JP2016169335A - Curable composition, cured article, laminate and picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable composition suitable for forming an adhesive layer adhering face bars each other, being transparent, small in elasticity after curing and less in deterioration by ultraviolet.SOLUTION: A curable composition containing a non-curable component (D) of 1 to 90 pts.mass based on 100 pts.mass of a curable compound (Z)and further a photoinitiator, an antioxidant and an ultraviolet absorber, where the photoinitiator contains an acylphosphine oxide-based photoinitiator, the antioxidant is one or more kind selected from a group consisting of a phenolic antioxidant, a phosphorus-based antioxidant and an antioxidant having a thioether skeleton and the ultraviolet absorber contains a benzotriazole ultraviolet. The curable compound (Z) has an addition polymerizable unsaturated group, urethane acrylate synthesized by using polyoxy alkylene polyol and polyisocyanate as raw materials (A) and a monomer having the addition polymerizable unsaturated group and a hydroxyl group (B).SELECTED DRAWING: None

Description

  The present invention relates to a curable composition, a cured product of the curable composition, a laminate including the cured product, and an image display device.

  For example, as a curable composition suitable for forming an adhesive layer when a transparent surface material such as a cover glass is attached to the display surface of a liquid crystal display device via an adhesive layer, the present applicant has already made urethane acrylate and A curable composition containing a monomer having a curable group and a hydroxyl group, a photopolymerization initiator, and a non-curable component has been developed and patent application has been filed (Patent Document 1).

International Publication No. 2011/158840

In recent years, as display devices such as liquid crystal display devices have become thinner and lighter, for example, the display surface of a display device is directly attached to the indoor side surface of a window glass installed facing the outside. A new installation method has been proposed.
Since the display device installed in this way visually recognizes the display surface through the window glass and the adhesive layer from the outside, the adhesive layer is transparent, and display quality such as display unevenness is deteriorated. In addition to not occurring, it is also required that there is little deterioration due to ultraviolet rays.

The curable composition described in Patent Document 1 has a cured product that is transparent and has a low elastic modulus after curing, and thus can prevent deterioration in display quality. The specifications have not yet been studied.
The present invention is suitable for forming a pressure-sensitive adhesive layer for attaching face materials to each other, is transparent, has a low elastic modulus after curing, and has little deterioration due to ultraviolet rays, and a cured product of the curable composition. An object of the present invention is to provide a laminate and an image display device provided with the cured product.

  The present inventors conducted an accelerated test of irradiating ultraviolet rays for a long time on the adhesive layer made of a cured product of the curable composition described in Patent Document 1, and if no ultraviolet absorber was added, the adhesive layer It has been found that there is a case in which liquid dripping that softens and deforms and yellowing in which the periphery of the cured product turns yellow. In addition, an attempt was made to add an ultraviolet absorber, but it was also found that the effect varies greatly depending on the ultraviolet absorber. As a result of extensive research, the inventors have found that liquid dripping and yellowing due to ultraviolet irradiation can be satisfactorily suppressed by adding specific ultraviolet absorbers and antioxidants, and the present invention has been achieved.

The present invention includes the following [1] to [12].
[1] 100 parts by mass of the following curable compound (Z) contains 1 to 90 parts by mass of the following non-curable component (D), and further contains a photopolymerization initiator, an antioxidant, and an ultraviolet absorber. The photoinitiator comprises an acylphosphine oxide photoinitiator, and the antioxidant comprises a phenolic antioxidant, a phosphorus antioxidant, and an antioxidant having a thioether skeleton. It is 1 or more types chosen from a group, The said ultraviolet absorber contains a benzotriazole type ultraviolet absorber, The curable composition characterized by the above-mentioned.
Curable compound (Z): urethane acrylate (A) having an addition polymerizable unsaturated group and synthesized using polyoxyalkylene polyol and polyisocyanate as raw materials and having a molecular weight of 1,000 to 100,000 And one or more monomers (B) having a molecular weight of 100 to 600 having an addition polymerizable unsaturated group and a hydroxyl group.
Non-curable component (D): polyoxyalkylene poly (mono) ol having 1 to 6 hydroxyl groups per molecule.

  [2] In the above [1], the curable compound (Z) contains one or more monomers (C) having an addition polymerizable unsaturated group, no hydroxyl group, and a molecular weight of 100 to 500. The curable composition as described.

[3] The curable composition according to [1] or [2], containing bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide as the acylphosphine oxide-based photopolymerization initiator.
[4] The curable composition according to any one of [1] to [3], wherein the benzotriazole-based ultraviolet absorber includes a compound represented by the following formula (I).

［式中、Ｒ^１は炭素数７〜９の直鎖状または分岐状アルキル基を表す。］

[Wherein, R ¹ represents a linear or branched alkyl group having 7 to 9 carbon atoms. ]

  [5] [1] to [4] containing 0.05 to 5% by mass of the antioxidant and 0.01 to 10% by mass of the ultraviolet absorber with respect to 100% by mass of the curable composition. ] The curable composition as described in any one of.

[6] A cured product of the curable composition according to any one of [1] to [5].
[7] In the measurement of dynamic viscoelasticity after curing, the storage shear modulus at 1 Hz at 25 ° C. is 5 × 10 ^{2 to} 2.5 × 10 ⁴ Pa, and the loss tangent is 1.4 or less. [6].
[8] A laminate comprising the cured product according to [6] or [7] and a pair of face materials sandwiching the cured product.
[9] The laminate according to [8], wherein at least one of the pair of face materials is a glass plate.

[10] An image display device body, the cured product according to [6] or [7], and a face material,
An image display device in which the cured product is sandwiched between an outermost member on the viewing side of the image display device main body and a face material.
[11] The image display device according to [10], wherein the face material is a transparent face material that forms part of the outer surface of the structure and faces the outdoors.
[12] The image display device according to [11], wherein the image display device is a liquid crystal display.

ADVANTAGE OF THE INVENTION According to this invention, it is suitable for formation of the adhesion layer which sticks face materials together, and it is transparent, the elastic modulus after hardening is low, and the curable composition with little deterioration by an ultraviolet-ray is obtained.
The hardened | cured material of the curable composition of this invention is suitable as an adhesion layer which sticks face materials, is transparent, has a low elasticity modulus after hardening, and there is little deterioration by an ultraviolet-ray.
In the laminate of the present invention, face materials are adhered to both surfaces of the adhesive layer, the adhesive layer is transparent, has a low elastic modulus after curing, and is less deteriorated by ultraviolet rays.
In the image display device of the present invention, one surface of the adhesive layer is attached to the outermost member on the viewing side of the image display device, and an arbitrary face material is attached to the other surface of the adhesive layer. It is transparent, has a low elastic modulus after curing, and is hardly deteriorated by ultraviolet rays.

It is a graph which shows the light absorption spectrum of the photoinitiator used by the Example and the comparative example. It is a graph which shows the light absorption spectrum of the ultraviolet absorber used by the Example and the comparative example.

In the present specification, “transparent” means having optical transparency to visible light. Specifically, it means that the light transmittance at a wavelength of 420 to 800 nm is maintained within a range of 70 to 99%.
“Number average molecular weight (also referred to as Mn)” in the present specification is a polystyrene-converted molecular weight obtained by measuring with gel permeation chromatography using a calibration curve prepared using a standard polystyrene sample with a known molecular weight. It is.
The “molecular weight” in the present specification is a molecular weight represented by a formula weight obtained based on a chemical formula.
In this specification, polyoxyalkylene polyol and polyoxyalkylene monool are collectively referred to as polyoxyalkylene poly (mono) ol.

<Curable composition>
The curable composition of the present invention contains a curable compound (Z), a non-curable component (D), a photopolymerization initiator, an antioxidant, and an ultraviolet absorber.
[Curable compound (Z)]
The curable compound (Z) is one or more of urethane acrylate (A) having a molecular weight of 1,000 to 100,000, and a monomer (B) having a molecular weight of 100 to 600 having an addition polymerizable unsaturated group and a hydroxyl group. 1 or more types of.
The curable compound (Z) may further contain a monomer (C) having an addition polymerizable unsaturated group, no hydroxyl group, and a molecular weight of 100 to 500.

[Urethane acrylate (A)]
The urethane acrylate (A) is a urethane acrylate synthesized using polyoxyalkylene polyol and polyisocyanate as raw materials. Urethane acrylate (A) has an oxyalkylene chain and a urethane bond.
The curable group of the urethane acrylate (A) is an acryloyloxy group. An acryloyloxy group is preferable from the viewpoint of productivity because of its high curing rate.
The number of curable groups in one molecule of the urethane acrylate (A) is 1 or more, preferably 1 or more and 4 or less, and more preferably 2 or 3. In consideration of the case where a by-product having no curable group is produced during the production of urethane acrylate (A), the average number of curable groups in urethane acrylate (A) is preferably 0.8 to 4.0, and 0 .8 to 3.0 is more preferable.

The polyisocyanate used for the production of the urethane acrylate (A) is preferably a diisocyanate selected from aliphatic diisocyanates, alicyclic diisocyanates and non-yellowing aromatic diisocyanates.
Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, and the like. Examples of the alicyclic polyisocyanate include isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate) and the like. Examples of the non-yellowing aromatic diisocyanate include xylylene diisocyanate. These may be used alone or in combination of two or more.

The urethane acrylate (A) is obtained by reacting a polyoxyalkylene polyol and a polyisocyanate compound to obtain a prepolymer having an isocyanate group at the terminal, and then having an acryloyloxy group in the isocyanate group of the prepolymer and an isocyanate. What introduced the acryloyloxy group by making the monomer (m) which has a group which reacts with a group react is preferable.
The number average molecular weight of the polyoxyalkylene polyol is preferably 500 to 20,000, more preferably 1,000 to 18,000, and still more preferably 1,500 to 15,000.
The index for reacting the polyoxyalkylene polyol and the polyisocyanate compound is preferably in the range of 105 to 200. The index is a value obtained by dividing the number of moles of isocyanate groups of the polyisocyanate compound by the number of moles of hydroxyl groups of the polyol and multiplying by 100.

The group that reacts with the isocyanate group in the monomer (m) is a group having an active hydrogen (hydroxyl group, amino group, etc.).
Specific examples of the monomer (m) include a hydroxyalkyl acrylate having a hydroxyalkyl group having 2 to 6 carbon atoms (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, etc.). Is mentioned. In particular, a hydroxyalkyl acrylate having a C2-C4 hydroxyalkyl group is preferred.

The number average molecular weight of the urethane acrylate (A) is 1,000 to 100,000, preferably 10,000 to 80,000, and more preferably 15,000 to 70,000. When the number average molecular weight of the urethane acrylate (A) is within the above range, a curable composition having a viscosity suitable for forming an adhesive layer is easily obtained.
When using 2 or more types of urethane acrylate (A) together, it is preferable that the number average molecular weight of each urethane acrylate (A) is in said range.
The viscosity at 25 ° C. of the urethane acrylate (A) is preferably 10 to 2,000 Pa · s, more preferably 20 to 1,800 Pa · s, and further preferably 30 to 1,600 Pa · s. Within the above range, it is easy to obtain a curable composition having a viscosity suitable for forming an adhesive layer.
The viscosity of the urethane acrylate (A) is a value measured at 25 ° C. using an E-type viscometer.

The urethane acrylate (A) is a reaction product of at least one polyoxyalkylene polyol having a number average molecular weight of 1,500 to 15,000, at least one alicyclic diisocyanate, and a hydroxyalkyl acrylate. Preferably there is.
10-90 mass% is preferable, as for the content rate of urethane acrylate (A) with respect to 100 mass% of curable compound (Z), 20-90 mass% is more preferable, and 30-80 mass% is further more preferable. Within this range, the adhesiveness and curability of the curable composition are good, and the heat resistance of the cured product is good.

[Monomer (B)]
The monomer (B) having a curable group and a hydroxyl group contributes to the improvement of the adhesion and light transmittance of the cured product of the curable composition.
The curable group of the monomer (B) is an addition polymerizable unsaturated group. An acryloyloxy group or a methacryloyloxy group is preferred, and an acryloyloxy group is more preferred from the viewpoint of a high curing rate and a highly transparent adhesive layer.
The molecular weight of the monomer (B) is 100 to 600, preferably 110 to 400. When the molecular weight of the monomer (B) is 100 or more, volatilization of the monomer is suppressed. When the molecular weight of the monomer (B) is 600 or less, the adhesion between the face material and the cured product (adhesive layer) becomes good.
The monomer (B) preferably has 1 to 3 curable groups per molecule from the viewpoint of curability and mechanical properties of the cured product.
When two or more monomers (B) are used in combination, the molecular weight of each monomer (B) is preferably within the above range.

The number of hydroxyl groups in the monomer (B) is preferably 1 or 2.
The monomer (B) is preferably a hydroxy acrylate having 2 to 8 carbon atoms or a hydroxy methacrylate.
Specifically, for example, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, 6 -Hydroxyhexyl methacrylate and the like. Among these, a hydroxy acrylate having a hydroxyalkyl group having 2 to 8 carbon atoms is preferable, and 4-hydroxybutyl acrylate is particularly preferable.
The proportion of the monomer (B) contained in the curable compound (Z) is preferably 10 to 90 mass%, more preferably 10 to 70 mass%, more preferably 10 to 60 mass% with respect to 100 mass% of the curable compound (Z). More preferred is mass%.

[Monomer (C)]
The monomer (C) having a curable group contributes to suppression of an increase in the elastic modulus of the cured product of the curable composition. Monomer (C) does not contain a hydroxyl group.
The curable group of the monomer (C) is an addition polymerizable unsaturated group. The group is preferably an acryloyloxy group or a methacryloyloxy group, and more preferably an acryloyloxy group, from the viewpoint of a high curing rate and a highly transparent adhesive layer.
The molecular weight of the monomer (C) is 100 to 500, preferably 150 to 400.
When two or more monomers (C) are used in combination, the molecular weight of each monomer (C) is preferably within the above range.

  As the monomer (C) having an acryloyloxy group, an alkyl acrylate having an alkyl group having 8 to 22 carbon atoms (n-octyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, n-behenyl acrylate, etc.) ) And acrylates having an alicyclic hydrocarbon group (isobornyl acrylate, adamantyl acrylate, etc.). Among these, an alkyl acrylate having an alkyl group having 8 to 22 carbon atoms is preferable, and n-dodecyl acrylate is particularly preferable.

  In the curable compound (Z), the monomer (C) is not essential, but when the curable compound (Z) includes the monomer (C), 1 to 60 mass with respect to 100 mass% of the curable compound (Z). % Is preferable, and 10 to 50% by mass is more preferable. The effect by containing a monomer (B) and a monomer (C) is fully acquired as it is more than the lower limit of the said range, and favorable sclerosis | hardenability is acquired as it is below an upper limit. The total mass of the monomer (B) and the monomer (C) is preferably 11 to 80% by mass with respect to the total (100% by mass) of the urethane acrylate (A), the monomer (B) and the monomer (C). -70 mass% is more preferable, and 50-70 mass% is further more preferable.

[Non-curable component (D)]
The non-curable component (D) is a polyoxyalkylene poly (mono) ol having 1 to 6 hydroxyl groups per molecule. The non-curable component (D) contributes to the reduction of the elastic modulus of the cured product. A non-hardening component (D) may be used individually by 1 type, and may use 2 or more types together.
The hydroxyl group of the non-curable component (D) does not undergo a curing reaction with the urethane acrylate (A), the monomer (B) and the monomer (C) at the time of curing. The non-curable component (D) contributes to a decrease in the elastic modulus of the cured product.
When the hydroxyl group in the cured product containing the monomer (B) and the hydroxyl group of the non-curable component (D) coexist in the curable composition, the non-curing property in the cured product is caused by the interaction between the hydroxyl groups. Good stability of the component (D) is easily obtained. It is assumed that hydrogen bonds are involved in the interaction between the hydroxyl groups.

The number average molecular weight of the non-curable component (D) is preferably 500 to 20,000, more preferably 1,000 to 18,000, and still more preferably 1,500 to 15,000. When it is at least the lower limit of the above range, the polarity does not become too high, and good compatibility with the curable compound (Z) in the curable composition is easily obtained. The non-curing component (D) is stabilized in the cured resin layer by the interaction between the hydroxyl group derived from the curable compound (Z) and the hydroxyl group of the non-curing component (D) if it is not more than the upper limit. It is easy to get an effect.
As the non-curable component (D), one kind of polyoxyalkylene poly (mono) ol may be used, or two or more kinds having different molecular weights and functional groups may be used. By using two or more types together, it becomes easy to adjust physical properties such as viscosity and adhesion.

  When a polyol having the same structure as the polyoxyalkylene polyol used as a raw material for the urethane acrylate (A) coexisting in the curable composition is used as the non-curable component (D), the compatibility in the curable composition is improved. .

  The non-curable component (D) is preferably 1 to 90 parts by mass, more preferably 2 to 85 parts by mass, and still more preferably 2 to 80 parts by mass with respect to 100 parts by mass of the curable compound (Z). If it is at least the lower limit of the above range, the effect of reducing the stress generated by the shrinkage of the resin during curing can be sufficiently obtained. When the amount is not more than the upper limit value, the face materials are easily fixed to each other, and the positional deviation with time is easily prevented after the surface material and the back material are joined.

[Photopolymerization initiator]
As the photopolymerization initiator, at least an acyl phosphine oxide photopolymerization initiator is used. 1 type may be sufficient and 2 or more types may be used together.
In addition to the acylphosphine oxide system, a known photopolymerization initiator may be used in combination as long as the effects of the present invention are not impaired. The amount of the photopolymerization initiator other than the acylphosphine oxide is preferably 100% by mass or less, more preferably 50% by mass or less, and still more preferably 10% by mass or less in the total of the photopolymerization initiators. Zero is acceptable.
As an acylphosphine oxide photopolymerization initiator, for example, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (product name: IRGACURE 819, manufactured by BASF, photopolymerization initiator shown in FIG. 1)), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (product name: LUCIRIN TPO, manufactured by BASF) and the like.
In particular, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide is more preferable because it is an initiator having a photobleaching effect. The photobleaching effect is that the initiator itself has absorption in the visible light region, so it shows a pale yellow color before light irradiation, but the decomposition of the initiator proceeds with light irradiation, and the ability to absorb visible light wavelengths decreases. By this, the transmittance at the visible light wavelength is improved and the effect becomes colorless and transparent.

  The addition amount of the photopolymerization initiator is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 7 parts by weight, and 0.1 to 5 parts by weight with respect to 100 parts by weight of the curable compound (Z). Part is more preferred. When it is at least the lower limit of the above range, good curability is easily obtained. If it is not more than the upper limit, coloring after curing tends to be reduced.

[Antioxidant]
As the antioxidant, at least one selected from the group consisting of phenolic antioxidants, phosphorus antioxidants, and antioxidants having a thioether skeleton is used. A thioether skeleton means RSR ′ (R and R ′ are each independently an organic group containing a carbon atom bonded to a sulfur atom in the formula). Each can be appropriately selected from known antioxidants. Two or more kinds may be used in combination.
The antioxidant is preferably 0.05 to 5% by mass, more preferably 0.07 to 4% by mass, and still more preferably 0.1 to 3% by mass with respect to 100% by mass of the curable composition. If it is at least the lower limit of the above range, the effect of addition can be sufficiently obtained. Bleedout can be sufficiently reduced when the upper limit is not exceeded.

[Ultraviolet absorber]
As the UV absorber, at least a benzotriazole UV absorber is used. One type may be used, and two or more types of ultraviolet absorbers may be used in combination.
Ultraviolet absorbers other than benzotriazole-based ultraviolet absorbers may be used within a range that does not impair the effects of the present invention, but the addition amount is preferably 50% by mass or less, and 30% by mass or less of the total of the ultraviolet absorbers. Is more preferable, and 30 mass% or less is still more preferable. Zero is acceptable.

Examples of benzotriazole UV absorbers include:
(U1): (3- (2H-Benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-benzenepropanoic acid alkyl ester represented by the following formula (I). In the formula (I), R ¹ represents a linear or branched alkyl group having 7 to 9 carbon atoms.
(U2): 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol (eg, product Name: Tinuvin 928, manufactured by BASF).
(U3): Tinuvin 213 (product name, manufactured by BASF).
Among these, (U1) is preferable in terms of small initial coloring, and an ultraviolet absorber containing (U1) as an active ingredient is preferable.
Examples of the ultraviolet absorber containing (U1) include Tinuvin 384-2 (product name, manufactured by BASF Corporation, residual content: 95% by mass). The residue in Tinuvin 384-2 is a mixture of compounds in which R ¹ has 7, 8, or 9 carbon atoms in the following formula (I).

  The addition amount of the ultraviolet absorber is preferably 0.01 to 10% by mass, more preferably 0.03 to 4% by mass, and further 0.05 to 3% by mass with respect to 100% by mass of the curable composition. preferable. If it is at least the lower limit of the above range, the effect of addition can be sufficiently obtained. When the amount is not more than the upper limit, a good cured state can be obtained when a cured product (adhesive layer) made of the curable composition is obtained.

<Other additives>
Additives other than the above include polymerization inhibitors, chain transfer agents, light stabilizers (radical scavengers), photocuring accelerators, flame retardants, adhesion improvers (silane coupling agents, tackifier resins, etc.) Further, known additives such as pigments and dyes can be contained.

Polymerization inhibitors such as hydroquinone (2,5-di-tert-butylhydroquinone), catechol (p-tert-butylcatechol, etc.), anthraquinone, phenothiazine, hydroxytoluene, etc. are prohibited. Agents.
Examples of the chain transfer agent include compounds having a thiol group (n-octyl mercaptan, n-dodecyl mercaptan, 1,4-bis (3-mercaptobutyryloxy) butane, pentaerythritol tetrakis (3-mercaptobutyrate), etc. Is mentioned.
The light stabilizer (radical scavenger) is used for preventing light deterioration of the curable composition and improving weather resistance. For example, a hindered amine light stabilizer (radical scavenger) is used. Is mentioned.

When the curable compound (Z) contains other additives, the total content of the other additives is preferably 10.0% by mass or less with respect to 100% by mass of the curable composition; 0 mass% or less is more preferable.
In particular, when the curable compound (Z) contains a hindered amine light stabilizer as another additive, the content of the hindered amine light stabilizer is 0.001 to 100% by mass of the curable composition. 10.0 mass is preferable and 0.01-8.0 mass% is more preferable. When the curable compound (Z) contains a hindered amine stabilizer, it is further effective in preventing yellowing.

[Viscosity of curable composition]
If the viscosity of the curable composition is too low, it becomes difficult to ensure the thickness of the pressure-sensitive adhesive layer because it is too spread during coating. If the viscosity of the curable composition is too high, the workability during coating and the uniformity of the coating film may be deteriorated.
The viscosity of the curable composition may be in a range that does not cause these disadvantages. For example, 10 to 100,000 mP · s is preferable, 50 to 100,000 mP · s is more preferable, and 100 to 50,000 mP · s is more preferable. The viscosity of the curable composition is a value measured using an E-type viscometer at 25 ° C.

<Hardened product>
The curable composition of the present invention can be cured by irradiating light to obtain a cured product.
The hardened | cured material of the curable composition of this invention has adhesiveness, and is used suitably as an adhesion layer.
The cured product is colorless and transparent when it does not contain a coloring component. Therefore, it can be suitably used for an adhesive layer that requires good transparency and visibility.
In addition, since the cured product is hardly deteriorated by ultraviolet rays, it is suitable for an application that is used in a place where it is easily exposed to light or a place where much ultraviolet irradiation is performed.
Furthermore, since the cured product has a low elastic modulus after curing, it is suitable as an adhesive layer laminated on the display surface of the display device, and can prevent deterioration in display quality such as display unevenness.
Specifically, the physical shear modulus of 1 Hz at 25 ° C. in the dynamic viscoelasticity measurement after curing is 5 × 10 ^{2 to} 2.5 × 10 ⁴ Pa, and the loss tangent is 1.4 or less. A cured product is obtained. The lower limit value of the loss tangent is not particularly limited and can be within a range that can be taken in production, but in the case of a relatively flexible cured product, it is usually 0.01 or more.

The method for measuring the storage shear modulus and loss tangent in the present invention uses a dynamic viscoelasticity measuring device and irradiates light while applying dynamic shear strain to an uncured curable composition. Is performed by a method of curing.
Specifically, using a rheometer (Anton Paar, Physica MCR301), an uncured curable composition is mixed with a soda lime glass stage and a measuring spindle (Anton Paar, D-PP12 / AL). 150 mW / cm ^{2 for} 10 minutes by a mercury xenon lamp (Hamamatsu Photonics, LC8 LIGHTNINGCURE L9588-01) sandwiched in a 0.4 mm gap between the two layers of / S07) and installed at the bottom of the stage at 35 ° C. in an air atmosphere. The curable composition is cured by applying a dynamic shear strain of 1% while irradiating the light, and the storage shear modulus and its loss tangent (tan δ) are measured. When the curable composition is cured, the position of the spindle is automatically adjusted so that no stress is generated in the normal direction of the spindle. The irradiation intensity is measured on a stage on which the curable composition is installed using an illuminance meter (Ushio Electric Co., Ltd., UV intensity meter Unimeter UIT-101).

<Laminated body>
The laminate of the present invention includes a cured product of the curable composition of the present invention and a pair of face materials that sandwich the cured product (also referred to as an adhesive layer).
The average thickness of the adhesive layer is preferably 0.03 mm to 5 mm, more preferably 0.05 mm to 3 mm, and still more preferably 0.07 mm to 2 mm. If the average thickness of the pressure-sensitive adhesive layer is 0.03 mm or more, the pressure-sensitive adhesive layer effectively buffers an impact caused by an external force from one face material side, and the effect of protecting the other face material is easily obtained. In addition, even when a foreign material that does not exceed the thickness of the adhesive layer is mixed between the pair of face materials during the production of the laminate, the average thickness does not vary greatly depending on the site of the adhesive layer. It is easy to obtain. On the other hand, if the average thickness of the adhesive layer is 5 mm or less, the overall thickness of the laminate is not unnecessarily thick.
The thickness of the adhesive layer can be adjusted by, for example, a method of adjusting the amount of the curable composition at the time of production.

The pair of face materials may be transparent or opaque, but at least one of them is preferably transparent. The cured product of the present invention is particularly suitable when one or both face materials are transparent because good transparency is obtained.
Moreover, since the hardened | cured material of this invention has little deterioration by an ultraviolet-ray, what is excellent in a weather resistance as a face material is preferable. For example, it is preferable that at least one is a glass plate.
The shape of the face material is not particularly limited. For example, it may be a plate having rigidity or a flexible film. In the case of a plate shape, it may be a flat plate shape or a plate shape having a curved surface.
The face material may be a part of the structure. For example, a glass plate or a transparent resin plate as a protective plate provided on the viewing side of the display surface of the display panel, a part of the outer surface of a structure provided outdoors, a glass plate or transparent resin plate facing outdoors, etc. Is mentioned.

[First Embodiment of Laminate]
The 1st embodiment of a layered product is an adhesive sheet with a release film by which an adhesion layer was pinched between two release films. Both of the two release films may be opaque, both may be transparent, one may be transparent and the other opaque.
The release film is detachably attached to protect the surface of the adhesive layer, and is peeled off when the adhesive layer is used. The release film is made of a polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) or polyethylene naphthalate (PEN); a polyamide resin such as nylon-6 or nylon-66; Olefin resin such as polypropylene; and the like.
A release agent may be applied to the surface of the release film that is in close contact with the adhesive layer.

[Second Embodiment of Laminate]
The second embodiment of the laminate is a transparent surface material with an adhesive layer in which an adhesive layer is sandwiched between the transparent surface material and the release film. The release film may be transparent or opaque. The transparent surface material is, for example, a protective plate for a display panel.
The material of the transparent face material is preferably glass or transparent resin. In particular, glass is preferable because it is excellent in transparency, light resistance, low birefringence, planar accuracy, surface scratch resistance (abrasion resistance), and mechanical strength. Examples of the transparent face material include a transparent face material such as a glass plate, a transparent resin plate, and a laminate of a glass plate and a transparent resin. The release film is the same as in the first embodiment.

The transparent surface material with an adhesive layer may be provided with an adhesive layer on each side of the transparent surface material. For example, you may have the structure by which the adhesion layer and the release film were each laminated | stacked in this order on both surfaces of the transparent surface material. The transparent surface material is, for example, a protective plate for a display panel.
With such a configuration, for example, by sticking one adhesive layer to the display panel and sticking the other adhesive layer to the window glass, the display panel is sandwiched with a transparent surface material (protective plate). Therefore, it can be suitably used for applications where it is attached to a window glass.

Examples of the glass include glass materials such as soda lime glass. Among them, it is more preferable to use a highly transmissive glass (white plate glass) having a lower iron content and less bluishness. Moreover, as glass, in order to improve safety, laminated glass or tempered glass may be used, or glass subjected to physical strengthening or chemical strengthening may be used. You may use the glass which performed the low reflection coating for visibility improvement.
Examples of the transparent resin include highly transparent resin materials such as polycarbonate (PC) and polymethyl methacrylate (PMMA). Moreover, if it has the required transparency, you may use the resin board which laminated | stacked 2 or more types of resin materials, and the resin plate which uses as a forming material the resin composition which mixed 2 or more types of resin materials or fillers May be used.

The transparent surface material may be subjected to a surface treatment for improving the interfacial adhesive force with the adhesive layer. Examples of the surface treatment method include a method of treating the surface of the transparent surface material with a silane coupling agent. Further, when the transparent surface material is a glass plate, a surface treatment method includes a method of forming a silicon oxide thin film by an oxidation flame using a frame burner.
What is necessary is just to set the thickness of a transparent surface material from points, such as mechanical strength and transparency.
For example, the thickness of the glass plate as the protective plate of the display panel is preferably in the range of 0.2 mm to 30 mm. The thickness of the transparent resin plate as the protective plate of the display panel is preferably in the range of 0.4 mm to 10 mm.
A frame-shaped light shielding layer may be provided on one surface of a transparent surface material as a protective plate of the display panel by a known method.

The laminate of the first embodiment or the second embodiment is, for example, a step of sandwiching an uncured layer made of a curable composition between a pair of face materials, and curing by irradiating the uncured layer with light. It can manufacture suitably by the method which has a process to make. As this method, a known method can be appropriately used.
For example, a curable composition is applied by bar coating on a release surface of a release film to which a release agent is applied, and another release film to which a release agent is applied is then released. There is a method in which the curable composition is cured by irradiating ultraviolet rays from a high-pressure mercury lamp after the surface is placed in close contact with the curable composition.
It is preferable that at least one of the pair of face materials is a transparent face material because the uncured layer can be cured by being irradiated with light through the transparent face material.

[Third Embodiment of Laminate]
The 3rd embodiment of a layered product is a mode in which a face material is a part of structure. Although the face material that is a part of the structure is not particularly limited, the cured product (adhesive layer) of the present embodiment is less deteriorated by ultraviolet rays, and therefore, particularly a part of the structure provided facing the outdoors, such as the sun. It may be a face material that receives light.
Examples of the face material include an outermost member on the viewing side of the outdoor image display apparatus main body, a part of the outer surface of the structure, and a glass plate or a transparent resin plate facing the outdoors. An outdoor image display device is an image display device that is assumed to receive sunlight, such as an image display device installed outdoors or an image display device provided indoors so that the display screen faces the outdoors. Means device.
Examples of the outermost member on the viewing side of the image display device main body include a face material forming the display surface of the display panel and a protective plate attached to the viewing side of the display panel.
Examples of the transparent surface material that forms a part of the outer surface of the structure and faces the outdoors include a window glass of a building, a surface material of a display surface of a display device provided in a bus stop or a station premises, and the like.

As an example of the laminate of the present embodiment, an image display device having a configuration in which an adhesive layer is sandwiched between an outermost member on the viewing side of the image display device body and a release film; visual recognition of the image display device body And an image display device having a configuration in which an adhesive layer is sandwiched between an outermost member on the side and a transparent surface material that forms part of the outer surface of the structure and faces the outdoors.
The image display device is particularly preferably an outdoor image display device.

The laminate of the present embodiment is a surface material that is a part of a structure of the pressure-sensitive adhesive sheet with a release film of the first embodiment and / or the pressure-sensitive adhesive layer of the transparent surface material with the pressure-sensitive adhesive layer of the second embodiment. It can manufacture suitably by the method of having the sticking process stuck on.
When the sticking step is performed in a reduced pressure atmosphere, voids are less likely to occur at the interface between the face material and the adhesive layer. Moreover, even if a gap is generated at the interface between the adhesive layer and the face material when the sticking process is performed in a reduced pressure atmosphere and returned to the atmospheric pressure atmosphere after the sticking, the pressure in the gap (reduced pressure) And the pressure (atmospheric pressure) applied to the pressure-sensitive adhesive layer, the void volume tends to decrease. Furthermore, the gas in the voids whose volume has been reduced dissolves in the adhesive layer and is easily absorbed.
In particular, when the face material is the outermost member on the visual recognition side of the display device, the optical distortion due to the presence of the air gap is suppressed by reducing or eliminating the air gap at the interface between the face material and the adhesive layer in this way. Thus, excellent visibility is obtained.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
<Evaluation method of weather resistance>
The weather resistance (durability against ultraviolet rays) of the cured product of the curable composition was evaluated by the following method.
[Sample preparation method]
In advance, a silicone sheet for a mold was prepared by penetrating the center of a 0.5 mm thick silicone sheet into a shape corresponding to the film to be obtained.
As a release film, a release film in which a release agent was applied to one surface (hereinafter also referred to as a release surface) made of polyethylene terephthalate (PET) was prepared. Hereinafter, a substrate having a thickness of 125 μm is referred to as a first release film, and a substrate having a thickness of 75 μm is referred to as a second release film.
On the mold release surface of the first mold release film (length 150 mm, width 150 mm), a silicone sheet for molds was placed and the curable composition was applied by bar coating. A second release film (length 150 mm, width 150 mm) was placed thereon so that the release surface was in close contact with the curable composition, and then irradiated with ultraviolet rays from a high-pressure mercury lamp (integrated light quantity 1500 mJ / cm ² ), the curable composition was cured.
Thus, a laminate in which the cured product was sandwiched between the first release film and the second release film was obtained. The obtained laminate was cut out to a size of 65 mm in length and 60 mm in width, and after peeling off the second release film, it was attached to soda lime glass having a length of 74 mm, a width of 68 mm, and a thickness of 1.3 mm. Next, the first release film was peeled off, placed in a vacuum bonding machine, and placed on the elevating stage so that the cured product (adhesive layer) of the curable composition was on top (in contact with air). . Furthermore, a soda lime glass with a length of 74 mm, a width of 68 mm, and a thickness of 1.3 mm is placed on the upper lid of the vacuum bonding machine, directly above the cured product (adhesive layer) of the curable composition placed on the elevating stage. It was pasted with double-sided tape to match the position. After reducing the pressure inside the vacuum bonding machine to 10 Pa and holding it for 1 minute, the elevating stage was raised, and the cured product (adhesive layer) of the curable composition was brought into close contact with the soda lime glass attached to the upper lid. Thus, a laminate (sample) in which the cured product (adhesive layer) was sandwiched between two soda lime glasses was produced. After bonding, the pressure was returned to atmospheric pressure, and the sample was taken out from the vacuum bonding machine.

[Evaluation method]
About the obtained laminate (sample), with a super xenon weather meter (product name: SX75, manufactured by Suga Test Instruments Co., Ltd.) up to 500 hours under the conditions of UV irradiation illuminance of 150 W / m ² and black panel temperature of 83 ° C. Tested and observed over time.
(Liquid dripping)
It was confirmed by visual observation whether or not a liquid sagging caused by softening and deformation of the cured product (adhesive layer) occurred. The case where dripping occurred before 500 hours passed was rated as x, and the case where no dripping occurred after 500 hours passed was marked as ◯.
(Yellowing)
Yellowing was evaluated in three stages according to the following criteria.
X: Yellowing is observed in the cured product (adhesive layer) 200 hours after the start of the test.
◯: No yellowing was observed in the cured product (adhesive layer) after 200 hours from the start of the test, but yellowing was observed after 500 hours.
A: No yellowing is observed in the cured product (adhesive layer) after 500 hours from the start of the test.

[Preparation Example 1: Synthesis of urethane acrylate (A-1)]
A bifunctional polypropylene glycol having a molecular end modified with ethylene oxide (number average molecular weight: 4,000) and isophorone diisocyanate, which is an alicyclic polyisocyanate compound, are mixed at a molar ratio of polypropylene glycol: isophorone diisocyanate of 5: 6 ( The mixture was mixed so as to have an index of 120) and reacted at 70 ° C. in the presence of a catalyst that was a tin compound to obtain a prepolymer.
By adding 2-hydroxyethyl acrylate to the obtained prepolymer so that the molar ratio of prepolymer: 2-hydroxyethyl acrylate is about 1: 2, and reacting at 70 ° C., urethane acrylate (hereinafter, A-1) was obtained. The curable group of A-1 had an average of 2.0 per molecule, a number average molecular weight of about 24,000, and a viscosity at 25 ° C. of about 830 Pa · s.

Table 1 shows the composition of the curable composition. Each component described in the table is as follows. FIG. 1 shows the light absorption spectra of the photopolymerization initiators (1) and (2), and FIG. 2 shows the light absorption spectra of the ultraviolet absorbers (1), (4) and (6).
Urethane acrylate (A-1): urethane acrylate (A-1) obtained in Preparation Example 1.
Monomer (B): 4HBA (product name), manufactured by Osaka Organic Chemical Industry, 4-hydroxybutyl acrylate.
Monomer (C): Light acrylate LA LA (product name), manufactured by Kyoeisha Chemical Co., Ltd., n-dodecyl acrylate.
Photopolymerization initiator (1): Irgacure 819 (product name), manufactured by BASF, acylphosphine oxide photopolymerization initiator, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide.
Photopolymerization initiator (2): Irgacure 184 (product name), manufactured by BASF, alkylphenone photopolymerization initiator, 1-hydroxy-cyclohexyl-phenyl-ketone.
Polymerization inhibitor: 2,5-di-tert-butylhydroquinone (DTBHQ), manufactured by Tokyo Chemical Industry Co., Ltd.

Antioxidant (1): Irganox 1010 (product name), manufactured by BASF, phenol-based antioxidant, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate].
Antioxidant (2): 2112 (product name), manufactured by ADEKA, phosphorus antioxidant, tris (2,4-ditert-butylphenyl) phosphite.
Antioxidant (3): AO-503 (product name), manufactured by ADEKA, an antioxidant having a thioether skeleton, di (tridecyl) 3,3′-thiodipropionate.

Ultraviolet absorber (1): Tinuvin 384-2 (product name), manufactured by BASF, a benzotriazole-based ultraviolet absorber, a mixture containing as a main component a compound represented by the above formula (I).
UV absorber (2): Tinuvin 928 (product name), manufactured by BASF, benzotriazole UV absorber, 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol.
Ultraviolet absorber (3): Tinuvin 213 (product name), manufactured by BASF, a benzotriazole ultraviolet absorber.
Ultraviolet absorber (4): Tinuvin 400 (product name), manufactured by BASF, hydroxyphenyltriazine-based ultraviolet absorber.
Ultraviolet absorber (5): Tinuvin 479 (product name), manufactured by BASF, hydroxyphenyltriazine ultraviolet absorber.
Ultraviolet absorber (6): Tinuvin 477 (product name), manufactured by BASF, hydroxyphenyltriazine ultraviolet absorber.

Light stabilizer (1): Tinuvin 765 (product name), manufactured by BASF, a hindered amine light stabilizer (HALS).
Non-curable component (D1): The same bifunctional polypropylene glycol (number average molecular weight: 4,000) as used in the synthesis of A-1 and having a molecular end modified with ethylene oxide.
Non-curable component (D2): bifunctional polypropylene glycol having a molecular terminal modified with ethylene oxide (number average molecular weight: 7,000).

[Examples 1 to 11 and Comparative Examples 1 to 10]
Curable compositions were prepared with the formulations shown in Tables 1 and 2 (unit: parts by mass).
First, urethane acrylate (A-1), monomer (B), and monomer (C) were mixed uniformly. In the mixture, the additives shown in Table 1 (photopolymerization initiator, polymerization inhibitor, chain transfer agent, antioxidant, ultraviolet absorber, or light stabilizer) were uniformly dissolved to obtain an intermediate composition. . Next, the intermediate composition and the non-curable component were uniformly dissolved to obtain a curable composition. The viscosity at 25 ° C. of the obtained curable composition was in the range of 1,000 to 10,000 mPa · s in all examples.
About the hardened | cured material of the obtained curable composition, durability (liquid dripping, yellowing) with respect to an ultraviolet-ray was evaluated by said method. The results are shown in Tables 1 and 2. In any of the examples, the obtained cured product has good transparency to visible light, and the storage shear modulus at 25 ° C. is in the range of 5 × 10 ^{2 to} 2.5 × 10 ⁴ Pa and has low elasticity. It was rate.

As shown in the results of Tables 1 and 2, Examples 1 to 11 in which a phenolic antioxidant, a phosphorus antioxidant, and / or an antioxidant having a thioether skeleton and a benzotriazole ultraviolet absorber were added. Then, dripping did not occur even after 500 hours from the start of the test, and yellowing was well suppressed.
Comparative Example 1 was an example in which the antioxidant was added but no ultraviolet absorber was added, and liquid dripping was confirmed 50 hours after the start of the test. For this reason, yellowing was not evaluated.
Comparative Examples 2 to 10 are examples in which the antioxidant and the triazine ultraviolet absorber were added. Although dripping could be prevented, remarkable yellowing was observed 200 hours after the start of the test.

From these results, dripping can be prevented by adding the above-mentioned antioxidant and UV absorber, and yellowing can be suppressed well if the UV absorber is benzotriazole, but yellowing is suppressed if it is a triazine. It turns out that an effect is inadequate.
Even when the type of the antioxidant was changed to a phenolic antioxidant, a phosphorus antioxidant, or an antioxidant having a thioether skeleton, this tendency did not change.
For example, as shown in FIG. 2, the benzotriazole ultraviolet absorber (1) and the triazine ultraviolet absorbers (4) and (6) have a wavelength in the vicinity of 330 to 410 nm at which the photopolymerization initiator (1) has a low absorbance. It is a surprising finding that there is a large difference in the effect of suppressing yellowing in this way, despite showing a similar light absorption spectrum in that it has absorption in the band.

When Examples 1, 6, and 9 are compared, there is a difference in the degree of yellowing that is visually recognized. In particular, Example 1 using the benzotriazole ultraviolet absorber (1) is different from the benzotriazole ultraviolet absorber. The effect of suppressing yellowing was superior to Examples 6 and 9 using (2) and (3).
Moreover, Examples 1-5 are examples which used the mixture which has a compound represented by the said Formula (1) as a main component as a ultraviolet absorber, and compared with other Examples 6-11, initial stage coloring of hardened | cured material. Was small.

Claims (12)

1 to 90 parts by mass of the following non-curable component (D) is contained with respect to 100 parts by mass of the following curable compound (Z), and further includes a photopolymerization initiator, an antioxidant, and an ultraviolet absorber.
The photoinitiator includes an acyl phosphine oxide photoinitiator,
The antioxidant is at least one selected from the group consisting of phenolic antioxidants, phosphorus antioxidants, and antioxidants having a thioether skeleton,
The curable composition, wherein the ultraviolet absorber contains a benzotriazole ultraviolet absorber.
Curable compound (Z): urethane acrylate (A) having an addition polymerizable unsaturated group and synthesized using polyoxyalkylene polyol and polyisocyanate as raw materials and having a molecular weight of 1,000 to 100,000 And one or more monomers (B) having a molecular weight of 100 to 600 having an addition polymerizable unsaturated group and a hydroxyl group.
Non-curable component (D): polyoxyalkylene poly (mono) ol having 1 to 6 hydroxyl groups per molecule.   The hardening of Claim 1 in which the said sclerosing | hardenable compound (Z) contains one or more types of the monomer (C) which has an addition polymerizable unsaturated group, does not contain a hydroxyl group, and has a molecular weight of 100-500. Sex composition.   The curable composition according to claim 1 or 2, comprising bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide as the acylphosphine oxide-based photocuring initiator. The curable composition as described in any one of Claims 1-3 in which the said benzotriazole type ultraviolet absorber contains the compound represented by the following Formula (I).

[Wherein, R ¹ represents a linear or branched alkyl group having 7 to 9 carbon atoms. ]   The antioxidant according to any one of claims 1 to 4, comprising 0.05 to 5% by mass of the antioxidant and 0.01 to 10% by mass of the ultraviolet absorber with respect to 100% by mass of the curable composition. The curable composition according to item.   Hardened | cured material of the curable composition as described in any one of Claims 1-5. In the dynamic viscoelasticity measurement after curing, the storage shear elastic modulus at 1 Hz at 25 ° C. is 5 × 10 ^{2 to} 2.5 × 10 ⁴ Pa and the loss tangent is 1.4 or less. Hardened | cured material of description.   A laminate comprising the cured product according to claim 6 and a pair of face materials sandwiching the cured product.   The laminate according to claim 8, wherein at least one of the pair of face members is a glass plate. An image display device main body, the cured product according to claim 6 or 7, and a face material,
An image display device in which the cured product is sandwiched between an outermost member on the viewing side of the image display device main body and a face material.   The image display device according to claim 10, wherein the face material is a transparent face material that forms part of the outer surface of the structure and faces the outdoors.   The image display device according to claim 11, wherein the image display device is a liquid crystal display.

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