JP2007090644A - Multilayer mold-releasing film - Google Patents

Abstract

[PROBLEMS] To suppress void generation, adhesive flow-out and cushion layer resin exudation at the end face of a film during heat press molding while having heat resistance, releasability and followability to a substrate surface. Furthermore, the present invention provides a multilayer release film that can be easily discarded after use.
At least a release layer composed of a crystalline aromatic polyester resin having a melting point of 200 ° C. or higher measured using a differential scanning calorimeter and a melting point of 70 to 130 ° C. measured using a differential scanning calorimeter. And a multilayer release film having a cushion layer made of a polyolefin resin having a melt flow rate of 7 g / 10 min or less, wherein the release layer has a thickness of 5 to 50 μm. Mold film.
[Selection figure] None

Description

The present invention suppresses the generation of voids during hot press molding, the flow of adhesive, and the seepage of the cushion layer resin on the film end face while having heat resistance, mold release properties, and followability to the substrate surface. Further, the present invention relates to a multilayer release film that can be easily discarded after use.

In the manufacturing process of a printed board, a flexible printed wiring board, a multilayer printed wiring board, etc., a release film is used when a copper-clad laminate or a copper foil is hot-pressed through a prepreg or a heat-resistant film. Further, in the manufacturing process of the flexible printed circuit board, when the cover lay film or the reinforcing plate is hot press bonded to the flexible printed circuit board body on which the electric circuit is formed by the thermosetting adhesive or the thermosetting adhesive sheet, the cover lay film is used. In order to prevent the hot plate and the press plate from adhering to each other, a release film is widely used.

In recent years, for release films, in addition to functions such as heat resistance that can withstand hot press molding and releasability for printed wiring boards and hot press plates, environmental issues and increased social demands for safety have led to disposal. The ease of processing has been demanded. In addition, non-contamination for copper circuits has become important in order to improve product yield during hot press molding.

Conventionally, as a release film, a fluorine-based film, a silicone-coated polyethylene terephthalate film, a polypropylene film, or the like as disclosed in Patent Document 1 or Patent Document 2 has been used.

However, although the fluorine-based film is excellent in heat resistance, releasability and non-contamination, it is expensive and has a problem that it is difficult to burn in waste incineration after use and generates toxic gas. there were.
In addition, the silicone-coated polyethylene terephthalate film may cause contamination of a printed wiring board, particularly a copper circuit, due to the migration of a low molecular weight substance contained in silicone, and may impair quality. In addition, the polypropylene film has a problem that it has poor heat resistance and insufficient releasability.

Also, in the hot press molding process, it is necessary for the release film to follow the unevenness of the substrate surface, but since conventional release films are inferior in followability, a flexible printed circuit board during hot press molding There was a problem that voids were generated inside, or the adhesive of the cover lay film oozed out to the electrode part, which hindered the plating process of the electrode part.

For such problems, Patent Document 3 discloses a multilayer release film comprising a release layer containing polymethylpentene and a cushion layer. Such a multilayer release film has good releasability and followability and is easy to dispose of after incineration. Polymethylpentene is also a substrate due to migration of low molecular weight substances contained in its constituent components. Contamination of the substrate and the like due to the flow-out of the coverlay adhesive have become problems. Further, since the melt flow rate of the resin forming the cushion layer is high, there is also a problem that the resin oozes out from the end face of the film.

Therefore, it has been considered to prevent the resin from exuding by lowering the melt flow rate of the resin forming the cushion layer, but there is a problem that the follow-up property is deteriorated.
Therefore, while having the performance required for a release film such as heat resistance, release property, and followability to the substrate surface, generation of voids during hot press molding, flow of adhesive, and cushion layer at the film end face At present, there is a demand for a release film that can suppress the seepage of resin.
JP-A-2-175247 Japanese Patent Laid-Open No. 5-283862 Japanese Patent Laid-Open No. 2003-246019

In view of the above situation, the present invention has heat resistance, releasability, followability to the substrate surface, generation of voids during hot press molding, flow of adhesive, and stain of the cushion layer resin on the film end face. It is another object of the present invention to provide a multilayer release film that can suppress sticking and can be easily discarded after use.

