the protective panel side to cure the liquid curable resin composition (hereinafter also referred to as “step (2a)”), Can be manufactured.

  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. Between the step of interposing the liquid curable resin composition of the present invention (hereinafter also referred to as “step (1b)”) and the step of curing the liquid curable resin composition by irradiating light from the protective panel side ( Hereinafter, it can also be manufactured through step (2b)).

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

Light irradiation in the step (2a) and (2b), for example, using an ultraviolet irradiation device can be carried out under the conditions of exposure ^{500mJ / cm 2 ~5000mJ / cm 2} . The exposure amount refers to a value obtained by multiplying the illuminance measured by an ultraviolet illuminance meter “product name“ UV-M02 ”(receiver: UV-36), manufactured by Oak Co., Ltd.) and 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 steps (2a) and (2b), when light is irradiated, irradiation from the protective panel 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 resin composition simultaneously with light irradiation.

As described above, the liquid crystal display device which is one of the image display devices that can be manufactured by using the liquid curable resin composition of the present invention has been described. However, the liquid curable resin composition of the present invention is described. The image display device that can be manufactured by using 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 apparatus is 10 inches or larger, it is more preferable to produce a transparent resin layer using the liquid curable resin composition of the present invention.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.
Examples of preparing a resin composition that can be used in an image display device to which the present invention is applied will be described below. In the following examples, the weight average molecular weight is a value measured based on the following method.

(Weight average molecular weight)
The determination was performed using gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and polystyrene was used as a standard substance. Hereinafter, GPC conditions are shown.
・ Pump: Hitachi L-6000 type (manufactured by Hitachi, Ltd.)
Detector: Hitachi L-3300 RI (manufactured by Hitachi, Ltd.)
Column: Gelpack GL-R420 + Gelpack GL-R430 + Gelpack GL-R440 (3 in total) (trade name, manufactured by Hitachi Chemical Co., Ltd.)
・ Eluent: THF
・ Measurement temperature: 25 ℃

[Production Example 1]
(Synthesis of polyurethane acrylate 1)
In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 520.8 g (0.613 mol) of polytetramethylene glycol (molecular weight 850) and 1.06 g of diethylene glycol (0) as the component (b1). 0.01 mol), 275.2 g (0.8 mol) of caprolactone 2-mol adduct of 2-hydroxyethyl acrylate (trade name “Placcel FA2D”, manufactured by Daicel Chemical Industries, Ltd.) as the component (b3), p as a polymerization inhibitor -0.5 g of methoxyphenol and 0.3 g of dibutyltin dilaurate as a catalyst were added. After raising the temperature to 70 ° C. while flowing air into the reaction vessel, 222 g (1 mol) of isophorone diisocyanate as the component (b2) was uniformly dropped over 2 hours while stirring at 70 to 75 ° C. to carry out the reaction.
After the completion of the dropping, the reaction was completed for 5 hours, and the reaction was terminated after confirming that the isocyanate had disappeared by IR (infrared absorption analysis) measurement (device name: JIR-6500, manufactured by JEOL Ltd.). Polyurethane acrylate 1 (weight average molecular weight 7,000, average functional group number = 2 (calculated value)) having glycol and isophorone diisocyanate as repeating units and having an ethylenically unsaturated bond was obtained.

[Production Example 2]
(Synthesis of polyurethane acrylate 2)
In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 520.8 g (0.613 mol) of polytetramethylene glycol (molecular weight 850) and 1.06 g of diethylene glycol (0) as the component (b1). 0.01 mol), 137.6 g (0.4 mol) of 2-hydroxyethyl acrylate caprolactone 2-mol adduct (manufactured by Daicel Chemical Industries, Ltd., trade name “Placcel FA2D”) as the component (b3), butanol 34 as the blocking agent 0.9 g (0.47 mol), 0.5 g of p-methoxyphenol as a polymerization inhibitor, and 0.3 g of dibutyltin dilaurate as a catalyst were added. The temperature was raised to 70 ° C. while flowing air into the reaction vessel, and while stirring at 70 to 75 ° C., 222 g (1 mol) of isophorone diisocyanate was uniformly added dropwise over 2 hours as the component (b2) to carry out the reaction.
After the completion of the dropping, the reaction was completed for 5 hours, and the reaction was terminated after confirming that the isocyanate had disappeared by IR (infrared absorption analysis) measurement (device name: JIR-6500, manufactured by JEOL Ltd.). A polyurethane acrylate 2 having a glycol and isophorone diisocyanate as repeating units and having an ethylenically unsaturated bond (weight average molecular weight 7,000, average functional group number = 1 (calculated value)) was obtained.

