TWI572886B - Protection film, film laminate and polarizing plate - Google Patents

Description

Protective film, film laminate and polarizing plate

The present invention relates to a protective film, a film laminate, and a polarizing plate.

In recent years, liquid crystal displays used in TVs or portable devices have become increasingly thinner, and the components used in such displays, particularly polarizing plates, are being developed in the ultimate thinness. The polarizing plate is generally applied to both surfaces of a polarizing film containing a polyvinyl alcohol-based film which is uniaxially stretched by adsorbing iodine, and an optical film such as cellulose triacetate (hereinafter referred to as TAC) is used as a protective film and bonded by an adhesive. And constitute. In order to bond the TAC film to the polarizing film, a hydrophilic adhesive is used.

Such a conventional polarizing plate has a high moisture permeability due to a TAC film as a protective film and a large expansion and contraction due to moisture absorption and desorption, and is particularly long when the polarizing plate is exposed to a high-humidity environment. When exposed to a high temperature and high humidity environment, the optical function as a polarizing plate or a physical failure due to bending or warping of the polarizing plate may be impaired.

In order to improve these problems, the use of an acrylic film or a polyester film having a low moisture permeability is increasing. Moreover, as a method of attaching a protective film to a polarizing film, an energy ray hardening type is also used. The composition uses a method as an adhesive. However, from the viewpoint of handleability and durability at the time of work, it is difficult to form a protective film in the polarizing film, and it is difficult to make the protective film thin (for example, 40 μm or less).

In order to solve such a problem, Patent Document 1 proposes a method of forming a protective film on a polarizing film by coating an unhardened free radiation hardening resin on a substrate film or a substrate film on which a release layer is formed (energy). After the polarizing film is bonded to the coated surface, the cured resin is cured, and the base film is peeled off to form a protective film on the polarizing film.

Further, Patent Document 2 discloses a thin film formation technique in which a functional layer and an adhesive layer are formed on a base film having a release layer formed on both sides thereof, and then a polarizing film is formed, thereby achieving film formation. Further, Patent Document 3 describes a method of forming a protective film for protecting a polarizing film by directly applying an energy ray-curable resin to a polarizing film and curing it, thereby forming a film thickness of 40 μm or less and protecting the polarizing film. membrane.

[Previous Technical Literature] (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-163082

Patent Document 2: Japanese Laid-Open Patent Publication No. 2012-27260

Patent Document 3: Japanese Patent Laid-Open Publication No. 2014-010311

However, as the protective film becomes thinner, it becomes easier to penetrate moisture, and the moisture permeability tends to become higher, and the polarizing plate attached to the protective film becomes easy to absorb moisture and dehumidify. In addition, when the protective film which does not maintain the shape of the protective film itself and has low tensile strength is used, the expansion and contraction of the polarizing film by moisture absorption and desorption cannot be suppressed. As a result, the polarizing film may be cracked, or the polarizing film and the protective film may be peeled off, and the function of the polarizing plate may not be exhibited.

Regarding such a problem, in any of the above-mentioned patent documents, there is no detailed description of the protective film and the adhesive energy ray-cured film and the moisture permeability forming the protective film, and no independent protection with self-standing property is formed. The description of the film cannot be said to solve the above problem.

In view of the above problems, an object of the present invention is to provide a protective film having low moisture permeability and self-standing property in a thin layer state.

The inventors of the present invention have repeatedly reviewed the above-mentioned problems, and as a result, focused on an amine ester (meth) acrylate monomer which has been hardly regarded as a material of a protective film. Thus, it has been found that in the process of producing the protective film by hardening the monomer, the main chain of the amine ester (meth) acrylate monomer is combined into a branched chain alkyl group, and a state of a thin layer can be obtained. The present invention has been completed by a protective film having low moisture permeability and excellent self-standing property. The present invention relates to each of the following protective films, laminates, and polarizing plates.

<1> A protective film which is formed of a protective film having a structure derived from a structure of an amine ester (meth)acrylate which is a monomer, and the above-mentioned repeating sheet The element has a branched chain alkyl group.

<2> The protective film according to <1>, wherein the repeating unit further has a saturated cyclic aliphatic group.

The protective film according to <1>, wherein the above-mentioned repeating unit comprises the following structure A1 or structure B1 containing R ¹ , wherein R ¹ is a branched chain alkyl group; -CO -NH-R ¹ -NH-CO-‧‧‧ (Structure A1) -OR ¹ -O-‧‧‧ (Structure B1).

<4> The protective film according to <3>, wherein the repeating unit contains the structure A1, and further comprises the following structure B2 containing R ² , wherein R ² is a branched chain alkyl branch a chain alkyl group or a saturated cyclic aliphatic group; when the above repeating unit contains the structure B1, the structure further contains the following structure A2 containing R ² , wherein R ² is a branched chain alkyl group or a saturated cyclic aliphatic group. ;-CO-NH-R ² -NH-CO-‧‧‧ (Structure A2) -OR ² -O-‧‧‧ (Structure B2).

The protective film according to <3>, wherein the repeating unit is a structure represented by the following formula (1); In the formula (1), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, m represents an integer of 0 or more, and x represents an integer of 0 to 3.

<6> The protective film according to <4>, wherein the repeating unit has a structure represented by the following formula (2); In the formula (2), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A A group or an ethyl group, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

<7> The protective film according to <3>, wherein the repeating unit is a structure represented by the following formula (3); In the formula (3), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, m represents an integer of 0 or more, and x represents an integer of 0 to 3.

<8> The protective film according to <4>, wherein the repeating unit has a structure represented by the following formula (4); In the formula (4), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

<9> The protective film according to <5>, wherein the above m is 1 or 2.

<10> The protective film according to <6> or <8>, wherein the above n is 1 or 2.

<11><5> to <10> a protective film described in any one of the R ¹ is ^an alkyl group having two or more branched chains.

<12> The protective film according to <5>, wherein the above R ¹ is a trimethylhexamethylene group.

The protective film according to any one of <1> to <12>, wherein the moisture permeability is 100 g/(m ² ‧24 hours) or less, and the tensile strength is 25 MPa or more.

The protective film of any one of <1> to <13> containing the ultraviolet absorber.

The protective film according to any one of <1> to <14> which is a resin containing at least an amine ester (meth) acrylate belonging to the above monomer and a reactive cerium sol having an organic reactive group. A protective film obtained by hardening a composition, and the surface of the protective film is subjected to plasma treatment or corona treatment.

The film laminate according to any one of the above aspects of the present invention, comprising: (1) a film substrate supporting the protective film, (2) having a scratch-resistant hard coat layer, (3) an anti-glare layer for scattering light, and (4) an anti-reflection layer which is provided on the high refractive index layer provided on the protective film and disposed on the high refractive index layer Any one of the antireflection layers formed by the upper low refractive index layer.

<17> A polarizing plate comprising the protective film according to any one of <1> to <15> on at least one side of the polarizing film.

The method for producing a protective film according to any one of <1> to <14>, comprising: containing at least an amine ester (meth) acrylate belonging to the above monomer; a step of hardening the resin composition with a reactive cerium sol having an organic reactive group; and subjecting the surface of the obtained film to a plasma treatment or a corona treatment.

The protective film of the present invention has low moisture permeability even in a thin layer state, and has a branched chain alkyl group in the main chain of the amine ester (meth) acrylate forming the protective film, thereby having excellent self-supporting property. For example, by bonding to a polarizing film, the polarizing film is less likely to absorb moisture even in a high-temperature and high-humidity environment, and the expansion and contraction of the polarizing film can be suppressed.

Hereinafter, the protective film, the film laminate, and the polarizing plate of the present invention will be described, but the present invention is not limited to the following description.

Protective film

The protective film of the present invention is a protective film formed of a repeating unit having a structure derived from an amine ester (meth) acrylate belonging to a monomer, and at least the above-mentioned repeating unit has at least a branch at least in the main chain. Chain alkyl.

The polymer chain formed by the above-mentioned repeating unit is composed of a plurality of overlapping units. The above-mentioned repeating unit contains a bifunctional amine ester (meth) acrylate monomer unit, and a plurality of urethane (meth) acrylate monomer units are bonded to each other by a (meth) acrylate-derived site. The amine ester (meth) acrylate monomer unit means that in the amine ester (meth) acrylate which is a monomer, the (meth) acrylate group double bond is a cleavable structure, since the system has two ends The double bond of the (meth) acrylate group is a cleavable site and is therefore bifunctional.

Moreover, the above repeating unit has an amine ester bond. Amine ester The number of the keys is not particularly limited and is, for example, 1 to 8. The above amine ester bond is a polar group, and the amine ester bonds in each of the repeating units are close to each other by intermolecular force, whereby a higher cohesive force is produced. Further, since the nitrogen atom and the oxygen atom constituting the above-described amine ester bond are less than the number of covalent bonds, the flexibility of the repeating unit is imparted. On the other hand, a branched chain alkyl group has a non-polar and bulky structure. As a result, the protective film formed by the above-mentioned repeating unit has self-standing property and also has low moisture permeability in a state of a thin layer.

The above amine ester (meth) acrylate monomer unit has a branched chain alkyl group in its main chain. The branched chain alkyl group is not particularly limited, but a branched chain alkyl group having a branch number of 2 or more is preferred. The upper limit of the linear chain length of the alkyl group is not particularly limited, but the influence on the low moisture permeability is, for example, C ₈ or less, preferably C ₆ or less. The linear chain length of the above alkyl group is such that it does not contain a branched chain moiety. The lower limit of the linear chain length of the alkyl group is not particularly limited, but is, for example, C ₃ or more, and C ₄ or more (Cn (n is an integer), which represents the carbon number of the linear chain length, and Cn is C ₄ . The branched chain alkyl group is a butyl group).

Examples of the branched chain alkyl group include a trimethylhexamethylene group, a trimethylpentamethylene group, and a trimethylbutylene group. Among these, trimethylhexamethylene is preferred. The protective film containing the branched chain structure in the main chain of the repeating unit suitably exhibits low moisture permeability and self-standing property. The specific structure of these groups includes the structure of each isomer.

The above branched chain alkyl group is preferably bonded to an amine ester bond. Thereby, the effect of the branched chain alkyl group can be more exerted by the intermolecular force caused by the amine ester bond.

The main chain of the repeating unit preferably contains a saturated cyclic aliphatic group (preferably 15 or less members). By introducing a large annular structure, it is possible to suppress an increase in the moisture permeability of the protective film. The number of the above-mentioned members is the number of members having the largest ring structure when the saturated cyclic aliphatic group has a plurality of cyclic structures.

The cyclic structure of the saturated cyclic aliphatic group may be formed only by a carbon atom, or may be formed by a carbon atom or an oxygen atom and/or a nitrogen atom. Further, a linear or/or branched structure having a carbon number of 1 to 10 may be added to the carbon atom of the above cyclic structure.

Examples of the saturated cyclic aliphatic group include a 3,5,5-trimethylcyclohexane ring, a tricyclodecane ring, and an adamantane ring. The saturated cyclic aliphatic group can be contained in the repeating unit via a saturated aliphatic chain, whereby the carbon number of the saturated aliphatic chain can be changed, and the rigidity of the repeating unit can be appropriately adjusted. The saturated aliphatic chain has a linear structure and a branched structure, and an example of the linear structure is: -(CH ₂ ) _y - (y is an integer of 1 to 10), from the flexibility of the repeating unit From the viewpoint of the decrease and the rigidity, it is particularly preferable that -(CH ₂ )- or -(CH ₂ ) ₂ - is preferable. On the other hand, the branched structure may be exemplified by a structure in which hydrogen on at least one carbon atom of the above linear structure is substituted with a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or the like.

The above 3,5,5-trimethylcyclohexane ring is a 3-methylene-3,5,5-trimethyl group when bonded to two amine ester bonds via a methylene chain. The cyclohexane ring is bonded to each amine ester, and when the tricyclodecane ring is bonded to the two amine ester via a methylene chain, it is a dimethylene tricyclodecane ring and each amine ester. Key bond.

The above 3-methylene-3,5,5-trimethylcyclohexane ring and dimethylene tricyclodecane ring are preferred ring structures, and a protective film of the ring structure is contained in the polymer chain. It is suitably low in moisture permeability and self-standing.

Examples of the repeating unit include a form of the following structure A1 or structure B1 containing R ¹ , wherein R ¹ is a branched chain alkyl group; -CO-NH-R ¹ -NH-CO-‧ ‧ (Structure A1)

-OR ¹ -O-‧‧‧ (Structure B1).

The repeating unit can be obtained, for example, by using an amine ester (meth) acrylate obtained by using a diisocyanate or a diol containing R ¹ and a (meth) acrylate, and can be easily produced.

Repeating unit may further contain other structures, structures containing A1, include: further containing form comprises the following structure B2 ² R a, wherein, R ² is a branched chain alkyl group or saturated aliphatic cyclic . Further, the repeating unit containing the structure B1, include: further comprising a morphological structure comprising the following A2 R ² wherein, R ² is a branched chain alkyl group or a saturated cyclic aliphatic group.

-CO-NH-R ² -NH-CO-‧‧‧ (Structure A2)

-OR ² -O-‧‧‧ (Structure B2)

The ratio of each of these structures is, for example, a structure A1: structure B2 = m + 1 : m (m is an integer of 0 or more) or n: n + 1 (n is an integer of 1 or more), and structure B1: structure A2 = m +1: m (m is an integer of 0 or more) or n: n+1 (n is an integer of 1 or more). Wherein, when m is 0, the repeating unit has the structure A1 or the structure B1, and does not have the structure B2 or the structure A2. The upper limit of m and n is not particularly limited, but is considered to be 4, for example, considering the moisture permeability of the protective film. Or 2.

Specific examples of the above-described repeating unit having a branched chain alkyl group are shown below. As shown in the general formula (1), the moiety derived from (meth) acrylate means a (meth) acrylate structure H ₂ C=CH-CO ₂ - (or H ₂ C=C(CH ₃ )- The carbon-carbon double bond of CO ₂ -) is cleaved into a single bond structure.

(In the formula (1), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, Methyl or ethyl, m represents an integer of 0 or more, and x represents an integer of 0 to 3.

In the above formula (1), R ¹ is 3,3,5-trimethylhexamethylene, R ² is a dimethylene tricyclodecane ring, R ³ and R ⁴ are a hydrogen atom, and m is 1 , x is a suitable structure of 1, which is indicated below.

Other specific examples of the repeating unit are shown below.

(In the formula (2), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, Methyl or ethyl, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

In the above formula (2), R ¹ is 3,3,5-trimethylhexamethylene, R ² is a dimethylene tricyclodecane ring, R ³ and R ⁴ are a hydrogen atom, and n is 1 , x is a suitable structure of 1, which is indicated below.

Other specific examples of the repeating unit are shown below.

(In the formula (3), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, Methyl or ethyl, m represents an integer of 0 or more, and x represents an integer of 0 to 3.

In the above formula (3), R ¹ is 2,2,3-trimethylbutylene, R ² is a 3-methylene-3,5,5-trimethylcyclohexane ring, R ³ and R ⁴ is a hydrogen atom, m is 1, and x is a suitable structure of 1, which is shown below.

Other specific examples of the repeating unit are shown below.

(In the formula (4), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom. Methyl or ethyl, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

In the above formula (4), R ¹ is 2,2,3-trimethylbutylene, R ² is a 3-methylene-3,5,5-trimethylcyclohexane ring, R ³ and R ⁴ is a hydrogen atom, n is 1, and x is a suitable structure, which is shown below.

Even when m of the above formula (1) is 0, the moisture permeability of the protective film of the present invention shows a low value, but m in the above formulas (1) and (3), and the formula (2) and In the case of (4), n is an integer of 1 or more, whereby the moisture permeability of the protective film can be further lowered, and the tensile strength can be further improved, which is preferable. When m and n are 1 or 2, it is more preferable and more preferably 1 because the moisture permeability is lowered.

Further, the repeating unit of the present invention also includes the isomers of the structures represented by the above formula (1a), formula (2a), formula (3a) and formula (4a).

Further, from the viewpoint of lowering the moisture permeability of the protective film and improving the self-supporting property, it is desirable that the polymer chain ratio (total ratio of the repeating unit) of the protective film of the present invention is high, relative to the total mass of the protective film. It is preferably 70% by mass or more and 99.5% by mass or less, and more preferably 80% by mass or more and 99.5% by mass or less.

The protective film of the present invention can be thermally decomposed by GC-MS The protective film was analyzed by FT-IR to determine which structure of the polymer chain (repetitive unit) was formed. In particular, thermal decomposition GC-MS is useful because it can detect a monomer unit contained in a protective film as a monomer component.

The protective film may contain various additives such as an ultraviolet absorber, a leveling agent, and an antistatic agent as long as the film forming property, tensile strength, and low moisture permeability of the protective film are not impaired. Thereby, the ultraviolet absorbing property, the peeling property, and the antistatic property of the protective film can be imparted.

A known ultraviolet ray absorbing agent can be used, and examples thereof include benzophenone such as 2-hydroxy-4-octyloxybenzophenone and 2-hydroxy-4-methoxy-5-sulfobenzophenone. a benzotriazole system such as 2-(2'-hydroxy-5-methylphenyl)benzotriazole, a hindered amine such as phenyl salicylate or p-tert-butylphenylsalicylate Department and so on. A leveling agent or an antistatic agent can also be used by a known person.

The protective film of the present invention may be a protective film obtained by curing a resin composition containing at least the above-mentioned amine ester (meth) acrylate which is a monomer and a reactive cerium sol having an organic reactive group. The surface of the membrane is treated by plasma or corona. When the protective film is bonded to a PVA-based polarizing film, it is possible to use a water-based adhesive which is widely applied to a polarizing film.

The reactive cerium sol of the present invention is a dispersion of cerium oxide in a dispersion medium, and a colloidal cerium oxide can be typically used. The hydrogen atom of the sterol group on the surface of the cerium oxide particle is substituted with an organic reactive group such as a vinyl group, a glycidyl group or a (meth)acrylic group, and the substitution is, for example, by using a decane coupling agent having the above reactive group. The cerium oxide reaction is completed.

Colloidal cerium oxide, suitable for particle size 5nm to A ruthenium sol of about 100 nm. Further, specific examples of the decane coupling agent include 3-(trimethoxyindolyl)propyl methacrylate, 3-(methyldimethoxydecyl)propyl methacrylate, and 3-(methacrylic acid) acrylate. Triethoxymercapto)propyl ester, 3-(methyldiethoxymethyl)propyl methacrylate, 3-(trimethoxydecyl)propyl acrylate, 2-(3,4-epoxy) Cyclohexyl)ethyltrimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyl These may be used singly or in combination of two or more kinds, such as diethoxy decane or 3-glycidoxy propyl triethoxy decane.

Among these reactive cerium sols, the reactive cerium sol treated with a (meth)acrylic group-containing decane coupling agent is excellent in affinity with an amine ester (meth) acrylate, and thus is particularly suitably used. The amount of the reactive cerium sol to be added is not particularly limited as long as it is subjected to surface treatment by plasma or corona to be described later, and is suitable for the water-based adhesion to the PVA polarizing film. The ester (meth) acrylate is usually in the range of 1 to 60% by mass, preferably 3 to 40% by mass, more preferably 5 to 20% by mass.

Since the reactive cerium oxide contained in the protective film of the present invention has an organic structure, it has high dispersibility in the resin and is not easily distributed unevenly. Further, the reactive group interacts or reacts with a functional group of the amine ester (meth) acrylate, whereby the ruthenium oxide particles are hardly detached from the surface of the protective film. Further, after the amine ester (meth) acrylate is cured, the surface is subjected to surface treatment by plasma or corona, and a hydrophilic group such as a hydroxyl group or a sterol group can be introduced into the cerium oxide at a low energy. Surface guide A large amount of hydrophilic groups are incorporated.

As described above, a plurality of hydrophilic base portions which are uniformly and strongly bonded are formed in the resin component, whereby the protective film has water-based adhesion to the PVA polarizing film, and is excellent in durability after the water system is followed (difficult to self-practice) Polarized film peeling). These effects are not obtained when a non-reactive group of ruthenium sol is used.

By the effect of the surface treatment described above, it was confirmed that the physical contact angle of the water was lowered, the wettability of the water-based adhesive was improved, and the adhesion between the water-based adhesive and the PVA polarizing film was improved. Further, chemically, by using an X-ray photoelectron spectroscopy apparatus, it is possible to confirm the increase in the composition ratio of the oxygen element on the treated surface by a quantitative value. The oxygen element composition ratio of the protective film subjected to the plasma treatment or the corona treatment is preferably 1.3 times or more as compared with that before the treatment. When the composition ratio is increased by 1.3 times or more, the adhesion force to the water-based adhesive is remarkably improved.

The strength of the plasma or corona treatment is not particularly limited, but it is preferably treated with the water contact angle of the surface of the protective film of 30 degrees or less in terms of water-based adhesion to the PVA polarizing film. Specifically, the strength was due to the processing processing method, reactive silicon oxide type, addition amount of change significantly, but the dose is generally in the range of 200 to 1000 watts ‧ min / m ² of.

Since the protective film of the present invention is formed into a film, for example, the upper limit of the film thickness is 50 μm, and more preferably 30 μm. The lower limit is not particularly limited, but is preferably 5 μm and more preferably 10 μm from the viewpoint of ensuring low moisture permeability.

The protective film of the present invention has a low moisture permeability, and is preferably in a thin layer state of 30 μm (thickness of 30 μm or less) of 100 g/(m ² ‧24 hours) or less, more preferably 80 g/(m ² ‧24 hours )the following. The lower limit of the moisture permeability is not particularly limited, and is, for example, 15 g/(m ² ‧24 hours) or more.

The protective film of the present invention has self-standing properties. The self-supporting property means that the protective film can maintain a single shape, and the criterion is that if the tensile strength of the protective film is 15 MPa or more, the protective film is self-standing. Since the stretching and contraction of the polarizing film by moisture absorption and desorption can be suppressed, the tensile strength is preferably high, and more preferably 25 MPa or more. The upper limit is not particularly limited and is, for example, 100 MPa.

Membrane

Next, the film laminate will be described. The film laminate of the present invention comprises at least one surface of the protective film: (1) a film substrate supporting the protective film, (2) a hard coat layer having scratch resistance, and (3) preventing light scattering. The glare layer and (4) an antireflection layer comprising a high refractive index layer provided on the protective film and a low refractive index layer provided on the high refractive index layer. Of course, the above-mentioned film laminate may have any of the above (1) to (4) on both surfaces of the protective film. That is, the same layer may be provided on both surfaces (for example, (1) on the surface of the protective film, (1) on the reverse side) or a different layer (for example, (1) on the surface of the protective film, The reverse side has (2); either (2) on the surface or (3) on the reverse side. In addition, you can have other items besides (1) to (4) The layers of (1) to (4) are laminated structures. Hereinafter, (1) to (4) will be described. Further, other known layers may be provided without departing from the effects of the present invention.

[film substrate]

The protective film of the present invention can be treated integrally with other film layers. Further, a protective film is formed on the film substrate by a coating method such as a roll coating method or a gravure coating method, and when the film laminate is produced, the film substrate can be directly used as a part of the film laminate.

The film base material functions to support the protective film, and since it is finally peeled off, it is preferable to have a release layer on the side of the build-up protective film. In addition, when the film substrate is provided with a functional layer via a release layer, when the film substrate is bonded and removed on the functional layer side of the protective film, the functional layer does not remain in the film base. On the side of the material, it is transferred to the side of the protective film.

In general, since the protective film and the polarizing film are bonded together by the ultraviolet curable adhesive, the film substrate is preferably one which does not inhibit ultraviolet irradiation and does not have ultraviolet absorbing ability. Further, in various manufacturing steps in which another film is provided on the polarizing plate and processed into a display device, the optical characteristics are also checked, and the basic structure of the polarizing plate is such that the optical characteristics of the polarizing film and the protective film can be made. The effect of the measurement is minimized, and the film substrate preferably has transparency. From this point of view, the film substrate is preferably a polyester film substrate having a release layer.

The polyester film substrate may have a release layer as described above, or may further form another functional layer in addition to the release layer. Features Examples of the layer include a hard coat layer (HC layer), an antiglare layer (AG layer), and an antireflection layer (LR layer). These layers are formed on the release layer of the polyester film, and after laminating the protective film, the polyester substrate is peeled off from the release layer, whereby a film laminate in which the respective functional layers and the protective film are laminated is easily obtained.

[hard coating]

The hard coat layer is hard coatable. In the present invention, the hard coat property (scratch resistance) means a pencil scratch hardness of 2H or more under the conditions of a load of 500 g and a speed of 1 mm/s in accordance with JIS K5600:1999.

Since the resin component constituting the hard coat layer can be efficiently cured by a simple processing operation, it is suitable, as long as it has sufficient strength after hardening, and can impart free radiation to the transparency of the film. The hardening type resin can be used without particular limitation.

As the free-radiation-curable resin, a radical polymerizable functional group such as an acrylonitrile group, a methacryl fluorenyl group, an acryloxy group, or a methacryloxy group may be used alone, or an epoxy group, a vinyl ether group, or an oxa group. A monomer, an oligomer, a prepolymer, a polymer of a cationically polymerizable functional group such as a cyclobutane group, or a composition which is appropriately mixed. Examples of the monomer include methyl acrylate, methyl methacrylate, polymethoxymethyl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, and ethylene glycol. A acrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and the like. Examples of the oligomer and the prepolymer include polyester acrylate, polyurethane acrylate, polyfunctional amine ester acrylate, epoxy acrylate, polyether acrylate, An acrylate compound such as an alkyd acrylate, a melamine acrylate or a polyoxy acrylate, an unsaturated polyester, a tetramethylene glycol diglycidyl ether, a propylene glycol diglycidyl ether, a neopentyl glycol diglycidyl ether, Epoxy compounds such as bisphenol A diglycidyl ether or various alicyclic epoxy groups, 3-ethyl-3-hydroxymethyl oxetane, 1,4-double {[(3-ethyl-) An oxetane compound such as 3-oxetanyl)methoxy]methyl}benzene or bis[1-ethyl(3-oxetanyl)methyl ether. The polymer may, for example, be a polyacrylate, a polyurethane acrylate, a polyester acrylate or the like. These can be used alone or in combination with a plurality of species. Among these free radiation curable resins, in particular, a polyfunctional monomer having three or more functional groups can increase the curing rate and increase the hardness of the cured product. Further, by using a polyfunctional amine ester acrylate, hardness, flexibility, and the like of the cured product can be imparted.

The free radiation curable resin can be hardened by direct irradiation with free radiation, but it is necessary to add a photopolymerization initiator when it is cured by ultraviolet irradiation. The photopolymerization initiator is a radical polymerization initiator such as an acetophenone system, a benzophenone system, an oxathioxanthone system, a benzoin or a benzoin methyl ether, and an aromatic diazonium salt. A cationic polymerization initiator such as an aromatic onium salt, an aromatic onium salt or a metallocene compound is used singly or in combination as appropriate.

The film thickness of the hard coat layer is not particularly limited as long as it exhibits hard coatability, but is substantially 2 μm or more and 10 μm or less.

In order to impart a function other than hard coatability, various additives may be added to the above hard coat layer. For example, it can be appropriately selected depending on the function required: it is added to improve mold release property when peeled off from the polyester film substrate. A fluorine-based or polyoxane-based leveling agent; an electron-conjugated system, a metal oxide-based or an ion-based antistatic agent added to prevent adhesion of dust by peeling off static electricity during peeling. The anti-glare layer and the low refractive index layer described below are also the same in terms of the point at which the additive can be used.

[anti-glare layer]

The anti-glare layer has an anti-glare function for scattering light, and an anti-glare function is realized by external haze and/or internal haze. The anti-glare layer has irregularities on the surface and contains light transmission inside. Microparticles, or both.

The method of forming the unevenness on the surface of the antiglare layer is not particularly limited. However, since the shape of the unevenness is easily controlled, the free radiation curable resin is applied onto the polyester film substrate on which the unevenness is formed, and after coating. The method of hardening is preferred.

The shape of the surface unevenness on the polyester substrate side of the antiglare layer is determined according to the required antiglare property. A more suitable uneven shape can be defined by the thickness parameter Ra, and is preferably Ra: 0.01 μm or more, Sm: 50 μm to 500 μm, and an average tilt angle: 0.1° to 3.0°.

The thickness of the anti-glare layer is not particularly limited, but when it is too thin, the uneven shape formed on the side of the support body also forms irregularities on the side of the support body, which is not preferable from the viewpoint of anti-glare. On the other hand, when it is too thick, since it is bent or cracked due to hardening and shrinkage of the resin, it is not preferable from the viewpoint of handling, and therefore it is preferably in the range of 1 to 12 μm.

On the other hand, in order to generate internal haze, the light-transmitting fine particles added to the free radiation-curable resin may be, for example, propylene. Organic resin fine particles such as an acid resin, a polystyrene resin, a styrene-acrylic acid copolymer, a nylon resin, a polyoxyxylene resin, a melamine resin, a polyether oxime resin, and inorganic fine particles such as cerium oxide. Among them, the difference in refractive index between the light-transmitting fine particles and the resin component is suitably 0.04 or less, and more preferably 0.01 or less. When the refractive index difference with the resin component is large, since internal scattering occurs in the antiglare layer, the contrast is lowered, which is not preferable.

The film thickness of the anti-glare layer is not particularly limited as long as it exhibits anti-glare properties, and is substantially 2 μm or more and 10 μm or less. Further, the antiglare layer may have a hard coat property in addition to the antiglare property, and in this case, the hard coat property can be imparted by adjusting the resin component to be used.

[anti-reflection layer]

The antireflection layer is composed of a low refractive index layer and a high refractive index layer. The low refractive index layer refers to a layer having a lower refractive index than an adjacent high refractive index layer (for example, a hard coat layer, an antiglare layer or a protective film), and in a state of being laminated together with the high refractive index layer, Helps prevent reflection of light from the side of the low refractive index layer. In addition, the high refractive index and the low refractive index do not define an absolute refractive index, but the refractive indices of the two types of layers are defined as being higher or lower in the relative comparison, and when the two have the relationship of the following formula 1 The reflectivity is the lowest.

N2 = (n1) ^1/2 ‧ (1) (n1 is the refractive index of the high refractive index layer, and n2 is the refractive index of the low refractive index layer).

In order to appropriately exhibit the antireflection function, the refractive index of the low refractive index layer is preferably 1.45 or less. The material having such a characteristic is, for example, LiF (refractive index n = 1.4), MgF ₂ (n = 1.4), and 3NaF‧ AlF ₃ (micronized in a propylene resin, an epoxy resin, or the like). Inorganic low-reflection material of inorganic material such as n=1.4), AlF ₃ (n=1.4), Na ₃ AlF ₆ (n=1.33); fluorine-based or polyfluorene-based organic compound, thermoplastic resin, thermosetting resin Organic low-reflection materials such as radiation-curable resins. Among them, from the viewpoint of preventing contamination when the low refractive index layer is a surface, since the antifouling property is excellent, a fluorine-based fluorine-containing material is particularly preferable.

Examples of the fluorine-containing material include a vinylidene fluoride-based copolymer which is dissolved in an organic solvent and which is easy to handle, or a fluoroolefin/hydrocarbon copolymer, a fluorine-containing epoxy resin, a fluorine-containing epoxy acrylate, and a fluorine-containing polyfluorene. Oxygen, fluorine-containing alkoxydecane, fluorine-containing polyoxyalkylene, and the like. These may be used alone or in combination of plural numbers. The fluorinated polyoxyalkylene may be a mixture of at least a hydrolyzable decane compound and/or a hydrolyzate thereof and a curing accelerator, and may be contained as a film forming agent and an antistatic agent as a hydrolyzable decane compound. Functional cationically modified decane compound.

The film thickness of the low refractive index layer is not particularly limited as long as it exhibits an antireflection function in relation to the high refractive index layer, but is substantially 0.05 μm or more and 0.2 μm or less, and the film thickness of the high refractive index layer is substantially The upper layer is preferably 0.05 μm or more and 10 μm or less. The relationship between the low refractive index layer and the high refractive index layer exhibits an antireflection function, and may also have hard coat properties depending on the selection of the raw material. Further, depending on the selection of the raw material, the high refractive index layer may have a hard coat property, and may further have antiglare properties.

Polarizer

Next, a polarizing plate comprising the protective film of the present invention will be described. The polarizing plate of the present invention is provided with the above protective film on at least one side of the polarizing film.

The polarizing film is a polyvinyl alcohol-based resin (PVA resin) having light that penetrates a vibration surface having a certain direction among light incident on the polarizing film and absorbs light having a vibration surface perpendicular to the direction. A film of a nature, typically adsorbing a directional dichroic dye in a PVA resin. The PVA resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin which is a raw material of the PVA resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate in addition to the polyvinyl acetate of the vinyl acetate homopolymer. The polarizing film can be produced by subjecting the film containing the PVA resin to uniaxial stretching, dyeing with a dichroic dye, and dyeing with a boric acid cross-linking treatment. The dichroic dye system uses iodine or a dichroic organic dye. The uniaxial stretching may be carried out before the dyeing with the dichroic dye, or simultaneously with the dyeing of the dichroic dye, or after the dyeing with the dichroic dye, for example, in the cross-linking treatment of boric acid. In this manner, a polarizing film comprising a PVA resin adsorbing a directional dichroic dye is one of constituent materials of a polarizing plate.

In the bonding of the polarizing film and the protective film, an ultraviolet curable adhesive is preferably used. The ultraviolet curable adhesive can be used in the conventional production of a polarizing plate under the restriction of being supplied in a liquid state in a coatable state, but it is a viewpoint of weather resistance, polymerizability, etc. It is preferred that one of the ultraviolet curable components is a compound containing a cationic polymerizable property such as an epoxy compound.

