JP2020196840A - Silicone adhesive, silicone adhesive composition and use thereof - Google Patents

Abstract

To provide a silicone adhesive that can achieve improved adhesiveness.SOLUTION: A silicone adhesive is obtained by an addition reaction between an Si-H group and an Si-H reactive group. The silicone adhesive contains a silicone resin R1. The silicone resin R1 satisfies at least one condition of: (a) having a propyl group; and (b) having a Q unit and an Si-H group and/or an Si-H reactive group.SELECTED DRAWING: Figure 1

Description

The present invention relates to a silicone-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive composition, and a pressure-sensitive adhesive sheet prepared by using the silicone-based pressure-sensitive adhesive or the silicone-based pressure-sensitive adhesive composition.

Generally, an adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid (viscoelastic body) state in a temperature range near room temperature, and has a property of adhering to an adherend by pressure. Taking advantage of this property, the pressure-sensitive adhesive is used in various fields, for example, in the form of a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive is arranged on at least one side of the support, or in the form of a base material-less pressure-sensitive adhesive sheet. The type of adhesive to be used is selected from various adhesives such as acrylic, rubber, and silicone, depending on the application, purpose, performance, and the like. For example, a silicone-based adhesive is excellent in heat resistance, chemical resistance, weather resistance, etc., and therefore, as a highly functional pressure-sensitive adhesive having excellent durability, a silicone-based pressure-sensitive adhesive is used on a film-like base material (support). In the form of the provided adhesive sheet, it is preferably used for surface protection sheets and other uses. The surface protection sheet is attached to the adherend via the adhesive, and is used for the purpose of protecting the adherend from scratches and stains during processing, transportation, and the like. It is desirable that the adhesive used for this purpose has an adhesive strength that does not peel off from the adherend during the protection period, and is removed without any trouble on the surface of the adherend such as adhesive residue after the protection period ends. .. Patent Document 1 is mentioned as a prior art document that discloses a silicone-based pressure-sensitive adhesive sheet that can be used for this purpose.

JP 2015-189778

Silicone used for the above-mentioned adhesive exhibits its characteristics as an adhesive by, for example, adding and reacting a Si—H group in a raw material with a Si—H reactive group such as a vinyl group to cure it. It is configured to do. The raw material can be obtained by obtaining or synthesizing a material called silicone gum or silicone resin. The above material may be a mixture of two or more. Moreover, a commercially available product can also be used. The adhesive properties of the silicone-based adhesives as described above can be adjusted by the composition of the raw materials used, but for example, if various adhesives with different adhesive strengths are required, change the adhesive type. If this is the case, various types of adhesives must be prepared and stocked, and the work load such as switching the raw materials used is large, which is not efficient. Fixing the composition of the base adhesive component, blending sub-ingredients, and adjusting the characteristics according to the blending amount of the sub-ingredients, responds to various requests while minimizing changes in the raw materials used. Easy and desirable.

For example, in Patent Document 1, a silicone-based pressure-sensitive adhesive (base pressure-sensitive adhesive component) is fixed, and a silicone-based release agent is added to the base pressure-sensitive adhesive component to have a predetermined initial adhesive force and to be applied. An addition-curable silicone-based adhesive sheet that can maintain light peelability even after a lapse of time has been proposed. By using such a silicone-based release agent, it is possible to reduce the adhesive force such as the adhesive force over time. On the other hand, looking at the improvement of adhesive strength, there is no known component that can increase the adhesive strength of silicone. Therefore, in order to meet the demand for increasing the adhesive strength of silicone-based adhesives to some extent, the adhesive is changed or a highly adhesive adhesive (base adhesive component) is used, and the adhesive strength lowering component is used there. Will be added to produce a product having a predetermined adhesive strength. However, changing the silicone-based pressure-sensitive adhesive type has problems such as an increase in raw material stock as described above. In addition, some of the adhesive strength reducing components (for example, silicone oil) are likely to bleed out from the adhesive and cause contamination of the adherend, which may not be a practical solution.

The present invention has been created in view of the above circumstances, and an object of the present invention is to provide a silicone-based pressure-sensitive adhesive capable of improving the adhesive strength by using an adhesive strength-improving component. Another object of the present invention is to provide a pressure-sensitive adhesive sheet formed by using a silicone-based pressure-sensitive adhesive, and to provide a silicone-based pressure-sensitive adhesive composition for preparing the above-mentioned silicone-based pressure-sensitive adhesive.

According to the present specification, a silicone-based pressure-sensitive adhesive obtained by an addition reaction of a Si—H group and a Si—H reactive group is provided. Silicone resin R1 is contained in the silicone-based pressure-sensitive adhesive. The silicone resin R1 satisfies at least one of (a) having a propyl group; and (b) having a Q unit and having a Si—H group and / or a Si—H reactive group.

As a result of diligent studies, the present inventors have discovered a silicone resin having a specific chemical structure, that is, the silicone resin R1 as a component capable of improving the adhesive strength of a silicone-based pressure-sensitive adhesive. According to the addition-curing type silicone-based pressure-sensitive adhesive containing the silicone resin R1, the adhesive strength can be improved. Further, the addition-curing type silicone-based pressure-sensitive adhesive tends to have lower adhesive strength than the peroxide-curing type pressure-sensitive adhesive. The adhesive strength improving effect of the addition-curable silicone-based adhesive, which has relatively low adhesiveness, is expected to expand its application range, and has a great practical advantage. Further, according to the above configuration, for example, by blending the silicone resin R1 without changing the base material of the silicone-based pressure-sensitive adhesive (also referred to as “base silicone-based pressure-sensitive adhesive component”, for example, it may be a one-component material). Since the adhesive strength can be improved, it becomes easier to respond to various requests at the production site, and the production efficiency is also improved. In addition, in this specification, "base material" is a term used in a relative meaning indicating a relationship with silicone resin R1, and is said to be applicable except that it is a base material (essential component) of a silicone-based adhesive. It is not limitedly interpreted including the content ratio in the silicone-based pressure-sensitive adhesive.

In some preferred embodiments, the silicone resin R1 has a Q unit and has a propyl group. Further, the propyl group is bonded to the Q unit. By blending the silicone resin R1 having the above structure, the effect of improving the adhesive strength by the technique disclosed herein is preferably exhibited.

In some preferred embodiments, the weight ratio of the silicone resin R1 to the silicone-based pressure-sensitive adhesive is 1 to 50% by weight. By using the silicone resin R1 in a predetermined amount or more, the effect of adding the silicone resin R1 is preferably exhibited. Further, by setting the content of the silicone resin R1 to a predetermined value or less, the characteristics based on the base silicone-based pressure-sensitive adhesive component can be preferably maintained. Further, when the weight ratio of the silicone resin R1 is in the range of 1 to 50% by weight, the adhesive strength can be increased according to the increase in the amount of the silicone resin R1. This means that the target adhesive strength can be predicted and set by adjusting the content of the silicone resin R1, which is practically meaningful.

Further, according to the present specification, there is provided a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of any of the silicone-based pressure-sensitive adhesives disclosed herein. Since the adhesive strength of this pressure-sensitive adhesive sheet can be improved by blending the silicone resin R1, the pressure-sensitive adhesive sheet can well meet the demand for improving the adhesive strength.

The pressure-sensitive adhesive sheet according to a typical embodiment can have a 180-degree peel strength with respect to a glass plate of 1 gf / 25 mm or more. By applying the technique disclosed herein to the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet exhibiting the above-mentioned adhesive strength, the desired increase in adhesive strength can be preferably realized.

Further, according to the present specification, a silicone-based pressure-sensitive adhesive composition containing an addition-curable silicone is provided. The silicone-based pressure-sensitive adhesive composition contains a silicone resin R1. The silicone resin R1 satisfies at least one of (a) having a propyl group; and (b) having a Q unit and having a Si—H group and / or a Si—H reactive group. According to the pressure-sensitive adhesive composition having the above structure, the adhesive strength of the pressure-sensitive adhesive can be improved.

In some preferred embodiments, the silicone resin R1 has a Q unit and has a propyl group. Further, the propyl group is bonded to the Q unit. Alternatively, the weight ratio of the silicone resin R1 in the silicone-based pressure-sensitive adhesive composition is preferably 1 to 50% by weight based on the solid content.

Further, according to the present specification, there is provided a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from any of the silicone-based pressure-sensitive adhesive compositions disclosed herein. According to this pressure-sensitive adhesive sheet, the adhesive strength can be improved by blending the silicone resin R1, so that the demand for improving the adhesive strength can be well met.

Further, according to the present specification, there is provided a pressure-sensitive adhesive sheet provided with a silicone-based pressure-sensitive adhesive layer formed by an addition reaction between a Si—H group and a Si—H reactive group. In the pressure-sensitive adhesive layer, an adhesive strength improving component (typically, the above-mentioned silicone resin R1) is chemically bonded to a cured silicone product contained in the silicone-based pressure-sensitive adhesive layer, or the cured silicone product. Is included in the unbound state. The pressure-sensitive adhesive sheet has a formula: _RPS (%) = A / B × 100; (In the formula, A is a 180-degree peel strength [gf / 25 mm] of the pressure-sensitive adhesive sheet with respect to the glass plate, and B is The adhesive strength change rate (R) represented by 180 degree peel strength [gf / 25 mm] of the control adhesive sheet with respect to the glass plate, which is the same as the adhesive sheet except that the adhesive layer does not contain the adhesive strength improving component. _PS ) is 110% or more.

It is sectional drawing which shows one structural example of the adhesive sheet schematically.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the practice of the present invention shall be based on the teachings regarding the practice of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art.
In the following drawings, members / parts that perform the same action may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are schematically for the purpose of clearly explaining the present invention, and do not accurately represent the sizes and scales of the products and parts actually provided.

As described above, the term "adhesive" as used herein refers to a material that exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature and has the property of easily adhering to an adherend by pressure. ..

<Silicone adhesive composition>
The silicone-based pressure-sensitive adhesive composition disclosed herein is an addition-curable silicone-based pressure-sensitive adhesive composition containing an addition-curable silicone. Here, the "additionally curable silicone" refers to a silicone that can be additionally cured, and specifically, a silicone in a state before being cured by an addition reaction. The addition reaction refers to an addition reaction between a Si—H group and a Si—H reactive group present in the silicone. The Si—H group refers to a hydrogen (H) group directly bonded to a Si atom, and the Si—H reactive group is a chemical reaction (specifically, an addition reaction) with the Si—H group. A group capable of forming a bond (specifically, a covalent bond). Further, in the present specification, the "additionally curable silicone-based pressure-sensitive adhesive composition" can be cured by an addition reaction between a Si—H group and a Si—H reactive group existing in the composition. It refers to a silicone-based pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition becomes a silicone-based pressure-sensitive adhesive after being cured by an addition reaction. In the techniques disclosed herein, the terms addition reaction type and addition curing type are used to indicate the form of the curing reaction and to distinguish it from the peroxide curing type which is cured by an organic peroxide. According to the addition reaction type, no by-products are usually generated during curing, and problems such as odor and corrosion are unlikely to occur. The silicone-based pressure-sensitive adhesive composition may be either a one-component type or a two-component type.

The silicone-based pressure-sensitive adhesive compositions disclosed herein are typically one or more add-curable silicones (typically one or more selected from silicone gums and silicone resins, such as silicone gums). Can include. Such a silicone-based pressure-sensitive adhesive composition may further contain one or more silicone resins. In some preferred embodiments, the silicone-based pressure-sensitive adhesive composition may comprise one or more silicone gums and one or more silicone resins.

(Silicone gum)
As the silicone gum, a chain silicone polymer having a structure represented by the general formula (R ₂ SiO) _n can be typically used. Here, R in the above formula is hydrogen (hydrogen), or the same or different organic group, and is typically a hydrocarbon group (for example, a hydrocarbon group having 1 to about 10 carbon atoms). possible. Non-limiting examples of the hydrocarbon group that can be adopted as R include an alkyl group (typically an alkyl group having about 1 to 3 carbon atoms, for example, a methyl group), an alkenyl group (typically a vinyl group), and the like. Aaryl group (for example, phenyl group, naphthyl group), arylalkyl group, cycloalkyl group (for example, cyclohexyl group), and at least a part of hydrogen present in those groups are substituted with halogen, amino group, hydroxyl group, cyano group and the like. Things etc. can be included. The silicone gum may contain one or more of the organic groups (typically hydrocarbon groups) exemplified above as the organic group bonded to the silicon atom. The silicone gum is typically linear and may be branched. One type of silicone gum may be used alone, or two or more types may be used in combination.

The ratio of the repeating unit (R ₂ SiO) to the silicone gum can be typically about 50 mol% or more, about 70 mol% or more is appropriate, and preferably about 80 mol% or more. , It may be about 85 mol% or more (for example, about 90 mol% or more). The upper limit of the ratio of the repeating unit (R ₂ SiO) to the silicone gum is usually less than 100 mol% (for example, less than 99 mol%) because the polymer end can be (R ₃ SiO).
In the present specification, the ratio (mol%) of a specific repeating unit (for example, repeating unit (R ₂ SiO)) in a silicone polymer such as silicone gum or silicone resin is the molar of all repeating units constituting the silicone polymer. It refers to the ratio (mol%) of the number of moles of the specific repeating unit (for example, repeating unit (R ₂ SiO)) to the number. The mol% can be determined from the ratio of the number of the specific repeating units (number of units) to the total number of repeating units (number of units) constituting the polymer, based on one molecule of the silicone polymer. The "repetitive unit" of the silicone polymer referred to here may also be a unit derived from the monomer.

In some embodiments, in the silicone gum, the repeating unit (R ₂ SiO) in the above general formula is mainly a dialkylsiloxane unit (also referred to as a dialkyl type D unit; the D unit will be described later) and a diarylsiloxane unit (diaryl). It can be a silicone polymer that is one or more units selected from (also referred to as type D units) and monoalkyl monoarylsiloxane units (also referred to as monoalkyl monoaryl type D units). The total proportion of the dialkylsiloxane unit, the diarylsiloxane unit, and the monoalkylmonoarylsiloxane unit among the repeating units contained in the silicone gum is typically more than 50 mol%, which is about 60 mol% or more. It may be about 70 mol% or more, and may be about 80 mol% or more. The alkyl group described above can typically be a methyl group and the aryl group can typically be a phenyl group.

In some preferred embodiments, the silicone gum is a silicone polymer in which the repeating unit (R ₂ SiO) in the general formula is primarily a dimethylsiloxane unit ((CH ₃ ) ₂ SiO; also referred to as a dimethyl type D unit). obtain. The proportion of the dimethylsiloxane unit in the repeating unit contained in the silicone gum is typically more than 50 mol%, may be about 60 mol% or more, or may be about 70 mol% or more. , It may be about 80 mol% or more.

The silicone gum disclosed herein can typically be an addition reactive silicone polymer. Therefore, the silicone gum may have a Si—H reactive group. The Si—H reactive group may be directly bonded to Si constituting the main chain skeleton of the silicone gum, or may be present in the side chain bonded to the Si. In a preferred embodiment, the Si—H reactive group is directly attached to Si in the main chain of the silicone gum. The silicone gum may contain a Si—H reactive group-containing siloxane unit in which at least one of R of the repeating unit (R ₂ SiO) in the above general formula is a Si—H reactive group. Examples of the Si—H reactive group include alkenyl groups such as vinyl group, allyl group, hexenyl group and octenyl group; (meth) acryloyl such as acryloyloxymethyl group, acryloyloxypropyl group, methacryloyloxymethyl group and methacryloyloxypropyl group. Oxyalkyl group; The Si—H reactive group is preferably a vinyl group. Examples of the Si—H reactive group-containing siloxane unit include a monoalkyl monoalkenylsiloxane unit such as a monoalkylmonovinylsiloxane unit; and a dialkenylsiloxane unit such as a divinylsiloxane unit. The silicone gum may have one or more of the various Si—H reactive groups described above. Preferable examples include monoalkyl monovinyl siloxane units such as methyl vinyl siloxane units.

The proportion of the Si—H reactive group-containing siloxane unit among the repeating units contained in the silicone gum is not particularly limited, and can be approximately 0.1 mol% or more, and approximately 0.5 mol%. The above is appropriate, and from the viewpoint of cohesive force after curing, it is preferably about 1 mol% or more, and may be about 1.5 mol% or more (for example, about 2 mol% or more). The upper limit of the proportion of the Si—H reactive group-containing siloxane unit among the repeating units contained in the silicone gum is not particularly limited because it is determined according to the wettability and the target adhesive strength, and is approximately the same. It can be 10 mol% or less, about 5 mol% or less is appropriate, and it may be about 3 mol% or less.

Since the silicone gum disclosed herein can typically be an addition-reactive silicone polymer, the silicone gum can typically have a Si—H group. The Si—H group may be in the form of hydrogen (H) bonded to Si constituting the main chain of the silicone gum, or may be in the form of H bonded to Si in the side chain. The silicone gum may contain a Si—H group-containing siloxane unit in which at least one of R of the repeating unit (R ₂ SiO) in the above general formula is hydrogen (hydrogen). As the Si—H group-containing siloxane unit, an alkylhydrogensiloxane unit such as a methylhydrogensiloxane unit can be mentioned as a preferable example.

The ratio of the Si—H group-containing siloxane unit to the repeating unit contained in the silicone gum is not particularly limited, and may be approximately 0.01 mol% or more, and approximately 0.1 mol% or more. It is suitable, and is preferably about 0.2 mol% or more, and may be about 0.3 mol% or more (for example, about 0.5 mol% or more) from the viewpoint of cohesive force after curing. The upper limit of the proportion of the Si—H group-containing siloxane unit among the repeating units contained in the silicone gum is not particularly limited because it is determined according to the wettability and the target adhesive strength, and is approximately 10 mol. % Or less, about 5 mol% or less is appropriate, and may be about 3 mol% or less (for example, about 1 mol% or less).

In an embodiment in which the silicone gum contains at least one of a Si—H reactive group-containing siloxane unit and a Si—H group-containing siloxane unit, the Si—H reactive group-containing siloxane unit and the Si—H reactive group-containing siloxane unit among the repeating units contained in the silicone gum. The ratio occupied by the total of the Si—H group-containing siloxane units is not particularly limited, and may be about 0.1 mol% or more, about 0.5 mol% or more is appropriate, and the cohesive force after curing, etc. From the above viewpoint, it is preferably about 1 mol% or more, and may be about 1.5 mol% or more (for example, about 2 mol% or more). The upper limit of the ratio of the total of the Si—H reactive group-containing siloxane unit and the Si—H group-containing siloxane unit among the repeating units contained in the silicone gum depends on the wettability and the target adhesive strength. Since it is determined, it is not particularly limited, and it can be about 10 mol% or less, about 5 mol% or less is appropriate, and it may be about 3 mol% or less.

In an embodiment in which the silicone gum contains a Si—H reactive group-containing siloxane unit and a Si—H group-containing siloxane unit, the molar ratio of the Si—H reactive group-containing siloxane unit to the Si—H group-containing siloxane unit (Si—H). The reactive group-containing siloxane unit (Si—H group-containing siloxane unit) can be appropriately set according to the desired level of addition curing, and is not limited to a specific range, for example, 1:99 to 99: 1. 10:90 to 98: 2 is suitable, preferably 30:70 to 95: 5, more preferably 50:50 to 90:10, and 60:40 to 85:15. , 70:30 to 80:20.

In the techniques disclosed herein, the weight average molecular weight (Mw) of the silicone gum is 5 × 10 ⁴ or more, about 10 × 10 ⁴ or more is appropriate, preferably about 15 × 10 ⁴ or more, more preferably about. It is 25 × 10 ⁴ or more, and may be approximately 35 × 10 ⁴ or more (for example, 40 × 10 ⁴ or more). Further, the upper limit of Mw of the silicone gum is not particularly limited, and for example, about 150 × 10 ⁴ or less is suitable, preferably about 100 × 10 ⁴ or less, and about 80 × 10 ⁴ or less (for example, about 60 × 10 ^4). The following) may be used.

The dispersity (Mw / Mn) of the silicone gum is not particularly limited and can be about 10 or less, about 7 or less is appropriate, and from the viewpoint of exhibiting homogeneous performance, it is preferably about 5 or less. Yes, it may be about 3 or less. Further, the Mw / Mn is usually larger than 1, and may be about 1.3 or more (for example, about 1.7 or more). The degree of dispersion is the degree of dispersion (Mw / Mn) expressed by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn).

In addition, in this specification, Mw and Mw / Mn of the silicone polymer refer to the standard polystyrene conversion value obtained by GPC (gel permeation chromatography). Toluene shall be used as the eluent. As the GPC apparatus, for example, a model name "HLC-8320GPC" (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) can be used.

The weight ratio of the silicone gum in the silicone-based pressure-sensitive adhesive composition can be about 30% by weight or more based on the solid content, and about 40% by weight or more is appropriate. From the viewpoint of exhibiting the desired adhesive properties, the weight ratio of the silicone gum in the silicone-based pressure-sensitive adhesive composition is based on the solid content, preferably about 50% by weight or more, and may be about 70% by weight or more. It may be about 80% by weight or more. Further, the weight ratio of the silicone gum in the silicone-based pressure-sensitive adhesive composition is appropriately about 99% by weight or less based on the solid content, and is preferably about 95% by weight or less from the viewpoint of obtaining the effect of containing the silicone resin R1. It may be about 90% by weight or less. In the present specification, the weight ratio of the contained component in the silicone-based pressure-sensitive adhesive composition based on the solid content is synonymous with the weight ratio of the contained component in the silicone-based pressure-sensitive adhesive described later, unless otherwise specified.

(Silicone resin R1)
The silicone-based pressure-sensitive adhesive composition disclosed herein is characterized by containing a silicone resin R1. Silicone resin R1 satisfies at least one of (a) having a propyl group; and (b) having a Q unit and having a Si—H group and / or a Si—H reactive group. By incorporating the silicone resin R1 in an addition-curable silicone-based pressure-sensitive adhesive composition, the adhesive strength can be improved. As the silicone resin R1, one kind of compound (silicone) corresponding to the silicone resin R1 can be used alone or in combination of two or more kinds.

In the present specification, the "silicone resin" is a silicone polymer having a three-dimensional structure, and may have a degree of branching of a predetermined value or more, including, for example, T units and / or Q units described later. The silicone resin may preferably contain Q units. The silicone resin can also be defined as having a molecular weight range lower than that of the silicone gum described above. The silicone resin includes what is called a silicone oligomer.

The silicone resin R1 has an M unit represented by the general formula "R ₃ SiO _1/2 ", a D unit represented by the general formula "R ₂ SiO _2/2 " (that is, R ₂ SiO), and a general formula "RSi _{3 /} ". T unit represented by ₂ ", and the general formula" having at least one unit selected from Q unit represented by SiO _4/2 "(co) silicone resin consisting of an organopolysiloxane consisting of polymers and the like .. Here, R in the M unit, D unit and T unit represents a hydrogen (hydrogen) group, or the same or different organic group. The organic group is typically a hydrocarbon group having 1 to about 10 carbon atoms. Non-limiting examples of the hydrocarbon group that can be adopted as R include an alkyl group (typically an alkyl group having about 1 to 3 carbon atoms, for example, a methyl group), an alkenyl group (for example, a vinyl group), and an aryl group (typically, an alkyl group and an aryl group). For example, a phenyl group, a naphthyl group), an arylalkyl group, a cycloalkyl group (for example, a cyclohexyl group), and at least a part of hydrogen existing in those groups is substituted with a halogen, an amino group, a hydroxyl group, a cyano group, or the like. Can be included. The silicone resin R1 may contain one or more of the groups exemplified above as the organic group bonded to the silicon atom.

In some preferred embodiments, the silicone resin R1 may contain Q units. In this embodiment, the amount of Q units in the silicone resin R1 is not particularly limited, and the total amount of M units, D units, T units and Q units contained in the silicone resin R1 (based on the number of Si atoms) is 100 mol%. Then, it can be about 10 mol% or more, about 25 mol% or more is suitable, and preferably about 40 mol% or more (for example, about 50 mol% or more). The amount of Q units in the silicone resin R1 can be, for example, about 80 mol% or less, about 70 mol% or less is appropriate, and preferably about 60 mol% or less (for example, about 55 mol% or less). .. By setting the ratio of Q units within a predetermined range, the silicone resin R1 has an appropriate molecular weight lower than that of the silicone gum and is likely to contribute to the improvement of the adhesive strength, although it is not particularly limitedly interpreted. It is thought that it will be.

In some embodiments, the silicone resin R1 may contain M units. As a preferable example of the above M unit, a trialkylsiloxane unit (for example, a trimethylsiloxane unit) in which R in the general formula "R ₃ SiO _1/2 " is an alkyl group such as a methyl group or an alkenyl group such as a vinyl group. , Dialkyl monoalkenylsiloxane unit (for example, dimethylmonovinylsiloxane unit), monoalkyldialkenylsiloxane unit and the like. In this embodiment, the amount of M units in the silicone resin R1 is not particularly limited, and the total amount of M units, D units, T units and Q units contained in the silicone resin R1 (based on the number of Si atoms) is 100 mol%. Then, it can be about 10 mol% or more, about 20 mol% or more is suitable, and preferably about 30 mol% or more (for example, about 35 mol% or more). The amount of M units in the silicone resin R1 can be, for example, about 80 mol% or less, about 60 mol% or less is appropriate, and preferably about 50 mol% or less (for example, about 45 mol% or less). .. By setting the ratio of M units within a predetermined range, the silicone resin R1 is easily compatible with the adhesive and has an appropriate molecular weight lower than that of the silicone gum, and easily contributes to the improvement of the adhesive strength. it is conceivable that.

In some preferred embodiments, the silicone resin R1 may include M units and Q units as the main constituent units (units that occupy 50 mol% or more of the total constituent units). A resin having such a structure is generally referred to as an MQ resin. In the embodiment in which the silicone resin R1 is an MQ resin, the total amount of M units and Q units is not particularly limited, and the total amount of M units, D units, T units and Q units contained in the silicone resin R1 (Si atom number). When the standard) is 100 mol%, it can be about 70 mol% or more, about 75 mol% or more is appropriate, and preferably about 80 mol% or more (for example, about 90 mol% or more). The total amount of the M unit and the Q unit in the silicone resin R1 is 100 mol% or less, for example, it can be about 99 mol% or less, and about 95 mol% or less is appropriate. By setting the total ratio of the M unit and the Q unit within a predetermined range, the silicone resin R1 has an appropriate molecular weight lower than that of the silicone gum and improves the adhesive strength, although it is not particularly limitedly interpreted. It is thought that it will be easier to contribute to.

In some embodiments, the silicone resin R1 may contain D units or T units. In the embodiment in which the silicone resin R1 contains D units, the amount of D units in the silicone resin R1 is 100 mol, which is the total amount of M units, D units, T units and Q units contained in the silicone resin R1 (based on the number of Si atoms). When it is%, it can be about 1 mol% or more, about 2 mol% or more is appropriate, and preferably about 3 mol% or more (for example, about 5 mol% or more). The amount of the D unit in the silicone resin R1 can be, for example, about 20 mol% or less, about 15 mol% or less is appropriate, and preferably about 12 mol% or less (for example, about 10 mol% or less). .. Further, in the embodiment in which the silicone resin R1 contains T units, the amount of T units in the silicone resin R1 can be in the same range as the amount of the D units. Alternatively, in some other embodiments, the silicone resin R1 may include D units and T units as main constituent units (units that occupy 50 mol% or more of all constituent units). A resin having such a structure is generally referred to as a DT resin.

In some preferred embodiments, the silicone resin R1 has a propyl group. The propyl group may be either an n-propyl group or an isopropyl group, and is preferably an isopropyl group. It is considered that the improvement of the adhesive strength by the technique disclosed herein is realized by the silicone-based pressure-sensitive adhesive containing the silicone resin R1 having a propyl group. The propyl group may be bonded to any of M units, D units, T units, and Q units that can constitute the silicone resin R1, and is preferably bonded to the Q unit. That is, the propyl group may be bonded to a Si atom constituting the Q unit in the form of a propoxy group (n-propoxy group, isopropoxy group).

In some preferred embodiments, the silicone resin R1 has at least one selected from Si—H groups and Si—H reactive groups. By including the silicone resin R1 having at least one selected from the Si—H group and the Si—H reactive group in the addition-curable silicone-based pressure-sensitive adhesive, the adhesive strength can be improved. Although not particularly limitedly interpreted, it is considered that the silicone resin R1 having a Si—H group or a Si—H reactive group is incorporated into the silicone-based pressure-sensitive adhesive by an addition reaction, and such existence It is considered that the morphology exhibits its characteristics without migrating to the surface on the adherend side. The technology disclosed herein is not limited to the above interpretation. In some embodiments, the silicone resin R1 has a Si—H group. In this embodiment, the silicone resin R1 may typically contain Si—H group-containing siloxane units. In some other embodiments, the silicone resin R1 has a Si—H reactive group. In this embodiment, the silicone resin R1 may typically contain Si—H reactive group-containing siloxane units. In some preferred embodiments, the silicone resin R1 has a Si—H group and a Si—H reactive group. In this aspect, the silicone resin R1 may typically contain a Si—H group-containing siloxane unit and a Si—H reactive group-containing siloxane unit.

In the embodiment in which the silicone resin R1 has a Si—H group, the hydrogen atom constituting the Si—H group may be bonded to any of M units, D units, and T units, and is preferably bonded to the D unit. doing. The Si—H group can be introduced into the silicone resin R1 in the form of a Si—H group-containing siloxane unit (for example, (RHSiO)). Examples of the Si—H group-containing siloxane unit include alkylhydrogensiloxane units such as methylhydrogensiloxane units.

In the embodiment in which the silicone resin R1 has a Si—H group, the ratio of the Si—H group-containing siloxane unit to the total number of repeating units contained in the silicone resin R1 can be approximately 0.1 mol% or more, and is approximately 0.1 mol% or more. 1 mol% or more is suitable, and from the viewpoint of cohesive force after curing, it is preferably about 3 mol% or more, and may be about 5 mol% or more. The upper limit of the ratio of the Si—H group-containing siloxane unit to the total number of repeating units contained in the silicone resin R1 is not particularly limited because it is determined according to the wettability and the target adhesive strength, and is approximately 20 mol. % Or less, about 15 mol% or less is appropriate, and may be about 10 mol% or less.

In the embodiment in which the silicone resin R1 has a Si—H reactive group, the Si—H reactive group that the silicone resin R1 can have is one or 2 of the groups exemplified as the Si—H reactive group in the silicone gum. More than a seed can be adopted without any particular limitation. The Si—H reactive group is preferably a vinyl group. In the embodiment in which the silicone resin R1 has a Si—H reactive group-containing siloxane unit, the silicone resin R1 is a monoalkyl monoalkenyl siloxane unit such as a monoalkyl monovinyl siloxane unit as a Si—H reactive group-containing siloxane unit; divinyl. It may have a dialkenylsiloxane unit such as a siloxane unit. Preferable examples include monoalkyl monovinyl siloxane units such as methyl vinyl siloxane units.

In the embodiment in which the silicone resin R1 has a Si—H reactive group, the ratio of the Si—H reactive group-containing siloxane unit to the total number of repeating units contained in the silicone resin R1 shall be approximately 0.1 mol% or more. It is suitable to be about 1 mol% or more, preferably about 3 mol% or more, and may be about 5 mol% or more from the viewpoint of cohesive force after curing. The upper limit of the ratio of the Si—H reactive group-containing siloxane unit to the total number of repeating units contained in the silicone resin R1 is not particularly limited because it is determined according to the wettability and the target adhesive strength, and is approximately the same. It can be 20 mol% or less, about 15 mol% or less is suitable, and it may be about 10 mol% or less.

The Mw of the silicone resin R1 is not particularly limited, and can be less than 5 × 10 ⁴ , and is preferably about 2 × 10 ⁴ or less, and is preferable from the viewpoint of preferably exerting the effects of the techniques disclosed herein. Is about 1 × 10 ⁴ or less, more preferably about 8 × 10 ³ or less (for example, about 6 × 10 ³ or less). The lower limit of Mw of the silicone resin R1 is not particularly limited, and is appropriately about 1 × 10 ³ or more, preferably about 1.5 × 10 ³ or more, more preferably about 2 × 10 ³ or more, still more preferably. It is about 3 × 10 ³ or more. Silicone resin R1, the molecular weight may be a silicone oligomer of less than 1 × 10 ^3.

The dispersity (Mw / Mn) of the silicone resin R1 is not particularly limited and can be about 10 or less, preferably about 5 or less, preferably about 3 or less, and may be about 2 or less. Further, the Mw / Mn is usually larger than 1, and may be about 1.3 or more (for example, about 1.5 or more).

Examples of a commercially available product that can be the silicone resin R1 include the trade name "KS-3800" manufactured by Shin-Etsu Chemical Co., Ltd. The examples of the commercially available products do not limit the silicone resin R1 that can be used for the pressure-sensitive adhesive sheet disclosed herein.

The amount of the silicone resin R1 used can be an appropriate amount according to the desired adhesive strength, and is not limited to a specific range. The weight ratio of the silicone resin R1 in the silicone-based pressure-sensitive adhesive composition can be approximately 0.1% by weight or more based on the solid content, and approximately 1% by weight or more is appropriate. By using the silicone resin R1 in a predetermined amount or more, the effect of adding the silicone resin R1 is preferably exhibited. From such a viewpoint, the weight ratio of the silicone resin R1 in the silicone-based pressure-sensitive adhesive composition is based on the solid content, preferably about 2% by weight or more, may be about 3% by weight or more, and is about 5% by weight. It may be more than (for example, about 8% by weight or more), about 10% by weight or more, about 15% by weight or more, about 20% by weight or more, about 25% by weight or more, or about 30% by weight or more. Good. Further, the weight ratio of the silicone resin R1 in the silicone-based pressure-sensitive adhesive composition is appropriately about 50% by weight or less based on the solid content, and is preferably about 40% by weight or less from the viewpoint of maintaining the characteristics of the silicone-based pressure-sensitive adhesive. It may be about 30% by weight or less, about 20% by weight or less, or about 10% by weight or less (for example, about 5% by weight or less).

(Silicone resin R2)
The silicone-based pressure-sensitive adhesive composition disclosed herein may contain one or more of silicone resins (hereinafter, also referred to as "silicone resin R2") that do not correspond to silicone resin R1 as optional components.

The silicone resin R2 has an M unit represented by the general formula "R ₃ SiO _1/2 ", a D unit represented by the general formula "R ₂ SiO _2/2 " (that is, R ₂ SiO), and a general formula "RSi _{3 /} ". T unit represented by ₂ ", and the general formula" having at least one unit selected from Q unit represented by SiO _4/2 "(co) silicone resin consisting of an organopolysiloxane consisting of polymers and the like .. Here, R in the M unit, D unit and T unit represents a hydrogen (hydrogen) group, or the same or different organic group. The organic group is typically a hydrocarbon group having 1 to about 10 carbon atoms. Non-limiting examples of the hydrocarbon group that can be adopted as R include an alkyl group (typically an alkyl group having about 1 to 2 carbon atoms, for example, a methyl group), an alkenyl group, and an aryl group (for example, a phenyl group and a naphthyl). Groups), arylalkyl groups, cycloalkyl groups (eg, cyclohexyl groups) and the like can be included. The silicone resin R2 may contain one or more of the groups exemplified above as the organic group bonded to the silicon atom.

In some embodiments, the silicone resin R2 may contain Q units. In this embodiment, the amount of Q units in the silicone resin R2 is not particularly limited, and the total amount of M units, D units, T units and Q units contained in the silicone resin R1 (based on the number of Si atoms) is 100 mol%. Then, it can be about 10 mol% or more, about 25 mol% or more is suitable, and preferably about 40 mol% or more (for example, about 50 mol% or more). The amount of Q units in the silicone resin R2 can be, for example, about 80 mol% or less, about 70 mol% or less is appropriate, and preferably about 60 mol% or less (for example, about 55 mol% or less). .. In some other embodiments, the amount of Q units in the silicone resin R2 can be approximately 0.1 mol% or greater, with approximately 1 mol% or greater being appropriate, preferably approximately 3 mol% or greater. .. In this embodiment, the amount of Q units in the silicone resin R2 may be, for example, about 50 mol% or less, about 30 mol% or less, or about 10 mol% or less.

In some embodiments, the silicone resin R2 may contain M units. A preferable example of the above M unit is a trialkylsiloxane unit (for example, a trimethylsiloxane unit) in which all Rs in the general formula “R ₃ SiO _1/2 ” are alkyl groups. In this embodiment, the amount of M units in the silicone resin R2 is not particularly limited, and the total amount of M units, D units, T units and Q units contained in the silicone resin R2 (based on the number of Si atoms) is 100 mol%. At that time, it can be about 10 mol% or more, may be about 20 mol% or more, or may be about 30 mol% or more (for example, about 35 mol% or more). The amount of M units in the silicone resin R2 can be, for example, about 80 mol% or less, may be about 60 mol% or less, or may be about 50 mol% or less (for example, about 45 mol% or less).

In some embodiments, the silicone resin R2 can be an MQ resin comprising M units and Q units as the main constituent units (units that occupy 50 mol% or more of the total constituent units). In the embodiment in which the silicone resin R2 is an MQ resin, the total amount of M units and Q units is not particularly limited, and the total amount of M units, D units, T units and Q units contained in the silicone resin R2 (Si atom number). When the standard) is 100 mol%, it can be about 70 mol% or more, about 75 mol% or more is appropriate, and preferably about 80 mol% or more (for example, about 90 mol% or more). The total amount of the M unit and the Q unit in the silicone resin R2 is 100 mol% or less, for example, it may be about 99 mol% or less, or may be about 95 mol% or less.

In some embodiments, the silicone resin R2 may contain D units or T units. In the embodiment in which the silicone resin R2 contains D units, the amount of D units in the silicone resin R2 is 100 mol based on the total amount of M units, D units, T units and Q units contained in the silicone resin R1 (based on the number of Si atoms). When it is%, it can be about 1 mol% or more, may be about 2 mol% or more, or may be about 3 mol% or more (for example, about 5 mol% or more). The amount of the D unit in the silicone resin R2 is not particularly limited, and may be, for example, about 20 mol% or less, may be about 15 mol% or less, and may be about 12 mol% or less (for example, about 10 mol%). The following) may be used. Further, in the embodiment in which the silicone resin R2 contains T units, the amount of T units in the silicone resin R2 can be in the same range as the amount of the D units. Alternatively, in some other embodiments, the silicone resin R2 may include D units and T units as main constituent units (units that occupy 50 mol% or more of all constituent units). A resin having such a structure is generally referred to as a DT resin.

The Mw of the silicone resin R2 is not particularly limited and can be less than 5 × 10 ⁴ , and is preferably about 2 × 10 ⁴ or less, preferably about 1 × 10 ⁴ or less, and more preferably about 8 × 10. ^{It is 3} or less (for example, about 6 × 10 ³ or less). The lower limit of Mw of the silicone resin R2 is not particularly limited, and is appropriately about 1 × 10 ³ or more, preferably about 1.5 × 10 ³ or more, more preferably about 2 × 10 ³ or more, still more preferably. It is about 3 × 10 ³ or more. Silicone resin R2, the molecular weight may be a silicone oligomer of less than 1 × 10 ^3.

The dispersity (Mw / Mn) of the silicone resin R2 is not particularly limited and can be about 10 or less, preferably about 5 or less, preferably about 3 or less, and may be about 2 or less. Further, the Mw / Mn is usually larger than 1, and may be about 1.3 or more (for example, about 1.7 or more).

The amount of the silicone resin R2 used is not particularly limited. For example, in the embodiment in which the silicone-based pressure-sensitive adhesive composition contains the silicone resin R2, the weight ratio of the silicone resin R2 in the silicone-based pressure-sensitive adhesive composition can be approximately 0.1% by weight or more based on the solid content. It may be about 1% by weight or more, about 3% by weight or more, about 5% by weight or more, or about 10% by weight or more. Further, the weight ratio of the silicone resin R2 in the silicone-based pressure-sensitive adhesive composition is appropriately about 30% by weight or less based on the solid content, may be about 20% by weight or less, or may be about 15% by weight or less. It may be about 10% by weight or less, and may be about 3% by weight or less (for example, about 1% by weight or less). The technique disclosed herein can be carried out in a manner in which the silicone-based pressure-sensitive adhesive composition is substantially free of silicone resin R2. By limiting the amount of the silicone resin R2 used, it is possible to prevent or suppress the transfer of components to the surface of the adherend (also referred to as contamination of the adherend).

The silicone-based pressure-sensitive adhesive composition disclosed herein may contain a silicone oil, a silicone-based release agent, and other silicone-based compounds as optional components. The silicone oil is an organopolysiloxane that is fluid at room temperature (23 ° C.) and is typically liquid at room temperature. The silicone oil is not particularly limited, and is dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, cyclic dimethyl silicone, and modified products thereof (aralkyl modified product, long chain alkyl modified product, polyether modified product, fluoro. One or more selected from alkyl modified products, amino modified products, mercapto modified products, epoxy modified products, carboxyl modified products, carbinol modified products) and the like can be used. These silicone oils can typically be non-reactive. The silicone-based release agent is not particularly limited, and examples thereof include a thermosetting silicone-based release agent such as a thermosetting curable silicone-based release agent. The "silicone-based release agent" in the present specification does not correspond to the above-mentioned silicone resin R1. The silicone-based release agent may correspond to the above-mentioned silicone resin R2.

The content of the other silicone-based compounds can be set within a range that does not impair the adhesive strength improving effect of the techniques disclosed herein. The content of other silicone-based compounds in the silicone-based pressure-sensitive adhesive composition is about 30% by weight or less (for example, about 10% by weight or less) based on the solid content, and may be about 3% by weight or less, and is about 3% by weight or less. It may be 1% by weight or less. From the relative relationship with the amount of silicone resin R1 used, the amount of other silicone compounds used can be about 1/2 or less (for example, about 1/5 or less) of the amount of silicone resin R1 used. It may be about 1/10 or less. The technique disclosed herein can be carried out in a manner in which the silicone-based pressure-sensitive adhesive composition is substantially free of the above-mentioned other silicone-based compounds. By limiting the amount of the other silicone compounds used, it is possible to prevent or suppress the transfer of components to the surface of the adherend.

The silicone-based pressure-sensitive adhesive composition (for example, a silicone-based pressure-sensitive adhesive composition containing a silicone gum and a silicone resin) may usually contain a cross-linking agent so as to form a silicone-based pressure-sensitive adhesive having a cross-linked structure. .. The cross-linking agent is not particularly limited, and a siloxane-based cross-linking agent having a Si—H group (silicone-based cross-linking agent) or the like can be used. The cross-linking agent may be used alone or in combination of two or more.

As the siloxane-based cross-linking agent, for example, organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule can be preferably used. In such an organohydrogenpolysiloxane, various organic groups may be bonded to the silicon atom to which the hydrogen atom is bonded in addition to the hydrogen atom. Examples of the organic group include an alkyl group such as a methyl group and an ethyl group; an aryl group such as a phenyl group, and an alkyl halide group. From the viewpoint of ease of synthesis and ease of handling, the methyl group is preferable as the organic group. The skeleton structure of the organohydrogenpolysiloxane may have any of linear, branched, and cyclic skeleton structures, but linear skeleton is preferable. The content of the cross-linking agent can be appropriately set according to the desired degree of cross-linking and is not limited to a specific range.

In the silicone-based pressure-sensitive adhesive composition disclosed herein, the total amount (total amount) of the silicone gum and the silicone resin that can be contained in the composition may be approximately 80% by weight or more on a solid content basis. As described above, in the composition in which the total amount of the silicone gum and the silicone resin is not more than a predetermined amount, the cured pressure-sensitive adhesive layer can preferably exhibit the improved adhesive strength. From such a viewpoint, the total amount of the silicone gum and the silicone resin in the silicone-based pressure-sensitive adhesive composition is appropriately about 90% by weight or more, preferably about 95% by weight or more, and about 97% by weight based on the solid content. It may be more than that, and it may be about 99% by weight or more.

The technique disclosed herein is to add silicone resin R1 to an additive curable silicone-containing product (which may be in the form of a product, a product, etc.) that is commercially available or available as a silicone-based pressure-sensitive adhesive. The adhesive strength of the above-mentioned silicone-based pressure-sensitive adhesive (typically, an addition-curable silicone-based pressure-sensitive adhesive; also referred to as a "base silicone-based pressure-sensitive adhesive component" or a "base pressure-sensitive adhesive component") can be improved. Since the composition of the base pressure-sensitive adhesive component, which is commercially available as a silicone-based pressure-sensitive adhesive, is fixed, it is often difficult to adjust the adhesive strength. A typical example of this is a one-component base pressure-sensitive adhesive component. Even in the two-component type, changing the set two-component compounding ratio may not satisfy the expected performance. According to the technique disclosed herein, by adding the silicone resin R1 to such a base pressure-sensitive adhesive component, a desired adhesive strength improving effect can be obtained. Therefore, the silicone-based pressure-sensitive adhesive composition disclosed herein may contain a base silicone-based pressure-sensitive adhesive component and a silicone resin R1.

In the present specification, the "base silicone-based pressure-sensitive adhesive component" refers to a material that can function as a pressure-sensitive adhesive by itself, and in the techniques disclosed herein, the composition is particularly high except that it contains an addition-curable silicone. The content ratio with the silicone resin R1 added as an auxiliary component is not limited, nor is it limited. The base silicone-based pressure-sensitive adhesive component typically contains a silicone gum, and may optionally contain a silicone resin (silicone resin R2). Further, it may contain a siloxane-based cross-linking agent. The base silicone-based pressure-sensitive adhesive component may optionally contain other silicone-based compounds such as silicone oil and silicone-based release agent. The base silicone-based pressure-sensitive adhesive component may be either a one-component type or a two-component type. Typical examples include commercially available add-curable silicone-based pressure-sensitive adhesives as exemplified below. The base silicone-based pressure-sensitive adhesive component may be used alone or in combination of two or more.

The base silicone-based pressure-sensitive adhesive component disclosed herein is a pressure-sensitive adhesive having adhesiveness in itself, and has an adhesive strength equal to or higher than a predetermined value (specifically, 180-degree peel strength against a glass plate, "adhesive strength against glass". Also referred to as). Although not particularly limited, the base silicone-based pressure-sensitive adhesive component may have an adhesive force within the range described as the adhesive force against glass B described later. The adhesive strength of the base silicone-based pressure-sensitive adhesive component to glass is such that a 75 μm-thick pressure-sensitive adhesive layer composed of itself is formed on one side (silicone primer-treated surface) of a 75 μm-thick polyester film (typically a PET film). The adhesive sheet is measured by the same method as the method for measuring the adhesive strength against glass described in Examples described later.

The base silicone-based pressure-sensitive adhesive component may typically have a chain-like silicone structure represented by the general formula (R ₂ SiO) _n . As for R in the above formula, the same R in the general formula (R ₂ SiO) _n in the above-mentioned silicone gum can be selected. The ratio of the repeating unit (R ₂ SiO) to the base silicone-based pressure-sensitive adhesive component is approximately 50 mol% or more based on the total number of repeating units (total number of units) contained in the base silicone-based pressure-sensitive adhesive component. Approximately 70 mol% or more is suitable, preferably approximately 80 mol% or more, and may be approximately 85 mol% or more. The upper limit of the ratio of the repeating unit (R ₂ SiO) to the base silicone-based pressure-sensitive adhesive component is usually less than 100 mol% (for example, less than 99 mol%), and is approximately 95 mol% or less (for example, approximately 90 mol% or less). It may be.

In some embodiments, the base silicone-based pressure-sensitive adhesive component has a repeating unit (R ₂ SiO) in the above general formula mainly of a dialkylsiloxane unit (also referred to as a dialkyl type D unit; the D unit will be described later) and a diaryl. It may contain one or more units selected from a siloxane unit (also referred to as a diaryl type D unit) and a monoalkyl monoaryl siloxane unit (also referred to as a monoalkyl monoaryl type D unit). Of the repeating units contained in the base silicone-based pressure-sensitive adhesive component, the total proportion of the dialkylsiloxane unit, the diarylsiloxane unit, and the monoalkylmonoarylsiloxane unit is typically more than 50 mol%, which is approximately 60 mol. It may be about% or more, about 70 mol% or more, and may be about 80 mol% or more. The alkyl group described above can typically be a methyl group and the aryl group can typically be a phenyl group.

In some preferred embodiments, the base silicone-based pressure-sensitive adhesive component is mainly a dimethylsiloxane unit ((CH ₃ ) ₂ SiO; also referred to as a dimethyl type D unit) in the repeating unit (R ₂ SiO) in the above general formula. It can be a thing. The proportion of the dimethylsiloxane unit in the repeating unit contained in the base silicone-based pressure-sensitive adhesive component is typically more than 50 mol%, may be about 60 mol% or more, and is about 70 mol% or more. It may be present, and may be approximately 80 mol% or more.

The base silicone-based pressure-sensitive adhesive components disclosed herein can typically be addition reactive. Therefore, the base silicone-based pressure-sensitive adhesive component may have a Si—H reactive group. The base silicone-based pressure-sensitive adhesive component may contain a Si—H reactive group-containing siloxane unit in which at least one of R of the repeating unit (R ₂ SiO) in the above general formula is a Si—H reactive group. Examples of the Si—H reactive group include alkenyl groups such as vinyl group, allyl group, hexenyl group and octenyl group; (meth) acryloyl such as acryloyloxymethyl group, acryloyloxypropyl group, methacryloyloxymethyl group and methacryloyloxypropyl group. Oxyalkyl group; The Si—H reactive group is preferably a vinyl group. Examples of the Si—H reactive group-containing siloxane unit include a monoalkyl monoalkenylsiloxane unit such as a monoalkylmonovinylsiloxane unit; and a dialkenylsiloxane unit such as a divinylsiloxane unit. The base silicone-based pressure-sensitive adhesive component may have one or more of the above-mentioned various Si—H reactive groups. Preferable examples include monoalkyl monovinyl siloxane units such as methyl vinyl siloxane units.

The ratio of the Si—H reactive group-containing siloxane unit to the repeating units contained in the base silicone-based pressure-sensitive adhesive component is not particularly limited, and the total number of repeating units contained in the base silicone-based pressure-sensitive adhesive component (total). Based on the number of units), it can be about 0.1 mol% or more, about 0.5 mol% or more is appropriate, and from the viewpoint of cohesive force after curing, it is preferably about 1 mol% or more. Yes, it may be about 1.5 mol% or more (for example, about 2 mol% or more). The upper limit of the proportion of the Si—H reactive group-containing siloxane unit among all the repeating units contained in the base silicone-based pressure-sensitive adhesive component is particularly limited because it is determined according to the wettability and the target adhesive strength. However, it can be about 10 mol% or less, about 5 mol% or less is appropriate, and it may be about 3 mol% or less.

Since the base silicone-based pressure-sensitive adhesive component disclosed herein can typically be addition-reactive, the base silicone-based pressure-sensitive adhesive component can typically have a Si—H group. The base silicone-based pressure-sensitive adhesive component may contain a Si—H group-containing siloxane unit in which at least one of R of the repeating unit (R ₂ SiO) in the above general formula is hydrogen (hydrogen). As the Si—H group-containing siloxane unit, an alkylhydrogensiloxane unit such as a methylhydrogensiloxane unit can be mentioned as a preferable example.

The ratio of the Si—H group-containing siloxane unit to the repeating units contained in the base silicone-based pressure-sensitive adhesive component is not particularly limited, and the total number of repeating units contained in the base silicone-based pressure-sensitive adhesive component (total number of units). ) As a reference, it can be about 0.01 mol% or more, about 0.1 mol% or more is appropriate, and from the viewpoint of cohesive force after curing, it is preferably about 0.2 mol% or more. Yes, it may be about 0.3 mol% or more (for example, about 0.5 mol% or more). The upper limit of the proportion of the Si—H group-containing siloxane unit among all the repeating units contained in the base silicone-based pressure-sensitive adhesive component is not particularly limited because it is determined according to the wettability and the target adhesive strength. , About 10 mol% or less, about 5 mol% or less is suitable, and may be about 3 mol% or less (for example, about 1 mol% or less).

In an embodiment in which the base silicone-based pressure-sensitive adhesive component contains at least one of a Si—H reactive group-containing siloxane unit and a Si—H group-containing siloxane unit, Si-of the repeating units contained in the base silicone-based pressure-sensitive adhesive component. The ratio of the total of the H-reactive group-containing siloxane unit and the Si—H group-containing siloxane unit is not particularly limited, and is approximately based on the total number of repeating units (total number of units) contained in the base silicone-based pressure-sensitive adhesive component. It can be 0.1 mol% or more, and about 0.5 mol% or more is suitable, and from the viewpoint of cohesive force after curing, it is preferably about 1 mol% or more, about 1.5 mol%. The above (for example, about 2 mol% or more) may be used. The upper limit of the ratio of the total of the Si—H reactive group-containing siloxane unit and the Si—H group-containing siloxane unit among all the repeating units contained in the base silicone-based pressure-sensitive adhesive component is the wettability and the target adhesion. Since it is determined according to the force, it is not particularly limited, and may be about 10 mol% or less, about 5 mol% or less is appropriate, and may be about 3 mol% or less.

In an embodiment in which the base silicone-based pressure-sensitive adhesive component contains a Si—H reactive group-containing siloxane unit and a Si—H group-containing siloxane unit, the molar ratio of the Si—H reactive group-containing siloxane unit to the Si—H group-containing siloxane unit. (Si—H reactive group-containing siloxane unit: Si—H group-containing siloxane unit) can be appropriately set according to the desired level of addition curing, and is not limited to a specific range, for example, 1:99. It can be ~ 99: 1, with 10:90 to 98: 2 being appropriate, preferably 30:70 to 95: 5, more preferably 50:50 to 90:10, 60:40 to 85. : 15 may be used, or 70:30 to 80:20 may be used.

In the embodiment in which the silicone resin R1 is added to the base silicone-based pressure-sensitive adhesive component, the amount of the silicone resin R1 added can be determined according to the adhesive strength of the base silicone-based pressure-sensitive adhesive component and the target adhesive strength. Not limited to the range. For example, the blending amount of the silicone resin R1 with respect to 100 parts by weight of the base silicone-based pressure-sensitive adhesive component can be about 0.1 part by weight or more based on the solid content, and about 1 part by weight or more is appropriate. By using the silicone resin R1 in a predetermined amount or more, the effect of adding the silicone resin R1 is preferably exhibited. From such a viewpoint, the blending amount of the silicone resin R1 with respect to 100 parts by weight of the base silicone-based pressure-sensitive adhesive component is preferably about 2 parts by weight or more, and may be about 3 parts by weight or more based on the solid content. It may be about 5 parts by weight or more (for example, about 8 parts by weight or more), about 10 parts by weight or more, about 15 parts by weight or more, about 20 parts by weight or more, about 25 parts by weight or more, about 30 parts by weight. It may be more than a part by weight. Further, the blending amount of the silicone resin R1 with respect to 100 parts by weight of the base silicone-based pressure-sensitive adhesive component is appropriately about 50 parts by weight or less based on the solid content, and is preferable from the viewpoint of maintaining the characteristics of the base silicone-based pressure-sensitive adhesive component. It may be about 40 parts by weight or less, about 30 parts by weight or less, about 20 parts by weight or less, or about 10 parts by weight or less (for example, about 5 parts by weight or less).

Examples of commercially available products that can be used as the base silicone adhesive component include trade names "KR-3700", "KR-3701", "KR-3704", "X-40-3237", manufactured by Shin-Etsu Chemical Co., Ltd. Examples thereof include "X-40-3240", "X-40-3270-1", "X-40-3291-1", "X-40-3306", and "X-40-3323". The examples of these commercially available silicone-based pressure-sensitive adhesives do not limit the silicone-based pressure-sensitive adhesives that can be used for the pressure-sensitive adhesive sheets disclosed herein.

The silicone-based pressure-sensitive adhesive composition disclosed herein may contain a metal-based catalyst such as platinum-based, ruthenium, rhodium, palladium, or iridium. By using a metal-based catalyst, the addition curing reaction of the silicone-based pressure-sensitive adhesive composition can proceed smoothly. Of these, platinum-based catalysts are preferable. Platinum-based catalysts include platinum chloride acid, an alcohol solution of platinum chloride acid, a reaction product of platinum chloride acid and alcohol, a reaction product of platinum chloride acid and an olefin compound, and a reaction product of platinum chloride acid and a vinyl group-containing siloxane. One or more of the above can be used. The amount of the metal catalyst used can be 0.001 part by weight or more (for example, 0.01 part by weight or more, preferably 0.1 part by weight or more) per 100 parts by weight of the addition reaction type silicone adhesive. Further, it can be 5 parts by weight or less (for example, 2 parts by weight or less, preferably 1 part by weight or less).

The silicone-based pressure-sensitive adhesive composition can be prepared in a form containing a solvent (typically an organic solvent), if necessary, from the viewpoint of handleability, coatability, and the like. As the solvent, for example, an aromatic organic solvent such as toluene or xylene can be used, but the solvent is not limited thereto. The solvent may be a solvent composed of one kind of organic solvent or a mixed solvent containing two or more kinds of organic solvents.

The silicone-based pressure-sensitive adhesive composition disclosed herein may further contain additives such as fillers, plasticizers, antioxidants, antistatic agents, colorants (pigments, dyes, etc.), if necessary. Such additives can be used alone or in combination of two or more.

<Silicone adhesive>
The silicone-based pressure-sensitive adhesive disclosed herein is a silicone-based pressure-sensitive adhesive formed by an addition reaction of a Si—H group and a Si—H reactive group, and is formed from a silicone-based pressure-sensitive adhesive composition containing an addition-curable silicone. Will be done. The above-mentioned silicone-based pressure-sensitive adhesive is an addition-reaction cured product of the addition-curable silicone (silicone gum or silicone resin) described in the silicone-based pressure-sensitive adhesive composition, and is typically a silicone cure obtained by curing the addition-curable silicone. Including things. The details thereof are basically the same as those described in the silicone-based pressure-sensitive adhesive composition except for the difference between before and after the addition reaction, and therefore duplicate description will be omitted. Since the ratio of the components contained in the silicone-based pressure-sensitive adhesive is basically the same as the weight ratio based on the solid content in the silicone-based pressure-sensitive adhesive composition, duplicate description will be omitted.

Further, the silicone-based pressure-sensitive adhesive disclosed herein contains silicone resin R1. The details of the silicone resin R1 are as described above. In the cured silicone-based pressure-sensitive adhesive, at least a part of the silicone resin R1 may be chemically bonded to the cured silicone product. Alternatively, the silicone resin R1 may exist in a state in which at least a part thereof is not chemically bonded to the cured silicone product. Further, the silicone resin R1 may be one in which a plurality of molecules thereof are chemically bonded to each other. In some embodiments, in the cured silicone-based pressure-sensitive adhesive, the silicone resin R1 is partially chemically bonded to the cured silicone product and the other part is chemically bonded to the cured silicone product. It can be in an unbonded state. Further, one molecule of silicone resin R1 chemically bonded to the cured silicone product and one molecule of silicone resin R1 not chemically bonded to the cured silicone product are chemically bonded to another silicone resin R1 molecule. Can be. The above-mentioned "chemical bond" is specifically a chemical bond by an addition reaction, and is typically a covalent bond.

The silicone-based pressure-sensitive adhesive can be formed by curing (typically heating) the silicone-based pressure-sensitive adhesive composition. The curing treatment temperature (typically, the heating temperature) can be, for example, about 70 ° C. or higher, and about 100 ° C. or higher is suitable. The upper limit of the curing treatment temperature is appropriately set to about 250 ° C. or lower (for example, 200 ° C. or lower), preferably about 180 ° C. or lower, and more preferably about 150 ° C. or lower (for example, less than 150 ° C.). It can be at about 130 ° C. or lower. Since the technique disclosed here uses an addition reaction, it is advantageous in that it can be cured at a temperature lower than 150 ° C., unlike the peroxide curing type. In addition, limiting the curing treatment temperature is also preferable in terms of production efficiency and avoiding the influence of heating on other constituent materials (for example, a base film). The curing treatment time (typically, heating time) is about 10 seconds or more, about 1 minute or more is appropriate, and about 10 minutes or less (for example, about 5 minutes or less) is appropriate.

<Adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein includes a pressure-sensitive adhesive layer made of the above-mentioned silicone-based pressure-sensitive adhesive. This pressure-sensitive adhesive layer typically constitutes at least one surface of the pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet with a base material having a pressure-sensitive adhesive layer on one side or both sides of the base material (support), and the pressure-sensitive adhesive layer may be grasped as a release liner (base material having a release surface). It may be a base material-less adhesive sheet such as a form held in (.). In this case, the pressure-sensitive adhesive sheet may consist only of a pressure-sensitive adhesive layer. The concept of an adhesive sheet as used herein may include adhesive sheets that may be referred to as an adhesive tape, an adhesive label, an adhesive film, or the like. Further, the pressure-sensitive adhesive layer is typically formed continuously, but is not limited to such a form, and the pressure-sensitive adhesive layer is formed in a regular or random pattern such as a dot shape or a striped shape. It may be. In addition, the pressure-sensitive adhesive sheet provided by the present specification may be in the form of a roll or in the form of a single leaf. Alternatively, it may be an adhesive sheet in a form further processed into various shapes.

The pressure-sensitive adhesive sheet disclosed herein may have, for example, the cross-sectional structure schematically shown in FIG. The pressure-sensitive adhesive sheet 1 includes a base film 10 and a pressure-sensitive adhesive layer 20 supported on one surface 10A of the base film 10. The one surface 10A of the base film 10 is a non-peelable surface (non-peelable surface). The pressure-sensitive adhesive sheet 1 is used by attaching the surface 20A of the pressure-sensitive adhesive layer 20 to an adherend. The pressure-sensitive adhesive sheet 1 before use has a structure in which the pressure-sensitive adhesive surface 20A is protected by a release liner 30 in which at least the pressure-sensitive adhesive surface side is a surface (peeling surface) having peelability. Alternatively, the release liner 30 is omitted, and the other surface of the base film (the surface opposite to the surface 10A, the back surface) is the release surface, and when the adhesive sheet is wound, the adhesive layer is formed on the back surface of the base film. The adhesive surface may be in contact with the adhesive surface, and the adhesive surface may be protected by the back surface of the supporting base material.

When the technique disclosed herein is carried out in the form of a double-sided pressure-sensitive adhesive sheet with a base material, both of the pressure-sensitive adhesive layers arranged on each surface of the base material film are the silicones disclosed here. It may be a pressure-sensitive adhesive layer made of a based pressure-sensitive adhesive, only one of which is the silicone-based pressure-sensitive adhesive layer disclosed herein, and the other is a variety of conventionally known pressure-sensitive adhesives (for example, silicone-based or fluorine-based). It may be an adhesive layer formed of acrylic type, rubber type, etc.).

<Base film>
The material (film base material) of the base film used as the support of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, and for example, a resin film can be preferably used. The resin film may be formed by molding various resin materials into a film shape. As the resin material, those capable of forming a resin film having one or more excellent properties such as transparency, mechanical strength, thermal stability, moisture shielding property, and isotropic property are preferable. For example, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; celluloses such as diacetyl cellulose and triacetyl cellulose; polycarbonates; acrylic polymers such as polymethyl methacrylate; etc. A resin film composed of a resin material as a component (that is, a component contained in an amount of more than 50% by weight) can be preferably used as the base film. Other examples of the resin material constituting the resin film include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer; polyolefins such as polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, and ethylene-propylene. Copolymers and the like; polyvinyl chlorides; polyamides such as nylon 6, nylon 6, 6 and aromatic polyamides; and the like as main components can be mentioned. Alternatively, polyimides, polysulfones, polyethersulfones, polyetheretherketones, polyphenylene sulfides, fluororesins, polyvinyl alcohols, polyvinylacetates, polyvinylidene chlorides, polyvinylbutyrals, polyallylates, poly A resin film composed of a resin material containing oxymethylene, epoxy resins, etc. as a main component may be used as the base film. The resin material constituting the resin film can be a blend of two or more of these.

In addition, in this specification, a "resin film" means a resin film (of voidless) which has a non-porous structure and typically contains substantially no air bubbles. Therefore, the resin film is a concept that is distinguished from foam films and non-woven fabrics.

Other examples of the base film include foam sheets made of foams such as polyurethane foam, polyethylene foam, and polychloroprene foam, and synthesis of various fibrous substances (natural fibers such as hemp and cotton, polyester, vinylon, etc.). Woven fabrics and non-woven fabrics made of fibers, semi-synthetic fibers such as acetate, etc.) alone or by blending; papers such as Japanese paper, high-quality paper, kraft paper, crepe paper, metal foils such as aluminum foil and copper foil, Examples include glass. The support may be a composite structure of these. Examples of such a support having a composite structure include a support having a structure in which a metal foil and the plastic film are laminated, a plastic sheet reinforced with an inorganic fiber such as glass cloth, and the like.

In some preferred embodiments, the base film is a resin film (polyester resin film) in which a resin (polyester resin) containing polyester as a main component (a component contained in an amount of more than 50% by weight) is formed into a film. Use. For example, a resin film (PET film) in which the polyester is mainly PET, a resin film (PEN film) in which the polyester is mainly PEN, and the like can be preferably adopted.

The base film may have a single-layer structure or may have a multi-layer structure. Therefore, the resin film that can be used as the base film may also have a single-layer structure or a multilayer structure of two or more layers (for example, a three-layer structure). A resin film having a single-layer structure can be preferably used as the base film.

In some embodiments, the substrate film (typically a resin film) preferably has a transparency of approximately 50% or more in total light transmittance in the visible light wavelength region. A transparent resin film having a total light transmittance of 80% or more (for example, 85% or more) is more preferable. The upper limit of the total light transmittance is 100%, but if it has a total light transmittance of about 99% or less (typically 97% or less, for example, 95% or less), it is practically transparent. It can be preferably used as a resin film. As the value of the total light transmittance, the manufacturer's nominal value can be adopted. If there is no nominal value, the value measured according to JIS K 7361-1 can be adopted.

The base film (typically a resin film) contains various additives such as antioxidants, ultraviolet absorbers, antistatic components, plasticizers, and colorants (pigments, dyes, etc.), if necessary. It may have been.

The surface of the base film on the pressure-sensitive adhesive layer side may be subjected to surface treatment such as chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, and ionizing radiation treatment. Such a surface treatment may be, for example, a treatment for enhancing the adhesion between the base film and the pressure-sensitive adhesive layer. In some embodiments, the surface of the substrate film on the pressure-sensitive adhesive layer side may be primed. Silicone primer treatment is preferable from the viewpoint of adhesion to a silicone-based pressure-sensitive adhesive. In some embodiments, the back surface of the substrate film may be hard coated. As a result, the scratch resistance on the back surface of the base film is improved, and when the adhesive sheet is used as the protective sheet, more excellent protective performance can be exhibited. Further, in some other aspects, the base film may be antistatic treated from the viewpoint of suppressing the generation of static electricity. The base film may also be subjected to various treatments such as antifouling, anti-fingerprint, anti-glare, and anti-reflection.

The thickness of the base film can be appropriately selected in consideration of the use, purpose, usage pattern and the like of the pressure-sensitive adhesive sheet. From the viewpoint of workability such as strength and handleability, a base film having a thickness of about 10 μm or more is suitable, preferably about 20 μm or more, and more preferably about 30 μm or more (for example, 50 μm or more). Further, the thickness of the base film is preferably about 200 μm or less, preferably about 150 μm or less, and more preferably about 100 μm or less from the viewpoint of cost and the like.

<Adhesive layer>
The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein is formed, for example, by a method (direct method) in which the above-mentioned silicone-based pressure-sensitive adhesive composition is directly applied to the surface of a base film and dried or cured. be able to. Alternatively, the pressure-sensitive adhesive composition is applied to the surface (peeling surface) of the release liner and dried or cured to form a pressure-sensitive adhesive layer on the surface, and the pressure-sensitive adhesive layer is attached to a base film. It may be formed by a method of transferring the pressure-sensitive adhesive layer (transfer method). From the viewpoint of anchoring property of the pressure-sensitive adhesive layer, the above direct method can be preferably adopted. When applying (typically applying) the pressure-sensitive adhesive composition, various methods such as a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, and a coating method using a die coater are used. Can be adopted as appropriate. The drying or curing conditions of the pressure-sensitive adhesive composition are as described for the silicone-based pressure-sensitive adhesive.

The haze value of the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, about 80% or less. When inspecting the adherend through the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer needs to have appropriate permeability. From such a viewpoint, it is appropriate that the haze value of the pressure-sensitive adhesive layer is about 50% or less (for example, about 30% or less), preferably about 10% or less, more preferably about 3% or less, still more preferably. It is about 1.5% or less (for example, less than 1.0%). The haze value of the pressure-sensitive adhesive layer is measured by the following method. That is, the pressure-sensitive adhesive layer is cut into a size of 50 mm width × 50 mm length to prepare a measurement sample. The haze value of the measurement sample is measured in accordance with JIS K 7136: 2000 using a "haze meter HM150" manufactured by Murakami Color Technology Research Institute. This is defined as the haze value [%] of the adhesive layer. Alternatively, for the pressure-sensitive adhesive sheet with a base film, the haze value of the pressure-sensitive adhesive sheet and the haze value of the base film can be measured, and the haze value of the pressure-sensitive adhesive layer can be estimated from the difference between the two.

In some embodiments, the pressure-sensitive adhesive layer is preferably transparent with a total light transmittance of approximately 50% or more in the visible light wavelength region. A transparent pressure-sensitive adhesive layer having a total light transmittance of 80% or more (for example, 85% or more) is more preferable. The upper limit of the total light transmittance is 100%, but in applications where transparency is required, the upper limit of the total light transmittance is about 99% or less (typically 97% or less, for example, from the viewpoint of practicality. A pressure-sensitive adhesive layer of about 95% or less) can also be preferably used. As the value of the total light transmittance, a value measured in accordance with JIS K 7361-1 can be adopted.

Although not particularly limited, the thickness of the pressure-sensitive adhesive layer can be, for example, about 3 μm or more, about 5 μm or more is appropriate, and about 10 μm or more is preferable. From the viewpoint of adhesiveness to the adherend, the thickness is preferably about 20 μm or more, more preferably about 50 μm or more (for example, about 70 μm or more). Further, the thickness can be, for example, about 200 μm or less, about 150 μm or less (for example, about 120 μm or less) is appropriate, and preferably about 100 μm or less (for example, 80 μm or less). When the technique disclosed herein is carried out in the form of a double-sided pressure-sensitive adhesive sheet with a base material, the thickness of each pressure-sensitive adhesive layer may be the same or different.

<Peeling liner>
The adhesive sheet disclosed herein has a form in which a release liner is attached to the adhesive surface for the purpose of protecting the adhesive surface (the surface of the adhesive layer on the side to be attached to the adherend), if necessary. It may be provided (in the form of an adhesive sheet with a release liner). Paper, a synthetic resin film, or the like can be used as the base material constituting the release liner, and the synthetic resin film is preferably used from the viewpoint of excellent surface smoothness. For example, various resin films (for example, polyester films) can be preferably used as the base material of the release liner. The thickness of the release liner can be, for example, about 5 μm to 200 μm, and is preferably about 10 μm to 100 μm. A mold release agent (for example, silicone-based, fluorine-based, long-chain alkyl-based, fatty acid amide-based, etc.) or silica powder is used on the surface of the release liner to be bonded to the pressure-sensitive adhesive layer for mold release or antifouling treatment. May be applied.

<Total thickness of adhesive sheet>
The total thickness of the pressure-sensitive adhesive sheet (which may include the pressure-sensitive adhesive layer and the base film but does not include the release liner) disclosed herein is not particularly limited and may be about 5 μm or more (for example, about 15 μm or more). It is possible, and about 20 μm or more is suitable, and from the viewpoint of adhesive properties, handleability, etc., it is preferably about 50 μm or more, may be about 80 μm or more, or may be about 100 μm or more (for example, about 120 μm or more). Further, the total thickness of the adhesive sheet can be, for example, about 500 μm or less, and about 400 μm or less is appropriate, and from the viewpoint of weight reduction, cost, etc., it is preferably about 300 μm or less, about 250 μm or less. It may be about 200 μm or less (for example, about 180 μm or less).

<Characteristics of adhesive sheet>
The adhesive strength of the pressure-sensitive adhesive sheet disclosed herein is not limited to a specific range as long as the advantages of the adhesive strength improving effect by the technology disclosed herein can be enjoyed. For example, the pressure-sensitive adhesive sheet according to some aspects has a 180-degree peel strength (adhesive strength against glass) with respect to a glass plate of about 1 gf / 25 mm or more. The adhesive strength against glass can be about 2 gf / 25 mm or more, may be about 3 gf / 25 mm or more, may be about 5 gf / 25 mm or more, or may be about 8 gf / 25 mm or more. The upper limit of the adhesive force against glass can be less than 1000 gf / 25 mm (for example, less than 500 gf / 25 mm), less than 100 gf / 25 mm is appropriate, and preferably about 50 gf / 25 mm or less from the viewpoint of removability and the like. It may be about 30 gf / 25 mm or less, or about 15 gf / 25 mm or less (for example, about 10 gf / 25 mm or less). In applications where higher adhesive strength is desired, the adhesive strength against glass may be about 10 gf / 25 mm or more, about 50 gf / 25 mm or more, or about 100 gf / 25 mm or more (for example, about 300 gf / 25 mm or more). Good. The adhesive strength to glass is measured by the method described in Examples described later.

The PSA sheet disclosed herein, in embodiments the adhesive layer comprises a pressure-sensitive adhesive strength improving component such as a silicone resin R1, the adhesive force change rate _{(R PS: Ratio of Peel Strength} Change) thereof is at most 110% higher .. Here, the rate of change in adhesive strength ( _RPS ) is expressed by the formula:
R _PS (%) = A / B x 100;
Can be obtained more. In the above formula, A is the 180-degree peel strength [gf / 25 mm] of the adhesive sheet with respect to the glass plate, and B is the same as the adhesive sheet except that the adhesive layer does not contain the adhesive strength improving component. It is 180 degree peel strength [gf / 25 mm] with respect to the glass plate of the control adhesive sheet. According to the above-mentioned adhesive sheet, the adhesive strength can be improved by using the adhesive strength improving component. As a typical example of the adhesive strength improving component, the above-mentioned silicone resin R1 can be mentioned. The adhesive strength change rate ( _RPS ) may vary depending on the adhesive strength before using the adhesive strength improving component and the target adhesive strength, and is not limited to a specific range, for example, even if it is 120% or more. It may be 140% or more, 160% or more, 200% or more, 250% or more, 300% or more, 350% or more, or 400% or more. The upper limit of the adhesive strength change rate ( _RPS ) is not particularly limited, and may be about 800% or less, for example, about 500% or less.

In the technique disclosed herein, the adhesive strength of the adhesive sheet before the improvement of the adhesive strength is not particularly limited. In some embodiments, the control pressure-sensitive adhesive sheet is the same as the pressure-sensitive adhesive sheet except that the pressure-sensitive adhesive layer does not contain the above-mentioned pressure-sensitive adhesive strength component. 180 degree peel strength with respect to the glass plate (that is, B in the above formula. The adhesive strength (also referred to as "adhesive strength B") is preferably less than 8 gf / 25 mm, and may be less than 5 gf / 25 mm, from the viewpoint of sufficiently obtaining the effect of the adhesive strength improving component (typically, the above-mentioned silicone resin R1). It may be less than 3 gf / 25 mm, less than 2 gf / 25 mm, or less than 1 gf / 25 mm. In some other aspects, the upper limit of the adhesive strength to glass B can be less than 800 gf / 25 mm (eg, less than 300 gf / 25 mm), less than 80 gf / 25 mm, less than 30 gf / 25 mm, 20 gf. It may be less than / 25 mm, or less than 10 gf / 25 mm. The lower limit of the adhesive force against glass B can be about 0.5 gf / 25 mm or more, about 1 gf / 25 mm or more is appropriate, may be about 3 gf / 25 mm or more, or about 10 gf / 25 mm or more. It may be about 50 gf / 25 mm or more, and may be about 100 gf / 25 mm or more (for example, about 300 gf / 25 mm or more). The adhesive force against glass B is measured by the same method as the method for measuring the adhesive force against glass described in Examples described later.

The haze value of the adhesive sheet is not particularly limited and may be, for example, about 80% or less. When inspecting an adherend through an adhesive sheet, the adhesive sheet needs to have appropriate permeability. From such a viewpoint, it is appropriate that the haze value of the adhesive sheet is about 50% or less (for example, about 30% or less), preferably about 10% or less, more preferably about 3% or less, still more preferably about 30% or less. It is 1.5% or less (for example, less than 1.0%). The haze value of the adhesive sheet can be measured by the following method. That is, the pressure-sensitive adhesive sheet is cut into a size of 50 mm width × 50 mm length to prepare a measurement sample. The haze value of the measurement sample is measured in accordance with JIS K 7136: 2000 using a "haze meter HM150" manufactured by Murakami Color Technology Research Institute. Let this be the haze value [%] of the adhesive sheet.

In some embodiments, the pressure-sensitive adhesive sheet preferably has a transparency with a total light transmittance of approximately 50% or more in the visible light wavelength region. A transparent adhesive sheet having a total light transmittance of 80% or more (for example, 85% or more) is more preferable. The upper limit of the total light transmittance is 100%, but in applications where transparency is required, the upper limit of the total light transmittance is about 99% or less (typically 97% or less, for example, from the viewpoint of practicality. An adhesive sheet of about 95% or less) can also be preferably used. As the value of the total light transmittance, a value measured in accordance with JIS K 7361-1 can be adopted.

<Use>
The use of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited. The pressure-sensitive adhesive sheet disclosed herein can be used for various purposes such as joining members, protecting the surface, and sealing. In some preferred embodiments, the adhesive sheet can be used as a surface protective sheet. The protection target of the surface protective sheet is not particularly limited, and can be used as a protective sheet for various products, parts, and the like. For example, the surface protective sheet is particularly suitable as a surface protective sheet that protects the surface of an optical component (for example, an optical component used as a component of a liquid crystal display panel such as a polarizing plate or a wave plate) during processing or transportation. Is. More specifically, the surface protective sheet is an optical component (during manufacturing, transporting, etc.) of an optical member used as a component of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, or the like. It is also called an optical member) and is suitable for protection. In particular, surfaces applied to optical components such as polarizing plates (polarizing films, for example, reflective polarizing films) for liquid crystal display panels, wave plates, retardation plates, optical compensation films, brightness improving films, light diffusing sheets, and reflective sheets. It is useful as a protective sheet. The concept of the surface protection sheet disclosed herein includes masking tape used when processing electronic components such as flexible printed wiring boards. In some other aspects, the silicone-based pressure-sensitive adhesives disclosed herein can be used, for example, in the form of pressure-sensitive adhesive sheets, for applications such as protecting semiconductor wafers and encapsulating semiconductor devices.

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in the examples. In addition, "part" and "%" in the following description are based on weight unless otherwise specified.

<Evaluation method>
[180 degree peel strength against glass plate]
The pressure-sensitive adhesive sheet with a release liner is left in an environment of 23 ° C. and 50% RH for 30 minutes, and then a measuring sheet piece having a length of 100 mm and a width of 25 mm is obtained from the pressure-sensitive adhesive sheet. Next, in an environment of 23 ° C. and 50% RH, the release liner is peeled off from the sheet piece to expose the adhesive surface (measurement surface), and the adhesive surface of the sheet piece is made into a glass plate (trade name "soda lime glass"). # 0050 ", manufactured by Matsunami Glass Industry Co., Ltd.) is crimped with a 2 kg roller under the condition of one reciprocation, and the above sheet piece is attached to a glass plate. After leaving this for 30 minutes, using a tensile tester (trade name "TCM-1kNB", manufactured by Minebea), the peeling angle is 180 degrees and the tensile speed is 300 mm / min in an environment of 23 ° C. and 50% RH. Under the conditions, the sheet piece is peeled from the glass plate, and the peel strength measured at this time is set to 180 degree peel strength (adhesion to glass) [gf / 25 mm].
The 180-degree peel strength may be a value obtained by performing the same measurement as above except that adhesive sheets having different widths are used, and the obtained measured value is converted into a 25 mm width.
When the measurement sample is a double-sided adhesive sheet (for example, a base material-less adhesive sheet), the non-measurement surface is lined with a PET film having a thickness of about 50 μm to perform the measurement.

<Example 1>
100 parts of additive reaction type silicone adhesive (trade name "X-40-3306", manufactured by Shin-Etsu Chemical Co., Ltd.) as the main material, and platinum-based catalyst (trade name "CAT-PL-50T", manufactured by Shin-Etsu Chemical Co., Ltd.) (Manufactured) 0.4 parts and Silicone Resin A (trade name "KS-3800", manufactured by Shin-Etsu Chemical Co., Ltd .: Addition of having a Q unit and having an isopropyl group, in which the isopropyl group is bonded to the Q unit A silicone-based pressure-sensitive adhesive composition (silicone-based pressure-sensitive adhesive composition A) was prepared by mixing with 2.5 parts of a reactive silicone resin).
A polyester film having a thickness of 75 μm (trade name “Diafoil MRF # 75”, manufactured by Mitsubishi Chemical Corporation) having one surface treated with a silicone primer was prepared as a base film. The silicone-based pressure-sensitive adhesive composition A obtained above was applied to the silicone primer-treated surface of this base film to obtain a film having a layer made of the silicone-based pressure-sensitive adhesive composition. The film with the silicone-based pressure-sensitive adhesive composition layer was held at 30 ° C. for 2 minutes and further heated at 130 ° C. for 3 minutes to form a silicone-based pressure-sensitive adhesive layer having a thickness of 75 μm. In this way, an adhesive sheet in which a silicone-based adhesive layer was arranged on one surface of the base film was obtained. A PET film (a PET film that has not been peeled off) was attached as a peeling liner on the adhesive surface of the pressure-sensitive adhesive sheet.

<Examples 2 to 6>
The pressure-sensitive adhesive sheet according to each example was prepared in the same manner as in Example 1 except that the amount of silicone resin A (trade name "KS-3800") used for 100 parts of the addition reaction type silicone-based pressure-sensitive adhesive was changed to the number of copies shown in Table 1. Made.

<Example 7>
An adhesive sheet according to this example was prepared in the same manner as in Example 1 except that silicone resin A (trade name “KS-3800”) was not used.

<Example 8>
Silicone resin A (trade name "KS-3800") is replaced with a silicone-based release agent (trade name "KS-776A", manufactured by Shin-Etsu Chemical Co., Ltd .: an addition reaction type silicone-based release agent having no propyl group). The pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1.

Table 1 shows an outline of the silicone-based pressure-sensitive adhesive according to each example and the evaluation results of the adhesive strength against glass [gf / 25 mm]. Table 1 also shows the rate of change in adhesive strength [%] when the adhesive strength against glass of Example 7 in which silicone resin A was not used was 100 [%].

As shown in Table 1, the pressure-sensitive adhesive sheets according to Examples 1 to 6 having the pressure-sensitive adhesive layer containing silicone resin A had improved adhesive strength as compared with the pressure-sensitive adhesive sheets according to Example 7 containing no silicone resin A. Further, from the results of Examples 1 to 6, it was observed that the adhesive strength tended to increase as the amount of the silicone resin A added was increased. On the other hand, in Example 8 in which the silicone-based release agent was used, the adhesive strength against glass decreased.
From the above results, a silicone resin satisfying at least one of (a) having a propyl group; and (b) having a Q unit and having a Si—H group and / or a Si—H reactive group; It can be seen that the adhesive strength can be improved by the pressure-sensitive adhesive containing.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

1: Adhesive sheet 10: Base film 10A: One surface of base film 20: Adhesive layer 20A: Surface (adhesive surface)
30: Peeling liner

Claims (9)

A silicone-based pressure-sensitive adhesive formed by an addition reaction between a Si—H group and a Si—H reactive group.
Silicone resin R1 is contained in the silicone-based pressure-sensitive adhesive.
The silicone resin R1 is
(A) has a propyl group; and (b) has a Q unit and has a Si—H group and / or a Si—H reactive group;
A silicone-based adhesive that satisfies at least one of them. The silicone resin R1 has a Q unit and a propyl group, and has a propyl group.
The silicone-based pressure-sensitive adhesive according to claim 1, wherein the propyl group is bonded to the Q unit. The silicone-based pressure-sensitive adhesive according to claim 1 or 2, wherein the weight ratio of the silicone resin R1 to the silicone-based pressure-sensitive adhesive is 1 to 50% by weight. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of the silicone-based pressure-sensitive adhesive according to any one of claims 1 to 3. The adhesive sheet according to claim 4, wherein the 180-degree peel strength with respect to the glass plate is 1 gf / 25 mm or more. A silicone-based pressure-sensitive adhesive composition containing an addition-curable silicone.
The silicone-based pressure-sensitive adhesive composition contains silicone resin R1.
The silicone resin R1 is
(A) has a propyl group; and (b) has a Q unit and has a Si—H group and / or a Si—H reactive group;
A silicone-based pressure-sensitive adhesive composition that satisfies at least one of them. The silicone resin R1 has a Q unit and a propyl group, and has a propyl group.
The silicone-based pressure-sensitive adhesive composition according to claim 6, wherein the propyl group is bonded to the Q unit. The silicone-based pressure-sensitive adhesive composition according to claim 6 or 7, wherein the weight ratio of the silicone resin R1 in the silicone-based pressure-sensitive adhesive composition is 1 to 50% by weight based on the solid content. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the silicone-based pressure-sensitive adhesive composition according to any one of claims 6 to 8.

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