JP2015024511A - Multilayer film, polarizing plate protective film, and polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film capable of maintaining its adhesive strength for a long period of time even in a high-temperature and high-humidity environment.SOLUTION: The present invention is the multilayer film including: a substrate film which has a surface layer comprising a resin containing an alicyclic structure-containing polymer or an acrylic polymer; and an easily adhesive layer formed on the surface layer of the substrate film. The easily adhesive layer is formed using an aqueous resin composition which comprises a resin A having a polar group and a crosslinking agent having, in its molecule, two or more functional groups reactive with the polar group in the resin A. The functional groups in the crosslinking agent are epoxy groups, carbodiimide groups, and/or oxazoline groups.

Description

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

  In recent years, a film made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer is known as a film used in various image display devices such as a liquid crystal display device, an organic EL display device, and a plasma display. Since these films are excellent in optical properties, for example, an electrode substrate of a liquid crystal cell constituting a liquid crystal display device, a polarizing plate, a protective film for a polarizing plate, a retardation film, a viewing angle widening film, a brightness enhancement film, and a touch panel Development for optical applications such as a film with a transparent electrode, a light guide plate, and an optical disk is being made.

  As described above, films used for optical applications are bonded to members having various other functions such as polarizers, hard coat layers, antireflection layers, antistatic layers, antiglare layers, and antifouling layers. Therefore, it is desirable that the adhesive strength with the member to be bonded is high.

  However, in a film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, adhesion to other members may not always be sufficient. For this reason, an easy-adhesion layer may be provided on the surface of the film. Note that the easy-adhesion layer is a layer that reinforces the adhesive force of the film and bonds it more firmly when the film is bonded to some member via an adhesive as necessary. About the easily bonding layer, what was formed with the urethane resin has been proposed conventionally (refer patent document 1).

JP 2009-274390 A

  However, the adhesive layer is required to have a higher adhesive force. For example, a multi-layer film having a conventional easy adhesive layer is bonded to a polarizer, for example, in a high temperature and high humidity environment for a long time. If placed, the adhesive strength may decrease.

  The object of the present invention was devised in view of the above problems, and is a base film having a surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, and the surface of the base film It is a multilayer film provided with an easily bonding layer formed on a layer, and is to provide a multilayer film capable of maintaining the adhesive force for a long period even in a high temperature and high humidity environment. Another object of the present invention is to provide a polarizing plate protective film and a polarizing plate excellent in durability by using a multilayer film having a high adhesive strength.

  As a result of intensive studies to solve the above problems, the present inventor has obtained a base film having a surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, and the surface layer in the base film. In a multilayer film comprising: an easy-adhesion layer, a resin A having a polar group is used as a base resin, and a cross-linking agent having two or more specific functional groups that react with the polar group is used in combination As a result, it was found that a sufficient adhesive force can be exhibited even after being placed in a high temperature and high humidity environment, and the present invention has been completed.

That is, the gist of the present invention is the following [1] to [5].
[1] A multilayer comprising a base film having a surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, and an easy-adhesion layer formed on the surface layer in the base film. A water-based resin composition comprising a resin A having a polar group and a crosslinking agent having two or more functional groups that react with the polar group in the resin A in a molecule. A multilayer film, wherein the functional group in the crosslinking agent is an epoxy group, a carbodiimide group, and / or an oxazoline group.
[2] The multilayer film, wherein the resin A is a polyurethane resin, an acrylic resin, and / or a polyester resin.
[3] The multilayer film, wherein the aqueous resin composition further includes one or more kinds of fine particles.
[4] A polarizing plate protective film comprising the multilayer film.
[5] A polarizing plate comprising a polarizer and the polarizing plate protective film.

  According to the present invention, the adhesive force between the surface layer and the other member in the base film having the surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer is further higher, and the temperature is higher. A multilayer film that can maintain the adhesive strength for a long period of time even in a humidity environment can be provided. Moreover, according to this invention, the polarizing plate protective film and polarizing plate which are excellent in durability can be provided by using a multilayer film with high adhesive force.

Hereinafter, the present invention will be described in more detail using embodiments and examples.
The present invention provides a composite film comprising a base film having a surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, and an easy-adhesion layer formed on the surface layer in the base film. It is a layer film.

 Note that the present invention is not limited to the following embodiments and exemplifications, and may be arbitrarily modified without departing from the gist of the present invention and its equivalent scope. In the following description, “(meth) acryl” includes both “acryl” and “methacryl”. Hereinafter, a resin containing an alicyclic structure-containing polymer may be referred to as an “alicyclic structure-containing polymer resin”, and a resin containing an acrylic polymer may be referred to as an “acrylic resin”.

<Base film>
The base film has a surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer. Therefore, when the base film is a single-layer film having only one layer, the base film is formed only by a layer made of an alicyclic structure-containing polymer resin or a layer made of an acrylic resin. When the base film is a film having a multilayer structure having two or more layers, at least one outermost layer of the base film is a layer made of an alicyclic structure-containing polymer resin or an acrylic resin layer. If there is, the base film may have other arbitrary layers.

<Alicyclic structure-containing polymer resin>
The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the repeating unit of the polymer, and has a polymer having an alicyclic structure in the main chain and an alicyclic structure in the side chain. Any of the polymers may be used. An alicyclic structure containing polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Among these, a polymer containing an alicyclic structure in the main chain is preferable from the viewpoint of mechanical strength, heat resistance, and the like.

  Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Among these, from the viewpoints of mechanical strength, heat resistance and the like, a cycloalkane structure and a cycloalkene structure are preferable, and a cycloalkane structure is particularly preferable.

  The number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, particularly preferably per alicyclic structure. Is in the range of 15 or less, the mechanical strength, the heat resistance, and the moldability of the base film are highly balanced, which is preferable.

  The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer may be appropriately selected according to the purpose of use, preferably 55% by weight or more, more preferably 70% by weight or more. Particularly preferably, it is 90% by weight or more. When the ratio of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer is in this range, it is preferable from the viewpoint of the transparency and heat resistance of the base film.

  Examples of alicyclic structure-containing polymers include norbornene polymers, monocyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrides thereof. Can be mentioned. Among these, norbornene-based polymers are preferable because of their good transparency and moldability.

  As the norbornene-based polymer, for example, a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof; An addition polymer of a monomer having a norbornene structure, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. It is. Here, “(co) polymer” refers to a polymer and a copolymer.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7. -Diene (common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4. 0.1 ^2,5 . ^{17, 10} ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different, and a plurality thereof may be bonded to the ring. Moreover, the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfonic acid group.

  Other monomers capable of ring-opening copolymerization with a monomer having a norbornene structure include, for example, monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; and cyclic conjugates such as cyclohexadiene and cycloheptadiene. Dienes and derivatives thereof; and the like. As the other monomer capable of ring-opening copolymerization with a monomer having a norbornene structure, one type may be used alone, or two or more types may be used in combination at any ratio.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer with another monomer copolymerizable with a monomer having a norbornene structure are, for example, a known ring-opening monomer. You may manufacture by superposing | polymerizing or copolymerizing in presence of a polymerization catalyst.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, And cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene; and the like. Among these, α-olefin is preferable and ethylene is more preferable. Moreover, the other monomer which can carry out addition copolymerization with the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with the monomer having a norbornene structure are, for example, a known addition polymerization catalyst. You may manufacture by superposing | polymerizing or copolymerizing in presence.

  Examples of the monocyclic olefin polymer include addition polymers of a cyclic olefin monomer having a single ring such as cyclohexene, cycloheptene, and cyclooctene.

  Examples of the cyclic conjugated diene polymer include polymers obtained by cyclization reaction of addition polymers of conjugated diene monomers such as 1,3-butadiene, isoprene and chloroprene; cyclic conjugates such as cyclopentadiene and cyclohexadiene. And 1,2- or 1,4-addition polymers of diene monomers; and their hydrides.

  Examples of vinyl alicyclic hydrocarbon polymers include polymers of vinyl alicyclic hydrocarbon monomers such as vinylcyclohexene and vinylcyclohexane and their hydrides; vinyl aromatic hydrocarbons such as styrene and α-methylstyrene. Hydrogenated product obtained by hydrogenating an aromatic ring part contained in a polymer obtained by polymerizing monomers; vinyl alicyclic hydrocarbon monomer, or vinyl aromatic hydrocarbon monomer and vinyl aromatic hydrocarbon monomer And an aromatic ring hydride of a copolymer such as a random copolymer or a block copolymer with another copolymerizable monomer. Examples of the block copolymer include a diblock copolymer, a triblock copolymer or a multi-block copolymer having more than that, a gradient block copolymer, and the like.

  The molecular weight of the alicyclic structure-containing polymer is appropriately selected according to the purpose of use, but gel permeation using cyclohexane as a solvent (however, toluene may be used when the sample does not dissolve in cyclohexane). The polyisoprene or polystyrene-equivalent weight average molecular weight (Mw) measured by chromatography is usually 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, and usually 100,000 or less, preferably Is 80,000 or less, more preferably 50,000 or less. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the multilayer film of the present invention are highly balanced and suitable.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the alicyclic structure-containing polymer is usually 1.2 or more, preferably 1.5 or more, more preferably 1.8 or more, usually It is 3.5 or less, preferably 3.0 or less, and more preferably 2.7 or less. When the molecular weight distribution exceeds 3.5, low-molecular components increase, so the components with a short relaxation time increase. Even if the base film has the same in-plane retardation Re at first glance, the relaxation during high-temperature exposure is large in a short time. It is estimated that the stability of the base film is lowered. On the other hand, when the molecular weight distribution is less than 1.2, the productivity of the polymer is reduced and the cost is increased, which is not practical from the viewpoint of practicality.

The alicyclic structure-containing polymer preferably has an absolute value of the photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 7 × 10 ⁻¹² Pa ⁻¹ or less, and 4 × 10. It is particularly preferably ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient C is a value represented by “C = Δn / σ” where birefringence is Δn and stress is σ. If the photoelastic coefficient of the alicyclic structure-containing polymer exceeds 10 × 10 ⁻¹² Pa ⁻¹ , the in-plane retardation Re of the base film may vary greatly.

  The saturated water absorption of the alicyclic structure-containing polymer is preferably 0.03% by weight or less, more preferably 0.02% by weight or less, and particularly preferably 0.01% by weight or less. When the saturated water absorption is in the above range, the temporal change of the in-plane retardation Re and the thickness direction retardation Rth of the base film can be reduced. In addition, deterioration of the polarizing plate and the liquid crystal display device including the multilayer film of the present invention can be suppressed, and the display on the display can be kept stable and favorable for a long period.

  The saturated water absorption is a value expressed as a percentage with respect to the mass of the test piece before immersion, which is obtained by immersing the test piece in water at a constant temperature for a certain period of time. Usually, it is measured by immersing in 23 ° C. water for 24 hours. The saturated water absorption in the alicyclic structure-containing polymer can be adjusted to the above range, for example, by reducing the amount of polar groups in the alicyclic structure-containing polymer. From the viewpoint of lowering the saturated water absorption, the alicyclic structure-containing polymer preferably has no polar group.

  The alicyclic structure-containing polymer resin may contain other components in addition to the alicyclic structure-containing polymer as long as the effects of the present invention are not significantly impaired. Examples of other components include colorants such as pigments and dyes; plasticizers; fluorescent brighteners; dispersants; thermal stabilizers; light stabilizers; ultraviolet absorbers; antistatic agents; An additive such as a surfactant may be mentioned. These components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  However, the amount of the polymer contained in the alicyclic structure-containing polymer resin is generally 50% to 100%, or 70% to 100%. In particular, even when the base film according to the present invention has a layer made of a polymer resin containing an alicyclic structure having a high hydrophobicity, by providing a urethane resin layer with other members having high hydrophilicity It has the advantage of being able to adhere firmly. From the viewpoint of effectively utilizing this advantage, the amount of the polymer contained in the alicyclic structure-containing polymer resin is, for example, 80% to 100%, more specifically, 90% to 100%. It is preferable to adjust the amount of these components.

  However, it is preferable that the alicyclic structure-containing polymer resin does not substantially contain particles. Here, “substantially free of particles” means that the increase in haze of the base film from a state in which no particles are contained even when particles are included in the alicyclic structure-containing polymer resin is 0.05%. It means that amounts up to the following range are acceptable. Since the alicyclic structure-containing polymer lacks affinity with many organic particles and inorganic particles, when an alicyclic structure-containing polymer resin containing particles exceeding the above range is stretched, voids are generated. As a result, the haze may be significantly reduced.

  The layer made of the alicyclic structure-containing polymer resin is not particularly limited by the production method. The layer made of the alicyclic structure-containing polymer resin is obtained by molding the alicyclic structure-containing polymer resin by a known film forming method. Examples of the film forming method include a cast forming method, an extrusion forming method, and an inflation forming method. Among these, a melt extrusion method that does not use a solvent can reduce the amount of residual volatile components efficiently, and is preferable from the viewpoints of the global environment and work environment, and excellent manufacturing efficiency. Examples of the melt extrusion method include an inflation method using a die, and among them, a method using a T die is preferable in terms of excellent productivity and thickness accuracy.

<Acrylic resin>
An acrylic polymer means a polymer of (meth) acrylic acid or a (meth) acrylic acid derivative. For example, polymers such as acrylic acid, acrylic acid ester, acrylamide, acrylonitrile, methacrylic acid and methacrylic acid ester, and copolymer Coalesce is mentioned. Since the acrylic polymer has high strength and is hard, a multilayer film having high strength can be realized.

  As the acrylic polymer, a polymer containing a repeating unit derived from a (meth) acrylic acid ester is preferable. In that case, the acrylic polymer may be a homopolymer or copolymer consisting only of (meth) acrylic acid ester, or a copolymer of (meth) acrylic acid ester and a monomer copolymerizable therewith. But you can.

  The (meth) acrylic acid ester preferably has a structure derived from (meth) acrylic acid and an alkanol having 1 to 15 carbon atoms or a cycloalkanol, more preferably derived from an alkanol having 1 to 8 carbon atoms. The thing of the structure made is mentioned. When there are too many carbon numbers, there exists a tendency for the elongation at the time of the fracture | rupture of the obtained base film to become large.

  Specific examples of (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, sec-butyl acrylate, Acrylic acid esters such as t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate; methyl methacrylate; Ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, n-methacrylate Octyl, 2-ethylhexyl methacrylate Le, methacrylic acid n- decyl, methacrylic acid esters such as methacrylic acid n- dodecyl, and the like.

These (meth) acrylic acid esters may have an arbitrary substituent such as a hydroxyl group or a halogen atom. Examples of the (meth) acrylic acid ester having such a substituent include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-methacrylic acid 2- Examples thereof include hydroxypropyl, 4-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, glycidyl methacrylate and the like.
Moreover, (meth) acrylic acid ester may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The acrylic polymer may be a polymer of only acrylic acid or an acrylic acid derivative, or may be a copolymer of acrylic acid or an acrylic acid derivative and a monomer copolymerizable therewith. Examples of the copolymerizable monomer include α, β-ethylenically unsaturated carboxylic acid ester monomers other than the above-mentioned (meth) acrylic acid esters, and α, β-ethylenically unsaturated carboxylic acid monomers. Monomer, alkenyl aromatic monomer, conjugated diene monomer, non-conjugated diene monomer, vinyl cyanide monomer, α, β-ethylenically unsaturated carboxylic acid amide monomer, carboxylic acid unsaturated alcohol Examples thereof include esters and olefin monomers. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  Specific examples of α, β-ethylenically unsaturated carboxylic acid ester monomers other than (meth) acrylic acid esters include dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, and dimethyl itaconate. It is done.

  The α, β-ethylenically unsaturated carboxylic acid monomer may be any of a monocarboxylic acid, a polyvalent carboxylic acid, a partial ester of a polyvalent carboxylic acid, and a polyvalent carboxylic acid anhydride. Specific examples thereof include croton. Examples include acid, maleic acid, fumaric acid, itaconic acid, monoethyl maleate, mono n-butyl fumarate, maleic anhydride, itaconic anhydride and the like.

  Specific examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, methyl α-methylstyrene, vinyl toluene and divinylbenzene.

  Specific examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1. , 3-butadiene, cyclopentadiene and the like.

  Specific examples of the non-conjugated diene monomer include 1,4-hexadiene, dicyclopentadiene, ethylidene norbornene and the like.

  Specific examples of the carboxylic acid unsaturated alcohol ester monomer include vinyl acetate.

  Specific examples of the olefin monomer include ethylene, propylene, butene, pentene and the like.

  Among these copolymerizable monomers, alkenyl aromatic monomers are preferable, and styrene is particularly preferable. Moreover, the copolymerizable monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  When the acrylic polymer contains a copolymerizable monomer, the content of the repeating unit derived from the monomer copolymerizable with acrylic acid or an acrylic acid derivative in the acrylic polymer is preferably 50% by weight or less. More preferably, it is 15% by weight or less, particularly preferably 10% by weight or less.

  Preferable specific examples of the acrylic polymer include methyl methacrylate / methyl acrylate / butyl acrylate / styrene copolymer, methyl methacrylate / methyl acrylate copolymer, methyl methacrylate / styrene / butyl acrylate copolymer. Etc. An acrylic polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Of these, polymethacrylate is preferable, and polymethyl methacrylate is more preferable.

  The molecular weight of the acrylic polymer is not particularly limited, but is usually 50,000 to 500,000 in terms of weight average molecular weight. When the molecular weight is within this range, a homogeneous film layer can be easily produced by the melt casting method.

  The acrylic resin may contain other components in addition to the acrylic polymer as long as the effects of the present invention are not significantly impaired. When the example of the component is given, the example similar to the component which the alicyclic structure containing polymer resin may contain is given. In addition, these components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The elongation at break in the tensile test of the acrylic resin is preferably 10% or more, more preferably 50% or more, preferably 180% or less, more preferably 170% or less. When the elongation at break is within the above range, the scraping processability of the unnecessary portion of the base film becomes good. Here, the above-described scrap raising workability means operability when removing the removed unnecessary portion (cass) when the unnecessary portion of the base film is cut off. The elongation at break is a value obtained under the conditions of test piece type 1B (W10, L100, t0.1 mm) and speed of 5 mm / min according to JIS K 7127.

  There is no restriction | limiting in particular in the manufacturing method of the layer which consists of acrylic resins. For example, when forming a layer with a thermoplastic acrylic resin, you may manufacture by shape | molding with the film forming method similar to the layer which consists of the above-mentioned alicyclic structure containing polymer resin.

  For example, when the layer is formed of an ultraviolet curable acrylic resin, an uncured acrylic resin is applied to the surface of the underlying film, and then the ultraviolet curable acrylic resin is cured by irradiating ultraviolet rays. Thus, a layer made of acrylic resin may be formed.

  As the ultraviolet curable acrylic resin, it is preferable to use a resin having an affinity for the easy adhesion layer. For example, urethane acrylate, epoxy acrylate, and polyester acrylate acrylic resins are preferable.

As an uncured acrylic resin, for example, a resin that contains one or more of prepolymers, oligomers, and monomers having a polymerizable unsaturated bond or an epoxy group in the molecule and is cured by irradiation with ultraviolet rays, etc. Is mentioned.
Examples of the prepolymer or oligomer having a polymerizable unsaturated bond or epoxy group in the molecule include unsaturated polyesters such as a condensate of unsaturated dicarboxylic acid and polyhydric alcohol; polyester methacrylate, polyether methacrylate, polyol methacrylate And methacrylates such as melamine methacrylate; acrylates such as polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polyol acrylate, and melamine acrylate; and cationic polymerization type epoxy compounds.

Examples of monomers having a polymerizable unsaturated bond or an epoxy group in the molecule include styrene monomers such as styrene and α-methylstyrene; methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate Acrylates such as butoxyethyl acrylate, butyl acrylate, methoxybutyl acrylate, and phenyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, methoxyethyl methacrylate, ethoxymethyl methacrylate, phenyl methacrylate , Methacrylic acid esters such as lauryl methacrylate; acrylic acid-2- (N, N-diethylamino) ethyl, acrylic acid-2- (N, N-dimethylamino) ethyl, acrylic acid-2- (N, N- Dibenzylamino) methyl , Unsaturated substituted amino alcohol esters such as acrylic acid-2- (N, N-diethylamino) propyl; unsaturated carboxylic acid amides such as acrylamide and methacrylamide; ethylene glycol diacrylate, propylene glycol diacrylate, neo Pentyl glycol diacrylate, 1,6-hexanediol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, ethylene glycol diacrylate, propylene glycol dimethacrylate, diethylene glycol dimethacrylate, 2-hydroxy acrylate, 2-hexyl acrylate, Phenoxyethyl acrylate, ethylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylo Polyfunctional acrylates such as tripropanetriacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate; trimethylolpropane trithioglycolate, trimethylolpropane trithiopropylate Polythiols having two or more thiol groups in the molecule, such as pentaerythritol tetrathioglycolate; glycidyl acrylate, glycidyl methacrylate, glycidyl phenyl ether, glycidyl ethyl ether, epichlorohydrin, allyl glycidyl ether, ethylene oxide, Propylene oxide, neopentyl glycol diglycidyl ether, trimethylolpropane jig Sidyl ether, glycerol diglycidyl ether, diglycerol triglycidyl ether, diglycerol triglycidyl ether, pentaerythritol diglycidyl ether, pentaerythritol triglycidyl ether, diglycidyl ether of tris (2-hydroxyethyl) isocyanurate, phenol novolac polyglycidyl Examples thereof include epoxy compounds such as ether and cresol novolac polyglycidyl ether.
In the present invention, these prepolymers, oligomers and monomers may be used alone or in combination of two or more in any ratio.

  The content of the prepolymer, oligomer and monomer in the uncured ultraviolet curable acrylic resin is preferably 5% by weight to 95% by weight from the viewpoint of obtaining excellent coating suitability.

  The ultraviolet curable acrylic resin preferably contains a photopolymerization initiator and a photopolymerization accelerator. Examples of the photopolymerization initiator include radical polymerizable initiators such as acetophenones, benzophenones, thioxanthones, acylphosphine oxides, benzoin ethers, oxime esters; aromatic diazonium salts, aromatic sulfonium salts, aromatics Cation polymerizable initiators such as group iodonium salts, metathelone compounds, and benzoin sulfonates. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios. Content of a photoinitiator is 0.1 to 10 weight% normally in an acrylic resin.

  The ultraviolet curable acrylic resin may contain a solvent in an uncured state. Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, and isobutanol; ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, diethylene glycol, diethylene glycol monobutyl ether, diacetone glycol, and propylene. Glycols such as glycol monomethyl ether; aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane and n-heptane; esters such as ethyl acetate and butyl acetate; methyl ethyl ketone and methyl isobutyl ketone Ketones; oximes such as methyl ethyl ketoxime; and the like. Moreover, a solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The method for applying the uncured acrylic resin to the surface of the underlying film is not particularly limited, and a known coating method may be employed. Specific coating methods include, for example, a wire bar coating method, a dip method, a spray method, a spin coating method, a roll coating method, a gravure coating method, an air knife coating method, a curtain coating method, a slide coating method, and an extrusion coating method. Etc.

  The coating amount of the uncured acrylic resin is not particularly limited, but the thickness after curing is usually 0.05 μm or more, preferably 0.1 μm or more, more preferably 0.5 μm or more, usually 50 μm or less, preferably 20 μm or less. More preferably, the amount is 10 μm or less.

  As described above, the base film may be a film layer having a single layer structure including only one layer, or may be a film layer having a multilayer structure including two or more layers. By making the base film into a film layer having a multilayer structure, polarizing plates having various characteristics can be produced. However, when the base film includes two or more layers, the surface layer as the layer made of the alicyclic structure-containing polymer resin or the layer made of the acrylic resin is positioned on the outermost surface of the base film. . Under the present circumstances, the surface layer as a layer which consists of an alicyclic structure containing polymer resin or a layer which consists of an acrylic resin only in one outermost surface among the two outermost surfaces (a front surface and a back surface) of a base film May be located, and a surface layer as a layer made of an alicyclic structure-containing polymer resin or a layer made of an acrylic resin may be located on both outermost surfaces.

  When the base film includes two or more layers, one or more types of film layers may be included, or two or more different types of film layers may be included. Moreover, you may provide the layer which consists of resin other than the alicyclic structure containing polymer resin and acrylic resin which were mentioned above in a base film. Thus, there is no limitation on the type of layer combined with the layer made of alicyclic structure-containing polymer resin or the surface layer made of acrylic resin, such as scratch prevention, antireflection, antistatic, antiglare, antiglare, antifouling, etc. Examples thereof include a film layer having a function. Specific examples of the layer structure of the base film include, for example, a base film having a three-layer structure in which an acrylic resin layer, a styrene resin layer, and an acrylic resin layer are laminated in this order. It is done.

  When a base film is provided with two or more layers, there is no restriction | limiting in the manufacturing method of a base film. For example, you may manufacture a base film by bonding the film layer manufactured separately using an adhesive agent. For example, you may manufacture a base film by a coextrusion method etc., without using an adhesive agent.

  The adhesive may be appropriately selected depending on the type of resin forming the film layer to be bonded. Examples of adhesives include acrylic adhesives, urethane adhesives, polyester adhesives, polyvinyl alcohol adhesives, polyolefin adhesives, modified polyolefin adhesives, polyvinyl alkyl ether adhesives, rubber adhesives , Ethylene-vinyl acetate adhesive, vinyl chloride-vinyl acetate adhesive, SEBS (styrene-ethylene-butylene-styrene copolymer) adhesive, SIS (styrene-isoprene-styrene block copolymer) adhesive And ethylene-based adhesives such as ethylene-styrene copolymer, and acrylic acid ester-based adhesives such as ethylene- (meth) methyl acrylate copolymer and ethylene- (meth) ethyl acrylate copolymer. An adhesive agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The average thickness of the adhesive layer formed of the adhesive is preferably 0.1 μm or more, more preferably 0.5 μm or more, preferably 10 μm or less, more preferably 5 μm or less.

  When manufacturing a base film without using an adhesive, for example, a coextrusion molding method such as a coextrusion T-die method, a coextrusion inflation method, a coextrusion lamination method, or a film lamination molding method such as dry lamination is used. May be. Further, for example, a coating molding method in which the surface of a certain film layer is coated with a solution containing a resin constituting another film layer may be used. Among these, the coextrusion molding method is preferable from the viewpoint of production efficiency and the volatile component such as a solvent does not remain in the base film, and the coextrusion T die method is preferable among the coextrusion molding methods. Furthermore, the co-extrusion T-die method includes a feed block method and a multi-manifold method, but the multi-manifold method is more preferable from the viewpoint that variations in film layer thickness can be reduced.

  The base film may be a non-stretched unstretched film or a stretched stretched film. In addition, when the base film has two or more layers, a stretched film may be obtained by laminating a previously stretched film layer, or a stretched film obtained by stretching a multilayer film layer obtained by coextrusion or the like. You may get

  The stretching method is not particularly limited, and for example, either a uniaxial stretching method or a biaxial stretching method may be adopted. As an example of the stretching method, as an example of the uniaxial stretching method, a method of uniaxial stretching in the longitudinal direction using a difference in peripheral speed of a roll for film conveyance; uniaxial stretching in the width direction using a tenter stretching machine And the like. In addition, as an example of the biaxial stretching method, simultaneous biaxial stretching method that stretches in the width direction according to the spread angle of the guide rail at the same time as stretching in the longitudinal direction with an interval between the clips to be fixed; roll for film conveyance The biaxial stretching method such as the sequential biaxial stretching method is used in which the two ends are clipped and stretched in the width direction using a tenter stretching machine. Can be mentioned. Further, for example, an arbitrary angle θ is formed with respect to the width direction of the film by using a tenter stretching machine that can add a feeding force, a pulling force, or a pulling force at different speeds in the width direction or the longitudinal direction. An oblique stretching method in which oblique stretching is continuously performed in the direction may be used.

  Examples of the apparatus used for stretching include a longitudinal uniaxial stretching machine, a tenter stretching machine, a bubble stretching machine, and a roller stretching machine. The stretching temperature is preferably (Tg-30 ° C) or more, more preferably (Tg-10 ° C) or more, preferably, when the glass transition temperature of the material forming the unstretched base film is Tg. (Tg + 60 ° C.) or less, more preferably (Tg + 50 ° C.) or less. The draw ratio may be appropriately selected according to the optical characteristics of the base film used, and is usually 1.05 times or more, preferably 1.1 times or more, and usually 10.0 times or less, preferably 2. 0 times or less.

  The base film preferably has a total light transmittance of 80% or more in terms of 1 mm thickness, more preferably 90% or more. The base film preferably has a haze at a thickness of 1 mm of 0.3% or less. More preferably, the haze is 0.2% or less. If the haze exceeds 0.3%, the transparency of the base film may be lowered.

  The average thickness of the base film is preferably 5 μm or more, more preferably 20 μm or more, preferably 500 μm or less, more preferably 300 μm or less. The thickness variation width of the base film is preferably within ± 3% of the average thickness over the longitudinal direction and the width direction. By setting the thickness variation within the above range, variations in optical properties such as retardation of the base film can be reduced.

  The content of residual volatile components in the base film is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and still more preferably 0.02% by weight or less. By setting the content of the volatile component in the above range, the dimensional stability is improved, and the temporal change of the in-plane retardation Re and the thickness direction retardation Rth of the base film can be reduced. Deterioration of a polarizing plate or a liquid crystal display device provided with the multilayer film of the invention can be suppressed, and the display on the display can be kept stable and good for a long period. Volatile components are substances having a molecular weight of 200 or less, and examples thereof include residual monomers and solvents. The content of volatile components can be quantified by analyzing the total amount of substances having a molecular weight of 200 or less by gas chromatography.

<Easily adhesive layer>
The easy adhesion layer is a layer formed using a water-based resin composition. This easy-adhesion layer is usually provided directly on the surface layer made of an alicyclic structure-containing polymer resin or an acrylic resin of the base film without any other layer such as an adhesive layer. It is done. The easy adhesion layer may be provided only on one side of the base film, or may be provided on both sides. However, it is preferable to provide an easy-adhesion layer only on one side of the base film from the viewpoint of easily winding a multilayer film having an easy-adhesion layer into a roll. The easy adhesion layer can be obtained by applying the aqueous resin composition on the surface layer of the base film and drying the applied product.

<Aqueous resin composition>
The aqueous resin composition is a composition comprising a resin A having a polar group and a cross-linking agent having two or more functional groups in the molecule that react with the polar group in the resin A, and has water solubility or water dispersibility. Have.

<Resin A having polar group>
The resin A having a polar group is not particularly limited as long as it is water-soluble or water-dispersible and can be crosslinked by a crosslinking agent. As resin A which has a polar group, what introduce | transduced polar groups into various polymers, such as an acrylic resin, a vinyl resin, a polyurethane resin, a polyester resin, can be used, for example. Examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfo group, and a methylol group, a hydroxyl group, and a carboxyl group. It is preferably any one of a group and an amino group, more preferably a hydroxyl group or a carboxyl group, and particularly preferably a carboxyl group. The content of the polar group in the resin A is preferably 0.0001 to 1 equivalent / 1 kg, particularly preferably 0.001 to 1 equivalent / 1 kg.

  Acrylic resins include acrylic acid esters such as acrylic acid and alkyl acrylate, acrylamide, acrylonitrile, methacrylic acid esters such as methacrylic acid and alkyl methacrylate, and homopolymers of any monomer of methacrylamide and methacrylonitrile. , Copolymers obtained by polymerization of two or more of these monomers, copolymers obtained by polymerization of one or more of the monomers and other monomers, and the like. Among these, homopolymers of monomers of acrylic acid esters such as alkyl acrylates and methacrylic acid esters such as alkyl methacrylates, or copolymers obtained by polymerization of two or more of these monomers preferable. For example, mention may be made of homopolymers of monomers of acrylic acid esters and methacrylic acid esters having an alkyl group having 1 to 6 carbon atoms, or copolymers obtained by polymerization of two or more of these monomers. it can. The acrylic resin is a polymer obtained by using a part of the above-mentioned monomer having a polar group so that the composition is a main component and a reaction with a functional group in the crosslinking agent (crosslinking reaction) is possible.

  Examples of the vinyl resin include polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl methyl ether, polyolefin, ethylene / butadiene copolymer, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, vinyl chloride / (meta ) Acrylic acid ester copolymers and ethylene / vinyl acetate copolymers (preferably ethylene / vinyl acetate / (meth) acrylic acid ester copolymers). Among these, polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl polymer, polyolefin, ethylene / butadiene copolymer and ethylene / vinyl acetate copolymer (preferably ethylene / vinyl acetate / acrylic acid ester copolymer). Is preferred. For the vinyl resin, polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl methyl ether, and polyvinyl acetate leave, for example, a vinyl alcohol unit in the polymer so that a crosslinking reaction with a carbodiimide compound is possible. Thus, the polymer having a hydroxyl group is used, and the other polymer is, for example, a crosslinkable polymer by partially using a monomer having a methylol group, a hydroxyl group, a carboxyl group and / or an amino group.

  Examples of polyurethane resins include polyol compounds (ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, glycerin, trimethylolpropane, etc.) and polybasic acids (polyvalent carboxylic acids (eg, adipic acid, succinic acid). Reaction with dicarboxylic acids such as sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, and tricarboxylic acids such as trimellitic acid or their anhydrides)) Any of aliphatic polyester polyols, polyether polyols (eg, poly (oxypropylene ether) polyols, poly (oxyethylene-propylene ether) polyols), polycarbonate polyols, and polyethylene terephthalate polyols obtained by One kind, or it may be mentioned polyurethane resins derived from a mixture thereof with a polyisocyanate. In the polyurethane resin, for example, the unreacted hydroxyl group after the reaction between polyol and polyisocyanate can be used as a polar group capable of crosslinking reaction with a functional group in the crosslinking agent.

  As the polyurethane resin, a commercially available water-based urethane resin may be used. The water-based urethane resin is a composition containing a polyurethane resin and water, and is usually one in which polyurethane and other components contained as necessary are dispersed in water. Examples of water-based urethane resins include the “ADEKA BONTITER” series manufactured by ADEKA, the “Olestar” series manufactured by Mitsui Chemicals, the “Bondic” series manufactured by DIC, and the “Hydran (WLS201, WLS202, etc.)” series. Bayer's "Imprunil" series, Kao's "Poise" series, Sanyo Kasei's "Samprene" series, Daiichi Kogyo Seiyaku's "Superflex" series, Enomoto Kasei's " NEOREZ "series," Sancure "series manufactured by Lubrizol, etc. can be used. In addition, a polyurethane resin may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  As the polyester resin, a polymer obtained by a reaction between the polyol compound and the polybasic acid is generally used. In the polyester resin, for example, hydroxyl groups and carboxyl groups remaining unreacted after the reaction between the polyol and the polybasic acid can be used as polar groups capable of crosslinking reaction with a crosslinking agent. Of course, you may add the 3rd component which has polar groups, such as a hydroxyl group and a carboxyl group. Here, the polyester resin has an acrylic ester such as acrylic acid and alkyl acrylate, acrylamide ester such as acrylamide, acrylonitrile, methacrylic acid and alkyl methacrylate, methacrylamide and methacrylonitrile for improving adhesion. A polyester resin acrylic in which a homopolymer of any of the above monomers, a copolymer obtained by polymerizing two or more of these monomers, a copolymer obtained by polymerizing one or more of the monomers with another monomer, and the like are mixed. Resin composites are also included.

 As the water-soluble or water-dispersed polyester resin, those appropriately synthesized may be used, or commercially available products may be used. Examples of the commercially available products include “Nichigo Polyester (Nichigo Polyester W-0030, Nichigo Polyester W-0005S30WO, Nichigo Polyester WR-961, etc.)” series (manufactured by Nippon Gosei Kagaku Co., Ltd.), A-210, pesresin A-520, pesresin A-684G, pesresin A-695GE, etc.) ”series (manufactured by Takamatsu Yushi Co., Ltd.) and the like.

<Crosslinking agent>
Although the said crosslinking agent is not specifically limited, It is a compound which has two or more functional groups in a molecule | numerator which can react with the polar group in the said resin A, and can form a bond. Examples of the crosslinking agent include an epoxy compound, a carbodiimide compound, an oxazoline compound, and an isocyanate compound.

<Epoxy compound>
As the epoxy compound, a polyfunctional epoxy compound having two or more epoxy groups in the molecule can be used. Thereby, the cross-linking reaction can be advanced to effectively improve the mechanical strength of the easy adhesion layer made of the resin A.

  As the epoxy compound, those which are soluble in water or can be emulsified by being dispersed in water are preferable. Here, the aqueous resin refers to a composition containing a solid content dissolved or dispersed in an aqueous solvent such as water. If the epoxy group has solubility in water or can be emulsified, the coating property of the water-based resin can be improved, and the easy-adhesion layer can be easily produced.

  Examples of the epoxy compound include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexane glycol, neopentyl glycol and the like glycols 1 Diepoxy compound obtained by etherification of 1 mol with 2 mol of epichlorohydrin; obtained by etherification of 1 mol of polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and 2 mol or more of epichlorohydrin Polyepoxy compound: Diepoxy obtained by esterification of 1 mol of dicarboxylic acid such as phthalic acid, terephthalic acid, oxalic acid, adipic acid and 2 mol of epichlorohydrin Shi compounds; and the like. An epoxy compound may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  More specifically, as the epoxy compound, 1,4-bis (2 ′, 3′-epoxypropyloxy) butane, 1,3,5-triglycidyl isocyanurate, 1,3-diglycidyl-5- (γ -Acetoxy-β-oxypropyl) isosinurate, sorbitol polyglycidyl ethers, polyglycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, diglyceryl polyglycidyl ether, 1,3,5-triglycidyl (2-hydroxyethyl) ) Epoxy compounds such as isocyanurate, glycerol polyglycerol ethers and trimethylolpropane polyglycidyl ether are preferable. Specific examples of commercially available products include “Denacol (Denacol EX-52) manufactured by Nagase ChemteX Corporation. 1, EX-614B etc.) ”series and the like.

  The amount of the epoxy compound is usually 2 parts by weight or more, preferably 5 parts by weight or more, more preferably 8 parts by weight or more, and usually 20 parts by weight or less, preferably 16 parts by weight or less based on 100 parts by weight of the resin A. More preferably, it is 14 parts by weight or less. Since the reaction between the epoxy compound and the resin A proceeds sufficiently by setting the amount of the epoxy compound to be equal to or higher than the lower limit value of the above range, the mechanical strength of the easy-adhesion layer can be appropriately improved, and the upper limit value or less. By doing so, the residue of the unreacted epoxy compound can be reduced, and the mechanical strength of the easy-adhesion layer can be appropriately improved.

  The amount of the epoxy compound in the resin A having a polar group is preferably 0.2 times or more, more preferably 0.4 times, based on the weight, with respect to the amount of the epoxy compound equivalent to the polar group of the resin A. It is more than double, particularly preferably 0.6 times or more, preferably 1.4 times or less, more preferably 1.2 times or less, and particularly preferably 1.0 times or less. Here, the amount of the epoxy compound equivalent to the polar group of the resin A refers to the theoretical amount of the epoxy compound that can react with the total amount of the polar group of the resin A without excess or deficiency. The polar group of the resin A can react with the epoxy group of the epoxy compound. By keeping the amount of the epoxy compound within the above range, the reaction between the polar group and the epoxy compound can proceed to an appropriate level, and the mechanical strength of the easy-adhesion layer can be effectively improved.

<Carbodiimide compound>
As the carbodiimide compound, a compound having two or more carbodiimide groups in the molecule can be used. A carbodiimide compound is usually synthesized by a condensation reaction of an organic diisocyanate. Here, the organic group of the organic diisocyanate used for the synthesis of the compound having two or more carbodiimide groups in the molecule is not particularly limited, and either aromatic or aliphatic, or a mixture thereof can be used. However, an aliphatic type is particularly preferable from the viewpoint of reactivity.

  As the synthetic raw material, organic isocyanate, organic diisocyanate, organic triisocyanate and the like are used. As examples of organic isocyanates, aromatic isocyanates, aliphatic isocyanates, and mixtures thereof can be used. Specifically, 4,4′-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane Diisocyanate, xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-phenylene diisocyanate, etc. are used. As organic monoisocyanates, isophorone isocyanate, phenyl isocyanate are used. Cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate and the like are used.

 As the carbodiimide compound, for example, “Carbodilite (Carbodilite V-02, V-02-L2, SV-02, V-04, E-02, etc.)” series manufactured by Nisshinbo Chemical Co., Ltd. is commercially available. The carbodiimide compound can be added in an amount of 1 to 200% by mass, more preferably 5 to 100% by mass with respect to the resin A.

<Oxazoline compound>
As the oxazoline compound, a general formula represented by the following chemical formula 1 (wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same or different and are a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, a phenyl group or a substituted group). A polymer having an oxazoline group represented by a phenyl group) can be used. As this oxysazoline compound, for example, addition-polymerizable oxazoline is essential, and monomer components containing other unsaturated monomers as necessary are solution-polymerized in an aqueous medium by a conventionally known polymerization method. Can be obtained.

 Examples of the addition polymerizable oxazoline include a general formula shown in the following chemical formula 2;

In the formula, R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same as described above. R ⁸ represents an acyclic organic group having an addition polymerizable unsaturated bond. Can be mentioned. Specific examples of such a compound include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2- Examples thereof include oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and one or more can be used. Among these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

 The amount of the addition-polymerizable oxazoline compound used is not particularly limited. For example, the amount is preferably 5% by weight or more with respect to 100% by weight of all monomer components used for producing the oxazoline compound. If it is less than 5% by weight, the degree of curing becomes insufficient, and durability, water resistance and the like may be impaired. Further, the other unsaturated monomer is not particularly limited as long as it is a monomer that can be copolymerized with an addition-polymerizable oxazoline and does not react with the oxazoline group. Two or more species can be used.

 Examples of such oxazoline compounds include Epocros WS-500 and WS-700 for water-soluble types, and Epocros K-2010, K-2020, and K-2030 (manufactured by Nippon Shokubai Co., Ltd.) for emulsion types. In particular, a water-soluble type highly reactive with the main agent is preferable.

 The amount of the oxazoline compound used is such that the molar ratio (the number of moles of polar groups / the number of moles of oxazoline groups) of a polar group such as a carboxyl group that the reactant has and the oxazoline group that the oxazoline compound has is 100/20 to 100 / 100 is preferable. If the molar ratio of the oxazoline group to the polar group is less than 100/20, an unreacted polar group may remain, and if it exceeds 100/100, an excess oxazoline group may be generated and the hydrophilic group may increase. In addition, when using another hardening | curing agent together as a hardening | curing agent, it is preferable to set it as the said molar ratio.

 Here, when the resin A has a carboxyl group, in the reaction between the resin A and the oxazoline compound, when the carboxyl group is neutralized, the oxazoline group and the carboxylate are difficult to react. The reactivity can be controlled by changing the type (volatility) of the amine used.

<Isocyanate compound>
As the isocyanate compound, an aliphatic, alicyclic or aromatic compound containing two or more isocyanate groups in one molecule can be used. The aliphatic diisocyanate compound is preferably an aliphatic diisocyanate having 1 to 12 carbon atoms, and examples thereof include hexamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, and hexane diisocyanate (HDI). The alicyclic diisocyanate compound is preferably an alicyclic diisocyanate having 4 to 18 carbon atoms, such as 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), and the like. Can be mentioned. Examples of the aromatic isocyanate include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, and the like.

  In addition to the crosslinking agent, the water-based resin composition may contain a curing accelerator, a curing aid, and the like. As a hardening accelerator, the well-known hardening accelerator used for easily bonding layer formation can be used. For example, when an epoxy compound is used as a crosslinking agent, a tertiary amine compound (excluding a compound having a 2,2,6,6-tetramethylpiperidyl group having a tertiary amine at the 4-position) or trifluoride A boron complex compound or the like is suitably used as the curing accelerator. A hardening accelerator can be used individually by 1 type or in combination of 2 or more types. The blending amount of the curing accelerator may be appropriately selected depending on the purpose of use. 10 parts by weight, more preferably 0.03 to 5 parts by weight.

  As a hardening adjuvant, the well-known hardening adjuvant used for easy-bonding layer formation can be used. Curing aids include oxime and nitroso curing aids such as quinonedioxime, benzoquinonedioxime, and p-nitrosophenol; maleimide curing aids such as N, N-m-phenylenebismaleimide; diallyl phthalate, triary Allyl curing aids such as lucyanurate and triallyl isocyanurate; Methacrylate curing aids such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; Vinyl curing aids such as vinyltoluene, ethylvinylbenzene and divinylbenzene; Etc. These curing aids can be used singly or in combination of two or more. The amount of the curing aid is usually in the range of 1 to 100 parts by weight, preferably 10 to 50 parts by weight with respect to 100 parts by weight of the crosslinking agent.

<Other ingredients>
The aqueous resin composition may contain other components other than those described above as long as the effects of the present invention are not significantly impaired. The aqueous resin composition usually contains water or a water-soluble solvent. Examples of the water-soluble solvent include methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, and the like. It is preferable to use water as the solvent. In addition, a solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios. The amount of the solvent to be blended is preferably set so that the viscosity of the aqueous resin composition is in a range suitable for coating.

  The aqueous resin composition preferably further contains one type or two or more types of fine particles. According to such a structure, an unevenness | corrugation can be formed in the surface of an easily bonding layer because an easily bonding layer contains microparticles | fine-particles. When such a concavo-convex is formed, when the multilayer film is formed in a long shape, the area where the easy adhesion layer comes into contact with other layers at the time of winding of the multilayer film is reduced, The slip property of the surface of an easily bonding layer can be improved by that much, and the generation | occurrence | production of a wrinkle at the time of winding the multilayer film of this invention can be suppressed.

  The average particle size of the fine particles is usually 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and usually 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less. By making the average particle diameter not less than the lower limit value of the range, the slipping property of the easy-adhesion layer can be effectively increased, and by making it not more than the upper limit value of the range, the haze can be suppressed low. In addition, as an average particle diameter of microparticles | fine-particles, a particle size distribution is measured by the laser diffraction method, and the particle size from which the cumulative volume calculated from the small diameter side in the measured particle size distribution becomes 50% (50% volume cumulative diameter D50) Is adopted.

  As the fine particles, either inorganic fine particles or organic fine particles may be used, but it is preferable to use water-dispersible fine particles. Examples of inorganic fine particles include inorganic oxides such as silica, titania, alumina, zirconia; calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate Etc. Examples of the organic fine particle material include silicone resin, fluororesin, and acrylic resin. Among these, silica is preferable. This is because the fine particles of silica are excellent in the ability to suppress the generation of wrinkles and transparency, hardly cause haze, and are not colored, and thus have less influence on the optical properties of the multilayer film of the present invention. Further, silica is good in dispersibility and dispersion stability in urethane resin. Among the silica fine particles, amorphous colloidal silica particles are particularly preferable.

  The amount of fine particles contained in the easy adhesion layer is usually 0.5 parts by weight or more, preferably 5 parts by weight or more, more preferably 8 parts by weight or more, based on 100 parts by weight of polyurethane contained in the urethane resin layer. It is 20 parts by weight or less, preferably 18 parts by weight or less, more preferably 15 parts by weight or less. By setting the amount of fine particles to be equal to or more than the lower limit of the above range, generation of wrinkles can be suppressed when the multilayer film of the present invention is wound. Moreover, the external appearance without the cloudiness of the multilayer film of this invention is maintainable by making the quantity of microparticles | fine-particles into the upper limit of the said range.

  Furthermore, in the water-based resin composition, unless the effects of the present invention are significantly impaired, for example, a heat resistance stabilizer, a weather resistance stabilizer, a leveling agent, a surfactant, an antioxidant, an antistatic agent, a slip agent, and an antiblocking agent. , Anti-fogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, cross-linking agents other than the above may be included. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

<Method for producing easy-adhesion layer>
The easy-adhesion layer can be usually produced by forming a layer made of an aqueous resin composition on the surface layer of the substrate film and curing the resin component in the coating film. In the aqueous resin composition, each component such as the resin A is usually dispersed as particles. The particle size of the particles is preferably 0.01 μm to 0.4 μm from the viewpoint of the optical properties of the multilayer film of the present invention. The particle size may be measured by a dynamic light scattering method, for example, a light scattering photometer DLS-8000 series manufactured by Otsuka Electronics Co., Ltd.

  The viscosity of the aqueous resin composition is preferably 15 mPa · s or less, particularly preferably 10 mPa · s or less. When the viscosity of the aqueous resin composition is within the above range, the aqueous resin composition can be uniformly applied to the surface of the base film. The viscosity is a value measured under a condition of 25 ° C. with a tuning fork type vibration viscometer. The viscosity of the aqueous resin composition can be adjusted by, for example, the ratio of the solvent contained in the aqueous resin composition and the particle size of the particles contained in the resin.

  Usually, when forming the layer of a water-based resin composition on the surface layer of a base film, resin is apply | coated by the apply | coating method and a coating film is formed. A coating method is not particularly limited, and a known coating method may be employed. Specific coating methods include, for example, a wire bar coating method, a dip method, a spray method, a spin coating method, a roll coating method, a gravure coating method, an air knife coating method, a curtain coating method, a slide coating method, and an extrusion coating method. Etc.

  After the layer of the aqueous resin composition is formed on the base film, the resin component forming the layer is cured to obtain the easy-adhesion layer according to the present invention. Usually, since a water-based resin composition contains a solvent, when making it harden | cure, water is dried and removed. The drying method is arbitrary, and for example, the drying may be performed by any method such as reduced pressure drying or heat drying. Especially, it is preferable to harden resin by heat drying from a viewpoint of advancing reaction, such as a crosslinking reaction, rapidly in an aqueous resin composition.

  When the resin is cured by heating, the heating temperature is appropriately set within a range in which the solvent can be dried to cure the resin component in the aqueous resin composition. However, when a stretched film is used as the base film and it is not desired to change the retardation developed in the base film, the heating temperature may be set to a temperature at which no orientation relaxation occurs in the base film. preferable. Specifically, when the glass transition temperature of the material forming the base film is Tg, it is preferably (Tg−30 ° C.) or higher, more preferably (Tg−10 ° C.) or higher, preferably (Tg + 60). ° C) or less, more preferably (Tg + 50 ° C) or less.

  Furthermore, you may perform an extending | stretching process, after forming the easily bonding layer which consists of a water-system resin composition on the surface of a base film. The stretching treatment may be performed after the aqueous resin composition is cured, but the resin component in the aqueous resin composition is cured from the viewpoint of preventing the removal of fine particles from the layer made of the aqueous resin composition. It is preferable to perform the stretching treatment before or simultaneously with the curing. Furthermore, from the viewpoint of forming a uniform easy-adhesion layer, it is more preferable to perform a stretching treatment at the same time as curing the resin component in the aqueous resin composition.

  In the stretching treatment, the base film is usually stretched to cause the base film to exhibit a desired retardation. Accordingly, the stretching method, the apparatus used for stretching, the stretching temperature, and the like may be the same as those described in the description of the base film.

  When the base film is stretched, the easy adhesion layer formed on the surface of the base material is also stretched. However, since the thickness of the easy adhesion layer is usually sufficiently smaller than the thickness of the base film, a large retardation is not exhibited in the stretched easy adhesion layer.

  Moreover, before providing an easily bonding layer, the modification | reformation process may be given to the surface of a base film, and the adhesiveness of a base film and an easily bonding layer may be improved. Examples of the surface modification treatment for the base film include energy ray irradiation treatment and chemical treatment. Examples of the energy ray irradiation treatment include corona discharge treatment, plasma treatment, electron beam irradiation treatment, ultraviolet ray irradiation treatment, etc., and from the viewpoint of treatment efficiency, corona discharge treatment and plasma treatment are preferred, and corona discharge treatment is particularly preferred. preferable. Examples of the chemical treatment include a saponification treatment, a method of immersing in an aqueous oxidizing agent solution such as potassium dichromate solution and concentrated sulfuric acid, and then washing with water.

  Furthermore, it is preferable to perform a hydrophilic surface treatment on the surface of the easy adhesion layer. The surface of the easy-adhesion layer usually serves as a bonding surface when the multilayer film of the present invention is bonded to another member. By further improving the hydrophilicity of this surface, the multilayer film of the present invention Adhesiveness with other members can be significantly improved.

  Examples of the hydrophilic surface treatment for the easily adhesive layer include corona discharge treatment, plasma treatment, saponification treatment, and ultraviolet irradiation treatment. Among these, from the viewpoint of processing efficiency, corona discharge treatment and plasma treatment are preferable, and corona discharge treatment is more preferable. As the plasma treatment, atmospheric pressure plasma treatment is preferable.

  In the hydrophilic surface treatment, the average water contact angle on the surface of the easy-adhesion layer is preferably 70 ° or less, more preferably 60 ° or less, particularly preferably 50 ° or less, and usually 20 ° or more. The standard deviation of the water contact angle is preferably 0.01 ° to 5 °. By subjecting the surface of the easy adhesion layer to such a water contact angle, the multilayer film of the present invention can be firmly bonded to other members such as a polarizer.

The water contact angle is determined by the θ / 2 method using a contact angle meter.
The average water contact angle is determined by, for example, measuring 20 water contact angles randomly selected within a range of 100 cm ^{2 on} the surface of the easily adhesive layer subjected to the hydrophilized surface treatment, and calculating the average of the measured values. Calculated. The standard deviation of the water contact angle is calculated from this measured value. By performing the hydrophilization treatment, a functional group such as a hydroxy group, a carboxyl group, a carbonyl group, an amino group, or a sulfonic acid group can be introduced on the surface of the easy adhesion layer.

  For the corona discharge treatment, the electrode structure is preferably a wire electrode, a planar electrode, or a roll electrode. In order to make the discharge uniform, it is preferable to carry out the treatment by sandwiching a dielectric between the film to be treated and the electrode. Examples of the material of the electrode include metals such as iron, copper, aluminum, and stainless steel. Examples of the electrode shape include a thin plate shape, a knife edge shape, and a brush shape.

  As the dielectric, a structure having a relative dielectric constant of 10 or more and a structure in which both electrodes are sandwiched between the dielectrics is preferable. Examples of dielectric materials include ceramics; plastics such as silicon rubber, polytetrafluoroethylene, and polyethylene terephthalate; glass; quartz; silicon dioxide; metal oxides such as aluminum oxide, zirconium dioxide, and titanium dioxide; barium titanate, and the like. And the like. In particular, it is advantageous to interpose a solid dielectric having a relative dielectric constant of 10 or more (under an environment of 25 ° C.) in that corona discharge treatment can be performed at a low voltage and at a high speed. Examples of the solid dielectric having a relative dielectric constant of 10 or more include metal oxides such as zirconium dioxide and titanium dioxide; oxides such as barium titanate; and silicon rubber. The thickness of the dielectric is preferably in the range of 0.3 mm to 1.5 mm. If the thickness of the dielectric is too thin, dielectric breakdown is likely to occur, and if it is too thick, the applied voltage is increased, which may reduce efficiency.

  The distance between the film to be treated and the electrode is preferably 0.5 mm to 10 mm. If it is less than 0.5 mm, only a thin film can pass between the electrodes. For this reason, when there exists a thick part, such as a seam, for example, when a thick part of a film passes between electrodes, a film may be damaged. Moreover, since an applied voltage will become high when it exceeds 10 mm, a power supply may become large and discharge may become a streamer shape.

  The output of the corona discharge treatment is preferably performed under the condition that the damage to the surface to be treated is as small as possible. Specifically, it is preferably 0.02 kW or more, more preferably 0.04 kW or more, preferably 5 kW or less, more preferably Is 2 kW or less. Further, within this range, it is a preferable corona discharge treatment method to perform the corona discharge treatment several times with the lowest possible output.

The density of the corona discharge treatment is such that the average water contact angle of the surface of the base film subjected to the corona discharge treatment is usually 20 ° to 70 °, more preferably 20 ° to 50 °. It is preferable to adjust so that the standard deviation can be within a range of 0.01 ° to 5 °. Specifically, the density of the corona discharge treatment is preferably 1 W · min / m ² or more, more preferably 5 W · min / m ² or more, particularly preferably 10 W · min / m ² or more, preferably 1000 W · Min / m ² or less, more preferably 500 W · min / m ² or less, particularly preferably 300 W · min / m ² or less. If the treatment density is too low, the application property of the water-based resin tends to be lowered. In addition, when the treatment density is too high, the treated surface is destroyed and the adhesion tends to be lowered.

  The frequency of the corona discharge treatment is preferably 5 kHz or more, more preferably 10 kHz or more, preferably 100 kHz or less, more preferably 50 kHz or less. If the frequency is too low, the uniformity of the corona discharge treatment is deteriorated, and the corona discharge treatment may be uneven. In addition, if the frequency becomes too high, there is no particular problem when performing high-output corona discharge treatment, but it becomes difficult to perform stable treatment when performing low-output corona discharge treatment. There is a risk of unevenness.

  In the corona discharge treatment, discharge can be generated in a finer state by surrounding the electrode with a casing, putting an inert gas inside the casing, and applying gas to the electrode part. As an inert gas, helium, argon, nitrogen etc. are mentioned, for example. In addition, an inert gas may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  When plasma treatment is performed as the hydrophilization surface treatment, examples of the plasma discharge treatment include glow discharge treatment and flame plasma treatment. As the glow discharge, either a vacuum glow discharge process performed under vacuum or an atmospheric pressure glow discharge process performed under atmospheric pressure can be used. Among these, from the viewpoint of productivity, atmospheric pressure glow discharge treatment performed under atmospheric pressure is preferable. The atmospheric pressure is in the range of 700 to 780 Torr.

  In the glow discharge treatment, a film to be treated is placed between opposing electrodes, a plasma-exciting gas is introduced into the apparatus, and a high-frequency voltage is applied between the electrodes to excite the gas between the electrodes. Glow discharge is performed. This further increases the hydrophilicity of the treated surface.

  A plasma-excitable gas refers to a gas that is plasma-excited under the above conditions. Examples of the plasma-exciting gas include rare gases such as argon, helium, neon, krypton, and xenon; nitrogen; carbon dioxide; chlorofluorocarbons such as tetrafluoromethane and mixtures thereof; and inert gases such as argon and neon. , A reactive gas capable of imparting a polar functional group such as a carboxyl group, a hydroxyl group or a carbonyl group; In addition, plasma excitation gas may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The frequency of the high frequency voltage in the plasma treatment is preferably in the range of 1 kHz to 100 kHz, and the magnitude of the voltage is preferably in the range in which the electric field strength when applied to the electrode is in the range of 1 kV / cm to 100 kV / cm. .

  When the saponification treatment is performed as the hydrophilic surface treatment, the alkali saponification treatment is suitable as the saponification treatment. Examples of the treatment method include a dipping method and an alkaline solution coating method, but the dipping method is preferable from the viewpoint of productivity.

  The dipping method in saponification is a technique in which a film to be treated is immersed in an alkaline solution under appropriate conditions, and all surfaces having reactivity with alkali on the entire surface of the film are saponified. It is preferable from the viewpoint of cost because it does not require any equipment. The alkaline liquid is preferably a sodium hydroxide aqueous solution. The concentration of the alkaline solution is preferably 0.5 mol / l or more, more preferably 1 mol / l or more, preferably 3 mol / l or less, more preferably 2 mol / l or less. The liquid temperature of the alkaline solution is preferably 25 ° C. or higher, more preferably 30 ° C. or higher, preferably 70 ° C. or lower, more preferably 60 ° C. or lower. In order to set the average water contact angle of the treated surface and the standard deviation of the water contact angle within a desired range, for example, the dipping time is appropriately adjusted.

  After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by immersing in a dilute acid so that the alkali component does not remain in the treated film.

When performing ultraviolet irradiation treatment as a hydrophilic treatment, the wavelength of ultraviolet rays to be irradiated is usually 100 nm to 400 nm. The output value of the lamp, which is an ultraviolet light source, is usually 120 W or more, preferably 160 W or more, and is usually 240 W or less, preferably 200 W or less. The amount of UV irradiation is preferably 100 mJ / cm ² or more, more preferably 200 mJ / cm ² or more, and particularly preferably 300 mJ / cm ² or more when expressed as the total amount of UV light integrated with respect to the UV irradiation object. , and the preferably 2,000 mJ / cm ² or less, more preferably 1,500 mJ / cm ² or less, particularly preferably 1,000 mJ / cm ² or less. The total amount of integrated light quantity is a value determined by the illuminance of the ultraviolet irradiation lamp and the line speed (film moving speed), and is measured, for example, by an ultraviolet integrated illuminometer (EYEUV METER UVPF-A1).

  The thickness of the easy-adhesion layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, particularly preferably 0.02 μm or more, more preferably 5 μm or less, more preferably 2 μm or less, and particularly preferably 1 μm or less. Within the above range, sufficient adhesive strength between the base film and the easy-adhesion layer can be obtained, and defects such as warpage of the multilayer film of the present invention can be eliminated.

The ratio _t 2 / _{t 1} with thickness _{t 2} of the thickness _{t 1} and the adhesion layer of the base film is preferably 0.0003 or more, more preferably more than 0.0010, particularly preferably 0.0025 or more, 0.0100 or less is preferable, 0.0080 or less is more preferable, and 0.0050 or less is particularly preferable. Thereby, the transparency of the multilayer film of the present invention can be improved. In addition, when the multilayer film of the present invention includes only _one base film, the thickness of the base film becomes the thickness t1, and when the multilayer film of the present invention includes two or more base film, these The total thickness of the base film is the thickness t ₁ . Further, in the case when the multilayer film of the present invention comprises an easy-adhesion layer only one layer is provided the thickness of the thickness t ₂ next to the adhesive layer, the multilayer film is readily adhesive layer of the present invention two or more layers thereof the total thickness of the adhesive layer is a thickness t ₂ of the.

  The difference in interface refractive index between the base film and the easy-adhesion layer is preferably 0.05 or less. When the interface refractive index difference is within the above range, it is possible to suppress light loss when light is transmitted through the multilayer film of the present invention.

<Other layers>
The multilayer film of the present invention may include other layers on the surface of the base film on which the easy adhesion layer is not formed unless departing from the gist of the present invention. Examples thereof include an antireflection layer, a hard coat layer, an antistatic layer, an antiglare layer, an antifouling layer, a separator film and the like.

<Physical properties of multilayer film>
In the multilayer film of the present invention, the total light transmittance in terms of 1 mm thickness is preferably 80% or more and more preferably 90% or more from the viewpoint of stably exhibiting the function as an optical member. preferable. The light transmittance can be measured using a spectrophotometer (manufactured by JASCO Corporation, ultraviolet-visible near-infrared spectrophotometer “V-570”) in accordance with JIS K0115.

  The multilayer film of the present invention has a haze in terms of 1 mm thickness of preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. By setting the haze to a low value, the sharpness of the display image of the display device incorporating the multilayer film according to the present invention can be enhanced. Here, the haze is an average value obtained by measuring five points using a “turbidimeter NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K7361-1997.

  The multilayer film of the present invention may be a retardation film having a retardation in the plane or in the thickness direction. The specific retardation range is set according to the use of the multilayer film of the present invention. When a specific range is given, it is usually selected appropriately from the range of 10 nm to 500 nm in the in-plane retardation Re and the range of −500 nm to 500 nm in the thickness direction retardation Rth. The in-plane retardation Re is defined as the refractive index nx in the slow axis direction of the film, the refractive index ny in the direction perpendicular to the slow axis in the plane, the refractive index nz in the thickness direction, and the average thickness D of the film. Sometimes, it is a value defined by (nx−ny) × D. The thickness direction retardation Rth is a value defined by ((nx + ny) / 2−nz) × D.

  In the multilayer film of the present invention, the variation in the in-plane retardation Re is usually within 10 nm, preferably within 5 nm, and more preferably within 2 nm. By setting the variation of the in-plane retardation Re within the above range, when the multilayer film of the present invention is used as a retardation film for a liquid crystal display device, display quality can be improved. Here, the variation in the in-plane retardation Re is obtained when the in-plane retardation Re at the light incident angle of 0 ° (in which the incident light beam and the surface of the base film are orthogonal) is measured in the width direction of the film. Is the difference between the maximum value and the minimum value of the in-plane phase difference Re.

  The content of the residual volatile component in the multilayer film of the present invention is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and further preferably 0.02% by weight or less. By setting the content of the volatile component in the above range, the dimensional stability is improved, and the temporal change of the in-plane retardation Re and the thickness direction retardation Rth of the multilayer film of the present invention can be reduced.

  The multilayer film of the present invention may have a dimension in the TD direction (also referred to as a transverse direction, usually coincides with the width direction) of, for example, 1000 mm to 3000 mm. Moreover, although the multilayer film of this invention does not have a restriction | limiting in the dimension of the MD direction (it is also called the vertical direction. Usually, it corresponds to a longitudinal direction), It is preferable that it is a long film. Here, the “long” film means a film having a length of at least 5 times the width of the film, preferably a length of 10 times or more, specifically a roll. It has a length enough to be wound up into a shape and stored or transported.

<Polarizing plate>
You may use the multilayer film of this invention for arbitrary uses as an optical film. However, since the multilayer film of the present invention has the advantage that it is excellent in adhesiveness with other members and the adhesiveness is not easily lowered even under high humidity, from the viewpoint of effectively utilizing this advantage, It is preferable to apply to the use which is bonded to the member. If the example of a specific use is given, it is preferable to use the multilayer film of this invention as a polarizing plate protective film.

  The polarizing plate usually includes a polarizer and a polarizing plate protective film. Accordingly, when the multilayer film of the present invention is used as a polarizing plate protective film, the multilayer film of the present invention is usually bonded to a polarizer.

  A polarizing plate can be manufactured by bonding together the easily bonding layer of the multilayer film of this invention, and a polarizer, for example. At the time of bonding, the polarizer may be directly bonded to the easy-adhesive layer without using the adhesive layer, or may be bonded through the adhesive layer. Furthermore, the multilayer film of the present invention may be bonded to only one surface of the polarizer, or may be bonded to both surfaces. When the multilayer film of the present invention is bonded to only one surface of the polarizer, another highly transparent film may be bonded to the other surface of the polarizer.

  The polarizer may be produced, for example, by adsorbing iodine or a dichroic dye on a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath. Alternatively, for example, iodine or a dichroic dye may be adsorbed and stretched on a polyvinyl alcohol film, and a part of the polyvinyl alcohol unit in the molecular chain may be modified to a polyvinylene unit. Furthermore, a polarizer having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer, a multilayer polarizer, and a cholesteric liquid crystal polarizer, may be used as the polarizer. Among these, a polarizer comprising polyvinyl alcohol is preferable. The polarization degree of the polarizer is preferably 98% or more, more preferably 99% or more. The thickness (average thickness) of the polarizer is preferably 5 μm to 80 μm.

  The adhesive for adhering the polarizer and the multilayer film of the present invention is not particularly limited as long as it is optically transparent. For example, an aqueous adhesive, a solvent-type adhesive, a two-component curable adhesive, Examples thereof include a photocurable adhesive and a pressure sensitive adhesive. Among these, a water-based adhesive is preferable, and a polyvinyl alcohol-based water-based adhesive is particularly preferable. In addition, an adhesive agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

 As the photocurable adhesive, an acrylate adhesive containing urethane (meth) acrylate, hydroxyalkyl (meth) acrylate, and an acrylamide derivative can be used. First, the urethane (meth) acrylate is not particularly limited. For example, after reacting a polyisocyanate and a polyhydric alcohol, a hydroxyl group-containing (meth) acryl compound and, if necessary, a hydroxyl group-containing allyl ether. Examples include a radical polymerizable unsaturated group-containing oligomer that can be obtained by reacting a compound. Alternatively, it can also be obtained by reacting a hydroxyl group-containing (meth) acrylic compound with a polyhydric alcohol and then further reacting with a polyisocyanate. Among these, the use of urethane (meth) acrylate having 2 to 3 double bonds per molecule and having a number average molecular weight per double bond of 500 to 3000 is adhesive strength and flexibility. It is preferable because it is easy to balance photocurability and viscosity. The blending amount of the urethane (meth) acrylate needs to be 30 to 50% by weight, and if it is less than 30% by weight, the adhesive layer tends to be brittle, and if it exceeds 50% by weight, the overall viscosity is high. Not only is it likely to occur, but the adhesive strength decreases, which is not preferable.

 Examples of the hydroxyalkyl (meth) acrylate include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate, among which hydroxyethyl methacrylate is preferable. The compounding amount of the hydroxyalkyl (meth) acrylate needs to be 13 to 40% by weight, and if it is less than 13% by weight, the hydrophilicity of the entire adhesive composition is lowered, and particularly the adhesive strength to the polyvinyl alcohol polarizing film is lowered. Therefore, it is not preferable, and if it exceeds 40% by weight, the adhesive layer not only becomes brittle, but also the photocurability decreases, which is not preferable.

 Acrylamide derivatives include N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylaminoethylacrylamide, N, N-dimethylaminopropylacrylamide, N-isopropylacrylamide, and N, N-dimethylaminopropylacrylamide. , N-hydroxyethyl acrylamide, particularly N, N-diethyl acrylamide, N-isopropyl acrylamide, N, N-dimethylaminopropyl acrylamide, N-hydroxyethyl acrylamide, or 0-30. It is preferable to blend in the range of 1% by weight, preferably 1 to 30% by weight.

  The photocurable adhesive preferably contains 30-40% by weight of isobornyl (meth) acrylate in addition to the components described above. By blending isobornyl (meth) acrylate, heat resistance is imparted to the adhesive layer, and the viscosity can be adjusted to improve coating performance without deteriorating adhesion performance. A suitable viscosity of the adhesive composition of the present invention is 23 ° C., 20 to 5000 mPa, preferably 30 to 3000 mPa, and more preferably 50 to 1500 mPa.

  Furthermore, it is preferable to use 2 to 10% by weight of a photopolymerization initiator in the photocurable adhesive composition of the present invention. Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4 -Chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methyl Propan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2 Chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino - propan-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the like.

  The average thickness of the adhesive layer is preferably 0.05 μm or more, more preferably 0.1 μm or more, preferably 5 μm or less, more preferably 1 μm or less.

  Although there is no restriction | limiting in the method of bonding the multilayer film of this invention, and a polarizer, For example, after apply | coating an adhesive agent as needed to one surface of a polarizer, a polarizer and this invention are used using a roll laminator. The method of laminating | stacking with a multilayer film and drying as needed is preferable. The drying time and drying temperature are appropriately selected according to the type of adhesive.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below, and may be arbitrarily changed without departing from the gist of the present invention and its equivalent scope. May be implemented. In the following description, “parts” and “%” indicating amounts are based on weight unless otherwise specified. In addition, the operations described below were performed under normal temperature and normal pressure conditions unless otherwise specified.

<Production Example 1: Production of base film>
Pellets of alicyclic structure-containing polymer resin (ZEONOR 1430, manufactured by Nippon Zeon Co., Ltd .; glass transition temperature 135 ° C.) were dried at 70 ° C. for 2 hours using a hot air dryer in which air was circulated. Then, using a T-die type film melt extrusion molding machine having a resin melt kneader equipped with a 65 mm diameter screw, under a molding condition of a molten resin temperature of 270 ° C. and a T die width of 500 mm, a thickness of 100 μm and a length of 1000 m A base film was produced. This base film is a base film made of an alicyclic structure-containing polymer resin.

<Production Example 2: Production of Polarizer>
A polyvinyl alcohol film having a thickness of 80 μm was dyed in a 0.3% iodine aqueous solution. Thereafter, the film was stretched 5 times in 4% boric acid aqueous solution and 2% potassium iodide aqueous solution, and then dried at 50 ° C. for 4 minutes to produce a polarizer.

<Production Example 3: Preparation of adhesive liquid>
Water was added to goosephimer Z410 (manufactured by Nippon Synthetic Chemical Industry, polyvinyl alcohol containing an acetoacetyl group) to dilute to a solid content of 3% to produce an adhesive solution.

<Example 1>
<Preparation of aqueous resin composition 1>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 210 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. An epoxy compound, Denacol EX-521 (manufactured by Nagase ChemteX Corporation), 20 parts, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size of 100 nm), and water were blended, and the solid content was 5%. A liquid aqueous resin composition 1 was obtained.

<Manufacture of multilayer film>
Using a corona treatment device (Kasuga Denki Co., Ltd.), the surface of the base film obtained in Production Example 1 was subjected to discharge treatment under the conditions of an output of 300 W, an electrode length of 240 mm, a work electrode distance of 3.0 mm, and a conveying speed of 4 m / min. Was given.

  The liquid aqueous resin composition 1 was applied to the surface of the base film subjected to the discharge treatment using a roll coater so that the dry film thickness was 0.5 μm. Then, using a tenter-type transverse stretching machine, the both ends of the base film were held with clips and stretched at a stretching temperature of 140 ° C. for 40 seconds and continuously stretched uniaxially at a stretching ratio of 2.0 times. Both ends were cut and removed. Thereby, the process of drying the apply | coated aqueous resin composition 1 and the process of extending | stretching a film were implemented simultaneously, the easily bonding layer was formed in the surface of a base film, and the orientation axis corresponded to the width direction. A stretched multilayer film 1 was obtained.

<Example 2>
A stretched multilayer film 2 was produced in the same manner as in Example 1 except that the following aqueous resin composition 2 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 2>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 210 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. 20 parts of carbodilite V-02-L2 (Nisshinbo Chemical Co., Ltd.) which is a carbodiimide compound, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water are blended to obtain a solid content of 5%. A liquid aqueous resin composition 2 was obtained.

<Example 3>
A stretched multilayer film 3 was produced in the same manner as in Example 1 except that the following aqueous resin composition 3 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 3>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 210 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. A carbodiimide compound, carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.) 20 parts, sebacic acid dihydrazide 5 parts, silica fine particles (average particle size 100 nm) 8 parts, and water are mixed to form a liquid with a solid content of 5%. Water-based resin composition 3 was obtained.

<Example 4>
A stretched multilayer film 4 was produced in the same manner as in Example 1 except that the following aqueous resin composition 4 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 4>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 210 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. An oxazoline compound, Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 20 parts, sebacic acid dihydrazide, 5 parts, silica fine particles (average particle size: 100 nm), 8 parts of water and water are blended to form a liquid with a solid content of 5%. An aqueous resin composition 4 was obtained.

<Example 5>
A stretched multilayer film 5 was produced in the same manner as in Example 1 except that the following aqueous resin composition 5 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 5>
As an aqueous dispersion of a polyurethane resin, which is a resin A having a polar group, Superflex 130 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. An epoxy compound, Denacol EX-521 (manufactured by Nagase ChemteX Corporation), 20 parts, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size of 100 nm), and water were blended, and the solid content was 5%. A liquid aqueous resin composition 5 was obtained.

<Example 6>
A stretched multilayer film 6 was produced in the same manner as in Example 1 except that the following aqueous resin composition 6 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 6>
As an aqueous dispersion of a polyurethane resin, which is a resin A having a polar group, Superflex 130 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. 20 parts of carbodilite V-02-L2 (Nisshinbo Chemical Co., Ltd.) which is a carbodiimide compound, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water are blended to obtain a solid content of 5%. Liquid aqueous resin composition 6 was obtained.

<Example 7>
A stretched multilayer film 7 was produced in the same manner as in Example 1 except that the following aqueous resin composition 7 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 7>
As an aqueous dispersion of a polyurethane resin, which is a resin A having a polar group, Superflex 130 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. A carbodiimide compound, carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.) 20 parts, sebacic acid dihydrazide 5 parts, silica fine particles (average particle size 100 nm) 8 parts, and water are mixed to form a liquid with a solid content of 5%. An aqueous resin composition 7 was obtained.

<Example 8>
A stretched multilayer film 8 was produced in the same manner as in Example 1 except that the following aqueous resin composition 8 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 8>
As an aqueous dispersion of a polyurethane resin, which is a resin A having a polar group, Superflex 130 (produced by Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts. An oxazoline compound, Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 20 parts, sebacic acid dihydrazide, 5 parts, silica fine particles (average particle size: 100 nm), 8 parts of water and water are blended to form a liquid with a solid content of 5%. An aqueous resin composition 8 was obtained.

<Example 9>
A stretched multilayer film 9 was produced in the same manner as in Example 1 except that the following aqueous resin composition 9 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 9>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 150HS (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester / ether polyurethane resin) is taken in an amount of 100 parts of the polyurethane resin contained, Here, 20 parts of an epoxy compound, Denacol EX-521 (manufactured by Nagase ChemteX), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water are blended to obtain a solid content of 5 % Liquid aqueous resin composition 9 was obtained.

<Example 10>
A stretched multilayer film 10 was produced in the same manner as in Example 1 except that the following aqueous resin composition 10 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 10>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 150HS (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester / ether polyurethane resin) is taken in an amount of 100 parts of the polyurethane resin contained, A carbodiimide compound, carbodilite V-02-L2 (Nisshinbo Chemical Co., Ltd.) 20 parts, sebacic acid dihydrazide 5 parts, silica fine particles (average particle size 100 nm) 8 parts, and water are blended to obtain a solid content. A 5% liquid aqueous resin composition 10 was obtained.

<Example 11>
A stretched multilayer film 11 was produced in the same manner as in Example 1 except that the following aqueous resin composition 11 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 11>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 150HS (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester / ether polyurethane resin) is taken in an amount of 100 parts of the polyurethane resin contained, Here, 20 parts of carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.), which is a carbodiimide compound, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water are blended, and the solid content is 5%. A liquid aqueous resin composition 11 was obtained.

<Example 12>
A stretched multilayer film 12 was produced in the same manner as in Example 1 except that the following aqueous resin composition 12 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 12>
As an aqueous dispersion of a polyurethane resin that is a resin A having a polar group, Superflex 150HS (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ester / ether polyurethane resin) is taken in an amount of 100 parts of the polyurethane resin contained, Here, 20 parts of Epocross WS-700 (made by Nippon Shokubai Co., Ltd.), which is an oxazoline compound, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle diameter 100 nm), and water are blended, and the solid content is 5%. Liquid aqueous resin composition 12 was obtained.

<Example 13>
A stretched multilayer film 13 was produced in the same manner as in Example 1 except that the following aqueous resin composition 13 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 13>
Superflex 870 (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) as an aqueous dispersion of polyurethane resin, which is resin A having a polar group, is taken in an amount such that the polyurethane resin contained is 100 parts. An epoxy compound, Denacol EX-521 (manufactured by Nagase ChemteX Corporation), 20 parts, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size of 100 nm), and water were blended, and the solid content was 5%. A liquid aqueous resin composition 13 was obtained.

<Example 14>
A stretched multilayer film 14 was produced in the same manner as in Example 1 except that the following aqueous resin composition 14 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 14>
Superflex 870 (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) as an aqueous dispersion of polyurethane resin, which is resin A having a polar group, is taken in an amount such that the polyurethane resin contained is 100 parts. 20 parts of carbodilite V-02-L2 (Nisshinbo Chemical Co., Ltd.) which is a carbodiimide compound, 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water are blended to obtain a solid content of 5%. A liquid aqueous resin composition 14 was obtained.

<Example 15>
A stretched multilayer film 15 was produced in the same manner as in Example 1 except that the following aqueous resin composition 15 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 15>
Superflex 870 (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) as an aqueous dispersion of polyurethane resin, which is resin A having a polar group, is taken in an amount such that the polyurethane resin contained is 100 parts. A carbodiimide compound, carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.) 20 parts, sebacic acid dihydrazide 5 parts, silica fine particles (average particle size 100 nm) 8 parts, and water are mixed to form a liquid with a solid content of 5%. An aqueous resin composition 15 was obtained.

<Example 16>
A stretched multilayer film 16 was produced in the same manner as in Example 1 except that the following aqueous resin composition 16 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 16>
Superflex 870 (Daiichi Kogyo Seiyaku Co., Ltd., carboxyl group-containing ether polyurethane resin) as an aqueous dispersion of polyurethane resin, which is resin A having a polar group, is taken in an amount such that the polyurethane resin contained is 100 parts. An oxazoline compound, Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 20 parts, sebacic acid dihydrazide, 5 parts, silica fine particles (average particle size: 100 nm), 8 parts of water and water are blended to form a liquid with a solid content of 5%. An aqueous resin composition 16 was obtained.

<Example 17>
A stretched multilayer film 17 was produced in the same manner as in Example 1 except that the following aqueous resin composition 17 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 17>
As an aqueous dispersion of a polyurethane resin which is a resin A having a polar group, hydran WLS201 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts, and this is an epoxy compound. A liquid aqueous resin having a solid content of 5%, comprising 20 parts of Denacol EX-521 (manufactured by Nagase ChemteX Corp.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water. A composition 17 was obtained.

<Example 18>
A stretched multilayer film 18 was produced in the same manner as in Example 1 except that the following aqueous resin composition 18 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 18>
As an aqueous dispersion of a polyurethane resin which is a resin A having a polar group, hydran WLS201 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts, and this is a carbodiimide compound. Carbodilite V-02-L2 (manufactured by Nisshinbo Chemical Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water are mixed to form a liquid aqueous system having a solid content of 5%. A resin composition 18 was obtained.

<Example 19>
A stretched multilayer film 19 was produced in the same manner as in Example 1 except that the following aqueous resin composition 19 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 19>
As an aqueous dispersion of a polyurethane resin which is a resin A having a polar group, hydran WLS201 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts, and this is a carbodiimide compound. Carbodilite SV-02 (manufactured by Nisshinbo Chemical Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water are blended to form a liquid aqueous resin composition having a solid content of 5%. Product 19 was obtained.

<Example 20>
A stretched multilayer film 20 was produced in the same manner as in Example 1 except that the following aqueous resin composition 20 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 20>
As an aqueous dispersion of a polyurethane resin which is a resin A having a polar group, hydran WLS201 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts, and this is an oxazoline compound. 20 parts of Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle diameter 100 nm), and water are mixed to form a liquid aqueous resin composition having a solid content of 5%. Product 20 was obtained.

<Example 21>
A stretched multilayer film 21 was produced in the same manner as in Example 1 except that the following aqueous resin composition 21 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 21>
As an aqueous dispersion of a polyurethane resin which is a resin A having a polar group, Hydran WLS202 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) is taken in an amount such that the polyurethane resin contained is 100 parts, and this is an epoxy compound. A liquid aqueous resin having a solid content of 5%, comprising 20 parts of Denacol EX-521 (manufactured by Nagase ChemteX Corp.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water. A composition 21 was obtained.

<Example 22>
A stretched multilayer film 22 was produced in the same manner as in Example 1 except that the following aqueous resin composition 22 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 22>
Hydran WLS202 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) as an aqueous dispersion of a polyurethane resin, which is a resin A having a polar group, is taken in an amount such that the polyurethane resin contained is 100 parts, which is a carbodiimide compound. Carbodilite V-02-L2 (manufactured by Nisshinbo Chemical Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water are mixed to form a liquid aqueous system having a solid content of 5%. A resin composition 22 was obtained.

<Example 23>
A stretched multilayer film 23 was produced in the same manner as in Example 1 except that the following aqueous resin composition 23 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 23>
Hydran WLS202 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) as an aqueous dispersion of a polyurethane resin, which is a resin A having a polar group, is taken in an amount such that the polyurethane resin contained is 100 parts, which is a carbodiimide compound. Carbodilite SV-02 (manufactured by Nisshinbo Chemical Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water are blended to form a liquid aqueous resin composition having a solid content of 5%. Product 23 was obtained.

<Example 24>
A stretched multilayer film 24 was produced in the same manner as in Example 1 except that the following aqueous resin composition 24 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 24>
As an aqueous dispersion of a polyurethane resin which is a resin A having a polar group, Hydran WLS202 (manufactured by DIC, carboxyl group-containing ether polyurethane resin) is taken in an amount of 100 parts of the polyurethane resin contained therein, and this is an oxazoline compound. 20 parts of Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle diameter 100 nm), and water are mixed to form a liquid aqueous resin composition having a solid content of 5%. Product 24 was obtained.

<Example 25>
A stretched multilayer film 25 was produced in the same manner as in Example 1 except that the following aqueous resin composition 25 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 25>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-684G (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is taken in an amount such that the polyester resin contained is 100 parts. 5 parts of solid content 5% by blending 20 parts of epoxy compound Denacol EX-521 (manufactured by Nagase ChemteX Corp.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water. A liquid aqueous resin composition 25 was obtained.

<Example 26>
A stretched multilayer film 26 was produced in the same manner as in Example 1 except that the following aqueous resin composition 26 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 26>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-684G (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is contained, and the polyester resin acrylic resin composite contained is 100 parts. Weighed, 20 parts carbodilite V-02-L2 (manufactured by Nisshinbo Chemical Co., Ltd.), 5 parts sebacate dihydrazide, 8 parts silica fine particles (average particle size 100 nm), and water were mixed here. A liquid aqueous resin composition 26 having a solid content of 5% was obtained.

<Example 27>
A stretched multilayer film 27 was produced in the same manner as in Example 1 except that the following aqueous resin composition 27 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 27>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-684G (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is taken in an amount such that the polyurethane resin contained is 100 parts. Is mixed with 20 parts carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.), 5 parts sebacic acid dihydrazide, 8 parts silica fine particles (average particle size 100 nm), and water, and 5% solid content. A liquid aqueous resin composition 27 was obtained.

<Example 28>
A stretched multilayer film 28 was produced in the same manner as in Example 1 except that the following aqueous resin composition 28 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 28>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-684G (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is taken in an amount such that the polyurethane resin contained is 100 parts. 5 parts of Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water, A liquid aqueous resin composition 28 was obtained.

<Example 29>
A stretched multilayer film 29 was produced in the same manner as in Example 1 except that the following aqueous resin composition 29 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 29>
As an aqueous dispersion of a polyester resin, which is a resin A having a polar group, pesresin A-695GE (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is taken in an amount such that the polyester resin contained is 100 parts. 5 parts of solid content 5% by blending 20 parts of epoxy compound Denacol EX-521 (manufactured by Nagase ChemteX Corp.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm) and water. A liquid aqueous resin composition 29 was obtained.

<Example 30>
A stretched multilayer film 30 was produced in the same manner as in Example 1 except that the following aqueous resin composition 30 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 30>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-695GE (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is contained, and the polyester resin acrylic resin composite contained is 100 parts. Weighed, 20 parts carbodilite V-02-L2 (manufactured by Nisshinbo Chemical Co., Ltd.), 5 parts sebacate dihydrazide, 8 parts silica fine particles (average particle size 100 nm), and water were mixed here. A liquid aqueous resin composition 30 having a solid content of 5% was obtained.

<Example 31>
A stretched multilayer film 31 was produced in the same manner as in Example 1 except that the following aqueous resin composition 31 was used instead of the aqueous resin composition 1.
<Preparation of water-based resin composition 31>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-695GE (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is taken in an amount such that the polyurethane resin contained is 100 parts. Is mixed with 20 parts carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.), 5 parts sebacic acid dihydrazide, 8 parts silica fine particles (average particle size 100 nm), and water, and 5% solid content. A liquid aqueous resin composition 31 was obtained.

<Example 32>
A stretched multilayer film 32 was produced in the same manner as in Example 1 except that the following aqueous resin composition 32 was used instead of the aqueous resin composition 1.
<Preparation of aqueous resin composition 32>
As an aqueous dispersion of a polyester resin which is a resin A having a polar group, pesresin A-695GE (manufactured by Takamatsu Yushi Co., Ltd., carboxyl group-containing polyester resin acrylic resin composite) is taken in an amount such that the polyurethane resin contained is 100 parts. 5 parts of Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.), 5 parts of sebacic acid dihydrazide, 8 parts of silica fine particles (average particle size 100 nm), and water, A liquid aqueous resin composition 32 was obtained.

<Evaluation of adhesive strength: Evaluation of adhesive strength of composite after moisture resistance test>
By bonding the surface of the easy-adhesion layer of the multilayer film produced in each Example and one side of the polarizer produced in Production Example 3 with a roll laminator using the adhesive produced in Production Example 4, polarization is achieved. A board was produced. Subsequently, the glass substrate and the surface of the polarizing plate opposite to the easy-adhesion layer were bonded to each other through a predetermined adhesive to form a composite. The obtained composite was left in a constant temperature and high humidity bath at 60 ° C. and 90% RH for 200 hours. Then, it cut | disconnected and cut with the cutter from the edge part and surface of the composite_body | complex. When peeling occurs between the polarizing plate and the glass substrate, the easy-adhesive layer and the adhesive maintain sufficient strength, and when peeling occurs between the polarizer and the multilayer film, the strength is insufficient. It was evaluated.

  In Examples 1 to 32, sufficient strength was maintained in the adhesive strength evaluation test, and all of the evaluations were “◯”.

Claims (5)

A multilayer film comprising a base film having a surface layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, and an easy-adhesion layer formed on the surface layer in the base film. And
The easy-adhesion layer is formed using an aqueous resin composition comprising a resin A having a polar group and a crosslinking agent having two or more functional groups that react with the polar group in the resin A in the molecule. Layer,
The multilayer film, wherein the functional group in the cross-linking agent is an epoxy group, a carbodiimide group, and / or an oxazoline group.   The multilayer resin according to claim 1, wherein the resin A is a polyurethane resin, an acrylic resin, and / or a polyester resin.   The multilayer film according to claim 1 or 2, wherein the aqueous resin composition further comprises one or more kinds of fine particles.   A polarizing plate protective film provided with the multilayer film in any one of Claims 1-3.   A polarizing plate comprising a polarizer and the polarizing plate protective film according to claim 4.