CN115776944A

CN115776944A - Mold release film

Info

Publication number: CN115776944A
Application number: CN202180048706.3A
Authority: CN
Inventors: 河合奈瑠美; 中岛奈未; 小屋原宏明; 日下康成; 内田一步
Original assignee: Sekisui Chemical Co Ltd
Current assignee: Sekisui Chemical Co Ltd
Priority date: 2020-09-07
Filing date: 2021-09-03
Publication date: 2023-03-10
Also published as: TW202222930A; WO2022050396A1; JPWO2022050396A1

Abstract

The purpose of the present invention is to provide a mold release film which has excellent mold release properties and conformability to irregularities and is less likely to cause resin bleed-out. The present invention relates to a mold release film, which has a relaxation time (T) of a soft component at 180 ℃ measured by a CPMG method using pulse NMR ₂ ) Is 220 milliseconds or more and 330 milliseconds or less, and the soft component ratio at 30 ℃ measured by a Solid Echo method using pulse NMR after the release film is exposed to the following temperature conditions is 0.1% or more and 15% or less. Temperature conditions: the temperature is raised from 30 ℃ to 180 ℃ at a heating rate of 10 ℃/min, and then the temperature is lowered from 180 ℃ to 30 ℃ at a cooling rate of 10 ℃/min.

Description

Mold release film

Technical Field

The present invention relates to a release film.

Background

Release films are used in the production processes of printed wiring boards, flexible circuit boards, multilayer printed wiring boards, and the like.

In the manufacturing process of a flexible circuit board, a cover film is thermocompression bonded to a flexible circuit board main body on which a copper circuit is formed, with a thermosetting adhesive or a thermosetting adhesive sheet. In this case, by disposing the release film between the cover film and the hot press plate, the cover film and the hot press plate can be prevented from adhering to each other, and the adhesive can be prevented from bleeding out and causing troubles such as a trouble in plating treatment of the electrode portion.

The release film is required to have releasability which is easy to peel off after thermocompression bonding. In order to improve the mold release property, for example, the crystallinity of the release film is adjusted. Patent document 1 describes a release film having a release layer containing a polyester resin on at least one surface, and the crystallinity of the release layer is 10% or more and 50% or less.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-2730

Disclosure of Invention

Problems to be solved by the invention

In recent years, with the thinning of flexible circuit boards, further improvement in releasability has been demanded for release films. In recent years, release films including a plurality of layers including a release layer and a buffer layer have also been used in order to ensure performance such as releasability and conformability to unevenness (embeddability) in response to thinning of L/S (lines/spaces) of a flexible circuit board.

From the viewpoint of improving the followability to the irregularities, it is considered to further soften the release film (particularly the cushion layer). However, if the release film (particularly the cushion layer) is softened, the elastic modulus is lowered and the releasability is deteriorated, so that it is difficult to improve both the releasability and the conformability to the unevenness. Further, if the cushion layer is softened excessively, there is also a problem that bleeding of the resin constituting the cushion layer occurs at the time of hot press bonding.

The purpose of the present invention is to provide a release film which has excellent releasability and conformability to irregularities, and is less likely to cause resin bleeding.

Means for solving the problems

The present invention relates to a mold release film, which has a relaxation time (T) of a soft component at 180 ℃ measured by a CPMG method using pulse NMR (pulse nuclear magnetic resonance) ₂ ) Is 220 milliseconds or more and 330 milliseconds or less, and the soft component ratio at 30 ℃ measured by Solid Echo method using pulse NMR after the release film is exposed to the following temperature conditions is 0.1% or more and 15% or less.

[ temperature conditions ]

Heating from 30 deg.C to 180 deg.C at a heating rate of 10 deg.C/min, and cooling from 180 deg.C to 30 deg.C at a cooling rate of 10 deg.C/min

The present invention will be described in detail below.

The hot press bonding is usually carried out at a high temperature of about 160 to 180 ℃ and then the release film is peeled off after returning to normal temperature. In order to improve both the mold release property and the ability to follow the unevenness, it is necessary to produce: and a release film which softens at high temperature during hot press bonding and hardens when peeled off after returning to normal temperature, and has an appropriate elastic modulus. In order to obtain a release film showing such behavior, the present inventors used a pair ¹ Pulsed NMR for H-nucleus measurement was used to analyze the release film. In pulse NMR, the obtained data is divided into a plurality of components such as a hard component having high crystallinity and a soft component having low crystallinity, and the "relaxation time" is measured for each component, whereby the molecular mobility can be evaluated. Specifically, by mixing the obtained ¹ The free induction decay curve waveform of the spin-spin relaxation of the H-nucleus is separated into a plurality of components, and thereby the relaxation time of each component is obtained. It is noted that the spin-spin relaxation time, also referred to as transverse relaxation time, is commonly expressed as T ₂ . On the other hand, the spin-lattice relaxation time, also called longitudinal relaxation time, is commonly expressed as T ₁ 。

