JP5915542B2 - Laminated polyester film and method for producing the same - Google Patents

Description

  The present invention relates to a laminated film having peelability, and more particularly to a laminated polyester film suitable as a process film that requires peelability in a processing step.

  Polyester film, especially polyethylene terephthalate biaxially stretched film has excellent mechanical properties, heat resistance or chemical resistance, etc., so magnetic tape, photographic film, packaging film, diazo easy adhesion film, capacitor metalizing film It is widely used as a material for electrical insulation film or literary film. One of the fields is the field of process films for manufacturing electronic components such as ceramic capacitors, ceramic substrates, dry film resists, and polarizing plates.

  Polyester film alone, when used for various mold release materials, has a poor peeling effect, and there are places where the resin and the mold release material adhere to each other, and there are cases where adhesion occurs between the mold release film and the resin, which is satisfactory. It was not a thing and could not be used at all.

  For this reason, films with improved release properties by applying a release layer such as a curable silicone resin film on the surface of polyester film are process films for manufacturing electronic parts, especially ceramic multilayer capacitors, process sheets for forming ceramic sheets, and polarizing films. It is used in large quantities as a release film.

  In this release layer coating process, there are not a few process losses including uneven coating thickness and wrinkles during heating. Although the process loss reduction in this process is progressing, the effect has a limit.

  Moreover, the film which apply | coated the release layer, such as a curable silicone resin film | membrane, to the surface of a polyester film has a subject in the collectability of a polyester film, when it uses it as a process sheet for ceramic sheet forming, or a polarizing plate release film. When a film in which a release layer such as a curable silicone resin film is applied to the surface of the polyester film is used as a process sheet for forming a ceramic sheet, the remaining film or ceramic is cured in the process film after chip cutting from the ceramic sheet. As a result, the polyester film cannot be easily separated and recovered. Similarly, when a film having a release layer such as a curable silicone resin film applied to the surface of a polyester film is used as a polarizing plate release film, the curable silicone resin is adhered to the film peeled off from the polarizing plate. This is a factor that hinders recoverability.

  As means for solving this problem, a peelable laminated film (Patent Document 1) having a layer composed of polyvinyl alcohol on its surface has been proposed. In addition, a polyester film (Patent Documents 2, 3, 4, and 5) to which a wax component is added has been proposed as a material that provides releasability in place of a release layer such as a curable silicone resin film.

Japanese Patent Laid-Open No. 2003-118058 JP 2002-187963 A JP 2005-342911 A JP 2006-326902 A JP 2002-264258 A

  However, when the technique described in Patent Document 1 is employed, the number of steps to be removed increases when a layer composed of polyvinyl alcohol adheres to the object after peeling. Moreover, when the layer comprised from polyvinyl alcohol has adhered to the film, the process which removes in the case of reuse will generate | occur | produce, productivity will fall and it will become costly.

  Moreover, although the film of patent document 2 has an effect which reduces the adhesion amount to films, such as foodstuff, the peeling effect is inadequate to apply as a process film for ceramic green sheet shaping | molding, or a polarizing plate release use film There is a problem that it is inappropriate.

  According to Patent Document 3, the polyester resin layer contains a wax component in a predetermined concentration range, and the surface orientation coefficient of the resin layer in the polyester resin layer containing the wax component is controlled within a certain range to exhibit a peeling effect. Although it is a thing, the peeling effect is inadequate. Moreover, although patent document 4 makes a polyester resin layer contain a wax component in the predetermined | prescribed density | concentration range, unless a film is heated to about 125-135 degreeC, sufficient peelability cannot be expressed. In Patent Document 5, it is possible to obtain good moldability and impact resistance by controlling the crystal size of the (100) plane obtained by X-ray diffraction measurement in a film containing a wax component to 6.0 nm or less. Although shown, its release effect is not sufficient.

  As described above, simply applying the techniques of Patent Documents 1 to 5 has a problem that the peeling effect is insufficient for use as a process film for forming a ceramic green sheet or as a polarizing plate release application film. is there.

  Accordingly, an object of the present invention is to provide a polyester film that can be used for ceramic green sheet molding applications, polarizing plate release applications, and the like, and has sufficient releasability without applying a release layer. There is to do.

  As a result of intensive studies on a process film that can be easily peeled off from a ceramic green sheet or a polarizing plate without using a curable silicone resin, the present invention has the following characteristics. It has been clarified that the problem can be solved at once.

(1) A biaxially oriented laminated polyester film having at least a polyester A layer and a polyester B layer, wherein the outermost layer on at least one side of the biaxially oriented laminated polyester film is a polyester A layer containing a wax component, and polyester A Biaxially oriented laminate in which the polyester A layer satisfies the following formulas (1) and (2) when the concentration of the wax component contained in the layer is WA (% by weight) and the thickness of the polyester A layer is TA (μm) Polyester film 0.8 ≦ WA ... Formula (1)
0.4 <= WA / TA <= 20 ... Formula (2).

(2) The biaxially oriented laminated polyester film according to (1), wherein the concentration of the wax component contained in the polyester A layer is WA (% by weight), the thickness of the A layer is TA (μm), and the polyester film X The polyester A layer satisfies the following formulas (3), (4), and (5) when the crystal size of the (100) plane obtained by line diffraction measurement is χc (nm). Axial oriented laminated polyester film 0.8 ≤ WA ≤ 5.0 ... (3)
0.3 ≦ TA ≦ 5.0 Formula (4)
χc> 6.0 Formula (5).

(3) The biaxially oriented laminated polyester film according to (1), wherein the concentration of the wax component contained in the polyester A layer is WA (% by weight), the thickness of the A layer is TA (μm), and the polyester film X When the crystal size of the (100) plane obtained by the line diffraction measurement is χc (nm), the polyester A layer satisfies the following formulas (3), (4), and (6). Biaxially oriented laminated polyester film obtained by aging treatment for 24 hours or more under a temperature condition of from 0 to 70 ° C. 0.8 ≦ WA ≦ 5.0 Formula (3)
0.3 ≦ TA ≦ 5.0 Formula (4)
4.0 ≦ χc ≦ 6.0 Equation (6).

  (4) The polyester film according to (1) to (3), wherein the wax component is carnauba wax and / or stearyl stearate.

(5) The biaxial orientation according to any one of (1) to (4), wherein the concentration WB of the wax component in the polyester B layer satisfies the following formula (7) with respect to the polyester B layer: Laminated polyester film 0 ≦ WB <0.6 (7).

  (6) The biaxially oriented laminated polyester film according to any one of (1) to (5), which is used as a polarizing plate release film or a process sheet for forming a ceramic sheet.

  (7) The biaxially oriented laminated polyester film according to any one of (1) to (6), wherein the polymer constituting the polyester film is substantially composed of one kind of dicarboxylic acid and one kind of diol.

(8) A method for producing a biaxially oriented laminated polyester film having at least a polyester A layer and a polyester B layer, wherein at least one outermost layer is a polyester A layer containing a wax component, wherein the polyester A layer is (A) A method for producing a biaxially oriented laminated polyester film formed by a method having the steps (A), (B) and (C) in that order. (A) A polyester composition constituting a polyester film by adding a wax component to polyester. (B) A polymer melted using the polyester composition is coextruded to form A layer and B layer, and the polyester A layer is formed so as to satisfy the following formulas (2), (3), and (4): Step of adjusting the concentration WA (% by weight) of the wax component to be contained and the thickness TA (μm) of the layer A 0.8 ≦ WA ≦ 5.0 (2)
0.3 ≤ TA ≤ 5.0 ... Formula (3)
0.4 ≦ WA / TA ≦ 20 (4)
(C) Adjusting the crystal size χc to satisfy the following formula (5) when the crystal size of the (100) plane obtained by X-ray diffraction measurement of the polyester film is χc (nm): χc> 6. 0 Formula (5).

(9) A method for producing a biaxially oriented laminated polyester film having at least a polyester A layer and a polyester B layer, wherein at least one outermost layer is a polyester A layer containing a wax component, wherein the polyester A layer is (A) A method for producing a biaxially oriented laminated polyester film formed by a method having the steps (A), (B), (D), and (E) in that order. (A) A polyester film is formed by adding a wax component to polyester. Obtaining a polyester composition.

(B) A wax component contained in the polyester A layer so as to satisfy the following formulas (2), (3), and (4) by coextrusion of the polymer melted using the polyester composition to form the A layer and the B layer. Step of adjusting the concentration WA (% by weight) and the thickness TA (μm) of the layer A 0.8 ≦ WA ≦ 5.0 (2)
0.3 ≤ TA ≤ 5.0 ... Formula (3)
0.4 ≦ WA / TA ≦ 20 (4)
(D) Adjusting the crystal size χc so that the following formula (6) is satisfied when the crystal size of the (100) plane obtained by X-ray diffraction measurement of the polyester film is χc (nm): 4.0 ≦ χc ≦ 6.0 (6)
(E) The process of performing the aging process for 24 hours or more on 30 degreeC-70 degreeC temperature conditions after forming a film.

  According to the present invention, since the ceramic green sheet and the polarizing plate can be easily peeled off from the surface of the polyester film, the step of forming a release layer such as a curable silicone resin layer which is conventionally required is omitted, and the cost is greatly reduced. And process loss reduction in an intermediate process can be realized.

  Hereinafter, the present invention will be described in more detail.

  The laminated polyester film of the present invention has at least a polyester A layer and a polyester B layer.

  The polyester constituting the polyester A layer and the polyester B layer is preferably polyethylene terephthalate, a copolymer of ethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, a copolymer of butylene terephthalate and ethylene terephthalate, or butylene. Copolymers of terephthalate and hexamethylene terephthalate, copolymers of hexamethylene terephthalate and 1,4-cyclohexanedimethylene terephthalate, copolymers of ethylene terephthalate and ethylene-2,6-naphthalate, and blends thereof Can be used.

  In addition, for the purpose of improving the moldability and handling of the film within the range that does not impair the effects of the present invention, the polyester may be a polyfunctional compound such as trimellitic acid, trimesic acid, pentaerythritol, trimethylolpropane, glycerin or the like. -An oxydicarboxylic acid such as oxybenzoic acid may be copolymerized.

  The polyester constituting the polyester A layer and the polyester B layer has a diethylene glycol component amount of 0.01 to 4% by weight, more preferably 0.01 to 3% by weight, and particularly preferably 0.01 to 2% by weight. It is desirable to maintain good structural control and maintain good structural control even after elapse of time or after receiving a thermal history during processing. Further, an antioxidant may be added in an amount of 0.0001 to 1% by weight. Further, diethylene glycol may be added during the production of the polymer as long as the characteristics are not impaired.

On the other hand, it is preferable that the polymer which comprises the laminated polyester film of this invention as a preferable form substantially consists of 1 type of dicarboxylic acid and 1 type of diol. The reason for this is that if it is composed of multiple types of diols and dicarboxylic acids, the repeating units in the polymer will vary, and the difference in length will prevent crystallization and control the crystal size within the desired range. It becomes difficult. In addition, when the laminated polyester film of the present invention is used for ceramic green sheet molding, a thermal history is applied in the drying process of the coating layer after applying the green sheet or adhesive material, but there are many amorphous parts of the polyester. This is because if it is too large, it may be affected by this thermal history and cause dimensional change or deformation.
In the present invention, the polyester consisting essentially of one type of dicarboxylic acid and one type of diol refers to a polyester obtained using one type of dicarboxylic acid and one type of diol as a raw material for synthesizing the polyester. Represent.

  Moreover, in order to optimize the protrusion height and surface roughness of the film layer surface, the polyester constituting the polyester A layer and the polyester B layer can contain inert particles.

  For the above-mentioned inert particles, 0.2 to 1.0% by weight of inert particles having an average particle size of 0.5 to 2.5 μm, preferably 0.8 to 1.3 μm, more preferably 0.3 to 0%. It is preferable to contain 8% by weight.

  As the kind of inert particles, inorganic particles such as spherical silica, aluminum silicate, titanium dioxide, calcium carbonate, and other organic polymer particles include crosslinked polystyrene resin particles, crosslinked silicone resin particles, crosslinked acrylic resin particles, Crosslinked styrene-acrylic resin particles, crosslinked polyester particles, polyimide particles, melamine resin particles and the like are preferable. These 1 type (s) or 2 or more types can also be selected and used.

  These inert particles can be added at the stage of the polyester polymerization process to prepare an inert particle-containing polymer. For example, by making a slurry of ethylene glycol, which is a glycol component of polyester, adding an inert particle-containing slurry after transesterification before polycondensation or at the oligomer stage after esterification, and subsequently performing a polycondensation reaction, An inert particle-containing polymer can be obtained. Moreover, it is also possible to obtain a polymer containing inert particles by putting the polyester chips and inert particles after polymerization into a biaxial kneading extruder and kneading them.

  Moreover, in the polyester which comprises the polyester A layer and the polyester B layer, the terminal carboxyl group amount of polyester is 25-55 equivalent / ton from the point which improves the compatibility with the wax component (especially carnauba wax) mentioned later. It is preferable that More preferably, it is 30-50 equivalent / ton, Most preferably, it is 35-45 equivalent / ton. A polyester having a terminal carboxyl group amount of more than 55 equivalents / ton reduces the hydrolysis resistance of the film and tends to cause thermal degradation. Further, in order to obtain a polyester having a terminal carboxyl group amount of less than 25 equivalents / ton, it is necessary to go through another process such as solid phase polymerization after polymerization, which is not practical in terms of cost.

  In the present invention, the polyester A layer needs to contain a wax component, and the polyester A layer needs to be the outermost layer on at least one side of the biaxially oriented laminated polyester film.

  By using the polyester A layer containing the wax component as the outermost layer, the peeling performance of the surface of the A layer can be improved, and it can be used for ceramic green sheet forming applications, polarizing plate release films, and the like.

  As the wax component, stearyl stearate or carnauba wax is preferably used from the viewpoint of compatibility with polyester. That is, in the present invention, the polyester A layer preferably contains stearyl stearate and / or carnauba wax as a wax component. In particular, from the viewpoint of peelability of the ceramic green sheet, it is preferable to contain carnauba wax, and it is particularly preferable to use purified carnauba wax.

In the present invention, the concentration WA (% by weight) of the wax component in the polyester A layer must satisfy the following formula (1): 0.8 ≦ WA (1)

When the concentration WA of the wax component is less than 0.8% by weight, the releasability due to the wax component is not sufficiently exhibited, and it is bonded via a ceramic green sheet or an adhesive applied on the polyester A layer. It becomes impossible to peel off the polarizing plate easily. On the other hand, when WA is greater than 5.0% by weight, the effect of improving the releasability is saturated, which not only causes a high cost, but also the kneading of the wax component becomes uneven in the resin production process, It also causes productivity deterioration. As a preferable range of WA for the reasons described above, 0.8 ≦ WA ≦ 5.0 (Expression (3)), which is a range represented by the following expression (3).

On the other hand, if WA exceeds 2.0% by weight, surface defects tend to occur on the film surface, and the surface defects may be the starting point, and the peelability may be non-uniform. Accordingly, a more preferable range of WA is a range represented by the following formula (3 ′): 0.8 ≦ WA ≦ 2.0 (formula (3 ′)).

Moreover, it is necessary for the laminated polyester film of this invention to satisfy following formula (2). 0.4 <= WA / TA <= 20 ... Formula (2).
Here, TA is the thickness (μm) of the polyester A layer, and WA is the concentration (% by weight) of the wax component of the polyester A layer.

  When WA / TA <0.4, the releasability due to the wax component is not sufficiently exhibited. When WA / TA> 20, the releasability due to the wax component does not appear uniformly. For this reason, the ceramic green sheet applied on the polyester A layer or the polarizing plate bonded via the adhesive cannot be easily peeled off.

  The reason why the peeling performance on the surface of the polyester A layer is improved by satisfying the above-mentioned formula (2) is that the wax component contained in the polyester A layer diffuses to the film surface when undergoing a film manufacturing process involving stretching and heat treatment. It is estimated that That is, for the diffusion of the wax component, the movement distance to the surface of the wax component and the concentration of the wax component contribute, so it is presumed that the relationship represented by the above formula (2) is necessary.

The laminated polyester film of the present invention preferably satisfies the following formula (4) when TA is the thickness (μm) of the polyester A layer: 0.3 ≦ TA ≦ 5.0 (4) ).

  When TA is less than 0.3 μm, unevenness in the peel direction is likely to occur when unevenness in the thickness direction occurs in the laminated state of the polyester A layer during film formation, and when TA is greater than 5 μm, per unit area of the film. The amount of the polymer containing the wax component to be used is large and is not desirable in terms of cost.

  In the laminated film of the present invention, it is preferable that the following formula (5) is satisfied with respect to the crystal size χc (nm) of the (100) plane obtained by X-ray diffraction measurement.

    χ c> 6.0 Formula (5).

  By satisfying the formula (5), the wax component in the polyester more effectively contributes to the peelability. The reason why the releasability is improved when the crystal size χc is increased is presumed that the wax component cannot be present in the crystal portion in the polyester, and therefore the wax component moves to the amorphous portion when the crystal size χc is increased.

  However, when χc is 9.0 nm or more, the crystal size in the film is large, so that the strength of the film tends to be lowered, and there is a risk that the film is cleaved during processing. Therefore, a more preferable range of χc is larger than 6.0 nm and smaller than 9.0 nm.

Next, the crystal size χc (nm) of the (100) plane obtained by X-ray diffraction measurement of the laminated polyester film of the present invention will be described in the case of the following formula (6) 4.0 ≦ χc ≦ 6.0 -Formula (6).

  When χc is 6.0 nm or less, the crystal size in the film is small, and the above-described effects are insufficient. However, in the case of a film having a crystal size χc within the range of formula (6), the wax component diffuses on the surface by performing an aging treatment for 24 hours or more at a temperature of 30 ° C. to 70 ° C. after the film is formed. As a result, the peelability is improved. On the other hand, if χc is less than 4.0 nm, the effect of improving the peelability cannot be sufficiently obtained even if the aging treatment is performed. The aging treatment referred to in the present invention means that the film after film formation is left in an environment of a set temperature condition.

  If the temperature at which the aging treatment is performed is less than 30 ° C., the effect of diffusing the wax component is small. A more preferable aging temperature is 40 ° C. or higher, and further preferably 50 ° C. or higher.

If the time for performing the aging treatment is 24 hours or more, an effect of promoting the diffusion of the wax component to the surface can be obtained. Even after aging for 150 hours or more, the effect of the wax component diffusing to the surface is saturated, and only the productivity is deteriorated.
Of course, aging treatment may be performed on a film having χc larger than 6.0 nm. However, the effect of improving the peelability is saturated, which causes high cost.

  The polyester B layer may contain a wax component as long as the effects of the present invention are not adversely affected. However, the concentration WB of the wax component in the polyester B layer preferably satisfies the following formula (7).

    0 ≦ WB <0.6 (7).

  That is, the concentration of the wax component in the polyester B layer is preferably 0% by weight or more and less than 0.6% by weight, and particularly preferably 0.4% by weight or less. In particular, when the laminated polyester film of the present invention has a two-layer configuration of A layer / B layer, when the concentration WB of the wax component in the polyester B layer is 0.6% by weight or more, the layers constituting both sides of the laminated polyester film Since the wax component is included, friction on either side of the film is reduced, which causes problems such as wrinkling and meandering in the film forming and post-processing transport rolls. Further, as described above, it is estimated that the peeling performance on the surface of the polyester A layer is expressed by the diffusion of the wax component contained in the polyester A layer to the film surface. Since the diffusion rate of the wax from the layer B to the layer B is fast, there is a place where the concentration of the wax component is locally high near the boundary of the layer AB, but the diffusion amount of the wax component from the layer A to the layer B is low. However, when the concentration of the wax component in the B layer becomes high and the concentration of the wax component in the polyester B layer becomes 0.6% by weight or more, the diffusion rate of the wax component from the A layer to the B layer becomes slow, but the diffusion proceeds slowly. However, since the diffusion amount of the wax component is increased, it is presumed that the diffusion of the wax component to the surface sufficient to develop the peeling performance of the polyester A layer surface does not occur.

  In the present invention, the maximum protrusion height (Rmax) on the surface of the polyester A layer is preferably 1.5 μm or less, more preferably 1.0 μm or less. If the height of the protrusion is higher than 1.5 μm, defects are likely to enter the formed ceramic green sheet or the like to be peeled, and a depression of the adhesive layer is generated, which is not preferable.

  In order to make the maximum protrusion height within the above range, it is preferable to control the average particle diameter of the inert particles contained in the polyester A layer. The average particle diameter of the inert particles contained in the polyester A layer is preferably 1.5 μm or less.

  The thickness of the laminated polyester film of the present invention is preferably 15 μm or more, more preferably 25 μm or more, and further preferably 40 μm or more. If the thickness is less than 15 μm, there is no rigidity, and there is a possibility that problems such as wrinkles and breakage may occur when the green sheet is peeled off or peeled off from the polarizing plate. On the other hand, due to the property of peeling the film itself, a film having a thickness of 250 μm or more may be unpreferable because it is costly to recover.

  The laminated polyester film of the present invention needs to have at least two layers of a polyester A layer and a polyester B layer, but polyester A layer / polyester B layer / polyester A layer or polyester A layer / polyester B layer / It may be a three-layer structure such as a polyester C layer, or may be a multilayer structure having more layers than three layers. A two-layer structure consisting of a polyester A layer / polyester B layer or a three-layer structure consisting of a polyester A layer / polyester B layer / polyester C layer is preferred. The polyester C layer refers to a layer that does not correspond to the polyester A layer or the polyester B layer.

  Although the manufacturing method of the laminated polyester film of this invention is described below, this invention is limited to what was obtained by the following manufacturing methods, and is not interpreted.

  The laminated polyester film of the present invention is preferably formed by a method having the steps (A), (B), and (C) or (A), (B), (D), and (E) in that order.

  (A) The process of adding the wax component to polyester and obtaining the polyester composition which comprises a polyester film.

(B) A polymer melted using the polyester composition is coextruded to form A layer and B layer, and contained in the polyester A layer so as to satisfy the following formulas (2), (3), (4), and (7) Adjusting the concentration WA (wt%) of the wax component, the thickness TA (μm) of the A layer, and the concentration WB (wt%) of the wax component contained in the polyester B layer 0.8 ≦ WA ≦ 5.0・ Formula (2)
0.3 ≤ TA ≤ 5.0 ... Formula (3)
0.4 ≦ WA / TA ≦ 20 (4)
0 ≦ WB <0.6 (7).

(C) Step of adjusting the crystal size χc so as to satisfy the following formula (5) when the crystal size χc (nm) of the (100) plane obtained by X-ray diffraction measurement of the polyester film χc> 6.0 ... Formula (5).

(D) A step of adjusting the crystal size χc so as to satisfy the following formula (6) when the crystal size χc (nm) of the (100) plane obtained by X-ray diffraction measurement of the polyester film is set: 4.0 ≦ χc <= 6.0 ... Formula (6).

  (E) The process of performing the aging process for 24 hours or more on 30 degreeC-70 degreeC temperature conditions after forming a film.

First, the process (A) will be described below.
(A) A step of adding a wax component to polyester to obtain a polyester composition.

  In the step (A), the method of adding the wax component to the polyester is not particularly limited, but from the viewpoint of improving the dispersibility of the wax component and exhibiting stable performance and suppressing contamination in the film forming step. The method of adding at the following polymerization processes is preferable. (1) A method of adding a wax component in the polyester polymerization step. (2) A polyester composition containing a large amount of a wax component (sometimes referred to as “master polymer” or “wax master polyester”) is produced, and a polyester composition containing no or a small amount of a wax component (diluted polyester) ) And a predetermined amount are mixed and kneaded.

  In the present invention, when carnauba wax is used as the wax component, when carnauba wax is incorporated into the polyester by the method (1), polymerization using a germanium catalyst is particularly effective in improving dispersibility. Is particularly preferred. It is preferable that 1 to 200 ppm of germanium element is contained in the polyester composition, more preferably 10 to 100 ppm, and particularly preferably 20 to 80 ppm. When obtaining a polyester composition containing carnauba wax by the method (2), the carnauba wax master polymer is not limited to the germanium catalyst as described above.

  Next, the process of (B) is demonstrated below.

The polymer melted using the polyester composition is coextruded to form the A layer and the B layer, and the concentration WA of the wax component contained in the polyester A layer so as to satisfy the following formulas (2), (3), and (4) (Weight%), thickness TA of layer A (μm), step of adjusting the concentration WB (weight%) of the wax component contained in the polyester B layer 0.8 ≦ WA ≦ 5.0 (2)
0.3 ≤ TA ≤ 5.0 ... Formula (3)
0.4 <= WA / TA <= 20 ... Formula (4).

  In the laminated polyester film of the present invention, for example, after drying each polyester raw material, it is supplied to two or more known extruders, and the polyester A layer is the outermost layer (the outermost layer using two or more manifolds and merging blocks). After being laminated so as to form an outer layer and melt-extruding (melt-coextrusion) from a slit-shaped die into a sheet shape, it can be produced by a biaxial stretching method described later.

  The method of supplying the dried raw material to the extruder includes (I) a method of supplying the polyester composition to which the wax component is added in the polyester polymerization step to the extruder, and (II) the wax component manufactured in the step of (A). A method for producing a polyester composition with a large amount of added and supplying a predetermined amount of a polyester composition (diluted polyester) containing no or a small amount of a wax component, and (III) a polyester or a wax component is required. Depending on the method, after drying, there is a method of supplying directly to the extruder. In the method (III), a wax component is added to the polyester to obtain a polyester composition in an extruder, and the polyester composition that has undergone step (A) is melt-extruded as it is into a sheet. It can adjust so that Formula (2) (3) (4) may be satisfy | filled by these (I) (II) (III). Of these, the method (II) is preferable because the concentration of the wax component can be easily adjusted.

  Further, when extruding the prepared raw material, even a very small foreign object becomes a film defect, and therefore, a high-precision filter that collects 95% or more of a foreign substance having a size of 25 μm or more is used and discharged from the extruder. It is effective to filter the polymer through a filter.

  As a manufacturing method of a biaxially oriented film, after extruding into a sheet form from a slit-shaped die, it is brought into close contact with a casting drum by a method such as electrostatic application, and cooled and solidified to obtain an unstretched sheet. The obtained unstretched sheet is stretched.

  Next, the steps (C) and (D) performed after the stretching step will be described below.

  In the steps (C) and (D), the crystal size χc when the crystal size χc (nm) of the (100) plane obtained by the X-ray diffraction measurement of the polyester film is adjusted.

  In the step (C), the crystal size χc is adjusted so as to satisfy both of the expressions (5), and in the step (D), the crystal size χc is adjusted so as to satisfy both of the expressions (6).

χ c> 6.0 (5)
4.0 ≦ χc ≦ 6.0 Expression (6)
In order to achieve the above crystal size χc, it is necessary to combine stretching conditions (stretching area ratio (longitudinal stretching ratio × lateral stretching ratio)) and heat treatment conditions (heat treatment temperature, heat treatment time). The lower the area ratio for stretching, the smaller the crystal size, the higher the heat treatment temperature, the larger the crystal size, and the longer the heat treatment time, the larger the crystal size.

  When polyethylene terephthalate is used as the polyester, an example of a combination in which the crystal size χc is about 6.0 nm is a combination of an area magnification of 15.2 times, a heat treatment temperature of 225 ° C., and a heat treatment time of 6 seconds. As an example of a combination of about 4.0 nm, a combination of an area magnification of 11.6 times, a heat treatment temperature of 200 ° C., and a heat treatment time of 5 seconds can be given.

  The stretching method as the above-mentioned stretching conditions may be either simultaneous biaxial or sequential biaxial stretching, but the unstretched sheet is stretched in the longitudinal direction and width direction of the film and heat-treated to obtain the desired crystal size. Get a film. Preferably, the tenter method is preferred in terms of film quality. After stretching in the longitudinal direction, a sequential biaxial stretching method in which the film is stretched in the width direction, and a simultaneous biaxial stretching method in which the longitudinal direction and the width direction are stretched almost simultaneously. Is desirable. As a draw ratio, it is 1.5 to 5.0 times in each direction, Preferably it is 3.0 to 4.5 times. Either the stretching ratio in the longitudinal direction or the width direction may be increased or the stretching ratio may be the same.

  The stretching speed is desirably 1000% / min to 200000% / min, and the stretching temperature can be any temperature as long as it is not less than the glass transition temperature of the polyester used and not more than the glass transition temperature + 80 ° C. Usually, 80 to 155 ° C is preferable.

  Further, the heat treatment of the film after the biaxial stretching described above will be described. This heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. The heat treatment temperature can usually be an arbitrary temperature of 120 ° C. or higher and 245 ° C. or lower, but it is usually preferably performed for 1 to 60 seconds.

  The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction. Furthermore, it may be performed once or more in each direction of redrawing, and then heat treatment may be performed.

Furthermore, about what passed through the process (D), it is preferable to pass through a process (E).
(E) The process of performing the aging process for 24 hours or more on 30 degreeC-70 degreeC temperature conditions after forming a film. Aging is preferably performed in a roll form from the viewpoint of handleability, but it may be performed in the form of a sheet cut into sheets.

  Since the laminated polyester film of the present invention has a polyester A layer surface containing a wax component on at least one side, it is easily peeled off at the interface with the ceramic green sheet layer or polarizing plate formed on the surface of the A layer. be able to. Therefore, it is possible to easily separate and collect only the base film portion. Moreover, since the base film collected in this way does not include a silicone resin film that has been applied in order to develop peelability, it is easy to recycle as a recycled material. Therefore, the laminated polyester film of the present invention can be suitably used as a ceramic green sheet peeling application or a polarizing plate release application.

  In particular, when the peelable laminated polyester film of the present invention is used as a process film for producing a green sheet such as a laminated ceramic capacitor, the concentration of the wax component of the polyester A layer on which the ceramic green sheet is directly formed is small, Since there is little influence from the transfer of the wax component to the ceramic green sheet, only the base film can be separated and recovered without adding any additional process to the conventional manufacturing process of multilayer ceramic parts. The formation of the cured silicone film on the base film that has been assumed to be unnecessary can be eliminated.

  Next, the embodiment of the present invention will be described more specifically based on examples.

  The characteristic value measurement method and evaluation method defined in the present invention will be described below.

(1) Peelability of ceramic green sheet The following ceramic slurry was applied to the surface of the polyester A layer of the laminated polyester film using a screen printing machine and dried, and then 10 cm × 10 cm and a thickness of 10 μm (after the slurry was dried) The thickness of the ceramic green sheet was formed.

  Next, a polyester adhesive tape (Nitto Denko Co., Ltd. No. 31B, width 19 mm) is pasted on the ceramic green sheet, a strip sample having a width of 19 mm and a length of 100 mm is cut out, and the ceramic green sheet is removed from the base film. It peeled. The peeled state was visually observed and judged as follows.

  That is, a ceramic green sheet that could be easily peeled off without causing wrinkles or cracks was marked with ◎. Although it was able to peel, the thing which the wrinkles and the crack generate | occur | produced on the sheet | seat after peeling was set as (circle). Although it can be easily peeled up to the middle (from the base of the tape to 5 mm and beyond), the one that is broken so that it breaks at some point is designated as Δ. Those broken at a location within 5 mm from the base of the tape were marked with x.

≪Ceramic slurry composition≫
Barium titanate powder (average particle size 1.1 um, sintered density 5.84): 90 parts by weight Binder (polyvinyl butyral resin: degree of polymerization 200-700, viscosity 10-30 cps): 10 parts by weight Agent (dioctyl phthalate): 1 part by weight-toluene / methyl ethyl ketone mixed solvent (1: 1 blending ratio): 50 parts by weight.
(2) Peelability from polarizing plate Using an adhesive having acrylic resin, an adhesive layer is provided on the surface of the laminated polyester film on the A layer side, and the polarizing plate is bonded to the surface of the polyester A layer, and then laminated polyester. The peeled state when the polarizing plate was peeled from one end of the film and the transfer of the pressure-sensitive adhesive onto the laminated polyester film were visually observed and determined as follows.

  That is, the laminated polyester film can be easily peeled off without being broken or wrinkled, and the pressure-sensitive adhesive does not remain on the surface of the layer A of the laminated polyester film. The case where the wrinkles and the adhesive residue were generated in the laminated polyester film after peeling was evaluated as x. Although it was able to peel, it was set as (triangle | delta) that the residue of the adhesive or the adhesive tape was recognized.

(3) Maximum protrusion height (Rmax)
It measured based on the following measurement conditions using the three-dimensional fine surface shape measuring device (Kosaka Seisakusho ET-350K), and computed from the profile curve of the obtained surface. In addition, the measurement was implemented in the surface which the polyester A layer comprises.
[Measurement condition]
X direction measurement length: 0.5 mm, X direction feed rate: 0.1 mm / second.
Y direction feed pitch: 5 μm, number of Y direction lines: 40.
Cut-off: 0.25 mm.
Stylus pressure: 0.02 mN.
Height (Z direction) magnification: 50,000 times.

(4) Crystal size χc of (100) plane
The film is cut to be 30 mm (film longitudinal direction) × 20 mm (film width direction), the film is used as an X-ray diffraction sample, and an X-ray diffractometer TYPE PW1840 manufactured by Nippon Philips is used. The diffraction intensity is measured by the reflection method while changing the X-ray irradiation angle in a vertical plane. The measurement conditions are as follows.
[Measurement condition]
Time constant: 2 seconds Measurement angle range: 18 degrees to 32 degrees Traveling speed: 1 degree / minute Diversity Slit: 1.5 mmφ
Scattering Slit: 1 degree Receiving Slit: 0.3 mm
X-ray: Cu-Kα (35 Kv, 15 mA, Ni-filter) with Cu counter cathode
When the film is a polyethylene terephthalate film, if the diffraction intensities at 25.8 ° and 22.5 ° corresponding to the diffraction angles of the (100) and (110) planes of the polyethylene terephthalate crystal are H1 and H2, (100 ) Plane crystal size χc can be obtained by the following equation.
χc = K · λ / β · cosθ
Where K (constant when half width is used) = 0.90
λ (X-ray wavelength) = 1.5418 (４)
θ (diffraction angle of [100] plane) = 25.8 (°)
β (Diffraction line width rad) = Diffraction line width (half width) measured at half the diffraction intensity H1 of the diffraction intensity H1 × Half width × 0.01744 (rad)
(Since 2π (rad) = 360 °, 1 ° = 0.01744 rad).

(5) Peelability of adhesive tape Adhesive tape ("SCOTCH" (registered trademark) 313, manufactured by Sumitomo 3M Limited) is cut into a width of 20 mm and a length of 50 mm, bent at the position of a tip of 10 mm in the length direction, and a 10 mm tab And a pasting base material was created (width 20 mm, tab portion 10 mm, pasting portion 30 mm).

  Next, the film to be measured was cut into a width of 20 mm and a length of 40 mm.

  Affix the base material so that it overlaps the surface of the polyester A layer of the film to be measured (adhered part 30 mm, non-adhered part 10 mm), and reciprocate the adhering part once with a 2 kg rubber roller. The sample was measured by pressure bonding. The bonded sample was aged for 24 hours under the conditions of 25 ° C. and 50% relative humidity.

  The tape side tab portion of the pasting substrate and the non-laminated portion of the film were held, and peeling was performed at a peeling angle of 180 ° and a peeling speed of 30 mm / second. It implemented similarly about 10 samples, visually observed the state of the film after peeling, and determined as follows.

  That is, the number of samples remaining on the surface of the film after peeling the adhesive was 0 or 1 sample, ◎, 2 or 3 sample ○, 4 or 5 sample △, 6 samples or more Was marked with x.

Example 1:
(Preparation for peelable laminated polyester film)
・ Polyester chip A
Heated by adding 59 parts by weight of ethylene glycol and magnesium acetate tetrahydrate (0.055 parts by weight) and 0.015 parts by weight of phosphoric acid to 100 parts by weight of dimethyl terephthalate (DMT). A transesterification reaction was performed. An ethylene glycol slurry containing 0.08% by weight of agglomerated silica particles having an average particle size of 2.5 μm was heat-treated at 190 ° C. for 2 hours, and then the slurry was added after the transesterification reaction, and then 0.0045 parts by weight of germanium dioxide was added. The temperature was raised and the polycondensation reaction was performed under vacuum. After 120 minutes, the pressure was returned to normal pressure, and 0.8% by weight of carnauba wax was added under normal pressure and stirred for 5 minutes. The mixture was returned and stirred until a predetermined degree of polymerization was reached. A chip of the obtained polyethylene terephthalate composition was used as chip A.
・ Polyester chip B
Heated by adding 59 parts by weight of ethylene glycol and magnesium acetate tetrahydrate (0.055 parts by weight) and 0.015 parts by weight of phosphoric acid to 100 parts by weight of dimethyl terephthalate (DMT). After transesterification, an ethylene glycol slurry containing 0.08% by weight of agglomerated silica particles having an average particle size of 2.5 μm was heat-treated at 190 ° C. for 2 hours, and then the slurry was added after the transesterification reaction was completed. .0045 parts by weight was added, the temperature was raised and the polycondensation reaction was performed under vacuum. After 120 minutes, the pressure was returned to normal pressure, and 0.4% by weight of carnauba wax was added under normal pressure and stirred for 5 minutes. Then, it was returned to vacuum again and stirred until a predetermined polymerization degree was reached. A chip of the obtained polyethylene terephthalate composition was used as chip B.

  After a predetermined amount of each of chip A and chip B is dried in vacuum at 180 ° C. for 3 hours, chip A is supplied to extruder I (A), chip B is supplied to extruder II (B), and discharged from the T die die. Then, it cooled and solidified with the mirror cooling drum of 25 degreeC, applying electrostatic, and obtained the unstretched film of the 2 layer structure of A layer / B layer. This unstretched film is guided to a roll-type stretching machine, heated with a preheated roll at 85 ° C., stretched 3.3 times in the longitudinal direction between rolls having a peripheral speed difference of 95 ° C., and once cooled to room temperature Then, it was fed into a tenter type horizontal stretching machine and stretched 3.5 times in the width direction at a temperature of 95 ° C. Further, a laminated polyester film having a thickness of 15 μm (A layer 2 μm / B layer 13 μm) was subjected to a heat treatment for 5 seconds while relaxing the film width after transverse stretching by 5% in an atmosphere of 200 ° C. in a heat treatment zone of the tenter. Was made.

  Table 1 shows the results of evaluating the characteristics of the produced film.

Examples 2-5:
As described in Table 1, the content WA (% by weight) in the polyester A layer, the thickness TA (μm) of the polyester A layer, and the content WB (% by weight) in the polyester B layer were adjusted. Table 1 shows the results of producing a polyester film having a total thickness of 15 μm and evaluating the characteristics in the same manner as in Example 1.

