JP6594782B2 - Polarizing plate with adhesive layer - Google Patents

Description

  The present invention relates to a polarizing plate with an adhesive layer.

  In recent years, as a display panel of various electronic devices, a touch panel that serves as both a display device and an input unit is often used. The types of touch panels are mainly resistive film type, capacitance type, optical type and ultrasonic type. Resistance film type includes analog resistance film type and matrix resistance film type. There are types and projection types.

  As a touch panel in a mobile electronic device such as a smartphone or a tablet terminal that has been attracting attention recently, a projected capacitive type is often used. As a projected capacitive touch panel in such mobile electronic devices, for example, in order from the bottom, a liquid crystal display (LCD), an adhesive layer, a transparent conductive film (tin-doped indium oxide: ITO), a glass substrate, a transparent conductive film ( ITO) and a laminate of protective plates such as tempered glass have been proposed.

  A liquid crystal cell is generally used as an optical component constituting the liquid crystal display device. In general, the liquid crystal cell is arranged such that the alignment layers of the two transparent electrode substrates on which the alignment layers are formed are placed inside, with a predetermined interval by a spacer, and the periphery thereof is sealed to form the two transparent electrode substrates. A liquid crystal material is sandwiched between them. Usually, a polarizing plate is bonded to the outside of two transparent electrode substrates in a liquid crystal cell via an adhesive.

  As an optical pressure-sensitive adhesive, for example, the one shown in Patent Document 1 is known. This pressure-sensitive adhesive contains 0.2 to 20 parts by weight of a carboxyl group-containing monomer as a copolymer component with respect to 100 parts by weight of an alkyl (meth) acrylate having an alkyl group having 4 to 14 carbon atoms as a monomer unit. 0.02 to 2 parts by mass of a peroxide and 0.005 to 5 parts by mass of an epoxy crosslinking agent as a crosslinking agent with respect to 100 parts by mass of the (meth) acrylic polymer and (meth) acrylic polymer to be formed Containing.

JP 2009-242786 A

  Here, with the recent demand for thinner mobile electronic devices, it is also required to reduce the thickness of the polarizing plate. However, the thin film polarizing plate has a high shrinkage rate due to heat or the like, and the conventional adhesive such as Patent Document 1 causes warping of the display panel, and floating or peeling under high temperature conditions or wet heat conditions. There are concerns about problems such as In addition, in order to improve the durability of the pressure-sensitive adhesive, when a monomer having a high glass transition point (Tg) is copolymerized as a component of the (meth) acrylic polymer, a large shrinkage stress is caused under high temperature conditions. As a result, warping of the display panel increases. Furthermore, a problem has been pointed out that light leakage (so-called heat unevenness) occurs due to a deviation of the optical axis of the polarizing plate due to stress at the time of thermal contraction of the polarizing plate.

  On the other hand, the release sheet or the polarizing plate laminated on the pressure-sensitive adhesive layer is usually made of a plastic material, and therefore has high electrical insulation, and static electricity is likely to occur when the release sheet is peeled off. If the polarizing plate is bonded to the liquid crystal cell with the generated static electricity remaining, the orientation of the liquid crystal molecules may be disturbed, and the presence of static electricity will attract dust and dust. Cause problems. In order to solve such a problem, it is conceivable to impart antistatic properties to the pressure-sensitive adhesive layer. However, it is required that the above-described durability is not deteriorated and the display panel is not warped.

  The present invention has been made in view of such a situation, and even if the polarizing plate is a thin film, it is excellent in durability, the display panel is hardly warped, and heat unevenness is hardly generated, and further, the antistatic property is improved. It aims at providing the polarizing plate with an adhesive layer which is also excellent.

  In order to achieve the above object, the present invention provides a polarizer, a first protective layer laminated on one side of the polarizer, and a second laminated on the other side of the polarizer. A pressure-sensitive adhesive layer-attached polarizing plate comprising a protective layer and a pressure-sensitive adhesive layer laminated on the surface opposite to the surface on the polarizer side in the second protective layer, wherein the pressure-sensitive adhesive layer is The monomer unit constituting the polymer contains an alicyclic structure-containing monomer (a1), an aromatic ring-containing monomer (a2), an oxyalkylene group-containing monomer (a3), and a hydroxyl group-containing monomer (a4), and has a hydroxyl value. (Meth) acrylic acid ester copolymer (A) having an acid value of 5 mgKOH / g or less, an acid value of 5 mgKOH / g or less, and a weight average molecular weight of 1.3 million or more and 3 million or less, and isocyanate Cross-linking agent (B The second protective layer is made of a cycloolefin-based resin or triacetyl cellulose, and is made of a pressure-sensitive adhesive having a gel fraction of 60% or more and 89% or less. The thickness of the polarizer is 1 μm or more and 20 μm or less, the thickness of the second protective layer is 5 μm or more and 30 μm or less, and the thickness of the second protective layer with respect to the thickness of the polarizer Provided is a polarizing plate with a pressure-sensitive adhesive layer, characterized in that the thickness ratio is 1.0 or more and 5.0 or less (Invention 1).

  According to the polarizing plate with an adhesive layer according to the invention (Invention 1), the polarizing plate (first protective layer / polarizer / second protective layer) is made thinner than the conventional product. In spite of this, when the polarizing plate with the pressure-sensitive adhesive layer is applied to a display panel, the polarizing plate with the pressure-sensitive adhesive layer is excellent in durability, the display panel is hardly warped, and heat unevenness is hardly caused. Has excellent antistatic properties.

  In the said invention (invention 1), it is preferable that the said adhesive composition further contains an antistatic agent (C) (invention 2).

  In the said invention (invention 2), it is preferable that the said antistatic agent (C) is a nitrogen-containing onium salt (invention 3).

  In the said invention (invention 1-3), the thickness of the said 1st protective layer is 5 micrometers or more and 120 micrometers or less, The ratio of the thickness of the said 1st protective layer with respect to the thickness of the said polarizer, It is preferably 1.0 or more and 6.0 or less (Invention 4).

  In the said invention (invention 1-4), it is preferable that a said 1st protective layer consists of a triacetyl cellulose (invention 5).

  In the said invention (invention 1-5), it is preferable that the alicyclic structure in the said alicyclic structure containing monomer (a1) is a polycyclic alicyclic structure (invention 6).

  In the said invention (invention 1-6), it is preferable that the said adhesive composition further contains an epoxy-group-containing silane coupling agent (D1) (invention 7).

  In the said invention (invention 1-7), it is preferable that the said adhesive composition further contains a mercapto group containing silane coupling agent (D2) (invention 8).

  In the said invention (invention 1-8), it is preferable that the said isocyanate type crosslinking agent (B) is a compound which has an aromatic ring (invention 9).

  According to the polarizing plate with the pressure-sensitive adhesive layer according to the present invention, even if the polarizing plate is a thin film, the durability is excellent, the display panel is hardly warped, heat unevenness is hardly generated, and antistatic properties are also excellent.

It is sectional drawing of the polarizing plate with an adhesive layer which concerns on one Embodiment of this invention. It is a figure (color) which shows the evaluation criteria of the heat-resistant unevenness test (visual observation) in a polarizing plate with an adhesive layer.

Hereinafter, embodiments of the present invention will be described.
As shown in FIG. 1, a polarizing plate 10 with an adhesive layer according to this embodiment includes a polarizer 21 and a first protective layer 22 laminated on one surface side (upper side in FIG. 1) of the polarizer 21. And a second protective layer 23 laminated on the other surface side (lower side in FIG. 1) of the polarizer 21 and a surface side opposite to the surface of the second protective layer 23 on the polarizer 21 side (see FIG. 1 and the adhesive layer 1 laminated on the lower side). In the present embodiment, the laminate of the first protective layer 22, the polarizer 21 and the second protective layer 23 constitutes the polarizing plate 2. Although not shown, a release sheet may be laminated on the surface of the pressure-sensitive adhesive layer 1 opposite to the side of the polarizing plate 2 until the polarizing plate 10 with the pressure-sensitive adhesive layer is used.

  The pressure-sensitive adhesive layer 1 includes, as monomer units constituting the polymer, an alicyclic structure-containing monomer (a1), an aromatic ring-containing monomer (a2), an oxyalkylene group-containing monomer (a3), and a hydroxyl group-containing monomer (a4). (Meth) acrylic acid ester copolymer having a hydroxyl value of 5 mgKOH / g or more and 20 mgKOH / g or less, an acid value of 5 mgKOH / g or less, and a weight average molecular weight of 1.3 million or more and 3 million or less. The gel fraction obtained from the adhesive composition (hereinafter sometimes referred to as “adhesive composition P”) containing the coalescence (A) and the isocyanate-based crosslinking agent (B) is 60% or more, 89 % Of the pressure-sensitive adhesive. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

  The second protective layer 23 is made of a cycloolefin resin or triacetyl cellulose, the thickness of the polarizer 21 is 1 μm or more and 20 μm or less, and the thickness of the second protective layer 23 is 5 μm. As described above, the thickness is 30 μm or less, and the ratio of the thickness of the second protective layer 23 to the thickness of the polarizer 21 is 1.0 or more and 5.0 or less.

  In the polarizing plate 10 with the pressure-sensitive adhesive layer satisfying the above requirements, the polarizing plate 2 is made thinner than the conventional product, and the display panel can be made thin. Nevertheless, when the pressure-sensitive adhesive layer-attached polarizing plate 10 is applied to a display panel, the pressure-sensitive adhesive layer-attached polarizing plate 10 is excellent in durability, under high temperature conditions, wet heat conditions or under heat shock. However, the occurrence of lifting and peeling is suppressed. In addition, the display panel using the polarizing plate 10 with the pressure-sensitive adhesive layer hardly warps even under high temperature conditions, hardly causes heat unevenness, and has excellent antistatic properties.

1. Adhesive Layer (1) Physical Properties As described above, the hydroxyl value of the (meth) acrylate copolymer (A) contained in the adhesive composition P for constituting the adhesive layer 1 in this embodiment is 5 mgKOH / g or more and 20 mgKOH / g or less, an acid value of 5 mgKOH / g or less, and a weight average molecular weight of 1.3 million or more and 3 million or less. Moreover, the gel fraction of the adhesive obtained from the adhesive composition P is 60% or more and 89% or less.

  When the hydroxyl value of the (meth) acrylic acid ester copolymer (A) is less than 5 mgKOH / g, there are too few crosslinking points, the cohesive force is lowered, and the resulting pressure-sensitive adhesive does not exhibit excellent durability. Moreover, when the hydroxyl value of the (meth) acrylic acid ester copolymer (A) exceeds 20 mgKOH / g, there are too many cross-linking points, the resulting pressure-sensitive adhesive becomes inflexible, and the stress relaxation properties are reduced. The display panel warps or heat unevenness occurs under high temperature conditions.

  From the above viewpoint, the lower limit of the hydroxyl value of the (meth) acrylic acid ester copolymer (A) is preferably 8 mgKOH / g or more, and particularly preferably 10 mgKOH / g or more. The upper limit of the hydroxyl value of the (meth) acrylic acid ester copolymer (A) is preferably 18 mgKOH / g or less, and particularly preferably 16 mgKOH / g or less.

  On the other hand, if the acid value of the (meth) acrylic acid ester copolymer (A) is 5 mgKOH / g or less, the sticking target of the pressure-sensitive adhesive is a transparent material such as a tin-doped indium oxide (ITO) that causes problems due to acid. Even in the case of a conductive film, a metal film, or the like, those problems due to acid can be suppressed. In particular, when the object to be pasted is a transparent conductive film, it is possible to suppress corrosion of the transparent conductive film or change of the resistance value of the transparent conductive film.

  From the above viewpoint, the upper limit of the acid value of the (meth) acrylic acid ester copolymer (A) is preferably 2 mgKOH / g or less, and particularly preferably 1 mgKOH / g or less. In addition, since the lower limit of the acid value of (meth) acrylic acid ester copolymer (A) is so preferable that it is small, it is especially preferable that it is 0 mgKOH / g.

  Here, the hydroxyl value and acid value in the present specification are basically theoretical values derived from the blending ratio of the (meth) acrylic acid ester copolymer (A), and when the theoretical values cannot be derived, The measured value is based on JIS K0070.

  When the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is less than 1.3 million, the durability of the pressure-sensitive adhesive layer 1 in this embodiment is deteriorated. Moreover, when the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) exceeds 3 million, the stress relaxation property of the pressure-sensitive adhesive layer 1 in the present embodiment is lowered, and the display panel is warped under high temperature conditions. Or heat unevenness occurs.

  From the above viewpoint, the lower limit of the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is preferably 1.5 million or more, and particularly preferably 1.6 million or more. The upper limit of the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is preferably 2.5 million or less, particularly preferably 1.9 million or less.

  Here, the weight average molecular weight in this specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

  Moreover, the durability of the said adhesive deteriorates that the gel fraction of the adhesive which comprises the adhesive layer 1 is less than 60%. On the other hand, when the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 1 exceeds 89%, the stress relaxation property of the pressure-sensitive adhesive layer 1 is lowered, and the display panel is warped or heat unevenness occurs under high temperature conditions. To do.

  From the above viewpoint, the lower limit value of the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 1 is preferably 65% or more, and particularly preferably 70% or more. Moreover, it is preferable that the upper limit of the gel fraction of the adhesive which comprises the adhesive layer 1 is 85% or less, and it is especially preferable that it is 78% or less. In addition, the measuring method of the gel fraction of an adhesive is as showing to the test example mentioned later.

  The pressure-sensitive adhesive layer 1 in the present embodiment preferably has a haze value (value measured according to JIS K7136: 2000) of 2% or less, particularly preferably 1% or less. When the haze value is 2% or less, the transparency is very high, which is suitable for optical applications.

(2) (Meth) acrylic acid ester copolymer (A)
The (meth) acrylic acid ester copolymer (A) in the present embodiment includes an alicyclic structure-containing monomer (a1), an aromatic ring-containing monomer (a2), and an oxyalkylene group-containing monomer unit constituting the polymer. It contains a monomer (a3) and a hydroxyl group-containing monomer (a4). Among these monomers, the pressure-sensitive adhesive obtained by combining the alicyclic structure-containing monomer (a1) and the aromatic ring-containing monomer (a2) can have both appropriate cohesive force and stress relaxation properties. At the same time, since the adhesiveness to the polarizing plate and the transparent conductive film is increased, when used in a display panel, excellent durability, warpage suppression and heat resistance unevenness can be exhibited.

  Moreover, the (meth) acrylic acid ester copolymer (A) contains an oxyalkylene group-containing monomer (a3) as a monomer unit constituting the polymer, whereby a (meth) acrylic acid ester copolymer ( A) As a result, the hydrophilicity of the resulting adhesive is improved, and the adhesive layer 1 exhibits excellent antistatic properties. Therefore, when peeling a peeling sheet from the adhesive layer 1 of the polarizing plate 10 with an adhesive layer which concerns on this embodiment, it becomes difficult to generate static electricity. Therefore, for example, when the polarizing plate 10 with the pressure-sensitive adhesive layer from which the release sheet has been peeled is bonded to the liquid crystal cell, it is possible to prevent the orientation of the liquid crystal molecules from being disturbed. Suction can also be suppressed.

  Here, the antistatic agent (C), which will be described later, is generally a low molecular weight component. If the amount of the antistatic agent (C) is too large, the cohesive force of the resulting pressure-sensitive adhesive tends to decrease and the durability tends to deteriorate. . In order to improve the cohesive strength of the pressure-sensitive adhesive, it is sufficient to increase the amount of the crosslinking agent (B) added. However, the pressure-sensitive adhesive layer becomes too hard and the resulting display panel is likely to warp. There is. Moreover, when there is too much addition amount of antistatic agent (C), there exists a possibility that the adhesiveness with respect to the cycloolefin type resin or triacetylcellulose (2nd protective layer) of an adhesive layer may fall. On the other hand, the (meth) acrylic acid ester copolymer (A) contains an oxyalkylene group-containing monomer (a3) as a monomer unit constituting the polymer, thereby adding an antistatic agent (C). By reducing the amount, the above problems can be prevented, and excellent antistatic properties can be obtained.

  The (meth) acrylic acid ester copolymer (A) includes the above alicyclic structure-containing monomer (a1), aromatic ring-containing monomer (a2), oxyalkylene group-containing monomer ( In addition to a3) and the hydroxyl group-containing monomer (a4), it is preferable to contain a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms. Moreover, you may contain another monomer if desired.

  The (meth) acrylic acid ester copolymer (A) contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Can be expressed. Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferable, and (meth) acrylic acid n-butyl or (meth) acrylic acid 2-ethylhexyl is particularly preferable. . In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester copolymer (A) may contain 0% by mass or more of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Preferably, from the viewpoint of imparting tackiness by the monomer unit, the content is preferably 30% by mass or more, and more preferably 45% by mass or more. Moreover, it is preferable to contain 90 mass% or less of the (meth) acrylic acid alkyl ester whose carbon number of an alkyl group is 1-20, It is preferable to contain especially 80 mass% or less, Furthermore, 70 mass% or less is contained. Is preferred. By setting the content of the (meth) acrylic acid alkyl ester to 90% by mass or less, a desired amount of other monomer components can be introduced into the (meth) acrylic acid ester copolymer (A).

  The alicyclic carbocyclic ring in the alicyclic structure-containing monomer (a1) may have a saturated structure or may have an unsaturated bond in part. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. From the viewpoint of making the distance between the obtained (meth) acrylic acid ester copolymer (A) appropriate and imparting stress relaxation to the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure ( A polycyclic structure). Furthermore, considering the compatibility between the (meth) acrylic acid ester copolymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. In addition, from the viewpoint of imparting stress relaxation properties as described above, the carbon number of the alicyclic structure (refers to the total number of carbon atoms of the portion forming the ring, and when multiple rings exist independently) , Which means the total number of carbon atoms) is usually preferably 5 or more, and particularly preferably 7 or more. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but it is preferably 15 or less and particularly preferably 10 or less from the viewpoint of compatibility as described above.

  Examples of the alicyclic structure include a cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.) , Cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, cubane skeleton, basketn skeleton, Hausan skeleton, spiro skeleton, etc. are included, and among them, more excellent durability is exhibited. Those containing a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10), adamantane skeleton (carbon number of alicyclic structure: 10) or isobornyl skeleton (carbon number of alicyclic structure: 7) are particularly preferable. Contains isobornyl skeleton Preference is.

  The alicyclic structure-containing monomer (a1) is preferably a (meth) acrylic acid ester monomer containing the skeleton, specifically, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (Meth) acrylic acid adamantyl, (meth) acrylic acid isobornyl, (meth) acrylic acid dicyclopentenyl, (meth) acrylic acid dicyclopentenyloxyethyl, etc. are mentioned, among them, more excellent durability, ( Dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate or isobornyl (meth) acrylate is preferred, and isobornyl (meth) acrylate is particularly preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester copolymer (A) is an alicyclic monomer unit that constitutes the polymer from the viewpoint that the resulting pressure-sensitive adhesive exhibits excellent durability, warpage suppression, and heat unevenness. The structure-containing monomer (a1) is preferably contained in an amount of 1% by mass to 20% by mass. Furthermore, in addition to the above viewpoints, from the viewpoint that the resulting pressure-sensitive adhesive exhibits excellent reworkability, it is more preferable to contain 2% by mass or more of the alicyclic structure-containing monomer (a1), and 3% by mass or more. It is particularly preferred. From the same viewpoint, the alicyclic structure-containing monomer (a1) is more preferably contained in an amount of 15% by mass or less, and particularly preferably 9% by mass or less.

  As the aromatic ring-containing monomer (a2), a (meth) acrylic acid ester having an aromatic ring is preferable. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a biphenyl ring, and a fluorene ring, and among them, a benzene ring is preferable.

  Examples of the aromatic ring-containing monomer (a2) include phenyl (meth) acrylate, 2-phenylethyl (meth) acrylate, benzyl (meth) acrylate, naphthyl (meth) acrylate, and phenoxyethyl (meth) acrylate. , Phenoxybutyl (meth) acrylate, ethoxylated o-phenylphenol acrylate, phenoxydiethylene glycol (meth) acrylate, and the like. Among them, 2-phenylethyl (meth) acrylate is preferable from the viewpoint of improving cohesion. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester copolymer (A) preferably contains 1% by mass or more, particularly 3% by mass or more of the aromatic ring-containing monomer (a2) as a monomer unit constituting the polymer. It is preferable to contain 12% by mass or more. Further, the aromatic ring-containing monomer (a2) is preferably contained in an amount of 30% by mass or less, particularly preferably 25% by mass or less, and more preferably 22% by mass or less. When the content of the aromatic ring-containing monomer (a2) is within the above range, the obtained pressure-sensitive adhesive can exhibit excellent durability, warpage suppression, and heat unevenness.

  The oxyalkylene group-containing monomer (a3) refers to a monomer having at least one alkylene oxide unit and not containing an alicyclic structure and an aromatic ring. Examples of the oxyalkylene group-containing monomer (a3) include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, and (meth) acrylic acid 3- Preferable examples include (meth) acrylic acid alkoxyesters such as methoxypropyl, 2-methoxybutyl (meth) acrylate, and 4-methoxybutyl (meth) acrylate. Furthermore, the (meth) acrylic-acid alkoxyester which has polyalkylene glycol chains, such as a polyethyleneglycol chain of a terminal alkoxy group, or a polypropylene glycol chain, can also be mentioned preferably. Among these, 2-methoxyethyl (meth) acrylate capable of effectively exhibiting the action of the alicyclic structure-containing monomer (a1) and the aromatic ring-containing monomer (a2), particularly durability, is particularly preferable. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester copolymer (A) preferably contains 0.5% by mass or more of the oxyalkylene group-containing monomer (a3) as a monomer unit constituting the polymer, particularly 1% by mass or more. It is preferably contained, more preferably 5% by mass or more, and most preferably 12% by mass or more. The oxyalkylene group-containing monomer (a3) is preferably contained in an amount of 90% by mass or less, particularly preferably 50% by mass or less, and further preferably 25% by mass or less. When the content of the oxyalkylene group-containing monomer (a3) is within the above range, the resulting pressure-sensitive adhesive exhibits excellent antistatic properties while maintaining excellent durability, warpage suppression and heat resistance unevenness. can do.

  The (meth) acrylic acid ester copolymer (A) contains a hydroxyl group-containing monomer (a4) as a monomer unit constituting the polymer. The hydroxyl group is highly reactive with the isocyanate group of the isocyanate-based crosslinking agent (B), and the (meth) acrylic acid ester copolymer (A) is crosslinked by the isocyanate-based crosslinking agent (B) by their reaction. Due to this crosslinked structure, the resulting pressure-sensitive adhesive is excellent in durability.

  Examples of the hydroxyl group-containing monomer (a4) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. , (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 3-hydroxybutyl, (meth) acrylic acid 4-hydroxybutyl, etc., among others, the reactivity with the isocyanate-based crosslinking agent (B) To 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is preferred, and 2-hydroxyethyl (meth) acrylate is particularly preferred. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester copolymer (A) preferably contains 0.5% by mass or more, particularly 1% by mass or more, of the hydroxyl group-containing monomer (a4) as a monomer unit constituting the polymer. It is preferable to contain 2% by mass or more. Further, the hydroxyl group-containing monomer (a4) is preferably contained in an amount of 10% by mass or less, particularly preferably 5% by mass or less, and more preferably 4% by mass or less. When the content of the hydroxyl group-containing monomer (a4) is in the above range, the hydroxyl value of the (meth) acrylic acid ester copolymer (A) easily enters the above range, and has excellent durability and warpage suppression. In addition, the heat unevenness can be effectively exhibited.

  The (meth) acrylic acid ester copolymer (A) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer so that the acid value is in the above-described range. The content is preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

  The (meth) acrylic acid ester copolymer (A) may contain a monomer other than the above-described monomers as a monomer unit constituting the polymer. The other monomer includes a functional group having reactivity with the isocyanate-based crosslinking agent (B) in order not to hinder the reaction between the hydroxyl group of the hydroxyl group-containing monomer (a4) and the isocyanate-based crosslinking agent (B). No monomer is preferred.

  Examples of such other monomers include non-crosslinkable acrylamides such as acrylamide and methacrylamide, non-crosslinks such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate. (Meth) acrylic acid ester having a functional tertiary amino group, vinyl acetate and the like. These may be used alone or in combination of two or more.

  The polymerization aspect of the (meth) acrylic acid ester copolymer (A) may be a random copolymer or a block copolymer.

  Here, in the adhesive composition P, the (meth) acrylic acid ester copolymer (A) may be used alone or in combination of two or more. The adhesive composition P further includes a (meth) acrylic acid ester polymer that does not contain the alicyclic structure-containing monomer (a1), aromatic ring-containing monomer (a2), or hydroxyl group-containing monomer (a4) as a constituent monomer unit. You may contain.

(3) Isocyanate-based crosslinking agent (B)
The isocyanate-based crosslinking agent (B) has an advantage of excellent reactivity with the hydroxyl group (derived from the hydroxyl group-containing monomer (a4)) of the (meth) acrylic acid ester copolymer (A).

  The isocyanate-based crosslinking agent (B) contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, etc. In addition to these biuret bodies, isocyanurate bodies, and adduct bodies that are reaction products with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, castor oil, etc. And may be referred to as “denatured”). Among these, from the viewpoint of durability of the obtained pressure-sensitive adhesive, a compound having an aromatic ring, that is, an aromatic polyisocyanate or a modified product thereof is preferable, and an organic group (for example, an alkylene chain is preferably included in the aromatic ring, 1 to 4 alkylene chains are particularly preferred.) Polyisocyanates having an isocyanate group bonded via each other or a modified product thereof are particularly preferred. Specifically, xylylene diisocyanate or a modified product thereof is more preferable, and trimethylolpropane-modified xylylene diisocyanate is most preferable. The said isocyanate type crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The content of the isocyanate-based crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). In particular, it is preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more. Further, the content is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and further preferably 0.4 parts by mass or less. When the content of the isocyanate-based crosslinking agent (B) is in the above range, the pressure-sensitive adhesive is easy to enter the above-described range, and a pressure-sensitive adhesive excellent in durability, warpage suppression and heat resistance unevenness is obtained. It becomes easy.

(4) Antistatic agent (C)
It is preferable that the adhesive composition P further contains an antistatic agent (C). When the antistatic agent (C) is contained, the resulting adhesive (adhesive layer) is charged by the interaction with the oxyalkylene group-containing monomer (a3) constituting the (meth) acrylic acid ester copolymer (A). The prevention is more excellent.

  The antistatic agent (C) is not particularly limited as long as it can impart antistatic properties to the resulting pressure-sensitive adhesive, and examples thereof include ionic compounds and nonionic compounds, among which ionic compounds are preferred. . The ionic compound may be a liquid or a solid at room temperature, but is preferably a solid at room temperature from the viewpoint of easily exhibiting stable antistatic properties even when exposed to durability conditions. . Here, the ionic compound in this specification refers to a compound in which a cation and an anion are combined mainly by electrostatic attraction.

  As the ionic compound, a nitrogen-containing onium salt, a sulfur-containing onium salt, a phosphorus-containing onium salt, an alkali metal salt or an alkaline earth metal salt is preferable, and from the viewpoint that the obtained pressure-sensitive adhesive is excellent in durability, a nitrogen-containing onium salt or Alkali metal salts are preferred, and nitrogen-containing onium salts are more preferred. The nitrogen-containing onium salt is preferably an ionic compound composed of a nitrogen-containing heterocyclic cation and its counter anion.

  As the nitrogen-containing heterocyclic skeleton of the nitrogen-containing heterocyclic cation, a pyridine ring, a pyrimidine ring, an imidazole ring, a triazole ring, an indole ring and the like are preferable, and a pyridine ring is particularly preferable. The cation of the alkali metal salt is preferably lithium ion, potassium ion or sodium ion, and particularly preferably lithium ion or potassium ion.

  On the other hand, the anion constituting the ionic compound is preferably a halogenated phosphate anion or a sulfonylimide anion. Preferred examples of the halogenated phosphate anion include hexafluorophosphate. Further, preferred examples of the sulfonylimide anion include bis (fluoroalkylsulfonyl) imide and bis (fluorosulfonyl) imide.

  Specific examples of the antistatic agent (C) include N-butyl-4-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, and N-octyl-4. -Methylpyridinium hexafluorophosphate, N-dodecylpyridinium hexafluorophosphate, N-tetradecylpyridinium hexafluorophosphate, N-hexadecylpyridinium hexafluorophosphate, N-dodecyl-4-methylpyridinium hexafluorophosphate, N-tetradecyl-4 -Methylpyridinium hexafluorophosphate, N-hexadecyl-4-methylpyridinium hexafluorophosphate, N-decylpyridinium Su (fluorosulfonyl) imide, 1-ethylpyridinium bis (fluorosulfonyl) imide, 1-butylpyridinium bis (fluorosulfonyl) imide, 1-hexylpyridinium bis (fluorosulfonyl) imide, 1-butyl-3-methylpyridinium bis (Fluorosulfonyl) imide, 1-butyl-4-methylpyridinium bis (fluorosulfonyl) imide, 1-hexyl-3-methylpyridinium bis (fluorosulfonyl) imide, 1-butyl-3,4-dimethylpyridinium bis (fluoro Sulfonyl) imide, potassium bis (fluorosulfonyl) imide, lithium bis (fluorosulfonyl) imide, potassium bis (fluoromethanesulfonyl) imide, lithium bis (fluoromethanesulfonyl) imide, etc. It is below. Among these, from the viewpoint of compatibility with the (meth) acrylic acid ester copolymer (A), N-butyl-4-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N- Octyl-4-methylpyridinium hexafluorophosphate, N-decylpyridinium bis (fluorosulfonyl) imide, or potassium bis (fluorosulfonyl) imide is preferred. The above antistatic agent (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the antistatic agent (C) in the adhesive composition P is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A), in particular. The amount is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and most preferably 3.5 parts by mass or more. In addition, the content is preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and further preferably 5 parts by mass or less. When the content of the antistatic agent (C) is within the above range, it is possible to effectively exhibit antistatic properties and prevent deterioration of physical properties such as optical properties, durability, and warpage suppression. Can do. In the pressure-sensitive adhesive composition P, the (meth) acrylic acid ester copolymer (A) contains an oxyalkylene group-containing monomer (a3) as a monomer unit constituting the polymer, thereby providing an antistatic agent. Even when the content of (C) is relatively small as described above, the obtained pressure-sensitive adhesive exhibits excellent antistatic properties, and is compatible with cycloolefin-based resins or triacetyl cellulose (second protective layer). Adhesion is high, and durability and warpage suppression are excellent.

(5) Silane coupling agent (D)
The pressure-sensitive adhesive composition P preferably further contains a silane coupling agent (D). From the viewpoint of imparting excellent durability to the resulting pressure-sensitive adhesive, the epoxy group-containing silane coupling agent (D1) and / or Alternatively, it preferably contains a mercapto group-containing silane coupling agent (D2), and more preferably contains both an epoxy group-containing silane coupling agent (D1) and a mercapto group-containing silane coupling agent (D2).

  The epoxy group-containing silane coupling agent (D1) is an organosilicon compound having at least one epoxy group (an organic group containing an epoxy group) and at least one alkoxysilyl group in the molecule, Those having good compatibility and having light transmission properties, for example, substantially transparent materials are preferred.

  Specific examples of the epoxy group-containing silane coupling agent (D1) include 3-glycidoxypropyltrialkoxysilane such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane, and 3-glycidyl. 3-glycidoxypropylalkyldialkoxysilanes such as sidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, methyltri (glycidyl) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane 2- (3,4-epoxycyclohexyl) ethyltrialkoxysilane such as 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane. Among these, from the viewpoint of further improving durability, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ) Ethyltrimethoxysilane is preferred, and 3-glycidoxypropyltrimethoxysilane is particularly preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The mercapto group-containing silane coupling agent (D2) is an organosilicon compound having at least one mercapto group (an organic group containing a mercapto group) and at least one alkoxysilyl group in the molecule, Those having good compatibility and having light transmission properties, for example, substantially transparent materials are preferred.

  Specific examples of the mercapto group-containing silane coupling agent (D2) include mercapto group-containing low molecular weight silane couplings such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. Agents: Mercapto group-containing silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyl Examples include mercapto group-containing oligomer type silane coupling agents such as co-condensates with alkyl group-containing silane compounds such as trimethoxysilane. Among these, from the viewpoint of achieving both durability and reworkability, a mercapto group-containing oligomer type silane coupling agent is preferable, and a cocondensate of a mercapto group-containing silane compound and an alkyl group-containing silane compound is particularly preferable. A cocondensate of mercaptopropyltrimethoxysilane and methyltriethoxysilane is preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  As the silane coupling agent (D), in addition to the epoxy group-containing silane coupling agent (D1) and the mercapto group-containing silane coupling agent (D2), for example, an acryloyl-based silane coupling agent, Hydroxyl silane coupling agents, carboxyl group silane coupling agents, amino group silane coupling agents, amide group silane coupling agents, isocyanate group silane coupling agents, and the like may be used in combination.

  The total content of the silane coupling agent (D) in the adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). In particular, the amount is preferably 0.1 parts by mass or more, and more preferably 0.2 parts by mass or more. Further, the total content is preferably 5 parts by mass or less, particularly preferably 2 parts by mass or less, and further preferably 1 part by mass or less.

  The content of the epoxy group-containing silane coupling agent (D1) in the adhesive composition P is 0.005 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). Preferably, it is preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more. In addition, the content is preferably 2.5 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.5 parts by mass or less. On the other hand, the content of the mercapto group-containing silane coupling agent (D2) in the adhesive composition P is 0.005 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). Preferably, it is preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more. In addition, the content is preferably 2.5 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.5 parts by mass or less.

(6) Various additives For the adhesive composition P, various additives usually used for acrylic pressure-sensitive adhesives, for example, dispersants (for example, alkylene glycol dialkyl ethers), tackifiers, and antioxidants are optionally used. An agent, an ultraviolet absorber, a light stabilizer, a softener, a filler, a refractive index adjusting agent, and the like can be added. The pressure-sensitive adhesive composition P represents a mixture of various components that remain in the pressure-sensitive adhesive layer or in a reacted state, and is a component that is removed in a drying step or the like, for example, polymerization described later. Solvents and dilution solvents are not included in the adhesive composition P.

(7) Production of Adhesive Composition / Adhesive Adhesive composition P produced (meth) acrylic acid ester copolymer (A) and obtained (meth) acrylic acid ester copolymer (A). And an isocyanate-based crosslinking agent (B) and, if desired, an antistatic agent (C), a silane coupling agent (D), an additive and the like can be mixed.

  The (meth) acrylic acid ester copolymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  When the (meth) acrylic acid ester copolymer (A) is obtained, the solution of the (meth) acrylic acid ester copolymer (A) is added with an isocyanate-based crosslinking agent (B) and, optionally, an antistatic agent (C). Then, a silane coupling agent (D), an additive, a diluting solvent, and the like are added and mixed well to obtain an adhesive composition P (coating solution) diluted with a solvent.

  Examples of the dilution solvent for diluting the adhesive composition P to form a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, methylene chloride, ethylene chloride, and the like. Halogenated hydrocarbons, methanol, ethanol, propanol, butanol, alcohols such as 1-methoxy-2-propanol, acetone, methyl ethyl ketone, ketones such as 2-pentanone, isophorone, cyclohexanone, esters such as ethyl acetate and butyl acetate, ethyl A cellosolv solvent such as cellosolve is used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-40 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester copolymer (A) as a dilution solvent.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 1 in the present embodiment is obtained from the pressure-sensitive adhesive composition P. Specifically, the pressure-sensitive adhesive composition P is cross-linked. The pressure-sensitive adhesive composition P can be crosslinked by heat treatment. In addition, this heat processing can also serve as the drying process at the time of volatilizing the dilution solvent of the adhesive composition P, etc.

  When performing heat processing, it is preferable that heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. The heating time is preferably 30 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). When the curing period is necessary, after the curing period has elapsed, when the curing period is unnecessary, the pressure-sensitive adhesive layer 1 having predetermined physical properties is formed after the heat treatment.

  By the above heat treatment (and curing), the (meth) acrylic acid ester copolymer (A) is crosslinked by the isocyanate-based crosslinking agent (B) to form a three-dimensional network structure.

(8) Thickness of the pressure-sensitive adhesive layer The thickness of the pressure-sensitive adhesive layer 1 is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. In addition, the thickness is preferably 100 μm or less, more preferably 60 μm or less, and in particular, from the viewpoint of exhibiting excellent durability, warpage suppression, and heat resistance unevenness by the pressure-sensitive adhesive layer 1. It is preferably 50 μm or less, and more preferably 30 μm or less.

2. Polarizing Plate (1) Configuration As shown in FIG. 1, the polarizing plate 2 in the present embodiment has a configuration in which a first protective layer 22, a polarizer 21, and a second protective layer 23 are laminated in that order. By having such a configuration, the polarizing plate 2 has excellent mechanical strength and chemical resistance. Although not shown, an adhesive layer may be interposed between the polarizer 21 and the first protective layer 22 and / or between the polarizer 21 and the second protective layer 23.

(2) Polarizer The polarizer 21 is preferably made of a polyvinyl alcohol-based resin film on which a dichroic dye is adsorbed and oriented.

  The polyvinyl alcohol resin constituting the polarizer 21 can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids.

  The degree of saponification of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

  The polarizer 21 as described above includes a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, and adsorbing the dichroic dye, It is preferably manufactured by passing the adsorbed polyvinyl alcohol resin film with a boric acid aqueous solution.

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural stages. For uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched or uniaxially stretched using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 4 to 8 times.

  In order to dye the polyvinyl alcohol resin film with the dichroic dye, for example, the polyvinyl alcohol resin film may be immersed in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol resin film by dipping it in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by mass per 100 parts by mass of water, and the content of potassium iodide is usually about 0.5 to 10 parts by mass per 100 parts by mass of water. It is. The temperature of this aqueous solution is usually about 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 30 to 300 seconds.

  The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually about 2 to 15 parts by mass, preferably about 5 to 12 parts by mass per 100 parts by mass of water. When iodine is used as the dichroic dye, the aqueous boric acid solution preferably contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is usually about 2 to 20 parts by mass, preferably 5 to 15 parts by mass per 100 parts by mass of water. The immersion time in the boric acid aqueous solution is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. After washing with water, a drying process is performed to obtain the polarizer 21. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 2 to 120 seconds. The drying process performed thereafter is usually performed using a hot air dryer or a far infrared heater. The drying temperature is usually 40 to 100 ° C. Moreover, the time of a drying process is about 120 to 600 seconds normally.

  The thickness of the polarizer 21 in the present embodiment is 1 μm or more and 20 μm or less, and is thinner than a normal polarizer. If the thickness of the polarizer 21 is less than 1 μm, sufficient polarization performance cannot be exhibited. On the other hand, when the thickness of the polarizer 21 exceeds 20 μm, the warp and the heat unevenness are generated in the display panel, exceeding the warp suppressing effect / heat resistance unevenness effect of the pressure-sensitive adhesive layer 1. From this viewpoint, the thickness of the polarizer 21 is preferably 3 μm or more, and particularly preferably 5 μm or more. Further, the thickness of the polarizer 21 is preferably 18 μm or less, and particularly preferably 15 μm or less.

(3) Protective layer The first protective layer 22 is preferably made of a transparent resin film. The transparent resin film constituting the first protective layer 22 may be either an unstretched film or a uniaxially or biaxially stretched film.

  The main component of the transparent resin film is preferably at least one resin selected from the group consisting of polyester resins, polycarbonate resins, acrylic resins, amorphous polyolefin resins, and cellulose resins.

  The amorphous polyolefin resin used for the first protective layer 22 is preferably a cycloolefin resin. Examples of cycloolefin resins include resins obtained by performing ring-opening metathesis polymerization using cyclopentadiene and olefins by Diels-Alder reaction or a derivative thereof as a monomer, followed by hydrogenation; dicyclopentadiene and Resins obtained by performing ring-opening metathesis polymerization from olefins or methacrylates with Diels-Alder reaction obtained by Diels-Alder reaction as a monomer, followed by hydrogenation; norbornene, tetracyclododecene and the like Resins obtained by conducting ring-opening metathesis copolymerization in the same manner using two or more selected from the above derivatives and other cyclic polyolefin monomers, followed by hydrogenation; norbornene, tetra Kurododesen or their derivatives, resins obtained by addition copolymerization of aromatic compounds and the like having a vinyl group. Examples of commercially available amorphous polyolefin resins include “Arton” from JSR Corporation, “ZEONEX” and “ZEONOR” from ZEON Corporation, “APO” and “APO” from Mitsui Chemicals, Inc. Appel ”. When the amorphous polyolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used for forming the film.

  The cellulose resin is a resin in which at least a part of hydroxyl groups in cellulose is acetate esterified, and a mixed ester in which part is acetated and partly esterified with another acid. Good. The cellulose resin is preferably a cellulose ester resin, and more preferably an acetyl cellulose resin. Specific examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate. Commercially available films made of such acetylcellulose-based resins include, for example, “Fujitac TD80”, “Fujitac TD80UF” and “Fujitac TD80UZ” manufactured by Fuji Film Co., Ltd., and “KC8UX2M” manufactured by Konica Minolta Opto Co., Ltd. "," KC2UA "," KC8UY "and the like.

  A cellulose resin film provided with an optical compensation function can also be used. As such an optical compensation film, for example, a film in which a compound having a retardation adjusting function is contained in a cellulose resin, a film in which a compound having a retardation adjusting function is applied to the surface of the cellulose resin, a cellulose resin is uniaxial or biaxial. Examples thereof include a film obtained by stretching on a shaft. Examples of commercially available optical compensation films of cellulose resin include “Wide View Film WV BZ 438” and “Wide View Film WV EA” manufactured by Fuji Film Co., Ltd., “Konica Minolta Opto Co., Ltd.” KC4FR-1 "and" KC4HR-1 ".

  Among the above, the first protective layer 22 is preferably made of a cellulose-based resin, more preferably made of a cellulose ester-based resin, particularly preferably made of an acetylcellulose-based resin, and further preferably made of triacetylcellulose. preferable. When the first protective layer 22 is made of triacetyl cellulose, the obtained display panel is less likely to warp under high temperature conditions, and further, heat unevenness is less likely to occur.

  The thickness of the first protective layer 22 is preferably 5 μm or more, and more preferably 10 μm or more. When the thickness of the first protective layer 22 is 5 μm or more, the polarizer 21 can be sufficiently protected. The thickness of the first protective layer 22 is preferably 120 μm or less, particularly preferably 85 μm or less, and further preferably 30 μm or less. When the thickness of the first protective layer 22 is 120 μm or less, the warp suppressing effect and the heat resistance unevenness effect by the pressure-sensitive adhesive layer 1 are sufficiently exhibited.

  Furthermore, the ratio of the thickness of the first protective layer 22 to the thickness of the polarizer 21 is preferably 1.0 or more, particularly preferably 1.4 or more, and more preferably 1.6 or more. Preferably there is. The ratio is preferably 6.0 or less, particularly preferably 4.0 or less, and further preferably 3.8 or less. When this ratio is within the above range, the warp suppressing effect and the heat resistance unevenness effect by the pressure-sensitive adhesive layer 1 are sufficiently exhibited.

  On the other hand, the second protective layer 23 in the present embodiment is made of a cycloolefin resin or triacetyl cellulose, and is usually made of a transparent resin film mainly composed of a cycloolefin resin or triacetyl cellulose. This transparent resin film may be an unstretched film or a uniaxially or biaxially stretched film.

  The second protective layer 23 adjacent to the pressure-sensitive adhesive layer 1 is made of a cycloolefin resin or triacetyl cellulose having excellent optical isotropy. Thereby, the obtained polarizing plate 2 can suppress the fall of optical performance to the minimum. Furthermore, from the viewpoint of reducing the thickness while maintaining optical performance, the second protective layer 23 is more preferably made of a cycloolefin resin.

  As the cycloolefin resin constituting the second protective layer 23, the cycloolefin resin exemplified in the first protective layer 22 can be used. Of these, dicyclopentadiene resins are preferred. As a commercially available product of such cycloolefin resin, “ZEONOR” manufactured by Nippon Zeon Co., Ltd. is particularly preferable.

  As a commercially available product of triacetyl cellulose constituting the second protective layer 23, “KC2UA” manufactured by Konica Minolta Opto Co., Ltd. is particularly preferable.

  In addition, the 1st protective layer 22 and the 2nd protective layer 23 may consist of the same kind of material (transparent resin film), and may consist of a different kind of material (transparent resin film).

  The thickness of the second protective layer 23 in the present embodiment is 5 μm or more and 30 μm or less. When the thickness of the second protective layer 23 is less than 5 μm, the handling property of the second protective layer 23 in the manufacturing process of the polarizing plate 2 is difficult, and the ability to protect the polarizer 21 is also reduced. If the thickness of the second protective layer 23 exceeds 30 μm, it becomes impossible to meet the demand for thinning the polarizing plate 2 obtained. From this viewpoint, the thickness of the second protective layer 23 is preferably 10 μm or more, and particularly preferably 12 μm or more. From the same point of view, the thickness of the second protective layer 23 is preferably 25 μm or less, and particularly preferably 24 μm or less.

  Furthermore, the ratio of the thickness of the second protective layer 23 to the thickness of the polarizer 21 is 1.0 or more and 5.0 or less. If this ratio is less than 1.0, the function of holding the polarizer 21 against thermal shrinkage becomes insufficient, and if this ratio exceeds 5.0, the polarizing plate 2 cannot be made thinner. From such a viewpoint, the ratio of the thickness of the second protective layer 23 to the thickness of the polarizer 21 is preferably 1.3 or more, and particularly preferably 1.5 or more. From the same viewpoint, the ratio is preferably 4.0 or less, and particularly preferably 3.6 or less.

  Furthermore, the ratio of the total thickness of the first protective layer 22 and the second protective layer 23 to the thickness of the polarizer 21 is 3.0 or more from the viewpoint of preventing thermal contraction of the polarizer 21. Is preferred. The upper limit is not particularly limited, but is preferably about 8.0 or less in consideration of a request for thinning the polarizing plate 2.

  The first protective layer 22 and the second protective layer 23 (hereinafter sometimes collectively referred to as “protective layers 22 and 23”) may contain an ultraviolet absorber. This is because the liquid crystal cell can be protected from deterioration due to ultraviolet rays by disposing a protective layer containing an ultraviolet absorber on the viewing side of the liquid crystal cell.

  In addition, prior to bonding to the polarizer 21, the protective layers 22 and 23 may be subjected to easy adhesion treatment such as saponification treatment, corona treatment, primer treatment, and anchor coating treatment on the bonding surface. Moreover, you may have various process layers, such as a hard-coat layer, an antireflection layer, an anti-glare layer, in the surface on the opposite side to the bonding surface to the polarizer 21 of the protective layers 22 and 23. FIG.

(4) Adhesive Layer Adhesive that constitutes an adhesive layer that may be interposed between the polarizer 21 and the first protective layer 22 and / or between the polarizer 21 and the second protective layer 23. As such, an appropriate one can be appropriately used depending on the type and purpose of the adherend. For example, solvent type adhesives, emulsion type adhesives, water based adhesives, pressure sensitive adhesives, rewet adhesives, polycondensation type adhesives, solventless type adhesives, film adhesives, hot melt type adhesives, etc. Can be mentioned.

  One preferable adhesive constituting the adhesive is a water-based adhesive, and a typical example thereof is a polyvinyl alcohol resin as a main component. Examples of commercially available polyvinyl alcohol resins that can be used as water-based adhesives include “KL-318” manufactured by Kuraray Co., Ltd.

  The aqueous adhesive may contain a crosslinking agent. As the crosslinking agent, an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt and the like are preferable, and an epoxy compound is particularly preferable. Examples of commercially available cross-linking agents include Glyoxal and “Smilease Resin 650 (30)” which is an aqueous solution of a water-soluble epoxy compound sold by Sumika Chemtex Co., Ltd.

  Another preferred adhesive is an adhesive made of an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating. When the adhesive is used, the adhesive between the films is applied by irradiating active energy rays or heating the adhesive layer interposed between the films to cure the curable epoxy resin contained in the adhesive. Can be done. Curing of the epoxy resin by irradiation with active energy rays or heating is preferably performed by cationic polymerization of the epoxy resin. In this specification, an epoxy resin means a compound having two or more epoxy groups in the molecule.

  From the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., the epoxy resin contained in the curable epoxy resin composition that is an adhesive is preferably an epoxy resin that does not contain an aromatic ring in the molecule. Examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, and the like.

(5) Manufacturing method of polarizing plate The polarizing plate 2 can be manufactured by a normal method. Hereinafter, as an example, a manufacturing method when a water-based adhesive is used as the adhesive will be described.

  First, an adhesive layer is formed on the bonding surface of the polarizer 21 or the bonding surfaces of the protective layers 22 and 23. For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, or a gravure coating method can be used for forming the adhesive layer. Moreover, it is also possible to adopt a method in which the polarizer 21 and the protective layers 22 and 23 are continuously supplied so that the bonding surfaces of the polarizer 21 and the protective layers 22 and 23 are inside, and an adhesive is cast between them. After the adhesive is applied, heat treatment is performed as necessary to evaporate moisture and dry the adhesive layer.

  The film thickness of the adhesive layer can be arbitrarily set by the characteristic design of the polarizing plate 2, but from the viewpoint of reducing the material cost of the adhesive, a smaller one is preferable, and the viewpoint of suppressing defects such as bubbles and foreign matters at the time of bonding From the viewpoint of adhesion and durability, it is preferable to carry out within the optimum range determined for each combination of the adherend and the adhesive. The film thickness of the adhesive layer is generally 0.005 μm or more, preferably 0.01 μm or more, and more preferably 0.03 μm or more. The film thickness is generally 10 μm or less, preferably 5 μm or less, and more preferably 1 μm or less.

  In adhering the polarizer 21 and the protective layers 22 and 23, a corona discharge treatment, a plasma treatment, a flame treatment, and a primer treatment are performed on one or both of the bonding surfaces before forming an adhesive coating layer. An easy adhesion treatment such as an anchor coating treatment may be performed.

  When the adhesive layer is formed as described above, the first protective layer 22 is bonded to one surface of the polarizer 21 through the adhesive layer, and the second protective layer 23 is bonded to the polarizer 21. Paste it on the other side. Thereby, the polarizing plate 2 formed by laminating the first protective layer 22, the polarizer 21, and the second protective layer 23 is obtained.

  The total thickness of the polarizing plate 2 is preferably 15 μm or more and 170 μm or less. In particular, the total thickness of the polarizing plate 2 is more preferably 20 μm or more, and particularly preferably 30 μm or more, from the viewpoint of maintaining polarization performance while meeting the demand for thinning in mobile applications. From the same viewpoint, the total thickness is more preferably 100 μm or less, and particularly preferably 80 μm or less.

3. Release sheet The release sheet may be laminated | stacked on the surface (lower surface in FIG. 1) on the opposite side to the polarizing plate 2 of the adhesive layer 1 in this embodiment.

  As the release sheet, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, Polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that at least one surface of the release sheet (particularly the release surface in contact with the pressure-sensitive adhesive layer) is subjected to a release treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

  When laminating release sheets on both sides of the pressure-sensitive adhesive layer, it is preferable that one release sheet is a heavy release release sheet having a large release force and the other release sheet is a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of a peeling sheet, Usually, it is about 20-150 micrometers.

4). Manufacturing method of polarizing plate with pressure-sensitive adhesive layer As an example of a manufacturing method of polarizing plate 10 with a pressure-sensitive adhesive layer, first, a coating solution of the pressure-sensitive adhesive composition P is applied to the release surface of the release sheet, followed by heat treatment. After forming the coating film, if desired, another release sheet (so that the release surface is in contact with the coating film) is laminated on the coating film to obtain an adhesive sheet. When the curing period is unnecessary, the coating film becomes an adhesive layer as it is, and when the curing period is necessary, the coating film becomes an adhesive layer after the curing period. The conditions for the heat treatment and curing are as described above.

  As a method for applying the coating solution, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.

  Next, one release sheet (light release type release sheet) is released from the obtained adhesive sheet. And the 2nd protective layer 23 of the polarizing plate 2 is piled up on the exposed adhesive layer, and an adhesive sheet and the polarizing plate 2 are crimped | bonded. Thereby, the said polarizing plate 10 with an adhesive layer (with a peeling sheet) is obtained.

  As another example of the manufacturing method of the polarizing plate 10 with an adhesive layer, the solution (coating solution) containing the adhesive composition P mentioned above is apply | coated to the peeling surface of a peeling sheet, and it heat-processes and performs a coating film. After the formation, the second protective layer 23 of the polarizing plate 2 is overlaid on the coating film. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating film becomes the pressure-sensitive adhesive layer 1 as it is. Thereby, the said polarizing plate 10 with an adhesive layer (with a peeling sheet) is obtained.

5). Physical Properties of Polarizing Plate with Adhesive Layer From the viewpoint of excellent durability, the polarizing plate with an adhesive layer 10 according to the present embodiment has an adhesive strength to non-alkali glass of 0.5 N / 25 mm or more. In particular, it is preferably 1 N / 25 mm or more, more preferably 1.5 N / 25 mm or more. Further, from the viewpoint of excellent reworkability, the adhesive force is preferably 20 N / 25 mm or less, particularly preferably 10 N / 25 mm or less, and more preferably 7 N / 25 mm or less. . In addition, although the adhesive force here means the adhesive force measured by the 180 degree peeling method according to JIS Z0237: 2009, the measurement sample has a width of 25 mm and a length of 100 mm, and the measurement sample is attached. After being applied to the body by applying pressure at 0.5 MPa and 50 ° C. for 20 minutes, the sample was left for 24 hours under conditions of normal pressure, 23 ° C. and 50% RH, and then measured at a peeling rate of 300 mm / min. To do.

  In addition, the polarizing plate 10 with the pressure-sensitive adhesive layer according to the present embodiment is a pressure-sensitive adhesive force after being left on the adherend for 14 days under conditions of 23 ° C. and 50% RH (adhesive strength after 14 days of sticking). Force) is preferably 1 N / 25 mm or more, and particularly preferably 3 N / 25 mm or more. The adhesive strength is preferably 20 N / 25 mm or less, and particularly preferably 9 N / 25 mm or less. Thus, by suppressing the increase in the adhesive force with time, the polarizing plate 10 with the pressure-sensitive adhesive layer according to the present embodiment is excellent in reworkability and can be easily re-applied even after being applied to the liquid crystal cell. it can.

The surface resistivity of the pressure-sensitive adhesive layer in the polarizing plate 10 with the pressure-sensitive adhesive layer according to this embodiment is preferably 1.0 × 10 ¹² Ω / sq or less, particularly 5.0 × 10 ¹¹ Ω / sq or less. It is preferable that it is 1.0 × 10 ¹⁰ Ω / sq or less. When the surface resistivity is not more than the above value, sufficient antistatic properties can be exhibited in the display panel. Such surface resistivity is determined by the fact that the (meth) acrylic acid ester copolymer (A) contains the oxyalkylene group-containing monomer (a3) as a monomer unit constituting the polymer. This can be achieved even when the content of the antistatic agent (C) is relatively small. In addition, the measurement of the surface resistivity of an adhesive layer shall be performed according to JISK6911, and is specifically as shown in the test example mentioned later. The lower limit value of the surface resistivity is not particularly limited, but is about 5.0 × 10 ⁸ Ω / sq from the viewpoint of not adversely affecting durability and heat unevenness.

6). Use of the polarizing plate with an adhesive layer By using the polarizing plate 10 with an adhesive layer, the liquid crystal display device provided with the liquid crystal cell and the polarizing plate can be manufactured, for example.

  Specifically, the pressure-sensitive adhesive layer 1 of the polarizing plate 10 with the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer 1 exposed by peeling the release sheet when the release sheet is laminated) is removed from the desired liquid crystal cell. What is necessary is just to superimpose on a surface and to crimp. Thereby, the liquid crystal display device provided with the liquid crystal cell and the polarizing plate 2 is obtained.

  Since the polarizing plate 10 with the pressure-sensitive adhesive layer according to this embodiment is excellent in durability, the obtained liquid crystal display device floats at the interface of the pressure-sensitive adhesive layer 1 even under high temperature conditions, wet heat conditions, or heat shocks. Occurrence of peeling is suppressed. For example, when the glass plate with the pressure-sensitive adhesive layer-attached polarizing plate 10 is placed under a high temperature condition of 85 ° C. or a wet heat condition of 60 ° C./90% RH for 250 hours, or a heat shock (−35 ° C. to 70 ° C. The occurrence of floating and peeling is also suppressed when given 30 minutes and 200 cycles).

  Moreover, since the polarizing plate 10 with an adhesive layer which concerns on this embodiment is excellent also in stress relaxation property, the obtained liquid crystal display device does not warp easily also on high temperature conditions, and also it is hard to produce a thermal nonuniformity. For example, even when the glass plate with the pressure-sensitive adhesive layer-attached polarizing plate 10 is placed under a high temperature condition (for example, at 80 to 85 ° C.) for 250 hours, it is difficult to warp and heat unevenness is unlikely to occur. In particular, even if the polarizing plate 2 is a thin film, the liquid crystal display device is unlikely to warp, and even if the liquid crystal cell has a high definition, heat unevenness hardly occurs.

  Furthermore, since the polarizing plate 10 with the pressure-sensitive adhesive layer according to this embodiment is also excellent in antistatic properties, for example, when the release sheet is peeled off from the pressure-sensitive adhesive layer 1, static electricity is hardly generated. Therefore, for example, when the adhesive layer-attached polarizing plate 10 from which the release sheet has been peeled is bonded to the liquid crystal cell, adverse effects on the liquid crystal cell can be suppressed. Moreover, it can suppress that dust and dust are attracted | sucked to the polarizing plate 10 with an adhesive layer by static electricity.

  Here, a transparent conductive film may be present on the bonding surface of the liquid crystal cell with the pressure-sensitive adhesive layer 1, but in this case, the transparent conductive film is corroded or the resistance value of the transparent conductive film changes. It is suppressed.

  Examples of the transparent conductive film include metals such as platinum, gold, silver, and copper, tin oxide, indium oxide, cadmium oxide, zinc oxide, zinc dioxide, and other oxides, tin-doped indium oxide (ITO), and zinc oxide-doped oxide. Examples include composite oxides such as indium, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, and non-oxidized compounds such as chalcogenide, lanthanum hexaboride, titanium nitride, and titanium carbide. It is done.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Manufacture of polarizing plate (1) Preparation of polarizer A 75 μm-thick polyvinyl alcohol film made of polyvinyl alcohol having an average polymerization degree of about 2,400 and a saponification degree of 99.9 mol% or more is uniaxially about 5 times as dry. The film was stretched and immersed in pure water at 60 ° C. for 1 minute while maintaining the tension. Then, it was immersed in an aqueous solution having a mass ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Subsequently, it was immersed in an aqueous solution having a mass ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Next, after washing with pure water at 26 ° C. for 20 seconds, it was dried at 65 ° C. to obtain a polarizer in which iodine was adsorbed and oriented on polyvinyl alcohol. The thickness of this polarizer was 15 μm.

(2) Preparation of polarizing plate 3 parts by mass of carboxyl group-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name “KL-318”) is dissolved in 100 parts by mass of water, and the aqueous solution is a water-soluble epoxy resin. An epoxy adhesive was prepared by adding 1.5 parts by mass of a polyamide epoxy additive (made by Taoka Chemical Industry Co., Ltd., trade name “Smile Resin 650 (30)”, aqueous solution having a solid concentration of 30% by mass). . The said epoxy-type adhesive agent was apply | coated to one side of the polarizer obtained above.

  A 25 μm thick triacetylcellulose film (trade name “KC2UA”, manufactured by Konica Minolta Opto Co., Ltd.) having a surface saponified as a first protective layer for the epoxy adhesive coating layer. Was pasted.

  Next, an epoxy adhesive is applied to the other surface of the polarizer in the same manner as described above, and a zero-position consisting of a cyclic olefin resin having a thickness of 23 μm is applied to the applied layer as a second protective layer. A phase difference film (manufactured by Zeon Corporation, trade name “ZEONOR”) was bonded. Thereafter, the first protective layer and the second protective layer were adhered to the polarizer by drying at 80 ° C. for 5 minutes. After bonding, the film is cured at 40 ° C. for 168 hours, and a first protective layer (layer thickness 25 μm), a polarizer (stretching ratio 5 times, layer thickness 15 μm) and a second protective layer (layer thickness 23 μm) are laminated. A polarizing plate having a total thickness of 63 μm was obtained. The ratio of the thickness of the first protective layer to the thickness of the polarizer was 1.67, and the ratio of the thickness of the second protective layer to the thickness of the polarizer was 1.53. The ratio of the total thickness of the first protective layer and the second protective layer to the thickness of the polarizer was 3.2.

2. Production of polarizing plate with pressure-sensitive adhesive layer (1) Preparation of (meth) acrylate copolymer (A) 62 parts by mass of n-butyl acrylate, 10 parts by mass of 2-methoxyethyl acrylate, 5 parts by mass of isobornyl acrylate Then, 20 parts by mass of 2-phenylethyl acrylate and 3 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth) acrylic acid ester copolymer (A). When the molecular weight of this (meth) acrylic acid ester copolymer (A) was measured by the method mentioned later, it was weight average molecular weight (Mw) 1.6 million. In addition, from the said mixing | blending, the hydroxyl value of the said (meth) acrylic acid ester copolymer (A) is calculated to 14.49 mgKOH / g, and an acid value is calculated to 0 mgKOH / g.

(2) Preparation of adhesive composition 100 parts by mass of the (meth) acrylic acid ester copolymer (A) obtained in the above step (1), and trimethylolpropane-modified xylylene as an isocyanate crosslinking agent (B) 0.2 parts by mass of isocyanate (trade name “Takenate D110N”, manufactured by Mitsui Chemicals) and N-octyl-4-methylpyridinium hexafluorophosphate (ionic compound that is solid at room temperature) as an antistatic agent (C) 5 0.0 part by mass, 0.2 part by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM403”) as an epoxy group-containing silane coupling agent (D1), and mercapto group-containing Co-condensation of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane as silane coupling agent (D2) By mixing 0.2 parts by mass of compound (Shin-Etsu Chemical Co., Ltd., trade name “X-41-1810”, mercapto equivalent: 450 g / mol), stirring well, and diluting with ethyl acetate, A coating solution of the adhesive composition was obtained.

Here, Table 1 shows each composition (solid content converted value) of the adhesive composition when the (meth) acrylic acid ester copolymer (A) is 100 parts by mass (solid content converted value). Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic ester copolymer (A)]
BA: n-butyl acrylate MEA: 2-methoxyethyl acrylate IBXA: isobornyl acrylate PhEA: 2-phenylethyl acrylate HEA: 2-hydroxyethyl acrylate
[Isocyanate-based crosslinking agent (B)]
XDI: trimethylolpropane-modified xylylene diisocyanate (Mitsui Chemicals, trade name “Takenate D110N”)
[Antistatic agent (C)]
Pry + PF6-: N-octyl-4-methylpyridinium hexafluorophosphate (ionic compound solid at room temperature)
K + FSI−: Potassium N, N-bis (fluorosulfonyl) imide (ionic compound that is solid at room temperature; manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., trade name “K-FSI”)
Pry + FSI-: N-decylpyridinium bis (fluorosulfonyl) imide (ionic compound solid at room temperature)

(3) Production of polarizing plate with pressure-sensitive adhesive layer A release sheet (SP-PET3811, manufactured by Lintec Corporation, thickness) obtained by peeling off a coating solution of the obtained pressure-sensitive adhesive composition with a silicone-based release agent on one side of a polyethylene terephthalate film. : 38 μm) was coated with a knife coater and then heat-treated at 90 ° C. for 1 minute to form a coating film of the adhesive composition.

  Next, the polarizing plate obtained above was bonded to the coating film so that the surface of the second protective layer and the exposed surface of the coating film were in contact with each other, and cured at 23 ° C. and 50% RH for 7 days. By doing this, a polarizing plate with an adhesive layer in which an adhesive layer was formed on the polarizing plate was obtained. The formed pressure-sensitive adhesive layer had a thickness of 20 μm.

[Examples 2-9, Comparative Examples 1-9]
Kind and ratio of each monomer constituting (meth) acrylate copolymer (A), weight average molecular weight of (meth) acrylate copolymer (A), blending amount of crosslinking agent (B), and charging A polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1 except that the type and blending amount of the inhibitor (C) were changed as shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of gel fraction)
Instead of the optical film used for the production of the polarizing plate with the pressure-sensitive adhesive layer in Examples or Comparative Examples, a release sheet obtained by peeling one side of a polyethylene terephthalate film with a silicone-type release agent (SP-PET 3801, manufactured by Lintec Corporation, thickness) S: 38 μm) was used to prepare an adhesive sheet. Specifically, the release treatment surface side contacts the release sheet on the exposed coating film of the composition comprising the release sheet / adhesive composition coating film obtained in the production process of the examples or comparative examples. And then cured under conditions of 23 ° C. and 50% RH for 7 days. This produced the adhesive sheet which consists of a structure of a peeling sheet (SP-PET3801) / adhesive layer (thickness: 20 micrometers) / release sheet (SP-PET3811).

  The obtained pressure-sensitive adhesive sheet is cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer is wrapped in a polyester mesh (mesh size 200), the mass is weighed with a precision balance, and the mass of the mesh alone is subtracted. Thus, the mass of only the adhesive was calculated. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the pressure sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 2] (Durability evaluation)
The polarizing plate with an adhesive layer obtained in the Examples and Comparative Examples was cut to prepare a sample having a size of 150 mm × 200 mm. The release sheet is peeled off from this sample and attached to non-alkali glass (product name “Eagle-XG”, manufactured by Corning) via the exposed adhesive layer, and then 0.5 MPa, 50 ° C. in an autoclave manufactured by Kurihara Seisakusho. And pressurized for 20 minutes.

Then, it put into the environment of the following three durability conditions, and the presence or absence of the float or peeling was confirmed using the 10 time loupe after 250 hours. The evaluation criteria are as follows. The results are shown in Table 2.
A: No lifting or peeling was confirmed.
○: Lifting or peeling of a size of 0.5 mm or less was confirmed.
(Triangle | delta): The float and peeling of a magnitude | size exceeding 0.5 mm and 1.0 mm or less were confirmed.
X: Floating and peeling of a size exceeding 1.0 mm were confirmed.
<Durability conditions>
・ Heat resistance: 85 ℃ dry
-Humid heat: 60 ° C, relative humidity 90% RH
・ H. S. : Heat shock test at -35 ° C to 70 ° C for 30 minutes each, 200 cycles

[Test Example 3] (Evaluation of warpage resistance)
The polarizing plate with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut so as to be 200 mm long and 150 mm wide. The release sheet is peeled off from the polarizing plate with the pressure-sensitive adhesive layer, and the exposed pressure-sensitive adhesive layer is placed in the center of 250 mm long, 175 mm wide, 0.5 mm thick non-alkali glass (product name “Eagle-XG” manufactured by Corning). This was attached to the part and used as a sample. This sample was allowed to stand for 250 hours at 85 ° C. in a dry atmosphere. Thereafter, the sample is taken out in an environment of 25 ° C. and 50% RH, placed on a horizontal table with the polarizing plate side up, and the amount of warpage of each corner (four points) of the sample from the table (distance between the corner and the table). ) And the amount of warpage of each corner was summed. Based on the results, warpage resistance was evaluated as follows. The results are shown in Table 2.
◎: Total warpage amount is 10 mm or less ○: Total warpage amount is more than 10 mm, 15 mm or less △: Total warpage amount is more than 15 mm, 20 mm or less ×: Total warpage amount is more than 20 mm

[Test Example 4] (Evaluation of heat resistance unevenness)
The polarizing plate with an adhesive layer obtained in Examples and Comparative Examples was adjusted to a size of 200 mm × 150 mm using a cutting device (Super Cutter manufactured by Hadano Seisakusho, PN1-600). The release sheet was peeled off and attached to alkali-free glass (Corning Corp., Eagle XG) via the exposed adhesive layer, and then pressurized at 0.5 MPa and 50 ° C. for 20 minutes in an autoclave manufactured by Kurihara Seisakusho. In addition, the said bonding was performed on the front and back of non-alkali glass so that the polarizing axis may be in a crossed nicols state (polarizing axis: ∠45 °, ∠135 °). In this state, it was allowed to stand for 250 hours in an 80 ° C. dry environment, and then left for 2 hours in an environment of 23 ° C. and 50% RH. Using this as a sample, the heat resistance unevenness was evaluated by the following method. The results are shown in Table 2.

<Evaluation method>
The sample is placed on a flat illuminator (Dentsu Sangyo Co., Ltd., HF-SL-A312LC, illuminance: 26,000 Lux, luminance: 10,000 cd), and a two-dimensional color luminance meter (Konica Minolta, CA-2000). ) And converted into a luminance distribution image by analysis software (Konica Minolta, CA-S20w). The luminance distribution image of the obtained sample was evaluated based on FIG. 2 and the evaluation criteria shown below.
A: The luminance distribution is almost uniform. B: The luminance distribution on the four sides is slightly distorted. Δ: The luminance distribution on the four sides is clearly distorted. X: The luminance distribution on the four sides is severely distorted.

[Test Example 5] (Measurement of adhesive strength-reworkability evaluation)
Samples having a width of 25 mm and a length of 100 mm were cut out from the polarizing plate with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples, the release sheet was peeled off, and the alkali-free glass (Corning Corp., Eagle) was exposed through the exposed pressure-sensitive adhesive layer. After being attached to XG), it was pressurized at 0.5 MPa and 50 ° C. for 20 minutes in an autoclave manufactured by Kurihara Seisakusho. Then, after leaving for 24 hours under conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec Co., Ltd., Tensilon), the adhesive strength (adhesion) under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. The adhesive strength after 1 day; N / 25 mm) was measured. Conditions other than those described here were measured according to JIS Z 0237: 2009. The results are shown in Table 2.

  Further, after being left for 14 days under conditions of 23 ° C. and 50% RH, the adhesive strength (adhesive strength after 14 days of application; N / 25 mm) was measured in the same manner as described above. The results are shown in Table 2.

Based on the adhesive strength after 14 days from the pasting, reworkability was evaluated according to the following criteria. The results are shown in Table 2.
◎: Adhesive strength after 14 days of application is 8.8 N / 25 mm or less ○: Adhesive strength after 14 days of application is more than 8.8 N / 25 mm and less than 10 N / 25 mm △: Adhesive strength after 14 days of application is 10 N / 25 mm or more, 20 N / Less than 25 mm x: Adhesive strength after 14 days of application is 20 N / 25 mm or more

[Test Example 6] (Measurement of surface resistivity of adhesive layer)
The pressure-sensitive adhesive layer-attached polarizing plate obtained in Examples and Comparative Examples was cut into a size of 50 mm × 50 mm, and the obtained sample was allowed to stand at a temperature of 23 ° C. and a humidity of 50% RH for 24 hours. Thereafter, the release sheet is peeled off, and the exposed adhesive layer surface is subjected to surface resistivity (Ω / sq) according to JIS K6911 using a resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., Hiresta UP MCP-HT450 type). ) Was measured. The results are shown in Table 2.

  As can be seen from Table 2, the polarizing plate with the pressure-sensitive adhesive layer obtained in the examples was excellent in durability, hardly warped even at high temperatures, and hardly caused heat unevenness. Moreover, the polarizing plate with an adhesive layer obtained in the Example had a low surface resistivity of the adhesive layer, and had a small adverse effect on liquid crystal cells and the like. Furthermore, the polarizing plate with an adhesive layer obtained in the Examples was excellent in reworkability.

  The polarizing plate with an adhesive layer according to the present invention is suitable for bonding a polarizing plate and a liquid crystal cell, particularly a liquid crystal cell having a transparent conductive film on the bonding surface.

DESCRIPTION OF SYMBOLS 10 ... Polarizing plate 1 with an adhesive layer ... Adhesive layer 2 ... Polarizing plate 21 ... Polarizer 22 ... 1st protective layer 23 ... 2nd protective layer

Claims (9)

A polarizer,
A first protective layer laminated on one surface side of the polarizer;
A second protective layer laminated on the other surface side of the polarizer;
A pressure-sensitive adhesive layer-attached polarizing plate comprising a pressure-sensitive adhesive layer laminated on a surface opposite to the surface on the polarizer side in the second protective layer,
The pressure-sensitive adhesive layer is
The monomer unit constituting the polymer contains an alicyclic structure-containing monomer (a1), an aromatic ring-containing monomer (a2), an oxyalkylene group-containing monomer (a3), and a hydroxyl group-containing monomer (a4), and has a hydroxyl value. (Meth) acrylic acid ester copolymer (A) having 5 mg KOH / g or more and 20 mg KOH / g or less, an acid value of 5 mg KOH / g or less, and a weight average molecular weight of 1.3 million or more and 3 million or less,
It is composed of an adhesive having a gel fraction of 60% or more and 89% or less obtained from an adhesive composition containing an isocyanate-based crosslinking agent (B),
The second protective layer is made of a cycloolefin resin or triacetyl cellulose,
The polarizer has a thickness of 1 μm or more and 20 μm or less,
The thickness of the second protective layer is 5 μm or more and 30 μm or less,
The ratio of the thickness of the said 2nd protective layer with respect to the thickness of the said polarizer is 1.0 or more and 5.0 or less, The polarizing plate with an adhesive layer characterized by the above-mentioned.   The polarizing plate with the pressure-sensitive adhesive layer according to claim 1, wherein the pressure-sensitive adhesive composition further contains an antistatic agent (C).   The polarizing plate with an adhesive layer according to claim 2, wherein the antistatic agent (C) is a nitrogen-containing onium salt. The thickness of the first protective layer is 5 μm or more and 120 μm or less,
The ratio of the thickness of the said 1st protective layer with respect to the thickness of the said polarizer is 1.0 or more and 6.0 or less, The adhesion as described in any one of Claims 1-3 characterized by the above-mentioned. A polarizing plate with an agent layer.   The polarizing plate with the pressure-sensitive adhesive layer according to any one of claims 1 to 4, wherein the first protective layer is made of triacetyl cellulose.   The polarizing plate with an adhesive layer according to any one of claims 1 to 5, wherein the alicyclic structure in the alicyclic structure-containing monomer (a1) is a polycyclic alicyclic structure.   The said adhesive composition further contains an epoxy group containing silane coupling agent (D1), The polarizing plate with an adhesive layer as described in any one of Claims 1-6 characterized by the above-mentioned.   The said adhesive composition further contains a mercapto group containing silane coupling agent (D2), The polarizing plate with an adhesive layer as described in any one of Claims 1-7 characterized by the above-mentioned.   The said isocyanate type crosslinking agent (B) is a compound which has an aromatic ring, The polarizing plate with an adhesive layer as described in any one of Claims 1-8 characterized by the above-mentioned.

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