KR20230169973A - Optical films and their uses - Google Patents

Abstract

An optical film is formed from a cured product of a curable composition containing epoxy (meth)acrylate represented by the following formula (1).
^{[ Wherein , _} , m1 and m2 are the same or different from each other and represent an integer of 0 or more, and A ^1a and R ^1b is the same or different from each other and represents a straight-chain or branched alkylene group, n1 and n2 are the same or different from each other and represents an integer of 1 or more, and R ^2a and R ^2b are the same as each other or or different, represents a hydrogen atom or a methyl group]
The optical film is mounted on a display unit of an image display device that is used by repeated bending. The optical film has both bending resistance and surface hardness.

Description

Optical films and their uses

The present invention relates to an optical film that can be used as a cover sheet for a display having excellent bending resistance and excellent surface hardness, and its use.

Recently, there has been remarkable progress in the increased functionality of smartphones, and foldable smartphones have been proposed as one of them. Foldable smartphones have the advantage of being able to fold or unfold a single screen, and can be used as both a smartphone and a tablet with a single terminal, and can achieve both the portability of a smartphone and the large screen of a tablet. However, there are many technical challenges until it is put into practical use.

To enable folding, the display of the foldable smartphone uses an organic electroluminescence (EL) display (OLED) that can be made of all plastic, rather than a liquid crystal display (LCD) using a glass substrate. In addition, metal mesh such as copper mesh is being considered for the transparent electrode of OLED, rather than indium tin oxide (ITO), which is weak to bending and prone to breakage. In addition, a polyimide substrate is used instead of a glass substrate for a substrate forming a low-temperature polysilicon TFT (Thin Film Transistor), and a thin film encapsulation layer and a barrier film are used together to encapsulate OLEDs instead of glass encapsulation.

On the OLED, film materials such as a touch sensor, a circular polarizer, a λ/4 retardation plate for sunglasses readable, and a cover sheet are laminated, and an adhesive layer such as OCA (Optical Clear Adhesive) or PSA (Pressure Sensitive Adhesive) is placed between each film. This is included. Additionally, a surface treatment layer such as a hard coat is formed on the cover sheet. For the touch sensor, in the out-cell type, metal mesh electrodes are formed on a polyethylene terephthalate (PET) film, and in the on-cell type, metal mesh electrodes are formed on the thin film encapsulation layer of OLED. In order for a foldable smartphone to be put into practical use, all of these films and thin layers must achieve their original functions and then have unprecedented bending resistance (bending durability that suppresses breakage or folding stripes even when repeatedly bent, or bending and leaving it for a long period of time). However, it must also have bending stability to suppress fold marks (deformation).

Among them, since the cover sheet is used for the outermost surface, strict performance is required in terms of surface hardness and wear resistance. However, since surface hardness and bending resistance have a trade-off relationship, it is not easy to achieve both properties at the same time. Bending resistance is related to the elastic modulus and film thickness of the film. The lower the elastic modulus, the higher the bending resistance (less likely to cause damage or deformation due to bending). The thinner the film thickness, the higher the bending resistance, but the lower the elastic modulus. As the value is lowered or the film thickness is thinner, the surface hardness tends to decrease. As film materials for cover sheets, various transparent polyimides with excellent bending resistance have been proposed (Patent Documents 1 to 4).

On the other hand, as a material capable of achieving both high hardness and flexibility, a cured epoxy acrylate product having a 9,9-bis(aryl)fluorene structure and an oxyalkylene chain has been proposed (Patent Document 5).

Japanese Patent Publication No. 2018-28073 Japanese Patent Publication No. 2019-052287 WO2017/191830 Japanese Patent Publication No. 2019-051718 Japanese Patent Publication No. 2017-186513

However, the transparent polyimides of Patent Documents 1 to 4 all have insufficient surface hardness and require hard coating treatment in order to use them as a cover sheet. Additionally, in order to increase hardness, the thickness of the hard coat layer becomes thicker, which also poses a problem in that curling due to curing shrinkage increases. In addition, bending resistance requires not only durability through repeated bending, but also absence of fold marks when kept in a bent state for a long period of time. Transparent polyimide has high durability against repeated bending, but transparent polyimide with a hard coat layer needs to be improved because fold marks are observed.

On the other hand, in Patent Document 5, a cover sheet for a foldable terminal is not assumed as a use of the cured product described in the same document, and furthermore, no suggestion is made regarding the physical properties required for such use.

Therefore, the purpose of the present invention is to provide an optical film capable of achieving both bending resistance and surface hardness, and a use thereof.

As a result of intensive studies to achieve the above problem, the present inventors have found that a film formed from a cured product of epoxy acrylate having a specific aromatic hydrocarbon skeleton has excellent bending resistance and excellent surface hardness, and proposed the present invention. It has reached completion. In particular, if a structure having a rigid 9,9-bis(aryl)fluorene skeleton and a flexible oxyethylene chain of an appropriate length is selected as the aromatic hydrocarbon skeleton, both high flexibility and surface hardness can be achieved. It was discovered that the film formed from the cargo had high transparency, small phase difference, no rainbow stains or light leakage even when used as a cover sheet, and excellent visibility beyond polarized sunglasses.

One preferred form of the present invention is an optical film mounted on a display portion of an image display device used by repeated bending, and is formed of a cured product of a curable composition containing epoxy (meth)acrylate represented by the formula (1) below, there is.

[Formula 1]

[During the ceremony,

X represents a linking group selected from the group of formula (2) below,

[Formula 2]

(During the ceremony,

R ^3a and R ^3b are the same or different from each other, and are hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, C _1-9 alkyl group, C _1-5 alkoxy group, C _4-12 cycloalkyl group, C _{6 -12} represents an aryl group, a C _2-5 alkenyl group, or a C _7-17 aralkyl group, and R ^3a and R ^3b may combine to form a carbon ring or heterocycle,

p represents an integer greater than or equal to 1)

Ring Z ^1a and Ring Z ^1b are the same or different from each other and represent an arene ring,

R ^1a and R ^1b are the same or different from each other and represent a substituent, m1 and m2 are the same or different from each other and represent an integer of 0 or more,

A ^1a and A ^1b are the same or different from each other and represent a linear or branched alkylene group, n1 and n2 are the same or different from each other and represent an integer of 1 or more,

R ^2a and R ^2b are the same or different from each other and represent a hydrogen atom or a methyl group]

Moreover, in one preferred aspect of the present invention, the epoxy (meth)acrylate is an epoxy (meth)acrylate represented by the following formula (1a).

[Formula 3]

(During the ceremony,

R ⁴ represents a substituent, k represents an integer of 0 to 8,

Ring Z ^1a and Ring Z ^1b , A ^1a and A ^1b , n1 and n2, R ^1a and R ^1b , m1 and m2, R ^2a and R ^2b are the same as above)

In addition, one preferred aspect of the present invention is that in the formula (1), ring Z ^1a and ring Z ^1b are the same as or different from each other and represent a benzene ring or a naphthalene ring, and R ^1a and R ^1b are each other. They are the same or different, and represent a C _1-4 alkyl group or a C _6-10 aryl group, and n1+n2 represents an integer of 2 to 30.

Moreover, in one preferred aspect of the present invention, the epoxy (meth)acrylate is an epoxy (meth)acrylate represented by the following formula (1b).

[Formula 4]

(In the formula, n1+n2 represents an integer of 3 to 20)

In one preferred embodiment of the present invention, the proportion of the epoxy (meth)acrylate represented by the formula (1a) is 70 to 100 mol% based on the epoxy (meth)acrylate represented by the formula (1).

Additionally, in one preferred aspect of the present invention, the curable composition further includes an ultraviolet absorber.

Additionally, in one preferred aspect of the present invention, the cured product is a photocured product.

In addition, in one preferred embodiment of the present invention, the in-plane retardation Ro(550) of the optical film is 50 nm or less, and the thickness direction retardation Rth(589) is 100 nm or less.

In one preferred embodiment of the present invention, the optical film has a total light transmittance of 85% or more and a spectral transmittance at 380 nm of 8% or less.

Additionally, in one preferred aspect of the present invention, the optical film is a cover sheet for a display.

Additionally, in one preferred aspect of the present invention, the optical film is a polarizing plate protective film.

Additionally, in one preferred aspect of the present invention, the average thickness of the optical film is 20 to 200 μm.

Furthermore, one preferred aspect of the present invention is a polarizing plate in which the optical film and the polyvinyl alcohol polarizer are bonded together with an adhesive.

Additionally, in one preferred embodiment of the present invention, the optical film contains an ultraviolet absorber, and the adhesive does not contain an ultraviolet absorber.

Also, one of the preferred aspects of the present invention is an image display device provided with the optical film.

Additionally, in one preferred aspect of the present invention, the image display device includes an organic electroluminescence (EL) display.

Additionally, in one preferred aspect of the present invention, the image display device is a foldable portable information terminal.

Furthermore, one preferred aspect of the present invention is a method of placing the optical film on the surface of a display portion of an image display device used by repeated bending and using the optical film as a cover sheet.

Additionally, in the present specification and claims, the number of carbon atoms of the substituent may be expressed as C ₁ , C ₆ , C ₁₀ , etc. For example, “C ₁ alkyl group” means an alkyl group with 1 carbon number, and “C _6-10 aryl group” means an aryl group with 6 to 10 carbon atoms.

In the present invention, since the optical film is formed of a cured product of epoxy acrylate having a specific aromatic hydrocarbon skeleton, it is excellent in bending resistance and also has excellent surface hardness. In particular, by selecting a structure having a rigid 9,9-bis(aryl)fluorene skeleton and a flexible oxyalkylene chain of an appropriate length as the aromatic hydrocarbon skeleton, both high flexibility and surface hardness can be achieved, and high transparency is achieved. In addition, the phase difference is small, there are no rainbow stains or light leakage even when used as a cover sheet, and visibility beyond polarized sunglasses is excellent. In particular, when the optical film contains an ultraviolet absorber, it is effective as a polarizing plate protective film, and even if it is thin, bleed-out of the ultraviolet absorber can be suppressed, and both thinness and ultraviolet absorbing ability can be achieved, and adhesion to the polarizer can also be improved. there is.

1 is a schematic diagram of the manufacturing process of an optical film, which is one of the preferred embodiments of the present invention.
Figure 2 is a schematic diagram for explaining a method of bending an optical film in a bending stability test.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[Epoxy (meth)acrylate]

In one preferred aspect of the present invention, the curable composition contains epoxy (meth)acrylate represented by the above formula (1).

In the above formula (1), p in -(CH ₂ ) _p - of the linking group of It is ~ 4.

^{Among the linking groups} A linking group forming an aromatic carbon ring is more preferred, and R ^3a and Most preferably, R ^3b is a linking group that forms a fluorene ring.

In the above formula (1), the aromatic hydrocarbon ring (or arene ring) represented by ring Z ^1a and ring Z ^1b includes a monocyclic aromatic hydrocarbon ring such as a benzene ring (monocyclic arene ring), a polycyclic aromatic hydrocarbon ring ( It is largely distinguished by its ring-shaped arene ring. Examples of the polycyclic aromatic hydrocarbon ring include a fused polycyclic aromatic hydrocarbon ring (condensed polycyclic arene ring), a ring-assembly aromatic hydrocarbon ring (a ring-assembly arene ring), and the like.

Examples of the fused polycyclic arene ring include condensed 2 to 4 cyclic arene rings, such as a fused 2 cyclic arene ring and a fused 3 cyclic arene ring. Examples of the condensed bicyclic arene ring include condensed bicyclic C _10-16 arene rings such as a naphthalene ring. Examples of the condensed tricyclic arene ring include an anthracene ring and a phenanthrene ring.

Examples of the ring group arene ring include a viarene ring such as a non-C _6-12 arene ring, and a terarene ring such as a terC _6-12 arene ring. Examples of the non-C _6-12 arene ring include a biphenyl ring; Binaphthyl ring; and phenylnaphthalene rings such as 1-phenylnaphthalene ring and 2-phenylnaphthalene ring. Examples of the terC _6-12 arene ring include a terphenylene ring.

Among these aromatic hydrocarbon rings, C _6-12 arene rings such as benzene rings, naphthalene rings, and biphenyl rings are preferable, and since bending resistance and surface hardness are compatible, C _6-10 arene rings are more preferable. , a benzene ring is most preferred. Ring Z ^1a and ring Z ^1b may be different rings, but are usually the same ring.

In the above formula (1), the substituent represented by R ^1a and R ^1b is not particularly limited as long as it is a substituent that is non-reactive to the epoxy group, and may include a halogen atom, a hydrocarbon group, an alkoxy group, a cycloalkyloxy group, an aryloxy group, Examples include aralkyloxy group, alkylthio group, cycloalkylthio group, arylthio group, aralkylthio group, acyl group, nitro group, and cyano group.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of hydrocarbon groups include alkyl groups, cycloalkyl groups, aryl groups, and aralkyl groups. Alkyl groups include straight or branched C _1-10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, isobutyl, and t-butyl groups, Preferably, a straight-chain or branched C _1-6 alkyl group is used, and more preferably a straight-chain or branched C _1-4 alkyl group is used. Examples of the cycloalkyl group include C _5-10 cycloalkyl groups such as cyclopentyl group and cyclohexyl group. Examples of the aryl group include C _6-12 aryl groups such as phenyl group, alkylphenyl group, biphenylyl group, and naphthyl group. Examples of the alkylphenyl group include methylphenyl group (tolyl group), dimethylphenyl group (xylyl group), and the like. Examples of the aralkyl group include C _6-10 aryl-C _1-4 alkyl groups such as benzyl group and phenethyl group.

Examples of the alkoxy group include linear or branched C _1-10 alkoxy groups such as methoxy group, ethoxy group, propoxy group, n-butoxy group, isobutoxy group, and t-butoxy group. Examples of the cycloalkyloxy group include C _5-10 cycloalkyloxy groups such as cyclohexyloxy group. Examples of the aryloxy group include C _6-10 aryloxy groups such as phenoxy groups. Examples of the aralkyloxy group include C _6-10 aryl-C _1-4 alkyloxy groups such as benzyloxy group. Examples of the alkylthio group include C _1-10 alkylthio groups such as methylthio group, ethylthio group, propylthio group, n-butylthio group, and t-butylthio group. Examples of the cycloalkylthio group include C _5-10 cycloalkylthio groups such as cyclohexylthio group. Examples of the arylthio group include C _6-10 arylthio groups such as thiophenoxy group. Examples of the aralkylthio group include C _6-10 aryl-C _1-4 alkylthio groups such as benzylthio groups. Examples of the acyl group include C _1-6 acyl groups such as acetyl groups.

Among these substituents, typical examples include a halogen atom; Hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aralkyl groups; Alkoxy group; Acyl group; nitro group; Cyano group; A substituted amino group, etc. are mentioned. Preferred examples of R ^1a and R ^1b include alkyl groups, cycloalkyl groups, aryl groups, alkoxy groups, etc., and examples of alkyl groups include linear or branched C _1-6 alkyl groups such as methyl groups, and cycloalkyl groups such as Examples of alkyl groups include C _5-8 cycloalkyl groups such as cyclohexyl groups, examples of aryl groups include C _6-14 aryl groups such as phenyl groups, and examples of alkoxy groups include straight chain groups such as methoxy groups. type or branched chain type C _1-4 alkoxy group, etc. In particular, examples of the alkyl group include linear or branched C _1-4 alkyl groups such as methyl groups. Substituent R ^1a and substituent R ^1b may be different substituents, but are usually the same substituent.

The substitution numbers m1 and m2 of R ^1a and R ^1b may be integers of 0 or more and can be appropriately selected depending on the types of ring Z ^1a and ring Z ^1b . For example, they may be integers of 0 to 8, respectively, and are preferred substitution The numbers m1 and m2 are, in steps below, an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, and 0 or 1, with 0 being most preferable. The substitution numbers m1 and m2 may be different substitution numbers, but are usually the same substitution numbers. Additionally, when the substitution numbers m1 and m2 are 2 or more, the types of 2 or more R ^1a or R ^1b may be the same or different. In particular, when m1 and m2 are 1, it is preferable that ring Z ^1a and ring Z ^1b are a benzene ring, a naphthalene ring or a biphenyl ring, and R ^1a and R ^1b are a methyl group. In addition, the substitution positions of R ^1a and R ^1b are not particularly limited, and the substitution may occur at positions other than the bonding positions between ring Z ^1a and ring Z ^1b , the ether bond (-O-), and the linking group X.

In the above formula (1), the alkylene groups A ^1a and A ^1b are a straight group such as ethylene group, propylene group (1,2-propanediyl group), trimethylene group, 1,2-butanediyl group, tetramethylene group, etc. Examples include chain or branched C _2-6 alkylene groups. Among these, a linear or branched C _2-4 alkylene group is preferred, a linear or branched C _2-3 alkylene group is more preferred, and an ethylene group is most preferred.

The repeating numbers (added moles) n1 and n2 of the oxyalkylene group (OA ^1a ) and the oxyalkylene group (OA ^1b ) may each be integers of 1 or more, for example, 1 to 20, and the preferred repeating numbers n1 and n2 are , Hereinafter, in steps, it is an integer of 1 to 15, 1 to 10, 2 to 9, 2 to 8, and 2 to 7, and most preferably, it is an integer of 3 to 6. Additionally, n1 and n2 may be the same or different. In addition, when n1 or n2 is 2 or more, two or more oxyalkylene groups (OA ^1a ) or oxyalkylene groups (OA ^1b ) may be the same or different, respectively. In addition, the oxyalkylene group (OA ^1a ) and the oxyalkylene group (OA ^1b ) may be the same or different from each other.

In addition, in the present specification and claims, the “number of repetitions (number of added moles)” may be an average value (arithmetic average value, valence average value) or an average number of added moles, and the preferred embodiment is the same as the range of the preferred integer.

When ring Z ^1a and ring Z ^1b are a monocyclic aromatic hydrocarbon ring such as a benzene ring or a ring-set aromatic hydrocarbon ring such as a biphenyl ring, n1+n2 can be selected from an integer range of, for example, 2 to 30. , the preferred range is an integer of 3 to 25, 4 to 20, 5 to 18, 6 to 16, 7 to 15, 8 to 14, and 9 to 13 in the following steps, and most preferably 10 to 12. The range of these n1+n2 may be the range in case ring Z ^1a and ring Z ^1b are benzene rings.

On the other hand, when ring Z ^1a and ring Z ^1b are condensed polycyclic aromatic hydrocarbon rings such as a naphthalene ring, from the viewpoint that the cured product tends to become rigid and flexibility tends to decrease, n1 + n2 may be an integer of 3 or more, and is preferably It is an integer of 4 or more, more preferably an integer of 5 or more, and most preferably an integer of 6 or more. When ring Z ^1a and ring Z ^1b are condensed polycyclic aromatic hydrocarbon rings such as a naphthalene ring, n1+n2 can be selected from an integer range of about 3 to 30, with preferred ranges being 4 to 25 and 5 to 5 in steps below. It may be an integer of 20, 6 to 18, 7 to 15, or 8 to 13, and most preferably an integer of 10 to 15.

As described above, n1+n2 may be an integer, but may be the average value (or average added mole number) of the molecular aggregate of the compound represented by the above formula (1). n1+n2 can be selected, for example, from a range of about 2 to 30, and can be selected from a range of about 2.5 to 25 regardless of the types of ring Z ^1a and ring Z ^1b . A preferable range is 3 to 3 in steps below. 20, 5 to 18, 6 to 17, 7 to 16, 7.5 to 15, 8 to 14, 9 to 13, 9.5 to 12.5, 10 to 12, and most preferably 10.5 to 11.5.

If the value of n1+n2 is too small, the crosslinking density of the cured product tends to increase and it also becomes difficult to develop flexibility due to the oxyalkylene group, so there is a risk that surface hardness and bending resistance cannot be achieved in a good balance. On the other hand, if the value of n1 + n2 is too large, the crosslinking density of the cured product significantly decreases, and surface hardness and bending resistance cannot be achieved in a good balance, and furthermore, per unit amount (unit mass) of the ring Z ^1a and ring Z ^1b containing skeleton Since the content (number of moles contained in the skeleton to which the arene ring is bonded via the linking group

In particular, as will be described later, when the skeleton is a 9,9-bis(aryl)fluorene skeleton linked by a fluorene ring as the linking group , a cured product is obtained that has both high hardness and flexibility (bending resistance) in a good balance. n1+n2 of the epoxy(meth)acrylate whose skeleton is the 9,9-bis(aryl)fluorene skeleton can be selected from an integer of about 3 to 20, with a preferable range being 4 to 18, 4 to 4 in the following steps. It is an integer of 17, 5 to 16, 7 to 15, 8 to 14, and 9 to 13, and most preferably is an integer of 10 to 12. In particular, if the integer is 8 to 14, preferably 9 to 13, and more preferably 10 to 12, high hardness is exhibited even though the side chain is relatively long.

