JP2010221636A - Polyester release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester release film that has no deterioration of mold releasability caused by coating repellency or coating irregularity, that has a heavy release force, and that is suitable for ceramic sheet formation. <P>SOLUTION: The polyester release film for forming ceramic sheets has a releasing layer on one side of a polyester film and is characterized in that it satisfies expression (1) H≤2×Ra, where H denotes the thickness (g/m<SP>2</SP>) of a releasing layer and Ra denotes an average roughness (μm) of the center line of the polyester film. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a release film, and more particularly to a release film that can be suitably used for forming a green sheet used as a ceramic sheet.

  Conventionally, release films based on polyester films have been used in various ceramic release applications such as ceramic multilayer capacitors and ceramic substrates.

  For example, a ceramic slurry in which ceramic powder is dispersed in a solvent is cast on the release surface of a polyester release film by a doctor blade method, and then dried, and a ceramic green sheet is placed on the polyester release film. Obtainable. A ceramic release sheet can be peeled from the ceramic green sheet, and the resulting ceramic green sheet can be sintered to obtain a ceramic sheet.

  The polyester release film is required to have an appropriate peeling force upon peeling. If the peeling force is too heavy, it becomes difficult to peel off the green sheet in the peeling step, and the green sheet may be broken. Further, as disclosed in Patent Document 1, the green sheet is soft and fragile, and when the green sheet is subjected to processing such as cutting, punching, and printing, the green sheet may be broken or applied, so that the release film Before peeling off, these processes such as cutting, punching, and printing may be performed. However, if the release force for peeling the release film is too light, the green sheet may be separated during such processes as cutting, punching, and printing. Floating from the mold film occurs. Accordingly, an appropriate release force is required for the polyester release film, and the appropriate release force varies depending on the material of the solvent used in the green sheet and slurry and the processing method of the green sheet. Designed.

  In general, the release force of the release layer is determined by the material of the release layer. In order to obtain an appropriate peeling force, it is general to mix a release control agent in the release layer and obtain an appropriate peeling force depending on the amount of the release control agent. However, when the heavy release agent, which is a different component, is increased, in the process of applying the silicone release layer to the polyester film when producing the polyester release film, the application surface due to repelling or uneven application of the silicone coating film, etc. Deterioration of the state may occur. If a polyester release film with coating repellency or coating unevenness is used for forming a green sheet, there arises a problem that a uniform peeling force cannot be obtained. Moreover, when the peeling force becomes heavy, the adhesiveness between the release layer and the polyester film is deteriorated.

Japanese Patent Laid-Open No. 11-43376 JP 2004-351626 A JP 2006-181993 A

  This invention is made | formed in view of the said situation, The solution subject is providing the release polyester film for ceramic sheet formation which made the peeling force heavy, without generate | occur | producing an application repelling and application | coating unevenness. is there.

  As a result of intensive studies in view of the above-described actual situation, the present inventor has found that the above problems can be easily solved by a film having a specific configuration, and has completed the present invention.

  That is, the gist of the present invention resides in a polyester release film for forming a ceramic sheet, which is a film having a release layer on one surface of a polyester film and satisfies the following formula (1).

H ≦ 2 × Ra (1)
(In the above formula, H is the thickness (g / m ² ) of the release layer, and Ra means the center line average roughness (μm) of the polyester film)

Hereinafter, the present invention will be described in more detail.
The raw material polyester used in the polyester film of the present invention may be a homopolyester or a copolyester.

  When using 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 polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like.

  On the other hand, when a copolymer polyester is used, it is preferably a copolymer containing 30 mol% or less of the third component. Examples of the dicarboxylic acid component of the copolyester include one or two of isophthalic acid, terephthalic acid phthalate, 2,6-naphthalenedicarboxylic acid, adipic acid sebacic acid, and oxycarboxylic acid (for example, P-oxybenzoic acid). Examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like.

  In any case, the polyester referred to in the present invention is usually 80 mol% or more, preferably 90 mol% or more of polyethylene terephthalate which is an ethylene terephthalate unit, or polyethylene-2,6-naphthalate which is an ethylene-2,6-naphthalate unit. Refers to a polyester that is the like.

  It is preferable to mix | blend particle | grains in the polyester film in this invention with the main objective of providing slipperiness.

  The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, 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.
The average particle size of the particles used is preferably in the range of 0.1 to 5 μm, more preferably in the range of 0.5 to 5 μm. If the average particle size is less than 0.1 μm, the particles tend to aggregate and the dispersibility tends to be insufficient. On the other hand, if it exceeds 5 μm, the surface roughness of the film becomes too rough, Problems may occur when a release layer is provided in a subsequent process.

  Furthermore, the particle content in the polyester is preferably in the range of 0.01% by weight or more. When the particle content is less than 0.01% by weight, the slipperiness of the film may be insufficient.

  The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, the particles can be added at any stage for producing the polyester, but preferably, the polycondensation reaction may proceed 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.
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, 9-250 micrometers, Preferably it is the range of 12-188 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.

