JP2008260178A - Mold release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold release film suitable for a use extremely disliking that the foreign matter caused by an oligomer is present on the surface of a film such as a base material film or the like which constitutes a pressure-sensitive adhesive protecting mold release film used when a liquid crystal constituent member such as a liquid crystal polarization plate, a phase difference plate etc. is manufactured, a base material film or the like for various optical uses when a display member such as LCD, PDP, organic EL, etc. is manufactured. <P>SOLUTION: The mold release film is characterized in that a mold release layer is provided on the coating layer of at least a uniaxially stretched polyester film having the coating layer formed by coating a polyester film with a coating solution, which contains an organic compound containing at least a kind of a metal element selected from aluminum, titanium and zirconium, an organosilicon compound and a catalyst, and heat-treating the layer comprising the coating solution at 120°C or above. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a release film having as little oligomer precipitation as possible, for example, for producing LCD components such as polarizing plates and retardation plates used in liquid crystal displays (hereinafter abbreviated as LCD), plasma display panels. A mold release film suitable for various display uses, such as for manufacturing various display components, such as for manufacturing components (hereinafter abbreviated as PDP), for manufacturing organic electroluminescence (hereinafter abbreviated as organic EL) components. Is to provide.

  Conventionally, release films based on polyester films have been used in various optical applications such as LCD polarizing plates, retardation plates, PDP components, organic EL components, and various display components. It is used for etc. A problem in using the release film is that oligomers deposited on the surface of the release layer at high temperatures cause various problems in the production process.

  In recent years, with the advancement of the IT (Information Technology) field, various defects associated with the precipitation of oligomers have become apparent along with the improvement of the quality of release films used when manufacturing display members such as LCDs, PDPs, and organic ELs.

  In order to cope with the various uses described above, it is desired not only to have excellent mold releasability, but also to minimize foreign matter on the film surface. In other words, since it is also an application that places importance on so-called visibility, especially through light transmission, even a foreign matter on the film surface that is not a problem at all in a normal film application becomes a serious problem.

  For example, when the manufacturing process of a polarizing plate for LCD is given as an example, the manufacturing process includes a process in which a release film and a polarizing plate are bonded together via an adhesive layer and wound into a roll. Is considered to precipitate through a drying process after application of the adhesive. The oligomer deposited on the surface of the release layer is obtained when the LCD is manufactured by transferring the polarizing plate with the pressure-sensitive adhesive layer to which the oligomer is adhered to the glass substrate, by transferring to the surface of the opposite pressure-sensitive adhesive layer. In some cases, the brightness of the LCD is reduced.

  In recent years, there is a tendency to increase the brightness of the display screen for the purpose of improving the visibility of the LCD, and the above-mentioned problems have become serious problems.

  On the other hand, with the aim of reducing the manufacturing cost accompanying productivity improvement, there is a tendency to set the drying temperature higher in the drying process, especially with the speeding up of the manufacturing process, and the above-mentioned oligomer is more likely to precipitate. It has become.

  In the inspection process that involves optical evaluation such as display capability, hue, contrast, and foreign matter contamination of LCD polarizing plates, measures to prevent the outflow of defective products by visual or magnifying glass are taken. When the attached release film is used, it is judged as a defective product due to foreign matter mixing, and has a problem that a defect such as a decrease in product yield occurs.

Japanese Patent Laid-Open No. 6-16941 JP-A-7-3215 JP 2000-44904 A JP 2000-238441 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that the amount of oligomer precipitation is extremely small, for example, for producing liquid crystal components such as polarizing plates for LCDs and retardation plates, for producing PDP components, The present invention provides a release film suitable for various optical applications and the like, as well as a method for producing the same, as well as various display structural members such as an organic EL structural member.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above problem can be easily solved by a release film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is to apply a coating solution containing an organic compound, an organic silicon compound, or a catalyst containing one or more metal elements selected from aluminum, titanium, and zirconium, and heat-treat at 120 ° C. or higher. The release film is characterized by having a release layer on the applied layer of the polyester film stretched at least in a uniaxial direction.

Hereinafter, the present invention will be described in more detail.
The polyester film constituting the release film in the present invention may have a single-layer structure or a laminated structure. For example, the polyester film may have a four-layer or a three-layer structure as long as the gist of the present invention is not exceeded other than the two-layer or three-layer structure. It may be a multilayer having more than that, and 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 type of particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples thereof include, for example, 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 resin, thermosetting phenol resin, thermosetting epoxy resin, benzoguanamine resin, and the like. Furthermore, during the polyester production process, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed. On the other hand, the shape of the particles to be used is not particularly limited. Either a rod shape or a flat shape 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 for producing the polyester constituting each layer, but the polycondensation reaction may proceed preferably 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 1st step | paragraph extending | stretching direction is 70-170 degreeC normally, and a draw ratio is 3.0-7 times normally, Preferably it is 3.5-6 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 coating layer which comprises the release film in this invention is demonstrated. Regarding the coating layer, the above-described coating stretching method (in-line coating) may be used, so-called off-line coating that is applied outside the system on a once produced film may be employed, and any method may be employed. .

  In the present invention, it is an essential requirement that the coating layer contains an organic compound containing one or more metal elements selected from aluminum, titanium, and zirconium. Only one kind of these metal organic compounds may be used, or two or more kinds may be appropriately mixed and used.

  Specific examples of the organic compound having an aluminum element include aluminum tris (acetylacetonate), aluminum monoacetylacetonate bis (ethylacetoacetate), aluminum di-n-butoxide monoethylacetoacetate, aluminum di -Iso-propoxide monomethyl acetoacetate and the like are exemplified.

  Specific examples of the organic compound having a titanium element include, for example, titanium orthoesters such as tetranormal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate; titanium acetylacetonate, Examples thereof include titanium chelates such as titanium tetraacetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolamate, and titanium ethylacetoacetate.

  Specific examples of the organic compound having a zirconium element include, for example, zirconium acetate, zirconium normal propyrate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate and the like.

  Among them, it is preferable to use an organic compound containing one or more metal elements selected from aluminum, titanium, and zirconium, more preferably a chelate structure, particularly in that the oligomer precipitation preventing performance is good. Organic compounds are preferred. It is also described in detail in the “Crosslinking agent handbook” (Yamashita Shinzo, Kaneko East Assistant Editor, Taiseisha, 1990 edition).

In order for the coating layer constituting the release film in the present invention to have good oligomer precipitation prevention properties and good coating film adhesion between the release layer and the polyester film, it is essential to use an organic silicon compound in combination. As the organic silicon compound, a compound represented by the following general formula (1) is preferable.
Si (X) _d (Y) _e (R ¹ ) _f (1)
(In the above formula, X is an organic group having at least one selected from an epoxy group, a mercapto group, a (meth) acryloyl group, an alkenyl group, a haloalkyl group and an amino group, R ¹ is a monovalent hydrocarbon group, and 1 to 10 carbon atoms, Y is a hydrolyzable group, d is an integer of 1 or 2, e is an integer of 2 or 3, f is an integer of 0 or 1, and d + e + f = 4 )

The organosilicon compound represented by the general formula (1) has two hydrolyzable groups Y (D unit source) or three (T unit) capable of forming a siloxane bond by hydrolysis / condensation reaction. Source) can be used. In the general formula (1), R ¹ is particularly preferably a methyl group, an ethyl group, or a propyl group. As the hydrolyzable group Y, conventionally known ones can be used, and the following can be exemplified. Methoxy group, ethoxy group, butoxy group, isopropenoxy group, acetoxy group, butanoxime group, amino group and the like. These hydrolyzable groups may be used alone or in combination. The application of a methoxy group or an ethoxy group is particularly preferable because it can impart good storage stability to the coating material and has suitable hydrolyzability.

  In the present invention, as the organosilicon compound contained in the coating layer, conventionally known compounds can be used, specifically, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycid. Xylpropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ -Aminopropyltriethoxysilane, 5-hexenyltrimethoxysilane, p-styryltrimethoxysilane, trifluoropropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiisopropenoxysilane Etc. It is possible.

