JP6109198B2 - Release film and method for producing the same - Google Patents

Description

  The present invention relates to a release film excellent in releasability (peelability) from an adhesive / adhesive such as an acrylic resin-based adhesive / adhesive or an epoxy resin-based adhesive, and a method for producing the same.

  The adhesive tape wound up in a coil shape is subjected to a release treatment on the back surface of the base material so that the adhesive layer can be easily peeled off from the back surface of the base material, or a pressure-sensitive adhesive sheet used for joining various articles. Has a release liner laminated on the surface of the adhesive layer for the purpose of protecting the adhesive layer until use.

  Moreover, in the manufacturing process of a printed wiring board, a flexible printed wiring board, a multilayer printed wiring board, etc., a release film is used when a copper-clad laminate or a copper foil is hot-pressed through a prepreg or a heat-resistant film. . Moreover, in the manufacturing process of the flexible printed circuit board, when the cover lay film or the reinforcing plate is hot-press bonded to the flexible printed circuit board body on which the electric circuit is formed by the epoxy resin thermosetting adhesive or the thermosetting adhesive sheet, In order to prevent the cover lay film and the press hot plate from adhering to each other, a release film is used.

  Silicone mold release agents are generally used as mold release agents used for mold release treatments on the back side of such base materials and release liners on the surface of adhesive layers, or release films used in the manufacturing process of printed wiring boards. Has been used. For example, a silicone-based mold release agent such as dimethylpolysiloxane is applied to the surface of the substrate (the surface that does not have an adhesive layer) and crosslinked by irradiation with temperature, light, electron beam, etc. A method for improving the releasability of an adhesive layer in contact with a film is known.

  However, in the case of a pressure-sensitive adhesive tape wound up in a coil shape, a silicone compound such as a low molecular weight silicone resin, siloxane, or silicone oil contained in a silicone-based release agent applied to the surface of the substrate (the surface that does not have an adhesive layer) However, there is a problem that the adhesive performance is deteriorated by moving to the adjacent adhesive layer. In the case of a pressure-sensitive adhesive sheet, when used for fixing electronic device components, the silicone compound that has migrated to the adhesive layer generates siloxane gas, which causes a problem of corrosion or malfunction of the electronic device.

As a method for solving such a problem, a method of using an ethylene / α-olefin random copolymer having a density of 0.80 to 0.90 g / cm ³ and a melting point of 80 ° C. or less in place of the silicone release agent ( Patent Document 1: Japanese Patent Laid-Open No. 55-65281), release from a support base for a release sheet by an ethylene-α / olefin copolymer resin having a crystallinity of 40% or less through a polyolefin resin layer. A method (Patent Document 2: Japanese Patent Application Laid-Open No. Hei 6-99551) has been proposed which is a release sheet characterized in that a mold agent layer is formed. Further, as a method for improving the extrusion processability of the ethylene / α-olefin random copolymer, an ethylene / α-olefin random copolymer having a density of 0.80 to 0.90 g / cm ³ and a release agent layer A method using a composition with a polyethylene resin having a density of 0.902 to 0.912 g / cm ³ synthesized using a metallocene catalyst (Patent Document 3: Japanese Patent No. 4531911) has been proposed.

However, as the release layer, an ethylene / α-olefin random copolymer having a density of 0.80 to 0.90 g / cm ³ described in Patent Document 1 or Patent Document 2, or a crystallinity of 40% or less (density When an ethylene / α-olefin random copolymer of 0.8 to 0.95 g / cm ³ ) is used, there is still a possibility that the releasability from the acrylic resin-based adhesive / adhesive layer is still poor.

JP-A-55-65281 JP-A-6-99551 Japanese Patent No. 4531911

  The problems of the present invention are excellent in releasability (peelability) from adhesives / adhesives such as acrylic resin-based adhesives and epoxy resin adhesives, and the release layer is not sticky, The object is to obtain a release film having contamination.

The present invention provides a random copolymer (B) of an α-olefin having a density of 865 to 880 kg / m ³ , a melting point (Tm) of 70 ° C. or less, and ethylene and 6 or more carbon atoms on one side of the base material layer. It is related with the release film characterized by laminating the release layer which consists of, and its manufacturing method.

  The release film of the present invention has a very low peel strength of 0.3 to 0.4 N / 50 mm from an adhesive / adhesive such as an acrylic resin-based adhesive / epoxy adhesive or an epoxy resin-based adhesive, and is excellent in peelability In addition, since the release layer is not sticky and has a non-silicone release layer, there is no contamination with silicon compounds, and the residual adhesion rate indicating non-contamination is good at about 90%. Further, the release film of the present invention has good writing properties of the release layer.

<Base material layer>
The base material layer constituting the release film of the present invention may be various known thermoplastic resins such as polyolefin (polyethylene, polypropylene, poly-4-methyl / 1-pentene, poly-1-butene, etc.), polyester (polyethylene terephthalate, Polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide (nylon-6, nylon-66, polymetaxylene adipamide, etc.), polyvinyl chloride, polyimide, ethylene / vinyl acetate copolymer or saponified product thereof, polyvinyl alcohol, A film made of polyacrylonitrile, polycarbonate, polystyrene, ionomer, or a mixture thereof. Among these thermoplastic resins, preferred are thermoplastic resins having good stretchability and transparency, such as polyesters such as polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate, polyamide, and polypropylene.

The base material layer according to the present invention may be an unstretched film or a uniaxially or biaxially stretched film.
The base material layer according to the present invention may be a single layer or a multilayer of two or more layers.

  Among these base material layers, biaxially stretched films made of polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are particularly preferable because they are excellent in solvent resistance and heat resistance.

  In order to improve the adhesion with the release layer, the surface of the substrate layer according to the present invention is subjected to surface activation treatment such as corona treatment, plasma treatment, undercoat treatment, primer coat treatment, frame treatment, etc. You may keep going.

<Ethylene / α-olefin random copolymer (B)>
The ethylene / α-olefin random copolymer (B) constituting the release layer constituting the release film of the present invention has a density of 865 to 880 kg / m ³ , preferably 867 to 875 kg / m ³ , a melting point (Tm ) Is 70 ° C. or less, preferably 65 ° C. or less, and 6 or more carbon atoms, preferably 6 to 10 carbon atoms such as 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc. Is a random copolymer with an α-olefin having 8 to 10 carbon atoms.

  In the present invention, the copolymer having a melting point (Tm) of 70 ° C. or lower includes an ethylene / α-olefin random copolymer that does not clearly show the melting point (Tm), that is, has no melting point (Tm). .

An ethylene / α-olefin random copolymer having a density exceeding 880 kg / m ³ or an ethylene / α-olefin random copolymer having a melting point (Tm) exceeding 70 ° C. may be used for a release layer of a release film. There is a possibility that the peelability from the adhesive / adhesive is inferior.

An ethylene / α-olefin random copolymer having a density exceeding 880 kg / m ³ or an ethylene / α-olefin random copolymer having a melting point (Tm) exceeding 70 ° C. is dissolved in an organic solvent such as toluene or hexane. Since it is difficult, it is difficult to form a release layer having a uniform thickness.

  In the ethylene / α-olefin random copolymer (B) according to the present invention, the ethylene content is not particularly limited as long as the density and the melting point (Tm) are in the above ranges, but usually in the range of 85 to 92 mol%. It is in.

  The ethylene / α-olefin random copolymer (B) according to the present invention usually has an MFR (load: 2160 g, temperature: 190 ° C.) of 0.1 to 50 g / 10 minutes, preferably 0.2 to 20 g / It is in the range of 10 minutes.

  The ethylene / α-olefin random copolymer (B) according to the present invention is a random copolymerization of ethylene and α-olefin using various known production methods, specifically, vanadium catalyst or metallocene catalyst. Can be manufactured.

  Further, the ethylene / α-olefin random copolymer (B) according to the present invention is manufactured and sold by Mitsui Chemicals, Inc. as an ethylene / 1-octene random copolymer under the trade name of Toughmer H5030.

<Release film>
In the release film of the present invention, a release layer composed of the ethylene / α-olefin random copolymer (B) is laminated on one surface of the base material layer.

The thickness of the base material layer of the release film of the present invention is usually in the range of 10 to 200 μm, preferably 15 to 100 μm, and more preferably 25 to 50 μm.
The thickness of the release layer of the release film of the present invention is usually in the range of 0.025 to 0.20 μm, preferably 0.050 to 0.15 μm, and more preferably 0.075 to 0.125 μm. When the thickness of the release layer is less than 0.025 μm, the peel strength with an adhesive / adhesive such as an acrylic resin adhesive / epoxy adhesive may exceed 1 N / 50 mm. On the other hand, when the thickness of the release layer is increased, the peel strength is further reduced, but the surface state of the release layer is deteriorated, the slipping property is lowered, and the handling property may be lowered.

The release film of the present invention is also characterized in that the release layer is as thin as 0.050 to 0.15 μm.
The release film of the present invention usually has a peel strength of 0.1-1 N / 50 mm, preferably 0.1-0, with an adhesive / adhesive such as an acrylic resin-based adhesive / epoxy adhesive. It is in the range of 7 N / 50 mm.

<Method for producing release film>
The release film of the present invention can be produced by applying and drying the solution of the ethylene / α-olefin random copolymer (B) according to the present invention on one surface of a base material layer obtained in advance.

  Since the production method of the present invention is a method of applying and drying a solution of the ethylene / α-olefin random copolymer (B), the thickness of the release layer is 0.025 to 0.20 μm, preferably 0. It is preferable because it can be as thin as 0.050 to 0.15 μm.

  Solvents used to adjust the solution of the ethylene / α-olefin random copolymer (B) are aliphatic hydrocarbons such as n-decane, n-heptane and n-hexane, and aromatic hydrocarbons such as toluene and xylene. , Alicyclic hydrocarbons such as decalin and tetralin, organic solvents such as methyl ethyl ketone and methyl isobutyl ketone, or a mixed solvent thereof, but a toluene / methyl isobutyl ketone mixed solvent (9/1: mass ratio) is most preferable.

  As a method of applying the ethylene / α-olefin random copolymer (B) solution to the base material layer, a method of applying the solution to the surface of the base material layer, a method of immersing the base material layer in the solution, the solution Various known coating methods such as a method of spraying the surface of the substrate layer can be employed.

Examples of the method for applying the ethylene / α-olefin random copolymer (B) solution to the base material layer include an air knife coater, a direct gravure coater, a gravure offset, an arc gravure coater, a gravure reverse and a jet nozzle method. Using various known coating machines such as gravure coaters, top feed reverse coaters, bottom feed reverse coaters and nozzle feed reverse coaters, reverse roll coaters, 5-roll coaters, lip coaters, bar coaters, bar reverse coaters, die coaters The ethylene / α-olefin random copolymer (B) in the solution (solid content) may be applied in an amount of 0.05 to 10 g / m ² , preferably 0.1 to 5 g / m ² .

  The application temperature of the solution is usually room temperature, for example, 10 to 40 ° C., preferably 15 to 30 ° C., but the ethylene / α-olefin random copolymer (B) is at room temperature and the solvent is used. If it is difficult to dissolve, the temperature may be lower than the boiling point depending on the solvent used.

  Moreover, the apply | coated solution is normally dried at the temperature of 70-120 degreeC, Preferably it is 90-100 degreeC.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples.
The ethylene / α-olefin random copolymers used in Examples and Comparative Examples are shown below.

(1) Ethylene / α-olefin random copolymer (B)
(1-1) Ethylene / 1-octene random copolymer (B1)
Density = 870 kg / m ³ , melting point (Tm) = 62 ° C., MFR = 5.0 g / 10 min (manufactured by Mitsui Chemicals, Inc., trade name: TAFMER H5030S).

(2) Ethylene / α-olefin random copolymer (2-1) Ethylene / 1-butene random copolymer (C1)
Density = 893 kg / m ³ , melting point (Tm) = 82 ° C., MFR = 3.6 g / 10 minutes (manufactured by Mitsui Chemicals, Inc., trade name: TAFMER A4090S).

(2-2) Ethylene / propylene random copolymer (C2)
Density = 869 kg / m ³ , melting point (Tm) = 38 ° C., MFR = 3.0 g / 10 minutes (manufactured by Mitsui Chemicals, Inc .: trade name Toughmer P-0280).

(2-3) Ethylene / 1-butene random copolymer (C3)
Density = 870 kg / m ³ , melting point (Tm) = 52 ° C., MFR = 3.6 g / 10 minutes (manufactured by Mitsui Chemicals, Inc., trade name: Toughmer A4070S).

The physical property values and the like in Examples and Comparative Examples were obtained by the following evaluation methods.
<Evaluation method>
(1) Measurement of melting point (Tm) (° C.) A sample of 5 mg was accurately weighed and increased from −50 ° C. to 10 ° C./min using a differential scanning calorimeter (DSC Q100) manufactured by TI Instruments. Heat to 200 ° C. at a temperature rate and hold for 10 minutes, then cool to −50 ° C. at a rate of 10 ° C./min and hold for 5 minutes, then raise the temperature again at a rate of 10 ° C./min, melting endotherm The temperature of the maximum peak indicated by the curve was taken as the melting point.

