JP2019035066A - Adhesive composition for protective film, and protective film - Google Patents

Abstract

To provide an adhesive composition for a protective film which is excellent in stain resistance and antistatic properties, and a protective film.SOLUTION: The adhesive composition for a protective film contains a (meth)acrylic resin (A) having at least a crosslinkable functional group, an isocyanate compound (B), an isocyanate compound (C) having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B), and an antistatic agent (D). The content of the isocyanate compound (C) is 0.10 pt.mass or more based on 100 pts.mass of the (meth)acrylic resin (A).SELECTED DRAWING: None

Description

  The present invention relates to a protective film pressure-sensitive adhesive composition and a protective film.

Protective films are widely used to protect optical members and the like used in display devices such as liquid crystal display devices and organic EL (electroluminescence) display devices.
The protective film is laminated on the surface of the optical member to protect the surface of the optical member from being contaminated or damaged, and is peeled off from the optical member when the surface protection becomes unnecessary. Therefore, the protective film is required not to contaminate the surface of the optical member (adhered body) after peeling (contamination resistance).

  In addition, if static electricity is generated when the protective film is peeled off from the optical member, problems such as adhesion of dust or damage to the liquid crystal display device circuit may occur on the optical member. Properties that can be prevented (antistatic properties) are required.

Examples of the pressure-sensitive adhesive composition that can be easily peeled off and can form a pressure-sensitive adhesive film with little contamination of the adherend include, for example, a (meth) acrylic copolymer having an acidic group and a hydroxyl group, and a reactive group. A pressure-sensitive adhesive composition containing a dimethylpolysiloxane compound having a crosslinking agent is disclosed (for example, see Patent Document 1).
As a pressure-sensitive adhesive composition having excellent antistatic properties and reduced contamination to the object to be protected, an alkali metal salt is included, and (meth) acrylic acid alkylene oxide adduct is added in an amount of 15 to 100% by weight as a monomer component. A pressure-sensitive adhesive composition used as an adhesive is disclosed (for example, see Patent Document 2).

JP, 2015-160907, A JP 2005-314579 A

In recent years, the demand for preventing contamination of adherends has been improved for protective films. As a result of investigations by the inventors, further improvement in stain resistance is required for the pressure-sensitive adhesive composition described in Patent Document 1.
In order to further improve the contamination resistance, for example, it is conceivable to reduce the addition amount of an antistatic aid such as a dimethylpolysiloxane compound and an antistatic agent. However, if the amount of the antistatic aid or the antistatic agent is simply reduced, the antistatic property tends to be lowered. Therefore, when the protective film is peeled and removed, static electricity is likely to be generated, and the liquid crystal display device or the like. May cause problems. For this reason, it has been difficult for conventional pressure-sensitive adhesive compositions to maintain both the stain resistance and the antistatic property at a high level.

  This invention is made | formed in view of the above, and makes it a subject to provide the adhesive composition for protective films which is excellent in stain resistance and antistatic property, and a protective film.

Specific means for solving the problems include the following aspects.
<1> (meth) acrylic resin (A) having at least a crosslinkable functional group;
An isocyanate compound (B);
An isocyanate compound (C) having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B);
An antistatic agent (D),
The content of the isocyanate compound (C) is a pressure-sensitive adhesive composition for a protective film, which is 0.10 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic resin (A).
<2> The mass ratio [(C) / (B)] of the isocyanate compound (C) to the isocyanate compound (B) is 1/1 to 1/20, and the pressure-sensitive adhesive for protective film according to <1>. Agent composition.
<3> The adhesive composition for a protective film according to <1> or <2>, wherein the isocyanate compound (C) includes a structure represented by the following structural formula (1).

  In Structural Formula (1), r represents an integer of 1 to 100, b represents an integer of 1 to 100, and X represents a monovalent organic group containing an isocyanate group.

<4> The adhesive composition for a protective film according to any one of <1> to <3>, wherein the isocyanate compound (C) is represented by the following general formula (1-1).

  In General Formula (1-1), p or q each independently represents an integer of 0 to 100, r represents an integer of 1 to 100, a represents an integer of 0 to 100, and b represents 1 to 100. X represents a monovalent organic group containing an isocyanate group.

<5> The pressure-sensitive adhesive composition for a protective film according to any one of <1> to <4>, wherein the antistatic agent (D) is an alkali metal salt or an organic salt.
<6> The adhesive composition for a protective film according to any one of <1> to <5>, which is used for an optical member.
<7> The protective film which has a base material and the adhesive layer which is a crosslinked material of the adhesive composition for protective films as described in any one of <1>-<6>.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition for protective films and protective film which are excellent in stain resistance and antistatic property can be provided.

Hereinafter, the pressure-sensitive adhesive composition of the present invention will be described in detail.
In the present invention, “to” in a numerical range means including numerical values before and after “to”. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in a numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
In this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means.

In the present specification, the (meth) acrylic resin or (meth) acrylic oligomer is a monomer having a (meth) acryloyl group as a monomer that is at least a main component among monomers constituting the (meth) acrylic resin. It means a resin or oligomer formed by polymerization.
The main component in the (meth) acrylic resin or (meth) acrylic oligomer means that the content (mass%) is the largest among the monomer components forming the resin or oligomer. For example, in the case of a (meth) acrylic resin, it means that the content of a structural unit derived from a monomer having a (meth) acryloyl group as a main component is 50% by mass or more of all structural units.
In the present specification, “(meth) acryl” means at least one of “acryl” and “methacryl”, “(meth) acrylate” means at least one of “acrylate” and “methacrylate” “(Meth) acryloyl” means at least one of “acryloyl” and “methacryloyl”.

≪Protective film adhesive composition≫
The pressure-sensitive adhesive composition for protective film of the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive composition”) includes at least a (meth) acrylic resin (A) having a crosslinkable functional group, an isocyanate compound (B), and And an isocyanate compound (C) having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B), and an antistatic agent (D), and the content of the isocyanate compound (C) is ) It is 0.10 mass part or more with respect to 100 mass parts of acrylic resin (A).

  Since the pressure-sensitive adhesive composition has the above-described configuration, it is possible to form a pressure-sensitive adhesive layer having excellent stain resistance and antistatic properties. The reason for this is not clear, but is presumed as follows.

Generally, it is known that a silicone compound having an alkylene oxide structure acts as an antistatic aid. The pressure-sensitive adhesive layer formed by coating a base material with a pressure-sensitive adhesive composition containing an antistatic agent and a silicone compound having an alkylene oxide structure has an alkylene oxide structure in the silicone compound immediately after coating. Since it is localized near the surface of the pressure-sensitive adhesive layer in a coordinated state, antistatic properties are easily exhibited even with a small amount of antistatic agent.
On the other hand, since the silicone compound is likely to be localized near the surface of the pressure-sensitive adhesive layer, it is known that the silicone compound is likely to be one of the factors that contaminate the surface of the adherend by transfer.

The pressure-sensitive adhesive composition of the present invention comprises at least a (meth) acrylic resin (A) having a crosslinkable functional group and an isocyanate compound having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B) in a certain amount or more. In the pressure-sensitive adhesive layer formed with (C) (hereinafter also simply referred to as “silicone-based isocyanate compound (C)”), the silicone-based isocyanate compound (C) is localized in the vicinity of the surface. The isocyanate (NCO) group in the isocyanate compound (C) and the crosslinkable functional group in the (meth) acrylic resin (A) react to form a crosslinked structure. It is presumed that the silicone-based isocyanate compound (C) is kept anchored in the pressure-sensitive adhesive layer due to the formation of the crosslinked structure. Therefore, when the protective film is peeled off from the adherend, for example, an antistatic agent and an antistatic assistant (hereinafter also referred to as “contaminating component”) contained in the pressure-sensitive adhesive composition on the adherend surface. Transfer can be suppressed, and the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention exhibits excellent stain resistance.
In addition, since the silicone-based isocyanate compound (C) has a polysiloxane structure in the molecule, the surface free energy becomes low and is hardly compatible with the (meth) acrylic resin (A). It is presumed to be localized near the surface of the pressure-sensitive adhesive layer. Furthermore, since the silicone-based isocyanate compound (C) has an alkylene oxide structure in the molecule, it is coordinated with the antistatic agent in the same manner as the silicone compound having an alkylene oxide structure generally used as an antistatic aid. Therefore, the antistatic agent can be localized on the surface of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention exhibits excellent antistatic performance even with a small amount of the antistatic agent.

From the above, the pressure-sensitive adhesive composition of the present invention is suitable for forming a pressure-sensitive adhesive layer having excellent stain resistance and antistatic properties.
Hereinafter, the detail of each component used for the adhesive composition of this invention is demonstrated.

<(Meth) acrylic resin (A)>
The pressure-sensitive adhesive composition has at least a (meth) acrylic resin (A) having a crosslinkable functional group (hereinafter also referred to as “specific (meth) acrylic resin”). The crosslinkable functional group in the specific (meth) acrylic resin reacts with an isocyanate compound (B) and a silicone isocyanate compound (C) described later to form a crosslinked structure. Since the silicone-based isocyanate compound (C) reacts with the specific (meth) acrylic resin to form a crosslinked structure, the silicone-based isocyanate compound (C) is easily kept anchored in the pressure-sensitive adhesive layer. Thereby, when peeling a protective film, it suppresses that a contaminating component transfers to a to-be-adhered body, and the adhesive layer formed from the adhesive composition is excellent in stain resistance.

  The specific (meth) acrylic resin has at least a crosslinkable functional group. The specific (meth) acrylic resin may be a resin formed by homopolymerizing a (meth) acrylic monomer having a crosslinkable functional group, and (meth) acryloyl having no crosslinkable functional group A resin formed by addition polymerization reaction of a monomer having a group and a monomer having a crosslinkable functional group may be used.

The monomer having a crosslinkable functional group is not particularly limited as long as it can form a crosslinked structure with an isocyanate compound (B) and a silicone-based isocyanate compound (C) described later.
Examples of the monomer having a crosslinkable functional group include monomers having a carboxy group, a methylol group, a hydroxyl group, a glycidyl group, an amide group, an amino group, and the like.
Among these, from the viewpoint of reactivity with the silicone-based isocyanate compound (C), the crosslinkable functional group may be at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amino group, and a glycidyl group. Preferably, it is at least one of a carboxy group and a hydroxyl group.
As the monomer having a crosslinkable functional group, one type may be used alone, or two or more types may be used in combination.

  Moreover, it is preferable that specific (meth) acrylic-type resin contains 2 or more types of structural units derived from the monomer which has a crosslinkable functional group, and the structural unit derived from the monomer which has a carboxy group, and a hydroxyl group. It is more preferable to contain the structural unit derived from the monomer which has.

The monomer having a carboxy group is not particularly limited. For example, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, 2- (meth) Acrylyloxyethyl succinic acid, monohydroxyethyl (meth) acrylate maleate, monohydroxyethyl (meth) acrylate fumarate, monohydroxyethyl (meth) acrylate phthalate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate , (Meth) acrylic acid dimer and ω-carboxy-polycaprolactone mono (meth) acrylate.
The monomer which has a carboxy group may be used individually by 1 type, or may use 2 or more types together.

  From the viewpoint of reactivity with the silicone-based isocyanate compound (C) described later, the monomer having a carboxy group includes acrylic acid, methacrylic acid, itaconic acid, and ω-carboxy-polycaprolactone mono (meth) acrylate. It is preferable to include at least one selected from the group consisting of acrylic acid, methacrylic acid, and ω-carboxy-polycaprolactone mono (meth) acrylate, and it is more preferable to include at least one selected from the group consisting of acrylic acid, Is more preferable.

  Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 6-hydroxy. Examples include hexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and 3-methyl-3-hydroxybutyl (meth) acrylate.

  From the viewpoint of reactivity with the silicone-based isocyanate compound (C) described later, monomers having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meta). ) It is preferable to include at least one selected from the group consisting of acrylates, and it is more preferable to include at least one of 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

It is preferable that the content rate of the structural unit derived from the monomer which has a crosslinkable functional group is 0.1 mass%-10 mass% with respect to all the structural units of specific (meth) acrylic-type resin.
When the content of the structural unit derived from the monomer having a crosslinkable functional group is 0.1% by mass to 10% by mass, at least one of an isocyanate compound (B) and a silicone-based isocyanate compound (C) described later. It is possible to sufficiently form a cross-linked structure by reacting with, and it is possible to further suppress transfer of contaminating components to the adherend.
From the above viewpoint, the content of the structural unit derived from the monomer having a crosslinkable functional group is preferably 0.5% by mass to 8% by mass, and preferably 1% by mass to 5% by mass. More preferred.

When the specific (meth) acrylic resin includes a monomer having a carboxy group as a structural unit derived from a monomer having a crosslinkable functional group, the inclusion of the structural unit derived from a monomer having a carboxy group The rate is preferably 0.1% by mass to 5% by mass with respect to all structural units of the specific (meth) acrylic resin.
When the content of the structural unit derived from the monomer having a carboxy group is 0.1% by mass to 510% by mass, it reacts with at least one of the isocyanate compound (B) and the silicone-based isocyanate compound (C) described later. Thus, the crosslinked structure can be sufficiently formed, and transfer of contaminating components to the adherend can be further suppressed.
From the above viewpoint, the content of the structural unit derived from the monomer having a carboxy group is more preferably 0.2% by mass to 5% by mass, and preferably 0.3% by mass to 3% by mass. Further preferred.

When the specific (meth) acrylic resin has a monomer having a hydroxyl group as a structural unit derived from a monomer having a crosslinkable functional group, the content of the structural unit derived from the monomer having a hydroxyl group is It is preferable that it is 0.5 mass%-10 mass% with respect to all the structural units of specific (meth) acrylic-type resin.
When the content of the structural unit derived from the monomer having a hydroxyl group is 0.5% by mass to 10% by mass, it can react with the isocyanate compound (B) described later to sufficiently form a crosslinked structure. Further, it is possible to further suppress transfer of contaminating components to the adherend.
From the above viewpoint, the content of the structural unit derived from the monomer having a hydroxyl group is more preferably 1% by mass to 9% by mass, and further preferably 2% by mass to 8% by mass.

The specific (meth) acrylic resin includes a structural unit derived from an alkyl (meth) acrylate having no crosslinkable functional group, in addition to the structural unit derived from the monomer having the crosslinkable functional group. You may go out.
When the specific (meth) acrylic resin includes a structural unit derived from an alkyl (meth) acrylate having no crosslinkable functional group, the alkyl (meth) acrylate having no crosslinkable functional group is an unsubstituted group. It is preferable that it is an alkyl (meth) acrylate, The kind in particular is not restrict | limited.
The alkyl group of the alkyl (meth) acrylate may be linear or branched. The number of carbon atoms in the alkyl group of the alkyl (meth) acrylate is preferably in the range of 1-18, and more preferably in the range of 1-12. When the carbon number of the alkyl group is within the above range, the adhesiveness suitable for the protective film tends to be excellent.

Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, and tert-butyl (meth). Acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl ( Mention may be made of (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate.
Alkyl (meth) acrylate may be used individually by 1 type, or may use 2 or more types together.

  From the viewpoint of adhesiveness suitable for the protective film, the alkyl (meth) acrylate is at least one selected from the group consisting of ethyl (meth) acrylate, n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. It is preferable to contain.

  From the viewpoint of improving the adhesion to the adherend, the content of the structural unit derived from the alkyl (meth) acrylate is 70.0% by mass to 99% with respect to all the structural units of the specific (meth) acrylic resin. It is preferable that it is .99 mass%, it is more preferable that it is 85.0 mass%-99.9 mass%, and it is still more preferable that it is 80.0 mass%-99.0 mass%.

  The specific (meth) acrylic resin is a structural unit derived from a monomer having a crosslinkable functional group and other structural units derived from an alkyl (meth) acrylate within the range in which the effects of the present invention are exhibited. A structural unit derived from a monomer (hereinafter, also referred to as “other structural unit”) may be included. The monomer constituting the other structural unit is not particularly limited as long as it can be copolymerized with a monomer having a crosslinkable functional group, and can be appropriately selected according to the purpose.

  As a monomer which comprises other structural units, a polyfunctional acrylic monomer and an aromatic monovinyl monomer are mentioned, for example.

  Examples of the polyfunctional acrylic monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol di (meth). ) Acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified di (meth) acrylate, di (meth) acryloxyethyl isocyanurate, tricyclodecane dimethanol (meth) acrylate, dimethylol dicyclopentane di (meth) ) Acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylpropane di (meth) acrylate, trime Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, diglycerol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate.

  Examples of the aromatic monovinyl monomer include styrene, α-methylstyrene, tert-butylstyrene, p-chlorostyrene, chloromethylstyrene, and vinyltoluene.

The weight average molecular weight (Mw) of the specific (meth) acrylic resin is preferably 100,000 to 1.9 million. When the weight average molecular weight (Mw) of the specific (meth) acrylic resin is in the above range, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for a protective film of the present invention exhibits more suitable adhesiveness for the protective film. It tends to be easy to do.
From the above viewpoint, the weight average molecular weight (Mw) of the specific (meth) acrylic resin is more preferably 300,000 to 1,800,000, still more preferably 400,000 to 1,500,000, and 400,000 to 1,300,000. It is especially preferable that it is 400,000 to 1,000,000.

The weight average molecular weight (Mw) of the specific (meth) acrylic resin is a value measured by the following method.
(Measurement method of weight average molecular weight (Mw))
It measures according to following (1)-(3).
(1) A specific (meth) acrylic resin solution is applied to release paper and dried at 100 ° C. for 1 minute to obtain a film-like specific (meth) acrylic resin.
(2) Using the film-like specific (meth) acrylic resin obtained in (1) and tetrahydrofuran, a sample solution having a solid content concentration of 0.2% by mass is obtained.
(3) Under the following conditions, the weight average molecular weight (Mw) of the specific (meth) acrylic resin is measured as a standard polystyrene equivalent value using gel permeation chromatography (GPC).
(conditions)
GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
Column: TSK-GEL GMHXL used Mobile phase solvent: Tetrahydrofuran Flow rate: 0.6 mL / min Column temperature: 40 ° C

  The glass transition temperature of the specific (meth) acrylic resin is preferably −40 ° C. or less and more preferably −50 ° C. or less from the viewpoint of peelability.

The glass transition temperature (Tg) of the specific (meth) acrylic resin is a molar average glass transition temperature obtained by calculation of the following formula.
1 / Tg = m ₁ / Tg ₁ + m ₂ / Tg ₂ +... + M _(k−1) / Tg _(k−1) + m _k / Tg _k
... (Formula 1)
In Formula 1, Tg ₁ , Tg ₂ ,..., Tg _(k−1) , Tg _k are absolute temperatures when each monomer constituting the specific (meth) acrylic resin is a homopolymer ( It is a glass transition temperature represented by K). m ₁ , m ₂ ,..., m _(k−1) , m _k represent the molar fraction of each monomer constituting the specific (meth) acrylic resin, and m ₁ + m ₂ +. + M _(k-1) + m _k = 1.

  The “glass transition temperature represented by the absolute temperature (K) when used as a homopolymer” is represented by the absolute temperature (K) of a homopolymer produced by polymerizing the monomer alone. Refers to the glass transition temperature. The glass transition temperature of the homopolymer was determined by using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments Co., Ltd., EXSTAR6000), measuring sample 10 mg, heating rate 10 ° C. / The measurement is performed under the conditions of minutes, and the inflection point of the obtained DSC curve is defined as the glass transition temperature of the homopolymer.

The typical monomer “glass transition temperature expressed by the homologous Celsius temperature (° C.)” is 5 ° C. for methyl acrylate, −27 ° C. for ethyl acrylate, and 103 ° C. for methyl methacrylate. N-butyl acrylate is -57 ° C, 2-ethylhexyl acrylate is -76 ° C, n-octyl acrylate is -65 ° C, isooctyl acrylate is -58 ° C, isononyl acrylate is- 58 ° C., acrylic acid is 163 ° C., ω-carboxy-polycaprolactone (n≈2) monoacrylate is −30 ° C., and 2-acryloyloxyethyl-succinic acid is −40 ° C.
For example, the glass transition temperature described above can be appropriately adjusted by using these representative monomers.

The content rate of specific (meth) acrylic-type resin in an adhesive composition can be suitably selected according to the objective. As content rate of specific (meth) acrylic-type resin, it is preferable that it is 80 mass%-99 mass% in solid content total mass of an adhesive composition, and it is more preferable that it is 85 mass%-99 mass%. Preferably, it is 90 mass%-98 mass%.
In addition, solid content gross mass means the gross mass of the residue remove | excluding volatile components, such as a solvent, from an adhesive composition.