In the present invention, it is an essential requirement to use a catalyst in combination with the coating layer constituting the release film for the purpose of promoting hydrolysis and condensation reaction. Specific examples of the catalyst include organic acids such as acetic acid, butyric acid, maleic acid and citric acid, inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, basic compounds such as triethylamine, tetrabutyl titanate, dibutyltin dilaurate, Organometallic salts such as dibutyltin diacetate, dibutyltin dioctate, dibutyltin diolate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dibutyltin benzylmalate, KF, NH ₄ Fluorine element-containing compounds such as F can be mentioned. The said catalyst may be used individually or may use 2 or more types together. Among these, organometallic salts are particularly preferable from the viewpoint of good coating film durability, and more preferably a tin catalyst is used from the viewpoint of long-lasting catalytic activity.

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

  Moreover, an antifoamer, a coating property improving agent, a thickener, an organic lubricant, organic polymer particles, an antioxidant, a UV absorber foaming agent, a dye, and the like may be contained as necessary.

  In the range not exceeding the gist of the present invention, only one type of organic solvent may be used for the purpose of improving dispersibility, improving film forming property, etc., and two or more types may be used as appropriate.

The coating amount of the coating layer provided on the polyester film constituting the release film of the present invention (after drying) is generally 0.005~1g / ^{m 2,} the range preferably from 0.005 to 0.5 / ^{m 2} It is. When the coating amount is less than 0.005 g / m ² , the uniformity of coating thickness may be insufficient, and the amount of oligomer deposited from the coating layer surface after heat treatment may increase. On the other hand, when the coating is applied in excess of 1 g / m ² , problems such as a decrease in slipperiness may occur.

  In the present invention, as a method for providing the coating layer, a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating or the like can be used. As for the coating method, there is a description example in “Coating method” published by Yoji Harasaki in 1979.

  In the present invention, regarding the curing conditions for forming the coating layer on the polyester film, it is necessary to perform heat treatment at 120 ° C. or higher, preferably 120 to 200 ° C. for 3 to 40 seconds, more preferably 120 to 160 ° C. Heat treatment is performed for 3 to 40 seconds as a guide. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. When the heat treatment is not performed at 120 ° C. or higher, the amount of oligomers deposited is increased, or the coating layer is insufficiently cured, resulting in a large fluctuation in the peeling force of the release layer.

  Next, formation of the release layer in the present invention will be described.

  The release layer constituting the release film in the present invention refers to a layer having releasability. Specifically, the peel force (F) between the acrylic adhesive tape and the release layer is 5 to 500 mN / It is preferable for use of the present invention to be cm.

  The release layer constituting the release film in the present invention may be provided on the polyester film in the film production process such as the above-described coating stretching method (inline coating), and is applied outside the system on the once produced film. So-called off-line coating may be employed, and any method may be employed. 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.

  Moreover, it is preferable that the release layer which comprises the release film in this invention contains a curable silicone resin in order to make mold release property favorable. A type having a curable silicone resin as a main component may be used, or a modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, or an alkyd resin may be used.

  As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X manufactured by Shin-Etsu Chemical Co., Ltd. -62-1387, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62 -7213, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210 manufactured by Dow Corning Asia Co., Ltd. YSR-3022, TPR-6700, TPR-6720 manufactured by GE Toshiba Silicone Co., Ltd. , TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775 XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, manufactured by Dow Corning Toray Co., Ltd. SRX357, SRX211, SD7220, LTC750A, LTC760A, SP7259, BY24-468C, SP7248S, etc. BY24-452 are exemplified. Further, a release control agent may be used in combination to adjust the release property of the release layer.

  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, and when providing the release layer by off-line coating, usually at 120 to 200 ° C. for 3 to 40 seconds, The heat treatment is preferably performed at 100 to 180 ° C. for 3 to 40 seconds as a guide. 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 an energy source can be used as an energy source for hardening by active energy ray irradiation.

The coating amount of the release layer from the viewpoint of coating property, usually 0.005~1g / ^{m 2,} preferably in the range from 0.005 to 0.5 / ^{m 2.} If the coating amount is less than 0.005 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, when the coating is thicker than 1 g / m ² , the coating layer adhesion and curability of the release layer itself may be lowered.

  Regarding the release film in the present invention, a coating layer such as an adhesive layer, an antistatic layer and an oligomer precipitation preventing layer may be provided on the surface where 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.

  In the present invention, when a release layer is provided on the coating layer, the film may be temporarily wound after the coating layer is provided, and the release layer may be provided again. After the coating layer is provided, the release layer is continuously provided. A mold layer may be provided on the coating layer, and any method may be adopted.

After the release film of the present invention is heat-treated (180 ° C., 10 minutes), the amount of oligomer (OL) extracted from the release layer surface with dimethylformamide needs to be 2.0 mg / m ² or less, preferably Is 1.0 mg / m ² or less, more preferably 0.5 mg / m ² or less. When the OL exceeds 2.0 mg / m ² , for example, when the liquid crystal component is manufactured, the adhesive layer is used for protecting the adhesive layer, the transparency of the adhesive is lowered, the adhesive strength of the adhesive layer is reduced, or optical evaluation is performed. There may be problems such as causing trouble in the accompanying inspection process.

  In the release film of the present invention, the amount of metal element contained in the coating layer is preferably 0.5 kcps or more, preferably 1.0 kcps or more in order that OL satisfies the above range. When the amount of the metal element is less than 0.5 kcps, the desired oligomer sealing performance may not be obtained.

  In the present invention, “oligomer” is defined as a cyclic trimer of low molecular weight substances that crystallize and precipitate on the film surface after heat treatment.

  According to the release film of the present invention, it is possible to provide a release film with as little oligomer precipitation as possible, and its industrial value is high.

  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) Measurement of peel force increase rate (ΔF) of release film before and after solvent treatment A sample film was immersed in a toluene solvent for 10 minutes in advance and then naturally dried.
Next, after attaching one side of a double-sided adhesive tape (“No. 502” manufactured by Nitto Denko) to the surface of the release layer of the sample film, it was cut into a size of 50 mm × 300 mm and left for 1 hour at room temperature. 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 a tensile speed of 300 mm / min. (F1)
Further, the peeling force (F2) was measured in the same manner except that the solvent treatment was not performed.
Using the obtained peel force values, the rate of change in peel force (ΔF (%)) before and after the solvent treatment was determined, and then judged according to the following criteria.
ΔF = (peeling force after solvent treatment−peeling force before solvent treatment) / peeling force before solvent treatment × 100
<Criteria>
○: ΔF is less than 20% (practical level)
Δ: ΔF is 20% or more and less than 50% (a level at which practical use may be difficult)>
X: ΔF is 50% or more (practical level)

(4) Measurement of amount of oligomer (OL) extracted from release layer surface of release film An unheat-treated release film is heated in air at 180 ° C. for 10 minutes in advance. After that, the heat-treated film is brought into close contact with the inner surface of a box having a top and width of 10 cm and a height of 3 cm, and the box shape is obtained. When the coating layer is provided, the coating layer surface is set to the inside. Next, 4 ml of DMF (dimethylformamide) is placed in the box prepared by the above method and left for 3 minutes, and then DMF is recovered. The recovered DMF was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of oligomer in DMF, and this value was divided by the film area in contact with DMF to obtain the amount of film surface oligomer (mg / M ² ).

  The amount of oligomer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by accurately weighing the oligomer (cyclic trimer) collected in advance and dissolving it in DMF accurately measured. The concentration of the standard sample is preferably in the range of 0.001 to 0.01 mg / ml. The conditions for the liquid chromatograph were as follows.

Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(5) Measurement of amount of metal element from release surface side of release film Preliminary X-ray fluorescence measurement device (Shimadzu Corp. model “XRF-1500” from the surface of the sample sample provided with the release layer. The amount of metal element was measured by the FP (Fundamental Parameter Method) method under the following measurement conditions.

(6) Critical fracture load (CDL) evaluation of release surface in release film The release surface of the sample film was measured 12 times using an ultra-thin scratch tester (CSR-02 type) manufactured by Reska. Thereafter, the critical average breaking load (CDL) was determined by taking the remaining 10 measured average values excluding the maximum and minimum values.
"Measurement condition"
Sensor: No. 1
Load (9 / mm): 238.75
Stylus diameter (μm): 15
Excitation level (μm): 80
Load Rate (mN / mm): Automatic calculation
Gain = 1000
Stage Angle (deg): 12.00
Stage Speed (μm / s): 10.0

(7) Coating film adhesion promotion evaluation of release film (practical property substitution evaluation)
The sample film was left in a constant temperature and humidity chamber at 60 ° C. and 70% RH for 48 hours, and then the sample film was taken out. Thereafter, the release surface of the sample film was rubbed with a tentacle five times, and the degree of release of the release layer was determined according to the following criteria.
<Criteria>
○: No dropout of the coating film (practical level)
Δ: The coating film turns white but does not fall off (practical level)
×: Detachment of the coating film was confirmed (practically difficult level)

(8) Optical defect detection evaluation using adhesive layer (practical property substitution evaluation)
An adhesive layer having the following adhesive composition was provided on the release surface of the sample film so that the thickness (after drying) was 20 μm. Adhesive layer sample obtained by adhering this to a glass plate and removing the release film is placed on the stage of a polarizing microscope, and set so that the two polarizers sandwiching the sample are in crossed Nicols, and so on. Optical anomalous defects were observed. Optical defects are 0.5 in size
Only those having a size of μm or more were counted, and the number was converted to the area of the adhesive layer, and then judged according to the following criteria.
<Criteria>
○: Less than 0.5 optical defects / m ² (practical level)
Δ: Optical defects of 0.5 / m ² or more and less than 1.0 / m ² (level at which practical use may be difficult)
X: Optical defects of 1.0 / m ² or more (practical level)

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 0.05 g / m ^2, and then heat-treated at 130 ° C. for 10 seconds. Examples of compounds constituting the coating layer are as follows.

(Compound example)
-Organic compound having an aluminum element: (A1)
Aluminum tris (acetylacetonate)
・ Organic compound containing titanium element: (A2)
Organic compound containing titanium tetraacetylacetonate / zirconium element: (A3)
Zirconium tetraacetylacetonate / organosilicon compound: (B1)
γ-glycidoxypropyltrimethoxysilane / organosilicon compound: (B2)
γ-glycidoxypropyltriethoxysilane catalyst (C1): dibutyltin dilaurate catalyst (C2): dibutyltin diacetate particle (D): silica sol (average particle size 60 nm)

<< Coating composition >>
Organic compound having aluminum element (A1): 19.5% by weight
Organosilicon compound (B1): 80% by weight
Catalyst (C1): 0.5% by weight
The coating agent was diluted with a toluene / MEK mixed solvent (mixing ratio was 1: 1) to obtain 4% by weight.

Thereafter, a release agent having the following release agent composition was applied on the coating layer by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m ² and heat-treated at 120 ° C. for 30 seconds. A release film was obtained later.
<Releasing agent composition>
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical): 99% by weight
Curing agent (PL-50T: manufactured by Shin-Etsu Chemical): 1% by weight
The release agent was diluted with a MEK / toluene mixed solvent (mixing ratio was 1: 1) to prepare a coating solution having a concentration of 2% by weight.

Examples 2-8, Comparative Examples 1-4:
A release film was obtained in the same manner as in Example 1 except that the coating composition was changed to the coating composition shown in Table 2 below.

  The properties of each release film obtained in the above examples and comparative examples are shown in Table 3 below.

  The release film of the present invention is suitably used for, for example, LCDs, PDPs, organic ELs, and other optical applications for manufacturing display members, and applications that extremely dislike the presence of oligomer-derived foreign matter on the film surface. be able to.

Claims (1)

A coating layer formed by applying a coating solution containing an organic compound, an organic silicon compound, or a catalyst containing one or more metal elements selected from aluminum, titanium, and zirconium, and heat-treating the coating at 120 ° C. or higher. A release film having a release layer on the coating layer of the polyester film stretched at least in a uniaxial direction.