KR20230141562A - Silicone-based plasticizer and use thereof - Google Patents

Abstract

Provided is a plasticizer with excellent stability in a flexibility imparting effect (plasticizing effect). Provided is a silicone-based plasticizer made of a siloxane compound. The number of Si atoms contained in the siloxane compound is 2 or more and 5 or less. At least one of the Si atoms has two or more double bond-containing rings bonded to the Si atom.

Description

Silicone-based plasticizer and its use {SILICONE-BASED PLASTICIZER AND USE THEREOF}

The present invention relates to a silicone-based plasticizer and an adhesive containing the silicone-based plasticizer.

In general, adhesives (also called pressure-sensitive adhesives; the same applies hereinafter) are in a flexible solid (viscoelastic) state in the temperature range around room temperature and have the property of easily adhering to an adherend by applying pressure. Taking advantage of these properties, adhesives are widely used for purposes such as bonding, fixation, and protection in various industrial fields such as home appliances, automobiles, various machines, electrical devices, and electronic devices. An example of the use of the adhesive is to bond polarizing films, retardation films, cover window members, and various other light-transmitting members to other members in display devices such as liquid crystal displays and organic EL displays. . Technical literature on adhesives for optical members includes Patent Documents 1 and 2.

Japanese Patent Publication No. 2014-169382 Japanese Patent Publication No. 2017-128732

Patent Documents 1 and 2 disclose a pressure-sensitive adhesive composition containing as a main component a (meth)acrylic acid ester polymer containing a monomer having a plurality of aromatic rings as a monomer unit, and an adhesive obtained by crosslinking the pressure-sensitive adhesive composition, which contains a plurality of aromatic rings. It is proposed to obtain an adhesive with a high refractive index by using a monomer having a high refractive index. For example, among the materials to which the adhesive is attached, such as optical members, there are materials with a high refractive index. When a general acrylic adhesive is used to bond such high refractive index materials, reflection occurs at the interface due to the difference in refractive index between the two. It is known to do so. As an adhesive used for bonding the high refractive index materials, etc., the interface reflection can be prevented or suppressed by using an adhesive with a high refractive index. Additionally, the refractive index of acrylic adhesive is usually around 1.47.

However, an adhesive having appropriate flexibility may be preferably used depending on the application location or usage mode. An adhesive having appropriate flexibility means adhesion to the adherend (e.g., conformability to steps that may exist on the surface of the adherend), conformability to deformation of the adherend, and air bubbles during bonding to the adherend. This can be advantageous in terms of preventing mixing, etc. For example, polymers formed by using a relatively large amount of monomers having an aromatic ring to increase the refractive index tend to become hard, so it would be advantageous to provide a means for imparting flexibility to an adhesive containing such a polymer. Furthermore, from the viewpoint of the performance stability of the adhesive, it is desirable that the flexibility imparting effect by the above means has little variation due to storage environment or aging.

The present invention was created in consideration of the above circumstances, and one object is to provide a plasticizer with excellent stability in the flexibility imparting effect (plasticizing effect). Another related object is to provide an adhesive comprising such a plasticizer.

By this specification, a silicone-based plasticizer consisting of a siloxane compound is provided. The number of Si atoms contained in the siloxane compound is 2 or more and 5 or less. At least one of the Si atoms has two or more double bond-containing rings bonded to the Si atom. A silicone-based plasticizer (hereinafter sometimes abbreviated as “plasticizer”) made of a siloxane compound of this structure can exert a plasticizing effect based on the flexibility of the siloxane structure, and has the advantage of being easy to mix with the material to be plasticized. Compatibility and stability of the plasticizing effect can be achieved in a good balance.

In some embodiments of the technology disclosed herein (including silicone-based plasticizers, adhesive compositions containing the plasticizers, adhesives containing the plasticizers, adhesive sheets containing the adhesives, etc.; the same applies hereinafter), the siloxane compound is a trisiloxane compound. A silicone-based plasticizer made of a trisiloxane compound having at least one Si atom bonded to two or more double bond-containing rings is preferable because it is easy to achieve a good balance of ease of mixing, compatibility, good plasticizing effect, and stability.

The number of double bond-containing rings included in the siloxane compound may be, for example, 4 or more and 6 or less. A silicone-based plasticizer made of a siloxane compound with such a structure is preferable because it is easy to achieve a good balance of ease of mixing, compatibility, good plasticizing effect, and stability.

In some embodiments of the silicone-based plasticizer, the number of Si atoms to which the two or more double bond-containing rings are bonded is two or more. A silicone-based plasticizer made of a siloxane compound with such a structure is preferable because it is easy to achieve a good balance of ease of mixing, compatibility, good plasticizing effect, and stability.

In some embodiments of the silicone-based plasticizer, the molecular weight of the siloxane compound is 450 or more and 750 or less. A silicone-based plasticizer with a molecular weight in the above range is preferable because it is easy to achieve a good balance between ease of mixing, compatibility, good plasticizing effect, and stability.

The silicone-based plasticizer in some embodiments is liquid at 25°C. Such silicone-based plasticizers are preferable from the viewpoint of handling, ease of mixing, compatibility, etc., and are also advantageous from the viewpoint of the effect of providing flexibility in a temperature range around room temperature (for example, about 23°C).

The silicone-based plasticizer disclosed herein is suitable as a plasticizer for adhesives, for example. Accordingly, this specification provides an adhesive containing any of the silicone-based plasticizers disclosed herein.

The adhesive according to some embodiments contains as a base polymer a polymer containing a repeating unit having a double bond-containing ring. In an adhesive containing a base polymer of such a structure, the plasticizing effect of the silicone-based plasticizer disclosed herein can be suitably exhibited.

The adhesive in some embodiments includes an acrylic polymer as a base polymer. An adhesive containing an acrylic polymer as a base polymer (acrylic adhesive) is preferable from the viewpoint of ease of adjusting adhesive properties and optical properties. The technology disclosed herein can be preferably implemented in the form where the acrylic polymer includes a repeating unit having a double bond-containing ring.

In addition, appropriate combinations of the elements described in this specification may also be included in the scope of inventions requiring patent protection through this patent application.

1 is a cross-sectional view schematically showing the structure of an adhesive sheet according to one embodiment.
Fig. 2 is a cross-sectional view schematically showing the structure of an adhesive sheet according to another embodiment.
Figure 3 is a cross-sectional view schematically showing the structure of an adhesive sheet according to another embodiment.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in this specification and matters necessary for practicing the present invention can be understood by those skilled in the art based on the teachings for implementing the invention described in this specification and the technical common sense at the time of filing the application. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field.

In addition, in the drawings below, members and parts that exert the same function may be described with the same reference numerals, and overlapping descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are modeled to clearly explain the present invention, and do not necessarily accurately represent the size or scale of the actually provided product.

<Silicone-based plasticizer>

The silicone-based plasticizer disclosed by this specification consists of a siloxane compound having a Si atom number of 2 to 5, and at least one of the Si atoms is characterized by having two or more double bond-containing rings bonded to the Si atom. . A silicone-based plasticizer made of a siloxane compound having such a structure can exhibit a plasticizing effect based on the flexibility of the siloxane structure, and has a Si atom number of 2 to 5 and two or more double bond-containing rings bonded to each other. By having at least one, it is possible to achieve a good balance between ease of mixing and compatibility with the material to be plasticized and stability of the plasticizing effect (for example, a low rate of increase in elastic modulus with respect to storage under moist heat). In addition, the silicone-based plasticizer disclosed herein is easy to obtain high adhesive strength when used in the form of being incorporated into the adhesive, so the flexibility and adhesive strength of the adhesive can be improved in a good balance. From the viewpoint of chemical stability, the siloxane compound preferably does not have a hydrogen atom bonded to a Si atom. That is, siloxane compounds that do not have Si-H bonds are preferred.

When the number of Si atoms of the siloxane compound is 3 or more, the siloxane compound may be linear or cyclic, but is preferably a linear siloxane compound from the viewpoint of suppressing volatilization. The linear siloxane compound having 3 or more Si atoms may be linear or branched, but is preferably linear from the viewpoint of obtaining a higher plasticization effect. Hereinafter, unless otherwise specified, a siloxane compound having 3 or more Si atoms means a chain-shaped (typically linear) siloxane compound having 3 or more Si atoms.

Each double bond-containing ring of the siloxane compound may each independently be a conjugated double bond-containing ring (typically an aromatic ring) or a non-conjugated double bond-containing ring. The plasticizer may have at least one ring selected from aromatic rings and heterocycles (heterocycles) as a double bond-containing ring. In addition, the heterocycle may have a structure contained in an aromatic ring, or may have a double bond-containing heterocycle structure different from the aromatic ring. Each double bond-containing ring (typically an aromatic ring) may be a carbon ring such as a benzene ring or naphthalene ring, or may be a heterocycle such as a pyridine ring, imidazole ring, triazole ring, oxazole ring, thiazole ring, or thiophene ring. do. In the above heterocycle, the heteroatoms included as ring constituent atoms may be, for example, one or two or more selected from the group consisting of nitrogen, sulfur, and oxygen. In some embodiments, the heteroatom constituting the heterocycle may be one or both of nitrogen and sulfur.

The double bond-containing ring (typically an aromatic ring, preferably a carbocyclic ring) may have one or two or more substituents on the ring constituent atoms, and may not have a substituent. When having a substituent, examples of the substituent include an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkyloxy group, and a glycidyloxy group. It is not limited to. In a substituent containing a carbon atom, the number of carbon atoms included in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be, for example, 1 or 2. In some embodiments, each double bond-containing ring of the siloxane compound is each independently a group consisting of an aromatic ring having no substituent on the ring constituent atom, and an alkyl group, an alkoxy group, a hydroxy group, and a hydroxyalkyl group (preferably Specifically, it is selected from the group consisting of an aromatic ring having one or two or more substituents selected from the group consisting of an alkyl group and an alkoxy group. For example, each double bond-containing ring of the siloxane compound is independently selected from aromatic rings (preferably carbocyclic rings) having no substituents on ring constituent atoms. In some preferred embodiments, each double bond-containing ring of the siloxane compound is a benzene ring.

The number of Si atoms in the siloxane compound is preferably 3 or more from the viewpoint of ease of exerting the plasticizing effect and its stability (for example, suppression of an increase in elastic modulus due to volatilization of the plasticizer from the material mixed with the plasticizer). do. In addition, the number of Si atoms in the siloxane compound is determined from the viewpoint of compatibility in materials to which the plasticizer is mixed (e.g., adhesives. Specifically, adhesives such as acrylic, rubber, urethane, polyester, and silicone). , it is preferable that it is 4 or less, and it is more preferable that it is 3 or less. Among them, a silicone-based plasticizer in which the Si atom number of the siloxane compound is 3, that is, a silicone-based plasticizer made of a trisiloxane compound, is preferable.

The number of double bond-containing rings (for example, benzene rings with or without substituents) of the siloxane compound is at least 2, and the heat resistance of the plasticizing effect (for example, the rate of increase in elastic modulus with respect to storage under moist heat) From the viewpoint of this low, it is preferable that it is 3 or more, it is more preferable that it is 4 or more, and it may be 5 or more. In addition, the number of double bond-containing rings in the siloxane compound is typically 2n+2 or less, with n being the number of Si atoms in the siloxane compound, and from the viewpoint of enhancing the plasticization effect, it is suitably 2n+1 or less, It is preferably 2n or less, may be 2n-1 or less, and may be 2n-2 or less. For example, in an embodiment where the siloxane compound is a trisiloxane compound, the number of double bond-containing rings that the trisiloxane compound has is typically 8 or less, for example, may be 2 or more and 7 or less, or 3 or more and 7 or less. It may be 4 or more and 7 or less. Among them, trisiloxane compounds in which the number of double bond-containing rings (for example, unsubstituted benzene rings) are 4 or more and 6 or less (for example, 4 or 5) are preferable.

At least one of the Si atoms (typically Si atoms constituting the siloxane chain) contained in the siloxane compound is a Si atom to which two or more double bond-containing rings are bonded. From the viewpoint of improving the stability of the plasticizing effect, the number of Si atoms to which two or more double bond-containing rings are bonded in the siloxane compound may be two or more. In the siloxane compound having 3 or more Si atoms, the number of Si atoms to which two or more double bond-containing rings are bonded may be 2 or more, or 3 or more. Additionally, with the number of Si atoms in the siloxane compound being n, n It may be less than, n-1 or less, or n-2 or less. In some embodiments, from the viewpoint of enhancing the plasticizing effect, at least one of the Si atoms contained in the siloxane compound (preferably a siloxane compound having 3 or more Si atoms) contains a double bond bonded to the Si atom. The number of rings is 1 or 0. For example, it is a linear siloxane compound having 3 to 5 Si atoms, the Si atoms at both terminals each independently have two or three (preferably two) double bond-containing rings, and other than both terminals A siloxane compound having a structure in which each Si atom independently has one double bond-containing ring or does not have a double bond-containing ring is preferred.

