JP2012206343A - Multilayer film, method for producing the same, polarizing plate protective film, and polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film which includes a base material film comprising a resin that contains a polymer having an alicyclic structure or an acrylic polymer, which has high adhesive force and whose adhesive force is hardly decreased even in a high-humidity environment.SOLUTION: The multilayer film includes: the base material film having a layer comprising the resin that contains the polymer having the alicyclic structure or the acrylic polymer, on the surface thereof; and a urethane resin layer. The urethane resin layer is formed by curing a resin containing (A) polyurethane, (B) an epoxy compound, (C) one or both of primary amine and secondary amine, and (D) at least one compound selected from the group comprising tertiary amine, imidazole compounds and imidazoline compounds of 1.4-2.7 equivalent based on 1 equivalent of an epoxy group of (B) the epoxy compound.

Description

  The present invention relates to a multilayer film, a method for producing the multilayer film, and a polarizing plate protective film and a polarizing plate provided with the multilayer film.

  For example, a film made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer is known as a film used for 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, electrode substrates of liquid crystal cells constituting liquid crystal display devices, polarizing plates, protective films for polarizing plates, retardation films, viewing angle widening films, brightness enhancement films, touch panels Development for optical applications such as a film with a transparent electrode, a light guide plate, and an optical disk is being made.

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

  However, some films having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer are inferior in adhesiveness to other members. Therefore, it has been conventionally performed to provide an easy adhesion layer on the surface of the film. 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 documents 1-3).

JP 2009-274390 A JP 2002-285124 A JP 2006-201736 A

However, the easy-adhesion layer formed of a urethane resin sometimes has poor water resistance. For this reason, when a multilayer film provided with a conventional easy-adhesion layer is bonded to a polarizer, for example, and then placed in a high-temperature and high-humidity environment for a long time, the adhesive strength may be reduced.
The present invention was devised in view of the above problems, and is a multilayer film including a base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, and having an adhesive force. An object of the present invention is to provide a multi-layer film that is high and hardly deteriorates in adhesive strength even in a high humidity environment.

As a result of intensive studies to solve the above problems, the present inventor has obtained a base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer, (A) polyurethane, and (B) an epoxy compound. (C) one or both of a primary amine and a secondary amine, and (D) a urethane obtained by curing a urethane resin containing at least one compound selected from the group consisting of a tertiary amine, an imidazole compound, and an imidazoline compound. In the multilayer film comprising the resin layer, the water resistance of the urethane resin layer is specifically determined by keeping the amount of the component (D) within a predetermined range with respect to 1 equivalent of the epoxy group of the (B) epoxy compound. Therefore, the present inventors have found that the adhesive force can be hardly lowered even in a high humidity environment, and completed the present invention.
That is, the gist of the present invention is the following [1] to [12].

[1] A base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer on the surface, and a urethane resin layer,
The urethane resin layer is
(A) polyurethane,
(B) an epoxy compound,
(C) one or both of a primary amine and a secondary amine, and
(D) It includes at least one compound selected from the group consisting of a tertiary amine, an imidazole compound, and an imidazoline compound, in an amount of 1.4 to 2.7 equivalents relative to 1 equivalent of the epoxy group of the (B) epoxy compound. A multilayer film, which is a cured layer of resin.
[2] The polyurethane (A) contains an acid structure,
[1] The amount of the (B) epoxy compound is 0.2 to 1.4 times the amount of the (B) epoxy compound equivalent to the acid structure of the (A) polyurethane. Multi-layer film.
[3] The multilayer film according to [1] or [2], wherein one or both of the (C) primary amine and secondary amine is a compound having a hydrazino group.
[4] One or both of the (C) primary amine and secondary amine, and the boiling point of at least one compound selected from the group consisting of the (D) tertiary amine, imidazole compound and imidazoline compound, The multilayer film according to any one of [1] to [3], which is higher than a glass transition temperature of a resin constituting the material film.
[5] From the group consisting of (A) polyurethane, (B) epoxy compound, (C) one or both of primary amine and secondary amine, and (D) tertiary amine, imidazole compound and imidazoline compound. The multilayer film according to any one of [1] to [4], wherein the resin including at least one selected compound further includes fine particles.
[6] The multilayer film according to any one of [1] to [5], which is a retardation film.
[7] On the surface of the base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer on the surface,
(A) polyurethane,
(B) an epoxy compound,
(C) one or both of a primary amine and a secondary amine, and
(D) It includes at least one compound selected from the group consisting of a tertiary amine, an imidazole compound, and an imidazoline compound, in an amount of 1.4 to 2.7 equivalents relative to 1 equivalent of the epoxy group of the (B) epoxy compound. The manufacturing method of a multilayer film including apply | coating resin and making it harden | cure.
[8] The polyurethane (A) contains an acid structure,
[7] The amount of the (B) epoxy compound is 0.2 to 1.4 times the amount of the (B) epoxy compound equivalent to the acid structure of the (A) polyurethane. Production method.
[9] The production method according to [7] or [8], wherein one or both of the (C) primary amine and secondary amine is a compound having a hydrazino group.
[10] One or both of the (C) primary amine and secondary amine, and the boiling point of at least one compound selected from the group consisting of the (D) tertiary amine, imidazole compound and imidazoline compound, The manufacturing method as described in any one of [7]-[9] higher than the glass transition temperature of resin which comprises a material film.
[11] From the group consisting of (A) polyurethane, (B) epoxy compound, (C) one or both of primary amine and secondary amine, and (D) tertiary amine, imidazole compound and imidazoline compound. The production method according to any one of [7] to [10], wherein the resin containing at least one selected compound further contains fine particles.
[12] The production method according to any one of [7] to [11], in which the applied resin is cured and simultaneously the base film is stretched.
[13] A polarizing plate protective film comprising the multilayer film according to any one of [1] to [6].
[14] A polarizing plate comprising a polarizer and the polarizing plate protective film according to [13].

According to the present invention, a base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer is provided, the adhesive strength is high, and the adhesive strength is reduced even in a high humidity environment. It is possible to provide a multilayer film that is difficult to perform.
In addition, according to the present invention, a base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer is provided. It is possible to provide a method for producing a multilayer film that is difficult to decrease.
Furthermore, according to this invention, the polarizing plate protective film and polarizing plate provided with the multilayer film of this invention can be provided.

FIG. 1 is a diagram illustrating the results of Examples 1 to 3, 9, and 10 and Comparative Examples 1 to 3.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the embodiments and examples described below, and the gist of the present invention and its equivalent scope are described below. You may implement arbitrarily changing in the range which does not deviate. In the following description, “(meth) acryl” means “acryl” and “methacryl”.

