JPH093219A - Production of mold release sheet or mold release film - Google Patents

Abstract

PURPOSE: To produce a mold release sheet or mold release film high in productivity, not enlarged in peel force with time and excellent in adhesivity between a mold-releasing agent and a base sheet or film. CONSTITUTION: A method for producing a mold release sheet or mold release film comprises arranging a base sheet or film (e.g. glassine paper, polyethylene terephthalate film) between mutually faced metal electrodes wherein a solid dielectric material is placed on at least one of the mutually faced surfaces, and subsequently applying an electric voltage between the metal electrodes under a pressure around the atmospheric pressure in a gas mixture comprising <=10vol.% of a fluorine gas-containing gas and the remaining amount of an inert gas to treat the base sheet or film with the generated discharged plasma. The treated mold release sheet or film has a contact angle of >=100 degree with water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a release sheet or a release film which is used for double-sided tapes, labels, processes, etc. and has one or both sides subjected to a release treatment.

[0002]

2. Description of the Related Art A release sheet or release film is used, for example, for protecting an adhesive layer of a double-sided tape or a label, and is peeled off from the surface when the double-sided tape or a label product is used and discarded. It is used for the step of temporarily forming the pressure-sensitive adhesive layer in the production of cast coat and various molded industrial products.

Conventionally, many release sheets or release films have a release agent coated on one side or both sides of a base sheet or film. As such a releasing agent, a polymer system containing a long chain alkyl group such as a cellulose derivative having an alkyl urethane group (Japanese Patent Publication No. 34-97).
No. 6) or a silicone polymer type such as thermosetting silicone (see, for example, Japanese Patent Application Laid-Open No. 2-191796) is used, and as a treatment method, a method of applying with a Meyer bar coater or a gravure coater is used. Has been taken.

Most of these releasing agents are used after being dissolved in a solvent, and in this case, there are problems in safety during processing and in working environment.

Since the long-chain alkyl group-containing polymer system has a heat resistant temperature of about 60 ° C., it cannot be applied with a high temperature when used for a process, so that the productivity is poor and it is used for a double-sided tape or a label. When it is used, the stability of the product over time (50 ° C) is difficult. Specifically, the release sheet or release film and the double-sided tape or label have a high level of peeling force, which makes them unusable. There's a problem.

The above silicone polymer type release agents are classified into addition polymerization type and condensation polymerization type according to the polymerization type. In addition polymerization type, low molecular weight silicone compounds bleed and migrate to the adhesive layer. There is a problem that the adhesive force is reduced, and the vinyl group of the unreacted monomer at the time of polymerization adsorbs electrostatically charged dust and the like, the releasability is reduced and the developing force is increased, The condensation polymerization type has a problem that productivity is poor because the curing time is long. Further, in any type, since a high temperature of 200 ° C. or higher is required for curing the silicone polymer, there is a problem that it becomes a large-scale curing furnace and takes up a large space.

As a method of releasing treatment, it has been proposed to fluorinate a substrate sheet or film by low-pressure plasma treatment using a fluorine-containing gas (Japanese Patent Laid-Open No. 165925/1985). (See the official gazette),
In this case, there is a problem that not only the equipment for maintaining the low pressure becomes complicated and expensive, but also it is not suitable for continuous production of the release sheet or the release film.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems, and its object is to achieve high productivity and prevent the release force from increasing over time, and to improve the release agent and the base sheet or It is an object of the present invention to provide a method for producing a release sheet or a release film having excellent adhesion to a film.

[0009]

According to the present invention, a substrate sheet or film is disposed between opposing metal electrodes having a solid dielectric material disposed on at least one opposing surface, and the volume is 10% by volume.
The base sheet or film is treated with discharge plasma generated by applying a voltage between the metal electrodes under a pressure near the atmospheric pressure of a mixed gas containing the following fluorine atom-containing gas and the balance of an inert gas. Thus, the contact angle to water is 100 degrees or more, which is a method for producing a release sheet or release film.

The type of the base sheet or film is not particularly limited as long as it has been conventionally used for a release sheet or a release film. For example, paper bases such as Clupak processed kraft paper (can be used both bleached and unbleached), general high-quality papers, glassine papers; film bases such as polyethylene, polypropylene, polyethylene terephthalate. In the above paper base, clay, talc, calcium carbonate, polyethylene, polyvinyl alcohol, polypropylene, paper strength agent, sizing agent, etc. may be used for surface modification.