The present inventors have focused on a soft component having low crystallinity in a release film, and have studied the following: general will benefitRelaxation time (T) of Soft component at 180 ℃ measured by pulse NMR and CPMG method ₂ ) And a soft component ratio at 30 ℃ determined by Solid Echo method using pulse NMR after exposure to a specific temperature condition is adjusted to a specific range. The present inventors have found that such a release film softens at high temperature during thermocompression bonding, and hardens to have an appropriate elastic modulus when peeled off after returning to normal temperature, and therefore exhibits excellent releasability and conformability to irregularities, and is less likely to cause resin bleed out, and have completed the present invention.

Relaxation time (T) of Soft component at 180 ℃ of Release film of the present invention measured by CPMG method by pulsed NMR ₂ ) The lower limit of (2) is 220 msec and the upper limit is 330 msec.

Here, "soft component" means: the data obtained by pulse NMR is divided into a high-crystallinity component, a low-crystallinity component, and a component having intermediate properties between them. Note that a component having high crystallinity is referred to as a "hard component", and a component having an intermediate property is referred to as an "intermediate component".

The "hard component" corresponds to a portion including intramolecular bonds or intermolecular bonds (for example, a crystal structure, a cross-linked structure, etc.), the "soft component" corresponds to an amorphous portion, and the "intermediate component" corresponds to a portion comparatively capable of molecular motion (for example, a folded portion of a crystal, etc.).

The division into the components is performed as follows: data (free induction decay curve) obtained by pulse NMR is analyzed by the least square method and divided into three parts, i.e., a "hard component" in which the magnetization immediately decays and a "soft component" in which the magnetization decays with time and the molecular mobility is high, and an "intermediate component" having a property intermediate between these components.

The "relaxation time" is the time for the electron spin to return from the excited state to the ground state after application of a magnetic field. A longer "relaxation time" means a higher molecular mobility.

If the above softening is carried out at 180 DEG CFractional relaxation time (T) ₂ ) When the temperature is 220 milliseconds or more, the molecular mobility of the soft component at high temperature during hot press bonding increases, and therefore the release film is sufficiently softened and can exhibit excellent conformability to unevenness. If the above relaxation time (T) of the soft component at 180 ℃ is set ₂ ) If the time is 330 milliseconds or less, the molecular mobility of the soft component becomes too high, and the resin bleed can be suppressed. Relaxation time (T) of the Soft component at 180 ℃ as described above ₂ ) With a preferred lower limit of 250 milliseconds and a preferred upper limit of 310 milliseconds, a more preferred lower limit of 270 milliseconds and a more preferred upper limit of 290 milliseconds.

Relaxation time (T) of the Soft component at 180 ℃ as described above ₂ ) For example, the following can be measured: using pulse NMR and analysis software (for example, TD-NMRA, BRUKER Co., ltd.) such as the minispec mq20 (BRUKER Co., ltd.), the temperature of the release film was raised from 30 ℃ to 180 ℃ at a rate of 10 ℃ per minute, and the temperature was maintained at 180 ℃ for 10 minutes, and then the measurement was carried out by the CPMG method, using the release film as a measurement sample.

The lower limit of the soft component ratio at 30 ℃ of the release film of the present invention measured by Solid Echo method using pulse NMR after exposure to the following temperature conditions was 0.1% and the upper limit was 15%.

[ temperature conditions ]

The temperature conditions are set on the assumption of a series of steps in which hot press bonding is usually performed at a high temperature of about 160 to 180 ℃ and then the release film is peeled off after returning to normal temperature. If the soft component ratio at 30 ℃ is in the above range, the crystallinity of the release film when the release film is once heated to a high temperature at the time of thermocompression bonding and then returned to normal temperature is sufficiently increased, and therefore the release film has an appropriate elastic modulus and can exhibit excellent releasability. The lower limit of the soft component ratio at 30 ℃ is preferably 1%, the upper limit is preferably 10%, the lower limit is more preferably 3%, and the upper limit is more preferably 5%.

