JP2017095551A - Photocurable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent resin composition low in elasticity and shrinkage ratio, and less in change of color tone even exposed to ultraviolet and excellent in light resistance for a photocurable resin used for image display or the like.SOLUTION: There is provided a photocurable resin composition containing a compound having a (meth)acrylic group having hydrogenated polybutadiene or polyisoprene skeleton (A), a polybutadiene or polyisoprene oligomer having number average molecular weight of 500 to 5,000 and having a hydroxyl group at a terminal and/or double bond hydrogenated (B), a monofunctional (meth)acrylic acid ester monomer (C) and a photoinitiator (D).SELECTED DRAWING: None

Description

The present invention is a photocurable resin used for image display, etc., in addition to having a low elastic modulus and shrinkage, and a transparent resin composition excellent in light fastness characteristics with little change in color tone even when exposed to ultraviolet rays, In addition, the present invention relates to a touch panel or a flat panel display including a display body and an optical member bonded together.

  Acrylic photocurable resins are used in many fields in order to give special performance to the surface of plastic films and plastic moldings. For example, hard coat films that are coated on a PET (polyethylene terephthalate) film to give high hardness are used in large quantities in touch panel products, and adhesive films that give viscosity to PET films are manufacturing processes for flat panel display products. But it is used in large quantities.

  Acrylic resins are also used in various applications, taking advantage of their characteristics of transparency and fast curing, in fields other than the field of applying special performance by applying a thin film to the plastic surface. For example, in an image display such as a smartphone or a touch panel, such an acrylic transparent resin is used 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 member that protects the image display member. A technique has been developed in which the air layer between the image display member and the cover member is eliminated by filling and bonding to prevent a decrease in contrast and brightness. (Patent Document 1).

In such applications, if the shrinkage of curing is large, the touch panel and display screen may be deformed, and if the adhesive strength to the adherend is insufficient, the adhesive surface may peel off due to the difference in thermal expansion and hygroscopicity of the material. Improvements to these have been made, and the level has been improved to a level where there is no practical problem. (Patent Document 2) However, when the use time is long and the exposure to ultraviolet rays takes a long time, there is a problem that the resin is yellowed or the color tone is changed, and measures for these have been demanded. .

JP-A-2005-55641 Patent No. 5563983

The present invention is a photocurable resin used for image display and the like, and provides a transparent resin composition excellent in light resistance, having a low elastic modulus and a low shrinkage rate, and having a small color change even when exposed to ultraviolet rays. There is to do.

The invention according to claim 1 is a compound (A) having a (meth) acrylic group having a hydrogenated polybutadiene or polyisoprene skeleton, a number average molecular weight of 500 to 5,000, a hydroxyl group at the terminal and / or two. A photocurable resin composition comprising a polybutadiene or polyisoprene oligomer (B) hydrogenated with a heavy bond, a monofunctional (meth) acrylic acid ester monomer (C), and a photopolymerization initiator (D). provide.

According to a second aspect of the present invention, the compound (A) having a (meth) acryl group having a hydrogenated polybutadiene or polyisoprene skeleton is a urethane acrylate having a number average molecular weight of 3,000 to 50,000. 1 photocurable resin composition is provided.

  The invention according to claim 3 provides the photocurable resin composition according to claim 1, wherein the monofunctional (meth) acrylic acid ester monomer (C) is a compound having a viscosity of 500 mPa · s or less.

  Invention of Claim 4 provides the photocurable resin composition of Claims 1-3 which further contains carboxylic acid ester with a viscosity of 500 mPa * s or less as a plasticizer (E).

The invention according to claim 5 is characterized in that the color difference after irradiation with UVB for 500 hours is 0.5 or less with respect to the initial value of chromaticity b * value in a cured product having a thickness of 1 mm. A functional resin composition is provided.

Invention of Claim 6 provides the touch panel or flat panel display containing the photocurable resin composition of any one of Claims 1-5, a display body, and an optical member.

The photo-curing resin of the present invention is excellent in light resistance property that the change in color tone is small even when exposed to ultraviolet rays, in addition to the low elastic modulus and shrinkage, and between the image display member and the cover member protecting it. It is useful as a transparent resin to be filled in.

  The present invention will be described in detail below.

The composition of the present invention comprises a compound (A) having a (meth) acrylic group having a hydrogenated polybutadiene or polyisoprene skeleton, a number average molecular weight of 500 to 5,000, a hydroxyl group at the end, and / or Or a polybutadiene or polyisoprene oligomer (B) in which a double bond is hydrogenated, a monofunctional (meth) acrylic acid ester monomer (C), and a photopolymerization initiator (D). In the present specification, (meth) acrylate includes both acrylate and methacrylate.

The (A) used in the present invention has a structure in which a (meth) acryl group is directly bonded to hydrogenated polybutadiene or polyisoprene, and a urethane bond obtained by reacting an isocyanate with a hydrogenated polybutadiene or polyisoprene diol. Although there are urethane acrylates containing and having a (meth) acryl group bonded to the terminal, urethane acrylates having both toughness and extensibility are preferred. By hydrogenating a polybutadiene or polyisoprene skeleton, a highly reactive double bond is eliminated, and the light resistance against ultraviolet rays or the like can be remarkably improved.

Examples of the isocyanate used in the urethane acrylate include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Further, the number average molecular weight of the urethane acrylate is preferably 3,000 to 50,000. By setting the number to 3,000 or more, sufficient cohesive force can be secured, and by setting the number to 50,000 or less, workability is improved. It can be easily adjusted to a suitable viscosity. The number average molecular weight can be measured by gel permeation chromatography (column: TSKgel SuperHZ1000, SuperHZ2000, SuperHZ3000 4.6 * 150 each, eluent: tetrahydrofuran, standard sample: TSK polystyrene standard).

The blending amount of (A) with respect to 100 parts by weight of the total composition is 10 to 50 parts by weight. By making it 10 parts by weight or more, sufficient cohesive force and film strength can be secured, and by making it 50 parts by weight or less. Internal stress can be controlled low. Examples of commercially available hydrogenated butadiene-based urethane acrylates include Excelate RX 71-25 (trade name: manufactured by Asia Kogyo Co., Ltd.) and Urethane Acrylate 13-275 (trade name: manufactured by Rahn), and the like. May be.

  Said (B) used by this invention is a main material which comprises a resin film with (A), and has a role which gives a softness | flexibility to a film | membrane and relieve | moderates internal stress, without participating in reaction. You may mix | blend individually or in combination of 2 or more types of oligomers. If an oligomer that does not contain a hydroxyl group at the end and does not hydrogenate the double bond is used, the compatibility deteriorates and the light resistance decreases, so at least the terminal has a hydroxyl group or the double bond is hydrogenated. The structure must be added. The number average molecular weight is 500 to 5,000. If the number average molecular weight is less than 500, sufficient flexibility cannot be ensured.

The blending amount of (B) with respect to 100 parts by weight of the total composition is preferably 20 to 60 parts by weight. By blending in this range, a sufficient balance between flexibility and hardness of the film can be maintained. Commercially available products include GI-1000 (trade name: manufactured by Nippon Soda Co., Ltd.), Polyip (trade name: manufactured by JX Nippon Oil & Energy Corporation), and the like.

  The monofunctional (meth) acrylic acid ester monomer (C) used in the present invention is blended to dilute (A) and (B) and simultaneously increase the curing reactivity. Examples include alkyl (meth) acrylates, aromatic (meth) acrylates, and those (meth) acrylates containing polar groups such as hydroxyl groups and amino groups. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate as alkyl (meth) acrylate ) Acrylate, ethylhexyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, isobornyl acrylate and the like.

Examples of the aromatic (meth) acrylate include phenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, methylphenoxyethyl acrylate, phenoxydiethylene glycol acrylate, and phenoxy polyethylene glycol acrylate. Further, the hydroxyl group-containing monomer includes 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. Examples of the monomer contained include acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, and acryloylmorpholine. These monomers may be used independently and may use 2 or more types together. In order to easily adjust the viscosity of the blend, the viscosity is desirably 500 mPa · s or less. Further, the blending amount with respect to 100 parts by weight of the total composition is desirably 10 to 40 parts by weight, and by making it 10 parts by weight or more, quick curability can be obtained, and by making it 40 parts by weight or less, the shrinkage rate can be controlled small. it can.

  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. It is preferable to mix 0.1 to 5% by weight with respect to the radically polymerizable component.

  The photocurable resin composition of the present invention may further contain an ester compound obtained by synthesizing a carboxylic acid and a higher alcohol as a plasticizer (E) that imparts flexibility to the cured film. Examples include phthalic acid esters, isophthalic acid esters, adipic acid esters, benzoic acid esters, etc., and these may be used alone or in combination of two or more. In order to easily adjust the viscosity of the blend, the viscosity is preferably 500 mPa · s or less, and an aliphatic carboxylic acid having good compatibility is preferable. The compounding amount with respect to 100 parts by weight of the total composition is 30 parts by weight or less, and sufficient flexibility and long-term reliability can be secured at 30 parts by weight or less. As a commercial item, there is Exepar EH-S (trade name: manufactured by Kao Corporation, 2-ethylhexyl stearate) and the like.

Moreover, the photocurable resin composition of this invention can improve the adhesiveness to glass and a plastics by mix | blending the tackifier (F) which has a softening point in 80 to 150 degreeC. For example, there are rosin resins, terpene resins, petroleum resins, styrene resins, coumarone indene resins, alkylphenol resins, etc. Among these, fully hydrogenated petroleum resins are preferable from the viewpoint of improving compatibility and light resistance. These may be used alone or in combination of two or more. The blending amount with respect to 100 parts by weight of the total composition is 40 parts by weight or less, and examples of commercially available products include Alcon M-90 (trade name: Arakawa Chemical Industries, Ltd., fully hydrogenated petroleum resin).

In addition, the photocurable resin composition of the present invention is an additive such as an antioxidant, a flame retardant, a filler, a silane coupling agent, a polymerization stopper, and a colorant, as long as the performance is not impaired. Can also be used in combination.

The photocurable resin composition of the present invention can be used as an adhesive for bonding a display body such as a touch panel or a flat panel display and an optical member for protecting the display body. Specific examples of the optical member include a protective sheet and a protective plate. Examples of the material include PET, COP (cycloolefin polymer), PMMA (polymethyl methacrylate), PC (polycarbonate), and glass. The display body and the optical member bonded together with the photocurable resin composition of the present invention can be incorporated into an electronic device such as a mobile phone, a tablet terminal, a digital camera, a TV, and a personal computer monitor as a display panel for images and the like. .

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 a compound (A) having a (meth) acrylic group having a hydrogenated polybutadiene or polyisoprene skeleton, Excellate RX71-44 (trade name: manufactured by Asia, hydrogenated butadiene-based urethane acrylate, Mw. 5,500), GI-1000 (trade name: manufactured by Nippon Soda Co., Ltd., terminal hydroxyl group) as a polybutadiene or polyisoprene oligomer (B) having a number average molecular weight of 500 to 5,000, containing a hydroxyl group at the terminal and / or hydrogenating a double bond Containing hydrogenated polybutadiene, Mw. 1,600) as monofunctional (meth) acrylic acid ester monomer (C), light acrylate IB-XA (trade name: Kyoeisha Chemical Co., Ltd., isobornyl acrylate) and 4- HBA (trade name: Osaka Organic Chemical Industry, 4-hydroxybutyl) Acrylate) as a plasticizer (E) for imparting flexibility to the cured film, Hexamol DINCH (trade name: 1,2-cyclohexanedicarboxylic acid diisononyl ester, manufactured by BASF Japan Ltd.) as a photopolymerization initiator (D) Irgacure 184 (trade name: manufactured by BASF Japan) and Lucirin TPO (trade name: manufactured by BASF Japan) were stirred until they were uniformly dissolved with the formulation shown in Table 1 to prepare a photocurable transparent resin composition of Example 1. Here, Mw. And number average molecular weight.

Examples 2-8
In addition to the materials used in Example 1, Excelate RX71-25 (trade name: hydrogenated butadiene urethane acrylate, Mw.20,000, manufactured by Asia Industries) and Urethane Acrylate 13-275 (trade name: Rahn, hydrogenated butadiene urethane acrylate, Mw. 10,500) as (B) Polyip (trade name: manufactured by JX Nippon Mining & Energy, terminal hydroxyl group-containing polyisoprene, Mw. 3,000) And HV-100 (trade name: manufactured by JX Nippon Oil & Energy Corporation, polybutene, Mw. 920), (C) light acrylate LA (trade name: manufactured by Kyoeisha Chemical Co., Ltd., lauryl acrylate), Exepar EH-S (trade name: manufactured by Kao Corporation, 2-ethylhexa stearate as (E) Example 2-8 in which Alcon P-90 (trade name: manufactured by Arakawa Chemical Industry Co., Ltd., fully hydrogenated petroleum resin) as a tackifier (F) was uniformly dissolved in the formulation shown in Table 1. The photocurable transparent resin composition was prepared.

Comparative Examples 1-5
In addition to the materials used in the examples, UC-203 having a polyisoprene skeleton (trade name: manufactured by Kuraray Co., Ltd., non-hydrogenated polyisoprene trimethacrylate, Mw. 33,000) was used, and a polybutadiene skeleton had a hydroxyl group at the terminal. Polyester 110 (trade name: manufactured by Evonik Japan, non-hydrogenated low molecular weight polybutadiene, Mw.2,200), FA-512M (trade name: manufactured by Hitachi Chemical Co., Ltd., dicyclopentenyloxyethyl methacrylate) as a monofunctional acrylate Was stirred until the Alcon M-90 (trade name: Arakawa Chemical Industries, Ltd., partially hydrogenated petroleum resin) was uniformly dissolved in the formulation shown in Table 1 as (F). A transparent resin composition was prepared.

Table 1

The evaluation method was as follows.

Preparation of measurement sample A A cured resin composition was applied to a thickness of 1 mm on a white plate glass (manufactured by Matsunami Glass Industry Co., Ltd.) having a thickness of 1 mm, and bonded with white glass having a thickness of 1 mm, Fusion UV Systems Japan A measurement sample A was prepared by using an electrodeless UV irradiation apparatus F300S / LC-6B manufactured by UV irradiation and curing with a D bulb so that the output was 100 mW / cm 2 and the integrated light amount was 3000 mJ / cm 2.

Preparation of measurement sample B A photocurable resin composition was applied to a thickness of 1 mm on a 100 μm thick PET film (polyethylene teretalate, manufactured by Toyobo Co., Ltd., E7006) coated with a release agent. Bonded with a PET film with a thickness of 100 μm, and cured by UV irradiation using an electrodeless UV irradiation device F300S / LC-6B manufactured by Fusion UV Systems Japan, with an output of 100 mW / cm 2 and an integrated light quantity of 3000 mJ / cm 2 using a D bulb. The cured product was peeled off from the PET film to prepare a measurement sample B.

Total light transmittance: based on JISK 7361, Haze-GARD2
Sample A was measured using (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the value obtained by subtracting the glass portion sandwiching the resin was used.

  b * Value: In accordance with JIS K0062, sample A was measured using SD6000 Spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.), and the value obtained by subtracting the glass portion sandwiching the resin was used.

  Color change: Discoloration of the peripheral part of sample A was confirmed visually.

  UVB test: Sample A was irradiated for 500 hours under the conditions of 310 nm and 0.63 W / m 2 using QUV (manufactured by Q-LAB), and the total light transmittance, b * value, and color change were confirmed. Regarding the b * value, the color difference change rate before and after the UVB test was determined to be 0.5 or less.

Elastic modulus: The storage elastic modulus in shear shear mode at 25 ° C. and 1 Hz was measured by using HAAKE RheoStress 600 (manufactured by Thermo Scientific) using Sample B having a diameter of 20 mmΦ, and passed 1.0E + 05 Pa or less.

Curing shrinkage rate: Based on JIS K6833, the density of the liquid of the cured resin composition was measured using a specific gravity cup, and the density of the cured product of sample B was measured using the Archimedes method, and the volume shrinkage rate was calculated by the following formula. . A cure shrinkage of 2.5% or less was accepted.
Curing shrinkage [%] = (cured material density−liquid density) / cured material density × 100

Evaluation results <br/> Table 2

Each resin composition of the examples had good total light transmittance, b * value change, and color change after exposure to ultraviolet rays, and also had good results in curing shrinkage rate and elastic modulus within the specified range.

On the other hand, Comparative Example 1 containing (A) without hydrogenation could not be whitened and evaluated, and Comparative Examples 2 and 3 had a large b * value change after UVB irradiation, and discoloration was observed. Furthermore, Comparative Example 4 containing no oligomer (B) cannot be evaluated by whitening, and Comparative Example 5 also has a large change in b * value after UVB irradiation, in addition to a large elastic modulus and cure shrinkage, both of which are the invention of the present application. It was not suitable for.

The invention of the present application is useful as a photo-curable resin used for an image display or the like having excellent light resistance characteristics, in addition to having a low elastic modulus and a low shrinkage rate, and having a small change in color tone even when exposed to ultraviolet rays.

Claims (6)

Hydrogenated polybutadiene or compound (A) having a (meth) acryl group having a polyisoprene skeleton, and polybutadiene having a number average molecular weight of 500 to 5,000, containing a hydroxyl group at the terminal and / or hydrogenating a double bond Or the photocurable resin composition containing a polyisoprene-type oligomer (B), a monofunctional (meth) acrylic acid ester monomer (C), and a photoinitiator (D).   The photocurable resin composition according to claim 1, wherein the hydrogenated polybutadiene or compound (A) having a (meth) acryl group having a polyisoprene skeleton is a urethane acrylate having a number average molecular weight of 3,000 to 50,000. . The photocurable resin composition according to claim 1 or 2, wherein the monofunctional (meth) acrylic acid ester monomer (C) is a compound having a viscosity of 500 mPa · s or less. The photocurable resin composition of Claims 1-3 which further contains carboxylic acid ester with a viscosity of 500 mPa * s or less as a plasticizer (E). The photocurable resin composition according to claim 1, wherein a color difference after irradiation with UVB for 500 hours is 0.5 or less with respect to an initial value of chromaticity b * value in a cured product having a thickness of 1 mm. A touch panel or flat panel display comprising the photocurable resin composition according to claim 1, a display body, and an optical member.