JP2014117815A - Release polyester film for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release polyester film for molding having excellent release property, such as not only having foil nick inhibition, excellent detachability, crack resistance in early stage, but also inhibiting foil nick phenomenon, hardly generating crack phenomenon and easy to detach from a hard coating layer after a lapse of time.SOLUTION: A release polyester film for molding has a release layer on at least one surface of a polyester film, the release layer is formed from a copolymer containing a fluoroalkyl(meth)acrylate component ((I) component) and a (meth)acrylic acid component ((II) component) as constituting components and a crosslinking agent, the copolymer has the content of the (I) component of 40 to 95 mol% and the content of the (II) component of 2 to 10 mol% based on 100 mol% of the total component unit of the copolymer, glass transition temperature Tg of the copolymer of over 60°C, and the content of the copolymer in the release layer is 40 wt.% to 85 wt.% based on the weight of the release layer.

Description

  The present invention relates to a mold release polyester film. More specifically, the present invention relates to a mold release polyester film useful as a base film for a transfer foil for in-mold transfer that is transferred and printed simultaneously with molding in injection molding or the like.

  Conventionally, as a transfer foil for in-mold transfer, a polyester film is used as a base film, a thermosetting release layer is provided thereon, and a hard coat layer and a printing layer are applied on the release layer, Those sequentially stacked are used.

  Such a transfer foil for in-mold transfer is peeled off and separated between the release layer surface and the hard coat layer surface after molding transfer. That is, the printed layer adheres to the surface of the molded product after molding transfer, and the hard coat layer becomes the outermost surface of the product and is taken out as a product. On the other hand, the release layer is removed from the product while being provided on the base film of the transfer foil. Moreover, in the said laminated structure, in order to improve the adhesive force of a mold release layer and a base film, providing an adhesive layer between both layers is also examined.

  In such a transfer foil, a conventional release layer is formed by, for example, slitting a slit portion by a shock applied to a slit blade when the layers are laminated and then cut (slit) to an appropriate width according to the size of the transfer object. In some cases, a transfer layer such as a hard coat layer or a printing layer peels off from the surface of the release layer, so-called “foil spill phenomenon”. This occurs because the delamination force between the release layer and the hard coat layer is too low. The foil spill phenomenon becomes more prominent as the transfer layer is thicker, such as when a certain thickness is required as in the hard coat layer, or when there are many other functional layers.

  In order to prevent such foil spilling at the time of slitting, when a release layer is provided on the base film, a release layer is provided on a belt-like pattern excluding a portion corresponding to the slit, and a hard coat layer and a printing layer are provided thereon. A transfer layer comprising an adhesive layer or the like has been studied (Patent Document 1). However, such a method has a problem that a transfer layer having a pattern suitable for the transfer object must be formed.

  Moreover, in patent document 2, it replaces with the conventional thermosetting release layer as a mold release film, and the release layer whose normal peeling force is 2000 mN / cm or less is formed on one side instead of the conventional thermosetting release layer. Has been proposed, and it is described that a fluorine-containing resin is preferable as one of the components constituting the release layer. However, Patent Document 2 discloses a release film having a wide peeling force of 2000 mN / cm or less, but nothing has been studied on improving foil spillage.

  On the other hand, Patent Document 3 proposes a polyester film having adhesive release properties as an improvement in foil spillage of a mold release film, and describes that a fluorine-based polymer having a glass transition temperature of 20 ° C. or lower is preferable. Has been. However, this has made it possible to improve the initial foil spilling, but after processing the hard coat layer on the transfer foil for in-mold transfer and aging it for a long time, Further improvement is required for the stability of the peel force before and after the release (stable peel force stability).

  Also, if you try to increase the peel force by focusing on foil spillage, the peel force between the transfer foil and hard coat layer is too high, so that the hard coat layer and print layer are laminated on the transfer foil. When the molding resin is injected into a mold and molded into a mold shape, there is a need to solve the problem that the hard coat layer and the printing layer cannot follow the deformation of the transfer foil and cracks occur. In Patent Document 3, although the crack resistance in the initial stage has been improved, the problem of the crack resistance (crack resistance with time) after newly bonding for a long time has been found this time, and further improvement is required for this. ing.

Japanese Patent Laid-Open No. 11-58584 Japanese Patent Laid-Open No. 2007-111964 JP 2012-11656 A

  The object of the present invention is to solve the problems of the prior art and to suppress foil spillage, excellent peelability, and crack resistance (hereinafter, these may be collectively referred to as mold release characteristics) only in the initial stage. In addition, it is an object to provide a mold release film having excellent mold release characteristics that suppresses the foil spill phenomenon even after the passage of time, hardly causes the crack phenomenon, and easily peels off from the hard coat layer.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a copolymer containing a specific fluoroalkyl (meth) acrylate component and a (meth) acrylic acid component, and further cross-linked the copolymer with such a copolymer. It has been found that the above problem can be solved by employing a release layer that is used in combination with an agent, and the present invention has been completed.

That is, an object of the present invention is to have a release layer on at least one surface of a polyester film, and the release layer includes a fluoroalkyl (meth) acrylate component ((I) component) represented by the following general formula (I): , A copolymer containing a (meth) acrylic acid component ((II) component) represented by the following general formula (II) as a constituent component, and a crosslinking agent,
In the copolymer, the total structural unit of the copolymer is 100 mol%, the content of the component (I) is 40 to 95 mol%, and the content of the component (II) is 2 to 10 mol%. Yes, the glass transition temperature Tg of the copolymer is more than 60 ° C and 85 ° C or less,
The content of the copolymer in the release layer is 40% by weight or more and 85% by weight or less based on the weight of the release layer.
This is achieved by a mold release polyester film.

（式（Ｉ）（ＩＩ）中、Ｒ^１〜Ｒ^２は水素またはメチル基、Ｒ_Ｘは炭素原子数１〜１０の炭化水素基、Ｒ_ｆはフッ素原子数３〜９のフルオロアルキル基をそれぞれ表わす。）

(In the formulas (I) and (II), R ^{1 to} R ² are hydrogen or a methyl group, R _X is a hydrocarbon group having 1 to 10 carbon atoms, and R _f is a fluoroalkyl group having 3 to 9 fluorine atoms, respectively. Represents.)

  Moreover, the mold release polyester film of the present invention has, as a preferred embodiment, the content of the crosslinking agent in the release layer is 10% by weight or more and 40% by weight or less based on the weight of the release layer. The crosslinking agent is a crosslinking agent having an oxazoline group, the normal peel force of the release layer to the adhesive tape is 0.2 N / mm or more and 0.5 N / mm or less, and the release layer is on the polyester film. It is provided directly, the release layer is formed by coating in the process of forming a polyester film, has a release layer on one side of the polyester film, and is opposite to the release layer of the polyester film Further, it is possible to include those having at least one of an antistatic release layer on the surface and for in-mold molding.

  According to the present invention, not only the initial release characteristics, but also after the passage of time, the foil spill phenomenon is suppressed when slitting to a width that matches the size of the transfer object, and the transfer is performed during molding. It is possible to obtain a release polyester film for molding having excellent release characteristics such that a crack phenomenon hardly occurs in the product and it is easy to peel off from the hard coat layer after transfer. Such a mold release polyester film can be suitably used for molding such as molding with in-mold transfer.

Hereinafter, the present invention will be described in detail.
[Polyester film]
The polyester constituting the polyester film in the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalenedicarboxylate.

  The polyester may be a homopolymer, a copolymer having one of these polyesters as a main component, or a blend. Here, the “main component” is 80 mol% or more based on the number of moles of the repeating structural unit of the polyester. The ratio of the main component is preferably 85 mol% or more, and more preferably 90 mol% or more. The copolymer component or blend component is 20 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less, based on the number of moles of the repeating structural unit of the polyester. As the polyester, polyethylene terephthalate is particularly preferable because of a good balance between mechanical properties and moldability.

The polyester film in the present invention may contain lubricant particles, a colorant, an antistatic agent, and an antioxidant within the range not impairing the problems of the present invention. When high transparency and surface flatness are required, it is preferable that lubricant particles are not substantially contained.
The polyester film can be produced, for example, by the following method. That is, polyester is melt-extruded into a film shape, cooled and solidified with a casting drum to form an amorphous unstretched film, and the longitudinal direction (hereinafter sometimes referred to as a continuous film-forming direction, the longitudinal direction, and the MD direction) and the lateral direction (hereinafter referred to as the “non-stretched film”) , Sometimes referred to as the width direction and the TD direction). Stretching in the machine direction is, for example, at a temperature of 60 to 130 ° C., preferably 90 to 125 ° C., and stretched in the machine direction of, for example, 2.0 to 4.0 times, preferably 2.5 to 3.5 times. The stretching in the transverse direction is, for example, at a temperature of 60 to 130 ° C., preferably 90 to 125 ° C., and is stretched in the transverse direction, for example, 2.0 to 4.5 times, preferably 3.0 to 4.2 times. The area magnification after biaxial stretching is preferably 13 or less.

In addition, it is preferable to perform a heat setting process after extending | stretching a film. The heat setting treatment is preferably performed within a period of 1 to 30 seconds at a temperature higher than the final stretching temperature and not higher than the melting point. For example, in the case of a polyethylene terephthalate film, it is preferable to select and heat-set at a temperature of 150 to 250 ° C. and a time of 2 to 30 seconds. At that time, it is performed under a limited shrinkage or elongation within 20%, or under a constant length, or may be performed in two or more stages.
The thickness of the polyester film is preferably 12 to 100 μm, more preferably 25 to 75 μm, from the viewpoints of handling properties and moldability, and if necessary, from the viewpoint of transparency.

[Release layer]
The mold release polyester film of the present invention has a release layer on at least one surface of the polyester film, and the release layer is a fluoroalkyl (meth) acrylate component represented by the following general formula (I) ((I ) Component) and (meth) acrylic acid component ((II) component) represented by the following general formula (II) as constituent components (hereinafter referred to as fluorinated acrylic copolymer) And a cross-linking agent.

（式（Ｉ）（ＩＩ）中、Ｒ^１〜Ｒ^２は水素またはメチル基、Ｒ_Ｘは炭素原子数１〜１０の炭化水素基、Ｒ_ｆはフッ素原子数３〜９のフルオロアルキル基をそれぞれ表わす。）

(In the formulas (I) and (II), R ^{1 to} R ² are hydrogen or a methyl group, R _X is a hydrocarbon group having 1 to 10 carbon atoms, and R _f is a fluoroalkyl group having 3 to 9 fluorine atoms, respectively. Represents.)

  The mold release polyester film of the present invention, when used as a transfer foil for in-mold molding, is characterized by having crack resistance, suppression of foil spillage, and good peelability not only in the initial stage but also after time. There is. Here, “after time” actually means that after hard coating or printing (ink) after hard coating has been processed, it is aged for one week or more, preferably one month or more. In the present invention, as will be described later, the acceleration test is performed by applying temperature and humidity.

In addition, in order to obtain stability over time, it is a release layer having a high solvent resistance to the solvent and the like contained in the hard coating agent coating liquid, and hardly changes even under various assumed environments in the factory. A release layer is preferred.
Specifically, the release layer contains the above-mentioned fluorinated acrylic copolymer having the specific composition and the glass transition temperature Tg of the copolymer is in a predetermined temperature range, so that not only at the initial stage but also after the passage of time. Foil spillage is suppressed, and since the fluorinated acrylic copolymer contains a (meth) acrylic acid component, it has a cross-linking point. By further containing a cross-linking agent, the degree of cross-linking of the release layer is increased and molding is performed. A release layer suitable for a mold release film can be obtained, and a release layer having both these contradictory functions can be obtained not only at the initial stage but also after the passage of time. Can do.

[Fluoroacrylic copolymer]
In the present invention, the fluorinated acrylic copolymer used for the release layer includes a fluoroalkyl (meth) acrylate component represented by the above general formula (I) and a (meth) acrylic acid represented by the above general formula (II). It is a copolymer containing a component as a constituent component. Each component of the copolymer may be used alone or in combination of two or more of the exemplified components described below.

  Such a fluorinated acrylic copolymer is one type of acrylic resin having a structural unit derived from a (meth) acrylic ester in the main chain. In the present invention, “(meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position. In the present invention, “(meth) acrylate” means one or both of an acrylate having a hydrogen bond at the α-position and a methacrylate having a methyl group bonded to the α-position. That is, the fluoroalkyl (meth) acrylate component is a general term for a fluoroalkyl acrylate component and a fluoroalkyl methacrylate component. The fluorinated acrylic copolymer of the present invention is obtained by copolymerizing fluoroalkyl (meth) acrylate and (meth) acrylic acid as monomer components on a polymer.

  When the fluorinated acrylic copolymer contains a fluoroalkyl group, and the number of fluorine atoms in the fluoroalkyl group is 3 or more, release performance is exhibited. Further, when the number of fluorine atoms in the fluoroalkyl group is 9 or less, the dispersibility in water is improved, so that emulsification is facilitated, and the peeling force becomes moderately high, and foil spillage can be suppressed. The number of fluorine atoms in such a fluoroalkyl group is preferably 3-7.

In Formula (I), R _X contained in the fluoroalkyl (meth) acrylate component is a hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, specifically methylene. Preferred examples include saturated chain hydrocarbon groups such as a group, ethylene group, propylene group, butylene group, pentylene group and hexylene group, and saturated alicyclic hydrocarbon groups such as a cyclopentylene group, with an ethylene group being particularly preferred.

Specific examples of the fluoroalkyl (meth) acrylate component constituting the copolymer component of the fluorinated acrylic copolymer include trifluoromethyl (meth) acrylate, trifluoroethyl (meth) acrylate, trifluoropropyl (meth) acrylate, Examples of the copolymer component include tetrafluoropropyl (meth) acrylate, trifluorobutyl (meth) acrylate, and hexafluorobutyl (meth) acrylate as monomer components. Such a component is preferably soluble or dispersible in water, but is preferably soluble in water containing some organic solvent, and particularly preferably the monomer component is trifluoromethyl (meth) acrylate, trifluoroethyl (meta ) By using acrylate or trifluorobutyl (meth) acrylate, the adhesion to the polyester film, the releasability from the hard coat layer, and the processability are further improved.
The (meth) acrylic acid component (component (II)) constituting the fluorinated acrylic copolymer is obtained using monomer components such as acrylic acid and methacrylic acid. Methacrylic acid is preferred because of its safety and ease of handling.

  In the fluorinated acrylic copolymer of the present invention, the total of the structural units derived from the methacrylate derivative is preferably 25 mol% or more and 80 mol% or less with all the structural units being 100 mol%. More preferably, they are 30 mol% or more and 75 mol% or less, Especially preferably, they are 35 mol% or more and 70 mol% or less. Here, the structural unit derived from the methacrylate derivative represents a structural unit derived from the fluoroalkyl methacrylate component represented by the formula (I) and the methacrylic acid component represented by the formula (II). If the total of the structural units derived from the methacrylate derivative is less than the lower limit, the solvent resistance tends to be low, and suitable release performance tends to be difficult to develop after the lapse of time, and the hard coat layer and the interface It tends to be mixed and easily peeled off, whereby the effect of improving crack resistance may be reduced, and in some cases, peeling may not be possible. In addition, the fluorine-containing acrylic copolymer containing fluorine tends to affect the film-forming property when forming a release layer on a polyester film, so the total of structural units derived from methacrylate derivatives is the upper limit from the viewpoint of film-forming property. It is preferable to use in the range which does not exceed.

  In the fluorinated acrylic copolymer of the present invention, the total structural unit of the copolymer is 100 mol%, and the fluoroalkyl (meth) acrylate component (component (I)) represented by the formula (I) is 40 mol%. Above, it is 95 mol% or less. More preferably, they are 45 mol% or more and 85 mol% or less, Especially preferably, they are 48 mol% or more and 75 mol% or less. If the fluoroalkyl (meth) acrylate component is less than the lower limit, the solvent resistance is poor, and a suitable release performance cannot be exhibited after time. Further, it may be mixed with the hard coat layer at the interface to cause heavy peeling, resulting in reduced crack resistance or inability to peel. On the other hand, when the fluoroalkyl (meth) acrylate component exceeds the upper limit value, the peel force becomes too light and foil spillage cannot be suppressed, and the film-forming property may be poor.

  Further, the fluorinated acrylic copolymer in the present invention comprises 2 mol of the (meth) acrylic acid component ((II) component) represented by the formula (II), with the total structural unit of the copolymer being 100 mol%. % Or more and 10 mol% or less. More preferably, they are 4 mol% or more and 8 mol% or less, Most preferably, they are 5 mol% or more and 6 mol% or less. If the (meth) acrylic acid component is less than the lower limit, the cohesive force of the release layer is not sufficient because the number of crosslinking points of the copolymer is small, and the solvent resistance to the solvent and the like contained in the hard coating agent coating liquid, Chemical resistance may be poor. In addition, a suitable release performance after the lapse of time may not be exhibited, and there may be a case where interfacial mixing with the hard coat layer causes heavy peeling to reduce crack resistance or make peeling impossible. On the other hand, when the (meth) acrylic acid component exceeds the upper limit value, the compatibility with the fluoroalkyl (meth) acrylate component is deteriorated in the synthesis of the copolymer, and the mold release performance is not sufficiently exhibited. May decrease.

(Other acrylic components)
As a monomer constituting the other copolymerization component of the fluorinated acrylic copolymer, an alkyl (meth) acrylate containing no fluorine represented by the following general formula (III) may be included.

（式（ＩＩＩ）中、Ｒ^３は水素またはメチル基、Ｒ_Ｙは炭素原子数１〜１０の炭化水素基をそれぞれ表わす。）

(In formula (III), R ³ represents hydrogen or a methyl group, and R _Y represents a hydrocarbon group having 1 to 10 carbon atoms.)

  Examples of the alkyl acrylate having 1 to 10 carbon atoms in the alkyl group include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, Examples include hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, and the like. These monomer components may be used alone or in admixture of two or more.

  Examples of the alkyl methacrylate having 1 to 10 carbon atoms in the alkyl group include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, and isoamyl methacrylate. Hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, and the like.

Among these alkyl (meth) acrylates not containing fluorine, those based on methacrylate are preferable, and alkyl methacrylate and alkyl acrylate may be mixed and used.
The content is preferably 3 to 50 mol%, more preferably 11 to 47 mol%, and still more preferably 20 to 46 mol%, based on 100 mol% of all structural units of the fluorinated acrylic copolymer. What is necessary is just to make it be the range which requires a total amount when using two or more together.

(Glass-transition temperature)
The glass transition temperature Tg of the fluorinated acrylic copolymer in the present invention is more than 60 ° C and not more than 85 ° C. More preferably, it is 65 degreeC or more and 80 degrees C or less. When the upper limit is exceeded, the film-forming property is lowered, and suitable peelability cannot be expressed. If it is less than the lower limit, the initial peelability is good, but over time, particularly after processing the hard coat layer, etc., it may be heavily peeled to reduce crack resistance, or it may become impossible to peel.

(Carboxyl group concentration)
The fluoroacrylic copolymer in the present invention preferably has a carboxyl group concentration of 20 mmol (/ 100 g) or more and 190 mmol (/ 100 g) or less with respect to 100 g of the copolymer. The carboxyl group concentration is obtained by first obtaining an acid value (mg number of potassium hydroxide necessary for neutralizing the carboxyl group contained in 100 g of the fluorinated acrylic copolymer), and calculating the molecular weight of potassium hydroxide (g / mol). ) Divided by. Here, the carboxyl group concentration of the fluorinated acrylic copolymer represents the carboxyl group concentration of the fluorinated acrylic copolymer before forming the coating layer.

  The lower limit of the carboxyl group concentration of the fluorinated acrylic copolymer is more preferably 25 mmol / 100 g, particularly preferably 30 mmol / 100 g, and the upper limit is more preferably 150 mmol / 100 g, further preferably. Is 100 mmol / 100 g, particularly preferably 50 mmol / 100 g. If the carboxyl group concentration exceeds the upper limit, the film-forming property tends to be lowered, and the coating appearance may be lowered. Also, if the carboxyl group concentration is less than the lower limit, the cohesive force of the release layer tends to be low because the crosslinking point of the copolymer tends to be low, and the solvent resistance to solvents, etc. in the hard coat agent coating liquid , Chemical resistance tends to be low, suitable mold release performance tends to be difficult to develop after time, and tends to cause heavy peeling due to interfacial mixing with hard coat layer, improving crack resistance Tends to decrease, and in some cases, peeling may not be possible.

(Weight average molecular weight)
The weight average molecular weight of the fluorinated acrylic copolymer used in the present invention is preferably in the range of 5,000 to 1,000,000, more preferably 100,000 to 800,000, and particularly preferably 200,000. ~ 600,000. If the weight average molecular weight is less than the lower limit, the cohesive strength of the release layer tends to be low, the solvent resistance to the hard coat coating solvent tends to be poor, and the mold release performance suitable after time Tends to be difficult to develop, and further tends to be easily peeled off by interfacial mixing with the hard coat layer, tends to reduce crack resistance, and in some cases may not be peeled off. On the other hand, when the weight average molecular weight exceeds the upper limit, the coatability may be lowered due to the increase in the viscosity of the water-dispersed coating liquid.

(Content in release layer)
The content of the fluorinated acrylic copolymer in the release layer is preferably 40% by weight or more and 85% by weight or less based on the weight of the release layer. The upper limit of the content is preferably 80% by weight, more preferably 75% by weight, and particularly preferably 70% by weight. The lower limit is preferably 45% by weight, more preferably 50% by weight, and particularly preferably 55% by weight. The content of the fluorinated acrylic copolymer is within such a range, and is further cross-linked at a cross-linking point including a carboxyl group of (meth) acrylic acid by a cross-linking agent described later contained in the release layer. By this, the adhesiveness with a polyester film, a mold release characteristic, and the solvent resistance with respect to a hard-coat coating solvent can further be improved.

  If the content of the fluorinated acrylic copolymer is less than the lower limit, the effect of improving the crack resistance of the transferred material after time tends to decrease, and the effect of improving the stability of the release performance after time Tend to be lower. In addition, when the content exceeds the upper limit, the content of the crosslinking agent is relatively reduced, so that the cohesive force of the release layer tends to be reduced, and the effect of suppressing foil spillage after time tends to be reduced. In addition, the effect of improving the release property tends to decrease, or the solvent resistance to the hard coat coating solvent tends to be poor, and the effect of improving the peelability over time tends to decrease.

(Method for producing fluorinated acrylic copolymer)
The fluorinated acrylic copolymer in the present invention can be produced by emulsion polymerization. A known redox initiator can be used as the polymerization initiator, and examples thereof include hydrogen peroxide, ammonium persulfate, potassium persulfate, and t-butyl hydroperoxide.

The emulsion polymerization reaction can be carried out at a temperature and reaction time depending on the type of monomer and radical polymerization initiator used and other conditions. As the polymerization conditions, for example, the polymerization reaction temperature can be 50 to 90 ° C., and the polymerization reaction time can be 3 to 24 hours. Emulsion polymerization can also be performed in inert gas atmosphere, such as nitrogen gas or argon gas, for example.
These fluorinated acrylic copolymers may be in the form of an emulsion. Or a powder form may be sufficient. Examples of the method of making the fluorinated acrylic copolymer into a powder form include a method of drying the fluorinated acrylic copolymer prepared by the above method. On the other hand, the emulsion form is preferred from the viewpoint that the coating layer can be prepared easily and in a large area.

  The fluorinated acrylic copolymer in the present invention preferably forms a spherical dispersed phase in the coating liquid, and the average particle size of the dispersed phase is preferably 0.02 to 1.0 μm, more preferably It is 0.03-0.5 micrometer, Most preferably, it is 0.04-0.2 micrometer. Within such a range, the peelability, workability, film-forming property, durability, antifouling property and adhesion to the substrate can be further improved.

[Other resins]
The release layer in the present invention can contain a thermoplastic resin such as a polyester resin and an acrylic resin as another resin, in addition to the above-mentioned fluorinated acrylic copolymer. Among them, an acrylic resin is preferable, and an alkyl (meth) acrylate copolymer containing no fluorine is particularly preferable.

  By using a thermoplastic resin having a moderately low glass transition temperature Tg, it is possible to make the release force of the release layer moderate, thereby further enhancing the effect of suppressing foil spillage. Such Tg is preferably 60 ° C. or less, more preferably 50 ° C. or less, further preferably 30 ° C. or less, and particularly preferably 20 ° C. or less. Further, it is preferably −20 ° C. or higher, more preferably 0 ° C. or higher.

  Although there is no restriction | limiting in particular in a mixture ratio, in order to express a more preferable mold release property from a viewpoint of foil spilling suppression, a thermoplastic resin is 75 weight% or less with respect to 100 weight% of fluorinated acrylic copolymers. It is preferably used, more preferably 50% by weight or less, still more preferably 40% by weight or less, and particularly preferably 35% by weight or less. If it is used beyond this range, there is a tendency that poor peeling is likely to occur locally, and uniform release properties tend to be difficult to obtain. Also, the glass transition temperature as a whole of the thermoplastic resin constituting the release layer tends to decrease, tends to be easily peeled with time, and the effect of improving crack resistance tends to decrease. Depending on the condition, there is a possibility that peeling cannot be performed. Moreover, in order to express more preferable releasability from the viewpoint of suppressing foil spillage, it is preferably 10% by weight or more, more preferably 15% by weight or more.

  In the present invention, a particularly preferable embodiment is an embodiment in which the release layer contains a fluorine-free alkyl (meth) acrylate copolymer having a glass transition temperature Tg in the above preferable range in the above preferable blending amount.

[Crosslinking agent]
In the release layer in the present invention, it is necessary to add a crosslinking agent in order to improve the cohesive force of the layer. When a crosslinking agent is not added, the cohesive force of the release layer is not sufficient, and even if the above-mentioned fluorinated acrylic copolymer is contained, the cohesive failure occurs first, and the fluorinated acrylic copolymer Not only does the mold release performance due to the ink not sufficiently develop, but the mold release characteristics after the lapse of time do not develop, and the hard coat layer may be mixed with the interface to deteriorate the crack resistance, or may not be peeled off.

  As a crosslinking agent, an oxazoline compound, an epoxy compound, a melamine compound, an isocyanate compound can be illustrated, and the compound generally called a coupling agent can also be used. Oxazoline compounds and epoxy compounds are preferably used because of easy handling and the pot life of the coating liquid, and a coupling agent is also preferably used. Furthermore, it is preferable to use an oxazoline compound since the solvent resistance against the hard coat coating solvent is further improved and the peelability after aging is stable. Furthermore, it is preferable from the viewpoint of compatibility with the fluorinated acrylic copolymer, and the film-forming property and coating appearance are stable, which is preferable.

  Furthermore, a polymer containing an oxazoline group is preferable as the oxazoline compound. Specifically, it can be prepared by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer. Addition polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like can be mentioned, and one or a mixture of two or more thereof can be used. Among these, 2-propenyl-2-oxazoline is preferred because it is easily available industrially and is also preferred from the viewpoint of compatibility with the fluorinated acrylic copolymer. The other monomer is not particularly limited as long as it is a monomer copolymerizable with an addition polymerizable oxazoline group-containing monomer.

  Examples of the epoxy compound include polyepoxy compounds, diepoxy compounds, monoepoxy compounds, and the like, and more specifically, glycidyl ether compounds and glycidyl amine compounds thereof are exemplified.

  The melamine compound is preferably a compound obtained by reacting a methylol melamine derivative obtained by condensing melamine and formaldehyde with methyl alcohol, ethyl alcohol, isopropyl alcohol or the like as a lower alcohol, and a mixture thereof. Examples of the methylol melamine derivative include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine and the like.

  Isocyanate compounds include, for example, tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, metaxylylene diisocyanate, hexamethylene-1,6-diisocyanate, 1,6-diisocyanate hexane, an adduct of tolylene diisocyanate and hexane triol, Tolylene diisocyanate and trimethylolpropane adduct, polyol-modified diphenylmethane-4,4'-diisocyanate, carbodiimide-modified diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-vitrylene- 4,4 'diisocyanate, 3,3' dimethyldiphenylmethane-4,4'-diisocyanate, metaphenylene diisocyanate and the like.

  The content of the crosslinking agent is preferably 10% by weight or more and 40% by weight or less based on the weight of the release layer. The upper limit of the addition amount of the crosslinking agent is more preferably 35% by weight, further preferably 30% by weight, and particularly preferably 25% by weight. Moreover, the lower limit of the addition amount of the crosslinking agent is more preferably 15% by weight. When the upper limit is exceeded, the cohesiveness of the coating film tends to be too high, which is not preferable from the viewpoint of appearance and film-forming property, and tends to be difficult to use in terms of recoverability of the polyester film. It is not preferable. Furthermore, since the addition amount of the fluorinated acrylic copolymer is relatively small, the effect of improving the initial peelability tends to decrease, or the effect of improving the crack resistance with time tends to decrease, and In some cases, peeling may not be possible. If it is less than the lower limit value, the cohesiveness of the coating film tends to be lowered, and cohesive failure tends to occur first, and sufficient release performance after aging with a fluorinated acrylic copolymer is difficult to be exhibited. In addition, it tends to be easily peeled by interfacial mixing with the hard coat layer, thereby reducing the effect of improving crack resistance, and in some cases, peeling may not be possible.

[Surfactant]
The fluorinated acrylic copolymer constituting the release layer in the present invention is preferably used in the form of an aqueous dispersion or an emulsion from the viewpoint of ease of handling during coating and working environment. In order to obtain a good aqueous dispersion and emulsion form using such a fluorinated acrylic copolymer, it is preferable to use a surfactant, and dispersion with other components of the coating liquid. Nonionic surfactants are particularly preferred because of their stability. The content of the surfactant is preferably in the range of 15% by weight or less based on the weight of the release layer, more preferably in the range of 10% by weight or less, and particularly preferably in the range of 5% by weight or less. It is. If the upper limit is exceeded, the surfactant tends to be localized on the surface of the release layer due to the bleed-out phenomenon, causing interfacial mixing with the hard coat agent applied on the surface, and the release performance by the release layer of the present invention. Tends to be difficult to fully express.

[Film characteristics]
(Normal peel force)
The initial normal peel force of the pressure-sensitive adhesive tape with respect to the release layer of the mold release polyester film of the present invention is preferably in the range of 0.2 N / mm to 0.5 N / mm, more preferably 0.22 N. / Mm to 0.45 N / mm, particularly preferably 0.25 N / mm to 0.40 N / mm. Here, the initial normal peel force in the present invention was determined by attaching a Nitto Denko adhesive tape (product name “NO.502”) to the surface of the release layer, leaving it at room temperature for 1 hour, and then using a tensile tester. It is a value obtained by performing 180 ° peeling at a pulling speed of 300 mm / min and dividing the average peeling load in a region where peeling is stable by the width of the adhesive tape.

  The mold release layer of the mold release polyester film of the present invention is actually laminated when an in-mold transfer foil is prepared by satisfying the above-described peel force with respect to the initial normal peel force with the adhesive tape. The hard coat coating agent can be applied to the release layer while suitably suppressing the occurrence of omission, and the transfer foil after in-mold transfer is also excellent in releasability. In this case, a mold release characteristic that hardly causes a crack phenomenon is exhibited. In addition, the release layer contains a fluorinated acrylic copolymer with a specific composition, so that it has chemical affinity with the hard coat layer, so that the adhesive strength with the hard coat layer becomes moderately high and foil spillage occurs. It is suppressed.

When the initial normal state peeling force is less than the lower limit, foil spillage tends to occur during slit processing. Moreover, there is a tendency that application omission is likely to occur when the hard coat coating agent is applied onto the release layer. On the other hand, when the initial normal state peeling force exceeds the upper limit value, the adhesive performance acts strongly, and when the transfer product is peeled off, the transfer product tends to be easily cracked.
Such an initial normal peeling force has a crosslinking point by using a fluorinated acrylic copolymer containing the above-mentioned components as a release layer component, and the fluorinated acrylic copolymer contains a certain amount of an acrylic acid component. And by increasing the degree of crosslinking of the release layer with a crosslinking agent.

In the present invention, it is preferable that the change in the normal peeling force is small even after lapse of time (after leaving for 24 hours or 48 hours in a 40 ° C. and 95% wet heat environment). Therefore, it is preferable that the normal peel force with time is in the same range as the initial normal peel force described above. The effect is also the same. The rate of change of the normal peel force with time relative to the initial normal peel force (| normal normal peel force−initial normal peel force | / initial normal peel force) is preferably within ± 20%, more preferably ± 10%. . Thereby, it is possible to obtain a suitable peeling force even after aging.
Such normal peel force over time is obtained by using a fluorinated acrylic copolymer containing the above-mentioned components as a release layer component, and the fluorinated acrylic copolymer contains a certain amount of an acrylic acid component, thereby cross-linking points. And obtained by increasing the degree of crosslinking of the release layer with a crosslinking agent.

(Crack resistance)
The release layer in the present invention uses a fluorinated acrylic copolymer containing the above-mentioned components as a release layer component, and the acrylic acid component contained in the fluorinated acrylic copolymer is crosslinked by a crosslinking agent as a crosslinking point. Therefore, it can have excellent peelability (low peel force), thereby relieving the stress applied to the hard coat layer and the ink layer at the time of molding, and the crack resistance of the transferred hard coat layer is good It will be a thing.

  The crack in the present invention is a phenomenon that occurs at the time of molding if the peeling force between the hard coat layer and the release layer is heavy. Specifically, when the transfer layer including the hard coat layer is simultaneously molded and transferred, if the peeling force between the hard coat layer and the release layer is heavy, stress is applied to a part of the transfer layer, and a part of the transfer layer is not peeled off. This is a phenomenon in which cracks and cracks occur. As a result, minute scratches may be observed, white clouds may be observed, cracks and cracks may be observed, and the decorativeness of the transfer foil may be significantly lost.

Such a phenomenon occurs particularly when the hard coat layer is in an incompletely cured state. As one of the methods for curing the hard coat layer used for molding simultaneous transfer, it is first incompletely cured with heat before being subjected to molding, and then completely cured by irradiating the resulting molded product with ultraviolet rays. A processing method is mentioned. By performing simultaneous molding transfer by in-mold transfer using the release film of the present invention on the incompletely cured hard coat layer, a crack-free transfer product can be obtained.
Further, in the present invention, the crack resistance is excellent even after aging, and there is no change in the crack resistance even after leaving for 24 hours, preferably 48 hours in a 40 ° C. and 95% wet heat environment. preferable.

(Solvent resistance)
The release layer in the present invention has a predetermined amount of the above-mentioned fluorinated acrylic copolymer and has a crosslinked structure with a crosslinking agent, so that a ketone solvent such as methyl ethyl ketone and methyl isobutyl ketone, acetic acid Excellent solvent resistance against ester solvents such as ethyl. By being excellent in the solvent resistance to the solvent, it is possible to suppress abrasion damage due to the solvent when a hard coat layer containing methyl ethyl ketone or the like as a solvent is formed on the release layer. Furthermore, it is possible to suppress the residual solvent remaining due to heat during processing of the hard coat layer from interfacial mixing with the release layer over time, and to stabilize the peelability over time.

[Antistatic release layer]
The mold release polyester film of the present invention preferably has a release layer on one side of the polyester film and further has an antistatic release layer provided on the opposite side of the polyester film from the release layer. Such an antistatic release layer is preferably an antistatic release coating layer provided by coating, and preferably contains an antistatic agent and a release agent. The antistatic release layer is a layer generally provided in a film for transfer material for in-mold, and is often imparted not only with chargeability but also with release properties in order to suppress sticking between transfer foils due to charging. However, a hard coat layer is not provided on such a layer, and the function required in addition to the antistatic property is usually only a release force necessary for preventing sticking between films, and an adhesive force is not required. The functional layer is different from the release layer of the present invention.
By having such a layer, when handling the transfer foil for in-mold transfer, sticking of the transfer foils due to charging and generation of dust and dirt on the transfer foil surface can be suppressed.

As the antistatic agent, a known type of antistatic agent can be used, and a cationic polymer can be preferably used. Moreover, although a well-known thing can be used also as a mold release agent, a silicone type mold release agent can be used preferably. In addition, a crosslinking agent may be further used to increase the cohesive strength of the antistatic release layer, and a surfactant may be used to increase the coating property to the film.
The thickness of the antistatic layer is preferably 0.01 to 0.2 [mu] m, more preferably 0.01 to 0.08 [mu] m, as the thickness after drying. When the thickness of the antistatic layer is less than the lower limit, the antistatic property may be insufficient, and when the thickness exceeds the upper limit, blocking with the in-mold transfer foil may easily occur.

[Coating method]
In the present invention, the release layer is preferably provided on at least one surface of the polyester film and provided only on one surface. As a method for providing the release layer on the polyester film, a method of forming the release layer by applying a coating solution for forming the release layer in the polyester film forming process (sometimes referred to as in-line) is preferable. .

  Conventionally, an easy-adhesion layer was formed on a polyester film, and after such a film was once rolled, a method of providing a release layer on the easy-adhesion layer as a base of a hard coat layer in a separate process was used. On the other hand, in this method, the release layer in the present invention can be directly coated on the polyester film in the process of forming the polyester film, and the process can be simplified. Moreover, since it will dry and heat-process in a horizontal extending process, it is preferable if it apply | coats after the longitudinal stretch in the polyester film manufacturing process by a normal biaxial stretching method.

  The method for laminating the release layer on the polyester film by coating is not particularly limited, and for example, a coating method as shown in Yuji Harasaki, Tsuji Shoten, 1979, “Coating Method” can be used. Specifically, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnated coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar Examples of the method include a coater, an extrusion coater, and a bar coater.

The coating amount of the coating solution is usually 3 to 30 g / m ² , preferably 4 to 20 g / m ² , and more preferably 5 to 10 g / m ² . The thickness of the obtained release layer is preferably 0.01 to 0.2 μm, more preferably 0.01 to 0.08 μm as the thickness after drying. When the thickness of the release layer is less than the lower limit value, the releasability tends to be low, and when the upper limit value is exceeded, the mold release polyester film further has an antistatic release layer and antistatic release It tends to cause blocking with the layer, and drying tends to be insufficient during the formation of the polyester film, making it difficult to form a coating film.

  In the present invention, when it further has an antistatic release layer, such an antistatic release layer is preferably provided on the surface of the polyester film opposite to the release layer. Further, the antistatic release layer is also preferably provided by coating. As a coating method, the same method as the above-mentioned release layer can be used.

[Release polyester film for molding]
The mold release polyester film of the present invention has a coating layer containing a specific fluorinated acrylic copolymer and a crosslinking agent as a release layer on at least one surface of the polyester film, and the fluorinated polyester film. The acrylic copolymer has a configuration in which the glass transition temperature Tg of the acrylic copolymer satisfies a predetermined range. Thereby, when used for molding applications such as in-mold molding, not only in the initial stage but also over time, similarly, it has excellent release properties and workability from the in-mold transfer foil preparation process to molding transfer. Desirable effects such as application of hard coat agent, peeling of hard coat layer, foil spilling during slit processing, generation of dust / foil dust and product surface adhesion of generated waste / foil dust can be achieved, Productivity can be greatly improved. In addition, by using the mold release polyester film of the present invention for molding applications such as in-mold molding, not only at the initial stage but also over time, when the transferred product is peeled off, no crack phenomenon occurs in the transferred product. There is an effect.

  Moreover, conventionally, after laminating an easy-adhesion layer on a polyester film in a film production process, it was a process of laminating a release layer in which a release agent having an organic solvent composition was applied on the easy-adhesion layer in a separate process. However, according to the preferable manufacturing method of the present invention, effects of simplification of the process, addition of low environment, and reduction of cost are also exhibited.

  The mold release polyester film of the present invention has a release coating layer that further contains an antistatic component on the surface opposite to the release layer, and is used for molding applications that perform in-mold transfer. In addition, it has excellent antistatic properties and releasability from the in-mold transfer foil creation process to molding transfer, such as sticking between transfer foils by charging and blocking, dust and dust on the transfer foil surface, etc. Can be suppressed, and productivity can be significantly improved.

  Hereinafter, the present invention will be described in more detail with reference to examples. Various physical properties were evaluated by the following methods. Moreover, wt% represents weight%, and part represents weight part.

(1) Release Layer Thickness, Antistatic Release Layer Thickness A small piece of film is embedded in an epoxy resin (Epomount manufactured by Refine Tech Co., Ltd.), and the embedded resin is 50 nm using a Microtome 2050 manufactured by Reichert-Jung. Sliced to thickness, stained with 2% osmic acid at 60 ° C. for 2 hours, observed with a transmission electron microscope (Topcon LEM-2000) at an acceleration voltage of 100 KV and a magnification of 100,000 times, and the thickness of the coating layer Was measured.

(2) Normal peel force (2-1) Initial normal peel force A 10 cm × 20 cm release film sample was cut out, and a 25 mm wide adhesive tape (trade name “No. 502, manufactured by Nitto Denko Corporation) was formed on the surface of the release layer. ”) Is applied, and a reciprocating load is applied with a pressure roller of 2 kg × 45 mm width. The sample with the tape attached is cut into 25 mm width × 150 mm length and stored at room temperature (23 ° C.) for 1 hour. The adhesive tape surface side is affixed to a 50 mm wide × 125 mm long SUS plate and fixed to a tensile tester (trade name “Tensilon” manufactured by Toyo Baldwin), and the release film is at an angle of 180 °. And peeling at a peeling speed of 300 mm / min, and the load is measured. This measurement was performed 5 times, and the average value was defined as the normal state peeling force (unit: N / mm).

(2-2) Normal peel strength with respect to time With regard to normal peel strength with time, a 10 cm × 20 cm release film sample was cut out and left for 48 hours in a 40 ° C. and 95% wet heat environment, and then the same conditions as in (2-1) above In comparison with the case where the initial acceleration was not carried out, the following criteria were used.
○: The peel force does not change compared to the initial normal peel force. (Change rate is within ± 20%.)
X: The peel force is heavier than the initial normal peel force. (Change rate exceeds + 20%)

(3) Foil spillability (alternative evaluation)
(3-1) Initial foil spillability On the surface of the release layer of the polyester film, a hard coat agent coating solution containing the following thermosetting hard coat agent was applied so that the thickness after drying was 5 μm. And dried in a hot air oven at 120 ° C. for 1 minute to prepare a hard coat layer in an incompletely cured state.
An adhesive tape with a width of 25 mm (manufactured by Nitto Denko Corporation, trade name “No. 31B”) was bonded to the surface of the prepared hard coat layer, and then pressure-bonded with a metal roller (linear pressure 2 kg / cm). After leaving at room temperature for 30 minutes, the adhesive tape was quickly and manually peeled off together with the hard coat layer. At that time, the presence or absence of occurrence of foil spillage in the hard coat layer which was larger than the width of the adhesive tape and was peeled off was observed and evaluated.
○: The same width as the width of the adhesive tape (difference is 1 mm or less) and the hard coat layer is peeled. Δ: Partially wider than the width of the adhesive tape (difference exceeds 1 mm). The hard coat layer is peeled. Wide (difference exceeds 1 mm) hard coat layer peels off

(Hard coating agent coating solution)
A hard coating agent coating solution having a non-volatile component of 30% was prepared using MEK (methyl ethyl ketone) as a solvent with respect to a hard coating agent (product name “TSF028) manufactured by DIC Graphics Corporation as a hard coating agent.

(3-2) Time-lapse foil spillability With respect to time-lapse foil spillability, a sample in which a hard coat layer was prepared under the same conditions as in (3-1) above was allowed to stand in a 40 ° C. and 95% wet heat environment for 24 hours or 48 hours. Then, it evaluated on the same conditions as said (3-1), and performed by the following reference | standard compared with the case where it does not accelerate | stimulate early.
○: No change after 24 hours and 48 hours compared to the initial state Δ: No change after 24 hours, but performance is degraded after 48 hours ×: Performance is degraded after 24 hours "No change" means that the evaluation results are the same, and "Performance degradation" means that the evaluation results become worse.

  Further, the results obtained by the evaluations according to the above (3-1) and (3-2) are correlated with the foil spillability at the time of slitting at the initial stage and after the lapse of time, respectively, that is, those excellent in the foil spillability evaluation are as follows. It was confirmed that the foil spillability at the time of slitting was excellent, and the other one was inferior to the foil spillability at the time of slitting.

(4) Crack resistance (substitute evaluation)
(4-1) Initial crack resistance A hard coat layer is formed on the surface of the release layer of the polyester film under the same conditions as the evaluation of the foil spillability to the release layer of (3-1) above, and the above (3-1) Use a tensile tester (trade name “Tensilon” manufactured by Toyo Baldwin Co., Ltd.) using a sample in which an adhesive tape (trade name “No. 31B” manufactured by Nitto Denko Co., Ltd.) is pressure-bonded to the hard coat layer surface under the same conditions as above. Then, the adhesive tape was peeled off together with the hard coat layer under the condition of 90 ° peeling under the condition of a tensile speed of 300 mm / min. After peeling, the hard coat layer attached to the adhesive tape was observed with a scanning electron microscope manufactured by Hitachi, Ltd.
○: No crack was observed in the peeled hard coat layer.
Δ: Some cracks were observed in the peeled hard coat layer.
X: Cracks were observed in the peeled hard coat layer.

(4-2) Crack resistance over time For evaluation of crack resistance over time, a sample in which a hard coat layer was prepared under the same conditions as in (4-1) above was allowed to stand for 24 hours or 48 hours in a 40 ° C. and 95% wet heat environment. Then, the evaluation was performed under the same conditions as in the above (4-1), and the following criteria were used in comparison with the case where the initial acceleration was not performed.
○: No change after 24 hours and 48 hours compared to the initial state Δ: No change after 24 hours, but performance is degraded after 48 hours ×: Performance is degraded after 24 hours “No change” means that the evaluation results are the same, and “Performance reduction” means that the evaluation results become worse.

(5) Transfer peelability evaluation (hard coat peel strength)
(5-1) Initial peelability evaluation Create a hard coat layer on the surface of the release layer of the polyester film under the same conditions as the evaluation of foil spillability at the time of peeling the hard coat layer with respect to the release layer of (3-1) above, Evaluation is performed using a sample obtained by pressure-bonding an adhesive tape (manufactured by Nitto Denko Corporation, trade name “No. 31B”) to the hard coat layer surface under the same conditions as in the above (3-1). The sample with the tape attached is cut into 25 mm width × 150 mm length and stored at room temperature (23 ° C.) for 1 hour. The adhesive tape surface side is affixed to a 50 mm wide x 125 mm long SUS plate and fixed to a tensile tester (trade name “Tensilon” manufactured by Toyo Baldwin Co., Ltd.), and the release film is at an angle of 180 °. And peeling at a peeling speed of 300 mm / min, and the load is measured. This measurement was performed 5 times, and the average value was taken as the initial peel force (unit: mN / mm). The evaluation was performed based on the following criteria in addition to the numerical value of the peeling force.
○: Peelable △: Hard coat layer partially left ×: Unpeelable

(5-2) Evaluation of peelability over time A sample obtained by processing a hard coat layer under the same conditions as the initial peelability evaluation in (5-1) above was left for 48 hours in a 40 ° C. and 95% wet heat environment, and then the above (5 -1) The peelability with time was evaluated with an adhesive tape (manufactured by Nitto Denko Corporation, trade name “No. 31B”) under the same conditions. The evaluation was performed based on the following criteria as compared with the case where the initial acceleration was not performed, in addition to the numerical value of the peeling force.
◎: Peeling force does not increase and no change ○: Peeling force increases at less than 20% △: Peeling force increases at 20% or more and less than 70% ×: Peeling force increases by 70% or more Or cannot peel

(6) Acid value of fluorinated acrylic copolymer (carboxyl group concentration)
The acid value (carboxyl group concentration) of the fluorinated acrylic copolymer was measured by a neutralization titration method according to JIS K0070. 0.15 g of a fluorinated acrylic copolymer was precisely weighed, 5 ml of benzyl alcohol was added and dissolved by heating. After mixing 10 ml of chloroform with this, phenol red was added as an indicator, neutralization titration was performed with a 0.1 N KOH benzyl alcohol solution while stirring, and the number of mg of KOH consumed for neutralization was calculated per 100 g of resin. The converted value was determined as the acid value (carboxyl group concentration, mmol / 100 g).

(7) Solvent resistance evaluation The surface of the release layer of the film was overlaid with gauze soaked in a mixed solution of methyl ethyl ketone / toluene. Observe the condition of the coated surface of the part. The state of ○ satisfies normal performance.
○: No change △: Missing part ×: Missing overall

(8) Measurement of glass transition temperature Tg According to JIS standard (K7121), glass transition temperature Tg was calculated | required by DSC method. The sample amount was 10 mg, the temperature was 20 to 290 ° C., and the temperature elevation rate was 20 ° C./min.

[Example 1]
Molten polyethylene terephthalate ([η] = 0.64 dl / g, Tg = 78 ° C.) containing 0.01 wt% of silicon oxide particles having an average particle diameter of 2 μm is extruded from a die, cooled by a cooling drum by a conventional method, and unstretched After the film was stretched 3.4 times in the longitudinal direction, a release layer coating solution having the release layer constituents shown in Table 1 at the solid content composition ratio shown in Table 1 (solid content concentration 4 wt% application) Liquid) on one surface of the film as a wet coating amount of 6 g / m ² (after drying, the coating layer thickness on the resulting film is 0.04 μm), and on the opposite surface, coating for an antistatic release layer The liquid (solid content concentration 2.0 wt% coating solution) is 6 g / m ² (weighs 0.02 μm as the coating layer thickness on the film obtained after drying) as the wet coating amount on the back surface of the film. Roll coat It was uniformly applied in the over.
The coated film was subsequently dried at 105 ° C., stretched 3.5 times in the transverse direction at 140 ° C., and heat-set at 230 ° C., and biaxially stretched with a thickness of 50 μm having a release layer shown in Table 1. A polyester film was obtained. The measurement results of the physical properties of the obtained film are shown in Table 1.
When the coating liquid was applied onto the polyester film, the release layer of this example was able to be uniformly applied to the entire surface of the film, and no coating spots were generated, and the film forming property was excellent.

[Examples 2-7, Comparative Examples 1-4]
A biaxially stretched polyester film having a release layer was obtained in the same manner as in Example 1 except that the composition of the coating solution was changed as shown in Table 1.
In Comparative Example 3, with respect to the hard coat peeling force after the lapse of time, the hard coat layer could not be peeled off.
In Comparative Example 4, the hard coat layer could not be formed, and the hard coat peeling force could not be evaluated.

[Production Example: Production of fluorinated acrylic copolymer A]
Fluoroacrylic copolymer A (trifluoromethyl methacrylate (72.9 mol%)-n-butyl acrylate (14.2 mol%)-ethyl methacrylate (7.6 mol%)-acrylic acid (5.3 mol%) Polymer; glass transition temperature 75 ° C.):
The fluorinated acrylic copolymer A was obtained as follows.
That is, 1700 parts by weight of ion-exchanged water and 35.4 parts by weight of alkyldiphenyl ether disulfonate as an emulsifier were charged in a four-necked flask and the temperature was raised to 80 ° C. in a nitrogen stream, and then ammonium persulfate 10. 9 parts by weight was added, and 214.4 parts by weight of trifluoromethyl methacrylate, 13.4 parts by weight of n-butyl acrylate, 9.8 parts by weight of ethyl methacrylate, and 1.5 parts by weight of acrylic acid were added over 3 hours. The mixture was added dropwise while adjusting the temperature to 70 to 80 ° C., and the reaction was continued with stirring while maintaining the same temperature for 5 hours after completion of the addition, and then cooled and dried in a vacuum dryer to obtain an average particle size of 0. An aqueous dispersion of fluorinated acrylic copolymer A having a thickness of 0.065 μm and a nonvolatile component weight of 20% was obtained.

[Production Example: Production of fluorinated acrylic copolymers B to F]
-Fluoroacrylic copolymers B to F:
In the same synthesis and polymerization method as the above-mentioned fluorinated acrylic copolymer A, the amount of each raw material is adjusted so that the component ratios shown in Table 2 are obtained, and the fluorinated acrylic copolymers BF An aqueous dispersion was obtained.

[Production Example: Production of acrylic copolymer G containing no fluorine]
-Acrylic copolymer G not containing fluorine:
In the same synthesis and polymerization method as the above-mentioned fluorinated acrylic copolymer A, the amount of each raw material was adjusted so that the component ratios shown in Table 3 were obtained, and an acrylic copolymer G containing no fluorine ( An aqueous dispersion having a Tg of 10 ° C. was obtained.

Crosslinking agent 1: Oxazoline compound (Nippon Shokubai Co., Ltd., trade name “Epocross WS-700”)
Crosslinking agent 2: Epoxy compound (Mitsubishi Gas Chemical Co., Ltd., trade name “TETRAD-X”)
Surfactant: Polyoxyethylene (n = 12) dodecyl ether (manufactured by Sanyo Chemical Co., Ltd., trade name “Sannonic SS-70”)

[Production Example: Production of coating liquid for forming antistatic release layer]
-Silicone component: Epoxy group-containing silicone (product name TSF4730, manufactured by Momentive Performance Material Japan GK)
Cationic polymer: A copolymer having a structure represented by the following formula (IV) consisting of 80 mol% / methyl acrylate 15 mol% / N-methylol acrylamide 5 mol% was used.

（式（ＩＶ）中、Ｒ^Ａ、Ｒ^ＢはそれぞれＨであり、Ｒ^Ｃは炭素原子数が３のアルキレン基であり、Ｒ^Ｄ、Ｒ^Ｅはそれぞれ炭素原子数が１の飽和炭化水素基であり、Ｒ^Ｆは炭素原子数が３のヒドロキシアルキレン基であり、Ｙ⁻はメチルスルホネートイオンである。）

(In the formula (IV), R ^A and R ^B are each H, R ^C is an alkylene group having 3 carbon atoms, and R ^D and R ^E are each a saturated hydrocarbon group having 1 carbon atom. And R ^F is a hydroxyalkylene group having 3 carbon atoms, and Y ⁻ is a methyl sulfonate ion.)

・ Crosslinking agent: Oxazoline compound (product name “Epocross K-2030E” manufactured by Nippon Shokubai Co., Ltd.)
Surfactant: polyoxyethylene (n = 7) lauryl ether (trade name “Naroacty N-70” manufactured by Sanyo Chemical Co., Ltd.)

  Mix so that the solid content mass ratio of the silicone component / cationic polymer / crosslinking agent / surfactant / lubricant is 15/45 / 9.5 / 15.5 / 15, so that the solid content concentration is 2%. A coating solution diluted in water was used as a coating solution for forming an antistatic release layer.

  The mold release polyester film of the present invention has not only the initial mold release property but also the release property with time, and has excellent release properties of the release layer, and when slit (cut) with an appropriate width. In addition, since the foil spilling phenomenon is suppressed and cracking (cracking) of the transferred product at the time of peeling is suppressed, it can be suitably used as a release polyester film for molding such as molding processing involving in-mold transfer. .

Claims (8)

The polyester film has a release layer on at least one surface, and the release layer comprises a fluoroalkyl (meth) acrylate component ((I) component) represented by the following general formula (I) and the following general formula (II): A (meth) acrylic acid component (component (II)) represented by a copolymer, and a cross-linking agent.
In the copolymer, the total structural unit of the copolymer is 100 mol%, the content of the component (I) is 40 to 95 mol%, and the content of the component (II) is 2 to 10 mol%. Yes, the glass transition temperature Tg of the copolymer is more than 60 ° C and 85 ° C or less,
The content of the copolymer in the release layer is 40% by weight or more and 85% by weight or less based on the weight of the release layer.
Mold release polyester film.

(In the formulas (I) and (II), R ^{1 to} R ² are hydrogen or a methyl group, R _X is a hydrocarbon group having 1 to 10 carbon atoms, and R _f is a fluoroalkyl group having 3 to 9 fluorine atoms, respectively. Represents.)   The mold release polyester film of Claim 1 whose content of the said crosslinking agent in a mold release layer is 10 to 40 weight% on the basis of the weight of a mold release layer.   The mold release polyester film according to claim 1 or 2, wherein the crosslinking agent is a crosslinking agent having an oxazoline group.   The mold release polyester film according to any one of claims 1 to 3, wherein a normal peel force of the release layer to the adhesive tape is 0.2 N / mm or more and 0.5 N / mm or less.   The release polyester film for molding according to any one of claims 1 to 4, wherein the release layer is directly provided on the polyester film.   The mold release polyester film of any one of Claims 1-5 formed by apply | coating a mold release layer within the film forming process of a polyester film.   The mold release according to any one of claims 1 to 6, further comprising a release layer on one side of the polyester film, and further having an antistatic release layer on a surface opposite to the release layer of the polyester film. Type polyester film.   The mold release polyester film according to any one of claims 1 to 7, which is used for in-mold molding.