JP4378179B2 - Release sheet and adhesive - Google Patents

Description

  The present invention relates to a release sheet and a pressure-sensitive adhesive body.

  Conventionally, the adhesive body which has a peeling sheet and an adhesive sheet is used for various uses. In particular, when used for medical purposes, it is generally sterilized. As such sterilization treatment, sterilization treatment using an autoclave, sterilization treatment using ethylene oxide gas (EOG sterilization), radiation sterilization treatment such as electron beam and γ-ray, and the like are performed.

However, when sterilizing in an autoclave, steam of high temperature and high pressure is used, so there is a problem that it is limited to materials that can withstand the harsh conditions. There was a problem.
For this reason, radiation sterilization has been actively performed in recent years.

  Incidentally, it is generally known that a silicone resin is used as a material constituting the release sheet (see, for example, Patent Document 1).

  When such a release sheet is irradiated with radiation for sterilization, there is a problem that it becomes difficult to release from the pressure-sensitive adhesive sheet and so-called heavy release occurs.

JP-A-6-336574 (Claims)

  As a result of intensive studies to solve the above problems, the present inventors have used a release sheet that is unlikely to undergo heavy release even when irradiated with radiation, particularly an electron beam. It has been found that an increase in peeling force (heavy peeling) of the release sheet can be effectively suppressed.

  An object of the present invention is to provide a release sheet that hardly undergoes heavy release even when irradiated with radiation, and a pressure-sensitive adhesive body using the release sheet.

Such an object is achieved by the present inventions (1) to (4) below.
(1) a base material;
A release sheet provided on the base material and having a release agent layer mainly composed of a silicone resin,
The crosslinking point density of the silicone resin is 1/500 or less,
A release sheet that is subjected to radiation sterilization.

  (2) The release sheet according to (1), wherein the silicone resin has a weight average molecular weight of 40,000 to 2,000,000.

  (3) The release sheet according to (1) or (2), wherein the release agent layer has a thickness of 0.01 to 3.0 μm.

  (4) A pressure-sensitive adhesive body comprising the release sheet according to any one of (1) to (3) above and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer.

  According to the present invention, it is possible to obtain a release sheet and a pressure-sensitive adhesive that hardly undergo heavy peeling even when irradiated with radiation.

  Therefore, according to this invention, even if it puts after performing radiation sterilization, a peeling sheet can be peeled from an adhesive sheet simply and reliably.

  The pressure-sensitive adhesive body of the present invention has a configuration in which a pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer and a pressure-sensitive adhesive sheet substrate is adhered to a release sheet composed of a release agent layer and a base material (peeling sheet base material). In such a pressure-sensitive adhesive body, the pressure-sensitive adhesive layer is in contact with the release agent layer.

  In the pressure-sensitive adhesive body, the pressure-sensitive adhesive sheet can be peeled from the release sheet, and after peeling, the pressure-sensitive adhesive sheet is attached to the adherend.

Hereinafter, the release sheet of the present invention will be described.
The release sheet has a configuration in which a release agent layer is formed on a substrate.

  The material constituting the substrate is not particularly limited, and any material can be appropriately selected from those conventionally used as a substrate in a release sheet. Such substrates include, for example, polyester films such as polyethylene terephthalate films and polybutylene terephthalate films, polyolefin films such as polypropylene films and polymethylpentene films, plastic films such as polycarbonate films, metal foils such as aluminum and stainless steel, glassine Paper base materials such as paper, high-quality paper, coated paper, impregnated paper, and synthetic paper, and paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials.

  Although the thickness of a base material is not specifically limited, It is preferable that it is 5-300 micrometers, and it is more preferable that it is 10-200 micrometers.

  By providing the release agent layer on the substrate, the pressure-sensitive adhesive sheet can be peeled from the release sheet.

  The release agent layer is composed of a release agent, and this release agent is mainly composed of a silicone resin.

  By the way, conventionally, a silicone resin has been widely used as a release agent constituting the release sheet. Such a silicone resin has excellent peelability.

  When the release sheet (or the adhesive sheet adhered to the release sheet) needs to be sterilized, for example, as used for medical purposes, the release sheet may be irradiated with radiation. Examples of radiation used for such sterilization include electron beam, γ-ray, ultraviolet ray and the like.

  However, when a conventional release agent is used, heavy release may occur due to irradiation of radiation. In particular, among the radiations described above, heavy peeling was remarkable when an electron beam was used. This heavy release is considered to be because a crosslinking reaction occurs between the component constituting the release agent layer of the release sheet and the component constituting the adhesive layer of the adhesive sheet. Therefore, the present inventors have studied in detail about preventing such heavy peeling, and by using a silicone resin having a relatively low cross-linking point density, the above-described radiation can be irradiated. It was found that heavy peeling can be suppressed.

  In particular, the silicone resin used in the present invention has a cross-linking point density of 1/500 or less. As a result, when sterilizing by irradiation with radiation as described above, it is possible to suppress the rate of increase in peeling force after irradiation relative to the peeling force before irradiation, and as a result, effectively prevent heavy peeling. be able to. Thereby, excellent peelability is obtained. On the other hand, when the average value of the crosslinking point density exceeds the upper limit, the effect of preventing the peeling force from increasing before and after irradiation with radiation cannot be sufficiently obtained.

  As described above, the present invention is characterized in that a silicone resin having a crosslinking point density of 1/500 or less is used. The silicone resin preferably has a crosslinking point density of 1/1000 or less. / 1500 or less is more preferable. Thereby, the above-mentioned effect becomes more remarkable.

In addition, generally the crosslinking point density of a silicone resin is calculated | required as follows.
First, the degree of polymerization of the silicone resin is determined from the weight average molecular weight based on dimethylsiloxane. Then, from the ratio of the number of crosslinking points to the degree of polymerization, the crosslinking point density of the silicone resin can be determined.

  That is, the crosslinking point density of the silicone resin can be determined as a ratio of the number of crosslinking points to the degree of polymerization (number of crosslinking points / degree of polymerization).

  The silicone resin used in the present invention is not particularly limited. For example, a condensation reaction type silicone capable of undergoing a condensation reaction, an addition reaction type silicone capable of undergoing an addition reaction, a radical reaction type silicone capable of undergoing a radical reaction, an ultraviolet curing cured by ultraviolet rays. Type silicone and the like.

  Examples of such condensation reaction type silicones include those represented by the following general formulas (I) to (III).

  As described above, when the silicone resin containing the condensation reaction type silicone represented by the general formulas (I) to (III) is used, the effect of the present invention can be made more remarkable.

  The silicone resin is not limited to those described above. For example, an acryloyl group, a methacryloyl group, an alkenyl group, a vinylamide group, a hydrosilyl group, a silanol group, a diazo group, an acetylene group, a thiol group, It may be a polyorganosiloxane having a functional group such as a hydroxyl group or a mixture thereof.

  Moreover, it is preferable that the weight average molecular weights of a silicone resin are 40,000-2 million, and it is more preferable that it is 100,000-1 million. As a result, it is possible to make the release resin processing suitability excellent while keeping the crosslinking density of the silicone resin within a preferable range.

  Note that the release agent layer may contain other resin components and various additives such as a plasticizer and a stabilizer.

  The thickness of the release agent layer is not particularly limited, but is preferably 0.01 to 3.0 μm, and more preferably 0.05 to 2.0 μm.

  When the thickness of the release agent layer is within this range, the release properties of the obtained release sheet are particularly excellent, and blocking of the release agent layer can be more reliably prevented.

Hereinafter, the adhesive sheet will be described.
The pressure-sensitive adhesive sheet has a configuration in which a pressure-sensitive adhesive layer is formed on a pressure-sensitive adhesive sheet substrate.

  The pressure-sensitive adhesive sheet base material has a function of supporting the pressure-sensitive adhesive layer. For example, polyethylene terephthalate, polyester such as polybutylene terephthalate, plastic film such as polystyrene, metal foil such as aluminum and stainless steel, dust-free paper, synthetic paper It is composed of a simple substance such as paper or a composite.

  Although the thickness of an adhesive sheet base material is not specifically limited, It is preferable that it is 5-300 micrometers, and it is more preferable that it is 10-200 micrometers.

  The pressure-sensitive adhesive sheet substrate may be printed or printed on the surface (the surface opposite to the surface on which the pressure-sensitive adhesive layer is laminated). Moreover, the surface of the pressure-sensitive adhesive sheet substrate may be subjected to surface treatment for the purpose of improving the adhesion of printing or printing. Moreover, the adhesive sheet may function as a label.

The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition mainly composed of a pressure-sensitive adhesive.
Examples of the pressure sensitive adhesive include acrylic pressure sensitive adhesive, polyester pressure sensitive adhesive, and urethane pressure sensitive adhesive. Among them, the pressure-sensitive adhesive is particularly preferably an acrylic pressure-sensitive adhesive.

  When the release agent layer is a silicone resin as in the present invention, when an acrylic adhesive is used as the adhesive, the peelability of the adhesive sheet is extremely high.

  For example, when the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive, the main monomer component that provides tackiness, the comonomer component that provides adhesiveness and cohesion, and the functional group-containing monomer component for improving the cross-linking point and adhesion are mainly used. It can be composed of a polymer or a copolymer.

  As the main monomer component, for example, acrylic acid alkyl esters such as ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, methoxyethyl acrylate, Examples include methacrylic acid alkyl esters such as butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate.

