JP2019189712A - Ultraviolet curable adhesive composition, lamination method and article using the same - Google Patents

Abstract

To provide an ultraviolet curable adhesive composition excellent in durability under high temperature, low temperature, and high temperature and high humidity environment, having viscosity suitable for application, and high in transparency, and a manufacturing method of an optical member using the same.SOLUTION: The above described problem can be solved by an ultraviolet curable adhesive composition, used for laminating at least 2 optical substrates, containing a photopolymerizable oligomer (A), a (meth)acrylate monomer (B), and a copolymerizable (meth)acrylate monomer (C), and having transmissivity of 450 to 800 nm of a cured article of 85% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultraviolet curable adhesive composition using at least two optical substrates for bonding, and a method for producing an optical member using the same.

  In recent years, display devices that allow screen input by attaching a touch panel to a display screen of a display device such as a liquid crystal display, a plasma display, or an organic EL display are widely used. In this touch panel, two substrates such as a glass plate on which a transparent electrode is formed or a resin film are bonded to each other with a slight gap, and if necessary, a glass is formed on the touch surface. Or it has the structure which bonded the transparent protection board made from resin.

  In particular, unlike consumer devices such as mobile personal computers and smart phones, touch panels used for in-vehicle displays are required to have durability with higher required quality. In addition, with the increase in the size of in-vehicle displays, a resin substrate has been increasingly used for the front plate in consideration of ensuring safety at the time of breakage and versatility of design. When a resin substrate is used for the front plate, the resin substrate is deformed by expansion or contraction due to a temperature change, while there is almost no deformation on the module side. For this reason, the adhesive sheet for consumer use or the adhesive causes problems such as foaming and peeling in the reliability test at high temperature and high temperature and high humidity; and the optical member bonded in the reliability test at low temperature is warped. There is. In addition, it is common to heat-treat the resin substrate before bonding with an adhesive, but this is because the moisture present in the resin substrate becomes outgas and bubbles are generated at the interface between the substrate and the adhesive. This is because defects such as peeling are likely to occur.

  In this regard, as a conventional technique, several adhesives for touch panels have been proposed as disclosed in Patent Document 1. Therefore, it has been attempted to divert the adhesive for bonding substrates prepared for small-sized displays for consumer use. However, when the adhesive for bonding substrates developed for a conventional small-sized display is diverted, when a low temperature environment such as -40.degree. C. and a high temperature environment such as 95.degree. There was a concern that peeling at the interface between the substrate on the side and the cured product layer of the adhesive for bonding and warping of the display due to temperature change may occur. For this reason, in addition to the characteristics required for small consumer displays such as low dielectric constant, low shrinkage, and high transmittance, the interface between the substrate and the cured adhesive layer can be used even if the environment changes at a higher temperature or lower temperature. There has been a strong demand for the development of an in-vehicle display adhesive that does not peel off or warp. Furthermore, since an adhesive that does not require a heat treatment step of the resin substrate can be produced efficiently and inexpensively, development of such a more reliable adhesive has been demanded.

Patent No. 5563983

  The present invention is an ultraviolet curable adhesive composition that is excellent in durability under high temperature, low temperature, and high temperature / high humidity environments, has a viscosity suitable for application, and has high transparency, and an optical member using the same It is an object to provide a manufacturing method.

The present inventors have completed the present invention as a result of intensive studies in order to solve the above problems. That is, the present invention relates to the following (1) to (12).
(1)
An ultraviolet ray comprising a resin composition used for laminating at least two optical substrates and containing a photopolymerizable oligomer (A), a (meth) acrylate monomer (B), and a copolymerizable (meth) acrylate monomer (C) A curable adhesive composition.
(2)
The copolymerizable (meth) acrylate monomer (C) is selected from the group consisting of methyl (meth) methacrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, isobornyl (meth) acrylate, and hydroxyethyl (meth) acrylate. The adhesive composition according to (1) above, which is a copolymerizable (meth) acrylate monomer having at least one kind of skeleton.
(3)
(1) The photopolymerizable oligomer (A) is a urethane (meth) acrylate having at least one skeleton selected from the group consisting of polypropylene, polybutadiene, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene. The adhesive composition described in 1.
(4)
The adhesive composition according to (1), wherein the (meth) acrylate monomer (B) is a mixture of two or more monomers selected from C8-C30 alkyl (meth) acrylate monomers.
(5)
The (meth) acrylate monomer (B) is a mixture of one or more monomers each selected from a C8-C30 linear alkyl (meth) acrylate monomer and a C10-C30 branched alkyl (meth) acrylate monomer. The adhesive composition according to any one of (1) or (4).
(6)
The adhesive composition according to any one of (1) to (5), wherein a transmittance of 450 to 800 nm of the cured product is 85% or more.
(7)
The optical base material is one or more materials selected from PET, PC, PEN, cycloolefin, PMMA, a composite of PC and PMMA, COC, COP, polyimide, plastic, glass, and tempered glass. The adhesive composition according to (1) above.
(8)
A substrate comprising at least one material selected from the group consisting of PET, PC, PEN, cycloolefin, PMMA, a composite of PC and PMMA, COC, COP, polyimide, plastic, glass, and tempered glass; The adhesive composition according to (1), which is a film; and a substrate and a film on which a transparent electrode is formed; or a laminate in which a plurality of the substrates and films are laminated.
(9)
The optical substrate is selected from an icon sheet, a decorative sheet, a protective sheet, a glass and polarizing plate LCD, an organic EL display, a micro LED display, an EL illumination, a quantum dot display, an electronic paper, and a plasma display. The adhesive composition according to (1), wherein
(10)
The adhesive composition according to any one of (1) to (9), which is used for bonding an in-vehicle display.
(11)
Hardened | cured material obtained by irradiating an active energy ray to the adhesive composition as described in any one of said (1)-(10), and hardening an adhesive composition.
(12)
The manufacturing method of the optical member with which at least 2 optical base material pasted which has the following processes 1-2.
Step 1:
Applying the adhesive composition according to any one of (1) to (10) above to at least one of the two optical substrates to form an adhesive coating layer, The process of obtaining the optical base material which has a layer of hardened | cured material by irradiating a coating layer with an ultraviolet-ray.
Step 2:
The other optical substrate that does not have the cured product layer of the two optical substrates is bonded to the cured product layer of the optical substrate obtained in step 1, or
The process of bonding together the layer of the hardened | cured material of two optical base materials each obtained by the process 1 and having a layer of hardened | cured material.

  INDUSTRIAL APPLICABILITY According to the present invention, an ultraviolet curable adhesive composition excellent in durability under high temperature, low temperature, and high temperature / high humidity environments, having a viscosity suitable for coating, and having high transparency, and an optical member using the same A manufacturing method could be provided.

It is process drawing which shows 1st Embodiment of the manufacturing method of this invention. It is process drawing which shows 2nd Embodiment of the manufacturing method of this invention. It is process drawing which shows 3rd Embodiment of the manufacturing method of this invention. It is the schematic of the optical member obtained by this invention.

In the present specification, “%” and “part” are based on weight unless otherwise specified.
In the present specification, unless otherwise specified, “(meth) acrylate” includes both “methacrylate” and “acrylate”, and the same applies to “(meth) acryloyl” and the like.
In the present specification, the “adhesive composition” may be referred to as “adhesive”.
Further, in this specification, the “cured product” means a cured product of the adhesive cured by irradiating the adhesive with ultraviolet rays.

[Adhesive composition]
The adhesive composition may contain other additives used for optics in addition to the components described above. When the adhesive contains other additives, a substance that does not lower the transparency of the cured product to the extent that it cannot be used for optics is preferable.
The adhesive has a light transmittance of 450 to 800 nm (meaning an average transmittance) of 85% or more when a cured product layer having a thickness of 200 μm is prepared. , Preferably 90% or more.

[Photopolymerized oligomer (A)]
The photopolymerizable oligomer (A) is not particularly limited as long as it is an oligomer having a weight average molecular weight of 7000 to 100,000. Examples of such oligomers include (meth) acrylate oligomers. Among them, urethane (meth) acrylate is preferable.
The (meth) acrylate oligomer is a polyalkylene (preferably a poly C2-C4 alkylene, more preferably a poly C2-C3 alkylene, more preferably a polypropylene) from the viewpoint of adhesive strength, adhesion to a substrate and resistance to peeling. (Meth) acrylate oligomers having one or more skeletons selected from the group consisting of skeletons of polybutadiene, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene are preferred. Moreover, it is preferable that urethane (meth) acrylate also has the same skeleton as the (meth) acrylate oligomer.
(Meth) acrylate oligomers and urethane (meth) acrylates can be obtained as commercial products or synthesized. For example, examples of the (meth) acrylate oligomer having a polyisoprene skeleton include UC-208 manufactured by Kuraray Co., Ltd.

The weight average molecular weight of the photopolymerizable oligomer (A) is usually from 7000 to 100,000, preferably from 9000 to 80000, more preferably from 11000 to 70000, still more preferably from 15000 to 50000, sometimes from 15000 to 4000, particularly preferably from 20000. 25000.
The numerical value of the molecular weight distribution ([weight average molecular weight (Mw)] / [number average molecular weight (Mn)]) is preferably 1.5 or more. By setting it as such a photopolymerizable oligomer, there exists a tendency for the softness | flexibility of hardened | cured material and the sclerosis | hardenability of an adhesive agent to become favorable.
The content of the photopolymerizable oligomer (A) in the total weight of the adhesive is usually 25 to 70%, preferably 30 to 60%, more preferably 35 to 50%.
By setting it as content of the said photopolymerizable oligomer (A), the hardened | cured material of an adhesive agent can show the high adhesiveness with a base material, and favorable elastic property. For this reason, for example, when the substrate is deformed due to a temperature change or the like, the cured product can also respond to the deformation, so that it is difficult to cause peeling from the substrate. Such an effect can be satisfactorily exhibited even in a display having a large base material bonding area, for example, an in-vehicle display.
The adhesive may further contain a photopolymerizable oligomer having a weight average molecular weight other than 7000 to 100,000 within a range not impairing the characteristics of the present invention.

The urethane (meth) acrylate is preferably a reaction product of polyhydric alcohol, polyisocyanate and (meth) acrylate having a hydroxy group.
Examples of the polyhydric alcohol include polybutadiene glycol, hydrogenated polybutadiene glycol, polyisoprene glycol, hydrogenated polyisoprene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4 -C2-C10 alkylene glycol such as butanediol and 1,6-hexanediol; triol such as trimethylolpropane and pentaerythritol; and cyclic skeleton such as tricyclodecanedimethylol and bis-[[hydroxymethyl]]-cyclohexane Alcohol (preferably a polyol having a cyclic alkane, more preferably a diol having a cyclic alkane, more preferably a C3-C14 cyclic alkane diol, particularly preferably a C6- 10 cyclic alkanediols); a reaction product of these polyhydric alcohols and polybasic acids (for example, succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydrophthalic anhydride, etc.) Polyester polyol; Caprolactone alcohol obtained by reaction of polyhydric alcohol and ε-caprolactone; Polycarbonate polyol which is a reaction product of C2-C10 alkylene glycol and carbonate selected from alkyl and aryl carbonate (for example, 1,6-hexanediol) Polycarbonate diol obtained by the reaction of benzene with diphenyl carbonate); polyether polyol (preferably polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.) Poly C2-C4 alkylene glycol; poly C2-C4 alkylene-modified bisphenol compounds such as ethylene oxide-modified bisphenol A) and the like.
The polyhydric alcohol is preferably selected from the following group. That is, from the viewpoint of adhesive strength and moisture resistance, poly C2-C4 alkylene glycol (preferably polypropylene glycol), polybutadiene glycol, hydrogenated polybutadiene glycol, polyisoprene glycol, hydrogenated polyisoprene glycol are preferred; transparency and flexibility In consideration of the viewpoint, poly C2-C4 alkylene glycol, hydrogenated polybutadiene glycol, and hydrogenated polyisoprene glycol are preferable; in consideration of discoloration such as heat-resistant coloring property, poly C2-C4 alkylene glycol and hydrogenated polybutadiene glycol are preferable. A poly C2-C4 alkylene glycol is preferable from the viewpoint of compatibility with other components contained in the adhesive.
Although the weight average molecular weight of a polyhydric alcohol is not specifically limited, Usually, 500-10000, Preferably it is 1000-5000, More preferably, it is 2000-4000, More preferably, it is 2500-3500.

The polyisocyanate is not particularly limited as long as it is a compound having two or more isocyanates. Among them, organic polyisocyanate is preferable.
Examples of the organic polyisocyanate include polyisocyanates selected from isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4′-diisocyanate, dicyclopentanyl isocyanate, and the like. Among these, isophorone diisocyanate is preferable from the viewpoint of toughness.

  Examples of the (meth) acrylate having a hydroxy group include hydroxy C2-C4 alkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate, dimethylolcyclohexyl mono ( A (meth) acrylate, a hydroxycaprolactone (meth) acrylate, a hydroxy group terminal polyalkylene glycol (meth) acrylate, etc. can be used.

  Examples of the method for synthesizing the urethane (meth) acrylate include the following methods. That is, mixing is performed such that the isocyanate group of the organic polyisocyanate is 1.1 to 2 equivalents (preferably 1.1 to 1.5 equivalents) per equivalent of hydroxy groups of the polyhydric alcohol, and 70 to 90 ° C. To synthesize urethane oligomers. The resulting urethane oligomer is mixed so that the hydroxyl group of the (meth) acrylate having a hydroxy group is 1 to 1.5 equivalents per equivalent of the isocyanate group, and the target urethane is reacted at 70 to 90 ° C. This is a method for obtaining (meth) acrylate.

[(Meth) acrylate monomer (B)]
The (meth) acrylate monomer (B) is not particularly limited as long as it is a compound different from the photopolymerizable oligomer (A). Preferably, the (meth) acrylate monomer which has one (meth) acryloyl group in a molecule | numerator is mentioned.
From the viewpoint of curability, the (meth) acrylate monomer (B) is preferably an acrylate monomer rather than a methacrylate monomer.
Examples of the (meth) acrylate monomer having one (meth) acryloyl group in the molecule include octyl (meth) acrylate, isooctyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, and isodecyl (meth). C8-C30 alkyl (meth) acrylate (flexible and dilutable) such as acrylate, stearyl (meth) acrylate, cetyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl (meth) acrylate, tridecyl (meth) acrylate From the viewpoint, C8-C18 alkyl (meth) acrylate is preferable; in view of volatility and reactivity, normal octyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate Benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acryloylmorpholine, cyclic trimethylolpropane formal acrylate, phenyl glycidyl (meth) acrylate, triacrylate, lauryl (meth) acrylate and isostearyl (meth) acrylate are preferred. Cyclodecane (meth) acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl acrylate 2-ethyl-2-adamantyl acrylate, 1-adamantyl methacrylate, polypropylene oxide modified nonylphenyl (meth) acrylate (Meth) acrylate having a cyclic skeleton such as a rate, dicyclopentadieneoxyethyl (meth) acrylate, C3-C7 alkyl (meth) acrylate having a hydroxy group, ethoxydiethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polypropylene Polyalkylene glycol (meth) acrylates such as oxide-modified nonylphenyl (meth) acrylate (preferably poly C2-C4 alkylene glycol (meth) acrylate, more preferably poly C2-C3 alkylene glycol (meth) acrylate); ethylene oxide-modified phenoxylation Phosphoric acid (meth) acrylate, ethylene oxide modified butoxylated phosphoric acid (meth) acrylate and ethylene oxide modified octyloxygenated phosphorus Examples include (meth) acrylate monomers such as acid (meth) acrylate and caprolactone-modified tetrafurfuryl (meth) acrylate.

From the viewpoint of adhesiveness, (meth) acrylate monomer (B) includes (meth) acrylate monomer having an alicyclic ring or a heterocyclic ring. In these, the (meth) acrylate monomer which has an alicyclic ring is preferable. Monofunctional (meth) acrylate monomers are preferred. Specific examples thereof include dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl acrylate, 2-ethyl-2- (Meth) acrylate monomers having an alicyclic ring such as adamantyl acrylate, 1-adamantyl methacrylate, dicyclopentadieneoxyethyl (meth) acrylate, dicyclopentenyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, acryloylmorpholine, cyclic tri Examples include (meth) acrylate monomers having a heterocycle such as methylolpropane formal acrylate.
Among these, from the viewpoint of compatibility with other components contained in the adhesive, it is preferably selected from the group consisting of acryloylmorpholine, dicyclopentanyl (meth) acrylate, and isobornyl (meth) acrylate; acryloylmorpholine And more preferably selected from dicyclopentanyl (meth) acrylate.

Moreover, the (meth) acrylate monomer which has a hydroxyl group is preferable as a (meth) acrylate monomer (B) from a viewpoint of the tolerance to at least one of high temperature and high humidity.
Examples of the (meth) acrylate monomer having a hydroxy group include hydroxy C2-C4 alkyl (meth) acrylates such as hydroxybutyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxyethyl (meth) acrylate.
When the (meth) acrylate monomer (B) contains a (meth) acrylate monomer having a hydroxy group, the content of the (meth) acrylate monomer having a hydroxy group in the total weight of the adhesive is usually 2 to 10%. , Preferably 3 to 7%.

The (meth) acrylate monomer (B) is preferably a mixture of two or more monomers selected from C8-C30 alkyl (meth) acrylate monomers.
By setting it as such a mixture, the adhesiveness to the base material of hardened | cured material can be improved, keeping the dielectric constant of an adhesive agent low. Moreover, it can be set as the viscosity suitable for application | coating, and the sclerosis | hardenability and hardening rate of an adhesive agent can also be adjusted suitably.
Two or more types of monomers selected from the C8-C30 alkyl (meth) acrylate monomers are C8-C30 linear alkyl (meth) acrylate (preferably C10-C20 linear alkyl (meth) acrylate) monomers and C10- Monomers selected from one or more of C30 branched chain alkyl (meth) acrylate (preferably C13-C25 branched chain alkyl (meth) acrylate, more preferably C15-C20 branched chain alkyl (meth) acrylate) monomers are preferred. .
By using the polymerizable oligomer (A) in combination with such a (meth) acrylate monomer (B), an adhesive composition that exhibits the effect of the present invention more remarkably, and a cured product thereof Can provide.
The content of the C8-C30 linear alkyl (meth) acrylate monomer and the C10-C30 branched alkyl (meth) acrylate monomer in the total weight of the adhesive is preferably smaller in the former.

The (meth) acrylate monomer (B) is optionally
A first group of the C8-C30 alkyl (meth) acrylate monomers;
A second group of (meth) acrylate monomers having an alicyclic or heterocyclic ring, and
Preferred is one monomer from two or more groups, ie, a mixture of two or more different monomers, selected from three groups of the third group consisting of (meth) acrylates having hydroxy groups; More preferred are at least one monomer from the group, i.e. a mixture of three or more different monomers. When the (meth) acrylate monomer (B) contains a (meth) acrylate monomer having an alicyclic ring, the adhesion tends to be good.
The total content of the (meth) acrylate monomer (B) in the total weight of the adhesive is usually 10 to 60%, preferably 15 to 55%, more preferably 20 to 45%.

[Copolymerizable (meth) acrylate monomer (C)]
As the copolymerizable (meth) acrylate monomer (C), a monomer (preferably, a side chain having 20 or more carbon atoms in the side chain when it becomes a (meth) acrylic (co) polymer by polymerization) A monomer that forms a C20 or higher chain alkyl group in the chain). By using the copolymerizable (meth) acrylate monomer (C), a (meth) acrylic (co) polymer can be used as a graft copolymer. Therefore, the characteristics of the main chain and side chain of the graft copolymer can be changed depending on the selection and blending ratio of the copolymerizable (meth) acrylate monomer (C) and other monomers.

The copolymerizable (meth) acrylate monomer (C) is selected from the group consisting of methyl (meth) methacrylate / butyl (meth) acrylate / isobutyl (meth) acrylate / isobornyl (meth) acrylate / hydroxyethyl (meth) acrylate. It is a copolymerizable (meth) acrylate monomer having at least one selected skeleton.

The weight average molecular weight (Mw) of the copolymerizable (meth) acrylate monomer (C) is preferably 2000 to 30000, and more preferably 3000 or more and 20000 or less. If the weight average molecular weight (Mw) of the copolymerizable (meth) acrylate monomer (C) is 2000 or more, it is possible to reduce curing shrinkage when the adhesive is cured and to improve the adhesion to the substrate. Can do. On the other hand, if it is 30000 or less, compatibility with other components contained in the adhesive can be improved.

As the copolymerizable (meth) acrylate monomer (C), commercially available products (for example, Macromonomer AB-6 manufactured by Toa Gosei Co., Ltd.) can be appropriately used. The content of the copolymerizable (meth) acrylate monomer (C) in the total weight of the adhesive is usually 5 to 30%, preferably 10 to 20%.
By making such a range, flexibility can be imparted to the adhesive; the adhesiveness between the adhesive and the substrate can be improved; and the ambient temperature can be changed from normal to high / low. When a change occurs, the adhesive deforms according to the strain between the base material such as a glass substrate or plastic substrate (polycarbonate substrate, etc.) and the adhesive, the optical member is less warped, and it is difficult to peel off. can do. Such an effect can be satisfactorily exhibited even with an optical member having a large substrate bonding area, such as an in-vehicle optical member.

The adhesive may further contain a softening component. It does not specifically limit as a softening component, What is selected from a well-known softening component can be used according to the objective. Among them, those having good compatibility with other components contained in the adhesive are preferable.
As such a softening component, polyether polyol (preferably poly C2-C3 alkylene glycol; more preferably polyethylene glycol, polypropylene glycol, etc.), polybutadiene polyol, polyisoprene polyol, polyisoprene, hydrogenated polyisoprene, polybutadiene, Oligomers or polymers having one or more skeletons selected from hydrogenated polybutadiene and xylene skeletons, or esterified products thereof; polybutenes; phthalates; phosphates; glycol esters; citrates; Aliphatic dibasic acid esters; fatty acid esters; epoxy plasticizers; castor oil; terpene resins; hydrogenated terpene resins; rosin resins; hydrogenated rosin resins; Etc. The.
Among these, from the viewpoint of transparency, an oligomer or a polymer having one or more skeletons selected from each skeleton of hydrogenated polyisoprene and hydrogenated polybutadiene, or an esterified product thereof; polybutene; hydrogenated terpene resin Hydrogenated rosin resins; and liquid terpenes are preferred.
Further, when considering the viewpoints of adhesive strength and compatibility, each of them has one or more skeletons selected from the skeletons of hydrogenated polyisoprene and hydrogenated polybutadiene each having a hydroxy group at the terminal or side chain. Preferred are oligomers or polymers, or esterified products thereof; hydrogenated rosin resins; hydrogenated terpene resins; hydrogenated rosin resins; and liquid terpene resins. These softening components tend to improve at least one of adhesion and compatibility.
The content of the softening component in the total weight of the adhesive is usually 1 to 20%, preferably 2 to 18%, more preferably 3 to 16%, and further preferably 4 to 15%.

The adhesive may contain a photopolymerization initiator, a monomer different from the (meth) acrylate monomer (B), an epoxy (meth) acrylate, and an additive as other components as necessary. . Although it is difficult to specify the content of other components in the total weight of the adhesive, the standard is usually 0 to 10%, preferably 0 to 5%.
However, the content of the monomer different from the (meth) acrylate monomer (B) and the epoxy (meth) acrylate is not included in the above guidelines.

It does not specifically limit as a photoinitiator, A well-known photoinitiator can be used according to the objective. The adhesive preferably contains a photopolymerization initiator. The content of the photopolymerization initiator in the total weight of the adhesive is usually 0 to 10%, preferably 0.005 to 10%, more preferably 0.01 to 5%, still more preferably 0.05 to 3%. In some cases, it is preferably 0.1 to 3%. Specific examples thereof include, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine. Oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone (Irgacure 184; manufactured by BASF), 2-hydroxy-2-methyl- [4 -(1-Methylvinyl) phenyl] propanol oligomer (Esacure ONE; manufactured by Lambarti), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one ( (Irgacure 2959; manufactured by BASF) 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one (Irgacure 127; manufactured by BASF), 2 , 2-dimethoxy-2-phenylacetophenone (Irgacure 651; manufactured by BASF), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173; manufactured by BASF), 2-methyl-1- [ 4- (methylthio) phenyl] -2-morpholinopropan-1-one (Irgacure 907; manufactured by BASF), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2 -Chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, isopropyl Xanthone and the like.
Among these, from the viewpoint of curability and transparency, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl- 1-propan-1-one is preferred.
Further, the intramolecular hydrogen abstraction type photopolymerization initiator is not particularly limited. For example, oxyphenyl acetate acid methyl ester (Irgacure MBF; manufactured by BASF), oxyphenylacetic acid, 2- [2-oxo-2-phenyl] Examples thereof include oxyphenyl photopolymerization initiators such as a mixture of acetoxyethoxy] ethyl ester and oxyphenylacetic acid and 2- (2-hydroxy-ethoxy) ethyl ester (Irgacure 754; manufactured by BASF). .

  As the photopolymerization initiation assistant, amines and the like can be used in combination with the photopolymerization initiator. Examples of amines include benzoic acid 2-dimethylaminoethyl ester, dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl ester, and p-dimethylaminobenzoic acid isoamyl ester.

  Examples of the monomer different from the (meth) acrylate monomer (B) include tricyclodecane dimethylol di (meth) acrylate, dioxane glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and polytetramethylene glycol. Di (meth) acrylate, alkylene oxide modified bisphenol A type di (meth) acrylate, caprolactone modified hydroxypivalic acid neopentyl glycol di (meth) acrylate and ethylene oxide modified di (meth) acrylate phosphoric acid, trimethylolpropane tri (meth) acrylate , Trimethylol C2-C10 alkane tri (meth) acrylate such as trimethylol octane tri (meth) acrylate, trimethylolpropane polyethoxylate Trimethylol C2-C10 alkane polyalkoxy tri (meth) acrylate such as (meth) acrylate, trimethylolpropane polypropoxytri (meth) acrylate, trimethylolpropane polyethoxypolypropoxytri (meth) acrylate, tris [(meth) acryl [Iloxyethyl] isocyanurate, pentaerythritol tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate and other alkylene oxide modified trimethylolpropane tri (meth) Acrylate pentaerythritol polyethoxytetra (meth) acrylate, pentaerythritol polypropoxytetra (meth) acrylate , Pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate.

As said epoxy (meth) acrylate, the reaction material of a glycidyl ether type epoxy compound and (meth) acrylic acid is mentioned.
As the glycidyl ether type epoxy compound, a diglycidyl ether (an alkylene oxide adduct is C2-) of a bisphenol compound selected from bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F or an alkylene oxide adduct thereof. C4 alkylene oxide adducts are preferred.); Ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, etc. Diglycidyl ether of C2-C8 alkanediol; and poly C2-C4 alkylene glycol diglycidyl ether (Preferably polypropylene glycol diglycidyl ether) and the like.

Reaction of a glycidyl ether type epoxy compound and (meth) acrylic acid is performed as follows, for example.
(Meth) acrylic acid 0.9 to 1.5 equivalents (preferably 0.95 to 1.1 equivalents), reaction temperature 80 to 120 ° C., reaction time with respect to 1 equivalent of epoxy group of the glycidyl ether type epoxy compound. The reaction is performed for about 10 to 35 hours. In order to accelerate the reaction, for example, a catalyst such as triphenylphosphine, TAP, triethanolamine, tetraethylammonium chloride can be used. In order to prevent the polymerization reaction, for example, a polymerization inhibitor such as paramethoxyphenol or methylhydroquinone can also be used.

  When the adhesive contains a monomer different from the (meth) acrylate monomer (B) and one or more monomers selected from epoxy (meth) acrylate, the (meth) acrylate monomer in the total weight of the adhesive The content of the monomer different from (B) and the epoxy (meth) acrylate is usually 0.1 to 10%, preferably 0.5 to 7%, more preferably 0.5 to 4%. When the adhesive contains these monomers, the curing rate tends to increase and the hardness of the cured product tends to increase.

[Additive]
Examples of the additives include antioxidants, thixotropic agents, antifoaming agents, surface tension adjusting agents, silane coupling agents, polymerization inhibitors, leveling agents, antistatic agents, surface lubricants, fluorescent whitening agents, Examples thereof include light stabilizers.
When the adhesive contains an additive, the content of the additive in the total weight of the adhesive is usually 0.01 to 3%, preferably 0.01 to 1%, more preferably 0.02 to 0.00. 5%.
The adhesive may further contain a solvent. When the adhesive contains a solvent, the content of the solvent in the total weight of the adhesive is usually 0 to 5%, preferably 0 to 3%, more preferably 0 to 2%. By setting it as such content, sclerosis | hardenability is favorable and sufficient thickness and the hardened | cured material of uniform thickness are obtained.

  Specific examples of the antioxidant include, for example, BHT, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine , Pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3-t -Butyl-5-methyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N N-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t- Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, octylated diphenylamine, 2,4-bis [(octylthio) methyl-O-cresol, Isooctyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], dibutylhydroxytoluene and the like.

  Specific examples of the silane coupling agent include, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxy) (Cyclohexyl) ethyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, γ-mercapropropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyltrimethoxysilane, 3 -Aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N- (2- (vinylbenzylamino) ethyl) 3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane 3 Silane coupling agents such as chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane; isopropyl (N-ethylaminoethylamino) titanate, isopropyl triisostearoyl titanate, titanium di (dioctyl pyrophosphate) oxyacetate, tetra Titanium coupling agents such as isopropyldi (dioctylphosphite) titanate and neoalkoxytri (pN- (β-aminoethyl) aminophenyl) titanate; Zr-acetylacetonate, Zr-methacrylate, Zr-propionate, neo Alkoxy zirconate, neoalkoxy trisneodecanoyl zirconate, neoalkoxy tris (dodecanoyl) benzenesulfonyl zirconate, neoalkoxy tris ( Chi range aminoethyl) zirconate, neoalkoxy tris (m-aminophenyl) zirconate, ammonium zirconium carbonate, Al- acetylacetonate, Al- methacrylate, zirconium or the like Al- propionate, or aluminum coupling agent, and the like.

  Specific examples of the polymerization inhibitor include paramethoxyphenol and methylhydroquinone.

  Specific examples of the light stabilizer include, for example, 1,2,2,6,6-pentamethyl-4-piperidyl alcohol, 2,2,6,6-tetramethyl-4-piperidyl alcohol, 1,2,2, 6,6-pentamethyl-4-piperidyl (meth) acrylate (manufactured by Adeka Corporation, LA-82), tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4 -Butanetetracarboxylate, tetrakis (2,2,6,6-totramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid and 1 2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undeca Esterified product with bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) ) Carbonate, 2,2,6,6, -tetramethyl-4-piperidyl methacrylate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6) -Pentamethyl-4-piperidyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, 1,2 , 2,6,6-pentamethyl-4-piperidinyl-methacrylate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) [[3,5-bis (1,1-dimethylethyl)- 4-hydroxyphenyl] methyl] butyl malonate, decanedioic acid bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and octane Reaction product N, N ′, N ″, N ′ ″-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl ) Amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, dibutylamine 1,3,5-triazine N, N'-bis (2,2,6,6-tetra) Methyl A polycondensate of 4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [[6- (1,1,3,3- Tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6 -Tetramethyl-4-piperidyl) imino]], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, 2,2,4,4-tetramethyl- 20- (β-Lauryloxycarbonyl) ethyl-7-oxa-3,20-diazadispiro [5 · 1 · 11 · 2] heneicosan-21-one, β-alanine, N,-(2,2,6,6 -Tetramethyl-4 Piperidinyl) -dodecyl ester / tetradecyl ester, N-acetyl-3-dodecyl-1- (2,2,6,6-tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione, 2,2,4, 4-Tetramethyl-7-oxa-3,20-diazadispiro [5 · 1 · 11 · 2] heneicosan-21-one, 2,2,4,4-tetramethyl-21-oxa-3,20-diazadicyclo- [5,1,11,2] -Heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, propanedioic acid, [(4-methoxyphenyl) -methylene] -bis (1,2,2,6,6) -Pentamethyl-4-piperidinyl) ester, 2,2,6,6-tetramethyl-4-piperidinol higher fatty acid ester, 1,3-benzenedi Hindered amines such as ruboxamide, N, N′-bis (2,2,6,6-tetramethyl-4-piperidinyl), benzophenone compounds such as octabenzone, 2- (2H-benzotriazol-2-yl) -4 -(1,1,3,3-tetramethylbutyl) phenol, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- [2-hydroxy-3- (3,4,5,6-tetrahydro) Phthalimido-methyl) -5-methylphenyl] benzotriazole, 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di -T-pentylphenyl) benzotriazole, methyl 3- (3- (2H-benzotriazol-2-yl) -5-t-butyl-4- Reaction product of droxyphenyl) propionate and polyethylene glycol, benzotriazole compounds such as 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, 2,4-di-t-butyl Benzoate series such as phenyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy ] Triazine-based compounds such as phenol. Among these, a hindered amine system is preferable.

The adhesive can be obtained by mixing and dissolving the above-described components at room temperature (about 25 ° C.) to 80 ° C. Moreover, impurities can be removed by an operation such as filtration as necessary.
The viscosity of the adhesive at 25 ° C. is usually 500 to 20000 mPa · s, preferably 1000 to 10000 mPa · s, and more preferably 2000 to 8000 mPa · s. By setting it as such a viscosity, defoaming from an adhesive agent becomes easy and the applicability | paintability to a base material becomes favorable. For this reason, for example, even if it uses a dispenser with a thin diameter of a discharge part etc., application of an adhesive is possible and the application method is not limited.

  The YI value of the cured product is usually 2 to 3, preferably 1 to 2, and more preferably 0.5 to 0.8 or less. By using such a YI value, it can also be used for in-vehicle use.

In the method for producing an optical member, it is preferable that at least two optical substrates are bonded together by the following steps 1 to 3. If it is determined that sufficient adhesive strength can be secured at the stage of step 2, step 3 can be omitted.
Step 1:
By applying an adhesive to at least one optical base material to form a coating layer, and irradiating the coating layer with ultraviolet rays, the optical base side of the coating layer (the lower side of the coating layer) Is present on the side opposite to the optical substrate side (the upper side of the coating layer, usually the atmosphere side). The process of obtaining the optical base material which has a hardened | cured material layer which has an uncured part (henceforth "the uncured part of a hardened | cured material layer" or only "an uncured part"). In Step 1, there is no particular limitation on the curing rate of the coating layer after ultraviolet irradiation, and there is an uncured portion on the surface opposite to the optical substrate side (the upper side of the coating layer, usually the atmosphere side). All you need is it. After irradiation with ultraviolet rays, when the opposite side (the upper side of the coating layer, usually the atmosphere side) of the optical substrate is touched with a finger and a liquid component adheres to the finger, it can be determined that it has an uncured portion.
Step 2:
Another optical substrate is bonded to the uncured portion of the cured product layer of the optical substrate obtained in Step 1, or the cured product layer of the other optical substrate obtained in Step 1 is not yet bonded. The process of bonding the cured parts together.
Step 3:
The process of irradiating an ultraviolet-ray through the optical base material which has a light-shielding part to the hardened | cured material layer which has the unhardened part in the bonded optical base material, and hardening this hardened | cured material layer.
A specific embodiment of the optical member manufacturing method of the present invention that goes through steps 1 to 3 will be described below with reference to the drawings, taking as an example the bonding of a liquid crystal display unit and a transparent substrate having a light shielding portion. To do.
Here, when two or more substrates are bonded together, the adhesive is applied in a liquid resin state to at least one substrate, and a liquid resin state or an uncured portion is applied to the other substrate. In the case of being cured by ultraviolet rays after being bonded together, it is particularly preferable to use in such a case because it exhibits a particularly excellent adhesive effect and prevents air from intervening.

(First embodiment)
FIG. 1 is a process diagram showing a first embodiment of a method for manufacturing an optical member.
This method is a method of obtaining an optical member by bonding the liquid crystal display unit 1 and the transparent substrate 2 together.
The liquid crystal display unit 1 is a liquid crystal display unit in which a liquid crystal material is sealed between a pair of substrates on which electrodes are formed, and a polarizing plate, a driving circuit, a signal input cable, and a backlight unit are provided.
The transparent substrate 2 is a transparent substrate such as a glass plate, a polymethyl methacrylate (PMMA) plate, a polycarbonate (PC) plate, an alicyclic polyolefin polymer (COP) plate.
Here, the transparent substrate 2 having a black frame-shaped light-shielding portion 4 on the surface of the transparent substrate can be preferably used, and the light-shielding portion 4 is formed by applying a tape, applying a paint, printing, or the like. In the present invention, the present invention can also be applied to a device that does not have the light shielding portion 4. However, in the following description of the first to third embodiments, a case where the light shielding portion 4 is provided will be described as a specific example. In the case where the light-shielding portion 4 is not provided, “transparent substrate having a light-shielding portion” can be read as “transparent substrate”, and can be considered as an example in which the light-shielding portion is not provided as it is.

Step 1:
First, as shown in FIG. 1A, an adhesive is applied to the surface of the liquid crystal display unit 1 on which the display surface and the light shielding portion of the transparent substrate 2 having the light shielding portion are formed. Examples of the coating method include a slit coater, a roll coater, a spin coater, a screen printing method, a bar coater, a doctor blade method, and an ink jet method. Here, the adhesive applied to the surface of the liquid crystal display unit 1 and the transparent substrate 2 having the light shielding portion can be the same or different. Usually the same adhesive is preferred.
The thickness of the cured product is adjusted so that the cured product layer 7 after bonding has a thickness of 10 to 500 μm, preferably 20 to 350 μm, and more preferably 30 to 200 μm. Here, it is preferable that the thickness of the cured product existing on the surface of the transparent substrate 2 having the light shielding portion is generally equal to or thicker than the thickness of the cured product existing on the surface of the liquid crystal display unit 1. . This is to minimize the portion that remains uncured even after irradiation with ultraviolet rays in Step 3 described later, thereby eliminating the risk of curing failure. In addition, when using an optical member for in-vehicle use, in the case of a liquid crystal module (LCM), the step may be larger than the liquid crystal panel (LCD), and the thickness of the cured product becomes thicker from 500 to 1000 mm. Become more severe. However, the adhesive expands and contracts in accordance with the deformation of the substrate and is extremely excellent in adhesiveness. Therefore, even in such a case, an excellent effect is exhibited.

The applied adhesive composition 5 is irradiated with ultraviolet rays 8, and a cured portion (not shown in the figure) existing on the lower side of the coating layer (the liquid crystal display unit side or the transparent substrate side as viewed from the adhesive) and the coating layer A cured product layer 6 having an uncured portion (not shown in the figure) present on the upper side (the side opposite to the liquid crystal display unit side or the side opposite to the transparent substrate side) (the atmosphere side when performed in the atmosphere) is obtained. The irradiation amount is preferably 5 to 2000 mJ / cm ² , and particularly preferably 10 to 1000 mJ / cm ² . By setting it as such irradiation amount, the hardening degree of the hardened | cured material of the obtained optical member becomes enough, and bonding of the liquid crystal display unit 1 and the transparent substrate 2 which has a light-shielding part becomes favorable.
In this specification, “uncured” means at least one of a fluid state in an environment of 25 ° C., or a case where a cured product after ultraviolet irradiation is touched with a finger and a liquid component adheres to the finger. It means when there is one.
For curing by ultraviolet irradiation from ultraviolet to near ultraviolet, any light source may be used as long as it is a lamp that irradiates ultraviolet to near ultraviolet rays. For example, a low-pressure, high-pressure or ultrahigh-pressure mercury lamp, metal halide lamp, (pulse) xenon lamp, LED lamp, or electrodeless lamp can be used.
In the above step 1, the wavelength of ultraviolet rays irradiated to the adhesive is not particularly limited, but when the maximum illuminance in the range of 320 nm to 450 nm is 100, the ratio of the maximum illuminance (illuminance ratio) at 200 to 320 nm is 30 or less is preferable, Especially preferably, the illumination intensity in 200-320 nm is 10 or less. By setting it as such a ratio, the adhesive strength of the optical member obtained becomes favorable.

