JP2022173329A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tacky adhesive composition which has sufficient adhesive strength when adhered to an adherend having fine surface unevenness and hardly increases adhesive strength even when exposed to a high temperature during transportation, storage or the like.

SOLUTION: There is provide a laminated film which has an adhesive layer composed of a tacky adhesive composition comprising an α-methyl styrenic resin and a phenol copolymer, which is mainly composed of a styrene-based elastomer and a release layer satisfying the following 1) and 2) on one surface of a substrate layer mainly composed of a polypropylene-based resin, wherein the laminated film is used for protecting a back surface of a prism sheet in which a tensile storage elastic modulus E', a tensile loss modulus E''and a loss tangent tanδ at a frequency of 1 Hz and a temperature of 10 to 60°C satisfy the following expression (1) to (3), respectively. 2E+6≤E'(Pa)≤1E+8 (1), 2E+5≤E''(Pa)≤1E+7 (2) and 0.1≤tanδ≤0.5 (3). 1) The release layer is composed of a resin composition comprising a polyterpene. 2) The release layer has an average surface roughness (Ra) of 0.40 to 0.85 μm.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a laminated film having an adhesive layer made of an adhesive composition. Specifically, when the laminated film is stored in a roll state and then unwound, the film does not partially stretch or deform, has excellent workability, and has adhesive strength and peelability to the adherend. It relates to a laminated film having an adhesive resin composition having excellent adhesiveness and an adhesive layer comprising the same.

Conventionally, laminated films are used for stacking and storing members such as prism sheets used for optical applications, synthetic resin plates, stainless steel plates, aluminum plates, decorative plywood, steel plates, and glass plates used for building materials. It has been used to protect against scratches during transportation and secondary operations such as bending and pressing. It has also been used to protect household appliances, precision instruments and automobile bodies from scratches during transportation in the manufacturing process.
Such a laminated film should have good adhesiveness and be easily peeled off after use without contaminating the surface of the adherend with the adhesive.

In recent years, the variety of adherends has progressed, and a large number of adherends ranging from those with smooth surfaces to those with uneven surfaces can be seen.
Among them, the back surface of the prism sheet is smoother than the prism surface, which has large surface irregularities, but the back surface has fine surface irregularities. It has functions such as preventing interference by close contact and making appearance defects such as scratches less noticeable.

Therefore, the back surface of the prism sheet needs to have good adhesion to the back surface in order to be protected by the laminated film when stacked and stored or transported.
However, when time elapses after the laminated film is attached to the adherend, there is a problem that the adhesive force increases (so-called increased adhesion), making it difficult to peel off. It is known that this is caused by exposure to high temperatures during transport, storage, etc. of the product to which the laminated film is adhered, and this becomes more conspicuous.

As a laminated film used for adherends having fine surface irregularities, a polymer block consisting mainly of aromatic alkenyl compound units and continuous aromatic alkenyl compound units, which is said to be relatively unlikely to cause adhesion increase, and a conjugated It is known to use a copolymer consisting of an aromatic alkenyl-conjugated diene monomer copolymer block randomly containing diene monomer units and aromatic alkenyl compound units for the adhesive layer (for example, patent See References 1, 2, etc.)
However, although this has a sufficient protective performance for the adherend, it does not satisfy both the easiness of peeling from the adherend and the easiness of unrolling 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 an adhesive layer made of an adhesive composition in a roll state, and then, when the film is unwound, the film is not partially stretched or deformed, and is easy to process. In addition, when attached to an adherend with fine surface irregularities, such as the back surface of a prism sheet, it has sufficient adhesive strength, and even when exposed to high temperatures during transportation and storage. To prevent adhesive residue from forming on an adherend even after peeling off a laminated film, and to maintain its function.

The inventors of the present invention have completed the present invention as a result of intensive studies in order to achieve this object.
That is, the present invention provides a laminated film having, on at least one side of a substrate layer, an adhesive layer made of an adhesive resin composition containing a styrene-based elastomer as a main component, wherein the adhesive resin composition at 1 Hz, 10 to 60 ° C. The laminated film has a tensile storage modulus E′, a tensile loss modulus E″, and a loss tangent tan δ satisfying the following formulas (1) to (3).
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 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 styrene-based elastomer preferably satisfies the following 1) and 2).
1) A block copolymer comprising a polymer block A below and a polymer block B below and having a structural formula ABA and/or AB.
Polymer block A: polymer block composed mainly of repeating units derived from aromatic alkenyl compound monomer units, and composed mainly of units derived from aromatic alkenyl compound monomer units Polymer block B : Aromatic alkenyl monomer-conjugated diene monomer copolymer block randomly containing units derived from conjugated diene monomer units and aromatic alkenyl compound monomer units 2) in the polymer block B The hydrogenation rate of double bonds 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 adhesive resin composition contains a phenol copolymer.

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

The adhesive layer surface preferably has an average surface roughness Ra of 0.05 to 0.50 μm.

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

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

The laminated film is preferably used to protect the back surface of the prism sheet.

Here, when the tensile storage modulus E′ at 10 to 60° C. satisfies the formula (1), 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 formula (2), and the maximum value and the minimum value of the tensile loss elastic modulus E'' at 10 to 60 ° C. are both the formula (2) is satisfied.
Moreover, the loss tangent tan δ at 10 to 60° C. satisfies the formula (3) means that both the maximum value and the minimum value of the loss tangent tan δ at 10 to 60° C. satisfy the formula (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 unwound after that, the film does not partially stretch or deform, and is excellent in workability. When attached to an adherend with a rough surface, it has sufficient adhesive strength and does not easily increase in adhesive strength even when exposed to high temperatures during transportation and storage, and even after peeling off the laminated film. Adhesive residue does not occur on the adhered body, and its function can be maintained.

The laminated film of the present invention is a laminated film having an adhesive layer made of an adhesive resin composition containing a styrene elastomer as a main component on at least one side of a substrate layer, and A tensile storage modulus E′, a tensile loss modulus E″, and a loss tangent tan δ at °C 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)

Here, when the tensile storage modulus E′ at 10 to 60° C. satisfies the formula (1), 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 formula (2), and the maximum value and the minimum value of the tensile loss elastic modulus E'' at 10 to 60 ° C. are both the formula (2) is satisfied.
Moreover, the loss tangent tan δ at 10 to 60° C. satisfies the formula (3) means that both the maximum value and the minimum value of the loss tangent tan δ at 10 to 60° C. satisfy the formula (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 for the pressure-sensitive adhesive layer of the present invention has a pressure range in which the laminated film using it easily adheres to the back surface of the optical prism sheet and does not float on the surface of the adherend. To achieve this, it is important that the tensile storage modulus E″ at 1 Hz and in the temperature range of 10 to 60° C. satisfies the formula (1).

2E+6≦E′(Pa)≦1E+8 (1)

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

If E' is less than 2E+6 Pa, the adhesive strength to the adherend increases over time, and peeling may become difficult in some cases. On the other hand, when E′ exceeds 10E+7 Pa, the laminate film may float on the surface of the adherend without exhibiting adhesive strength to the adherend.
E′ is more preferably 2E+6 to 7E+7 Pa, more preferably 3E+5 to 5E+7 Pa, and particularly preferably 4E+5 to 3E+7 Pa.

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

If the tensile storage loss modulus E″ is less than 2E+5 Pa, the adhesive layer becomes too soft, and the adhesive strength with the adherend increases over time, and peeling may become difficult in some cases. On the other hand, when E″ exceeds 10E+6 Pa, the laminate film may be in a floating state on the surface of the adherend without exhibiting adhesive strength 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 formula (3) in order to obtain stable peelability.
0.1≦tan δ≦0.5 (3)

If the loss tangent tan δ is less than 0.1, the adhesion to the adherend increases with time, and peeling may become difficult in some cases. On the other hand, when tan δ exceeds 0.5, peeling becomes easier. Loss tangent tan δ is more preferably 0.11 to 0.5, more preferably 0.1
It is more preferably 1 to 0.4, and particularly preferably 0.11 to 0.36. .

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., because the temperature dependence of the pressure-sensitive adhesive strength is small, and therefore it is preferable for use at high temperatures.

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

In the present invention, the method for controlling the tensile storage modulus E′, the tensile loss modulus E″ and the loss tangent tan δ of the pressure-sensitive adhesive resin composition within the above ranges is to use a styrene-based elastomer described below in the pressure-sensitive adhesive resin composition. , α-methylstyrene, and terpene-based resins are preferably used, but are not limited to these.

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

The block copolymer of the present invention is a block copolymer containing polymer block A and polymer block B described above and having a structural formula ABA and/or AB.
The block copolymer of the present invention is an aromatic alkenyl compound monomer-conjugated diene monomer copolymer block randomly containing units derived from conjugated diene monomer units and aromatic alkenyl compound monomer units. By having a certain polymer block B, when the laminated film is attached to an adherend having finer surface irregularities than other block copolymers, and is exposed to a high temperature during transportation and storage. However, it is difficult for adhesion to increase. Among them, it is preferable to use only the structural formula ABA having polymer blocks A at both ends, because the increase in adhesion at high temperatures is further suppressed.

The content of units derived from aromatic alkenyl compound monomer units in the block copolymer is preferably 30% by weight or more.
When the content of units derived from the aromatic alkenyl compound monomer units is 30% by weight or more, the tensile storage modulus E' tends to be increased. More preferably 40% by weight or more, more preferably 45% by weight or more The content of units derived from aromatic alkenyl compound monomer units is preferably 60% by weight or less, and when it is 60% by weight or less, tensile loss The elastic modulus E'' is unlikely to become too large. 55% by weight or less is more preferable.
The unit content (St(A+B)) derived from the aromatic alkenyl compound monomer in the block copolymer represents a numerical value defined by the following formula.
The content of units derived from such aromatic alkenyl compound monomer units is determined by 1H-NMR. In addition, the content of units derived from such aromatic alkenyl compound monomer units can also be determined by an infrared spectroscopy method, and a value substantially equivalent to 1H-NMR is obtained.

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

The block copolymer preferably has a weight average molecular weight of 100,000 to 200,000.
When the weight-average molecular weight is 200,000 or less, the tensile loss elastic modulus E″ can be easily increased, and adhesive strength to adherends having surface irregularities can be easily obtained. In addition, industrial processing into pellets and film production by melt co-extrusion may also be facilitated. More preferably, the weight average molecular weight of the block copolymer is 180,000 or less.
When the weight-average molecular weight is 100,000 or more, the tensile storage modulus E 1 ′ can be easily increased, and adhesion enhancement on adherends having surface irregularities is less likely to occur. In addition, in the process of desolvating and drying the polymer, the polymer is less likely to adhere to production equipment and the like, which may facilitate industrial production. The weight-average molecular weight of the block copolymer is more preferably 130,000 or more, more preferably 150,000 or more.

The block copolymer preferably has a melt flow rate (MFR) value 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 does it facilitate industrial production of the block copolymer, but it also provides excellent processability during film formation. be able to. When the melt flow rate value is less than 0.1 g/min, the solubility in the solvent during polymerization is deteriorated, the heat meltability is lowered, and it may be difficult to remove the polymer from the production equipment. This difficulty becomes a problem that may reoccur during film formation. More preferably, the melt flow rate value is 2 g/min or more, and even more preferably 3 g/min or more.
On the other hand, if the melt flow rate value is more than 20 g/min, the polymer adheres and remains inside the manufacturing equipment in the step of desolvating and drying the polymer, making it difficult to remove the polymer. This difficulty becomes a problem that may reoccur during film formation. More preferably, the melt flow rate value is 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 composed mainly of repeating units derived from aromatic alkenyl compound monomer units, and is a polymer block mainly composed of units derived from aromatic alkenyl compound monomer units. However, the content of units derived from aromatic alkenyl compound monomer units in the polymer block A is preferably 80% by weight or more.
By making the unit derived from the aromatic alkenyl compound monomer unit in the polymer block A 80% by weight or more, the thermoplasticity of the adhesive resin composition can be easily suppressed, and the tensile storage elastic modulus E' can be increased. I have the advantage to say It is more preferable that the unit derived from the aromatic alkenyl compound monomer unit in the polymer block A is 90% by weight or more.

In addition, repeating units other than units derived from aromatic alkenyl compound monomer units may be contained in an amount of less than 20% by weight.
Examples of aromatic alkenyl compound monomer units include, but are not limited to, styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, Aromatic alkenyl monomeric units such as vinylnaphthalene, vinylanthracene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene and vinylpyridine may be mentioned.
Among the aromatic vinyl alkenyl monomer units, styrene units are preferred because raw materials are readily available.
The repeating unit other than the unit derived from the aromatic alkenyl compound monomer is a repeating unit derived from a compound copolymerizable with the unit derived from the aromatic alkenyl compound monomer, such as a conjugated diene compound or A repeating unit derived from a (meth)acrylic acid ester compound can be mentioned. Among them, 1,3-butadiene and isoprene are preferred because they are highly copolymerizable with units derived from aromatic alkenyl compound units.

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

(Polymer block B)
Polymer block B in the present invention is an aromatic alkenyl monomer-conjugated diene monomer copolymer containing randomly units derived from conjugated diene monomer units and units derived from aromatic alkenyl compound monomer units. It is a polymer block. By randomly containing units derived from conjugated diene units and units derived from aromatic alkenyl compound units, the laminated film using the adhesive resin composition of the present invention can be attached to an adherend having fine surface irregularities. Even when exposed to high temperatures during transportation and storage after application, the tensile storage elastic modulus E' does not decrease, and adhesion is less likely to increase.
Here, the term "randomly" is interpreted in a broad sense, and the chain distribution of the conjugated diene units and the aromatic alkenyl compound units is a certain statistical rule obtained by simultaneously polymerizing the mixed conjugated diene and aromatic alkenyl compound. means to be in compliance with
Examples of aromatic alkenyl compound monomer units include, but are not limited to, styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, Aromatic vinyl monomeric units such as vinylnaphthalene, vinylanthracene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene and vinylpyridine may be mentioned.
Among the aromatic vinyl monomer units, styrene units are preferred because raw materials are readily available.
The conjugated diene monomer unit in polymer block B in the present invention is not particularly limited, but examples include 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 Mention may be made of diolefins such as -1,3-octadiene, myrcene and chloroprene.
Among diolefins, at least one unit selected from 1,3-butadiene units and isoprene units, which have high polymerization reactivity and easy availability of raw materials, is preferable. Furthermore, it is more preferable to select 1,3-butadiene units in order to obtain high mechanical strength.

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

The content of units derived from aromatic alkenyl compound monomer units in 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 elastic modulus E'' is not too small, the initial adhesive strength is not too strong, and adhesive residue is less likely to occur. Alternatively, the tensile storage modulus E' is not too small, and the initial adhesive strength is less likely to increase. The content of units derived from aromatic alkenyl compound monomer units is more preferably 20% by weight or more, particularly preferably 30% by weight or more.
On the other hand, the content of units derived from aromatic alkenyl compound monomer units is preferably 80% by weight or less. When it is 80% by weight or less, the tensile storage modulus E' is not too large, and initial adhesive strength is easily obtained. The content of units derived from aromatic alkenyl compound monomer units 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, α-methylstyrene resin increases the tensile storage elastic modulus E' of the adhesive resin composition, suppresses the increase in adhesion, and is used on the surface of the base material layer opposite to the surface of the adhesive layer or the release layer It has the effect of improving the releasability between the surface and the adhesive layer surface. Moreover, since the effect of the terpene-based resin, which will be described later, is less likely to be inhibited, it has been found that the tensile loss elastic modulus E″ is not lowered and sufficient initial adhesive strength can be obtained. It is presumed that this is because the α-methylstyrene resin diffuses into the polymer block B portion of the block copolymer and reduces the free deposition.
Such an effect is simply due to the content of units derived from the aromatic alkenyl compound monomer in the block copolymer having the structural formulas ABA and/or AB and the weight of the block copolymer. This effect cannot be obtained simply by increasing the content of coalescing block A or increasing the molecular weight of the block copolymer.

The α-methylstyrene resin used in the present invention includes α-methylstyrene homopolymer and/or α-methylstyrene as a main component, styrene and p-methylstyrene, p-chlorostyrene, chloromethylstyrene, Copolymers of two or more styrenic compounds such as tert-butylstyrene, p-ethylstyrene and divinylbenzene can be mentioned.
The α-methylstyrene resin may be a copolymer with an aliphatic monomer.
A molecular weight Mw of 4000 or more is preferable from the viewpoint of resin strength and bleeding out. A copolymer composed of two or more monomers may be a block copolymer or a random copolymer.
Among them, the α-methylstyrene resin preferably has a softening point of 100° C. or higher, more preferably 150° C. or higher. Specifically, Eastman Chemical Company, trade name "ENDEX155" (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), "ENDEX 160" (softening point 160°C), and the like.

(Terpene resin)
As a result of intensive studies, terpene-based resins or hydrogenated products thereof increase the tensile loss elastic modulus E'' of the adhesive resin composition, exhibit sufficient adhesive strength to the adherend, and adhere the laminated film. It tends to stick to the body surface. In addition, since the effects of the α-methylstyrene resin described above are less likely to be inhibited, the tensile storage modulus E' is not lowered, the adhesion to the adherend is less likely to increase over time, and peeling is easier. It is presumed that this is because the terpene-based resin diffuses into the polymer block B portion of the block copolymer, and has both the effect of plasticizing while increasing the Tg and the effect of adhesive strength due to electrical action. .

In the present invention, terpene-based resins or hydrogenated products thereof are mentioned.
Terpene-based resins are obtained by cationic polymerization of terpene-based compounds (eg, α-pinene, β-pinene, limonene, etc.) collected from pine trees and orange peels as raw materials. Terpene-based resins are roughly classified into polyterpene resins that are polymers of terpene monomers, aromatic modified terpene resins obtained by copolymerizing terpene monomers and aromatic monomers, terpene phenolic resins that are obtained by reacting terpene monomers and phenols, and further is classified as a hydrogenated terpene resin obtained by hydrogenating these.
If the resin is a hydrogenated terpene resin, it is possible to reduce concerns about discoloration due to high temperature or aging.
The above terpene-based resins may be used alone or in combination of two or more. The glass transition temperature or softening point of the terpene resin is preferably 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 preferred, and hydrogenated terpene phenol resins are particularly preferred. The phenol group of the terpene phenol resin has an electrical affinity with the adherend, so even if the product to which the laminated film is attached is exposed to high temperatures during transportation and storage, the adhesive strength does not easily increase, and the product is stable. High adhesion is expected.
The terpene phenol resin has a high softening point of about 130°C.
Also in the case of terpene phenol resins, hydrogenation can reduce concerns about discoloration due to high temperature or aging.

(Adhesive resin composition)
It is particularly preferable 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 it is contained in the adhesive resin composition in an amount of 50% by weight or more.
At this time, it is preferable that 100 parts by weight of the styrene elastomer contains 1 to 50 parts by weight of α-methylstyrene resin, more preferably 5 to 45 parts by weight, even more preferably 10 to 40 parts by weight, and 15 to 40 parts by weight. Parts by weight are particularly preferred. It is preferable to use 10 parts by weight or more of the α-methylstyrene resin with respect to 100 parts by weight of the block copolymer.
At this time, it is preferable to contain 1 to 50 parts by weight of the terpene resin with respect to 100 parts by weight of the styrene elastomer, more preferably 3 to 50 parts by weight or more, and still more preferably 5 to 50 parts by weight. be. It is preferable to contain 15 parts by weight or less of the terpene-based resin with respect to 100 parts by weight of the block copolymer.
The content of the terpene resin is more preferably 40 parts by weight or less, still more preferably 30 parts by weight or less, and particularly preferably 25 parts by weight or less.

The adhesive resin composition of the present invention contains, in addition to the block copolymer, α-methylstyrene resin, and terpene resin described above, an organic lubricant, an antioxidant, a light stabilizer, and an ultraviolet absorber, if necessary. agents, fillers, pigments, styrenic block phase reinforcing agents, softening agents, anti-adhesion agents, olefin resins, silicone resins, liquid acrylic copolymers, phosphoric acid ester compounds, etc. You can Each is described below.

(organic lubricant)
The organic lubricant used in the present invention is preferably saturated fatty acid bisamide or fatty acid metal salt, considering excessive exudation at room temperature or high temperature. Specific examples include ethylenebisstearic acid bisamide and stearic acid metal salts. These may be used alone or in combination of two or more.

In the adhesive resin composition of the present invention. It is preferable to contain 0.1 to 1.5 parts by weight of the organic lubricant with respect to 100 parts by weight of the block copolymer. An organic lubricant can be expected to have the effect of suppressing the 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 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 high temperature or over time, and there is no fear of staining the adherend, but it is more preferably 1 part by weight or less. 0.5 parts by weight or less is particularly preferred.
stomach.
The organic lubricant used in the present invention preferably has a high melting point in view of bleeding out at high temperatures and over time, and specific examples thereof include ethylenebisstearic acid amide and calcium stearate.

(Antioxidant)
Antioxidants used in the present invention are not particularly limited, and include, for example, commonly used phenolic (monophenolic, bisphenolic, polymeric phenolic), sulfur, and phosphorus antioxidants.

(light stabilizer)
The light stabilizer used in the present invention includes hindered amine compounds.

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

(Softener)
The softening agent refers to a low melting point conjugated polymer having a melting point of 50° C. or less, a low melting point petroleum oil or a natural oil. Polybutadiene, paraffinic process oil, naphthenic process oil, aromatic process oil, castor oil, tall oil, natural oil, liquid polyisobutylene resin, polybutene, or hydrogenated products thereof can be used. These softeners may be used alone or in combination of two or more.

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

(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 substrate layer. Furthermore, a release layer may be provided on the substrate layer on the side opposite to the adhesive layer.
A detailed description will be given below.

(adhesive layer)
The adhesive layer in the present invention is made of the adhesive resin composition described above, 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 resin. The polyolefin resin contained in the substrate is not particularly limited, but ethylene homopolymer, ethylene-α-olefin copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer. Polymers and polyethylene-based resins such as ethylene-vinyl acetate copolymers; polypropylene-based resins such as propylene homopolymers, propylene-α-olefin copolymers, and propylene-ethylene copolymers; butene homopolymers; butadiene and homopolymers or copolymers of conjugated dienes such as isoprene. Further, examples of the polyethylene-based resin include high-density polyethylene, medium-density polyethylene, and low-density polyethylene. The form of copolymerization may be random, block, or terpolymer form. The above polyolefin-based resins may be used alone, or two or more of them may be used in combination.

The polyethylene-based resin is obtained using ethylene as a main component. The proportion of structural units 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 in 100% by weight of all structural units of the polyethylene-based resin.

The polypropylene-based 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 still more preferably 90% by weight or more in 100% by weight of all structural units of the polypropylene resin.
The substrate layer of the present invention is preferably composed mainly of a polypropylene-based resin in terms of heat resistance, weather resistance, or adhesion to the adhesive layer.

The thickness of the substrate layer in the present invention is preferably 10 μm or more, more preferably 100 μm or less. When the thickness of the substrate is 10 μm or more and 100 μm or less, the laminated film can be handled even more easily.

When the laminated film according to the present invention consists only of a substrate layer and an adhesive layer composed of the adhesive resin composition, the surface is provided with unevenness in order to suppress the peeling force between the surface of the substrate layer and the surface of the adhesive layer. It is preferable to reduce the contact area with the adhesive layer.
In this case, considering the resin composition of the adhesive layer of the present invention, the average surface roughness SRa of the surface of the release layer is preferably 0.40 μm or more. It is more preferable that the average surface roughness of the surface is 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 adhesive layer surface and the opposite surface of the adhesive layer of the base material layer to 0.40 μm or more, the adherend protection performance and peeling force can be improved. When the surface roughness of the release layer is less than 0.40 μm, the unreeling property of the film is deteriorated when the film is rolled. If the surface roughness of the base material layer is higher than 0.85 μm, the surface unevenness of the base material layer may be transferred to the surface of the adhesive layer, resulting in a significant decrease in adhesive strength.

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 of 0.40 μm or more, the resin used for the substrate layer is incompatible with homopolypropylene or random polypropylene. A propylene-ethylene block copolymer can be suitably used. When a propylene-ethylene block copolymer is used, the uneven state is less likely to change due to changes in production equipment and melt-kneading conditions during 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 an incompatible resin into the propylene-ethylene block copolymer, the average surface roughness SRa can be increased.
The average surface roughness SRa can also be increased by lowering the tensile speed applied to the resin or lengthening the residence time in the extrusion step, which will be described later.
On the other hand, in order to reduce the average surface roughness SRa, it is effective to mix a propylene-ethylene block copolymer with a homopolypropylene resin.

As the resin incompatible with the propylene-ethylene block copolymer, α-olefin (co)polymers having 4 or more carbon atoms such as 4-methylpentene-1 (co)polymers can be suitably used. In addition, low-density polyethylene, high-density polyethylene, copolymer of ethylene and a small amount of α-olefin, copolymer of ethylene and vinyl acetate, polystyrene, alicyclic olefin resin, polyester resin, polyamide resin, etc. is mentioned. In particular, a 4-methylpentene-1 (co)polymer is preferable because it not only roughens the surface in a matt state, but also lowers the surface free energy of the film surface, thereby further reducing the peeling force.

The content of the α-olefin (co)polymer having 4 or more carbon atoms in the resin composition constituting the substrate layer is in the range of 0% by weight or more and 35% by weight or less. When the content of the α-olefin (co)polymer having 4 or more carbon atoms exceeds 35% by weight, the substrate layer and adhesive layer materials are co-extruded using a T-die or the like to laminate the substrate. The film formability of the layer deteriorates.

(release layer)
The release layer in the present invention can be provided on the substrate layer on the side opposite to the adhesive layer. As a result, by distributing the functions to the substrate layer and the release layer respectively, it is possible to respond to a wider range of applications.

In this case, it is preferable to reduce the contact area with the adhesive layer by imparting unevenness to the surface in order to suppress the peeling force between the surface of the release layer and the surface of the adhesive layer.
Considering the resin composition of the adhesive layer of the present invention, the average surface roughness SRa of the surface of the release layer is preferably 0.40 μm or more. It is more preferable that the average surface roughness of the surface is 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, it is possible to improve the protection performance of the adherend and the release force. When the surface roughness of the release layer is less than 0.40 μm, the film unreeling property is deteriorated when the film is rolled. If the surface roughness of the release layer is higher than 0.850 μm, the unevenness of the surface of the release layer may be transferred to the surface of the adhesive layer, resulting in a significant decrease in adhesive strength.

In order to set the average surface roughness SRa of the surface of the release layer to 0.40 μm or more, a resin incompatible with homopropylene or random polypropylene is added as the resin used for the release layer, or propylene-ethylene A block copolymer can be preferably used. When a propylene-ethylene block copolymer is used, the uneven state is less likely to change due to changes in production equipment and melt-kneading conditions during 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 an incompatible resin into the propylene-ethylene block copolymer, the average surface roughness SRa can be increased.
The average surface roughness SRa can also be increased by lowering the tensile speed applied to the resin or lengthening the residence time in the extrusion step, which will be described later.
On the other hand, in order to reduce the average surface roughness SRa, it is effective to mix a propylene-ethylene block copolymer with a homopolypropylene resin.

As the resin incompatible with the propylene-ethylene block copolymer, α-olefin (co)polymers having 4 or more carbon atoms such as 4-methylpentene-1 (co)polymers can be suitably used. Other examples include low-density polyethylene, high-density polyethylene, copolymers of ethylene and a small amount of α-olefin, copolymers of ethylene and vinyl acetate, polystyrene, polyester resins, polyamide resins, and the like. In particular, a 4-methylpentene-1 (co)polymer is preferable because it not only roughens the surface in a matt state, but also lowers the surface free energy of the film surface, thereby further reducing the peeling force.

The content 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 or more and 35% by weight or less. When the content of the α-olefin (co)polymer having 4 or more carbon atoms exceeds 35% by weight, the film formability of the base layer deteriorates when the base layer and the adhesive layer are laminated by co-extrusion.
The thickness of the release layer is not particularly limited. The thickness of the release layer is preferably 2 μm or more and preferably 10 μm or less. When the release layer has a thickness of 2 μm or more and 10 μm or less, the laminated film can be handled even more easily.

(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 off or float during handling or transportation, and when it is less than 20 cN/25 mm, excessive force is not required when peeling it off. 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 follows.
23±2° C. and a relative humidity of 50±5% RH 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 opposite side of the adhesive layer surface of the laminated film, and the laminate film was adhered at a speed of 2 m/min.
The resulting specimens were subjected to a temperature of 23±2° C. and a relative humidity of 50±5% RH. H. After being left in a room for 30 minutes, the 180-degree peel strength (unit: cN) at a width of 25 mm was measured at a peel rate of 300 mm/min according to JIS Z0237, and taken as the initial adhesive strength.

It is preferable that the laminated film of the present invention has an adhesion enhancement rate of 400% or less. When the adhesion rate is 400% or less, the peeling work can be performed under more constant conditions, and the work efficiency is improved. More preferably, it is 300% or less, still more preferably 200% or less.
The adhesion rate was calculated by the following formula using the initial adhesive strength and the time-dependent adhesive strength.
Adhesion rate = (adhesive strength over time/initial adhesive strength) x 100 (%)

The laminated film of the present invention preferably has a time-dependent adhesive strength of 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 off or float during handling and transportation, and when it is 40 cN/25 mm or less, excessive force is not required when peeling it off. 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 strength over time was measured as follows.
A test piece was prepared under the same conditions as those for the prism sheet used to measure the initial adhesive strength. After being left for one week in an atmosphere of 65°C ± 2°C and a load of 6 kg/400 cm 2 , the 180° peel strength at a width of 25 mm was measured at a peel rate of 300 mm/min according to JIS Z0237, and this was taken as the adhesive strength over time.

The release force between the surface of the adhesive layer of the present invention and the surface of the base layer or the surface of the release layer on the opposite side of the adhesive layer is in the range of 10 cN/25 mm or less at 23 ° C. When the laminated film is in the form of a roll. is preferred from the viewpoint of film feedability. If the peel force exceeds 10 cN/25 mm, problems such as partial elongation or deformation of the film may occur when the laminated film is rolled out. The peel force at 23° C. is more preferably 5 cN/25 mm or less, particularly preferably 3 cN/25 mm or less.
In addition, the lower limit of the peeling force to the surface of the adhesive layer of the laminated film and the surface of the base layer on the opposite side of the adhesive layer or the surface of the release layer is about 1 cN/25 mm as a practical value, and further about 2 cN/25 mm. is preferred.

(Method for forming laminated film)
The method for producing the laminated film of the present invention includes, for example, putting the adhesive composition and the polyolefin resin for the base layer into separate extruders and, if necessary, the polyolefin resin for the release layer, melting, A method of co-extrusion from a T-die and laminating, or a method of laminating another layer on the layer obtained by inflation molding by a lamination method such as extrusion lamination or extrusion coating, each layer being independently formed into a film. After that, there is a method of laminating each obtained film by dry lamination, but from the viewpoint of productivity, each material of the release layer, the base layer, and the pressure-sensitive adhesive layer is used in a multilayer extruder Co-extrusion molding is preferable, and T-die molding is more preferable from the viewpoint of thickness accuracy.

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

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
The measurement method is shown below.

(1) Initial Adhesion The obtained surface laminated film was cut into a size of 150 mm length (winding direction during film production) x 25 mm width (perpendicular to the winding direction during film production) and used as a test piece. The pressure-sensitive adhesive layer surface was attached to the back surface of a 150 mm×35 mm prism sheet (acrylate polymer, SRa=0.24 μm) to prepare a test piece. Application was performed at 23±2° C. and 50±5% R.H. 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 pressure-sensitive adhesive layer surface) under the environment of , and the film was adhered at a speed of 2 m/min. The following laminator was used for lamination.
Laminator manufacturer: Tester Sangyo Co., Ltd.
Model: SA-1010-S
Roll: Heat-resistant silicone rubber roll Roll diameter: Φ200
The resulting specimens were stored at 23±2° C. and 50±5% R.H. relative humidity. H. After being left in a room for 30 minutes, the 180-degree peel strength (unit: cN) at a width of 25 mm was measured at a peel rate of 300 mm/min according to JIS Z0237, and taken as the initial adhesive strength.

(2) Adhesive strength over time The obtained laminated film was attached under the same conditions as the prism sheet used for the initial adhesive strength evaluation in (1), and placed at 65°C ± 2°C under an atmosphere of 6 kg/400 cm for 1 week. After standing, 23±2° C. and 50±5% R.H. H. and the 180-degree peel strength at a width of 25 mm was measured at a peel rate of 300 mm/min according to JIS Z0237, and was taken as the adhesive strength over time.

(3) Rate of Adhesion Rise Using the initial adhesive strength and the time-dependent adhesive strength obtained in (1) and (2) above, the rate of change from the initial adhesive strength to the time-dependent adhesive strength (adhesion rate) was calculated by the following formula. .
Rate of change (adhesion rate) = (adhesive strength over time/initial adhesive strength) x 100

(4) Peeling force Two sheets of the obtained laminated film were stacked and cut out to a size of 110 mm (winding direction during film production) x 40 mm (perpendicular to the winding direction during film production) to obtain a test piece. , the top and bottom of which were sandwiched between copy papers, a weight of 60 kg was placed thereon, and the sample was allowed to stand in a room at a temperature of 40° C. for 72 hours. After that, it was cooled to 23±2° C. and 50±5% R.H. H. 1 hour in a room, and using Shimadzu Corporation "Autograph (registered trademark)" (AGS-J), the resistance value when peeled 180 degrees at a speed of 300 mm / min was measured as peel force [cN /25 mm].
When measuring, prepare a polyester sheet with a thickness of 190 μm and a size of 40 mm × 170 mm as a gripping margin for the measurement sample, and attach it to the end of the 110 mm × 40 mm test piece with a cellophane tape with a width of 15 mm. It was used as a holding fee. The measurement was performed three times for one sample, and the average value was taken as the peel strength of that sample.

5) Elongation and deformation of the laminated film when unwinding the laminated film After obtaining a film roll with a width of 550 mm and a roll of 500 m 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. For this storage roll, immediately after 300m rewinding onto another plastic core (9 cm diameter), the film end was manually grasped and pulled to rewind 3m. A visual check was made to see if there was any partial stretching or deformation of the film upon unwinding. A sample with no partial elongation or deformation was rated as ◯ (good), and a sample with partial elongation or deformation was rated as x (bad).

6) Adhesive residue and transferred material after peeling from the adherend The obtained laminated film was attached under the same conditions as the prism sheet used for the initial adhesive strength evaluation in (1), and was loaded at 65 ° C ± 2 ° C. After left for one week in an atmosphere of 6 kg/400 cm 2 , it was placed at 23±2° C. and a relative humidity of 50±5%R. H. was allowed to stand in the room 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. A case where there was no adhesive residue or transferred matter was rated as ◯ (good), and a case where there was even a little adhesive residue or transferred matter was rated as x (bad).

7) Surface roughness Evaluation of the surface roughness on the side opposite to the adhesive layer of the obtained laminated film is performed using a three-dimensional roughness meter (manufactured by Kosaka Laboratory Co., Ltd., model number ET-30HK), with a stylus pressure of 20 mg. , X-direction measurement length 1 mm, feed speed 100 μm/sec, Y-direction feed pitch 2 μm, number of recorded lines 99, height direction magnification 20000 times, cut-off 80 μm Measurement was performed, and conformed to JISB 0601 (1994). It was calculated according to the definition of arithmetic mean roughness described.
Arithmetic mean roughness (SRa) was evaluated by the average value of three trials.

8) Content of Aromatic Alkenyl Compound Unit in Block Copolymer Each raw material resin and mixed resin sample was dissolved in CDCl3, and 1H-NMR was measured.

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

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

11) Hydrogenation rate of double bonds derived from conjugated diene monomer units in polymer block B The hydrogenation rate of double bonds derived from conjugated diene monomer units in polymer block B is The content of carbon-carbon double bonds derived from the conjugated diene compound monomer units in block B is measured before and after hydrogenation by iodine value measurement, infrared spectrophotometer, 1H-NMR spectrum, etc. It can be obtained from the measured value.

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

Raw material resins used in the following examples and comparative examples are shown below.
(1) S1605: Product 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 units = 66% by weight, content of polymer block A = 31% by weight, structural formula Mixtures of ABA and Structural Formula AB.

(2) S1606: Product name “S1606”, hydrogenated styrene-butadiene copolymer, manufactured by Asahi Kasei Corporation, MFR = 4.0 g/10 min, 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 units = 50% by weight, content of polymer block A = 25% by weight, structural formula ABA.

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

(4) UH115: trade name "UH115", hydrogenated terpene phenolic resin, manufactured by Yasuhara Chemical Co., glass transition temperature = 65°C

(5) TH130: Product name "TH130", terpene phenol resin, manufactured by Yasuhara Chemical Co., Ltd., glass transition temperature = 80°C

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

(7) EB-P: trade name “EB-P”, ethylenebisstearic 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", propylene ethylene random copolymer) as a raw material for the base layer , Prime Polymer Co., Ltd., MFR = 4.5/10 minutes, melting point = 164°C, ethylene copolymerization amount = 0.3% by weight) and a 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 adhesive layer resin is extruded at a rate of 4 kg / hour by a 40 mm diameter single screw extruder. The resin is discharged by a 90mmφ single screw extruder at a discharge rate of 32Kg/hour, and the release layer resin is discharged by a 60mmφ single screw extruder at a discharge rate of 4Kg/hour. ) were coextruded and cooled with a cooling roll to obtain a laminated film having an adhesive layer, a base layer, and a release layer with thicknesses of 4 μm, 32 μm, and 4 μm, respectively, and a length of 650 mm in the width direction. rice field. Table 1 shows the above results.

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

The laminated films of Examples 1 to 4 have sufficient adhesive strength when attached to the back surface of the prism sheet, and the adhesive strength does not easily increase even after one week at high temperature, and the peel strength is also good. It was an excellent control. In addition, the adhesive layer of the film and the surface on the opposite side have a large peeling force, and the film is difficult to stretch or deform.

On the other hand, the laminate film of Comparative Example 1 exhibited too strong adhesion over time to the prism back surface.

The laminated film of Comparative Example 2 had a weak initial adhesion to the prism back surface and was easily peeled off. In addition, the adhesive strength over time increased significantly compared to the initial adhesive strength.

The laminate film of Comparative Example 3 had too strong an adhesive force over time to the prism back surface and was difficult to peel off. In addition, the peeling force between the adhesive layer of the film and the surface on the opposite side is large, and the film is partially stretched or deformed.

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

The laminated film of Comparative Example 5 had a very high initial adhesive strength to the prism back surface and a very high adhesive strength over time, and was difficult to peel off.

The laminate film of Comparative Example 6 had a very high adhesive strength over time to the prism back surface and was difficult to peel off.

The laminate film of Comparative Example 7 had a weak initial adhesive force to the prism back surface and was easily peeled off.

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

In the laminated film of Comparative Example 9, a transferred material was likely to appear on the prism back surface.

The pressure-sensitive adhesive composition of the present invention is industrially useful as 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 (3)

An adhesive layer made of an adhesive resin composition containing a styrene-based elastomer as a main component, an α-methylstyrene-based resin, and a phenol copolymer on one side of a base material layer mainly composed of a polypropylene-based resin, and the following 1), 2) is a laminated film having a release layer that satisfies the requirements, wherein the adhesive resin composition has a tensile storage modulus E′ at 10 to 60° C., a tensile loss elastic modulus E″, and a loss tangent tan δ, respectively. A laminated film used for protecting the back surface of a prism sheet, which satisfies the following formulas (1) to (3).
2E+6≦E′(Pa)≦1E+8 (1)
2E+5≦E″(Pa)≦1E+7 (2)
0.1≦tan δ≦0.5 (3)
1) The release layer is made of a resin composition containing polymethylpentene 2) The average surface roughness (Ra) of the release layer is 0.40 to 0.85 μm The laminate film according to claim 1 or 2, wherein the loss tangent tan δ at 1 Hz of the 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. . 3. The laminated film according to claim 1, wherein the styrene-based elastomer satisfies the following 1) and 2).
1) A block copolymer comprising a polymer block A below and a polymer block B below and having a structural formula ABA and/or AB.
Polymer block A: polymer block composed mainly of repeating units derived from aromatic alkenyl compound monomer units, and composed mainly of units derived from aromatic alkenyl compound monomer units Polymer block B : Aromatic alkenyl monomer-conjugated diene monomer copolymer block randomly containing units derived from conjugated diene monomer units and aromatic alkenyl compound monomer units 2) in the polymer block B The hydrogenation rate of double bonds derived from the conjugated diene monomer unit is 90 mol % or more.