Examples of the fluorine atom-containing gas include tetrafluoromethane (CF ₄ ), hexafluoroethane (C ₂ F ₆ ), hexafluoropropylene (C ₃ F ₆ ).
Fluorocarbons such as monochlorotrifluoromethane (CCl
Halogenated fluorocarbons such as F ₃ ); hexafluorosulfide (SF ₆ ) and the like, which are safe and do not generate harmful gas such as hydrogen fluoride in plasma, CF ₄ ,
C ₂ F ₆ , C ₃ F _{6 and the} like are particularly preferable. The fluorine atom-containing gas may be used alone or in combination.

As the above-mentioned inert gas, a rare gas such as helium, argon, neon, xenon, etc. or a nitrogen gas is used alone or in combination, but helium is a metastable state and has a long life, and a fluorine atom-containing gas. Is preferable because it is advantageous for exciting When a gas other than helium is used as the inert gas, in order to generate stable discharge plasma, organic vapor such as acetone and methanol, and hydrocarbon gas such as methane and ethane are mixed at a ratio of 2% by volume or less. Is preferred.

The mixing ratio of the fluorine atom-containing gas and the inert gas varies depending on the type of gas used, but when the relative concentration of the fluorine atom-containing gas becomes low, the degree of fluorination becomes insufficient, and the obtained mold release The contact angle of the sheet or the release film to water is easily less than 100 degrees, and when it becomes higher, arc discharge easily occurs, and when it becomes higher, discharge plasma does not occur even when a high voltage is applied,
The concentration of fluorine atom-containing gas is limited to 10% by volume or less,
It is preferably 0.1 to 10% by volume.

The pressure of the above mixed gas consisting of the fluorine atom-containing gas and the inert gas is limited to near atmospheric pressure,
Specifically, the pressure is 100 to 800 Torr, and the pressure adjustment is easy and the device is simple. Therefore, the pressure is 700 to 780.
Torr is preferred.

The release sheet or release film obtained in the present invention has a treated surface having a contact angle with water of 100 degrees or more. When the contact angle with water is less than 100 degrees, the releasability becomes insufficient.

The plasma processing step in the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a plasma processing apparatus used in the present invention. This apparatus comprises a power supply unit 1, a processing container 2, an upper metal electrode 4, and a lower metal electrode 5. The power supply unit 1 has a kHz
Although a power source having a frequency of a table can be applied, a frequency of 10 to 30 kHz is preferable for plasma treatment of a base sheet or film having low heat resistance, which has a small influence on the base.

The discharge plasma is generated by applying a voltage to the electrodes. When the electric field strength is low, the plasma density is low, so that it takes a long time to process the plasma. , So
It is preferable to apply a voltage so that the electric field strength is about 5 to 40 kV / cm.

The processing container 2 has a top surface 2a and a bottom surface 2b made of stainless steel, a side surface 2c made of polymethylmethacrylate, and an insulator 2d disposed between the top surface 2a and the upper electrode 4. The material of the processing container 2 is not limited to this, and all may be made of plastic or glass, or may be made of metal such as stainless steel or aluminum as long as it is insulated from the electrodes.

The processing container 2 serves as an inlet and an outlet of the substrate sheet or film to the processing container 2 so that the substrate sheet or film can be continuously plasma-processed.
Slits 12 and 12 are formed on both side surfaces thereof. Further, the slits 12 and 12 can be opened and closed so that the processing container 2 can be hermetically sealed if necessary.

A pair of opposed parallel plate type upper and lower metal electrodes 4 and 5 are arranged in the processing container 2.
In addition to the parallel plate type, the electrode arrangement structure may be a coaxial cylinder type, a cylinder facing flat plate type, a sphere facing flat plate type, a hyperboloid facing flat plate type, or a plurality of thin wires and flat plates. The material of the electrode is not particularly limited as long as it is a metal, and may be, for example, a multi-component metal such as stainless steel or brass, or a pure metal such as copper or aluminum. The surface treatment part 3 by discharge plasma is a space between the upper metal electrode 4 and the lower metal electrode 5 which face each other.

