JP2005335261A - Mold releasing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold releasing film suitable for applications in which the existence of foreign matter caused by an oligomer on the surface of a film is extremely prohibited, including a substrate film constituting a mold releasing film for protecting an adhesive layer used when a liquid crystal constituting member such as a liquid crystal polarizing plate or a phase difference plate is produced and a substrate film for various optical applications used when a display member such as LCD, PDP, or an organic EL is produced. <P>SOLUTION: In the mold releasing film, a coating layer and a mold releasing layer are formed in turn on one side of a polyester film oriented in at least uniaxial direction. An organic compound (A) having a metal element and a binder polymer (B) are incorporated in the coating layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 sometimes abbreviated as LCD), In addition to manufacturing various display components such as plasma display panel (hereinafter may be abbreviated as PDP) component manufacturing, organic electroluminescence (hereinafter also abbreviated as organic EL) component manufacturing, etc. The present invention provides a release film suitable for optical applications and the like.

  Conventionally, a release film based on a polyester film has been used for various optical components such as a liquid crystal polarizing plate, a retardation plate component, a PDP component, an organic EL component, and various display components. Used for applications. 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 that not only the mold release property is excellent, but also the foreign matter on the film surface is as small as possible. That is, since it is also an application that places importance on so-called visibility, especially when transmitting light, even a foreign matter on the film surface, which is not a problem at all in a normal film application, becomes a serious problem.

  For example, when the manufacturing process of a liquid crystal polarizing plate is given as an example, the manufacturing process includes a process in which a release film and a polarizing plate are bonded to each other via a pressure-sensitive adhesive layer and wound into a roll, and the oligomer is adhesive. It is thought that it precipitates through the drying process after agent coating. 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 the display performance, hue, contrast, and contamination of liquid crystal polarizing plates, measures to prevent the outflow of defective products are taken by visual observation or using a magnifier, but crystallized oligomers adhere. When the released release film is used, it is determined that the product is defective due to the inclusion of foreign matter, and there is a problem in that the product yield is reduced.

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 as small as possible, for example, for producing liquid crystal components such as liquid crystal polarizing plates and retardation plates, for producing PDP components, organic The present invention provides a release film suitable for various optical applications and the like as well as for various display structural members and the like for the production of EL structural members.

  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 a release film in which a coating layer and a release layer are sequentially provided on one side of a polyester film stretched in at least a uniaxial direction, and an organic compound having a metal element in the coating layer ( A release film comprising A) and a binder polymer (B).

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 structure or a two-layer structure as long as it does not exceed the gist of the present invention other than the two-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, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, P-oxybenzoic acid, etc.), etc. 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 which is polyethylene terephthalate or the like in which 60 mol% or more, preferably 80 mol% or more 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, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

  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 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 under 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 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. .

  This invention makes it an essential requirement to contain the organic compound (A) containing a metal element and a binder polymer (B) in a coating layer.

  The organic compound (A) containing a metal element used in the present invention is an organic compound containing a metal element such as aluminum, titanium, zirconium, etc., and an organic compound containing an aluminum element is particularly preferable.

Specific examples of the organic compound having an aluminum element include aluminum alcoholates such as (CH ₃ O) ₃ Al and (C ₂ H ₅ O) ₃ Al, aluminum salts such as stearic acid, octylic acid and benzoic acid, aluminum tris ( Acetylacetonate), aluminum monoacetylacetonate bis (ethylacetoacetate), aluminum-di-n-butoxide-monoethylacetoacetate, aluminum-di-iso-propoxide-monomethylacetoacetate, aluminum organic acid chelate, etc. The aluminum chelate is exemplified. Among these, it is preferable to contain an aluminum chelate in the coating layer in that the oligomer precipitation preventing property is particularly good. Specific examples are also described in the “Crosslinking agent handbook” (Yamashita Shinzo, Kaneko East Assistant Editor, Taiseisha, 1990 edition).

  Specific examples of the organic compound having titanium element include 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 propylate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate and the like.
One kind of the organic compound (A) may be used, or two or more kinds may be appropriately mixed and used.

  Furthermore, in the laminated polyester film in the present invention, it is necessary to use a binder polymer (B) in combination in order to further improve the oligomer precipitation preventing property after heat treatment (180 ° C., 10 minutes). The “binder polymer (B)” used in the present invention is a number average measured by gel permeation chromatography (GPC) according to a polymer compound safety evaluation flow scheme (sponsored by the Chemical Substances Council in November 1985). It is defined as a polymer compound having a molecular weight (Mn) of 1000 or more and having a film-forming property.

  Specific examples of the binder polymer (B) include polyvinyl alcohol, polyacrylamide, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches, polyurethane, polyacrylate, chlorinated polymers (polyvinyl chloride and vinyl chloride vinyl acetate) Polymer, etc.). Among the above-mentioned binder polymers (B), it is preferable to contain polyvinyl alcohol in the coating layer because the oligomer precipitation preventing performance is further improved.

  The content of polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) contained in the coating layer is not particularly limited, but is preferably in the range of 10% by weight or more. If the PVA content is less than 10% by weight, the oligomer precipitation preventing effect may be insufficient. Further, the degree of polymerization of PVA is not particularly limited, but usually 100 or more, preferably 300 to 40,000 is suitably used for applications.

  On the other hand, the saponification degree of PVA is not particularly limited, but 70 mol% or more, preferably 80 mol% or more and 99.9 mol% or less is suitably used. As a specific example, saponified vinyl acetate is used. Etc. In order to further improve the oligomer precipitation preventing property with respect to the content (% by weight) of the organic compound (A) and the binder polymer (B) having a metal element in the coating layer constituting the release film in the present invention, It is preferable to satisfy the expressions (1) and (2) at the same time.

10 ≦ W (A) ≦ 95 (1)
20 ≦ W (B) ≦ 80 (2)
(In the above formula, W (A) and W (B) are the content (% by weight) of the organic compound (A) containing a metal element in the coating layer constituting the laminated polyester film, and the content of the binder polymer (B). (Represents (% by weight))

  More preferably, W (A) is in the range of 20 to 80% by weight and W (B) is in the range of 30 to 70% by weight. When either of the organic compound (A) and the binder polymer (B) is out of the above range, the oligomer precipitation amount from the coating layer surface after the heat treatment may increase.

  In the coating layer, a crosslinking agent (C) may be used in combination as long as the gist of the present invention is not impaired. Specific examples include methylolated or alkylolated urea, melamine, guanamine, and acrylamide. System, polyamide compound, epoxy compound, aziridine compound, block polyisocyanate, silane coupling agent, titanium coupling agent, zirco-aluminate coupling agent and the like. These crosslinking components may be previously bonded to the binder polymer.

  Further, inorganic particles (D) 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 case of the coating stretching method (in-line coating), a coating solution in which the above-mentioned series of compounds is used as an aqueous solution or water dispersion and the solid content concentration is adjusted to about 0.1 wt% to 50 wt% as a guide is applied onto the polyester film. It is preferable to produce a laminated polyester film in the manner of application.

  In addition, a small amount of an organic solvent may be contained in the coating solution for the purpose of improving the dispersibility in water, improving the film forming property, and the like within a range not exceeding the gist of the present invention. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

The coating amount of the polyester film on the provided is a coating layer constituting the release film of the present invention (after drying) is generally 0.005~1g / ^{m 2,} preferably in the range of 0.005 to 0.5 / ^{m 2} is there. 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. 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 coating layer on the polyester film are not particularly limited. For example, when the coating layer is provided by a coating stretching method (in-line coating), it is usually 170 to 280 ° C. The heat treatment may be performed for 3 to 40 seconds, preferably 200 to 280 ° C. for 3 to 40 seconds. On the other hand, when the coating layer is provided by off-line coating, heat treatment is usually performed at 80 to 200 ° C. for 3 to 40 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

  Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed irrespective of the coating extending | stretching method (in-line coating) or offline coating.

Next, formation of the release layer in the present invention will be described.
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, KM765, KM766, KM768, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210 manufactured by Dow Corning Asia Co., Ltd. YSR-3022, TPR manufactured by GE Toshiba Silicone Co., Ltd. -6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300 UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, SM3200, SM3030, Toray Dow Corning Silicone SRX357, SRX211, SD7220, LTC750A, LTC760A, SP7259, SP7259, SP7259, SP7259 BY24-452, SP7268S, SP7265S, LTC1000M, LTC1050L, SYLOFF7900, SYLOFF7198, SYLOFF22A, etc. 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. For example, when the release layer is provided by a coating stretching method (inline 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. On the other hand, when providing a release layer by off-line coating, heat treatment is usually performed at 80 to 200 ° C. for 3 to 40 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed irrespective of the coating extending | stretching method (in-line coating) or offline coating. In addition, a conventionally well-known apparatus and 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.

After heat treatment (180 ° C., 10 minutes) of the release film of the present invention, the amount of oligomer (OL) extracted from the release layer surface with dimethylformamide is usually 1.5 mg / m ² or less, preferably 1 0.0 mg / m ² or less. When OL exceeds 1.5 mg / m ² , for example, when the liquid crystal component is manufactured, when used for pressure-sensitive adhesive layer protection, the transparency of the pressure-sensitive adhesive decreases or the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer decreases. May cause problems such as

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

  Further, the total light transmittance (TL) of the release film in the present invention is 80% or more, especially for applications that require transparency, such as for optical applications in which visibility is particularly important, for manufacturing display members. Preferable in terms of possible, more preferably 85% or more. When the TL is less than 80%, the transparency is insufficient, and for example, in the inspection process accompanied by optical evaluation, there may be a problem that it is easy to overlook the mixing of foreign matters.

  The residual adhesion rate of the release film in the present invention is preferably 80% or more in order to suppress the migration or transfer of the release component to the surface of the opposite base material to be bonded or the transfer roll surface in the production process. Preferably it is 90% or more. When the residual adhesion rate is less than 80%, the release component is transferred to the roll surface of the transport roll in the manufacturing process, or the adhesive force of the pressure-sensitive adhesive layer in contact with the release surface is reduced, for example, in an adhesive application. May cause problems such as

  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 oligomer amount (OL) extracted from release layer surface of release film Pre-heated laminated polyester film is heated in air at 180 ° C. for 10 minutes. 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 an oligomer (cyclic trimer) collected in advance and dissolving it in accurately measured DMF. 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

(4) Measurement of total light transmittance (TL) of release film Total light transmission of release film using an integrating sphere turbidimeter “NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS-K-7105. The rate (%) was measured.

(5) Evaluation of Residual Adhesion Rate of Release Film / Residual Adhesive Strength Nitto Denko (manufactured) No. The 31B adhesive tape is subjected to one reciprocating pressure bonding with a 2 kg rubber roller, and heat-treated at 100 ° C. for 1 hour. Next, the sample film was peeled off from the pressure-bonded sample. The adhesive strength of the 31B pressure-sensitive adhesive tape is measured according to the method of JIS-C-2107 (adhesive strength to stainless steel plate, 180 ° peeling method). This is the residual adhesive strength.
-Basic adhesive force Using the same tape (No. 31B) as in the case of residual adhesive force, an adhesive tape is pressure-bonded to a stainless steel plate according to JIS-C-2107, and measurement is performed in the same manner. The value at this time is defined as the basic adhesive strength. Using these measured values, the residual adhesion rate is determined based on the following equation.
Residual adhesion rate (%) = (residual adhesive force / basic adhesive force) × 100
The measurement is performed at 20 ± 2 ° C. and 65 ± 5% RH.

(6) Evaluation of release film peel force (F) After applying one side of a double-sided adhesive tape (Nitto Denko “No. 502”) to the surface of the release layer of the sample film, cut into a size of 50 mm × 300 mm After that, the peel strength after standing for 1 hour at room temperature is measured. 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.

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.

Production Example 2 (Polyethylene terephthalate A2)
Polyethylene terephthalate A2 in the same manner as in Production Example 1 except that 0.01 parts of silica particles having an average particle diameter of 1.5 μm were added in place of 0.01 parts of silica particles having an average particle diameter of 1.5 μm in Production Example 1. Got.

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 unstretched sheet thus obtained was stretched 3.6 times in the MD direction at 95 ° C., and the following coating agent was applied by the reverse gravure coating method, then led to a tenter and 4.3 times in the TD direction. Sequential biaxial stretching was performed. Thereafter, it was heat-set at 230 ° C. for 3 seconds to obtain a PET film having a thickness of 38 μm provided with a coating layer having a coating amount (after drying) of 0.04 g / m ² .

Examples of compounds constituting the coating layer are as follows.
(Compound example)
-Organic compound having an aluminum element: (A1)
Aluminum organic acid chelate AL-135 (Matsumoto Pharmaceutical Co., Ltd.)
Organic compound having aluminum element: (A2)
Aluminum chelate D (manufactured by Kawaken Fine Chemical Co., Ltd.)
・ PVA resin: (B1)
Polyvinyl alcohol / acrylic resin having saponification degree = 88 mol% and polymerization degree = 500: (B2)
Jurimar AT-M-918 (Nippon Pure Chemicals Co., Ltd.)
・ Crosslinking agent (C)
γ-Glycidoxypropyltrimethoxysilane particles: (D)
Silica sol with an average particle size of 65 nm

<< Coating composition >>
Organic compound having aluminum element (A1): 50% by weight
Organic compound containing aluminum element (A2): 0% by weight
PVA resin (B1): 25% by weight
Acrylic resin (B2): 0% by weight
Cross-linking agent (C): 20% by weight
Particle (D): 5% by weight
The concentration of the coating solution was 4% by weight.

Next, a release agent having the following release agent composition was applied on the PET film coating layer by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m ^2, and the coating was performed at 120 ° C., 30 A release film was obtained after heat treatment for 2 seconds.

<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.

(Example 2 to Example 4)
In Example 1, 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 1 below.

(Example 5)
A release film was obtained in the same manner as in Example 1 except that polyethylene terephthalate A1 was changed to polyethylene terephthalate A2 in Example 1.

(Example 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 following release agent composition.

<Releasing agent composition>
Curable silicone resin (KS-772: manufactured by Shin-Etsu Chemical): 98% by weight
Silicone oil (KF-353: Shin-Etsu Chemical): 1% by weight
Curing agent (PL-3: 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.

(Comparative Examples 1 to 6)
In Example 1, it manufactured like Example 1 except having changed the coating composition into the coating composition shown in the following table 1, and obtained the release film.
Table 1 shows the properties of the release films obtained in the above Examples and Comparative Examples.

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

Claims (1)

A release film in which a coating layer and a release layer are sequentially provided on one side of a polyester film stretched at least in a uniaxial direction, and the organic compound (A) and binder polymer (B) having a metal element in the coating layer A release film comprising: