JP2014151612A - Peelable sheet and adhesive body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a peelable sheet which can be peeled off from an adhesive sheet even after radiation sterilization and can suppress deterioration in adhesive force of the adhesive sheet after the elapse of product storage.SOLUTION: There is provided a peelable sheet used for radiation sterilization which has a base material 11 and a peeling agent layer 12 containing a silicone resin provided on the base material 11, wherein a ratio of an aryl group bonded to the siloxane chain of the silicone resin contained in the peeling agent layer 12 is 0.01 to 9.99 mol%.

Description

  The present invention relates to a release sheet premised on sterilization by irradiation with radiation. Moreover, this invention relates also to the adhesive body which laminated | stacked such a peeling sheet with the adhesive sheet.

  The pressure-sensitive adhesive sheet with the pressure-sensitive adhesive layer formed on the substrate may cause the pressure-sensitive adhesive layer to deteriorate during storage or transportation when the pressure-sensitive adhesive layer is exposed, or may stick to unintended materials In general, the pressure-sensitive adhesive layer is stored or transported in a state protected with a release sheet. The release sheet is obtained by forming a release agent layer on a substrate, and the release agent layer is directly bonded to the adhesive layer of the adhesive sheet.

  As described above, the pressure-sensitive adhesive body in which the pressure-sensitive adhesive sheet and the release sheet are bonded to each other has various uses. However, when used for medical hygiene, the pressure-sensitive adhesive body needs to be sterilized. Ethylene oxide gas and radiation are generally used for sterilization, but ethylene oxide gas is extremely toxic, flammable and explosive and difficult to handle, and radiation sterilization is becoming the mainstream. However, when the pressure-sensitive adhesive body is sterilized with radiation, there may be a problem that the release sheet is difficult to peel from the pressure-sensitive adhesive sheet. Therefore, in order to cope with such problems, it has been proposed to improve the release sheet.

For example, in Patent Document 1, the release agent layer of the release sheet is mainly composed of a silicone resin, and the ratio of phenyl groups in all substituents bonded to silicon atoms as the silicone resin is 10 to 50 mol%. It has been proposed to use According to this patent document, it is described that by adopting such a configuration, it is possible to prevent the release sheet from being easily peeled off even when irradiated with radiation. Further, according to this patent document, it is described that such an effect cannot be sufficiently obtained when the proportion of the phenyl group is less than 10 mol%.
However, a silicone resin having a phenyl group of 10 mol% or more has a high viscosity and is difficult to apply, and a solvent must be used. Further, a crosslinked film of a silicone resin having a phenyl group of 10 mol% or more has a large peeling force and cannot be easily peeled off.

  Patent Document 2 proposes that a release agent layer of a release sheet is mainly composed of a silicone resin, and a radical inhibitor is added therein. Examples of the radical inhibitor include compounds having an aromatic ring such as (2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate). According to this patent document, it is described that by adopting such a configuration, the release sheet can be easily and reliably peeled off from the adhesive sheet even when irradiated with radiation. It is known that the resin has poor compatibility with aromatic compounds and is likely to separate over time, and Patent Document 2 does not describe the use of a silicone resin as a radical inhibitor. Therefore, the radical suppression effect may be insufficient.

JP 2004-351612 A JP 2004-351613 A

  The present inventors have made various studies on a release sheet composed mainly of a silicone resin as a release agent layer. As a result, excellent release properties after radiation sterilization can be obtained even if a formulation within the range described in the above patent document is carried out. It turns out that there may not be. In other words, when radiation sterilization is performed on an adhesive body using a release sheet mainly composed of a silicone resin as the release agent layer, a large peeling force is required when peeling the adhesive sheet from the release sheet, and smooth peeling can be performed. It turns out that there may not be. It has also been found that in sterilized products, the adhesive strength may be reduced when the adhesive sheet after peeling the release sheet is adhered to the adherend.

  Based on the discovery of a new problem that has not been recognized in the past, the present inventors can easily peel off the pressure-sensitive adhesive sheet even after radiation sterilization, and adhere the pressure-sensitive adhesive sheet to the adherend. In order to provide a release sheet that can prevent the adhesive strength from being reduced when it is applied, studies were conducted.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a silicone resin that satisfies a specific condition contrary to the suggestion of the prior art. It came to be completed. That is, the following present invention has been provided as means for solving the problems.

（一般式（１）中、Ｒはそれぞれ独立に水素原子、水酸基または有機基を表し、シリコーン樹脂１分子中のＲの少なくとも２個がアルケニル基であり、全Ｒの０〜９．９８モル％がアリール基である。ｘは１以上の整数を表す。）
（Ｂ）下記式（２）で表される、アルケニル基は含有せず、アリール基を含有するシリコーン樹脂からなる軽剥離コントロール剤 ０．１〜３０質量部

（一般式（２）中、Ｒ’はそれぞれ独立に水素原子、水酸基またはアルケニル基以外の有機基を表し、全Ｒ’の０．０１〜５０モル％がアリール基である。Ｙは１以上の整数を表す。）
（Ｃ）１分子中に少なくとも２個の水素原子がケイ素原子に結合しているシリコーン樹脂 ０．１〜３０質量部
（Ｄ）白金族金属系触媒 ０．１〜５質量部
で構成されており、全シリコーン樹脂中に占めるアリール基の割合が０．０１〜９．９９モル％であることを特徴とする、［１］に記載の放射線滅菌に用いられる剥離シート。
［３］ 前記（Ａ）の一般式（１）で表されるシリコーン樹脂は、２５℃における粘度が５０〜５，０００ｍＰａ・ｓであることを特徴とする［１］または［２］に記載の剥離シート。
［４］ 前記（Ｂ）のアリール基を有するシリコーン樹脂が、２５℃における粘度が５０〜１，０００，０００ｍＰａ・ｓであることを特徴とする［１］〜［３］のいずれか１項に記載の剥離シート。
［５］ 前記剥離剤層は、白金族金属系触媒を１０〜５００ppm含むことを特徴とする［１］〜［４］のいずれか１項に記載の剥離シート。
［６］ 前記剥離剤層が非溶剤型であることを特徴とする［１］〜［５］のいずれか１項に記載の剥離シート。
［７］ 前記剥離剤層に含まれる全シリコーン樹脂が、

を満たすことを特徴とする［１］〜［６］のいずれかに記載の剥離シート。
（ａは下記一般式（３−１）で表されるシロキサンの単位数を表し、ｂは下記一般式（３−２）で表されるシロキサンの単位数を表し、ｃは下記一般式（３−３）で表されるシロキサンの単位数を表し、ｄは下記一般式（３−４）で表されるシロキサンの単位数を表す。）

（一般式（３−１）〜（３−４）中、Ｒ₁〜Ｒ₈はそれぞれ独立に水素原子、水酸基、または不飽和炭化水素基以外の有機基を表す。Ｑ₁およびＱ₂はそれぞれ独立に炭素数２〜６の不飽和炭化水素基を表す。）
［８］ ［１］〜［７］のいずれか１項に記載の剥離シートと、基材と該基材上に設けられた粘着剤層とを有する粘着シートを積層した構造を有する粘着体であって、前記剥離シートの剥離剤層と前記粘着シートの粘着剤層とが粘着している粘着体。
［９］ ［８］に記載の粘着体であって、放射線滅菌が成された滅菌済み粘着体。 [1] A substrate and a release agent layer containing a silicone resin provided on the substrate,
A release sheet used for radiation sterilization, characterized in that the ratio of aryl groups bonded to the siloxane chain of the silicone resin contained in the release agent layer is 0.01 to 9.99 mol%.
[2] The release agent layer is
(A) Silicone resin represented by the following general formula (1) containing 2 or more alkenyl groups and 0 to 9.98 mol% of aryl groups in one molecule 100 parts by mass

(In the general formula (1), each R independently represents a hydrogen atom, a hydroxyl group, or an organic group, and at least two R in one molecule of the silicone resin are alkenyl groups, and 0 to 9.98 mol% of the total R. Is an aryl group, x represents an integer of 1 or more.)
(B) The light peeling control agent which consists of a silicone resin which does not contain the alkenyl group represented by following formula (2) but contains an aryl group 0.1-30 mass parts

(In General Formula (2), R ′ each independently represents an organic group other than a hydrogen atom, a hydroxyl group, or an alkenyl group, and 0.01 to 50 mol% of all R ′ is an aryl group. Y is 1 or more. Represents an integer.)
(C) A silicone resin in which at least two hydrogen atoms are bonded to a silicon atom in one molecule 0.1 to 30 parts by mass (D) platinum group metal catalyst 0.1 to 5 parts by mass The release sheet used for radiation sterilization according to [1], wherein the ratio of aryl groups in the total silicone resin is 0.01 to 9.99 mol%.
[3] The silicone resin represented by the general formula (1) of (A) has a viscosity at 25 ° C. of 50 to 5,000 mPa · s, according to [1] or [2] Release sheet.
[4] In any one of [1] to [3], the silicone resin having an aryl group of (B) has a viscosity at 25 ° C. of 50 to 1,000,000 mPa · s. The release sheet as described.
[5] The release sheet according to any one of [1] to [4], wherein the release agent layer contains 10 to 500 ppm of a platinum group metal catalyst.
[6] The release sheet according to any one of [1] to [5], wherein the release agent layer is a non-solvent type.
[7] The total silicone resin contained in the release agent layer is

The release sheet according to any one of [1] to [6], wherein:
(A represents the number of siloxane units represented by the following general formula (3-1), b represents the number of siloxane units represented by the following general formula (3-2), and c represents the following general formula (3 -3) represents the number of siloxane units represented by d), and d represents the number of siloxane units represented by the following general formula (3-4).

(In the general formulas (3-1) to (3-4), R _{1 to} R ₈ each independently represents a hydrogen atom, a hydroxyl group, or an organic group other than an unsaturated hydrocarbon group. Q ₁ and Q ₂ each represent Independently represents an unsaturated hydrocarbon group having 2 to 6 carbon atoms.)
[8] An adhesive body having a structure in which a release sheet according to any one of [1] to [7] and an adhesive sheet having a base material and an adhesive layer provided on the base material are laminated. An adhesive body in which the release agent layer of the release sheet and the adhesive layer of the adhesive sheet are adhered.
[9] A sterilized pressure-sensitive adhesive body according to [8], which has been subjected to radiation sterilization.

  The pressure-sensitive adhesive body using the release sheet of the present invention can easily peel the release sheet from the pressure-sensitive adhesive sheet even after radiation sterilization, and adheres the pressure-sensitive adhesive sheet after peeling the release sheet to the adherend. It is possible to suppress a decrease in the adhesive strength of the adhesive sheet during product storage.

It is sectional drawing which shows the structural example of the adhesive body using the peeling sheet of this invention. It is sectional drawing which shows another structural example of the adhesive body using the peeling sheet of this invention.

  Below, the peeling sheet and adhesive body of this invention are demonstrated in detail. The description of the constituent elements described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Peeling sheet]
(Feature)
The release sheet of the present invention has a base material and a release agent layer containing a silicone resin provided on the base material. The ratio of the aryl group bonded to the siloxane chain of the silicone resin contained in the release agent layer is 0.01 to 9.99 mol%.

  In the present invention, the aryl group-containing silicone resin having the migratory property of the component (B) contained in the release agent layer is transferred to the surface layer, thereby efficiently suppressing the influence of radiation by increasing the concentration of the aryl group on the surface layer. be able to. Further, since the silicone resin of component (B) adheres to or penetrates into the adhesive, the peeling force when peeling the adhesive is very small.

(Silicone resin)
The silicone resin is contained in the release agent layer. The silicone resin in the present invention is selected from R ₃ SiO _1/2 (M unit), R ₂ SiO _2/2 (D unit), R ₁ SiO _3/2 (T unit), and SiO _4/2 (Q unit). It is a polymer composed of the structured components. In the above units, each R independently represents a hydrogen atom, a hydroxyl group or an organic group.

The release agent layer contains a silicone resin. In this invention, the ratio of the aryl group couple | bonded with the siloxane chain of the silicone resin contained in a release agent layer is 0.01-9.99 mol%.
In this specification, the “ratio of the aryl group bonded to the siloxane chain” means the silicon constituting the siloxane chain (..- Si-O-Si- ..) which is an alternating chain of silicon atoms and oxygen atoms. This means the ratio of the aryl group to the hydrogen atom bonded to the atom and the substituent. That is, it means the ratio of the number of aryl groups to the total number of hydrogen atoms and substituents bonded to silicon atoms constituting the siloxane chain. Incidentally, various atoms and functional groups such as a hydrogen atom, a methyl group, and a vinyl group can be bonded to the silicon atom constituting the silicone resin. The aryl group means a functional group derived from an aromatic hydrocarbon, and specific examples include a phenyl group, a benzyl group, a tolyl group, a xylyl group, and a naphthyl group. 6-14 are preferable and, as for carbon number of an aryl group, 6-10 are more preferable.
The ratio of the aryl group in the silicone resin in the present invention is preferably 0.01 to 8 mol%, more preferably 0.01 to 6 mol%, and more preferably 0.01 to 4 mol%. More preferably. The ratio of the aryl group in the silicone resin can be measured, for example, by performing ¹ H-NMR.
By setting the ratio of the aryl group in the silicone resin within the above range, in the present invention, the release sheet can be easily peeled from the adhesive sheet even after radiation sterilization. Furthermore, even when the pressure-sensitive adhesive sheet after peeling the release sheet is adhered to the adherend and the product is stored, a decrease in the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet can be suppressed.

The release agent layer is preferably composed of components (A) to (D).
Here, (A) represents two or more alkenyl groups represented by the following formula (1), and aryl groups are 0 to 9.98 mol% of all R (total substituents), preferably 0 to 5 mols. %, More preferably 0.1 to 3 mol% silicone resin.

In general formula (1), each R independently represents a hydrogen atom, a hydroxyl group, or an organic group, at least two of R in one molecule of the silicone resin are alkenyl groups, and 0 to 9.98 mol% of the total R Is an aryl group. x represents an integer of 1 or more.
When the ratio of all R (all substituents) aryl groups is 10 mol% or more, the peel strength becomes too high, which is not preferable.

(B) is a silicone resin represented by the following general formula (2) that does not contain an alkenyl group and contains an aryl group in an amount of 0.01 to 50 mol% of the total R ′ (total substituents).
(B) is preferably blended in an amount of 0.1 to 30 parts by mass, preferably 0.1 to 28 parts by mass, more preferably 0.1 to 25 parts by mass with respect to 100 parts by mass of (A). If the amount is less than 0.1 parts by mass, light peeling may not be achieved or radiation resistance may be insufficient. In addition, when the amount is 30 parts by mass or more, there are too many migration components, and a large amount of migration components may adhere to the surface of the pressure-sensitive adhesive. .

  Here, in general formula (2), R 'represents a hydrogen atom, a hydroxyl group, or an organic group each independently. In the present specification, the “organic group” means a monovalent atomic group containing a carbon atom, and preferably a hydrocarbon or a part or all of the hydrogen atoms bonded to these groups are a nitrogen atom, an oxygen atom, and A group substituted with a group containing a sulfur atom. Examples thereof include a substituted or unsubstituted alkyl group and a substituted or unsubstituted aryl group. 1-10 are preferable, as for carbon number of an alkyl group, 1-6 are more preferable, and 1-3 are more preferable. Specific examples include a methyl group, an ethyl group, and a propyl group. 6-14 are preferable and, as for carbon number of an aryl group, 6-10 are more preferable. Specific examples include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. Examples of the substituent that can be substituted with an alkyl group or an aryl group include an alkyl group, an aryl group, an alkoxy group, and an aryloxy group.

  0.01 to 50 mol% of R 'in the silicone resin is an aryl group. When the proportion of the aryl group is less than 0.01 mol%, the radiation resistance is reduced, and the radical site from which the organic group such as methyl group bonded to the siloxane of (A) or (B) is removed is crosslinked. As a result, the peeling force increases. On the other hand, when the proportion of the aryl group exceeds 50 mol%, the viscosity becomes too high, and mixing into (A), (C), and (D) becomes difficult. In addition, since the aryl group has higher peel strength than the alkyl group, the presence of an excess aryl group is not preferable.

  In general formula (2), Y represents an integer of 1 or more. Moreover, the viscosity in 25 degreeC is 50-1,000,000 mPa * s, Preferably it is 100-100,000 mPa * s. A viscosity of 50 mPa · s or less is not preferable because the surface becomes sticky. In addition, in the case of 1,000,000 mPa · s or more, mixing into (A), (C), and (D) becomes difficult.

(C) is a silicone resin represented by the following general formula (4) in which at least two hydrogen atoms are bonded to silicon atoms in one molecule.

In general formula (4), R ″ each independently represents an organic group. However, the aryl group is 0 to 3 mol%, preferably 0 to 1 mol%, more preferably 0 to 0.1 mol% of the total R ″. is there.
Z represents an integer of 2 or more, and Z ′ is a number satisfying 0 ≦ Z ′ / (Z + Z ′) <0.4, preferably 0 ≦ Z ′ / (Z + Z ′) <0.2.

(D) is a platinum group metal catalyst. The platinum group metal catalyst is used as a catalyst for promoting an addition curing reaction (hydrosilylation) between a silicone resin component and a crosslinking agent.
As the component (D), a known platinum group metal catalyst can be used, but it is preferable to use platinum or a platinum compound. Specific examples of platinum group metal catalysts include platinum black, platinous chloride, chloroplatinic acid, chloroplatinic acid-modified products, chloroplatinic acid and olefins, aldehydes, vinyl siloxanes or acetylene alcohols. Can be mentioned. The platinum group metal catalyst can be obtained, for example, by adding a complex of platinum and vinyl siloxane to 1-ethyl 1-cyclohexanol.

  When the release agent layer contains 100 parts by mass of a silicone resin containing 2 or more alkenyl groups as component (A) and 0 to 9.98 mol% of aryl groups in total R ′ (total substituents) It is preferable that 0.1 to 30 parts by mass of the component (B), 0.1 to 30 parts by mass of the component (C), and 10 to 500 ppm of platinum group metal as the component (D) with respect to the total amount of siloxane. In addition, if the addition amount of (D) component is an effective amount as a catalyst, it can be suitably increased / decreased according to the desired cure rate.

  The release agent layer is preferably a non-solvent type. The non-solvent type means that no solvent is used when the components constituting the release agent layer are mixed. If the release agent layer is a non-solvent type, the burden on the environment can be reduced, and the manufacturing cost can be suppressed.

  The silicone resin contained in the release agent layer preferably satisfies the following general formula (3).

  In general formula (3), a represents the number of siloxane units represented by the following general formula (3-1), b represents the number of siloxane units represented by the following general formula (3-2), and c Represents the number of siloxane units represented by the following general formula (3-3), and d represents the number of siloxane units represented by the following general formula (3-4).

In general formulas (3-1) to (3-4), R _{1 to} R ₈ each independently represents a hydrogen atom, a hydroxyl group, or an organic group. However, unsaturated hydrocarbons are not included. Q ₁ and Q ₂ each independently represents an unsaturated hydrocarbon having 2 to 6 carbon atoms. When R _{1 to} R ₈ are each a methyl group, the siloxane unit represented by the general formula (3-1) is a dimethylsiloxane unit, and the siloxane unit represented by the general formula (3-2) is trimethylsiloxane. The siloxane unit represented by the general formula (3-3) is a methylalkenylsiloxane unit, and the siloxane unit represented by the general formula (3-4) is a dimethylalkenylsiloxane unit.
The general formula (3) is a value obtained by dividing the number of siloxane units not containing an unsaturated functional group by the number of siloxane units containing an unsaturated functional group which is considered to be crosslinked. The smaller the value, the higher the crosslinking density. Means that.

  In the present invention, the number of siloxane units preferably satisfies 40 <(a + b) / (c + d) <200, more preferably 40 <(a + b) / (c + d) <100. When (a + b) / (c + d) is 40 or less, the crosslink density becomes too high, and the transfer to the surface of the component (B), which is a transition component, is hindered by the high crosslink density, so that the release force increases, and the release sheet May be difficult to remove. On the other hand, when (a + b) / (c + d) is 200 or more, the crosslinking density becomes too low, and a solid coating film may not be obtained.

(Additive to release agent layer)
In the release agent layer of the release sheet of the present invention, various additives that can be added to the silicone resin used for the normal release agent layer can be added. It is also possible to add a resin other than the silicone resin.

(Base material)
The base material constituting the release sheet of the present invention plays a role as a support. In this invention, a base material can be selected and used from what is normally used as a base material of a peeling sheet. For example, papers such as high-quality paper, clay-coated paper, glassine paper, and polyethylene laminated paper; various plastic films such as polyethylene film, polypropylene film, polyethylene terephthalate film, polybutylene terephthalate film, and polycarbonate film may be used as the base material. it can.
The thickness of the substrate is preferably 5 μm or more, and more preferably 10 μm or more. Moreover, it is preferable that it is 300 micrometers or less, and it is more preferable that it is 200 micrometers or less.

(Formation of release agent layer)
The release sheet of the present invention can be produced by forming a release agent layer on a substrate. The method for forming the release agent layer is not particularly limited, but may be formed by coating and drying with a normal coating apparatus such as a Mayer bar coater, kiss roll coater, roll coater, gravure coater, rod coater, blade coater, air knife coater, etc. Is preferred. The coating amount of the release agent is preferably in the range of 0.1 to 5.0 g / m ² , more preferably 0.5 to 3.0 g / m ² . If the amount of the release agent applied is too small, satisfactory release performance cannot be obtained. Conversely, even if the amount of the release agent applied is excessively increased, the release performance is saturated and tends to be economically disadvantageous.

(Radiation irradiation)
It can sterilize by irradiating the pressure-sensitive adhesive body using the release sheet of the present invention with radiation. Irradiation may be before or after forming the adhesive body by laminating the release sheet of the present invention with the adhesive sheet, but generally sterilization after forming the adhesive body is preferred. . Further, radiation sterilization may be performed both before and after the formation of the adhesive body.
The type of radiation can be selected from those usually used in the medical hygiene field, and examples include γ-rays, electron beams, and ultraviolet rays, and the irradiation dose can be arbitrarily adjusted to obtain a desired sterilization effect. it can. In addition, radiation sterilization may be performed a plurality of times, and in that case, the type of radiation can be changed.

[Adhesive]
(Feature)
The pressure-sensitive adhesive body of the present invention has a structure in which a release sheet and a pressure-sensitive adhesive sheet are laminated. At this time, it is configured such that the release agent layer of the release sheet is in contact with the adhesive layer of the adhesive sheet. The release sheet used here is the above-described release sheet of the present invention. Since the pressure-sensitive adhesive body of the present invention has the release sheet of the present invention, it is possible to easily release the release sheet from the pressure-sensitive adhesive sheet even after radiation sterilization, and to suppress a decrease in adhesive strength with time of the pressure-sensitive adhesive sheet. Can do.

(Adhesive sheet)
The type of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is not particularly limited and can be appropriately selected from various known rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, etc. From this point of view, an acrylic ester adhesive is preferably used. The pressure-sensitive adhesive is classified into strong viscosity, general-purpose, re-peeling, etc. from the viewpoint of adhesive strength, but this is not particularly limited, and a desired adhesive level can be selected. The pressure-sensitive adhesive can be either a one-pack type or a two- or more-cured curing type, and the form of the pressure-sensitive adhesive may be any of a solvent type, an emulsion type, and a hot melt type. In addition, various known additives can be added to the pressure-sensitive adhesive layer as long as the effects of the present invention are not impaired. Examples of additives include rosin-based, terpene-based, petroleum-based tackifier resins, starches, binders such as CMC, surfactants such as wetting agents such as polyethylene glycol, antifoaming agents, wetting agents, and viscosity modifiers. , Pigments and dyes can be used in combination.

  The base material of the pressure-sensitive adhesive sheet can be selected from those usually used as the base material of the pressure-sensitive adhesive sheet. For example, a polyethylene film, a polypropylene film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polycarbonate film, various plastic films such as a urethane film, a metal foil such as an aluminum foil, and a nonwoven fabric can be used. The thickness of the substrate is preferably 5 to 300 μm, and more preferably 10 to 200 μm.

  The pressure-sensitive adhesive sheet can be produced by forming a pressure-sensitive adhesive layer on a substrate. The method for forming the pressure-sensitive adhesive layer is not particularly limited, but it may be a normal application such as Mayer bar coater, kiss roll coater, lip coater, roll coater, gravure coater, rod coater, blade coater, comma coater, air knife coater, slit die coater, etc. It is preferably formed by coating and drying with an apparatus. The thickness of the pressure-sensitive adhesive layer is preferably in the range of 5 to 200 μm, more preferably 10 to 100 μm.

(Preparation of adhesive)
The method for producing the adhesive body is not particularly limited. The pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed on the substrate may be directly bonded to the release sheet of the present invention, or the pressure-sensitive adhesive layer is formed on the release layer of the release sheet of the present invention. You may employ | adopt the transfer system which bonds the base material for adhesive sheets later.
Moreover, after creating a pressure-sensitive adhesive body using a general release sheet different from the present invention, the release sheet can be replaced with the release sheet of the present invention.

  As shown in FIG. 1, the pressure-sensitive adhesive body 1 of the present invention has a structure in which a release sheet 2 composed of a base material 11 and a release agent layer 12 is bonded to a pressure-sensitive adhesive sheet 3 composed of a base material 21 and a pressure-sensitive adhesive layer 22. As shown in FIG. 2, the release sheet 2 made of the base material 11 and the release agent layer 12 is formed on both sides of the pressure-sensitive adhesive sheet 3 made of the pressure-sensitive adhesive layer 22, the base material 21, and the pressure-sensitive adhesive layer 22. It may have a structure in which are bonded together. In the embodiment shown in FIG. 2, the pressure-sensitive adhesive sheet can be used as a double-sided pressure-sensitive adhesive sheet. At this time, only one of the two release sheets may be used as the release sheet of the present invention or both may be used as the release sheet of the present invention depending on the application.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(1) Production of release sheet As a base material, a high-quality paper having a polyethylene laminate was prepared. Moreover, the release agent layer forming coating solution was prepared by mixing a silicone resin having an aryl group content shown in Table 1 and a platinum catalyst. The release agent layer-forming coating solution was applied onto the substrate with a gravure coater and dried to form a release agent layer having a coating amount of 0.5 g / m ² . In this way, a release sheet was obtained.

(2) Preparation of pressure-sensitive adhesive body As a pressure-sensitive adhesive layer-forming coating solution, 100 parts by weight of an acrylic resin (MD1 manufactured by Soken Chemical Co., Ltd.) and 100 parts by weight of a toluene solvent were mixed. This pressure-sensitive adhesive layer-forming coating solution was applied onto the release agent layer of the release sheet with a comma coater and dried to form a pressure-sensitive adhesive layer having a thickness of 30 μm. Furthermore, a 25 μm-thick urethane film (Silkron HV85 manufactured by Okura Kogyo Co., Ltd.) was bonded onto the adhesive layer to obtain an adhesive.

(3) Radiation irradiation The adhesive prepared as described above was irradiated with 20 kGy and 40 kGy of γ rays using cobalt 60 as a radiation source.

(4) Peel force measurement test The radiation-treated adhesive body was cut into a size of 50 mm x 100 mm, the release sheet end was fixed to a tensile tester, and the adhesive sheet end was peeled by pulling the adhesive sheet end in a 180 ° direction at 300 mm / min. The force was measured. The peel force was measured in the same manner for the standard sample not irradiated with radiation, and the rate of increase with respect to the peel force of the standard sample was calculated, and the results are shown in Table 1.

(5) Residual adhesive strength measurement test After accelerating the irradiated adhesive body at 50 ° C. for 2 months, cutting it into a size of 25 mm × 55 mm and peeling it off, the adhesive layer side of the adhesive sheet was baked (Japan) Adhesive strength was measured by adhering to a test panel) with a 2 kg roll, and after 30 minutes, pulling in a 180 ° direction at 300 mm / min with a tensile tester. For the standard sample not treated at 50 ° C., the adhesive strength was measured in the same manner, and the residual adhesive strength was calculated as a relative value with the adhesive strength of the standard sample as 100%. The results are shown in Table 1.

Example 1
100 parts by mass of dimethylpolysiloxane having a viscosity of 400 mPa · s with both ends of the molecular chain blocked with vinyldimethylsiloxy groups as the component (A) described above, and a phenyl group with both ends of the molecular chain blocked with trimethylsilyl groups as the component (B) described above 1 part by weight of methylphenylsiloxane having a viscosity of 3,000 mPa · s containing 5 mol% of all substituents, and as a component (C), both ends of the molecular chain are blocked with trimethylsilyl groups, and the methyl group is 10 mol of all substituents. (D) as described above in which 2.8 parts by weight of methyl hydrogen siloxane with a viscosity of 20 mPa · s contained and 0.3 part by weight of 1-ethynyl-1-cyclohexanol as a control agent were stirred and made uniform. Addition and mixing of platinum and vinylsiloxane complex as components to 100ppm in terms of platinum, silicone composition It was obtained.

(Example 2)
In the formulation of Example 1, component (B) was blocked with a trimethylsilyl group at both ends of the molecular chain, and a silicone composition containing 1 part by weight of a methylphenylsiloxane having a viscosity of 450 mPa · s and containing 25 mol% of the phenyl group as a total substituent. I got a thing.

Example 3
In the formulation of Example 1, the silicone composition was prepared by using 10 parts by weight of methylphenylsiloxane having a viscosity of 450 mPa · s and containing 25 mol% of the phenyl group as the component (B) at both ends of the molecular chain and blocked with a trimethylsilyl group. I got a thing.

Example 4
In the formulation of Example 1, component (A) was blocked with a vinyldimethylsiloxy group, and a silicone composition containing 100 parts by mass of methylphenylsiloxane having a viscosity of 490 mPa · s and containing 1 mol% of phenyl groups as the total substituents was obtained. It was.

(Example 5)
In the formulation of Example 1, the composition (A) was prepared by using 100 parts by mass of dimethylpolysiloxane having a viscosity of 100 mPa · s in which both ends of the molecular chain were blocked with vinylmethylsiloxy groups.

(Comparative Example 1)
A silicone composition obtained by removing methylphenylsiloxane as the component (B) from the formulation of Example 1 was obtained.

(Comparative Example 2)
As component (A), 60 parts by mass of dimethylpolysiloxane having a viscosity of 400 mPa · s with both ends of the molecular chain blocked with vinyldimethylsiloxy groups and 32.7 mol% of the diphenylsiloxane unit with both ends of the molecular chain blocked with vinyldimethylsiloxy groups. Containing a viscosity of 2500 mPa · s, a methylphenylsiloxane containing both terminal vinyl groups with a viscosity of 2500 mPa · s. As a component (C), both ends of the molecular chain are blocked with trimethylsilyl groups and the viscosity containing 10 mol% of dimethylsiloxane units is 20 mPa · s. 3 parts by mass of methyl hydrogen siloxane, 1 part of 1-ethynyl-1-cyclohexanol as a control agent and a uniform mixture of 0.3 part by mass, and a complex of platinum and vinyl siloxane as component (D) in terms of platinum It added and mixed so that it might be set to 100 ppm, and the silicone composition was obtained.

(Comparative Example 3)
As component (A), 30 parts by mass of dimethylpolysiloxane having a viscosity of 400 mPa · s blocked at both ends of the molecular chain with vinyldimethylsiloxy groups, and both ends of the molecular chain blocked with vinyldimethylsiloxy groups, the phenyl group is all substituted. 70 parts by mass of methylphenylsiloxane containing vinyl groups with both ends having a viscosity of 2500 mPa · s containing 7 mol%, and (C) component containing 10 mol% of all substituents by blocking both ends of the molecular chain with trimethylsilyl groups 3 parts by mass of methyl hydrogen siloxane with a viscosity of 20 mPa · s, and 0.3 parts by mass of 1-ethynyl-1-cyclohexanol as a control agent are stirred and made uniform with a platinum-vinylsiloxane complex converted to platinum Was added and mixed so as to be 100 ppm to obtain a silicone composition.

(Comparative Example 4)
In addition to the blend of Comparative Example 2, as component (B), 1 part by mass of methylphenylsiloxane having a viscosity of 3,000 mPa · s and containing 5 mol% of the phenyl group is blocked with a trimethylsilyl group at the molecular chain end. And mixed to obtain a silicone composition.

  As is clear from the results in Table 1, the release sheet of the example in which the aryl group content in the silicone resin is within a desired range is suppressed from increasing in peel strength even after irradiation, The adhesive strength of the pressure-sensitive adhesive sheet after the 50 ° C. acceleration treatment is also high. On the other hand, the release sheet of Comparative Example 1 has a remarkable increase in peel strength after irradiation, and the release sheet of Comparative Example 2 has low residual adhesive strength of the pressure-sensitive adhesive sheet after 50 ° C. acceleration treatment.

  The release sheet of the present invention can be easily peeled off from the pressure-sensitive adhesive sheet even after radiation sterilization, and can suppress a decrease in the adhesive strength of the pressure-sensitive adhesive sheet. For this reason, if the peeling sheet of this invention is utilized, the adhesive body which can be used effectively especially in the medical hygiene field can be provided. Since the release sheet of the present invention can be produced at low cost by a simple method, the present invention has high industrial applicability.

DESCRIPTION OF SYMBOLS 1 Adhesive body 2 Release sheet 3 Adhesive sheet 11 Base material 12 Release agent layer 21 Base material 22 Adhesive layer

Claims (9)

A base material, and a release agent layer containing a silicone resin provided on the base material,
A release sheet used for radiation sterilization, characterized in that the ratio of aryl groups bonded to the siloxane chain of the silicone resin contained in the release agent layer is 0.01 to 9.99 mol%. The release agent layer is
(A) Silicone resin represented by the following general formula (1) containing 2 or more alkenyl groups and 0 to 9.98 mol% of aryl groups in one molecule 100 parts by mass

(In the general formula (1), each R independently represents a hydrogen atom, a hydroxyl group, or an organic group, and at least two R in one molecule of the silicone resin are alkenyl groups, and 0 to 9.98 mol% of the total R. Is an aryl group, x represents an integer of 1 or more.)
(B) The light peeling control agent which consists of a silicone resin which does not contain the alkenyl group represented by following formula (2) but contains an aryl group 0.1-30 mass parts

(In General Formula (2), R ′ each independently represents an organic group other than a hydrogen atom, a hydroxyl group, or an alkenyl group, and 0.01 to 50 mol% of all R ′ is an aryl group. Y is 1 or more. Represents an integer.)
(C) A silicone resin in which at least two hydrogen atoms are bonded to a silicon atom in one molecule 0.1 to 30 parts by mass (D) platinum group metal catalyst 0.1 to 5 parts by mass The release sheet used for radiation sterilization according to claim 1, wherein the proportion of aryl groups in the total silicone resin is 0.01 to 9.99 mol%.   The release sheet according to claim 1 or 2, wherein the silicone resin represented by the general formula (1) of (A) has a viscosity at 25 ° C of 50 to 5,000 mPa · s.   The release sheet according to any one of claims 1 to 3, wherein the silicone resin having an aryl group (B) has a viscosity of 50 to 1,000,000 mPa · s at 25 ° C.   The release sheet according to claim 1, wherein the release agent layer contains 10 to 500 ppm of a platinum group metal catalyst.   The release sheet according to any one of claims 1 to 5, wherein the release agent layer is a non-solvent type. All silicone resin contained in the release agent layer,

The release sheet according to any one of claims 1 to 6, wherein:
(A represents the number of siloxane units represented by the following general formula (3-1), b represents the number of siloxane units represented by the following general formula (3-2), and c represents the following general formula (3 -3) represents the number of siloxane units represented by d), and d represents the number of siloxane units represented by the following general formula (3-4).

(In the general formulas (3-1) to (3-4), R _{1 to} R ₈ each independently represents a hydrogen atom, a hydroxyl group, or an organic group other than an unsaturated hydrocarbon group. Q ₁ and Q ₂ each represent Independently represents an unsaturated hydrocarbon group having 2 to 6 carbon atoms.)   It is an adhesive body which has the structure which laminated | stacked the adhesive sheet which has a peeling sheet of any one of Claims 1-7, and a base material and the adhesive layer provided on this base material, Comprising: The said peeling An adhesive body in which the release agent layer of the sheet and the adhesive layer of the adhesive sheet are adhered.   The pressure-sensitive adhesive body according to claim 8, which has been sterilized by radiation.

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