KR20140106691A - Mold release film - Google Patents

Abstract

When the film is stretched at the time of molding by a mold, a release film having no thickness unevenness due to uneven elongation is provided. Wherein the difference between the stress in the longitudinal direction and the stress in the transverse direction of the film is 1.80 MPa or less and the stress is measured by the method according to ASTM D1708-02a at an ambient temperature of 120 Deg.] C, and a tensile speed of 100 mm / min.

Description

MOLD RELEASE FILM

The present invention relates to a release film.

In the mold releasing film for molding, in the molding process of a resin using a mold forming apparatus, in order to demold the resin (sealing material) from the mold after molding, the mold is inserted between the mold and the resin, .

However, when a general-purpose PET film or a high heat-resistant polyimide film is used as the release film, since the elongation of the film is small, the ability to follow the mold becomes insufficient and wrinkles easily occur in the film. Further, the wrinkles of the resulting film are transferred to the molded resin, resulting in roughness on the surface of the product, and the yield is lowered.

There has been proposed a release film for resin mold molding comprising a thermoplastic tetrafluoroethylene copolymer for the purpose of improving productivity and yield (see Patent Document 1). Further, there is proposed a release film for semiconductor chip encapsulation, which is a laminated film in which a film containing a fluororesin is laminated on at least one surface of a base film comprising a stretched polyester resin film (see Patent Document 2) .

There has also been proposed a release laminated film having a layer containing a modified polyolefin resin and a layer containing an adhesive fluororesin laminated on at least one side of the layer, interposed between a press plate of the press machine and the print substrate Patent Document 3). This release film is a release film for laminated press molding in which a thermosetting adhesive at the time of lamination molding of a wiring board is pressed at a high temperature and a high pressure to form a laminate without displacement. Therefore, in order to make the press pressure uniform, It is necessary to have cushioning property, and the film thickness is about 0.1 mm.

It is also possible to provide a release film having excellent gas permeability and excellent trackability and strength to the shape of the mold and having three layers of a fluorine-containing polymer layer, a fluorine-free polymer layer, and a fluorine-containing polymer layer, , And a fluorine-containing polymer has a specific adhesive functional group (see Patent Document 4).

Japanese Patent Laid-Open No. 2001-310336 Japanese Patent Application Laid-Open No. 2006-49850 International Publication No. 2005/115751 brochure Japanese Patent Application Laid-Open No. 2009-285990

However, such a conventional release film has improved followability to the shape of the mold, but when the film is stretched at the time of molding, the film stretches unevenly, causing unevenness in thickness. As a result, unevenness in the thickness of the film is transferred to the molded article, which causes roughness on the surface, resulting in a problem that the molded article having a desired surface shape can not be obtained and the yield is lowered.

In view of the above situation, the present invention aims to provide a release film which does not cause thickness unevenness due to uneven elongation when stretched during molding by a mold.

The present invention relates to a release film comprising a fluorine-containing resin, wherein the difference between the stress in the longitudinal direction and the stress in the transverse direction of the film is 1.80 MPa or less and the stress is measured by a method according to ASTM D1708-02a , At a temperature of 120 占 폚 and a tensile rate of 100 mm / min.

It is preferable that the releasing film has a stretch ratio in the longitudinal direction and the transverse direction of the film of 0.50% or less.

Wherein the fluorine-containing resin is at least one selected from the group consisting of a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and an ethylene-tetrafluoroethylene copolymer It is desirable to be species.

The fluorine-containing resin is preferably an ethylene-tetrafluoroethylene copolymer.

The release film preferably has a tetrafluoroethylene unit content of 50 mol% or more with respect to all the monomer units constituting the ethylene-tetrafluoroethylene copolymer.

The release film is preferably used for molding the light emitting diode sealing material.

The inventors of the present invention have been able to prevent the occurrence of thickness unevenness due to uneven stretching of the film during molding with a mold when the difference in stress between the longitudinal direction and the width direction is not more than a predetermined value in the release film, , And that a molded article having a desired surface shape can be obtained, thereby completing the present invention.

