JP2020019917A - Laminated film - Google Patents

Abstract

To provide an adhesive composition that has a sufficient adhesive force upon sticking to an adherend having fine surface ruggedness and is less likely to cause an increase in adhesive force even with exposure to high temperature during transportation and storage.SOLUTION: A laminated film has an adhesive layer comprising an adhesive resin composition composed mainly of a styrene-based elastomer on at least one surface of a base material layer. In the laminated film, a tensile storage elastic modulus E', a tensile loss elastic modulus E'' and a loss tangent tanδ, respectively, at 1 Hz and 10 to 60°C of the adhesive resin composition satisfies the following formulae (1) to (3): (1) 1E+6≤E'(Pa)≤1E+8; (2) 1E+5≤E''(Pa)≤1E+7; and (3) 0.1≤tanδ≤0.5.SELECTED DRAWING: None

Description

  The present invention relates to a laminated film having an adhesive layer made of an adhesive composition. In detail, when the laminated film is stored in a roll state and then unwound, the film is not stretched or deformed, has excellent workability, and has excellent adhesiveness and peelability to adherends. The present invention relates to an adhesive resin composition having excellent adhesiveness and a laminated film having an adhesive layer comprising the same.

Conventionally, laminated films have been stored by stacking members such as prism sheets used for optical applications, synthetic resin plates used for building materials, stainless steel plates, aluminum plates, decorative plywood, steel plates, glass plates, It has been used to protect it from damage during transport or secondary processing such as bending and pressing. It has also been used to protect household appliances, precision machinery and automotive bodies from being damaged during transport during the manufacturing process.
Such a laminated film must have good adhesiveness and be able to be easily peeled off after use without contaminating the surface of the adherend with the adhesive.

In recent years, the adherends have been diversified, and a large number of adherends have been found, from those having a smooth covering surface to those having surface irregularities.
Among them, the back surface of the prism sheet is smoother than the prism surface having large surface irregularities, but the back surface having fine surface irregularities is formed, and in addition to uniformly diffusing the light of the backlight, there is a possibility that the back surface of the prism sheet may be different from other members. A function is provided to prevent interference due to close contact and to make appearance defects such as scratches less noticeable.

For this reason, the back surface of the prism sheet needs to have good adhesive strength with the back surface in order to be protected by the laminated film when being stored and transported in a stacked state.
However, if the time elapses after the laminated film is attached to the adherend, there is a problem that the adhesive strength is increased (so-called increased adhesion), and there is a problem that the peeling becomes difficult. It has been found that this is due to the fact that the product to which the laminated film is attached is exposed to high temperatures during transportation and storage, etc., and becomes more conspicuous.

  As a laminated film used for adherends having fine surface irregularities, it is said that adhesion promotion is relatively unlikely to occur, and a polymer block in which aromatic alkenyl compound units are continuous and mainly consist of aromatic alkenyl compound units, It is known that a copolymer comprising an aromatic alkenyl-conjugated diene monomer copolymer block containing a diene monomer unit and an aromatic alkenyl compound unit at random is used for an adhesive layer (for example, Patent References 1 and 2, etc.), although this has sufficient protection performance for the adherend, but it does not achieve both the ease of peeling from the adherend and the ease of feeding the laminated film from the roll state. .

JP 2014-16934 A Japanese Patent No. 6206749

  An object of the present invention is to store a laminated film having a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition in a roll state, and then, when feeding out the film, the film is not partially stretched or deformed, and the workability is improved. Excellent, yet has sufficient adhesive strength when adhered to an adherend with fine surface irregularities, such as the back surface of a prism sheet, and even when exposed to high temperatures during transportation and storage. Is difficult to promote, no adhesive residue remains on the adherend even after the laminated film is peeled off, and its function is maintained.

The present inventors have conducted intensive studies in order to achieve such an object, and as a result, have reached the present invention.
That is, the present invention is a laminated film having a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive resin composition containing a styrene-based elastomer as a main component on at least one surface of the base material layer, wherein the pressure-sensitive adhesive resin composition has a pressure of 1 Hz at 10 to 60 ° C. The laminate film has a tensile storage modulus E ′, a tensile loss modulus E ″, and a loss tangent tan δ that satisfy the following formulas (1) to (3), respectively.
2E + 6 ≦ E ′ (Pa) ≦ 1E + 8 (1)
2E + 5 ≦ E ″ (Pa) ≦ 1E + 7 (2)
0.1 ≦ tan δ ≦ 0.5 (3)

It is preferable that the loss tangent tan δ at 1 Hz of the pressure-sensitive adhesive resin composition does not have a maximum value at 10 to 60 ° C., and the ratio between the maximum value and the minimum value is 5 or less.

It is preferable that the styrene-based elastomer satisfies the following 1) and 2).
1) A block copolymer containing the following polymer block A and the following polymer block B, and having the structural formula ABA and / or AB.
Polymer block A: a polymer block mainly composed of units derived from an aromatic alkenyl compound monomer unit, and mainly composed of units derived from an aromatic alkenyl compound monomer unit. Polymer block B : Aromatic alkenyl monomer-conjugated diene monomer copolymer block randomly containing units derived from a conjugated diene monomer unit and an aromatic alkenyl compound monomer unit 2) In the polymer block B, The hydrogenation rate of the double bond derived from the conjugated diene monomer unit is 90 mol% or more.

  The laminated film according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive resin composition contains a phenol copolymer.

It is preferable that the base layer is made of a polypropylene resin.

  The average surface roughness Ra of the adhesive layer surface is preferably 0.05 to 0.50 μm.

  It is preferable that a release layer having an average surface roughness (Ra) of 0.10 to 1.00 μm is provided on the side of the base layer opposite to the adhesive layer.

  It is preferable that the release layer is made of a resin composition containing polymethylpentene.

  It is preferable that the laminated film is used for protecting the back surface of the prism sheet.

Here, that the tensile storage modulus E ′ at 10 to 60 ° C. satisfies the expression (1) means that both the maximum value and the minimum value of the tensile storage modulus E ′ at 10 to 60 ° C. satisfy the formula (1). It means that the tensile loss elastic modulus E ″ at 10 to 60 ° C. satisfies the expression (2) when both the maximum value and the minimum value of the tensile loss elastic modulus E ″ at 10 to 60 ° C. (2) It means that it satisfies.
The expression that the loss tangent tan δ at 10 to 60 ° C satisfies Expression (3) means that the maximum value and the minimum value of the loss tangent tan δ at 10 to 60 ° C both satisfy Expression (3).

  In the present invention, the tensile storage modulus E ′ and the tensile loss modulus E ″ of the adhesive resin composition can be calculated by the methods described in Examples.

  The laminated film of the present invention is stored in a roll state, and when the film is fed out thereafter, the film is not partially stretched or deformed, has excellent workability, and has a fine structure such as a back surface of a prism sheet. When applied to an adherend with a rough surface, it has sufficient adhesive strength, and its adhesive strength is not easily increased even when exposed to high temperatures during its transportation and storage. There is no adhesive residue on the body, and the function can be maintained.

