JP2846155B2 - Release film - Google Patents

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 having excellent non-transfer properties of a release agent, excellent flatness and releasability of a film, and particularly useful for the production of a substrate to be released. Related to shape film .

[0002]

2. Description of the Related Art As a release film, a plastic film obtained by applying a silicone resin to one or both surfaces of a plastic film has been widely used.

As the silicone resin, an addition polymerization or condensation polymerization type silicone resin which is thermally cured by using a curing catalyst is widely used. When the silicone resin is thermally cured, the reaction temperature is from 120 ° C. to 150 ° C. Action is required. If the curing reaction is insufficient, the phenomenon that the surface of the silicone resin coating adheres to the plastic surface on the back side or a part of the surface of the silicone resin coating is removed to the release layer side such as an adhesive ( (Transfer phenomenon) occurs, and there is a risk of deteriorating the performance of the release layer surface, for example, the pressure-sensitive adhesive surface.

One of the means for sufficiently promoting the thermosetting of the silicone resin is to reduce the thickness of the coating film. The thinner the thickness, the faster the coating of the silicone resin becomes. Metastases are reduced. However, as the thickness of the coating film is reduced, the release properties are reduced, and the peeling force (applying an adhesive tape to the silicone resin surface and measuring the peeling force) is increased. In particular, when the thickness of the coating film is less than 0.1 μm, the peeling force becomes abnormally large. For this reason, when a polyester film is used as a plastic film, the thickness of the silicone resin coating film has been proposed and used in the range of 0.1 μm to 1.0 μm.

[0005] Release films are also used in applications utilizing their flatness, for example, sheet molding of vinyl chloride, polyurethane, acrylic resin, etc., ceramic sheet molding, and molding of pressure-sensitive adhesive sheets. In molding a polyurethane resin sheet and a ceramic sheet, a high degree of flatness is required. Since the polyester film is excellent in flatness, it is particularly useful as Besufui Le beam such applications, to a releasing film such applications, it is necessary to form a flat coating film of the silicone resin . In order to make the silicone resin film flat, it is necessary to devise a method of applying the coating liquid uniformly and smoothly, but a means for reducing the thickness of the coating film is also effective. However, when the thickness of the coating film is less than 0.1 μm, the above-described problem occurs.

[0006]

The present inventor has conducted intensive studies to solve such a problem. As a result, when the thickness of the silicone resin coating film is reduced, especially when the thickness is less than 0.1 μm, the trouble is reduced. Aggregation of silicone resin occurs,
It has been found that coating unevenness occurs and a uniform thin film cannot be obtained, and furthermore, when this coating unevenness is eliminated, it is possible to form a thin film having excellent flatness and a thickness of less than 0.1 μm while maintaining a small peeling force. Have found that it is effective to modify the surface of the polyester film to have a surface wetting index of 46 dyn / cm or more, in other words, to increase the difference in surface tension between the polyester film and the silicone resin as much as possible. It was done.

[0007]

That is, in the present invention, the surface of a polyester film is free of isocyanate silane.
The surface wettability index is modified to 46 dyn / cm or more by coating with a hydrophilic resin or high-frequency treatment , and a thermosetting silicone resin layer is formed thereon with a thickness of 0.05 μm or more and less than 0.1 μm. It is a release film characterized by the following.

The polyester in the present invention is a crystalline linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol. Specifically, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate and the like can be exemplified. Further, a copolymer in which some of the constituent components of these polymers are substituted with other components, or a mixture of a small proportion of polyalkylene glycol and other resins such as nylon and polycarbonate may be used.

[0009] Such a polyester may contain a film property improving agent. For example, calcium carbonate
Arm, kaolin, silica, such as inorganic particles and polyester precipitated particles formed from the residue of the catalyst used in the synthesis reaction of such as alumina can be included as a sliding property improving agent.

[0010] The polyester film in the present invention comprises:
For example, it is manufactured by a conventionally known method. The thickness of the polyester film is not particularly limited.
About 250 μm. As the polyester film, a biaxially stretched polyester film, particularly a biaxially stretched polyethylene terephthalate film is preferable.

In the present invention, the surface of such a polyester film is made of a hydrophilic resin excluding isocyanate silane.
Modified by coating or high frequency treatment , surface wetting index is 4
It is necessary to be 6 dyn / cm or more. This isocyane
Examples of the hydrophilic resin excluding the silane include surfactants such as sodium alkyl sulfonate and sodium alkyl phosphate, silane coupling agents such as vinyl ethoxy silane and γ-glycidoxy propyl trimethoxy silane, and ethyl silane. And the like . These
The silicate compound is dissolved or mixed in a solvent or the like, and thinly applied to the polyester film surface . Alternatively, a method of subjecting a polyester film surface to a discharge treatment, for example, a corona treatment, can be exemplified .

In the present invention, the thermosetting silicone resin used for forming the release layer includes dimethylpolysiloxane, which has, for example, a vinyl group, a hydroxyl group, phenyl or the like at some or all of its terminals and side chains; And a silicone resin which undergoes a curing reaction using a catalyst such as tin oxide. As a solvent for the silicone resin, an organic solvent such as toluene, xylene, methyl ethyl ketone, or n-hexane is used. A silicone resin is dissolved or dispersed in this organic solvent to prepare a coating solution having a concentration of 0.5 to 5.0 w%.

The coating of the silicone resin coating solution is performed by a gravure coating method, a Meyer bar coating method, a kiss roll coating method, a slit reverse coating method, a reverse coating method, or the like. Usually, when coating silicone resin,
It is performed so that the coating amount is 5 to 15 g / m ² .

The thickness of the release layer is 0.05 μm or more and 0.1 μm.
m. If the thickness is 0.1 μm or more, the flatness is undesirably reduced.

[0015]

EXAMPLES The present invention will be further described below with reference to examples. The film characteristics in the examples were measured according to the following methods.

1. Surface wettability index According to JIS-K6768-1977, a wettability index reagent (manufactured by Wako Pure Chemical Industries, Ltd.) is used to flow the reagent on the surface of the sample film, and the wettability is determined.

2. Silicone film thickness The polyester film of the base material and the polyester film with improved wettability were used as blanks, and the surface of the release film coated with silicone resin was counted with fluorescent X-rays (Rigaku Electric mini X # 3577) to count the Si peak. Then, the silicone film thickness is measured.

3. Peeling force A sample film and a polyester adhesive tape (Nitto 31B) are stuck together and pressed with a 5 kg pressure roller.
The peeling force after standing for 20 hours is measured by a tensile tester.

4. Residual Adhesion Rate The peeling force after attaching a polyester pressure-sensitive adhesive tape (Nitto 31B) to a smooth stainless steel plate is measured and defined as a basic adhesive force. Further, the polyester adhesive tape is pressed against the silicone resin-coated surface of the sample film with a 5 kg pressure roller, left for 20 hours, and then the adhesive tape is removed. Then, the peeled adhesive tape is stuck on the above-mentioned smooth stainless steel plate, and the peeling force of the stuck portion is measured, and the measured value is defined as the residual adhesive force.
From these respective adhesive strengths, the residual adhesive ratio is determined from the following equation.

[0020]

## EQU1 ## Residual adhesion rate (%) = (Residual adhesive strength / Basic adhesive strength) × 100

5. Planarity Aluminum is vapor-deposited on the surface of the release film, and a surface photograph is taken at × 200 magnification with an optical microscope to evaluate the uniformity of the coating of the release agent.

[0022] [Example 1] molten polyethylene terephthalate ([eta] = 0.65)
Is extruded from a die, adhered and quenched while applying static electricity on a rotating cooling drum maintained at about 40 ° C. to obtain an unstretched film. Then, the film was stretched 3.6 times in the machine direction, and then γ An aqueous solution (2% solid content) containing 90 parts by weight of glycidoxypropylmethyldiethoxysilane and 10 parts by weight of a nonionic surfactant (polyoxyethylene nonylphenyl ether) was applied to about 5 g / m ² by a kiss coat method. . Next, the film was stretched 3.7 times in the transverse direction at 105 ° C., and heat-set at 235 ° C. to obtain an undercoating film having a thickness of 50 μm. When the surface wetting index of the film was measured, it was 48 dyn / cm .

The treated surface of the undercoating film is coated with an addition-polymerized silicone (TPR-67 by Toshiba Silicone Co., Ltd.).
00) of a 0.9% by weight toluene / methyl ethyl ketone (60:40) solution was applied to a Meyer bar at an application amount of 10%.
g / m ² and then dried at 140 ° C. to obtain a release film. Table 1 shows the performance of the release film.

[0024] one surface of Example 2 biaxially stretched polyethylene terephthalate film (thickness 50 [mu] m), subjected to corona treatment of 15W / m ² using a Kasuga Denki Co., Ltd. RF-power type HFS-401, surface wetting A polyester film having an index of 54 dyn / cm was obtained.

On a corona-treated surface, a 0.8% by weight toluene / methyl ethyl ketone (60:40) solution of polycondensation type silicone (Toshiba Silicone Co., Ltd., YSR-3022) was applied with a Meyer bar at an application amount of 10 g / m ^2, and then dried at 140 ° C. to obtain a release film. Table 1 shows the performance of the release film.

The surface wetting index of the film before the corona treatment was 41 dyn / cm .

[0027] one surface of Example 3 biaxially stretched polyethylene terephthalate film (thickness 50 [mu] m), partially hydrolyzed polysiloxane (Nippon Colcoat Co.: Colcoat P) and like a thickness 0.07μm after drying To give an undercoating film. The film has a surface wetting index of 58 dyn / cm.
Met.

A 0.5% by weight solution of addition-polymerized silicone (KS-847H, Shin-Etsu Chemical Co., Ltd., KS-847H) in toluene / methyl ethyl ketone (60:40) was applied to the treated surface with a Meyer bar at a coating amount of 10 g / m 2. Apply so that it becomes ² .
Subsequently, it was dried at 140 ° C. to obtain a release film. Table 1 shows the performance of the release film.

Incidentally, the surface wetting index of the film before the undercoating treatment was 41 dyn / cm .

[0030] [Comparative Example 1] on one surface of the biaxially stretched polyethylene terephthalate film (thickness 50 [mu] m), 1.0 wt% of toluene-methyl ethyl ketone polycondensation type silicone (Toshiba Silicone (Ltd.) YSR-3022) (60: 40) The solution was applied using a Meyer bar so that the application amount was 10 g / m ^2, and then dried at 140 ° C. to obtain a release film.
Table 1 shows the performance of the release film.

Incidentally, the surface wetting index of the film before the undercoating treatment was 41 dyn / cm .

[0032] [Comparative Example 2] on one surface of the same biaxially stretched polyethylene terephthalate film as in Comparative Example 1, 0.5 wt% of toluene-methyl ethyl ketone addition polymerization type silicone (Shin-Etsu Chemical (Co.) KS-847H) (60: 40) The solution was applied using a Meyer bar so that the application amount was 10 g / m ^2, and then dried at 140 ° C. to obtain a release film. Table 1 shows the performance of the release film.

[0033]

[Table 1]

[0034]

According to the present invention, it is possible to provide a release film having a higher degree of flatness, no transfer of a release agent, and excellent release properties. Is particularly useful for the production of flat release substrates.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B32B 1/00-35/00 C09J 7/02 C08J 7/04

Claims (1)

(57) [Claims] 1. The surface of a polyester film is isocyanate
Coating or high frequency treatment of hydrophilic resin excluding silane
A release film, characterized in that it is formed in the surface wetting index 46 dyn / cm or more modified, thickness less than that of the layer of heat-curable silicone resin or 0.05μm on 0.1μm by.