When the transparent substrate 2 is a polycarbonate (PC) plate, an LED lamp capable of irradiating 405 nm ultraviolet rays is preferable in step 3. By using such a lamp, irradiation can be performed efficiently and without damage to the substrate.
Therefore, when the substrate 2 is a polycarbonate plate, it is preferable to use a photopolymerization initiator that cleaves at 405 nm and starts the reaction.

Here, the method of irradiating ultraviolet rays so as to achieve the illuminance ratio is, for example, a method of applying a lamp satisfying the illuminance ratio as a lamp that irradiates ultraviolet to near-ultraviolet rays, or the lamp itself has the illuminance. Even if the above condition is not satisfied, such illuminance can be obtained by using a base material (for example, a short wave ultraviolet cut filter, a glass plate, a film, etc.) that cuts short wavelength ultraviolet rays at the time of irradiation in step 1. Irradiation at a ratio is possible. Although it does not specifically limit as a base material which adjusts the illumination intensity ratio of an ultraviolet-ray, For example, the glass plate, soda-lime glass, PET film etc. which were given the short wave ultraviolet-ray cut process are mentioned.
In step 1, irradiation with ultraviolet rays is usually carried out in the atmosphere in the upper surface on the coating side (as viewed from the ultraviolet curable adhesive composition, on the side opposite to the liquid crystal display unit side or opposite to the transparent substrate side) (normal air From the surface). Further, ultraviolet irradiation can be performed while spraying a curing-inhibiting gas on the upper surface of the coating layer after evacuation. When the adhesive is cured in the atmosphere, the side opposite to the liquid crystal display unit side or the side opposite to the transparent substrate side is the atmosphere side. In addition, when it is desired to improve the tackiness of the surface of the coating layer formed in step 1, ultraviolet rays can be irradiated in a vacuum environment or in a gas environment that does not cause hardening inhibition such as nitrogen.
On the other hand, when the step 3 is omitted, the curing can be performed in a vacuum or while spraying a gas (for example, nitrogen) that promotes the curing. Thereby, even if the step 3 is omitted, sufficient adhesion can be performed.

The state of the uncured portion and the thickness of the uncured portion can be adjusted by spraying oxygen or ozone on the surface of the adhesive during the ultraviolet irradiation.
That is, oxygen inhibition of the curing occurs on the surface of the adhesive sprayed with oxygen or ozone. For this reason, the uncured part of the surface can be ensured, and the thickness of the uncured part can be increased.

Step 2:
As shown in FIG. 1B, the liquid crystal display unit 1 and the transparent substrate 2 having a light shielding portion are bonded together so that the uncured portions face each other. Bonding can be performed either in air or in vacuum.
Here, in order to prevent bubbles from being generated during bonding, it is preferable to perform bonding in a vacuum.
As described above, when a cured product having a cured part and an uncured part is obtained on each of the liquid crystal display unit and the transparent substrate, the adhesion can be improved.
Bonding can be performed by pressing, pressing, or the like.

Step 3:
Next, as shown in FIG.1 (c), the optical member obtained by bonding the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with the ultraviolet rays 8 from the transparent substrate 2 side having the light shielding portion, and the adhesive is applied. Harden.
The dose of ultraviolet rays about 100~10000mJ / cm ² is preferably in accumulated light amount, particularly preferably about 200~8000mJ / cm ^2. The light source used for curing by irradiation with ultraviolet to near ultraviolet light may be any light source as long as it is a lamp that emits ultraviolet to near ultraviolet light. For example, a low-pressure, high-pressure or ultrahigh-pressure mercury lamp, metal halide lamp, (pulse) xenon lamp, LED lamp, or electrodeless lamp can be used.
In this way, an optical member as shown in FIG. 4 can be obtained.

(Second Embodiment)
In addition to the first embodiment, the optical member can also be manufactured by the following modified second embodiment. Note that the details of each process are the same as those in the first embodiment, and therefore, the description of the same parts is omitted.

Step 1:
First, as shown in FIG. 2 (a), an adhesive is applied to the surface of the transparent substrate 2 having the light-shielding portion on which the light-shielding portion 4 is formed, and then the obtained adhesive 5) is irradiated with ultraviolet rays 8. Thus, a cured product 6 having a cured portion present on the lower side of the coating layer (on the transparent substrate side as viewed from the adhesive) and an uncured portion present on the upper side of the coating layer (the side opposite to the transparent substrate side) is obtained.
At this time, the wavelength of ultraviolet rays irradiated to the adhesive is not particularly limited, but when the maximum illuminance in the range of 320 nm to 450 nm is 100, the ratio of the maximum illuminance at 200 to 320 nm is preferably 30 or less, particularly preferably. The illuminance at 200 to 320 nm is 10 or less. When the maximum illuminance in the range of 320 nm to 450 nm is 100, if the ratio of the maximum illuminance at 200 to 320 nm is higher than 30, the adhesive strength of the finally obtained optical member may be inferior.

Step 2:
As shown in FIG. 2B, the liquid crystal display unit 1 and the transparent substrate 2 having a light shielding portion are bonded so that the uncured portion of the obtained cured product 6 and the display surface of the liquid crystal display unit 1 face each other. Bonding can be performed either in air or in vacuum.

Step 3:
As shown in FIG. 2 (c), the optical member obtained by laminating the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with ultraviolet rays 8 from the transparent substrate 2 side having a light-shielding portion, and an uncured portion of the adhesive. The cured product 6 having the following is cured.

  In this way, an optical member as shown in FIG. 4 can be obtained.

(Third embodiment)
FIG. 3 is a process diagram showing a third embodiment of the method of manufacturing the optical member. Note that the details of each process are the same as those in the first embodiment, and therefore, the description of the same parts is omitted.
In addition, the same code | symbol is attached | subjected in the figure about the same member as the structural member in 1st Embodiment mentioned above, and the description is not repeated here.

Step 1:
As shown in FIG. 3A, an adhesive is applied to the surface of the liquid crystal display unit 1. Thereafter, the adhesive 5 is irradiated with ultraviolet rays 8 to be present on the lower side of the coating layer, the cured portion existing on the transparent substrate side as viewed from the adhesive, and on the upper side (opposite side of the transparent substrate side) of the coating layer. A cured product 6 having an uncured portion is obtained.
At this time, the wavelength of ultraviolet rays irradiated to the adhesive is not particularly limited, but when the maximum illuminance in the range of 320 nm to 450 nm is 100, the maximum illuminance at 200 to 320 nm is preferably 30 or less, particularly preferably 200 to The illuminance at 320 nm is 10 or less. By setting it as such maximum illumination intensity, the adhesive strength of the optical member finally obtained becomes favorable.

Step 2:
As shown in FIG. 3B, the liquid crystal display unit 1 and the light-shielding part are arranged so that the uncured part of the obtained cured product 6 and the surface on which the light-shielding part on the transparent substrate 2 having the light-shielding part is opposed to each other. The transparent substrate 2 which has is bonded. Bonding can be performed either in air or in vacuum.

Step 3:
Next, as shown in FIG.3 (c), the optical member obtained by bonding the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with the ultraviolet rays 8 from the transparent substrate 2 side having the light shielding portion, and the adhesive The cured product layer 6 having an uncured portion is cured.

  In this way, an optical member as shown in FIG. 4 can be obtained.

In each of the embodiments described above, some of the embodiments of the method for producing the optical member are described using one specific optical substrate. In each embodiment, a liquid crystal display unit and a transparent substrate having a light-shielding portion have been described, but in the manufacturing method, various materials described later as an optical base material can be used instead of the liquid crystal display unit, Also about a transparent substrate, the various materials mentioned later as an optical base material can be used.
Moreover, as an optical base material such as a liquid crystal display unit and a transparent substrate, other various optical base materials (for example, a film or other optical base material bonded with a cured product) It is also possible to use a laminate).
Furthermore, by applying the adhesive application method, the thickness of the cured product, the irradiation amount and the light source of ultraviolet rays, and oxygen or nitrogen or ozone on the surface of the adhesive described in the section of the first embodiment, Any method for adjusting the thickness of the uncured portion of the cured product is not applied only to the above-described embodiment, and can be applied to any manufacturing method included in the present invention.

Specific modes of the optical members that can be manufactured in the first to third embodiments including the liquid crystal display unit are shown below.
(I)
At least one optical substrate selected from the group consisting of a transparent glass substrate having a light shielding portion, a transparent resin substrate having a light shielding portion, and a glass substrate having a light shielding portion and a transparent electrode formed thereon. And the optical substrate to be bonded to it is at least one display unit selected from the group consisting of a liquid crystal display unit, a plasma display unit, an organic EL display unit, a quantum dot display unit, and a micro LED display unit. A mode in which the optical member is a display unit having an optical base material having the light shielding portion.
(Ii)
One optical base material is a protective base material having a light shielding part, and another optical base material bonded thereto is a touch panel or a display unit having a touch panel, and at least two optical base materials are bonded together. A mode in which the member is a touch panel having a protective base material having a light shielding part or a display unit having the same.
In this case, in the step 1, the adhesive is applied to the surface of the protective base material having the light shielding portion provided with the light shielding portion, the touch surface of the touch panel, or both of them. preferable.
(Iii)
One optical substrate is an optical substrate having a light shielding portion, the other optical substrate bonded thereto is a display unit, and an optical member having at least two optical substrates bonded has a light shielding portion. The aspect which is a display body unit which has an optical base material to have.
In this case, in Step 1, the adhesive is applied to either the surface of the optical substrate having the light shielding portion on which the light shielding portion is provided, the display surface of the display unit, or both. It is preferable to do this.
Specific examples of the optical substrate having a light shielding part include a display screen protective plate having a light shielding part, or a touch panel provided with a protective substrate having a light shielding part.
For example, when the optical substrate having the light-shielding portion is a protective plate for a display screen having the light-shielding portion, the surface of the optical substrate having the light-shielding portion is provided on the side on which the light-shielding portion is provided. It is the surface on the side where the part is provided. In addition, when the optical substrate having the light shielding portion is a touch panel having a protective substrate having the light shielding portion, the surface having the light shielding portion of the protective substrate having the light shielding portion is bonded to the touch surface of the touch panel. The surface of the optical substrate having the light shielding portion on the side where the light shielding portion is provided means the substrate surface of the touch panel opposite to the touch surface of the touch panel.
The light-shielding part of the optical base material having the light-shielding part may be in any of the optical base materials, but is usually formed in a frame shape around the optical base material in the form of a transparent plate or sheet, and its width is 0 About 1 mm to 10 mm, preferably about 1 to 8 mm, more preferably about 1.5 to 5 mm.

The adhesive can be used in a method of manufacturing an optical member by laminating at least two optical base materials by performing Step 1 to Step 2 and Step 3 as necessary. .
The curing shrinkage of the cured product is usually 0 to 10%, preferably 0 to 6%. Thereby, when an adhesive agent hardens | cures, the internal stress accumulate | stored in hardened | cured material can be reduced and it can prevent effectively that the interface between a base material and hardened | cured material can be distorted.
Further, when the substrate such as glass is thin, if the curing shrinkage rate is large, the warp when the adhesive is cured increases. Since the warpage of the base material has a large adverse effect on the display performance of the optical member, it is preferable that the curing shrinkage rate is small.

  The transmittance of 450 nm to 800 nm of the cured product is usually 85% or more, preferably 90% or more. By setting it as such a transmittance | permeability, it is easy to permeate | transmit light and visibility when it is set as a display apparatus becomes favorable.

The adhesive can be suitably used as an adhesive for manufacturing an optical member by laminating a plurality of optical substrates by the steps 1 to 3.
As a preferable optical member obtained by the above manufacturing method, an optical member in which a plate-like or sheet-like transparent optical base material having a light-shielding portion and the above laminate are bonded with a cured product can be mentioned.

In this specification, the “optical substrate” means both an optical substrate having no light-shielding portion on the surface and an optical substrate having a light-shielding portion on the surface. Of the at least two optical substrates, at least one of the optical substrates is preferably an optical substrate having a light shielding portion.
Various materials can be used as the material of the optical substrate. Specific examples include PET, PC, PEN, cycloolefin, PMMA, a composite of PC and PMMA, COC, COP, polyimide, plastic (such as acrylic resin), and the like; glass, tempered glass, and the like.
Moreover, an optical base material contains forms, such as a transparent plate, a transparent film, and a transparent sheet. Moreover, the form of the laminated body which laminated | stacked multiple optical base materials chosen from these plates, films, and sheets like a polarizing plate, a touch panel (touch panel input sensor), a display unit, etc. is also included. Non-laminated sheets or transparent plates, and transparent plates made from glass (inorganic glass plates and processed products thereof such as lenses, prisms, ITO glass) and the like can be used.
That is, a substrate made of one or more materials selected from PET, PC, PEN, cycloolefin, PMMA, a composite of PC and PMMA, COC, COP, polyimide, plastic, glass, and tempered glass; Films; and those substrates and films on which transparent electrodes are formed; or a laminate in which a plurality of these substrates and films are laminated.
The optical substrate is, for example, an icon sheet, a decorative sheet, a protective sheet, an LCD having a polarizing plate attached to glass, an organic EL display, a micro LED display, an EL illumination, a quantum dot display, an electronic paper, a plasma display, or the like. It can be set as the base material selected from these.
The thickness of the optical substrate is not particularly limited. The standard is usually 5 μm to 5 cm, preferably 10 μm to 10 mm, more preferably about 50 μm to 3 mm. Further, as the optical substrate, any of a plate-like substrate having high rigidity and a substrate having low rigidity that can be bent or rolled can be used.

  The refractive index of the cured product is preferably 1.45 to 1.55. By setting it as such a refractive index, the difference of the refractive index with an optical base material can be reduced, the light reflection can be suppressed by suppressing irregular reflection of light.

Preferred embodiments of the optical member include the following (i) to (vii).
(I)
The optical member which bonded together the optical base material which has a light-shielding part, and the said functional laminated body with hardened | cured material.
(Ii)
An optical base material having a light shielding part is formed with a transparent glass substrate having a light shielding part, a transparent resin substrate having a light shielding part, a glass substrate on which the light shielding part and the transparent electrode are formed, and the light shielding part and the transparent electrode. The optical member according to (i), wherein the optical member is an optical base selected from the group consisting of transparent resin substrates, and the functional laminate is a display unit or a touch panel.
(Iii)
The optical member according to (ii), wherein the display unit is any one of a liquid crystal display unit, a plasma display unit, an organic EL display unit, a quantum dot display unit, and a micro LED display unit.
(Iv)
A touch panel (or touch panel input sensor) in which a plate-like or sheet-like optical base material having a light-shielding portion and a touch panel sensor are bonded together with a cured product.
(V)
A display panel in which a plate-like or sheet-like optical base material having a light shielding portion is bonded to a display screen of a display unit by a cured product.
(Vi)
The display panel according to (v), wherein the plate-shaped or sheet-shaped optical base material having the light shielding portion is a protective base material or a touch panel for protecting the display screen of the display unit.
(Vii)
The optical member, touch panel, or display panel according to any one of (i) to (vi), wherein the adhesive is the adhesive composition according to any one of (1) to (10). .

  The optical member obtained by the above manufacturing method can be incorporated into electronic devices such as a television, a small game machine, a mobile phone, a personal computer, and a wearable device.

  Unless otherwise specified, the above-mentioned adhesive can contain one each selected from those types for all the components described above. Two or more selected from these types can also be used in combination.

  For all the components and matters described above, a combination of preferable ones is more preferable, and a combination of more preferable ones is further preferable. The same applies to combinations of preferable and more preferable, combinations of more preferable and more preferable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[Preparation of adhesive]
The components shown in Table 1 below were heated and mixed to prepare adhesives for evaluation tests of Examples 1 to 5 and Comparative Examples 1 to 3. The numerical value of the component in the following table | surface represents weight%.
Each prepared adhesive was used for the evaluation test described below.

  Abbreviations and the like in Table 1 below represent the following meanings.

Oligomer: Photopolymerizable oligomer (A).
Monomer: (Meth) acrylate monomer (B).
Copolymerizable monomer: copolymerizable (meth) acrylate monomer (C).
A: Urethane acrylate (reactant having a molar ratio of 1: 1.3: 0.7, a weight average molecular weight Mw of 22000) comprising three components of polypropylene glycol (molecular weight 3000), isophorone diisocyanate and 2-hydroxyethyl acrylate.
B1: Blemmer LA (lauryl acrylate, manufactured by NOF Corporation).
B2: NK ester S-1800A (isostearyl acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.).
B3: 4HBA (4-hydroxybutyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.).
C: Macromonomer AB-6 (methacryloyloxypolybutyl methacrylate, manufactured by Toagosei Co., Ltd.).
D: Pine crystal KE311 (hydrogenated rosin ester resin, manufactured by Arakawa Chemical Co., Ltd.).
E1: IRGACURE 184D (hydroxycyclohexyl phenyl ketone, manufactured by BASF).
E2: Speed cure TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by LAMBSON).

[durability]
A glass plate having a thickness of 1.0 mm and a polycarbonate plate having a thickness of 1.5 mm (MR-58U manufactured by Mitsubishi Gas Chemical Co., Ltd.) were prepared, and an adhesive was applied to the polycarbonate plate so as to have a thickness of 200 μm. . The applied adhesive was irradiated with ultraviolet rays having an integrated light quantity of 200 mJ / cm ^{2 with} an LED lamp (365 nm), and then a glass plate was bonded to the adhesive. Among the bonded glass plate and polycarbonate plate, the adhesive is irradiated with ultraviolet rays with an integrated light amount of 5000 mJ / cm ² from the polycarbonate plate side with an LED lamp (405 nm), for durability evaluation of each example and comparative example. Two samples were prepared each.
One of the obtained samples was left in a high temperature environment of 95 ° C., and the other was left in a high temperature and high humidity environment of 85 ° C. and 85% RH for 250 hours. In the sample after standing, the presence or absence of foaming of the cured product or peeling of the cured product from the substrate was visually confirmed, and evaluated according to the following three-stage criteria. The evaluation results are shown in Table 1.
In addition, the polycarbonate board used here was used without performing heat processing.
[Evaluation criteria]
A: No foaming or peeling.
Δ: Partial foaming and peeling occurred.
X: Generated on the entire surface of foaming and peeling.

[War of optical member]
A glass plate having a thickness of 1.0 mm and a polycarbonate plate having a thickness of 1.5 mm (MR-58U manufactured by Mitsubishi Gas Chemical Co., Ltd.) were prepared, and an adhesive was applied to the polycarbonate plate so as to have a thickness of 200 μm. . The applied adhesive was irradiated with ultraviolet rays having an integrated light quantity of 200 mJ / cm ^{2 with} an LED lamp (365 nm), and then a glass plate was bonded to the adhesive. Among the bonded glass plate and polycarbonate plate, the adhesive is irradiated with ultraviolet rays with an integrated light amount of 5000 mJ / cm ² from the polycarbonate plate side with an LED lamp (405 nm), for durability evaluation of each example and comparative example. Two samples were prepared each.
The obtained sample was left for 3 hours in a low temperature environment of −40 ° C. The test piece taken out from the environmental tester was placed on a smooth table with the glass side down, and the distance from the table to the end of the sample in the vertical direction was measured as the warp of the optical member. The evaluation results are shown in Table 1.

[viscosity]
The viscosity of the adhesive was measured at 25 ° C. using an E-type viscometer (TV-200: manufactured by Toki Sangyo Co., Ltd.). The measurement results are shown in Table 1.

[transparency]
Prepare two glass slides each having a thickness of 1 mm coated with a fluorine-based mold release agent, and apply each of the examples and comparative examples so that the thickness of the slide glass on one slide glass is 200 μm. Adhesive was applied. The application surface of the release agent of the other slide glass was bonded to the adhesive so that the application surfaces of the release agents of the two glasses face each other. A cured product was obtained by irradiating UV light with an integrated light quantity of 2000 mJ / cm ² with a high-pressure mercury lamp (80 W / cm, ozone-less) through one of the two glass slides bonded together. Thereafter, the two slide glasses were peeled off to produce a cured product for measuring transparency.
The transparency of the obtained cured product was measured for transmittance (average transmittance) in a wavelength region of 450 to 800 nm using a spectrophotometer (U-3310, manufactured by Hitachi High-Technologies Corporation). As a result, the transmittances of 450 to 800 nm of all the cured products of each Example and Comparative Example were 85% or more.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display unit, 2 Transparent base material which has a light-shielding part, 3 Transparent base material, 4 Light-shielding part, 5 Adhesive (adhesive composition), 6 Hardened | cured material which has an uncured part, 7 Hardened | cured material, 8 Ultraviolet rays

Claims (12)

  An ultraviolet ray comprising a resin composition used for laminating at least two optical substrates and containing a photopolymerizable oligomer (A), a (meth) acrylate monomer (B), and a copolymerizable (meth) acrylate monomer (C) A curable adhesive composition.   The copolymerizable (meth) acrylate monomer (C) is selected from the group consisting of methyl (meth) methacrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, isobornyl (meth) acrylate, and hydroxyethyl (meth) acrylate. The adhesive composition according to claim 1, which is a copolymerizable (meth) acrylate monomer having at least one kind of skeleton.   The photopolymerizable oligomer (A) is a urethane (meth) acrylate having at least one skeleton selected from the group consisting of polypropylene, polybutadiene, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene. The adhesive composition as described.   The adhesive composition according to claim 1, wherein the (meth) acrylate monomer (B) is a mixture of two or more monomers selected from C8-C30 alkyl (meth) acrylate monomers.   The (meth) acrylate monomer (B) is a mixture of one or more monomers each selected from a C8-C30 linear alkyl (meth) acrylate monomer and a C10-C30 branched alkyl (meth) acrylate monomer. Item 5. The adhesive composition according to any one of Items 1 and 4.   The adhesive composition according to any one of claims 1 to 5, wherein the cured product has a transmittance of 450 to 800 nm of 85% or more.   The optical base material is one or more materials selected from PET, PC, PEN, cycloolefin, PMMA, a composite of PC and PMMA, COC, COP, polyimide, plastic, glass, and tempered glass. The adhesive composition according to claim 1.   A substrate comprising at least one material selected from the group consisting of PET, PC, PEN, cycloolefin, PMMA, a composite of PC and PMMA, COC, COP, polyimide, plastic, glass, and tempered glass; The adhesive composition according to claim 1, which is a film; and a substrate and a film on which a transparent electrode is formed; or a laminate in which a plurality of these substrates and films are laminated.   The optical substrate is selected from an icon sheet, a decorative sheet, a protective sheet, a glass and polarizing plate LCD, an organic EL display, a micro LED display, an EL illumination, a quantum dot display, an electronic paper, and a plasma display. The adhesive composition according to claim 1, wherein   The adhesive composition as described in any one of Claims 1-9 used for bonding of a vehicle-mounted display.   Hardened | cured material obtained by irradiating an active energy ray to the adhesive composition as described in any one of Claims 1-10, and hardening an adhesive composition. The manufacturing method of the optical member with which at least 2 optical base material pasted which has the following processes 1-2.
Step 1:
The adhesive composition according to any one of claims 1 to 10 is applied to at least one of the two optical substrates to form an adhesive coating layer, and the coating layer is applied to the coating layer. The process of obtaining the optical base material which has a layer of hardened | cured material by irradiating an ultraviolet-ray.
Step 2:
The other optical substrate that does not have the cured product layer of the two optical substrates is bonded to the cured product layer of the optical substrate obtained in step 1, or
The process of bonding together the layer of the hardened | cured material of two optical base materials each obtained by the process 1 and having a layer of hardened | cured material.

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