Since the release film of the present invention is uniformly stretched when the resin is molded by a mold and thickness irregularity hardly occurs, a molded article of a resin having a desired surface shape without roughness can be suitably obtained .

Fig. 1 is a view showing a method of specifying stress values from a stress-strain curve. Fig.

The present invention relates to a release film comprising a fluorine-containing resin, wherein the difference between the stress in the longitudinal direction and the stress in the transverse direction of the film is 1.80 MPa or less and the stress is measured by a method according to ASTM D1708-02a Is a value obtained under conditions of an ambient temperature of 120 DEG C and a tensile rate of 100 mm / min.

For this reason, the release film of the present invention is uniformly stretched when stretched in the molding by the mold, so that the thickness irregularity does not occur.

In the release film of the present invention, the difference between the stress in the longitudinal direction (also referred to as "MD") and the stress in the transverse direction (also referred to as "TD") is 1.80 MPa or less.

If the difference in the stress exceeds 1.80 MPa, thickness unevenness may occur at the time of drawing by molding with a mold or the like.

The difference in the stress is preferably 1.20 MPa or less, more preferably 0.85 MPa or less, still more preferably 0.70 MPa or less, and most preferably 0.5 MPa or less because the surface of the molded article obtained by molding at a high temperature hardly becomes rough More preferably 0.30 MPa or less, and most preferably 0.10 MPa or less.

The stress in the longitudinal direction and the stress in the width direction are values obtained by measurement under the conditions of an atmospheric temperature of 120 DEG C and a tensile speed of 100 mm / min by a method in accordance with ASTM D1708-02a. More specifically, as shown in Fig. 1, a stress-strain curve (SS curve) is created by the above-described method, and the strain (distortion) of the Y (B) of the axial stress. The difference in stress is a subtraction of the difference of these values.

The stress in the longitudinal direction and the stress in the width direction are preferably 7.3 MPa or less, more preferably 6.0 MPa or less, and more preferably 3.0 MPa, from the viewpoint of compliance with the mold at the time of evacuation.

The release film of the present invention is also excellent in the stress-strain curve in the longitudinal direction and in the width direction described above because the roughness does not occur on the surface of the molded article even when the release film is stretched by using a mold of a more complicated shape , The difference between the value of the stress in the Y axis when the strain (elongation) of the X axis in the longitudinal direction is 120% and the value of the stress in the Y axis when the strain in the width direction (elongation) is 120% is 1.80 MPa or less.

In the above stress-strain curve in the longitudinal direction and the width direction, the value of the stress in the Y-axis when the distortion (elongation) of the X-axis in the longitudinal direction is 180% and the value of the stress in the X- ) ≪ / RTI > 180% of the stress in the Y-axis is 1.80 MPa or less.

In the release film of the present invention, the stretching ratio of the film in the longitudinal direction (MD) and the transverse direction (TD) is preferably 0.50% or less, more preferably 0.30% or less. If the expansion / contraction ratio exceeds 0.50%, roughness may occur on the surface of the molded article.

It is more preferable that the expansion / contraction ratio is 0.50 to -1.60%.

The expansion / contraction ratio is a value obtained by the method according to JIS K 7133 (115 ° C × 10 minutes).

The release film of the present invention comprises a fluorine-containing resin.

The fluorine-containing resin is a polymer (homopolymer or copolymer) having a repeating unit derived from at least one fluorine-containing ethylenic monomer, and is a polymer having melt processability.

The fluorine-containing ethylenic monomer is an olefinically unsaturated monomer having at least one fluorine atom. Specific examples of the fluorine-containing ethylenic monomer include tetrafluoroethylene [TFE], vinylidene fluoride [VDF], chlorotrifluoroethylene [CTFE], vinyl fluoride, hexafluoropropylene [HFP], hexafluoro Isobutene, formula (1)

(Wherein X ¹ is H or F, X ² is H, F or Cl, and n is an integer of 1 to 10), perfluoro (alkyl vinyl ether), and the like.

Examples of the perfluoro (alkyl vinyl ether) [PAVE] include perfluoro (methyl vinyl ether) [PMVE], perfluoro (ethyl vinyl ether) [PEVE], perfluoro (propyl vinyl ether) PPVE] and perfluoro (butyl vinyl ether).

The fluorine-containing resin may be a copolymer having the fluorine-containing ethylenic monomer unit and the fluorine-free ethylenic monomer unit.

The fluorine-free ethylenic monomer is preferably an ethylenic monomer having 5 or less carbon atoms in view of heat resistance and chemical resistance. Specific examples thereof include ethylene, propylene, 1-butene, 2-butene, vinyl chloride , Vinylidene chloride, and the like.

Examples of the fluorine-containing resin include polytetrafluoroethylene [PTFE], polychlorotrifluoroethylene [PCTFE], ethylene [Et] -TFE copolymer [ETFE], Et- chlorotrifluoroethylene [CTFE] It is preferably at least one selected from the group consisting of CTFE-TFE copolymer, TFE-HFP copolymer [FEP], TFE-PAVE copolymer [PFA] and polyvinylidene fluoride [PVdF].

The fluorine-containing resin is more preferably at least one fluorine-containing copolymer selected from the group consisting of PFA, FEP and ETFE, more preferably ETFE.

The PFA is not particularly limited, but a copolymer having a molar ratio of TFE unit to PAVE unit (TFE unit / PAVE unit) of 70 to 99/30 to 1 is preferable. A more preferable molar ratio is 80 to 98.5 / 20 to 1.5. If the TFE unit is too small, the mechanical properties tend to be deteriorated. If the TFE unit is too large, the melting point tends to be too high, and the moldability tends to deteriorate.

The PFA is also preferably a copolymer having 0.1 to 10 mol% of monomer units derived from monomers copolymerizable with TFE and PAVE, and 90 to 99.9 mol% of TFE units and PAVE units in total.

Examples of the monomer copolymerizable with TFE and PAVE include HFP, CZ ¹ Z ² = CZ ³ (CF ₂ ) _n Z ⁴ _wherein Z ¹ , Z ² and Z ³ are the same or different and represent a hydrogen atom or a fluorine atom , Z ⁴ represents a hydrogen atom, a fluorine atom or a chlorine atom, and n represents an integer of 2 to 10), and CF ₂ ═CF-OCH ₂ -Rf ¹ (wherein Rf ¹ represents a carbon number of 1 And an alkyl perfluorovinyl ether derivative represented by a perfluoroalkyl group having 1 to 5 carbon atoms.

The FEP is not particularly limited, but a copolymer having a molar ratio (TFE unit / HFP unit) of TFE unit to HFP unit of 70 to 99/30 to 1 is preferable. A more preferable molar ratio is 80 to 97/20 to 3. If the TFE unit is too small, the mechanical properties tend to be deteriorated. If the TFE unit is too large, the melting point tends to be too high, and the moldability tends to deteriorate.

The FEP is also preferably a copolymer having a monomer unit derived from a monomer copolymerizable with TFE and HFP in an amount of 0.1 to 10 mol%, and a total of a TFE unit and an HFP unit in an amount of 90 to 99.9 mol%. Examples of the monomer copolymerizable with TFE and HFP include PAVE, alkyl perfluorovinyl ether derivatives and the like.

As the ETFE, a copolymer having a molar ratio of TFE unit to ethylene unit (TFE unit / ethylene unit) of 20 to 90/80 to 10 is preferable. A more preferable molar ratio is 37 to 85/63 to 15, and a more preferable molar ratio is 38 to 80/62 to 20.

The ETFE may be a copolymer comprising TFE, ethylene, and monomers copolymerizable with TFE and ethylene.