  Examples of the comonomer component include methyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, styrene, acrylonitrile, and the like.

  Examples of the functional group-containing monomer component include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, 2-hydroxyethyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. And hydroxyl group-containing monomers such as N-methylolacrylamide, acrylamide, methacrylamide, glycidyl methacrylate and the like.

  By including these components, the adhesive force and cohesive force of the pressure-sensitive adhesive composition are improved. In addition, since such an acrylic resin usually does not have an unsaturated bond in the molecule, stability to light and oxygen can be improved. Furthermore, a pressure-sensitive adhesive composition having quality and characteristics according to the application can be obtained by appropriately selecting the type and molecular weight of the monomer.

  As such a pressure-sensitive adhesive composition, any of a crosslinked type that undergoes crosslinking treatment and a non-crosslinked type that does not undergo crosslinking treatment may be used, but a crosslinked type is more preferred. When a cross-linked type is used, a pressure-sensitive adhesive layer with better cohesion can be formed.

  Examples of the crosslinking agent used in the crosslinking adhesive composition include an epoxy compound, an isocyanate compound, a metal chelate compound, a metal alkoxide, a metal salt, an amine compound, a hydrazine compound, and an aldehyde compound.

  Moreover, in the adhesive composition used for this invention, various additives, such as a plasticizer, a tackifier, and a stabilizer, may be contained as needed.

  Although the thickness of an adhesive layer is not specifically limited, It is preferable that it is 5-200 micrometers, and it is more preferable that it is 10-100 micrometers.

  The release sheet can be produced by preparing a base material and applying a release agent on the base material to form a release agent layer.

  As a method for coating the release agent on the substrate, for example, an existing method such as a gravure coating method, a bar coating method, a spray coating method, a spin coating method, a knife coating method, a roll coating method, or a die coating method can be used. .

  The pressure-sensitive adhesive sheet can be prepared by preparing a pressure-sensitive adhesive sheet substrate and coating the pressure-sensitive adhesive composition on the pressure-sensitive adhesive sheet substrate to form a pressure-sensitive adhesive layer.

  Examples of the method for coating the pressure-sensitive adhesive composition on the pressure-sensitive adhesive sheet substrate include existing gravure coating methods, bar coating methods, spray coating methods, spin coating methods, knife coating methods, roll coating methods, die coating methods and the like. The method can be used.

  Examples of the form of the pressure-sensitive adhesive composition in this case include a solvent type, an emulsion type, and a hot melt type.

  Then, an adhesive body can be obtained by bonding a release sheet and an adhesive sheet so that an adhesive layer may contact | connect a release agent layer.

  According to such a production method, the pressure-sensitive adhesive body can be produced without exposing the release sheet to a high temperature during production. Furthermore, for example, it becomes difficult to be affected by the solvent used when forming the pressure-sensitive adhesive layer.

  In addition, an adhesive body may be manufactured by forming an adhesive layer on the release agent layer of a release sheet, and then joining an adhesive sheet base material on the adhesive layer.

  As mentioned above, although the peeling sheet and adhesive body of this invention were described about suitable embodiment, this invention is not limited to these. For example, the pressure-sensitive adhesive body may have a pressure-sensitive adhesive layer formed on both surfaces of a pressure-sensitive adhesive sheet base material, and further a release sheet formed on the surface of both pressure-sensitive adhesive layers.

  In the above-described embodiment, the pressure-sensitive adhesive sheet has been described as including a pressure-sensitive adhesive sheet base material and a pressure-sensitive adhesive layer. For example, an intermediate layer is provided between the pressure-sensitive adhesive sheet base material and the pressure-sensitive adhesive layer. It may be.

  In the embodiment described above, the pressure-sensitive adhesive body has been described as having a structure in which the release sheet and the pressure-sensitive adhesive sheet are adhered, but the release agent layer is formed on one side of the substrate, and the other side. An adhesive layer may be formed on the side.

Next, specific examples of the release sheet of the present invention will be described.
1. Preparation of release sheet On one side of the following substrate, a 5% by weight solution of a release agent composition prepared by dissolving the following silicone resin and catalyst in toluene was applied with a Meyer bar (# 8), followed by drying at 130 ° C. Then, a release sheet was formed by forming a release agent layer.
The configuration of each layer is as follows.

Example 1
[1] Base material: Glassine paper (Lintech Co., Ltd. product name “Glasin Blue 73”)
Thickness: 65μm

[2] Release agent layer constituting material: Condensation reaction type silicone resin having a crosslinking point density of 1/2000 (weight average molecular weight 296000): 100 parts by weight catalyst (dibutyltin, “Toray Dow Corning Silicone: SRX-242AC”): 4 weights Part thickness: 0.8μm

  In addition, the polysiloxane which combined the silanol group was synthesize | combined by the existing method so that the compounding ratio of a monomer might be adjusted and the density of a crosslinking point might be 1/2000, and the condensation reaction type silicone resin was obtained.

(Example 2)
Example 1 except that condensate silicone having a crosslink density of 1/4000 (weight average molecular weight 592000) was used as a constituent material of the release agent layer in place of the condensate silicone resin having a crosslink density of 1/2000. In the same manner as in Example 1, a release sheet was prepared.

(Example 3)
Example 1 except that addition type silicone (weight average molecular weight 148000) having a crosslinking point density of 1/1000 was used as a constituent material of the release agent layer in place of the condensation type silicone resin having a crosslinking point density of 1/2000. In the same manner as in Example 1, a release sheet was prepared.

(Example 4)
A 6% by weight solution of a release agent composition prepared by dissolving the following silicone resin and catalyst in toluene with a Mayer bar (# 4) was applied to the surface of the polyethylene resin of the following substrate, followed by drying at 130 ° C. Then, a release sheet was formed by forming a release agent layer.

[1] Base material constituting material: high quality paper (manufactured by Nippon Paper Industries Co., Ltd .: trade name “KYP81.4 g”) laminated with polyethylene resin to a thickness of 18 μm.

[2] Release agent layer constituting material: Condensation reaction type silicone resin having a crosslinking point density of 1/2000 (weight average molecular weight 296000): 100 parts by weight catalyst (dibutyltin, “Toray Dow Corning Silicone: SRX-242AC”): 4 weights Part thickness: 0.5μm

(Example 5)
As a constituent material of the release agent layer, a condensation reaction type silicone resin having a crosslinking point density of 1/4000 (weight average molecular weight 592000) was used in place of the condensation reaction type silicone resin having a crosslinking point density of 1/2000. A release sheet was prepared in the same manner as in Example 4.

(Example 6)
As the constituent material of the release agent layer, in place of the condensation type silicone resin having a crosslinking point density of 1/2000, an addition type silicone resin having a crosslinking point density of 1/1000 (weight average molecular weight 148000) was used. A release sheet was prepared in the same manner as in Example 4.

(Comparative Example 1)
As a constituent material of the release agent layer, a silicone resin (weight average molecular weight 14800) using an addition type silicone resin having a crosslinking point density of 1/100 was used instead of the condensation type silicone resin having a crosslinking point density of 1/2000. Except for the above, a release sheet was produced in the same manner as in Example 1.

(Comparative Example 2)
As the constituent material of the release agent layer, in place of the condensation type silicone resin having a crosslinking point density of 1/2000, a condensation reaction type silicone resin having a crosslinking point density of 1/100 (weight average molecular weight 14800) was used. A release sheet was produced in the same manner as in Example 4.

2. Production of pressure-sensitive adhesive body Each release sheet produced in each of the above Examples and Comparative Examples was irradiated with an electron beam so that the irradiation dose was 0, 0.5, 1.5, and 5.0 Mrad. Then, after leaving at room temperature for 24 hours, an acrylic pressure-sensitive adhesive (manufactured by Toyo Ink Co., Ltd .: trade name “Olivein BPS-5127”) is applied with an applicator roll (5 mil) so that the thickness after drying becomes 50 μm. Then, a polyethylene terephthalate film (thickness: 50 μm) was bonded to prepare an adhesive body.

3. Evaluation For each pressure-sensitive adhesive body, the peel strength of the release sheet after 1 day and 7 days from the production was measured.

The peeling force was measured by cutting the pressure-sensitive adhesive to a width of 20 mm, fixing the release sheet using a tensile tester, and pulling the substrate in the 180 ° direction at a speed of 300 mm / min. Moreover, the increase rate in each condition when the peeling force of the peeling sheet not irradiated with the electron beam was used as a reference (1.0) was obtained.
These results are shown in Table 1.

  As is clear from Table 1, the release sheet of the comparative example has a large rate of increase in peel force due to electron beam irradiation and is difficult to peel, whereas the release sheet of each example has a peel force due to electron beam irradiation. The rate of increase was small, and the heavy peeling was sufficiently suppressed.

Claims (4)

A substrate;
A release sheet provided on the base material and having a release agent layer mainly composed of a silicone resin,
The crosslinking point density of the silicone resin is 1/500 or less,
A release sheet that is subjected to radiation sterilization.   The release sheet according to claim 1, wherein the silicone resin has a weight average molecular weight of 40,000 to 2,000,000.   The release sheet according to claim 1 or 2, wherein the release agent layer has a thickness of 0.01 to 3.0 µm.   A pressure-sensitive adhesive body comprising the release sheet according to claim 1 and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer.