KR20200054235A - Polarizing film protective laminate and method for manufacturing the same - Google Patents

Abstract

A laminate for protecting a polarizing film in which a photocurable resin layer made of a radically polymerizable compound is laminated on a base film, wherein the photocurable resin layer has a thickness of 9 µm or less, and the boric acid transmittance of the photocurable resin layer is 2.25 in terms of boron atoms. g / m 2 · day or less, the adhesion between the base film and the photocurable resin layer is 0.005 to 0.06 N / mm, and the photocurable resin layer on the base film side after peeling the base film from the photocurable resin layer It is characterized by being a laminate for protecting a polarizing film having a mean square surface roughness (rms) of 300 nm or less. Thereby, the laminated body for polarizing film protection which can obtain the polarizing plate excellent in surface smoothness, and excellent in moisture heat resistance even if the thickness of a photocurable resin layer is 9 micrometers or less, and its manufacturing method are provided.

Description

Polarizing film protective laminate and method for manufacturing the same

The present invention relates to a laminate for protecting a polarizing film in which a photocurable resin layer is laminated on a base film, and a method for producing the laminate.

A polarizing plate having a function of transmitting and shielding light is a basic component of a liquid crystal display (LCD) along with liquid crystals that change the polarization state of light. Many of the polarizing plates have a structure in which a protective film such as cellulose triacetate (TAC) film is bonded to the surface of the polarizing film, and a polyvinyl alcohol (PVA) film is used as a polarizing film constituting the polarizing plate 1 it has been a mainstream with or dichroic (二色性) dichroic dye such as an organic dye is adsorbed to the axial stretching in an iodine-based dye was stretched film orientation (such as I ₃ ^{- -} or I _5). Such a polarizing film is usually a uniaxially stretched PVA film containing a dichroic dye in advance, adsorbs a dichroic dye simultaneously with uniaxial stretching of the PVA film, or uniaxially stretches the PVA film and then dichroic dye. It is produced continuously by adsorbing or the like.

LCDs are intended to be used in a wide range of small devices such as electronic desk calculators and wrist watches, notebook PCs, liquid crystal monitors, liquid crystal color projectors, liquid crystal televisions, vehicle navigation systems, smart phones, and indoor and outdoor measurement equipment. In particular, with the development of mobile applications such as small-sized smart phones, the demand for thinning of the polarizing plate is increasing. In addition, in mobile applications, since the place of use extends over a wide range, improvement in durability is also demanded at the same time.

One of the techniques for thinning the polarizing plate includes thinning the protective film, and recently, a polarizing plate having a photocurable resin layer instead of the protective film has been proposed (for example, see Patent Documents 1 to 4, etc.). ).

Japanese Patent Application Publication No. 2011-221185 Japanese Patent Publication No. 2004-245924 Japanese Publication Patent Publication No. 2013-513832 Japanese Patent Application Publication No. 2008-20891

However, in the polarizing plates provided with the photocurable resin layers described in Patent Documents 1 to 4, polarization performance may be deteriorated when used under high temperature and high humidity conditions. When a composition composed of a radically polymerizable compound or the like is coated directly on the surface of the polarizing film, as in the method described in Patent Literature 1 or 2, the surface smoothness of the photocurable resin layer tends to decrease, and polarization performance of the polarizing plate due to disturbance This may decrease. In addition, the solvent contained in the composition composed of a radically polymerizable compound or the like erodes the polarizing film, or the polarization performance is lowered, or the adhesive force between the polarizing film and the photocurable resin layer is lowered, and the polarizing plate is reduced to a panel size from a long roll. There is a problem that the photocurable resin layer is peeled off during handling such as cutting. In addition, when a composition composed of a radically polymerizable compound or the like is directly coated on the surface of the polarizing film, since the polarizing film may be deteriorated, it is difficult to sufficiently irradiate ultraviolet rays or electron beams, and it is difficult to increase the crosslinking density. On the other hand, in Patent Documents 3 or 4, a method of bonding a photocurable resin layer and a polarizing film using an adhesive after forming a photocurable resin layer on a base film such as a release PET film has been proposed. However, when the peelability of the base film and the photocurable resin layer is not good, the surface smoothness of the photocurable resin layer is lowered, and the polarization performance of the polarizing plate may be lowered due to disturbance. Moreover, polarization performance may fall when used under high temperature and high humidity conditions, and improvement has been required.

The present invention has been made to solve the above problems, the surface smoothness is excellent, even if the thickness of the photo-curable resin layer is less than 9 ㎛, can obtain a polarizing plate excellent in heat and moisture resistance, a polarizing film protective laminate, and a method of manufacturing the same It is aimed at providing.

As a result of repeated examinations of the inventors in order to achieve the above object, even if the thickness of the photocurable resin layer is 9 μm or less, the photocurable resin layer having a boric acid transmittance of 2.25 g / m 2 · day or less in terms of boron atom is a polarizing film. Based on these findings, it was found that a polarizing plate excellent in moisture and heat resistance was obtained by bonding to the substrate, and a photocurable resin layer excellent in surface smoothness was obtained by having an adhesive strength between the base film and the photocurable resin layer of 0.005 to 0.06 N / mm. Then, further examination was repeated to complete the present invention.