The siloxane compound may contain a Si atom to which a group other than the double bond-containing ring is bonded. Groups other than the double bond-containing ring include an alkyl group, aralkyl group, alkoxy group, halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), fluoroalkyl group, hydroxyl group, hydroxyalkyl group, hydroxyalkyloxy group, epoxy group, Examples include, but are not limited to, glycidyloxy group, amino group, monoalkylamino group, dialkylamino group, carboxyl group, carboxyalkyl group, and mercapto group. In the substituent containing a carbon atom, the number of carbon atoms included in the substituent is, for example, 1 to 8, preferably 1 to 4, more preferably 1 to 3, for example 1 or It could be 2. Groups other than the double bond-containing ring bonded to each Si atom included in the siloxane compound may each independently be selected from the group consisting of the groups exemplified above.

In some embodiments, it is preferable that the siloxane compound does not have an ethylenically unsaturated group (including those where the double bond in the double bond-containing ring is an ethylenic double bond). A silicone-based plasticizer made of a siloxane compound without an ethylenically unsaturated group is advantageous from the viewpoint of stability of the plasticizing effect by the plasticizer, and also has an adhesive containing the silicone-based plasticizer and the adhesive (for example, an adhesive layer). It is also desirable from the viewpoint of storage stability of the adhesive sheet, and from the viewpoint of suppressing changes in elastic modulus, dimensional changes and deformations (bending, waviness, etc.), and occurrence of optical distortion due to the reaction of ethylenically unsaturated groups.

In some embodiments of the silicone-based plasticizer disclosed herein, at least one of the Si atoms contained in the siloxane compound (at least two in the case of a siloxane compound having a Si atom number of 3 or more) is Si It is preferred to have at least one methyl group on the atom. For example, it is preferable that the Si atoms located at both ends of the siloxane chain each independently have one or two (more preferably one) methyl groups. In some preferred embodiments, each of the Si atoms contained in the siloxane compound independently has one or two methyl groups. According to a silicone-based plasticizer made of a siloxane compound with such a structure, the plasticization effect due to the flexibility of the siloxane structure and the stability of the plasticization effect due to having a structure in which two or more double bond-containing rings are bonded to at least one Si atom are achieved. It can be achieved in a good balance.

In the silicone-based plasticizer disclosed herein, the number of Si atoms contained in the siloxane compound is set to n, and the sum of the number of substituents bonded to those Si atoms (hereinafter also referred to as the total number of substituents) is typically: is 2n+2, at least two of which are double bond-containing rings. In the silicone-based plasticizer disclosed herein, the ratio S _R of the number of substituents containing a double bond-containing ring (preferably an aromatic carbocycle, such as a benzene ring) to the total number of substituents is at least 16%, and 20%. It may be more than 25%. As the ratio S _R increases, the heat resistance of the silicone-based plasticizer and the stability of the plasticizing effect by the silicone-based plasticizer tend to generally improve. In some embodiments, the ratio S _R is advantageously 33% or more, preferably 40% or more, more preferably 50% or more (for example, 60% or more), and may be 65% or more, It may be 75% or more. The ratio S _R may be 100%, but from the viewpoint of ease of mixing and compatibility, it is advantageous to be 85% or less, preferably 80% or less, may be 75% or less, may be 65% or less, and may be 60% or less (e.g. For example, 50% or less) may be sufficient.

The siloxane compound is preferably a liquid compound at at least 30°C. In addition, in this specification, “liquid phase” means showing fluidity, and refers to a liquid state as a state of a substance. These compounds include compounds with a melting point of 30°C or lower. By being in a liquid state at 30°C, the plasticizer exhibits an appropriate plasticizing effect and can effectively reduce the elastic modulus of the adhesive. The plasticizer is preferably a liquid compound at 25°C, and more preferably a liquid compound at 23°C (for example, 20°C).

In the silicone-based plasticizer disclosed herein, the molecular weight of the siloxane compound is suitably 400 or more, advantageously 430 or more, preferably 460 or more, may be 490 or more, and may be 520 or more from the viewpoint of stability of the plasticizing effect. You can continue. In addition, the molecular weight of the siloxane compound is suitably 900 or less, advantageously 850 or less, preferably 700 or less, more preferably 650 or less, and more preferably 600 or less from the viewpoint of plasticization effect, ease of mixing, compatibility, etc. It may be 560 or less, 540 or less, or 500 or less.

As the molecular weight of the siloxane compound, a molecular weight calculated based on the chemical structure or a value measured using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) can be used. If a nominal value of molecular weight is provided by a manufacturer, etc., that nominal value can be adopted.

The refractive index of the silicone-based plasticizer disclosed herein is not particularly limited and may be, for example, in the range of 1.300 to 1.800. From the viewpoint of suppressing a decrease in the refractive index of the material to which the plasticizer is mixed (e.g., an adhesive) while achieving low elasticity, the silicone-based plasticizer in some embodiments has a refractive index of 1.440 or more (e.g., 1.450 or more). It is suitable, and is preferably 1.500 or more, more preferably 1.520 or more (e.g., 1.530 or more or 1.540 or more), and even more preferably 1.550 or more (e.g., 1.560 or more or 1.570 or more). In addition, the refractive index of the silicone-based plasticizer may be, for example, 1.700 or less, 1.650 or less, or 1.600 or less from the viewpoint of ease of mixing and compatibility.

In addition, the refractive index of the silicone plasticizer is measured using an Abbe refractometer under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. As an Abbe refractometer, model “DR-M4” manufactured by ATAGO or its equivalent can be used. If the nominal value of the refractive index at 25°C is provided by the manufacturer, etc., the nominal value can be adopted.

The kinematic viscosity at 25°C of the silicone-based plasticizer disclosed herein may be, for example, less than 3000 mm2/s, advantageously less than 2000 mm2/s, and less than 1000 mm2/s (for example, less than 700 mm2/s). It is preferable, it is more preferable that it is less than 500 mm2/s, it may be less than 400 mm2/s, it may be less than 350 mm2/s, it may be less than 300 mm2/s, it may be less than 250 mm2/s, and it may be less than 200 mm2/s. It may be less than 150 mm2/s, less than 100 mm2/s, or less than 50 mm2/s. Using a silicone-based plasticizer with a lower kinematic viscosity, it is easy to obtain a higher plasticizing effect and better low-temperature characteristics. In addition, the kinematic viscosity of the silicone plasticizer at 25°C may be, for example, 1.0 mm2/s or more or 3.0 mm2/s or more, preferably 5.0 mm2/s or more, more preferably 10 mm2/s or more, and 15 mm2 or more. It may be more than /s, it may be more than 25㎟/s, it may be more than 35㎟/s, it may be more than 40㎟/s, it may be more than 60㎟/s, it may be more than 90㎟/s, or it may be more than 120㎟/s. It can be more than that. Having the kinematic viscosity of the silicone-based plasticizer above a predetermined level can be advantageous from the viewpoint of suppressing volatilization of the silicone-based plasticizer and improving the stability of the plasticizing effect. The kinematic viscosity of the silicone plasticizer can be measured by a conventional method. If a nominal value of kinematic viscosity is provided by the manufacturer, etc., the nominal value can be adopted.

<Adhesive>

The adhesive disclosed herein is characterized by containing a silicone-based plasticizer as described above. The type of the adhesive is not particularly limited and includes, for example, acrylic polymer, rubber polymer (e.g. natural rubber, synthetic rubber, mixtures thereof, etc.), polyester polymer, urethane polymer, polyether polymer, silicone polymer. , may contain one or two or more types of various rubber-like polymers such as polyamide-based polymers and fluorine-based polymers as the base polymer. From the viewpoint of adhesive performance, cost, etc., an adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be preferably used. Among them, an adhesive containing an acrylic polymer as a base polymer (acrylic adhesive) is preferable.

In addition, in this specification, the “base polymer” of the adhesive refers to the main component of the rubber-like polymer contained in the adhesive. The rubber-like polymer refers to a polymer that exhibits rubbery elasticity in a temperature range around room temperature (for example, 25°C). The base polymer is typically a structural polymer that forms the adhesive. In addition, in this specification, the “main component” refers to a component contained in excess of 50% by weight, unless otherwise specified.

In addition, in this specification, “acrylic polymer” refers to a polymer containing a monomer unit derived from a monomer having at least one (meth)acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as an “acrylic monomer.” Therefore, the acrylic polymer in this specification is defined as a polymer containing a monomer unit derived from an acrylic monomer. A typical example of an acrylic polymer includes an acrylic polymer in which more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of the monomer components constituting the polymer is an acrylic monomer.

In addition, in this specification, “acrylic monomer” refers to a monomer having at least one (meth)acryloyl group in one molecule. Here, “(meth)acryloyl group” refers comprehensively to acryloyl group and methacryloyl group. Therefore, the concept of acrylic monomer as used herein may include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer). Similarly, in this specification, “(meth)acrylic acid” refers comprehensively to acrylic acid and methacrylic acid, and “(meth)acrylate” refers to acrylate and methacrylate, respectively. The same goes for other similar terms.

In addition, in this specification, the term “monomer component constituting the polymer” refers to the component, regardless of whether it is included in the adhesive composition in the form of a pre-formed polymer (which may be an oligomer) or in the form of an unpolymerized monomer. In the adhesive formed from the adhesive composition, it refers to the monomer that constitutes the repeating unit of the polymer. That is, the monomer component constituting a predetermined polymer (for example, a base polymer, preferably an acrylic polymer) contained in the adhesive may be contained in the adhesive composition in any form of a polymerized product, unpolymerized product, or partially polymerized product. From the viewpoint of ease of preparation of the adhesive composition, etc., in some embodiments, the adhesive composition contains substantially all of the monomer components (for example, 95% by weight or more, preferably 99% by weight or more) in the form of a polymer. desirable.

Hereinafter, the mode in which the adhesive is an acrylic adhesive will be mainly described, but the adhesive in the technology disclosed herein is not intended to be limited to the acrylic adhesive.

(Acrylic polymer)

In some embodiments of the acrylic adhesive containing a silicone plasticizer disclosed herein, the acrylic polymer that is the base polymer of the acrylic adhesive is preferably an acrylic polymer containing an aromatic ring-containing monomer (A1) as a monomer unit. That is, it is preferable to include an aromatic ring-containing monomer (A1) as a monomer component constituting the acrylic polymer. The silicone-based plasticizer disclosed herein can be used in an adhesive containing such an acrylic polymer as a base polymer, and can effectively and stably exert the effect of making the adhesive more flexible (plasticizing).

(Monomer (A1))

As the monomer (A1), a compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule is used. As the monomer (A1), one type of such compound can be used individually or in combination of two or more types.

Examples of the ethylenically unsaturated group include (meth)acryloyl group, vinyl group, and (meth)allyl group. A (meth)acryloyl group is preferable from the viewpoint of polymerization reactivity, and an acryloyl group is more preferable from the viewpoint of flexibility and adhesiveness. From the viewpoint of suppressing a decrease in the flexibility of the adhesive, a compound (i.e., a monofunctional monomer) in which the number of ethylenically unsaturated groups contained in one molecule is 1 is preferably used as the monomer (A1).

The number of aromatic rings contained in one molecule of the compound used as the monomer (A1) may be 1 or 2 or more. The upper limit of the number of aromatic rings is not particularly limited, and may be, for example, 16 or less. In some embodiments, from the viewpoint of ease of preparation of the acrylic polymer, transparency of the adhesive, etc., the number of aromatic rings may be, for example, 12 or less, preferably 8 or less, more preferably 6 or less, and 5 or less. It may be 2 or less, it may be 4 or less, it may be 3 or less, and it may be 2 or less.

The aromatic ring possessed by the compound used as the monomer (A1) includes a benzene ring (may be a benzene ring constituting a part of a biphenyl structure or a fluorene structure); Condensed rings of naphthalene ring, indene ring, azulene ring, anthracene ring, and phenanthrene ring; It may be a carbon ring such as pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, isoxazole ring, thiazole ring, thiophene ring. ; It may be a heterocycle (heterocycle) such as: In the above heterocycle, the heteroatoms included as ring constituent atoms may be, for example, one or two or more selected from the group consisting of nitrogen, sulfur, and oxygen. In some embodiments, the heteroatom constituting the heterocycle may be one or both of nitrogen and sulfur. The monomer (A1) may have a structure in which 1 or 2 or more carbocyclic rings and 1 or 2 or more heterocycles are condensed, such as a dinaphthothiophene structure.

