JPH064313B2 - Release film and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has excellent properties such as releasability, transparency, and suitability for adhesion on a non-releasing surface. The present invention relates to a mount, a film for so-called print lamination laminated on paper, a release film used as a base material for an adhesive tape, and a method for producing the release film.

[Prior Art] A release sheet or release film in which a coating layer made of a silicone resin is formed on a base material made of paper or a plastic film is used, for example, as a mount for a label or a tag, or
It is often used as a base material for adhesive tapes.

Furthermore, in recent years, a release film in which a coating layer made of a silicone resin is formed on a base material made of a stretched polypropylene resin film has been found to have transparency, mechanical strength, chemical resistance,
It has come to be used as a release film having excellent properties such as electric properties, waist strength, and surface smoothness.

Further, a release film using a base material made of a polyethylene film is a release film having excellent properties in transparency and chemical resistance, and a release film using a base material made of a low density polyethylene film is further used. , A release film having excellent properties in flexibility and tear resistance, and a release film utilizing a base material made of a high-density polyethylene film, particularly a release film having excellent properties in waist strength It is starting to be used as a film.

[Problems to be Solved by the Invention] However, a release film in which a silicone resin coated surface is formed on a substrate made of the above-mentioned thermoplastic synthetic resin film has excellent properties such as transparency and chemical resistance. However, due to the insufficient heat resistance of the thermoplastic synthetic resin film used as the base material, it is sufficient for curing the silicone resin coating layer in the step of forming the silicone resin coating layer. It cannot be heated, and the silicone resin coating layer is wound in an insufficiently cured state.

Therefore, the silicone resin in the under-cured silicone resin coating layer is transferred to the non-coated layer surface of the base film while the silicone resin coating layer is in the wound state after formation. As a result, when processing such as attaching another substrate to the non-releasing surface of the release film having the silicone resin coating layer, or printing on the non-releasing surface, In addition, defective adhesion or insufficient adhesion of printing ink may occur.

The transfer phenomenon of the silicone resin to the non-releasing surface in the release film having the silicone resin coating layer is
What is called "back slip", and when this "back slip" is severe, a decrease in peelability occurs on the silicone resin coating layer surface of the release film, and further,
It also leads to blocking.

Furthermore, in recent years, "back slip" of the silicone resin due to insufficient curing of the silicone resin coating layer
In order to prevent this, it is possible to use a silicone resin that can be cured at a low temperature, or to make the non-coated surface uneven to reduce the contact area between the non-coated surface and the silicone resin coating layer surface. It is done, for example,
Silicone resin that can be completely cured at a temperature that does not cause heat damage to the stretched polypropylene film or polyethylene film, etc., is the fact that it has not been obtained yet. There is another problem that the transparency of the synthetic resin film is reduced.

On the other hand, the first aspect of the present invention is a release film that does not have "backsiding" of a silicone resin and that also has excellent properties in transparency, and that the non-release surface has A release film having excellent properties such as adhesion suitability and printability, and the second invention is
Provided is a method for easily and surely obtaining the release film of the first invention.

[Means for Solving the Problems] The release film of the first invention is a base film made of a thermoplastic synthetic resin, and a coating made of vinylidene chloride resin formed on one surface of the base film. And a coating layer of silicone resin formed on the other surface of the base film.

The method for producing a release film according to the second aspect of the present invention includes a step of subjecting one surface of a base material film made of a thermoplastic synthetic resin to corona discharge treatment, and a step of forming an anchor coat layer on the corona discharge treated surface. A step of forming a coating layer of vinylidene chloride resin on the anchor coat layer surface, a step of corona discharge treatment on the other surface of the base film, and a coating layer of silicone resin on the corona discharge treatment surface And the step of forming a release film of the present invention.

In the present invention, as the base film in the release film, for example, a usual thermoplastic synthetic resin film such as a stretched polypropylene film, a polyethylene film or a polyester film is used.

The coating layer made of vinylidene chloride resin formed on one surface of the base film is made of a monomer copolymerizable with vinylidene chloride, such as vinyl chloride, acrylic acid ester, methacrylic acid ester, acrylonitrile, methacrylic acid. Copolymers of vinylidene chloride with vinyl compounds such as nitrile and vinyl acetate, acids such as acrylic acid, methacrylic acid, crotonic acid and itaconic acid, and monomers such as Na salts, Ka salts and ammonium salts of these acids. Is formed of a vinylidene chloride resin.

When the coating layer formed of vinylidene chloride resin is made of a resin having a vinylidene chloride component of less than 80% by weight, the performance of preventing the "backswing" phenomenon of the silicone resin in the release film decreases, and When the vinylidene chloride component is more than 95% by weight, the coating layer has poor film-forming properties and the obtained coating layer is not homogeneous. Therefore, the above-mentioned coating layer of vinylidene chloride resin is
It is preferably formed by a vinylidene chloride copolymer resin containing 80 to 95% by weight of a vinylidene chloride component and 20 to 5% by weight of a copolymerization component other than vinylidene chloride.

Further, the coating layer of the vinylidene chloride resin, a general additive used when forming a normal coating layer of vinylidene chloride resin, for example, an anti-blocking agent,
It goes without saying that a lubricant, an antistatic agent and the like can be contained as appropriate.

An anti-blocking agent such as silica, talc, mica, calcium carbonate, barium sulfate, or other inorganic fine particles in the coating layer of vinylidene chloride resin, polystyrene,
The inclusion of an anti-blocking agent composed of organic fine particles such as melamine resin prevents the coating layer from blocking during the formation of a coating layer of vinylidene chloride resin, and imparts slipperiness in the coating layer. It is advantageous that the anti-blocking property for the surface of the silicone resin layer formed on the other surface and the effect of preventing the transfer of the silicone resin from the silicone resin layer can be further improved.

The thickness of the coating layer of vinylidene chloride resin is preferably thin from the viewpoint of the transparency of the release film to be obtained, for example, coating with a vinylidene chloride resin containing an anti-blocking agent. In the case of a coating layer, if the coating amount is too small, it becomes difficult to obtain the effect of the anti-blocking agent, and therefore, usually 0.01 to 0.5 parts by weight of the anti-blocking agent with respect to 100 parts by weight of the vinylidene chloride resin. It is preferable that the coating liquid contains 0.5 to 8.0 g (resin component) / m ² of the coating liquid.

[Examples] Specific configurations of the release film of the present invention and a method for producing the same will be described below with reference to Examples.

Example 1 A 20μ thick biaxially oriented polypropylene film [Honshu Paper Co., Ltd .: Alphan PY-101 # 20] having a corona discharge treatment on one side was used as a substrate film. An isocyanate resin (Nihon Polyurethane Co., Ltd .: Coronate L) diluted with ethyl acetate was applied to the corona discharge treated surface using a gravure coater, and an anchor of 0.3 g (solid component) / m ² was applied. A coat layer was formed.

Then, 2.5 g (solid component) / m ^{2 of} vinylidene chloride resin coating agent having the following composition was applied to the surface of the anchor coat layer.
After coating and drying at a ratio of 1, the mixture was aged in a wound state at 40 ° C. for 2 days to measure the crystallization of the vinylidene chloride resin in the coating layer.

Composition of coating agent Vinylidene chloride resin emulsion (Kureha Chemical Co., Ltd .: DO-821-S) Solid content: 100 parts by weight Finely powdered silica (Fuji Devison Co., Ltd .: Cyloid # 244): 0.3 part by weight Then, the biaxially oriented polypropylene film having a coating layer of the above-mentioned wound vinylidene chloride resin is unwound, and the other surface of the film (non-coating layer surface)
Corona discharge treatment is applied to the surface so that the surface has a wetting index of 40 dynes or more, and immediately, a silicone resin coating solution is applied at a rate of 0.2 g (resin component) / m ² and wound up. , Leave it at room temperature for 24 hours and then rewind,
A release film [I] as an example of the present invention was sampled.

As the silicone resin coating liquid, a 30% by weight resin component silicone resin liquid [Shin-Etsu Chemical Co., Ltd .: KS-774] was used.
-Diluted with heptane, to which 3% by weight of the curing agent (PL-4) based on the silicone resin component and 0.2% by weight of finely powdered silica (Fuji Devison Co., Ltd.) based on the silicone resin component : Syroid # 978) was used.

Example 2 A 100 μm-thick low-density polyethylene film [Honshu Paper Co., Ltd .: Tufflap PM-102 # 100] having a corona discharge treatment on one side was used as a base film, and the following Example 1 was used. By performing the same steps as the corresponding steps in Example 1, a release film [II] as an example of the present invention was sampled.

Comparative Example 1 A 20 μ thick biaxially oriented polypropylene film [Honshu Paper Co., Ltd .: Alfan PY-101 # 20] having a corona discharge treatment on one side was used as a base film, and The same coating liquid as the silicone resin coating liquid used in Example 1 was applied to the corona discharge treated surface by 0.2
It was coated at a ratio of g (resin component) / m ² and wound up, left at room temperature for 24 hours and then rewound, and a release film [III] for comparison was sampled.

Comparative Example 2 A 20 μm-thick biaxially oriented polypropylene film having a corona discharge treatment on one side [Honshu Paper Co., Ltd .: Alfan PY-101 # 20] was used as a base film, and The same coating liquid as the silicone resin coating liquid used in Example 1 was applied to the corona discharge treated surface by 0.2
It is coated at a ratio of g (resin component) / m ² , and subsequently the uncoated layer surface of the base film is subjected to corona discharge treatment so that the surface has a wetting index of 40 dynes or more and then wound. The film was taken, allowed to stand at room temperature for 24 hours, rewound, and a release film [IV] for comparison was sampled.

The corona discharge treatment on the surface of the non-coated layer of the base film in this comparative example is for improving the adhesion suitability of the surface of the non-coated layer of the base film.

Comparative Example 3 A 100 μm-thick low density polyethylene film [Honshu Paper Co., Ltd .: Toughlap PM-102 # 100] having a corona discharge treatment on one surface was used as a base film, and corona discharge was applied to the base film. On the treated surface, the same coating liquid as the silicone resin coating liquid used in Example 1 was used.
Coated at a rate of 0.2 g (resin component) / m ² and wound up,
This was left at room temperature for 24 hours and then rewound, and a release film [V] for comparison was sampled.

[Experiment] Various physical properties of the samples obtained in Examples 1 to 2 and Comparative Examples 1 to 3 were measured.

The results are shown in Table 1.

The methods for measuring each physical property of the sample are as follows.

1) Haze (%) Total haze value measured in accordance with JIS B6718 using a digital haze meter NDH-20D [Nippon Denshoku Industries Co., Ltd.].

2) Peel force (g / 50mm) A pressure-sensitive adhesive [Toyo Ink Co., Ltd .: BPS-8170] was applied to the silicone resin coating layer surface of the release film to a thickness of 100μ, including a solvent, at 100 ° C, Let it dry for 3 minutes,
Further, 50 g / m ² of high-quality paper was attached to the surface coated with the pressure-sensitive adhesive and left in an atmosphere of 20 ° C. and 65% RH for 24 hours to obtain a laminate of a release film and high-quality paper. After that, the peel resistance between the silicone resin coating layer surface and the pressure-sensitive adhesive layer of the obtained laminate was measured at a pulling speed of 0.3 m / min.

3) Residual Adhesion Rate (%) Adhesive tape (Nitto 31B) was attached to the silicone resin coating layer surface of the release film and adhered with a rubber roll, then at 70 ° C with a load of 25g / cm ² applied. After leaving it for 20 hours, peel off the adhesive tape from the release film, stick it on the polishing surface of the stainless steel plate as it is, and leave it at room temperature for 1 hour, then peel it off at 180 degrees between the stainless steel plate and the adhesive tape. , The adhesive force (A) between the stainless steel plate and the adhesive tape obtained by carrying out at a pulling speed of 40 mm / min, and by attaching the adhesive tape (Nitto 31B) to the Teflon sheet,
After sticking with a rubber roll, leave it at 70 ° C for 20 hours with a load of 25g / cm ² applied, peel off the adhesive tape from the Teflon sheet, and stick it to the polished surface of the stainless steel plate at room temperature for 1 hour. After leaving for a period of time, the adhesive strength (B) between the stainless steel plate and the adhesive tape obtained by performing 180 ° peeling between the stainless steel plate and the adhesive tape at a pulling speed of 40 mm / min. , The numerical value measured and displayed as the ratio between the two (A / B) x 100.

The residual adhesion ratio measures the protective performance of the release surface of the release film against the adhesiveness of the adhesive tape.

4) Wetting of non-silicone resin coating layer surface Measured according to JIS K 6782.

5) State of "back wandering" to the non-silicone resin coating layer surface Write on the non-silicone resin coating layer surface of the release film with a felt-tip pen with oil-based ink, and check the degree of ink repelling at that time.・ ・ ・ Does not play at all or hardly △ △ ・ ・ ・ plays slightly × ・ ・ ・ ・ played well.

7) Adhesion of non-silicone resin coating layer Adhesive (Takelac A-369 / Takenate A-19: 10/1; Takeda Yakuhin Co., Ltd.) diluted with isopropyl alcohol was applied to the release film with non-silicone resin. After coating the layer surface at a rate of ² g (solid component) / m ² and drying, apply 50 g / m ² of high quality paper on the layer surface coated with the adhesive, leave it for 24 hours, and then release film When peeling between the high-quality paper and the high-quality paper with a fingertip, the adhesiveness of the surface of the non-silicone resin coating layer is judged according to the degree of peeling in the paper layer, and peels well in the paper layer. Things △ ・ ・ ・ ・ Somewhat good peeling in the paper layer × ・ ・ ・ ・ Incomplete peeling in the paper layer.

[Operation and Effect of the Invention] The release film of the present invention comprises a base film made of a thermoplastic synthetic resin, a coating layer of vinylidene chloride resin formed on one surface of the base film, and the above-mentioned base. A film formed of a coating layer of a silicone resin formed on the other surface of the material film, and having excellent properties as a base material film in terms of transparency and chemical resistance. When it receives a sufficient amount of heat to completely cure the coating layer of
Thermoplastic synthetic resin films having insufficient heat resistance are used.

Therefore, during the manufacturing process of the release film having the silicone resin coating layer, the release film winding step is performed before the silicone resin coating layer is completely cured. However, the release film of the present invention, since the non-silicone resin coating layer surface is formed of vinylidene chloride resin layer, even in this winding step, in the silicone resin coating layer in a state of insufficient curing The silicone resin does not transfer to the non-silicone resin coating layer surface, and the adhesiveness and printability on the non-releasing surface are extremely good. It has an excellent effect in processing suitability such as sticking or printing on the non-releasing surface.

In particular, the release film of the present invention does not prevent the "back slip" phenomenon of the silicone resin by making the surface of the substrate film uneven, and the release film has excellent transparency. Moreover, as described above, since the non-releasing surface has excellent adhesion suitability, the release film of the present invention is laminated on the printing surface of paper by both of these characteristics. In the application as a so-called film for print lamination, it exhibits extremely preferable properties.

In the release film manufacturing method of the second invention, the release film of the first invention having the above characteristics is
Easy and reliable.

Claims (2)

[Claims] 1. A base film made of a thermoplastic synthetic resin,
A coating layer made of vinylidene chloride resin formed on one surface of the base film, and a coating layer made of silicone resin formed on the other surface of the base film. Release film. 2. A substrate film made of a thermoplastic synthetic resin is subjected to corona discharge treatment on one surface thereof, an anchor coat layer is formed on the corona discharge treated surface, and then a vinylidene chloride resin is formed on the anchor coat layer surface. The coating film is formed by applying a corona discharge treatment to the other surface of the substrate film, and then a coating layer made of a silicone resin is formed on the corona discharge treatment surface. Method for producing mold film.