JP2000334885A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film for a separator of a label or self-adhesive tape extremely reduced in charge at the time of peeling, having good appearance over a long period of time and good in visibility. SOLUTION: In a release film wherein a metal layer is provided on at least the single surface of a plastic film and a release layer is provided on the upper surface of the metal layer, it is pref. that the release layer comprises a silicone resin and the metal layer comprises aluminum and the surface specific resistance value of at least the single surface of the release film is 1012 Ω/(square) or less and the surface resistance value of the surface having the metal layer and the release layer is 1010 Ω/(square) or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film suitably used as a separator for a label or an adhesive tape.

[0002]

2. Description of the Related Art Conventionally, a release film in which a silicone resin layer is provided on the surface of a plastic film, for example, a polyester film, a polyethylene film, a polypropylene film, or the like, and the silicone resin layer is a release layer, has been used as a pressure-sensitive adhesive separator or the like. It is used in various fields such as ceramic sheet manufacturing processes.

[0003] Such release films are specifically disclosed in Japanese Patent Publication No. 6-2393, Japanese Patent Application Laid-Open No. 60-141553, Japanese Patent Application Laid-Open No. Hei 3-231812, and Japanese Patent Application Publication No. 4-592.
No. 07, Japanese Patent Publication No. 6-2393, and the like.

[0004] However, the above-mentioned release film is disadvantageous in that since it is colorless and transparent, visibility is poor, and peeling-off charging is apt to occur when peeling off.

[0005] On the other hand, conventionally used aluminum vapor-deposited films have the drawback that when they are placed in a high-temperature and high-humidity atmosphere for a long period of time, the aluminum layer becomes aluminum hydroxide and becomes partially transparent. are doing.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, has a peeling force suitable for mold release, has good visibility, and has a reduced appearance and a charge at the time of peeling. It is an object of the present invention to provide a release film having a small amount of heat.

[0007]

The object of the present invention can be attained by a release film having a metal layer on at least one surface of a plastic film and a release layer on the upper surface of the metal layer.

In the release film of the present invention, in particular, the release layer is made of a silicone resin, the metal layer is made of aluminum, and the surface resistivity of at least one surface is 10 ¹² Ω / □ or less. The surface having the metal layer and the release layer preferably has a surface resistivity of 10 ¹⁰ Ω / □ or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

Examples of the plastic film used in the present invention include synthetic polymer films (including sheets) such as a polypropylene film, a polyester film, and a nylon film.
Among them, polyethylene terephthalate film having excellent heat resistance and surface properties, polyethylene-2,6
A naphthalate film, a polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate film, particularly a biaxially stretched polyethylene terephthalate film excellent in mechanical strength and dimensional stability; Biaxially oriented polyethylene-2,6-naphthalate film and biaxially oriented polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate film are preferred.

The above-mentioned plastic film may be one produced by a conventional method, particularly a biaxially oriented polyethylene terephthalate film, a biaxially oriented polyethylene-2,6-
Naphthalate film, biaxially oriented polyethylene-α, β
The film thickness of the -bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate film is determined from the viewpoints of mechanical properties, dimensional stability, heat resistance, and price.
Preferably it is 4-350 μm, more preferably 10 μm.
〜100 μm.

In the release film of the present invention, a metal layer is provided on at least one surface of the plastic film, and a release layer is provided on the upper surface of the metal layer.

The metal layer is made of, for example, aluminum,
It is preferably made of a metal such as tin, zinc, or copper, and is particularly preferably made of aluminum which is inexpensive, has excellent appearance, and is generally used industrially.

As a method of providing a metal layer on a plastic film, there are methods such as vacuum deposition and plating, but from the viewpoint of cost and workability, a method by vacuum deposition is preferably used. As the above vacuum evaporation method, heating evaporation,
Known techniques such as sputtering and ion plating can be applied. Industrially, a continuous winding type is usually employed, but a single-wafer type is also possible. The deposition thickness can be arbitrarily set in the required characteristics, but is not particularly limited as long as it has sufficient light reflectance and surface gloss. The deposition thickness is generally 50 to 10
00 Angstroms, preferably 200-600 Angstroms.

Examples of the release layer provided on the upper surface of the metal layer include a coating layer made of a silicone resin, an acrylic silicone resin, a fluorine resin, a melamine resin, and the like. Excellent peelability of
A release layer containing a silicone resin as a main component, which is inexpensive, is preferable. In addition, by providing a resin coating mainly composed of a silicone resin layer as a release layer on the upper surface of a metal layer, especially an aluminum layer, the effect of preventing the disappearance of the aluminum layer, that is, the deterioration to aluminum hydroxide, is excellent.

The silicone resin used for the release layer in the present invention is not particularly limited, but the following formula (1)

[0017]

Embedded image (Wherein, R 1 is a methyl group, R 2 is a C 4-15 carbon atom)
An alkyl group or an ester group, a ketone group, an alkyl group or an aralkyl group having 2 to 15 carbon atoms having a hydroxyl group,
Vi represents a vinyl group. The silicone resin containing a polyorganosiloxane having a structure represented by the formula (1) as a main component is preferable in that the effects of the present invention can be made more remarkable.

The above silicone resin is subjected to an addition reaction between a polyorganosiloxane represented by the above formula (1) and an organohydrogenpolysiloxane in the presence of a platinum catalyst represented by chloroplatinic acid, It can be obtained by forming a crosslinked structure of silicone.

The thickness of the silicone resin layer as the release layer is preferably 0.05 to 0.5 μm in terms of the thickness after drying.
m, more preferably in the range of 0.1 to 0.3 μm.

In the present invention, the method of forming a release layer made of a silicone resin or the like on the metal layer is not particularly limited. For example, aromatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, n-hexane, n-hexane -Direct gravure using a coating agent in which a silicone resin is dissolved at a concentration of 4 to 18% by weight in an organic solvent such as an aliphatic hydrocarbon such as heptane, a halogenated hydrocarbon such as perchloroethylene, ethyl acetate, or methyl vinyl ketone. It can be formed by coating with a coater, a microgravure coater, a reverse gravure coater, a direct kiss coater, a reverse kiss coater, a comma coater, a die coater, a bar-rod type coating device, or the like. Among them, it is preferable to use a microgravure coater, a direct kiss coater, or a reverse kiss coater, because the uniformity of the thickness of the release layer is good and the occurrence of coating unevenness is small.

The drying and curing (thermal curing, ultraviolet curing, etc.) of the silicone resin coating film can be performed individually or simultaneously. When drying and curing are performed at the same time, it depends on the heat resistance (thermal dimensional stability) of the plastic film.
° C, more preferably in the temperature range of 120 ° C to 180 ° C,
Heating is preferably performed for 15 seconds or more, more preferably 30 seconds or more.

The specific structure of the release film of the present invention is as follows. (1) A release film in which a metal layer and a release layer are provided on the metal layer only on one side of the plastic film. (2) A release film in which a metal layer and a release layer are provided on only one side of the plastic film, and a silicone resin layer is provided on the other side of the plastic film. (3) A release film in which a metal layer and a release layer are provided on one side of the plastic film, and only the metal layer is provided on the other side. (4) A release film in which a metal layer and a release layer are provided on the metal layer on both surfaces of the plastic film.

Of the above-mentioned constitutions (1) to (4), the constitution (1) is particularly desirable in that the metal layer is not shaved when the plastic film is transported in each step and the transportability is excellent.

Also, at least one surface of the release film of the present invention, which is not necessarily the surface on which the release layer is provided on the upper surface of the metal layer, is at least the surface resistivity value of either surface of the plastic film. In the point that the generation of static electricity at the time of peeling when used as a separator and the sticking due to the static electricity at the time of peeling of the film etc. attached to the separator are more prevented, and the handling workability is better,
It is preferably at most 10 ¹² Ω / □, more preferably at most 10 ¹⁰ Ω / □, even more preferably at most 10 ⁵ Ω / □.

Further, it is preferable that the surface having the release layer on the upper surface of the metal layer has a surface resistivity of 10 ¹⁰ Ω / □ or less.

In the release film of the present invention, in order to prevent the metal layer made of aluminum or the like from disappearing by oxidation, the thickness of the silicone resin layer should be 3.0 k in terms of fluorescent X-ray intensity.
It is preferably at least cps. Further, in order to prevent set-off of the silicone resin layer, the thickness of the silicone resin layer is preferably 6.0 kcps or less in terms of fluorescent X-ray intensity.

The release film of the present invention is suitably used as a separator such as a label or an adhesive tape.

[0028]

The present invention will be described in more detail with reference to the following examples. The measurement and evaluation of each property in the examples are performed by the following methods.

(1) Releasability Film and polyester adhesive film (Nitto Denko 31)
B adhesive tape: 25 μm thick, 18 mm width) and bonded together by pressing with a 5 kg roller, and after leaving for 20 hours in an atmosphere of a temperature of 20 ° C. and a humidity of 65% RH, 180
を Peel strength is 300mm with a tensile tester.
/ Min.

When the peel strength is 20 g or less, the releasability is good. In the table, the meanings of ○, Δ and X are as follows.

：: Peel strength less than 6 g / 18 mm width Δ: Peel strength is 6 to 20 g / 18 mm width X: Peel strength exceeding 20 g / 18 mm width.

(2) Surface resistivity The surface resistivity was measured using MCPTESTER (manufactured by Mitsubishi Yuka Co., Ltd.) for 1 hour in an atmosphere at a temperature of 20 ° C. and a humidity of 65% RH.

When the surface resistivity is 10 ¹² Ω / □ or less, the workability at the time of peeling is improved. In particular, when the surface resistivity is 10 ¹⁰ Ω / □ or less, the charge at the time of peeling can be made almost zero.
Workability during peeling is greatly improved.

(3) Silicone resin layer rub-off The silicone resin layer was rubbed with a Gakushin type abrasion tester for 500 times.
g was applied, and the wear portion was worn back and forth by using No. 3 wire for 10 reciprocations. Then, a polyester adhesive film (31B adhesive tape manufactured by Nitto Denko: 25 μm thickness, 18 m) was applied to the wear portion.
m width) was bonded by pressing with a 5 kg roller, and the 180 ° peel strength after being left for 20 hours in an atmosphere at room temperature of 20 ° C. and a humidity of 65% RH was measured at a peeling speed of 300 mm / min using a tensile tester. did. The ratio of the peel strength obtained here to the peel strength obtained by the releasability of (1) above, “the peel strength after abrasion treatment / the untreated peel strength” is the rub-off value in the table, and is 15%. If it is below, it can be said that the rub-off is good.

(4) Moisture resistance life of aluminum layer The appearance after standing for one month in an atmosphere at a temperature of 40 ° C. and a humidity of 65% RH was visually evaluated. If there is no part where the aluminum layer disappears colorless and transparent, it can be said that the moisture resistance life is good.

In the table, 場合 indicates that the aluminum layer did not have a colorless and transparent portion disappeared by oxidation, and X indicates that it had disappeared and had a colorless and transparent portion.

(5) Visibility In the table, ○ indicates that the film was colored, and X indicates that the film was colorless and transparent.

(6) X-ray fluorescence intensity The intensity of silicon element is measured by the following X-ray fluorescence method.

A release film having a predetermined size (50 m in diameter)
m), and the silicon element intensity A on the release surface side is counted using a fluorescent X-ray apparatus under the following conditions. Next, after removing the silicone-based resin film on the surface with sandpaper, washing and drying with methyl ethyl ketone, the silicon element strength B is counted under the same condition method as described above.

The silicon element strength A thus obtained
The value obtained by subtracting the silicon element strength B from the above was defined as the silicon element strength (unit: KCPS) of the silicone resin film.

Equipment name: Rigaku X-ray spectrometer RIX1000 X-ray tube: Horizontal Cr target Element code: SiO₆  Spectral crystal: LIP1 Slit: COARSE Primary filter: OUT Diaphragm: 30 mm Applied voltage, current (XG): 50 kv-50 mA PHA: 100-350 PEAK: 2θ / 144.520 deg. Time / 40 seconds BG1: 2θ / 143.000 deg. Time / 10 seconds BG2: 2θ / 146.100 deg. Time / 10 seconds (Example 1) Biaxially stretched polyester film having a thickness of 25 μm
One side of LUM "" Lumilar "S28" (manufactured by Toray Industries, Inc.)
(A side), using a continuous vacuum evaporation device, as a metal layer
Aluminum to a thickness of 500 angstroms
Was deposited. Put this deposited film in a 160 ° C oven
After heat treatment for 15 seconds, the following composition A
Gravure roll (#)
200, diagonal line type)
Dry and heat cure for 15 seconds with a bun, and make the A surface a release surface
A release film was obtained. Silicone of the obtained release film
Element strength of the resin layer by X-ray fluorescence was 4.5.
kcps.

The other surface of the release film is referred to as surface B, and the structure of each of the surfaces A and B is shown below. Also, in the following examples and comparative examples, the surface A is a release surface. The measurement results of physical properties are shown in Table 1. The releasability of the release surface, the surface resistivity, the rub-off, the moisture resistance life, and the visibility were all very good.

Side A: After depositing and heat-treating an aluminum layer,
A silicone resin layer is coated thereon. Side B: untreated. Composition A: “thermosetting silicone resin coating material” 1) KS774 4.6 parts by weight manufactured by Shin-Etsu Chemical 2) 0.05 parts by weight of PL-50T manufactured by Shin-Etsu Chemical 3) Toluene 100 parts by weight (Example 2) An aluminum layer was deposited and heat-treated on both sides in the same manner as in Example 1, and only one side was coated with a silicone resin layer in the same manner as in Example 1. The configuration of each surface is shown below.

Side A: After depositing and heat-treating an aluminum layer,
A silicone resin layer was coated thereon. Side B: Evaporation of only the aluminum layer, heat treatment. The physical property measurement results are shown in Table 1. The release properties of the release surface, surface resistivity, rub-off, moisture resistance life, and visibility are all the same. Very good.

Example 3 An aluminum layer was deposited and heat-treated on both sides in the same manner as in Example 1, and a silicone resin layer was coated on both sides in the same manner as in Example 1. The configuration of each surface is shown below.

Surface A: After depositing and heat-treating an aluminum layer,
A silicone resin layer was coated thereon. Surface B: An aluminum layer was deposited and heat-treated, and then a silicone resin layer was coated thereon. Table 1 shows the measurement results of physical properties. , Rub off, moisture resistance life and visibility are all very good.

Example 4 An aluminum layer was deposited and heat-treated on one side in the same manner as in Example 1, and a silicone resin layer was coated on both sides in the same manner as in Example 1. The configuration of each surface is shown below.

Surface A: After depositing and heat-treating an aluminum layer,
The silicone resin layer was coated thereon. Side B: Only the silicone resin layer was coated. The measurement results of the physical properties are shown in Table 1. The release properties of the release surface, the surface resistivity, the rub-off, the moisture resistance life, and the visibility were all extremely high. Good.

Comparative Example 1 An aluminum layer was vapor-deposited on one side and heat-treated in the same manner as in Example 1, and a silicone resin layer was coated on the other side in the same manner as in Example 1. The configuration of each surface is shown below.

Surface A: Coating only with silicone resin layer Surface B: Evaporation of only aluminum layer, heat treatment The results of physical properties measured are shown in Table 1. Although the releasability and visibility of the release surface were extremely good, both the rub-off and the surface resistivity were inferior to those of the release film of the present invention.

Comparative Example 2 A 25 μm thick biaxially stretched polyester film “Lumilar” S28 (manufactured by Toray Industries, Inc.) was provided on one surface with an antistatic layer having the following composition B as a gravure roll (# (200, oblique line type) and dried in an oven at 130 ° C. for 20 seconds.

Further, the back surface was coated with a silicone resin layer in the same manner as in Example 1. The configuration of each surface is shown below.

Surface A: Coating only with silicone resin layer Surface B: Coating only with antistatic layer The measurement results of physical properties are shown in Table 1. The rub-off of the release surface, the releasability, the surface resistivity and the visibility are all the same as those of the present invention. Inferior to the release film.

Composition B: “Antistatic layer composition” 1) 100 parts by weight of NR-121X manufactured by Colcoat 2) 800 parts by weight of MEK (methyl ethyl ketone) 3) 100 parts by weight of IPA (isopropyl alcohol) (Comparative Example 3) Comparative Example 2 An antistatic layer was coated in the same manner as in Example 1, and a silicone resin layer was further coated on the upper surface in the same manner as in Example 1. The configuration of each surface is shown below.

Surface A: coated with an antistatic layer and then coated with a silicone resin layer. Surface B: untreated. The results of measurement of physical properties are shown in Table 1. As shown in FIG. Very poor. Also, the surface specific resistance value of the release surface is inferior to the release film of the present invention.

[0056]

[Table 1]

[0057]

The release film of the present invention has the following effects due to the above constitution. (1) There is little peeling charge when the release film and the adhesive (sheet) are peeled off, and the work of removing the release film becomes good. (2) Since the transparency of the deposited metal such as aluminum due to oxidation can be prevented, the appearance is improved over a long period of time. (3) The visibility is improved by providing the metal layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 15/04 B32B 15/04 Z 15/20 15/20 27/00 27/00 D L 101 101 C09J 7 / 02 C09J 7/02 Z (72) Inventor Junzo Inagaki 1-33, Nagafushi, Mishima-shi, Shizuoka Pref. BA06 BA07 BA10A BA10C BA10D EH462 EH661 EJ082 EJ862 GB90 JG04 JK06 JL14C JN01 YY00 4J004 DA02 DA03 DA04 DA06 DB04

Claims (5)

[Claims] 1. A release film comprising a plastic film provided on at least one side with a metal layer and a release layer on the upper surface of the metal layer. 2. The release film according to claim 1, wherein the release layer comprises a silicone resin. 3. The method according to claim 1, wherein the metal layer is made of aluminum.
Or the release film according to 2. 4. The surface resistivity of at least one side is 10 ¹²
The release film according to any one of claims 1 to 3, which has an Ω / □ or less. 5. The release film according to claim 1, wherein the surface having the metal layer and the release layer has a surface resistivity of 10 ¹⁰ Ω / □ or less.