The present invention has at least a release layer composed of a crystalline aromatic polyester resin having a melting point of 200 ° C. or higher measured using a differential scanning calorimeter, and a melting point of 70 to 130 ° C. measured using a differential scanning calorimeter. And a multilayer release film having a cushion layer made of a polyolefin resin having a melt flow rate of 7 g / 10 min or less, wherein the release layer has a thickness of 5 to 50 μm. Type film.
The present invention is described in detail below.

As a result of intensive studies, the inventors of the present invention have determined the melting point and melt flow rate of the resin forming the cushion layer within a predetermined range in a multilayer release film having at least a release layer and a cushion layer, By defining the melting point and thickness of the resin forming the resin within a predetermined range, it has heat resistance, releasability, and followability to the substrate surface, while generating voids during hot press molding and flowing out adhesive. And it is possible to suppress the seepage of the cushion layer resin on the film end face, and furthermore, it is found that a multilayer release film that can be easily discarded after use can be manufactured, and the present invention is completed. It came to.

The multilayer release film of this invention has a release layer which consists of crystalline aromatic polyester resin whose melting | fusing point measured using the differential scanning calorimeter is 200 degreeC or more.
By using such a resin having a high melting point for the release layer, the release layer has a release property without melting even in the hot press molding step, and the release layer is destroyed. Can be prevented.

The lower limit of the melting point of the crystalline aromatic polyester resin measured using a differential scanning calorimeter is 200 ° C. Since the hot press molding step is usually performed at less than 200 ° C., if the melting point is less than 200 ° C., the release layer melts in the hot press molding step, and the heat resistance of the multilayer release film is lowered. A preferred lower limit is 220 ° C. Although the upper limit of melting | fusing point is not specifically limited, When carrying out melt molding, a preferable upper limit is 400 degreeC from the reason of the cost of heating equipment.
In addition, it does not specifically limit as said differential scanning calorimeter, For example, DSC 2920 (made by TA Instruments) etc. can be used.

The crystalline aromatic polyester resin having a melting point of 200 ° C. or higher measured using the differential scanning calorimeter is not particularly limited. For example, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polyethylene naphthalate, polybutylene. Naphthalate, butanediol terephthalate polytetramethylene glycol copolymer, and the like. These may be used independently and 2 or more types may be used together. Of these, polybutylene terephthalate is preferably used because it is excellent in non-contamination and crystallinity.

The release layer may contain a stabilizer. The stabilizer is not particularly limited, and examples thereof include 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,9-bis. {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5 5] hindered phenol antioxidants such as undecane; tris (2,4-di-t-butylphenyl) phosphite, trilauryl phosphite, 2-t-butyl-α- (3-t-butyl-4 -Hydroxyphenyl) -p-cumenylbis (p-nonylphenyl) phosphite, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, pentaerythryl Tetrakis (3-laurylthiopropionate), thermal stabilizers such as ditridecyl 3,3'-thiodipropionate and the like.

The said release layer may contain additives, such as a fiber, an inorganic filler, a flame retardant, an ultraviolet absorber, an antistatic agent, an inorganic substance, a higher fatty acid salt, in the range which does not impair the effect of this invention.

The fibers are not particularly limited, and examples thereof include glass fibers, carbon fibers, boron fibers, silicon carbide fibers, alumina fibers, amorphous fibers, inorganic fibers such as silicon / titanium / carbon fibers, and organic fibers such as aramid fibers. Can be mentioned.

The inorganic filler is not particularly limited, and examples thereof include calcium carbonate, titanium oxide, mica and talc.
The flame retardant is not particularly limited, and examples thereof include hexabromocyclododecane, tris- (2,3-dichloropropyl) phosphate, pentabromophenyl allyl ether, and the like.

The ultraviolet absorber is not particularly limited, and examples thereof include pt-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2,4,5- And trihydroxybutyrophenone.
The antistatic agent is not particularly limited, and examples thereof include N, N-bis (hydroxyethyl) alkylamine, alkylallyl sulfonate, and alkyl sulfonate.