<Isocyanate compound (B)>
The pressure-sensitive adhesive composition of the present invention contains an isocyanate compound (B). The isocyanate compound (B) reacts with a crosslinkable functional group in the specific (meth) acrylic resin to form a crosslinked structure. Thereby, it becomes possible to give moderate hardness to the adhesive layer formed from the adhesive composition of this invention. Moreover, it is possible to hold | maintain the peelability suitable for the use of a protective film, providing the adhesive force required as a protective film to an adhesive layer.

The isocyanate compound (B) is not particularly limited as long as it can react with the crosslinkable functional group in the specific (meth) acrylic resin. For example, xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, tolylene diisocyanate Bifunctional or higher functional polyisocyanate compounds such as an aromatic polyisocyanate compound represented by the formula, a hexamethylene diisocyanate, isophorone diisocyanate, a chain or cyclic aliphatic polyisocyanate compound represented by a hydrogenated aromatic polyisocyanate compound, In addition, burettes, dimers (for example, uretdione-modified products), trimers (for example, isocyanurate-modified products, iminooxadiazinedione-modified products) or pentamers of these polyisocyanate compounds. And adducts of polyol compounds such as these polyisocyanate compounds with trimethylolpropane.
These isocyanate compounds (B) may be used individually by 1 type, or may use 2 or more types together.

Among these, from the viewpoint of reactivity with the crosslinkable functional group, as the isocyanate compound (B), a linear or cyclic aliphatic polyisocyanate compound, a dimer of a linear or cyclic aliphatic polyisocyanate compound, Adducts of chain or cyclic aliphatic polyisocyanate compounds and polyol compounds, trimers or pentamers containing isocyanurate-modified products of chain or cyclic aliphatic polyisocyanate compounds, or chain or cyclic A polyisocyanate compound derived from a burette of an aliphatic polyisocyanate compound is preferred.
Furthermore, from the viewpoint of excellent reactivity and high crosslink density, and excellent compatibility with a specific (meth) acrylic resin, the isocyanate compound (B) is an isocyanurate modified product of hexamethylene diisocyanate and isophorone. It is preferably at least one of diisocyanates, and more preferably an isocyanurate-modified product of hexamethylene diisocyanate.

  A commercially available product may be used as the isocyanate compound (B). Examples of commercially available products include “Coronate HX”, “Coronate HL-S”, “Coronate L”, “Coronate 2031”, “Coronate 2030”, “Coronate 2037”, “Coronate 2234”, “Coronate 2785”, “ “Coronate T-80”, “Aquanate 200”, “Aquanate 210” and “HDI” (manufactured by Tosoh Corporation), “Sumijour N-3300”, “Death Module N-3400”, “Sumi "Jule N-75" and "Desmodur I" (manufactured by Sumika Covestrourethane Co., Ltd.), "Duranate E-405-80T", "Duranate 24A-100", and "Duranate TSE-100" [above, Asahi Kasei Manufactured by Co., Ltd.], "Takenate 500", "Takenate 600", "Takenate D-110N" "Takenate D-120N", "Takenate M-631N" and "MT-Olestar NP1200" (above, manufactured by Mitsui Chemicals, Inc.) can be suitably used.

As content of an isocyanate compound (B) (when 2 or more types are used, it is 0.5 mass part-8.0 mass parts with respect to 100 mass parts of specific (meth) acrylic-type resin). It is preferably 1.0 parts by mass to 7.0 parts by mass, more preferably 3.0 parts by mass to 6.0 parts by mass.
When the content of the isocyanate compound (B) is within the above range, peeling from the adherend tends to be further suppressed, and the adhesive force more suitable for the use of the protective film tends to be maintained.

<Silicone-based isocyanate compound (C)>
The pressure-sensitive adhesive composition contains an isocyanate compound (C) (silicone-based isocyanate compound (C)) having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B).
Since the silicone-based isocyanate compound (C) contains an isocyanate group, it reacts with a crosslinkable functional group in the specific (meth) acrylic resin to form a crosslinked structure, and is kept anchored in the pressure-sensitive adhesive layer. It becomes easy to sag. Therefore, when the protective film is peeled off, transfer of contaminating components to the adherend surface is suppressed, so that the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention exhibits excellent stain resistance. .
Moreover, since a silicone type isocyanate compound (C) has a polysiloxane structure in a molecule | numerator, it is hard to be compatible with specific (meth) acrylic-type resin, and there exists a tendency to localize on the surface vicinity of an adhesive layer. Further, since the silicone-based isocyanate compound (C) has an alkylene oxide structure in the molecule, the pressure-sensitive adhesive is in a state of being coordinated with the antistatic agent in the same manner as the silicone compound having an alkylene oxide structure used as an antistatic aid. There is a tendency to localize near the surface of the layer. Therefore, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition exhibits excellent antistatic performance even with a small amount of antistatic agent.
In this specification, the polysiloxane structure refers to a structure in which siloxane groups (—Si—O—) are linked. The number of silicon atoms contained in the polysiloxane structure in the silicone-based isocyanate compound (C) used in the present invention is preferably in the range of 1-100.

  The silicone-based isocyanate compound (C) can be obtained by a reaction between a silicone compound having a reactive group and an alkylene oxide structure and an isocyanate compound (hereinafter also referred to as “pre-reaction”).

The reactive group in the silicone compound having a reactive group and an alkylene oxide structure includes a hydroxyl group, a carboxy group, a substituted or unsubstituted amide group, a substituted or unsubstituted amino group, an epoxy group, a mercapto group, and silicon. Examples thereof include reactive groups such as a containing group.
Among these, from the viewpoint of effectively promoting the reaction between the reactive group and the NCO group in the isocyanate compound and effectively suppressing the occurrence of contamination on the adherend, the reactive group is a hydroxyl group. Preferably there is.
The reactive group may be introduced at any of both ends, one end, or side chain of the silicone compound having an alkylene oxide structure.
Here, one end means, for example, one end of the main chain of the silicone compound having a polysiloxane chain (main chain) having a repeating unit of a siloxane group. Both ends mean, for example, both ends of the main chain of the silicone compound having a molecular chain (main chain) having a repeating unit of a siloxane group.

Examples of the silicone compound having a reactive group and having an alkylene oxide structure include a compound in which an alkylene oxide structure is bonded to a silicone chain (polysiloxane main chain) in a graft form or a block form. It is done.
Examples of the compound having an alkylene oxide structure include polyethylene oxide having a reactive group, polypropylene oxide and the like, and may be a polyalkylene oxide in which ethylene oxide and propylene oxide are added in a block form or randomly.

The silicone compound having a reactive group and having an alkylene oxide structure has an alkylene oxide structure and an alkylene oxide structure in view of excellent antistatic properties and effectively suppressing contamination of the adherend. It is preferably a silicone compound containing a structure in which a hydroxyl group is bonded to the terminal (hereinafter also referred to as a “specific alkylene oxide structure-containing silicone compound”).
When the specific alkylene oxide structure-containing silicone compound has a structure in which a hydroxyl group is bonded to the terminal of the alkylene oxide structure, it is possible to exhibit better stain resistance.
The silicone compound having an alkylene oxide chain interacts with the antistatic agent (D) described later and tends to localize near the surface of the pressure-sensitive adhesive layer. As a result, it is assumed that the surface resistance value on the surface of the pressure-sensitive adhesive layer is lowered. That is, the silicone-based isocyanate compound (C) can suppress the amount of the antistatic agent in the pressure-sensitive adhesive composition of the present invention.

From the viewpoint of imparting antistatic properties and lowering the contamination to the adherend, the specific alkylene oxide structure-containing silicone compound includes a structural unit derived from dialkylsiloxane and alkyl (hydroxypolyalkyleneoxyalkyl) siloxane. It is preferable that it is a polysiloxane compound containing the derived structural unit.
The number of carbon atoms of the alkyl group in the dialkylsiloxane is preferably 1 to 4, and more preferably 1.
Moreover, it is preferable that carbon number of the alkylene oxide chain in alkyl (hydroxy polyalkylene oxyalkyl) siloxane is 2-4, and it is more preferable that it is 2-3.
The content of the alkylene oxide chain in the alkyl (hydroxypolyalkyleneoxyalkyl) siloxane is preferably 1 to 100, and more preferably 10 to 100. It is preferable that carbon number of the alkyl group in alkyl (hydroxy polyalkylene oxyalkyl) siloxane is 1-4.

  When the specific alkylene oxide structure-containing silicone compound includes a structural unit derived from dialkylsiloxane and a structural unit derived from alkyl (hydroxypolyalkyleneoxyalkyl) siloxane, the number of structural units derived from dialkylsiloxane is 100 or less. It is preferable that it is 1-80. The content of the structural unit derived from alkyl (hydroxypolyalkyleneoxyalkyl) siloxane is preferably 2 to 100, more preferably 2 to 80.

  The specific alkylene oxide structure-containing silicone compound is preferably a compound represented by the following general formula (3) or general formula (4) from the viewpoint of reducing adhesiveness, antistatic properties, and contamination on the adherend. .

  In general formula (3), p is the repeating number of a dimethylsiloxane structural unit, and represents the number of 0-100. q is the number of repeating methylpropylenesiloxane structural units having a polyethylene oxide chain and represents a number of 2 to 100. A is the number of repeating ethylene oxide structural units and represents a number of 1 to 100, respectively. Here, when the compound represented by the general formula (3) is an aggregate of a plurality of compounds, p, q, and a are average values as the aggregate of the compounds and are rational numbers.

  The repeating number a of the ethylene oxide structural unit is 1 to 100, and preferably 10 to 100. When a is 1 or more, sufficient conductivity is obtained, and the antistatic effect tends to be further improved. Further, when a is 100 or less, it tends to be localized near the surface of the pressure-sensitive adhesive layer.

Moreover, the repeating number p of a dimethylsiloxane structural unit is a number of 0-100, and it is preferable that it is a number of 1-80. When p is 0 or more, the antistatic effect tends to be improved. Further, when p is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.
Furthermore, the repeating number q of the methylpropylenesiloxane structural unit is 2 to 100, and preferably 2 to 80. When q is 2 or more, sufficient conductivity is easily obtained, and the antistatic effect tends to be improved. Moreover, when q is 100 or less, the compatibility with other components constituting the pressure-sensitive adhesive composition is further improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

  Specific examples of the compound represented by the general formula (3) include “SF-8428”, “FZ-2162”, “SH-3773M”, “FZ-77”, “FZ-2104”, “FZ-2110”. ”,“ L-7001 ”,“ L-7002 ”,“ SH-3749 ”[manufactured by Toray Dow Corning Co., Ltd.].

In General Formula (4), R ¹ and R ² each independently represent an alkylene group having 1 to 6 carbon atoms, c represents an integer of 10 to 80, and d represents the number of repeating ethylene oxide (EO) structural units. And e represents an integer of 1 or more, e represents the number of repeating propylene oxide (PO) structural units, represents an integer of 0 or more, and d + e represents an integer of 1 to 30. The order of ethylene oxide and propylene oxide may be random.

  Specific examples of the compound represented by the general formula (4) include “BY-16-201” and “SF-8427” [manufactured by Toray Dow Corning Co., Ltd.].

There is no restriction | limiting in particular as a weight average molecular weight (Mw) of a specific alkylene oxide structure containing silicone compound, For example, it is preferable that it is 1,000-20,000, and it is more preferable that it is 3,000-15,000. .
The weight average molecular weight (Mw) of the specific alkylene oxide structure-containing silicone compound can be measured in the same manner as the method for measuring the weight average molecular weight (Mw) of the specific (meth) acrylic resin described above.

  Further, the HLB value of the specific alkylene oxide structure-containing silicone compound is not particularly limited. From the viewpoint of compatibility with a specific (meth) acrylic resin, ease of localization, and adhesiveness suitable for a protective film, the HLB value is preferably 5 or more and less than 16, preferably 7 to 15. More preferably.

The HLB value is a scale indicating a balance between hydrophilicity and hydrophobicity of a silicone compound having an alkylene oxide structure. In this specification, according to the definition of the Griffin method calculated by the following formula, when the silicone having an alkylene oxide structure is a commercial product, the catalog data of the commercial product is preferentially adopted.
HLB = {(sum of formula weight of hydrophilic group moiety) / (molecular weight of silicone compound having alkylene oxide structure)} × 20

  The specific alkylene oxide structure-containing silicone compound may be selected from the above-mentioned commercially available products, and the specific alkylene oxide structure-containing silicone compound is based on a dimethylpolysiloxane main chain having silicon hydride, It may be obtained by grafting an organic compound having an unsaturated bond and a polyethylene oxide chain by a hydrosilylation reaction.

The isocyanate compound used for the pre-reaction of the silicone-based isocyanate compound (C) is not particularly limited as long as it can react with the silicone compound having the reactive group and having an alkylene oxide structure.
As such an isocyanate compound, the above-mentioned isocyanate compound (B) is mentioned, for example, It is the same as that of the specific example of an isocyanate compound (B).

  From the viewpoint of reactivity in the pre-reaction, the isocyanate compound used in the pre-reaction is at least one selected from isophorone diisocyanate or xylene diisocyanate, hexamethylene diisocyanate, and isocyanurate-modified products of polyol. Preferably, it is more preferably at least one of isophorone diisocyanate and xylene diisocyanate from the viewpoint of particularly suppressing gelation during the pre-reaction described later.

Furthermore, from the viewpoint of antistatic properties, the isocyanate compound used for the pre-reaction is preferably an isocyanate compound different from the isocyanate compound (B).
If the isocyanate compound (B) and the isocyanate compound used for the pre-reaction of the silicone-based isocyanate compound (C) are different, the isocyanate compound (B) and the silicone-based isocyanate compound (C) are hardly compatible in the pressure-sensitive adhesive layer. The silicone-based isocyanate compound (C) is more likely to be localized on the surface of the pressure-sensitive adhesive layer, so that more excellent antistatic properties tend to be obtained.

  The isocyanate compound used for the pre-reaction may be used alone or in combination of two or more. For example, when hexamethylene diisocyanate and isophorone diisocyanate are used in combination, gelation during pre-reaction tends to be further suppressed.

  The silicone-based isocyanate compound (C) preferably includes a structure represented by the following structural formula (1).

  In Structural Formula (1), r represents an integer of 1 to 100, b represents an integer of 1 to 100, and X represents a monovalent organic group containing an isocyanate group.

  The number r of methylpropylenesiloxane structural units is preferably an integer of 2 to 80. When r is 1 or more, sufficient conductivity is obtained, and the antistatic property tends to be further improved. Further, when r is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

  Although the repeating number b of an ethylene oxide structural unit is an integer of 1-100, it is preferable that it is an integer of 10-100. When b is 1 or more, sufficient conductivity is obtained, and the antistatic property tends to be improved. Further, when b is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

Examples of the monovalent organic group represented by X include a monovalent group obtained by removing one isocyanate group (NCO group) from the aforementioned bifunctional or higher functional isocyanate compound (B).
Among these, from the viewpoint of reactivity with a specific (meth) acrylic resin, the monovalent organic group represented by X includes a chain or cyclic aliphatic polyisocyanate compound, a chain or cyclic aliphatic. One isocyanate group from at least one polyisocyanate compound selected from a dimer of a polyisocyanate compound and a trimer or a pentamer including a chain or cyclic aliphatic polyisocyanate compound isocyanurate-modified product The monovalent group removed is preferably at least selected from isophorone diisocyanate, xylene diisocyanate or hexamethylene diisocyanate, hexamethylene diisocyanate dimer, and trimer or pentamer including isocyanurate-modified hexamethylene diisocyanate. One polyisocyanate A monovalent group obtained by removing one isocyanate group from a compound is more preferable, and a monovalent group obtained by removing one isocyanate group from at least one of trimers including an isocyanurate modified product of isophorone diisocyanate, xylene diisocyanate and hexamethylene diisocyanate. And a monovalent group obtained by removing one isocyanate group from at least one of isophorone diisocyanate and xylene diisocyanate is particularly preferable.
In addition, from the viewpoint of antistatic properties, the monovalent organic group represented by X may be selected from other bifunctional or higher isocyanate compounds different from the isocyanate compound (B) contained in the pressure-sensitive adhesive composition of the present invention. A monovalent group excluding one group (NCO group) is preferred.

  Specific examples of the structure represented by the structural formula (1) are shown below. Note that the structure represented by the structural formula (1) is not limited to the following exemplary structures, and is not particularly limited as long as the structure is included in the structure represented by the structural formula (1).

  From the viewpoint of stain resistance, the silicone-based isocyanate compound (C) is preferably a compound represented by the general formula (1-1) or the general formula (2), represented by the general formula (1-1). More preferably, the compound is

In general formula (1-1), p or q is each independently an integer of 0 to 100, q and r are each independently an integer of 1 to 100, a is 0 to 100, and b is 1 to 100. Each represents an integer. X represents a monovalent organic group containing an isocyanate group.
Here, when the compound represented by the general formula (1-1) is an aggregate of a plurality of compounds, p, q, r, a, and b are average values as the aggregate of the compounds and are rational numbers. .

  Although the repeating number a of an ethylene oxide structural unit is an integer of 1-100, it is preferable that it is the number of 10-100. When a is 1 or more, sufficient conductivity is obtained, and the antistatic property tends to be improved. Moreover, when a is 100 or less, the compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

Moreover, although the repeating number p of a dimethylsiloxane structural unit is an integer of 0-100, it is preferable that it is an integer of 1-80. When p is 0 or more, the antistatic property tends to be improved.
Further, when p is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.
Furthermore, it is preferable that the repeating number q of a methylpropylene siloxane structural unit is 2-80. When q is 2 or more, sufficient conductivity is obtained, and the antistatic property tends to be further improved. Moreover, when q is 100 or less, the compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

  In general formula (1-1), r and b are synonymous with r and b in structural formula (1), and their preferred ranges are also the same.

In General Formula (2), R ¹ and R ² each independently represent an alkylene group having 1 to 6 carbon atoms, c represents an integer of 10 to 80, and d represents the number of repeating ethylene oxide (EO) structural units. And e represents an integer of 1 or more, e represents the number of repeating propylene oxide (PO) structural units, represents an integer of 0 or more, and d + e represents an integer of 1 to 30. The order of the ethylene oxide structural unit and the propylene oxide structural unit may be random.

Formula (2), the alkylene group having 1 to 6 carbon atoms represented by R ¹ or R ^2, is not particularly limited, for example, methylene group, ethylene group, propylene group, butylene group It is done.

The repeating number d of the ethylene oxide structural unit is preferably an integer of 1 to 100, and more preferably an integer of 10 to 100.
When d is 1 or more, sufficient conductivity is obtained, and the antistatic property tends to be improved. Further, when d is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

The repeating number e of the propylene oxide structural unit is preferably an integer of 1 to 100, and more preferably an integer of 10 to 100.
When e is 1 or more, sufficient conductivity is obtained, and the antistatic property tends to be improved. When e is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

  The sum of the repeating number d of the ethylene oxide structural unit and the repeating number e of the propylene oxide structural unit is more preferably an integer of 1 to 50.

  Specific examples of the silicone-based isocyanate compound (C) are shown below. The silicone-based isocyanate compound (C) is not limited to the following exemplary compounds and is not particularly limited as long as it is a compound included in the compound including the structure represented by the structural formula (1).

The manufacturing method in particular of a silicone type isocyanate compound (C) is not restrict | limited, A well-known manufacturing method is applicable.
For example, by adding a predetermined amount of a silicone compound having a reactive group and having an alkylene oxide structure and an isocyanate compound into a reaction vessel in a predetermined amount, and uniformly stirring and reacting (pre-reaction), the silicone system An isocyanate compound (C) can be obtained.

  The temperature of the pre-reaction is preferably 40 ° C to 100 ° C, more preferably 45 ° C to 95 ° C, and further preferably 50 ° C to 95 ° C.

Content of a silicone type isocyanate compound (C) is 0.10 mass part or more with respect to 100 mass parts of (meth) acrylic-type resin (A).
When the content of the silicone isocyanate compound (C) is 0.10 parts by mass or more, the silicone isocyanate compound (C) contains an isocyanate group, so that the crosslinkable functional group in the specific (meth) acrylic resin. It reacts with and forms a crosslinked structure, and it becomes easy to be kept in the state anchored in the adhesive layer. Therefore, when peeling a protective film from a to-be-adhered body, transfer of a contaminating component to an to-be-adhered body is suppressed, and the adhesive layer formed from the adhesive composition exhibits the outstanding stain resistance.
Further, since the silicone-based isocyanate compound (C) has a polysiloxane structure in the molecule, it is difficult to be compatible with the specific (meth) acrylic resin and is likely to be localized near the surface of the pressure-sensitive adhesive layer. Furthermore, since the silicone-based isocyanate compound (C) has an alkylene oxide structure in the molecule, it is coordinated to the antistatic agent in the same manner as the silicone compound having an alkylene oxide structure generally used as an antistatic aid. Therefore, it tends to localize near the surface of the pressure-sensitive adhesive layer. Therefore, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition exhibits excellent antistatic performance even with a small amount of antistatic agent.
From the above viewpoint, the content of the silicone isocyanate compound (C) is preferably 0.2 parts by mass to 3 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin (A). It is more preferably 25 parts by mass to 2.5 parts by mass, and further preferably 0.3 parts by mass to 2 parts by mass.

The mass ratio [(C) / (B)] of the silicone-based isocyanate compound (C) to the isocyanate compound (B) is preferably 1/1 to 1/20.
When the mass ratio [(C) / (B)] is 1/20 or less, the isocyanate compound (B) contained in the pressure-sensitive adhesive composition does not increase excessively, and the silicone-based isocyanate compound (C) is moderate. Therefore, the contamination resistance tends to be further suppressed. When the mass ratio [(C) / (B)] is 1/1 or more, the specific (meth) acrylic resin (A) and the isocyanate compound (B) sufficiently react to form a crosslinked structure. It can form, and there exists a tendency to provide more suitable adhesive force to an adhesive layer.
From the above viewpoint, the mass ratio [(C) / (B)] is more preferably 1/2 to 1/15, and still more preferably 1/3 to 1/10.

<Antistatic agent (D)>
The pressure-sensitive adhesive composition contains an antistatic agent (D). The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition exhibits excellent antistatic performance.
Examples of the antistatic agent include ionic compounds. There is no restriction | limiting in particular as an ionic compound, An alkali metal salt, an organic salt, etc. are mentioned.
The antistatic agent is preferably an alkali metal salt or an organic salt because it has high ion dissociation properties and easily exhibits excellent antistatic properties even in a small amount.

The alkali metal salt is not particularly limited as long as it is a metal salt having lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), rubidium (Rb ⁺ ), or the like as a cation.
For example, at least one cation selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ , and Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ^— and (CF ₃ SO ₂ ) ₃ C ⁻ A metal salt composed of a seed anion can be suitably used.

Among these, alkali metal salts include LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ (LiTFS), Li (FSO ₂ ) ₂ N, Li (CF ₃ ) from the viewpoint of antistatic properties. It is preferably a lithium salt such as SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, and LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, and Li (CF ₃ SO ₂ ) ₃ C are more preferable.
An alkali metal salt may be used individually by 1 type, or may be used in combination of 2 or more type.

The organic salt contains an organic cation and its counter ion. Organic salts include, for example, ionic solids having a melting point of 30 ° C. or higher and ionic liquids having a melting point of less than 30 ° C.
As an organic salt, it is preferable that melting | fusing point is 30 degreeC or more. When the melting point of the organic salt is 30 ° C. or higher, it is preferable that the migration to the adherend is small and the contamination is low.
Examples of the organic cation include an imidazolium cation, a pyridinium cation, an alkylpyrrolidinium cation, an ammonium cation having an organic group as a substituent, a sulfonium cation having an organic group as a substituent, and a phosphonium cation having an organic group as a substituent. Can be mentioned. Among these, from the viewpoint of antistatic properties, the organic cation is preferably a pyridinium cation or an imidazolium cation.

The anion part which becomes a counter ion of the organic cation is not particularly limited, and may be either an inorganic anion or an organic anion. Among them, in particular, it is excellent in antistatic properties, is preferably a fluorine-containing anion containing a fluorine atom, more hexafluorophosphate anions _- is preferably (PF ^6).

  Preferable examples of the organic salt include pyridinium salt, imidazolium salt, alkylammonium salt, alkylpyrrolidinium salt, alkylphosphonium salt and the like. Among these, the organic salt is preferably a pyridinium salt or an imidazolium salt, and more preferably a salt of a pyridinium cation, an imidazolium cation, and a fluorine-containing anion.

As content of antistatic agent (D), it is preferable that it is 0.05 mass part-0.50 mass part with respect to 100 mass parts of specific (meth) acrylic-type resin, and 0.10 mass part-0. More preferably, it is 30 parts by mass.
When the content of the antistatic agent (D) is 0.05 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic resin, the antistatic property tends to be excellent. When the content of the antistatic agent (D) is 0.50 parts by mass or less, the efficiency of the antistatic effect with respect to the content of the antistatic agent (D) tends to be higher.

(Other silicone compounds)
The pressure-sensitive adhesive composition of the present invention may contain a silicone compound other than the silicone-based isocyanate compound (C) (hereinafter also referred to as “other silicone compound”) as long as the effects of the present invention are not impaired.

Examples of the other silicone compounds include silicone compounds having a reactive group and an alkylene oxide structure, which are used in the pre-reaction of the silicone-based isocyanate compound (C). In addition, it is the same as the specific example of the silicone compound having an alkylene oxide structure, and the preferred range is also the same.
When other silicone compounds are included, the antistatic property can be further improved.
Another silicone compound may be used individually by 1 type, or may use 2 or more types together.

When the pressure-sensitive adhesive composition contains another silicone compound, the content of the other silicone compound is 0.05 parts by mass to 1 part by mass with respect to 100 parts by mass of the specific (meth) acrylic resin. Is more preferable, it is more preferable that it is 0.05 mass part-0.7 mass part, and it is still more preferable that it is 0.05 mass part-0.3 mass part.
When the content of the other silicone compound is 0.05 parts by mass or more, the antistatic property tends to be excellent. Moreover, generation | occurrence | production of the contamination (spider) to a to-be-adhered body is suppressed because content of another silicone compound is 1 mass part or less, and compatibility with specific (meth) acrylic-type resin falls. It is possible to further suppress the white turbidity that occurs.

((Meth) acrylic oligomer)
The pressure-sensitive adhesive composition of the present invention may contain a (meth) acrylic oligomer.
The (meth) acrylic oligomer is preferably a (meth) acrylic oligomer containing an alkylene oxide structural unit from the viewpoint of exhibiting better antistatic properties and stain resistance to the adherend.

  It is inferred that the (meth) acrylic oligomer contains an alkylene oxide structural unit and has a molecular weight smaller than that of the specific (meth) acrylic resin, so that it can move relatively easily in the pressure-sensitive adhesive composition. The As a result, the surface resistance value of the pressure-sensitive adhesive composition can be more effectively reduced, and more excellent antistatic properties can be imparted.

  The alkyleneoxy group contained in the alkylene oxide structural unit is preferably an alkyleneoxy group having 2 to 4 carbon atoms, and more preferably an alkyleneoxy group having 2 to 3 carbon atoms.

The content of the alkyleneoxy group can be appropriately selected depending on the purpose and the like. From the viewpoint of antistatic properties, the content of the alkyleneoxy group is preferably 20 or more, more preferably 20 to 100, still more preferably 20 to 50. When the content of the alkyleneoxy group is 20 or more, there is a tendency to exhibit more remarkable antistatic properties by the combination with the above-described antistatic agent (D).
In addition, the content number of an alkyleneoxy group becomes a rational number which is an average value of the content number when two or more structural units having an alkyleneoxy group are included in the (meth) acrylic oligomer.

  The terminal portion of the alkyleneoxy group may be a hydroxyl group or an alkoxy group, and is preferably an alkoxy group from the viewpoint of antistatic properties. When the terminal part of the polyalkylene oxide group is an alkoxy group, the alkoxy group preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.

Even if the structural unit derived from the alkyleneoxy group is derived from a monomer having an alkyleneoxy group and a vinyl group, an alkyleneoxy group was introduced into the structural unit having no alkyleneoxy group by a polymer reaction. It may be a thing.
From the viewpoint of productivity, the structural unit derived from an alkyleneoxy group is preferably derived from a monomer having an alkyleneoxy group and a vinyl group.

Specific examples of the monomer having an alkyleneoxy group and a vinyl group include polyethylene glycol (meth) acrylate, methoxypolyethyleneoxy (meth) acrylate, ethoxypolyethyleneoxy (meth) acrylate, polypropylene glycol (meth) acrylate, and methoxypolypropyleneoxy. (Meth) acrylate, ethoxy polypropyleneoxy (meth) acrylate, etc. are mentioned.
Among these, at least one selected from the group consisting of methoxypolyethyleneoxy (meth) acrylate and methoxypolypropyleneoxy (meth) acrylate is preferable, and methoxypolyethyleneoxy (meth) acrylate and propylene oxide group having an ethyleneoxy group content of 20 or more. More preferred is at least one selected from the group consisting of methoxypolypropyloxyoxy (meth) acrylates having a content of 20 or more.

  The (meth) acrylic oligomer may contain one type of structural unit derived from an alkyleneoxy group, or may contain two or more types in combination.

  The content of the structural unit derived from the alkyleneoxy group in the (meth) acrylic oligomer is 1% by mass to 50% by mass with respect to the total mass of the (meth) acrylic oligomer from the viewpoint of antistatic properties. It is preferably 1% by mass to 30% by mass, more preferably 5% by mass to 20% by mass.

The (meth) acrylic oligomer preferably contains at least one structural unit derived from a monomer having a carboxy group in addition to the structural unit derived from an alkyleneoxy group.
When the (meth) acrylic oligomer contains a structural unit derived from a monomer having a carboxy group, it tends to contribute to an improvement in peelability.
The type of the monomer having a carboxy group is not particularly limited, and examples thereof include a monomer having a carboxy group in the aforementioned (meth) acrylic resin. From the viewpoint of releasability, the monomer having a carboxy group is preferably (meth) acrylic acid.

  As a content rate of the structural unit derived from the monomer which has a carboxy group, it is 0.1 mass%-10 mass% with respect to all the structural units of a (meth) acrylic-type oligomer from a viewpoint of making pollution low. It is preferably 0.5% by mass to 7% by mass, more preferably 1% by mass to 5% by mass.

The (meth) acrylic oligomer may further contain a structural unit derived from alkyl (meth) acrylate. The structural unit derived from alkyl (meth) acrylate tends to contribute to the adjustment of adhesive strength.
The alkyl (meth) acrylate has the same meaning as the alkyl (meth) acrylate in the specific (meth) acrylic resin described above, and specific examples thereof are also the same.
When the pressure-sensitive adhesive layer is exposed to a high-temperature and high-humidity environment, the alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having 4 to 12 carbon atoms in that high durability is exhibited. It is more preferable that it is a C4-C12 alkyl (meth) acrylate which has a branched chain, and it is still more preferable that it is 2-ethylhexyl methacrylate.

From the viewpoint of durability, the content of the structural unit derived from the alkyl (meth) acrylate is preferably 65% by mass or more and 75% by mass or more based on the total structural unit of the (meth) acrylic oligomer. It is more preferable, and it is still more preferable that it is 80 mass% or more.
Moreover, as content rate of the structural unit derived from alkyl (meth) acrylate, it is preferable that it is 99 mass% or less with respect to all the structural units of a (meth) acrylic-type oligomer from a durable point, and is 95 mass%. More preferably, it is more preferably 90% by mass or less.

The (meth) acrylic oligomer is a structural unit derived from a monomer having a carboxy group, a structural unit derived from an alkyl (meth) acrylate, and a single unit having an alkyleneoxy group within the range in which the effects of the present invention are exhibited. You may include structural units (other structural units) other than the structural unit derived from a monomer.
When the (meth) acrylic oligomer includes other structural units, the structural unit derived from the monomer having a carboxy group in the total structural units of the (meth) acrylic oligomer, the configuration derived from alkyl (meth) acrylate The total content of the structural units derived from the unit and the monomer having an alkyleneoxy group is preferably 80% by mass or more, and 90% by mass or more with respect to all the structural units of the (meth) acrylic oligomer. It is more preferable that it is 95 mass% or more.

  Examples of the monomer constituting the other structural unit include the above-described monomers having a hydroxyl group and monomers having a cyclic group, and specific examples and preferred ranges thereof are also the same.

  The weight average molecular weight (Mw) of the (meth) acrylic oligomer is not particularly limited as long as it is smaller than the weight average molecular weight (Mw) of the specific (meth) acrylic resin. The weight average molecular weight (Mw) of the specific (meth) acrylic oligomer is preferably 3,000 to 60,000, and more preferably 3,000 to 20,000. There exists a tendency which can suppress generation | occurrence | production of the contamination with respect to a to-be-adhered body more effectively as a weight average molecular weight (Mw) is 3,000 or more. Further, when the weight average molecular weight (Mw) is 60,000 or less, the antistatic property tends to be further improved.

  The weight average molecular weight (Mw) of the (meth) acrylic oligomer can be measured in the same manner as the method for measuring the weight average molecular weight (Mw) of the specific (meth) acrylic resin described above.

  The glass transition temperature (Tg) of the (meth) acrylic oligomer is preferably 50 ° C. or lower. If the Tg of the (meth) acrylic oligomer is 50 ° C. or lower, an increase in the adhesive strength due to the heat treatment can be suppressed, so that the peelability tends to be more excellent.

  The glass transition temperature of the (meth) acrylic oligomer can be calculated in the same manner as the method for calculating the glass transition temperature of the specific (meth) acrylic resin described above.

As content of (meth) acrylic-type oligomer, it is (meth) acrylic-type resin 100 from the viewpoint of maintaining the peelability suitable for the use of a protective film, providing the adhesive layer with the adhesive force required as a protective film. It is preferably 0.05 parts by mass to 2 parts by mass, more preferably 0.1 parts by mass to 1.5 parts by mass, and 0.1 parts by mass to 1.2 parts by mass with respect to parts by mass. More preferably.
When the content of the (meth) acrylic oligomer is 0.05 part by mass to 2 parts by mass, the peelability suitable for the use of the protective film is further provided while providing the adhesive layer with the adhesive force necessary for the protective film. It becomes possible to hold.

<Other ingredients>
In addition to the specific (meth) acrylic resin, isocyanate compound (B), silicone-based isocyanate compound (C), antistatic agent (D) and (meth) acrylic oligomer, the pressure-sensitive adhesive composition, Resins other than specific (meth) acrylic resins, crosslinking agents other than isocyanate compounds, crosslinking catalysts, weathering stabilizers, tackifiers, plasticizers, softeners, peeling aids, dyes, pigments, inorganic fillers, surfactants Etc. can be contained appropriately.

  Examples of the crosslinking catalyst include a catalyst that promotes dissociation of the blocking agent of the blocked isocyanate compound, and a catalyst that promotes the reaction between the isocyanate group regenerated by dissociation and other functional groups.

As the crosslinking catalyst, a known catalyst can be used without particular limitation. For example, an organometallic compound, a tertiary amine compound, a metal salt, etc. are mentioned.
Specific examples of the organometallic compound include dioctyltin dilaurate and 1,3-diacetoxytetrabutylstannoxane.
Specific examples of the tertiary amine compound include tertiary amines such as triethylenediamine and N-methylmorpholine.
Among these, as the crosslinking catalyst, a tertiary amine compound is preferable.

[Usage]
The pressure-sensitive adhesive composition of the present invention is preferably used for an optical member. Since the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention is excellent in stain resistance and antistatic properties, it can be suitably used as a protective film for optical members.

[Protective film]
The protective film of this invention has an adhesive layer which is a crosslinked material of the adhesive composition for protective films, and a base material at least.
The pressure-sensitive adhesive layer included in the protective film exhibits excellent stain resistance and antistatic properties with respect to the optical member.

The substrate used for the protective film is not particularly limited as long as an adhesive layer can be formed on the substrate.
From the viewpoint of inspection and management of optical members by fluoroscopy, the base materials include polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylic resins. Examples thereof include a film using a resin selected from a series resin.
Especially, as a base material, the film using a polyester-type resin is preferable from a viewpoint of surface protection performance, and when the practicality is considered, the film using a polyethylene terephthalate (PET) resin is more preferable.

  Generally as thickness of a base material, it can be 500 micrometers or less, Preferably they are 5 micrometers-300 micrometers, More preferably, they are 10 micrometers-200 micrometers.

  An antistatic layer may be provided on one side or both sides of the substrate. Moreover, in order to improve the adhesiveness of an adhesive layer and a base material, the corona discharge process etc. may be given to the surface at the side in which the adhesive layer of a base material is provided.

On the base material, a pressure-sensitive adhesive layer that is a cross-linked product of the pressure-sensitive adhesive composition is provided.
As a method for forming the pressure-sensitive adhesive layer, for example, a method is adopted in which the pressure-sensitive adhesive composition is diluted as it is or with an appropriate solvent as necessary, and this is applied to a substrate and then dried to remove the solvent. can do.
First, the pressure-sensitive adhesive composition is applied on a release sheet made of an appropriate film such as paper or polyester film that has been subjected to a release treatment with a silicone resin, and then dried by heating to form a pressure-sensitive adhesive layer, and then peeled off. A method of transferring the pressure-sensitive adhesive layer to the substrate by pressing the pressure-sensitive adhesive layer side of the sheet to the substrate can also be employed.

  The thickness of the pressure-sensitive adhesive layer formed on the substrate can be appropriately set according to the adhesive force required for the protective film, the surface roughness of the optical member, and the like. The thickness of the pressure-sensitive adhesive layer is generally 1 μm to 100 μm, preferably 5 μm to 50 μm, and more preferably about 15 μm to 30 μm.

  That is, the pressure-sensitive adhesive layer for the optical member preferably has an adhesive force (peeling force) at 180 ° peeling (peeling speed 0.3 m / min) (low-speed peeling) of 0.05 N / 25 mm or more, and 0.06 N / More preferably, it is 25 mm or more. There is a tendency that the adhesive force at the time of low-speed peeling is 0.05 N / 25 mm or more, and the occurrence of turning or shifting is further suppressed.

  Moreover, since the workability at the time of high-speed peeling decreases as the adhesive strength increases, the adhesive strength (peeling force) at a peeling speed of 30 m / min (high-speed peeling) is preferably less than 1.5 N / 25 mm. / 25 mm is more preferable, and it is further more preferable that it is less than 0.9 N / 25 mm.

  From the viewpoint of suppressing the influence on the optical member due to charging at the time of peeling, the pressure-sensitive adhesive composition is an absolute value of peeling voltage at the time of peeling at 30 m / min with respect to a polarizing plate (trade name: SRDB31E, manufactured by Sumitomo Chemical Co., Ltd.) Is preferably 0.9 kV or less, more preferably 0.7 kV or less, and even more preferably 0.5 kV or less.

Further, from the viewpoint of preventing charging on the film side at the time of peeling, the surface resistance value of the pressure-sensitive adhesive layer is 4.9E + 11 (Ω / □) (that is, 4.9 × 10 ¹¹ Ω / □) or less. preferable.

  The thickness of the pressure-sensitive adhesive layer formed on the substrate can be appropriately set according to the adhesive force required for the optical member surface protective film, the optical member surface roughness, etc., and is generally 1 μm to 100 μm, preferably 5 μm. A thickness of about 50 μm, more preferably about 15 μm to 30 μm can be exemplified.

  As an optical member, the member which comprises apparatuses (optical apparatus), such as an image display apparatus and an input device, or the member used for these apparatuses is mentioned. Specific examples of the optical member include, for example, a polarizing plate, an AG polarizing plate, a wave plate, a retardation plate including a wave plate such as 1/2, 1/4, a viewing angle compensation film, an optical compensation film, a brightness enhancement film, a light guide film, and the like. Examples thereof include those used for display devices such as a light plate, a reflective film, an antireflection film, a transparent conductive film such as an ITO film, a prism sheet, a lens sheet, and a diffusion plate.

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

(Silicone crosslinking agent 1 (silicone isocyanate compound (C))
-Production of silicone cross-linking agent 1-
Isophorone diisocyanate (IPDI) (trade name: Desmodur I, manufactured by Sumika Covestrourethane Co., Ltd.) is added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a reflux condenser, and a dropping funnel. 82 parts by mass of SH-3773M (chemical name: polyether-modified silicone compound, manufactured by Toray Dow Corning Co., Ltd.) was charged, and the air in the reaction vessel was replaced with nitrogen gas for 30 minutes, and the internal temperature was 50 ° C. The silicone crosslinking agent 1 was obtained by stirring for 4 hours. The composition of the obtained silicone crosslinking agent 1 is shown in Table 1.

(Silicone crosslinking agent 2 to silicone crosslinking agent 8)
Silicone crosslinking agent 2 to silicone crosslinking agent 8 were prepared in the same manner as in the production of silicone crosslinking agent 1 except that the composition of silicone crosslinking agent 1 was changed as shown in Table 1.

Abbreviations in Table 1 are as follows.
SH-3773M: Specific alkylene oxide structure-containing silicone compound (polyether-modified silicone compound, manufactured by Toray Dow Corning Co., Ltd.) (polysiloxane compound represented by general formula (3))
SF-8427: Specific alkylene oxide structure-containing silicone compound (carbinol-modified silicone compound (both terminal-modified), manufactured by Toray Dow Corning Co., Ltd.) (polysiloxane compound represented by general formula (4))
Desmodur I: Isocyanate compound (Chemical name: Isophorone diisocyanate (IPDI), manufactured by Sumika Covestro Urethane Co., Ltd.)
N-3300: Isocyanate compound (chemical name: isocyanurate-modified hexamethylene diisocyanate, trade name: Sumidur N-3300, manufactured by Sumika Covestro Urethane Co., Ltd., solid content: 100% by mass)
Takenate 500: Isocyanate compound (chemical name: xylene diisocyanate (XDI), manufactured by Mitsui Chemicals, Inc.)

(Production Example 1)
-Production of (meth) acrylic resin (A)-
In a reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser, 171.0 parts by mass of ethyl acetate and 249 parts by mass of tert-butanol were placed. In another reaction vessel, 217.8 parts by mass of n-butyl acrylate (nBA), 360.0 parts by mass of 2-ethylhexyl acrylate (2EHA), and 18.0 parts by mass of 4-hydroxybutyl acrylate (4HBA) as monomers. And 4.2 parts by mass of acrylic acid (AA) were added and mixed to obtain a monomer mixture. Of this monomer mixture, 20.0% by mass was added to the reaction vessel, the air in the reaction vessel was then replaced with nitrogen gas, and then 0.08% by mass of azobisisobutyronitrile (AIBN) as a polymerization initiator. The temperature of the mixture in the reaction vessel was raised to 85 ° C. in a nitrogen atmosphere with stirring to initiate the initial reaction. After the initial reaction was almost completed, the remaining monomer mixture 80.0% by mass, ethyl acetate 88.0 parts by mass and AIBN 0.80 parts by mass were respectively reacted for about 2 hours, and then continuously. And further reacted for 2 hours. Thereafter, a solution prepared by dissolving 0.60 parts by mass of tert-butyl peroxypivalate in 132.0 parts by mass of ethyl acetate was added dropwise to the above mixture over 1 hour and further reacted for 1.5 hours. After completion of the reaction, a (meth) acrylic resin (A) solution was obtained. Table 2 shows the weight average molecular weight (Mw) of the obtained (meth) acrylic resin (A) solution.
The weight average molecular weight (Mw) is measured by the method described above.

(Production Example 2 to Production Example 4)
In Production Example 1, the monomer was changed as shown in Table 2, and the weight average molecular weight was adjusted by appropriately changing the amount of initiator and polymerization conditions, etc., and the same method as in Production Example 1, A (meth) acrylic resin (A) solution was prepared. Table 2 shows the composition (mass%) and weight average molecular weight (Mw) of the solid content of the (meth) acrylic resin (A) solution obtained.
The weight average molecular weight (Mw) is measured by the method described above.

  In Table 2, “-” indicates that the corresponding component is not included.

-Production of (meth) acrylic oligomers-
In a reaction vessel equipped with a thermometer, a stirring blade, a nitrogen gas inlet tube, a cooler, and a dropping funnel, 100.0 parts of methyl ethyl ketone was placed and heated to reflux temperature while stirring under a nitrogen atmosphere. In the dropping funnel, 68.0 parts by mass of n-butyl methacrylate (nBMA), 20.0 parts by mass of 2-hydroxyethyl methacrylate (2HEMA), and methoxypolyethylene glycol methacrylate (the number of alkylene oxide groups contained in advance): 23) A mixed solution of 10 parts, 2.0 parts by weight of acrylic acid (AA), 100.0 parts by weight of methyl ethyl ketone and 5.0 parts by weight of azobisisobutyronitrile is placed in a reaction vessel at reflux temperature over 120 minutes. Sequentially added. Then, it was made to react, maintaining a reflux temperature for 240 minutes, and reaction was complete | finished. In this way, a (meth) acrylic oligomer solution was obtained.
The obtained (meth) acrylic oligomer solution had a solid content of 33.0% by mass and a weight average molecular weight (Mw) of 7,000. The weight average molecular weight (Mw) is measured by the method described above.

Example 1
222.2 parts by mass (solid content) of the (meth) acrylic resin (A) solution (solid content 45%) prepared in Production Example 1 in a four-necked flask equipped with a stirring blade, thermometer, cooler, and dropping funnel 100 parts by mass), 0.9 parts by mass of the (meth) acrylic oligomer solution prepared above (solid content 33%) (0.80 parts by mass as solids), and LiTFS (chemical) as the antistatic agent (D) Name: LiCF ₃ SO ₃ , Morita Chemical Co., Ltd.) 0.25 part by mass was charged, and the mixture was stirred for 4.0 hours while maintaining the liquid temperature in the flask at around 25 ° C. 12.0 parts by mass (3.00 parts by mass as a solid content) of Sumidur N-3300 diluted as the isocyanate compound (B) (chemical name: hexamethylene diisocyanate (HMDI), manufactured by Sumika Cobestrourethane Co., Ltd.), The silicone cross-linking agent 1 prepared in (1) was added in an amount corresponding to 0.38 parts by mass and stirred sufficiently to obtain a pressure-sensitive adhesive composition solution.

[Evaluation]
−Contamination resistance−
<Preparation of protective film>
The pressure-sensitive adhesive composition solution obtained above is coated on a release film (trade name: film binder 25E0010BD, thickness 100 μm, manufactured by Fujimori Kogyo Co., Ltd.) surface-treated with a silicone release agent. It apply | coated so that a work amount might be 15 g / m < ² >, and it dried with the hot air circulation type dryer at 100 degreeC for 60 second. Thereafter, the release film coated surface to which the pressure-sensitive adhesive composition solution was applied was subjected to a surface treatment with a separately prepared silicone release agent (trade name: Film Vina 100E-0010NO23, thickness 25 μm, Fujimori Kogyo Co., Ltd. ))) To obtain a laminate. The laminate was pressed through a pair of pressure nip rolls and bonded together, and then cured under conditions of 23 ° C. and 50% RH for 96 hours to produce a non-base type pressure-sensitive adhesive sheet.

<Silicone reaction rate>
A 250-mesh wire mesh (manufactured by Manabe Industries Co., Ltd) To the product). Next, the remaining release film was peeled off and wrapped with a 250 mesh wire mesh so that the adhesive would not leak when immersed in the solvent, to prepare a wire mesh with an adhesive. This operation was repeated to prepare six wire meshes with adhesive, and the total mass of the adhesive was measured.
Total mass of adhesive = mass of wire mesh with adhesive (g) −mass of wire mesh (g)

  Six wire meshes with pressure-sensitive adhesive were immersed in a container containing 80 g of ethyl acetate and allowed to stand at 23 ° C. for 3 days. After the elapse of 3 days, all six wire meshes with pressure-sensitive adhesive were taken out from the container, and the immersed ethyl acetate was filtered through a 250 mesh wire mesh to obtain a sample sample.

First, 10 g to 11 g of sample samples were weighed and collected in a 50 ml Teflon (registered trademark) dish, and then sufficiently evaporated to dryness on a hot plate at around 80 ° C. and allowed to cool. After standing to cool, the residue was transferred to a polypropylene (PP) watch glass, 1.5 ml of hydrochloric acid (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and about 5 minutes on a hot plate at around 80 ° C. After dissolving by heating, it was allowed to cool again.
After allowing to cool again, the remaining solution was poured into a plastic container, and an evaporating dish made of perfluoroalkoxy (PFA) was washed with 10 ml of distilled water, and then the washing solution was poured into a plastic container, and the residue was used as a measurement sample.
The amount of silicon (Si) atoms contained in the measurement sample is measured under the following measurement conditions using an inductively coupled plasma emission spectroscopy (ICP-AES) device (model number: ICPS-7510, manufactured by Shimadzu Corporation). And quantified.

<Measurement conditions>
Analytical instrument: Inductively coupled plasma emission spectrometer (ICP-AES) (model number: ICPS-7510, manufactured by Shimadzu Corporation)
Spray chamber: Cyclone chamber Measurement position: Lateral observation Nebulizer: Coaxial nebulizer High frequency power: 1.2 kW
Coolant gas: 14.0 L / min Carrier gas: Argon gas, 0.7 L / min Quantification method: Performed by calibration curve method Sample concentration for calibration curve: 0.2 ppm, 1.0 ppm, 5.0 ppm (Wako Pure Chemical Industries, Ltd. ( A standard solution for atomic absorption (Si 1000ppm))

  Based on the detected amount of silicon (Si) atoms, the silicone reaction rate was calculated by the following formula.

Silicone reaction rate (%) = (1− (A / B)) × 100
A: amount of silicone compound eluted into ethyl acetate (ppm) = value of amount of detected silicon (Si) atoms (ppm) −0.04 (ppm)
The detected amount of silicon (Si) atoms is a numerical value obtained by subtracting 0.04 ppm as the influence of the silicone compound contained in the release film.
B: Amount of silicone compound contained in pressure-sensitive adhesive layer (ppm) = (w × s) / e × t × 1000000
w: Total mass of adhesive (g)
s: Ratio of silicone compound contained in pressure-sensitive adhesive (% by mass)
e: Mass of ethyl acetate; 80 (g)
t: Si atomic weight in the silicone compound (ICP-AES measured value, SH-3773M (side-chain polyether-modified silicone compound (manufactured by Toray Dow Corning)) is 0.20, and SF -8427 (both terminal polyether-modified silicone compound (manufactured by Dow Corning Toray)) has an Si atomic weight of 0.45. )

The silicone reaction rate in Example 1 is 94.5%, which is a value obtained using the following numerical values.
A: 0.24-0.04 = 0.20
B: (w × s) /e×t×1000000=3.67
w: 0.51 (g)
s: 0.30 / (100 + 0.80 + 0.25 + 0.38 + 0.13 + 3.0)
= 0.002869
e: 80 (g)
t: 0.20

The s (ratio (mass%) of the silicone compound contained in the pressure-sensitive adhesive) in Example 1 is a value obtained by dividing the silicone compound content of 0.30 by the total mass of the active ingredient of 104.25.
The total mass of the active ingredients is (meth) acrylic resin content 100, (meth) acrylic oligomer content 0.80, antistatic agent content 0.25, silicone isocyanate compound (C) The content is 0.38, the content of the unreacted isocyanate compound in the pre-reaction is 0.13, and the content of the isocyanate compound (B) is 3.0.

The calculated silicone reaction rate was evaluated for contamination resistance according to the following evaluation criteria. The results are shown in Table 3.
If the silicone reaction rate is high, the stain resistance of the pressure-sensitive adhesive composition is excellent. If the evaluation was “A” or higher, it was judged that the stain resistance was excellent.

(Evaluation criteria)
AA: 90% or more.
A: 60% to less than 90%.
B: 40% to less than 60%.
C: Less than 40%.

-Antistatic property-
<Preparation of protective film>
The pressure-sensitive adhesive composition solution is applied to a polyethylene terephthalate (PET) film (trade name: Teijin Tetron Film G2, thickness 38 μm, manufactured by Teijin DuPont Films) so that the coating amount after drying is 15 g / m ^2. And dried with a hot air circulating dryer at 100 ° C. for 60 seconds. After that, the coated surface on which the adhesive composition solution was applied was overlaid on the surface treated surface of a release film (trade name: film binder 25E0010BD, thickness 100 μm, manufactured by Fujimori Kogyo Co., Ltd.) surface-treated with a silicone-based release agent. A laminated body was obtained. The laminate was pressed through a pair of pressure nip rolls and bonded together, and then cured for 96 hours under the conditions of 23 ° C. and 50% RH to prepare an adhesive sheet.
The surface resistance value of the pressure-sensitive adhesive sheet prepared above was measured under the conditions of 23 ° C., 50% RH, and applied voltage of 100 V using a surface resistance measuring device (manufactured by Advantest Co., Ltd .: R12704 REISTIVITY CHAMBER). Evaluated according to. The results are shown in Table 3.
The smaller the surface resistance value, the better the antistatic property. In addition, if evaluation was "C" or more, it evaluated that it had antistatic property.

(Evaluation criteria)
A: The surface resistance value is less than 1.0 × 10 ¹¹ Ω / □, and the antistatic property is very excellent.
B: The surface resistance value is 1.0 × 10 ¹¹ Ω / □ to 4.9 × 10 ¹¹ Ω / □, and the antistatic property is excellent.
C: The surface resistance value exceeds 4.9 × 10 ¹¹ Ω / □ and is 9.9 × 10 ¹¹ Ω / □ or less, and has antistatic properties.
D: The surface resistance value exceeds 9.9 × 10 ¹¹ Ω / □, and the antistatic property is inferior.

(Examples 2 to 18 and Comparative Examples 1 to 3 and Comparative Example 5)
In Production Example 1, a pressure-sensitive adhesive composition was prepared in the same manner as in Production Example 1 except that the monomer composition shown in Table 1 was changed and the amount of initiator was appropriately adjusted. Using the prepared pressure-sensitive adhesive composition, a protective film was produced in the same manner as in Example 1, and each evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

(Comparative Example 4)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube and a reflux condenser, and a dropping funnel, 118 parts by mass of Desmodur I (chemical name: isophorone diisocyanate, manufactured by Sumika Covestro Urethane Co., Ltd.) 82 parts by mass of SH-8400 (side-chain polyether-modified non-reactive silicone compound, manufactured by Toray Dow Corning Co., Ltd.) was charged, and the air in the reaction vessel was replaced with nitrogen gas for 30 minutes. While maintaining, the mixture was stirred for 4 hours to prepare a mixed solution of a non-reactive silicone compound and an isocyanate compound.
In Comparative Example 4, the liquid mixture of the non-reactive silicone compound and isocyanate compound obtained above, the (meth) acrylic resin (A) prepared in Production Example 1, the isocyanate compound (B), and an antistatic agent (D) was mixed with the compounding ratio of Table 1, and the adhesive composition solution was prepared. Using the prepared pressure-sensitive adhesive composition, a protective film was produced in the same manner as in Example 1, and each evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

  Abbreviations in Table 3 are as follows. In Table 3, “-” indicates that the corresponding component is not included or cannot be measured, and “ND” indicates that it cannot be detected.

N-3300: Isocyanate compound (chemical name: isocyanurate-modified hexamethylene diisocyanate, trade name: Sumidur N-3300, manufactured by Sumika Covestro Urethane Co., Ltd., solid content: 100% by mass)
IPDI: isocyanate compound (chemical name: isophorone diisocyanate, trade name: Desmodur I, manufactured by Sumika Covestro Urethane Co., Ltd.)
XDI: isocyanate compound (chemical name: xylene diisocyanate (XDI), trade name: Takenate 500, manufactured by Mitsui Chemicals, Inc.)
LiTS: Antistatic agent (Chemical name: Li (CF ₃ SO ₂ ) O, manufactured by Morita Chemical Co., Ltd.)
MP-402: antistatic agent (chemical name: trimethyldodecyl ammonium bis (fluorosulfonyl) imide, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
SH-3773M: Specific alkylene oxide structure-containing silicone compound (side-chain polyether-modified silicone compound, manufactured by Toray Dow Corning Co., Ltd.)
SH-8400: Silicone compound (side-chain polyether-modified non-reactive silicone compound, manufactured by Toray Dow Corning Co., Ltd.)
DOBDL: cross-linking catalyst (chemical name: dioctyltin dilaurate, trade name: OT-1, manufactured by ADEKA Corporation, appropriately diluted with acetylacetone)

In Table 3, the unreacted isocyanate compound means a reactive group and an alkylene oxide structure in a pre-reaction of a silicone compound having a reactive group and an alkylene oxide structure with an isocyanate compound. It means an isocyanate compound that has not reacted with the silicone compound.
In Table 3, SH-3773M (*) means a silicone compound having a reactive group and not having reacted with the isocyanate compound and having an alkylene oxide structure in the preparation of the silicone isocyanate compound (C). .

(Meth) acrylic resin (A) having at least a crosslinkable functional group, isocyanate compound (B), and isocyanate compound (C) having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B) (silicone type) Isocyanate compound (C)) and antistatic agent (D), and the content of the isocyanate compound (C) is 0.10 mass relative to 100 parts by mass of the (meth) acrylic resin (A). The pressure-sensitive adhesive layer, which is a cross-linked product of the pressure-sensitive adhesive composition of Example 1 to Example 18 that is greater than or equal to the part, was excellent in stain resistance and antistatic properties.
In particular, the pressure-sensitive adhesive layer that is a cross-linked product of the pressure-sensitive adhesive composition of Example 1 was particularly excellent in stain resistance and antistatic properties. In Example 1, the silicone crosslinking agent 1 (silicone isocyanate compound (C)) was prepared using another isocyanate compound different from the isocyanate compound (B).

On the other hand, the content of the silicone isocyanate compound (C) is less than 0.10 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin (A). In the preparation of the silicone-based isocyanate compound (C), the pressure-sensitive adhesive layer is a reactive group and the amount of the isocyanate compound relative to the silicone compound having an alkylene oxide structure is small, so the silicone reaction rate is low, and the unreacted Since many silicone compounds were produced, the contamination resistance was poor.
Moreover, the adhesive layer which is a crosslinked material of the adhesive composition of Comparative Example 2 which does not contain the antistatic agent (D) was inferior in antistatic properties.

In the preparation of the silicone-based isocyanate compound (C), the silicone compound having a reactive group and having an alkylene oxide structure and the isocyanate compound were not pre-reacted with Comparative Example 3, and the reactive group was not included. Moreover, since the silicone-based isocyanate compound (C) is not generated in the pressure-sensitive adhesive layer that is a cross-linked product of the pressure-sensitive adhesive composition of Comparative Example 4 in which the silicone compound having an alkylene oxide structure and the isocyanate compound are pre-reacted. The stain resistance was poor.
Since the antistatic agent (D) is not localized near the surface of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer that is a crosslinked product of the pressure-sensitive adhesive composition of Comparative Example 5 that does not contain the silicone isocyanate compound (C) is charged It was inferior in prevention.

  From the above, the pressure-sensitive adhesive layer that is a cross-linked product of the pressure-sensitive adhesive composition of the present invention is excellent in stain resistance and antistatic properties, and therefore can be suitably used as a protective film for optical members.

Claims (7)

(Meth) acrylic resin (A) having at least a crosslinkable functional group;
An isocyanate compound (B);
An isocyanate compound (C) having a polysiloxane structure and an alkylene oxide structure other than the isocyanate compound (B);
An antistatic agent (D),
The content of the isocyanate compound (C) is a pressure-sensitive adhesive composition for a protective film, which is 0.10 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic resin (A).   The pressure-sensitive adhesive composition for a protective film according to claim 1, wherein a mass ratio [(C) / (B)] of the isocyanate compound (C) to the isocyanate compound (B) is 1/1 to 1/20. . The pressure-sensitive adhesive composition for a protective film according to claim 1 or 2, wherein the isocyanate compound (C) includes a structure represented by the following structural formula (1).

[In Structural Formula (1), r represents an integer of 1 to 100, b represents an integer of 1 to 100, and X represents a monovalent organic group containing an isocyanate group. ] The said isocyanate compound (C) is an adhesive composition for protective films of any one of Claims 1-3 represented by the following general formula (1-1).

[In general formula (1-1), p or q each independently represents an integer of 0 to 100, r represents an integer of 1 to 100, a represents an integer of 0 to 100, and b represents 1 to 100. 100 represents an integer, and X represents a monovalent organic group containing an isocyanate group. ]   The pressure-sensitive adhesive composition for a protective film according to any one of claims 1 to 4, wherein the antistatic agent (D) is an alkali metal salt or an organic salt.   The pressure-sensitive adhesive composition for a protective film according to any one of claims 1 to 5, which is used for an optical member.   The protective film which has an adhesive layer which is a crosslinked material of the adhesive composition for protective films of any one of Claims 1-6, and a base material.