[Production Example 3]
(Synthesis of polyurethane acrylate 3)
In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 520.8 g (0.613 mol) of polytetramethylene glycol (molecular weight 850) and 1.06 g of diethylene glycol (0) as the component (b1). 0.01 mol), 137.6 g (0.4 mol) of 2-hydroxyethyl acrylate caprolactone 2-mol adduct (manufactured by Daicel Chemical Industries, Ltd., trade name “Placcel FA2D”) as the component (b3), butanol 34 as the blocking agent 0.9 g (0.47 mol), 0.5 g of p-methoxyphenol as a polymerization inhibitor, and 0.3 g of dibutyltin dilaurate as a catalyst were added. While raising the temperature to 70 ° C. while flowing air into the reaction vessel, stirring at 70 to 75 ° C., TMDI (2,2,4-trimethylhexamethylene diisocyanate and 2,4,4-trimethyl as the component (b2) was stirred. 209.8 g (1 mol) of a mixture of hexamethylene diisocyanate, mixing ratio 4: 6 (mass ratio)) was uniformly added dropwise over 2 hours to carry out the reaction.
After the completion of the dropping, the reaction was completed for 5 hours, and the reaction was terminated after confirming that the isocyanate had disappeared by IR (infrared absorption analysis) measurement (device name: JIR-6500, manufactured by JEOL Ltd.). A polyurethane acrylate 3 having a glycol and TMDI as a repeating unit and having an ethylenically unsaturated bond (weight average molecular weight 7,000, average number of functional groups = 1 (calculated value)) was obtained.

[Production Example 4]
(Synthesis of polyurethane acrylate 4)
In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 520.8 g (0.613 mol) of polytetramethylene glycol (molecular weight 850) and 1.06 g of diethylene glycol (0) as the component (b1). .01 mol), 68.8 g (0.2 mol) of 2-hydroxyethyl acrylate caprolactone 2-mol adduct (trade name “Placcel FA2D”, manufactured by Daicel Chemical Industries, Ltd.) as the component (b3), and butanol 52 as the blocking agent 0.3 g (0.71 mol), 0.5 g of p-methoxyphenol as a polymerization inhibitor, and 0.3 g of dibutyltin dilaurate as a catalyst were added. The temperature was raised to 70 ° C. while flowing air into the reaction vessel, and then stirred at 70 to 75 ° C., and as the component (b2), TMDI (2,2,4-trimethylhexamethylene diisocyanate and 2,4,4- A mixture of trimethylhexamethylene diisocyanate, mixing ratio 4: 6 (mass ratio)) 209.8 g (1 mol) was uniformly added dropwise over 2 hours to carry out the reaction.
After the completion of the dropping, the reaction was completed for 5 hours, and the reaction was terminated after confirming that the isocyanate had disappeared by IR (infrared absorption analysis) measurement (device name: JIR-6500, manufactured by JEOL Ltd.). Polyurethane acrylate 4 having a glycol and TMDI as repeating units and having an ethylenically unsaturated bond (weight average molecular weight 7,000, average number of functional groups = 0.5 (calculated value)) was obtained.

[Examples 1-11, Comparative Examples 1-4]
The liquid curable resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 were prepared by blending the components (A) to (D) at the blending ratios shown in Tables 1 and 2 and stirring and mixing them. In addition, the unit of the numerical value about (A)-(D) component in Table 1, 2 is a mass part.

“Polyurethane acrylates 1 to 4” used as the component (B) in Tables 1 and 2 are polyurethane acrylates synthesized by the methods described in Production Examples 1 to 4, respectively.
Further, “AEROSIL R972”, “AEROSIL 200”, “SO-E1”, and “SO-E2” used as the component (A) are silica particles shown below.
AEROSIL R972: Product name manufactured by Nippon Aerosil Co., Ltd. Silica particles having an average particle size of 16 nm.
-AEROSIL 200: Nippon Aerosil Co., Ltd. product name. Silica particles having an average particle size of 12 nm.
-SO-E1: Product name manufactured by Admatechs. Silica particles having an average particle size of 0.25 μm.
-SO-E2: Product name, manufactured by Admatechs. Silica particles having an average particle size of 0.5 μm.

  About the prepared liquid curable resin composition, the test shown below was done. The results are shown in Tables 1 and 2.

(Viscosity stability)
About the liquid curable resin composition, the difference in viscosity at 25 ° C. was measured immediately after adjustment and after standing for 7 days in an environment of 25 ° C./55% RH (relative humidity). The viscosity at 25 ° C. was measured using an E-type viscometer (manufactured by Toki Sangyo, product name “RE-80L”).

(Light transmittance, haze)
On the surface of the release-treated polyethylene terephthalate film (hereinafter referred to as “PET film”) (manufactured by Fujimori Kogyo Co., Ltd.) having a film thickness of 50 μm, the film thickness after curing is 175 μm. The liquid curable resin compositions of Examples 1 to 10 and Comparative Examples 1 to 7 were applied to form a coating film, and the PET film having the same film thickness of 50 μm as described above was subjected to a release treatment and the coating film. And pasted together. Then, an ultraviolet ray irradiation device (product name: ELM-3000B-6N, manufactured by Oak Co., Ltd.) is used to irradiate ultraviolet rays at 2,000 mJ / cm ² to cure the coating film of the curable resin composition, thereby producing a cured product. did.
Thereafter, the two PET films were peeled off, and the light transmittance at a wavelength of 400 nm of the cured product having a film thickness of 175 μm was measured using a spectrophotometer (manufactured by Shimadzu Corporation, product name “UV-2400PC”).
Moreover, the haze of this hardened | cured material was measured using the haze meter (The product name "HGM-2" by Suga Test Instruments Co., Ltd.).

(Moisture and heat resistance reliability)
Each liquid curable resin composition of Examples 1-10 and Comparative Examples 1-7 was bonded to the same glass substrate and the coating film on a 4-inch glass substrate through a 175 μm spacer. And the ultraviolet-ray was irradiated by 2000 mJ / cm < ² > using the ultraviolet irradiation apparatus (product name: ELM-3000B-6N, the Oak company make), the coating film was hardened, and the test piece with a film thickness of 175 micrometers was obtained. This test piece was put into a test bath of 85 ° C./85% RH (relative humidity) for 50 hours, peeled off, and the presence or absence of bubble generation was visually observed and evaluated according to the following criteria.
A: No change visually.
B: It peeled off visually and the bubble was confirmed.

(Curing shrinkage)
The specific gravity of the cured product (resin composition after curing) having the same film thickness of 175 μm as that used in the above measurement of light transmittance and haze and the resin composition before curing was measured with an electronic hydrometer (Alpha Mirage Co., Ltd.) Manufactured, product name “SD-200L”), the cure shrinkage rate was calculated from the following formula, and evaluated according to the following criteria.
Curing shrinkage (%) = {(specific gravity of cured product−specific gravity of resin composition before curing) / specific gravity of cured product} × 100
A: Less than 1.8% B: 1.8% or more

(Adhesion)
Test samples were prepared by the following procedures (1) to (3).
(1): A 7 cm × 13.5 cm frame was formed on a glass substrate (soda lime glass) using a double-sided tape having a thickness of 180 μm (manufactured by 3M, product name “ScotchTM666”).
(2): The liquid curable resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 are dropped into the frame formed in (1) above, so that the polyethylene terephthalate (PET) film is covered with the frame. Covered.
(3): The liquid curable resin composition in the frame is irradiated with 2,000 mJ / cm ^{2 of} ultraviolet rays from above the PET film using an ultraviolet irradiation device (product name: ELM-3000B-6N, manufactured by Oak Co.). Was cured to obtain a cured product, and then the PET film and the cured product were cut at intervals of 15 mm so that the width was 25 mm and the length was 7 cm to obtain a test sample.
Using a precision universal testing machine (manufactured by Shimadzu Corporation, product name “AUTOGRAPH AGS-1000G”), the PET film adhered to the cured product of the produced test sample was pulled at a speed of 300 mm / min, 180 ° C. Based on JIS K6854-2, the adhesive strength (unit: N / 25 mm) between the PET film and the cured product was measured with a peel.

