JPH0732042Y2 - Release sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a releasable sheet, and more specifically, an object thereof is to provide a releasable sheet excellent in strength, durability, releasability and the like.

(Prior Art and Problems Thereof) Conventionally, a release layer made of a silicon compound or the like is formed on the surface of a supporting substrate such as paper, plastic film, and textile fabric to form a releasable sheet, which is used to manufacture synthetic leather and film. Manufacturing,
It is known to be used for laminating adhesive materials and the like.

In the case of the above-mentioned conventional releasable sheet, in addition to the one that is discarded by one use, there is the one that is repeatedly used many times, and in the latter case, its repeated durability is required. In the case of these conventional releasable sheets, in many cases, a layer to which silicone oil or the like is added is formed on the surface of a supporting substrate, and particularly in applications where durability is required, reactive silicone is used. A crosslinking agent is added to the oil to crosslink the silicone oil and strengthen the release layer.

However, conventional reactive silicon compounds are often low in purity, and non-reactive silicone oil is contained in them, and reactive components also have various molecular weights. Even if it is crosslinked by the agent, many uncrosslinked substances are present in it. Therefore, when a film is formed on the release layer, a part of the silicone oil is transferred to the film side, and the adhesion between the films is impaired especially in the field where a large number of the above films are required to be laminated. There is a problem that is. Further, even if the conventional release sheet is a cross-linked type, it does not have sufficient flexibility, durability, etc., and the number of times it can be repeatedly used is low,
There is a problem that the cost is high in the process.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a novel releasable sheet having no transfer of silicon components and excellent in durability, releasability, flexibility and the like.

(Means for Solving Problems) The above object is achieved by the present invention described below.

That is, according to the present invention, a two-component curable polyurethane adhesive layer is formed on at least one surface of a synthetic fiber woven fabric, and a release layer composed of a reactive silicon compound and polyisocyanate is further formed thereon. Is a release sheet.

(Function) By forming a release layer composed of a reactive silicone compound having reactivity with an isocyanate group and polyisocyanate on a synthetic fiber woven fabric via a two-component polyurethane adhesive layer, the silicone compound is made into The release layer is cross-linked and fixed by isocyanate, and the release layer also reacts with the polyisocyanate component of the two-component adhesive, so that a release layer having no transfer of the silicon compound is formed, and the release layer is flexible and flexible. Since the releasable sheet obtained is excellent in durability and durability, it has excellent repetitive durability, flexibility and flexibility.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

The synthetic fiber woven fabric used as the supporting substrate in the present invention is a woven fabric which has been used in the conventional production of a releasable sheet, and is made of a polyamide, polyester, polypropylene fiber or the like having high durability against repeated use. Alternatively, a non-woven fabric is suitable.

The adhesive for forming the adhesive layer on the surface of the base material firmly adheres the release layer having releasability to the base material and also fixes the free reactive silicon compound in the release layer. In addition, a polyurethane adhesive, particularly a two-component polyurethane adhesive containing a polyol component and a polyisocyanate component as main components is used. Many such adhesives are commercially available, and any of them can be effectively used in the present invention. The amount of adhesive applied is 1 to 100 g / m in terms of solid content.
Sufficient adhesion can be achieved with about ² .

The reactive silicon compound that mainly characterizes the present invention is
A compound having reactivity with an isocyanate group, and preferable examples thereof include the following compounds.

(1) Amino-modified silicone oil (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to 20
0, m = 2-200, n = 2-200) (2) Epoxy modified silicone oil (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to 20
0, m = 2-200, n = 2-200) (3) Alcohol modified silicone oil (N = 1 to 200, R = lower alkyl) (4) Mercapto-modified silicone oil (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to 20
0, m = 2-200, n = 2-200) (N = 1 to 200, R = lower alkyl group) (5) Carboxyl modified silicone oil (Branch point = 2 to 3, R = lower alkyl group, 1 = 2 to 20
0, m = 2-200, n = 2-200) (N = 1 to 200, R = lower alkyl group) The silicon compound having a reactive organic functional group as described above is an example of a preferable compound in the present invention, and the present invention is not limited to these examples. Nonetheless, the above-exemplified compounds and other compounds are commercially available at present and are easily available from the market, and any of them can be used in the present invention.

As the organic polyisocyanate, any conventionally known organic polyisocyanate can be used, but preferred examples thereof include 4,4'-diphenylmethane diisocyanate (MDI), water-added MDI, isophorone diisocyanate and 1,3-xylylene diisocyanate. , 1,4-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, etc. A urethane prepolymer or the like obtained by reacting an isocyanate with a low molecular weight polyol or polyamine so as to form a terminal isocyanate can naturally be used.

The amount of the reactive silicon compound and polyisocyanate used as described above is a weight ratio of 30 to 70:70 to 30, and if the amount of the reactive silicon compound is too small, the releasability of the release layer is insufficient. On the other hand, if the amount is too large, it is difficult to prevent migration of the silicon component from the release layer, which is not preferable.

The method for forming the release layer on the adhesive layer on the synthetic fiber woven fabric is
A film is formed by applying a mixture of the above-mentioned reactive silicon compound and polyisocyanate on the surface of a release paper and drying it, while applying a two-component polyurethane adhesive on the surface of a synthetic fiber woven cloth, and the adhesive layer is completely formed. A method of adhering the release film to the surface of the adhesive layer before curing is suitable. The thickness of the release layer is about 3 to 100 μm.

The adhesive layer and the release layer may be formed on one side of the woven fabric as shown in the first illustration, or may be provided on both sides of the woven fabric as shown in the second illustration.

(Example) Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on weight.

Example 1 About 60 parts of the above-mentioned reactive silicon compound, 40 parts of isocyanate-based curing agent (Seika Bond UD-C, manufactured by Dainichiseika Kogyo Co., Ltd.), and 20 parts of toluene are added to a release paper having a polypropylene resin laminate / paper structure. After coating at a rate of 120 g / m ² and drying, a urethane resin film having a thickness of about 45 μm was formed.

On the other hand, urethane resin adhesive (Seika Bond U-524, resin solid content 60%, toluene solution, Dainichi Seika Kogyo Co., Ltd.)
100 parts, isocyanate-based curing agent (SEICABOND UD-C,
15 parts by Dainichi Seika Kogyo Co., Ltd. and 20 methyl ethyl ketone
Part of the blended liquid is applied to the surface of nylon fiber woven fabric (tent etc.) at a rate of 120 g / m ² and then dried, and immediately the above urethane resin film is laminated and aged at a temperature of 40 ° C for 5 to 7 days. The releasable sheet of the present invention having the illustrated construction was obtained.

Examples 2 to 5 In place of the reactive silicon compound used in Example 1, the following reactive silicon compounds were used, and the release sheet of the present invention was prepared using the respective resins in the same manner as in Example 1. Obtained.

Example 2 Example 3 Example 4 Example 5 Example 6 An adhesive layer was formed on both sides of the nylon woven fabric in the same manner as in Example 1 and release films were attached to each other to obtain a release sheet of the present invention having the structure shown in FIG.

Comparative Example 1 The same woven fabric as in Example 1 was coated with a compounded liquid containing a curing catalyst added to silicone oil (KS883, manufactured by Shin-Etsu Chemical Co., Ltd.) at a solid content of 50 g / m ² , and the mixture was heated at 100 ° C. for 10 minutes. After heat-curing for 1 minute, it was aged at 40 ° C. for 7 days to prepare a release sheet of Comparative Example.

Performance comparison Styrene butadiene rubber 50 parts Natural rubber (crepe) 50 parts Calcium carbonate (extrinsic pigment) 100 parts Spindle oil 5 parts Zinc oxide 5 parts Vulcanization accelerator 3 parts Sulfur 5 parts Carbon black 3 parts The meat was uniformly kneaded to form a sticky sheet having a thickness of 1 mm.

Two release sheets of each of the above-mentioned Examples and Comparative Examples were prepared, and the above-mentioned pressure-sensitive adhesive sheet was sandwiched between the release layers, and pressed by a hydraulic press machine (1) 80 ° C. × 2 Kg /
It was left pressed while being pressed under the conditions of cm ² × 24 hours and (2) 80 ° C. × 2 Kg / cm ² × 48 hours. The peel strength between this adhesive sheet and the releasable sheet is 25 ± using a Shopper type tester.
The peel strength was measured when measured at 2 ° C. and a pulling speed of 300 m / min. This operation was repeated 5 times
The average values obtained by repeating 10 times are shown in Table 1 below.

The above results indicate whether or not the silicone component of the release sheet migrates to the adhesive sheet, and the greater the peel strength, the greater the migration of the silicone component, which means that the durability is insufficient. ing.

Further, the sandwiched pressure-sensitive adhesive sheet was peeled off, and the siloxane bond on the surface was analyzed by infrared absorption spectrum.When the release sheet of the example was used, migration of silicon to the surface of the pressure-sensitive adhesive sheet was observed in all cases. I couldn't do it. On the other hand, in all Comparative Examples, migration of silicon was clearly observed.

The physical properties of the release sheets of Examples and Comparative Examples are shown in Table 2 below.

(Effects) As described above, the release sheet of the present invention is excellent not only in various strengths, but also in repeated durability because silicon does not migrate to the adhesive body.

[Brief description of drawings]

FIG. 1 and FIG. 2 are diagrams schematically illustrating a cross section of the release sheet of the present invention.

Claims (2)

[Scope of utility model registration request] 1. A two-component curable polyurethane adhesive layer is formed on at least one surface of a synthetic fiber woven fabric, and a release layer comprising a reactive silicon compound and polyisocyanate is further formed thereon. A characteristic release sheet. 2. The release sheet according to claim 1, wherein the weight ratio of the reactive silicon compound to the polyisocyanate is 30 to 70:70 to 30.