TWI478811B - Release film - Google Patents

Description

Release film

The present invention relates to a release film, and more particularly to a release film used in the manufacture of a printed substrate. In particular, it relates to a release film which is useful when a cover film is bonded to a printed circuit board having a precise pattern by a thermosetting adhesive at a high temperature.

Release films are widely used in the industry. In particular, in a manufacturing step of a printed circuit board, a flexible printed circuit board, or a multilayer printed circuit board, when a copper foil laminate or a copper foil is hot-pressed via a prepreg or a heat-resistant film, it can be used to prevent a prepreg. Or the heat resistant film is adhered to the hot plate. Further, in the manufacturing step of the flexible printed circuit board, when the flexible printed circuit board body forming the electrical circuit is thermally pressure-bonded to the cover film by the thermosetting adhesive, it can be used to prevent the cover film from adhering to the hot plate.

The release film of the above-mentioned application may, for example, be a fluorine-based film, a polyoxymethylene-coated polyethylene terephthalate film, a polymethylpentene film or a polypropylene film.

However, the fluorine-based film which has been used as a release film in the past is excellent in heat resistance, release property, and non-contamination property, but it is difficult to burn and is toxic in waste burnt treatment after use except expensive. The problem of gas still exists. Further, the polyoxymethylene-coated polyethylene terephthalate film or the polymethylpentene film contains polyfluorene or a low molecular weight in the film composition, and thus moves on a printed circuit board, particularly a substrate. The copper circuit causes pollution, damage and quality. Further, the polypropylene film is inferior in heat resistance and insufficient in release property.

Therefore, it is possible to remove the burnt release film by improving the flexibility, heat resistance, release property, and non-contamination property, and it is known to contain, for example, a polypropylene resin and a buffer of a vinyl aromatic elastomer. A film of a release layer composed of a crystalline aromatic polyester is laminated on both sides of the layer (Patent Document 1). Further, a film of a polybutylene terephthalate, a polytrimethylene terephthalate, a polybutylene terephthalate, and a polyether as a release layer has been disclosed (Patent Document 2). Or such a film as a buffer layer (Patent Document 3).

In the laminated cosmetic sheet which is excellent in heat resistance and moldability, a film in which an amorphous polyester resin and a crystalline polyester resin are blended or laminated is disclosed (Patent Document 4, Patent Document 5).

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-049504

[Patent Document 2] International Publication No. 05/002850

[Patent Document 3] Japanese Patent No. 4099355

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2003-231761

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2008-162058

However, in such a technique, when the release property, the heat resistance, and the flexibility are not sufficiently obtained, the release property and the heat resistance are emphasized, the sacrificial flexibility is obtained, and the embedding property of the printed circuit board having a precise pattern is inferior. In addition, when the flexibility is emphasized, in addition to the deterioration of the release property or the deterioration of the slipperiness of the film surface, the elastic modulus is low, so that the film is stretched or wrinkled during the winding or cutting, and the comprehensive handling property is poor. .

For example, the film described in Patent Document 1 is excellent in release property and embedding property. However, since the melting point of the buffer layer resin is low, heat resistance is insufficient. Therefore, there is a problem that the buffer layer oozes from the end portion of the film during hot pressing or contaminates the printed circuit board due to the movement of the low molecular weight body.

In the technique of Patent Document 2 and Patent Document 3, since the soft copolymerized polybutylene terephthalate is used for the purpose of improving the embedding property, it is excellent in release property and non-contamination property. However, polybutylene terephthalate is used for the inner layer or the outer layer, and the hardness thereof is inferior to the polymethylpentene film used in the prior art.

In the techniques of Patent Document 4 and Patent Document 5, the amorphous polyester resin is blended in the crystalline polyester resin for the purpose of improving the moldability of the cosmetic sheet. Therefore, the embedding property is excellent. However, since the surface layer resin is not actively crystallized by paying attention to moldability, there is a problem of poor heat resistance or release property at the time of high-temperature hot pressing of the use of the present invention.

The present invention solves the aforementioned problems of the prior art, and an object thereof is to provide an excellent property of flexibility, release property, heat resistance, and non-contamination property, and in particular, good embedding property for a printed circuit board having a precise pattern, and a sheet A release film that is excellent in workability when being taken up or cut.

In order to solve the above-mentioned problems, the inventors of the present invention have concentrated on the polyester elastomer of the surface layer by laminating a polyester elastomer having a specific crystallinity and a polyester having a glass transition temperature higher than that. By imparting the release property, the crystallinity of the polyester of the inner layer of the crystalline resin is adjusted to a specific range, and it is found that the burying property and the non-bleeding property at the time of hot pressing at a high temperature can be reversed. The present invention has been completed. Further, in the present invention, the high-temperature hot pressing is a press working using a hot plate heated to 100 ° C or higher. That is, the gist of the present invention is as follows.