The substitution position of the oxyalkylene group-containing group is not particularly limited, and it can be substituted at an appropriate position in ring Z ^1a or ring Z ^1b . For example, when ring Z ^1a and ring Z ^1b are benzene rings, the substitution position may be any of the 2 to 6 positions, and examples include the 2 position, the 3 position, and the 4 position, and is preferably the 3 position. , 4 positions, most preferably 4 positions. In addition, when ring Z ^1a and ring Z ^1b are naphthalene rings, the substitution position is often the 5th to 8th position of the naphthyl group, for example, the 1st or 2nd position of the naphthalene ring is substituted for the linking group (substituted in the relationship of 1-naphthyl or 2-naphthyl), with respect to this substitution position, the relationship at the 1, 5, 1, 6, and 2, 6 positions is preferable, and the relationship at the 2 and 6 positions is most preferable. do. Additionally, when ring Z ^1a and ring Z ^1b are biphenyl rings, they may be substituted with an arene ring bonded to linking group X or an arene ring adjacent to the arene ring. For example, the 3rd or 4th position of the biphenyl ring may be bonded to the linking group X, and when the 3rd position of the biphenyl ring is bonded to the linking group It may be any of the 4 to 6 positions and the 2' to 6' positions, and is usually the 4, 5, 6, 3', and 4' positions, with the 4, 6, and 4' positions being preferred. , 6 position is most preferred.

The groups R ^2a and R ^2b may be either a hydrogen atom or a methyl group, but a hydrogen atom is preferred from the viewpoint of reactivity. Group R ^2a and group R ^2b may be different from each other, but are usually the same.

The epoxy (meth)acrylate represented by the above formula (1) has both surface hardness and bending resistance, has no phase difference, and is excellent in visibility in an image display device, so the epoxy (meth)acrylate represented by the above formula (1a) Meth)acrylate is preferable, and epoxy (meth)acrylate represented by the above formula (1b) is most preferable.

In the above formula (1a), ring Z ^1a and ring Z ^1b , A ^1a and A ^1b , n1 and n2, R ^1a and R ^1b , m1 and m2, R ^2a and R ^2b are the same as the above formula (1), including preferred embodiments.

In addition, the substitution positions of ring Z ^1a and ring Z ^1b bonded to the 9th position of fluorene are the same as described above, but for example, when ring Z ^1a and ring Z ^1b are benzene rings, the substitution positions at positions 2 to 6 are It may be any, and examples include the 2nd, 3rd, and 4th positions, preferably the 3rd and 4th positions, and most preferably the 4th position as in the above formula (1b).

In the above formula (1a), the substituent represented by R ⁴ is not particularly limited as long as it is a substituent that is non-reactive to an epoxy group, and examples include hydrocarbon groups such as alkyl groups and aryl groups, cyano groups, and halogen atoms. Examples of the alkyl group include linear or branched C _1-6 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and t-butyl groups. Examples of the aryl group include C _6-10 aryl groups such as phenyl groups. Halogen atoms include fluorine atoms, chlorine atoms, and bromine atoms. These substituents can be used individually or in combination of two or more types.

Among these substituents, an alkyl group, a cyano group, and a halogen atom are preferable, and a straight-chain or branched C _1-4 alkyl group is particularly preferable. Furthermore, among linear or branched C _1-4 alkyl groups, linear or branched C _1-3 alkyl groups are preferable, and C _1-2 alkyl groups such as methyl groups are particularly preferable.

The substitution number k of R ⁴ is an integer of 0 to 8, and the preferred range is an integer of 0 to 6, an integer of 0 to 4, and an integer of 0 to 2 in the following steps, with 0 being most preferable. Additionally, when k is 2 or more, the types of each R ⁵ may be the same or different from each other. In addition, when k is 2 or more, the types of 2 or more R ⁴ substituted by the same or different benzene rings may be the same or different from each other. In addition, the substitution position of R ⁴ is not particularly limited, and for example, it may be any of the 2nd to 7th positions of the fluorene ring, and is usually any of the 2nd, 3rd, and 7th positions.

Among the epoxy (meth)acrylates represented by the formula (1a), representative compounds include, for example, compounds wherein in the formula (1a), ring Z ^1a and ring Z ^1b are benzene rings, and n1 = n2 = 1. , that is, 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)alkoxyphenyl]fluorene; In the above formula (1a), ring Z ^1a and ring Z ^1b are a benzene ring or a naphthalene ring, and n1 and n2 are 2 to 10, that is, a compound in which 9,9-bis[(3-(meth)acryloyloxy -2-hydroxypropoxy)polyalkoxyphenyl]fluorene; 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)polyalkoxynaphthyl]fluorene, etc. can be mentioned.

As 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)alkoxyphenyl]fluorene, in the above formula (1a), ring Z ^1a and ring Z ^1b are substituted. or an unsubstituted benzene ring, k=0, A ^1a and A ^1b are C _2-4 alkylene groups, n1=n2=1, such as (1a-1)9,9-bis[4-(2) -(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)phenyl]fluorene, 9,9-bis[4-(2-(3-(meth)acryloyloxy-2 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)C _2-4 alkoxyphenyl]fluorene such as -hydroxypropoxy)propoxy)phenyl]fluorene; (1a-2)9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-3-methylphenyl]fluorene, 9,9-bis [4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)-3-methylphenyl]fluorene, 9,9-bis[4-(2-(3-( Meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-3-isopropylphenyl]fluorene, 9,9-bis[4-(2-(3-(meth)acryloyloxy-2 -Hydroxypropoxy)ethoxy)-3-isobutylphenyl]fluorene, 9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy) )-3-t-butylphenyl]fluorene, 9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-3,5-dimethyl Phenyl] fluorene, 9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-3-t-butyl-6-methylphenyl]fluorene , 9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-2,5-dimethylphenyl]fluorene, etc. [(3-(meth)acryloyloxy-2-hydroxypropoxy)C _2-4 alkoxy-mono or diC _1-4 alkylphenyl]fluorene; (1a-3)9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-3-cyclohexylphenyl]fluorene, 9,9 -Bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)-3-cyclohexylphenyl]fluorene and other 9,9-bis[(3-( Meth)acryloyloxy-2-hydroxypropoxy)C _2-4 alkoxy-C _5-10 cycloalkylphenyl]fluorene; (1a-4)9,9-bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)-3-phenylphenyl]fluorene, 9,9- 9,9-bis[(3-(meth) such as bis[4-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)-3-phenylphenyl]fluorene Acryloyloxy-2-hydroxypropoxy)C _2-4 alkoxy-C _6-10 arylphenyl]fluorene, etc. are mentioned.

As 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)polyalkoxyphenyl]fluorene, in the above formula (1a), ring Z ^1a and ring Z ^1b are A substituted or unsubstituted benzene ring, k = 0, A ^1a and A ^1b are C _2-4 alkylene groups, n1 and n2 are each 2 to 10, that is, compounds (1a-1) to (1a-4) above. Corresponding to the compounds of , n1 and n2 are each 2 to 10, such as (1a-5)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy -2-hydroxypropoxy)ethoxy)ethoxy)phenyl]fluorene, 9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy) ) propoxy) propoxy) phenyl] fluorene, 9,9-bis[4-(2-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy) 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxyphenyl]fluorene such as ethoxy)ethoxy)phenyl]fluorene; (1a-6)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3-methylphenyl]fluorene , 9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)propoxy)-3-methylphenyl]fluorene, 9,9 -bis[4-(2-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)ethoxy)-3-isopropylphenyl]fluorene , 9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3,5-dimethylphenyl]fluorene, etc. 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxy-mono or diC _1-4 alkylphenyl]fluorene; (1a-7)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3-cyclohexylphenyl] Fluorene, 9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)propoxy)-3-cyclohexylphenyl]fluorene , 9,9-bis[4-(2-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)ethoxy)-3-cyclohexyl 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxy-C _5-10 cycloalkylphenyl]fluorene such as phenyl]fluorene; (1a-8)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3-phenylphenyl]flu Orene, 9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)propoxy)-3-phenylphenyl]fluorene, 9 ,9-bis[4-(2-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)ethoxy)-3-phenylphenyl]flu 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxy-C _6-10 arylphenyl]fluorene such as orene. .

9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)polyalkoxynaphthyl]fluorene, in formula (1a) above, ring Z ^1a and ring Z ^1b A substituted or unsubstituted naphthalene ring, k=0, A ^1a and A ^1b are C _2-4 alkylene groups, and n1 and n2 are each 2 to 10, such as (1a-9)9,9- Bis[6-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-2-naphthyl]fluorene, 9,9-bis[6 -(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)propoxy)propoxy)-2-naphthyl]fluorene, 9,9-bis[6-(2 -(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)ethoxy)-2-naphthyl]fluorene, 9,9-bis[5 -(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-1-naphthyl]fluorene, etc. 9,9-bis[(3- (meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxynaphthyl]fluorene, etc.

These epoxy (meth)acrylates may be used individually or in combination of two or more to form a molecular aggregate. Preferred epoxy (meth)acrylates include compounds in which, in the formula (1a), ring Z ^1a and ring Z ^1b are benzene rings or naphthalene rings, and n1 and n2 are each 2 to 10, that is, 9,9-bis. [(3-(meth)acryloyloxy-2-hydroxypropoxy)polyalkoxyphenyl]fluorene; and 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)polyalkoxynaphthyl]fluorene.

Among these epoxy (meth)acrylates, (1a-5)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy) 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxyphenyl]fluorene such as ethoxy)phenyl]fluorene; (1a-6)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3-methylphenyl]fluorene 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxy-mono or diC _1-4 alkylphenyl]fluorene, such as; (1a-8)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3-phenylphenyl]flu 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxy-C _6-10 arylphenyl]fluorene such as Orene; (1a-9)9,9-bis[6-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-2-naphthyl]flu orene, 9,9-bis[5-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy-1-naphthyl]fluorene, etc. , 9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxynaphthyl]fluorene is preferred.

In addition, among the epoxy (meth)acrylates, in the formula (1a), rings Z ^1a and Z ^1b are benzene rings, R ^1a and R ^1b are alkyl groups, and m1 and m2 are 0 to 2, that is, The (1a-5)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)phenyl]fluorene, etc. 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxyphenyl]fluorene; (1a-6)9,9-bis[4-(2-(2-(3-(meth)acryloyloxy-2-hydroxypropoxy)ethoxy)ethoxy)-3-methylphenyl]fluorene 9,9-bis[(3-(meth)acryloyloxy-2-hydroxypropoxy)di to decaC _2-4 alkoxy-mono or diC _1-4 alkylphenyl]fluorene, such as .

The proportion of the epoxy (meth)acrylate represented by the formula (1a) may be 50 to 100 mol%, preferably 70 to 100 mol%, and more preferably 70 to 100 mol% of the epoxy (meth)acrylate represented by the formula (1). Typically, it is 80 to 100 mol%, more preferably 90 to 100 mol%, and 100 mol% is most preferable.