[1. Overview]
The multilayer film of the present invention includes a base film and a urethane resin layer. Among these, the base film has a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer on the surface. 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”.

  In addition, the urethane resin layer includes (A) polyurethane, (B) epoxy compound, (C) one or both of primary amine and secondary amine, and (D) tertiary amine, imidazole compound and imidazoline compound. This is a layer obtained by curing a resin containing at least one selected compound (hereinafter sometimes referred to as “uncured urethane resin”). Hereinafter, (C) one or both of the primary amine and the secondary amine may be referred to as “component (C)”, and (D) at least one kind selected from the group consisting of a tertiary amine, an imidazole compound, and an imidazoline compound. The compound is sometimes referred to as “component (D)”.

  Usually, a urethane resin layer is provided on the surface of the layer which consists of resin containing the alicyclic structure containing polymer or acrylic polymer of a base film, and this urethane resin layer improves the adhesiveness of a base film. Furthermore, in the multilayer film of the present invention, the water resistance of the urethane resin layer is improved by keeping the equivalent of the component (D) within a specific range with respect to 1 equivalent of the epoxy group of the (B) epoxy compound. Even in a high humidity environment, it is difficult to reduce the adhesive force.

[2. Base film]
The base film has a layer made of an alicyclic structure-containing polymer resin or a layer made of an acrylic resin on the surface of the base film. 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.

[2-1. 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 glass transition temperature of the alicyclic structure-containing polymer is preferably 130 ° C. or higher, more preferably 135 ° C. or higher, preferably 150 ° C. or lower, more preferably 145 ° C. or lower. When the glass transition temperature is lower than 130 ° C., durability at high temperatures may be deteriorated. When the glass transition temperature is higher than 150 ° C., durability is improved, but normal stretching may be difficult.

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. When 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 within 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, voids are generated when the alicyclic structure-containing polymer resin containing particles exceeding the above range is stretched. 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.

[2-2. acrylic resin〕
The acrylic polymer means a polymer of acrylic acid or an acrylic acid derivative, and examples thereof include polymers and copolymers such as acrylic acid, acrylic ester, acrylamide, acrylonitrile, methacrylic acid and methacrylic ester. 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 affinity with the urethane resin 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.

[2-3. (Structure and physical properties of base film)
The base film may be a single layer film layer having only one layer, or may be a multilayer film layer having two or more layers. A polarizing plate having various characteristics can be produced by using a base film as a film layer having a multilayer structure. However, when the base film includes two or more layers, 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. At this time, a layer made of an alicyclic structure-containing polymer resin or a layer made of an acrylic resin is located only on one of the two outermost surfaces (front surface and back surface) of the base film. Alternatively, 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 layer made of acrylic resin, for example, functions such as anti-scratch, anti-reflection, anti-static, anti-glare, anti-stain The film layer which has is mentioned. 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, the total light transmittance is 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 characteristics 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 making the content of the volatile component in the above range, the dimensional stability can be 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.

[3. Urethane resin layer]
The urethane resin layer comprises (A) polyurethane, (B) epoxy compound, (C) component {ie, one or both of primary amine and secondary amine}, and (D) component {ie, tertiary amine, imidazole compound And at least one compound selected from the group consisting of imidazoline compounds} is a layer obtained by curing an uncured urethane resin. The urethane resin layer functions as an easy-adhesion layer. When the base film is bonded to another member (for example, a polarizer, etc.) via an adhesive, the adhesive between the base film and the other member by the adhesive is used. It is reinforced and more firmly bonded. That is, the urethane resin layer is a layer that reinforces the function of the adhesive, and is called a primer layer or the like as another name.

Usually, a urethane resin layer is directly provided on the surface of a layer made of an alicyclic structure-containing polymer resin or a layer made of an acrylic resin of the base film without passing through another layer such as an adhesive layer. .
The urethane resin layer may be provided on one surface of the base film or on both surfaces. By providing the urethane resin layer on both surfaces of the base film, the handleability of the base film can be effectively improved.

[3-1. (A) Polyurethane]
Examples of the polyurethane include: (i) a polyurethane obtained by reacting a component containing an average of 2 or more active hydrogens in one molecule and (ii) a polyvalent isocyanate component; or the above (i) component and ( ii) The component is urethanated in an organic solvent that is inert to the reaction and has a high affinity for water under an excess of isocyanate groups to obtain an isocyanate group-containing prepolymer, and then the prepolymer is neutralized. A polyurethane produced by chain extension using a chain extender and adding water to form a dispersion; and the like. These polyurethanes may contain an acid structure (acid residue).

  The chain extension method of the isocyanate group-containing prepolymer may be a known method. For example, water, water-soluble polyamine, glycols, etc. are used as the chain extender, and the isocyanate group-containing prepolymer and the chain extender are required. Depending on the reaction, the reaction may be carried out in the presence of a catalyst.

  The component (i) (that is, a component containing an average of 2 or more active hydrogens in one molecule) is not particularly limited, but preferably has a hydroxylic active hydrogen. Specific examples of such compounds include the following.

(1) Polyol compound As the polyol compound, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol. 1,5-pentanediol, neopentyl glycol, 1,6-hexane glycol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, tricyclodecane dimethanol 1,4-cyclohexanedimethanol, 2,2-dimethylpropanediol, 1,4-butanediol and the like.

(2) Polyether polyol As the polyether polyol, for example, an alkylene oxide adduct of the aforementioned polyol compound; a ring-opening (co) polymer of alkylene oxide and a cyclic ether (for example, tetrahydrofuran); polyethylene glycol, polypropylene glycol, ethylene Glycol-propylene glycol copolymer; glycols such as glycol, polytetramethylene glycol, polyhexamethylene glycol, polyoctamethylene glycol; and the like.

(3) Polyester polyol Examples of the polyester polyol include dicarboxylic acids such as adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, and phthalic acid, and anhydrides thereof, and those mentioned in (1) above. Obtained by polycondensation with a polyol compound such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octamethylenediol, neopentylglycol and the like under conditions of excess hydroxyl group. Etc. More specifically, for example, ethylene glycol-adipic acid condensate, butanediol-adipine condensate, hexamethylene glycol-adipic acid condensate, ethylene glycol-propylene glycol-adipic acid condensate, or lactone with glycol as an initiator. And polylactone diol obtained by ring-opening polymerization.

(4) Polyether ester polyol As the polyether ester polyol, for example, an ether group-containing polyol (for example, the polyether polyol or diethylene glycol of the above (2)) or a mixture of this and other glycols in the above (3) Examples thereof include those obtained by reacting an alkylene oxide in addition to the dicarboxylic acid or its anhydride as exemplified. More specifically, examples include polytetramethylene glycol-adipic acid condensate.

(5) Polycarbonate polyol As the polycarbonate polyol, for example, the general formula HO-R- (OC (O) -O-R) x-OH (wherein R is saturated with 1 to 12 carbon atoms) A fatty acid polyol residue, and x is the number of repeating units of the molecule, and is usually an integer of 5 to 50). These are a transesterification method in which a saturated aliphatic polyol and a substituted carbonate (for example, diethyl carbonate, diphenyl carbonate, etc.) are reacted under the condition that the hydroxyl group becomes excessive; the saturated aliphatic polyol and phosgene are reacted, or If necessary, it can be obtained by a method of further reacting a saturated aliphatic polyol thereafter.

  The compounds as exemplified in the above (1) to (5) may be used alone or in combination of two or more at any ratio.

  Examples of the component (ii) to be reacted with the component (i) (that is, the polyvalent isocyanate component) include, for example, an aliphatic, alicyclic or aromatic compound containing an average of two or more isocyanate groups in one molecule. May 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, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and the like.

  The polyurethane preferably has an acid structure. Polyurethane having an acid structure can be dispersed in water without using a surfactant or even if the amount of the surfactant is small, so that the water resistance of the urethane resin layer is expected to be improved. Is done. This is called a self-emulsifying type and means that the polyurethane can be dispersed and stabilized in water only by molecular ionicity without using a surfactant. A urethane resin layer using such a polyurethane is preferable because it does not require a surfactant and is excellent in adhesion to an alicyclic structure-containing polymer resin and an acrylic resin and can maintain high transparency. .

Examples of the acid structure include acid groups such as a carboxyl group (—COOH) and a sulfonic acid group (—SO ₃ H). In addition, the acid structure may be present in the side chain or at the terminal in the polyurethane. In addition, 1 type may be used for an acid structure and it may use it combining 2 or more types by arbitrary ratios.

  The content of the acid structure is preferably 20 mgKOH / g or more, more preferably 25 mgKOH / g or more, preferably 250 mgKOH / g or less, more preferably 150 mgKOH / g or less as the acid value in the polyurethane. If the acid value is less than 20 mgKOH / g, the water dispersibility tends to be insufficient. On the other hand, if the acid value is more than 250 mgKOH / g, the water resistance of the urethane resin layer tends to be inferior.

  As a method for introducing an acid structure into polyurethane, a conventionally used method can be used without any particular limitation. Preferable examples include dimethylol alkanoic acid by replacing some or all of the glycol components described in (2) to (4) above with a polyether polyol, polyester polyol, polyether ester polyol, etc. The method of introduce | transducing group is mentioned. Examples of the dimethylol alkanoic acid used here include dimethylol acetic acid, dimethylol propionic acid, and dimethylol butyric acid. In addition, dimethylol alkanoic acid may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Moreover, it is preferable to neutralize a part or all of the acid structure contained in the polyurethane. By neutralizing the acid structure, the water dispersibility of the polyurethane can be improved. Examples of the neutralizing agent that neutralizes the acid component include organic amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, N-methyldiethanolamine, and triethanolamine; inorganics such as sodium hydroxide, potassium hydroxide, and ammonia Bases; and the like. In addition, a neutralizing agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The number average molecular weight of the polyurethane is preferably 1,000 or more, more preferably 20,000 or more, preferably 1,000,000 or less, more preferably 200,000 or less.

As polyurethane, you may use what is marketed as a water-based urethane resin. The water-based urethane resin is a composition containing polyurethane and water, and is usually one in which polyurethane and other components contained as necessary are dispersed in water. As water-based urethane resins, for example, “Adeka Bon titer” series manufactured by Asahi Denka Kogyo Co., Ltd., “Olestar” series manufactured by Mitsui Toatsu Chemical Co., Ltd., “Bondic” series manufactured by Dainippon Ink & Chemicals, Inc., “Hydran” Series, Bayer's "Impranil" series, Japan Soflan's "Sofuranate" series, Kao's "Poise" series, Sanyo Kasei's "Samprene" series, Hodogaya Chemical Industries' The “IZerax” series, the “Superflex” series manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the “Neolet's” series manufactured by Zeneca, etc. can be used.
In addition, a polyurethane may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

[3-2. (B) Epoxy compound]
The epoxy compound is a component that functions as a crosslinking agent, and the mechanical strength of the urethane resin layer can be increased by using the epoxy compound. Moreover, the effect | action which improves adhesive force is also anticipated with the polar structure which an epoxy compound has.

  As the epoxy compound, a compound having an epoxy group is used. Usually, an epoxy compound having two or more epoxy groups per molecule is used. Thereby, a crosslinking reaction can be advanced and the mechanical strength of a urethane resin layer can be improved effectively.

  Moreover, as an epoxy compound, what is soluble in water or dispersible in water and can be emulsified is preferable. The uncured urethane resin used for forming the urethane resin layer is usually prepared as a fluid aqueous resin containing water. Here, the aqueous resin refers to a composition containing a solid content in a dissolved or dispersed state in an aqueous solvent such as water. If the epoxy group is soluble in water or can be emulsified, the application property of the water-based resin can be improved and the urethane resin layer can be easily produced.

  Examples of epoxy compounds include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexane glycol, neopentyl glycol and other glycols 1 mol. And a diepoxy compound obtained by etherification with 2 mol of epichlorohydrin; a polyepoxy compound obtained by etherification of 1 mol of polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and 2 mol or more of epichlorohydrin Epoxy 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 Epoxy compound compounds and the like; 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.

  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, usually 20 parts by weight or less, preferably 16 parts by weight or less, based on 100 parts by weight of polyurethane. The amount is preferably 14 parts by weight or less. By making the amount of the epoxy compound equal to or higher than the lower limit of the above range, the reaction between the epoxy compound and the polyurethane sufficiently proceeds, so that the mechanical strength of the urethane resin layer can be appropriately improved, and the upper limit value or less. Thus, the residual unreacted epoxy compound can be reduced, and the mechanical strength of the urethane resin layer can be appropriately improved.

  When the polyurethane has an acid structure, the amount of the epoxy compound 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 acid structure of the polyurethane. Above, particularly preferably 0.6 times or more, preferably 1.4 times or less, more preferably 1.2 times or less, particularly preferably 1.0 times or less. Here, the amount of the epoxy compound equivalent to the acid structure of the polyurethane refers to the theoretical amount of the epoxy compound that can react with the total amount of the acid structure of the polyurethane without excess or deficiency. When the polyurethane has an acid structure, the acid structure can react with the epoxy group of the epoxy compound. At this time, by keeping the amount of the epoxy compound within the above range, the reaction between the acid structure and the epoxy compound can proceed to an appropriate level, and the mechanical strength of the urethane resin layer can be effectively improved.

[3-3. (C) component]
The component (C) represents one or both of a primary amine and a secondary amine. Therefore, only a primary amine may be used as the component (C), only a secondary amine may be used as the component (C), or a primary amine and a secondary amine may be used in combination as the component (C). The component (C) is a component that functions as a crosslinking agent, and the mechanical strength of the urethane resin layer can be increased by using the component (C). Moreover, adhesive force can be improved notably by combining a polyurethane, an epoxy compound, and (C) component.

  As the component (C), those which are soluble in water or can be emulsified by being dispersed in water are preferable. As a result, when an uncured urethane resin is prepared as a water-based resin, it becomes possible to improve the applicability of the water-based resin and easily manufacture the urethane resin layer.

Examples of the component (C) include 2-amino-2-methyl-1-propanol (AMP), monoethanolamine, 2-amino-2-methyl-1,3-propanediol (AMPD), 2-amino. 2-hydroxymethyl-1,3-propane potassium hydroxide, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β (Aminoethyl) -γ-aminopropyltrimethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyl-tris (2-methoxy-ethoxy-ethoxy) silane, cyclohexylamine, hexamethylenediamine, ethylenediamine, diethylenetriamine, Tetraethylenepentamine, pentaeth N-pentamine, aminoethylethanolamine, 1,2-propanediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine , Aminoethylethanolamine, aminopropylethanolamine, aminohexylethanolamine, aminoethylpropanolamine, aminopropylpropanolamine, aminohexylpropanolamine, 5-aminopyrazole, 1-methyl-5-aminopyrazole, 1-isopropyl-5 -Aminopyrazole, 1-benzyl-5-aminopyrazole, 1,3-dimethyl-5-aminopyrazole, 1-isopropyl-3-methyl-5-aminopyrazole, 1 -Benzyl-3-methyl-5-aminopyrazole, 1-methyl-4-chloro-5-aminopyrazole, 1-methyl-4-asino-5-aminopyrazole, 1-isopropyl-4-chloro-5-aminopyrazole , Primary amines such as 3-methyl-4-chloro-5-aminopyrazole, 1-benzyl-4-chloro-5-aminopyrazole; diethanolamine, morpholine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, N Secondary amines such as phenyl-γ-aminopropyltrimethoxysilane; N-methyl-3-aminopropyltrimethoxycarboxylic acid dihydrazide, carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebatin Acid dihydrazide, dode Emissions diacid dihydrazide, isophthalic acid dihydrazide, terephthalic acid, glycolic acid dihydrazide, hydrazides compounds such polyacrylic acid dihydrazide; melamine resins; urea resins; guanamine resin; and the like. Among them, a compound having a hydrazino group (—NHNH ₂ group) such as a hydrazide compound has high reactivity, and therefore can appropriately improve the mechanical strength of the urethane resin layer, and has a relatively high boiling point. Since the heat resistance of a layer can be made high, it is especially preferable. Moreover, (C) component may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  It is preferable that the boiling point of (C) component is higher than the glass transition temperature of resin which comprises a base film. When the base film contains a plurality of types of resins, it is preferable that the boiling point of the component (C) is higher than the lowest glass transition temperature among the glass transition temperatures of those resins. When the multilayer film of the present invention is stretched or dried, it is usually stretched or dried at a temperature about the glass transition temperature of the resin constituting the base film. At this time, if the boiling point of the component (C) is high as described above, it can be stably prevented that the component (C) is vaporized and bubbles are generated in the urethane resin layer.

  The amount of component (C) is usually 0.5 parts by weight or more, preferably 1 part by weight or more, more preferably 2 parts by weight or more, and usually 40 parts by weight or less, preferably 20 parts by weight with respect to 100 parts by weight of polyurethane. Part or less, more preferably 10 parts by weight or less. The mechanical strength of the urethane resin layer can be appropriately improved by setting the amount of the component (C) to be equal to or higher than the lower limit of the above range, and the residual unreacted epoxy compound can be reduced by setting the amount of the component to the upper limit or lower. Also, the mechanical strength of the urethane resin layer can be appropriately improved.

[3-4. (D) component]
The component (D) represents at least one compound selected from the group consisting of tertiary amines, imidazole compounds and imidazoline compounds. Since the component (D) acts as a catalyst for promoting the crosslinking reaction by the epoxy group of the epoxy compound, the mechanical strength of the urethane resin layer can be increased by using the component (D). Moreover, since the chemical bond in the urethane resin layer is strengthened by the progress of the crosslinking reaction, the water resistance of the urethane resin layer can be improved in the component (D). However, since the component (D) specifically improves the water resistance of the urethane resin layer when used in a specific amount relative to the epoxy group of the epoxy compound, in view of this point, the component (D) is a catalyst. It is presumed that actions other than the action can be exhibited.

  The component (D) is preferably soluble in water or can be emulsified by dispersing in water. As a result, when an uncured urethane resin is prepared as a water-based resin, it becomes possible to improve the applicability of the water-based resin and easily manufacture the urethane resin layer.

  Of the components (D), the tertiary amine is a compound having a tertiary amino group. In the tertiary amine, it is considered that reaction or catalysis with the epoxy group of the epoxy compound occurs at the nitrogen atom of the tertiary amino group of the tertiary amine. For this reason, in the relationship between the tertiary amine and the epoxy group of the epoxy compound, the valence of the tertiary amine is usually the same as the number of tertiary amino groups of the tertiary amine.

  Examples of tertiary amines include triethanolamine, triisopropanolamine, tri [(2-hydroxy) -1-propyl] amine, N, N-diethylmethanolamine, N, N-dimethylethanolamine, N, N, N ′, N′-tetramethylethylenediamine, N, N-dimethylbenzylamine, diethylaminopropylamine, N- (2-aminoethyl) piperazine, 2,4,6-tris (dimethylaminomethyl) phenol, N, N— And bis (trimethylsilyl) urea. In addition, a tertiary amine may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  By the way, in the amine, there may be an amine containing a primary amino group or a combination of a secondary amino group and a tertiary amino group. In this regard, in the present invention, an amine containing a primary amino group or a combination of a secondary amino group and a tertiary amino group is handled as a tertiary amino group.

  Among the components (D), the imidazole compound is imidazole and its derivatives. In the imidazole compound, it is considered that reaction or catalysis with the epoxy group of the epoxy compound occurs at two nitrogen atoms contained in the imidazole ring. For this reason, in the relationship between the imidazole compound and the epoxy group of the epoxy compound, the valence of the imidazole compound is usually divalent.

  Examples of the imidazole compound include imidazole; alkyl imidazole such as 2-methylimidazole; 1- (2-aminoethyl) -2-methylimidazole, 1- (2-aminoethyl) -2-ethylimidazole, 2-aminoimidazole. Examples thereof include imidazole having an amino group such as sulfate and 2- (2-aminoethyl) -benzimidazole. In addition, an imidazole compound may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Among the components (D), the imidazoline compound is imidazoline and its derivatives. In the imidazoline compound, it is considered that reaction or catalysis or the like occurs with the epoxy group of the epoxy compound at two nitrogen atoms contained in the imidazoline ring. For this reason, in the relationship between the imidazoline compound and the epoxy group of the epoxy compound, the valence of the imidazoline compound is usually divalent.

  Examples of the imidazoline compound include imidazoline; alkyl imidazolines such as 2-methyl-2-imidazoline. In addition, an imidazoline compound may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  (D) It is preferable that the boiling point of a component is higher than the glass transition temperature of resin which comprises a base film. When the base film contains a plurality of types of resins, it is preferable that the boiling point of the component (D) is higher than the lowest glass transition temperature among the glass transition temperatures of those resins. When the multilayer film of the present invention is stretched or dried, if the boiling point of the component (D) is high as described above, it is stable that the component (D) is vaporized and bubbles are generated in the urethane resin layer. Can be prevented.

  The amount of the component (D) is usually 1.4 equivalents or more, preferably 1.6 equivalents or more, usually 2.7 equivalents or less, preferably 2.5 equivalents or less with respect to 1 equivalent of the epoxy group of the epoxy compound. It is. In the uncured urethane resin in which (A) polyurethane, (B) epoxy compound, (C) component, and (D) component are combined, the amount of (D) component is within such a range, and the resin is Since the water resistance of the cured urethane resin layer can be improved, the adhesive force can be hardly lowered even in a high humidity environment.

  When combining the epoxy compound and the component (D) in the conventional easy-adhesion layer, since the component (D) has been recognized to function as a catalyst, the amount of the component (D) has a great influence on the performance of the easy-adhesion layer. It was thought not to give. However, the present inventor has found that the water resistance can be remarkably improved by making the amount of the component (D) within a specific range equivalent to the epoxy group of the epoxy compound as described above. This improvement in water resistance is a remarkable effect that cannot be predicted from the prior art, and has excellent practical significance.

[3-5. solvent〕
The uncured urethane resin is usually a fluid resin containing a solvent. Specifically, it becomes a liquid composition in which (A) polyurethane, (B) epoxy compound, (C) component and (D) component, and other components used as necessary are dissolved or dispersed in a solvent. ing. At this time, water or a water-soluble solvent is used as the 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. Among these, water is preferably used 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 is preferably set so that the viscosity of the uncured urethane resin is in a range suitable for coating.

[3-6. Other ingredients
The uncured urethane resin may contain components other than those described above as long as the effects of the present invention are not significantly impaired.

  For example, the uncured urethane resin preferably further contains fine particles. Thereby, a urethane resin layer will also contain microparticles | fine-particles and an unevenness | corrugation can be formed in the surface of a urethane resin layer. As a result, the area where the urethane resin layer comes into contact with other layers during winding is reduced, and the sliding property of the surface of the urethane resin layer is improved by that much, and when the multilayer film of the present invention is wound. The generation of wrinkles 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 equal to or greater than the lower limit value of the range, the slipperiness of the urethane resin layer can be effectively increased, and by making the average particle diameter equal to or less than the upper limit value of the range, 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.
In addition, fine particle may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The amount of fine particles contained in the urethane resin 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, the uncured urethane resin may contain a crosslinking agent. In particular, when the thickness of the urethane resin layer is 1 μm or less, it is preferable to include a crosslinking agent from the viewpoint of improving the mechanical strength of the urethane resin layer. As the crosslinking agent, any compound having a functional group that reacts with a reactive group of a polymer present in the resin can be used without particular limitation. Among these, those that are soluble in water or that can be emulsified by dispersing in water are preferred. Examples of the crosslinking agent include water-based isocyanate compounds, water-based carbodiimide compounds, water-based oxazoline compounds, and the like.

As the aqueous isocyanate compound, a compound having two or more non-blocked isocyanate groups or blocked isocyanate groups is usually used.
Examples of the non-blocking isocyanate compound include compounds obtained by reacting a polyfunctional isocyanate compound with a monovalent or polyvalent nonionic polyalkylene ether alcohol.
Examples of the block type isocyanate compound include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4′-diphenylmethane diisocyanate (MDI), Xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), methylcyclohexyl diisocyanate (H6TDI), 4,4′-dicyclohexylmethane diisocyanate (H12MDI), 1,3-bis (isocyanatomethyl) cyclohexane (H6XDI), tetramethylxylylene Range isocyanate (TMXDI), 2,2,4-trimethylhexamethylene diisocyanate (TMHDI), hexamethylene diisocyanate (HDI), norbornene diisocyanate (NBDI) 2,4,6-triisopropylphenyl diisocyanate (TIDI), 1,12-diisocyanatododecane (DDI), 2,4, -bis- (8-isocyanatooctyl) -1,3-dioctylcyclobutane (OCDI), n -Pentane-1,4-diisocyanate and their isocyanurate-modified products, adduct-modified products, burette-modified products, allophanate-modified products, and those polymers having one or more isocyanate groups in the polyoxyalkylene group , A compound obtained by modifying with a carboxyl group, making it water-soluble and / or water-dispersible, and masking an isocyanate group with a blocking agent (phenol, ε-caprolactam, etc.).

  As the aqueous carbodiimide compound, a compound having two or more carbodiimide bonds (—N═C═N—) is usually used. A compound having two or more carbodiimide bonds can be obtained, for example, by a method of forming a carbodiimide bond by decarboxylation of two isocyanate groups using two or more molecules of polyisocyanate and a carbodiimidization catalyst. . The polyisocyanate and the carbodiimidization catalyst used when producing a compound having two or more carbodiimide bonds are not particularly limited, and conventionally known ones can be used.

  A crosslinking agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The amount of the crosslinking agent is usually 1 part by weight or more, preferably 5 parts by weight or more, and usually 70 parts by weight or less, preferably 65 parts by weight or less in terms of solid content with respect to 100 parts by weight of polyurethane. By blending in this way, it is possible to achieve both the mechanical strength of the urethane resin layer and the stability of the uncured urethane resin.

  Furthermore, in the uncured urethane resin, unless the effects of the present invention are significantly impaired, for example, heat resistance stabilizer, weather resistance stabilizer, leveling agent, antistatic agent, slip agent, antiblocking agent, antifogging agent, lubricant , Dyes, pigments, natural oils, synthetic oils, waxes, crosslinking agents and the like 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.

[3-7. Method for producing urethane resin layer]
The urethane resin layer usually forms an uncured urethane resin layer containing (A) polyurethane, (B) epoxy compound, (C) component and (D) component on the surface of the base film, and then It is manufactured by curing a urethane resin. The uncured urethane resin is usually a composition in which (A) polyurethane, (B) epoxy compound, (C) component and (D) component, etc. are dissolved or dispersed in a solvent. Further, it may be in the form of an aqueous solution.

  In an uncured urethane resin, components such as polyurethane are 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 uncured urethane resin is preferably 15 mPa · s or less, and particularly preferably 10 mPa · s or less. When the viscosity of the uncured urethane resin is within the above range, the uncured urethane resin 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 uncured urethane resin can be adjusted by, for example, the ratio of the solvent contained in the uncured urethane resin and the particle size of the particles contained in the resin.

  Usually, when a layer of an uncured urethane resin is formed on the surface of a base film, the resin is applied by a coating method to form a coating film. 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 uncured urethane resin layer is formed on the base film, the resin forming the layer is cured to obtain the urethane resin layer according to the present invention.
Usually, since the uncured urethane resin contains a solvent, the solvent is removed by drying when it is cured. 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 making reaction, such as a crosslinking reaction, advance rapidly in resin.

  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 uncured urethane resin. 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, after an uncured urethane resin layer is formed on the surface of the substrate film, a stretching treatment may be performed. The stretching treatment may be performed after the uncured urethane resin is cured, but from the viewpoint of preventing the removal of fine particles from the urethane resin layer, or before curing the uncured urethane resin. It is preferable to perform a stretching process at the same time. Furthermore, from the viewpoint of forming a uniform urethane resin layer, it is more preferable to perform a stretching process simultaneously with curing the uncured urethane resin.

  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 substrate film is stretched, the urethane resin layer formed on the substrate surface is also stretched. However, since the thickness of the urethane resin layer is usually sufficiently smaller than the thickness of the base film, a large retardation is not exhibited in the stretched urethane resin layer.

  Moreover, before providing a urethane resin layer, the modification | reformation process may be given to the surface of a base film, and the adhesiveness of a base film and a urethane resin 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.

  Further, the surface of the urethane resin layer is preferably subjected to a hydrophilic surface treatment. Since the surface of the urethane resin layer is usually 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 urethane resin 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 atmospheric pressure plasma treatment are preferable, and corona discharge treatment is particularly preferable. As the plasma treatment, atmospheric pressure plasma treatment is preferable.

  In the hydrophilization surface treatment, the average water contact angle of the surface of the urethane resin 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 urethane resin 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 the range of 100 cm ^{2 on} the surface of the urethane resin layer that has been subjected to a hydrophilic surface treatment, and calculating an 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, functional groups such as a hydroxy group, a carboxyl group, a carbonyl group, an amino group, and a sulfonic acid group can be introduced on the surface of the urethane resin 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).

[3-8. Urethane resin layer structure and properties, etc.)
The thickness of the urethane resin 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 urethane resin 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 urethane resin 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, the urethane resin layer thickness The thickness t ₂ next if multilayer film comprises only one layer of the urethane resin layer of the present invention, when the multilayer film of the present invention comprises a urethane resin layer two or more layers thereof the total thickness of the urethane resin layer a thickness t ₂ of the.

  The interface refractive index difference between the base film and the urethane resin 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.

[4. Other layers]
The multilayer film of the present invention may include other layers on the surface of the base film on the side where the urethane resin 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.

[5. 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, it is possible to improve the display quality when the multilayer film of the present invention is used as a retardation film for a liquid crystal display device. 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 this invention is good also considering the dimension of the TD direction (it is also called a horizontal direction. Usually, it corresponds to the width direction) as 1000 mm-2000 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.

[6. Polarizer]
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 urethane resin layer and polarizer of the multilayer film of this invention, for example. At the time of bonding, the polarizer may be directly bonded to the urethane resin 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 an ultraviolet curable 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.

  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 (I)]
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 (I) was produced. This base film (I) is a base film made of an alicyclic structure-containing polymer resin.

[Production Example 2: Production of base film (II)]
Layer b made of methacrylic resin (glass transition temperature 105 ° C., Vicat softening temperature 103 ° C.) containing rubber particles, styrene-maleic anhydride copolymer (Dylark D332, manufactured by Nova Chemical Japan, glass transition temperature 130 ° C., Vicat softening An unstretched three-layer film comprising a layer consisting of a temperature of 130 ° C. and an oligomer component content of 3% by weight in the order of b layer (thickness 70 μm) −a layer (thickness 40 μm) −b layer (thickness 70 μm) Obtained by coextrusion molding. The obtained film was simultaneously biaxially stretched at a stretching temperature of 134 ° C., a stretching speed of 107% / min, a stretching ratio of 1.6 times in the MD direction, and a stretching ratio of 1.2 times in the TD direction, and the width was 1200 mm and the thickness (total Thickness) A stretched film of 94 μm was obtained as the base film (II). This base film (II) is a base film having a layer made of an acrylic resin on the surface.

[Production Example 3: 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 4: 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]
[(A) Preparation of polyurethane]
In a four-necked flask equipped with a thermometer, a stirrer, a nitrogen introducing tube and a cooling tube, 840 parts of a polyester polyol, Maximol FSK-2000 (manufactured by Kawasaki Chemical Industry Co., Ltd., hydroxyl value 56 mgKOH / g), 119 parts of tolylene diisocyanate And 200 parts of methyl ethyl ketone were allowed to react at 75 ° C. for 1 hour while introducing nitrogen. After completion of the reaction, the mixture was cooled to 60 ° C., 35.6 parts of dimethylolpropionic acid was added, and reacted at 75 ° C. to obtain a polyurethane solution containing an acid structure. The content of isocyanate groups (—NCO groups) in the polyurethane was 0.5%.

  Next, the polyurethane solution is cooled to 40 ° C., and 1500 parts of water and 51.4 parts of isophthalic acid dihydrazide (boiling point 224 ° C. or higher) (3 parts with respect to 100 parts of polyurethane) are added and stirred at high speed with a homomixer. Was emulsified. Methyl ethyl ketone was distilled off from the emulsion under heating and reduced pressure to obtain an aqueous dispersion of neutralized polyurethane. The solid content concentration of this aqueous dispersion was 40%.

[Preparation of liquid resin]
Furthermore, this aqueous dispersion was taken in an amount such that 100 parts of polyurethane was contained, and 10 parts of Denacol EX-313 (manufactured by Nagase ChemteX Corporation, glycerol polyglycidyl ether, epoxy equivalent 141 g / eq) as an epoxy compound and , 8 parts of silica fine particles (average particle size 100 nm), 4.3 parts of imidazole (boiling point 257 ° C.) and water are blended to obtain a liquid aqueous resin having a solid content of 5% as an uncured urethane resin. It was. This is calculated by adding 1.8 equivalents of imidazole to 1 equivalent of epoxy group of Denacol EX-313.

[Manufacture of multilayer films]
Using a corona treatment device (Kasuga Denki Co., Ltd.), discharge was performed on the surface of the base film I obtained in Production Example 1 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. Treated.

  The liquid aqueous resin was applied to the surface of the base film I subjected to the discharge treatment using a roll coater so that the dry film thickness was 0.5 μm. Thereafter, using a tenter-type transverse stretching machine, both ends of the base film I are held with clips and stretched at a stretching temperature of 140 ° C. for 40 seconds, and continuously stretched laterally and uniaxially at a stretching ratio of 2.0 times. The left and right ends were cut and removed. As a result, the step of drying the applied aqueous resin and the step of stretching the film are performed simultaneously, a urethane resin layer is formed on the surface of the base film I, and the orientation compound is aligned in the width direction. A layer film 1 was obtained.

[Example 2]
A stretched multilayer film 2 was produced in the same manner as in Example 1 except that the amount of imidazole was 3.8 parts. Under the present circumstances, the equivalent of the imidazole with respect to 1 equivalent of epoxy groups of Denacol EX-313 was 1.6 equivalent.

[Example 3]
A stretched multilayer film 3 was produced in the same manner as in Example 1 except that the amount of imidazole was 6.1 parts. Under the present circumstances, the equivalent of the imidazole with respect to 1 equivalent of epoxy groups of Denacol EX-313 was 2.5 equivalent.

[Example 4]
The type of epoxy compound was changed to Denacol EX-521 (manufactured by Nagase ChemteX Corp., polyglycerol polyglycidyl ether, epoxy equivalent 183 g / eq), adipic acid dihydrazide (boiling point 270 ° C.) instead of isophthalic acid dihydrazide, polyurethane 100 A stretched multilayer film 4 was produced in the same manner as in Example 1 except that 3 parts per part was used and that 2-methylimidazole (boiling point 270 ° C.) was used instead of imidazole. Under the present circumstances, 2-methylimidazole was 1.9 equivalent with respect to 1 equivalent of epoxy groups of Denacol EX-521.

[Example 5]
Instead of isophthalic acid dihydrazide, 3-aminopropyltriethoxysilane (boiling point 217 ° C.) was used in an amount of 3 parts per 100 parts of polyurethane, and N, N-dimethylbenzylamine (boiling point 183 ° C.) was used instead of imidazole. 15.0 parts were used, silica fine particles were not blended, and the film was not stretched by a tenter-type lateral stretching machine, and after application of an aqueous resin, the film was dried at 100 ° C. for 50 seconds, and then the left and right ends of the film. A multilayer film 5 was produced in the same manner as in Example 1 except that this part was cut. At this time, N, N-dimethylbenzylamine was 1.6 equivalents relative to 1 equivalent of the epoxy group of Denacol EX-313.

[Example 6]
The type of epoxy compound was changed to Denacol EX-612 (manufactured by Nagase ChemteX Corporation, sorbitol polyglycidyl ether, epoxy equivalent 166 g / eq), ethylenediamine (boiling point 117 ° C.) was used instead of isophthalic acid dihydrazide for 100 parts of polyurethane. 3 parts were used, 5.8 parts of N, N, N ′, N′-tetramethylethylenediamine (TMEDA, boiling point 120 ° C.) was used instead of imidazole, and by a tenter type transverse stretcher. A multi-layer film 6 was produced in the same manner as in Example 1 except that the film was not stretched and dried at 100 ° C. for 50 seconds after application of the aqueous resin and then the left and right ends of the film were cut. did. At this time, the equivalent of N, N, N ′, N′-tetramethylethylenediamine to 1.7 equivalents of epoxy group of Denacol EX-612 was 1.7 equivalents.

[Example 7]
The base film II obtained in Production Example 2 was used in place of the base film I, and adipic acid dihydrazide (boiling point 270 ° C.) was used in an amount of 3 parts per 100 parts of polyurethane instead of isophthalic acid dihydrazide. The use of 5.5 parts of 2-methyl-2-imidazoline (boiling point 144 ° C.) instead of imidazole, the use of acrylic resin fine particles (average particle diameter of 100 nm) instead of silica fine particles, and the stretching temperature A stretched multilayer film 7 was produced in the same manner as in Example 1 except that the temperature was changed to 100 ° C. At this time, the equivalent of 2-methyl-2-imidazoline to 1 equivalent of epoxy group of Denacol EX-313 was 1.8 equivalent.

[Example 8]
The base film II obtained in Production Example 2 was used in place of the base film I, and the type of epoxy compound was PG-207GS (manufactured by Nippon Steel Chemical Co., Ltd., polypropylene glycol diglycidyl ether, epoxy equivalent 320 g / eq). In place of isophthalic acid dihydrazide, using monoethanolamine (boiling point 171 ° C.) in an amount of 3 parts with respect to 100 parts of polyurethane, making the amount of imidazole 2.0 parts, and stretching temperature A stretched multilayer film 8 was produced in the same manner as in Example 1 except that was changed to 134 ° C. At this time, imidazole was 1.9 equivalents with respect to 1 equivalent of epoxy group of PG-207GS.

[Example 9]
A stretched multilayer film 3 was produced in the same manner as in Example 1 except that the amount of imidazole was 3.3 parts. Under the present circumstances, the equivalent of the imidazole with respect to 1 equivalent of epoxy groups of Denacol EX-313 was 1.4 equivalent.

[Example 10]
A stretched multilayer film 3 was produced in the same manner as in Example 1 except that the amount of imidazole was 6.5 parts. Under the present circumstances, the equivalent of the imidazole with respect to 1 equivalent of epoxy groups of Denacol EX-313 was 2.7 equivalent.

[Comparative Example 1]
A stretched multilayer film 9 was produced in the same manner as in Example 1 except that imidazole was not used.

[Comparative Example 2]
A stretched multilayer film 10 was produced in the same manner as in Example 1 except that the amount of imidazole was 3.0 parts. Under the present circumstances, the equivalent of the imidazole with respect to 1 equivalent of epoxy groups of Denacol EX-313 was 1.2 equivalent.

[Comparative Example 3]
A stretched multilayer film 11 was produced in the same manner as in Example 1 except that the amount of imidazole was 7.5 parts. At this time, the equivalent of imidazole to 3.1 equivalent of epoxy group of Denacol EX-313 was 3.1 equivalent.

[Comparative Example 4]
A stretched multilayer film 12 was produced in the same manner as in Example 1 except that isophthalic acid dihydrazide was not used. Under the present circumstances, the equivalent of the imidazole with respect to 1 equivalent of epoxy groups of Denacol EX-313 was 1.8 equivalent.

[Comparative Example 5]
A stretched multilayer film 13 was produced in the same manner as in Example 1 except that the epoxy compound Denacol EX-313 was not used and the stretching temperature was changed to 140 ° C.

[Evaluation of adhesive strength]
[Measurement of peel strength of initial polarizing plate]
A roll laminator using the adhesive produced in Production Example 4 and the surface of the stretched multilayer film produced in Examples or Comparative Examples or the urethane resin layer of the multilayer film and one side of the polarizer produced in Production Example 3 The polarizing plate was manufactured by bonding together. The obtained polarizing plate was cut into a width of 10 mm, the polarizer and the film were pulled in the 90 ° direction, and the tensile force (90 ° peel strength) when peeling off was measured. The measurement was performed with a length of 20 mm, and the average value (average peel strength) at that time was determined. In addition, as a measuring machine, a universal tensile compression testing machine (TCM-500CR: manufactured by Shinsei Tsushin Kogyo Co., Ltd.) was used, and the test was carried out at a tensile speed of 20 mm / min. The results are shown in Tables 1-3.

[Measurement of peel strength of polarizing plate after moisture resistance test]
The polarizing plate produced as described above was left in a constant temperature and high humidity bath at 60 ° C. and 90% RH for 200 hours. Thereafter, the obtained polarizing plate was cut into a width of 10 mm, and the average peel strength was determined in the same manner as in [Measurement of peel strength of initial polarizing plate]. The results are shown in Tables 1-3.

[Consideration]
By comparing the average peel strength of the initial polarizing plates of the examples and comparative examples described above, according to the present invention, by combining (A) polyurethane, (B) epoxy compound and (C) component according to the present invention. It can be seen that high adhesive strength can be realized in a multilayer film including a base film made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer.

  Here, the results of Examples 1 to 3, 9, 10 and Comparative Examples 1 to 3 in which conditions other than the number of equivalents of the component (D) with respect to 1 equivalent of the epoxy group of the (B) epoxy compound are shown in FIG. . In FIG. 1, the horizontal axis indicates the number of equivalents of the component (D) relative to 1 equivalent of the epoxy group of the epoxy compound (B), and the vertical axis indicates the average peel strength of the polarizing plate after the moisture resistance test with respect to the average peel strength of the initial polarizing plate. The ratio of As can be seen from FIG. 1, in the range where the number of equivalents of the component (D) with respect to 1 equivalent of the epoxy group of the (B) epoxy compound is in the range of 1.4 equivalents to 2.7 equivalents, the moisture resistance test with respect to the average peel strength of the initial polarizing plate The ratio of the average peel strength of the subsequent polarizing plate is specifically increased. From this, when the number of equivalents of the component (D) relative to 1 equivalent of the epoxy group of the (B) epoxy compound is in the range of 1.4 equivalents to 2.7 equivalents, the decrease in the adhesiveness of the urethane resin layer due to the moisture resistance test can be reduced. I understand. Therefore, in the urethane resin layer combining (A) polyurethane, (B) epoxy compound, (C) component and (D) component according to the present invention, (D) component (D) relative to 1 equivalent of epoxy group of (B) epoxy compound It can be understood that by keeping the number of equivalents in the range of 1.4 equivalents to 2.7 equivalents, it is difficult to lower the adhesive force even in a high humidity environment.

Claims (14)

A base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer on the surface, and a urethane resin layer,
The urethane resin layer is
(A) polyurethane,
(B) an epoxy compound,
(C) one or both of a primary amine and a secondary amine, and
(D) It includes at least one compound selected from the group consisting of a tertiary amine, an imidazole compound, and an imidazoline compound, in an amount of 1.4 to 2.7 equivalents relative to 1 equivalent of the epoxy group of the (B) epoxy compound. A multilayer film, which is a cured layer of resin. The (A) polyurethane contains an acid structure,
The amount of the (B) epoxy compound is 0.2 to 1.4 times the amount of the (B) epoxy compound equivalent to the acid structure of the (A) polyurethane. Multi-layer film.   The multilayer film according to claim 1 or 2, wherein one or both of the (C) primary amine and secondary amine is a compound having a hydrazino group.   One or both of the (C) primary amine and secondary amine, and the boiling point of at least one compound selected from the group consisting of the (D) tertiary amine, imidazole compound and imidazoline compound, The multilayer film as described in any one of Claims 1-3 higher than the glass transition temperature of resin to comprise.   At least selected from the group consisting of (A) polyurethane, (B) epoxy compound, (C) one or both of primary amine and secondary amine, and (D) tertiary amine, imidazole compound and imidazoline compound. The multilayer film as described in any one of Claims 1-4 in which resin containing one type of compound further contains microparticles | fine-particles.   The multilayer film according to any one of claims 1 to 5, which is a retardation film. On the surface of the base film having a layer made of a resin containing an alicyclic structure-containing polymer or an acrylic polymer on the surface,
(A) polyurethane,
(B) an epoxy compound,
(C) one or both of a primary amine and a secondary amine, and
(D) It includes at least one compound selected from the group consisting of a tertiary amine, an imidazole compound, and an imidazoline compound, in an amount of 1.4 to 2.7 equivalents relative to 1 equivalent of the epoxy group of the (B) epoxy compound. The manufacturing method of a multilayer film including apply | coating resin and making it harden | cure. The (A) polyurethane contains an acid structure,
The amount of the (B) epoxy compound is 0.2 to 1.4 times the amount of the (B) epoxy compound equivalent to the acid structure of the (A) polyurethane. Production method.   The production method according to claim 7 or 8, wherein one or both of the (C) primary amine and secondary amine is a compound having a hydrazino group.   One or both of the (C) primary amine and secondary amine, and the boiling point of at least one compound selected from the group consisting of the (D) tertiary amine, imidazole compound and imidazoline compound, The manufacturing method as described in any one of Claims 7-9 higher than the glass transition temperature of resin to comprise.   At least selected from the group consisting of (A) polyurethane, (B) epoxy compound, (C) one or both of primary amine and secondary amine, and (D) tertiary amine, imidazole compound and imidazoline compound. The manufacturing method as described in any one of Claims 7-10 in which resin containing one type of compound further contains microparticles | fine-particles.   The manufacturing method according to any one of claims 7 to 11, wherein the base film is stretched simultaneously with curing the applied resin.   A polarizing plate protective film provided with the multilayer film as described in any one of Claims 1-6.   A polarizing plate comprising a polarizer and the polarizing plate protective film according to claim 13.

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