  That is, 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 130-170 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 unstretched sheet can be simultaneously biaxially stretched so that the area magnification is 10 to 40 times. Furthermore, it may be stretched again in the longitudinal and / or transverse direction before or after performing the heat treatment, if necessary.

  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. Although it is not limited to the following, for example, in the sequential biaxial stretching, in particular, the first-stage stretching is completed, and the coating treatment can be performed before the second-stage stretching. When a coating layer is provided on a polyester film by the above-described 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, which is suitable as a polyester film. A film can be manufactured.

  In the release film of the present invention, the relationship between the center line flatness roughness (Ra) of the polyester film surface on which the release layer is provided and the thickness of the release layer (H: value represented by solid content) is expressed by the following formula (1 ) Must be satisfied. If the following conditions are not satisfied, the peeling force cannot be increased without application defects.

H ≦ 2 × Ra (1)
(In the above formula, H is the thickness (g / m ² ) of the release layer, and Ra means the center line average roughness (μm) of the polyester film)

  Further, in the polyester film constituting the release film in the present invention, as a method of forming a film surface having a centerline maximum roughness Ra, a particle kneading method, a particle coating method, an embossing method, a sandblasting method, an etching method, A method such as an electric discharge machining method can be used. In the present invention, any of the methods described above may be adopted, and there is no particular limitation.

  Next, a typical method for forming a film surface will be specifically described, but the present invention is not limited to the following production examples.

  In the process of kneading the polyester film, inorganic fine particles such as titanium oxide, calcium carbonate, silica, and kaolin are added in the course of manufacturing the polyester film, or the precipitated fine particles of the catalyst residue are left in the polyester. This is a method for roughening the film surface.

  The embossing method is a method of roughening the film surface by embossing at a predetermined temperature using an apparatus composed of an embossing roll and a backup roll having a desired uneven shape.

  The particle coating method is a method in which a roughened surface is formed on a film by applying a coating solution having an appropriate viscosity prepared from particles, a binder, and a solvent to the film surface. Examples of the particles include inorganic particles such as silica, alumina, calcium carbonate, and titanium oxide, and organic particles such as silicone resin, fluorine resin, and benzoguanamine resin. Examples of the binder include polyester resins, acrylic resins, polyvinyl butyral resins, polyurethane resins, phenoxy resins, epoxy resins, polyvinyl chloride resins, and compounds containing radical polymerizable double bonds. Examples of the coating apparatus include a gravure coater, a reverse coater, and a wire bar coater. In addition, an antifoamer, a coating property improving agent, a thickener, a particle dispersion stabilizing resin, and the like can be added to the coating solution as necessary.

  The release layer constituting the release film of the present invention is not particularly limited as long as it contains a material having releasability. Among such materials, it is preferable to use a curable silicone resin because release properties are particularly improved.

  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 ray curable type, an electron beam curable type, and a solventless type can be used.

  Specific examples of the curable silicone resin include KS-772, KS-774, KS-775, KS-778, KS-779H, KS-856, X-62-2422, X- manufactured by Shin-Etsu Chemical Co., Ltd. 62-2461, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210, FSQK-2560, FSXK-2560 manufactured by Dow Corning Asia Co., Ltd. YSR-3022, TPR-6700 manufactured by Toshiba Silicone Co., Ltd. , TPR-6720, TPR-6721, SD7220, SD7226, SD7229 manufactured by Toray Dow Corning Co., Ltd., and the like.

Further, a release control agent may be used in combination in order to adjust the peelability of the release layer.
The coating amount (Si) of the release layer constituting the release film of the present invention is 0.01 to 5 (g / m 2), further 0.01 to 2 (g / m 2), particularly 0.01 to 1. A range of (g / m2) is preferred. If the coating amount of the release layer is less than 0.01 (g / m 2), the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, when the coating amount exceeds 5 (g / m ² ), the coating film adhesion and curability of the release layer itself may decrease.

In the present invention, conventionally known coating methods such as reverse roll coating, gravure coating and bar coating can be used as a method for providing a release layer on the polyester film.
With respect to the release film in the present invention, a coating layer such as an adhesive layer or an antistatic layer may be provided on the surface where no release layer is provided, and the polyester film may be subjected to a surface treatment such as corona treatment or plasma treatment. May be applied.

  Furthermore, the polyester film may be provided with a coating layer such as an adhesive layer or an antistatic layer in advance by the above-described coating stretching method (inline coating method).

  If the release film of this invention is used for the release polyester film for ceramic sheet formation, the industrial value is very 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 a sample was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) was added and 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 maximum height (Ra) of polyester film Portion of reference length (2.5 mm) extracted from cross-sectional curve obtained by surface roughness measuring machine (SE3500) manufactured by Kosaka Laboratory Ltd. ( From the roughness curve (hereinafter referred to as “extracted part”), the center line of this extracted part is taken as the X axis, the direction of the vertical magnification as the Y axis, and the roughness curve is expressed as y = f (x). The value of Ra given was expressed in micrometer units (μm). The radius of the stylus used at this time was 2.0 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

(4) Evaluation of peel strength (F) of release film One side of a double-sided pressure-sensitive adhesive tape (Nitto Denko “No. 502”) was attached to the release layer of the measurement sample, cut into a size of 50 mm × 300 mm, and room temperature The peel force after standing 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 the condition of a tensile speed of 300 mm / min. The measurement was performed at 20 ± 2 ° C. and 65 ± 5% RH.