The laminated film of the present invention is a laminated film having an adhesive layer composed of an adhesive resin composition containing a styrene-based elastomer as a main component on at least one surface of a substrate layer, wherein the adhesive resin composition has a frequency of 1 Hz, 10 to 60. The tensile storage modulus E ′, the tensile loss modulus E ″, and the loss tangent tan δ at 0 ° C. satisfy the following expressions (1) to (3), respectively.
2E + 6 ≦ E ′ (Pa) ≦ 1E + 8 (1)
2E + 5 ≦ E ″ (Pa) ≦ 1E + 7 (2)
0.1 ≦ tan δ ≦ 0.5 (3)

Here, that the tensile storage modulus E ′ at 10 to 60 ° C. satisfies the expression (1) means that both the maximum value and the minimum value of the tensile storage modulus E ′ at 10 to 60 ° C. satisfy the formula (1). It means that the tensile loss elastic modulus E ″ at 10 to 60 ° C. satisfies the expression (2) when both the maximum value and the minimum value of the tensile loss elastic modulus E ″ at 10 to 60 ° C. (2) It means that it satisfies.
The expression that the loss tangent tan δ at 10 to 60 ° C satisfies Expression (3) means that the maximum value and the minimum value of the loss tangent tan δ at 10 to 60 ° C both satisfy Expression (3).

  In the present invention, the tensile storage modulus E ′ and the tensile loss modulus E ″ of the adhesive resin composition can be calculated by the methods described in Examples.

  The pressure-sensitive adhesive resin composition used in the pressure-sensitive adhesive layer of the present invention has a range of pressure-sensitive adhesive strength such that a laminated film using the pressure-sensitive adhesive layer easily adheres to the back surface of the optical prism sheet and does not float on the adherend surface. It is important that the tensile storage modulus E ″ in the temperature range of 1 Hz and 10 to 60 ° C. satisfies the expression (1).

  2E + 6 ≦ E ′ (Pa) ≦ 1E + 8 (1)

  Here, that the tensile storage modulus E ′ at 10 to 60 ° C. satisfies the expression (1) means that the maximum value and the minimum value of the tensile storage modulus E ″ at 10 to 60 ° C. are both the expression (1). It means to satisfy.

  When E 'is less than 2E + 6 Pa, the adhesive force with the adherend increases with time, and in some cases, peeling may be difficult. When E ′ exceeds 10E + 7 Pa, the laminated film may float on the surface of the adherend without exhibiting the adhesive force to the adherend. E 'is more preferably 2E + 6 to 7E + 7Pa, further preferably 3E + 5 to 5E + 7Pa, and particularly preferably 4E + 5 to 3E + 7Pa.

The pressure-sensitive adhesive resin composition used for the pressure-sensitive adhesive layer of the present invention is measured at 1 Hz so that the laminated film using the pressure-sensitive adhesive layer is easily adhered to the back surface of the optical prism sheet, or in a range of adhesive force such that the adhesive film is easily peeled off. It is important that the tensile loss modulus E ″ at 10 to 60 ° C. (hereinafter sometimes referred to as E ″) satisfies the expression (2).
2E + 5 ≦ E ″ (Pa) ≦ 1E + 7 (2)
Here, that the tensile loss elastic modulus E ″ at 10 to 60 ° C. satisfies the expression (2) means that both the maximum value and the minimum value of the tensile loss elastic modulus E ″ at 10 to 60 ° C. ).

  When the tensile storage loss modulus E '' is less than 2E + 5 Pa, the pressure-sensitive adhesive layer becomes too soft, so that the pressure-sensitive adhesive force with the adherend increases with time, and in some cases, peeling becomes difficult. If E ″ exceeds 10E + 6 Pa, the laminated film may float on the surface of the adherend without exhibiting the adhesive force to the adherend. The tensile loss modulus E ″ is more preferably 2E + 5 to 8E + 6 Pa, more preferably 3E + 5 to 6E + 6 Pa, and particularly preferably 4E + 5 to 4E + 6 Pa.

It is important that the loss tangent tan δ at 1 Hz of the pressure-sensitive adhesive resin composition satisfies the following expression (3) in that stable peelability is obtained.
0.1 ≦ tan δ ≦ 0.5 (3)

When the loss tangent tan δ is less than 0.1, the adhesive force with the adherend increases with time, and in some cases, peeling may be difficult. On the other hand, when tan δ exceeds 0.5, it becomes easier to peel. The loss tangent tan δ is more preferably 0.11 to 0.5, even more preferably 0.11 to 0.4, and particularly preferably 0.11 to 0.36.
.

  It is preferred that the loss tangent tan δ at 1 Hz of the pressure-sensitive adhesive resin composition does not have a maximum value at 10 to 60 ° C. for use at a high temperature because the temperature dependency of the pressure-sensitive adhesive force is small.

Further, in order to stabilize the adhesive strength, the loss tangent tan δ at 1 Hz of the adhesive resin composition is preferably 5 or less at a ratio between the maximum value and the minimum value at 10 to 60 ° C.
The ratio of the maximum value to the minimum value at 10 to 60 ° C is more preferably 4 or less, and particularly preferably 3 or less. It is sufficient if the ratio between the maximum value and the minimum value at 10 to 60 ° C is 1 or more.

  In the present invention, the method for controlling the tensile storage elastic modulus E ′, the tensile loss elastic modulus E ″ and the loss tangent tan δ of the pressure-sensitive adhesive resin composition within the above ranges is as follows. , Α-methylstyrene and terpene resins are preferably used, but are not limited thereto.

(Styrene-based elastomer)
The styrene-based elastomer contained in the adhesive resin composition of the present invention is preferably a block copolymer containing the following polymer block A and the following polymer block B.
Polymer block A: a polymer block mainly composed of units derived from an aromatic alkenyl compound monomer unit, and mainly composed of units derived from an aromatic alkenyl compound monomer unit. Polymer block B : Aromatic alkenyl compound monomer-conjugated diene monomer copolymer block randomly containing units derived from a conjugated diene monomer unit and an aromatic alkenyl compound monomer unit

The block copolymer of the present invention is a block copolymer containing the above-mentioned polymer block A and polymer block B and having the structural formula ABA and / or AB.
The block copolymer of the present invention is an aromatic alkenyl compound monomer-conjugated diene monomer copolymer block containing units derived from a conjugated diene monomer unit and an aromatic alkenyl compound monomer unit at random. By having a certain polymer block B, compared to other block copolymers, when the laminated film is applied to an adherend having fine surface irregularities and then exposed to high temperatures during its transportation and storage However, the increase in adhesion is unlikely. Above all, it is preferable to use only the structural formula ABA in which the polymer blocks A are present at both ends, since the increase in adhesion at high temperatures is further suppressed.

The content of the units derived from the aromatic alkenyl compound monomer units in the block copolymer is preferably 30% by weight or more.
When the content of the unit derived from the aromatic alkenyl compound monomer unit is 30% by weight or more, the tensile storage modulus E ′ is easily increased. The content of the unit derived from the aromatic alkenyl compound monomer unit is preferably 60% by weight or less, and more preferably 60% by weight or less, and the tensile loss is 60% by weight or less. The elastic modulus E ″ is unlikely to be too large. It is more preferably at most 55% by weight.
The content (St (A + B)) of the unit derived from the aromatic alkenyl compound monomer in the block copolymer represents a numerical value defined by the following formula.
The content of the unit derived from such an aromatic alkenyl compound monomer unit is determined by 1H-NMR. The content of the unit derived from such an aromatic alkenyl compound monomer unit can also be determined by an infrared spectrum method, and a value almost equivalent to 1H-NMR is obtained.

