JPH1025698A - Production of release sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a release sheet with slight change in release performance with the lapse of time by coating a base material sheet with an addition reaction-type silicone followed by its curing and by coating the resultant cured coating surface with a specific polyorganosiloxane followed by its curing. SOLUTION: At least one side of a base material sheet such as a polyester film is first coated with an addition reaction-type silicone coating liquid which, in turn, is heat-treated and cured. Subsequently, the surface of the resultant cured coating film is further coated with a polyorganosiloxane bearing vinyl groups each directly bound to a silicon atom or higher alkenyl groups (e.g. methylvinyldimethylpolysiloxane) which is then heat-treated, thus obtaining the objective release sheet.

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, and more specifically, has good adhesion to a substrate and low-temperature curability at a temperature of 90.degree. The present invention relates to a method for producing a release sheet that has little performance release.

[0002]

2. Description of the Related Art Conventionally, addition-reaction silicones have been widely used because of their lower curing temperature and less migration of silicones to pressure-sensitive adhesives than condensation-reaction silicones. However, polyethylene terephthalate (hereinafter referred to as PET) has been widely used.
), Polyethylene (PE), and polypropylene (PP). In order to compensate for such a defect, a means has been taken to improve the adhesiveness by applying a corona treatment to the film substrate, but even when the corona treatment is applied, the adhesiveness of the silicone to the substrate is not sufficient. Hard to say. Therefore, a method of adding a specific adhesion improver such as a silane coupling agent to silicone, and a method of improving adhesion by using a specific cross-linking agent as a cross-linking agent have been proposed. Also, there is a problem that the curability of the silicone is reduced, and in the former case, the peeling becomes heavy,
In the latter case, there is a drawback that the separator is aged, that is, lightly peeled off when stored and aged over time in the state of being manufactured as a release sheet.

When the addition-reaction type silicone is applied to the above-mentioned thermoplastic resin substrate sheet, it is preferable to cure at a low temperature of 90 ° C. or lower in order to reduce the influence of heat on the substrate. In order to perform low-temperature curing, it is necessary to make Si-H groups excessive with respect to Si-vinyl groups in the silicone material. There is also the disadvantage of being significant.

[0004]

As described above, the conventional addition-reaction silicone has poor adhesion to film base materials such as PET, PE, PP, etc., and is intended to be cured at a low temperature of 90 ° C. or lower. In this case, there was a problem that light peeling was remarkable due to separator aging.

The present invention has been made to solve the above-mentioned problems, and has good adhesion to a film substrate and low-temperature curability of silicone at a temperature of 90 ° C. or less.
And, there is little light peeling by separator aging,
That is, it is an object of the present invention to provide a method for producing a release sheet that exhibits stable release performance even with time.

[0006]

In order to improve the low-temperature curability at a temperature of 90 ° C. or less, the present inventor has proposed that the Si-vinyl group in the addition-reacting silicone release agent be replaced with a Si-vinyl group.
Excessive presence of the H group is effective, and it has been found that if there is a large amount of Si—H groups remaining after the silicone release agent is cured, there is a problem that the peeling becomes heavy or the light peeling is remarkable with time. Further, they have found that the above problem can be solved by suppressing the function of the residual Si-H group after curing of the silicone, thereby completing the present invention.

That is, the method for producing a release sheet of the present invention comprises:
After coating and curing the addition-reaction silicone on at least one surface of the base sheet, a polyorganosiloxane having a vinyl group or a higher alkenyl group directly bonded to a silicon atom is coated and cured on the coated surface. .

Further, the polyorganosiloxane having a vinyl group or a higher alkenyl group is methylvinyl dimethylpolysiloxane or methyl higher alkenyl dimethylpolysiloxane.

[0009] The release sheet obtained by the production method of the present invention is obtained by applying and curing an addition reaction type silicone having an excess amount of Si-H groups relative to Si-vinyl groups on various substrates.
A polyorganosiloxane containing a vinyl group or a higher alkenyl group directly bonded to a silicon (Si) atom (hereinafter, appropriately referred to as a vinyl group-containing silicone) is applied to the silicone-coated surface, and the silicone is left after being cured. Since the amount of Si-H groups is smaller, the adhesion to the base material is good without deteriorating the excellent low-temperature curability of the addition-reaction type silicone having an excessive amount of Si-H groups, and the secular change of the peeling performance. It is possible to provide a release sheet having a small amount of.

