JP4448006B2 - Easy adhesion polyester film - Google Patents

Description

  The present invention relates to an easily-adhesive polyester film excellent in adhesion to a photocurable resin layer and excellent in antistatic properties, slipperiness and transparency.

  Polyester films, especially biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, heat resistance, chemical resistance, and transparency, so magnetic tape, photographic film, packaging film, film for electronic parts It is widely used as a material for 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, especially in the semiconductor manufacturing process, in order to support and protect semiconductor wafers and to improve releasability when not required, a laminated film in which a polyester film is used as a base layer and an ultraviolet curable adhesive layer is laminated thereon has been used. ing.

  In general, since the component constituting the pressure-sensitive adhesive layer has low adhesion to the polyester film, surface treatment has been performed on the polyester film surface when the pressure-sensitive adhesive is laminated on the polyester film. As this surface treatment, physical treatment such as corona treatment is known, but the adhesion of the ultraviolet curable adhesive is insufficient in these treatments. In addition, there is a method of providing a pressure-sensitive adhesive made of a polyester film, but when used in harsh environmental conditions, for example, in an environment of rapid temperature change (thermal shock), the adhesive force between the pressure-sensitive adhesive layer and the film layer may decrease and peel off. is there. Furthermore, the adhesiveness is lowered by the resin component of the pressure-sensitive adhesive layer to be laminated, which is not satisfactory.

Furthermore, as a method for improving the adhesion between the layers, a polymer block (A) mainly composed of a vinyl aromatic compound and a polymer block (B) mainly composed of a conjugated diene compound are formed on a base film. An epoxy-modified block polymer, which is a block copolymer 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 stacking a target layer (see, for example, Patent Document 1). However, when an ultraviolet curable pressure-sensitive adhesive layer is laminated on the easy-adhesion layer, the compatibility between the pressure-sensitive adhesive layer and the easy-adhesion layer is not good, and a sufficient easy-adhesion effect may not be obtained. . Further, the generation of static electricity may make it difficult to process the pressure-sensitive adhesive, and may cause defects in the semiconductor.
JP 2000-191989

  An object of the present invention is to provide a polyester film that solves the problems of the prior art and has excellent adhesion to a photocurable resin typified by ink, adhesive, and pressure-sensitive adhesive.

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

That is, the gist of the present invention is as follows.
A polyester film having at least one easy-adhesion layer, wherein the easy-adhesion layer comprises a polymer block (A) mainly composed of a vinyl aromatic compound and a polymer block (B) mainly composed of a conjugated diene compound. A block copolymer or a partially hydrogenated product thereof, which is composed of an epoxy-modified block polymer in which a carbon-carbon double bond of the conjugated diene is epoxidized, and the easy-adhesion layer includes conductive metal oxide fine particles and And an easily adhesive polyester film characterized by containing an acrylic / styrene copolymer.

  In the easy-adhesive polyester film of the present invention, the easy-adhesive layer suppresses the decrease in adhesion due to curing shrinkage and heat treatment, and also keeps the dispersed state of conductive metal oxide fine particles used as an easy-lubricant, anti-blocking agent, and antistatic agent in good condition. Therefore, it is possible to remarkably improve the adhesion to the photocurable resin layer such as the ultraviolet curable adhesive and the antistatic property while ensuring transparency.

Hereinafter, the present invention will be described in more detail.
In the easily adhesive polyester film of the present invention, the polyester constituting the base film is a linear saturation obtained by polycondensation from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Polyester. 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, etc. Is 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 easy-adhesion polyester film of the present invention has at least one easy-adhesion layer on the substrate polyester film. This easy-adhesion layer is composed of an epoxy-modified block polymer, and the easy-adhesion layer further contains conductive metal oxide fine particles and an acrylic / styrene copolymer. 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 aromatic 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. -1 type or 2 types or more are chosen from octadiene, a phenyl- 1, 3- butadiene, etc., A butadiene, isoprene, and these combination are especially 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, and ABBABA are 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.

  As a method for producing the block polymer, any production method can be used as long as it has a structure as described above. 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 for 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. The method of hydrogenating in presence of a hydrogenation catalyst is mentioned.

  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, trifluoroperacetic acid and the like. 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 and 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 this invention, an easily bonding layer is comprised with an epoxy-modified block polymer, and needs to contain electroconductive metal oxide fine particles in this. When an epoxy-modified block polymer is used alone for the easy-adhesion layer, the coating film has tackiness, and is difficult to use because it causes blocking during winding, slippage failure during post-processing, and winding around a roll. In addition, since the epoxy-modified block polymer generally has high insulating properties, static electricity is likely to be generated, which becomes a problem when the generation of static electricity has a significant effect on the quality of products, such as in semiconductor manufacturing. In this invention, in order to solve these problems, electroconductive metal oxide fine particles are mix | blended with an easily bonding layer as an antistatic agent and an antiblocking agent.

  The type of conductive metal oxide fine particles used in the present invention is not particularly limited, and examples thereof include tin-doped indium oxide, antimony-doped tin oxide, tin oxide, zinc antimonate, indium oxide, antimony pentoxide, and zinc oxide. One type or a combination of two or more types. Of these conductive metal oxide fine particles, it is more preferable to use antimony-doped tin oxide because excellent conductivity and transparency can be easily obtained.

  The average particle diameter of the conductive metal oxide fine particles is preferably 0.005 to 2 μm, and more preferably 0.01 to 1 μm. If the average particle size is less than 0.005 μm, it is necessary to increase the content of the conductive metal oxide fine particles in order to obtain a desired surface resistivity, and as a result, the adhesion performance of the easy-adhesion layer decreases. There is a case. On the other hand, if the average particle diameter exceeds 2 μm, the conductive metal oxide fine particles are likely to settle, and handling may be difficult, or the transparency of the resulting easy-adhesive polyester film may be reduced. is there. In particular, when antimony-doped tin oxide is used, the average particle diameter is more preferably in the range of 0.1 to 0.5 μm.

  The content of the conductive metal oxide fine particles is preferably 50 to 400 parts by mass, and more preferably 80 to 200 parts by mass with respect to 100 parts by mass of the epoxy-modified block polymer. When the content of the conductive metal oxide fine particles is less than 50 parts by mass, the electrical resistance between the adjacent conductive metal oxide fine particles increases, and as a result, the value of the surface resistivity may increase. On the other hand, when the content exceeds 400 parts by mass, the adhesion performance and transparency of the easy-adhesion layer to be obtained may be deteriorated.

  The volume resistance (powder resistance) value of the conductive metal oxide fine particles is preferably 1000 Ωcm or less. When the volume resistance of the conductive metal oxide fine particles exceeds 1000 Ωcm, the electrical resistance between the adjacent conductive metal oxide fine particles increases, and as a result, the value of the surface resistivity may increase, and a predetermined surface resistance In order to obtain the rate, it must be added in a large amount, and the total light transmittance may be lowered.

  The easy-adhesion layer in the present invention needs to contain an acrylic / styrene copolymer in addition to the epoxy-modified block polymer and the conductive metal oxide fine particles. Generally, when an epoxy-modified block polymer having a low polarity and conductive metal oxide fine particles having a high polarity are mixed, they are not compatible with each other. It may become cloudy and remarkably deteriorate transparency. In the present invention, in order to solve this problem, an acrylic / styrene copolymer is blended in the easily adhesive layer as a compatibilizing agent.

  The acrylic / styrene resin used in the present invention is a resin obtained by polymerizing a styrene monomer and an acrylic acid monomer.

  Examples of the styrene monomer include styrene, α-methyl styrene, vinyl toluene, pt-butyl toluene, and chlorostyrene.

  Examples of acrylic monomers include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and n-amyl (meth) acrylate. , Isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid Examples include (meth) acrylic acid ester monomers such as hydroxypropyl, and glycidyl esters of ethylenically unsaturated acids such as glycidyl (meth) acrylate. In the present specification, (meth) acryl means acryl or methacryl. These polymerizable monomers can be used alone or in combination of two or more.

  The content of the acrylic / styrene copolymer is preferably 30 to 200 parts by mass, and more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the epoxy-modified block polymer. When the content of the acrylic / styrene copolymer is less than 30 parts by mass, the compatibility with the photocurable resin is not good, and the adhesiveness is lowered. Furthermore, the compatibility between the conductive metal oxide fine particles and the epoxy-modified block copolymer is not good, and the coated surface may become cloudy. On the other hand, if the content exceeds 200 parts by mass, the adhesion with the polyester film is lowered, and the photocurable resin may be cured and peeled between the film and the easy-adhesion layer.

