JP2001179892A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightly releasable release film having a release layer based on polydimethylsiloxane, reduced in the transfer of a silicone component from the release layer and useful for a protective film for a self-adhesive film or a carrier film for molding a resin film or a ceramic sheet. SOLUTION: A release film satisfies such a condition that (1) a ratio of the peak strength of polydimentylsiloxane to that caused by chloroform when a chloroform extract is measured by 1H-NMR is 0-3, (2) a ratio of the repelled area of an oily paint to a painting-out area is 0-10% when the surface of the release layer of the release film and the surface to which the release layer of the plastic film constituting the release film is not laminated are superposed one upon another to be pressed under a specific condition and the pressed part of the plastic film is painted out with an oily paint and (3) the ordinary temperature peel strength of the release layer of the release film is 10-100 mN/25 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more particularly, to a release film when used as a protective film for an adhesive film or a carrier film for molding a resin sheet, a resin film or a ceramic sheet. The present invention relates to a release film having less migration.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive film is usually produced by applying a coating solution containing a pressure-sensitive adhesive and a solvent to the surface of a base film, and then heating to remove the solvent. The release film is laminated on the surface of the pressure-sensitive adhesive film and used as a protective film.

[0003] The release film is also used as a carrier film when forming a resin sheet, a resin coating or a ceramic sheet. For example, the resin sheet is separated from the carrier film after coating (casting) a resin solution obtained by dissolving a resin such as a vinyl chloride resin in a solvent on a release film (carrier film), heating and removing the solvent, Used for various applications such as marking sheet. In addition, the resin coating, after applying a coating solution comprising a resin such as an adhesive and a solvent on the surface of the carrier film,
It is formed by heating to remove the solvent. Also,
The ceramic sheet is formed as a ceramic green sheet (ceramic green sheet) by, for example, applying a slurry in which a ceramic powder and a binder agent or the like are dispersed in a solvent onto a carrier film, and removing the solvent by heating.

The release film used for the above applications has a structure in which a release layer is laminated on one or both sides of a base film. As a component of the release layer, generally, a silicone resin, a fluorine resin, an aliphatic wax, or the like is used, and among these components, a stable film or sheet provided on the release film when peeling off. Silicone resin is excellent in terms of uniform and light release characteristics and cost. But,
The release layer using a silicone-based resin can provide a light release force by selecting the silicone-based resin, but unreacted components, etc. remain, or a silicone-based resin is used to obtain a lighter release force. Oil may be added, and these unreacted components and silicone oil may migrate to the resin sheet or ceramic sheet, which may cause problems in printing, laminating, laminating, etc. in subsequent steps. You.

In general, resin sheets, ceramic sheets, and the like are often used for applications requiring high-precision surface properties. Therefore, the surface of a carrier film on which these are formed, particularly, a base used for the carrier film. The surface roughness of the film greatly affects the surface roughness of a resin sheet, a ceramic sheet, or the like. As a base film of these carrier films, an olefin-based film such as polyethylene or polypropylene, or a polyester film such as biaxially oriented polyethylene terephthalate (hereinafter sometimes abbreviated as PET) is often used. Further, a polyester film or the like generally contains a lubricant composed of inert fine particles in order to impart lubricity to the film. However, while techniques such as thinning of resin sheets and ceramic sheets and fine processing on their surfaces are progressing, aggregates of resins such as fish eyes and additives such as lubricants are present in the film, A large surface roughness may cause a defect such as a variation in thickness of a resin sheet or a ceramic sheet or a pinhole. For example, when a release film is wound into a roll,
If the base film has protrusions due to agglomerates, pressure is applied to the release layer, and the components constituting the release layer migrate to the film in contact with the release layer, and the release layer becomes non-uniform and uniform. There is a concern that the wettability will deteriorate.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the disadvantages of the prior art and to provide a release film having a release layer containing polydimethylsiloxane as a main component. It is an object of the present invention to provide a release film having a small release property which is useful for a protective film of an adhesive film or a carrier film for molding a resin sheet, a resin film or a ceramic sheet.

[0007]

The object of the present invention is to provide, according to the present invention, one or both sides of a plastic film,
A film provided with a release layer having a thickness of 0.02 to 1 μm and containing polydimethylsiloxane as a main component, wherein the film satisfies the following characteristic ranges (1) to (3): Achieved by film. (1) releasing the chloroform extract of the film ¹ H-NM
When measured at R, the ratio of the peak intensity of polydimethylsiloxane to the peak intensity attributable to chloroform was 0%.
3 or less. (2) The release layer surface of the release film and the surface of the plastic film constituting the release film on which the release layer was not laminated were overlapped, and pressure was applied under the conditions of a pressure of 9.8 MPa, a temperature of 70 ° C., and 20 hours. Thereafter, when the pressurized portion of the plastic film is painted with oil-based ink, the area where the oil-based ink is repelled is 0% or more and 10% or less with respect to the painted area. (3) The release force of the release layer of the release film at room temperature is 10 mN /
25mm or more and 100mN / 25mm or less.

Further, it is preferable that the base film of the release film is a biaxially oriented polyester film, the center line average roughness (Ra) of which is 2 to 50 nm, and one side of the base film. Length 210m
m and a range of the length of the side orthogonal to the length of 148 mm (area 3
It is preferable that there is no foreign matter having a major axis of 25 μm or more at 10.8 cm ² ) and there are no more than 10 foreign matter having a major axis of 5 μm or more and less than 25 μm.

[Plastic Film] The plastic film used as the film substrate in the present invention is preferably a polyester film which is excellent in heat-resistant dimensional stability of the film, flatness, and little fisheye during film formation. As the polyester film, a polyester film having good transparency is preferably used for applications requiring transparency, and a biaxially stretched polyester film is particularly preferable. For applications requiring hiding and light-shielding properties, it is preferable to use a polyester film containing an inorganic pigment, and a biaxially stretched polyester film containing a pigment such as TiO ₂ or SiO ₂ is particularly preferable.

The polyester constituting such a polyester film is preferably a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component. Examples of the polyester film include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate and polyethylene terephthalate. 2,6-naphthalenedicarboxylate and the like can be mentioned. Further, a copolymer in which a part of these is substituted by another component, or a mixture with polyalkylene glycol or another resin may be used.

The above polyester film is preferably a biaxially stretched film. The biaxially stretched film can be produced by a known method. For example, the polyester is dried and then melted, and a die (eg, a T-die, an I-die, etc.) is formed.
, And rapidly cooled to obtain an unstretched film. Subsequently, the unstretched film is stretched in the longitudinal direction in a range of 2 to 5 times, and then stretched in the transverse direction in a range of 2 to 5 times. And heat-setting at 160 to 260 ° C. There is no particular limitation on the film thickness,
5 to 200 μm is desirable.

Such a polyester film may contain a lubricant such as inorganic fine particles or organic fine particles in order to improve the slipperiness and processability of the film.
In particular, the center line average roughness (Ra) of the substrate film surface should be 2
The average particle diameter is in the range of 0.01 nm to 20 μm, preferably 0.1 nm
Inorganic or organic fine particles having a size of not less than 5 μm and
The content is preferably 001 to 10% by weight, particularly preferably 0.01 to 3% by weight. When Ra is less than 2 nm, when the film is wound, there is a problem that the films adhere to each other and become hard to slip, and
When it is larger than 50 nm, there is a concern that irregularities may be deformed on the surface of the resin sheet or the ceramic sheet coated on the release film. Specific examples of such fine particles include silicon dioxide, anhydrous silicon, hydrated silicon, aluminum oxide, kaolin, calcium carbonate, titanium oxide, aluminum silicate (including calcined products and hydrates), monolithium phosphate, phosphoric acid 3 Inorganic fine particles such as lithium, calcium phosphate, lithium benzoate, barium sulfate, double salts of these compounds (including hydrates), carbon black, glass powder, clay (including kaolin, benite, clay, etc.) and crosslinked acrylic resins And organic fine particles such as a crosslinked polystyrene resin, a melamine resin, a crosslinked silicone resin, and a polyamideimide resin. In addition, one kind of these fine particles may be used, or two or more kinds may be used. In order to maintain the effects of the present invention,
In order to prevent a change in performance due to the interaction, the particles are preferably inert particles. In addition, as a method of containing the fine particles, a method of thinly laminating a layer containing these fine particles on at least one surface of the substrate film can also be used. As a lamination method, it is applied at the time of film formation,
Further, for example, a co-extrusion method using a plurality of extruders and a feed block or a multi-manifold die may be used.

[0013] In addition to the fine particles, a stabilizer, an ultraviolet absorber, a coloring agent, a flame retardant, an antistatic agent, a light stabilizer, an antioxidant, etc., as long as the surface flatness and thermal stability of the film are not impaired. Can be incorporated into the polyester polymer. A small amount of other thermoplastic resin (for example, 2
0% by weight or less, especially 10% by weight or less).

Further, in the biaxially oriented polyester film, there is no foreign matter having a major axis of 25 μm or more in a range (area: 310.8 cm ² ) of 210 mm on one side and 148 mm on a side orthogonal thereto, and a 5 μm major axis. Above 2
It is preferable that the number of foreign substances having a size of less than 5 μm is 10 or less.
When a foreign substance having a major axis of 25 μm or more is present, voids or the like are generated at the time of application or transfer of the adhesive, and the adhesive is removed or swells only at that portion, so that there is a local appearance defect that can be visually confirmed. May be. In addition, when the release film is formed into a roll, pressure is locally applied to the release layer, and as a result, uniform wettability of the release layer is deteriorated, and a resin solution such as an adhesive or a ceramic slurry is further placed thereon. Is apprehended that an unsightly appearance defect may occur. In addition, foreign matters of 5 μm or more and less than 25 μm
If the number is larger than 0, the above-mentioned disadvantage may be conspicuous due to the large number.

[Release Layer] In the release film of the present invention, a release layer mainly composed of polydimethylsiloxane is provided on one or both sides of a plastic film. Such a release film needs to satisfy the following characteristic ranges (1) to (3). (1) releasing the chloroform extract of the film ¹ H-NM
When measured at R, the ratio of the peak intensity of polydimethylsiloxane to the peak intensity attributable to chloroform was 0%.
3 or less. (2) The release layer surface of the release film and the surface of the plastic film constituting the release film on which the release layer was not laminated were overlapped, and pressure was applied under the conditions of a pressure of 9.8 MPa, a temperature of 70 ° C., and 20 hours. Thereafter, when the pressurized portion of the plastic film is painted with oil-based ink, the area where the oil-based ink is repelled is 0% or more and 10% or less with respect to the painted area. (3) The release force of the release layer of the release film at room temperature is 10 mN /
25mm or more and 100mN / 25mm or less.

The release layer containing polydimethylsiloxane as a main component is a release layer obtained by mainly adding or condensing a silicone resin having polydimethylsiloxane as a main skeleton as described below. Among them, an addition reaction system having a high reaction rate is preferable as the one having a small amount of silicone migration. The silicone that can be used may be a known silicone, but it is preferable that a silicone oil or other component that does not easily migrate is added. Addition reaction: {Si-CH = CH ₂ + H-Si} → {Si-CH ₂ −
CH ₂ —Si≡ condensation reaction: {Si—OH + H—Si} → {Si—O—Si} +
H ₂

As a measure of the transferability and transferability of the release layer, in the above-mentioned chloroform extraction method, the release film is immersed in chloroform for 30 minutes, and then the extract is analyzed by ¹ H-NMR, and the extraction Is defined as the ratio of the peak intensity of polydimethylsiloxane to the peak intensity of the polydimethylsiloxane.
Such an intensity ratio needs to be 0 or more and 3 or less. If the strength ratio is greater than 3, a large amount of the silicone component is extracted into chloroform, which means that a large amount of the transfer and transfer components from the release layer are present, and the silicone transfer to the back surface of the release film roll. Is large,
There is a concern that the wettability of the resin solution or the ceramic slurry on the surface of the release film may be deteriorated.

Further, the release layer surface of the release film and the surface of the plastic film constituting the release film on which the release layer is not laminated are overlapped, and the pressure is 9.8 MPa, the temperature is 70 ° C., and the pressure is 9.8 MPa.
After pressurizing under the condition of 0 hours, when the pressurized portion of the plastic film is painted with oil-based ink, the area where the oil-based ink is repelled must be 0% or more and 10% or less with respect to the painted area. And it is preferably 0% or more and 5% or less. If the repelled area is larger than 10%, the wettability described above is concerned, and further, a silicone component adheres to the interface between the formed resin sheet and the ceramic sheet with the release film. There is a concern that it becomes difficult to adhere during lamination, lamination, etc., and that a problem may occur.

As a method of suppressing the migration of silicone, there are no addition of a component that deteriorates the migration such as silicone oil, the thickness of the release layer is set as described below, and silicone, catalyst and other additives are added. And the like.

Silicone oil having no functional group easily bleeds out and migrates to the surface in the release layer, and even if it has a functional group at the terminal or side chain, it does Since the amount is small, it is feared that the migration property is deteriorated. Further, among silicones, platinum-based catalysts, reaction inhibitors, and the like, those dispersed in silicone oil may deteriorate the transferability depending on the amount thereof.

The thickness of the release layer must be 0.02 to 1 μm, preferably 0.05 to 0.5 μm. When the thickness is less than 0.02 μm, the base film is not sufficiently covered with the silicone resin, and there is a concern that a defect of heavy peeling may occur. On the other hand, if the thickness is more than 1 μm, the absolute amount of unreacted substances and low-molecular silicone increases, which may cause migration of silicone.

The silicone resin has a release force of 10 mN / 2 at room temperature to control the release force.
The use of functional groups and various additives can be used within a range satisfying 5 mm or more and 100 mN / 25 mm or less and not impairing the non-migratory property of the silicone resin. For example, examples of the functional group include an alkyl group such as an ethyl group and a hexenyl group and a phenyl group. Further, as an additive, a silicone resin or a silica filler such as colloidal silica can be used. Further, an organic resin can be added, for example, an alkyd resin, an acrylic resin, a melamine resin, or the like can be added.

[Method of Coating Release Layer] In the present invention,
The release layer is provided on one side or both sides of the plastic film. For example, the release layer is formed by applying a coating liquid containing the components constituting the release layer to a film, drying by heating and curing to form a coating film. By doing so, it can be applied. As a coating method of the coating liquid, any known coating method can be applied, and examples thereof include a roll coating method, a blade coating method, and a bar coating method, but are not limited to these methods. .

[Adhesive Layer] In the present invention, an adhesive layer is provided on at least one side of the plastic film in order to enhance the adhesion between the plastic film and the release layer, and a release layer is further laminated on the adhesive layer. can do. For this adhesive layer, for example, a silane coupling agent can be used. This silane coupling agent is represented by the general formula Y
It can be exemplified those represented by -Si-X _3. Here, Y is, for example, an amino group, an epoxy group, a vinyl group,
A functional group represented by a methacryl group, a mercapto group, etc., X
Represents a hydrolyzable functional group represented by an alkoxy group. The preferable thickness of the above-mentioned adhesive layer is 0.01 to 5 μm, particularly 0.02 to 2 μm.

[0025]

The present invention will be further described below with reference to examples. In addition, each characteristic value of the film was measured by the following method. (1) Surface roughness Ra Using a stylus type surface roughness meter (Surfcoder 30C, manufactured by Kosaka Laboratory Co., Ltd.), the film surface is scanned under the conditions of a needle radius of 2 μm and a stylus pressure of 30 mg. The surface displacement was measured and the surface roughness curve was recorded. From this surface roughness curve, extract the measurement length (L) in the direction of its center line,
It was calculated from the surface roughness curve (Y = f (x)) when the X axis was the scan distance and the Y axis was the surface displacement.

[0026]

(Equation 1)

(2) Room Temperature Peeling Force Nitto 31B tape (manufactured by Nitto Denko Corporation) was adhered to the release layer surface of the release film with a rubber roller, and was reciprocated once from above with a 20N rubber roller. It was left as it was under the condition of a temperature of 23 ° C. and a humidity of 55 ± 5% RH for 30 minutes, and then cut into 25 mm wide strips. Using a tensile tester (Strograph manufactured by Toyo Seiki Co., Ltd.)
The bonded tape was pulled at 180 ° at 300 mm / min, and its strength was defined as the room temperature peeling force.

(3) Extraction with chloroform The release film was immersed in chloroform for 30 minutes, and the extract was analyzed by ¹ H-NMR.
The peak intensity at 7.3 ppm of the signal and 0.084 ppm of the methyl group CH signal of polydimethylsiloxane was integrated and calculated as the intensity ratio of polydimethylsiloxane to chloroform 1.

(4) Number of Foreign Substances in Plastic Film A plastic film sample was 210 mm in length × 14 in width.
8 mm (area 310.8 cm ² ) was cut out, and the whole area of the film was inspected for foreign substances by visual inspection by the cross Nicol method. Next, the detected foreign matter in the sample film was observed with transmitted light using an optical microscope, and the maximum diameter of a portion observed as an optically abnormal range was defined as the size of the foreign matter. In addition, when a cavity (void) existing around the foreign particle is observed as an optically abnormal range, it is included in the size of the foreign particle. Then, the size of the foreign particles was counted in a range of 5 μm to less than 25 μm and 25 μm or more.

(5) Evaluation of ink repellency A plastic film constituting the release film is superimposed on the release layer surface of the release film, and after pressurizing under the conditions of a pressure of 9.8 MPa, a temperature of 70 ° C. and 20 hours, The plastic film was peeled off from the release layer surface. Next, an oil-based ink pen “Product name: Magic ink extra-thick 18 mm (oil-based, M
GD-T2 red) ", the area of 6 cm × 10 cm of the plastic film surface superimposed on the release layer was painted out. Place this filled part on graph paper,
The area of the repelled part was marked, the area was determined, and the area was divided by the area of the solid part to calculate the percentage.

(6) Wettability of paint The release film after pressurization prepared in (5) is used, and acrylic paint Olivine BPS4849 is used as paint.
(Toyo Ink Co., Ltd.) 100 parts of curing agent BP
2 parts of S8515 (manufactured by Toyo Ink Co., Ltd.) were charged, and applied to the release layer surface of the release film so as to have a dry thickness of 5 μm using an applicator having a gap of 25 μm. Was observed and evaluated according to the following criteria. A: Adhesive surface is smooth and no peeling is observed ... good wettability B: Slightly undulating peeling is partially present ... slightly wettability C: Clear peeling is observed ... wettability Bad

Example 1 An intrinsic viscosity of 0.62 containing 0.1% by weight of true spherical silica particles having an average particle size of 0.15 μm.
The polyethylene terephthalate polymer was melted by an extruder, and was brought into close contact with a rotary cooling drum maintained at 40 ° C. from a die by using an electrostatic adhesion method, and rapidly cooled to obtain an unstretched film. Next, the unstretched film was stretched 3.5 times in the machine direction and then 3.6 times in the transverse direction,
Heat fixing was performed at 20 ° C. to obtain a biaxially oriented polyethylene terephthalate film having a thickness of 38 μm. Next, a curable silicone of a type in which a platinum catalyst is added to a mixed solution of polydimethylsiloxane and dimethylhydrogensilane to cause an addition reaction (LTC manufactured by Toray Dow Corning Co., Ltd., LTC
760A) was dissolved in a mixed solvent of methyl ethyl ketone and toluene to prepare a solution having a solid content of 2%. Further, a platinum catalyst dispersed in toluene (NC25, manufactured by Toray Dow Corning Co., Ltd.) was added as a catalyst in an excess amount of 6 parts with respect to 100 parts of the silicone solid content, and coated on the biaxial polyethylene terephthalate film. Quantity 6
g / m ² (wet), dried and cured at a heating temperature of 140 ° C. for 1 minute to obtain a release layer having a thickness of 0.15 μm.
m was formed. Table 1 shows the characteristics of the release film.

Comparative Example 1 A release film was prepared in the same manner as in Example 1, except that the toluene dispersion of the catalyst used was changed to a silicone oil dispersion. Table 1 shows the characteristics of the release film.

Comparative Example 2 A release film was prepared in the same manner as in Example 1, except that the thickness of the silicone after drying was changed to 1.2 μm. Table 1 shows the characteristics of the release film.

Comparative Example 3 The procedure of Example 1 was repeated except that the components of the release layer were changed to the following.
Table 1 shows the characteristics of the release film. 100 parts by weight of an acrylic resin (ethyl polyacrylate), 100 parts by weight of a melamine resin (butylated melamine resin) and 70 parts by weight of a silicone resin (hydroxyl-substituted diphenylpolysiloxane) (100 parts by weight of a resin mixture composed of an acrylic resin and a melamine resin) Silicone resin 35
(Equivalent to parts by weight) was dissolved in a mixed solvent of methyl ethyl ketone and toluene to prepare a solution having a total solid content of 3% by weight.
Further, an acid catalyst (p-toluenesulfonic acid) was added to the above solution to prepare a coating solution.

Comparative Example 4 In Example 1, the particles contained in the polyethylene terephthalate polymer having an intrinsic viscosity of 0.61 in the biaxially oriented polyester film were replaced with 0.5 spherical spherical silica particles having an average particle diameter of 0.5 μm. A plastic film was obtained in the same manner except that the amount was changed to wt%, and a release film was prepared. The characteristics are shown in Table 1.

[0037]

[Table 1]

As is clear from Table 1, the release film of the present invention shown in Examples has a small amount of foreign matter in the film.
There was almost no migration of the release layer, and it was lightly peeled off, and was excellent in wettability to paint and appearance of application. Further, in Comparative Example 3, although the migration is small and the paint appearance is excellent, the peeling force is large, so that depending on the type of the material of the resin sheet or the ceramic sheet, it is feared that when they are made into a thin layer, they can be broken without being peeled. You.

[0039]

According to the present invention, a release film having a release layer containing polydimethylsiloxane as a main component, the silicone component of the release from the release layer being small, the use of light-release silicone, and the surface roughness being further reduced. By using a base film with few coarse protrusions in the film, the migration of the release layer is further suppressed, and it is useful for a protective film of an adhesive film, a resin sheet, a resin film, and a carrier film for molding such as a ceramic sheet. A release film can be provided.

Continued on the front page F-term (reference) 4F100 AA20H AK01A AK41A AK42 AK52B AK52C BA02 BA03 BA06 BA13 CA23 DD07A EJ38A GB41 GB90 JA20A JB06 JB08 JK06B JK06C JL00 JL14B JL14C YY00 YY00AY01B01A00 AFYB

Claims (6)

[Claims] 1. A film in which a release layer mainly composed of polydimethylsiloxane having a thickness of 0.02 to 1 μm is provided on one side or both sides of a plastic film, wherein the film has the following (1) to (3): A release film characterized by satisfying the following characteristic range. (1) releasing the chloroform extract of the film ¹ H-NM
When measured at R, the ratio of the peak intensity of polydimethylsiloxane to the peak intensity attributable to chloroform was 0%.
3 or less. (2) The release layer surface of the release film and the surface of the plastic film constituting the release film on which the release layer was not laminated were overlapped, and pressure was applied under the conditions of a pressure of 9.8 MPa, a temperature of 70 ° C., and 20 hours. Thereafter, when the pressurized portion of the plastic film is painted with oil-based ink, the area where the oil-based ink is repelled is 0% or more and 10% or less with respect to the painted area. (3) The release force of the release layer of the release film at room temperature is 10 mN /
25mm or more and 100mN / 25mm or less. 2. The plastic film is a biaxially oriented polyester film having a center line average roughness (Ra).
Is 2 to 50 nm. 3. A length 21 of one side of a plastic film
^2. The mold release according to claim 1, wherein there is no foreign matter having a major axis of 25 μm or more in a range of 0 mm and a side length of 148 mm (area of 310.8 cm ² ) and 10 or less foreign matter having a major axis of 5 μm or more and less than 25 μm. the film. 4. The release film according to claim 1, which is used as a protective film for an adhesive film. 5. The release film according to claim 1, which is used as a carrier film for producing a resin sheet or a resin film. 6. The release film according to claim 1, which is used as a carrier film for producing a ceramic green sheet.