JP2022133959A - Multilayer film, self-adhesive film, and self-adhesive film for semiconductor production process - Google Patents

Abstract

To provide a film that is excellent in film-forming properties at the time when a resin is formed into a film shape, and is also excellent in the restorability of an obtained film.SOLUTION: A multilayer film having at least two layers includes a layer that contains 80-100 mass% of a styrenic elastomer in which a content of a styrene component is 15 mass% or more in 100 mass% of a thermoplastic resin, and a layer that contains 0-40 mass% of a styrenic elastomer in which a content of a styrene component is 15 mass% or more in 100 mass% of a thermoplastic resin, and has a thickness of 3 to 15 μm; and contains 75 mass% or more of a styrenic elastomer in 100 mass% of a thermoplastic resin constituting the multilayer film.

Description

The present invention provides an adhesive film (tape) used in the semiconductor manufacturing process, a sticker, a label and a marking film that are affixed to give design to signboards, automobiles, etc., adhesive films (tape), decorative sheets, etc. and a pressure-sensitive adhesive film obtained by providing a pressure-sensitive adhesive layer on the multilayer film.

Conventionally, adhesive films (tapes), stickers, labels, marking films, decorative sheets, etc., which are pasted to give design to signboards, automobiles, etc., have had colorability, workability, Films made of polyvinyl chloride resin (hereinafter also referred to as "PVC-based films"), which are excellent in scratch resistance, weather resistance, etc., are frequently used as substrates.

The PVC-based film itself has rigidity, but a plasticizer is added for the purpose of imparting flexibility so that it can function as an adhesive film. However, depending on the plasticizer used, there is a problem that the compatibility with the adhesive is poor, the stability is poor when the adhesive film is formed, and the plasticizer bleeds out significantly. In addition, there is a tendency to tighten restrictions on the use of plasticizers themselves.
Therefore, polyolefin-based resin films have been widely used as materials to replace PVC-based films.

Also, in the process of manufacturing semiconductors, adhesive films for semiconductor wafer processing are used when cutting semiconductor wafers, packages, etc., and due to the problems described above, polyolefin resin films are used instead of PVC films. The number of cases where
As a film for such a semiconductor manufacturing process, a film using a polyolefin resin has been developed (for example, Patent Document 1). Further, Patent Document 2 discloses a base film for a semiconductor manufacturing process, which imparts antistatic performance and is excellent in flexibility and heat resistance.

Furthermore, in recent years, semiconductor elements have become smaller and thinner, and there is a tendency to demand greater expandability of films in an expanding process for expanding the intervals between chips on a semiconductor wafer. As the size of chips becomes smaller, chips and devices are more likely to be damaged due to contact between chips, resulting in a decrease in yield and an economic impact. Further, there is also a demand for a film capable of temporarily storing and housing a film having chips stacked thereon by restoring its original shape after being expanded.

In order to solve these problems, Patent Documents 3, 4 and 5 disclose base films for dicing containing a large amount of styrene-based elastomer and amorphous polyolefin.

However, in the inventions described in Patent Documents 1 and 2, polyolefin-based resins and olefin-based elastomers, which are not sufficiently expandable, are the main components, and the resilience is insufficient.
In addition, although the invention described in Patent Document 3 uses many styrene-based elastomers, the document does not select materials in consideration of the film-forming properties and handleability of the film. There is no detailed description of
In the invention described in Patent Document 4, although the intermediate layer is described as being made of a styrene-based elastomer, it is difficult to select a styrene-based elastomer when considering film-forming properties when molding a resin into a film. had room for improvement.
Furthermore, although Patent Document 5 describes a film that uses a styrene-based elastomer and amorphous polyolefin and has excellent restoration properties, it is necessary to apply heat to restore it, and after expansion, it is restored without heating. Such characteristics have not yet been imparted.

JP-A-9-8111 JP 2020-84143 A Japanese Patent No. 4259050 JP 2018-125521 A Japanese Patent No. 6716396

In view of such problems, an object of the present invention is to provide a film which is excellent in film formability when a thermoplastic resin is formed into a film, and which is excellent in resilience after expansion. In addition, since the film of the present invention has excellent restoring properties, it restores to a state close to the original shape after expansion, and it is an adhesive for semiconductor manufacturing processes that can be easily stored and accommodated temporarily even when chips are stacked. It is also an object to provide a film.

The present inventor has completed the present invention as a result of intensive studies on a film that is excellent in film-forming properties when a thermoplastic resin is molded into a film and also excellent in restorability of the resulting film.

［７］
引張弾性率が５０ＭＰａ以上である［１］～［６］のいずれか１項に記載の複層フィルム。
［８］
［１］～［７］のいずれか１項に記載の複層フィルムの少なくとも片方の面に粘着層を設けてなる粘着フィルム。
［９］
半導体製造工程に用いられる［８］に記載の半導体製造工程用粘着フィルム。 That is, the gist of the present invention is as follows.
[1]
A multilayer film having at least two layers,
A layer A containing 80 to 100% by mass of a styrene-based elastomer having a styrene component content of 15% by mass or more in 100% by mass of the thermoplastic resin;
A layer B containing 0 to 40% by mass of a styrene elastomer having a styrene component content of 15% by mass or more in 100% by mass of a thermoplastic resin and having a thickness of 3 to 15 μm,
A multilayer film containing 75% by mass or more of a styrene-based elastomer in 100% by mass of a thermoplastic resin constituting the multilayer film.
[2]
The multilayer film according to [1], wherein the thermoplastic resin other than the styrene elastomer is a polyolefin resin.
[3]
The multi-layer film according to [1] or [2], wherein at least one of the layers on the front and back is a layer made of only a styrene-based elastomer as the thermoplastic resin.
[4]
The multilayer film according to any one of [1] to [3], wherein at least one of the front and back layers is layer B, and the layer has a static friction coefficient of 0.800 or less.
[5]
The multilayer film according to any one of [1] to [3], wherein at least one of the front and back layers is layer B, and both the static friction coefficient and the dynamic friction coefficient of the layer are 0.800 or less.
[6]
6. The multilayer film according to any one of claims 1 to 5, wherein the film has a recovery rate of 90% or more in the following test methods.
<Method for measuring recovery rate>
Test atmosphere: 23°C, 50% RH
Test piece: JISK6732 compliant dumbbell "SDK-600" used Test conditions Test speed: 200mm/min
Distance between chucks: 40mm
Tensile elongation: 50%
Holding time: Hold for 1 minute after 50% elongation

