JP2000006320A - Release film, carrier film for molding resin sheet using the same, and resin sheet protecting film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film generating no release charge, excellent in releasability and useful as a carrier film for molding a resin sheet and a film for protecting a resin sheet. SOLUTION: A release film is constituted by providing a release layer on the single surface of the polyester film and providing an antistatic layer on one surface thereof. The antistatic layer comprises an org. resin containing conductive carbon black and the surface resistivity value of the antistatic layer is set to 5×104-5×109 Ω/(square) and the release charge quantity thereof is set to -5-+5 kV. By using the release film, a carrier film for molding the resin sheet and a film for protecting the resin sheet can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, a carrier film for forming a resin sheet and a film for protecting the resin sheet using the same. More particularly, the present invention relates to a polyester film as a base film, which is charged during feeding or running. Low release with excellent peeling behavior without causing charging failure on pressure-sensitive adhesive film or resin sheet formed on release layer when used for carrier film for molding such as pressure-sensitive adhesive film or resin sheet The present invention relates to a film, a carrier film for forming a resin sheet and a film for protecting a resin sheet using the release film.

[0002]

2. Description of the Related Art A release film is used as a carrier film or a surface protective sheet for molding such as an adhesive film, a resin sheet, a resin film or a ceramic sheet. For example, a vinyl chloride resin sheet is composed of a vinyl chloride resin and a solvent. After applying the coating liquid on a release film (carrier film), the solvent is removed by heating to form a vinyl chloride sheet (for example, for a marking sheet).
These pressure-sensitive adhesive films, resin sheets, resin films or ceramic sheets are conveyed while being formed on a carrier film, and are wound up, cut into an appropriate size, provided with holes, printed, and the like. You.

In the steps of transporting, cutting and printing, the above-mentioned laminated film comes into contact with various rolls and belt conveyors. However, when a release film using a polyester film as a base film is used as a carrier film, the polyester film is charged, and when the charging voltage becomes a certain value or more, when a resin sheet or the like as a product is peeled off from the carrier film. Discharge occurs on the surface of the resin sheet or the like, and particularly when the discharge is remarkable, serious physical damage is caused on the surface of the resin sheet or the like.

[0004] Further, the resin sheet or the like is cut into a desired constant shape while being laminated with the carrier film, or after the resin sheet or the like is separated and separated from the carrier film,
When stacking the cut sheets of a certain shape on a case etc., it is not possible to stack them neatly due to electrical repulsion, or conversely, the stacked sheets will stick together due to electrical inquiries, so try to align the corners of the sheets However, when the sheets are picked up one by one, there are problems such as being picked up with several sheets stuck together.

Further, when used for a magnetic recording medium or a circuit board, there is a problem that dust and dirt are adsorbed.

In order to solve these problems, various antistatic treatment methods have been proposed for the release film. As one of them, a method of directly adding an antistatic compound to a silicone resin layer has been proposed. ing. However, when an antistatic compound is added to the silicone resin layer, the crosslinking reaction of the silicone resin layer is hindered, and properties such as peeling properties and slipperiness are deteriorated. In some cases, blocking (sticking phenomenon) occurs, and in severe cases, the silicone resin layer is transferred to a roll in the process, causing a problem of process contamination. further,
When used for casting a resin sheet or the like, there is a problem that the transfer of the silicone resin or the antistatic compound contaminates the resin sheet.

As a countermeasure, there is a method of reducing the amount of the antistatic compound to be added, but there is a problem that desired antistatic performance cannot be obtained. In addition, it has been proposed to apply a coating in which a conductive polymer such as polyaniline or polypyrrole or a conductive metal oxide fine powder is dispersed in an organic resin as an antistatic layer on the back of the release layer of the release film. But,
There are problems that the cost is high and that a special solvent must be used. In addition, the quaternary ammonium salt type cationic polymer compound is inexpensive and exhibits an appropriate antistatic property,
If used for a long time at a high temperature, there is a problem that the antistatic property is reduced.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to improve the drawbacks of the prior art, to reduce the charge during feeding or running, and to be used for a carrier film for molding such as an adhesive film or a resin sheet. A release film having a release layer surface (having good releasability) which can be peeled off by a moderate force without causing a charging failure to the pressure-sensitive adhesive film or resin sheet formed on the release layer, and To provide a carrier film for forming a resin sheet and a film for protecting a resin sheet using the same.

[0009]

According to the present invention, there is provided the following 3
It consists of two components. 1. A release film provided with a release layer on one side of the polyester film and an antistatic layer provided on the other side,
The antistatic layer is made of an organic resin containing conductive carbon black, and the antistatic layer has a surface resistivity of 5 × 1
0 ^{4 to} 5 × 10 ⁹ Ω / □ and the peeling charge amount is -5 to +5 k
V. A release film characterized by being V. 2. A carrier film for forming a resin sheet using the release film. 3. A resin sheet protective film using the release film.

In the present invention, a polyester film is used as the base film. For applications requiring transparency, a polyester film having good transparency is preferably used, and a biaxially stretched polyester film is particularly preferable. For applications requiring light-shielding properties, it is preferable to use a polyester film containing a pigment.
A white biaxially stretched polyester film containing a pigment such as O ₂ or SiO ₂ is particularly preferred.

As the polyester film, it is preferable to use a polyester film in which inorganic fine particles, organic fine particles, and the like are blended as necessary. As the lubricant, inorganic fine particles are preferable, and silicon oxide-based fine particles are particularly preferable.

The polyester constituting such a polyester film is a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component. Examples of the polyester include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene-2. , 6-naphthalate and the like. Furthermore, polyethylene terephthalate, polyethylene-
2,6-Naphthalate is particularly preferred from the viewpoint of processability.

[0013] In addition, an improving agent other than the above-mentioned additives can be blended in the polyester. For example, sodium dodecylbenzenesulfonate or the like can be contained as an antistatic agent.

The polyester film of the present invention comprises:
It can be manufactured by a conventionally known manufacturing method. For example, a biaxially stretched polyester film is obtained by drying a polyester, melting it with an extruder, and forming a die (eg,
(Die, I-die, etc.), extruded onto a rotary cooling drum, quenched to produce an unstretched film, and then stretched in the machine and transverse directions, and heat-fixed if necessary. it can. The thickness of the polyester film is preferably from 5 to 250 μm.

In the present invention, a release layer is provided on the above-mentioned polyester film. Such release layer is not particularly limited, silicone resin, silicone oil, fluorine resin,
By applying a coating liquid containing at least one selected from fluorine oil, various waxes and polymers having a long-chain alkyl group as a main component to one surface of the polyester film, drying and further curing by heat or ionizing radiation. Can be formed. In addition, use an organic resin such as polyester, alkyd, polyurethane, acrylic, melamine, or polyvinyl acetal modified with silicone or fluorine, or a coating liquid of a component obtained by adding silicone oil, fluorine oil or various waxes to the organic resin. May be.

Of these, silicone resins are preferred.
Examples of the silicone resin include a condensation reaction type, an addition reaction type, and an ultraviolet or electron beam curing type. One of these silicone resins may be used alone, or two or more thereof may be used in combination. The curing reaction of various silicone resins can be shown as follows.

[0017]

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Examples of the condensation reaction type silicone resin include a polydimethylsiloxane having a terminal -OH group and a polydimethylsiloxane (hydrogensilane) having a -H group at an end, an organic tin catalyst (for example, an organic tin acylate catalyst). To form a three-dimensional cross-linked structure.

As an addition reaction type silicone resin, for example, polydimethylsiloxane having a vinyl group introduced into a terminal and hydrogensilane are reacted using a platinum catalyst.
One that forms a three-dimensional crosslinked structure may be mentioned.

As the UV-curable silicone resin,
For example, the most basic type uses the same radical reaction as ordinary silicone rubber crosslinking, the one that introduces an acrylic group and cures it, and the one that decomposes an onium salt with ultraviolet rays to generate a strong acid, thereby forming an epoxy ring. Examples thereof include those that are cleaved and crosslinked, and those that are crosslinked by the addition reaction of thiol to vinylsiloxane. Electron beams have higher energy than ultraviolet rays, and a radical crosslinking reaction occurs without using an initiator as in the case of ultraviolet curing.

As a silicone resin, the degree of polymerization is 5
Those having about 0 to 200,000, preferably about 1,000 to 100,000 are preferable, and specific examples thereof include KS-718, -774, -775, -778, and -7 manufactured by Shin-Etsu Chemical Co., Ltd.
79H, -830, -835, -837, -838,-
839, -841, -843, -847, -847H,
X-62-2418, -2422, -2125, -24
92, -2494, -470, -2366, -630,
X-92-140, -128, KS-723A-B,-
705F, -708A, -883, -709, -71
9. TPR-6701, -67 of Toshiba Silicone Co., Ltd.
02, -6703, -3704, -6705, -672
2, -6721, -6700, XSR-7029, YS
R-3022, YR-3286, Dow Corning Co., Ltd.
DK-Q3-202, -203, -204, -21
0, -240, -3003, -205, -3057, S
FXF-2560, SD-7226, -7320, -7229, manufactured by Dow Corning Toray Silicone Co., Ltd.
BY24-900, -171, -312, -374, S
RX-375, SYL-OFF23, SRX-244,
SEX-290 and SILCOLASE 425 manufactured by ICI Japan Ltd. can be exemplified. Also, JP-A-47-34447, JP-B-52
A silicone resin described in -40918 or the like can also be used.

The release layer in the present invention is formed by applying a coating solution containing the above components to one surface of a polyester film, heating and drying. As the coating method, a conventionally known method such as a bar coating method, a doctor blade method, a reverse roll coating method, or a gravure roll coating method can be used.

Drying and curing (thermal curing, ultraviolet curing, etc.) of the coating film can be performed individually or simultaneously. When performing simultaneously, it is preferable to perform at 100 degreeC or more. The drying and curing conditions are preferably 100 ° C. or more and 30 seconds or more. If the drying temperature is less than 100 ° C. and the curing time is less than 30 seconds, the curing of the coating film is incomplete, and the coating film tends to fall off, which is not preferable.

The thickness of the coating film is not particularly limited.
A range of 5 to 0.5 μm is preferred. If the thickness of the coating film is less than this range, the releasing performance is reduced and satisfactory performance cannot be obtained. Conversely, if the thickness of the coating film is larger than this range, it takes a long time for curing, which causes a disadvantage in production.

In the present invention, an antistatic layer, that is, a layer made of an organic resin containing conductive carbon black, is provided on the surface of the base film opposite to the surface on which the release layer is provided. The conductive carbon black constituting the antistatic layer in the present invention is a carbon black having an average particle diameter of about 30 to 60 nm and maintaining a chain structure, and is called acetylene black, Ketjen black or furnace black depending on the production method. Have been. As acetylene black, electrified acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd .; and as Ketjen black, Ketjen Black EC and Ketjen Black EC- by Akzo Chemical Co.
Examples of 600DJ furnace black include Vulcan XC-72 manufactured by Cabot Corporation. These conductive carbon blacks can be used alone or in combination of two or more.

When the release film is required to have a transparency in the range of the total light transmittance of 40 to 60%, in addition to acetylene black, the rearrangement of the crystal proceeds and the film has a typical hollow shell structure. A method of adding a small amount of Ketjen Black is preferable because it exhibits antistatic properties.

As the organic resin constituting the antistatic layer in the present invention, various organic resins containing at least one selected from thermoplastic resins, thermosetting resins and fibrous resins can be used.

As the thermoplastic resin, a polyester resin,
Examples of thermosetting resins such as acrylic resins and polyvinyl resins include thermosetting acrylic resins, melamine resins, epoxy resins, and urethane resins, and examples of fibrous resins include nitrocellulose and acetylcellulose.

The antistatic layer in the present invention is formed by applying a coating liquid containing the above-mentioned conductive carbon black and an organic resin to a polyester film.

The coating liquid may be of an organic solvent type or an aqueous type. Further, a dispersant, an anti-settling agent, a cross-linking agent, a curing acceleration catalyst may be added to the coating liquid, and a surfactant may be appropriately added to the water-based coating liquid in order to prevent repelling of the film.

Examples of the method for dispersing the conductive carbon black in the coating liquid include a method using a combination of various ball mills, roll mills, stone mills, and high-speed grinders, and a method in which carbon black is already dispersed in a solvent and a dispersant. A method of mixing with an organic resin binder is exemplified.

The amount of the conductive carbon black to be added depends on the type of the carbon black, the dispersion method and the type of the organic resin, but is generally required to be 1 to 30% by weight in the antistatic layer. For applications requiring transparency in the range of the rate, antistatic properties can be exhibited by using Ketjen black in an amount of 1 to 10% by weight. The thickness of the antistatic layer is preferably from 0.1 to 5 μm, and particularly preferably 2 μm or less when transparency is required.

The antistatic layer can be formed by the same method as that for the release layer.

The antistatic layer formed by the above method must have a surface specific resistance of 5 × 10 ^{4 to} 5 × 10 ⁹ Ω / □ and a peeling charge of -5 to +5 kV. If the surface specific resistance exceeds 5 × 10 ⁹ Ω / □ or the peeling charge amount is less than −5 kV or exceeds +5 kV, the antistatic performance of the antistatic layer becomes insufficient. Further, the surface specific resistance value is 5 × 10 ⁴ Ω /
In order to make □, it is necessary to increase the amount of the conductive carbon black, which is industrially disadvantageous.

Since the release film of the present invention has excellent antistatic properties and can be peeled off with a moderate force, it can be used as a carrier film for forming a resin sheet or a film for protecting a resin sheet.

[0036]

The present invention will be described below in detail with reference to examples. The physical property values and characteristic values in the present invention were measured by the following methods.

(1) Peeling strength A polyester adhesive tape (Nitto 31B) is adhered to the release layer surface of the film and pressed with a 5 kg pressure roller, and then the peeling force (R _f0 ) between the release layer and the adhesive tape is pulled. It was measured with a testing machine.

(2) Residual Adhesion Rate JIS polyester adhesive tape (Nitto 31B)
Cold rolled stainless steel sheet (SUS3
04) was measured for the peeling force after application, and the result was taken as the basic adhesive force (f ₀ ). Next, the new polyester pressure-sensitive adhesive tape was pressed against the release layer surface of the sample film with a 5 kg pressure roller and maintained for 30 seconds, and then the pressure-sensitive adhesive tape was peeled off.
Then, the peeled polyester pressure-sensitive adhesive tape was stuck on the stainless steel plate, and the peeling force of the bonded portion was measured to obtain a residual adhesive force (f). From the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), a residual adhesive rate was determined using the following equation. Residual adhesion rate (%) = (f / f ₀ ) × 100

(3) Electrification (Evaluation method for peeling electrification) A polyester adhesive tape (Nitto 31B) was adhered to the release layer surface of the film, pressed with a 5 kg pressure roller and maintained at 70 ° C. for 20 hours. As shown in FIG. 1, the release film side was fixed downward, the polyester adhesive tape was peeled off at a speed of 500 mm / min, and the potential of the adhesive surface of the peeled polyester adhesive tape was measured from a distance of 3 cm from the adhesive surface. It measured and it was set as the peeling charge amount.

(4) Surface Specific Resistance Using a specific resistance measuring device manufactured by Takeda Riken Co., Ltd.
The surface resistivity after one minute at an applied voltage of 500 V was measured under the conditions of ° C and a measurement humidity of 65% RH and 45% RH.

(5) Total light transmittance The total light transmittance was measured using a haze meter (wavelength: 580 nm) manufactured by Nippon Seimitsu Optics with the antistatic layer side facing the light source.

Example 1 Addition reaction type silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd .; KS-778, solid content 30%)
100 parts by weight of a toluene solution) and 1 part by weight of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd .; PL-50T) are dissolved in toluene, and a toluene solution having a solid content of 3% by weight (release layer) (For coating). Further, 80 parts of a copolymerized polyester resin (solid content ratio, the same applies hereinafter) methylolated melamine resin (manufactured by Sumitomo Chemical Co., Ltd .; SUMIMAL M-4)
0W) 15 parts, a surfactant (NS-208. Manufactured by NOF CORPORATION).
5) After adjusting 5 parts to a 20% by weight aqueous solution, a conductive carbon black aqueous dispersion (W-356 manufactured by Lion Corporation) was used.
A) was added in an amount of 7% by weight in the antistatic layer to prepare a coating solution for the antistatic layer.

Then, 0.2 μm silicon oxide 0.1%
Is applied to a 25 μm-thick biaxially stretched polyethylene terephthalate film having a coating amount of 6 g / m ² (coating amount base), and is heated and dried at 150 ° C. for 1 minute and cured. An antistatic layer having a thickness of 1.0 μm was formed.

Subsequently, a coating liquid for forming a release layer was applied on the surface of the film opposite to the antistatic layer at a coating amount of 6 g / m ² (coating liquid amount base), and the coating liquid was applied at 140 ° C. for 30 seconds. Heat release drying and addition polymerization were carried out to produce a release film. Table 1 shows the performance of the release film.

[Example 2] Instead of the aqueous dispersion of conductive carbon black used in Example 1, SP manufactured by Mikuni Pigment Co., Ltd.
A release film was prepared in the same manner as in Example 1 except that Black AS-1193 was added so as to be 10% by weight in the antistatic layer to prepare a coating solution for the antistatic layer. Table 1 shows the performance of the release film.

Example 3 A coating liquid for an antistatic layer was prepared by using a polyurethane resin (Hydran AP-40 manufactured by Dainippon Ink Industries, Ltd.) instead of the copolymerized polyester used in Example 1. Produced a release film in the same manner as in Example 1. Table 1 shows the performance of the release film.

Example 4 A wax-based release agent (polyethylene wax / polyamide wax / carnauba wax = 1/1/1, solid content ratio) was used in place of the addition-reaction type silicone resin used in Example 1. A release film was prepared in the same manner as in Example 1 except that a release layer was formed by drying at 100 ° C. Table 1 shows the performance of the release film.

Example 5 A release film was prepared in the same manner as in Example 1, except that polyethylene-2,6-naphthalate was used instead of polyethylene terephthalate. Table 1 shows the performance of the release film.

Example 6 A release film was prepared in the same manner as in Example 3 except that the application of the coating liquid was changed in the order of the coating liquid for forming the release layer and the coating liquid for forming the antistatic layer. did. Table 1 shows the performance of the release film.

Comparative Example 1 A release film was prepared in the same manner as in Example 1 except that the antistatic layer was not provided. Table 1 shows the characteristics of the release film.

[0051]

[Table 1]

[0052]

According to the present invention, an adhesive film formed on a release layer when used for a carrier film for molding, such as an adhesive film or a resin sheet, is less charged during feeding or running. It is possible to provide a release film capable of peeling an adhesive film, a resin sheet, or the like with an appropriate force without causing a charging failure in the resin sheet or the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a facility for evaluating charging properties.

Claims (6)

[Claims] 1. A release film in which a release layer is provided on one side of a polyester film and an antistatic layer is provided on the other side, wherein the antistatic layer comprises an organic resin containing conductive carbon black. The antistatic layer has a surface specific resistance of 5 × 10 ^{4 to} 5 × 10 ⁹ Ω / □ and a peeling charge of −
A release film having a voltage of 5 to +5 kV. 2. The release film according to claim 1, wherein the organic resin is at least one selected from a thermoplastic resin, a thermosetting resin and a fibrous resin. 3. The release film according to claim 1, wherein the conductive carbon black is Ketjen black. 4. The polyester film is a polyethylene terephthalate film or polyethylene-2,6-
The release film according to any one of claims 1 to 3, which is a naphthalate film. 5. A carrier film for forming a resin sheet using the release film according to claim 1. 6. A resin sheet protecting film using the release film according to claim 1.