In the present invention, the solid dielectric is provided on at least one opposing surface of the metal electrode. In particular,
A solid dielectric 6 is provided on at least one opposing surface of the upper metal electrode 4 and the lower metal electrode 5. In the device of FIG. 1, the solid dielectric 6 is disposed on the lower metal electrode 5. The solid dielectric 6 needs to be disposed on the entire surface of the facing surface of the opposing electrodes. Even if a part of the facing surface is exposed, arc discharge occurs during plasma processing. Solid dielectric 6
1 does not necessarily have to be provided on the lower metal electrode 5 as shown in FIG. 1, and may be provided on the upper metal electrode 4 side or both electrodes.

Examples of the solid dielectric 6 include plastics such as polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET); simple metal oxides such as silica, alumina, titanium oxide and zirconium oxide, or compounds of these metals. Is mentioned. Solid dielectric 6
The shape of may be sheet-like or film-like. Regarding the thickness of the solid dielectric 6, if the thickness is thin, dielectric breakdown occurs at the time of applying a high voltage, and arc discharge easily occurs, and if it is thick, a high voltage is required to generate discharge plasma. A thickness of 4 mm is preferred.

In the apparatus of FIG. 1, the fluorine atom-containing gas is supplied to the surface treatment section 3 from the porous upper metal electrode 4 via the gas introduction pipe 8 and the inert gas is supplied from the gas introduction pipe 9 to the surface treatment unit 3. . Note that, in FIG. 1, the upper metal electrode 4 is a porous electrode having a gas passage inside thereof in order to uniformly supply the fluorine atom-containing gas. Thus, it is preferable that the upper metal electrode 4 also serves as a gas inlet and an electrode and has a porous structure in order to uniformly supply the fluorine atom-containing gas to the surface treatment part 3 and perform uniform treatment. However, if the fluorine atom-containing gas can be uniformly supplied to the surface-treated portion 3 by, for example, spraying a fluorine atom-containing gas at a high speed, the porous structure is not necessarily required.

The inert gas may be mixed with the fluorine atom-containing gas and introduced from the upper metal electrode 4 through the gas introduction pipe 8. However, in order to perform the plasma treatment with good uniformity, the fluorine atom may be introduced. It is preferable to introduce the contained gas from the upper metal electrode 4 and the inert gas from the gas introduction pipe 9. Further, as shown in FIG. 1, the distal end portion of the gas introducing pipe 9 inside the processing container 2 has a ring shape with a large number of holes, and gas is supplied into the processing container 2 through the holes. It is preferable because it can be uniformly treated.

Although not shown, the fluorine atom-containing gas and the inert gas are preferably supplied while the flow rate is controlled by a mass flow controller.

The procedure for plasma-treating a substrate sheet or film using the plasma treatment apparatus shown in FIG.
Although not particularly limited, for example, the following procedure is performed. After evacuating the air in the processing container 2, the flow rate of the fluorine atom-containing gas and the inert gas is then controlled by the mass flow controller, and the mixed gas having the above-mentioned predetermined concentration is supplied to the surface treatment unit 3, and the surface treatment unit 3 The pressure of the mixed gas of 3 is 100
~ 800 Torr Then, the slits 12, 12
Open the base sheet or film 7 and one slit 1
2 into the processing container 2 and the other slit 12 to the outside of the processing container 2 and a substrate sheet or film 7 continuously in the processing container 2 using a take-up roll (not shown). Allow to pass. At this time, the base sheet or film 7 is brought into contact with the solid dielectric 6 with the surface of the base sheet or film 7 to be subjected to plasma treatment facing the surface treatment section 3. Also, the base sheet or film 7
If it is desired to perform plasma treatment on both sides of the surface treatment section 3 without contacting the base sheet or film 7 with the solid dielectric 6,
It should be placed so that it floats inside. Then, a voltage is applied between the metal electrodes to generate discharge plasma, and the plasma is brought into contact with the surface of the substrate sheet or film 7 to be subjected to plasma treatment. Then, the base material sheet or film 7 is passed through the inside of the processing container 2 at a line speed at which the plasma is brought into contact with the base material sheet or film 7 for a necessary time, and plasma processing is performed.

The distance between the upper metal electrode 4 and the lower metal electrode 5 depends on the gas flow rate of the supplied fluorine atom-containing gas, the magnitude of the applied voltage, the material and thickness of the solid dielectric material, and the base sheet. Or, depending on the thickness of the film, etc., it is appropriately determined, but when the distance becomes small, the amount of unused fluorine atom-containing gas becomes inefficient, and when it becomes large,
Since the uniformity of gas in the electrode space tends to be impaired,
20 mm is preferable.

Excess fluorine atom-containing gas and inert gas are discharged from the gas outlet 10 of the processing container 2. Further, when the fluorine atom-containing gas and the inert gas are introduced into the processing container 2, it is preferable that the air remaining in the processing container 2 be exhausted from the exhaust port 11 in advance as described above. .

Further, in the above operation procedure, after the air in the processing container 2 is exhausted before the plasma processing,
Although the mixed gas having a predetermined concentration was supplied to the surface treatment section 3, the gas outlet 10 was supplied while the mixed gas having a predetermined concentration was supplied to the surface treatment section 3 for a certain time without exhausting the air in the processing container 2.
Alternatively, the gas in the processing container 2 may be exhausted from the exhaust port 11 to exchange the gas, and then the plasma processing may be performed.

[0030]

In the release sheet or release film of the present invention, the fluorine atom is distributed on the surface of the base sheet or film by the plasma treatment, and the surface energy of the base sheet or film is reduced. Adhesives, cast-coated products, industrial products, etc. are less likely to get wet on the surface, and the surface of the base sheet or film becomes releasable, so peeling of double-sided tapes, labels, cast-coated products, industrial products, etc. becomes lighter. .

Further, since the fluorine atoms are strongly bonded to the surface of the substrate sheet or film by the plasma treatment, the migration of fluorine atoms from the surface of the substrate sheet or film to the surface of the adhesive, cast coat product or industrial product. Without
The release force of the release sheet or release film obtained in the present invention does not change with time.

Further, the adhesive tape of the present invention is 100 to 8
Since it is manufactured by plasma treatment under a pressure of about 00 Torr near atmospheric pressure, there is no need for a device for maintaining a low pressure as a processing device, and unlike a conventional mold release processing device, a solvent type release agent is applied. After the work, a drying furnace for volatilizing and drying the solvent is not necessary, and a curing furnace other than the processing device is not necessary. The equipment is compact, the manufacturing is easy, and the productivity is high.

[0033]

Embodiments of the present invention will be described below. (Embodiment 1) The plasma processing apparatus shown in FIG. 1 [The processing container 2 is a cube of 500 mm × 500 mm × 500 mm. The upper and lower metal electrodes are 300 mm x 300 m
m of stainless steel (SUS304). On the surface of the upper metal electrode 4 facing the lower metal electrode 5, 1 mmφ holes are opened at 1 cm intervals. The distance between the electrodes is 5 mm, and the thickness of the solid dielectric 6 on the lower metal electrode 5 is 1 mm.
350 mm × 350 mm of polytetrafluoroethylene is provided. 〕It was used. First, tetrafluoromethane was introduced into the processing container 2 from the gas introduction pipe 8 at a flow rate of 100 sccm and helium gas at a flow rate of 9900 sccm into the processing container 2, and the gas was replaced with the atmospheric pressure of 760 Torr for 15 minutes.

The slits 12, 12 are opened, and the basis weight is 95 g /
m ² glassine paper (manufactured by Shin Oji Paper Co., Ltd., 3G-95-11
1-124, width 300 mm) 7 was arranged so as to pass through the inside of the processing container 2, and was arranged so as to face the surface treatment portion 3, and one surface thereof was brought into contact with the solid dielectric material 6.

Next, the flow rate of tetrafluoromethane was set to 10
After changing the sccm and helium gas flow rates to 990 sccm, a voltage of 15 kHz and a voltage of 6.2 kV was applied between the electrodes, and the glassine paper 7 was plasma-treated while moving at a running speed of 10 m / min to obtain a release sheet. .

Example 2 As a base sheet or film 7, instead of glassine paper, a polyethylene terephthalate film having a thickness of 25 μm (Lumirror # 2, manufactured by Toray Industries, Inc.) was used.
A release film was obtained in the same manner as in Example 1 except that 5) was used.

Comparative Example 1 Glassine paper (manufactured by Shin Oji Paper Co., Ltd., 3G-95-111-124, width 300 mm) having a basis weight of 95 g / m ² was used as a release sheet without treatment.

(Comparative Example 2) 25 μm thick polyethylene terephthalate film (Toray Industries, Inc., Lumirror # 25)
Was used as a release film without treatment.

(Comparative Example 3) A solventless silicone (manufactured by Shin-Etsu Chemical Co., Ltd., on one side of glassine paper (manufactured by Shin Oji Paper Co., Ltd., 3G-95-111-124, width 300 mm) having a basis weight of 95 g / m ² KNS-3100) was applied at 1.0 g / m ² and cured to obtain a release sheet.

(Comparative Example 4) Polyethylene terephthalate film having a thickness of 25 μm (Lumirror # 25, manufactured by Toray Industries, Inc.)
Solvent-free silicone (made by Shin-Etsu Chemical Co., Ltd., K
NS-3100) was applied at 0.7 g / m ² and cured to obtain a release film.

(Comparative Example 5) In gas replacement in Example 1, the flow rate of tetrafluoromethane was 1500 sccm,
Changing the flow rate of helium gas to 8500 sccm,
In the plasma treatment, the flow rate of tetrafluoromethane is 150 sccm and the flow rate of helium gas is 850 sc.
A release sheet was obtained in the same manner as in Example 1 except that the release sheet was changed to cm.

(Comparative Example 6) In gas replacement in Example 2, the flow rate of tetrafluoromethane was 1500 sccm,
Changing the flow rate of helium gas to 8500 sccm,
In the plasma treatment, the flow rate of tetrafluoromethane is 150 sccm and the flow rate of helium gas is 850 sc.
A release film was obtained in the same manner as in Example 2 except that the release film was changed to cm.

Evaluation of the release sheets or release films obtained in Evaluation Examples 1 and 2 and Comparative Examples 1 to 6, the contact angle peeling force and the heat-time peeling force were examined as follows, and the results are shown in Table 1. Indicated. Contact angle A water drop having a diameter of 2 mm is dropped at an interval of 2 mm on the plasma-treated surface or the release agent-treated surface of the release sheet or release film,
Contact angle measuring device (trade name CA-D) manufactured by Kyowa Interface Science Co., Ltd.
It measured using. Peeling force Release sheet or release film is made of stainless steel plate (thickness 1m
Nitto polyester tape # 3 on the plasma-treated surface or the release agent-treated surface of the release sheet or release film.
1B (manufactured by Nitto Denko Corporation) is attached, and JIS Z 023
According to the adhesive strength test of 7 (Adhesive tape / adhesive sheet test method), the 180-degree peeling-off adhesive strength was measured. Peeling force with heat with time Release sheet or release film is made of stainless steel plate (thickness 1m
Nitto polyester tape # 3 on the plasma-treated surface or the release agent-treated surface of the release sheet or release film.
1B (manufactured by Nitto Denko Corporation) is left in an atmosphere of 50 ° C. for 1 month, and then pulled by 180 degrees based on the adhesive strength test of JIS Z 0237 (adhesive tape / adhesive sheet test method) The peeling adhesion was measured.

[0044]

[Table 1]

[0045]

The constitution of the method for producing a release sheet or release film of the present invention is as described above, and the productivity is high and the peeling force does not increase with time, and the release agent and the base sheet or Provided is a method for producing a release sheet or a release film having excellent adhesion to a film.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a plasma processing apparatus.

[Explanation of symbols]

 1 Power Supply Section 2 Processing Container 3 Surface Treatment Section 4 Upper Metal Electrode 5 Lower Metal Electrode 6 Solid Dielectric 7 Base Material Sheet or Film 8 Gas Introducing Tube 9 Gas Introducing Tube 10 Gas Outlet 11 Exhaust 12 Slit

Claims (1)

[Claims] 1. A substrate sheet or film is disposed between opposing metal electrodes having a solid dielectric disposed on at least one opposing surface, and 10% by volume or less of a fluorine atom-containing gas and the balance are inert. The contact angle to water is 100 degrees or more by treating the base sheet or film with discharge plasma generated by applying a voltage between the metal electrodes under a pressure near the atmospheric pressure of a mixed gas of gases. The method for producing a release sheet or release film, comprising: