JP2009220462A - Mold release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold release film which is suitably used in a photo-curing resin layer manufacturing process, and successfully controlled in ultraviolet ray absorbency, visible light transmissibility, and releasability. <P>SOLUTION: The mold release film has a release layer on one side of polyester film, wherein a light transmittance in all wavelength region of the film of 300-380 nm is 20% or less, an average transmittance of light of wavelength of 400-760 nm is 80-99%, and a residual Si-H index of the release layer surface is 2.0 or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a release film having ultraviolet absorptivity and releasability, and is used for manufacturing LCD components such as polarizing plates and retardation plates used in liquid crystal displays (hereinafter abbreviated as LCD), plasma displays. For the production of various display components such as panel (hereinafter abbreviated as PDP) component production, organic electroluminescence (hereinafter abbreviated as organic EL) component production, etc., for example, photocuring formed by ultraviolet irradiation The release film suitable for the manufacturing process which shape | molds a conductive resin layer is provided.

  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. Is used.

  In recent years, with the advancement of IT (Information Technology) field, the required quality of optical members that constitute displays has been steadily improving with higher functionality in display members such as LCDs, PDPs, and organic ELs. Optical members are needed.

  While the need to manufacture optical members with high accuracy is increasing, photocurable resins may be used for manufacturing optical components for reasons such as being able to handle complex surface shapes as patterning becomes finer. (For example, patent document 1).

  In the manufacturing process for forming the photocurable resin layer, a release film may be used. For example, a photocurable resin is applied on a release film and dried, and then a desired pattern is formed by ultraviolet exposure using a stepper, and then the release film is peeled off. In the manufacturing process, at the time of ultraviolet exposure, the ultraviolet rays pass through a portion without a light shielding film of the photomask on which the light shielding pattern is drawn, reach the photocurable resin, and are cured. Further, the remaining ultraviolet light consumed for the curing reaction further reaches the release film. The ultraviolet rays are reflected at the interface between the release surface and the photocurable resin and on the opposite surface of the release film, reach the photocurable resin again, and cure the photocurable resin. This reflected return light is not taken into consideration when creating the pattern of the photomask, and this reflected return light is likely to act at the boundary between the light shielding part and the transmissive part of the pattern. Since it could not be reproduced with high accuracy, a release film is required to have a function of eliminating this harmful reflected return light.

  In addition, in order to perform precise patterning in the manufacturing process, the workpiece is positioned by visual observation or a sensor using visible light. At this time, if the visible light transmittance of the release film is insufficient, the positioning accuracy is deteriorated.

  On the other hand, regarding the release layer constituting the release film, for example, in the release layer in contact with the photocurable resin, when the ultraviolet ray is irradiated from the surface of the release layer, the adhesion between the release layer and the photocurable resin layer In some cases, it was difficult to peel off when releasing the release film. Therefore, there is a need for a release film in which the interaction between the release layer and the photocurable resin layer is as small as possible before and after the release layer surface is irradiated with ultraviolet rays.

  As described above, in the release film, it is necessary to control the ultraviolet absorptivity, visible light transmittance and release property at a higher level than before.

JP 2006-30621 A JP 2007-34026 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that, particularly, in the photocurable resin layer manufacturing process, the ultraviolet absorption property, visible light transmission property and releasability are excellent. It is to provide a controlled release film.

  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 film having a release layer on one side of a polyester film, the light transmittance in the wavelength region of 300 to 380 nm of the film is 20% or less over the entire region, and the light having a wavelength of 400 to 760 nm. The release film is characterized by having an average transmittance of 80 to 99% and a residual Si—H index of 2.0 or less on the surface of the release layer.

Hereinafter, the present invention will be described in more detail.
The polyester film constituting the release film of the present invention may have a single-layer structure or a laminated structure. For example, in addition to the two-layer and three-layer structure, the polyester film is 4 unless the gist of the present invention is exceeded. It may be a multilayer or more layers, 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 as long as it does not impair the gist of the present invention. Specific examples include silica, calcium carbonate, magnesium carbonate, Examples of the particles include barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, 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 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 the present invention, in the polyester film constituting the release film, in addition to the above-mentioned particles, a conventionally known antioxidant, antistatic agent, heat, etc., as long as they do not impair the gist of the present invention. Stabilizers, lubricants, dyes, pigments, UV absorbers and the like can be added.

