JPH0623345B2 - Method of manufacturing release sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a release sheet coated with a silicone resin, which is used for protecting an adhesive surface of an adhesive tape, an adhesive label or the like.

(Prior Art) Such a release sheet has different release levels depending on its use and purpose, and has a low release level (low adhesive strength) to heavy release (high adhesive strength).
Various things are used up to.

Conventionally, for control of peeling level, especially for heavy level, there are various methods such as changing the type of silicone resin according to the adhesive, increasing or decreasing the amount of release control agent or coating amount, and special coating method. Has been used.

However, all of these methods are not preferable from the viewpoint of productivity.

That is, changing the type and concentration of the coating liquid causes a time loss in operation and a loss of the remaining coating liquid. Further, in the case of silicone coating, most of them are gravure coating, and there is a large time loss of gravure roll replacement due to change in coating amount. Furthermore, the increase in the types of silicone resins and gravure rolls complicates their management, which is not preferable.

However, in reality, there is no other suitable method, so we are producing release sheets with various release levels by changing the type and coating amount of silicone resin.These release sheets are a variety of small lot brands. Since there are many cases, a lot of efforts are spent on how to reduce the loss.

(Problems to be Solved by the Invention) Accordingly, it is an object of the present invention to provide a method for producing a release sheet, which is capable of efficiently producing a release sheet having an arbitrary peeling force. .

(Means for Solving Problems) That is, according to the present invention, the silicone-coated surface and / or the non-coated surface of a release sheet coated with a silicone resin is subjected to a DC voltage (0.5 KV / mm 2KV / mm)
The present invention relates to a method for producing a release sheet, in which the release level of a silicone-coated surface is controlled by performing a charging treatment with.

Corona discharge treatment for plastic film, especially polyolefin film, is widely carried out for the purpose of improving the adhesiveness of the film, and corona discharge treatment for the purpose of imparting adhesiveness to other paper and non-adhesive resin Teflon etc. There is also an example.

However, when the corona discharge treatment was applied to the silicone coated surface, the release level suddenly became heavy and it could not be used as a release sheet, whereas the silicone coated release sheet was charged with a low DC voltage. In some cases, it was unexpected that the peel level could be controlled very easily.

In the present invention, the silicone coating surface and / or the non-coating surface should be charged with a DC voltage lower than the corona discharge inception voltage. When the applied voltage becomes high and the corona discharge starts, the peeling level suddenly becomes heavy, and the releasability is lost. In the present invention, it is necessary to perform the charging treatment at a voltage lower than the corona discharge inception voltage, but in consideration of the purpose of stabilizing the peeling force at a low level and the fact that the residual adhesion ratio is desired to be maintained at 90% or more, the treatment voltage is Is from 0.5
Must be between 2KV / mm.

In the present invention, the peeling level is mainly adjusted by the applied voltage, but other base material, surface property, permittivity, or other conditions such as charge-treated electrode material, shape and back roll material, electrode and sheet It can be arbitrarily adjusted by combining with conditions such as distance or seat speed.

Unlike the case of corona discharge treatment, the silicone resin surface of the release sheet charged in this way changes the peeling level, although the surface tension represented by the wet tension measurement and the contact angle measurement with water hardly rises. Of.

The type of the silicone resin used in the present invention is not particularly limited, and may be a usual addition polymerization type, condensation polymerization type, or a type of coating on paper or film, solvent type, water type, solventless type. Any of

There is no particular limitation on the base material such as paper and film,
Another layer may be present between the substrate and the silicone coated surface. Further, the surface of the base material may be subjected to some surface treatment.

In the present invention, the peeling level is usually adjusted by charging the silicone resin surface, but the peeling level can be adjusted by charging the non-silicone resin surface, that is, the back surface of the sheet. . However, in that case, the peeling level is about 30 to 70% lighter than the charging treatment from the silicone resin surface even if the charging treatment with the same strength is performed, and it is necessary to consider this point in the treatment. .

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.

The peeling force and the residual adhesion rate in the examples were measured by the following methods.

Peeling force A Adhesive tape (Nitto polyester tape 3
1B, hereinafter the same) was stuck, and a pressure of 20 g / cm ² was applied, and the mixture was left at 70 ° C for 1 day. After that, the peeling resistance was measured with a tensile strength tester at a peeling speed of 30 cm / min, and the peeling force A was measured.
And Unit: g / 30mm (2) Peeling force B Apply adhesive (Toyo Ink BPS-8170) to the silicone surface to a thickness of 70μ including solvent and dry at 100 ° C for 2 minutes, then apply to the adhesive application surface. 50 g / m ² of high quality paper (made by Kobayashi recording paper) was stuck and left at 20 ° C. and 65% RH for 1 day.
After that, the peeling resistance was measured by using a tensile strength tester at a peeling speed of 30 cm / min, and the peeling force B was obtained. Unit: g / 50mm (3) Residual adhesion rate 20g / by attaching adhesive tape to the surface of Teflon sheet
A pressure of cm ² was applied and the mixture was left at 70 ° C for 1 day. After that, remove the tape and attach it to a clean stainless steel plate (# 280), then
The adhesive force measured at a pulling speed of 30 cm / min after standing at 0 ° C. for 1 hour was defined as C (g / 30 mm). On the other hand, an adhesive tape was adhered to the silicone surface of the release sheet, and the adhesive force measured by the same method as in the case of being adhered to a Teflon sheet was D (g / 30).
mm) and the residual adhesion rate is expressed in units of 5% by the following formula.

In the examples, a high-voltage generator PK-20 manufactured by Kasuga Denki Co., Ltd. was used for charging, and the film was charged with a DC voltage. The electrode used was an edge-shaped edge with a thickness of 2 mm and a width of 500 mm. The distance between the electrode and the counter electrode roll was 2 mm.

The processing speed was 30 m / min.

Example 1 A surface tension of 40 dynes / cm was treated by a corona discharge treatment of 40.
μ biaxially oriented polypropylene film (Alphan PY10
2 # 40, manufactured by Honshu Paper Co., Ltd.) was coated with a silicone resin solution (I) having the following composition using a gravure roll so that the coating amount was 0.3 g / m ² in terms of solid content.

Silicone resin solution (I) Silicone (KS-774; manufactured by Shin-Etsu Silicone KK) 10 parts by weight Curing agent (PL-4; manufactured by Shin-Etsu Silicone KK) 0.15 Ethyl acetate 30 Toluene 60 After coating, pass the film through the dryer zone immediately. The solvent was dried and a heat treatment for curing the silicone was performed to produce a conventional releasable biaxially oriented polypropylene film. Then on the silicone side of the film
The charging treatment was performed under the conditions shown in the table.

After left at room temperature for 2 days, sampling was performed to measure the peeling force A and the residual adhesion rate. The results are shown in Table 1.

Example 2 A 64 g / m ² glassine paper (special SP; made by Honshu Paper Co., Ltd.) was coated with a silicone resin solution (II) having the following composition with a gravure roll so that the coating amount was 0.8 g / m ^{2 in} solid form. did.

Silicone resin solution (II) Silicone (KS-772; manufactured by Shin-Etsu Silicone KK) 20 Curing agent (PL-4; manufactured by Shin-Etsu Silicone KK) 0.3 Toluene 80 After coating, the same treatment as in Example 1 was applied, and release paper Was manufactured. Subsequently, the silicone surface or non-silicone surface of the release paper was charged under the conditions shown in Table 2.

After being left in a room at 30 ° C. for 2 days, sampling was performed to measure the peeling force B and the residual adhesion rate. The results are shown in Table 2.

(Effect of the invention) As is clear from the table, the release sheet of the present invention has a large peeling force when the surface thereof is subjected to a charging treatment at a DC voltage lower than that at the start of corona discharge. It is clear that

Therefore, according to the present invention, the peeling level can be adjusted very easily without impairing the productivity. Also, the method of the present invention has good reproducibility.

Claims (1)

[Claims] 1. A silicone-coated release sheet having a silicone-coated surface and / or a non-coated surface is charged with a direct current voltage (0.5 KV / mm to 2 KV / mm) lower than a corona discharge inception voltage, and then silicone-coated. A method for producing a release sheet for controlling the peeling level of a work surface.