The aromatic ring (preferably a carbocyclic ring) may have one or two or more substituents on the ring constituent atoms, and does not need to have any substituent. When having a substituent, the substituent includes an alkyl group, alkoxy group, aryloxy group, hydroxyl group, halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), hydroxyalkyl group, hydroxyalkyloxy group, glycidyloxy group, etc. Illustrative, but not limited to these. In a substituent containing a carbon atom, the number of carbon atoms included in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be, for example, 1 or 2. In some embodiments, the aromatic ring is an aromatic ring that has no substituents on ring constituent atoms or has one or two or more substituents selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom (for example, a bromine atom). You can. In addition, that the aromatic ring of the monomer (A1) has a substituent on its ring constituent atoms means that the aromatic ring has a substituent other than the substituent having an ethylenically unsaturated group.

The aromatic ring and the ethylenically unsaturated group may be directly bonded or may be bonded through a linking group. The linking group is, for example, an alkylene group, an oxyalkylene group, a poly(oxyalkylene) group, a phenyl group, an alkylphenyl group, an alkoxyphenyl group, and a group in which one or two or more hydrogen atoms in these groups are substituted with hydroxyl groups (e.g. , hydroxyalkylene group), oxy group (-O- group), thioxy group (-S- group), etc. may be a group containing one or two or more structures selected from the group. In some embodiments, an aromatic ring is contained in a structure in which an aromatic ring and an ethylenically unsaturated group are bonded directly or bonded through a linking group selected from the group consisting of an alkylene group, an oxyalkylene group, and a poly(oxyalkylene) group. A monomer can be preferably employed. The number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, and may be, for example, 1 or 2. The repeating number of the oxyalkylene unit in the poly(oxyalkylene) group may be, for example, 2 to 3.

Examples of compounds that can be preferably employed as the monomer (A1) include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds. The aromatic ring-containing (meth)acrylate and aromatic ring-containing vinyl compound can be used individually or in combination of two or more types. You may use a combination of 1 type or 2 or more types of aromatic ring-containing (meth)acrylates and 1 type or 2 or more types of aromatic ring-containing vinyl compounds.

In some preferred embodiments, a monomer having two or more aromatic rings (preferably carbocyclic rings) in one molecule is used as the monomer (A1). By using a monomer having two or more aromatic rings in one molecule (monomer containing multiple aromatic rings), it is easy to obtain a high refractive index effect with respect to the optical properties of the adhesive. On the other hand, when a monomer containing multiple aromatic rings is used as the monomer component constituting the base polymer of the adhesive, the elastic modulus of the adhesive tends to increase. By containing the silicone-based plasticizer disclosed herein in an adhesive containing an acrylic polymer containing a plurality of aromatic ring-containing monomers as a monomer component as a base polymer, an adhesive that achieves both high refractive index and flexibility (low elastic modulus) in a good balance can be realized. .

Examples of monomers containing multiple aromatic rings include monomers having a structure in which two or more non-fused aromatic rings are bonded through a linking group, monomers having a structure in which two or more non-fused aromatic rings are chemically bonded directly (i.e., without going through other atoms), and condensed aromatic ring structures. A monomer having a monomer having a fluorene structure, a monomer having a dinaphthothiophene structure, a monomer having a dibenzothiophene structure, etc. can be mentioned. Among them, a monomer having a structure in which two or more non-fused aromatic rings are bonded through a linking group (for example, phenoxybenzyl (meth)acrylate described later) is preferably used. The monomer containing multiple aromatic rings can be used individually or in combination of two or more types.

The linking group is, for example, an oxy group (-O-), a thiooxy group (-S-), an oxyalkylene group (for example -O-(CH ₂ ) _n -group, where n is 1 to 3, Preferably 1), a thiooxyalkylene group (e.g. -S-(CH ₂ ) _n -group, where n is 1 to 3, preferably 1), a straight chain alkylene group (e.g. -(CH ₂ ) _n -group, where n is 1 to 6, preferably 1 to 3), the alkylene group in the oxyalkylene group, the thiooxyalkylene group and the straight chain alkylene group may be a partially halogenated or fully halogenated group, etc. . From the viewpoint of flexibility of the adhesive, etc., suitable examples of the linking group include an oxy group, a thioxy group, an oxyalkylene group, and a straight chain alkylene group. Specific examples of monomers having a structure in which two or more non-fused aromatic rings are bonded through a linking group include phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), thiophenoxybenzyl ( Meth)acrylate, benzylbenzyl (meth)acrylate, etc. are mentioned.

The monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded may be, for example, biphenyl structure-containing (meth)acrylate, triphenyl structure-containing (meth)acrylate, vinyl group-containing biphenyl, etc. Specific examples include o-phenylphenol (meth)acrylate and biphenylmethyl (meth)acrylate.

Examples of the monomer having the condensed aromatic ring structure include (meth)acrylate containing a naphthalene ring, (meth)acrylate containing an anthracene ring, naphthalene containing a vinyl group, and anthracene containing a vinyl group. Specific examples include 1-naphthylmethyl (meth)acrylate (alias: 1-naphthalenemethyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2- Naphthoxyethyl acrylate, 2-(4-methoxy-1-naphthoxy)ethyl (meth)acrylate, etc. are mentioned.

Specific examples of monomers having the above fluorene structure include 9,9-bis(4-hydroxyphenyl)fluorene(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluor Orene (meth)acrylate, etc. can be mentioned. In addition, since the monomer having a fluorene structure includes a structural portion in which two benzene rings are directly chemically bonded, it is included in the concept of a monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded.

Examples of monomers having the dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, and (meth)allyl group-containing dinaphthothiophene. As a specific example, (meth)acryloyloxymethyldinaphthothiophene (for example, a compound having a structure in which CH ₂ CH(R ¹ )C(O)OCH ₂ - is bonded to the 5th or 6th position of the dinaphthothiophene ring Here, R ¹ is a hydrogen atom or a methyl group), (meth)acryloyloxyethyldinaphthothiophene (for example, at the 5th or 6th position of the dinaphthothiophene ring, CH ₂ CH(R ¹ )C (O)OCH(CH ₃ )- or CH ₂ CH(R ¹ )C(O)OCH ₂ CH ₂ - A compound having a structure where R ¹ is a hydrogen atom or a methyl group), vinyldinaphthothiophene ( For example, compounds having a structure in which a vinyl group is bonded to the 5th or 6th position of the naphthothiophene ring), (meth)allyloxydinaphthothiophene, etc. In addition, the monomer having a dinaphthothiophene structure is included in the concept of the monomer having the above condensed aromatic ring structure by including a naphthalene structure and having a structure in which a thiophene ring and two naphthalene structures are condensed.

Examples of the monomer having the dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene, vinyl group-containing dibenzothiophene, and the like. In addition, a monomer having a dibenzothiophene structure has a structure in which a thiophene ring and two benzene rings are condensed, and is therefore included in the concept of a monomer having the above-mentioned condensed aromatic ring structure.

In addition, neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to a structure in which two or more non-fused aromatic rings are directly chemically bonded.

In some preferred embodiments, a monomer having one aromatic ring (preferably a carbocyclic ring) per molecule is used as the monomer (A1). A monomer having one aromatic ring per molecule (monomer containing a single aromatic ring) can be helpful, for example, in improving the flexibility of the adhesive, adjusting the adhesive properties, and improving transparency. Single aromatic ring-containing monomers can be used individually or in combination of two or more types. In some embodiments, a monomer having one aromatic ring per molecule may be used in combination with a monomer containing multiple aromatic rings from the viewpoint of improving the refractive index of the adhesive.

Examples of monomers having one aromatic ring per molecule include benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, and phenoxypropyl (meth)acrylate. ) Acrylate, phenoxybutyl (meth)acrylate, cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, chlorobenzyl (meth)acrylate, etc., carbon aromatic rings containing (meth)acrylates; 2-(4,6-dibromo-2-s-butylphenoxy)ethyl(meth)acrylate, 2-(4,6-dibromo-2-isopropylphenoxy)ethyl(meth)acrylate , 6-(4,6-dibromo-2-s-butylphenoxy)hexyl(meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl(meth)acrylate bromine-substituted aromatic ring-containing (meth)acrylates such as late, 2,6-dibromo-4-nonylphenylacrylate, and 2,6-dibromo-4-dodecylphenylacrylate; Vinyl compounds containing aromatic carbon rings, such as styrene, α-methylstyrene, vinyltoluene, and tert-butylstyrene; Compounds having a vinyl substituent on the heteroaromatic ring, such as N-vinylpyridine, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, and N-vinyloxazole; etc. can be mentioned.

As the monomer (A1), a monomer having a structure in which an oxyethylene chain is interposed between the ethylenically unsaturated group and the aromatic ring in the various aromatic ring-containing monomers described above may be used. In this way, the monomer in which the oxyethylene chain is sandwiched between the ethylenically unsaturated group and the aromatic ring can be understood as an ethoxylated product of the original monomer. The repeating number of the oxyethylene unit (-CH ₂ CH ₂ O-) in the oxyethylene chain is typically 1 to 4, preferably 1 to 3, more preferably 1 to 2, for example It is 1. Specific examples of ethoxylated aromatic ring-containing monomers include ethoxylated o-phenylphenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, ethoxylated cresol (meth)acrylate, and phenoxyethyl (meth)acrylate. , phenoxydiethylene glycol (meth)acrylate, phenoxydiethylene glycol di(meth)acrylate, etc.

The content of the monomer containing multiple aromatic rings in the monomer (A1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In some embodiments, the content of the monomer containing multiple aromatic rings in the monomer (A1) may be, for example, 50% by weight or more, and is preferably 70% by weight or more from the viewpoint of making it easier to obtain a higher refractive index, It may be 85% by weight or more, 90% by weight or more, or 95% by weight or more. Substantially 100% by weight of the monomer (A1) may be a monomer containing multiple aromatic rings. That is, as the monomer (A1), only one or two or more types of aromatic ring-containing monomers may be used. In addition, in some other embodiments, for example, taking into account the balance between high refractive index and flexibility (low elastic modulus), the content of the aromatic ring-containing monomer in the monomer (A1) may be less than 100% by weight, It may be 98% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 65% by weight or less, 50% by weight or less, 25% by weight or less, and 10% by weight or less. It may be less than % by weight. The technology disclosed here can also be implemented in an embodiment in which the content of the monomer containing multiple aromatic rings in the monomer (A1) is less than 5% by weight. It is not necessary to use a monomer containing multiple aromatic rings.

The content of the monomer containing multiple aromatic rings in the monomer component constituting the acrylic polymer is not particularly limited and can be set so as to realize an adhesive that achieves both the desired refractive index and flexibility. The content of the monomer containing multiple aromatic rings in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In some embodiments, from the viewpoint of making it easier to realize an adhesive having a higher refractive index, the content of the aromatic ring-containing monomer in the monomer component may be, for example, more than 35% by weight, or more than 50% by weight. It is advantageous, it is preferable that it is more than 70% by weight, it may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, 91% by weight or more, 92% by weight or more, 93% by weight or more, It may be 94% by weight or more, 95% by weight or more, 96% by weight or more, 97% by weight or more, 98% by weight or more, or 99% by weight or more. Considering the balance between high refractive index and flexibility, the content of the aromatic ring-containing monomer in the monomer component is advantageous to be approximately 99% by weight or less, and may be 98% by weight or less, or 96% by weight or less, It may be 93 weight% or less, 90 weight% or less, 85 weight% or less, 80 weight% or less, and 75 weight% or less. In several other embodiments, from the viewpoint of making it easier to realize higher adhesive properties and/or optical properties (for example, transparency), the content of the aromatic ring-containing monomer in the monomer component is 70% by weight or less. It may be 60% by weight or less, 50% by weight or less, 40% by weight or less, 25% by weight or less, 15% by weight or less, and 5% by weight or less. The technology disclosed here can also be implemented in an embodiment in which the content of the monomer containing multiple aromatic rings in the monomer component is less than 3% by weight.

The content of the monomer containing a single aromatic ring in the monomer (A1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In some embodiments, the content of the monomer containing a single aromatic ring in the monomer (A1) may be, for example, 50% by weight or more, and is preferably 70% by weight or more from the viewpoint of making it easier to obtain a higher refractive index, It may be 85% by weight or more, 90% by weight or more, or 95% by weight or more. Substantially 100% by weight of the monomer (A1) may be a monomer containing a single aromatic ring. That is, as the monomer (A1), only one or two or more types of monomers containing single aromatic rings may be used. In addition, in some embodiments, for example, considering the balance between high refractive index and flexibility, the content of the aromatic ring single-containing monomer in monomer (A1) may be less than 100% by weight, and may be 98% by weight or less. It may be 90% by weight or less, 80% by weight or less, 70% by weight or less, 65% by weight or less, 50% by weight or less, 25% by weight or less, and 10% by weight or less. . The technology disclosed here can also be carried out in an embodiment in which the content of the monomer containing a single aromatic ring in the monomer (A1) is less than 5% by weight. It is not necessary to use a monomer containing a single aromatic ring.

The content of the monomer containing a single aromatic ring in the monomer component constituting the acrylic polymer is not particularly limited and can be set so as to achieve an adhesive that achieves both the desired refractive index and flexibility. The content of the aromatic ring single-containing monomer in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In some embodiments, from the viewpoint of making it easier to realize an adhesive having a higher refractive index, the content of the monomer containing a single aromatic ring in the monomer component may be, for example, more than 35% by weight, or more than 50% by weight. It is advantageous, preferably 60% by weight or more, more preferably more than 70% by weight, may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, and may be 95% by weight or more. , may be 98% by weight or more. The content of the aromatic ring single-containing monomer in the monomer component may be approximately 99% by weight or less, preferably 98% by weight or less, and 96% by weight or less, considering the balance between high refractive index and flexibility. More preferably, it may be 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, and 75% by weight or less. In some embodiments, from the viewpoint of making it easier to realize higher adhesive properties and/or optical properties (e.g. transparency), the content of the aromatic ring single-containing monomer in the monomer component may be 70% by weight or less. It may be 60% by weight or less, 50% by weight or less, 40% by weight or less, 25% by weight or less, 15% by weight or less, and 5% by weight or less. The technique disclosed herein can also be carried out in an embodiment in which the content of the monomer containing a single aromatic ring in the monomer component is less than 3% by weight.

In some preferred embodiments, a high refractive index monomer can be preferably employed as at least part of the monomer (A1). Here, “high refractive index monomer” refers to a monomer whose refractive index is, for example, approximately 1.510 or higher, preferably approximately 1.530 or higher, and more preferably approximately 1.550 or higher. The upper limit of the refractive index of the high refractive index monomer is not particularly limited, but from the viewpoint of ease of preparation of acrylic polymer and compatibility with flexibility suitable as an adhesive, it may be, for example, 3.000 or less, 2.500 or less, or 2.000 or less. It may be less than 1.900, less than 1.800, or less than 1.700. High refractive index monomers can be used individually or in combination of two or more types.

In addition, the refractive index of the monomer is measured using an Abbe refractometer under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. As an Abbe refractometer, model “DR-M4” manufactured by ATAGO or its equivalent can be used. If the nominal value of the refractive index at 25°C is provided by the manufacturer, etc., the nominal value can be adopted.

As the high refractive index monomer, those having the corresponding refractive index can be appropriately adopted from among the compounds included in the concept of the aromatic ring-containing monomer (A1) disclosed herein (for example, the compounds and compound groups exemplified above). there is. Specific examples include m-phenoxybenzyl acrylate (refractive index: 1.566, Tg of homopolymer: -35°C), 1-naphthylmethyl acrylate (refractive index: 1.595, Tg of homopolymer: 31°C), ethoxylated o- Phenylphenol acrylate (number of repetitions of oxyethylene units: 1, refractive index: 1.578), benzyl acrylate (refractive index (nD20): 1.519, Tg of homopolymer: 6°C), phenoxyethyl acrylate (refractive index (nD20): 1.517, Tg of homopolymer: 2℃), phenoxydiethylene glycol acrylate (refractive index: 1.510, Tg of homopolymer: -35℃), 6-acryloyloxymethyldinaphthothiophene (6MDNTA, refractive index: 1.75) , 6-methacryloyloxymethyldinaphthothiophene (6MDNTMA, refractive index: 1.726), 5-acryloyloxyethyldinaphthothiophene (5EDNTA, refractive index: 1.786), 6-acryloyloxyethyldinaphthothiophene Examples include, but are not limited to, ophene (6EDNTA, refractive index: 1.722), 6-vinyldinaphthothiophene (6VDNT, refractive index: 1.802), and 5-vinyldinaphthothiophene (abbreviation: 5VDNT, refractive index: 1.793). does not

The content of the high refractive index monomer (i.e., an aromatic ring-containing monomer with a refractive index of approximately 1.510 or more, preferably approximately 1.530 or more, more preferably approximately 1.550 or more) in the monomer (A1) is not particularly limited, and is, for example, For example, it may be 5% by weight or more, 25% by weight or more, 35% by weight or more, and 40% by weight or more. In some embodiments, from the viewpoint of making it easier to obtain a higher refractive index, the content of the high refractive index monomer in the monomer (A1) may be, for example, 50% by weight or more, and is preferably 70% by weight or more, 85 It may be % by weight or more, may be 90 % by weight or more, and may be 95 % by weight or more. Substantially 100% by weight of the monomer (A1) may be a high refractive index monomer. In addition, in some embodiments, for example, from the viewpoint of achieving both high refractive index and flexibility in a good balance, the content of the high refractive index monomer in monomer (A1) may be less than 100% by weight, and may be 98% by weight or less. It may be 90% by weight or less, 80% by weight or less, or 65% by weight or less. In several other embodiments, taking adhesion properties and/or optical properties into consideration, the content of the high refractive index monomer in monomer (A1) may be 50% by weight or less, 25% by weight or less, or 15% by weight. It may be less than or equal to 10% by weight. The technology disclosed here can also be carried out in an embodiment where the content of the high refractive index monomer in the monomer (A1) is less than 5% by weight. There is no need to use a high refractive index monomer.