  The thickness of the polyester film constituting the release film of the present invention is not particularly limited as long as it can be formed as a film, but is usually 9 to 188 μm, preferably 12 to 100 μm, for use. is there.

  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 stretching method, a conventionally known stretching method such as a screw method, a pantograph method, a linear drive method, or the like can be employed.

  Further, a so-called coating stretching method (inline coating: ILC) for treating the film surface during the above-described stretching process of the polyester film can be performed. 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.

  With respect to the release film in the present invention, examples of a method for imparting ultraviolet absorptivity and maintaining visible light transmittance at the same time include a method of containing a dye, a pigment, and the like in a polyester film constituting the release film.

  In the present invention, the dyes contained in the polyester film constituting the release film can be classified into natural dyes and synthetic dyes, and examples of natural dyes include indigo (indigo). Synthetic dyes include azo dyes, anthraquinone dyes, indigoid dyes, sulfur dyes, triphenylmethane dyes, pyrazolone dyes, stilbene dyes, diphenylmethane dyes, xanthene dyes, alizarin dyes, acridine dyes, quinoneimine dyes (for example, azine dyes, oxazine dyes) , Thiazine dyes), thiazole dyes, methine dyes, nitro dyes, nitroso dyes, cyanine dyes and the like. In the present invention, the pigment to be used can be classified into an organic pigment and an inorganic pigment, and as the organic pigment, quinacridone, phthalocyanine-based, dioxazine-based, anthraquinone-based pigments, Watch angle red, dioxazine violet, and the like. Examples of the inorganic pigment include titanium white, zinc white, lead white, carbon black, bengara, vermilion, cadmium red, yellow lead, ultramarine blue, cobalt blue, cobalt purple, zinc chromate and the like.

  These dyes and / or pigments can be used alone or in combination of two or more. The content of these in the polyester film is usually 0.01 to 5% by weight, preferably 0.05 to 2% by weight, and more preferably 0.1 to 1% by weight. When the content is less than 0.01% by weight, the degree of coloring is small, and it may be difficult to obtain the desired ultraviolet absorptivity. On the other hand, if it exceeds 10% by weight, the degree of coloring is saturated, which is not only uneconomical, but also may cause problems such as reduced productivity. In the present invention, it is preferable that the polyester film contains the above-mentioned particles in addition to the dye and / or pigment in a range that does not impair the gist of the present invention in terms of the handleability of the release film.

  In the release film of the present invention, the method for imparting ultraviolet absorptivity is not particularly limited as long as it does not impair the gist of the present invention, and a conventionally known method can be adopted. For example, as described above, a method of containing a dye, a pigment, an ultraviolet absorber and the like in the material constituting the release film is exemplified.

  When the polyester film constituting the release film in the present invention contains an ultraviolet absorber, the ultraviolet absorber is usually 0.15 to 10% by weight, preferably 0.3 to 1.8% by weight, more preferably It is contained in the range of 0.5 to 1.8% by weight, most preferably 0.5 to 1% by weight. If the ultraviolet absorber content is less than 0.1% by weight, the desired ultraviolet absorptivity may not be obtained. On the other hand, when the content exceeds 10% by weight, the ultraviolet absorber bleeds out on the surface of the polyester film, which affects the release layer laminated on the polyester film, and may cause problems such as a decrease in releasability.

  Specific examples of the ultraviolet absorber used in the present invention include benzophenone compounds, 1,3,5-triazine compounds, benzoxazinone compounds, etc., and one or a combination of two or more may be used. However, when the color tone is taken into consideration, a benzoxazinone-based compound that does not easily have a yellowish tint is preferably used for the purpose. Specific examples of the benzoxazine-based compound include 2,2- (1,4-phenylene) bis [4H-3,1-benzoxazin-4-one].

  With respect to the method of imparting ultraviolet absorptivity to the polyester film constituting the release film in the present invention, each of the above methods may be used alone or in combination of two or more.

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 release force (F) between the acrylic pressure-sensitive adhesive tape and the release layer is usually 10 to 10. The range is 300 mN / cm, preferably 10 to 200 mN / cm.

  The release film of the present invention needs to suppress the residual Si-H index to 2.0 or less in order to improve the peelability in the process of forming the photocurable resin layer. The residual Si-H index is preferably 1.5 or less. When the residual Si-H index exceeds 2.0, the peelability is insufficient for the purpose of the present invention.

  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 and stretching method (in-line coating). Applying so-called off-line coating (OLC) 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, Toray Dow Corning Co., Ltd. YSR-3022, TPR-6700, manufactured by Momentive Performance Materials Japan GK TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, U 9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, Toray Dow Corning Co., Ltd. SRX357, SRX211, SD7220, LTC750A, LTC760A, SP7259, BY24-468C, SP2448S, BY24 Is done. By selecting a coating material having few Si—H bonds, the residual Si—H index defined in the present invention can be suppressed low. 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, but in order to control the residual Si-H index defined in the present invention low, the thermal history is set. It takes a lot of time, ie high temperature and long time, to be effective. For example, when a release layer is provided by off-line coating, heat treatment is usually performed at 120 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.

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.} When the coating amount is less than 0.005 g / m ² , the coating property is lacking in stability 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 decrease.

  Moreover, in order to control the residual Si-H index defined in the present invention to be low, after the release layer is formed, it is aged for a long time before it is used to form the photocurable resin layer described below. Is also effective. This is because active Si—H groups are considered to disappear when oxygen or water in the air reacts. For example, the residual Si—H index decreases as compared with immediately after the release layer is formed by aging such as 25 ° C. for 1 week or 40 ° C. for 3 days.

  As described above, the number of remaining Si—H groups decreases with time, and the remaining Si—H index defined in the present invention decreases immediately after the release layer is formed and converges in about one week. Therefore, it is necessary to perform the evaluation using a sample that is regarded as converged and is at least one week after the release layer is formed.

  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 release film of the present invention, the light transmittance in the range of 300 to 380 nm needs to be 20% or less, preferably 10% or less, more preferably 1%, in order to impart ultraviolet absorptivity. Hereinafter, it is most preferably 0.2% or less. When the light transmittance exceeds 20%, a desired pattern accuracy is ensured when a photocurable resin layer is applied on the release surface of the release film, dried, and then subjected to ultraviolet irradiation to form a pattern. It becomes difficult.

Next, formation of the photocurable resin layer in the present invention will be described.
For the photocurable resin layer, unsaturated polyester resin acrylic, addition polymerization, thiol / acrylic hybrid, cationic polymerization, and cationic polymerization and radical polymerization curing components can be used.

  When emphasizing curability, scratch resistance, surface hardness, flexibility and durability, it is preferable to use acrylic materials, which provide antifouling properties, kill resistance, antistatic properties and slipperiness to the surface. In the case of imparting, it is preferable to use a cationic copolymer composed of a cationic monomer unit, a hydrophobic monomer unit and an organopolysiloxane unit as main components.

  The acrylic curing component includes an acrylic oligomer and a reactive diluent as an ultraviolet polymerization component, and additionally contains a photopolymerization initiator, a photosensitizer, and a modifier as necessary. May be.

  Acrylic oligomers include polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, polyethers (meth), including those in which a reactive acryloyl group or methacryloyl group is bonded to an acrylic resin skeleton. ) Acrylate, silicone (meth) acrylate, polybutadiene (meth) acrylate, etc., and those having an acryloyl group or methacryloyl group bonded to a rigid skeleton such as melamine, isocyanuric acid, cyclic phosphazene, etc. It is not limited to these.

  The reactive diluent is a coating agent component having a group that reacts with a polyfunctional or monofunctional acrylic oligomer as well as serving as a solvent in the coating process as a coating medium. It will be. For example, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa ( Examples include (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, (meth) acryloyloxypropyltriethoxysilane, (meth) acryloyloxypropyltrimethoxysilane, and the like. It is done.

  The peelability of the acrylic photo-curable resin layer from the release film is strongly governed by the interaction between the Si-H groups remaining in the silicone resin used in the release layer and the acrylic molecules, resulting in stable quality. It can be easily evaluated with an acrylic pressure-sensitive adhesive tape. An example of such an acrylic adhesive tape is “No. 502” tape manufactured by Nitto Denko.

  In the present invention, examples of the ultraviolet ray generation source include a low-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, and a metal halide lamp. Further, the method of irradiating with ultraviolet rays may be either batch type or continuous type, and is not particularly limited for the purpose of the present invention.

  In the present invention, the thickness of the photocurable resin layer to be molded is not particularly limited in terms of use, but is preferably 5 to 200 μm, more preferably 10 to 100 μm.

  According to the release film of the present invention, as for the photocurable resin layer molding, the light transmittance is particularly small in the wavelength region of 300 to 380 nm, the ultraviolet absorption is good, and the release layer before and after the ultraviolet irradiation, It is possible to provide a release film having as little peeling force variation as possible and good release properties, 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) Particle Primary Particle Size After a sample film piece was fixed and molded with an epoxy resin, it was cut with a microtome, and the cross section of the film was observed with a transmission electron microscope. The maximum diameter (a) of particles observed in the film cross section (a) and the diameter (b) orthogonal thereto are measured, the primary particle diameter of one particle is obtained from the following formula, and 500 particles are measured. The arithmetic average was taken as the primary particle size of the particles.
Primary particle size of one particle = (a + b) / 2

(4) Measurement of light transmittance of release film Using a spectrophotometer UV3100 manufactured by Shimadzu Corporation, the scanning speed is low, the sampling pitch is 2 nm, the wavelength is 300 to 380 nm, the ultraviolet ray region and the 400 to 760 nm visible ray region. The transmittance was measured. As shown below, in the ultraviolet region, the ultraviolet absorptivity was determined by the maximum value in the region, and in the visible light region, the transmittance was determined by the average value of the region.

(5) Evaluation of light transmittance of release film Using the measured value of light transmittance obtained in the item (4), the determination was made according to the following criteria. << Criteria 1: Ultraviolet region >>
A: Maximum light transmittance is less than 0.2% (practical level)
○ +: The maximum value of light transmittance is 0.2% or more and less than 1% (practical level)
○: Maximum value of light transmittance is 1% or more and less than 10% (practical level)
Δ: Maximum value of light transmittance is 10% or more and less than 20% (practical level)
X: The maximum value of light transmittance is 20% or more (practical level)

<< Criteria 2: Visible light region >>
○: The average value of light transmittance is 80% or more (practical level)
X: Average value of light transmittance is less than 80% (practical level)
(6) Evaluation of residual Si-H index of release layer in release film A sample film corresponding to 40 cm ² is prepared in advance. Next, cut out to about 5 mm square and place in a 20 cc vial. Further, 4 cc of a saturated butanol solution of potassium hydroxide is added and sealed with a Teflon (registered trademark) tube. Then, it is allowed to stand for 45 minutes in a constant temperature bath at 50 ° C and 80 ° C, respectively. After cooling to room temperature, the amount of hydrogen gas generated in the vial was quantitatively analyzed by gas chromatography under the following measurement conditions. Using the obtained hydrogen gas generation amount, the residual Si-H index was determined by the following formula, and the determination was made according to the following criteria.

* Gas chromatography measurement conditions <Detector>: TCD
<Carrier>: Nitrogen gas <Temperature setting>: Column: 150 ° C.
Injection: 150 ° C
TCD: 150 ° C
Residual Si-H index = (amount of generated hydrogen gas (80 ° C. treatment)) / (amount of generated hydrogen gas (50 ° C. treatment))
The larger the residual Si-H index, the greater the amount of Si-H groups remaining on the surface of the coating after the release layer coating is formed, so that the adhesion to the photocurable resin layer produced in the present invention is improved. Become.

<Criteria>
○: Residual Si-H index is 1.5 or less, particularly good peelability (practical level)
Δ: Good peelability when residual Si-H index exceeds 1.5 and is 2.0 or less (practical level)
X: Since the residual Si-H index exceeds 2.0, poor peelability (practical level)
In any case, the determination was made based on the measured value of a sample that had passed one week or more after the release agent was applied.

(7) Measurement of release force of release film After attaching one side of a double-sided adhesive tape (Nitto Denko "No. 502") to the release layer surface of an A4 cut-size release film, 50 mm x 300 mm It was cut into a size and the peel strength after standing at room temperature for 1 hour was 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 a tensile speed of 300 mm / min.

(8) Evaluation of peelability of UV curable resin layer An UV curable resin layer having the following composition was applied in advance on a sample film having an A4 cut size so that the coating thickness (after drying) was 5 μm, and then 80 ° C., 1 Heat treated for minutes. Next, ultraviolet irradiation was performed under the following ultraviolet irradiation conditions. After cooling to room temperature, the release film was peeled off from the ultraviolet curable resin layer by hand, and the peelability was evaluated according to the following criteria.

<< UV curable resin composition >>
UV curable resin: KAYANOBA FOP5000 manufactured by Nippon Kayaku
<Ultraviolet irradiation conditions>
Equipment: “UVC-402 type” manufactured by USHIO
Line speed: 5m / min
Line output: 120 w / cm
Irradiation distance: 10cm

<Criteria>
○: Peeling smoothly without catching (practical level)
Δ: Slightly seized but peels off smoothly (practical level)
×: There is a strong sticking point and it does not peel off smoothly (practical level)

(9) Comprehensive evaluation Based on the evaluation result in each item of a sample film, it determined by the following criteria.
<Criteria>
○: When UV absorption is judged as ◎, ○ + or ○, visible light transmittance is judged as ○, and residual Si-H index is judged as ○ (practical level)
Δ: Either UV absorption determination or residual Si-H index determination is Δ, and visible light transmission determination is ○ (practical level)
X: When any of the determination of ultraviolet absorptivity, the determination of visible light transmission, and the determination of the residual Si-H index is x (practical level)

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyethylene terephthalate A)
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 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 as an ethylene glycol slurry were added, and the temperature was 280 ° C. in 100 minutes. The pressure was allowed to reach 15 mmHg, and thereafter the pressure was gradually reduced to finally 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyethylene terephthalate A having an intrinsic viscosity of 0.61.

Production Example 2 (Polyethylene terephthalate B)
The polyethylene terephthalate A produced in Production Example 1 was subjected to a twin screw extruder with a vent, and 2,2- (1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] was used as an ultraviolet absorber. (Cysorb manufactured by CYTECB UV-3638 molecular weight 369 benzoxazine) was supplied to a concentration of 10% by weight, melted and kneaded to form chips, and an ultraviolet absorbent master batch polyethylene terephthalate B was produced. The intrinsic viscosity of the obtained polyethylene terephthalate B was 0.59.

Production Example 3 (Polyethylene terephthalate C)
97.5 parts of polyethylene terephthalate A produced in Production Example 1 and 2.5 parts of titanium oxide particles having an average particle size of 0.35 μm are dry blended and extruded using a twin-screw kneading extruder to obtain polyethylene terephthalate C. It was. The intrinsic viscosity of the obtained polyethylene terephthalate C was 0.61.

Example 1:
A raw material obtained by mixing 90 parts of polyethylene terephthalate A produced in Production Example 1 and 10 parts of polyethylene terephthalate B produced in Production Example 2 was dried in an inert gas atmosphere at 180 ° C. for 4 hours, and 290 ° C. by a melt extruder. Then, it was extruded from a die and cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an unstretched sheet. First, the obtained unstretched sheet was stretched 3.6 times in the MD direction at 95 ° C., and then the reverse gravure was applied so that the following release agent was applied (after drying) to 0.05 g / m ^2. After coating by the coating method, the film was guided to a tenter and subjected to sequential biaxial stretching 4.3 times in the TD direction. Then, it heat-set at 230 degreeC for 3 second, and obtained the 50-micrometer-thick polyester film.

Examples of the release agent composition constituting the release layer are as follows.
<Releasing agent composition>
Curing type silicone resin (Dehesive430: Asahi Kasei Wacker): 50% by weight
Curable silicone resin (Dehesive440: Asahi Kasei Wacker): 50% by weight
The release agent was diluted with water to prepare a coating solution having a concentration of 5% by weight.

Example 2:
A raw material obtained by mixing 90 parts of polyethylene terephthalate A produced in Production Example 1 and 10 parts of polyethylene terephthalate B produced in Production Example 2 was dried in an inert gas atmosphere at 180 ° C. for 4 hours, and 290 ° C. by a melt extruder. Then, it was extruded from a die and cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an unstretched sheet. First, the obtained unstretched sheet was stretched 3.6 times in the MD direction at 95 ° C., then led to a tenter, and sequentially biaxially stretched 4.3 times in the TD direction. Then, it heat-set at 230 degreeC for 3 second, and obtained the 50-micrometer-thick polyester film. Next, a release agent having the following release agent composition was applied off-line by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m 2, and then dried at 120 ° C. for 10 seconds. A release film was obtained later.

Examples of the release agent composition constituting the release layer are as follows.
<Releasing agent composition>
Curing type silicone resin (KS-778: 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 toluene / MEK mixed solvent (mixing ratio = 1: 1) to obtain a coating solution having a solid content concentration of 2% by weight.

Example 3:
In Example 2, a release film was obtained in the same manner as in Example 2 except that the release agent composition was the following release agent composition.
<Releasing agent composition>
Curable silicone resin (KS-3703: manufactured by Shin-Etsu Chemical): 79% by weight
Curable silicone resin (KS-3800: manufactured by Shin-Etsu Chemical): 20% by weight
Curing agent (PL-50T: manufactured by Shin-Etsu Chemical): 1% by weight
The release agent was diluted with a toluene / MEK mixed solvent (mixing ratio = 1: 1) to obtain a coating solution having a solid content concentration of 2% by weight.

Example 4:
In Example 2, a release film was obtained in the same manner as in Example 2 except that the release agent composition was the following release agent composition.
<Releasing agent composition>
Curable silicone resin (KS-3703: manufactured by Shin-Etsu Chemical): 59% by weight
Curable silicone resin (KS-3800: manufactured by Shin-Etsu Chemical): 40% by weight
Curing agent (PL-50T: manufactured by Shin-Etsu Chemical): 1% by weight
The release agent was diluted with a toluene / MEK mixed solvent (mixing ratio = 1: 1) to obtain a coating solution having a solid content concentration of 2% by weight.

Example 5:
Instead of the raw material used in Example 2, the same procedure as in Example 2 was used, except that a raw material obtained by mixing 93 parts of polyethylene terephthalate A manufactured in Production Example 1 and 7 parts of polyethylene terephthalate B produced in Production Example 2 was used. A release film was obtained.

Example 6:
Instead of the raw material used in Example 2, a raw material obtained by mixing 97 parts of polyethylene terephthalate A produced in Production Example 1 and 3 parts of polyethylene terephthalate B produced in Production Example 2 was used. A release film was obtained.

Example 7:
Instead of the raw material used in Example 2, the same procedure as in Example 2 was used except that a raw material obtained by mixing 98 parts of polyethylene terephthalate A produced in Production Example 1 and 2 parts of polyethylene terephthalate B produced in Production Example 2 was used. A release film was obtained.

Comparative Example 1:
A release film was obtained in the same manner as in Example 2 except that 100 parts of polyethylene terephthalate A manufactured in Preparation Example 1 was used instead of the raw material used in Example 2.

Comparative Example 2:
A release film was obtained in the same manner as in Example 2 except that polyethylene terephthalate C produced in Production Example 3 was used instead of the raw material used in Example 2.

Comparative Example 3:
In Example 2, a release film was obtained in the same manner as in Example 2 except that the release agent composition was the following release agent composition.
<Releasing agent composition>
Curable silicone resin (KS-3703: manufactured by Shin-Etsu Chemical): 29% by weight
Curable silicone resin (KS-3800: manufactured by Shin-Etsu Chemical): 70% by weight
Curing agent (PL-50T: manufactured by Shin-Etsu Chemical): 1% by weight
The release agent was diluted with a toluene / MEK mixed solvent (mixing ratio = 1: 1) to obtain a coating solution having a solid content concentration of 2% by weight.

Comparative Example 4:
Instead of the raw material used in Example 2, the same procedure as in Example 2 was used, except that a raw material obtained by mixing 99 parts of polyethylene terephthalate A produced in Production Example 1 and 1 part of polyethylene terephthalate B produced in Production Example 2 was used. A release film was obtained.

  When the release film of the present invention is used for the production of optical members, particularly for photocurable resin layer molding, the ultraviolet absorption and release properties are good, especially LCD backlight, organic EL, inorganic EL, etc. It can utilize suitably for the optical member manufacture for a display.

Claims (1)

It is a film having a release layer on one side of a polyester film, the light transmittance in the wavelength region of 300 to 380 nm of the film is 20% or less over the entire region, and the average transmittance of light having a wavelength of 400 to 760 nm is 80 to 99. %, And the residual Si—H index on the surface of the release layer is 2.0 or less.