JP5495609B2 - Release film - Google Patents

Description

The present invention is characterized in that it is a release film provided with a release layer in which the dependency of the peeling force on the coating thickness is as small as possible. For example, it is suitable for use in a production process in which a release layer is made thin as a film is deformed, for example, for forming a transfer foil at the same time as molding (hereinafter sometimes abbreviated as in-mold). Can do.

Conventionally, polyester films represented by polyethylene terephthalate and polyethylene naphthalate have excellent mechanical performance, dimensional stability, flatness, heat resistance, chemical resistance, optical properties, etc., and excellent cost performance. Therefore, it is used for various purposes. However, as the applications diversify, the film processing conditions and usage conditions tend to diversify. As an example, a release film for producing an in-mold transfer foil can be mentioned. Generally, a transfer foil using the release film has a structure such as a design printing layer and an adhesive layer in order on a release layer on one side. The transfer layer is laminated, and a hard coat layer, a metal vapor deposition layer, or the like is laminated on the transfer layer according to the purpose. Further, a functional agent such as an antistatic agent or an antibacterial agent is added to the release layer or the transfer layer to give a function as a transfer foil.

Regarding the transfer method of the transfer foil described above, the transfer foil is set in an injection mold, and a resin molded product is molded. At the same time, the transfer foil sheet is integrated and bonded to the surface, and the design is applied to the resin molded product. Transfer and decorate. A so-called in-mold transfer method (molding simultaneous transfer method) is widely known.

Such a transfer method is a method of transferring to a transfer object via an adhesive layer using a plurality of laminated transfer foils including an adhesive layer on the surface of a polyester base material. It is used in a wide range of applications for the purpose of surface treatment such as decoration and surface protection on the surface of various resin molded products such as automobile parts, cosmetic containers, and toys.

Also, in molding applications, the diaphragm in molding processing varies greatly depending on various applications, such as cellular phones and electrical products, from those with a narrow diaphragm during molding to those with a large diaphragm during molding such as automobiles. The drawing in this forming process is classified into shallow drawing, medium drawing, and deep drawing, and a suitable base film is selected and used according to the intended application.

As a problem in using a release film, printing and adhesive layers, such as coating and printing, are affected by drying temperature and tension, and the release film undergoes thermal dimensional changes due to stretch deformation and width shrinkage, resulting in printing. There may be problems such as deviation and flatness deterioration. Therefore, certain required thermal dimension stability and mechanical characteristics are required for the release film. However, the transfer foil laminated using this release film also has high mechanical strength, so the deformation stress is high during in-mold molding, the followability with the mold is poor, and the printing is clear. There was a problem that chipping phenomenon and molding breakage were likely to occur.

  With regard to the release layer constituting the release film, the release layer tends to become thinner as the film is stretched in the molding process, and the desired release force can be obtained even when the release layer is thinly stretched. It is in a situation where expression is required. Therefore, at present, in the release layer provided off-line, the application thickness (after drying) of the release layer is set to several μm level, and the application thickness is sufficiently increased. (For example, Patent Document 1)

  However, in the above-described method, the heavy peeling due to the thinning of the release layer is improved, but in order to sufficiently cure the release layer, for example, the film may be baked at a high temperature of 180 ° C. or higher. Originally, the good dimensional stability and formability of the film may be impaired.

  On the other hand, in-line, when the release layer is provided on the polyester film, the above-mentioned problems related to the coating film curability can be avoided, but in the release layer used for general purposes, a certain coating thickness (after drying) The peel strength tended to increase suddenly when the film thickness was reduced below the region. For this reason, it has been difficult to cope with a manufacturing process in which the thickness of the release layer is reduced as the film is deformed, such as for manufacturing a simultaneous molding transfer foil.

At present, regarding the coating thickness of the release layer, a release film with a release layer that has the smallest possible increase in peel force as the release layer is thinned, that is, the so-called release force dependency of the peel force as small as possible is required. It is in the situation to be.

International Publication WO2005 / 7380 Pamphlet

The present invention is intended to solve the above-mentioned problems, and the problem to be solved is the application of so-called peeling force, in which the increase in peeling force accompanying the reduction in the thickness of the release layer is as small as possible with respect to the coating thickness of the release layer. By using a release layer having as little thickness dependence as possible, for example, it has a film stretching process such as simultaneous molding (hereinafter sometimes abbreviated as “in-mold”) for producing a transfer foil. An object of the present invention is to provide a release film having good release properties and good moldability without extremely heavy peeling in the production process in which the release layer is thinned.

  As a result of intensive studies in view of the above problems, the present inventors provide a release film suitable for in-mold transfer, for example, without deteriorating excellent film characteristics, according to a release film having a specific configuration. The inventors have found what can be done and have completed the present invention.

That is, the gist of the present invention is that a polyester resin (C) containing a 5- chain sulfoisophthalic acid component as a long-chain alkyl compound (A), a thermosetting compound (B) and an acid component on at least one film surface. ), A release film provided with a release layer, which satisfies the following formula (1) at the same time.
F2 / F1 ≦ 2 (1)
(In the above formula, F2 is the release film, the peeling force (mN / cm) between the release layer and the acrylic adhesive tape after 100% stretching, and F1 is the release layer before 100% stretching in the release film. And represents the peel force (mN / cm) between the adhesive tape and the acrylic adhesive tape.)

The release film in the present invention is characterized in that it is a release film provided with a release layer in which the dependency of the peeling force on the coating thickness is as small as possible. For example, at the same time as molding (hereinafter sometimes abbreviated as in-mold), for transfer foil production, etc., it has a film stretching process, and it can cope with the manufacturing process in which the release layer becomes thinner with film deformation, The industrial value of the present invention is very large.

Hereinafter, the present invention will be described in more detail.
In the release film of the present invention, a release layer is provided on at least one film surface, and it is possible to provide a release layer on both surfaces of the film depending on applications.
The film (polyester film) constituting the release film in the present invention may be a single layer structure or a laminated structure. For example, as long as it does not exceed the gist of the present invention other than a two-layer or three-layer structure, There may be four or more layers, and it is not particularly limited.

  The polyester used for the polyester film in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyester includes polyethylene terephthalate (PET) and the like. On the other hand, examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (eg, P-oxybenzoic acid). 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, is mentioned. In any case, the polyester referred to in the present invention refers to a polyester that is usually 60 mol% or more, preferably 80 mol% or more of polyethylene terephthalate or the like which is an ethylene terephthalate unit.

  In the present invention, it is preferable to blend particles in the polyester layer mainly for the purpose of imparting slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed during the polyester production process.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.01-1 micrometer. When the average particle diameter is less than 0.01 μm, the particles are likely to aggregate and dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 3 μm, the surface roughness of the film becomes too rough and There may be a problem when a release layer is applied in the process.

  Furthermore, the particle content in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film is insufficient. There is.

  The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of producing the polyester constituting each layer, but preferably a polycondensation reaction may be carried out after the esterification stage or after the transesterification reaction.

  Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  Although the thickness of the polyester film which comprises the release film of this invention will not be specifically limited if it is a range which can be formed into a film, Usually, 5-250 micrometers, Preferably it is the range of 5-188 micrometers.

Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all.
First, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, the extending | stretching temperature orthogonal to the extending | stretching direction of the 1st step is 70-170 degreeC normally, and a draw ratio is 3.0 to 7 times normally, Preferably it is 3.5 to 6 times. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  The simultaneous biaxial stretching method can also be adopted for the production of the polyester film in the present invention. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is as follows: The area magnification is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

  Furthermore, a so-called coating stretching method (in-line coating) in which the film surface is treated during the above-described polyester film stretching step can be applied. When a coating layer is provided on a polyester film by a coating stretching method, coating can be performed simultaneously with stretching and the thickness of the coating layer can be reduced according to the stretching ratio, producing a film suitable as a polyester film. it can.

Next, formation of the release layer in the present invention will be described.
In the present invention, as a required characteristic for a release film, it is necessary to provide a thin release layer on a flattened polyester film. Therefore, the release layer is formed on the polyester film by a coating stretching method (inline coating). It is preferable to be provided.

The coating stretching method (in-line coating) is not limited to the following, but for example, in sequential biaxial stretching, the first stage of stretching may be completed and the coating treatment may be performed before the second stage of stretching. it can. When a release layer is provided on a polyester film by a coating and stretching method, the film can be applied simultaneously with stretching, and the thickness of the release layer can be reduced according to the stretching ratio. Can be manufactured.

With respect to the release layer constituting the release film in the present invention, a release agent (A), a thermosetting compound (B), and a binder are included in the release layer in order to improve release properties before and after film stretching. The polymer (C) is preferably contained. The release agent (A) contains at least one release agent (A) selected from fluorine compounds, long-chain alkyl compounds and waxes as a constituent material. These release agents may be used alone or in combination.

  The fluorine compound in the present invention is a compound containing a fluorine atom in the compound. Organic fluorine compounds are preferably used in terms of planarity due to in-line coating, and examples include perfluoroalkyl group-containing compounds, polymers of olefin compounds containing fluorine atoms, and aromatic fluorine compounds such as fluorobenzene. . In view of heat resistance and contamination due to transfer, a polymer compound is preferable.

  The long-chain alkyl compound in the present invention is a compound having a linear or branched alkyl group having 6 or more, particularly preferably 8 or more carbon atoms. Specific examples include, but are not limited to, long-chain alkyl group-containing polyvinyl resins, long-chain alkyl group-containing acrylic resins, long-chain alkyl group-containing polyester resins, long-chain alkyl group-containing amine compounds, long-chain alkyl groups. And an ether compound, a long-chain alkyl group-containing quaternary ammonium salt, and the like. In consideration of the transfer of the component derived from the release layer to the surface of the counterpart base material bonded when the release film is peeled off, a polymer compound is preferable.

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

With respect to the release agent (A) contained in the release layer, it is preferable for use of the present invention to use a long-chain alkyl compound in terms of being able to adjust the peeling force over a wide range.

  Various known resins can be used as the thermosetting compound (B) used in the release layer of the present invention, and examples thereof include melamine compounds, epoxy compounds, oxazoline compounds, isocyanate compounds and the like. A melamine compound is more preferable in that it has excellent heat resistance during heat transfer and does not lower the releasability.

  Examples of the melamine compound in the present invention include methoxymethylated melamine and butoxymethylated melamine which are alkylol or alkoxyalkylolated melamine compounds, and those obtained by co-condensing urea or the like with a part of melamine can also be used. .

  As an epoxy compound in this invention, the compound containing an epoxy group in a molecule | numerator, its prepolymer, and hardened | cured material are mentioned, for example. A typical example is a condensate of epichlorohydrin and bisphenol A. In particular, a reaction product of a low molecular polyol with epichlorohydrin gives an epoxy resin having excellent water solubility.

  The oxazoline compound in the present invention is a compound having an oxazoline ring in the molecule, and includes a monomer having an oxazoline ring and a polymer synthesized using the oxazoline compound as one of raw material monomers.

  The isocyanate compound in the present invention refers to a compound having an isocyanate group in the molecule, specifically, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, naphthalene diisocyanate, tolylene diisocyanate. And their polymers and derivatives.

  These thermosetting compounds may be used alone or in combination of two or more. It can also be used with a catalyst to promote thermosetting. Furthermore, when consideration is given to application to in-line coating, it is preferable to have water solubility or water dispersibility.

  Concerning the release layer constituting the release film in the present invention, the binder polymer (C) is used in combination for the purpose of adjusting the peeling force, improving the adhesion between the polyester film and the release layer, or improving the coated surface of the release layer. There is a need to.

  The “binder polymer” used in the present invention is a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) according to a polymer compound safety evaluation flow scheme (sponsored by the Chemical Substance Council in November 1985). ) Is a polymer compound having a molecular weight of 1000 or more and having a film-forming property.

  Specific examples of the binder polymer (C) include polyester resin, acrylic resin, urethane resin, polyvinyl, polyalkylene glycol, polyalkyleneimine, celluloses, and starches.

  Further, for the purpose of improving the adhesion and slipperiness of the coating layer, inert particles may be contained, and specific examples include silica, alumina, kaolin, calcium carbonate, titanium oxide, organic particles, and the like.

  Furthermore, as long as it does not impair the gist of the present invention, an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, etc. May be contained.

  In the present invention, conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating and the like can be used as a method for providing a release layer on the polyester film. Regarding the coating method, there is a description example in “Coating method” published by Yasuharu Harasaki in 1979.

  In the present invention, the curing conditions for forming the release layer on the polyester film are not particularly limited. For example, when the release layer is provided by a coating stretching method (in-line coating), it is usually 170 to 280. The heat treatment may be performed for 3 to 40 seconds at a temperature, preferably 200 to 280 ° C. for a time of 3 to 40 seconds. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. In addition, a conventionally well-known apparatus and energy source can be used as an energy source for hardening by active energy ray irradiation.

From coating amount (after drying) a surface of the coating of the release layer, typically 0.01~0.4g / ^{m 2,} preferably 0.01~0.2g / ^{m 2,} more preferably 0.01 to 0.1 g / ^{m 2,} and most preferably in the range of 0.01-0.04 / ^{m 2.} When the coating amount (after drying) is less than 0.01 g / m ² , the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, in the case of thick coating exceeding 0.4 g / m ² , the coating film adhesion and curability of the release layer itself may be lowered.

As a feature of the release film in the present invention, conventionally, it has been difficult to ensure good release characteristics in a region where the application thickness of the release layer (after drying) is 0.5 g / m ² or less (for example, There is an example described in Patent Document 5.) However, by using the release layer of the present invention, it is possible to ensure good peeling characteristics in the above-described thin film region.
Further, incidentally, by using the release layer of the present invention, it is possible to omit one manufacturing step, which has the advantage of contributing to productivity improvement.

When the release film in the present invention is used for producing a molded simultaneous transfer foil, it is preferable that the difference in peeling force between the release layers before and after stretching the film is as small as possible.
However, in general, a release layer used for general purposes does not involve a film stretching step, and therefore, in many cases, the dependency of the peeling force on the coating thickness is not taken into consideration. Therefore, in a release layer that is generally used for general purposes, as the coating thickness (after drying) of the release layer becomes thinner, for example, the set coating thickness (after drying) is 0.03 (g / m). ² ) When reaching the following region (after drying), the peeling force tended to increase rapidly.

On the other hand, in the case of a release layer used off-line, taking into consideration the thinning of the release layer after stretching the film, the coating thickness (after drying) is preliminarily applied to a level of several μm. There was a trend.

  The present inventors pay attention to the relationship between the coating thickness (after drying) of the release layer and the release characteristics, and by using a release layer that exhibits a release force behavior different from that of the conventional release layer, the release layer before and after film stretching. It has been found that it is possible to reduce the difference in peeling force between the two, and the present invention has been completed.

Regarding the release film in the present invention, the peeling force (F2) between the release layer after 100% elongation of the release film and the acrylic adhesive tape (F2) and the release layer and the acrylic adhesive tape before 100% extension of the release film The relationship with the peeling force (F1) needs to satisfy the following formula (1) at the same time. F2 / F1 ≦ 3 (1)
The F2 / F1 value is preferably 2 or less. When the F2 / F1 value is out of the range of the above formula (1), after molding using a release film, the release layer has a large coating thickness dependency, and the release layer has a heavy peeling force after stretching. It may be difficult to peel off.

Further, in the release layer constituting the release film in the present invention, as a specific method for satisfying the above formula (1), in order to reduce the dependency of the peeling force on the coating thickness, The content ratio of the binder polymer (C) is preferably 60% by weight at the maximum, and more preferably 40% by weight or less. When the content ratio of the binder polymer (C) exceeds 60% by weight, and when the binder polymer (C) is not contained, for example, the set coating thickness (after drying) is 0.03 as the release layer becomes thinner. In the region below (g / m ² ), the peel force may increase rapidly. Regarding the content of the binder polymer (C) in the release layer, for example, when the binder polymer (C2) described in the examples is used, it is one component among the acid components constituting the binder polymer. Quantitative information can be obtained by elemental analysis of sulfur element derived from Na-sulfoisophthalic acid.

  As described above, the present inventors have found that the use of a predetermined amount of the binder polymer (C) in the release layer has an effect of further reducing the coating thickness dependency of the release layer. It came to complete. In addition, peeling force here is force required when peeling the release film of this invention.

Unlike the normal usage method, the release film in the present invention has a film stretching step, so that it is considered that the release layer is deformed as the film is stretched. As a result, in the re-molded release layer after stretching the film, part of the component exhibiting releasability is buried in the release layer, resulting in heavy peeling (peeling force is increased). It is thought that there is a tendency to increase). Therefore, with respect to the release film in the present invention, it is preferable that the component imparting releasability exists as much as possible on the outermost surface of the film even after the film is stretched.

From such a viewpoint, regarding the release layer constituting the release film in the present invention, the above-mentioned formula (1) is satisfied, and as an additional requirement, regarding the binder polymer (C) used in the release layer, The use of a polyester resin is preferable in that good release properties can be secured even when the release layer is further thinned.

Regarding the release film in the present invention, by using the binder polymer (C) in combination with the release layer, it is possible to further change the peel force especially when the release layer coating thickness (after drying) is 0.03 g / m ² or less. This is preferable in that it can be made smaller.

  With respect to the release film in the present invention, a coating layer such as an antistatic layer, an adhesive layer, and an oligomer precipitation preventing layer may be provided on the surface on which the release layer is not provided as long as the gist of the present invention is not impaired.

  Further, the polyester film constituting the release film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measuring method used in the present invention is as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Measurement of average particle diameter (d ₅₀ : μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Evaluation of Release Force (F1) of Release Film After attaching an adhesive tape (Nitto Denko “No. 31B”) to the release layer surface of the sample film, release force after standing at room temperature for 1 hour Measure. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.

(4) Evaluation of peel force (F2) of release film (after 100% elongation) Sample film having a length of 50 mm and a width of 15 mm at a temperature of 25 ° C. using an Intesco tensile tester Intesco model 2001 type Was subjected to a tensile test at a speed of 200 mm / min to obtain a sample film after 100% elongation. Next, the peeling force (F2) was measured according to the procedure of item (6).

(5) Evaluation of peel force ratio (F2 / F1) in the release film In the sample film, the F2 / F1 value was calculated using the peel force values obtained in (3) and (4), and the following determination was made. Judgment was made according to the criteria.
<Criteria>
A: F2 / F1 ≦ 2 (particularly good peelability)
○: 2 <F2 / F1 ≦ 3 (excellent peelability)
X: F2 / F1> 3 (poor peelability)
Among the above judgment criteria, “◯” or more is a level that can be used practically without any problem.

(6) Releasability (F3) evaluation (practical property substitution evaluation)
With respect to the sample film, a top coat layer having the following coating composition was coated on the release surface under the following coating conditions. Next, according to the procedure of the item (4), the sample film was pulled in the longitudinal direction and stretched 100%, and then the releasability (F3) between the topcoat layer and the release layer was determined according to the following criteria.
<Topcoat composition>
In a four-liter flask having a capacity of 2 liters equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a cooling tube, 340 g of 2-ethylhexyl acrylate (hereinafter referred to as 2-EHA) and isobornyl acrylate (hereinafter referred to as iBoA) 600 g, 60 g of 2-hydroxyethyl acrylate (hereinafter referred to as 2-HEA), and 3.0 g of n-dodecyl mercaptan were charged, and the flask was heated to 55 ° C. while replacing the air in the flask with nitrogen. . Subsequently, 2, -2 ′ azobis (4-methoxy-2,4-dimethylvaleronitrile) (trade name V-70; manufactured by Wako Pure Chemical Industries, Ltd. (hereinafter referred to as V-70)) 0 as a polymerization initiator 0.025 g was added with stirring and mixed uniformly After the polymerization initiator was added, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 120 ° C. When the temperature of the reaction system dropped to 115 ° C., 68.0 g of 2-EHA, 120.0 g of iBoA, 12.0 g of 2-HEA, and 1.5 g of n-dodecyl mercaptan The mixture was added and cooled to 55 ° C., and the temperature was maintained and stirred for 30 minutes while purging with nitrogen.
Next, 0.05 g of V-70 was added as a polymerization initiator under stirring and mixed uniformly. After the polymerization initiator was charged, the temperature of the reaction system increased to 115 ° C. and then gradually began to decrease. When the temperature of the reaction system dropped to 110 ° C., 102.0 g of 2-EHA, 180.0 g of iBoA, and 18.0 g of 2-HEA were added, followed by cooling to obtain acrylic syrup A. This syrup had a monomer concentration of 50% and a polymer concentration of 50%, and the weight average molecular weight by GPC of the polymer was 50,000. 1,200 hexanediol diacrylate (trade name light acrylate 1,6HX-A; manufactured by Kyoeisha Chemical Co., Ltd .: hereinafter referred to as HX-A) with respect to 200 parts by mass of the syrup A (100 parts by mass of the monomer mixture) 1. 0 parts by mass (1.8 parts by mass with respect to 100 parts by mass of iBoA), 18.8 parts by mass of isocyanurate HDI (trade name Duranate TPA100; manufactured by Asahi Kasei Co., Ltd .: hereinafter referred to as TPA), silica particles (trade name Type R) -972; manufactured by Tegusa: hereinafter referred to as R-972) 6.0 parts by mass, peroxide-based initiator: cumyl-peroxy-neodecanoate (trade name Park Mill ND; manufactured by Nippon Oil & Fats Co., Ltd .: hereinafter referred to as initiator ND 2.0 parts by mass, 1,1,3,3-tetramethylbutyl-peroxy-2-ethylhexanoate (trade name Perocta O; manufactured by NOF Corporation: hereinafter referred to as initiator PO) 3. 0 part by mass, tin-based curing accelerator (trade name Neostan U-340; manufactured by Nitto Kasei Co., Ltd .: hereinafter referred to as U-340) 0.12 part by mass is added, mixed and defoamed, and thermally polymerized. Composition A-1 was prepared.
<Application conditions>
Drying conditions: 120 ° C. × 10 minutes Application amount (after drying): 80 (g / m ² )
Application method: Bar coat method <Criteria>
○: Good peelability.
Δ: Slightly heavy, but peelable
X: Difficult to peel off
Among the above judgment criteria, Δ or more is a level that can be used practically without any problem.

(7) Evaluation of moldability of release film Roll-shaped film samples were unwound with a tension of 8 MPa, subjected to four-color gravure printing, and then dried at 180 ° C for 30 seconds to produce a picture-printing film. did. Next, the pattern printing film was continuously formed at a speed of 100 pieces / min into a cylindrical shape having a bottom diameter of 50 mm and a depth of 2 mm using a male and female mold. The state of the obtained sample was visually observed and judged according to the following criteria.
<Criteria>
○: 95 or more out of 100 films are not uniformly broken and are uniformly formed.
(Triangle | delta): 80 or more of 100 pieces do not generate | occur | produce a film tear, and are shape | molded uniformly.
X: Film breakage occurs in 21 or more of 100 films, and many defective parts are observed.
Among the above judgment criteria, Δ or more is a level that can be used practically without any problem.

(8) Comprehensive evaluation Comprehensive evaluation was performed on the release film according to the following criteria.
<Criteria>
○: All items of releasability (F3) and formability are ○
Δ: At least one of the releasability (F3) and moldability is Δ
×: At least one item of releasability (F3) and moldability is ×
Among the above judgment criteria, Δ or more is a level that can be used practically without any problem.

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyethylene terephthalate A1)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 part of ethylene glycol slurry ethyl acid phosphate, 0.03 part of antimony trioxide and 0.01 part of silica particles having an average particle diameter of 1.5 μm were added, and then the temperature was 280 ° C. and the pressure was increased in 100 minutes. The pressure reached 15 mmHg, and the pressure was gradually reduced thereafter to finally reach 0.3 mmHg. After 4 hours, the system was returned to atmospheric pressure to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.61.

Example 1
The polyethylene terephthalate A1 produced in Production Example 1 was dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature was adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. First, the obtained unstretched sheet was stretched 3.6 times in the MD direction at 95 ° C., led to a tenter, and sequentially biaxially stretched 4.3 times in the TD direction. Thereafter, it was heat-fixed at 230 ° C. for 3 seconds to obtain a PET film having a thickness of 38 μm.
Next, the following coating agent was applied by a reverse gravure coating method so that the coating amount (after drying) was 0.03 g / m ^2, and then heat-treated at 130 ° C. for 10 seconds.

Examples of compounds constituting the release layer are as follows.
(Example compounds)

Long chain alkyl compound (A1):
To a four-necked flask, 200 parts of xylene and 600 parts of otadecyl isocyanate were added and heated with stirring. From the time when xylene began to reflux, 100 parts of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% was added in small portions over a period of about 2 hours. After the addition of polyvinyl alcohol, the reaction was completed by further refluxing for 2 hours. When the reaction mixture was cooled to about 80 ° C. and added to methanol, the reaction product was precipitated as a white precipitate. This precipitate was filtered off, added with 140 parts of xylene, and heated to dissolve completely. After repeating the operation of adding methanol again to precipitate several times, the precipitate was washed with methanol and dried and ground.

Fluorine compound (A2):
In a glass reaction vessel, perfluoroalkyl group-containing acrylate CF3 (CF2) nCH2CH2OCOCH = CH2 (n = 5 to 11, n average = 9) 80.0 g, acetoacetoxyethyl methacrylate 20.0 g, dodecyl mercaptan 0 0.8 g, 354.7 g of deoxygenated pure water, 40.0 g of acetone, 1.0 g of C16H33N (CH3) 3Cl and 3.0 g of C8H17C6H4O (CH2CH2O) nH (n = 8) were added, and azobisisobutylamidine dihydrochloride 0. 5 g was added and a copolymerization reaction was carried out at 60 ° C. for 10 hours while stirring under a nitrogen atmosphere to obtain a copolymer emulsion.

-Wax (A3):
An emulsification facility with an internal volume of 1.5 L equipped with a stirrer, thermometer, temperature controller, melting point 105 ° C., acid value 16 mgKOH / g, density 0.93 g / mL, average molecular weight 5000 oxidized polyethylene wax 300 g, ion-exchanged water 650 g 50 g of decaglycerin monooleate surfactant and 10 g of 48% potassium hydroxide aqueous solution were added and replaced with nitrogen, then sealed, stirred at 150 ° C for 1 hour at high speed, cooled to 130 ° C, and passed through a high-pressure homogenizer at 400 atm. And cooled to 40 ° C. to obtain a wax emulsion.

-Thermosetting compound (B):
Crosslinkable resin of alkylol melamine / urea copolymer (Beckamine manufactured by Dainippon Ink and Chemicals: “J101”)

-Binder polymer (C1):
Polyvinyl alcohol binder polymer (C2) having a saponification degree of 88 mol% and a polymerization degree of 500:
Polyester resin Tg = 63 ℃
Acid component: terephthalic acid 50 mol%
Isophthalic acid 48mol%
5-Na sulfoisophthalic acid 2 mol%
Diol component: Ethylene glycol 50 mol%
Neopentyl glycol 50 mol%

(Examples 2 to 4 ) and (Comparative Examples 1 to 6)
In Example 1, a release film was obtained in the same manner as in Example 1 except that the release agent composition was changed to the release agent composition shown in Table 1 below.
Tables 2 and 3 show the properties of the release films obtained in the above Examples and Comparative Examples.
For Examples 1, 3 , and 4 and Comparative Examples 2, 5, and 6, the release layer coating thickness (DRY) is plotted on the horizontal axis and the peel force (F1) is plotted on the vertical axis. Depending on the presence or absence of the binder polymer (C) in the mold layer, it is confirmed that different peel force behavior is exhibited.

The release film of the present invention is characterized in that a release layer having a small dependency of the peeling force on the coating thickness is provided. For example, it is suitable for a production process in which a release layer is formed into a thin film as the film is deformed, for example, for production of a simultaneous molding transfer foil, and has a great industrial value.

Claims (1)

A release layer containing a long-chain alkyl compound (A), a thermosetting compound (B) and a polyester resin (C) containing a 5-Na sulfoisophthalic acid component as an acid component is provided on at least one film surface. A release film, wherein the release film satisfies the following formula (1) at the same time.
F2 / F1 ≦ 2 (1)
(In the above formula, F2 is the release film, the peeling force (mN / cm) between the release layer and the acrylic adhesive tape after 100% stretching, and F1 is the release layer before 100% stretching in the release film. And represents the peel force (mN / cm) between the adhesive tape and the acrylic adhesive tape.)