JP2018127528A - Photocurable resin composition having high refractive index - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent resin composition having a high refractive index, which is a photocurable resin to be used for an image display device or the like, which shows good adhesiveness in bonding an image display body to a plastic cover panel and which is free from blistering.SOLUTION: A photocurable resin composition having a high refractive index is provided, comprising a polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more, a monofunctional (meth)acrylate monomer (B) containing a polar group, a urethane resin (C) having no unsaturated group, and a photo-initiator (D), in which, with respect to the whole compounded amounts, the compounded amount of (A) is 30 to 60 wt.%, the compounded amount of (B) is 5 to 20 wt.%, and the compounded amount of (C) is 3 to 25 wt.%.SELECTED DRAWING: None

Description

  The present invention relates to a high refractive index photocurable resin used for bonding an image display member such as a liquid crystal and a plastic cover panel.

  Acrylic resins are used in various applications by taking advantage of their transparency and fast curing characteristics. For example, in an image display such as a smartphone or a touch panel, such an acrylic transparent resin is placed between an image display member such as a liquid crystal display panel or an organic EL display panel that displays an image and a cover panel that protects the image display member. A technique has been developed in which the air layer between the image display member and the cover panel is eliminated by filling and bonding to prevent a decrease in contrast and brightness. (Patent Document 1).

  In this field, there are various required properties in terms of physical properties. For example, in order to cope with a high refractive index in which the degree of freedom in optical design is widened, as a curable composition having a low shrinkage and being colorless and transparent, a poly ( An optical adhesive composed of a (meth) acrylate compound, a polythiol compound having a thioalkyl structure, and a photopolymerization initiator has been proposed (Patent Document 2).

However, when using an acrylate with a fluorene skeleton, it is difficult to adjust the hardness to be suitable for adhesion of optical members because of its rigid structure, and there is a problem that the yellow color is high in terms of color, and there is room for improvement. there were.

JP-A-2005-55641 Japanese Patent No. 5810611

An object of the present invention is to provide a transparent resin composition having a high refractive index, which is a photocurable resin used for an image display or the like.

The invention according to claim 1 includes a polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more, a monofunctional (meth) acrylate monomer (B) containing a polar group, and a urethane resin containing no unsaturated group ( C) and a photoinitiator (D), the blending amount of (A) is 30 to 60% by weight, the blending amount of (B) is 5 to 20% by weight, and (C) A high refractive index photocurable resin composition having a blending amount of 3 to 25% by weight is provided.

The invention according to claim 2 is the high refractive index photocurable resin composition according to claim 1, wherein the polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more is a 3-phenoxybenzyl acrylate oligomer. provide.

The invention according to claim 3 is the high refractive index light according to claim 1 or 2, wherein the monofunctional (meth) acrylate monomer (B) containing a polar group is an acrylate monomer containing a hydroxyl group or an amino group. A curable resin composition is provided.

  Invention of Claim 4 provides the high refractive index photocurable resin composition in any one of Claims 1-3 whose urethane resin (C) which does not contain the said unsaturated group is a polyurethane of polypropylene glycol frame | skeleton. To do.

  Invention of Claim 5 provides the high refractive index photocurable resin composition in any one of Claims 1-4 whose refractive index of hardened | cured material is 1.56 or more.

The photocurable resin of the present invention is useful as a high-refractive-index transparent resin composition that exhibits good adhesion in bonding a display body and a cover panel.

  The present invention will be described in detail below.

  The composition of the present invention is composed of a polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more, a monofunctional (meth) acrylate monomer (B) containing a polar group, and a urethane resin not containing an unsaturated group. (C) and a photoinitiator (D). In this specification, (meth) acrylate includes both acrylate and methacrylate.

The polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more used in the present invention is a main component constituting the present composition, and the refractive index is a polycarbonate widely used as a cover panel for a touch panel or a flat display panel. The refractive index is approximately the same as 1.54. By making the refractive index of the resin to be bonded to the cover panel close, reflection at the interface is reduced and visibility can be improved. Here, the refractive index of 1.56 means the refractive index of the oligomer itself, and the cover panel is not limited to polycarbonate. Examples of oligomers having a refractive index of 1.56 or more include naphthalene-based, anthracene-based, fluorene-based, and phenoxybenzyl-based oligomers having a plurality of aromatic rings. Among these, phenoxybenzyl-based oligomers are preferred from the viewpoint of flexibility. Is preferred.

The weight average molecular weight of (A) used in the present invention is preferably 10,000 to 25,000, and more preferably 13,000 to 20,000. By setting it to 10,000 or more, sufficient cohesive force can be ensured, and by setting it to 25,000 or less, it is easy to control the viscosity suitable for workability. The weight average molecular weight (hereinafter referred to as “Mw.”) Was measured and calculated by a gel permeation chromatography method using a tetrahydrofuran solvent in a column of a styrene vinyl benzene base material and a molecular weight in terms of standard polystyrene.

(A) used in the present invention contains a polyfunctional functional group so that it can form a tougher film by reacting with the (meth) acrylate monomer (B), but the number of functional groups is cured. Bifunctionals that do not shrink too much are preferred.