As the soft component ratio at 30 ℃ as described above, pulse NMR and analysis software such as the minispec mq20 (manufactured by BRUKER Co., ltd.) can be used (for example)Such as TD-NMRA, manufactured by BRUKER, etc.). More specifically, the release film may be used as a measurement sample, and the temperature may be raised from 30 ℃ to 180 ℃ at a temperature raising rate of 10 ℃/min, maintained at 180 ℃ for 10 minutes, then lowered from 180 ℃ to 30 ℃ at a temperature lowering rate of 10 ℃/min, maintained at 30 ℃ for 10 minutes, and then measured by the Solid Echo method. The soft component ratio at 30 ℃ may be measured by measuring the relaxation time (T) of the soft component at 180 ℃ as described above ₂ ) The measurement of (3) is continued.

The CPMG method and the Solid Echo method are both one of irradiation conditions of electromagnetic wave pulses in pulse NMR. The measurement method is generally selected according to the length of the relaxation time, and the Solid Echo method is applied when measurement is intended with attention paid to a component having a short relaxation time, and the CPMG method is applied when measurement is intended to include a component having a long relaxation time.

The relaxation time (T) of the soft component at 180 ℃ is measured ₂ ) The method for adjusting the molecular mobility to the above range is not particularly limited, and a method using a resin having a smaller intermolecular interaction at 180 ℃ and a higher molecular mobility as a resin constituting the release film is preferable. More specifically, there may be mentioned: as described later, a method of using a polyolefin resin having a linear structure as a resin constituting the cushion layer. Examples of the resin constituting the buffer layer include a resin having a small molecular weight, a nonpolar polymer, and a resin having no unsaturated bond.

The method for adjusting the soft component ratio at 30 ℃ to the above range is not particularly limited, and is preferably: a method of promoting crystallization at the time of returning to normal temperature after heating to a high temperature at the time of thermocompression bonding. More specifically, there may be mentioned: a method of adding a nucleating agent to the buffer layer as described later. Further, there may be mentioned: a method of adjusting cooling conditions, a method of controlling the stereoregularity of a resin constituting the cushion layer, a method of combining a resin having a high crystallinity and a resin having a low crystallinity in the cushion layer, and the like.

The structure of the release film of the present invention is not particularly limited, and the release film may have a single-layer structure or a multilayer structure, and preferably has a release layer and a buffer layer. Further, it is more preferable to have a release layer on both sides of the cushion layer.

The release layer functions to impart excellent releasability to the release film. Further, the inclusion of the buffer layer improves the ability of the release film to follow irregularities. By forming a release film having the release layer and the buffer layer and having the release layer on both sides of the buffer layer, the relaxation time (T) of the soft component at 180 ℃ can be easily adjusted ₂ ) And the soft component ratio at 30 ℃ is adjusted to the above range, the mold release film can exhibit more excellent mold release properties and followability to irregularities.

The release layers on both sides may have the same resin composition or different resin compositions. The release layers on both sides may be the same thickness or different thicknesses. The release layer and the cushion layer may be integrated in direct contact with each other or integrated via an adhesive layer.

The resin constituting the release layer is not particularly limited, and preferably at least 1 resin selected from the group consisting of polyesters, polyolefins, and polystyrenes, from the viewpoint of improving the releasability of the release film.

The polyester preferably contains an aromatic polyester resin. The polyolefin preferably contains poly (4-methyl-1-pentene) or an alicyclic olefin resin. The polystyrene preferably contains a polystyrene resin having a syndiotactic structure. Among them, the release layer more preferably contains an aromatic polyester resin in view of excellent followability to unevenness and excellent bleeding prevention property of an adhesive formed on a cover film.

In the case of using the resins exemplified here, the release layer becomes relatively hard, and therefore it is considered that the release layer monomer (single layer) contains almost no soft component at 30 ℃.

The aromatic polyester resin is not particularly limited, and a crystalline aromatic polyester resin is preferable. Specific examples thereof include polyethylene terephthalate resins, polybutylene terephthalate resins, polyhexamethylene terephthalate resins, polyethylene naphthalate resins, polybutylene terephthalate polytetramethylene glycol copolymers, and the like. These aromatic polyester resins may be used alone, or 2 or more of them may be used in combination. Among them, polybutylene terephthalate resins are preferred from the viewpoint of a balance among heat resistance, mold releasability, conformability to irregularities, and the like.

Further, a mixed resin in which a block copolymer of polybutylene terephthalate and aliphatic polyether is mixed with polybutylene terephthalate resin is also preferable. The aliphatic polyether is not particularly limited, and examples thereof include polyethylene glycol, polydiethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

The aromatic polyester resin preferably has a melt volume flow rate of 30cm from the viewpoint of film-forming properties of the film ³ Less than 10min, more preferably 20cm ³ Less than 10 min. The melt volume flow rate was measured at a measurement temperature of 250 ℃ under a load of 2.16kg in accordance with ISO 1133.

Examples of commercially available products of the aromatic polyester resin include "PELPRENE (registered trademark)" (manufactured by Toyo Boseki Co., ltd.), "Hytrel (registered trademark)" (manufactured by Toray DuPont Co., ltd.), "DURANEX (registered trademark)" (manufactured by polyplastic Co., ltd.), "NOVADURAN (registered trademark)" (manufactured by Mitsubishi Engineering Plastics Co., ltd.).

The polyolefin containing poly (4-methyl-1-pentene) preferably contains at least 90% by weight of a poly (4-methyl-1-pentene) resin.

As the poly (4-methyl-1-pentene) resin, commercially available products such as TPX (registered trademark) manufactured by Mitsui chemical company, for example, can be used.

The alicyclic olefin resin is an olefin resin having a cyclic aliphatic hydrocarbon in the main chain or side chain, and a thermoplastic saturated norbornene resin is preferable from the viewpoint of heat resistance, strength, and the like.

Examples of the thermoplastic saturated norbornene-based resin include: a resin obtained by hydrogenating a ring-opened polymer or a ring-opened copolymer of norbornene monomers (modified by maleic acid addition or cyclopentadiene addition, if necessary). Further, there may be mentioned: resins obtained by addition polymerization of norbornene monomers, resins obtained by addition polymerization of norbornene monomers and olefin monomers such as ethylene or α -olefin, and resins obtained by addition polymerization of norbornene monomers and cyclic olefin monomers such as cyclopentene, cyclooctene, 5, 6-dihydrodicyclopentadiene, and the like. Further, modified products of these resins are also included.

The polystyrene containing the polystyrene resin having a syndiotactic structure preferably contains 70 to 90% by weight of the polystyrene resin having a syndiotactic structure.

The polystyrene-based resin having a syndiotactic structure means: a resin having a syndiotactic structure, that is, a steric regular structure in which phenyl groups and substituted phenyl groups as side chains are alternately located in opposite directions with respect to a main chain formed of a carbon-carbon sigma bond.

The polystyrene resin having a syndiotactic structure is not particularly limited. Examples thereof include polystyrene, poly (alkylstyrene), poly (arylstyrene), poly (halostyrene), poly (haloalkylstyrene), poly (alkoxystyrene), poly (vinylbenzoate) and the like having a syndiotactic tacticity of 75% or more in the racemic diad group (japanese: 12521124751245046. Further, hydrogenated polymers thereof, mixtures thereof, copolymers containing these as the main component, and the like can be mentioned. As the polystyrene resin having a syndiotactic structure, commercially available products such as XAREC (registered trademark) (124701252483\\ 12463.

The release layer may contain a rubber component. By containing a rubber component in the release layer, the following property of the release film to the unevenness is improved.

The rubber component is not particularly limited, and examples thereof include natural rubber, styrene-butadiene copolymer, polybutadiene, polyisoprene, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer (EPM, EPDM), polychloroprene, butyl rubber, acrylic rubber, silicone rubber, urethane rubber, and the like. Examples of the rubber component include olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers.

The release layer may contain a stabilizer.

The stabilizer is not particularly limited, and examples thereof include hindered phenol antioxidants, heat stabilizers and the like.

The hindered phenol antioxidant is not particularly limited, and examples thereof include: 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-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 ] undecane, and the like. The heat stabilizer is not particularly limited, and examples thereof include: tris (2, 4-di-t-butylphenyl) phosphite, trilauryl phosphite, 2-t-butyl- α - (3-t-butyl-4-hydroxyphenyl) -p-cumylbis (p-nonylphenyl) phosphite, dimyristyl 3,3' -thiodipropionate, distearyl 3,3' -thiodipropionate, pentaerythritol tetrakis (3-laurylthiopropionate), ditridecyl 3,3' -thiodipropionate and the like.

The release layer may further contain conventionally known additives such as fibers, inorganic fillers, flame retardants, ultraviolet absorbers, antistatic agents, inorganic substances, and higher fatty acid salts.

The thickness of the release layer is not particularly limited, and the contribution of the buffer layer to the entire release film can be increased and the soft component ratio can be increased by relatively decreasing the thickness of the release layer and increasing the thickness of the buffer layer. Thus, the release film can exhibit more excellent followability to the unevenness. The lower limit of the thickness of the release layer is preferably 10 μm, and the upper limit is preferably 40 μm. When the thickness of the release layer is 10 μm or more, the heat resistance of the release film is improved. When the thickness of the release layer is 40 μm or less, the following property of the release film to the unevenness is improved. A more preferable lower limit and a more preferable upper limit of the thickness of the release layer are 15 μm and 30 μm, respectively.

The resin constituting the cushion layer is not particularly limited, and a polyolefin resin is preferable.

The polyolefin resin is not particularly limited, and examples thereof include polyethylene resins (e.g., high-density polyethylene, low-density polyethylene, and linear low-density polyethylene), polypropylene resins, and ethylene-vinyl acetate copolymers. Further, ethylene-acrylic acid monomer copolymers such as ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-acrylic acid copolymers may be mentioned. These polyolefin resins may be used alone, or 2 or more kinds may be used in combination. Among these, polyethylene resins are preferred in that a release film exhibiting more excellent releasability and conformability to unevenness can be obtained.

The polyolefin resin preferably contains a polyolefin resin having a linear structure.

Specifically, for example, when the polyolefin resin contains the polyethylene resin, it is preferable to use High Density Polyethylene (HDPE) having a linear structure in an appropriate blending amount in addition to Low Density Polyethylene (LDPE) having a large number of branches which has been conventionally used for a cushion layer. Thereby, the relaxation time (T) of the soft component at 180 ℃ can be easily adjusted ₂ ) When the amount is adjusted to the above range, the release film can exhibit more excellent conformability to unevenness. This is because High Density Polyethylene (HDPE) having a linear structure has a smaller intermolecular interaction at a temperature not lower than the melting point and has a higher molecular mobility than Low Density Polyethylene (LDPE) having many branches.

Further, high Density Polyethylene (HDPE) having a linear structure is likely to form a crystal structure when cooled to a temperature equal to or lower than the melting point and returned to normal temperature, and the crystallinity can be improved. Therefore, by using High Density Polyethylene (HDPE), the soft component ratio at 30 ℃ can be easily adjusted to the above range, and the release film can exhibit more excellent releasability.

The content of the polyolefin resin having a linear structure in the cushion layer is not particularly limited, and the relaxation time of the soft component at 180 ℃ is adjusted(T ₂ ) From the viewpoint of adjusting the soft component ratio at 30 ℃ to the above range, the lower limit is preferably 5% by weight, and the upper limit is preferably 25% by weight. When the content of the polyolefin resin having a linear structure is 5% by weight or more, the release film easily exhibits more excellent releasability and conformability to unevenness. If the content of the polyolefin resin having a linear structure is 25 wt% or less, the occurrence of resin bleeding due to excessively high molecular mobility of the soft component can be further suppressed. A more preferable lower limit of the content of the polyolefin resin having a linear structure is 10 wt%, a more preferable upper limit is 20 wt%, and a further more preferable lower limit is 15 wt%.

The content of the polyolefin resin in the cushion layer is not particularly limited, and the lower limit is preferably 50% by weight, and the upper limit is preferably 90% by weight. When the content of the polyolefin resin is 50% by weight or more, the flexibility of the cushion layer becomes sufficient, and the following property of the release film to the unevenness is improved. When the content of the polyolefin resin is 90% by weight or less, the adhesion between the release layer and the cushion layer is improved. A more preferable lower limit of the content of the polyolefin resin is 60 wt%, and a further more preferable lower limit is 65 wt%. A more preferable upper limit of the content of the polyolefin resin is 80 wt%, and a further more preferable upper limit is 75 wt%.

The cushion layer may contain a resin constituting the release layer. By incorporating the resin constituting the release layer into the cushion layer, the adhesion between the release layer and the cushion layer is improved. The cushion layer more preferably contains a main component resin of the release layer. Here, the main component resin of the release layer is a resin having the largest content among resins contained in the release layer.

The content of the resin constituting the release layer in the cushion layer is not particularly limited, and a preferable lower limit is 10 wt%, and a preferable upper limit is 50 wt%. When the content of the resin constituting the release layer is 10% by weight or more, the adhesion between the release layer and the cushion layer is improved. When the content of the resin constituting the release layer is 50 wt% or less, the cushion layer has sufficient flexibility, and the following property of the release film to the unevenness is improved. A more preferable lower limit of the content of the resin constituting the release layer is 20 wt%, and a still more preferable lower limit is 25 wt%. A more preferable upper limit of the content of the resin constituting the release layer is 40 wt%, and a further more preferable upper limit is 35 wt%.

The buffer layer may further contain a resin such as polystyrene, polyvinyl chloride, polyamide, polycarbonate, polysulfone, or polyester.

The above buffer layer preferably further contains a nucleating agent.

