JP6187025B2 - Biaxially oriented polyester film for mold release - Google Patents

Description

The present invention relates to a biaxially oriented polyester film for release, and is particularly suitable as a heat-resistant release film for use in circuit process films that require a matte tone because of its low gloss and high tear propagation resistance. The present invention relates to a release biaxially oriented polyester film.

  In recent years, with the integration of circuits accompanying the expansion of smartphones and tablets, high precision and high density of printed wiring boards have been advanced. In the printed wiring board manufacturing process, a circuit is provided on the surface of an insulating substrate (polyimide resin, polyphenylene sulfide resin, etc.) and then covered with a cover lay, which is a heat-resistant resin film having an adhesive layer, for the purpose of insulation and circuit protection. Then, molding by press lamination is performed via a release film. At this time, the printed wiring board material, release property with the press plate, conformability to the shape, uniform formability, matte appearance, etc. are excellent. There is a need for release films. Further, there is an increasing need for a matte film excellent in appearance and releasability as a base material on which a functional layer such as an insulating layer or an electromagnetic wave shielding layer is transferred onto the surface of a circuit board by a hot press.

  A polyester film containing inorganic particles or organic particles at a high concentration has been proposed as a film to be applied to the application (for example, Patent Documents 1 and 2).

JP 2005-312263 A JP 2009-215822 A

  However, although the films described in Patent Documents 1 and 2 are excellent in matte tone, the tear propagation resistance is insufficient, resulting in film tearing after hot pressing and maintaining process stability in the circuit manufacturing process. It is difficult.

  An object of the present invention is to eliminate the above-described problems of the prior art. That is, to provide a biaxially oriented polyester film suitable for a heat-resistant release film used for circuit process films that require a matte tone by exhibiting a matte appearance with a low glossiness and a high tear propagation resistance. It is in.

The gist of the present invention for solving this problem is as follows:
At least one outermost layer has a polyester A layer containing 1% by mass or more and 10% by mass or less of inorganic particles and / or organic particles based on 100% by mass of the entire polyester A layer, and the polyester A layer side of the outermost layer The gloss value measured from 1 to 30 is an average value of tear propagation resistance in an arbitrary direction of the film (X direction) and a direction orthogonal to the X direction (Y direction) of 6. A biaxially oriented polyester film for release that is 5 N / mm or more,
It is.

Since the release biaxially oriented polyester film of the present invention has low gloss and high tear propagation resistance, it can be suitably used for heat-resistant release films for circuit process film applications that require matte tone.

  The polyester constituting the biaxially oriented polyester film for mold release according to the present invention is a general term for polymer compounds having an ester bond as the main bond in the main chain. The polyester resin can be usually obtained by polycondensation reaction of dicarboxylic acid or its derivative with glycol or its derivative.

  In the present invention, from the viewpoint of appearance, heat resistance, dimensional stability and economy, 60 mol% or more of the glycol units constituting the polyester are structural units derived from ethylene glycol, and 60 mol% or more of the dicarboxylic acid units are terephthalic. A structural unit derived from an acid is preferred. Here, the dicarboxylic acid unit (structural unit) or the diol unit (structural unit) means a divalent organic group from which a portion to be removed by polycondensation has been removed. It is represented by

Dicarboxylic acid unit (structural unit): —CO—R—CO—
Diol unit (structural unit): —O—R′—O—
(Where R and R ′ are divalent organic groups)
In addition, when a trivalent or higher carboxylic acid or alcohol such as trimellitic acid unit or glycerin unit or a derivative thereof is included, the trivalent or higher carboxylic acid or alcohol unit (structural unit) is similarly obtained by polycondensation. The trivalent or higher valent organic group from which the part to be removed is removed is meant.

  Glycols or derivatives thereof that give polyester for use in the present invention include, in addition to ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, Aliphatic dihydroxy compounds such as 1,5-pentanediol, 1,6-hexanediol and neopentyl glycol, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, 1,4-cyclohexanedimethanol , Alicyclic dihydroxy compounds such as spiroglycol, aromatic dihydroxy compounds such as bisphenol A and bisphenol S, and derivatives thereof. Of these, diethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol are preferably used from the viewpoint of moldability and handleability.

  In addition to terephthalic acid, the dicarboxylic acid or derivative thereof that provides the polyester used in the present invention includes isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid. Acids, aromatic dicarboxylic acids such as 5-sodiumsulfone dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid, etc. Alicyclic dicarboxylic acids, oxycarboxylic acids such as paraoxybenzoic acid, and derivatives thereof. Examples of dicarboxylic acid derivatives include dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl adipate, diethyl maleate, and dimethyl dimer. An esterified product can be mentioned. Among these, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and esterified products thereof are preferably used from the viewpoint of moldability and handleability.

  The biaxially oriented polyester film for mold release of the present invention has a low glossiness and a matte appearance. In order to achieve a matte appearance, inorganic particles and / or organic particles are added in an amount of 1% by mass or more based on 100% by mass of the entire polyester A layer. It is necessary to have a polyester A layer containing at most mass% in at least one outermost layer.

  Here, the inorganic particles and / or organic particles to be used are not particularly limited. For example, the inorganic particles include wet and dry silica, colloidal silica, aluminum silicate, calcium carbonate, calcium phosphate, aluminum oxide, and the like. As the organic particles, particles containing styrene, silicone, acrylic acids, methacrylic acids, polyesters, divinyl compounds and the like as constituent components can be used. Among them, it is preferable to use inorganic particles such as wet and dry silica, colloidal silica, and aluminum silicate, and particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituent components. From the viewpoint of mat appearance and economy, wet and dry silica, colloidal silica, and aluminum silicate are particularly preferably used. These externally added particles may be used in combination of two or more.

  In the present invention, the inorganic particles and organic particles used do not include coloring agents for coloring purposes such as dyes, inorganic pigments, and organic pigments. Specifically, Bengala, Molybdenum Red, Cadmium Red, Red Yellow Pb, Chromium Permillion, Blue Pigment, Bitumen, Cobalt Blue, Cerulean Blue, etc. Inorganic pigments such as yellow, yellow iron oxide, titanium yellow, manganese violet, mineral violet, titanium dioxide, barium sulfate, zinc white, zinc sulfate, carbon black, black iron oxide, condensed azo, phthalocyanine, quinacridone, dioxazine, isoindolinone Organic pigments such as quinophthalone and anthraquinone are not applicable to the inorganic particles and organic particles of the present invention.

Further, the content of the inorganic particles and / or organic particles used in the biaxially oriented polyester film for release of the present invention is 1% by mass or more based on 100% by mass of the entire polyester A layer in order to achieve a matte appearance. Although it is necessary to contain 10 mass% or less, from a viewpoint of a mat-like appearance and tear propagation resistance, it is preferable to contain 1.5 mass% or more and 8 mass% or less by making the whole polyester A layer into 100 mass%. It is preferable to contain 6 mass% or less.
In addition, the inorganic particles and / or organic particles used in the present invention preferably have an average particle size of 2 μm or more and 10 μm or less, more preferably 3 μm or more and 9 μm or less from the viewpoint of matte appearance and tear propagation resistance. The thickness is most preferably 4 μm or more and 8 μm or less. The average particle diameter in the present invention refers to the number average diameter D represented by D = ΣDi / N (Di: equivalent circle diameter of particles, N: number of particles).

  The biaxially oriented polyester film for release of the present invention needs to have a glossiness of 30 or less as measured from the polyester A layer side of the outermost layer in order to achieve excellent release properties and a matte appearance. It is preferable that the glossiness measured from the polyester A layer side of the outermost layer is 30 or less because it is easy to achieve releasability and matte appearance as a circuit process film. When the glossiness is greater than 30, the mold release may be deteriorated and the matte tone may be insufficient. More preferably, the glossiness measured from the polyester A layer side of the outermost layer is 25 or less, most preferably 20 or less. When the glossiness measured from the polyester A layer side of the outermost layer is 20 or less, even when a functional layer such as an insulating layer or an electromagnetic wave shielding layer is transferred to a circuit board or the like by a heat press, the appearance of the functional layer is also This is very preferable because it provides an excellent mat appearance. The method of setting the glossiness of at least one side to 30 or less is not particularly limited. For example, inorganic particles and / or organic particles having a particle size of 2 μm or more and 10 μm or less are used in an amount of 1% by mass or more based on 100% by mass of the entire polyester A layer The method which has a polyester A layer containing 10 mass% or less is mentioned.

The biaxially oriented polyester film for mold release of the present invention is an arbitrary one direction (X direction) of the film from the viewpoint of suppressing tearing at the time of film peeling when used as a heat-resistant release film as a process film for a circuit. The average value of tear propagation resistance in the direction orthogonal to the X direction (Y direction) is 6. It is necessary to be 5 N / mm or more. When the average value of tear propagation resistance in any one direction (X direction) and the direction orthogonal to the X direction (Y direction) is less than 5 N / mm, when used as a heat-resistant release film, the film is torn during film peeling. There is a case . The higher the tear propagation resistance, the better from the viewpoint of suppressing film breakage, but from the viewpoint of film forming properties and practical properties, tear propagation in any one direction (X direction) and the direction orthogonal to the X direction (Y direction). The average value of resistance is more preferably 20 N / mm or less, and most preferably 10 N / mm or less.

The average value of tear propagation resistance in any one direction (X direction) of the biaxially oriented polyester film for release of the present invention and in the direction orthogonal to the X direction (Y direction) is 6. Although it does not specifically limit as a method of setting it as 5 N / mm or more, For example, it is more inorganic than the polyester A layer which contains an inorganic particle and / or an organic particle 1 mass% or more and 10 mass% or less by making the whole polyester A layer into 100 mass%. The method of setting it as the structure which has the polyester B layer with little content of particle | grains and / or organic particle | grains is mentioned. When inorganic particles and / or organic particles are contained in the polyester film, the particles become the starting point and the tear propagation resistance is lowered, but the polyester B layer has a smaller content of inorganic particles and / or organic particles than the polyester A layer. In the polyester A layer, the glossiness can be lowered to 30 or less, and the tear propagation resistance can be kept high in the polyester B layer. In the present invention, the content of inorganic particles and / or organic particles in the polyester B layer having a smaller content of inorganic particles and / or organic particles than the polyester A layer is not particularly limited as long as it is lower than that of the polyester A layer. The amount is preferably less than 1% by mass, more preferably 0.5% or less, and most preferably 0.1% by mass or less. For the purpose of increasing the average value of tear propagation resistance to 5 N / mm or more, the content of inorganic particles and / or organic particles in the polyester B layer is preferably 0% by mass.

Further, in the case of a configuration having a polyester B layer, the tear propagation resistance in a glossy of 30 or less, an arbitrary direction (X direction) and a direction orthogonal to the X direction (Y direction) measured from the polyester A layer side of the outermost layer The average value is 6. In order to make 5 N / mm or more compatible, the thickness ratio of the A layer and the B layer is preferably 0.1 or more and 1 or less as the A layer thickness / B layer thickness, and more preferably 0.1 or more and 0.5 or less. Preferably, it is most preferably 0.15 or more and 0.4 or less.

In addition, since the biaxially oriented polyester film for release of the present invention needs to have a glossiness of 30 or less as measured from the polyester A layer side of the outermost layer, when it has a polyester B layer, A layer / B layer At least one surface layer such as A layer / B layer / A layer is preferably an A layer.
In addition, the average value of tear propagation resistance in any one direction (X direction) of the biaxially oriented polyester film for release of the present invention and the direction orthogonal to the X direction (Y direction) is 6. As a method of making it 5 N / mm or more, it is also preferable that the intrinsic viscosity (dl / g) of the polyester A layer is 0.6 or more. By making the intrinsic viscosity as high as 0.6 or more, it becomes possible to keep the tear propagation resistance high even if inorganic particles and / or organic particles are contained. The intrinsic viscosity of the polyester A layer is more preferably 0.62 or more, and most preferably 0.65 or more. In order to set the intrinsic viscosity of the polyester A layer to 0.6 or more, the intrinsic viscosity of the resin before the extrusion forming the polyester A layer is preferably 0.68 or more, more preferably 0.69 or more.
Moreover, the average value of the tear propagation resistance in any one direction (X direction) of the biaxially oriented polyester film for release of the present invention containing particles at a high concentration and in the direction orthogonal to the X direction (Y direction) Is 5 N / mm or more, a method of suppressing thermal crystallization while keeping the amorphous chain in a low orientation is effective. Specifically, this is a method in which the draw ratio is lowered and the heat treatment after biaxial stretching is raised and lowered stepwise. A preferred draw ratio is preferably 2.8 times or more and 3.4 times or less, more preferably 2.9 times or more and 3.3 times or less in the longitudinal direction. The stretching speed is preferably 1,000% / min or more and 200,000% / min or less. Moreover, it is preferable that the extending | stretching temperature of a longitudinal direction shall be 70 degreeC or more and 90 degrees C or less. The stretching ratio in the width direction is preferably 2.8 times or more and 3.8 times or less, and more preferably 3 times or more and 3.6 times or less. The stretching speed in the width direction is desirably 1,000% / min or more and 200,000% / min or less. The stretching temperature in the width direction is preferably 90 ° C. or higher and 150 ° C. or lower. Furthermore, the heat treatment of the film after biaxial stretching can be performed by any conventionally known method such as in an oven or on a heated roll, but the first half temperature of the heat treatment is 180 ° C. or more and less than 220 ° C. It is preferable that the temperature in the latter half of the heat treatment be 210 ° C. or higher and 235 ° C. or lower and 210 ° C. or higher and 220 ° C. or lower. In order to further reduce the heat shrinkage rate, it is also preferable to perform slow cooling at 140 ° C. or more and less than 180 ° C. after the heat treatment.