That is, the present invention,

[1] A laminate for protecting a polarizing film in which a photocurable resin layer made of a radically polymerizable compound is laminated on a base film,

The thickness of the photocurable resin layer is 9 μm or less, and the boric acid transmittance of the photocurable resin layer is 2.25 g / m 2 · day or less in terms of boron atom,

The adhesive force between the base film and the photocurable resin layer is 0.005 to 0.06 N / mm,

A laminate for protecting a polarizing film having a square average surface roughness (rms) of the photocurable resin layer on the base film side after peeling the base film from the photocurable resin layer is 300 nm or less;

[2] The polarizing plate in which the photocurable resin layer in the laminate for protecting a polarizing film according to [1] is pasted through an adhesive layer on at least one surface of the polarizing film;

[3] A method for producing a laminate for protecting a polarizing film obtained by laminating a photocurable resin layer made of a radically polymerizable compound on a base film,

A step of coating a solution containing a radically polymerizable compound and a solvent on a base film,

A step of heating the base film after coating to volatilize the solvent,

It has a process of irradiating at least one of ultraviolet rays and electron beams,

The manufacturing method of the laminated body for polarizing film protection as described in [1] characterized by the water contact angle of the coating surface of the said base film being 40-100 degree;

[4] The method for producing a laminate for protecting a polarizing film according to [3], wherein the detection strength of silicon on the coating surface of the base film is 10 cps / mA or less;

It is about.

ADVANTAGE OF THE INVENTION According to this invention, even if the surface smoothness is excellent and the thickness of a photocurable resin layer is 9 micrometers or less, the polarizing film protective laminated body which can obtain the polarizing plate excellent in moisture-heat resistance, and its manufacturing method are provided.

1 is a schematic view of a method for measuring boric acid permeability in terms of boron atoms.

The present invention will be described in detail below.

<Lamination body for polarizing film protection>

The laminate for protecting a polarizing film of the present invention is a laminate for protecting a polarizing film in which a photocurable resin layer made of a radically polymerizable compound having a thickness of 9 µm or less is laminated on a base film, wherein the boric acid transmittance of the photocurable resin layer is in terms of boron atoms. It is characterized by being less than 2.25 g / m 2 · day. When the boric acid transmittance of the photocurable resin layer is 2.25 g / m 2 · day or less in terms of boron atom, a polarizing plate having excellent heat and moisture resistance that can maintain initial polarization performance when bonded to a polarizing film can be obtained. When the boric acid transmittance exceeds 2.25 g / m 2 · day in terms of boron atom, the heat and moisture resistance of the polarizing plate cannot be sufficiently improved. From this viewpoint, the boric acid transmittance of the photocurable resin layer is preferably 1.50 g / m 2 · day or less in terms of boron atom, more preferably 0.50 g / m 2 · day or less, and even more preferably 0.20 g / m 2 · day or less , 0.10 g / m 2 · day or less is particularly preferred. On the other hand, the lower limit of the boric acid transmittance in terms of boron atom in the photocurable resin layer is not particularly limited, but when the boric acid permeability in boron atom conversion is too low, the flexibility of the photocurable resin layer tends to be easily lost. Is preferably 0.02 g / m 2 · day or more in terms of boron atom, and more preferably 0.03 g / m 2 · day or more. In addition, the boric acid permeability of boron atom conversion can be calculated | required by the method described in the Example mentioned later.

In the present invention, the photocurable resin layer is made of a radically polymerizable compound or the like. By using a radically polymerizable compound, the boric acid permeability of boron atom conversion of the obtained photocurable resin layer can be reduced. As the radically polymerizable compound, a compound having an acryloyl group in the molecule can be preferably used. As the radically polymerizable compound, one type may be used alone, or two or more types may be used in combination. Moreover, it is preferable to use a radical polymerization initiator as a photoinitiator for curing by irradiating at least one of ultraviolet rays and electron beams. As a radical polymerization initiator, the compound which can accelerate the reaction of a radically polymerizable compound by irradiating an active energy ray can be used. Examples of such radical polymerization initiators include carbonyl compounds such as acetophenones, benzophenones, mihila ketones, and benzoin; And sulfur compounds such as tetramethylthiuram monosulfide and thioxanthone, and carbonyl compounds are preferred. These radical polymerization initiators may be used alone or in combination of two or more.

In the present invention, the thickness of the photocurable resin layer is 9 µm or less. When the thickness exceeds 9 μm, sufficient thinning cannot be achieved for a polarizing plate laminated with a conventional protective film. From this viewpoint, the thickness of the photocurable resin layer is preferably 8 μm or less, more preferably 7 μm or less, and even more preferably 6 μm or less. On the other hand, although the lower limit of the thickness of the photocurable resin layer is not particularly limited, when the boric acid transmittance of the boron atom is achieved in the thin photocurable resin layer, the flexibility of the photocurable resin layer tends to be easily lost. It is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more.

As a base film used for the polarizing film protective laminate of the present invention, it is preferable to have excellent surface uniformity, polycarbonate film, triacetyl cellulose film, norbornene film, polypropylene film, polyester film, polystyrene film, etc. Can be used. The surface of the base film on the side of the photocurable resin layer may be subjected to a release treatment. By using the base film excellent in surface uniformity, the square average surface roughness (rms) of the photocurable resin layer on the base film side after peeling the base film from the photocurable resin layer tends to be 300 nm or less.

In the present invention, the adhesive force between the photocurable resin layer and the base film is 0.005 to 0.06 N / mm. Since it is necessary to peel the base film from the photocurable resin layer after bonding the photocurable resin layer with the polarizing film to obtain a polarizing plate, the adhesive force between the photocurable resin layer and the base film is preferably 0.05 N / mm or less, and 0.04 N / mm or less is more preferable, and 0.03 N / mm or less is more preferable. In addition, by strengthening the release treatment of the base film used, the adhesion between the photocurable resin layer and the base film can be 0.06 N / mm or less. When the adhesion between the photocurable resin layer and the base film is too low, the base film is peeled from the photocurable resin layer and handled when handling a laminate for protecting a polarizing film, such as when the photocurable resin layer is bonded to a polarizing film. From the point of difficulty, the adhesion between the photocurable resin layer and the base film is preferably 0.010 N / mm or more, more preferably 0.013 N / mm or more, and even more preferably 0.015 N / mm or more.

In the present invention, the square average surface roughness (rms) of the photocurable resin layer on the base film side after peeling the base film from the photocurable resin layer is 300 nm or less. The square average surface roughness (rms) of the photocurable resin layer on the base film side is preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 150 nm or less. In order to set the square-average surface roughness (rms) of the photocurable resin layer on the base film side to 300 nm or less, a solution containing a radically polymerizable compound and a solvent on the base film when forming the laminate for polarizing film protection appears It is important not to turn or to have good peelability between the base film and the photocurable resin layer, and as described later, it is effective to adjust the solubility parameter of the solvent used for the radical polymerizable compound and the water contact angle of the coated surface of the base film. Do. The lower limit of the squared average surface roughness (rms) of the photocurable resin layer on the base film side is not particularly limited, but it is, for example, 20 nm or more in that it is difficult to have an excessively smooth surface.

<Method for producing a laminate for polarizing film protection>

As a manufacturing method of the laminated body for polarizing film protection of this invention, the process of apply | coating the solution containing a radically polymerizable compound and a solvent to a base film, the process of heating a base film and volatilizing a solvent after coating, and ultraviolet ray and electron beam It has a process of irradiating at least one of, and it is preferable that the water contact angle of the coated surface of the base film is 40 to 100 degrees. By containing a solvent in the solution, the surface smoothness of the photocurable resin layer having a thickness of 9 µm or less becomes good.

[Coating process]

As a process of coating the base film with a solution containing a radically polymerizable compound and a solvent, any suitable method may be employed. As a method of coating the base film with a solution containing a radically polymerizable compound and a solvent, for example, die coat, roll coat, air knife coat, gravure roll coat, doctor roll coat, doctor knife coat, curtain flow coat, And methods such as spray coating, wire bar coating, road coating, dipping, and brush application. Especially, in order to make the thickness of the photocurable resin layer obtained 9 micrometers or less, a gravure roll coat is preferable.

[Solvent volatilization process]

Any suitable method may be employed as a step of heating the base film after coating the solution to volatilize the solvent. The base film coated with the solution may be heated on a heat roll or may be heated in a floating dryer. The preferred temperature of the heat roll or hot air can be determined depending on the boiling point of the solvent to be used, but is preferably in the range of 60 ° C to 120 ° C. Moreover, it is preferable to volatilize a solvent until the residual amount of a solvent becomes 10% or less.

[Investigation process]

As a process of irradiating at least one of ultraviolet rays and electron beams, after drying the solution coated on the base film, at least one of ultraviolet rays and electron beams may be directly irradiated or may be irradiated from the base film side. Moreover, it is more preferable to have a process of irradiating ultraviolet rays from the viewpoint of curing speed, availability of the irradiation device, price, and the like.

The ultraviolet rays or electron beams can be irradiated using a known device. When using ultraviolet light, a high-pressure mercury lamp, ultra-high-pressure mercury lamp, carbon arc lamp, metal halide lamp, xenon lamp, chemical lamp, LED, etc. that emit light in a wavelength range of 450 nm or less can be used. Moreover, when using the electron beam EB, it is preferable that it is in the range of 0.1-10 MeV as acceleration voltage, and it is preferable that it is in the range of 1-500 kGy as irradiation dose.

Although there is no restriction | limiting in particular in the integrated light quantity of the said ultraviolet ray or electron beam, It is preferable to exist in the range of 10-20,000 mJ / cm <2>, More preferably, it is in the range of 30-5,000 mJ / cm <2>. If the accumulated light amount of ultraviolet rays or electron beams is too small, curing of the radically polymerizable compound becomes poor, and the boric acid permeability in terms of boron atoms in the photocurable resin layer increases, or the mechanical strength of the photocurable resin layer decreases. On the other hand, when the accumulated light amount of ultraviolet rays or electron beams is too large, excessive heat is generated in the laminate for polarizing film protection, and the photocurable resin layer or the base film may be deteriorated.

In order to increase the crosslinking density of the photocurable resin layer during or after irradiation with ultraviolet rays or electron beams, the photocurable resin layer may be accelerated by heating as necessary. The heating temperature is preferably in the range of 40 to 130 ° C, more preferably in the range of 50 to 100 ° C, from the viewpoint of the curing rate, the effect on the photocurable resin layer, and the base film. When the temperature is less than 40 ° C, curing of the photocurable resin layer is not promoted well, and when the temperature exceeds 130 ° C, the base film tends to deform and a smooth photocurable resin layer may not be obtained. have. With the above method, since the crosslinking density of the photocurable resin layer on the base film can be sufficiently increased, it is possible to desirably lower the boric acid transmittance in terms of boron atom conversion.

In the manufacturing method of the laminated body for polarizing film protection of this invention, it is preferable that the water contact angle of the solution coating surface of a base film is 40-100 degrees. When the water contact angle of the solution coating surface of the base film is large, when the solution is coated on the base film, the solution tends to turn out and it is sometimes difficult to uniformly coat the solution. In addition, even when the solution can be uniformly coated, there is a problem that the surface of the photocurable resin layer on the base film side after peeling the base film from the photocurable resin layer is not smoothed well. On the other hand, when the water contact angle is small, the adhesion between the base film and the photocurable resin layer becomes strong, making it difficult to peel the base film from the photocurable resin layer, or after peeling the base film from the photocurable resin layer, to the base film side. The surface smoothness of the photocurable resin layer in the case may be rough. From these viewpoints, the water contact angle of the solution coating surface of the base film is preferably 45 to 95 degrees, more preferably 50 to 90 degrees, and even more preferably 55 to 85 degrees. In order to adjust the water contact angle of the solution coating surface of the base film within the above range, it is effective to adjust the strength of the hydrophilic treatment such as corona treatment.

It is preferable that the solubility parameter (SP value) of the solvent of the solution containing a radically polymerizable compound and a solvent is 8-10 (cal / cm <3>) ^1/2 . If the solubility parameter of the solvent is too small or too large, when the solution is coated on the base film, the solution tends to turn out and it is difficult to uniformly coat the solution. From this point of view, the solubility parameter of the solvent is more preferably in the range of 8.2 to 9.8 (cal / cm 3) ^1/2 , more preferably in the range of 8.4 to 9.6 (cal / cm 3) ^1/2 , and 8.6 to 9.4 (cal / cm 3) It is particularly preferable to be in the range of ^1/2 . Solubility parameters are those described in the literature (e.g., Polymer Data Handbook: Polymer Society Compilation, Solvent Handbook; Asahara Teruzo et al., DWVAN KREVELEN, PROPERTIES OF POLYMERS Third edition, p214-220 (1990), etc.). Did.

In the manufacturing method of the laminated body for polarizing film protection of this invention, it is preferable that the detection intensity of silicon in the coating surface of a base film is 10 cps / mA or less. Usually, it is possible to improve the peelability of the formed photocurable resin layer by coating a surface of the base film with a release agent containing silicon or the like. However, there is a problem that the release agent containing silicon or the like migrates to a solution containing a radically polymerizable compound and a solvent, and the properties of the resulting photocurable resin layer are changed, or the equipment for manufacturing a laminate for protecting a polarizing film is contaminated. have. For this reason, it is preferable to use a base film which has been subjected to a release treatment by a method that does not use a release agent containing silicon. In addition, the measurement of silicon on the coating surface of a base film can be measured using an X-ray analysis microscope, as described in the Example mentioned later.

<Polarizing plate>

In the polarizing plate obtained by the present invention, a photocurable resin layer is pasted on at least one surface of a polarizing film via an adhesive layer. Thereby, a polarizing plate excellent in heat resistance and surface smoothness can be obtained. The polarizing film used to manufacture the polarizing plate is after uniaxially stretching a PVA film containing a dichroic dye in advance, adsorbing a dichroic dye simultaneously with uniaxial stretching of the PVA film, or uniaxially stretching the PVA film. It can be produced by adsorbing a dichroic dye or the like.

By attaching the photocurable resin layer in the polarizing film protective layered product of the present invention to a polarizing film, a polarizing plate excellent in moisture resistance and heat resistance can be produced while being thin and lightweight. There is no restriction | limiting in particular in the manufacturing method of a polarizing plate, For example, the process of laminating | stacking the photocurable resin layer in the laminated body for polarizing film protection of this invention via an adhesive layer on at least one surface of a polarizing film (bonding process) ), And the step of curing the adhesive layer by irradiating at least one of ultraviolet rays or electron beams after the bonding step (adhesive step), and further, a step of peeling the base film after the bonding step (peeling step). It can be produced by a method.

[Combination process]

In the pasting step, the photocurable resin layer in the laminate for polarizing film protection of the present invention is pasted on at least one surface of the polarizing film via an adhesive layer. Although there is no restriction | limiting in particular in this bonding method, From the point which can be more easily bonded, the method of superimposing a polarizing film after apply | coating an adhesive to the surface of the photocurable resin layer in the laminated body for polarizing film protection of this invention is preferable. Further, an adhesive may be applied to the surface of the photocurable resin layer in the other laminate for protecting a polarizing film, and may be superimposed on the other surface of the polarizing film. The method of applying the adhesive is not particularly limited, for example, die coat, roll coat, air knife coat, gravure roll coat, doctor roll coat, doctor knife coat, curtain flow coat, spray coat, wire bar coat, road coat And methods such as brush application.

Moreover, you may pressurize the paste obtained in the pasting process with a roll etc. In this case, as the material of the roll, for example, metal, rubber, or the like can be mentioned.

The adhesive used is not particularly limited as long as it can bond the polarizing film and the photocurable resin layer, and a solvent-free photocurable adhesive or the like is preferably used.

Further, in order to further improve the adhesion between the polarizing film and the photo-curable resin layer, the surface of the photo-curable resin layer may be modified by known corona treatment, plasma treatment, UV treatment, flame treatment, or the like, if necessary.

[Adhesion process]

In the bonding step, at least one of ultraviolet rays or electron beams is irradiated to cure the uncured adhesive layer. Irradiation of ultraviolet rays or electron beams can be carried out using a known device. Although there is no particular limitation on the amount of accumulated light of ultraviolet rays or electron beams, it is preferably in the range of 10 to 20,000 mJ / cm 2, and more preferably in the range of 30 to 5,000 mJ / cm 2. When the accumulated light amount is too small, the adhesion between the polarizing film and the photocurable resin layer may be insufficient. On the other hand, if the accumulated light amount is too large, excessive heat is generated, and the adhesive layer, the polarizing film, and the photocurable resin layer may be deteriorated. Moreover, it is more preferable to use ultraviolet rays from the viewpoints of curing speed, availability of the irradiation device, price, and the like.

Curing of the adhesive layer may be accelerated by heating, if necessary, during or after irradiation of ultraviolet rays or electron beams. The heating temperature is preferably in the range of 40 to 130 ° C, and more preferably in the range of 50 to 100 ° C, from the viewpoint of the curing rate, the degree of deterioration of a polarizing film, and the like. When the temperature is less than 40 ° C, curing of the adhesive layer is not facilitated, and when the temperature exceeds 130 ° C, the polarizing film or the base film tends to deteriorate or deform, and a polarizing plate excellent in polarization performance and smoothness can be obtained well. none.

[Peeling process]

By peeling the base film after the bonding step, a polarizing plate in which the photocurable resin layer is disposed via at least one side of the polarizing film via an adhesive layer can be obtained.

Example

Although the present invention is specifically described by the following examples, the present invention is not limited at all by these examples. In addition, each evaluation method and measurement method employed in the following Examples and Comparative Examples are shown below.

[Borrate transmittance in terms of boron atom in the photocurable resin layer]

The photocurable resin layer obtained in each of the following Examples or Comparative Examples was attached to a moisture permeability cup (fastening type, conforming to JIS Z-0208) with pure water, and immersed in an aqueous solution of boric acid in 8 mass% at 60 ° C. Then, the boron concentration of the number of samples (pure water) in the moisture permeability cup before the start of the test and the number of samples in the moisture permeability cup 24 hours after immersion was analyzed by the ICP emission analysis method (Shimadzu Corporation's Shimadzu multi-type ICP emission analysis device ICPE-9000), The boric acid permeability (A) of the boron atom conversion was calculated from the boron concentration increase amount by the following formula (1) (see Fig. 1).

A = {a ₂₄ -a ₀ ) × 10 ^-6 × M} / S (1)

A: Boric acid permeability in terms of boron atom conversion [g / ㎡ · day]

a ₂₄ : Boron concentration in the number of samples after 24 hours [ppm]

a ₀ : Boron concentration in the number of samples (pure water) before the start of the test [ppm]

M: Weight of sample number [g]

S: Area where the photocurable resin layer and the aqueous boric acid solution are in contact (transmitted area of the moisture permeability cup) [㎡]

[Adhesive force between base film and photocurable resin layer]

The polarizing film protective laminate obtained in each of the following Examples or Comparative Examples was left standing for 24 hours under conditions of 23 ° C and 50% RH, and then a 250 mm x 25 mm single-handed desk from the laminate for protecting the polarizing film ( Iii) Five film pieces were cut out. Next, for each film piece, the base film and the photocurable resin layer were peeled off according to the T-type peeling test of JIS K6854-3: 1999, and the average value of the five measurements of the peeling force obtained was used as the adhesive force. In this test, the peeling rate was 30 mm / min. Moreover, when the adhesive force of a base film and a photocurable resin layer is too high and a base film or a photocurable resin layer was destroyed, it evaluated as "material destruction."

[Squared average surface roughness (rms) of the photocurable resin layer on the base film side]

The base film of the polarizing film protective laminate obtained in each of the following examples or comparative examples was peeled off, and the surface of the photocurable resin layer on the base film side was exposed. Then, the surface shape of the photocurable resin layer on the base film side was measured using a white interference microscope (manufactured by Zygo), and the square average surface roughness (rms) was calculated (calculation range is 2.0 mm × 2.7 mm).

[Water contact angle]

A 200 mm × 15 mm single-walled film piece was cut out from the base film used in the following Examples or Comparative Examples, and the water contact angle on the solution coating surface of the film piece was JIS R3257: 1999 (substrate glass surface It was measured in accordance with the description of the wettability test method. That is, 4 μl or less of water droplets are left on a horizontally placed film piece, the shape of the water drop is measured, and the radius r (mm) of the surface where the water drop is in contact with the film piece, and from the surface of the film piece to the peak of the water drop From the height h (mm), the water contact angle θ (degree) was obtained by the following formula (2).

θ = 2tan ^-1 (h / r) (2)

In addition, measurement was performed 5 times, and the average value was made into the water contact angle of the base film. Moreover, the measurement was performed on condition of 25 degreeC and 50% RH.

[Silicone on the coated surface of the base film]

A film piece having a width and width of 50 mm was cut out from the base film used in the following Examples or Comparative Examples, and an X-ray analysis microscope (XGT-5200 manufactured by Horiba Co., Ltd., X-ray irradiation diameter of 100 µm, current of 1 mA, Using the X-ray tube voltage 30 kV, measurement time 400 seconds), the detection strength of silicon on the solution coated surface of this film piece was measured.

[All light transmittance and polarization degree of the polarizing plate]

Two rectangular samples of 2 cm in the longitudinal direction (MD) and 3 cm in the width direction (TD) were taken from the central portion of the width direction (TD) of the polarizing plate obtained in the following Examples or Comparative Examples. For each sample, the transmittance of light in the case of a 45 ° tilt and the transmittance of light in the case of a -45 ° tilt with respect to the longitudinal direction were measured, and all of these average values were taken as the total light transmittance (%) of the polarizing plate. In addition, the transmittance of light T ∥ (%) when the two samples were in parallel nicol state, and the transmittance T⊥ (%) of light when the two samples were in cross nicol state, were the total light transmittance (%). It measured in the same manner as in the case of, and the polarization degree was obtained by the following formula (3). In addition, the measurement of transmittance was performed using a spectrophotometer with an integrating sphere ("V7100" manufactured by Nippon Spectrum Co., Ltd.), in accordance with JIS Z 8722 (Measurement method for object color), correcting the visibility of a C light source and a visible light region of 2 ° field of view. Was carried out.

Polarization degree = {(T∥-T⊥) / (T∥ + T⊥)} ^1/2 × 100 (3)

In addition, the initial total light transmittance before the heat resistance test was set to T ₀ .

[Moisture resistance of polarizing plate]

From the central portion of the width direction (TD) of the polarizing plate obtained in the following Examples or Comparative Examples, 2 samples of 4 cm in the longitudinal direction (MD) and 3 cm in the width direction (TD) of the polarizing plate were taken, and each of them was collected. It was fixed to a metal frame, and the initial total light transmittance (T ₀ ) and polarization degree were determined by the above method. Placed in 60 ℃, 90% RH thermo-hygrostat (Yamato Science Co., Ltd. HUMIDIC CHAMBER IG400) of, subjected to moist heat resistance test of 48 hours, the total light transmittance after the moist heat resistance test by the method (T _48), measuring the degree of polarization Did. From the above-mentioned T ₀ and T ₄₈ , the change amount (ΔT) of the total light transmittance was obtained using the following formula (4), and this was used as an index of the moisture resistance and heat resistance of the polarizing plate.

ΔT = T ₄₈ -T ₀ (4)

[Example 1]

<Production of a laminate for polarizing film protection>

As a solution containing a radically polymerizable compound and a solvent, Heataloid 7975 containing a radically polymerizable compound (manufactured by Hitachi Chemical Co., Ltd., resin powder 32 mass%, solvent toluene, solvent SP value 8.9) 31.25 g and 1-hydride A solution was obtained by weighing 0.4 g of hydroxycyclohexylphenylketone (manufactured by BASF, IRGACURE 184) into a sample tube and stirring and mixing it uniformly for 24 hours. Thereafter, as a base film, a Ray Hyper F (a Nakai Industries Co., Ltd., water contact angle of 68.9 degrees, a detection strength of 5.25 cps / mA of silicon), which is a release-treated PET film, was cut to a size of 300 mm × 150 mm, and a bar coater was used Then, the solution was coated on the release treatment surface, heated at 70 ° C. for 1 minute to volatilize the solvent, and then integrated using an ultraviolet irradiation device (using a metal halide lamp manufactured by GS YUASA, irradiation intensity of 300 mW / cm 2). By irradiating ultraviolet rays so that the light amount was 300 mJ / cm 2, a laminate for protecting a polarizing film having a photocurable resin layer having a thickness of 5.9 µm on a base film was obtained. In addition, about this integrated light quantity, it measured using the UV meter (GS YUASA Co., Ltd.).

<Evaluation of the laminate for polarizing film protection>

About the obtained laminated body for polarizing film protection, by the above-mentioned method, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square of the photocurable resin layer on the base film side The average surface roughness (rms) was evaluated. The results are shown in Table 1 and Table 2.

<Production of the polarizing film>

A long PVA film with a thickness of 30 μm and a width of 65 cm (containing PVA and glycerin and surfactant, the content of glycerin is 12 parts by mass relative to 100 parts by weight of PVA, and the content of surfactant is 100 parts by mass of PVA) PVA film with respect to 0.03 parts by mass.PVA is a saponified product of a vinyl acetate homopolymer, the degree of polymerization is 2,400, and the degree of saponification is 99.9 mol%.) Continuously released from the film roll, followed by swelling treatment, dyeing treatment, crosslinking A polarizing film was produced by performing treatment, stretching treatment, fixing treatment, and drying treatment.

That is, as a swelling treatment, the PVA film was immersed in water at 30 ° C for 1 minute, and uniaxially stretched in the longitudinal direction at a draw ratio of 2 times. Then, as a dyeing treatment, it was immersed in an aqueous solution containing an iodine dye (iodine concentration: 0.02 mass%, potassium iodide concentration: 0.4 mass%, 30 ° C) for 1 minute, and uniaxially stretched in the longitudinal direction at a draw ratio of 1.2 times during that time. Did. Moreover, as a bridge | crosslinking process, it immersed in the boric-acid aqueous solution (boric-acid concentration: 2.6 mass%, 30 degreeC) for 2 minutes, and uniaxially stretched in the longitudinal direction with the draw ratio 1.1 times in the meantime. Subsequently, as the stretching treatment, uniaxial stretching was performed in the longitudinal direction at a stretching ratio of 2.4 times in a boric acid aqueous solution (borate concentration: 2.8 mass%, potassium iodide concentration: 5 mass%, 57 ° C) (total stretching ratio: 6.3). Moreover, as a fixing treatment, it was immersed for 10 seconds in a boric-acid aqueous solution (boric acid concentration: 1.5 mass%, potassium iodide concentration: 5 mass%, 22 degreeC). And as a drying process, it dried at 60 degreeC for 1 minute, and obtained the polarizing film.

<Production of adhesives>

3-ethyl-3-hydroxymethyloxetane (manufactured by Toa Synthetic Corporation, OXT-101) 2 g, 3 ', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicel Co., Ltd. , Celloxide 2021P) 8 g, and 0.8 g of a 50% by mass solution of propylene carbonate (CPI-100P, manufactured by San Afro Co., Ltd.) of diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate was weighed into a sample tube. Then, the mixture was uniformly mixed by stirring for 24 hours to obtain an adhesive for bonding the polarizing film and the photocurable resin layer.