By including the nucleating agent in the buffer layer, crystallization of the resin constituting the buffer layer is promoted when the buffer layer is temporarily heated to a high temperature at the time of thermocompression bonding and then returned to normal temperature. This makes it easy to adjust the soft component ratio at 30 ℃ to the above range, and the release film can exhibit more excellent releasability.

The nucleating agent is not particularly limited as long as it is a compound that promotes crystallization of the polymer compound. Examples of the nucleating agent for the polypropylene resin include: phosphoric ester metal salts, carboxylic acid metal salt-based nucleating agents, pimelic acid metal salts, rosin metal salts, sorbitol-based nucleating agents, quinacridones, phthalocyanine blues, talcs, and the like.

Examples of the metal carboxylate nucleating agent include sodium benzoate, aluminum dibenzoate, and potassium benzoate. Examples of the sorbitol-based nucleating agent include dibenzylidene sorbitol and dialkyl-benzylidene sorbitol.

Further, examples of the nucleating agent for the polyethylene resin include: cyclohexane-1, 2-dicarboxylate, anthracene, potassium hydrogen phthalate, a benzoic acid-based compound, ultrahigh molecular weight polyethylene, a phosphate metal salt, talc, calcium carbonate, titanium dioxide, silica, barium sulfate, vermiculite, carbon nanotubes, and the like.

The content of the nucleating agent in the buffer layer is not particularly limited, and a preferable lower limit is 0.5 wt%, a preferable upper limit is 5 wt%, a more preferable lower limit is 1 wt%, and a more preferable upper limit is 3 wt%. When the content of the nucleating agent is 1% by weight or more, the release film can exhibit more excellent releasability. If the content of the nucleating agent is 3 wt% or less, the occurrence of bleeding of the resin can be suppressed while maintaining the flexibility of the cushion layer. A more preferable lower limit of the content of the nucleating agent is 1.5 wt%, and a more preferable upper limit is 2 wt%.

The buffer layer may further contain additives such as fibers, inorganic fillers, flame retardants, ultraviolet absorbers, antistatic agents, inorganic substances, and higher fatty acid salts. Wherein the buffer layer contains the inorganic filler, whereby the relaxation time (T) of the soft component at 180 ℃ is prevented ₂ ) And the above soft component ratio at 30 ℃ adversely affect the resin bleed-out and can be further suppressed.

The buffer layer may have a single-layer structure composed of a single layer or a multilayer structure composed of a laminate of a plurality of layers. When the cushion layer has a multilayer structure, a plurality of layers may be stacked and integrated via an adhesive layer.

The thickness of the buffer layer is not particularly limited, and the contribution of the buffer layer to the entire release film can be increased and the soft component ratio can be increased by making the thickness of the release layer relatively thin and making the thickness of the buffer layer relatively thick. This allows the release film to exhibit more excellent conformability to irregularities.

The lower limit of the buffer layer is preferably 15 μm, and the upper limit is preferably 200 μm. When the thickness of the buffer layer is 15 μm or more, the following property of the release film to the unevenness is improved. If the thickness of the cushion layer is 200 μm or less, the resin can be prevented from bleeding out of the cushion layer, which is generated at the film end during the hot press bonding. A more preferable lower limit and a more preferable upper limit of the thickness of the buffer layer are 30 μm and 150 μm, respectively.

The method for producing the release film of the present invention is not particularly limited, and examples thereof include: water-cooled or air-cooled co-extrusion blow molding, a method of forming a film by a co-extrusion T-die method, a solvent casting method, a hot press molding method, and the like.

In the case of the structure having the release layer on both sides of the buffer layer, examples thereof include: a method in which a film to be one release layer is produced, a buffer layer is laminated on the film by an extrusion lamination method, and then the other release layer is dry-laminated. Further, there may be mentioned: a method of dry laminating a film to be one release layer, a film to be a buffer layer, and a film to be the other release layer.

Among these, a method of forming a film by a coextrusion T-die method is preferable in terms of excellent control of the thickness of each layer.

The use of the release film of the present invention is not particularly limited, and the release film can be suitably used in the production process of a printed wiring board, a flexible circuit board, a multilayer printed wiring board, and the like. Specifically, for example, in the production process of a flexible circuit board, the release film of the present invention can be used when a cover film is thermocompression bonded to a flexible circuit board main body on which a copper circuit is formed via a thermosetting adhesive or a thermosetting adhesive sheet.

Effects of the invention

According to the present invention, a mold release film which is excellent in both mold release properties and conformability to irregularities and is less likely to cause resin bleeding can be provided.

Detailed Description

The mode of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(example 1)

(1) Production of Release film

A resin composition for a mold release layer was obtained by mixing 60 parts by weight of a polybutylene terephthalate resin (PBT) and 40 parts by weight of a copolymer of polybutylene terephthalate and polytetramethylene glycol (PBT/PTMG copolymer).

39 parts by weight of Low Density Polyethylene (LDPE) (SUNTEC-LD (M2102), manufactured by asahi chemicals corporation), 59.5 parts by weight of ethylene-methyl methacrylate copolymer (EMMA 1) (ACRYFT WH401, manufactured by sumitomo chemical corporation) and 1.5 parts by weight of PE nucleating agent (Rikemaster (japanese: 1252212412412512510, 12412412412479) CN, manufactured by mitamin corporation), to obtain a resin composition for a buffer layer.

The obtained resin composition for a release layer and the obtained resin composition for a buffer layer were subjected to three-layer coextrusion using an extruder at a T-die width of 400mm, thereby obtaining a release film having release layers (thickness of 15 μm on one side) on both sides of a buffer layer (thickness of 90 μm). The extruder used GM30-28 manufactured by GM ENGINEERING corporation, and the screw diameter was 30mm and L/D28.

(2) Pulsed NMR measurement

About 10g of a mold release film as a measurement sample was wound in a roll shape and introduced into a glass sample tube (product No. 1824511, length 180mm, flat bottom, manufactured by BRUKER Co.) having a diameter of 10mm so as to have a height of 20 mm.

The release film in the sample tube was heated from 30 ℃ to 180 ℃ at a heating rate of 10 ℃/min using pulse NMR "the minispec mq20" (manufactured by BRUKER Co., ltd.), and maintained at 180 ℃ for 10 minutes, and then the relaxation time (T.sub.m.) of the soft component at 180 ℃ was determined by the CPMG method ₂ )。

[ measurement conditions of CPMG method ]

And (4) Scans:128 times

Recycle Deray：2sec

90-180plus searation：0.05

Total number of acquired echoes：3000

Further, the soft component ratio at 30 ℃ was determined by using pulse NMR "the minispec mq20" (manufactured by BRUKER). More specifically, the mold release film in the sample tube was heated from 30 ℃ to 180 ℃ at a heating rate of 10 ℃/min, maintained at 180 ℃ for 10 minutes, then cooled from 180 ℃ to 30 ℃ at a cooling rate of 10 ℃/min, maintained at 30 ℃ for 10 minutes, and then the soft component ratio at 30 ℃ was determined by the Solid Echo method.

[ measurement conditions of Solid Echo method ]

And (4) Scans:64 times

Recycle Deray：2sec

Acquisition scale：1ms

Relaxation time (T) of soft component at 180 ℃ based on CPMG method ₂ ) And the soft component ratio at 30 ℃ based on the Solid Echo method were calculated by the following method.

Will be used as pulseObtained by measuring results of impact NMR ¹ The free induction decay curve (vertical axis: magnetization, horizontal axis: time) waveform of the spin-spin relaxation of H nuclei is separated into 3 curves from 3 kinds of components of soft component, intermediate component and hard component, and the component ratio and relaxation time of the soft component, intermediate component and hard component are determined. Waveform separation was performed by using and fitting both gaussian and exponential types (japanese: 1245612463124731250912540124125124931251247112515. Specifically, the hard component was fitted to the hard component using a gaussian model, and the intermediate component and the soft component were fitted to each other using an exponential model in the Solid Echo method at 30 ℃ according to the product manual using the analysis software "TD-NMRA (Version 4.3 Rev 0.8)" manufactured by BRUKER. In the CPMG method at 180 ℃, fitting is performed using an exponential type for all of the hard component, the intermediate component and the soft component. In addition, the Solid Echo method is adapted by using points of the obtained free induction decay curve (relaxation curve) up to 0.5 msec, and the CPMG method is adapted by using all the points. The fitting was performed by the least squares method using the following formula.

[ mathematical formula 1]

Here, Y is a free induction decay curve, and w1, w2, and w3 are weibull coefficients. The Solid Echo method takes w1 as 2, w2 and w3 as 1, and the CPMG method takes w1 to w3 as 1. A1 is the component ratio of the hard component (unit:%), B1 is the component ratio of the intermediate component (unit:%), and C1 is the component ratio of the soft component (unit:%), so that A1+ B1+ C1=100 is satisfied. T2A is a relaxation time (unit: millisecond) of the hard component, T2B is a relaxation time (unit: millisecond) of the intermediate component, and T2C is a relaxation time (unit: millisecond) of the soft component, and T2A < T2B < T2C is satisfied. T is time (unit: millisecond).

In the examples of the present invention, the value of the Recycle route was set to 2sec, but when an appropriate measurement result (relaxation curve) was not obtained, T was set to ₁ A value of 5 times (spin-lattice relaxation time; longitudinal relaxation time). At T ₁ In the assay, the saturation recovery method (Japanese: 39165and Selaginella) and the inverse recovery method (Japanese: selaginella) are usually applied.

(examples 2 to 5 and comparative examples 1 to 6)

A release film was obtained in the same manner as in example 1, except that the composition of the buffer layer was changed as shown in table 1. The materials shown in table 1 are as follows.

High Density Polyethylene (HDPE) (SUNTEC-HD (F371), manufactured by Asahi Kasei corporation)

EMMA2 (ACRYFT WD106, manufactured by Sumitomo chemical Co., ltd.)

< evaluation >

The following evaluations were made with respect to the release films obtained in examples and comparative examples. The results are shown in Table 1.

(1) Evaluation of mold releasability

The release film was laminated on an epoxy adhesive sheet (CISV 2535 manufactured by NIKKAN INDUSTRIES Inc.) at 180 ℃ and 30kgf/cm ² Hot pressing for 5 minutes under the condition of (1). Then, the sheet was cut into a width of 25mm, and a peel test was performed at a test speed of 500 mm/min and a peel angle of 180 °. The peel strength was 20gf/cm ² The following cases are indicated as O, and the air pressure exceeds 20gf/cm ² And 30gf/cm ² The following is x, and the average value is more than 30gf/cm ² Is set to xxx.

(2) Evaluation of followability to unevenness

A cover film (12.5 cm × 12.5cm, polyimide thickness 25 μm, epoxy adhesive layer thickness 35 μm) having a hole of Φ =1mm was laminated on the copper foil surface of a Copper Clad Laminate (CCL) (12.5 cm × 12.5cm, polyimide thickness 25 μm, copper foil thickness 35 μm) in contact with the epoxy adhesive layer. Further, a release film is laminated on the cover film. The laminate was heated at 180 ℃ and 30kgf/cm ² Hot pressing for 2 minutes under the condition of (1). Then, the release film was peeled off, and the epoxy adhesive flowing out of the Copper Clad Laminate (CCL) was observed with an optical microscope. The bleeding width of the epoxy adhesive at 12 points was measured, and the average value thereof was calculated to evaluate the followability of the release film to irregularities. The average value of the bleed width of the epoxy adhesive was set to be less than 55 μm, and the value was set to be 55 μm or lessA value of 65 μm or less is shown as "A", and a value exceeding 65 μm is shown as "X".

(3) Evaluation of resin bleed-out

The release film was cut into 10cm squares. A25 cm square SUS plate, a cushion paper, a SiPET sheet, a release film, a SiPET sheet, a cushion paper, and a 25cm square SUS plate were sequentially laminated, and hot-pressed by a slide type vacuum heater press (MKP-3000 v-MH-ST, manufactured by MIKADO TECHNOS). The distance between the end of the resin constituting the cushion layer that bleeds out from the release film and the end of the release layer of the release film was measured as a bleeding distance. The bleeding distance was evaluated to be good, the value exceeding 1mm and 2mm or less was evaluated to be Δ, and the value exceeding 2mm was evaluated to be x.

Industrial applicability

Claims

1. A mold release film characterized by a relaxation time T of a soft component at 180 ℃ measured by CPMG method using pulsed nuclear magnetic resonance ₂ Is 220 milliseconds or more and 330 milliseconds or less, and,

the mold release film has a soft component ratio at 30 ℃ of 0.1% or more and 15% or less as measured by a solid echo method using pulsed nuclear magnetic resonance after exposure to the following temperature conditions,

[ temperature conditions ]

The temperature is raised from 30 ℃ to 180 ℃ at a temperature raising speed of 10 ℃/min, and then the temperature is lowered from 180 ℃ to 30 ℃ at a temperature lowering speed of 10 ℃/min.

2. The release film of claim 1, having a release layer and a buffer layer, the release layer being provided on both sides of the buffer layer.

3. The release film of claim 2, wherein the cushion layer comprises a polyolefin resin.

4. The release film of claim 3, wherein the polyolefin resin comprises a polyethylene resin.

5. The release film according to claim 3 or 4, wherein the polyolefin resin contains a polyolefin resin having a linear structure.

6. The release film of claims 2, 3, 4 or 5, wherein the buffer layer contains a nucleating agent.

7. The release film according to claim 1,2, 3, 4, 5 or 6, wherein the release layer contains at least 1 resin selected from the group consisting of polyester, polyolefin and polystyrene.