It does not specifically limit as said inorganic substance, For example, barium sulfate, an alumina, a silicon oxide etc. are mentioned.
The higher fatty acid salt is not particularly limited, and examples thereof include sodium stearate, barium stearate, and sodium palmitate.

The release layer may contain a thermoplastic resin and a rubber component in order to modify its properties. The thermoplastic resin is not particularly limited, and examples thereof include polyolefin, modified polyolefin, polystyrene, polyvinyl chloride, polyamide, polycarbonate, polysulfone, and polyester.
The rubber component is not particularly limited. For example, natural rubber, styrene-butadiene copolymer, polybutadiene, polyisoprene, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer (EPM, EPDM), polychloroprene, Examples include butyl rubber, acrylic rubber, silicon rubber, urethane rubber, olefin-based thermoplastic elastomer, styrene-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer, ester-based thermoplastic elastomer, and amide-based thermoplastic elastomer.

The release layer may contain an inorganic compound having a large aspect ratio. By including an inorganic compound having a large aspect ratio, the resulting multilayer release film of the present invention has improved release properties at high temperatures, and additives and low molecular weight substances contained in the film bleed out to the film surface. That can be suppressed, and cleanliness during hot press molding is improved.
The inorganic compound having a large aspect ratio is not particularly limited, and examples thereof include layered silicates such as clay; layered double hydrates such as hydrotalcite.

The release layer has a thickness lower limit of 5 μm and an upper limit of 50 μm. If the thickness is less than 5 μm, the thickness is too thin and the strength of the release layer is impaired. Therefore, the release layer may be destroyed in the hot press molding step or the release step of the multilayer release film. If it exceeds, the stiffness of the multilayer release film becomes too strong and the flexibility is impaired, so the followability is lowered.
Furthermore, in the present invention, by setting the thickness of the release layer to 30 μm or less, a cushion layer and a release layer using a resin having a low melt flow rate of 0.3 g / 10 minutes or less as described later are provided. Even if combined, it is possible to suppress the bleeding of the cushion layer while maintaining sufficient followability.

The surface of the release layer preferably has smoothness, but for the purpose of slipping necessary for handling, anti-blocking properties, and air release during hot press molding, at least one side has an appropriate embossed pattern and fine irregularities. May be provided.
The method of the treatment is not particularly limited, and examples thereof include a method of rubbing the surface of the release layer using a metal roll or the like having an embossed pattern, a cloth such as gauze, a brush, or the like.

The release layer may be subjected to heat treatment or friction treatment in order to improve heat resistance, dimensional stability, and release properties.
Although it does not specifically limit as the method of the said heat processing, For example, the method of passing between the rolls heated to the fixed process temperature, the heating with a heater, etc. are preferable.
The temperature of the heat treatment is not particularly limited as long as it is not lower than the glass transition temperature of the resin constituting the release layer and not higher than the melting point, but a preferable lower limit is 120 ° C. and a preferable upper limit is 200 ° C. When the temperature is lower than 120 ° C., the effect of improving the releasability by heat treatment may be hardly obtained. When the temperature exceeds 200 ° C., the release layer is likely to be deformed during the heat treatment and may not be manufactured. A more preferable lower limit is 170 ° C., and a more preferable upper limit is 190 ° C.

The friction treatment method is not particularly limited, and examples thereof include a method of rubbing the surface of the release layer using a cloth such as a metal roll or gauze, a brush, or the like.

The multilayer release film of the present invention has a cushion layer made of a polyolefin resin having a melting point of 70 to 130 ° C. measured using a differential scanning calorimeter and a melt flow rate of 7 g / 10 min or less.
By using a resin having a melting point and a melt flow rate within the above range for the cushion layer, the cushion layer starts to soften near the temperature at which the adhesive melts, and improves the followability to the irregularities on the surface of the flexible printed circuit board. Or the coverlay adhesive can be prevented from flowing out.

The polyolefin resin has a lower limit of melting point of 70 ° C. and an upper limit of 130 ° C. measured using a differential scanning calorimeter. If it is less than 70 ° C., the function of the cushion layer for uniformly applying the pressing pressure to the flexible printed circuit board in the hot press molding process cannot be performed sufficiently, and the ambient temperature during storage of the film is 50 depending on the situation. Although it may be ˜60 ° C., in that case, the cushion layer resin may melt and ooze out depending on the ambient temperature and cause blocking. When the temperature exceeds 130 ° C., the cushion layer is not sufficiently softened in a temperature region where the adhesive melts, and the problem of the adhesive flowing out occurs.

The polyolefin resin has a melt flow rate upper limit of 7 g / 10 min. If it exceeds 7 g / 10 minutes, the resin oozes out from the end face of the multilayer release film, resulting in poor workability. Although it does not specifically limit as a minimum of a melt flow rate, 0.1 g / 10min can be mentioned as a minimum of the resin now generally available.
In addition, as described above, by combining a release layer having a thickness of 30 μm or less and a cushion layer, sufficient followability can be maintained even when the melt flow rate is 0.3 g / 10 min or less, which has been impossible in the past. Meanwhile, it is possible to suppress the seepage of the cushion layer.

Although it does not specifically limit as polyolefin resin whose melting | fusing point measured using the said differential scanning calorimeter is 70-130 degreeC and a melt flow rate is 7 g / 10min or less, For example, polyethylene, ethylene-vinyl acetate Examples thereof include copolymers of ethylene-acrylic monomers such as copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-acrylic acid copolymers. These may be used independently and 2 or more types may be used together.

Further, the cushion layer may contain additives such as fibers, inorganic fillers, flame retardants, ultraviolet absorbers, antistatic agents, inorganic substances, higher fatty acid salts, etc., as in the case of the release layer. .

Although it does not specifically limit as thickness of the said cushion layer, A preferable minimum is 30 micrometers and a preferable upper limit is 150 micrometers. When the thickness is less than 30 μm, the thickness is too thin, and when the resin constituting the cushion layer is softened during hot press molding, a portion where the cushion layer does not exist partially occurs, and the press pressure is uniformly applied to the flexible printed circuit board. May not be able to load. If it exceeds 150 μm, the stiffness of the multilayer release film becomes too strong and the flexibility is impaired, and the followability may be lowered. Furthermore, since it is thicker than necessary, the excess part may ooze out from the end face of the film, causing problems. A more preferable lower limit is 60 μm, and a more preferable upper limit is 100 μm.

Although it does not specifically limit as the whole thickness of the multilayer release film of this invention, A preferable minimum is 50 micrometers and a preferable upper limit is 200 micrometers. When it is less than 50 μm, the strength of the multilayer release film is insufficient, and when it exceeds 200 μm, flexibility is impaired and handling properties are deteriorated. In addition, the manufacturing cost increases.

The multilayer release film of the present invention preferably has a dimensional change rate of 1.5% or less when pressed at 170 ° C. with a load of 3 MPa for 60 minutes. If it exceeds 1.5%, the circuit pattern may be damaged during hot press molding. More preferably, it is 1.0% or less. Furthermore, it is preferable that the dimensional change rate in the width direction (hereinafter also referred to as TD) and the length direction (hereinafter also referred to as MD) of the film is in the same direction and in the same order. When the vertical and horizontal dimensional changes such that one (for example, MD) contracts and the other (for example, TD) expands are different, the circuit pattern may be damaged during hot press molding.

The method for producing the multilayer release film of the present invention is not particularly limited. For example, a water-cooled or air-cooled coextrusion inflation method, a method of forming a film by a coextrusion T-die method, and a film to be a release layer were produced. Thereafter, a method of laminating a cushion layer on this film by an extrusion laminating method, a method of dry lamination of a film to be a release layer and a film to be a cushion layer, a solvent casting method, a hot press molding method and the like can be mentioned. Especially, the method of forming into a film by the coextrusion T die method is suitable from the point which is excellent in the thickness control of each layer.

In the solvent casting method, for example, after the anchor layer is undercoated on the film to be the cushion layer, the resin composition dissolved in the solvent is applied on the anchor layer, and the coating film is uniformly heated and dried. A multilayer release film is produced by forming a release layer.
Moreover, in the said hot press molding, the film used as a mold release layer and the film used as a cushion layer are overlap | superposed and hot press molded, for example.

According to the present invention, while having heat resistance, releasability and followability to the substrate surface, it suppresses generation of voids during hot press molding, flow of adhesive and exudation of cushion layer resin at the film end face. Furthermore, it is possible to provide a multilayer release film that can be easily discarded after use.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(1) Resin material used for release layer A For the release layer A, polybutylene terephthalate (manufactured by Mitsubishi Engineering Plastics, Novadejuran 5010R5) was used as the crystalline aromatic polyester resin.

(2) Resin material used for release layer B For the release layer B, polybutylene terephthalate (manufactured by Mitsubishi Engineering Plastics, Novadejuran 5010R5) was used as the crystalline aromatic polyester resin.

(3) Resin material used for release layer C For the release layer C, polybutylene terephthalate (manufactured by Mitsubishi Engineering Plastics, Novadejuran 5010R5) was used as the crystalline aromatic polyester resin.

(4) Resin material used for cushion layer 1 For the cushion layer 1, a low density polyethylene (UBE150: MFR = 0.23 manufactured by Ube Industries, Ltd.) is used as a polyolefin resin having a melt flow rate of 0.2 g / 10 min. Using.

(5) Resin material used for the cushion layer 2 For the cushion layer 2, low density polyethylene (CX1001: MFR = 1.0, manufactured by Sumitomo Chemical Co., Ltd.) was used as a polyolefin resin having a melt flow rate of 1 g / 10 min. .

(6) Resin material used for the cushion layer 3 The cushion layer 3 has an ethylene-methylmethacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., ACRIFT WD301: MFR = 7.15) as a polyolefin resin having a melt flow rate of 7 g / 10 min. 0) was used.

(7) Resin material used for the cushion layer 4 For the cushion layer 4, low density polyethylene (manufactured by Sumitomo Chemical Co., Ltd., CX4002: MFR = 8.0) was used as a polyolefin resin having a melt flow rate of 8 g / 10 min. .

Example 1
(1) Production of multi-layer release film Resin for release layer A and resin for cushion layer 1 are respectively extruded into extruders (GM 30-28, screw diameter 30 mm, L / D28). ) And melted, and co-extruded with a multilayer T die having a T die width of 400 mm to produce a multilayer release film. At that time, a two-layer release film was prepared so that the film thicknesses of the release layer A and the cushion layer 1 were 20 μm and 80 μm, respectively.

(2) Production of flexible printed circuit board A laminate of copper-clad laminate cut to 400 mm × 400 mm, a coverlay film cut to 400 mm × 400 mm, and a multilayer release film obtained by cutting to 420 mm × 420 mm in this order. As one set, 32 sets were placed on a hot press and subjected to hot press molding under the conditions of a press temperature of 170 ° C., a press pressure of 300 N / cm ² , and a press time of 60 minutes, then the press pressure was released, and a multilayer release film was formed. The flexible printed circuit board was obtained by peeling off.
The coverlay film was installed with the epoxy adhesive side on the copper-clad laminate side, and the multilayer release film was installed with the release layer side on the coverlay film side.
As the copper-clad laminate, a 25 μm thick polyimide film (manufactured by DuPont, Kapton) is used as a base film, and after curing, an epoxy adhesive equivalent to 20 μm is applied, and a copper foil having a thickness of 35 μm and a width of 50 μm. Used were bonded at intervals of 50 μm.
As the coverlay film, a polyimide film having a thickness of 20 μm applied on a 25 μm-thick polyimide film (manufactured by DuPont, Kapton) was used.

(Example 2)
A multilayer release film was prepared by coextruding the resin for the release layer A and the resin for the cushion layer 2 in the same manner as in Example 1.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Example 3)
A multilayer release film was prepared by coextruding the resin for the release layer A and the resin for the cushion layer 3 in the same manner as in Example 1.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

Example 4
A multilayer release film was prepared by coextruding the resin for the release layer B and the resin for the cushion layer 1 in the same manner as in Example 1.
In that case, the multilayer release film was produced so that the film thickness of the release layer A and the cushion layer 1 might be 40 micrometers and 80 micrometers, respectively.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Example 5)
A multilayer release film was prepared by coextruding the resin for the release layer B and the resin for the cushion layer 2 in the same manner as in Example 4.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Example 6)
The resin for the release layer B, the resin for the cushion layer 3 and the resin for the release layer B are put into each extruder (extruder GM30-28 (screw diameter 30 mm, L / D28) manufactured by GM Engineering). A three-layer release film was prepared by coextrusion with a multilayer T die having a T die width of 400 mm so as to have a release layer B / cushion layer 3 / release layer B. At that time, a three-layer release film was prepared so that the film thickness of the release layer B and the cushion layer 3 was 40 μm and 80 μm, respectively.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Comparative Example 1)
A multilayer release film was prepared by coextruding the resin for release layer A and the resin for cushion layer 4 in the same manner as in Example 1.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Comparative Example 2)
A multilayer release film was prepared by coextruding the resin for release layer B and the resin for cushion layer 4 in the same manner as in Example 4.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Comparative Example 3)
A multilayer release film was prepared by coextrusion in the same manner as in Example 1 except that the resin for the release layer C and the resin for the cushion layer 1 were used, and the thickness of the release layer was 3 μm.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Comparative Example 4)
A multilayer release film was prepared by coextruding the resin for the release layer C and the resin for the cushion layer 2 in the same manner as in Comparative Example 3.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Comparative Example 5)
A multilayer release film was prepared by coextruding the resin for the release layer C and the resin for the cushion layer 3 in the same manner as in Comparative Example 3.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

(Comparative Example 6)
A multilayer release film was prepared by coextrusion in the same manner as in Example 6 except that the resin for the release layer C and the resin for the cushion layer 4 were used, and the thickness of the release layer was 3 μm.
A flexible printed circuit board was produced in the same manner as in Example 1 except that the obtained multilayer release film was used.

<Evaluation>
The following evaluation was performed about the multilayer release film obtained in Examples 1-6 and Comparative Examples 1-6, and the flexible printed circuit board. The results are shown in Table 1.

(1) Follow-up evaluation (existence of void generation)
The obtained flexible printed circuit board was checked for the presence or absence of air remaining portions (voids) with a microscope and evaluated according to the following criteria.
○: No void was seen.
X: A void was observed.

(2) Evaluation of strength of release layer The presence or absence of damage to the release layer of the peeled multilayer release film was visually confirmed and evaluated according to the following criteria.
○: No damage was observed in the release layer.
X: The release layer was destroyed.

(3) Amount of flow-out of adhesive The electrode part of the obtained flexible printed circuit board was visually confirmed (observed with a microscope) and evaluated according to the following criteria.
○: Less than 100 μm Δ: 100 to 120 μm
×: 120 μm or more

(4) Exuding amount of film end face The length of resin exuding from the film end face during the production of the flexible printed circuit board was measured and evaluated according to the following criteria.
○: Less than 5 mm Δ: 5 to 15 mm
×: 15 mm or more

According to the present invention, while having heat resistance, releasability and followability to the substrate surface, it suppresses generation of voids during hot press molding, flow of adhesive and exudation of cushion layer resin at the film end face. Furthermore, it is possible to provide a multilayer release film that can be easily discarded after use.

Claims (2)

At least a release layer composed of a crystalline aromatic polyester resin having a melting point of 200 ° C. or higher measured using a differential scanning calorimeter, a melting point of 70 to 130 ° C. measured using a differential scanning calorimeter, and A multilayer release film having a cushion layer made of a polyolefin resin having a melt flow rate of 7 g / 10 min or less,
The release layer is a multilayer release film having a thickness of 5 to 50 μm. 2. The multilayer release film according to claim 1, wherein the release layer has a thickness of 5 to 30 [mu] m, and the cushion layer is made of a polyolefin resin having a melt flow rate of 0.3 g / 10 min or less. .