JP2009214347A - Mold release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold release polyester film which suppresses silicone desorption and can approprioately be used in applications needing a stable peel strength in optical applications, for example, for producing display members such as LCD, PDP, and organic EL. <P>SOLUTION: The mold release polyester film is composed in which the treated surface of a corona-treated polyester film is coated with a contained addition reaction type silicone resin satisfying formula (1): 3<SiH/SiVi<8 (wherein, SiH is the mole number of a hydrogen atom bonded to a silicon atom contained in the addition reaction type silicone resin, and SiVi is the mole number of vinyl group bonded to the silicon atom contained in the addition reaction type silicone). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a release film in which an addition reaction type silicone release layer is provided on at least one surface of a polyester film. More specifically, the adhesion of the silicone release layer and the polyester film is improved to suppress the release of silicone. An object of the present invention is to provide a release film having a stable peeling force.

  Examples of the release film having a polyester film as a base material include those having a structure in which a silicone release layer is formed on at least one surface of a polyester film surface. Such a release film is produced by applying a film-forming silicone resin imparting releasability to the film surface, and curing these using means such as heating. However, it is usually difficult to firmly adhere and bond the silicone resin to the polyester film substrate. The reason is that the silicone resin has a low surface tension and the silicone resin and the polyester resin are incompatible. For this reason, it is difficult to obtain a release film in which the silicone release layer and the polyester film are firmly adhered.

  In order to overcome this drawback, a method has been proposed in which an epoxy group-containing organosiloxane is added to a silicone resin to improve adhesion to a resin substrate (Patent Document 1). However, this method is not effective in a trace amount that does not change the peeling characteristics, and even if an appropriate amount of an epoxy group-containing organosiloxane is added, the effect is limited. Therefore, as a means for solving this, it has been proposed to provide an undercoat layer having high adhesion to both the polyester film and the silicone resin on the surface of the polyester film before applying the silicone resin to the polyester film. An organosilicon compound has been proposed as the coating layer (Patent Document 2).

These methods are premised on two coatings (coating of the undercoat layer and the silicone release layer). The undercoat layer is applied between the silicone release layer and the polyester film and dried, and then the release silicone composition is applied and dried. Furthermore, it is suitable to apply the silicone release layer continuously after forming the undercoat layer, instead of winding it once after forming the undercoat layer and forming a new silicone release layer again. However, these methods are disadvantageous in terms of cost and versatility from the viewpoint of an increase in material cost, an increase in the number of processing steps, and a limitation of the apparatus that can be processed only by an apparatus capable of continuous coating. In addition, the increase in processing steps is also disadvantageous from the viewpoint of foreign matter contamination. Therefore, it is necessary to improve the adhesion between the silicone release layer and the polyester film without increasing the material cost and increasing the number of processing steps.
Japanese Patent Publication No. 2-53466 JP 2006-110945 A Japanese Patent No. 3540340

  The present invention has been made in view of the above circumstances, and the problem to be solved is to improve the adhesion between the silicone release layer and the polyester film to suppress the detachment of the silicone and to have a stable release force. To provide a film.

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

  That is, the gist of the present invention is that a release polyester film is obtained by coating a treated addition surface of a polyester film subjected to corona treatment with a contained addition reaction type silicone resin satisfying the following formula (1). Exist.

3 <SiH / SiVi <8 (1)
(SiH in the above formula (1) is the number of moles of hydrogen atoms bonded to silicon atoms contained in the addition reaction type silicone resin, and SiVi was bonded to silicon atoms contained in the addition reaction type silicone resin. (Mole number of vinyl group)

Hereinafter, the present invention will be described in more detail.
In the present invention, the polyester used for the polyester film 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 polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like.

  On the other hand, in the case of a copolymerized polyester, a copolymer containing 30 mol% or less of the third component is preferable. 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 having ethylene terephthalate units and polyethylene-2,6-naphthalate having ethylene-2,6-naphthalate units. Refers to a polyester that is the like.