Example 6:
In producing the polyester chip A, a polyester film was prepared in the same manner as in Example 1 except that the particles to be added were changed to 0.25% by weight of an average particle size of 0.2 μm spherical silica particles. The evaluation results are shown in Table 1.

Example 7:
A laminated polyester film was produced in the same manner as in Example 1 except that the heat treatment temperature in the heat treatment zone was changed to 185 ° C.

  Table 2 shows the results of evaluating the characteristics of the produced film.

Example 8:
Using the same polyester chip A and chip B as in Example 1, after weighing each predetermined amount, vacuum drying at 180 ° C. for 3 hours and chip A into extruder I (A) and chip B into extruder II (B) After being supplied and discharged from the T die die, it was cooled and solidified with a mirror cooling drum at 25 ° C. while applying an electrostatic force to obtain an unstretched film having a two-layer structure of A layer / B layer. After this unstretched film is guided to a roll-type stretching machine and heated with a 103 ° C preheated roll, it is stretched 3.5 times in the longitudinal direction between rolls having a peripheral speed difference of 104 ° C, and once cooled to room temperature Then, it was fed into a tenter type horizontal stretching machine and stretched 3.5 times in the width direction at a temperature of 100 ° C. Further, a laminated polyester film having a thickness of 25 μm (A layer 2 μm / B layer 23 μm) was subjected to heat treatment for 6 seconds while relaxing the film width after transverse stretching by 6% in an atmosphere of 235 ° C. in a heat treatment zone of the tenter. Was made.

  Table 2 shows the results of evaluating the characteristics of the produced film.

Example 9:
・ Polyester chip C
Heated by adding 61 parts by weight of ethylene glycol and magnesium acetate tetrahydrate (0.05 parts by weight) and phosphoric acid (0.015 parts by weight) to 100 parts by weight of dimethyl terephthalate (DMT). A transesterification reaction was carried out, 0.025 parts by weight of antimony trioxide was subsequently added, a polycondensation reaction was carried out under heating and under vacuum, and a chip of the obtained polyethylene terephthalate composition containing substantially no particles was chipped. C.

・ Polyester chip D
Calcium carbonate having a true specific gravity of 2.71 g / cm ³ and an average particle diameter of 1.0 μm was prepared to prepare a 10 wt% ethylene glycol slurry. This slurry was dispersed for 1 hour with a jet agitator and filtered with high accuracy through a filter having a collection efficiency of 95% of 5 μm or more. Next, 0.05 parts by weight of ethylene glycol and magnesium acetate tetrahydrate of 61 parts by weight (1.9 moles per mole of DMT) and 100 parts by weight of dimethyl terephthalate (DMT) and 0.015 parts by weight of phosphoric acid Part of the mixture was subjected to a transesterification reaction, 0.025 parts by weight of antimony trioxide and the slurry prepared above were added after the transesterification, the temperature was raised by heating, a polycondensation reaction was performed under vacuum, and an average particle size of 1.0 μm Chip D of the obtained polyethylene terephthalate composition containing 1% by weight of calcium carbonate was used as chip D.

・ Polyester chip E
Heated by adding 61 parts by weight of ethylene glycol and magnesium acetate tetrahydrate (0.05 parts by weight) and phosphoric acid (0.015 parts by weight) to 100 parts by weight of dimethyl terephthalate (DMT). The transesterification reaction was carried out, followed by the addition of 0.0045 parts by weight of germanium dioxide, the temperature was raised by heating and the polycondensation reaction was carried out under vacuum. After 120 minutes, the pressure was returned to normal pressure, and carnauba wax was added under normal pressure. After adding 0% by weight, the mixture was stirred for 5 minutes, then returned to vacuum and stirred until a predetermined degree of polymerization was reached. The chip of the obtained polyethylene terephthalate composition was used as chip E.

・ Polyester chip F
In a bi-axial kneading extruder of the same direction rotation type heated to 280 ° C., 20 parts by weight of a slurry of 98 parts by weight of a chip C and 10% by weight water-crosslinked polystyrene particles having an average diameter of 0.3 μm (as spherically crosslinked polystyrene) 2 parts by weight), the vent hole is maintained at a reduced pressure of 1 kPa or less, moisture is removed, and a chip of a polyethylene terephthalate composition containing 2 parts by weight of spherical crosslinked polystyrene particles having an average particle size of 0.3 μm did.

  The spherical crosslinked polystyrene particles described above were produced by a method in which seed particles were synthesized by soap-free emulsion polymerization, swollen with a swelling aid, and absorbed and polymerized. As a method for absorbing the polymerizable monomer, a method of collectively adding these to the water-soluble dispersion synthesized with the seed particles was adopted.

  Next, chips were weighed by a predetermined amount and supplied to each extruder. When the total amount of chips supplied to the extruder I (A) is 100% by weight after drying in vacuum at 180 ° C. for 3 hours, the chip C is 55% by weight and the chip E is 40%. When the total amount of chips supplied to the extruder II (B) is 100% by weight, the chip C is 80% by weight, the chip E When the total amount of chips supplied to the extruder III (C) is 100% by weight, the chip C is 45% by weight, the chip D is 50% by weight, After supplying 5% by weight of F and discharging it from the T die die, it is cooled and solidified with a mirror cooling drum at 25 ° C. while applying electrostatic force, and an unstretched film having a three-layer structure of A layer / B layer / C layer Got. After this unstretched film is guided to a roll-type stretching machine and heated with a 103 ° C. preheating roll, it is stretched 3.8 times in the longitudinal direction between rolls having a peripheral speed difference of 120 ° C., and once cooled to room temperature Then, it was fed into a tenter type horizontal stretching machine and stretched 3.9 times in the width direction at a temperature of 110 ° C. Furthermore, in a heat treatment zone of the tenter, the film width after transverse stretching was relaxed by 3% in an atmosphere of 230 ° C., and heat treatment was performed for 4 seconds to obtain a thickness of 25 μm (A layer 1.5 μm / B layer 22 μm / C layer). 1.5 μm) laminated polyester film was prepared.

  Table 2 shows the results of evaluating the characteristics of the produced film.

Example 10:
A laminated polyester film was produced in the same manner as in Example 9 except that the thickness of the laminated polyester film was 31 μm (A layer 1.5 μm / B layer 28 μm / C layer 1.5 μm). Table 2 shows the results of evaluating the characteristics of the produced film.

Example 11:
A laminated polyester film was produced in the same manner as in Example 9 except that the heat treatment time was 5 seconds and the thickness of the laminated polyester film was 38 μm (A layer 1.5 μm / B layer 35 μm / C layer 1.5 μm). did.

  Table 2 shows the results of evaluating the characteristics of the produced film.

Example 12:
An unstretched film was produced in the same manner as in Example 9. After this unstretched film is guided to a roll-type stretcher and heated with a 103 ° C preheating roll, it is stretched 3.4 times in the longitudinal direction between rolls having a peripheral speed difference of 104 ° C and once cooled to room temperature. Then, it was fed into a tenter type horizontal stretching machine and stretched 4.5 times in the width direction at a temperature of 100 ° C. Furthermore, in the heat treatment zone of the tenter, the film width after transverse stretching was relaxed by 3% in an atmosphere of 220 ° C., and heat treatment was performed for 6 seconds to obtain a thickness of 38 μm (A layer 1.5 μm / B layer 35 μm / C layer). 1.5 μm) laminated polyester film was prepared. The produced film was subjected to aging treatment at 30 ° C. for 100 hours.

  Table 2 shows the results of evaluating the properties of the film after the aging treatment.

Example 13:
A laminated polyester film was produced in the same manner as in Example 12 except that the heat treatment temperature was 190 ° C. and the aging treatment conditions were 60 ° C. and 100 hours.

  Table 2 shows the results of evaluating the properties of the film after the aging treatment.

Comparative Examples 1-5:
As described in Table 1, the content WA (% by weight) in the polyester A layer, the thickness TA (μm) of the polyester A layer, and the content WB (% by weight) in the polyester B layer were adjusted. Table 3 shows the results of producing a polyester film having a total thickness of 15 μm and evaluating the characteristics in the same manner as in Example 1.

  Since the laminated polyester film of the present invention has excellent peeling performance, it can be suitably used for ceramic green sheet molding or polarizing plate release.

Claims (8)

A biaxially oriented laminated polyester film having at least a polyester A layer and a polyester B layer,
The outermost layer on at least one side of the biaxially oriented laminated polyester film is a polyester A layer containing a wax component,
A polarizing plate in which the polyester A layer satisfies the following formulas (1) and (2) when the concentration of the wax component contained in the polyester A layer is WA (% by weight) and the thickness of the polyester A layer is TA (μm): A biaxially oriented laminated polyester film used as a release film or a process film for forming a ceramic sheet .
0.8 ≤ WA (1)
0.4 ≦ WA / TA ≦ 20 (2) The biaxially oriented laminated polyester film according to claim 1, wherein the concentration of the wax component contained in the polyester A layer is WA (wt%), the thickness of the A layer is TA (μm), and the X-ray diffraction measurement of the polyester film. A polarizing plate release film characterized in that the polyester A layer satisfies the following formulas (3), (4), and (5) when the crystal size of the (100) plane obtained by the following equation is χc (nm) Or the biaxially oriented laminated polyester film used as a process sheet for forming a ceramic sheet .
0.8 ≦ WA ≦ 5.0 Equation (3)
0.3 ≦ TA ≦ 5.0 Formula (4)
χc> 6.0 (Equation 5) The biaxially oriented laminated polyester film according to claim 1, wherein the concentration of the wax component contained in the polyester A layer is WA (wt%), the thickness of the A layer is TA (μm), and the X-ray diffraction measurement of the polyester film. polarizer release film polyester a layer and crystal size of the resulting (100) plane when the Kaishi (nm), wherein the Ru der satisfy the following formula (3) (4) (6) Or the biaxially oriented laminated polyester film used as a process sheet for forming a ceramic sheet .
0.8 ≦ WA ≦ 5.0 Equation (3)
0.3 ≦ TA ≦ 5.0 Formula (4)
4.0 ≦ χc ≦ 6.0 Expression (6) The biaxially oriented laminated polyester film used as a polarizing plate release film or a process sheet for forming a ceramic sheet according to any one of claims 1 to 3 , wherein the wax component is carnauba wax and / or stearyl stearate. . The polarizing plate release film or ceramic sheet according to any one of claims 1 to 4, wherein the concentration WB of the wax component in the polyester B layer satisfies the following formula (7) with respect to the polyester B layer. A biaxially oriented laminated polyester film used as a molding process film.
0 ≦ WB <0.6 (7) The polarizing plate release film or ceramic sheet-forming process film according to any one of claims 1 to 5, wherein the polymer constituting the polyester film is substantially composed of one kind of dicarboxylic acid and one kind of diol. Biaxially oriented laminated polyester film used as A method for producing a biaxially oriented laminated polyester film having at least a polyester A layer and a polyester B layer, wherein at least one outermost layer is a polyester A layer, wherein the A layer comprises the following (A) (B) (C ), A method for producing a biaxially oriented laminated polyester film used as a polarizing plate release film or a ceramic sheet-forming process film .
(A) The process of adding the wax component to polyester and obtaining the polyester composition which comprises a polyester film.
(B) A wax component contained in the polyester A layer so as to satisfy the following formulas (2), (3), and (4) by coextrusion of the polymer melted using the polyester composition to form the A layer and the B layer. Adjusting the concentration WA (% by weight) and the thickness TA (μm) of the A layer.
0.4 ≦ WA / TA ≦ 20 (2)
0.8 ≦ WA ≦ 5.0 Equation (3)
0.3 ≦ TA ≦ 5.0 Formula (4)
(C) A step of adjusting the crystal size χc so that the following formula (5) is satisfied when the crystal size χc (nm) of the (100) plane obtained by X-ray diffraction measurement of the polyester film is used.
χ c> 6.0 (5) A method for producing a biaxially oriented laminated polyester film having at least a polyester A layer and a polyester B layer, wherein at least one outermost layer is a polyester A layer, wherein the A layer comprises the following (A) (B) (D ) A method for producing a biaxially oriented laminated polyester film used as a polarizing plate release film or a process sheet for forming a ceramic sheet , formed by a method having the steps (E) in that order.
(A) The process of adding the wax component to polyester and obtaining the polyester composition which comprises a polyester film.
(B) A wax component contained in the polyester A layer so as to satisfy the following formulas (2), (3), and (4) by coextrusion of the polymer melted using the polyester composition to form the A layer and the B layer. Step of adjusting the concentration WA (% by weight) and the thickness TA (μm) of the layer A 0.4 ≦ WA / TA ≦ 20 Formula (2)
0.8 ≦ WA ≦ 5.0 Equation (3)
0.3 ≦ TA ≦ 5.0 Formula (4)
(D) A step of adjusting the crystal size χc so that the following equation (6) is satisfied when the crystal size of the (100) plane obtained by X-ray diffraction measurement of the polyester film is χc (nm).
4.0 ≦ χc ≦ 6.0 Expression (6)
(E) The process of performing the aging process for 24 hours or more on 30 degreeC-70 degreeC temperature conditions after forming a film.