(Growth rate)
Test samples were prepared by the following procedures (1) to (3).
(1): On the KX-4 film, three double-sided tapes (manufactured by 3M, product name “ScotchTM666”) having a thickness of 180 μm were stacked to form a 2 cm × 8 cm frame.
(2): The liquid curable resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 were dropped into the frame formed in (1) above, and the BD film was covered so that the inside of the frame was covered.
(3): The liquid curable resin composition in the frame is irradiated with 2,000 mJ / cm ^{2 of} ultraviolet rays from above the BD film using an ultraviolet irradiation device (product name: ELM-3000B-6N, manufactured by Oak Co.). Was cured to obtain a cured product, and then the BD film and the cured product were cut into a width of 10 mm and a length of 7 cm to obtain a test sample.
The produced BD film of the test sample is peeled off to obtain only a cured product, and the cured product is sandwiched between plastic plates so that the distance between chucks is 25 mm. A precision universal testing machine (manufactured by Shimadzu Corporation, product name “AUTOGRAPH”) AGS-1000G ") was used to measure the elongation (%) under the condition of a pulling speed of 1 mm / min.

  From Table 1, the hardened | cured material of the liquid curable resin composition of Examples 1-11 is excellent in transparency and moist-and-heat-reliability, has a low cure shrinkage rate, is excellent in adhesion, and has a high elongation rate. On the other hand, the liquid curable resin compositions of Comparative Examples 1 to 4 resulted in inferior adhesion and elongation of the cured product as compared to the present example.

  The liquid curable resin composition of the present invention is excellent in transparency and moist heat resistance when cured, and has a low cure shrinkage, excellent adhesion, and high elongation. Therefore, it can be suitably applied as a material for filling the space between the protective panel and the image display unit in the large image 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 Transparent protective substrate (protective panel)
50 Backlight system

Claims (7)

(A) silica particles having an average particle diameter of 1 nm to 1 μm,
(B) a urethane polymer having a (meth) acryloyl group,
(C) a low molecular weight monomer having one ethylenically unsaturated group in the molecule, and (D) a polymerization initiator,
Comprises, (A) content of the component Ri 8 to 40% by mass, (C) component, alkyl (meth) acrylate represented by the following general formula (3), (meth) acrylic groups in the molecule And a liquid curable resin composition containing at least one selected from a compound having a hydroxyl group and a morpholine group-containing (meth) acrylate .

(In the general formula (3), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 6 to 18 carbon atoms.)   In the liquid curable resin composition, the content of the component (A) is 8 to 40% by mass, the content of the component (B) is 30 to 88% by mass, and the content of the component (C) is 3 to 25% by mass. And the liquid curable resin composition of Claim 1 whose content of (D) component is 0.01-5 mass%. The liquid curable resin composition of Claim 1 or 2 whose average functional group number in (B) component is 0.3-2.0. The liquid curable resin composition according to any one of claims 1 to 3, which contains substantially no organic solvent and has a viscosity at 25 ° C of 500 to 25000 mPa · s. The image display apparatus provided with the hardened | cured material of the liquid curable resin composition as described in any one of Claims 1-4 as a transparent resin layer. An image display device comprising: an image display unit; and a protection panel,
A step of interposing the liquid curable resin composition according to any one of claims 1 to 4 between the image display unit and the protective panel;
And a step of curing the liquid curable resin composition by irradiating light from the protective panel side. A method for manufacturing an image display device comprising an image display unit, a touch panel, and a protection panel,
A step of interposing the liquid curable resin composition according to any one of claims 1 to 4 between the image display unit and the touch panel and / or between the touch panel and the protective panel. ,
And a step of curing the liquid curable resin composition by irradiating light from the protective panel side.