  In the polyester layer in the present invention, it is preferable to blend particles for the main purpose of imparting slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and magnesium phosphate. , Particles of kaolin, aluminum oxide, titanium oxide and the like. 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 3 μm. When the average particle size is less than 0.1 μm, the particles tend to aggregate and dispersibility becomes insufficient. On the other hand, when the average particle size exceeds 5 μm, the surface roughness of the film becomes too rough and is separated in the subsequent process. Problems arise when a mold layer is provided. Furthermore, the particle content in the polyester preferably satisfies 0.01 to 5% by weight, more preferably 0.01 to 3% by weight.

  When the particle content is less than 0.01% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the smoothness of the film surface is insufficient. It may become.

  The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of producing the polyester, but preferably a method of proceeding the polycondensation reaction by adding particles after the esterification stage or after the transesterification reaction is adopted. 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 method of blending dried particles and a polyester raw material using a kneading extruder Etc.

  Although the thickness of the polyester film which comprises the release film of this invention is not necessarily limited, Usually, 9-188 micrometers, Preferably the range of 9-100 micrometers is good.

  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 using an extruder to cool and solidify with a cooling roll using a molten sheet extruded from a die 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.

  Next, the film is stretched in a direction orthogonal to the first-stage stretching direction. The stretching temperature is usually 130 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 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. It is also possible to perform simultaneous biaxial stretching. As the simultaneous biaxial stretching method, the unstretched sheet is stretched simultaneously in the machine direction (or machine direction) and transverse direction (or width direction) at a temperature of usually 70 to 120 ° C., preferably 80 to 110 ° C. The stretching ratio is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. 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.

  As for the simultaneous biaxial stretching apparatus using the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, a linear drive method, or the like can be adopted. The “screw method” is a method in which a clip is placed in the groove of the screw to increase the clip interval. The “pantograph method” is a method of expanding the clip interval using a pantograph. The “linear motor system” has an advantage that the clip interval can be arbitrarily adjusted by applying the linear motor principle and controlling the clips individually.

  Further, simultaneous biaxial stretching may be performed in two or more stages. In that case, stretching may be performed in one tenter or a plurality of tenters may be used in combination. 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. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. 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.

  In addition, a so-called coating stretching method (in-line coating) for treating the film surface during the above-described stretching process of the polyester film can be performed.

  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.

  Regarding the structure of the release film of the present invention, it is necessary to perform corona treatment before applying the silicone release layer on at least one surface of the polyester film. Corona treatment is a technology that modifies the surface of a substrate by irradiating corona discharge generated by applying high-frequency and high-voltage output supplied by a high-frequency power source to the treatment substrate between the discharge electrode and the treatment roll. It is. The corona treatment may be performed on the film surface during the stretching process of the polyester film, or after the stretching, only the corona treatment may be performed, or may be performed before the coating process in the release layer forming process. . The surface modification of the polyester film by corona treatment is preferably a surface wetness index of 47 to 65 dyn / cm, more preferably 50 to 62 dyn / cm.

  As a result of intensive studies on the release layer constituting the release film in the present invention, adhesion is improved by applying an addition reaction type silicone resin satisfying the following formula (1) to the corona-treated polyester film surface. I understood that.

3 <SiH / SiVi <8 (1)
SiH in the above formula (1) is the number of moles of hydrogen atoms bonded to silicon atoms contained in the addition reaction type silicone resin, and SiVi is vinyl bonded to silicon atoms contained in the addition reaction type silicone resin. The number of moles of the group.

Specific examples of the addition reaction type silicone resin include X-62-5508 and X-62-5039 manufactured by Shin-Etsu Chemical Co., Ltd. The coating amount (Si) (after drying) of the release layer constituting the release film in the present invention is usually 0.01 to ² g / m ² , preferably 0.01 to 1 g / m ² , and more preferably 0.00. A range of 01 to 0.5 g / m ² is preferred. If the coating amount (Si) (after drying) is less than 0.01 g / m ² , the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, when the coating amount (Si) exceeds ² g / m ² , the coating film adhesion and curability of the coating layer 2 itself may decrease.

  About the release layer which comprises the release film in this invention, you may add the silane coupling agent of a formula (I) to addition reaction type | mold silicone resin.

R ¹ is an organic group containing an epoxy group such as γ-glycidoxypropyl group, 3,4-epoxycyclohexylethyl group, and R ² , R ³ , R ⁴ and R ⁵ are each independently Alkyl groups such as methyl, ethyl, propyl, and butyl groups, monovalent hydrocarbon groups such as aryl groups such as phenyl and tolyl groups, alkoxy groups such as methoxy and ethoxy groups, and the following formula (II) It is the group shown.

R ⁶ , R ⁷ and R ⁸ are each independently the same epoxy group-containing organic group as the R ¹ group described above, the same monovalent hydrocarbon group as R ^{2 to} R ⁵ , or an alkoxy group, but at least one of them Is an alkoxy group. Specific examples of the organosiloxane include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl). Examples thereof include monomers such as ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and 5,6-epoxyhexyltriethoxysilane, and hydrolyzable organisms of these monomers. .

  This organosiloxane can be obtained by hydrolyzing an organosilane obtained by a hydrosilylation reaction between an epoxy group-containing olefin and an organosilane containing a hydrogen atom bonded to a silicon atom. It is optional to use a silane that does not contain an epoxy group that can be cohydrolyzed with an amount within 10 mol%. Moreover, n of Formula (I) is an integer of 0-10. n = 0 represents a monomer.

  Moreover, the addition amount of organosilane has the preferable range of 0.05-10 weight part with respect to 100 weight part of addition reaction type silicone resins. If it is 0.1 parts by weight or less, the adhesion to the corona-treated surface is poor, and if it is 10 parts by weight or more, the release performance may be affected.

  In the present invention, conventionally known coating methods such as reverse gravure coating, bar coating, and die coating can be used as a method for providing a silicone 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 silicone release layer on the polyester film are not particularly limited. When the release layer is provided by off-line coating, usually at 120 to 200 ° C. for 3 to 40 seconds. The heat treatment is preferably performed at 100 to 180 ° C. for 3 to 40 seconds as a guide. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed.

  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 silicone release layer is not provided, as long as the gist of the present invention is not impaired. .

  ADVANTAGE OF THE INVENTION According to this invention, the release | release film which suppresses detachment | leave of silicone and has the stable peeling force can be provided, The 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 surface wetting index According to JIS-K6768-1977, using a wetting reagent (manufactured by Wako Pure Chemical Industries, Ltd.), before providing a silicone release layer, the reagent is allowed to flow on the coated surface of the polyester film and wettability Was measured.

(4) Viscosity measurement of diluted toluene solution of silicone According to JIS-Z-8803, curable silicone resin to be applied in Examples and Comparative Examples is 30 wt. %, The kinematic viscosity of the toluene solution was measured, and the viscosity was determined from the result.

(5) Chemical structure evaluation of addition reaction type silicone resin A 0.5 wt% diluted toluene solution of addition reaction type silicone resin used in Examples and Comparative Examples was prepared, and FT-NMR LA400 (manufactured by JEOL Ltd.)
The SiH / SiVi ratio SiH / SiVi was evaluated.

(6) Evaluation of coating film adhesion promotion of release film (practical property substitution evaluation)
Immediately after the processing of the sample film, the sample film was taken out after being left in a constant temperature and humidity chamber at 25 ° C. and 50% RH for one month. Immediately thereafter, the release surface of the sample film was rubbed 10 times with a tentacle, and the degree of removal of the release layer was determined according to the following criteria.
<Criteria>
○: No dropout of the coating film (practical level)
Δ: The coating film turns white but does not fall off (practical level)
×: Detachment of the coating film was confirmed (practically difficult level)

(7) Measurement of release force increase rate (ΔF) of release film before and after solvent treatment In advance, using RUBING TESTER (manufactured by Ohira Riko Kogyo Co., Ltd.), BEMCOT F-1 (manufactured by Ozu Sangyo) was applied to a 7 cm × 5 cm square plate surface. Attach and impregnate BEMCOT with 4 ml of methyl ethyl ketone, apply a load of 500 g to the square plate (surface pressure: 14.3 gf / cm ² ), and apply the surface of the release layer of the sample film to BEMCOT F-1 at a rate of 200 mm / s. And 100 reciprocating wipes. Next, after affixing one side of a double-sided adhesive tape (Nitto Denko “No. 502”) to the surface of the release layer of the sample film, it was cut into a size of 50 mm × 300 mm and left for 1 hour at room temperature. Measure. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under a tensile speed of 300 mm / min. (F1) The peel force (F2) was measured in the same manner except that no further solvent treatment was performed. Using the obtained peel force values, the rate of change (ΔF) in peel force before and after solvent treatment was determined, and the solvent peel resistance was determined according to the following criteria.
ΔF (%) = (peeling force after solvent treatment−peeling force before solvent treatment) × 100 / peeling force before solvent treatment

<Criteria>
○: ΔF is less than 50% (practical level)
Δ: ΔF is 50% or more and less than 100% (a level at which practical use may be difficult)>
X: ΔF is 100% or more (practical level)

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyethylene terephthalate A1)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 part of 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 reached to 15 mmHg, and thereafter the pressure was gradually reduced to finally 0.3 mmHg. After 4 hours, the system was returned to atmospheric pressure to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.61.

Example 1:
The polyethylene terephthalate A1 produced in Production Example 1 is dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded into a sheet form from the die, and the surface using an electrostatic application adhesion method. It cooled and solidified on the cooling roll which set temperature to 40 degreeC, and the unstretched sheet was obtained. First, the obtained unstretched sheet was stretched 3.6 times in the MD direction at 95 ° C., led to a tenter, and sequentially biaxially stretched 4.3 times in the TD direction. Thereafter, it was heat-fixed at 230 ° C. for 3 seconds to obtain a PET film having a thickness of 38 μm. Next, the PET film is subjected to corona treatment at 20 W / min / m ² , and a coating amount (after drying) of a release agent having the following release agent composition is 0.11 g / m ² on the corona-treated surface. A release film was obtained after coating and heat-treating at 150 ° C. for 15 seconds.

<Releasing agent composition>
・ Silicone resin (X-62-5508: manufactured by Shin-Etsu Chemical Co., Ltd.): 20 parts by weight ・ Curing agent (PL-5000: manufactured by Shin-Etsu Chemical Co., Ltd.): 2 parts by weight 1: 1) A coating solution was prepared by diluting with 350 parts by weight.

Example 2 and Comparative Examples 1-4:
In Example 1, the coating agent composition was produced in the same manner as in Example 1 except that the release agent compositions shown in Tables 1 and 2 below and the presence or absence of corona treatment shown in Table 2 were changed to obtain a release film. .
Table 2 shows the properties of the release films obtained in the above Examples and Comparative Examples.

Abbreviations in Table 1 are as follows.
X-62-5508: addition reaction type silicone resin (SiH / SiVi = 4)
KS-847H: addition reaction type silicone resin (SiH / SiVi = 3)
X-62-5427: addition reaction type silicone resin (SiH / SiVi = 9)
PL-5000: Curing agent, PL-50T: Curing agent, X-92-185: Epoxy group-containing organosiloxane

  The release film of the present invention can be suitably used for optical applications such as LCDs, PDPs, organic ELs, and the like for manufacturing display members, and for applications that require a stable peeling force.

Claims (1)

A release polyester film obtained by coating a treated addition surface of a polyester film subjected to corona treatment with a contained addition reaction type silicone resin that satisfies the following formula (1).
3 <SiH / SiVi <8 (1)
(SiH in the above formula (1) is the number of moles of hydrogen atoms bonded to silicon atoms contained in the addition reaction type silicone resin, and SiVi was bonded to silicon atoms contained in the addition reaction type silicone resin. (Mole number of vinyl group)