After the retention time has elapsed, the specimen is removed from the tester, and after 5 minutes have elapsed, the recovery rate is calculated using the following formula.

a formula:

[7]
The multilayer film according to any one of [1] to [6], which has a tensile modulus of 50 MPa or more.
[8]
An adhesive film obtained by providing an adhesive layer on at least one surface of the multilayer film according to any one of [1] to [7].
[9]
The pressure-sensitive adhesive film for semiconductor manufacturing processes according to [8], which is used in semiconductor manufacturing processes.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a film that is excellent in film-forming properties when a resin is molded into a film, and that is excellent in restoring properties of the obtained film. Further, according to the present invention, it is possible to provide an adhesive film for a semiconductor manufacturing process that can be restored to a state close to the original shape after being expanded, and that can be easily stored or accommodated temporarily even in a state in which chips are stacked. .

Although the present invention will be described in detail below, the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist thereof. In addition, when the expression "~" is used in this specification, it is used as an expression including numerical values or physical property values before and after it.

One embodiment of the present invention is a multilayer film having at least two layers,
A layer containing 80 to 100% by mass of a styrene elastomer having a styrene component content of 15% by mass or more in 100% by mass of thermoplastic resin (hereinafter also referred to as “layer A”), and 100% by mass of thermoplastic resin. A layer containing 0 to 40% by mass of a styrene elastomer having a styrene component content of 15% by mass or more and having a thickness of 3 to 15 μm (hereinafter also referred to as “layer B”), and a multilayer The multilayer film contains 75% by mass or more of a styrene-based elastomer in 100% by mass of the thermoplastic resin constituting the film.

<Thermoplastic resin>
A thermoplastic resin having excellent moldability is used for the resin composition used for producing the multilayer film used in the present invention. Among them, the thermoplastic resin used for the layer A contains a styrene-based elastomer as an essential component. Further, the thermoplastic resin used for the layer B also contains 0 to 40% by mass of the styrene-based elastomer in 100% by mass of the thermoplastic resin.
Moreover, it is necessary that the content of the styrene component in the styrene-based elastomer is 15% by mass or more.
In addition, as thermoplastic resins other than styrene-based elastomers, polyolefin-based resins should be used from the viewpoint of ease of availability, relatively easy adjustment of heat resistance and flexibility, and compatibility with styrene-based elastomers. is preferred.

[Styrene-based elastomer]
The multilayer film used in the present invention contains a styrene-based elastomer as an essential component. By using a styrene-based elastomer, it becomes possible to impart resilience to the multilayer film.
The styrene-based elastomer is preferably a block copolymer represented by the following formula (I) or (II).
X-(Y-X)n ... (I)
(X-Y)n ... (II)
X in general formulas (I) and (II) is an aromatic vinyl polymer block represented by styrene (hereinafter referred to as a styrene component). may be different. Y is butadiene polymer block, isoprene polymer block, butadiene/isoprene copolymer block, hydrogenated butadiene polymer block, hydrogenated isoprene polymer block, hydrogenated butadiene/isoprene copolymer block. At least one selected from coalesced blocks, partially hydrogenated butadiene polymer blocks, partially hydrogenated isoprene polymer blocks and partially hydrogenated butadiene/isoprene copolymer blocks. Also, n is an integer of 1 or more.

Specific examples include styrene-ethylene/butylene-styrene copolymer, styrene-ethylene/propylene-styrene copolymer, styrene-ethylene/ethylene/propylene-styrene copolymer, and styrene-butadiene-butene-styrene copolymer. , styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-hydrogenated butadiene diblock copolymer, styrene-hydrogenated isoprene diblock copolymer, styrene-butadiene diblock copolymer, styrene-isoprene diblock copolymers, etc. Among them, styrene-ethylene/butylene-styrene copolymers, styrene-ethylene/propylene-styrene copolymers, styrene-ethylene/ethylene/propylene-styrene copolymers, Styrene-butadiene-butene-styrene copolymers are preferred. A block copolymer, which is a styrene-ethylene/butylene-crystalline olefin copolymer, can also be used.

The content of the styrene component in the styrene-based elastomer is required to be 15% by mass or more. If the content of the styrene component is less than 15% by mass, the film becomes too flexible and is poor in handleability, and when it is used for the surface layer, the film sticks to the roll during film formation due to the tackiness of the material. is difficult to obtain.
If the content of the styrene component is 15% by mass or more, it becomes possible to impart appropriate flexibility to the obtained film, and to obtain a film excellent in film formability and handleability. More preferably 17% by mass or more, still more preferably 20% by mass or more.

The content of the styrene component and the content of other components can be measured by using ¹ H-NMR or ¹³ C-NMR. Here, "the content of the styrene component" refers to the content ratio (% by mass) of the aromatic vinyl polymer block represented by styrene based on the mass of the styrene elastomer.
The melt flow rate of the styrene-based elastomer (value measured with a load of 2.16 kg under temperature conditions of 230° C.) is preferably 0.1 to 10 g/10 minutes, more preferably 0.15 to 9 g/10 minutes. is more preferable, and 0.2 to 8 g/10 minutes is particularly preferable. If the melt flow rate of the styrene elastomer is less than 0.1 g/10 minutes or more than 10 g/10 minutes, the compatibility with the polyolefin resin will decrease and the film-forming properties will deteriorate, resulting in sufficient flexibility and expandability. may not.

Examples of commercially available styrene elastomers include Tufprene A, Tufprene 125, Asaprene T-438, Asaprene T-439, Tuftec H1221, Tuftec H1041, Tuftec H1043, Tuftec H1052, Tuftec H1053, Tuftec H1517, Tuftec P1083, and Tuftec H5051. , Tuftec P2000 (manufactured by Asahi Kasei Corporation), Septon 4099, Septon HG252, Septon 8004, Septon 8006, Septon 8007L, Septon HG252, Septon V9461, Septon V9475, Hibler 7311, Hibler 7125F, Hibler 5127, Hibler 5125 (above, Kuraray DYNARON 1320P, DYNARON 4600P, DYNARON 8300P, DYNARON 8903P, DYNARON 9901P (manufactured by JSR Corporation) and the like.

Among them, commercially available styrene elastomers having a styrene component content of 15% by mass or more include, for example, Tuftec H1041, Tuftec H1043, Tuftec H1052, Tuftec H1053, Tuftec H1517, Tuftec P1083, Tuftec P5051, Tuftec P2000 (above, Asahi Kasei Corp.), Septon 8007L, Septon HG252, Hybler 5125 (manufactured by Kuraray Co., Ltd.), Dynaron 4600P, Dynaron 8903P, Dynaron 9901P (manufactured by JSR Corporation), and the like.
As the styrene-based elastomer, one type of elastomer may be used alone, or two or more types may be used in combination. It can be appropriately selected as necessary, taking into account the film formability when obtaining the multilayer film, the flexibility and handleability of the obtained multilayer film, and the expandability. It is more preferable to use two or more types in combination from the viewpoint of the film-forming property of the multilayer film and the performance of the resulting film.

[Polyolefin resin]
As the polyolefin-based resin, one or more resins selected from polypropylene-based resins, polyethylene-based resins, and olefin-based elastomers are preferably used from the viewpoint of availability, flexibility, handling, economy, etc. . Among them, polypropylene-based resins and polyethylene-based resins are preferable from the standpoint of availability and economy, and relatively easy control of heat resistance and flexibility.

Examples of polypropylene-based resins include homopolymers of propylene (homopolypropylene), copolymers of propylene as a main component and other copolymerizable monomers, and mixtures thereof.
Examples of the copolymer containing propylene as a main component and other copolymerizable monomers include random copolymers (random polypropylene) and block copolymers of propylene and ethylene or other α-olefins. (block polypropylene), block copolymers or graft copolymers containing a rubber component, and the like.
The α-olefin used as another monomer copolymerizable with propylene preferably has 4 to 12 carbon atoms, such as 1-butene, 1-pentene, 1-hexene and 1-heptene. , 1-octene, 4-methyl-1-pentene, 1-decene, and the like, and one or a mixture of two or more thereof is used.

Examples of polyethylene-based resins include ethylene homopolymers, ethylene-based copolymers of ethylene and other copolymerizable monomers (low-density polyethylene (LDPE), high-pressure low-density polyethylene, Linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), ethylene-based copolymer obtained by polymerization using a metallocene-based catalyst (metallocene-based polyethylene), ethylene-vinyl acetate copolymer, ethylene-(meth ) methyl acrylate copolymer, ethylene-(meth)ethyl acrylate copolymer, ethylene-(meth)butyl acrylate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid Metal ion cross-linked resins (ionomers) of copolymers and the like can be mentioned.
Among them, high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), from the viewpoint of ease of availability, handling of the resin, and ease of adjustment of the flexibility of the resulting film ) is preferably used.

An olefinic elastomer is a soft resin containing a polyolefinic resin and a rubber component. The rubber component may be dispersed in the polyolefinic resin, or they may be copolymerized with each other.
Specific examples of olefinic elastomers include ethylene-propylene copolymer elastomers, ethylene-1-butene copolymer elastomers, ethylene-propylene-1-butene copolymer elastomers, and ethylene-1-hexene copolymer elastomers. , ethylene-1-octene copolymer elastomer, ethylene-styrene copolymer elastomer, ethylene-norbornene copolymer elastomer, propylene-1-butene copolymer elastomer, ethylene-propylene-nonconjugated diene copolymer elastomer, ethylene Amorphous elastic copolymers mainly composed of olefins such as 1-butene-nonconjugated diene copolymer elastomers and ethylene-propylene-1-butene-nonconjugated diene copolymer elastomers, their derivatives and acid-modified Derivatives etc. can be mentioned.

The melt flow rates of polypropylene resins, polyethylene resins, olefin elastomers, etc. mentioned above are appropriately selected according to the molding method and application to which they are applied. It is preferable that the value obtained is 0.1 to 50 g/10 minutes. If it is 0.1 g/10 minutes or more, the formability of the film will be good, and if it is 50 g/10 minutes or less, it will be possible to maintain good film thickness accuracy. More preferably 0.5 to 40 g/10 minutes, still more preferably 1.0 to 30 g/10 minutes.

Regarding the strength of polypropylene-based resins, polyethylene-based resins, olefin-based elastomers, etc., it is preferable that the tensile modulus of a film obtained by using these resins alone is within the range of 50 to 2000 MPa. If the tensile modulus is within the range of 50 to 2000 MPa, it is possible to impart appropriate flexibility to the film of the present invention. It is more preferably in the range of 80 to 1900 MPa, still more preferably in the range of 100 to 1800 MPa.
As for the polyolefin-based resin, one type of resin may be used alone, or two or more types may be used in combination. Considering the flexibility, heat resistance, and film formability of the multilayer film to be obtained, it can be appropriately selected as necessary.

[Other resins]
In the elastomer layer of the laminated film of the present invention, a cyclic olefin-based resin, a polymethylpentene-based resin, or the like can be added as a resin other than the polypropylene-based resin, polyethylene-based resin, olefin-based elastomer, and styrene-based elastomer. .

Examples of cyclic olefin-based resins include norbornene-based polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene-based polymers are preferred. Examples of norbornene-based polymers include ring-opening polymers of norbornene-based monomers, and norbornene-based copolymers obtained by copolymerizing norbornene-based monomers with α-olefins such as ethylene. Hydrogenated products thereof can also be used.

[Other ingredients]
In order to provide the performance required for the resulting film, the multilayer film of the present invention is provided with heat resistance, weather resistance, antistatic performance, etc. as components other than styrene elastomers and polyolefin resins. Various additives can be blended in.
Specific examples include, for example, antistatic agents, antioxidants, neutralizers, lubricants, antiblocking agents, plasticizers, heat stabilizers, light stabilizers, dyes and pigments, crystal nucleating agents, ultraviolet absorbers, fillers, Inorganic fillers that impart rigidity and elastomers other than those mentioned above for imparting flexibility may be used as long as the effects of the present invention are not impaired.
Moreover, when it is necessary to impart different performance to each layer of the multilayer film, various additives can be imparted to each layer.

As the antistatic agent, a known one can be used, but compatibility with the obtained multilayer film, imparting long-term antistatic performance, suppression of bleeding out of the antistatic agent over time. Therefore, it is preferable to use a polymeric antistatic agent.

A known polymeric antistatic agent can be used, and for example, a block copolymer of a hydrophobic block and a hydrophilic block can be used. In the polymer-type antistatic agent, a hydrophobic block and a hydrophilic block form a block copolymer through an ester bond, an ether bond, an amide bond, an imide bond, a urethane bond, a urea bond, or the like.

Hydrophobic blocks include, for example, polyolefin blocks, and polyolefin blocks include blocks made of polyethylene, polypropylene, ethylene-propylene copolymers, and the like.

Hydrophobic blocks such as polyolefin blocks have polar groups such as carbonyl groups, hydroxyl groups and amino groups at both ends. The polar groups that the hydrophobic block has at both ends are polymerized with the carbonyl groups, hydroxyl groups, amino groups, etc. present at both ends of the hydrophilic block, or crosslinked with diisocyanate, diglycidyl ether, etc. Thereby, a block copolymer of a hydrophobic block and a hydrophilic block can be obtained.

Hydrophilic blocks can include, for example, polyether blocks, polyether-containing hydrophilic polymer blocks, cationic polymer blocks and anionic polymer blocks.
In addition, in order to further improve the antistatic properties, the polymer type antistatic agent may contain alkali metal or alkaline earth metal salts, quaternary ammonium salts, surfactants and ions, as long as the effects of the present invention are not impaired. A liquid or the like may be blended.

Examples of commercially available polyether-polyolefin block copolymers, which are one of high-molecular-weight antistatic agents, include Perestat 300, Perestat 230, Pelestat UC, Pelektron PVL, and Pelektron PVH (manufactured by Sanyo Chemical Industries, Ltd.). ) and the like.

As the ultraviolet absorber, known ones can be used, and examples thereof include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

As the light stabilizer, a known one can be used, and examples thereof include hindered amine light stabilizers.

Known substances such as organic particles, inorganic particles, and amide compounds can be used as lubricants and antiblocking agents. In addition, since it has excellent compatibility with the above-mentioned polyolefin resin, it is possible to impart defects due to bleeding out to the surface of the obtained film, long-term scratch resistance and slipperiness, so silicone-olefin copolymer is preferably used.

<Multilayer film>
The multilayer film of the present invention is a multilayer film having at least two layers, and contains 80 to 100% by mass of a styrene-based elastomer having a styrene component content of 15% by mass or more in 100% by mass of a thermoplastic resin. and a layer B containing 0 to 40% by mass of a styrene-based elastomer having a styrene component content of 15% by mass or more in 100% by mass of the thermoplastic resin and having a thickness of 3 to 15 μm. A multilayer film characterized by containing 75% by mass or more of a styrene-based elastomer in 100% by mass of a thermoplastic resin constituting the multilayer film.

At least one layer of the multilayer film of the present invention is a layer containing 80 to 100% by mass of a styrene-based elastomer having a styrene component content of 15% by mass or more in 100% by mass of the thermoplastic resin constituting the layer. (Layer A).
When the content of the styrene-based elastomer contained in the layer is 80 to 100% by mass, it becomes possible to provide the resulting film with good resilience and good film-forming properties. It is more preferably in the range of 82 to 100% by mass, still more preferably in the range of 84 to 100% by mass. The layer may be a single layer, or may be composed of two or more layers. When two or more layers are used, the content of the styrene-based elastomer in each layer may be the same or different as long as the content is within the above range.

The content of the styrene component of the styrene-based elastomer contained in Layer A is 15% by mass or more, preferably 17% by mass or more, and more preferably 20% by mass or more.
If the content of the styrene component is 15% by mass or more, it is possible to suppress the tackiness of Layer A while imparting sufficient flexibility and resilience to Layer A, which is effective during the formation of a multilayer film. It is possible to suppress blocking between films when conveying the film and winding the film.

In one preferred embodiment of the present invention, at least either the surface layer or the back layer is a layer made of only a styrene-based elastomer as the thermoplastic resin.
If at least one of the surface layer and the back layer is a layer composed only of a styrene-based elastomer as a thermoplastic resin, it is possible to provide a layer that does not impair the flexibility and resilience of the styrene-based elastomer. It becomes possible to impart sufficient flexibility and restorability to the film.

The other layer contains 0 to 40% by mass of a styrene elastomer having a styrene component content of 15% by mass or more in 100% by mass of thermoplastic resin and has a thickness of 3 to 15 μm (Layer B ).
The thickness of the layer is 3 to 15 μm, and the content of the styrene elastomer is 0 to 40% by mass with respect to 100% by mass of the thermoplastic resin contained in Layer B. A multilayer film obtained by It is possible to suppress the tackiness of the surface of either the front or back side having the layer, reduce the coefficient of friction of the surface on the layer side, and improve the transportability during film formation of a multilayer film or between films when the film is wound. blocking can be suppressed.

The thickness of layer B is more preferably in the range of 4 to 15 μm, more preferably 5 to 15 μm, and the content of the styrene elastomer is more preferably 0 to 35% by mass, more preferably 0 to 30% by mass. is.
Layer B can be provided as either the surface layer or the back layer of the multilayer film, but whether to provide the layer on the front or back layer is appropriately selected in consideration of the method of use of the multilayer film. can do.

The styrene component content of the styrene-based elastomer contained in Layer B must be 15% by mass or more. If the content of the styrene component is less than 15% by mass, the film becomes too flexible and is poor in handleability, and when it is used for the surface layer, the film sticks to the roll during film formation due to the tackiness of the material. is difficult to obtain.
If the content of the styrene component is 15% by mass or more, it becomes possible to impart appropriate flexibility to the obtained film, and to obtain a film excellent in film formability and handleability. More preferably 17% by mass or more, still more preferably 20% by mass or more.

As for the surface roughness of layer B, it is preferable that the value of arithmetic mean roughness Ra is in the range of 0.1 to 5.0 μm. When the value of the arithmetic mean roughness Ra is in the range of 0.1 to 5.0 μm, the layer has good slipperiness and blocking between films when the film is wound can be improved. can. When the thickness is less than 0.1 μm, the blocking property is deteriorated, and when the thickness exceeds 5.0 μm, when the film is wound up, the unevenness is likely to be transferred to the surface opposite to the layer, which is not preferable. . A more preferable range of the arithmetic mean roughness Ra is 0.1 to 5.0 μm, and a more preferable range is 0.1 to 3.0 μm.

As for the friction coefficient of the layer B, it is preferable that the static friction coefficient is 0.800 or less. When the coefficient of static friction is 0.800 or less, sticking of the film to various rolls during film formation and sticking of films to each other are suppressed, and film transportability and blocking between films when the film is wound are suppressed. can be improved. The coefficient of static friction is more preferably 0.750 or less, still more preferably 0.700 or less. As for the friction coefficient, not only the static friction coefficient but also the dynamic friction coefficient is preferably 0.800 or less. When the coefficient of dynamic friction is 0.800 or less, it becomes possible to improve the transportability of the film and the blocking between films as in the case of the coefficient of static friction. The coefficient of dynamic friction is more preferably 0.750 or less, still more preferably 0.700 or less.

[Total Content of Styrene Elastomer]
Furthermore, it is necessary that the total 100% by mass of the thermoplastic resin used in all the layers constituting the multilayer film contain 75% by mass or more of the styrene elastomer. If the total content of the styrene-based elastomer is 75% by mass or more, it is possible to impart sufficient restorability to the resulting film. More preferably 78% by mass or more, still more preferably 81% by mass or more.

[Structure of multilayer film]
The multilayer film of the present invention has at least two layers, layer A and layer B, and contains 75% by mass or more of a styrene elastomer in 100% by mass of the thermoplastic resin constituting the multilayer film. , and those having arbitrary layer configurations are included. Examples include, but are not limited to, layer A/layer B, layer A1/layer A2/layer B, layer A1/layer A2/another layer/layer B, and the like. Here, "layer A1" and "layer A2" refer to layers corresponding to layer A having the same or different compositions, and "another layer" refers to a layer that does not correspond to layer A or layer B. do.

[Thickness of multilayer film]
Moreover, the total thickness of the multilayer film of the present invention is preferably 30 to 250 μm. If it is 30 μm or more, the film-forming property when producing the film and the handleability of the obtained film will be good, and if it is 250 μm or less, the economical viewpoint and the ability to pass through processes such as adhesive processing using the film will be maintained. becomes possible. In addition, from the viewpoint of economy and the load applied to the film and equipment during expansion, it is more preferably within the range of 30 to 200 μm, and more preferably within the range of 30 to 150 μm.

[Tensile modulus of multilayer film]
The tensile modulus of the multilayer film of the present invention is preferably in the range of 50-1000 MPa. If it is 50 MPa or more, sufficient rigidity is imparted to the film, so that it is possible to maintain good handleability. It is possible to keep the film at an appropriate value, and furthermore, it is possible to make the load applied to the film and the device at the time of expansion appropriate. More preferably 50 to 7000 MPa, still more preferably 50 to 400 MPa.

[Molding method of multi-layer film]
As a method for molding the multilayer film of the present invention, a known method can be used, but a melt extrusion molding method is preferably used. Among the melt extrusion molding methods, a T-die molding method in which a molten resin is extruded from an extruder having a T-die and solidified by cooling to obtain a film is more preferable.

In order to obtain a film, it is preferable to adopt a co-extrusion T-die molding method using a plurality of extruders. By using a co-extrusion T-die molding method using a plurality of extruders, it is possible to obtain a multi-layered film, and it is also possible to form a layer made of the resin composition of the present invention on only one side of the front and back. It is also possible to use both sides.
Further, by extruding the same resin from all extruders, it is possible to obtain a substantially monolayer film in which all layers are made of the same resin composition.

As a coextrusion T die molding method, a multi-manifold die is used to form a plurality of resin layers into a film, and then they are brought into contact in the T die to form multiple layers to obtain a film. A method of obtaining a multilayer film after merging and adhering a plurality of resins using an apparatus for merging the resins.

The film may optionally be surface-treated on one or both sides by methods such as plasma treatment, corona treatment, ozone treatment and flame treatment. It is possible to select whether to surface-treat one side or both sides depending on the intended use of the resulting film.

<Adhesive film>
By laminating an adhesive layer on at least one surface of the multilayer film of the present invention, an adhesive film can be obtained (hereinafter also referred to as "the adhesive film of the present invention").

The adhesive used for the adhesive layer is not particularly limited, but various adhesives such as natural rubber resins, acrylic resins, styrene resins, silicone resins, and polyvinyl ether resins are used. A functional layer such as an adhesive layer or a thermosetting resin layer may be further provided on the adhesive layer.

In the pressure-sensitive adhesive film of the present invention, one side or both sides of the film before laminating the pressure-sensitive adhesive layer may be subjected to the surface treatment described above. A primer layer may be provided between the substrate film and the adhesive layer, if necessary.
The thickness of the adhesive layer and the primer layer can be appropriately determined according to need.

The pressure-sensitive adhesive film of the present invention is excellent in resilience and can be easily stored and accommodated temporarily, so that it can be suitably used in semiconductor manufacturing processes.

Examples and comparative examples of the present invention will be shown and described below in detail, but the present invention is not limited to these examples. The materials used in the following examples and comparative examples, the methods for measuring the properties evaluated, etc. are as follows.

[Materials used]
As thermoplastic resins, the following styrene-based elastomers and polyolefin-based resins were used.

<Styrene-based elastomer>
Styrene-based elastomer (A):
Asahi Kasei Corporation, "Tuftec H1221" (melt flow rate at 230 ° C., 2.16 kg: 4.5 g / 10 minutes, styrene component content: 12% by mass, styrene-ethylene-butylene-styrene copolymer)
Styrene-based elastomer (B):
Asahi Kasei Corporation, "Tuftec H1041" (melt flow rate at 230 ° C., 2.16 kg: 5.0 g / 10 minutes, styrene component content: 30% by mass, styrene-ethylene-butylene-styrene copolymer)
Styrene-based elastomer (C):
Asahi Kasei Corporation, "Tuftec H1517" (melt flow rate at 230 ° C., 2.16 kg: 3.0 g / 10 minutes, styrene component content: 43% by mass, styrene-ethylene-butylene-styrene copolymer)
Styrene-based elastomer (D):
JSR Corporation, "Dynaron 4600P" (melt flow rate at 230 ° C., 2.16 kg: 5.5 g / 10 minutes, styrene component content: 20% by mass, styrene-ethylene / butylene-crystalline olefin copolymer)

<Polyolefin resin>
Japan Polyethylene Co., Ltd., "Novatec HF560" (high-density polyethylene, 190 ° C., melt flow rate at 2.16 kg: 7.0 g / 10 minutes, melting point: 135 ° C., tensile modulus of single film: 1000 MPa)

<Preparation of resin composition>
The above styrene-based elastomer and polyolefin-based resin were blended so that each layer had a total of 100 parts by mass, and mixed by dry blending. It was visually confirmed that the mixture was uniformly mixed, and a resin composition for film molding was prepared for each of the surface layer, the intermediate layer, and the back layer.

<Film forming method>
Each hopper of three single-screw extruders manufactured by Toshiba Machine (for surface layer: 35 φ mm, L / D = 25 mm, for intermediate layer: 50 φ mm, L / D = 32, for back layer: 35 φ mm, L / D = 25 mm) The dry blended raw material is put in, the extruder temperature of each extruder is set to 190 to 240 ° C., and the three-layer structure of the surface layer / intermediate layer / back layer is combined at the feed block section, and a 650 mm wide T die (Temperature setting: 240°C, lip opening: 0.5 mm). For the thickness configuration, each extruder rotation speed was set so as to achieve the thicknesses shown in Table 1.

The extruded molten resin is nip-molded by a winder equipped with a mat-like cooling roll and a mat-like rubber roll (cooling roll width: 700 mm x φ350 mm, roll temperature: about 30°C). Then, the film was subjected to corona treatment and wound up to obtain a multi-layered film of three kinds and three layers having a predetermined thickness. Further, in the present invention, the surface of the obtained film on the cooling roll side is expressed as the surface layer.

[Total thickness of film]
Using a contact-type thickness meter, the thickness of the film was measured at the central portion and both ends, and it was confirmed that the film had a predetermined thickness.

[Thickness of each layer]
The thickness of each layer was set by calculation from the amount of resin extruded from each extruder. Moreover, from the result of cross-sectional observation of the obtained film, it was confirmed that the thickness was as set.

[Total Content of Styrene Elastomer]
Calculated from the content of the styrene elastomer contained in each layer and the ratio of the thickness of each layer, and the total content (% by mass) of the styrene elastomer with respect to the total amount (100% by mass) of the thermoplastic resin contained in the multilayer film. did.

[Film formability]
The thickness stability and handleability of the film produced by the film-forming method described above were evaluated according to the following criteria.
⊚: Good film formability without sticking to the conveying roll of the winder.
◯: A film can be formed although there is slight sticking to the transport roll.
x: Remarkable sticking to the conveying roll, film formation not possible.

[Measurement of arithmetic surface roughness Ra]
According to a method in accordance with JIS B0601: 2001, a surface roughness profile measuring machine SURFCOM FLEX-50A manufactured by Tokyo Seimitsu Co., Ltd., using a stylus with a tip radius of 2 μm and a conical taper angle of 60 °, a measuring force of 0.6 mN, and a cut Measurement was performed under the conditions of off value λc = 0.8 mm, evaluation length = 2.0 mm, filter type = Gaussian, λs filter type = cutoff ratio 300, and evaluation speed = 0.3 mm/s.

[Measurement of friction coefficient]
Using a method compliant with JIS K7125 and a friction coefficient measurement tester, test temperature: 23 ° C., relative humidity: 50%, test speed: 100 mm / min, test load: 200 g (1.96 N). The surface of the back layer side of the film and a smooth aluminum plate were overlapped, and the static friction coefficient and dynamic friction coefficient between the two materials were measured. As the value of each friction coefficient, the average value of 5 tests was used.

[Measurement of resilience]
A test piece was taken from the obtained multilayer film using a dumbbell "SDK-600" made according to JISK6732, and an autograph (AGS-X manufactured by Shimadzu Corporation) was measured under the following test conditions. Measurement was performed using the following calculation formula to calculate the recovery rate.
The recovery rate was measured in the extrusion direction (MD) of the film.

Test atmosphere: 23°C, 50% RH
Test piece: JISK6732 compliant dumbbell "SDK-600" used Test conditions Test speed: 200mm/min
Distance between chucks: 40mm
Tensile elongation: 50%
Holding time: Hold for 1 minute after 50% elongation

a formula:

[Tensile modulus]
From the obtained multilayer film, a test piece was taken using a dumbbell "SDK-600" created according to JISK6732, and with reference to JISK7127, an autograph (Shimadzu The tensile modulus (MPa) was measured at a tensile speed of 50 mm/min using AGS-X manufactured by Seisakusho.
The tensile modulus was measured in the extrusion direction (MD) of the film.

[Tensile breaking strength, tensile breaking elongation]
From the obtained film, a test piece was taken using a dumbbell "SDK-600" created according to JISK6732, and a small desktop tester (EZ-L manufactured by Shimadzu Corporation) was placed in an atmosphere of 23 ° C. and 50% RH. ) was used to measure tensile strength at break (MPa) and elongation (%) at a tensile speed of 300 mm/min.
Tensile breaking strength and elongation were measured in the extrusion direction (MD) of the film.

[Example 1]
Styrene-based elastomer (B) and styrene-based elastomer (D) as surface layer resins, styrene-based elastomer (B), styrene-based elastomer (C) and styrene-based elastomer (D) as intermediate layer resins, and back layer resins High-density polyethylene was used as the resin in the content shown in Table 1, and a 100-μm-thick film consisting of 3 types and 3 layers was obtained by the film-forming method described above. The thickness of each layer was 20 μm for the surface layer, 72.5 μm for the intermediate layer, and 7.5 μm for the back layer.
The surface layer and the intermediate layer contained 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the total content of the styrene elastomer contained in the multilayer film was 92.5% by mass.
During the film formation of this film, no sticking of the film to various rolls including the transport roll was observed, and the film formability was good.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 0.80 μm, a static friction coefficient of 0.316, and a dynamic friction coefficient of 0.191. Since the film had no tackiness, it had good slipperiness and was excellent in anti-blocking property between films.
The resulting film had a resilience of 92%, exhibiting good resilience, a tensile modulus of 100 MPa, a tensile strength at break of 42 MPa, and a tensile elongation at break of 550%. It was a film excellent not only in restorability but also in handleability due to its high degree of elasticity.

[Example 2]
The procedure of Example 1 was repeated except that the amounts of the styrene-based elastomer (B), the styrene-based elastomer (D), and the high-density polyethylene shown in Table 1 were used as the resins for the intermediate layer.
The surface layer is 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the intermediate layer is 90% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used. The total content of the styrenic elastomer contained was about 85.3% by mass.
During the film formation of this film, no sticking of the film to various rolls including the transport roll was observed, and the film formability was good.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 0.83 μm, a static friction coefficient of 0.262, and a dynamic friction coefficient of 0.171. Since the film had no tackiness, it had good slipperiness and was excellent in anti-blocking property between films.
The resulting film had a resilience of 91%, exhibiting good resilience, a tensile modulus of 80 MPa, a tensile strength at break of 44 MPa, and a tensile elongation at break of 560%. It was a film excellent not only in restorability but also in handleability due to its high degree of elasticity.

[Example 3]
The procedure of Example 2 was repeated except that the styrene-based elastomer (B) and the styrene-based elastomer (D) were used in the amounts shown in Table 1 as resins for the surface layer.
The surface layer is 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the intermediate layer is 90% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used. The total content of the styrenic elastomer contained was about 85.3% by mass.
During the film formation of this film, no sticking of the film to various rolls including the transport roll was observed, and the film formability was good.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 0.78 μm, a static friction coefficient of 0.320, and a dynamic friction coefficient of 0.192. Since the film had no tackiness, it had good slipperiness and was excellent in anti-blocking property between films.
The obtained film had a resilience of 91%, and had good resilience. It was a film excellent not only in restorability but also in handleability due to its high degree of elasticity.

[Example 4]
Styrene-based elastomer (B) and styrene-based elastomer (D) as resins for the surface layer, and styrene-based elastomer (B), styrene-based elastomer (D) and high-density polyethylene as resins for the intermediate layer, as shown in Table 1. The procedure was carried out in the same manner as in Example 2, except that the amount was used.
The surface layer is 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the intermediate layer is 85% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used. The total content of the styrenic elastomer contained was about 81.6% by mass.
During the film formation of this film, no sticking of the film to various rolls including the transport roll was observed, and the film formability was good.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 1.05 μm, a static friction coefficient of 0.311, and a dynamic friction coefficient of 0.182. Since the film had no tackiness, it had good slipperiness and was excellent in anti-blocking property between films.
The resulting film had a resilience of 91%, exhibiting good resilience, a tensile modulus of 108 MPa, a tensile strength at break of 48 MPa, and a tensile elongation at break of 590%. It was a film excellent not only in restorability but also in handleability due to its high degree of elasticity.

[Example 5]
The procedure of Example 1 was repeated except that the styrene elastomer (D) and the high-density polyethylene were blended in the amounts shown in Table 1 as the resin for the back layer.
The surface layer and the intermediate layer are 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the back layer is 15% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used. The total content of styrene-based elastomer contained in the multilayer film was about 93.6% by mass.
During the film formation of this film, no sticking of the film to various rolls including the transport roll was observed, and the film formability was good.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 1.00 μm, a static friction coefficient of 0.525, and a dynamic friction coefficient of 0.488. The film contained only 15% by mass of the elastomer, and since the content was also small, it did not exhibit tackiness, had slipperiness, and was excellent in blocking resistance between films.
The resulting film had a resilience of 92%, exhibiting good resilience, a tensile modulus of 76 MPa, a tensile strength at break of 46 MPa, and a tensile elongation at break of 570%. It was a film excellent not only in restorability but also in handleability due to its high degree of elasticity.

[Comparative Example 1]
The procedure of Example 1 was repeated except that the thickness of each layer was 20 μm for the surface layer, 78.5 μm for the intermediate layer, and 1.5 μm for the back layer.
The surface layer and the intermediate layer contained 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the total content of the styrene elastomer contained in the multilayer film was 98.5% by mass.
During the film formation of this film, slight sticking was observed on various rolls including the transport roll, but film formation was possible.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 1.05 µm, a static friction coefficient of 1.003, and a dynamic friction coefficient of 0.980. Although the layer did not contain a styrene-based elastomer, the layer did not have a sufficient thickness, so the coefficient of friction was large and the film was inferior in slipperiness and in blocking resistance between films.

[Comparative Example 2]
The procedure of Example 5 was repeated except that the styrene-based elastomer (D) and the high-density polyethylene were blended in the amounts shown in Table 1 as the resin for the back layer.
The surface layer and the intermediate layer are 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the back layer is 50% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used. The total content of styrene-based elastomer contained in the multilayer film was about 96.3% by mass.
During the film formation of this film, slight sticking was observed on various rolls including the transport roll, but film formation was possible.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 0.80 μm, a static friction coefficient of 0.893, and a dynamic friction coefficient of 0.841. Since the styrene-based elastomer was contained in a large amount of 50% by mass, the film had a large coefficient of friction, poor slipperiness, and poor blocking resistance between films.

[Comparative Example 3]
The procedure of Example 4 was repeated except that the thickness of each layer was 20 μm for the surface layer, 60 μm for the intermediate layer, and 20 μm for the back layer.
The surface layer is 100% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used, and the intermediate layer is 85% by mass of the styrene elastomer in 100% by mass of the thermoplastic resin used. The total content of the styrenic elastomer contained was 71.0% by mass.
During the film formation of this film, no sticking of the film to various rolls including the transport roll was observed, and the film formability was good.
The back layer side of the obtained film had an arithmetic mean roughness Ra of 0.81 μm, a static friction coefficient of 0.301, and a dynamic friction coefficient of 0.190. Since the film had no tackiness, it had good slipperiness and was excellent in anti-blocking property between films.
However, the restorability of the obtained film was 80%.
Since the total amount of the styrene-based elastomer contained in the multilayer film was insufficient, it was confirmed that the film did not have sufficient restorability.

[Comparative Example 4]
The procedure was carried out in the same manner as in Example 1, except that the styrene-based elastomer (A) was used in the amount shown in Table 1 as the resin for the surface layer.
The surface layer and the intermediate layer contained 100% by mass of styrene-based elastomer in 100% by mass of the thermoplastic resin used, and the total amount of styrene-based elastomer contained in the multilayer film was 92.5%.
However, the styrene content of the styrene-based elastomer used in the surface layer was small, and the tackiness of the surface layer was strong. Therefore, it was difficult to form a film and obtain a film.

[Industrial applicability]
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a film which is excellent in film formability when a thermoplastic resin is formed into a film and which is excellent in restorability after expansion. Further, it is desirable to provide an adhesive film for a semiconductor manufacturing process, which has excellent restorability, so that it can be restored to a state close to its original shape after being expanded, and can be easily stored or accommodated temporarily even in a state where chips are stacked. to enable.

Claims (9)

A multilayer film having at least two layers,
A layer A containing 80 to 100% by mass of a styrene-based elastomer having a styrene component content of 15% by mass or more in 100% by mass of the thermoplastic resin;
A layer B containing 0 to 40% by mass of a styrene elastomer having a styrene component content of 15% by mass or more in 100% by mass of a thermoplastic resin and having a thickness of 3 to 15 μm,
A multilayer film containing 75% by mass or more of a styrene-based elastomer in 100% by mass of a thermoplastic resin constituting the multilayer film. 2. The multilayer film according to claim 1, wherein the thermoplastic resin other than the styrene elastomer is a polyolefin resin. 3. The multi-layer film according to claim 1, wherein at least one of the front and back layers is a layer comprising only a styrene-based elastomer as a thermoplastic resin. 4. The multilayer film according to any one of claims 1 to 3, wherein at least one of the front and back layers is a layer B, and the layer has a static friction coefficient of 0.800 or less. The multilayer film according to any one of claims 1 to 3, wherein at least one of the front and back layers is a layer B, and both the static friction coefficient and the dynamic friction coefficient of the layer are 0.800 or less. . 6. The multilayer film according to any one of claims 1 to 5, wherein the film has a recovery rate of 90% or more in the following test methods.
<Method for measuring recovery rate>
Test atmosphere: 23°C, 50% RH
Test piece: JISK6732 compliant dumbbell "SDK-600" used Test conditions Test speed: 200mm/min
Distance between chucks: 40mm
Tensile elongation: 50%
Holding time: Hold for 1 minute after 50% elongation

After the retention time has elapsed, the specimen is removed from the tester, and after 5 minutes have elapsed, the recovery rate is calculated using the following formula.

a formula:

7. The multilayer film according to any one of claims 1 to 6, which has a tensile modulus of 50 MPa or more. An adhesive film obtained by providing an adhesive layer on at least one surface of the multilayer film according to any one of claims 1 to 7. The pressure-sensitive adhesive film for a semiconductor manufacturing process according to claim 8, which is used in a semiconductor manufacturing process.