(1) A release film characterized by having a polyester-based elastomer (A) layer disposed on a surface layer, and a polyester (B) layer, and a polyester-based elastomer (A)-based glass transition temperature of 0 to 20 ° C and the crystallization rate index is 20 to 50 ° C, polyester (B) contains crystalline aromatic polyester (B1) and 1,4-cyclohexane dimethanol copolymerized polyethylene terephthalate ( B2), the mass ratio (B1) / (B2) is in the range of 5/95 to 50/50, and the polyester (B) system has a glass transition temperature of 40 to 80 ° C and a heat of crystal fusion of 5 to 40 J/g.

(2) The release film polyester elastomer (A) according to (1) has a glass transition temperature of 3 to 12 ° C and a crystallization rate of 25 to 48 ° C, and a crystalline aromatic in the polyester (B) The mass ratio (B1)/(B2) of the copolymerized polyester (B1) to 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate (B2) is in the range of 10/90 to 50/50. The polyester (B)-based glass has a glass transition temperature of 50 to 73 ° C and a heat of crystal fusion of 8 to 35 J/g.

(3) The release film of (1) or (2), wherein the polyester elastomer (A) is a block copolymer of polybutylene terephthalate and polyether.

(4) The release film of any one of (1) or (3), wherein the crystalline aromatic polyester (B1) is polybutylene terephthalate or polytrimethylene terephthalate Any of polyethylene terephthalate or isophthalic acid copolymerized polyethylene terephthalate or a mixture of two or more thereof.

The release film of any one of (1) or (4), wherein the laminated film is composed of two types of (A)/(B)/(A), or (A) / (B) 2 kinds of 2 layers.

[Formation for implementing the invention]

Hereinafter, the present invention will be described in detail.

The release film of the present invention has a polyester-based elastomer (A) layer disposed on the surface layer and a laminated film with the polyester (B) layer.

<Polyester Elastomer (A)>

The polyester elastomer (A) layer is disposed on the surface layer of the release film to exhibit a release layer function. If there is no polyester elastomer (A) layer, the release property during hot pressing is lowered. For example, in the hot pressing step of the laminate using the cover film, the film is easily peeled off and adhered to the laminate or the hot plate. The membrane, which is contaminated.

The polyester elastomer (A) is exemplified by a block copolymer of a high melting point crystalline segment and a low melting point segment. The high melting point crystalline segment is mainly composed of a crystalline aromatic polyester unit, and the low melting point segment is composed of an aliphatic polyether unit and/or an aliphatic polyester unit.

The copolymerization ratio of the high-melting-point crystalline segment and the low-melting-point segment in the polyester-based elastomer (A) is selected in addition to the monomers constituting each segment to satisfy the melting point, glass transition temperature, and crystallization rate which will be described later. The range of heat of crystal melting is determined, and is not particularly limited. However, it is preferable that the polyester elastomer (A) contains 5 to 50% by mass of the low melting point segment.

In the polyester elastomer (A), the crystalline aromatic polyester constituting the high melting point crystalline segment is preferably a polyester formed of an aromatic dicarboxylic acid component and an aliphatic diol component. Specifically, from the viewpoint of heat resistance or high crystallinity, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polytrimethylene terephthalate (PTT) are preferable. ).

A polyester obtained from an aromatic dicarboxylic acid component or a diol component as described below may be used as the crystalline aromatic polyester in addition to the above-mentioned PET, PBT, and PTT. Further, such a crystalline aromatic polyester may be copolymerized with any of PET, PBT, and PTT.

Examples of the aromatic dicarboxylic acid component include isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and diphenyl-4,4'-dicarboxylate. An acid, a diphenoxyethane dicarboxylic acid, a 5-sulfoisophthalic acid, or an ester-forming derivative thereof.

The diol component is preferably a diol having a molecular weight of 300 or less. Examples thereof include aliphatic diols such as ethylene glycol, propylene glycol, pentanediol, hexanediol, neopentyl glycol, and decanediol; 1,4-cyclohexanedimethanol, tricyclodecane dimethylol, and the like. Alicyclic diol; xylene diol, bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl] Propane, bis[4-(2-hydroxy)phenyl]anthracene, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 4,4'-dihydroxy-para-triphenyl An aromatic diol such as a 4,4'-dihydroxy-p-tetraphenyl group or the like. These dicarboxylic acid components and diol components may be used in combination of two or more kinds.

The crystalline aromatic polyester may be a copolymer of a trifunctional or higher polyfunctional carboxylic acid component, a polyfunctional hydroxy acid component, a polyfunctional hydroxy component, or the like in a range of 5 mol% or less.

In the polyester elastomer (A), the aliphatic polyether constituting the low melting point segment may, for example, be a poly(ethylene oxide) glycol, a poly(propylene oxide) glycol, or a poly(butylene oxide). Glycol, poly(ethylene oxide) diol, copolymer of ethylene oxide and propylene oxide, ethylene oxide addition polymer of poly(propylene oxide) diol, ethylene oxide and tetrahydrofuran Copolymers, etc. Examples of the aliphatic polyester constituting the low melting point segment include poly(ε-caprolactone), polydecalactone, polyvalerolactone, polybutylene adipate, and polyethylene adipate. Among these aliphatic polyethers and/or aliphatic polyesters, the elastic properties of the obtained polyester block copolymer are preferably poly(butylene oxide) glycol or poly(propylene oxide) glycol. The ethylene oxide adduct, poly(ε-caprolactone), polybutylene adipate, polyethylene adipate or the like is particularly preferably poly(butylene oxide) glycol. Further, the number average molecular weight of the low melting point segments is preferably from about 300 to about 6,000 in the state of copolymerization.

The glass transition temperature of the polyester elastomer (A) must be 0 to 20 °C. When the glass transition temperature is lower than 0 ° C, the release property and the heat resistance at the time of hot pressing are inferior, and further, the film forming workability is also lowered. If it exceeds 20 ° C, the embedding property is poor. The glass transition temperature of the polyester elastomer (A) is preferably from 0 to 15 °C.

The melting point of the polyester elastomer (A) is preferably 200 ° C or higher. If the melting point is lower than 200 ° C, the heat resistance at the time of hot pressing may be poor.

The polyester elastomer (A) must be sufficiently crystallized by a casting roll at the time of film formation. Therefore, the crystallization rate index of the polyester elastomer (A) must be 20 to 50 °C. The crystallization rate index is an index indicating the crystallization rate at the time of cooling of the polyester elastomer (A) after melting. When the crystallization rate index exceeds 50 ° C, that is, the crystallization rate at the time of cooling after melting is slow, the heat resistance at the time of forming a laminated film is difficult, and the crystallization process is directly performed by heating the laminated film by a roll. Poor peeling of the roll. When the crystallization rate index is within the above range, the resin can be crystallized by a cooling roll after being melted, and the crystal state of the sheet can be controlled by the temperature or speed of the casting roll. The crystallization rate index is preferably from 25 to 50 °C.

The polyester elastomer (A) preferably has a heat of crystal fusion of 25 to 45 J/g. When the thickness is less than 25 J/g, the heat resistance and the release property are insufficient, and if it exceeds 45 J/g, the embedding property is liable to lower.

A preferred configuration of the polyester-based elastomer (A) having the above crystallization characteristics is, for example, a block copolymer of polybutylene terephthalate and a polyether. The copolymerization amount of the polyether is preferably from 10 to 40% by mass, more preferably from 15 to 30% by mass. When the amount of copolymerization of the polyether is small, the softening effect is small, and if too much, the heat resistance or crystallinity is excessively lowered. In such a range, the melting point of the polyester elastomer (A), the glass transition temperature, the crystallization rate index, the heat of crystal melting, and the like can be easily adjusted.

The polyester elastomer (A) can be produced by a known method. For example, a method in which a lower alcohol diester of a dicarboxylic acid, an excessive amount of a low molecular weight diol, and a low melting point component are subjected to a transesterification reaction in the presence of a catalyst to obtain a condensation reaction of the obtained reaction product. Alternatively, a method in which a dicarboxylic acid, an excess amount of a diol, and a low-melting-point segment component are subjected to an esterification reaction in the presence of a catalyst to obtain a condensation reaction of the obtained reaction product. Further, for example, a method of preparing a high-melting-point crystalline segment in advance, adding a low-melting-point segment component, and randomizing it by a transesterification reaction may be mentioned. A method of connecting a high-melting-point crystalline segment and a low-melting-point segment to a chain linking agent is exemplified. Further, when poly(ε-caprolactone) is used in the low-melting-point segment, a method of adding an ε-caprolactone monomer to a high-melting-point crystalline segment may be mentioned. It can also be a method of either.

<Polyester (B)>

In the release film of the present invention, it is necessary to laminate a support layer of the polyester elastomer (A) layer which functions as a release layer, and a polyester (B) layer which is a buried layer which is hot pressed at a high temperature. . In the case of the non-layer (B), when the film is taken up by the roll during the production of the film, wrinkles are generated due to the fragile body of the film, and the film forming workability is remarkably lowered, which is industrially difficult to produce. Moreover, the embedding property at the time of hot pressing of high temperature is inadequate.

The component constituting the polyester (B) layer must be a crystalline aromatic polyester (B1) and a polyethylene terephthalate (B2) copolymerized with 1,4-cyclohexanedimethanol.

Mass ratio (B1)/(B2) of the crystalline aromatic polyester (B1) constituting the polyester (B) layer and 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate (B2) Must be in the range of 5/95 to 50/50, preferably in the range of 30/70 to 50/50. When the crystalline aromatic polyester (B1) is less than 5% by mass, the crystallinity of the layer (B) is too low, and the heat resistance at the time of high-temperature hot pressing tends to be lowered, and the (B) layer may be contaminated by oozing. section. When (B1) exceeds 50% by mass, the crystallinity of the layer (B) is too high, and the embedding property at the time of high-temperature hot stamping tends to be inferior.

The glass transition temperature of the polyester (B) must be 40 to 80 °C. When the glass transition temperature is lower than 25 ° C, the film is softened at room temperature, so that the sheet wrinkles during winding, and the handling property such as cutting property at the time of cutting becomes insufficient. Further, when the glass transition temperature exceeds 80 ° C, the softening of the film at the time of hot pressing becomes insufficient, so that the embedding property is poor. The glass (M) has a glass transition temperature of preferably 45 to 75 ° C, particularly preferably 50 to 70 ° C.

The heat of crystal melting of the polyester (B) must be 5 to 40 J/g. In such a range, the layer (B) can sufficiently exhibit the function of the support layer of the layer (A), and can have heat resistance and embedding property at the time of high-temperature hot pressing. When the heat of crystal melting is less than 5 J/g, since the crystallinity is too low, the heat resistance at the time of high-temperature hot pressing is poor, and the bleeding of the layer (B) may occur from the end portion of the film. Further, when the heat of crystal melting exceeds 40 J/g, the softening of the film at the time of high-temperature hot pressing becomes insufficient, so that the embedding property is poor. The heat of crystal melting of the polyester (B) is preferably from 10 to 35 J/g, particularly preferably from 15 to 30 J/g.

<Crystalline aromatic polyester (B1)>

The crystalline aromatic polyester (B1) may, for example, be PET, PBT, PTT, or a copolymer thereof with isophthalic acid or the like, or a mixture of two or more thereof, from the viewpoint of heat resistance or high crystallinity. .

The melting point of the crystalline aromatic polyester (B1) is preferably 200 ° C or higher. If the melting point is lower than 200 ° C, the heat resistance at the time of hot pressing may be poor.

When the isophthalic acid copolymerized polyethylene terephthalate is used as the crystalline aromatic polyester (B1), for example, the ratio of the melting point to the copolymerization within the above range may be selected. Specifically, the ratio of isophthalic acid is preferably 20 mol% or less, and particularly preferably 10 mol% or less, based on the total dicarboxylic acid component. When it exceeds 20 mol%, since the melting point and crystallinity of the (B) layer are lowered, the heat resistance at the time of high-temperature hot pressing tends to be inferior.

The crystalline aromatic polyester (B1) may be copolymerized in a range which does not impair the melting point and crystallinity of the layer (B).

The copolymerization component is not particularly limited, and examples of the acid component include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfisophthalic acid, oxalic acid, succinic acid, and adipic acid. Azelaic acid, azelaic acid, dodecanedioic acid, dimer acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, cyclohexanedicarboxylic acid, etc. Carboxylic acid, 4-hydroxybenzoic acid, ε-caprolactone or lactic acid.

Further, examples of the alcohol component include ethylene glycol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, triethylene glycol, and polyethylene glycol. , an ethylene oxide adduct of polypropylene glycol, polytetramethylene glycol, bisphenol A or bisphenol S, and the like.

Further, a trifunctional compound such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin or pentaerythritol can be used in a small amount. These copolymerizable components may be used in combination of two or more kinds.

When two or more kinds of these crystalline aromatic polyesters are used in combination, the mixing ratio is considered to be the crystallinity of the (B1) resin, and may be appropriately selected.

The crystalline aromatic polyester (B1) can be produced by a known method. For example, a method in which a lower alcohol diester of a dicarboxylic acid and an excessive amount of a low molecular weight diol are subjected to a transesterification reaction in the presence of a catalyst to obtain a condensation reaction of the obtained reaction product. Alternatively, for example, a method in which a dicarboxylic acid and an excess amount of a diol are subjected to a transesterification reaction in the presence of a catalyst to obtain a condensation reaction of the obtained reaction product.

Since the polyester after polymerization contains a monomer, an oligomer, or a by-product of acetaldehyde or tetrahydrofuran, when it is used directly for hot pressing, there arises a problem that such a low molecular weight substance moves to a substrate. Therefore, it is preferred to use a raw material which is solid-phase polymerized at a temperature of 200 ° C or higher under a reduced pressure or an inert gas flow.

<1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate (B2)>

1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate (hereinafter, abbreviated as "CHDM-PET") is a PET in which one part of ethylene glycol is substituted with 1,4-cyclohexanedimethanol. Copolymer. In order to increase the degree of amorphization of the polyester (B) layer and to satisfy the embedding property at the time of hot pressing, the 1,4-cyclohexane dimethanol component is contained in an amount of 10 mol% or more, preferably 12 mol, based on the total diol component. More than or equal to the ear, more preferably 15% by mole or more. Further, when the 1,4-cyclohexanedimethanol component is too much, the film tends to have no heat resistance, and the upper limit is preferably 50 mol%, more preferably 45 mol% or less, and most preferably 40 mol% or less.

Specific examples of such CHDM-PET include, for example, "PETG 6763" manufactured by Eastman Chemical Co., Ltd., and the like.

The polyester elastomer (A), the crystalline aromatic polyester (B1), and the CHDM-PET (B2) may be added with a heat stabilizer, an antistatic agent, a crystal nucleating agent, or the like in a non-destructive and practical range. Among them, it is preferred to contain a heat stabilizer. The heat stabilizer is preferably a pentavalent or/and trivalent phosphorus compound or a hindered phenol compound.

The release film of the present invention is preferably a polyester elastomer (A) layer having a thickness of 5 to 50 μm. When the thickness of the polyester elastomer (A) layer is less than 5 μm, the flow balance between the (A) layer and the (B) layer is deteriorated when the resin is extruded during the film production, and flow marks are likely to occur, which is likely to be difficult to form a film. If it exceeds 50 μm, the embedding property is liable to be insufficient.

The thickness of the polyester-based elastomer (A) layer is more preferably from 10 to 30 μm. Here, when the thickness of the layer (A) is two or three layers, the thickness of the layer (A) is two layers or more.

The release film of the present invention is preferably a polyester (B) layer having a thickness of 15 to 160 μm. If the thickness of the polyester (B) layer is less than 15 μm, the soft (A) layer at room temperature is relatively thick, and since the body of the film is weak, wrinkles are easily obtained when the film is taken up, or softness at the time of hot pressing. Insufficient, resulting in a decrease in embedding. When the resin is extruded at a temperature of more than 160 μm, the flow balance between the (A) layer and the (B) layer is deteriorated, flow marks are likely to occur, and film formation tends to be difficult. The thickness of the polyester (B) layer is more preferably from 20 to 100 μm.

The release film of the present invention preferably has a thickness of from 30 μm to 200 μm. When the thickness of the whole is less than 30 μm, the strength and rigidity of the sheet are liable to be lowered, and the handling is difficult to change. In addition, when it exceeds 200 μm, the traceability of the surface pattern of the printed substrate during hot pressing is liable to be lowered, and it may not be suitable for the production of a printed substrate having a fine pattern. The thickness of the whole is more preferably from 30 μm to 150 μm, most preferably from 40 μm to 100 μm.

The preferred structure of the release film of the present invention may be, for example, two or three layers of (A)/(B)/(A) of the polyester elastomer (A) and the polyester (B), or Two types of two layers of A)/(B). However, the layer (A) is not limited to this, and the layer (A) may have other layers if it is disposed on the surface layer.

The preferred thickness composition ratio of the two 3-layer structures of (A)/(B)/(A) is 1/2/1 to 1/5/1. In this range, the (B) layer can sufficiently exhibit the function as the support layer of the (A) layer, and can have both heat resistance and embedding property at the time of hot pressing at a high temperature.

Next, a method of producing the release film of the present invention will be described.

In the production of the release film of the present invention, a method of forming a film by a co-extrusion T-die method is preferred. According to this method, it is easy to adjust the thickness of each layer or to make the layer (A) a desired crystallization state.

In the production of the release film of the present invention, it is necessary to provide a crystallization step for the purpose of imparting specific thermal characteristics to the film and improving heat resistance, release property, and dimensional stability. The crystallization method may, for example, be heat crystallization or alignment crystallization. However, since dimensional stability at a high temperature is necessary for use in hot pressing, there is no substantial alignment, and it is preferable to heat crystallization. The method of heating and crystallization is a method of crystallization from the T die and simultaneously cooling with cooling, and is preferable in terms of the simplicity of the conditioning step or the film quality. When crystallizing at the same time as cooling, the crystallization rate is considered and the temperature of the casting rolls must be appropriately set. The temperature is preferably from 50 to 100 ° C, more preferably from 50 to 80 ° C, if it is a resin of the present invention. Further, in order to adjust the release property and the embedding property, it is necessary to arrange the polyester elastomer (A) which is a release layer on the casting roll side.

The heat shrinkage rate of the release film of the present invention at 180 ° C is preferably 2% or less in the MD direction, more preferably 1.5% or less. In the TD direction, it is preferably 1% or less, more preferably 0.5% or less. If the heat shrinkage rate is such that it is in contact with the hot plate during hot pressing, it is difficult to become wrinkles, and the heat resistance and dimensional stability when producing a printed board are good.

In the release film of the present invention, the surface state of the polyester-based elastomer (A) layer disposed on the surface layer can be smooth depending on the application, and the slip property and the pressure-resistant property can be imparted for workability. Further, for the purpose of removing air during hot press forming, a moderate embossing pattern may be provided on at least one side of the film. For this embossing process, a surface-casting casting roll can be used.

The release film of the present invention is excellent in embedding property, heat resistance, release property, and non-contamination property at the time of high-temperature hot pressing, and can be disposed of safely and easily. Therefore, in the production process of a printed circuit board, a flexible printed circuit board, or a multilayer printed wiring board, the release film of the present invention is obtained by hot-pressing a copper foil laminate or a copper foil via a prepreg or a heat resistant film. It can be suitably used as a release film which is adhered to a hot plate, a printed circuit board, a flexible printed circuit board, a multilayer printed wiring board, or the like. Further, in the manufacturing step of the flexible printed circuit board, when the cover film is adhered by a thermosetting adhesive by hot press forming, it can be suitably used as a film to prevent adhesion between the cover film and the heat press plate, or between the cover films. Adhesive release film.

[Examples]

Hereinafter, the present invention will be described based on examples. However, the present invention is not limited to the following examples.

(A) Polyester elastomer

(A-1) HYTREL 5557: manufactured by Toray Dupont, Tm 208 ° C, Tg -20 ° C

(A-2) HYTREL 6347: manufactured by Toray Dupont, Tm 221 ° C, Tg 3 ° C

(A-3) HYTREL 7247: manufactured by Toray Dupont, Tm 221 ° C, Tg 12 ° C

(A-4) HYTREL 6347M: manufactured by Toray Dupont, Tm 215 ° C, Tg 3 ° C

Tm means melting point and Tg means glass transition temperature. The following is the same.

Any of the above four polyester-based elastic systems is a block copolymer of polybutylene terephthalate and a polyether.

(B1) crystalline aromatic polyester

(B1-1) Polybutylene terephthalate: "Novaduran 5010CS" manufactured by Mitsubishi Engineering Plastic Co., Ltd., Tm 223 ° C, Tg 34 ° C

(B1-2) Polytrimethylene terephthalate; "Corterra 9200" manufactured by Shell Chemical Japan Co., Ltd., Tm 223 ° C, Tg 52 ° C

(B1-3) Polyethylene terephthalate; "NEH-2050" manufactured by Ester Co., Ltd., Tm 255 ° C, Tg: 80 ° C

(B1-4) 4 mol% isophthalic acid copolymerized polyethylene terephthalate, Tm 246 ° C, Tg: 75 ° C

(B2) CHDM-PET

‧Eastman Chemical Company "PETG 6763", Tg 80 ° C

(C) Other

‧ Polymethylpentene: "DX 845" manufactured by Mitsui Chemicals Co., Ltd., Tm 233 ° C, Tg 20 ° C

Various assays and evaluations are shown below.

Using a differential scanning calorimeter ("Pyrisl DSC" manufactured by Perkin Elmer Co., Ltd.), 10 mg of the sample was heated to 260 ° C at a rate of 20 ° C / min, and the glass transition temperature (Tg), melting point (Tm), and crystal melting heat (Δ) were measured. Hm). Further, after maintaining at 260 ° C for 3 minutes, the film was cooled at a rate of 20 ° C / minute, and the crystallization peak temperature (Tc) was measured. The difference between the melting point and the temperature at which the crystallization peak is lowered is the index of crystallization rate.

The sample in the measurement of the melting point (Tm), the glass transition temperature (Tg), and the crystallization rate index is a sample obtained by rapidly melting the raw material resin and then quenching it. The heat of crystal melting of the layer (A) is determined by using a polyester-based elastomer (A) alone resin, and the thickness, the extrusion speed, the temperature of the casting roll, and the temperature of the laminated film are the same, and a single-layer film sample is produced. . Even in the heat of crystal melting of the layer (B), the resin in which the crystalline aromatic polyester (B1) and the CHDM-PET (B2) are blended is similarly produced under the same manufacturing conditions as the laminated film. As such, it is measured using this.

<film forming workability>

The roll take-up property after the end of the film obtained by the cutting was evaluated based on the following criteria, and ○ was acceptable (good).

○: There is no problem in the rollability of the roll.

△: a little wrinkle when the roll is taken up

×: There is no wrinkle when the roll is taken, it is difficult to take up

<heat resistance, interlayer non-bleeding property, embedding property, release property>

Both sides of the 25 μm thick polyimide film ("Kapton 100V" manufactured by Dupont Co., Ltd.) having a 20 μm epoxy adhesive ("AS-60" manufactured by Toagosei Co., Ltd.) were coated on both sides, and laminated to a thickness of 35 μm. Copper foil, a three-layer copper foil laminate was produced. A 25 μm thick polyimide film ("Kapton 100V" manufactured by Dupont Co., Ltd.) coated with a 20 μm epoxy-based adhesive ("AS-60" manufactured by Toagosei Co., Ltd.) was used as a cover film on one surface thereof, and further provided for use. The release film used for the test was placed on both sides. At this time, the surface of the polyester elastomer (A) of the release film is disposed inside. Thereafter, the pressure was hot pressed at a temperature of 180 ° C and a pressure of 3 MPa for 5 minutes. After the hot pressing, the film was quickly taken out from the hot press device and allowed to cool, and then the release film was peeled off. Regarding the current situation, evaluation of heat resistance, interlayer non-bleeding property, embedding property, and release property was performed based on the following criteria. ○ The above is judged to be acceptable (good). At this time, the cover film was opened with a true round hole having a diameter of 5 mm, and was used for evaluation of the bleeding of the adhesive.

(heat resistance)

○: No wrinkles were observed in the film after hot pressing.

△: The film after hot pressing showed a slight wrinkle.

×: Significant wrinkles were observed in the film after hot pressing.

(intermediate layer non-exudative)

○: no seepage of the intermediate layer polymer was observed from the end of the film after hot pressing

△: Exudation of the intermediate layer polymer can be seen from the end of the film after hot pressing

X: The exudation of the intermediate layer polymer was apparent from the end of the film after hot pressing, and the polymer adhesion to the laminate or the hot plate was observed.

(buried)

The exudation length of the adhesive covering the pores of the film was observed under a microscope, and evaluated based on the following criteria.

◎: The exudation length of the adhesive is 50 μm or less

○: The exudation length of the adhesive is more than 50 μm and 70 μm or less.

△: The bleed length of the adhesive is more than 70 μm and 100 μm or less.

╳: The exudation length of the adhesive is more than 100μm

(release)

◎: peeling without impedance

○: Slightly resistive, but peeled off without affecting the laminate

△: There is impedance, but the laminate is peeled off without deformation.

╳: Strong impedance, accompanied by deformation of the laminate

<Weather resistance>

Using a thermal debonding GC-MS, the gas generated from the film by heating at 180 ° C for 10 minutes was separated using a non-polar capillary, and the amount of hexane in terms of the total area of the detected peak was normalized by the film weight. As the amount of outgassing. The amount of outgassing is preferably small, and 400 ppm or less is judged to be acceptable (good).

<heat shrinkage rate>

The heat shrinkage ratio in the MD direction and the TD direction of the film was measured in the following order.

The sample film was cut into 10 mm × 150 mm, and five test pieces on which two lines were placed were prepared at intervals of 100 mm.

The obtained test piece was heat-treated in an oven at 170 ° C for 30 minutes under no load, and the test piece was taken out and returned to room temperature to measure the distance between the lines. The heat shrinkage ratio was determined according to the following formula, and the five average values were used as the heat shrinkage ratio of each sample film.

Heat shrinkage rate (%) = (L-L') / A × 1000

L: distance between the lines before the heat treatment (mm), L': distance between the lines after the heat treatment (mm).

[Example 1]

For each of the two independent extruders, A-2 was supplied as the (A) layer resin, and B1-1 and B2 were supplied to have a mass ratio of 40/60 as the (B) layer resin, and the resin of either layer was melted at 260 ° C. Mixed. The respective melts were combined into a layered A/B/A layer before reaching the exit of the T-die, and then extruded from the T-die outlet, and sealed with a casting roll adjusted to 80 ° C to be cooled. A laminate film having a layer thickness of A/B/A = 20/60/20 (μm). The adhesion time of the casting rolls was 4 seconds.

[Examples 2 to 12, Comparative Examples 1 to 5]

The composition of the resin used in each of the layers (A) and (B), the blending ratio of the layer B (B1) (B2), and the layer thickness were changed as shown in Tables 1 to 3 as compared with Example 1. . Examples 2 to 7, Example 10, and Comparative Examples 1 to 5 were melted at 260 ° C, and Examples 8 to 9 were melted at 280 ° C and extruded from the T die exit. The resin to be extruded was adhered to a casting roll adjusted to the temperatures shown in Tables 1 and 3. In the same manner as in Example 1, two types of three-layered laminated films having a structure of A/B/A were obtained. The adhesion time of the casting rolls was 4 seconds.

[Example 13]

For each of the two independent extruders, A-2 was supplied as the (A) layer resin, and B1-1 and B2 were supplied to have a mass ratio of 40/60 as the (B) layer resin, and the resin of either layer was melted at 260 ° C. Mixed. After the respective melts are joined to the outlet of the T die, the two layers of the A/B are combined, and then extruded from the exit of the T die, and sealed with a casting roll adjusted to 80 ° C to be cooled to obtain a layer thickness. It is a laminated film of A/B = 30/60 (μm). The adhesion time of the casting rolls was 4 seconds.

[Examples 14 to 15, Comparative Example 6]

The type of the resin used in each of the layers (A) and (B), the blending ratio of the layer B, and the layer thickness were changed as shown in Tables 2 to 3 as compared with Example 13. It is then melted at 260 ° C and extruded from the T die exit. The casting rolls were adhered to the temperatures adjusted to the temperatures shown in Tables 2 to 3. In the same manner as in Example 1, two types of two-layered laminated films having a structure of A/B were obtained. The adhesion time of the casting rolls was 4 seconds.

[Comparative Examples 7 to 10]

The resin shown in Table 3 was supplied to the extruder, melt-kneaded at 260 ° C, and baked, and baked with a casting roll adjusted to the temperature shown in Table 3, and cooled to obtain a single-layer film having the thickness shown in Table 3. The adhesion time of the casting rolls was 4 seconds. Further, since the films produced in Comparative Examples 7 to 10 were single-layer films, evaluation of non-bleeding of the intermediate layers could not be performed.

The layer constitutions, blending ratios, various characteristics, and performance evaluation results of Examples 1 to 15 and Comparative Examples 1 to 10 are shown in Tables 1 to 3. In each table, the B layer blending ratio represents the mass ratio.

The sheets of Examples 1 to 15 have various characteristics within the range specified by the present invention, and thus fully satisfy the required properties as a release film. In particular, since it is excellent in release property and embedding property at the time of high-temperature hot pressing, it can cope with a printed circuit board having a precise pattern, and has a small amount of outgassing and excellent stain resistance.

In Comparative Example 1, the release layer was polybutylene terephthalate, and the intermediate layer was a polyester elastomer. Therefore, although the release property is good, the glass transition temperature and the crystal melting heat are high, so the embedding property is poor.

In Comparative Example 2, the release layer was a polyester elastomer, and the intermediate layer was polybutylene terephthalate. Therefore, the crystal melting heat is high and the embedding property is poor.

In Comparative Example 3, since the intermediate layer did not contain the crystalline aromatic polyester, the intermediate layer was in an amorphous state. Therefore, although the embedding property is good, the heat resistance is poor, and in particular, the bleeding of the polymer derived from the intermediate layer is remarkable.

In Comparative Example 4, the content of the crystalline aromatic polyester in the intermediate layer was too large, and since the crystallinity of the intermediate layer was too high, the embedding property was poor.

In Comparative Examples 5 and 6, the glass transition temperature of the release layer was too low, so that the embedding property was good, but the heat resistance and the release property were poor, and the film was wrinkled during winding during film formation.

In Comparative Example 7, the polyester-based elastomer single layer did not have the polyester layer of the intermediate layer. Therefore, the film body was weak, the film forming workability was poor, and the flexibility at the time of hot pressing was insufficient, so that the embedding property was also insufficient.

Comparative Example 8 is a single layer of polybutylene terephthalate, and since the crystallinity is too high, the release property or heat resistance is good, but the embedding property is poor.

Comparative Example 9 is a film composed of polymethylpentene which is widely used as a release film. However, the outgas generation amount is remarkably as large as about 10 times that of the film of the present invention, and is poor in stain resistance.

Comparative Example 10 does not have a release layer composed of a polyester elastomer. Therefore, although the embedding property at the time of hot press is excellent, since the film has low crystallinity, heat resistance and release property are inferior.

Claims (5)

A release film characterized by having a polyester-based elastomer (A) layer disposed on a surface layer and a polyester (B) layer, and the polyester-based elastomer (A)-based glass has a glass transition temperature of 0 to 20 ° C and The crystallization rate is 20 to 50 ° C, and the polyester (B) contains a crystalline aromatic polyester (B1) and 1,4-cyclohexane dimethanol copolymerized polyethylene terephthalate (B2). The mass ratio (B1) / (B2) is in the range of 5/95 to 50/50, and the polyester (B) is glass transition temperature of 40 to 80 ° C and the heat of crystal fusion is 5 to 40 J/g. The release film according to claim 1, wherein the polyester elastomer (A) has a glass transition temperature of 3 to 12 ° C and a crystallization rate of 25 to 48 ° C, in the polyester (B) The mass ratio (B1)/(B2) of the crystalline aromatic polyester (B1) to 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate (B2) is 10/90 to 50/ In the range of 50, the polyester (B) glass has a glass transition temperature of 50 to 73 ° C and a heat of crystal fusion of 8 to 35 J/g. The release film according to claim 1 or 2, wherein the polyester elastomer (A) is a block copolymer of polybutylene terephthalate and polyether. The release film according to claim 1 or 2, wherein the crystalline aromatic polyester (B1) is polybutylene terephthalate, polytrimethylene terephthalate or polyparaphenylene Ethylene formate or isophthalic acid copolymerized polyethylene terephthalate or a mixture of two or more thereof. The release film according to claim 1 or 2, wherein the laminate film is composed of two types of (A)/(B)/(A), or (A)/(B) 2 kinds of 2 layers.