<Production of the polarizing plate>

The polarizing film protective laminate was cut into two pieces having a size of 140 mm × 120 mm, and the adhesive was coated on the photocurable resin layer surface of the first polarizing film protective laminate using a bar coater. Next, thereon, the polarizing film cut out by 120 mm in the longitudinal direction (MD) and 100 mm in the width direction (TD) was superimposed through the adhesive. Thereafter, the same adhesive as above was applied to the photocurable resin surface of the second laminate for protecting a polarizing film using a bar coater, and superposed on the other side of the polarizing film. The base film / photo-curing resin layer / adhesive / polarizing film / adhesive / photo-curing resin layer / base film obtained in this way is pressed by passing through the laminator through a laminate having the layer constitution, and the thickness of the portion of the adhesive. Was adjusted to be 1 µm each. Thereafter, after irradiating with ultraviolet rays and curing the adhesive, the base film on both sides was peeled off to obtain a polarizing plate.

<Evaluation of the polarizing plate>

With respect to the obtained polarizing plate, by the above method, the initial polarization performance (initial total light transmittance (T ₀ ), polarization degree) of the polarizing plate and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat and humidity resistance test (T ₄₈ ), polarization Moreover, evaluation of the change amount ((DELTA) T) of total light transmittance was performed. Table 2 shows the results.

[Example 2]

A laminate and a polarizing plate for protecting a polarizing film were obtained in the same manner as in Example 1 except that the obtained photocurable resin layer had a thickness of 1.4 μm. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ), The initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization degree) and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat resistance test (T ₄₈ ), the degree of change in the polarization degree and the total light transmittance (ΔT) )). The results are shown in Table 1 and Table 2.

[Example 3]

As the base film, a release-treated PET film, Rayhyper N1 (manufactured by Nakai Industries, Inc., water contact angle of 84 degrees, detection strength of silicon of 5.89 cps / mA) was used, and the obtained photocurable resin layer had a thickness of 5.5 µm. In the same manner as in Example 1, a laminate for protecting a polarizing film and a polarizing plate were obtained. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ), The initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization degree) and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat resistance test (T ₄₈ ), the degree of change in the polarization degree and the total light transmittance (ΔT) )). The results are shown in Table 1 and Table 2.

[Example 4]

As the base film, a release-treated PET film using Purex AN15 (Teijin DuPont Film Co., Ltd., water contact angle 82.7 degrees, detection strength of silicon 6.12 cps / mA), and the obtained photocurable resin layer having a thickness of 5.6 μm Except in the same manner as in Example 1, a laminate for protecting a polarizing film and a polarizing plate were obtained. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ), The initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization degree) and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat resistance test (T ₄₈ ), the degree of change in the polarization degree and the total light transmittance (ΔT) )). The results are shown in Table 1 and Table 2.

[Example 5]

As a radically polymerizable compound, 5 g of dimethylol tricyclodecane diacrylate (Kyoeisha Chemical Co., Ltd., light acrylate DCP-A) and tris (2-hydroxyethyl) isocyanurate triacrylate (Toa Synthetic Co., Ltd.) Preparation, M-315) 5 g, 0.4 g of 1-hydroxycyclohexylphenylketone (manufactured by BASF, IRGACURE 184) as a photopolymerization initiator, and ethyl acetate (manufactured by Wako Pure Chemical Industries, SP value 9.1) as a solvent The amount of was weighed into a sample tube, stirred 24 hours, and uniformly mixed to obtain a solution. After this, a laminate and a polarizing plate for protecting a polarizing film were obtained in the same manner as in Example 1 except that the obtained photocurable resin layer had a thickness of 5.1 μm. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ), The initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization degree) and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat resistance test (T ₄₈ ), the degree of change in the polarization degree and the total light transmittance (ΔT) )). The results are shown in Table 1 and Table 2.

[Comparative Example 1]

As a radically polymerizable compound, Heataloid 7975D (made by Hitachi Chemical Co., Ltd., resin content 60 mass%, solvent methyl isobutyl ketone, SP value of solvent 8.4) 16.67 g, and 1-hydroxycyclohexylphenyl ketone as photopolymerization initiator (Manufactured by BASF, IRGACURE 184) 0.4 g was weighed into a sample tube, stirred for 24 hours, and uniformly mixed to obtain a solution. After this, a laminate and a polarizing plate for protecting a polarizing film were obtained in the same manner as in Example 1 except that the thickness of the obtained photocurable resin layer was 6.0 μm. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ), The initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization degree) and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat resistance test (T ₄₈ ), the degree of change in the polarization degree and the total light transmittance (ΔT) )). The results are shown in Table 1 and Table 2.

[Comparative Example 2]

As a radically polymerizable compound, 10 g of 3 ', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicel Co., Ltd., Celloxide 2021P), and diphenyl [4- ( By weighing 0.8 g of a 50% by mass solution (CPI-100P, manufactured by San Apro Co., Ltd.) consisting of phenylthio) phenyl] sulfonium hexafluorophosphate and propylene carbonate as a solvent, the sample tube was stirred and stirred for 24 hours to uniformly mix, A solution was obtained. After this, a laminate and a polarizing plate for protecting a polarizing film were obtained in the same manner as in Example 1 except that the thickness of the obtained photocurable resin layer was 6.1 μm. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ), The initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization degree) and the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance after the heat resistance test (T ₄₈ ), the degree of change in the polarization degree and the total light transmittance (ΔT) )). The results are shown in Table 1 and Table 2.

[Comparative Example 3]

As the base film, a release-treated PET film using Purex A31 (Teijin DuPont Film Co., Ltd., water contact angle of 110.6 degrees, detection strength of silicon of 19.24 cps / mA) was used, and the obtained photocurable resin layer had a thickness of 5.7 μm. Except in the same manner as in Example 1, a laminate for protecting a polarizing film was obtained. However, since the solution turned out when applied on the PET film, it was impossible to obtain a uniform photocurable resin layer when it was filmed. Therefore, the boric acid transmittance in terms of boron atom in the obtained photocurable resin layer, the adhesive force between the base film and the photocurable resin layer, the square average surface roughness (rms) of the photocurable resin layer on the base film side, and the initial polarization performance of the polarizing plate (Initial total light transmittance (T ₀ ), degree of polarization) and polarization performance after the moisture resistance test of the polarizing plate (total light transmittance after the heat resistance test (T ₄₈ ), degree of polarization, change in total light transmittance (ΔT)) were evaluated. Could not. The results are shown in Table 1 and Table 2.

[Comparative Example 4]

As the base film, the release-treated PET film, Purex A71 (Teijin DuPont Film Co., Ltd., water contact angle 108.2 degrees, silicon detection strength 18.55 cps / mA) was used, and the obtained photocurable resin layer had a thickness of 5.8 μm. Except in the same manner as in Example 1, a laminate for protecting a polarizing film and a polarizing plate were obtained. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ). Since the square-average surface roughness of the photocurable resin layer on the base film side was very large, it was judged as unsuitable, and after the initial polarization performance (initial total light transmittance (T ₀ ), polarization degree) of the polarizing plate and after the heat and moisture resistance test of the polarizing plate Evaluation of the polarization performance (the total light transmittance (T ₄₈ ) after the heat and humidity resistance test, the degree of change in the polarization degree, and the total light transmittance (ΔT)) was stopped. The results are shown in Table 1 and Table 2.

[Comparative Example 5]

As the base film, the same procedure as in Example 1 was performed except that the release-treated PET film, Furex A71 (Teijin DuPont Film Co., Ltd., 18.55 cps / mA of silicon detection strength) was corona-treated and water contact angle was 33.3 degrees. , A polarizing film protective laminate and a polarizing plate were obtained. About the obtained laminated body for polarizing film protection and a polarizing plate, the boric acid transmittance of the photocurable resin layer in terms of boron atom, the adhesive force of the base film and the photocurable resin layer, and the square average surface roughness (rms of the photocurable resin layer on the base film side) ). Since the square-average surface roughness of the photocurable resin layer on the base film side was very large, it was judged as unsuitable, and after the initial polarization performance (initial total light transmittance (T ₀ ), polarization degree) of the polarizing plate and after the heat and moisture resistance test of the polarizing plate Evaluation of the polarization performance (the total light transmittance (T ₄₈ ) after the heat and humidity resistance test, the degree of change in polarization degree, and the total light transmittance (ΔT)) was stopped. The results are shown in Table 1 and Table 2.

[Comparative Example 6]

As the base film, the polarization was performed in the same manner as in Example 1, except that the release-treated PET film TN-100 (manufactured by Toyobo Corporation, 7.11 cps / mA of silicon detection strength) was corona-treated and the water contact angle was 31.1 degrees. A laminate for film protection was obtained. However, the adhesion between the base film and the photocurable resin layer was strong, and the photocurable resin layer was destroyed. Therefore, boric acid transmittance in terms of boron atom in the photocurable resin layer, square average surface roughness (rms) of the photocurable resin layer on the base film side, initial polarization performance of the polarizing plate (initial total light transmittance (T ₀ ), polarization Fig.) And evaluation of the polarization performance after the heat and humidity resistance test of the polarizing plate (the total light transmittance (T ₄₈ ) after the heat and humidity resistance test, the degree of change in the polarization degree and the total light transmittance (ΔT)) could not be performed. The results are shown in Table 1 and Table 2.

1: photocurable resin layer
2: moisture permeability cup
3: pure
4: sealed container
5: 8 mass% aqueous solution of boric acid at 60 ° C
6: Number of samples

Claims (4)

A laminate for protecting a polarizing film in which a photocurable resin layer made of a radically polymerizable compound is laminated on a base film,
The thickness of the photocurable resin layer is 9 µm or less, and the boric acid transmittance of the photocurable resin layer is 2.25 g / m 2 · day or less in terms of boron atom,
The adhesive force between the base film and the photocurable resin layer is 0.005 to 0.06 N / mm,
The laminated body for polarizing film protections whose square average surface roughness (rms) of the photocurable resin layer on the base film side after peeling the base film from the photocurable resin layer is 300 nm or less. A polarizing plate in which the photocurable resin layer in the laminate for protecting a polarizing film according to claim 1 is pasted through an adhesive layer on at least one surface of the polarizing film. As a manufacturing method of the laminated body for polarizing film protection of Claim 1 obtained by laminating | stacking the photocurable resin layer which consists of a radically polymerizable compound to a base film,
A step of coating a solution containing a radically polymerizable compound and a solvent on a base film,
A step of heating the base film after coating to volatilize the solvent,
It has a process of irradiating at least one of ultraviolet rays and electron beams,
The manufacturing method of the polarizing film protective layered product characterized by the water contact angle of the coating surface of the said base film being 40-100 degree. The method of claim 3,
The manufacturing method of the laminated body for polarizing film protection whose detection intensity of silicon in the coating surface of a base film is 10 cps / mA or less.

Images