(2) Preparation of Solution The ethylene / α-olefin random copolymer described above was prepared at room temperature as a solution having a concentration of 1% by mass of toluene / methyl isobutyl ketone = 9/1 (mass ratio).

(3) Peeling force [N / 50mm]
The release films obtained in Examples and Comparative Examples were placed on a horizontal table with the release layer facing up, and an adhesive tape “No. 31B” (manufactured by Nitto Denko Corporation) was attached to the release layer surface to 200 mm. It cut | disconnected to the magnitude | size of * 50mm, and also the load was put so that it might become 20 g / cm < ² > from the top of the adhesive tape, and it aged at 70 degreeC for 20 hours.

After aging, 180 ° peeling was performed at a tensile speed of 300 mm / min with a tensile tester, and a value obtained by dividing the average peeling load in a region where peeling was stable by the width of the adhesive tape was determined as the peeling force.
(4) Residual adhesion rate [%]:
The release films obtained in Examples and Comparative Examples were placed on a horizontal table with the release layer facing up, and an adhesive tape “No. 31B” (manufactured by Nitto Denko Corporation) was attached to the release layer surface. Then, it was cut into a size of 200 mm × 50 mm, and a load was further applied from above the pressure-sensitive adhesive tape to 20 g / cm ² , followed by aging at 70 ° C. for 20 hours.

  After aging, the release film is peeled off, and the pressure-sensitive adhesive tape is pressure-bonded 3 times with a 2 kg rubber roller to a stainless steel plate and heat-treated at 70 ° C. for 2 hours. Next, the adhesive force F is measured according to the method of JIS-C-2107 (adhesive strength to stainless steel plate, 180 ° peeling method). The percentage of F (F / F0 × 100) relative to the adhesive force F0 when the adhesive tape “No. 31B” was directly adhered to and peeled from the stainless steel plate was determined as the residual adhesion rate.

(5) Appropriate coating (appearance)
The release surface of the obtained release film was visually confirmed, and it was evaluated as “◯” if a uniform film was formed, or “x” if no film was formed.

[Example 1]
Ethylene prepared by the above-described method as a release layer on one side of a biaxially stretched polyethylene terephthalate film (trade name Lumirror R58 manufactured by Toray Industries, Inc.) having a thickness of 31 μm and a stretching ratio of 3 × 3 as a base film. A solution of the 1-octene random copolymer (B1) was added to the Mayer bar No. 4 was applied and dried in an oven at 95 ° C. for 20 seconds to obtain a release film.

The obtained release film was evaluated by the method described above. The results are shown in Table 1.
[Comparative Example 1]
Instead of the ethylene / 1-hexene random copolymer (B1) used in Example 1, an ethylene / 1-butene random copolymer (C1) was used, but C1 was insoluble in toluene / methyl isobutyl ketone. The release film could not be obtained.

[Comparative Example 2]
A release film was obtained in the same manner as in Example 1 except that instead of the ethylene / 1-octene random copolymer (B1) used in Example 1, an ethylene / propylene random copolymer (C2) was used. . The results of the obtained release film are shown in Table 1.

[Comparative Example 3]
A release film was prepared in the same manner as in Example 1 except that instead of the ethylene / 1-hexene random copolymer (B1) used in Example 1, an ethylene / 1-butene random copolymer (C3) was used. Obtained. The results of the obtained release film are shown in Table 1.

  As is clear from Table 1, the release film using the ethylene / α-olefin random copolymer (B) according to the present invention is excellent in release properties with a peel strength of 0.34 N / 50 mm. The release film using the ethylene / α-olefin random copolymer that does not satisfy the requirements of the present invention has a strong peel strength of 11.5 N / 50 mm and is inferior in release properties.

  The release film of the present invention is excellent in releasability, and can be used as a release film for acrylic adhesives and epoxy adhesives. It is used for a release film for a process such as a substrate, a flexible printed circuit board, a multilayer printed circuit board.

Claims (3)

On one side of the substrate layer, density 865~880kg / m ^3, a melting point (Tm) is 70 ° C. or less, and the thickness consisting of a random copolymer (B) of ethylene and carbon number 8-10 α- olefin A release film comprising a release layer having a thickness of 0.025 μm to 0.15 μm .   The release film according to claim 1, wherein the base material layer is a polyester film. Drying on one side of the substrate layer, density 865~880kg / m ^3, a melting point (Tm) is 70 ° C. or less, and a random copolymer of ethylene and carbon number 8-10 α- olefin solution of (B) A method for producing a release film, characterized by applying and drying so that the subsequent thickness is in the range of 0.025 μm to 0.15 μm .