JP4571417B2 - Laminated film with an easy adhesion layer - Google Patents

Description

  The present invention relates to an easily-adhesive polyester film excellent in transparency such as adhesion of inks, adhesives and the like, in particular, adhesion to a UV curable resin not only after UV irradiation but also before UV irradiation.

  Polyester films, especially biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, heat resistance, chemical resistance, and transparency. For magnetic tapes, photographic films, packaging films, and electronic parts. It is widely used as a material for films, optical films, surface protective films and the like. These films are often used by laminating a magnetic layer, a photosensitive layer, a protective layer, an intermediate layer, a colored layer, and the like, and affixing or sticking to another adherend. Recently, a polyester film with a hard coat layer laminated and an antireflection layer and antifouling layer laminated on the display surface has been used for the purpose of protecting the screen of displays (LCD and CRT), especially for optical applications. Yes. In general, the components constituting the hard coat layer have low adhesion to the polyester film, and therefore, when the hard coat layer is laminated, surface treatment has been performed on the polyester film surface. As this surface treatment, physical treatment such as corona treatment is known, but even when these treatments are performed, the adhesion of a hard coat agent or the like is insufficient. Further, when a polyester film having a hard coat layer laminated thereon is used under severe environmental conditions, for example, in an environment of rapid temperature change (thermal shock), the adhesion between the hard coat layer and the film layer may be reduced and peeled off. In addition, the adhesiveness was lowered by the resin component of the hard coat layer to be laminated, and it was not fully satisfactory.

As a method for improving the adhesion between layers, a block film comprising a polymer block (A) mainly composed of a vinyl aromatic compound and a polymer block (B) mainly composed of a conjugated diene compound is formed on a base film. An epoxy-modified block polymer, which is a polymer or a partially hydrogenated product thereof and in which a carbon-carbon double bond of a conjugated diene is epoxidized, is formed as an easy-adhesion layer. There is a method of laminating layers to perform (see, for example, Patent Document 1). However, for example, when a UV curable resin layer constituting a hard coat layer or a UV curable pressure-sensitive adhesive layer used for a dicing tape or the like is formed on this easy-adhesion layer, before UV irradiation, The adhesiveness with a base film may not be favorable, and the improvement was calculated | required.
JP 2000-191989

The object of the present invention is to solve such problems of the prior art, and is excellent in adhesion before curing and also after curing to inks and adhesives, particularly UV curable resins represented by hard coating agents. It is providing the polyester film which has an easily bonding layer which does not fall.

  As a result of intensive studies to solve these problems, the present inventor has found that the problem can be solved by providing an easy-adhesion layer comprising a specific component on a polyester film as a substrate, and has completed the present invention.

That is, the gist of the present invention is a laminated film in which a UV curable resin layer is provided on a polyester film via at least one easy-adhesion layer, and the easy-adhesion layer is mainly composed of a vinyl aromatic compound. a polymer block (a), a block copolymer or partially hydrogenated product thereof consisting of a polymer block composed mainly of a conjugated diene compound (B), carbon of the conjugated diene - carbon double bond is epoxidized A laminated film characterized in that it is composed of an epoxy-modified block polymer, and the easy-adhesion layer contains 10 to 70% by mass of at least one binder selected from an acrylic resin, a polyester resin, and a urethane resin. .

In the laminated film of the present invention, since a specific binder is added to the easy-adhesion layer, it has excellent adhesion to the UV curable resin layer, and without damaging the adhesion after UV irradiation, the UV curable resin layer can be formed. The initial adhesiveness before the subsequent UV irradiation can be improved.

  Hereinafter, the present invention will be described in more detail.

  The polyester constituting the polyester film in the present invention is a linear saturated polyester obtained by polycondensation from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polyethylene-2,6 naphthalene dicarboxylate, and the like. These copolymers or blends thereof with a small proportion of other resins. Things are also included.

  The polyester film can be produced by a conventionally known method. For example, the biaxially stretched polyester film is obtained by drying the polyester, melting it with an extruder at a temperature of Tm to (Tm + 70) ° C. (Tm: melting point of the polyester), and from a die (for example, T-die, I-die). Extruded onto a rotating cooling drum, rapidly cooled at 40 to 90 ° C. to produce an unstretched film, and then the unstretched film was heated at a temperature of (Tg-10) to (Tg + 70) ° C. (Tg: glass transition temperature of polyester). Stretch in the longitudinal direction at a magnification of 2.5 to 8.0 times, stretch in the transverse direction at a magnification of 2.5 to 8.0 times, and heat for 1 to 60 seconds at a temperature of 180 to 250 ° C. as necessary. It can be manufactured by fixing.

  The thickness of the film is preferably in the range of 5 to 250 μm. When the thickness of the film is less than 5 μm, there is a problem that the deformation resistance (dimensional stability) in a high temperature range is inferior, and when it exceeds 250 μm, the rigidity is too high.

  If necessary, an appropriate filler can be contained in the polyester film. Examples of the filler include those conventionally known as slipperiness imparting agents for polyester films, and specific examples thereof include calcium carbonate, calcium oxide, aluminum oxide, silica, kaolin, silicon oxide, zinc oxide, and carbon black. , Silicon carbide, tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, crosslinked silicone resin particles, and the like. Further, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, and the like can be appropriately added to the polyester.

The laminated film of the present invention has at least one easy-adhesion layer on the polyester film. This easy-adhesion layer is composed of an epoxy-modified block polymer, and the easy-adhesion layer contains at least one binder selected from acrylic resins, polyester resins, and urethane resins. The epoxy-modified block polymer is a block copolymer comprising a polymer block (A) mainly composed of a vinyl aromatic compound and a polymer block (B) mainly composed of a conjugated diene compound, or a partial hydrogenation thereof. And a polymer in which the carbon-carbon double bond of the conjugated diene is epoxidized.

  In the present invention, the block copolymer is a block copolymer comprising a polymer block (A) mainly composed of a vinyl aromatic compound and a polymer block (B) mainly composed of a conjugated diene compound. The copolymerization ratio of the group compound and the conjugated diene compound is preferably 5/95 to 70/30, particularly preferably 10/90 to 60/40. When the copolymerization ratio exceeds this range, the coating film becomes brittle and durability may be lowered.

  Examples of the vinyl aromatic compound constituting the polymer block (A) include styrene, α-methylstyrene, vinyltoluene, p-tertiary butylstyrene, divinylbenzene, p-methylstyrene, 1,1-diphenylstyrene, and the like. One or more can be selected from among them, and styrene is preferable among them.

  Examples of the conjugated diene compound constituting the polymer block (B) include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3. -One or more types are selected from octadiene, phenyl-1,3-butadiene, etc. Among them, butadiene, isoprene and combinations thereof are preferable.

  The number average molecular weight of the block copolymer is in the range of 5,000 to 600,000, preferably 10,000 to 500,000, and the molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)]. Is preferably 10 or less. When the number average molecular weight is less than 5,000, the coating film becomes brittle and tackiness may occur, and the viscosity of the coating agent exceeding 600,000 tends to be high and the leveling tends to deteriorate. On the other hand, if the molecular weight distribution exceeds 10, problems of tack and blocking occur.

The molecular structure of the block copolymer may be linear, branched, radial, or any combination thereof. For example, structures such as ABA, BABA, (AB) ₄ Si, ABBABA, and the like can be given.

  In the block copolymer, a carbon-carbon double bond of a conjugated diene may be partially hydrogenated. By adding hydrogen, the effect of improving light resistance can be obtained.

In the present invention, the epoxy-modified block polymer is obtained by epoxidizing a carbon-carbon double bond of a conjugated diene of a block copolymer or a partially hydrogenated product thereof. As for the degree of epoxidation, the epoxy equivalent (g / equiv) calculated by the following formula is preferably 140 to 2700, and more preferably 500 to 1500. When the epoxy equivalent is less than 140, blocking may occur and adhesion with the UV curable resin may be lowered. When the epoxy equivalent exceeds 2,700, adhesion with the substrate film may be insufficient.
Epoxy equivalent = (16000 × [epoxy-modified block polymer mass]) / ([titration amount of hydrobromic acid (ml)] × [factor of hydrobromic acid])

  As a method for producing the block copolymer, any production method can be used as long as a product having the structure described above can be produced. For example, JP-B-40-23798, JP-B-47-3252, JP-B-48-2423, JP-B-49-105970, JP-B-50-27094, JP-B-46-32415, JP-A-59 166518, JP-B-49-36957, JP-B-43-17979, JP-B-46-32415, JP-B-56-28925, in an inert solvent using a lithium catalyst or the like. A vinyl aromatic compound-conjugated diene compound block copolymer can be synthesized.

  Furthermore, as a method of partially hydrogenating the block copolymer, a method described in JP-B-42-8704, JP-B-43-6636, or JP-A-59-133203 can be used in an inert solvent. And hydrogenation in the presence of a hydrogenation catalyst.

  The epoxy-modified block copolymer in the present invention can be obtained by reacting the above-mentioned block copolymer or a partially hydrogenated product thereof with an epoxidizing agent such as peracids and hydroperoxides in an inert solvent. it can. Examples of peracids include performic acid, peracetic acid, perbenzoic acid, and trifluoroperacetic acid. Of these, peracetic acid is preferred because it is industrially produced in large quantities, is available at low cost, and has high stability. Examples of hydroperoxides include hydrogen peroxide, tertiary butyl hydroperoxide, cumene peroxide, and the like.

  In the epoxidation, a catalyst can be used as necessary. For example, in the case of a peracid, an alkali such as sodium carbonate or an acid such as sulfuric acid can be used as a catalyst. In the case of hydroperoxides, a catalytic effect can be obtained by using a mixture of tungstic acid and caustic soda with hydrogen peroxide, organic acid with hydrogen peroxide, or molybdenum hexacarbonyl with tertiary butyl hydroperoxide. Can do.

  There is no strict regulation of the amount of epoxidizing agent, and the optimum amount in each case depends on variable factors such as the particular epoxidizing agent used, the desired degree of epoxidation, the particular block copolymer used, etc. be able to.

  The inert solvent is used for the purpose of reducing the viscosity of the raw material or stabilizing by diluting the epoxidizing agent. In the case of peracetic acid, aromatic compounds, ethers, esters and the like are used. Particularly preferred solvents are hexane, cyclohexane, toluene, benzene, ethyl acetate, carbon tetrachloride, and chloroform.

  There are no strict regulations on the epoxidation reaction conditions. The reaction temperature range that can be used is determined by the reactivity of the epoxidizing agent used. For example, in the case of peracetic acid, 0 to 70 ° C. is preferable. If it is less than 0 ° C., the reaction is slow, and if it exceeds 70 ° C., decomposition of peracetic acid occurs. Moreover, in the tertiary butyl hydroperoxide / molybdenum dioxide diacetylacetonate system which is an example of hydroperoxide, 20-150 degreeC is preferable for the same reason. No special operation of the reaction mixture is necessary. For example, the mixture may be stirred for 2 to 10 hours. Isolation of the resulting epoxy-modified copolymer is carried out by an appropriate method, for example, a method of precipitating with a poor solvent, a method of adding the polymer to hot water under stirring and distilling off the solvent, or a direct desolvation method. It can be carried out.

In the present invention, the easy-adhesion layer needs to be composed of an epoxy-modified block polymer and a binder. As a binder, 10-70 mass% of 1 or more types chosen from an acrylic resin, a polyester resin, and a urethane resin needs to be contained. If the content of the binder in the easy-adhesion layer is less than 10%, the wettability is not good, coat streaks or initial adhesion cannot be obtained when forming a coating film such as an adhesive, after drying, If you rub with your finger or peel off the adhesive tape (registered trademark) on the coating film, the coating film provided on the easy-adhesion layer may be removed relatively easily. When the content of the binder exceeds 70% by mass, the adhesion after UV irradiation may decrease.

  The binder preferably has at least one functional group capable of reacting with an epoxy group such as an amino group, a hydroxyl group, and a carboxyl group (including a carboxylic acid anhydride). Since these functional groups react with the epoxy group, dispersibility and agglomeration are increased and transparency is not impaired, which is preferable.

  The acrylic resin used as the binder is obtained by polymerizing the following monomers / oligomers, for example. Monomers include alkyl acrylate, alkyl methacrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl. Group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, etc.). And in order to give the said functional group further using the said monomer as a basic skeleton, it is copolymerized with the monomer which has the following functional groups. That is, a carboxyl group, a methylol group, an acid anhydride group, a sulfonic acid group, an amide group, an alkylated amide group, an amino group (including a substituted amino group), an alkylated amino group, or a hydroxyl group And monomers having a functional group such as an epoxy group, and salts and esterified products thereof may be copolymerized. Specifically, examples of the compound having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, their alkali metal salts, ammonium salts, and anhydrides.

  The polyester resin used as the binder is a resin having a dicarboxylic acid component and a glycol component containing a branched glycol component as constituent components. The branched glycol component includes 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-methyl-2-butyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl 2-n-hexyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2,2-di-n-hexyl-1,3-propanediol, and the like Can be mentioned. The branched glycol component is preferably contained in the total glycol component in a proportion of 10 mol% or more, and more preferably in a proportion of 20 mol% or more. As the glycol component other than the branched glycol component, ethylene glycol is most preferable. Further, diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol, or the like may be used as long as the amount is small.

  As the dicarboxylic acid component, terephthalic acid and isophthalic acid are most preferable. Also, in small amounts, other dicarboxylic acid components, for example, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and azelaic acid, diphenyldicarboxylic acid, and aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid are used. In addition, it may be copolymerized.

  Examples of the urethane resin used as the binder include those obtained by a reaction between an isocyanate compound and a hydroxyl group-containing compound. Examples of the isocyanate compound include polyisocyanates having two or more isocyanates in the same molecule. Specific examples of the polyisocyanate include diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. These urethane-modified products, carbodiimide-modified products, and mixtures thereof are also included. Diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, modified polyisocyanates thereof, or mixtures thereof are preferred.

  The hydroxyl group-containing compound is not particularly limited, but a polyol compound having two or more hydroxyl groups in the same molecule is usually used. Specific examples of the polyol compound include propylene glycol, diethylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose and other hydroxyl group-containing compounds, triethanolamine, diethanolamine and other amino group- and hydroxyl group-containing compounds, or ethylenediamine. A polyether having 2 to 6 hydroxyl groups in the molecule obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to an amino group-containing compound such as diaminotoluene and having an average hydroxyl equivalent weight of 200 or more, for example, 500 to 3000 Examples thereof include polyols and polymer polyols obtained by addition polymerization of these polyether polyols with vinyl compounds. Polyester polyols obtained by reacting polycarboxylic acids with low molecular weight hydroxyl group-containing compounds, polycarbonate polyols obtained by ring-opening polymerization of caprolactone, amination of the hydroxyl groups of polyether polyols, or isocyanate prepolymers of polyether polyols The polyether polyamine obtained by hydrolyzing the water may have an average active hydrogen equivalent of 200 or more, for example, 500 to 3000. The molecular weight of the polyol is preferably 1000 or more, more preferably 1000 to 18000, and even more preferably 2000 to 8000. The amount of the polyol may be 5 to 80 parts by mass, for example 15 to 50 parts by mass, per 100 parts by mass of the polyol compound.

  Catalysts used in the production of urethane resins include triethylenediamine, pentamethyldiethylenetriamine, 1,8-diazabicyclo-5,4-undecene-7, dimethylaminoethanol, tetramethylethylenediamine, dimethylbenzylamine, tetramethylhexamethylenediamine, bis ( Tertiary amines such as 2-dimethylaminoethyl) ether and organometallic compounds such as dibutyltin dilaurate, tin octoate, and dibutyltin diacetate are used. The amount of the catalyst is preferably in the range of 0.1 to 5 parts by mass per 100 parts by mass of the polyol mixture.

  In the present invention, the easy adhesion layer preferably contains a curing agent that reacts with an epoxy group. Examples of such a curing agent include amino group, carboxyl group, carboxylic anhydride group, hydroxyl group,-(C = X) -NH- (C = Y) -unit (wherein X and Y are oxygen atoms). Or a compound containing two or more of the same or different functional groups selected from a sulfur atom, or one of which represents an oxygen atom and the other is a sulfur atom) in one molecule. Moreover, even if it is monofunctional at the time of addition like the coupling agent which has an amino group, the compound which compounded after mixing | blending and can function as a polyfunctional compound is also contained. The molecular weight of the curing agent is not particularly limited and may be a polymer compound. Specific examples of such curing agents include aliphatic amines, acid anhydrides, phenols, imidazoles, dicyandiamide, boron trifluoride amine complexes, and adipine dihydrazide compounds. You may use together. By containing the curing agent in the easy-adhesion layer, the solvent resistance is improved. It is preferable that content of a hardening | curing agent is 2-5 mass% with respect to an epoxy-modified block polymer.

  Furthermore, in order to accelerate the reaction between the curing agent and the epoxy-modified block copolymer, it may be preferable to use a reaction accelerator. Examples of the reaction accelerator include quaternary ammonium salts, quaternary phosphonium salts, and phosphine compounds. In particular, it is preferable to use a reaction accelerator when using a compound having a carboxyl group or a — (C═X) —NH— (C═Y) — unit as a curing agent. Examples of the quaternary ammonium salt include tetrabutylammonium bromide, n-dodecyltrimethylammonium bromide, and octadecyltrimethylammonium bromide. Examples of the quaternary phosphonium salt include triphenylbenzylphosphonium chloride, triphenylbenzylphosphonium iodide, tetrabutylphosphonium bromide and the like. Examples of phosphine include triphenylphosphine and tri-2,6-dimethoxyphenylphosphine. The content of the reaction accelerator is preferably 5% by mass or less with respect to the epoxy-modified block copolymer. Even if more than 5% by mass is used, the effect of increasing the amount cannot be expected.

  Hereinafter, the present invention will be further described by way of examples, but is not limited thereto. In forming the easy-adhesion layer, the following epoxy-modified block polymer and binder were used.

Epoxy-modified block polymer solution (A):
A solution obtained by dissolving an epoxy group-containing styrene-butadiene-styrene block copolymer (weight average molecular weight = 30000, epoxy equivalent (g / equiv) = 1900) in a toluene / MEK mixed solvent so as to have a solid content of 30% by mass.

Epoxy-modified block polymer solution (I):
A solution in which an epoxy group-containing styrene-butadiene-styrene block copolymer (weight average molecular weight = 30000, epoxy equivalent (g / equiv) = 1000) is dissolved in a toluene / MEK mixed solvent so as to have a solid content of 30% by mass.

Binder liquid (U):
Elitel UE3300 (Unitika Copolyester)

Binder liquid (D):
Poliment NK380 (Japan Catalyst Acrylic Resin 30% by mass solution)

Binder liquid (e):
Thermolac EF-42 (Acrylic resin 30% by mass solution from Soken Chemical)

  Further, as a UV curable resin formed on the easy-adhesion layer, a UV curable adhesive prepared by the following method was used.

UV curable adhesive:
79 parts by mass of butyl acrylate, 15 parts by mass of ethyl acrylate, 1 part by mass of acrylic acid, 5 parts by mass of 2-hydroxyethyl acrylate, 0.2 parts by mass of photopolymerization initiator (Irgacure 651, 50% ethyl acetate solution), lauryl mercaptan 0 A mixed solution composed of 0.02 parts by mass was irradiated with ultraviolet rays to obtain an acrylic copolymer having a weight average molecular weight of 70,000. With respect to 100 parts by mass of the resin solid content of the obtained acrylic copolymer ethyl acetate solution, 3.5 parts by mass of 2-isocyanatoethyl methacrylate is added and reacted, and further the resin solid of the ethyl acetate solution after the reaction UV curing by mixing 20 parts by mass of pentaerythritol triacrylate, 0.5 parts by mass of a photopolymerization initiator (Irgacure 651, 50% ethyl acetate solution) and 1.5 parts by mass of polyisocyanate with respect to 100 parts by mass. An ethyl acetate solution of a mold adhesive was prepared.

The measuring method of the physical property of the polyester film which provided the easily bonding layer is shown below. In addition, as long as the principle is the same, a machine, an apparatus, etc. may differ.

Adhesion with UV curable resin:
First, the UV curable pressure-sensitive adhesive was applied onto an easy-adhesive layer of a polyester film so as to have a dry thickness of 15 μm to form a pressure-sensitive adhesive layer, thereby preparing a pressure-sensitive adhesive tape. The pressure-sensitive adhesive surface of this pressure-sensitive adhesive tape was rubbed with the belly of the finger. Furthermore, after this film was attached to a glass plate, using an ultra-high pressure mercury lamp, irradiation with ultraviolet rays of 365 nm was performed for 2 minutes while adjusting the illuminance so that the irradiation intensity on the surface of the glass plate was 40 mW / cm ² . When the pressure-sensitive adhesive tape was peeled off from the glass plate after irradiation, the case where no pressure-sensitive adhesive remained on the glass plate surface was marked with ◯, and the case where the pressure-sensitive adhesive remained on the glass plate surface was marked with x.

Example 1
A coating formed by mixing 10 parts by mass of the epoxy-modified block copolymer solution (A) and 10 parts by mass of the binder liquid (U) is applied to the corona-treated surface of the polyester film (Embret SA-125 manufactured by Unitika). after coating, and dried at 130 ° C., to obtain a polyester film formed of the adhesive layer.

Examples 2-6, Comparative Examples 1-5
It was changed to a epoxy-modified block polymer and the binder shown in Table 1, in the same manner as in Example 1 to obtain a polyester film formed of the adhesive layer.

The easy adhesion layers of the polyester films obtained in Examples 1 to 6 had adhesion before and after UV irradiation, but the films obtained in Comparative Examples 1 to 5 had adhesion before irradiation and after irradiation. Could not be satisfied at the same time.

Claims (4)

A laminated film in which a UV curable resin layer is provided on at least one easy-adhesion layer on a polyester film, the easy-adhesion layer being a polymer block (A) mainly composed of a vinyl aromatic compound, A block copolymer comprising a polymer block (B) mainly composed of a conjugated diene compound or a partially hydrogenated product thereof , and an epoxy-modified block polymer in which the carbon-carbon double bond of the conjugated diene is epoxidized. A laminated film characterized in that the easy-adhesion layer contains 10 to 70% by mass of at least one binder selected from acrylic resin, polyester resin, and urethane resin. The laminated film according to claim 1, wherein an epoxy equivalent of the epoxy-modified block polymer in the easy-adhesion layer is 140 to 2700. The laminated film according to claim 1 or 2, wherein the binder in the easy adhesion layer has an amino group, a hydroxyl group or a carboxyl group. The laminated film according to any one of claims 1 to 3, wherein the easy adhesion layer contains a curing agent that reacts with an epoxy group.