[Method for producing epoxy (meth)acrylate]

The method for producing epoxy (meth)acrylate represented by the above formula (1) is not particularly limited, and a common method can be used as long as the oxyalkylene group addition number, that is, n1+n2, can be adjusted to a predetermined range. In particular, the method for producing epoxy (meth)acrylate represented by the above formula (1a) may be, for example, method (A) in which an epoxy compound represented by the following formula (3) and a (meth)acrylic acid component are reacted. In addition, the epoxy compound represented by the above formula (3) can be produced by the method described in Japanese Patent Application Laid-Open No. 2009-155256, etc.

[Formula 5]

(wherein ring Z ^1a and ring Z ^1b , A ^1a and A ^1b , n1 and n2, R ^1a and R ^1b , m1 and m2, R ⁴ , k are the same as above)

Alternatively, the method (B) of reacting the first hydroxy compound represented by the following formula (4) with glycidyl (meth)acrylate may be used, for example, the method described in Japanese Patent Application Laid-Open No. 2004-83855.

[Formula 6]

(wherein ring Z ^1a and ring Z ^1b , A ^1a and A ^1b , n1 and n2, R ^1a and R ^1b , m1 and m2, R ⁴ , k are the same as above)

From the viewpoint of reactivity etc., it is usually prepared by method (A) in many cases. In addition, the epoxy compound represented by the formula (3) used in the method (A) may be a commercial product, or may be prepared by a conventional method, for example, by combining the first hydroxy compound represented by the formula (4) and epi It may be prepared by, for example, a method of reacting epihalohydrin such as chlorohydrin or epibromohydrin. Therefore, even when preparing the epoxy (meth)acrylate represented by the formula (1a) by either method (A) or (B), the oxyalkyl of the first hydroxy compound represented by the formula (4) By controlling the ene group addition number (n1+n2) to a predetermined range, the oxyalkylene group addition number (n1+n2) in the epoxy compound represented by the above formula (3) and the epoxy (meth)acrylate represented by the above formula (1a) is adjusted. You can do it. In addition, the epoxy compound represented by the formula (3) and the first hydroxy compound represented by the formula (4) may each be a molecular aggregate, and the addition number of each oxyalkylene group (n1+n2) is also represented by the formula (1a) As with the epoxy (meth)acrylate shown, it may be the average value of the molecular aggregate.

(First hydroxy compound represented by formula (4) above)

In the above formula (4), ring Z ^1a and ring Z ^1b , A ^1a and A ^1b , n1 and n2, R ^1a and R ^1b , m1 and m2, R ^2a and R ^2b , R ⁴ , k are each preferred The aspects and the like are the same as those described above. Representative first hydroxy compounds represented by the formula (4) include, for example, compounds (1a-1) to (1a-9) exemplified as representative examples of the epoxy (meth)acrylate represented by the formula (1a). ), that is, a compound in which the 3-(meth)acryloyloxy-2-hydroxypropyl group is replaced with a hydrogen atom can be mentioned. These compounds may be contained individually or in combination of two or more types as a molecular aggregate.

The first hydroxy compound represented by the formula (4) is not particularly limited, and commercial products may be used. For example, the second hydroxy compound represented by the formula (5) below and the formula ( It may be prepared by a method such as reacting alkylene oxide or alkylene carbonate corresponding to the oxyalkylene groups OA ^1a and OA ^1b in 4). As a specific manufacturing method, the method described in Patent Document 5 (Japanese Patent Application Publication No. 2017-186513), etc. can be used.

[Formula 7]

(wherein n3 and n4 each represent 0 or 1, ring Z ^1a and ring Z ^1b , A ^1a and A ^1b , R ^1a and R ^1b , m1 and m2, R ⁴ , k are the same as above)

(Method (A))

Regarding the specific production method for preparing the epoxy (meth)acrylate represented by the formula (1a) using the epoxy compound represented by the formula (3) and the method (A), see Patent Document 5 (Japanese Patent Application Publication No. 2017-186513) The method described in ) can be used.

Additionally, in the present invention, since the addition number of the oxyalkylene group (n1+n2) is adjusted to a predetermined range, the viscosity is relatively low and the handleability is excellent. The viscosity of the epoxy (meth)acrylate represented by the above formula (1a) at a temperature of 25°C can be selected in the range of about 5000 to 150000 mPa·s, for example, 10000 to 60000 mPa·s, preferably 20000. ~ 50000 mPa·s, more preferably 30000 ~ 45000 mPa·s, most preferably 35000 ~ 40000 mPa·s.

In addition, in the present specification and claims, the viscosity is measured at 25°C using a TV-22 type viscometer (cone plate type, “TVE-22L” manufactured by Toki Sangyo Co., Ltd.). Options depending on the viscosity It can be measured with a rotor (01: 1˚34'×R24, 07: 3˚×R7.7) at 1 to 20 rpm (selected according to viscosity).

[Curable composition]

The epoxy (meth)acrylate may be used alone, or may be mixed with other components such as an ultraviolet absorber, a polymerization initiator, another polymerizable compound, and a solvent to form a curable composition.

(UV absorbent)

The curable composition, which is one of the preferred embodiments of the present invention, may contain an ultraviolet absorber. As the ultraviolet absorber, a conventional ultraviolet absorber can be used.

The curable composition containing an ultraviolet absorber has excellent light resistance, and as described later, it is effective to laminate it on the surface of a polarizing plate to function as a polarizer protective film. In order to prevent deterioration of iodine by ultraviolet rays, the polarizer protective film needs to block ultraviolet rays with a wavelength of 380 nm or less, and in detail, it is said that the spectral transmittance of 380 nm needs to be 10% or less. In order to satisfy these requirements, the addition of an ultraviolet absorber having a maximum absorption wavelength of 320 to 400 nm, called UVA, is effective. Examples of such ultraviolet absorbers include oxybenzophenone-based compounds, benzotriazole-based compounds, and triazine-based compounds.

Examples of the oxybenzophenone-based compound include 2,4-dihydroxybenzophenone; 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-pentyloxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-octyloxy-4'-me Hydroxy C _1-18 alkoxy benzophenone such as toxin benzophenone; Hydroxycycloalkyloxybenzophenones such as 2-hydroxy-4-cyclohexyloxybenzophenone; and hydroxyC _1-18 alkoxyhalobenzophenones such as 2-hydroxy-4-octyloxy-4'-chlorobenzophenone. These oxybenzophenone compounds can be used individually or in combination of two or more types. Commercially available products include Adekastab 1413 from ADEKA Co., Ltd. and Chimassorb81 from BASF Japan Co., Ltd. Among these, oxybenzophenone compounds having a straight chain alkyl group of 2 or more carbon atoms, such as 2-hydroxy-4-octyloxybenzophenone, are preferred because it is easy to prepare a uniform composition. The carbon number of the straight-chain alkyl group having 2 or more carbon atoms can be selected from the range of about 2 to 18, and the preferred range is 3 to 16, 4 to 14, 5 to 12, and 6 to 10 in the following steps, and most preferably 7. It is ~ 9.

In addition, in the present specification and claims, the term straight-chain alkyl group is used to also include straight-chain alkyl groups included in branched-chain alkyl groups (for example, ethyl group and n-butyl group in 2-ethylhexyl group).

Benzotriazole-based compounds include, for example, 2-(2H-benzotriazol-2-yl)-4-methyl-phenol, 2-(2H-benzotriazol-2-yl)-4-t-butyl -Phenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol, 2-(2H-benzotriazol-2-yl)-4 Benzotriazol-2-yl-C _1-18 alkyl-phenol such as -methyl-6-dodecyl-phenol; Benzotriazol-2-yl-bis(phenylC _1-18 alkyl)-phenol such as 2-(2H-benzotriazol-2-yl)-4,6-bis(1-phenylethyl)phenol; Benzotriazol-2-yl-bis(C _1-18 alkyl-phenyl, such as 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)-phenol C _1-18 alkyl)-phenol; Benzotriazole-2, such as 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol -yl-(C _1-18 alkyl-phenylC _1-18 alkyl)-C _1-18 alkyl-phenol; Halobenzotriazol-2-yl-C _1-18 alkyl, such as 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methyl-phenol -Phenol; 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2,2'-methylene-bis[6 -(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol], etc. Methylene-bis(benzotriazol-2-yl-C _1-18 alkyl -phenol) ; 2-(2-hydroxy-3-α-cumyl-5-dodecylphenyl)-2H-benzotriazole, etc. 2-(hydroxy-α-cumyl-5-C _1-18 alkyl-phenyl)-2H -benzotriazole; Octyl-3-[3-(1,1-dimethylethyl)-4-hydroxy-5-(2H-benzotriazol-2-yl)phenyl]propionate, octyl-3-[3-tert-butyl -4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate, 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5- C _1-18 alkyl-[C 1-18 alkyl-hydroxy-((halo)-2H-benzotriazole-2, such as (5-chloro- _2H -benzotriazol-2-yl)phenyl]propionate -1) phenyl] C _2-4 acylate, etc. can be mentioned.

These benzotriazole-based compounds can be used individually or in combination of two or more types. Commercially available benzotriazole compounds include Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 329, Tinuvin 360, Tinuvin 571, Tinuvin 99-2, Tinuvin 213, and Tinuvin 900 from BASF Japan Co., Ltd. , Tinuvin 928, Adekastab LA-31 from ADEKA Co., Ltd., and Eversorb89, Eversorb109, and EversorbBL1A from Everlight Chemical.

Among these benzotriazole-based compounds, octyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl) is preferred because it is easy to prepare a uniform composition. Benzotriazole-based compounds having a straight-chain alkyl group of 2 or more carbon atoms, such as phenyl]propionate, are preferable. The carbon number of the straight-chain alkyl group having 2 or more carbon atoms can be selected from the range of about 2 to 18, and the preferred range is 3 to 16, 4 to 14, 5 to 12, and 6 to 10 in the following steps, and most preferably 7. It is ~ 9.

Triazine-based compounds include, for example, 2-(4-hexyloxy-2-hydroxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-[4-[(2 -Hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, etc. Roxy-C _1-18 alkoxy-hydroxyphenyl)bis(diC _1-18 alkyl-phenyl)-1,3,5-triazine; Bis(hydroxy-C _1- , such as 2,4-bis(2-hydroxy-4-butoxy-phenyl)-6-(2,4-dibutoxy-phenyl)-1,3,5-triazine ₁₈ alkoxy-phenyl)-(diC _1-18 alkoxy-phenyl)-1,3,5-triazine; Tris(hydroxy-C _1-18 alkoxy-C _1-18 alkyl, such as 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine -phenyl)-1,3,5-triazine, etc. can be mentioned. These triazine compounds can be used individually or in combination of two or more types. Commercially available products include Tinuvin 405 and Tinuvin 460 from BASF Japan Co., Ltd. and Adekastave CA-F70 from ADEKA Co., Ltd. Among these, because it is easy to prepare a uniform composition, those having 2 or more carbon atoms such as 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine Oxybenzophenone compounds having a straight-chain alkyl group are preferred. The carbon number of the straight-chain alkyl group having 2 or more carbon atoms can be selected from the range of about 2 to 18, and the preferred range is 3 to 16, 4 to 14, 5 to 12, and 6 to 10 in the following steps, and most preferably 7. It is ~ 9.

These ultraviolet absorbers can be used individually or in combination of two or more types. Among these ultraviolet absorbers, benzotriazole-based compounds are preferable, and benzotriazole-based compounds having a straight-chain alkyl group having 4 or more carbon atoms are more preferable because it is easy to prepare a uniform composition. Among them, C _4-12 alkyl-[C _2-16 alkyl-hydroxy-(halo-2H-benzotriazol-2-yl)phenyl]C _2-4 acylate is preferable, and C _4-10 alkyl- [Branched chain C _3-12 alkyl-hydroxy-(halo-2H-benzotriazol-2-yl)phenyl]C _3-4 acylate is particularly preferred.

The type and addition amount of the ultraviolet absorber can be set in an optimal range depending on the absorption spectrum and molar extinction coefficient of the ultraviolet absorber and the compatibility of the curable resin composition. Specifically, it can be determined based on the evaluation results of total light transmittance (JIS K7361), spectral transmittance at 380 nm (JIS K7105), haze (JIS K7136), and yellowness (YI) (JIS K7373) of the prepared cured film. there is. Although it is not limited to the values below, the total light transmittance is preferably 85% or more, more preferably 88% or more, and especially preferably 89% or more. The lower the spectral transmittance at 380 nm, the more preferable it is, for example, 20% or less is preferable, 10% or less is more preferable, and 8% or less is especially preferable. The lower the haze value, the more preferable it is, for example, more preferably 1% or less. The evaluation standard for YI is 1 or less. It is better for the maximum absorption wavelength to be close to 380 nm, but as it approaches 400 nm, yellow coloring becomes stronger, which is not desirable. In order to achieve a spectral transmittance of 10% or less at 380 nm, if the molar extinction coefficient at 380 nm is too low, the amount added increases and the insoluble content becomes haze or bleeds out, which is not preferable.

The ratio of the ultraviolet absorber is the total amount of (meth)acryloyl group-containing components in the curable composition (for example, the total amount of epoxy (meth)acrylate represented by the above formula (1) and other polymerizable compounds described later, etc.) 100 mass. Part by mass, for example, 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 0.8 to 5 parts by mass, and most preferably 1 to 3 parts by mass. In particular, since the UV blocking ability can be improved even with a small amount of addition, and various properties such as optical and mechanical properties are excellent, the ratio of the UV absorber is determined by the total amount of (meth)acryloyl group-containing component in the curable composition. For example, it is 0.6 to 3 parts by mass, preferably 0.7 to 2 parts by mass, more preferably 0.8 to 1.5 parts by mass, more preferably 0.9 to 1.2 parts by mass, and most preferably 0.9 to 1.1 parts by mass. . If the ratio of the ultraviolet absorber is too small, there is a risk that the effect of improving light resistance will not be realized, and conversely, if it is too large, there is a risk that the mechanical properties of the cured product may deteriorate.

(polymerization initiator)

The curable composition, which is one of the preferred embodiments of the present invention, may contain a thermal polymerization initiator and/or a photopolymerization initiator. Thermal polymerization initiators include organic peroxides, aso compounds, and the like. Examples of organic peroxides include dialkyl peroxides such as di-t-butyl peroxide; Diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; Peracids (or peracid esters) such as t-butylhydroperoxide, cumene hydroperoxide, and t-butyl peracetate; Ketone peroxides; Peroxycarbonates; Peroxyketals, etc. can be mentioned. Examples of the azo compound include azonitrile compounds such as 2,2'-azobis(isobutyronitrile); Azoamide compound; Azoamidine compounds, etc. can be mentioned. These thermal polymerization initiators can be used individually or in combination of two or more types.

Examples of the photopolymerization initiator (or radical photopolymerization initiator) include benzoins such as benzoin; Benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzoin phenyl ether; Acetophenone, 3-hydroxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hyde Roxycyclohexylphenylketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4- [4-(2-Hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1- Acetophenones such as on; 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1 Aminoacetophenones such as -one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one; Anthraquinones such as anthraquinone, anthraquinone-2-sulfonate, and 2-ethylanthraquinone; Thioxanthone such as thioxanthone, isopropoxychlorothioxanthone, 2-chlorothioxanthone, and 2,4-dimethylxanthone; Ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; Benzophenone, such as benzophenone, 4-hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 4,4'-dichlorobenzophenone, 3-methylbenzophenone, and 4-phenylbenzophenone; 2,4, such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer, 5-triarylimidazole dimer; xanthons; 2,4,6-trihalomethyltriazine; Acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl- Acylphosphine oxides, such as diphenyl-phosphine oxide, etc. are mentioned. These photopolymerization initiators can be used individually or in combination of two or more types.

When the curable composition contains an ultraviolet absorber that absorbs ultraviolet rays with a shorter wavelength than 400 nm, in order to efficiently photocure using visible light, the photopolymerization initiator has a threshold (threshold or maximum absorption wavelength) of 400 to 450 nm. It is preferable to include an initiator (a photopolymerization initiator with an absorption wavelength in the long wavelength range), a photopolymerization initiator with an absorption wavelength in the long wavelength range, and a photopolymerization initiator with a threshold below 400 nm (a photopolymerization initiator with an absorption wavelength in the short wavelength range). A combination of is particularly preferred.

Examples of the photopolymerization initiator (long-wavelength photopolymerization initiator) having an absorption wavelength in the long wavelength region include aminoacetophenones (α-aminoacetophenone compounds), acylphosphine oxides, and the like, among the above photopolymerization initiators. As commercially available aminoacetophenones, for example, IRGACURE369, IRGACURE379, IRGACURE907, etc. from BASF Japan Co., Ltd. can be used. Commercially available products of acylphosphine oxides include, for example, IRGACURE819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide) and IRGACURE1800 (bis(2,6-dimethoxybenzoyl)) manufactured by BASF Japan Co., Ltd. Phosphine oxide), DAROCUR TPO, etc. can be used. Among these, acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide are preferable.

Examples of the photopolymerization initiator (short-wavelength photopolymerization initiator) having an absorption wavelength in the short wavelength range include photopolymerization initiators other than aminoacetophenones and acylphosphine oxides among the above photopolymerization initiators. Among the photopolymerization initiators, acetophenones such as 1-hydroxycyclohexylphenyl ketone are preferable. As a commercial product of acetophenones, for example, IRGACURE184 [phenyl (1-hydroxycyclohexyl) ketone] manufactured by BASF Japan Co., Ltd. can be used.

The ratio of the polymerization initiator (thermal and/or photopolymerization initiator) is the total amount of (meth)acryloyl group-containing components in the curable composition (e.g., epoxy (meth)acrylate represented by the above formula (1) and other polymerizations described later) Total amount of chemical compounds, etc.) is, for example, 0.1 to 15 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, and most preferably 2 to 5 parts by mass, based on 100 parts by mass. . Among these polymerization initiators, it is preferable to include at least a photopolymerization initiator.

When combining a short-wavelength photopolymerization initiator and a long-wavelength photopolymerization initiator, the ratio of the long-wavelength photopolymerization initiator may be 1 part by mass or more per 100 parts by mass of the short-wavelength photopolymerization initiator, for example, 1 to 200 parts by mass, preferably 5 to 150 parts by mass. parts, more preferably 10 to 100 parts by mass, most preferably 20 to 50 parts by mass. If the ratio of the long-wavelength photopolymerization initiator is too small and the curable composition contains an ultraviolet absorber, there is a risk that photocurability may decrease.

Additionally, the photopolymerization initiator may be combined with a photosensitizer. The photosensitizer may be a conventional photosensitizer such as tertiary amines. Tertiary amines include trialkylamine; Trialkanolamines such as triethanolamine; dialkylaminobenzoic acid alkyl esters such as ethyl N,N-dimethylaminobenzoate and amyl N,N-dimethylaminobenzoate; Bis(dialkylamino)benzophenone such as 4,4-bis(dimethylamino)benzophenone and 4,4-bis(diethylamino)benzophenone; and dialkylaminobenzophenones such as 4-(dimethylamino)benzophenone and 4-methoxy-4'-dimethylaminobenzophenone. These photosensitizers can be used individually or in combination of two or more types. When the curable composition contains an ultraviolet absorber that absorbs ultraviolet rays with a wavelength shorter than 400 nm, the photosensitizer is preferably a photosensitizer with an absorption wavelength of 400 to 450 nm.

The ratio of the photosensitizer is, for example, 1 to 200 parts by mass, preferably 5 to 150 parts by mass, and more preferably 10 to 100 parts by mass, with respect to 100 parts by mass of the photopolymerization initiator.

(Other polymerizable compounds)

The curable composition, which is one of the preferred embodiments of the present invention, may further contain a polymerizable compound having one or more polymerizable functional groups in the molecule, thereby improving sensitivity (or curability), fluidity, chemical resistance, heat resistance, or mechanical strength. You can also improve your back. The other polymerizable compound may be a polymerizable compound having a vinyl group, but is often a monofunctional or polyfunctional (meth)acrylate having a (meth)acryloyl group.

Examples of monofunctional (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; Hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate; Alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate; Cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate; Aryl (meth)acrylate such as phenyl (meth)acrylate; Aryloxyalkyl (meth)acrylates such as phenoxyethyl (meth)acrylate; Aralkyl (meth)acrylates such as benzyl (meth)acrylate; Aryloxy ((poly)alkoxy)alkyl (meth)acrylates such as phenoxyethoxyethyl (meth)acrylate; Alkylaryloxyalkyl (meth)acrylates such as nonylphenoxyethyl (meth)acrylate; Alkylaryloxy(poly)alkoxyalkyl(meth)acrylates such as nonylphenoxy(poly)ethoxyethyl(meth)acrylate; Arylaryloxyalkyl (meth)acrylates such as 2-(o-phenylphenoxy)ethyl (meth)acrylate; Arylaryloxy(poly)alkoxyalkyl(meth)acrylates such as phenylphenoxy(poly)ethoxyethyl(meth)acrylate; Alkylthio(meth)acrylates such as methylthio(meth)acrylate; Arylthio(meth)acrylates such as phenylthio(meth)acrylate; Aralkylthio(meth)acrylates such as benzylthio(meth)acrylate; Arylthioalkyl (meth)acrylates such as phenylthioethyl (meth)acrylate; N,N-dialkyl (meth)acrylamides such as N,N-dimethylaminoethyl (meth)acrylate; Bisphenols, such as the mono(meth)acrylate of the ethylene oxide adduct of bisphenol A, or the mono(meth)acrylate of its alkylene oxide adduct; (meth)acrylates having a fluorene skeleton such as 9-(meth)acryloyloxymethylfluorene, etc. can be mentioned.