As the monomer copolymerizable with TFE and ethylene,

_{^{CH 2 = CX 3 Rf 2,}} CF 2 = CFRf 2, CF 2 = CFORf 2, CH 2 = C (Rf 2) 2

(Wherein X ³ represents a hydrogen atom or a fluorine atom, and Rf ² represents a fluoroalkyl group which may contain an ether bondable oxygen atom), among which CF ₂ = CFRf ² , CF ₂ = CFORf ² and CH ₂ = CX ³ Rf ² , and is preferably at least one member selected from the group consisting of HFP, CF ₂ ═CF ³ -Rf ³ wherein Rf ³ is a carbon number of 1 to refers to an alkyl group in the 5 perfluoroalkyl) as shown which is perfluoro (alkyl vinyl ether) [PAVE], and Rf ⁴ is a CH ₂ = CX ³ Rf ⁴ the fluorine-containing vinyl-expressed with a fluoroalkyl group having 1 to 8 carbon atoms More preferably at least one member selected from the group consisting of monomers.

Examples of the fluorine-containing vinyl monomer includes, for example, such as _{CH 2 = CH-C 4 F} 9, CH 2 = CF-CF 2 -CF 2 -CF 2 H, CH 2 = CH-C 6 F 13. As the monomer copolymerizable with TFE and ethylene, an aliphatic unsaturated carboxylic acid such as itaconic acid or itaconic anhydride may be used.

The monomer copolymerizable with TFE and ethylene is preferably used in an amount of 0.1 to 10 mol%, more preferably 0.1 to 5 mol%, and particularly preferably 0.2 to 4 mol% based on the fluorine-containing polymer.

The ETFE preferably has a TFE unit content of 50 mol% or more, more preferably 55 mol% or more, and still more preferably 65 mol% or more, with respect to all the monomer units constituting the ETFE from the viewpoint of good releasability.

The content of each monomer in the above-mentioned copolymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis and fluorescent X-ray analysis according to the types of monomers.

The fluorine-containing resin preferably has a melt flow rate (MFR) of 60 g / 10 min or less. If it exceeds 60 g / 10 min, there is a possibility that the releasability between the resin and the release film is lowered when the resin (sealing material) is demolded from the mold after the molding. The MFR is more preferably 45 g / 10 min or less, still more preferably 30 g / 10 min or less, particularly preferably 25 g / 10 or less, most preferably 18 g / 10 min or less.

The MFR is preferably not less than 1.5 g / 10 min, more preferably not less than 4 g / 10 min, more preferably not less than 10 g / 10 min, since roughness does not occur on the surface of the molded product even in the course of high- And particularly preferably 20 g / 10 min or more.

The MFR is a value measured by a method in accordance with ASTM D 3159.

The fluorine-containing resin preferably has a melting point of 180 to 270 캜.

The melting point of the fluorine-containing resin is more preferably from 230 to 270 ° C from the viewpoint of heat resistance, more preferably from 200 to 230 ° C from the viewpoint of low elasticity, and still more preferably from 190 to 230 ° C.

The melting point is a temperature corresponding to the maximum value in the heat of fusion curve when the temperature is raised at a rate of 10 ° C / minute using a differential scanning calorimeter [DSC].

The release film of the present invention may contain other components as necessary insofar as the effect of the present invention is not impaired. Examples of the other components include various fillers such as inorganic powder, glass fiber, carbon fiber, metal oxide, or carbon, pigments, ultraviolet absorbers, other optional additives, resins such as other fluorine-containing polymers, thermoplastic resins and thermosetting resins , Synthetic rubber, and the like. By blending these, it is possible to improve the mechanical properties, improve the weather resistance, impart design properties, prevent static electricity, and improve moldability.

The release film comprising the fluorine-containing resin of the present invention may be a release film comprising a single layer or a release film having a lamination structure. The release film having a laminated structure may contain two or more layers containing a fluorine-containing resin, and may include a layer containing at least one fluorine-containing resin and a layer containing a resin other than the at least one fluorine- . The release film of the present invention is preferably composed of a single layer.

The release film of the present invention preferably has a thickness of 15 to 100 mu m. If the thickness is less than 15 占 퐉, the strength is not sufficient and the release film may relax or tear at the time of stretching. If it is more than 100 탆, the ability to follow the mold is lowered, and there is a fear that wrinkles easily occur in the molded article.

The thickness is a value obtained according to the JIS K 7130 A method.

The release film of the present invention preferably has a modulus of elasticity at 25 占 폚 in the longitudinal direction (MD) of 350 to 600 MPa and a transverse direction (TD) of 350 to 550 MPa.

The release film of the present invention preferably has a modulus of elasticity at 120 占 폚 in the longitudinal direction (MD) of 20 to 70 MPa and a transverse direction (TD) of 20 to 75 MPa.

The elastic modulus is a value measured by ASTM D-1708.

The release film of the present invention can be produced by molding the fluorine-containing resin alone or a mixture of the fluorine-containing resin and the other components into a film.

Examples of the mixing method of the fluorine-containing resin and the other components include a melt kneading method and the like.

Examples of the method of molding into the film shape include a melt extrusion method, an inflation method, and a T-die method. From the viewpoint of high precision of the film thickness, the T-die method is preferable.

In the T-die method, when the molten resin is rolled into a film and molded into a film, it is stretched in the extrusion direction (MD direction). In the case of producing the release film of the present invention by such a T-die method, it is preferable to narrow the lip width of the die or shorten the air gap so as to suppress the orientation of the formed film as much as possible.

For example, when the lip width of the die is narrowed, the lip width is preferably less than 1.5 mm.

When the air gap is shortened, the air gap is preferably 145 mm or less.

The air gap refers to the distance between the outlet of the die and the time when the molten resin comes into contact with the cooling roll.

The release film of the present invention can be suitably applied as a release film for molding a resin used for molding a resin to produce a molded article. The molded article produced using the release film of the present invention has low surface roughness and high yield.

In general, the molding of the semiconductor encapsulating material is performed at a molding temperature of 170 to 180 캜, and the molding of the light emitting diode sealing material is performed at a molding temperature of 100 to 150 캜. The release film of the present invention is suitably used in the molding of a semiconductor encapsulation material or a light emitting diode encapsulation material which is performed within the above-described molding temperature range since the thickness unevenness hardly occurs even at a high temperature.

Specifically, the release film of the present invention is a mold for molding a semiconductor sealing material or a light emitting diode sealing material, which is sandwiched between a sealing material and a mold of a molding machine, And can be particularly suitably applied as a film.

Particularly, in the release film of the present invention, even when a plurality of air-shaped concave portions are pressed at equal intervals, the thickness irregularity hardly occurs. Therefore, it is particularly preferable that the release film of the present invention is used in the molding of a light emitting diode sealing material.

Example

EXAMPLES The present invention will be described in further detail with reference to the following examples, but the present invention is not limited to these examples.

(Example 1)

Using a T-die method using ETFE (1) (NEOPLON ETFE EP-610 (trade name), melting point 223 DEG C, MFR 30.0 g / 10 min, manufactured by Daikin Industries Co., Ltd.) (Thickness: 50 占 퐉, stretch ratio (115 占 폚, 10 minutes) at a die temperature of 305 占 폚 under the condition that the rib width of the release film was narrowed (0.8 mm) and the orientation of the resin in the extrusion direction was suppressed. MD: -1.15%, TD: 0.25%).

(Example 2)

ETFE (2) (NEOPLON ETFE EP-543 (trade name), melting point 258 DEG C, MFR 6.0 g / 10 min, manufactured by Daikin Industries, Ltd.) was used in place of ETFE (1) (Thickness: 50 占 퐉, MD: -0.65%, TD: -0.66%) at a stretch ratio (115 占 폚, 10 minutes) in the same manner as in Example 1 except that the die temperature was changed to 340 占 폚.

(Example 3)

ETFE (3) (NEOPLON ETFE EP-546 (trade name), melting point 253 DEG C, MFR 6.0 g / 10 min, manufactured by Daikin Industries Co., Ltd.) was used in place of ETFE (1) (Thickness: 50 占 퐉; MD: -0.82%; TD: 0.29%; MD: 115 占 폚, 10 minutes) MD was obtained in the same manner as in Example 1 except that the die temperature was changed to 340 占 폚.

(Example 4)

Except that FEP (NEOPLON FEP NP-120 (trade name), melting point 265 DEG C, MFR 7.0 g / 10 min, manufactured by Daikin Industries, Ltd.) was used in place of ETFE (1) (Thickness: 50 占 퐉, elongation (115 占 폚, 10 minutes) MD: 0.21%, TD: -1.52%) was obtained in the same manner as in Example 1,

(Comparative Example 1)

(50 占 퐉 in thickness, stretch ratio (115 占 폚, 10 minutes) MD: -4.64%, TD in 10 minutes) in the same manner as in Example 1 except that the lip width was widened : 0.20%).

The resulting release film was evaluated for the following items. The obtained results are shown in Table 1.

≪ Measurement of Stress in the Longitudinal Direction (MD) and the Longitudinal Direction (TD)

Stress-strain curves (S-S curves) in the longitudinal direction and the width direction were obtained by measurement in accordance with ASTM D1708-02a except that the atmospheric temperature was set at 120 DEG C and the tensile rate was set at 100 mm / min. Then, the value obtained when the distortion (elongation) of each obtained stress-strain curve was 60% was taken as the value of each stress.

Further, in the obtained stress-strain curves, the difference between the stress values in the longitudinal direction and in the width direction in the cases of the distortion of 120% and 180% was calculated.

<Breaking Strength and Breaking Elongation>

The breaking strength and elongation at break of the obtained release film in the longitudinal direction and the width direction were measured using Autograph AG-1 KNIS (Shimadzu Seisakusho Co., Ltd.) under the following conditions.

The tensile conditions at 28 占 폚 were a rectangular shape (10 mm width) and a tensile speed of 500 mm / min (in accordance with JIS K 7127).

The tensile conditions at 120 占 폚 were a sample shape of a micro dumbbell (thickness 50 占 퐉) and a tensile speed of 100 mm / min (in accordance with ASTM D1708-02a).

<Mold Formability>

The mold release film obtained above was used to perform mold molding under the following conditions, and the obtained molded article was evaluated according to the following criteria.

(Molding conditions)

(A4 size: sheet of 30 cm long × 20 cm wide sheet) was set on a mold (mold formed by air-shaped concave portion having a diameter of 2.6 mm) of a constant temperature (115 ° C) by a resin mold molding method The roll film may be set to a roll to roll), and vacuum-drawn to follow the mold. Thereafter, an uncured silicone resin for sealing (trade name: OE-6370HF (manufactured by Toray Dow Corning Co., Ltd.)) was flown and held for 120 to 300 seconds to cure the resin. Then, the mold was opened to demold the molded product, .

(Assessment Methods)

The surface of the obtained molded article was observed using a microscope (DIGITAL MICROSCOPE VHX-900, manufactured by KEENES CO., LTD., Magnification: 25 to 100) and evaluated according to the following criteria.

(Evaluation standard)

○: The surface was not rough.

X: The surface was rough.

It can be seen from Table 1 that by using the release film of the examples, a resin molded article having a good surface state can be obtained in the molding of the resin using the mold forming apparatus.

&Lt; Industrial applicability >

The release film of the present invention can be suitably applied as a mold releasing film for releasing a resin from a mold at the time of molding.

Claims (6)

A release film comprising a fluorine-containing resin,
The release film had a difference in stress between the longitudinal direction and the transverse direction of the film of 1.80 MPa or less and the stress was measured by a method in accordance with ASTM D1708-02a under the conditions of an ambient temperature of 120 DEG C and a tensile rate of 100 mm / Is a value obtained by measurement. The method according to claim 1,
Wherein the stretching ratio in the longitudinal direction and the width direction of the film is 0.50% or less. 3. The method according to claim 1 or 2,
The fluorine-containing resin is at least one member selected from the group consisting of a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and an ethylene-tetrafluoroethylene copolymer. film. 4. The method according to any one of claims 1 to 3,
And the fluorine-containing resin is an ethylene-tetrafluoroethylene copolymer. 5. The method of claim 4,
Wherein the content of tetrafluoroethylene units relative to all the monomer units constituting the ethylene-tetrafluoroethylene copolymer is 50 mol% or more. 6. The method according to any one of claims 1 to 5,
A release film for use in molding a light emitting diode sealing material.

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