[0010]

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

In the production method of the present invention, first, an addition-reaction type silicone is applied as a silicone release agent to at least one surface of a base sheet used as a release sheet, and is cured by reaction.

The base sheet used in the present invention includes 2
Kraft paper or high-quality paper having a basis weight of about 0 to 150 g / m ^2, a paper base material such as glassine paper, and a sheet obtained by laminating a polyolefin-based resin or the like on one or both sides with a thickness of 10 to 30 μm on these papers, Furthermore, thickness 10-20
A plastic film such as 0 μm of PE, PP, polyester, or polyamide can be used. Above all, it is made of a thermoplastic resin such as polyester having excellent properties as a base material, but having poor adhesion to a silicone release agent, or PP having low adhesion and heat resistance, high density or medium or low density PE. The effect of the present invention is remarkable when a plastic film is used as a base sheet.

The addition reaction type silicone which can be used in the present invention has excellent low-temperature curability as compared with the condensation reaction type silicone,
There is an advantage that transfer of silicone to the pressure-sensitive adhesive after heat curing is small, and that the residual adhesion rate is high. The addition reaction type silicone that can be used in the production method of the present invention is a commercially available product such as SRX211, SRX manufactured by Toray Dow Corning Silicone Co., Ltd.
X345, KS776A manufactured by Shin-Etsu Chemical Co., Ltd., TPR6701 manufactured by Toshiba Silicone Co., Ltd. may be used. Alternatively, the effect of the present invention is more remarkable when a Si-H group-containing polyorganosiloxane such as methyl hydrogen / dimethyl polysiloxane is added. If the method of adding a Si-H group-containing polyorganosiloxane to a commercially available addition reaction type silicone is adopted, more types of addition reaction type silicones, for example, SD7335, SD7328, SD7239, SD7 manufactured by Toray Dow Corning Silicone Co., Ltd.
223, SD7220, SP7248S and KS847, KS838, KS854, KS77 manufactured by Shin-Etsu Chemical Co., Ltd.
4, KNS305, KNS303, TPR6702, TPR6700, TPR6600 manufactured by Toshiba Silicone Co., Ltd.
TPR6601 or DK Q3 made by Dow Corning Asia
-202, Q3-240 and the like can be used.

When the addition type silicone is applied to the above-mentioned base sheet, a solution obtained by dissolving the silicone in an appropriate solvent is applied to one or both sides of the base material by a known means such as a Meyer bar or a roll coat. In this case, the coating amount of silicone is 10 to 50 g /
m ² , and preferably about 0.02 to 2.5 g / m ² in terms of silicone solid content. If the coating amount is less than 0.02 g / m ² in terms of silicone solid content, the curability of the polyorganosiloxane having a vinyl group or a higher alkenyl group directly bonded to a silicon atom to be applied in the next step will deteriorate, and
If it exceeds 5 g / m ² , the silicone-coated surface when the release sheet is wound into a roll tends to block with the back surface of the release sheet, and the peeling performance of the silicone-coated surface may decrease due to blocking. Prior to applying the silicone to the base sheet, a known surface treatment such as a mat treatment, a corona discharge treatment, and a plasma treatment may be applied to the application side surface of the base sheet in advance.

In the step of curing the silicone applied to the substrate sheet, as a curing means, curing by radiation irradiation can be employed in addition to heat curing. Curing may be performed by a known method according to the characteristics of the silicone used. Since the addition reaction type silicone used in the production method of the present invention has excellent low-temperature curability, it can be cured even at a low temperature of 90 ° C. or lower to form a favorable coating film.

In the present invention, after the silicone is cured by heat or the like as described above, in order to prevent the remaining Si-H groups from affecting the release performance, silicon is directly bonded to silicon atoms on the coating film forming surface. The applied polyorganosiloxane having a vinyl group or a higher alkenyl group is applied and cured.
Examples of the polyorganosiloxane having a vinyl group or a higher alkenyl group to be used herein include vinyl group-containing polyorganosiloxanes such as methylvinyl dimethylpolysiloxane, methylphenyl methylvinyl dimethylpolysiloxane, about 4 to 8 carbon atoms. Methylbutenyl dimethyl polysiloxane, methyl hexenyl dimethyl polysiloxane, methyl octenyl dimethyl polysiloxane, etc., which are polyorganosiloxanes having higher alkenyl groups of SH41
0, KE78VBS manufactured by Shin-Etsu Chemical Co., Ltd., TSE201 manufactured by Toshiba Silicone, PS255, PS manufactured by Chisso
H.264, PS288, and the like.

The coating of the silicone containing vinyl group etc.
It can be carried out by the same means as the application of the addition reaction type silicone. The coating amount is preferably about 0.05 to 1.0 g / m ^2, the effect of stabilization of the release performance is less than 0.05 g / m ² is insufficient, a vinyl group exceeds 1 g / m ² There is a possibility that the curing of the contained silicone becomes insufficient, and the peeling performance and the residual adhesion rate may be reduced.

At the time of applying the silicone containing a vinyl group or the like, an appropriate amount of a platinum catalyst or the like can be added as needed to improve curability.

[0019]

EXAMPLES The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to these examples.

Examples 1 to 6 A coating liquid of an addition reaction type silicone was prepared according to the formulation shown in Table 1 below, and polyethylene having a thickness of 25 μm was prepared so that the amount of adhesion (solid content) was 0.1 g / m ^2. Apply to terephthalate film surface, 80 ℃
For 30 seconds to cure. Thereafter, a coating solution of a vinyl group-containing silicone was prepared according to the formulation shown in Table 1 below.
Amount (solid content) of the addition-reaction silicone coating surface
The coating was applied at 0.1 g / m ² , heated at 80 ° C. for 30 seconds, and cured to produce a release sheet.

[0021]

[Table 1]

The silicone raw materials represented by the symbols in Table 1 and Table 2 below are those described below.

Addition reaction type silicone SRX211 (commercially available): Methyl hydrogen polysiloxane SH1107 manufactured by Dow Corning Silicone Toray Co., Ltd.
(Commercially available): Toray Dow Corning Silicone Co., Ltd.
Addition reaction type silicone SRX345 (commercially available): Dow Corning Silicone Co., Ltd. Addition reaction type silicone KS776A (commercially available): Shin-Etsu Chemical Co., Ltd. methyl hydrogen polysiloxane KF-99 (commercially available) : Platinum catalyst SRX212 (commercially available) manufactured by Shin-Etsu Chemical Co., Ltd .: Platinum catalyst PL-50T (commercially available) manufactured by Toray Dow Corning Silicone Co., Ltd .: Methyl vinyl dimethylpolysiloxane manufactured by Shin-Etsu Chemical Co., Ltd. PS255:
[Comparative Examples 1 to 3] Coating solution of addition reaction type silicone was prepared with the composition shown in Table 2 below, and the amount of adhesion (solid content) was 0.2 g /
m ² was applied to the surface of a 25 μm-thick polyethylene terephthalate film, heated at 80 ° C. for 60 seconds, and cured to produce a release sheet.

[0024]

[Table 2]

[Comparative Example 4] A release sheet was produced by performing only the application and curing of the addition-reaction-type silicone coating liquid without performing the coating and curing of the coating liquid of the vinyl group-containing silicone in Example 1 described above. did.

[Comparative Example 5] In the above-mentioned Example 1, the coating liquid (solid content) of the silicone liquid containing a vinyl group or the like was applied without applying the coating liquid of the addition reaction type silicone.
g / m ² was applied to the surface of a 25 μm-thick polyethylene terephthalate film, heated at 80 ° C. for 60 seconds, and cured to produce a release sheet.

Next, the curability and adhesiveness of the release sheets of Examples and Comparative Examples obtained by the above-mentioned production method were measured under the following conditions. In addition, a release sheet was prepared in which the curing conditions of the addition-reaction silicone were set at 100 ° C. for 30 seconds, and the same curability was evaluated. The results are shown in Table 3 below.
Shown in

Further, the obtained release sheet was heated at a temperature of 20
After leaving it for 5 days in an atmosphere at 50 ° C. and for 7 days in an atmosphere at a temperature of 50 ° C., it was subjected to the following peeling force and residual adhesion test. The results are shown in Table 3 below.

1) Curability The coated surface of the release sheet coated with silicone under predetermined conditions is strongly rubbed five times with a finger, and the cloudiness of the coated surface is observed. When there is very cloudiness, there are many smears (Sxx),
When there was fogging, there was smearing (Sx), when there was some fogging, there was slight smearing (S △), and when there was no fogging, good (良好). Set the curing condition of the paint to 80 ° C x 3
In addition to 0 seconds, both primary and secondary coatings are at 100 ° C x
The test was also performed under a curing condition of 30 seconds.

2) Adhesion The coated surface of the release sheet coated with silicone under predetermined conditions is strongly rubbed five times with a finger, and the state of the coated surface coming off is observed. There is a love off when there is paint falling off (Rx),
There is a slight love off when there is a slight drop of paint (R
Δ), good (塗料) when the paint did not fall off.

3) Peeling force SK Dyne 801B on one side of high quality paper having a basis weight of 54 g / m ²
(Manufactured by Soken Chemical Co., Ltd.) was applied with an applicator to a thickness of 130 μm, dried in an atmosphere of 100 ° C. for 2 minutes, and applied to the release sheets prepared in Examples and Comparative Examples.
After applying while pressing with a rubber roll of 40 kg weight, 40
℃ 50, width 150mm, length 150m
m and cut off with a tensile tester according to the method specified in JIS Z 0237 (adhesive tape / adhesive sheet test method) to read the resistance value.

4) Residual Adhesion Rate A polyester tape (31B manufactured by Nitto Denko Corporation) is adhered to the release sheet, heated at 70 ° C. for 20 hours under a load of 20 g / cm ² , and then peeled off. Peel off the sheet and stick it on a stainless steel plate. On the other hand, a tape obtained by adhering the tape to a stainless steel plate is used as a blank, and a resistance value at the time of peeling with a tensile tester is measured to calculate a percentage based on the blank. It is determined that the closer the value is to 100%, the better the residual adhesion ratio is.

[0033]

[Table 3]

As is clear from the results in Table 3, Examples 1 to 6 which are release sheets obtained by the production method of the present invention.
All have excellent curability at low temperature, excellent adhesion to the substrate, little change in release performance after aging, stable release performance, and a good residual adhesion rate. It was found that there was no decrease in the adhesive strength due to the transfer of the silicone to the pressure-sensitive adhesive. On the other hand, Comparative Examples 1 to 3 in which only the coating film of the addition reaction type silicone was formed
Has good curability at high temperature, but is inferior in low-temperature curability and adhesion to a PET film as a substrate sheet, and furthermore, a light release of the release performance over time in a high-temperature atmosphere is observed, Stable peeling performance was not obtained. Comparative Example 4 in which only the addition reaction type silicone coating film in Example 1 was formed had good adhesion to the PET film, but the peeling performance was heavy peeling, and was significantly lighter due to aging in a high-temperature atmosphere. Peeling was observed. Comparative Example 5 in which only the silicone film containing a vinyl group or the like in Example 1 was formed was inferior in curability and adhesion to the PET film as the base material, and the sheet coated with the adhesive was a release sheet. , And the residual adhesion rate was extremely low, which was not a level suitable for practical use.

[0035]

As described above, according to the method for producing a release sheet of the present invention, the adhesiveness to various substrates and the low-temperature curability are excellent, and the change in the release performance with time, particularly,
A release sheet with little light release can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location D06M 15/643 D06M 15/643 17/00 C09D 183/07 PMV // C09D 183/07 PMV D06M 17 / 00 Z B32B 27/00 L

Claims (2)

[Claims] 1. An addition reaction type silicone is applied to at least one surface of a substrate sheet and cured, and then a polyorganosiloxane having a vinyl group or a higher alkenyl group directly bonded to a silicon atom is applied to the application surface and cured. A method for producing a release sheet, comprising: 2. The method for producing a release sheet according to claim 1, wherein the polyorganosiloxane having a vinyl group or a higher alkenyl group is methylvinyl dimethylpolysiloxane.