  In addition, the biaxially oriented polyester film for mold release of the present invention is obtained from the viewpoint of heat resistance when used for heat-resistant mold release applications, after heat-pressing for 2 hours at 180 ° C. × 3 MPa. It is preferable that the average value of tear propagation resistance in any one direction (X direction) and the direction orthogonal to the X direction (Y direction) is 5 N / mm or more. This is done by using a press machine heated to a temperature of 180 ° C. for both the upper mold temperature and the lower mold temperature, and a 0.2 mm thick aluminum plate / 0.125 mm thick polyimide film (Kapton 500H / V manufactured by Toray DuPont). ) / Biaxially oriented polyester film for mold release of the present invention / Polyimide film of 0.125 mm thickness (Kapton 500H / V manufactured by Toray DuPont) / Aluminum plate of 0.2 mm thickness 2 under the condition of 3 MPa This value is obtained by measuring the tear propagation resistance after performing the time heating press. When used in heat-resistant release applications, film peeling is generally performed after heating, and even if the tear propagation resistance before heating is high, the tear propagation resistance decreases after heating. In the film peeling process, the film may be torn. The average value of the tear propagation resistance in any one direction (X direction) and the direction orthogonal to the X direction (Y direction) after heat-pressing for 2 hours under the condition of 180 ° C. × 3 MPa is 5. 5 N / mm or more is more preferable, and 6 N / mm or more is most preferable. The average value of the tear propagation resistance in any one direction (X direction) and the direction orthogonal to the X direction (Y direction) after heating and pressing for 2 hours under the condition of 180 ° C. × 3 MPa is 5 N / mm. Although the method to make it above is not particularly limited, the average value of the tear propagation resistance in any one direction (X direction) of the film before pressing and in the direction orthogonal to the X direction (Y direction) is 5 N / mm or more. In addition to the above method, a method in which the amount of carboxyl end groups of the polyester A layer is 20 eq / t or less is preferably used. By keeping the carboxyl end group amount of the polyester A layer as low as 20 eq / t or less, thermal decomposition of the polyester A layer during heating can be suppressed, and tear propagation resistance can be kept high even after heating. The method for setting the carboxyl end group amount of the A layer to 20 eq / t or less is not particularly limited, but the carboxyl end group amount of the resin constituting the polyester A layer is set to 20 eq / t or less, and further, the flow of nitrogen through the extruder during melt extrusion In the atmosphere, it is preferable to control the oxygen concentration to 0.7 volume% or less and the resin temperature to 265 ° C. to 285 ° C.

  Moreover, the biaxially oriented polyester film for mold release of the present invention is at 25 ° C. in an arbitrary direction (X direction) of the film and a direction orthogonal to the X direction (Y direction) from the viewpoint of strength at the time of roll conveyance. It is preferable that the average value of breaking strength is 150 MPa or more and 250 MPa or less. By setting the average value of the breaking strength at 25 ° C. in any one direction (X direction) of the film and the direction orthogonal to the X direction (Y direction) to 150 MPa or more and 250 MPa or less, the film can be transported at high speed. It is possible to suppress the occurrence of process trouble such as cutting. The biaxially oriented polyester film for mold release of the present invention is effective to suppress the thermal crystallization while making the amorphous chain low oriented in order to increase the tear propagation resistance. Therefore, it is difficult to achieve both high breaking strength with a simple film forming method. Therefore, as a result of intensive studies, the present inventors have found that it is effective to make a low-oriented amorphous chain more rigid as a method for achieving both high tear propagation resistance and high breaking strength. Specifically, a method in which stretching in the width direction is divided into a plurality of zones and is stretched while raising the temperature stepwise is preferable. Further, there is a method in which the stretching latter half temperature is 110 ° C. or more and 150 ° C. or less, and the temperature is increased in the order of the first half stretching temperature, the middle stretching temperature, and the second half stretching temperature.

  In addition, the biaxially oriented polyester film for release of the present invention preferably has a color tone L value of 60 or more and 80 or less from the viewpoint of visibility as a film. By setting the color tone L value to 60 or more and 80 or less, it is possible to ensure appropriate visibility. The color tone L value is more preferably from 62 to 78, and most preferably from 65 to 75. As a method for setting the color tone L value of the biaxially oriented polyester film for release of the present invention to 60 or more and 80 or less, for example, the entire layer is 100% by mass, and titanium dioxide is 0.1% by mass or more and 5% by mass or less. It is preferable to have a layer containing 0.5% by mass or more and 4% by mass or less. Titanium dioxide may be contained in the polyester A layer, or may be contained in the polyester B layer when it has a polyester B layer.

  The biaxially oriented polyester film for mold release according to the present invention has a film thickness of preferably 15 μm or more and 150 μm, more preferably 25 μm or more and 100 μm or less, and more preferably 30 μm or more, from the viewpoints of heat resistance, handleability and economy. Most preferably, it is 75 μm or less.

  Moreover, when the biaxially oriented polyester film for mold release of the present invention is used for heat-resistant mold release, the surface free energy may be 25 mN / m or more and 40 mN / m or less on the surface having a glossiness of 30 or less. preferable. By making the surface free energy 25 mN / m or more and 40 mN / m or less while setting the glossiness measured from the polyester A layer side of the outermost layer to 30 or less, it is possible to achieve excellent releasability. The surface free energy of the biaxially oriented polyester film for mold release according to the present invention is more preferably 30 mN / m or more and 38 mN / m or less, and more preferably 32 mN / m or more and 37 mN, in order to achieve appropriate adhesion and release properties. / M or less is most preferable.

  The method for setting the surface free energy of at least one surface of the biaxially oriented polyester film for mold release of the present invention to 25 mN / m or more and 40 mN / m or less is not particularly limited, but mold release of silicone compounds, wax compounds, fluorine compounds, and the like. In the present invention, from the viewpoint of heat resistance during heating, a release layer containing a melamine resin and a release agent is included. It is preferable to laminate. From the viewpoint of heat resistance and release stability, the content of the melamine resin in the release layer is preferably 50% by mass or more.

  Examples of the melamine resins include melamine formaldehyde resins, methylated melamine formaldehyde resins, butylated melamine formaldehyde resins, etherified melamine formaldehyde resins, melamine formaldehyde resins such as epoxy-modified melamine formaldehyde resins, urea melamine resins, and acrylic melamine resins. Melamine formaldehyde resin is preferable, and methylated melamine formaldehyde resin is particularly preferably used because it has an appropriate release property. Moreover, it is preferable that the mold release layer of this invention contains binder resin other than binder resin and a mold release agent from a viewpoint of film forming property and extending | stretching followability. As the binder resin, a polyester resin, an acrylic resin, and a urethane resin are preferably used, and an acrylic resin is particularly preferably used. Examples of the acrylic resin include a homopolymer or copolymer of (meth) acrylic acid alkyl ester, a (meth) acrylic acid ester copolymer having a curable functional group at the side chain and / or main chain terminal, Examples of the curable functional group include a hydroxyl group, a carboxyl group, an epoxy group, and an amino group. Among them, an acrylic monomer copolymer obtained by copolymerizing an acrylic monomer and an acrylic ester having a curable functional group at the side chain and / or main chain terminal is preferable. Moreover, as a mold release agent contained in the mold release layer of this invention, a fluorine compound, a long-chain alkyl compound, a wax compound etc. are mentioned, for example. These release agents may be used alone or in combination.

  The fluorine compound that can be used in the present invention is a compound containing a fluorine atom in the compound. Examples thereof include perfluoroalkyl group-containing compounds, polymers of fluorine-containing olefin compounds, and aromatic fluorine compounds such as fluorobenzene. When the release film of the present invention is used for molding simultaneous transfer foil applications and the like, a high heat load is applied at the time of transfer. Therefore, considering heat resistance and contamination, the fluorine compound is preferably a polymer compound.

  The long-chain alkyl compound is a compound having a linear or branched alkyl group having 6 or more, particularly preferably 8 or more carbon atoms. Specific examples include, but are not limited to, long-chain alkyl group-containing polyvinyl resins, long-chain alkyl group-containing acrylic resins, long-chain alkyl group-containing polyester resins, long-chain alkyl group-containing amine compounds, long-chain alkyl groups. And an ether compound, a long-chain alkyl group-containing quaternary ammonium salt, and the like. It is preferable that the long-chain alkyl compound is a polymer compound because the component derived from the release layer on the surface of the counterpart substrate that is bonded when the release film is peeled can be suppressed.

  The wax that can be used in the present invention is a wax selected from natural waxes, synthetic waxes, and blended waxes thereof. Natural waxes are plant waxes, animal waxes, mineral waxes, and petroleum waxes. Examples of plant waxes include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil. Animal waxes include beeswax, lanolin, and whale wax. Examples of the mineral wax include montan wax, ozokerite, and ceresin. Examples of petroleum wax include paraffin wax, microcrystalline wax, and petrolatum. Synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, and ketones. As synthetic hydrocarbons, Fischer-Tropsch wax (also known as sazoir wax) and polyethylene wax are well known, but in addition to these, low molecular weight polymers (specifically, polymers having a viscosity average molecular weight of 500 to 20000) are used. The following polymers are also included. That is, there are polypropylene, ethylene / acrylic acid copolymer, polyethylene glycol, polypropylene glycol, polyethylene glycol and polypropylene glycol block or graft conjugate. Examples of the modified wax include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivative herein is a compound obtained by any of purification, oxidation, esterification, saponification treatment, or a combination thereof. Hydrogenated waxes include hardened castor oil and hardened castor oil derivatives.

  By uniformly dispersing these release agents on the surface of the release layer, the adhesion and release force with the release layer laminated and peeled on the release layer can be within an appropriate range. As the mold release agent, a long-chain alkyl compound is preferably used for the purpose of the present invention because the peel force can be adjusted over a wide range.

  Further, the resin constituting the release layer of the present invention may contain inert particles for the purpose of improving the adhesion and slipperiness of the release layer. Specific examples of the inert particles include silica, alumina, kaolin, calcium carbonate, titanium oxide, and organic particles.

  The biaxially oriented polyester film for mold release of the present invention is bonded to Nitto Denko Corporation OPP adhesive tape (Dumplon Tape No. 375), and the peel strength required by the following measurement method is 0.02 N / 10 mm or more. 2N / 10 mm or less is preferable. (Measurement method) The biaxially oriented polyester film for mold release of the laminate of the present invention and Nitto Denko Co., Ltd. OPP adhesive tape (Damplon Ace No. 375) were bonded together and cut into a rectangle with a width of 10 mm and a length of 150 mm. A sample. The sample was forcibly peeled between the biaxially oriented polyester film and the OPP adhesive tape layer, and using a tensile tester (Tensilon UCT-100 manufactured by Orientec), the initial tensile chuck distance was 100 mm, and the tensile speed was 20 mm / As a minute, a 180 ° peel test is performed. Measurement is performed until the peel length reaches 130 mm (distance between chucks 230 mm), and the average value of the loads having a peel length of 25 mm to 125 mm is defined as the peel strength.

  When the biaxially oriented polyester film for mold release of the present invention is used for heat-resistant mold release applications, the peel strength with the Nitto Denko Corporation OPP adhesive tape (Damplon tape No. 375) determined by the above-described measurement method By setting the ratio to 0.02 N / 10 mm or more and 2 N / 10 mm or less, it is possible to achieve both appropriate adhesion and releasability regardless of the counterpart material. The peel strength is more preferably 0.03 N / 10 mm or more and 1.5 N / 10 mm or less, and most preferably 0.04 N / 10 mm or more and 1 N / 10 mm or less. In particular, in applications where light peeling is required, it is preferably 0.04 N / 10 mm or more and 0.2 N / 10 mm or less.

  The method for setting the peel strength of the biaxially oriented polyester film for release of the present invention to Nitto Denko Corporation OPP adhesive tape (Dumplon tape No. 375) to 0.02 N / 10 mm or more and 2 N / 10 mm or less is not particularly limited. However, for example, there is a method in which the glossiness measured from the polyester A layer side of the outermost layer is 25 or less. Lowering the gloss level means that the surface becomes rough, so the contact area with the Nitto Denko Corporation OPP adhesive tape (Damplon Tape No. 375) is reduced, and the peel strength is 0.02 N / 10 mm or more and 2 N. / 10mm or less and easy to control. Further, as a method of controlling the peel strength with higher accuracy, a method of providing a release layer is preferably used. By providing the release layer, the peel strength with the Nitto Denko Corporation OPP adhesive tape (Dumplon Tape No. 375) can be controlled with high accuracy. Further, in order to control the peel strength with high accuracy, the thickness of the release layer is preferably 0.02 μm or more and 0.1 μm or less. By setting the thickness of the release layer to 0.02 μm or more and 0.1 μm or less, it is possible to suppress unevenness of glossiness (surface irregularity shape) due to the release layer, thus ensuring stable release properties. And the above peel strength can be achieved. An example of a method for setting the thickness of the release layer to 0.02 μm or more and 0.1 μm or less is an in-line coating method in which a release layer is provided in the film manufacturing process. The in-line coating method as used herein refers to a film obtained by dispersing a release layer composition in water on at least a uniaxially stretched film, uniformly applied using a metalling bar, gravure roll, etc. This is a method of drying the coating agent.

  Next, although the example of the specific manufacturing method of the biaxially-oriented polyester film for mold release of this invention is described, this invention is limited to this example and is not interpreted.

  When making a laminated polyester film having a polyester A layer and a polyester B layer, first, as polyester A used for the polyester A layer, silica particles having an average particle diameter of 5 μm in polyethylene terephthalate resin (a) and polyethylene terephthalate resin (a) The particle-containing polyethylene terephthalate resin (a ′) containing ss is weighed at a predetermined ratio. Further, as the polyester B used for the polyester B layer, a polyethylene terephthalate resin (a ") containing a polyethylene terephthalate resin (a) and titanium dioxide is used.

  Then, the mixed polyester resin is supplied to a single screw extruder and melt extruded. At this time, the resin temperature is preferably controlled to 265 ° C to 295 ° C. Next, foreign matter is removed and the amount of extrusion is leveled through a filter and a gear pump, respectively, and discharged from the T die onto a cooling drum in a sheet form. At that time, an electrostatic application method in which a cooling drum and the resin are brought into close contact with each other by static electricity using an electrode applied with a high voltage, a casting method in which a water film is provided between the casting drum and the extruded polymer sheet, The sheet-like polymer is brought into close contact with the casting drum, cooled and solidified by a method of sticking the extruded polymer at a glass transition point to (glass transition point−20 ° C.) or a combination of these methods, and unstretched. Get a film. Among these casting methods, when using polyester, a method of applying an electrostatic force is preferably used from the viewpoint of productivity and flatness.

  The biaxially oriented polyester film for mold release of the present invention needs to be a biaxially oriented film from the viewpoint of heat resistance and dimensional stability. The biaxially oriented film is obtained by stretching an unstretched film in the longitudinal direction and then stretching in the width direction, or by stretching in the width direction and then stretching in the longitudinal direction, or by the longitudinal direction of the film. It can be obtained by stretching by a simultaneous biaxial stretching method in which the width direction is stretched almost simultaneously.

  As a draw ratio in such a drawing method, 2.8 to 3.4 times, more preferably 2.9 to 3.3 times in the longitudinal direction is employed. The stretching speed is preferably 1,000% / min or more and 200,000% / min or less. Moreover, it is preferable that the extending | stretching temperature of a longitudinal direction shall be 70 degreeC or more and 90 degrees C or less. The stretching ratio in the width direction is preferably 2.8 times or more and 3.8 times or less, and more preferably 3 times or more and 3.6 times or less. The stretching speed in the width direction is desirably 1,000% / min or more and 200,000% / min or less. In order to achieve both high tear strength and high breaking strength, the stretching temperature in the width direction is such that the first half temperature of stretching is 90 ° C. or higher and 120 ° C. or lower, the middle temperature of stretching is 100 ° C. or higher and 130 ° C. or lower, and the second half temperature of stretching is 110 ° C. A method of increasing the temperature in the order of the first half temperature of stretching, the first half temperature of stretching, the middle temperature of stretching, and the second half temperature of stretching is preferably employed.

Furthermore, the film is heat-treated after biaxial stretching. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. This heat treatment is performed at a temperature of 120 ° C. or more and below the crystal melting peak temperature of the polyester. In order to achieve high tear strength, the first half temperature of the heat treatment is 180 ° C. or more and less than 220 ° C., and the mid-heat treatment temperature is 220 ° C. or more. It is preferable that the heat treatment second half temperature is 210 ° C. or higher and 220 ° C. or lower. In order to further reduce the heat shrinkage rate, it is also preferable to perform slow cooling at 140 ° C. or more and less than 180 ° C. after the heat treatment.
The heat treatment time can be arbitrarily set as long as the characteristics are not deteriorated, and is preferably 5 seconds to 60 seconds, more preferably 10 seconds to 40 seconds, and most preferably 15 seconds to 30 seconds. Furthermore, the release layer can be coated in-line in order to ensure stable release properties. As a method of providing the coating layer in-line in the film manufacturing process, at least uniaxially stretched film with a coating layer composition dispersed in water is uniformly applied using a metalling ring bar or gravure roll. In addition, a method of drying the coating agent while performing stretching is preferable. In this case, the thickness of the release layer is preferably 0.02 μm or more and 0.1 μm or less. Also, various additives such as antioxidants, heat stabilizers, ultraviolet absorbers, infrared absorbers, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, etc. may be added to the release layer. Good.

  Since the biaxially oriented polyester film for mold release of the present invention has low gloss and high tear propagation resistance, it can be suitably used as a heat-resistant release film as a circuit process film application requiring a matte tone.

(1) Composition of polyester A polyester resin and a film are dissolved in hexafluoroisopropanol (HFIP), and the content of each monomer residue component and by-product diethylene glycol can be quantified using ¹ H-NMR and ¹³ C-NMR. it can. In the case of a laminated film, the components constituting each layer can be collected and evaluated by scraping off each layer of the film according to the laminated thickness. In addition, about the film of this invention, the composition was computed by calculation from the mixing ratio at the time of film manufacture.

(2) Intrinsic viscosity of polyester The intrinsic viscosity of the polyester resin and the film was measured at 25 ° C. using an Ostwald viscometer after dissolving the polyester in orthochlorophenol. In the case of a laminated film, the intrinsic viscosity of each layer can be evaluated by scraping each layer of the film according to the laminated thickness.

(3) Film thickness, layer thickness The film was embedded in an epoxy resin, and the film cross section was cut out with a microtome. The cross section was observed with a transmission electron microscope (TEM H7100, manufactured by Hitachi, Ltd.) at a magnification of 5000 times to determine the film thickness and the thickness of the polyester layer.

(4) Average particle diameter of particles Polyester is removed from the polyester film by plasma low-temperature ashing (PR-503, manufactured by Yamato Kagaku) to expose the particles. This is observed with a transmission electron microscope (TEM H7100, manufactured by Hitachi, Ltd.), and the image of the particles (light density produced by the particles) is linked to an image analyzer (QTM900 manufactured by Cambridge Instrument), and the number of particles is 5000 by changing the observation location. The following numerical processing was performed as described above, and the number average diameter D determined thereby was defined as the average particle diameter.
D = ΣDi / N
Here, Di is the equivalent circle diameter of the particles, and N is the number of particles.

(5) Content of particles 1 g of polymer was put into 200 ml of 1N-KOH methanol solution and heated to reflux to dissolve the polymer. 200 ml of water was added to the solution after dissolution, and the liquid was then centrifuged to settle the particles, and the supernatant was removed. Water was further added to the particles, and washing and centrifugation were repeated twice. The particles thus obtained were dried, and the content of the particles was calculated by measuring the mass of the particles.

(6) Glossiness According to the method defined in JIS-Z-8741 (1997), 60 ° mirror surface on both sides of film (I side / II side) using a digital variable angle gloss meter UGV-5D manufactured by Suga Test Instruments The glossiness was measured for each surface at N = 3, and the average value was adopted for each.

(7) Using a tear propagation resistance load tear tester (manufactured by Toyo Seiki Co., Ltd.), it was measured according to JIS K-7128-2-1998. The sample has a rectangular shape with a length of 75 mm and a width of 63 mm in any one direction (X direction) of the film and a direction orthogonal to the X direction (Y direction). Read the indicated value when the remaining 43 mm is torn. The tear propagation resistance value was obtained by dividing the tear force (N) obtained from the indicated value by the film thickness (mm). The measurement was performed 10 times in each direction, and the average value was adopted.

(8) The breaking strength film was cut into rectangles each having a length of 150 mm and a width of 10 mm in an arbitrary direction (X direction) of the film and a direction orthogonal to the X direction (Y direction), and used as samples. Using a tensile tester (Orientec Tensilon UCT-100) under the conditions of 25 ° C. and 63% Rh, the film was stretched in the longitudinal direction and width direction of the film with a crosshead speed of 300 mm / min, a width of 10 mm, and a sample length of 50 mm. The test is performed, the load applied to the film at the time of breaking is read, and the value divided by the cross-sectional area (laminate thickness x 10 mm) of the sample before the test is taken as the breaking strength. Each measurement was performed 5 times, and the average was used.

(9) Tear propagation resistance after 2 hours of heating and pressing under conditions of 180 ° C. × 3 MPa Aluminum having a thickness of 0.2 mm using a press machine heated to a temperature of 180 ° C. for both the upper mold temperature and the lower mold temperature Plate / 0.125mm thick polyimide film (Toray DuPont Kapton 500H / V) / Release biaxially oriented polyester film / 0.125mm thick polyimide film (Toray DuPont Kapton 500H / V) / Thickness 0 A 2 mm aluminum plate was heated and pressed under a condition of 3 MPa for 2 hours. The biaxially oriented polyester film after hot pressing was taken out and the tear propagation resistance was measured in the same manner as (7).

(10) Amount of carboxyl end groups The polyester A layer was dissolved in cresol / chloroform (weight ratio 7/3) at 95 ° C., and the potential difference was measured with an alkali.

(11) Color tone L value Based on JIS-Z-8722 (2000), using a spectroscopic color difference meter (SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd., light source halogen lamp 12V4A, 0 ° to −45 ° post spectroscopic method) The color tone L value was measured by the reflection method. The measurement was performed in an atmosphere at a temperature of 23 ° C. and a humidity of 65%. Measurements were made by selecting five arbitrary locations on the film, and the average value was adopted. (12) Surface free energy Four types of water, ethylene glycol, formamide, and diiodomethane were used as measurement solutions. The static contact angle with respect to the film surface of each liquid was calculated | required using Interface Science Co., Ltd. CA-D type | mold. Each liquid is measured five times, and the average contact angle (θ) and the surface tension component of the measurement liquid (j) are substituted into the following equations, respectively, and simultaneous equations consisting of four equations are expressed as γ ^L , γ ⁺ , Solved for γ ⁻ .
(Γ ^L γj ^L ) ^1/2 +2 (γ ⁺ γj ⁻ ) ^1/2 +2 (γj ⁺ γ ⁻ ) ^1/2
= (1 + cos θ) [γj ^L +2 (γj ⁺ γj ⁻ ) ^1/2 ] / 2
However, γ = γ ^L +2 (γ ⁺ γ ⁻ ) ^1/2
γj = γj ^L +2 (γj ⁺ γj ⁻ ) ^1/2
Here, γ, γ ^L , γ ⁺ and γ ⁻ are the surface free energy, long-range force term, Lewis acid parameter, and Lewis base parameter of the film surface, respectively, and γj, γj ^L , γj ⁺ , γj ^−. Indicates the surface free energy, long-range force term, Lewis acid parameter, and Lewis base parameter of the measurement solution used. The surface tension of each liquid used here was the value proposed by Oss (“fundamentals of Adhesion”, LH Lee (Ed.), P153, Plenum ess, New York (1991)).
In the biaxially oriented polyester film for mold release according to the present invention, both sides of the film were evaluated, and the value of the surface having low surface free energy was listed in the table.

(13) Peel strength Surface of the biaxially oriented polyester film for mold release of the present invention having a glossiness of 30 or less (surface having a surface free energy of 25 mN / m or more and 40 mN / m or less when glossiness is 30 or less on both surfaces) Nitto Denko Co., Ltd. OPP adhesive tape (Dumplon tape). Glossiness is 30 or less on both sides and surface free energy is 25 mN or more and 40 mN or less. No. 375) was pasted together and cut into a rectangle having a width of 10 mm and a length of 150 mm to obtain a sample. The sample was forcibly peeled between the biaxially oriented polyester film and the OPP adhesive tape layer, and using a tensile tester (Tensilon UCT-100 manufactured by Orientec), the initial tensile chuck distance was 100 mm, and the tensile speed was 20 mm / As a minute, a 180 ° peel test was performed. The measurement was performed until the peel length reached 130 mm (distance between chucks 230 mm), and the average value of the loads having a peel length of 25 mm to 125 mm was defined as the peel strength. The measurement was performed at N = 3, and the average value was adopted.

(14) Heat-resistant peelability The biaxially oriented polyester film for mold release of the present invention has a glossiness of 30 or less (if both surfaces have a glossiness of 30 or less, the surface free energy is 25 mN / m or more and 40 mN / m or less. When the surface is measured, the glossiness is 30 or less on both surfaces, and the surface free energy is 25 mN or more and 40 mN or less, both surfaces are evaluated and the average value is adopted.) Using an applicator, a hard coat layer (manufactured by Kyoeisha Chemical) UF-TCI-1) was coated to a thickness of 40 μm after drying and dried at 80 ° C. for 10 minutes. Thereafter, the sample was cut into a rectangle having a width of 10 mm and a length of 150 mm. Using the laminate, in the same manner as in (9), using a press machine heated to a temperature of 180 ° C. for both the upper mold temperature and the lower mold temperature, an aluminum plate having a thickness of 0.2 mm / thickness of 0. 125mm polyimide film (Toray DuPont Kapton 500H / V) / biaxially oriented polyester film for mold release / HC laminate / thickness 0.125mm polyimide film (Toray DuPont Kapton 500H / V) / thickness 0.2mm The aluminum plate was heated and pressed for 2 hours under the condition of 3 MPa. After heating the press, removed biaxially oriented polyester film / HC laminate was irradiated with ultraviolet rays at an illuminance of 2000 mJ / cm ^2, the releasing property between the biaxially oriented polyester film and the HC layer was evaluated according to the following criteria.
A: The mold release test was performed 10 times, and no film tearing occurred 10 times.