St (A + B) =
(Mass of the unit derived from the aromatic alkenyl compound monomer unit in the block copolymer)
/ (Mass of all units derived from monomers in the block copolymer) × 100 (% by weight)

The weight average molecular weight of the block copolymer is preferably from 100,000 to 200,000.
When the weight average molecular weight is 200,000 or less, the tensile loss elastic modulus E ″ is easily increased, and the adhesive strength to the adherend having surface irregularities is easily obtained. In addition, industrial processing into pellets or film production by melt coextrusion may be facilitated in some cases. The weight average molecular weight of the block copolymer is more preferably 180,000 or less.
When the weight average molecular weight is 100,000 or more, the tensile storage elastic modulus E ′ is easily increased, and adhesion increase on an adherend having surface irregularities is unlikely to occur. In addition, in the process of removing the solvent and drying the polymer, the polymer hardly adheres to a manufacturing facility or the like, which may make industrial production easy. The weight average molecular weight of the block copolymer is more preferably 130,000 or more, and further preferably 150,000 or more.

The melt flow rate (MFR) value of the block copolymer is preferably in the range of 0.1 to 20 g / min, more preferably 1 to 15 g / min. By setting the melt flow rate value in the range of 0.1 to 20 g / min, not only can industrial production of the block copolymer be facilitated, but also excellent workability can be provided during film formation. be able to. When the melt flow rate value is less than 0.1 g / min, the solubility in a solvent during polymerization is deteriorated, the heat fusibility is reduced, and it may be difficult to remove the polymer from the production equipment. This difficulty is a problem that can recur during film formation. The melt flow rate value is more preferably 2 g / min or more, further preferably 3 g / min or more.
On the other hand, when the melt flow rate is more than 20 g / min, in the step of removing the solvent and drying the polymer, the polymer adheres and remains inside the production equipment and the like, and it becomes difficult to take out the polymer. This difficulty is a problem that can recur during film formation. The melt flow rate value is more preferably 10 g / min or less, and even more preferably 6 g / min or less.

(Polymer block A)
The polymer block A in the present invention is constituted by a unit derived from an aromatic alkenyl compound monomer unit as a main repeating unit, and is mainly composed of a unit derived from an aromatic alkenyl compound monomer unit. However, the content of the unit derived from the aromatic alkenyl compound monomer unit in the polymer block A is preferably 80% by weight or more.
By setting the unit derived from the aromatic alkenyl compound monomer unit in the polymer block A to 80% by weight or more, it is easy to suppress the thermoplasticity of the adhesive resin composition and increase the tensile storage modulus E ′. There is an advantage to say. The unit derived from the monomer unit of the aromatic alkenyl compound in the polymer block A is more preferably 90% by weight or more.

The repeating unit other than the unit derived from the aromatic alkenyl compound monomer unit may be contained in an amount of less than 20% by weight.
The aromatic alkenyl compound monomer unit is not particularly limited, for example, styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, Examples include aromatic alkenyl monomer units such as vinylnaphthalene, vinylanthracene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and vinylpyridine.
Among the aromatic vinyl alkenyl monomer units, a styrene unit is preferable because the raw material is easily available.
The repeating unit other than the unit derived from the aromatic alkenyl compound monomer alone is a repeating unit derived from a compound copolymerizable with the unit derived from the aromatic alkenyl compound monomer alone, for example, a conjugated diene compound or The repeating unit derived from a (meth) acrylate compound can be mentioned. Among them, 1,3-butadiene and isoprene are preferred because of their high copolymerizability with units derived from aromatic alkenyl compound units.

  The content of the polymer block A in the block copolymer is preferably 10% by weight or more. When the content of the polymer block A is 10% by weight or more, the tensile loss modulus E ″ does not become too small, and the initial adhesive strength is easily obtained. Alternatively, the tensile storage elastic modulus E 'does not become too small, and the adhesive strength does not easily increase. On the other hand, the content of the polymer block A in the block copolymer is preferably 50% by weight or less. When it is 50% by weight or less, the tensile loss modulus E '' is not too small, and the initial adhesive strength is easily obtained. More preferably, it is at most 45% by weight, even more preferably at most 40% by weight.

(Polymer block B)
The polymer block B in the present invention is an aromatic alkenyl monomer-conjugated diene monomer containing units derived from conjugated diene monomer units and units derived from aromatic alkenyl compound monomer units at random. It is a polymer block. By randomly containing a unit derived from a conjugated diene unit and a unit derived from an aromatic alkenyl compound unit, a laminated film using the adhesive resin composition of the present invention is attached to an adherend having fine surface irregularities. After being attached, even when exposed at a high temperature during transportation and storage, the tensile storage elastic modulus E 'does not decrease, and the adhesion does not easily increase.
Here, "randomly" is interpreted in a broad sense, and the chain distribution of the conjugated diene unit and the aromatic alkenyl compound unit is a certain statistical rule obtained by simultaneously polymerizing a mixed conjugated diene and aromatic alkenyl compound. It means that it is in the state according to.
The aromatic alkenyl compound monomer unit is not particularly limited, for example, styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, Examples include aromatic vinyl monomer units such as vinylnaphthalene, vinylanthracene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and vinylpyridine.
Among the aromatic vinyl monomer units, a styrene unit is preferable because the raw material is easily available.
The conjugated diene monomer unit in the polymer block B in the present invention is not particularly limited. For example, 1,3-butadiene, 1,2-butadiene, isoprene, 2,3-dimethyl-butadiene, 1,3- Pentadiene, 2-methyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl Examples thereof include diolefins such as -1,3-octadiene, myrcene, and chloroprene.
Among the diolefins, at least one unit selected from a 1,3-butadiene unit or an isoprene unit, which has high polymerization reactivity and is easily available as a raw material, is preferable. Further, in order to obtain high mechanical strength, it is more preferable to select 1,3-butadiene unit.

  The hydrogenation rate of the double bond derived from the conjugated diene monomer unit in the block copolymer B in the present invention is preferably 90 mol% or more. It is more preferably at least 95 mol%, further preferably at least 98 mol%. When it is 90 mol% or more, the tensile loss elastic modulus E ″ is not too small, and not only adhesive strength to an adherend having fine unevenness is easily obtained, but also heat resistance and weather resistance are improved.

The content of the unit derived from the aromatic alkenyl compound monomer unit in the block copolymer B is preferably 10% by weight or more. When the content of the unit derived from the aromatic alkenyl compound monomer unit is 10% by weight or more, the tensile loss modulus E ″ is not too small, the initial adhesive strength is not too strong, and the adhesive residue hardly occurs. Alternatively, the tensile storage modulus E 'is not too small, and the initial adhesive strength is hard to increase. The content of the unit derived from the aromatic alkenyl compound monomer unit is more preferably 20% by weight or more, and particularly preferably 30% by weight or more.
On the other hand, the content of the unit derived from the aromatic alkenyl compound monomer unit is preferably 80% by weight or less. When it is at most 80% by weight, the tensile storage modulus E 'will not be too large, and the initial adhesive strength will be easily obtained. The content of the unit derived from the aromatic alkenyl compound monomer unit is more preferably 50% by weight or less, and particularly preferably 40% by weight or more.

(Α-methylstyrene resin)
As a result of intensive studies, the α-methylstyrene-based resin increases the tensile storage modulus E ′ of the adhesive resin composition, suppresses the increase in adhesion, and increases the surface of the base material layer or the release layer opposite to the surface of the adhesive layer. It has the effect of improving the releasability between the surface and the adhesive layer surface. In addition, it has been found that since the effect of the terpene-based resin described later is hardly hindered, the initial adhesive strength can be sufficiently obtained without lowering the tensile loss elastic modulus E ″. It is presumed that this is due to the fact that the α-methylstyrene-based resin also diffuses into the polymer block B of the block copolymer and reduces free deposition.
Such an effect simply depends on the content of the unit derived from the aromatic alkenyl compound monomer in the block copolymer having the structural formula ABA and / or AB and the weight in the block copolymer. This is an effect that cannot be obtained simply by increasing the content of the united block A or increasing the molecular weight of the block copolymer.

As the α-methylstyrene resin used in the present invention, α-methylstyrene homopolymer and / or α-methylstyrene as a main component, styrene and p-methylstyrene, p-chlorostyrene, chloromethylstyrene, Copolymers composed of two or more styrene compounds such as tert-butylstyrene, p-ethylstyrene, divinylbenzene and the like can be mentioned.
The α-methylstyrene resin may be a copolymer with an aliphatic monomer.
It is preferable that the molecular weight Mw is 4000 or more from the viewpoint of resin strength and bleed-out. In the case of a copolymer composed of two or more monomers, it may be a block copolymer or a random copolymer.
Among them, the α-methylstyrene-based resin preferably has a softening point of 100 ° C. or higher, and more preferably 150 ° C. or higher. Specifically, trade name “ENDEX155” (manufactured by Eastman Chemical Co., Ltd., softening point 155 ° C., molecular weight Mz = 13850, Mw = 6950, Mn = 2400, Mw / Mn = 3.0, density = 1.04 g / ml) , Glass transition temperature = 99 ° C), “ENDEX160” (softening point 160 ° C) and the like.

(Terpene resin)
As a result of intensive studies, the terpene-based resin or its hydrogenated product increases the tensile loss modulus E '' of the adhesive resin composition, sufficiently develops the adhesive force to the adherend, and adheres to the laminated film. It tends to be in close contact with the body surface. Moreover, since the effect of the α-methylstyrene-based resin described above is not easily inhibited, the tensile storage elastic modulus E ′ is not reduced, the adhesive force with the adherend is hardly increased with time, and peeling is easily performed. This is presumed to be due to the fact that the terpene-based resin also diffuses into the polymer block B portion of the block copolymer, and has both the effect of plasticizing while increasing Tg and the effect of adhesive force due to electric action. .

In the present invention, a terpene-based resin or a hydrogenated product thereof is exemplified.
The terpene-based resin is obtained by cation polymerization using a terpene-based compound (for example, α-pinene, β-pinene, limonene, etc.) collected from the skin of a pine tree or orange. The terpene resins are roughly classified into polyterpene resins, which are polymers of terpene monomers, aromatic modified terpene resins obtained by copolymerizing terpene monomers and aromatic monomers, terpene phenol resins obtained by reacting terpene monomers with phenols, and Are classified as hydrogenated terpene resins obtained by hydrogenating them.
When the terpene resin is a hydrogenated resin, the fear of discoloration due to high temperature or aging can be reduced.
The terpene resins may be used alone or in combination of two or more. The terpene resin preferably has a glass transition temperature or softening point of 30 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 65 ° C. or higher, and particularly preferably 90 ° C. or higher.

Among terpene-based resins, terpene phenol resins are preferable, and hydrogenated terpene phenol resins are particularly preferable. Since the phenol group of the terpene phenol resin has an electrical affinity with the adherend, the product to which the laminated film is attached is hardly increased in its adhesive strength even when exposed to high temperatures during its transportation and storage. High adhesive strength is expected. Terpene phenol resin has a high softening point, about 130 ° C.
Also, in the case of terpene phenol resin, the concern of discoloration due to high temperature or aging can be reduced by hydrogenation.

(Adhesive resin composition)
It is a particularly preferred embodiment that the adhesive resin composition of the present invention contains the styrene-based elastomer described in paragraph 0020 as a main component, and contains an α-methylstyrene-based resin and a terpene-based resin. Here, the main component means that 50% by weight or more is contained in the adhesive resin composition.
In this case, it is preferable that the α-methylstyrene resin is contained in an amount of 1 to 50 parts by weight, more preferably 5 to 45 parts by weight, further preferably 10 to 40 parts by weight, and more preferably 15 to 40 parts by weight based on 100 parts by weight of the styrene elastomer. Part by weight is particularly preferred. It is preferable that the α-methylstyrene resin is at least 10 parts by weight based on 100 parts by weight of the block copolymer.
Also, at this time, it is preferable that the styrene-based elastomer is contained in an amount of 1 to 50 parts by weight, more preferably 3 to 50 parts by weight, and still more preferably 5 to 50 parts by weight based on 100 parts by weight of the styrene-based elastomer. is there. It is preferable that the terpene resin is contained in an amount of 15 parts by weight or less based on 100 parts by weight of the block copolymer.
The content of the terpene resin is more preferably 40 parts by weight or less, further preferably 30 parts by weight or less, and particularly preferably 25 parts by weight or less.

  The adhesive resin composition of the present invention may contain, in addition to the above-described block copolymer, α-methylstyrene-based resin, and terpene-based resin, if necessary, an organic lubricant, an antioxidant, a light stabilizer, and an ultraviolet absorber. Agents, fillers, pigments, known additives such as styrene-based block phase reinforcing agents, softeners, anti-adhesion agents, olefin-based resins, silicone-based resins, liquid acrylic copolymers, and phosphate-based compounds You may. Each is described below.

(Organic lubricant)
The organic lubricant used in the present invention is preferably a saturated fatty acid bisamide or a fatty acid metal salt in consideration of excessive leaching at room temperature or high temperature. Specifically, ethylene bisstearic acid bisamide, metal stearate and the like can be mentioned. These may be used alone or in combination of two or more.

In the pressure-sensitive adhesive resin composition of the present invention. It is preferable to contain 0.1 to 1.5 parts by weight of an organic lubricant based on 100 parts by weight of the block copolymer. An organic lubricant can be expected to have an effect of suppressing an increase in adhesive strength.
When the content of the organic lubricant is 0.1 parts by weight or more, it is easy to suppress the increase in the adhesive strength at high temperature or over time, and it is more preferably 0.2 parts by weight or more.
When the content of the organic lubricant is 1.5 parts by weight or less, it is difficult to bleed out at a high temperature or over time, and there is no fear of contaminating the adherend. However, it is more preferably 1 part by weight or less. It is particularly preferred that the amount is not more than 0.5 parts by weight.
No.
The organic lubricant used in the present invention preferably has a high melting point in view of bleed-out at high temperatures and over time, and specific examples thereof include ethylene bisstearic acid amide and calcium stearate.

(Antioxidant)
The antioxidant used in the present invention is not particularly limited, and examples thereof include phenol-based (monophenol-based, bisphenol-based, polymer-based phenol-based), sulfur-based, and phosphorus-based ones.

(Light stabilizer)
Examples of the light stabilizer used in the present invention include a hindered amine compound.

(UV absorber)
The ultraviolet absorber used in the present invention is not particularly limited, and examples thereof include salicylic acid, benzophenone, benzotriazole, and cyanoacrylate.

(Softener)
The softener refers to a low-melting point conjugated polymer having a melting point of 50 ° C. or lower, a low-melting petroleum oil or a natural oil or fat, for example, a low molecular weight diene polymer, polyisobutylene, hydrogenated polyisobutylene, or hydrogenated. Polybutadiene, paraffinic process oil, naphthenic process oil, aromatic process oil, castor oil, tall oil, natural oil, liquid polyisobutylene resin, polybutene, hydrogenated products thereof, and the like can be used. These softeners may be used alone or in combination of two or more.

(filler)
Examples of the filler include calcium carbonate, magnesium carbonate, silica, zinc oxide, titanium oxide and the like.

(Laminated film)
The laminated film according to the present invention is obtained by laminating an adhesive layer made of the adhesive resin composition on a base material layer. Further, a release layer may be provided on the base material layer opposite to the adhesive layer.
This will be described in detail below.

(Adhesive layer)
The pressure-sensitive adhesive layer in the present invention comprises the above-mentioned pressure-sensitive adhesive resin composition, and has a thickness of usually about 1 to 30 μm, preferably 2 to 10 μm.

(Base material layer)
The substrate layer in the present invention can be formed from a polyolefin-based resin. The polyolefin-based resin contained in the base material is not particularly limited, but may be an ethylene homopolymer, an ethylene-α-olefin copolymer, an ethylene- (meth) acrylic acid copolymer, or an ethylene- (meth) acrylate ester. Polymers and polyethylene resins such as ethylene-vinyl acetate copolymer; polypropylene resins such as propylene homopolymer, propylene-α-olefin copolymer and propylene-ethylene copolymer; butene homopolymer; butadiene And conjugated dienes such as isoprene and the like. Examples of the polyethylene resin include high-density polyethylene, medium-density polyethylene, and low-density polyethylene. The form of the copolymer may be random, block, or terpolymer. The polyolefin resin may be used alone or in combination of two or more.

  The polyethylene resin is obtained by using ethylene as a main component. The proportion of the structural unit derived from ethylene is preferably 50% by weight or more, more preferably 70% by weight or more, and still more preferably 90% by weight or more, based on 100% by weight of the total structural units of the polyethylene resin.

The polypropylene resin is obtained using propylene as a main component. The proportion of structural units derived from propylene is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more, based on 100% by weight of all the structural units of the polypropylene resin.
The base material layer of the present invention is preferably composed mainly of a polypropylene-based resin in terms of heat resistance, weather resistance, and adhesion to an adhesive layer.

  The thickness of the base material layer in the present invention is preferably 10 μm or more, more preferably 100 μm or less. When the thickness of the base material is 10 μm or more and 100 μm or less, the handleability of the laminated film is further improved.

When the laminated film according to the present invention is composed of only a base layer and an adhesive layer made of the adhesive resin composition, surface irregularities are imparted to suppress the peeling force between the surface of the base layer and the surface of the adhesive layer. However, it is preferable to reduce the contact area with the adhesive layer.
In this case, considering the resin composition of the pressure-sensitive adhesive layer of the present invention, it is preferable that the average surface roughness SRa of the surface of the release layer be 0.40 μm or more. It is more preferable that the surface has an average surface roughness of 0.85 μm or less in SRa, and more preferably 0.50 μm or more and 0.70 μm or less.
By setting the average surface roughness SRa of the surface of the pressure-sensitive adhesive layer of the base material layer and the surface of the surface opposite to the pressure-sensitive adhesive layer to 0.40 μm or more, the protection performance and the peeling force of the adherend can be improved. If the surface roughness of the release layer is lower than 0.40 μm, the film will have poor rollability when the film is in a roll form. If the surface roughness of the substrate layer is higher than 0.85 μm, the surface irregularities of the substrate layer may be transferred to the surface of the adhesive layer, and the adhesive strength may be significantly reduced.

In order to make the average surface roughness SRa of the surface of the adhesive layer of the substrate layer and the surface opposite to the adhesive layer 0.40 μm or more, the resin used in the substrate layer is incompatible with homopolypropylene or random polypropylene. A suitable resin can be added, and a propylene-ethylene block copolymer can be suitably used. When a propylene-ethylene block copolymer is used, the state of unevenness is unlikely to change due to a change in a production machine stand or a melt-kneading condition at the time of film formation, and stable production is possible.
The average surface roughness SRa can be increased by increasing the molecular weight of the ethylene-propylene rubber in the propylene-ethylene block copolymer or by increasing the amount of ethylene.
Further, by mixing a resin incompatible with the propylene-ethylene block copolymer, the average surface roughness SRa can be further increased.
Further, in the extrusion step described later, the average surface roughness SRa can be further increased by reducing the tensile speed applied to the resin or increasing the residence time.
On the other hand, in order to reduce the average surface roughness SRa, it is effective to mix a homopropylene resin with a propylene-ethylene block copolymer.

  As a resin incompatible with the propylene-ethylene block copolymer, an α-olefin (co) polymer having 4 or more carbon atoms, such as a 4-methylpentene-1 (co) polymer, can be suitably used. In addition, low-density polyethylene, high-density polyethylene, copolymers of ethylene and a small amount of α-olefin, copolymers of ethylene and vinyl acetate, polystyrene, alicyclic olefin resins, polyester resins, polyamide resins, etc. Is mentioned. Particularly, a 4-methylpentene-1 (co) polymer is preferable because not only the surface is roughened in a mat shape but also the peeling force can be further reduced by lowering the surface free energy of the film surface.

  The amount of the α-olefin (co) polymer having 4 or more carbon atoms in the resin composition constituting the base material layer is in the range of 0% by weight or more and 35% by weight or less. When the compounding amount of the α-olefin (co) polymer having 4 or more carbon atoms exceeds 35% by weight, when the raw materials of the base material layer and the adhesive layer are co-extruded using a T-die or the like, the base material is laminated. The film forming property of the layer is deteriorated.

(Release layer)
The release layer in the present invention can be provided on the substrate layer on the side opposite to the adhesive layer. This makes it possible to cope with a wider range of applications by dispersing the functions in the base layer and the release layer.

In this case, in order to suppress the peeling force between the surface of the release layer and the surface of the adhesive layer, it is preferable to provide surface irregularities to reduce the contact area with the adhesive layer.
In view of the resin composition of the pressure-sensitive adhesive layer of the present invention, it is preferable that the average surface roughness SRa of the surface of the release layer be 0.40 μm or more. It is more preferable that the surface has an average surface roughness of 0.850 μm or less in SRa, and more preferably 0.500 μm or more and 0.700 μm or less.

  By setting the average surface roughness SRa of the surface of the release layer to 0.40 μm or more, the protection performance of the adherend and the peeling force can be improved. If the surface roughness of the release layer is lower than 0.40 μm, the film will have poor rollability when the film is formed into a roll. When the surface roughness of the release layer is higher than 0.850 μm, the surface irregularities of the release layer are transferred to the surface of the adhesive layer, and the adhesive strength may be significantly reduced.

In order to make the average surface roughness SRa of the surface of the release layer 0.40 μm or more, as a resin used for the release layer, a resin incompatible with homopropylene or random polypropylene may be added, or propylene-ethylene may be used. Block copolymers can be suitably used. When a propylene-ethylene block copolymer is used, the state of unevenness is unlikely to change due to a change in a production machine stand or a melt-kneading condition at the time of film formation, and stable production is possible.
The average surface roughness SRa can be increased by increasing the molecular weight of the ethylene-propylene rubber in the propylene-ethylene block copolymer or by increasing the amount of ethylene.
Further, by mixing a resin incompatible with the propylene-ethylene block copolymer, the average surface roughness SRa can be further increased.
Further, in the extrusion step described later, the average surface roughness SRa can be further increased by reducing the tensile speed applied to the resin or increasing the residence time.
On the other hand, in order to reduce the average surface roughness SRa, it is effective to mix a homopropylene resin with a propylene-ethylene block copolymer.

  As the resin incompatible with the propylene-ethylene block copolymer, an α-olefin (co) polymer having 4 or more carbon atoms, such as a 4-methylpentene-1 (co) polymer, can be suitably used. Other examples include low-density polyethylene, high-density polyethylene, a copolymer of ethylene and a small amount of α-olefin, a copolymer of ethylene and vinyl acetate, polystyrene, a polyester resin, and a polyamide resin. Particularly, a 4-methylpentene-1 (co) polymer is preferable because not only the surface is roughened in a mat shape, but also the peeling force can be further reduced by lowering the surface free energy of the film surface.

The amount of the α-olefin (co) polymer having 4 or more carbon atoms in the resin composition constituting the release layer is in the range of 0% by weight to 35% by weight. If the compounding amount of the α-olefin (co) polymer having 4 or more carbon atoms exceeds 35% by weight, the film-forming property of the base material layer will be deteriorated when the base layer and the adhesive layer are co-extruded and laminated.
The thickness of the release layer is not particularly limited. The thickness of the release layer is preferably 2 μm or more, and more preferably 10 μm or less. When the thickness of the release layer is 2 μm or more and 10 μm or less, the handleability of the laminated film is further enhanced.

(Characteristics of laminated film)
The initial adhesive strength of the laminated film of the present invention is preferably 3 cN / 25 mm or more and 20 cN / 25 mm or less. When it is 3 cN / 25 mm or more, it does not peel or float during handling or transportation, and when it is less than 20 cN / 25 mm, it does not require excessive force when peeling. More preferably, it is 4 cN / 25 mm or more and 15 cN / 25 mm or less. More preferably, it is 5 cN / 25 mm or more and 10 cN / 25 mm or less.
The initial adhesive strength was measured as described below.
23 ± 2 ° C. and 50 ± 5% R.H. so that the surface of the adhesive layer of the laminated film is in contact with the back surface of the prism sheet. H. , A linear pressure of 15 kN / m was applied from the side opposite to the surface of the pressure-sensitive adhesive layer of the laminated film, and the film was bonded at a speed of 2 m / min.
The obtained test piece was subjected to 23 ± 2 ° C. and 50 ± 5% RH. H. After being left in the room for 30 minutes, the 180-degree peel strength (unit: cN) at a width of 25 mm was measured under the condition of a peel speed of 300 mm / min according to JIS Z0237, and the result was defined as the initial adhesive strength.

It is preferable that the adhesion enhancement rate of the laminated film of the present invention is 400% or less. When the rate of increase in adhesion is 400% or less, the peeling operation can be performed under more constant conditions, so that the working efficiency is improved. More preferably, it is 300% or less, still more preferably 200% or less.
The adhesion enhancement rate was calculated by the following equation using the initial adhesive strength and the temporal adhesive strength.
Adhesion increase rate = (adhesive strength over time / initial adhesive strength) × 100 (%)

The temporal adhesive force of the laminated film of the present invention is preferably 3 cN / 25 mm or more and 40 cN / 25 mm or less. When it is 3 cN / 25 mm or more, it does not peel or float during handling or transportation, and when it is 40 cN / 25 mm or less, it does not require excessive force when peeling. More preferably, it is 4 cN / 25 mm or more and 40 cN / 25 mm or less. It is more preferably 5 cN / 25 mm or more and 30 cN / 25 mm or less, and particularly preferably 5 cN / 25 mm or more and 20 cN / 25 mm or less.
The adhesive force over time was measured as follows.
A test piece was prepared under the same conditions as the prism sheet used for measuring the initial adhesive force. After leaving for 1 week in an atmosphere of 65 ° C. ± 2 ° C. and a load of 6 kg / 400 cm ² , the 180-degree peel strength at a width of 25 mm was measured at a peel speed of 300 mm / min according to JIS Z0237, and the adhesive strength with time was determined. .

The peel strength of the surface of the pressure-sensitive adhesive layer of the present invention and the surface of the base material layer or the surface of the release layer opposite to the pressure-sensitive adhesive layer is within the range of 10 cN / 25 mm or less at 23 ° C. This is preferable from the viewpoint of the film feeding property. When the peeling force exceeds 10 cN / 25 mm, problems such as partial elongation and deformation of the film occur when the laminated film is rolled out. The peeling force at 23 ° C. is more preferably 5 cN / 25 mm or less, and particularly preferably 3 cN / 25 mm or less.
The lower limit of the peeling force to the surface of the adhesive layer of the laminated film and the surface of the base material layer or the surface of the release layer opposite to the adhesive layer is set to a realistic value of about 1 cN / 25 mm, and further about 2 cN / 25 mm. Is preferred.

(Lamination film production method)
The method for producing the laminated film of the present invention is, for example, a pressure-sensitive adhesive composition and a polyolefin resin for the base material layer, if necessary, a polyolefin resin for the release layer is charged into a separate extruder, melted, Coextrusion from a T-die and lamination, or lamination of other layers on the layer obtained by inflation molding by lamination such as extrusion lamination, extrusion coating, etc. After that, a method of laminating each of the obtained films by dry lamination, etc. may be mentioned, but from the viewpoint of productivity, each material of the release layer, the base material layer, and the pressure-sensitive adhesive layer is a multilayer extruder. Co-extrusion molding is preferable, and T-die molding is more preferable in terms of thickness accuracy.

  The laminated film of the present invention is used for protecting the surface of an adherend having a smooth or fine uneven surface, and is particularly effective when the surface roughness is about 0.1 to 1.0 μm. It is.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
The measuring method is shown below.

(1) Initial adhesive strength The obtained surface laminated film was cut out into a size of 150 mm length (winding direction at the time of film production) × 25 mm width (the direction perpendicular to the winding direction at the time of film production) as a test piece, A test piece was prepared by attaching the pressure-sensitive adhesive layer so that the pressure-sensitive adhesive layer surface was in contact with the back surface of a 150 mm × 35 mm prism sheet (acrylate polymer, SRa = 0.24 μm). Affixed at 23 ± 2 ° C. and 50 ± 5% RH. H. , A linear pressure of 20 N / m was applied from the outside of the surface laminated film (that is, the side opposite to the surface of the pressure-sensitive adhesive layer), and the film was adhered at a speed of 2 m / min. The following laminator was used for attachment.
Laminator Manufacturer: Tester Sangyo Co., Ltd.
Model: SA-1010-S
Roll: Heat resistant silicone rubber roll Roll diameter: Φ200
The obtained test piece was 23 ± 2 ° C. and 50 ± 5% RH. H. After being left in the room for 30 minutes, the 180-degree peel strength (unit: cN) at a width of 25 mm was measured under the condition of a peel speed of 300 mm / min according to JIS Z0237, and the result was defined as the initial adhesive strength.

(2) Adhesion over time The obtained laminated film was adhered under the same conditions as the prism sheet used for the evaluation of the initial adhesive force in (1), and the film was subjected to an adhesion under an atmosphere of 65 ° C. ± 2 ° C. and a load of 6 kg / 400 cm ^2. After standing for a week, 23 ± 2 ° C. and 50 ± 5% R.H. H. Was left still for 1 hour in a room, and the 180-degree peel strength at a width of 25 mm was measured at a peel speed of 300 mm / min in accordance with JIS Z0237, and the adhesive strength over time was determined.

(3) Adhesion enhancement rate Using the initial adhesive strength and the aging adhesive strength obtained in the above (1) and (2), the rate of change from the initial adhesion to the aging adhesion (adhesion enhancement rate) was calculated by the following equation. .
Change rate (adhesion enhancement rate) = (adhesive strength over time / initial adhesive strength) × 100

(4) Peeling force The obtained laminated films were stacked on top of each other and cut into a size of 110 mm (winding direction during film production) x 40 mm (direction perpendicular to the winding direction during film production) to obtain a test piece. The upper and lower sides were sandwiched between copy papers, and a weight of 60 kg was placed thereon, and the paper was allowed to stand in a room at a temperature of 40 ° C. for 72 hours. Thereafter, at 23 ± 2 ° C. and 50 ± 5% RH. H. And the resistance value when peeled 180 ° at a speed of 300 mm / min using “Autograph (registered trademark)” (AGS-J) manufactured by Shimadzu Corporation as a peeling force [cN / 25 mm].
At the time of measurement, a polyester sheet having a thickness of 190 μm and a size of 40 mm × 170 mm was prepared as a grip for the measurement sample, and was adhered to the end of a test piece of 110 mm × 40 mm with cellophane tape with a glue allowance of 15 mm. It was the grab allowance. The measurement was performed three times for one sample, and the average value was defined as the peel force of the sample.

5) Elongation / deformation of the laminated film when the laminated film is fed out After obtaining a film roll of 550 mm width and 500 m winding with a slit, it is stored in a roll state for 7 days in a light shielding environment at a temperature of 23 ° C. and a humidity of 75%. did. Immediately after the storage roll was wound 300 m around another plastic core (diameter 9 cm), the end of the film was grasped by hand and pulled, and the film was rewound 3 m. Upon rewinding, the film was visually checked for any partial elongation or deformation. A sample without partial elongation or deformation was evaluated as ○ (good), and a sample with partial expansion or deformation was evaluated as x (bad).

6) Adhesive residue or transfer after peeling from adherend The obtained laminated film is adhered under the same conditions as those of the prism sheet used for the evaluation of the initial adhesive strength in (1), and a load of 65 ° C ± 2 ° C is applied. After standing for one week in an atmosphere of 6 kg / 400 cm ^2, the temperature was 23 ± 2 ° C. and the relative humidity was 50 ± 5% R. H. Was left still for 1 hour. Subsequently, the film was peeled off by hand, and the presence or absence of adhesive residue on the back surface of the prism sheet was visually checked. If there was no adhesive residue or transferred matter, it was evaluated as ○ (good), and if there was any adhesive residue or transferred matter, it was evaluated as x (bad).

7) Surface roughness The surface roughness of the obtained laminated film on the side opposite to the adhesive layer was evaluated using a three-dimensional roughness meter (manufactured by Kosaka Laboratory Co., Ltd., model number ET-30HK) at a stylus pressure of 20 mg. Measurement of 99 recording lines, height direction magnification of 20,000 times, and cutoff of 80 μm at a measurement length of 1 mm in the X direction, a feed speed of 100 μm / sec, a feed pitch of 2 μm in the Y direction, and the measurement was performed according to JISB 0601 (1994). The calculation was performed according to the definition of the arithmetic average roughness described.
Arithmetic average roughness (SRa) was evaluated three times by each trial, and the average value was evaluated.

8) The content of the raw material resin and a mixed resin sample in the block copolymer of an alkenyl aromatic compound unit is dissolved in CDCl _3, it was measured IH-NMR.

9) Content of Block A in Block Copolymer The spectrum of homopolystyrene was compared with the infrared spectra of each raw material resin and mixed resin sample, and the content of block A was calculated.

10) Weight average molecular weight Each raw material resin and mixed resin sample were dissolved in tetrahydrofuran (sample concentration: 0.05% by weight). The solution was filtered through a 0.20 μm membrane filter, and the obtained sample solution was subjected to GPC analysis under the following conditions. The molecular weight was calculated in terms of standard polystyrene.
GPC equipment conditions Equipment: High performance liquid chromatograph HLC-8220 (TOSOH)
Column: TSKgel SuperHZM-H + SuperHZM-H + Super
HZ2000 (TOSOH)
Solvent: THF (tetrahydrofuran)
Flow rate: 0.35 mL / min
Injection volume: 10 μL
Temperature: 40 ° C
Detector: RI
Data processing: GPC data processing system (TOSOH)

11) Hydrogenation rate of double bond derived from conjugated diene monomer unit in polymer block B Hydrogenation rate of double bond derived from conjugated diene monomer unit in polymer block B The content of the carbon-carbon double bond derived from the monomer unit of the conjugated diene compound in the block B was measured by an iodine value measurement, an infrared spectrophotometer, a ¹ H-NMR spectrum and the like before and after hydrogenation. , From the measured values.

12) Measurement method of viscoelasticity A single film having a thickness of 100 μm consisting solely of an adhesive resin composition containing a styrene-based elastomer as a main component of the laminated film was discharged at a discharge rate of 2 kg / hour using a 25 mmφ single screw extruder. , Using a single-layer T die and cooling with a cooling roll. The viscoelasticity of the obtained film was measured under the following conditions.
Viscoelasticity measurement conditions Apparatus: Viscoelasticity measuring apparatus RSA-G2 (TA Instruments)
Sample size: thickness 100μm × length 30mm × width 5mm
Distance between measurements: 10mm
Measurement frequency: 1 Hz
Measurement temperature range: -130 to 130 ° C
Heating rate: 5 ° C / min

The raw material resins used in the following Examples and Comparative Examples are shown below.
(1) S1605: trade name “S1605”, hydrogenated styrene-butadiene copolymer, manufactured by Asahi Kasei Corporation, MFR = 3.5 g / 10 min, double bond derived from conjugated diene unit of polymer block B Hydrogenation rate = 100 mol%, weight average molecular weight = 180700, density = 1.00 g / cc, content of aromatic alkenyl compound unit = 66% by weight, content of polymer block A = 31% by weight, structural formula A mixture of ABA and Structural Formula AB.

(2) S1606: trade name “S1606”, hydrogenated styrene-butadiene copolymer, manufactured by Asahi Kasei Corporation, MFR = 4.0 g / 10 minutes, double bond derived from conjugated diene unit of polymer block B Hydrogenation rate = 100 mol%, weight average molecular weight = 169900, density = 0.96 g / cc, content of aromatic alkenyl compound unit = 50% by weight, content of polymer block A = 25% by weight, structural formula ABA.

(3) H1221: trade name “H1221”, hydrogenated product of styrene-butadiene block copolymer, manufactured by Asahi Kasei Corporation, MFR = 4.5 g / 10 min, hydrogenation rate of double bond derived from conjugated diene unit = 100 mol%, weight average molecular weight = 147600, density = 0.89 g / cc, content of aromatic alkenyl compound unit = 12% by weight, content of polymer block A = 12% by weight, no polymer block B.

(4) UH115: trade name “UH115”, hydrogenated terpene phenol resin, manufactured by Yashara Chemical Company, glass transition temperature = 65 ° C.

(5) TH130: trade name “TH130”, terpene phenol resin, manufactured by Yashara Chemical Company, glass transition temperature = 80 ° C.

(6) ENDEX155: trade name "Endex (TM) 155 Hydrocarbon Resin, hydrocarbon polymer, manufactured by Eastman Chemical Company, softening point = 153 ° C

(7) EB-P: trade name "EB-P", ethylene bisstearic acid amide, manufactured by Kao Corporation

(Example 1)
A pressure-sensitive adhesive composition comprising 100 parts by weight of S1606, 6.7 parts by weight of TH130, and 26.7 parts by weight of ENDEX155, and a polyolefin resin (trade name “WF836DG3”, a propylene ethylene random copolymer) Manufactured by Prime Polymer Co., Ltd., MFR = 4.5 / 10 minutes, melting point = 164 ° C., ethylene copolymerization amount = 0.3% by weight), and polyolefin resin (trade name “BC3HF”, polypropylene— (Ethylene block copolymer, manufactured by Prime Polymer Co., Ltd., melting point = 171 ° C., ethylene content = 9% by weight), and the resin of the adhesive layer was discharged at a discharge rate of 4 kg / hour using a 40 mmφ single screw extruder. The resin was discharged at a discharge rate of 32 kg / hour using a 90 mmφ single screw extruder, and the resin of the release layer was discharged at a discharge rate of 4 kg / hour with a 60 mmφ single screw extruder. Using a T-die (lip width 850 mm, lip gap 1 mm), co-extrude each, cool with a cooling roll, the thickness of the adhesive layer, base material layer, and release layer are 4 μm, 32 μm, and 4 μm, respectively. A laminated film having a length of 650 mm was obtained. The results are shown in Table 1.

(Examples 2 to 4, Comparative Examples 1 to 9)
A laminated film was obtained in the same manner as in Example 1 except that the content of the raw material resin and the additive of the adhesive layer, and the thickness and the content of the adhesive layer were changed as shown in Table 1. The results are shown in Table 1.

  The laminated films of Examples 1 to 4 have sufficient adhesive strength when adhered to the back surface of the prism sheet, and the adhesive strength is unlikely to increase even after one week at a high temperature, and the peel strength is also low. It was suppressed and excellent. In addition, the peeling force between the adhesive layer of the film and the surface on the opposite side was large, and the film was not easily stretched or deformed.

  On the other hand, the laminated film of Comparative Example 1 had too strong a temporal adhesion to the prism back surface.

  The laminated film of Comparative Example 2 had a low initial adhesive force to the prism back surface and was easily peeled. In addition, the adhesive strength with time was significantly increased as compared with the initial adhesive strength.

  The laminated film of Comparative Example 3 was too strong in adhesion with time to the prism back surface and was difficult to peel. In addition, the peeling force between the adhesive layer of the film and the surface on the opposite side was large, and the film was partially stretched or deformed.

  The laminated film of Comparative Example 4 was too strong in the initial adhesive strength and the temporal adhesive strength to the prism back surface, and was difficult to peel. In addition, the peeling force between the adhesive layer of the film and the surface on the opposite side was large, and the film was partially stretched or deformed.

  The laminated film of Comparative Example 5 was very large in both the initial adhesive force and the temporal adhesive force with respect to the prism back surface, and was difficult to peel.

  The laminated film of Comparative Example 6 had a very large temporal adhesion to the prism back surface and was difficult to peel.

  The laminated film of Comparative Example 7 had low initial adhesive strength to the prism back surface and was easily peeled.

  The laminated film of Comparative Example 8 had a large initial adhesive force to the prism back surface and was difficult to peel. In addition, the peeling force between the adhesive layer of the film and the surface on the opposite side was large, and the film was easily stretched or deformed partially.

  In the laminated film of Comparative Example 9, a transferred matter was easily generated on the prism back surface.

  The pressure-sensitive adhesive composition of the present invention is industrially useful because the surface laminated film of the present invention is suitably used for surface protection of prism sheets and the like, particularly for the back surface thereof.

Claims (9)

A laminated film having an adhesive layer composed of an adhesive resin composition containing a styrene-based elastomer as a main component on at least one surface of a base material layer, wherein the adhesive resin composition has a tensile storage modulus E at 1 Hz and 10 to 60 ° C. ′, A tensile loss elastic modulus E ″ and a loss tangent tan δ satisfy the following formulas (1) to (3), respectively.
2E + 6 ≦ E ′ (Pa) ≦ 1E + 8 (1)
2E + 5 ≦ E ″ (Pa) ≦ 1E + 7 (2)
0.1 ≦ tan δ ≦ 0.5 (3)   2. The laminated film according to claim 1, wherein the loss tangent tan δ at 1 Hz of the pressure-sensitive adhesive resin composition does not take a maximum value at 10 to 60 ° C., and the ratio of the maximum value to the minimum value is 5 or less. The laminated film according to claim 1, wherein the styrene-based elastomer satisfies the following 1) and 2).
1) A block copolymer containing the following polymer block A and the following polymer block B, and having the structural formula ABA and / or AB.
Polymer block A: a polymer block mainly composed of units derived from an aromatic alkenyl compound monomer unit, and mainly composed of units derived from an aromatic alkenyl compound monomer unit. Polymer block B : Aromatic alkenyl monomer-conjugated diene monomer copolymer block randomly containing units derived from a conjugated diene monomer unit and an aromatic alkenyl compound monomer unit 2) In the polymer block B, The hydrogenation rate of the double bond derived from the conjugated diene monomer unit is 90 mol% or more. The laminated film according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive resin composition contains a phenol copolymer. The laminated film according to any one of claims 1 to 4, wherein the base layer is made of a polypropylene resin.   The laminated film according to any one of claims 1 to 5, wherein the adhesive layer has an average surface roughness Ra of 0.05 to 0.50 µm.   The laminated film according to claim 1, further comprising a release layer having an average surface roughness (Ra) of 0.10 to 1.00 μm on a side of the base layer opposite to the adhesive layer.   The laminated film according to any one of claims 1 to 7, wherein the release layer is made of a resin composition containing polymethylpentene.   The laminated film according to any one of claims 1 to 8, which is used for protecting a back surface of a prism sheet.