Polyfunctional (meth)acrylates can be roughly divided into difunctional (meth)acrylates and trifunctional (meth)acrylates or higher. Bifunctional (meth)acrylates include (poly)C _2-4 alkylene glycol diacrylates such as ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, and dipropylene glycol di(meth)acrylate. (meth)acrylate; Di(meth)acrylate of bisphenol A (or its alkylene oxide adduct), 9,9-bis[4-(2-(meth)acryloyloxy(poly)ethoxy)phenyl]fluorene, etc. You can. Examples of tri-functional or higher (meth)acrylates include glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, Tri to hexaol tri to hexa(meth)acrylates such as dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate]; Urethane (meth)acrylate; 3- to 6-functional (meth)acrylate having a fluorene skeleton [e.g., 9,9-bis[4-(2-(meth)acryloyloxy(poly)ethoxy)phenyl]fluorene, etc. can be mentioned.

These monofunctional and polyfunctional (meth)acrylates can also be used individually or in combination of two or more types.

The ratio of these polymerizable compounds can be selected from a range of, for example, 0 to 50 parts by mass, preferably 0 to 30 parts by mass, based on 100 parts by mass of the epoxy (meth)acrylate represented by the formula (1). parts, more preferably 0 to 20 parts by mass, most preferably 0 to 10 parts by mass.

(Other additives)

Additionally, the curable composition may contain a solvent as needed. The solvent is not particularly limited and includes dialkyl ketones such as acetone, diisopropyl ketone, and methyl isobutyl ketone; Cyclic ketone diethyl ether such as cyclohexanone, and chain ether such as diisopropyl ether; Cyclic ethers such as tetrahydrofuran and dioxane; Alkylene glycol monoalkyl ether acetates such as methyl cellosolve acetate and propylene glycol monomethyl ether acetate; Ester such as ethyl acetate; Nitriles such as acetonitrile; Amides such as dimethylformamide and dimethylacetamide; Sulfoxides; Aliphatic hydrocarbons such as hexane and heptane; Alicyclic hydrocarbons such as cyclohexane; Aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; Halogen-based hydrocarbons such as methylene chloride, chloroform, and 1,2-dichloroethane can be mentioned. These solvents can also be used individually or in combination of two or more types as a mixed solvent.

In addition, the curable composition may contain conventional additives such as colorants, stabilizers, polymerization inhibitors, fillers, antistatic agents, flame retardants, surfactants, plasticizers, anti-foaming agents, coupling agents, etc., as long as they do not impair the effect of the present invention. It may be included. Examples of the stabilizer include heat stabilizers and antioxidants. These additives can be used individually or in combination of two or more types. The total ratio of additives is, for example, 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the total amount of the epoxy (meth)acrylate and other polymerizable compounds represented by the formula (1). More preferably, it is 1 to 5 parts by mass.

[Hardened product]

The curable composition is easily cured by applying activation energy (active energy rays). As for the activation energy, heat energy and/or light energy are useful, and can be appropriately selected depending on the purpose, etc. Examples of light energy include ultraviolet rays, electron beams, and X-rays.

When using thermal energy, the heating temperature is, for example, 50 to 250°C, preferably 60 to 120°C, and more preferably 70 to 100°C. The heating time is, for example, 5 minutes to 12 hours, preferably 10 minutes to 8 hours, and more preferably 30 minutes to 4 hours.

In addition, when using light energy such as ultraviolet rays, the amount of light irradiation energy can be appropriately selected depending on the application, for example, 50 to 10000 mJ/cm2, preferably 70 to 8000 mJ/ ^cm2 , more preferably 100 to 5000 mJ/cm ² , most preferably 300 to 3000 mJ/cm ² . As a light source, a deep UV lamp, low-pressure mercury lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, halogen lamp, laser light source such as a helium-cadmium laser or an excimer laser can be used.

Also, in the case of curing by light irradiation, heat treatment such as baking or after-baking may be performed to improve reactivity. The temperature and time of heat treatment are the same as in the case of using the heat energy. In addition, the reaction (or polymerization, crosslinking, or curing) may be carried out in an atmospheric atmosphere or an inert gas atmosphere, and the inert gas atmosphere may be carried out under normal pressure, under increased pressure, or under reduced pressure. Examples of the inert gas atmosphere include nitrogen atmosphere, helium, argon, etc. atmosphere, etc.

The cured product, which is one of the preferred embodiments of the present invention, has surprisingly high hardness despite the introduction of a highly flexible oxyalkylene group, and it coexists the conflicting characteristics of high hardness and flexibility with a good balance. Although the reason is not clear, it is presumed that a hydrogen bond is formed between the introduced oxyalkylene group and the hydroxyl group of the epoxy (meth)acrylate. Usually, when an oxyalkylene group is introduced, the cured product has a structure that is prone to bending, and the crosslinking density also decreases, so the flexibility of the cured product tends to improve significantly. For this reason, hardness, which is a characteristic opposite to flexibility, is greatly reduced. However, the epoxy (meth)acrylate represented by the above formula (1) has a hydroxyl group (hydroxyl group adjacent to the (meth)acryloyl group) in the side chain, and the addition number of the oxyalkylene group (n1+n2) Perhaps because is adjusted to a predetermined range, the oxyalkylene group is relatively easy to move even in the cured product, and the oxygen atom of the oxyalkylene group and the hydroxyl group easily form a hydrogen bond, forming a pseudo-crosslinking point. , it is believed that crosslinking density and hardness are improved. In addition, when the crosslink density and hardness are improved, the original flexibility is generally lost. However, in a cured product of a preferred embodiment of the present invention, the binding energy of hydrogen bonds is relatively low, and when an external force of a certain level or more is applied, it is easy to It is presumed that high hardness and flexibility can be achieved at the same time, perhaps because the bonds are released (crosslinking density is lowered), flexibility derived from the oxyalkylene group is expressed, and new hydrogen bonds are formed when the external force is removed.

[Optical film]

Below, an embodiment of a method for producing an optical film (a cured film formed from a cured product of the above curable composition), which is one of the preferred embodiments of the present invention, will be described.

1 is a schematic diagram of the manufacturing process of an optical film, which is one of the preferred embodiments of the present invention. Since the curable composition that serves as the raw material for the optical film is liquid, a known coating device can be used. As shown in FIG. 1, the curable composition 3 is cast-coated in a film form from the coating head 4 on the support film 2 unwound from the unwinding device 1. The soft-applied curable composition (3) is cured by irradiating a predetermined amount of light with an ultraviolet irradiation device (5), and the cured film-like cured product (cured film) (7) is applied to the support film (2) by the winding device (6). ) and is wound by the cured film winding device 8.

The method of flexible application of the curable composition is not particularly limited as long as it can be used in the technical field to which this technology belongs, and includes bar coating method, knife coating method, roll coating method, blade coating method, die coating method, micro gravure coating method, Comma coating method, slot die coating method, lip coating method, solution casting method, etc. can be used.

The curable composition is preferably in a liquid form, and may be used after adjusting the viscosity by using a solvent as a diluent. For example, as a method of adding the ultraviolet absorber, the ultraviolet absorber may be dissolved in an alcohol such as methanol, ethanol, butanol, an organic solvent such as methylene chloride, methyl acetate, acetone, and dioxolane, or a mixed solvent thereof and added as a solution. However, in that case, considering the volatilization removal process of the solvent, it takes time and production efficiency is reduced, and the presence of residual solvent inside the cured film leads to a deterioration in the properties of the molded film, etc. The curable composition to be applied Among these, the solvent content is preferably 5% by mass or less, it is particularly preferable to use a composition that substantially does not contain a solvent, and it is most preferable to use a composition that does not contain a solvent.

The support film is selected by evaluating surface smoothness, wettability with the curable composition, peelability of the cured film, transportability, etc. The support film includes polyester resin, polyolefin resin, vinyl chloride resin, acetylcellulose resin, acrylic resin, vinyl fluoride resin, polycarbonate resin, polyamide resin, polyethersulfone resin, and cycloolefin. Films such as resins can be used. Among these, polyester resins that have excellent surface smoothness and a balance of various other properties are preferable, especially polyethylene terephthalate (PET) films.

The thickness (average thickness) of the support film is not particularly limited, but is, for example, 10 to 400 μm.

Since the ends of the cured film may be wrinkled or warped due to curing shrinkage, they may be removed by cutting them to an appropriate width using a slitter.

The pencil hardness of the optical film (cured film), which is one of the preferred embodiments of the present invention, is, for example, H or higher, preferably 2H or higher, and more preferably 3H or higher. If the pencil hardness is too low, there is a risk that protective functions such as abrasion resistance may decrease when used as a cover sheet. In addition, in this specification and claims, pencil hardness can be measured by a method based on JIS K5600-5-4, and in detail, can be measured by the method described in the Examples described later.

The optical film has excellent bending stability, so fold marks or fold stripes are unlikely to occur. The bending stability of the optical film is, for example, 2 mm or less, preferably 1 mm or less, and more preferably 0.5 mm or less. If the bending stability is too low, there is a risk that deformation such as fold marks may occur if the bending is left in the bent state for a long time. In addition, in the present specification and claims, bending stability can be evaluated by the method disclosed in Patent Document 4 (Japanese Patent Application Publication No. 2019-051718), and in detail, measured by the method described in the Examples described later. can do.

The optical film has excellent bending durability, and the occurrence of folding stripes and fractures is suppressed even when repeatedly bent. The bending durability of the optical film may be, for example, 100,000 times or more, preferably 300,000 times or more, and more preferably 500,000 times or more. If the bending durability is too low, there is a risk of folding stripes or breakage when repeatedly bent. In the present specification and claims, bending durability can be measured by the method described in the Examples described later.

The optical film is excellent in transparency. The total light transmittance of the optical film may be 80% or more, for example, 80 to 100%, preferably 83 to 99%, more preferably 85 to 98%, and most preferably 88 to 95%. When the optical film contains an ultraviolet absorber, the total light transmittance may be 85% or more, preferably 87% or more, more preferably 88% or more, and most preferably 89% or more. In addition, in this specification and claims, the total light transmittance can be measured based on JIS K7361-1, and in detail, can be measured by the method described in the Examples described later.

The spectral transmittance of the optical film at a wavelength of 380 nm may be 50% or more, for example, 50 to 100%, preferably 60 to 95%, more preferably 70 to 90%, most preferably 80 to 85%. % am. When the optical film contains an ultraviolet absorber, the spectral transmittance may be 50% or less, for example, 30% or less, preferably 10% or less, and more preferably 8% or less. Additionally, in the present specification and claims, the spectral transmittance can be measured by the method described in the Examples described later.

The yellowness (YI) of the optical film may be 10 or less, for example, 0.1 to 10, preferably 0.3 to 8, more preferably 0.5 to 5, more preferably 1 to 3.5, most preferably 1.5. It is ~ 2.5. When the optical film contains an ultraviolet absorber, the yellowness is, for example, 10 or less, preferably 8 or less, more preferably 7 or less, and most preferably 6 or less. In addition, in this specification and claims, yellowness can be measured based on JIS K7373, and in detail, can be measured by the method described in the Examples described later.

The haze of the optical film may be 10% or less, for example, 0.1 to 10%, preferably 0.2 to 5%, more preferably 0.3 to 3%, more preferably 0.5 to 2%, most preferably It is 0.7 to 1.5%. When the optical film contains an ultraviolet absorber, the haze is 5% or less, preferably 3% or less, more preferably 1% or less, and most preferably 0.5% or less. In addition, in this specification and claims, haze can be measured based on JIS K7136, and in detail, can be measured by the method described in the Examples described later.

The refractive index of the optical film at 20°C and a wavelength of 589 nm can be selected from a range of 1.6 or less, for example, 1.52 to 1.6, preferably 1.53 to 1.59, more preferably 1.54 to 1.585, and more. Preferably it is 1.55 to 1.58, and most preferably 1.56 to 1.57. In addition, in the present specification and claims, the refractive index can be measured using a multi-wavelength Abbe refractometer, and in detail, can be measured by the method described in the Examples described later.

The optical film has a small phase difference (birefringence) and does not impair the visibility of the image display device. The in-plane retardation (or front retardation) Ro of the optical film is 0 to 10 nm at room temperature at a wavelength of 550 nm and a thickness of 50 μm, and the preferred range is 0 to 8 nm and 0.01 to 6 nm in the following steps. , 0.03 to 5 nm, 0.05 to 4 nm, 0.1 to 3 nm, 0.2 to 2 nm, and 0.3 to 1 nm is most preferable. When the optical film contains an ultraviolet absorber, Ro is, for example, 0 to 5 nm, preferably 0.01 to 3 nm, more preferably 0.03 to 1 nm, and most preferably 0.05 to 0.5 nm. If the in-plane phase difference Ro is too large, rainbow spots or light leakage may occur, which may reduce visibility beyond polarized sunglasses.

The thickness direction retardation Rth of the optical film is 0 to 150 nm at room temperature at a wavelength of 589 nm and a thickness of 50 μm. Preferred ranges are 1 to 100 nm, 5 to 80 nm, and 10 to 70 in the following steps. nm, 12 to 60 nm, 15 to 50 nm, and 20 to 30 nm is most preferable. When the optical film contains an ultraviolet absorber, the Rth is, for example, 0 to 10 nm, preferably 0.01 to 5 nm, more preferably 0.05 to 3 nm, and most preferably 0.1 to 1 nm. If the thickness direction phase difference Rth is too large, rainbow spots or light leakage may occur, which may reduce visibility beyond polarized sunglasses.

The in-plane retardation Ro and the thickness direction retardation Rth of the optical film can each be calculated using the following equations.

(In the formula, nx is the refractive index in the slow axis direction of the film, ny is the refractive index in the fast axis direction of the film, nz is the refractive index in the thickness direction of the film, and d is the thickness of the film).

In addition, in the present specification and claims, the in-plane retardation Ro and the thickness direction retardation Rth can be measured by the method described in the Examples described later.

The thickness (average thickness) of the optical film is not particularly limited, but is, for example, 20 to 300 μm, preferably 30 to 250 μm, more preferably 50 to 200 μm, more preferably 70 to 150 μm, most preferably 70 to 150 μm. Preferably it is 80 to 120 ㎛. The thickness (average thickness) of the optical film may be a thin film of 20 to 200 ㎛, preferably 30 to 150 ㎛, more preferably 50 to 120 ㎛, and such a thin film may include an ultraviolet absorber. And it is especially effective when used as a polarizing plate protective film. If the optical film is too thin, protective functions such as abrasion resistance may be reduced, and if it is too thick, bending resistance may be reduced.

[Cover sheet for display]

The optical film may be a cover sheet (or cover film) for a display, especially a cover sheet for a foldable display, and when the curable composition contains an ultraviolet absorber, it is laminated on the surface of a polarizer polarizer to function as a polarizer protective film. It is preferable to use it as a cover sheet (polarizing plate protective film) for a foldable display. The reasons why a sheet formed from a cured product of a curable composition containing an ultraviolet absorber is suitable for this application are as follows.

Usually, cover sheets for foldable or rollable displays are bonded to a circularly polarizing plate with an adhesive, but the circularly polarizing plate consists of a thin polyvinyl alcohol (PVA) polarizer formed by coating and a thin film of acrylic to withstand bending or winding. It is formed by bonding a protective film with an adhesive. Since the acrylic protective film cannot withstand bending at a thickness of about 40 μm, which is used as a normal polarizing plate protective film, it is designed to be about half the thickness. A UV absorber is added to the polarizer protective film to protect the iodine of the polarizer (polarizing film) from ultraviolet rays. However, as the thickness becomes thinner, the solubility of the ultraviolet absorber in the acrylic resin is low, so it is easy to bleed out, and the material required for UV absorption is reduced. Quantities cannot be added. For this reason, an insufficient amount of ultraviolet absorber is added to the adhesive, but this leads to a decrease in adhesive strength. In addition, by combining the function of a polarizer protective film with a foldable cover sheet, a foldable display that eliminates the protective film, promotes thinning, and is resistant to bending is being considered. The current situation is that there is no display that satisfies all of the above.

On the other hand, in one preferred embodiment of the present invention, since it is formed as a cured product of a curable composition containing an ultraviolet absorber, both thinning and ultraviolet absorbing ability can be achieved, and adhesion to the PVA polarizer can also be improved.

Since the cover sheet for a display, which is one of the preferred embodiments of the present invention, has a function as a polarizing plate protective film, it can be directly bonded to a PVA polarizer. The polarizing plate protective film usually needs to function as a support for the flexible PVA film, but the cover sheet, which is one of the preferred embodiments of the present invention, is a soft film and has rigidity as a support to withstand stress due to heat shrinkage of PVA, There is not. However, in a foldable display, the image display device is OLED, and the circular polarizer is comprised of a laminate in which a coated thin PVA layer is bonded to an acrylic retardation film, and the shrinkage stress of the PVA is alleviated by the rigid acrylic retardation film. do. Therefore, since the cover sheet can be integrated as a circularly polarizing plate by bonding it to the PVA layer with an adhesive with strong adhesive force, it can be adjusted so as not to be affected by the shrinkage stress of PVA.

As an adhesive used for bonding with the PVA layer, an active energy ray curing type adhesive can be used. Examples of this adhesive include photocationic polymerization type adhesives such as adhesives made of an epoxy resin composition containing a photocationic polymerization initiator; Photo-radical polymerization type adhesives, such as adhesives made of (meth)acrylic resin compositions such as (meth)acrylamide, (meth)acrylate, urethane (meth)acrylate, and epoxy (meth)acrylate, are included. These adhesives can be used individually or in combination of two or more types, and may be a combination of a photocationic polymerization type adhesive and a photoradical polymerization type adhesive. Since the display cover sheet, which is one of the preferred embodiments of the present invention, is hydrophobic, the moisture permeability is low and it takes time for moisture to dry. Therefore, as the adhesive, a PVA-based water-based adhesive that requires drying of moisture is not preferable. Therefore, among the above adhesives, hydrophobic adhesives are preferable. Additionally, since the adhesive does not require a drying process or drying equipment, an adhesive that does not contain an organic solvent is preferred.

The cover sheet for a display used as a polarizing plate protective film is coated with the above-described adhesive using an adhesive coating device, bonded to a polarizing film coated with a PVA layer on a retardation film using a nip roll, and then irradiated with ultraviolet rays to the cured film side using an ultraviolet irradiation device. It can be manufactured by irradiating from , curing the adhesive, etc.

In order to improve adhesion, the polarizer and/or display cover sheet may be subjected to surface modification treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet treatment, primer application treatment, or saponification treatment.

The laminated film in which the display cover sheet and the polarizer are bonded together is a member in which the cover sheet and the polarizer are integrated, and can be mounted on a foldable terminal such as a foldable smartphone.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Below, the raw materials and evaluation methods used are as follows.

[Raw material]

BPEF-5EOGA: This is an epoxy acrylate synthesized by the method described in the examples of Japanese Patent Application Publication No. 2017-186513, and in the above formula (1b), n1 + n2 = 7.

BPEF-9EOGA: An epoxy acrylate synthesized by the method described in the examples of Japanese Patent Application Laid-Open No. 2017-186513, and in the above formula (1b), n1 + n2 = 11.

BNEF-13EOGA: An epoxy acrylate synthesized by the method described in the examples of Japanese Patent Application Laid-Open No. 2017-186513, wherein in the formula (1a), Z ^1a and Z ^1b are naphthalene rings, and n1 + n2 = 15.

BPEF-9EOA: diacrylate of an adduct in which 9 moles of ethylene oxide are added on average to 1 mole of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene (BPEF) (Osaka) Gas Chemical Co., Ltd. Manufacturing)

UV-3200B (ester type): manufactured by Nippon Synthetic Chemical Industry Co., Ltd., difunctional urethane acrylate

Epoxy ester 3000A: manufactured by Kyoeisha Chemical Co., Ltd., acrylic acid adduct of diglycidyl ether of bisphenol A

Ultraviolet absorber A: Eversorb109, manufactured by Everlight Chemical, viscous liquid

Ultraviolet absorber B: EversorbBL1A, manufactured by Everlight Chemical, viscous liquid

Photopolymerization initiator A: manufactured by BASF Japan Co., Ltd., brand name “Irgacure 184”

Photopolymerization initiator B: manufactured by BASF Japan Co., Ltd., brand name “Irgacure 819”

Support film: manufactured by Toray Co., Ltd., brand name “PET Lumiror”, film thickness: 100 μm.

[Pencil hardness]

It was measured using a pencil hardness tester (“HEIDON-14” manufactured by Shinto Science Co., Ltd.) in accordance with JIS K5600-5-4 (load: 750 g).

[Bending stability]

It was measured as follows using a bending tester (“DMLHP-CS” manufactured by YUASA SYSTEM Co., Ltd.). That is, as shown in FIG. 2(a), first, a pair of plates 12, 13 of the tester 10 for holding the film 11 are placed so that each film mounting surface 12a, 13a is the same plane. It was fixed so that the film (test piece) 11 was installed on the film mounting surfaces 12a and 13a. Next, the opposing plate ends 12b, 13b between the pair of plates 12, 13 are moved relative to each other by using the plates 12, 13 as the rotation center of each plate 12, 13, so that each plate 12, 13 rotates. The film placement surfaces 12a and 13a were moved to face each other at a distance R regulated by a spacer (not shown) (hereinafter, this moving operation is referred to as “closing operation”). In this closing operation, both plates 12 and 13 were moved so that their respective film placement surfaces 12a and 13a finally faced each other and became parallel, as shown in FIG. 2(b). The distance R between each film mounting surface 12a and 13a was adjusted to be 4 mm.

After the pair of plates 12 and 13 are brought into the state shown in Fig. 2(b) by a closing operation and left at room temperature for 24 hours, the film 11 is removed from the testing machine 10 and bent. The film 11 was placed on a flat surface with one inner side facing up and left for 1 hour, and then the height at which the end of the film 11 floated above the flat surface was measured.

[Bending durability]

After performing a closing operation using the bending tester 10 using the same bending method as the bending stability test, the pair of plates 12 and 13 are moved relative to each other in the opposite direction of the closing operation, again as shown in FIG. 2(a). ), each film placement surface 12a, 13a was moved so as to be on the same plane (hereinafter, this moving operation is referred to as “opening operation”). Additionally, by repeating this series of closing and opening operations 100,000 or 1,000,000 times and visually observing the presence or absence of folding stripes and fractures on the surface of the film 11, it is observed that folding stripes are formed in the film; The number of bending times until fracture occurred and abnormalities in appearance occurred were counted.

[Total light transmittance]

It was measured using a color difference turbidity meter (“COH-400” manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K7361-1.

[Spectral line transmittance]

The spectral transmittance at 380 nm was measured using a spectrophotometer (“UV-3600” manufactured by Shimadzu Corporation).

[Yellowness (YI)]

In accordance with JIS K7373, measurement was performed using a color difference turbidity meter (“COH-400” manufactured by Nippon Denshoku Co., Ltd.).

[Hayes]

In accordance with JIS K7136, measurement was performed using a color difference turbidity meter (“COH-400” manufactured by Nippon Denshoku Co., Ltd.).

[Refractive index]

Using a multi-wavelength Abbe refractometer (“DR-M4 (Circulating constant temperature water tank 60-C3)” manufactured by Atago Co., Ltd.), the measurement temperature was 20°C, bromonaphthalene was used as the contact liquid, and 589 nm (D line) ) of the refractive index (nD) was measured.

[Phase difference]

Ro(550) and Rth(589) of the film were measured at a measurement temperature of 20°C using a retardation measuring device (“RETS-100” manufactured by Otsuka Electronics Co., Ltd.). Retardation is a value converted to a film thickness of 50 μm. Additionally, Ro(550) is the in-plane retardation under the condition of a wavelength of 550 nm, and Rth(589) is the thickness direction retardation under the condition of a wavelength of 589 nm.

[bleed out]

For the examples in which an ultraviolet absorber was added, the presence or absence of bleed-out on the surface of the obtained cured film was visually observed.

(Example 1)

As shown in Table 1, 100 parts by mass of BPEF-9EOGA and 3 parts by mass of photopolymerization initiator A were added and stirred and mixed at 70°C for 1 hour to obtain a curable composition. It was applied on a support film using a bar coater, and then cured by UV irradiation (500 mJ/cm ² ) using an ultraviolet irradiation device (“ECS-151U” manufactured by iGraphics), and peeled from the support film to give a thickness of 100%. A cured film of ㎛ thickness was prepared. The pencil hardness, bending stability, bending durability, total light transmittance, spectral transmittance, yellowness, haze, refractive index, and retardation of the obtained cured film were measured. The measurement results are shown in Table 2.

(Examples 2 to 5)

As shown in Table 1, a cured film was produced in the same manner as in Example 1, except that ultraviolet absorber A and photopolymerization initiator B were further added to the curable composition in the amounts shown in the same table. In addition, the film thickness of the cured film of Example 3 was 90 μm.

Various properties of the obtained cured film were measured in the same manner as in Example 1. The measurement results are shown in Table 2.

(Examples 6 to 9)

As shown in Table 1, a cured film was produced in the same manner as in Example 1, except that ultraviolet absorber B and photopolymerization initiator B were further added to the curable composition in the amounts shown in the same table.

Various properties of the obtained cured film were measured in the same manner as in Example 1. The measurement results are shown in Table 2.

(Examples 10 to 11 and Comparative Examples 1 to 3)

As shown in Table 1, curing was carried out in the same manner as in Example 1, except that BPEF-5EOGA, BNEF-13EOGA, BPEF-9EOA, UV-3200B (ester type) or epoxy ester 3000A was used instead of BPEF-9EOGA. A film was produced. In addition, the film thickness of the cured film was 90 μm in Comparative Example 1, 200 μm in Comparative Example 2, and 120 μm in Comparative Example 3.

Various properties of the obtained cured film were measured in the same manner as in Example 1. The measurement results are shown in Table 2.

As is clear from the results in Table 2, in the examples, surface hardness is high, bending stability and durability are excellent, and optical properties are also excellent. In particular, Examples 1 to 4, 6 to 8, and 10 to 11 showed high pencil hardness. Among them, the results of comparing Example 1 and Examples 10 to 11 showed that as the added mole number of ethylene oxide increases, the pencil hardness decreases. It was an unexpected result that could not be predicted from the results of the examples in Patent Document 5 in which the hardness was reduced. In addition, in the examples in which the ultraviolet absorber is blended, the ratio of 1 to 3 parts by mass is preferable with respect to 100 parts by mass of BPEF-9EOGA. In particular, at 1 part by mass, the ultraviolet ray blocking ability is improved and various properties are excellent.

Industrial applicability

The optical film, which is one of the preferred embodiments of the present invention, can be used as an optical film mounted on a display unit of an image display device that is used by repeated bending. In particular, since it has both excellent surface hardness and bending resistance, excellent surface hardness can be achieved without the need for a hard coat or simply by applying an ultra-thin hard coat, making it suitable as a cover sheet for the display unit. In addition, the optical film has excellent optical properties and low retardation, so it can be particularly preferably used in foldable portable information terminals as a cover sheet with excellent display visibility. Examples of the portable information terminal include mobile PCs such as smartphones, laptop-type personal computers (PCs), and tablet PCs. Among these, foldable smartphones are preferable.

1: Support film unwinding device
2: Support film
3: Curable composition
4: potter head
5: Ultraviolet irradiation device
6: Support film winding device
7: cured film
8: Cured film winding device

Claims (18)

An optical film mounted on a display portion of an image display device used by repeated bending, and formed from a cured product of a curable composition containing epoxy (meth)acrylate represented by the following formula (1).

[During the ceremony,
X represents a linking group selected from the group of formula (2) below,

(During the ceremony,
R ^3a and R ^3b are the same or different from each other, and are hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, C _1-9 alkyl group, C _1-5 alkoxy group, C _4-12 cycloalkyl group, C _{6 -12} represents an aryl group, a C _2-5 alkenyl group, or a C _7-17 aralkyl group, and R ^3a and R ^3b may combine to form a carbon ring or heterocycle,
p represents an integer greater than or equal to 1)
Ring Z ^1a and Ring Z ^1b are the same or different from each other and represent an arene ring,
R ^1a and R ^1b are the same or different from each other and represent a substituent, m1 and m2 are the same or different from each other and represent an integer of 0 or more,
A ^1a and A ^1b are the same or different from each other and represent a linear or branched alkylene group, n1 and n2 are the same or different from each other and represent an integer of 1 or more,
R ^2a and R ^2b are the same or different from each other and represent a hydrogen atom or a methyl group] According to claim 1,
An optical film wherein the epoxy (meth)acrylate is an epoxy (meth)acrylate represented by the following formula (1a).

(During the ceremony,
R ⁴ represents a substituent, k represents an integer of 0 to 8,
Ring Z ^1a and Ring Z ^1b , A ^1a and A ^1b , n1 and n2, R ^1a and R ^1b , m1 and m2, R ^2a and R ^2b are the same as above) The method of claim 1 or 2,
In the formula (1), ring Z ^1a and ring Z ^1b are the same or different from each other and represent a benzene ring or a naphthalene ring, and R ^1a and R ^1b are the same or different from each other and represent C _1-4 An optical film in which an alkyl group or a C _6-10 aryl group is represented, and n1+n2 represents an integer of 2 to 30. The method according to any one of claims 1 to 3,
An optical film wherein the epoxy (meth)acrylate is an epoxy (meth)acrylate represented by the following formula (1b).

(In the formula, n1+n2 represents an integer of 3 to 20) According to any one of claims 2 to 4,
An optical film in which the ratio of the epoxy (meth)acrylate represented by the formula (1a) is 70 to 100 mol% based on the epoxy (meth)acrylate represented by the formula (1). The method according to any one of claims 1 to 5,
An optical film wherein the curable composition further includes an ultraviolet absorber. The method according to any one of claims 1 to 6,
An optical film wherein the cured product is a photocured product. The method according to any one of claims 1 to 7,
An optical film having an in-plane retardation Ro(550) of 50 nm or less and a thickness direction retardation Rth(589) of 100 nm or less. The method according to any one of claims 1 to 8,
An optical film having a total light transmittance of 85% or more and a spectral transmittance of 8% or less at 380 nm. The method according to any one of claims 1 to 9,
Optical film, a cover sheet for displays. The method according to any one of claims 1 to 10,
An optical film that is a polarizer protective film. The method according to any one of claims 1 to 11,
An optical film with an average thickness of 20 to 200 ㎛. A polarizing plate obtained by bonding the optical film according to any one of claims 1 to 12 and a polyvinyl alcohol polarizer together with an adhesive. According to claim 13,
A polarizer in which the optical film contains an ultraviolet absorber and the adhesive does not contain an ultraviolet absorber. An image display device comprising the optical film according to any one of claims 1 to 12. According to claim 15,
An image display device including an organic EL display. The method of claim 15 or 16,
An image display device that is a foldable or rollable portable information terminal. A method of placing the optical film according to any one of claims 1 to 12 on the surface of a display portion of an image display device used by repeated bending, and using the optical film as a cover sheet.

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