The blending amount of (A) with respect to the total composition is 30 to 60% by weight, more preferably 35 to 58% by weight. If it is less than 30% by weight, the viscosity will be low, making it difficult to adjust the viscosity suitable for workability, and sufficient film strength may not be ensured. If it exceeds 60% by weight, the viscosity becomes high and it becomes difficult to adjust the viscosity to be suitable for workability.

Said (B) used by this invention plays the role which improves hardening reactivity simultaneously with diluting high viscosity (A), and the number of functional groups is monofunctional which does not enlarge hardening shrinkage | contraction. Polycarbonate, which is widely used as a cover panel material, has a high water vapor permeability, so that the permeated moisture easily enters the cured film. However, if there is a polar functional group in the cured film, the hydrophilicity is improved and moisture is mixed. However, it is difficult to whiten.

  The polar functional group includes a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,4- Cyclohexanedimethanol monoacrylate, 4-hydroxycyclohexyl (meth) acrylate, 5-hydroxycyclooctyl (meth) acrylate, and the like can be used alone or in combination of two or more. Among these, 4-hydroxybutyl acrylate is preferable in terms of molecular weight and handling.

  Other polar functional groups include amino groups such as (meth) acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dipropyl (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropylacrylamide, N-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide , Diacetone acrylamide, hydroxyethyl acrylamide, acryloylmorpholine, and the like, which can be used alone or in combination of two or more. Among these, acryloylmorpholine having a high refractive index is preferable.

  The blending amount of (B) with respect to the total composition is 3 to 20% by weight, and more preferably 5 to 15% by weight. If it is less than 3% by weight, the moisture resistance tends to decrease and whitening tends to occur.

  The urethane resin (C) that does not contain an unsaturated group used in the present invention is a polymer that is highly compatible with (A), which plays a role in reducing curing shrinkage. Here, “not containing an unsaturated group” means that it does not have a functional group that is polymerized by active energy rays with (A) and (B). The refractive index is not particularly specified but is preferably 1.45 or more, more preferably 1.50 or more. Mw. Is preferably 1,000 to 30,000, more preferably 2,000 to 20,000. By setting it to 1,000 or more, curing shrinkage can be sufficiently reduced, and by setting it to 30,000 or less, it is easy to control the viscosity suitable for workability.

The urethane resin (C) used in the present invention has flexibility, but a urethane resin having a polyether skeleton such as polypropylene glycol (hereinafter referred to as PPG) that is particularly excellent in flexibility is suitable. Even if there is flexibility like a urethane resin, diene polymers such as polybutadiene and polyisoprene are unsuitable because they have poor compatibility with (A).

The blending amount of (C) with respect to the total composition is 5 to 25% by weight, more preferably 8 to 20% by weight. If it is less than 5% by weight, curing shrinkage cannot be sufficiently reduced, and if it exceeds 25% by weight, the refractive index is low, and it is difficult to adjust the viscosity to suit workability.

  The photopolymerization initiator (D) used in the present invention may be a general-purpose photopolymerization initiator because radicals are generated by irradiation with ultraviolet rays or electron beams, and the radicals trigger a polymerization reaction. Specifically, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl -Ketones, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propane-1 -One, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, and the like may be used alone or in combination of two or more. The amount is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the radical polymerizable component.

In addition, the photo-curable resin composition of the present invention is a reactive diluent, plasticizer, tackifier, antioxidant, flame retardant, filler, silane coupling agent, polymerization prohibition as long as performance is not impaired. An additive such as an agent can be used in combination.

  As the reactive diluent, a 3-phenoxybenzyl acrylate monomer that has good compatibility with (A), low viscosity, and can maintain a high refractive index of the cured product is preferable. The blending amount based on the total composition is preferably 40% by weight or less.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, a specific example is shown and it does not specifically limit to these. In addition, when there is no description, it measured on the conditions of 25 degreeC relative humidity 65% of room temperature.

Example 1
As an acrylate oligomer (A) having a refractive index of 1.56 or more, AMHR-7 (trade name: manufactured by Negami Kogyo Co., Ltd.) 70 parts by weight of a difunctional acrylic group-containing 3-phenoxybenzyl acrylate oligomer is diluted with 30 parts by weight of POB-A. Mw. 15,000) as a monofunctional (meth) acrylate monomer (B) containing a polar group, containing 4HBA (trade name: 4-hydroxybutyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.) and containing an unsaturated group As a polymer component (C), FZ-100 (trade name: manufactured by Asia Kogyo Co., Ltd., PPG skeleton polyurethane, Mw.2,300, refractive index 1.48) and Irgacure 819 (trade name: BASF) as a photoinitiator (D) Japan)) as a reactive diluent, POB-A (trade name: manufactured by Kyoeisha Chemical Co., Ltd., 3-phenoxybenzyl alcohol) Relate), and stirred until uniformly dissolved in the formulation shown in Table 1, to prepare a high refractive index light-curable transparent resin composition of Example 1.

Examples 2-6
In addition to the materials used in Example 1, (A) AMHR-5 (trade name: manufactured by Negami Kogyo Co., Ltd., 70 parts by weight of a bifunctional acrylic group-containing 3-phenoxybenzyl acrylate oligomer is 30 parts by weight of POB-A. The diluted product (Mw. 18,000) was stirred as (B) until ACMO (trade name: acryloylmorpholine, manufactured by KJ Chemicals) was uniformly dissolved in the formulation shown in Table 1, and Examples 2 to 6 were stirred. A high refractive index photocurable transparent resin composition was prepared.

Comparative Examples 1-7
In addition to the materials used in the examples, HR-1N (manufactured by Negami Kogyo Co., Ltd., 3-phenoxybenzyl acrylate polymer, Mw. 16,000) and Polybest 110 (trade name: manufactured by Evonik, The non-functional liquid polybutadiene) was stirred until it was uniformly dissolved with the formulation shown in Table 1, and the high refractive index photocurable transparent resin compositions of Comparative Examples 1 to 7 were prepared.

Table 1

The evaluation method was as follows.

Using a UV curing conditions <br/> Fusion UV Systems Japan Ltd. electrodeless UV irradiation apparatus F300S / LC-6B, the output at D bulb 100 mW / cm ^2, integrated light quantity was 3000 mJ / cm ^2.

Appearance after curing: 1 mm thick white plate glass (manufactured by Matsunami Glass Industrial Co., Ltd.) 76 mm × 104 mm is coated with a photocurable resin composition so as to have a thickness of 200 μm, and the same white plate glass is bonded to the above ultraviolet curing. It hardened on condition and it was set as the test piece. Using a haze meter HAZEGAED2 (manufactured by Gardner), the glass portion sandwiching the resin was subtracted to measure the haze, and the haze value was less than 1.0, and the above was rated as x.

Viscosity: Using a cone plate viscometer RC-550R manufactured by Toki Sangyo Co., Ltd., measured at a cone angle of 3 ° × R17.65 at 25 ± 1 ° C. and a rotation speed of 10 rpm, and 1,000-15,000 mPa · s The case where it was out of this range was marked as x.

 Refractive index: A silicone sheet hollowed out to 40 mm × 8 mm is placed on the release surface of a release PET film (trade name E7002 manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm so that the photocurable resin composition has a thickness of 50 μm. It was applied, the PET film was placed thereon, cured under the above ultraviolet curing conditions, and then the PET film was peeled off to obtain a cured resin product. Thereafter, the refractive index at 589 nm of the D line was measured using an Atpe refractometer DR-M2. The test piece was set on the prism surface, and 1-bromonaphthalene was used as the intermediate solution. Evaluation made 1.56 or more (circle) and less than x.

Curing shrinkage: Measured according to the specific gravity cup method of JIS K 6833. A curing shrinkage rate of less than 5% was evaluated as ◯, and 5% or more as x.

Reliability: A 1 mm thick white plate glass (manufactured by Matsunami Glass Industrial Co., Ltd.) is applied to a photocurable resin composition to a thickness of 200 μm on 76 mm × 104 mm, and the same white plate glass is bonded thereon to the above UV curing conditions. The test piece was cured with The test piece was allowed to stand in a constant temperature and humidity chamber of 85 ° C. × 85% RH for 500 hours.

Evaluation results <br/> Table 2

Each of the resin compositions of the Examples obtained good results in any evaluation of appearance, viscosity, refractive index, curing shrinkage and reliability.

On the other hand, Comparative Examples 1, 2, and 7 in which components other than polyurethane were blended as (C), Comparative Example 3 that exceeded the blending upper limit of (C), Comparative Example 4 in which (B) was omitted, and Comparative Example in which (C) was omitted 5, Comparative Example 6 exceeding the blending lower limit of (A) had x evaluation in any of the evaluation items, and was not suitable for the present invention.

INDUSTRIAL APPLICABILITY The present invention is useful as a transparent resin composition that is a visibility improving resin that exhibits good adhesion in bonding a display body such as an image display display and a plastic cover panel, and does not generate floating.

Claims (5)

A polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more, a monofunctional (meth) acrylate monomer (B) containing a polar group, a urethane resin (C) containing no unsaturated group, a photoinitiator ( D), the blending amount of (A) is 30 to 60% by weight, the blending amount of (B) is 5 to 20% by weight, and the blending amount of (C) is 3 to 25% by weight based on the total blending amount % High refractive index photocurable resin composition.   The high refractive index photocurable resin composition according to claim 1, wherein the polyfunctional acrylate oligomer (A) having a refractive index of 1.56 or more is an oligomer of 3-phenoxybenzyl acrylate.   The high refractive index photocurable resin composition according to claim 1 or 2, wherein the monofunctional (meth) acrylate monomer (B) containing a polar group is an acrylate monomer containing a hydroxyl group or an amino group.   The high refractive index photocurable resin composition in any one of Claims 1-3 whose urethane resin (C) which does not contain the said unsaturated group is a polyurethane of polypropylene glycol frame | skeleton. The refractive index of hardened | cured material is 1.56 or more, The high refractive index photocurable resin composition in any one of Claims 1-4.