In the ultraviolet curing type of adhesive, in addition to epoxidation In addition to the cationically polymerizable compound of the representative example, a polymerization initiator may be formulated, and in particular, a cationic species or a Lewis acid may be prepared by irradiation of ultraviolet rays to cause photocationic polymerization of the cationically polymerizable compound to start polymerization. Starting agent. Further, a thermal cationic polymerization initiator which starts polymerization by heating, and various other additives such as a photosensitizer can also be formulated.

On the other hand, when a reactive cerium sol is used as a raw material of a protective film, a water-based adhesive (hydrophilic adhesive) can be used, and for example, a polyvinyl alcohol-based adhesive can be used.

The polarizing plate of the present invention includes the protective film on at least one surface thereof, and includes a protective film (including a laminated body including a protective film) on both surfaces of the polarizing plate. Since the protective film has a low moisture permeability even in a thin layer, the polarizing film is less likely to absorb moisture even in a high-temperature and high-humidity environment, so that expansion and contraction of the polarizing film can be suppressed.

"Manufacturing method of protective film and film laminate" [Protective film forming step]

The method for producing the protective film of the present invention is not particularly limited as long as the protective film can be produced, and examples thereof include a method of forming a protective film by the following (A1) and (A2).

(A1) An energy ray-curable composition containing an amine ester (meth) acrylate is coated on a film substrate or coated on a release layer of a film substrate.

(A2) After coating, the energy ray-curable composition is cured to form a protective film.

Energy ray hardening type composition, as necessary Amine (meth) acrylate of the component. The above-mentioned amine ester (meth) acrylate which is a monomer is a raw material of a protective film which is formed by polymerization to form a repeating unit described in the above section of "Protective Film". For this reason, although the monomer is different from the repeating unit in that the portion derived from the acrylate at both ends is an acrylate group, (1) the monomer has a branched chain in the main chain. The point of the alkyl group, (2) the point where the main chain of the preferred form monomer has a saturated cyclic aliphatic group, and the like, the structures other than the two ends are the same. Since specific examples of the branched chain alkyl group and the saturated cyclic aliphatic group are as described in the section of the repeating unit, the description thereof is omitted here.

As an example of the above-mentioned amine ester (meth) acrylate, a structure of the following structure A1 or structure B1 containing R ¹ in which R ¹ is a branched chain alkyl group; -CO-NH-R ¹ -NH can be exemplified. -CO-‧‧‧(Structure A1)

-OR ¹ -O-‧‧‧ (Structure B1).

The amine ester (meth) acrylate having the structure A1 can be produced, for example, by reacting a diisocyanate containing R ¹ with a (meth) acrylate in a ratio of 1:2, and having an amine ester of the structure B1 (methyl group) The acrylate can be easily produced, for example, by reacting a diol containing R ¹ with an isocyanate having a (meth)acryl group in a 1:2 ratio.

Further, the amine ester (meth) acrylate may further contain another structure, and when the structure A1 is contained, a form further containing a structure B2 containing R ² in which R ² is a branched chain alkyl group or Saturated cyclic aliphatic groups. And and the repeating unit structure containing B1, include: further comprising a morphological structure comprising the following A2 R ² wherein, R ² is a branched chain alkyl group or a saturated cyclic aliphatic group.

-CO-NH-R ² -NH-CO-‧‧‧ (Structure A2)

-OR ² -O-‧‧‧ (Structure B2)

The ratio of each of these structures is, for example, structure A1: structure B2 = m + 1 : m (m is an integer of 0 or more) or n: n + 1 (n is an integer of 1 or more); structure B1: structure A2 = m+1: m or n: n+1 (n is an integer of 1 or more). Wherein, when m is 0, an amine ester (meth) acrylate having a structure A1 or a structure B1, having no structure B2 or a structure A2 can be obtained. The upper limit of m and n is not particularly limited, but is, for example, 4, more preferably 2, in consideration of the moisture permeability of the protective film.

In the case of the raw material of the amine ester (meth) acrylate, examples of the diisocyanate containing R ¹ include 2,2,3-trimethylhexamethylene diisocyanate, and examples of the diol containing R ¹ include : 2,2,4-trimethyl-1,3-pentanediol, 2,2,3-trimethyl-1,4-butanediol, 2-methyl-1,5-pentane Glycol. Further, examples of the diisocyanate containing R ² include isophorone diisocyanate, and examples of the diol containing R ² include tricyclodecane dimethanol. The (meth) acrylate may, for example, be 2-hydroxyethyl acrylate, and the isocyanate may be 2-acetyl methoxyethyl isocyanate.

Amine ester repeating units having the structure illustrated in Synthesis A1 and corresponding to the general formula (1) of the structure B2 (meth) acrylate way, the system can make a diisocyanate containing R ¹ and R glycols containing ² to m A molar ratio of +1:m gives an intermediate having a -N=C=O group at both ends. Thereafter, an amine ester (meth) acrylate represented by the formula (5) can be obtained by reacting 1 mol of the above intermediate with 2 mol of (meth) acrylate.

(In the formula (5), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, Methyl or ethyl, m represents an integer of 0 or more, and x represents an integer of 0 to 3.

Secondly, illustrates the synthesis of the corresponding structural formula (2) A1 and B2 of the structural repeat units of an amine ester of (meth) acrylate technique, may be based diol diisocyanate containing R ¹ and R ² containing a An intermediate having a hydroxyl group at both terminals is obtained by a molar ratio of n:n+1. Thereafter, 1 mol of the above intermediate is reacted with 2 mol of isocyanate having a (meth)acryl group, whereby an amine ester (meth) acrylate represented by the formula (6) can be obtained.

When a method of synthesizing an amine ester (meth) acrylate corresponding to a repeating unit of the formula (3) having a structure B1 and a structure A2 is exemplified, a diol containing R ¹ and a diisocyanate diol containing R ² may be used. The molar ratio of m+1:m is used, whereby an intermediate having a hydroxyl group at both terminals can be obtained. Thereafter, 1 mol of the above intermediate is reacted with an isocyanate having a (meth)acrylic acid 2 mol, whereby an amine ester (meth) acrylate represented by the formula (7) can be obtained.

(In the formula (7), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, Methyl or ethyl, m represents an integer of 0 or more, and x represents an integer of 0 to 3.

When a method of synthesizing an amine ester (meth) acrylate corresponding to a repeating unit of the formula (4) having a structure B1 and a structure A2 is exemplified, a diol containing R ¹ and a diisocyanate diol containing R ² may be used. An intermediate having a -N=C=O group at both ends is obtained by a molar ratio of n:n+1. Thereafter, 1 mol of the above intermediate was reacted with 2 mol of (meth) acrylate to obtain an amine ester (meth) acrylate represented by the formula (8).

(In the formula (8), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, Methyl or ethyl, n represents an integer of 1 or more, and x represents an integer of 0 to 3.

Further, the monomer of the present invention also includes an isomer of the structure represented by the above formula (5), formula (6), formula (7) and formula (8).

The preparation of the energy ray-curable composition is carried out by adding a photopolymerization initiator which starts polymerization of the monomer to the monomer which produces the repeating unit.

The photopolymerization initiator may be a radical polymerization initiator such as an acetophenone system, a benzophenone system, an oxazetomone, a benzoin or a benzoin methyl ether, or an aromatic diazonium salt. A cationic polymerization initiator such as an aromatic onium salt, an aromatic onium salt or a metallocene compound is used singly or in combination as appropriate.

In the energy ray hardening type composition, the above ultraviolet absorbing agent, leveling agent and anti-antibiotic described in the section "Protective film" may also be added. Various additives such as electrostatic agents.

In the energy ray-curable composition, the ratio of the monomer, the photopolymerization initiator, and any of the various additives varies depending on the type of each material, and it is difficult to define a single definition. However, as an example, it may be set as follows: The monomer is 50% by mass or more and 99% by mass or less, and the photopolymerization initiator is 0.5% by mass or more and 10% by mass or less, and the various additives are 0.01% by mass or more and 50% by mass or less. Further, an organic solvent such as toluene may be added to the energy ray-curable composition.

When the continuous energy-producing composition is applied to a film substrate or a release layer of a film substrate in consideration of continuous productivity, coating by a roll coating method, a gravure coating method, or the like is applied. The law is better. By the coating method, an energy ray-curable composition can be applied so as to form a thin layer, for example, a protective film of 50 μm or less, preferably 30 μm or less.

The hardening in the step (A2) can be carried out by irradiating ultraviolet rays with an ultraviolet irradiation device. The ultraviolet light source to be used is not particularly limited, and a light-emitting distribution having a wavelength of 400 nm or less can be used. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a micro-excited mercury lamp, a metal halogen can be used. Lights, etc. When an epoxy compound is used as an adhesive for an active energy ray-curable component, an ultraviolet light source is used in consideration of a high-pressure mercury lamp or a metal halide lamp having a light having a light of 400 nm or less in consideration of an absorption wavelength expressed by a general polymerization initiator. Preferably.

Hardening energy ray hardening composition by which it can be applied to the film A protective film is formed on the release layer of the substrate or the film substrate, and a film laminate having a protective film laminated on the film substrate is obtained. Further, a protective film of a single monomer can be obtained by peeling off the protective film from the film laminate.

[Function layer forming step]

The change of the manufacturing method of the film laminate includes a production method including the functional layer formation step (B) before the protective film formation steps (A1) and (A2). The functional layer forming step (B) is an energy ray-curable composition in which a raw material of a functional layer is coated on a film substrate or a release layer of a film substrate, and is cured to form a functional layer on the film substrate.

The functional layer is not particularly limited, and examples thereof include the above-mentioned hard coat layer, antiglare layer, and antireflection layer. The energy ray-curable composition of the raw material of the functional layer includes the above-described resin and the like in the description of the hard coat layer, the antiglare layer, and the antireflection layer. Further, an organic solvent such as methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone (MIBK), isopropyl alcohol (IPA) or toluene may be added.

When the energy ray-curable composition of the raw material of the functional layer is applied to the film substrate or the release layer of the film substrate in consideration of continuous productivity, it is coated by a roll coating method, a gravure coating method, or the like. Cloth is better. The energy ray-curable composition to be used may be subjected to any method of crosslinking or curing by ultraviolet irradiation or the like after performing arbitrary heating.

When the functional layer forming step is to form a functional layer on the film substrate, in the protective film forming step (A1), an energy ray-curable composition containing an amine ester (meth) acrylate is coated on the film substrate. Functional layer side. When the functional layer is a plurality of layers, it is usually applied to the side of the functional layer formed last.

When a film substrate having irregularities is formed, irregularities are formed on the functional layer of the film substrate, and the antiglare layer having antiglare property is exhibited. The shape of the unevenness is determined depending on the required anti-glare property, and a more suitable uneven shape can be defined by the thickness parameter Ra, which is Ra: 0.01 μm or more, Sm: 50 μm to 500 μm, and an average tilt angle: 0.1°. 3.0° is better.

When a functional layer is formed, a plurality of layers can also be formed. For example, when a plurality of hard coat layers are formed, a first hard coat layer is formed on the film substrate or on the release layer of the film substrate, and a second hard coat layer is formed on the first hard coat layer. Thereafter, in step (A1), an energy ray-curable composition containing an amine ester (meth) acrylate is applied to the second hard coat layer side. An anti-glare layer may be formed instead of the second hard coat layer described above.

Further, when the antireflection layer is formed, a low refractive index layer is formed on the film substrate or on the release layer of the film substrate, and a high refractive index layer is formed on the low refractive index layer. Further, in the step (A1), an energy ray-curable composition containing an amine ester (meth) acrylate is applied to the high refractive index layer side. Thereby, a film laminate in which a film substrate, a functional layer, and a protective film are laminated in this order can be obtained.

"Manufacturing method of polarizing plate"

The polarizing plate of the present invention is provided with the protective film of the present invention on at least one side of the polarizing film. In the method for producing a polarizing plate of the present invention, the focus is on bonding the protective film to the polarizing film, and the bonding method is as long as a well-known method is used. Yes, without particular limitation.

As the protective film, a protective film may be used alone, but in terms of ease of handling, it is preferred to use the protective film together with the film laminate, that is, to use the protective film together with the film substrate.

For example, after the protective film forming step, after the functional layer forming step and the protective film forming step, or after the laminated body having the protective film is obtained, the polarizing film may be attached to the protective film side of the film laminate. The polarizing plate of the present invention is obtained.

More specifically, the steps of the method of manufacturing the polarizing plate will be described. The following steps (C1) to (C4) are carried out using a method of using an ultraviolet curable adhesive, after the protective film forming step, or after the functional layer forming step and the protective film forming step.

(C1) a coating step of applying an ultraviolet curable adhesive to the protective film side (or polarizing film) of the film laminate; (C2) a bonding step of laminating the pressure-sensitive polarizing film (or the protective film side of the film laminate) on the ultraviolet-curable adhesive layer coated in the coating step; (C3) a hardening step of curing the ultraviolet curable adhesive by irradiating ultraviolet rays with an ultraviolet irradiation device by a film laminate having a protective film adhered to the polarizing film via an ultraviolet curing adhesive; (C4) A peeling step of removing the support substrate by the laminated film as needed.

In the coating step (C1), an ultraviolet curable adhesive is applied to the protective film side of the film laminate of the bonding surface on which the polarizing film is formed (or the polarizing film on the protective film side of the substitute film laminate is coated with ultraviolet rays). Hardened type Agent).

The coating machine used here can be suitably used, and for example, a coating machine using a gravure roll or the like can be mentioned.

In the bonding step (C2), after the coating step (C1), the pressure-sensitive polarizing film is laminated on the adhesive-coated surface of the film laminate, and the bonding is performed at the same time (in the coating step (C1)) When the ultraviolet curable adhesive is applied to the polarizing film, the ultraviolet curable adhesive is laminated on the protective film side of the laminated film laminate and pressed while being bonded. In the pressurization step, a known means can be used. However, from the viewpoint of continuous transfer and simultaneous pressurization, it is preferable to use a pair of nip rolls, and the pressure at the time of pressurization is It is preferable that the linear pressure at the time of being sandwiched by a pair of nip rolls is about 150 to 500 N/cm.

In the hardening step (C3), after laminating the film laminate on the polarizing film, ultraviolet rays are irradiated by the ultraviolet irradiation device to cure the ultraviolet curable adhesive. Ultraviolet rays are irradiated through a film laminate. The ultraviolet light source to be used is not particularly limited, but has a light-emitting distribution at a wavelength of 400 nm or less, and for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a micro-excited mercury lamp, a metal halide lamp, or the like can be used. . When an epoxy compound is used as an adhesive for an energy ray-curable component, a high-pressure mercury lamp or a metal halide lamp having light of 400 nm or less is used as an ultraviolet light source in consideration of an absorption wavelength expressed by a general polymerization initiator. good.

The peeling step (C4) is a step which is appropriately carried out as needed, and by peeling off the film substrate laminated on the protective film by this step, Removal (When the film substrate is a plurality of layers, the film substrate of the system portion is peeled off) to obtain a polarizing plate. When the polarizing plate is further processed, when the surface of the protective film is to be protected in the post-processing step, etc., the film substrate may be peeled off after the processing is completed.

On the other hand, when a reactive cerium sol is used as a raw material of a protective film, it is preferable to use a water-based adhesive after the protective film and the polarizing film. Specific examples of the steps of the method for producing a polarizing plate are shown below.

(D1) a surface treatment step of performing a plasma surface treatment or a corona surface treatment on the protective film of the film laminate, (D2) a coating step of applying a water-based adhesive to the protective film side (or polarizing film) of the film laminate by plasma surface treatment or corona surface treatment, (D3) a laminating step of laminating a pressure-based polarizing film (or a protective film side of the film laminate) on the water-based adhesive surface coated in the coating step, (D4) a drying step of drying the laminated film formed by the laminated film laminate and the polarizing film, (D5) A peeling step of removing the support substrate by peeling off the laminated film as required.

In the treatment apparatus used in the surface treatment step (D1), a known apparatus can be suitably used, and after the plasma or corona surface treatment, the water contact angle of the protective film can be made to have a treatment strength of 30 or less. Treated plasma or corona treatment device. The coating machine in the coating step (D2) is the same as the coating step (C1). The heating temperature and the drying temperature in the drying step (D4) may be appropriately set as long as the thickness of the water-based adhesive is used.

[Examples]

Hereinafter, the present invention will be described based on examples and comparative examples. However, the present invention is not limited to the contents of the embodiments. When the obtained film laminate is peeled off from the protective film of the polyester film substrate (when the functional layer is formed in the film substrate, the protective film and the functional layer are used as the measurement target), the moisture permeability and the tensile strength of the protective film are as follows. Determination of the method of measurement.

[film thickness]

The film thickness of the protective film (or protective film + functional layer) was measured using a digital linear meter D-10HS and a digital linear gauge C-7HS (manufactured by Ozaki Seisakusho Co., Ltd.).

[transmotive humidity]

According to JIS Z0208 method moisture permeability test (cup method (Cup Method)), for the protective film was measured at a temperature of 40 ℃, ambient air humidity of 90% RH in the area of the test piece per 1m ² of the water vapor over 24 hours Grams.

[self-reliance]

For the sample film which was cut into a size of 15 mm × 160 mm, the long side was used as the stretching direction, and "Tensilon RTF-24" (manufactured by YAMATO SCIENTIFIC) was used to grasp the gripper between 100 mm. The holder grasped both ends of the sample film, and measured the load-bearing weight range of 40 N at normal temperature (25 ° C), and measured the maximum slope of the stress-deformation curve at a speed of 20 mm/min, and determined the tensile strength.

In the evaluation of the self-supporting property, when the tensile strength of the sample film is 15 MPa or more and less than 25 MPa, it is judged as ○, and the tensile strength is 25 MPa. When it is the above, it is judged that it is ◎, and when it is ○ or ◎, it is judged that it is self-standing. On the other hand, when the formed film collapsed at the stage of peeling off from the PET film, it was judged that X could not be measured.

[With PVA followed by adhesion to polarizing film]

The surface treatment surface of the protective film and the PVA-based polarizing film were bonded together by a wet stratification using a PVA aqueous solution (solid content: 3%), and then dried at 80 ° C for 5 minutes to obtain a polarizing plate. The protective film was peeled off from the polarizing plate by hand and evaluated. When the peeling film could not be peeled off, it was judged as ○, which was originally not followed, and was determined to be × when it was in the separated state.

[Manufacturing Example 1] Synthesis of Compound 1:

210.27 g (1 mol) of trimethylhexamethylene diisocyanate, 232.24 g (2 mol) of 2-hydroxyethyl acrylate were placed in a flask, and the reaction temperature was set to 70 ° C, and then added as a catalyst. Dibutyltin laurate 0.35 g. The reaction is carried out until the remaining isocyanate group becomes 0.1% or less, and an amine ester acrylate (compound 1) which is a monomer which produces a repeating unit is obtained. The structure of Compound 1 is shown below.

[Manufacturing Example 2] Synthesis of Compound 2:

222.29 g (1 mol) of isophorone diisocyanate was placed in the flask, and 264.41 g (2 mol) of trimethylbutylene glycol was added at a reaction temperature of 70 ° C, when the residual isocyanate group became 2.8%. 282.24 g (2 moles) of 2-propenyloxyethyl isocyanate was added, and the reaction was carried out until the residual isocyanate group became 0.1%, and the amine ester acrylate (compound 2) which is a monomer which produces a repeating unit was obtained. (The repeating unit of Compound 2 is as shown in the formula (2a)).

[Manufacturing Example 3] Synthesis of Compound 3:

Into the flask, 222.29 g (1 mol) of isophorone diisocyanate and 232.24 g (2 mol) of 2-hydroxyethyl acrylate were placed, and after the reaction temperature was set to 70 ° C, dibutyltin lauric acid as a catalyst was added. The ester was 0.35 g. The reaction is carried out until the residual isocyanate group becomes 0.1% or less, and the amine ester acrylate (compound 3) which is a monomer which produces a repeating unit is obtained. The structure of Compound 3 is as follows.

[Manufacturing Example 4] Synthesis of Compound 4:

Into the flask, 196.29 g (1 mol) of tricyclodecane dimethanol and 228.29 g (2 mol) of ε-caprolactone were placed, and the temperature was raised to 120 ° C, and 50 ppm of monobutyltin oxide as a catalyst was added. Thereafter, the reaction was carried out under a nitrogen gas stream until the remaining ε-caprolactone was analyzed by gas chromatography to be 1% or less to obtain a diol (1).

In a separate flask, 444.58 g (2 mol) of isophorone diisocyanate was placed, and diol (1) 425.57 g (1 mol) was added at a reaction temperature of 70 ° C, when the residual isocyanate group became 5.7%. Further, 232.24 g (2 mol) of 2-hydroxyethyl acrylate and 0.35 g of dibutyltin laurate were added, and the reaction was carried out until the residual isocyanate group became 0.1% to obtain an amine ester acrylate (compound 4).

[Manufacturing Example 5] Synthesis of Compound 5 (Reactive Oxime Sol):

In the flask, MEK-ST (manufactured by Nissan Chemical Industries Co., Ltd., MEK dispersed colloidal cerium oxide, solid content 30%) 600 g and 3-(trimethoxydecyl)propyl methacrylate were placed in a flask. 24.8 g (0.1 mol) was sufficiently stirred and reacted at 30 ° C for 24 hours, and then the dispersion medium was volatilized so that the solid content of the reactant was 40%, and a reactive cerium sol (compound 5) was obtained.

[Example 1: Polyester film substrate / protective film]

The following protective film forming energy was applied to the peeling layer side of non-polyoxynoxy stripped PET SG-1 (thickness: 38 μm) manufactured by PANAC Co., Ltd. using an applicator. Ray hardening composition (P1). The energy ray-curable composition (P1) contained toluene and had a solid content ratio (NV) of 60%.

The coating thickness of the energy ray-curable composition (P1) is adjusted so that the film thickness after drying is 20 μm to 30 μm. The temperature in the drying furnace was set in a dust-free oven at 100 ° C, and the coating film was dried. Thereafter, ultraviolet curing was carried out under the conditions of a peak illuminance of 326 mW/cm ² and a cumulative light amount of 192 mJ/cm ² in a nitrogen atmosphere to obtain PET. A film laminate having a protective film formed on one side of the film. The evaluation results of the film laminate are shown in Table 8.

[Example 2: Polyester film substrate / protective film]

In the same manner as in Example 1, except that the monomer (95 parts by mass of the compound 1) used in Example 1 was changed to 95 parts by mass of the compound 2, a protective film was formed on one side of the PET film. Membrane layer. The evaluation results of the above film laminates are shown in Table 8.

[Comparative Example 1: Polyester film substrate / protective film]

In addition to the monomer used in Example 1 (95 parts by mass of Compound 1) The film laminate having a protective film formed on one side of the PET film was obtained in the same manner as in Example 1 except that the compound 3 was changed to 95 parts by mass. The evaluation results of this film laminate are shown in Table 8.

[Example 3: Polyester film substrate / HC layer / protective film]

By the reverse coating method, the following energy-ray hardening type composition (HC1) for forming an HC layer was applied to the side of the release layer of non-polyoxynoxy stripped PET SG-1 (thickness: 38 μm) manufactured by PANAC Co., Ltd. The formed coating film was dried at 100 ° C for 1 minute, and irradiated with ultraviolet light (irradiation distance 10 cm, irradiation time 30 seconds) using a 120 W/cm concentrating high-pressure mercury lamp of 1 lamp in a nitrogen gas atmosphere, and hardening coating. The film was formed to form a hard coat layer (HC layer) having a thickness of 2.5 μm and a refractive index of 1.52.

Then, the energy ray-curable composition for forming a protective film used in Example 1 was applied and dried on the HC layer side under the same conditions as in Example 1 to obtain a protective film formed on the HC layer side. Membrane layer. The evaluation results of this film laminate are shown in Table 8.

[Example 4: Polyester film substrate / AG layer (containing filler) / protective film]

By the bar coating method, the coating for the release layer was applied to one surface of a PET film (product name: EMBLET S-50, manufactured by Unitika Co., Ltd.) which is a support for the release film, so that the dry film thickness was 2 μm. After the liquid was applied, the coated film was dried at 140 ° C for 1 minute to be hardened. In this manner, a support having a release layer having a thickness of 2 μm on the surface of the PET film was obtained. Next, the following energy-ray hardening type composition (AG1) for forming an AG layer is applied onto the release layer.

The coating thickness was adjusted so that the dry film thickness became 6 μm by a bar coating method. After drying the coated film of AG1 at 100 ° C for 1 minute, it was irradiated with ultraviolet light (lamp: high pressure mercury lamp, lamp output: 120 W/cm, cumulative light amount: 120 mJ/cm), and the coating film was hardened. Then, the energy ray-curable composition for forming a protective film used in Example 2 was applied and dried under the same conditions as in Example 2 on the side of the AG layer to obtain a protective film formed on the side of the AG layer. Membrane layer. The evaluation results of this film laminate are shown in Table 8.

[Example 5: Polyester film substrate / HC layer (without filler AG) / protective film]

By the bar coating method, the coating for the release layer was applied to one side of a PET film (product name: EMBLET S-50, manufactured by Unitika Co., Ltd.) as a release film support body so that the dry film thickness was 2 μm. After the liquid was applied, the coated film was dried at 140 ° C for 1 minute, and then hardened. In this manner, a support having a release layer having a surface unevenness of 2 μm on the PET film was obtained. Then, in the same manner as in the coating of AG1 of Example 4, the following energy ray-curable composition (HC2) for forming an HC layer was applied onto the release layer.

Then, the energy ray-curable composition used in Example 2 was applied and dried on the HC layer side under the same conditions as in Example 2 to obtain a film laminate having a protective film formed on the HC layer side. The evaluation results of this film laminate are shown in Table 8.

[Example 6: polyester film substrate / low refractive index layer / high refractive index layer and AG layer / protective film]

By the bar coating method, the coating for the release layer was applied to one side of a PET film (product name: EMBLET S-50, manufactured by Unitika Co., Ltd.) as a support for the release film, so that the thickness of the dried film was 2 μm. After the liquid was applied, the coated film was dried at 140 ° C for 1 minute, and then hardened. In this manner, a support having a release layer having a surface unevenness of 2 μm on the PET film was obtained.

The following low refractive index coating material (LR1) was applied onto the release layer by a reverse coating method to dry the coating film at 100 ° C for 1 minute to form a bump having a thickness of 0.1 μm and a refractive index of 1.38. Low refractive index layer. Thereafter, for curing of the low refractive index layer, it was allowed to stand at 60 ° C for 120 hours.

Next, the AG1 used in Example 4 was applied onto the above-mentioned low refractive index layer by a bar coating method so that the thickness of the dried film became 6 μm, and dried at 100 ° C for 1 minute, and then irradiated with ultraviolet rays (light: High-pressure mercury lamp, lamp output power: 120W/cm, cumulative light amount: 120mJ/cm), hardens the coating film to form an AG layer.

Then, the energy ray-curable composition for forming a protective film used in Example 2 was applied and dried on the AG layer side under the same conditions as in Example 2 to obtain a film having a protective film formed on the side of the AG layer. Laminated body. The evaluation results of this film laminate are shown in Table 8.

[Example 7: polyester film substrate / low refractive index layer / high refractive index layer and HC layer / protective film]

The low refractive index coating material (LR1) described in Example 6 was applied to the peeling layer side of non-polyoxynoxy stripping PETSG-1 (thickness: 38 μm) manufactured by PANAC Co., Ltd. using an applicator, and the coated film was dried at 100 ° C. After 1 minute, it was hardened to form a low refractive index layer having a thickness of 0.1 μm and a refractive index of 1.38. Thereafter, for curing of the low refractive index layer, it was allowed to stand at 60 ° C for 120 hours.

Next, the following energy-ray hardening type composition (HC3) for forming a HC layer is applied onto the low refractive index layer by a reverse coating method. After drying at 100 ° C for 1 minute, ultraviolet irradiation (irradiation distance 10 cm, irradiation time 30 seconds) was carried out in a nitrogen gas atmosphere with a 120 W/cm concentrating high-pressure mercury lamp, and the coating film was hardened to a thickness of 2.5 μm. , HC layer with a refractive index of 1.64.

Then, the energy ray-curable composition for a protective film used in Example 2 was applied and dried on the HC layer side under the same conditions as in Example 2 to obtain a film laminate having a protective film formed on the HC layer side. . The evaluation results of this film laminate are shown in Table 8.

[Example 8: Polyester film substrate / protective film]

The resin composition (P1) used in Example 1 was changed to the resin composition (P2) for forming a protective film in Table 7 below, and the same operation as in Example 1 was carried out, and after UV curing, it was 500. Corona treatment was carried out under conditions of ‧ min/m ² to obtain a film laminate having a protective film formed on one side of the PET film. The evaluation results of the above film laminate are shown in Table 8.

As shown in Table 8, Comparative Example 1 is a protective film obtained by using a branched chain alkyl group "un" in the main chain of an amine ester (meth) acrylate, and has a film thickness of 25 μm and a moisture permeability value of up to 117 g. / (m ² ‧24h), tensile strength is 15MPa. Next, Example 1 is a protective film obtained by using a branched chain alkyl group in the main chain of an amine ester (meth) acrylate, and has a film thickness of 25 μm and a moisture permeability of 45 g/(m ² ‧24 h). The tensile strength is 41 MPa. Comparing these two results, it is understood that Example 1 has a low moisture permeability and a large tensile strength.

Next, in Example 2, it was confirmed that when a branched chain alkyl group and a saturated cyclic aliphatic group were used in the main chain of the amine ester (meth) acrylate, the moisture permeability was higher than that of Example 1. To reduce, the tensile strength is increased.

In Examples 3 to 7, it is understood that a protective film having excellent moisture permeability and tensile strength can be obtained in the same manner as in Example 2, although a functional layer is provided on the protective film.

Further, in Example 8, by using a reactive cerium sol, it was shown to have good water-based adhesion to the polarizing film.

From the above examples and comparative examples, it is understood that in the production of a protective film, a protective film formed by polymerizing a main chain of an amine ester (meth) acrylate using a branched chain alkyl group can be understood to have a low Moisture permeability and high self-reliance.

Further, it is understood that the water-based adhesion property to the polarizing film is obtained by appropriately utilizing the reactive cerium sol.

[Industrial availability]

Since the protective film of the present invention is low in moisture permeability and self-standing in a state of a thin layer, it is used for applications requiring low moisture permeability, and particularly has structural members for use as a polarizing plate, and can be utilized in various fields. in.

Claims (15)

A protective film comprising a protective film formed by a repeating unit derived from a structure of an amine ester (meth) acrylate belonging to a monomer having a branched chain alkyl group and a saturated cyclic fat The above-mentioned repeating unit comprises the following structure A1 or structure B1 containing R ¹ wherein R ¹ is a branched chain alkyl group; -CO-NH-R ¹ -NH-CO-. . . (Structure A1) -OR ¹ -O-. . . (Structure B1). The protective film according to claim 1, wherein when the repeating unit contains the structure A1, the structure further comprises a structure B2 containing R ² , wherein R ² is a branched chain alkyl group or a saturated ring. The aliphatic group; when the repeating unit contains the structure B1, further comprises the following structure A2 comprising R ² , wherein R ² is a branched chain alkyl group or a saturated cyclic aliphatic group; -CO-NH-R ² -NH-CO-. . . (Structure A2) -OR ² -O-. . . (Structure B2). The protective film according to claim 1, wherein the repeating unit has a structure represented by the following formula (1). In the formula (1), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, m represents an integer of 0 or more, and x represents an integer of 0 to 3. The protective film according to claim 2, wherein the repeating unit has a structure represented by the following formula (2). In the formula (2), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, n represents an integer of 1 or more, and x represents an integer of 0 to 3. The protective film according to claim 1, wherein the repeating unit has a structure represented by the following formula (3). In the formula (3), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, m represents an integer of 0 or more, and x represents an integer of 0 to 3. The protective film according to claim 2, wherein the repeating unit has a structure represented by the following formula (4). In the formula (4), R ¹ represents a branched chain alkyl group, R ² represents a branched chain alkyl group or a saturated cyclic aliphatic group, R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a hydrogen atom, A Or an ethyl group, n represents an integer of 1 or more, and x represents an integer of 0 to 3. The protective film of claim 3, wherein the m is 1 or 2. The protective film according to Item 4 or Item 6, wherein the above n is 1 or 2. The protective film according to any one of claims 3 to 6, wherein the above R ¹ is an alkyl group having two or more branched chains. The protective film according to claim 3, wherein the above R ¹ is trimethylhexamethylene. The protective film according to any one of claims 1 to 6, which has a moisture permeability of 100 g/(m ² .24 hours) or less and a tensile strength of 25 MPa or more. The protective film according to any one of claims 1 to 6, which contains an ultraviolet absorber. The protective film according to any one of claims 1 to 6, which is characterized in that it contains at least an amine ester (meth) acrylate belonging to the above monomer and a reactive cerium sol having an organic reactive group. A protective film obtained by hardening a resin composition, and the surface of the protective film is subjected to plasma treatment or corona treatment. A film laminate according to any one of the following items (1) to (4), wherein at least one side of the protective film according to any one of claims 1 to 13 is: (1) a film substrate supporting the protective film, (2) a hard coat layer having scratch resistance, (3) an antiglare layer for scattering light, and (4) an antireflection layer provided on the protective film The high refractive index layer and the low refractive index layer provided on the high refractive index layer are formed. A polarizing plate comprising the protective film according to any one of the first to thirteenth aspects of the invention, wherein at least one side of the polarizing film is provided.