  The weight average molecular weight of the acrylic / styrene resin is preferably in the range of 500 to 500,000. If the weight average molecular weight is less than 500, there is a possibility that adhesion may be lowered due to precipitation of the substance on the surface of the easy adhesion layer. On the other hand, if the weight average molecular weight exceeds 500,000, it is difficult to handle the solution, and the compatibility with the epoxy-modified block polymer or the dispersibility of the conductive metal fine particles is deteriorated. There is a possibility of performance degradation.

  In the present invention, as a method for forming an easy-adhesion layer on one or both sides of a polyester film, a solution containing an epoxy-modified block polymer, conductive metal oxide fine particles, and an acrylic / styrene copolymer is applied to the polyester film. The method of doing is mentioned. MEK, toluene, etc. are mentioned as a solvent which melt | dissolves the said component which comprises an easily bonding layer. The solid content concentration of the solution is preferably 5 to 20% by mass. If the solid content concentration is less than 5% by mass, poor appearance due to uneven evaporation of the solvent and deterioration of antistatic performance are likely to occur. On the other hand, if it exceeds 20% by mass, coating appearance defects such as coating stripes and gravure plate marks are likely to occur. Examples of the solution coating method include a direct gravure method, a Meyer bar method, a spin coating method, a kiss gravure method, and a coating die method. Examples of the method for removing the solvent include a method of heating at 110 to 150 ° C. for 10 to 30 seconds using a hot air dryer, an infrared heater or the like.

  The thickness of the easy-adhesion layer formed on the polyester film surface is preferably 0.3 to 3.0 μm. When the thickness exceeds 3.0 μm, the transparency of the easy-adhesion layer decreases, and when the thickness is less than 0.3 μm, the surface specific resistance value increases and the adhesion may decrease.

In the easy-adhesive polyester film of the present invention, the photocurable resin layer provided on the surface of the easy-adhesive layer is not particularly defined. However, in terms of versatility and handleability, an ultraviolet curable resin layer, and further an ultraviolet curable radical polymerization resin. A layer is desirable. Among these, the easily adhesive polyester film of the present invention is suitable as a base film for a hard coat layer made of an ultraviolet curable resin.
Examples of the ultraviolet curable resin include ultraviolet curable compositions such as urethane-acrylate, epoxy acrylate, and polyester-acrylate. In particular, in order for the hard coat layer resin itself to follow the expansion and contraction of the base material, an acrylate-based photocurable resin containing a urethane component as a soft segment is preferable.
Furthermore, it is desirable to contain inorganic fine particles in order to improve the abrasion resistance of the coating film and to reduce the volume shrinkage rate upon curing. The content of the inorganic fine particles is preferably 20 to 60% by mass, and the average particle size of the inorganic fine particles is preferably 100 nm or less. Further, in order to improve the hard coat property, it is preferable to introduce a photosensitive group having photopolymerization reactivity on the surface of the inorganic fine particles. The photosensitive group is preferably a monofunctional or polyfunctional acrylate. When the content of the inorganic fine particles is less than 20% by mass, the abrasion resistance is poor and the volumetric shrinkage during UV curing is high, and the film is curled. If it is 60% by mass or more, the stretchability of the hard coat resin becomes poor, and cracking due to bending tends to occur. As the inorganic fine particles, fine particles made of a metal oxide such as silica or titanium are preferable.

EXAMPLES Hereinafter, although an Example demonstrates this invention further, it is not limited to this.
In addition, the liquid used for coating agent preparation is as follows.
Liquid A: 30 mass% solid content solution of epoxy group-containing styrene-butadiene-styrene block copolymer (weight average molecular weight = 30000, epoxy equivalent = 1000 g / equiv.) (Solvent: toluene)
B1 liquid: 30 mass% solid content solution of acrylic-styrene copolymer (weight average molecular weight = 8000) (solvent: toluene / MEK (1/1))
B2 liquid: 30% solid content solution of acryl-styrene copolymer (weight average molecular weight = 16000, hydroxyl value = 94 mg-KOH / g) (solvent: toluene / MEK (1/1))
B3 liquid: 30 mass% solid content solution (solvent: toluene / MEK (1/1)) of acrylic-styrene copolymer (weight average molecular weight = 150,000)
B4 liquid: 30 mass% solid content solution (solvent: toluene / MEK (1/1)) of acrylic-styrene copolymer (weight average molecular weight = 270000)
C liquid: 33 mass% solution (solvent: MEK) of antimony dope tin oxide fine particle dispersion (average particle diameter = 110 nm)

The measuring method of the physical property of the obtained film is shown below. In addition, as long as the principle is the same, a machine, an apparatus, etc. may differ.
(1) Blocking resistance:
After the film having the easy-adhesion layer was cut into A4 plates, 10 sheets were stacked so that the easy-adhesion layers were in contact with each other, and left for one week at room temperature. The case where blocking did not occur was indicated as ◯, and the case where blocking was indicated as x.
(2) Adhesion with the UV curable resin layer:
As an ultraviolet curable resin layer, Sekisui Chemical Co., Ltd. adhesive tape “Selfa” was used, which was attached to the surface of the easy-adhesion layer, and a peel test before and after ultraviolet irradiation was performed. The case where the interfacial peeling between the polyester film / the easy-adhesion layer and the cohesive failure of the easy-adhesion layer was not observed before and after the ultraviolet irradiation, and the case where the interfacial delamination and the cohesive failure were observed were indicated as x.
(3) Transparency:
The surface of the film provided with the easy-adhesion layer was visually confirmed, and the easy-adhesion layer was whitened and made opaque, and x was transparent, and the film was transparent.
(4) Surface resistivity:
Based on JIS-K6911, the surface resistivity value of the easy-adhesion layer was measured in an environment of 23 ° C. × 50% RH using a high resistance meter Hiresta IP manufactured by Dia Instruments Co., Ltd. and MCP-HT260.

Example 1
After mixing 10 g of A liquid, 10 g of B1 liquid, and 30 g of C liquid, after apply | coating to the corona surface of a polyester film (Embret S-50 by Unitika), it dried at 120 degreeC and obtained the easily bonding film. Table 1 shows the characteristics of the easily adhesive polyester film obtained.

Example 2
After 5 g of B1 liquid and 30 g of C liquid were mixed with 15 g of A liquid, it was applied to a corona surface of a polyester film emblet S-50 manufactured by Unitika Ltd. and dried at 120 ° C. to obtain an easy-adhesive film.

Example 3
An easy-adhesive film was obtained in the same manner as in Example 1 except that the B2 liquid was used instead of the B1 liquid.

Example 4
An easy-adhesive film was obtained in the same manner as in Example 2 except that the B2 liquid was used instead of the B1 liquid.

Example 5
After mixing 10 g of A liquid, 10 g of B3 liquid, and 30 g of C liquid, it was applied to a corona surface of a polyester film emblet S-50 manufactured by Unitika Ltd. and dried at 120 ° C. to obtain an easy-adhesive film.

Example 6
An easy-adhesive film was obtained in the same manner as in Example 5 except that the B4 liquid was used instead of the B3 liquid.

Comparative Example 1
After mixing 30 g of C solution with 20 g of B1 solution, it was applied to a corona surface of a polyester film emblet S-50 manufactured by Unitika Ltd. and dried at 120 ° C. to obtain an easy-adhesion film.

Comparative Example 2
An easy-adhesive film was obtained in the same manner as in Comparative Example 1 except that the liquid A was used instead of the liquid B1.

Comparative Example 3
After mixing 10 g of B1 liquid with 10 g of A liquid, it applied at the corona surface of the polyester film emblet S-50 made by Unitika, and dried at 120 ° C. to obtain an easily adhesive film.

Comparative Example 4
The corona surface of unitika polyester film emblet S-50 was used as an easy adhesion treatment layer.

Claims (5)

A polyester film having at least one easy-adhesion layer, wherein the easy-adhesion layer comprises a polymer block (A) mainly composed of a vinyl aromatic compound and a polymer block (B) mainly composed of a conjugated diene compound. A block copolymer or a partially hydrogenated product thereof, which is composed of an epoxy-modified block polymer in which a carbon-carbon double bond of the conjugated diene is epoxidized, and the easy-adhesion layer includes conductive metal oxide fine particles and An easy-adhesive polyester film comprising an acrylic / styrene copolymer. The easily adhesive polyester film according to claim 1, wherein the conductive metal oxide fine particles are fine particles made of antimony-doped tin oxide. The easily adhesive polyester film according to claim 1 or 2, wherein the content of the conductive metal oxide fine particles is 50 to 400 parts by mass with respect to 100 parts by mass of the epoxy-modified block polymer. The easily adhesive polyester film according to any one of claims 1 to 3, wherein the content of the acrylic / styrene copolymer is 30 to 200 parts by mass with respect to 100 parts by mass of the epoxy-modified block polymer. . The polyester film according to claim 1, wherein a photocurable resin layer is provided on the easy adhesion layer.