(5) Measurement of release layer coating amount (H) Using a fluorescent X-ray measurement apparatus (model “XRF-1500”, manufactured by Shimadzu Corporation), the FP (Fundamental Parameter Method) method allows the following measurement conditions: The amount of silicon element on the surface of the release film provided with the release layer and the surface without the release layer was measured, and the difference was taken as the amount of silicon element in the release layer. Next, the coating amount (H) (g / m ² ) as a unit of —SiO (CH ₃ ) ₂ was calculated using the obtained amount of silicon element.
"Measurement condition"
Spectral crystal: PET (pentaerythritol)
2θ: 108.88 °
Tube current: 95 mA
Tube voltage: 40 kv
In the case where no silicon element is present in the release layer, the coating amount is measured by a technique such as cross-sectional observation.

The manufacturing method of the raw material polyester used in the following examples and comparative examples is as follows.
<Manufacture of polyester>
Production Example 1 (Polyethylene terephthalate A1)
86 parts of terephthalic acid and 70 parts of ethylene glycol were placed in a reactor and subjected to a transesterification reaction at about 250 ° C. for 4 hours. Add 0.03 part of antimony trioxide and 0.01 part of phosphoric acid and 3 parts of silicon dioxide particles with an average particle size of 3.2 μm, gradually increase the temperature from 250 ° C. to 285 ° C. and gradually reduce the pressure to 0 0.5 mmHg. After 4 hours, the polymerization reaction was stopped to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.65.

Production Example 2 (Polyethylene terephthalate A2)
In Production Example 1, production was carried out in the same manner as in Production Example 1 except that 3 parts of silicon dioxide particles having an average particle diameter of 4.3 μm were added instead of adding 3 parts of silicon dioxide particles having an average particle diameter of 3.5 μm. Polyethylene terephthalate A2 having a viscosity of 0.65 was obtained.
<Manufacture of polyester film>

Production Example 3 (PET film F1)
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. The obtained sheet was stretched 3.5 times in the longitudinal direction at 85 ° C. Next, the film was guided to a tenter and stretched in the transverse direction by a factor of 3.7 at 100 ° C., followed by heat setting at 230 ° C. to obtain a PET film F1 (Ra = 0.03 μm) having a thickness of 50 μm.

Production Example 4 (PET film F2)
A PET film F2 having a thickness of 50 μm (Ra = 0.13 μm) was obtained in the same manner as in Production Example 3 except that polyethylene terephthalate A2 produced in Production Example 2 was used instead of polyethylene terephthalate A1 produced in Production Example 1. .

Example 1:
A release layer having the following release agent composition was provided on the polyester film F1 obtained in Production Example 3 so that the coating amount was 0.01 g / m ² (after drying) to obtain a release film.
<Releasing agent composition>
・ Curable silicone resin (manufactured by Shin-Etsu Chemical: KS-847H) 100 parts ・ Catalyst (manufactured by Shin-Etsu Chemical: PL-50T) 1 part ・ Toluene / MEK mixed solvent (mixing ratio is 1: 1) 1950 parts

Example 2:
A release layer having the following release agent composition was provided on the polyester film F1 obtained in Production Example 4 so that the coating amount was 0.01 g / m ² (after drying) to obtain a release film.
<Releasing agent composition>
• 100 parts of curable silicone resin (manufactured by Shin-Etsu Chemical: KS-723A) • 15 parts of curable silicone resin (manufactured by Shin-Etsu Chemical: KS-723B) • 5 parts of catalyst (manufactured by Shin-Etsu Chemical: PS-3) • Mixed toluene / MEK Solvent (mixing ratio is 1: 1) 7200 parts

Comparative Example 1:
In Example 1, it manufactured similarly to Example 1 except having used the polyester film F2 instead of the polyester film F1, and obtained the release film.

Comparative Example 2:
In Example 2, it manufactured like Example 1 except having changed the composition of the mold release agent as follows, and obtained the release film.
<Releasing agent composition>
・ Curable silicone resin (Shin-Etsu Chemical: KS-723A) 100 parts ・ Curable silicone resin (Shin-Etsu Chemical: KS-723B) 15 parts ・ Catalyst (Shin-Etsu Chemical: PS-3) 5 parts ・ Toluene / MEK mixed Solvent (mixing ratio is 1: 1) 3300 parts Table 1 shows the characteristics of the films obtained in the above Examples and Comparative Examples.

  The film of the present invention can be suitably used as a release film for forming a ceramic sheet, for example.

Claims (1)

A polyester release film for forming a ceramic sheet, which is a film having a release layer on one surface of a polyester film and satisfies the following formula (1).
H ≦ 2 × Ra (1)
(In the above formula, H is the thickness (g / m ² ) of the release layer, and Ra means the center line average roughness (μm) of the polyester film)