B: The mold release test was performed 10 times, and film breakage occurred 1 to 2 times.
C: The mold release test was performed 10 times, and the film was broken 3 times or more.

(15) Releasability The following criteria evaluated the releasability when the same test as (14) was performed. The peel strength was measured in the same manner as in the method (13).
A: The peel strength of the polyester film / hard coat layer of the present invention was 0.01 N / 10 mm or more and 0.2 N / 10 mm or less.
B: The peel strength of the polyester film / hard coat layer of the present invention was higher than 0.2 N / 10 mm and 1 N / 10 mm or less.
C: The peel strength of the polyester film / hard coat layer of the present invention was higher than 1 N / 10 mm or less than 0.01 N / 10 mm.

(17) High speed transportability Each film is transported at a speed of 150 m / min at unwinding tension: upper unwinding, tension of 300 N / m, winding tension: upper winding, tension of 200 N / m. It was evaluated with.
A: 1000 m or more, which was able to be transported without tearing at all B: Breakage occurred at less than 1000 m.

(Manufacture of polyester)
The polyester resin used for film formation was prepared as follows.

(Polyester A)
Polyethylene terephthalate resin (intrinsic viscosity 0.65) in which the terephthalic acid component is 100 mol% as the dicarboxylic acid component and the ethylene glycol component is 100 mol% as the glycol component.

(Polyester B)
Polyethylene terephthalate resin (intrinsic viscosity 0.8) in which the terephthalic acid component is 100 mol% as the dicarboxylic acid component and the ethylene glycol component is 100 mol% as the glycol component.

(Particle Master C)
Polyethylene terephthalate particle master (intrinsic viscosity 0.65) containing polyester A with aggregated silica particles having a number average particle size of 2.2 μm at a particle concentration of 10% by mass.

(Particle Master D)
Polyethylene terephthalate particle master (intrinsic viscosity 0.65) containing agglomerated silica particles having a number average particle diameter of 3.5 μm in polyester A at a particle concentration of 10% by mass.

(Particle Master E)
Polyethylene terephthalate particle master (intrinsic viscosity 0.65) containing polyester A with agglomerated silica particles having a number average particle size of 5.5 μm at a particle concentration of 10% by mass.

(Particle Master F)
Polyethylene terephthalate particle master (intrinsic viscosity 0.7) containing polyester A with agglomerated silica particles having a number average particle size of 5.5 μm at a particle concentration of 10% by mass.

(Particle Master G)
Polyethylene terephthalate particle master (intrinsic viscosity 0.7) containing polyester A with aluminum silicate particles having a number average particle size of 5.5 μm at a particle concentration of 10% by mass.

(Particle Master H)
Polyethylene terephthalate particles in which divinylbenzene / styrene (20/80) crosslinked particles having a number average particle size of 5.5 μm are added to polyester A so as to have a particle concentration of 10% by mass, and the particles are contained at a particle concentration of 10% by mass. Master (intrinsic viscosity 0.7).

(Titanium dioxide master)
Polyethylene terephthalate particle master (inherent viscosity 0.6) containing 50% by mass of anatase-type titanium dioxide in polyester A.

(Release layer forming solution (water dispersion)
The following crosslinking agent: binder resin: release agent: particles were mixed at a mass ratio of 60:23:17, respectively, and diluted with pure water to adjust the solid content to 1%.
・ Crosslinking agent: Methylated melamine / urea copolymer cross-linked resin (“Nicarac” (registered trademark) “MW12LF” manufactured by Sanwa Chemical Co., Ltd.))
-Binder resin I: Acrylic monomer copolymer (Nippon Carbide)
Release agent III: CF ₃ (CF ₂ ) _n CH ₂ CH ₂ OCOCH═CH ₂ (n = 5 to 11, n average = 9) 80 which is a perfluoroalkyl group-containing acrylate in a glass reaction vessel 0.0 g, acetoacetoxyethyl methacrylate 20.0 g, dodecyl mercaptan 0.8 g, deoxygenated pure water 354.7 g, acetone 40.0 g, C ₁₆ H ₃₃ N (CH ₃ ) ₃ Cl 1.0 g and C ₈ H ₁₇ C Add 3.0 g of ₆ H ₄ O (CH ₂ CH ₂ O) _n H (n = 8), add 0.5 g of azobisisobutylamidine dihydrochloride, and stir in a nitrogen atmosphere at 60 ° C. for 10 hours. A copolymer emulsion obtained by polymerization reaction.
Particles: Obtained by diluting silica particles having a number average particle diameter of 170 nm (“Snowtex” (registered trademark) MP2040 manufactured by Nissan Chemical Industries, Ltd.) with pure water so that the solid content concentration becomes 40% by weight. Water dispersion.

Hereinafter, Examples 5, 6, 14, 15, 20-22 are read as Reference Examples 1-7.
Example 1
The composition is as shown in the table, and the raw materials are supplied to separate single screw extruders each having an oxygen concentration of 0.2% by volume, and the A layer extruder cylinder temperature is 270 ° C. and the B layer extruder cylinder temperature is melted at 270 ° C. Then, the short tube temperature after joining the A layer and B layer is set to 275 ° C, the die temperature is set to 280 ° C, and the resin temperature is 280 ° C. did. At that time, a wire electrode having a diameter of 0.1 mm was applied electrostatically and adhered to the cooling drum to obtain an unstretched sheet. Next, the film temperature was raised with a heated roll before stretching in the longitudinal direction, and the film was stretched 3.1 times in the longitudinal direction at a stretching temperature of 85 ° C., and immediately cooled with a metal roll whose temperature was controlled at 40 ° C. Thereafter, a corona discharge treatment was applied, and a release layer forming solution (aqueous dispersion) was applied using a metalling bar so that the wet thickness became 13.5 μm, and then the first half temperature of stretching with a tenter type horizontal stretching machine The film is stretched 3.4 times in the width direction at 95 ° C., a stretching intermediate temperature of 110 ° C., a stretching latter half temperature of 140 ° C., and is directly subjected to heat treatment in the tenter at a heat treatment first half temperature of 200 ° C. and a heat treatment middle temperature of 230 ° C. Heat treatment was performed at 170 ° C. while relaxing 5% in the width direction, and the film thickness was 50 μm (lamination ratio is as shown in the table) and the release layer thickness was 40 nm. An axially oriented polyester film was obtained.

(Example 2)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 3)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

Example 4
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 5)
The heat treatment conditions after stretching in the width direction were the same as in Example 4 except that the first half temperature of the heat treatment was 230 ° C., the middle temperature of the heat treatment was 230 ° C., and the annealing temperature was 170 ° C. with 5% relaxation in the width direction. Thus, a biaxially oriented polyester film having a film thickness of 50 μm was obtained.

(Example 6)
Stretching conditions in the width direction were 95 ° C. for the first half of the stretching, 110 ° C. for the first half of the stretching, and 140 ° C. for the second half of the stretching. A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 4 except that the heat treatment was performed at 230 ° C., and the annealing was performed at a slow cooling temperature of 170 ° C. while relaxing 5% in the width direction.

(Example 7)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 8)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

Example 9
Stretching conditions in the width direction were a first half temperature of stretching 110 ° C., a middle stretching temperature of 110 ° C., a second half stretching temperature of 110 ° C., and stretched 3.4 times in the width direction. A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 8, except that the heat treatment was performed at 230 ° C., and the annealing was performed at a slow cooling temperature of 170 ° C. while relaxing 5% in the width direction.

(Example 10)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 11)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 12)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 13)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 14)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

(Example 15)
The temperature of the A-layer extruder cylinder was 280 ° C, the temperature of the B-layer extruder cylinder was 280 ° C, the short tube temperature after joining the A-layer and B-layer was set to 285 ° C, and the die temperature was set to 290 ° C. A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 14 except that the sheet was discharged at 290 ° C. onto a cooling drum controlled to 25 ° C. from a T die.

(Example 16)
After stretching in the longitudinal direction, the film thickness was 50 μm in the same manner as in Example 11 except that the corona discharge treatment and the release layer forming solution (aqueous dispersion) were not applied and were stretched in the width direction with a tenter-type transverse stretching machine. A biaxially oriented polyester film was obtained.

(Example 17)
After stretching in the longitudinal direction, a film thickness of 50 μm was obtained in the same manner as in Example 2 except that the corona discharge treatment and the release layer forming solution (aqueous dispersion) were not applied, but were stretched in the width direction with a tenter-type lateral stretching machine. A biaxially oriented polyester film was obtained.

(Example 18)
After stretching in the longitudinal direction, the film thickness was 50 μm in the same manner as in Example 3 except that the corona discharge treatment and the release layer forming solution (aqueous dispersion) were not applied and the film was stretched in the width direction with a tenter-type transverse stretching machine. A biaxially oriented polyester film was obtained.

(Example 19)
The biaxially oriented polyester film obtained in Example 16 was coated with a release layer forming solution (aqueous dispersion) using a metalling bar so that the wet thickness was 5 μm, and dried at 120 ° C. for 1 minute. It was.

(Example 20)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the film had a two-layer structure and the composition was changed as shown in the table.

(Example 21)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was a single film and the composition was changed as shown in the table.

(Example 22)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was a single film and the composition was changed as shown in the table.

(Comparative Example 1)
Stretching conditions in the width direction were 95 ° C. for the first half of the stretching, 110 ° C. for the first half of the stretching, and 140 ° C. for the second half of the stretching. A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 19 except that the heat treatment was performed at 230 ° C., and the annealing was performed at a slow cooling temperature of 170 ° C. while relaxing 5% in the width direction.

(Comparative Example 2)
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the composition was changed as shown in the table.

Since the biaxially oriented polyester film of the present invention has a low glossiness and a high tear propagation resistance, it can be suitably used as a heat-resistant release film as a circuit process film application requiring a matte tone.

Claims (8)

Measured from the polyester A layer side of the outermost layer having a polyester A layer containing 1 to 10% by mass or less of inorganic particles and / or organic particles based on 100% by mass of the entire polyester A layer. The biaxiality for mold release having a gloss value of 30 or less and an average value of tear propagation resistance in an arbitrary direction (X direction) of the film and a direction perpendicular to the X direction (Y direction) of 6.5 N / mm or more Oriented polyester film. Moreover, the average value of the breaking strength in 25 degreeC of the X direction of the said film and a Y direction is 150-250 MPa. The amount of carboxyl end groups of the polyester A layer is 20 eq / t or less. The biaxial for mold release according to claim 1, wherein an average value of breaking strength at 25 ° C in any one direction (X direction) of the film and in a direction orthogonal to the X direction (Y direction) is 150 MPa or more and 250 MPa or less. Oriented polyester film. The average value of the tear propagation resistance in any one direction (X direction) and the direction orthogonal to the X direction (Y direction) after heat pressing for 2 hours under the condition of 180 ° C. × 3 MPa is 5 N / mm It is the above, The biaxially-oriented polyester film for mold release of Claim 1 or 2. The biaxially oriented polyester film for mold release according to any one of claims 1 to 3, wherein the amount of carboxyl end groups of the polyester A layer is 20 eq / t or less. The biaxially oriented polyester film for mold release according to any one of claims 1 to 4, further comprising a polyester B layer having a smaller content of inorganic particles and / or organic particles than the polyester A layer. The biaxially oriented polyester film for mold release according to any one of claims 1 to 5, wherein the color tone L value is from 60 to 80. The biaxially oriented polyester for mold release according to any one of claims 1 to 6, wherein the gloss measured from the polyester A layer side of the outermost layer is 30 or less and the surface free energy is 25 mN / m or more and 40 mN / m or less. the film. Nitto Denko Co., Ltd. OPP adhesive tape (Damplon tape No. 375) and the release biaxially oriented polyester film were bonded together on the surface having a glossiness of 30 or less, and the peel strength required by the following measurement method Is 0.02 N / 10 mm or more and 2 N / 10 mm or less, The biaxially oriented polyester film for mold release according to claim 1.
(Measurement method) The biaxially oriented polyester film for mold release of the laminate of the present invention and Nitto Denko Co., Ltd. OPP adhesive tape (Damplon Ace No. 375) were bonded together and cut into a rectangle with a width of 10 mm and a length of 150 mm. The sample was forcibly peeled between the biaxially oriented polyester film for release and the OPP pressure-sensitive adhesive tape layer, and an initial tensile chuck distance of 100 mm using a tensile tester (Orientec Tensilon UCT-100). The 180 ° peel test is performed at a tensile speed of 20 mm / min. Measurement is performed until the peel length reaches 130 mm (distance between chucks 230 mm), and the average value of the loads having a peel length of 25 mm to 125 mm is defined as the peel strength.