The content of the high refractive index monomer in the monomer component constituting the acrylic polymer is not particularly limited and can be set to achieve an adhesive that achieves both the desired refractive index and flexibility. Additionally, if necessary, it can be set taking into account compatibility with adhesive properties (e.g., adhesive force, etc.) and/or optical properties (e.g., total light transmittance, haze value, etc.). The content of the high refractive index monomer in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In some embodiments, the content of the high refractive index monomer in the monomer component constituting the acrylic polymer may be, for example, more than 35% by weight, and from the viewpoint of making it easier to obtain a higher refractive index, it is advantageous to be more than 50% by weight. It is preferably more than 70% by weight, may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, and may be 95% by weight or more. The content of the high refractive index monomer in the monomer component is advantageously set to 99% by weight or less, preferably 98% by weight or less, and 96% by weight or less from the viewpoint of achieving both high refractive index and flexibility in a good balance. It is more preferable to do so, and may be 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, and 75% by weight or less. In several other embodiments, taking adhesion properties and/or optical properties into consideration, the content of the high refractive index monomer in the monomer component may be 70% by weight or less, 50% by weight or less, and 25% by weight or less. It may be 15% by weight or less, and may be 5% by weight or less. The technique disclosed herein can also be carried out in an embodiment in which the content of the high refractive index monomer in the monomer component is less than 3% by weight.

In some preferred embodiments, at least part of the monomer (A1) is an aromatic ring-containing monomer (hereinafter sometimes referred to as “monomer L”) having a homopolymer Tg of 10°C or lower. Increase the content of the aromatic ring-containing monomer (A1) (in particular, the aromatic ring-containing monomer (A1) corresponding to at least one of the above-mentioned multiple aromatic ring-containing monomers, single aromatic ring-containing monomers, and high refractive index monomers) in the monomer component. Since the flexibility of the bottom adhesive generally tends to decrease, the decrease in flexibility can be suppressed by employing monomer L as part or all of the monomer (A1). Thereby, the refractive index can be improved while suppressing an increase in the elastic modulus. The Tg of monomer L may be, for example, 5°C or lower, 0°C or lower, -10°C or lower, -20°C or lower, and -25°C or lower. The lower limit of Tg of monomer L is not particularly limited. Considering the balance with the refractive index improvement effect, in some embodiments, the Tg of monomer L may be, for example, -70°C or higher, -55°C or higher, or -45°C or higher. In several other embodiments, the Tg of monomer L may be, for example, -30°C or higher, -10°C or higher, 0°C or higher, or 3°C or higher. Monomer L can be used individually or in combination of two or more types.

As the monomer L, one having the corresponding Tg can be appropriately adopted from among the compounds included in the concept of the aromatic ring-containing monomer (A1) disclosed herein (for example, the compounds and compound groups exemplified above). Suitable examples of aromatic ring-containing monomers that can be used as monomer L include m-phenoxybenzyl acrylate (homopolymer Tg: -35°C), benzyl acrylate (homopolymer Tg: 6°C), and phenoxyethyl acrylate. Rate (Tg of homopolymer: 2°C) and phenoxydiethylene glycol acrylate (Tg of homopolymer: -35°C).

The content of monomer L in the monomer (A1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In some embodiments, from the viewpoint of making it easier to obtain an adhesive that achieves both a high refractive index and flexibility at a higher level, the content of monomer L in the monomer (A1) may be, for example, 50% by weight or more to improve flexibility. From the viewpoint, it is preferably 60% by weight or more, may be 70% by weight or more, may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, and may be 95% by weight or more. Substantially 100% by weight of monomer (A1) may be monomer L. In addition, in some other embodiments, for example, from the viewpoint of achieving both high refractive index and flexibility in a good balance, the content of monomer L in monomer (A1) may be less than 100% by weight, and may be 98% by weight or less. It may be 90% by weight or less, 80% by weight or less, or 65% by weight or less.

The content of monomer L in the monomer component constituting the acrylic polymer may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In some embodiments, from the viewpoint of making it easier to obtain an adhesive that achieves both high refractive index and flexibility at a higher level, the content of monomer L in the monomer component may be, for example, more than 35% by weight, from the viewpoint of improving the refractive index. It is advantageous that it is more than 50% by weight, it is preferable that it is more than 70% by weight, and it may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, and may be 95% by weight or more. The content of monomer L in the monomer component is advantageously set to approximately 99% by weight or less, preferably 98% by weight or less, and 96% by weight or less from the viewpoint of achieving both high refractive index and flexibility in a good balance. It is more preferable to do so, and may be 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, and 75% by weight or less.

In some embodiments, as the aromatic ring-containing monomer (A1), monomer L (i.e., aromatic ring-containing monomer with a homopolymer Tg of 10°C or lower) and monomer H with a Tg higher than 10°C may be used in combination. . The Tg of monomer H may be, for example, greater than 10°C, greater than 15°C, or greater than 20°C. By using monomer L and monomer H in combination, in an adhesive with a high content of aromatic ring-containing monomer (A1) in the monomer component, the adhesive has a high refractive index and flexibility suitable for adhesion to the adherend is improved. It can be compatible at a high level. The usage ratio of monomer L and monomer H can be set to appropriately produce these effects, and is not particularly limited.

In some embodiments, the aromatic ring-containing monomer (A1) can be preferably selected from compounds that do not contain a structure in which two or more non-fused aromatic rings are directly chemically bonded (for example, a biphenyl structure). For example, it is composed of a monomer component with a composition in which the content of a compound containing a structure in which two or more non-fused aromatic rings are directly chemically bonded is less than 5% by weight (more preferably less than 3% by weight, and may be 0% by weight). Acrylic polymers are preferred. In this way, limiting the amount of use of a compound containing a structure in which two or more non-fused aromatic rings are directly chemically bonded can be advantageous from the viewpoint of realizing an adhesive that achieves both high refractive index and flexibility in a better balance.

The content of monomer (A1) in the monomer component constituting the acrylic polymer is not particularly limited, and can be set so that desired properties are obtained in an adhesive containing a combination of the silicone-based plasticizer disclosed herein and the acrylic polymer. . The desired properties may be, for example, coexistence of the desired refractive index and flexibility (low elastic modulus), further optical properties (e.g., total light transmittance, haze value, etc.), and/or adhesive properties (e.g., adhesive force, etc.). In some embodiments, the content of monomer (A1) in the monomer component may be, for example, 30% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more, It may be 70% by weight or more. In some preferred embodiments, the content of monomer (A1) in the monomer component constituting the acrylic polymer may be, for example, more than 70% by weight, and is preferably 75% by weight or more, so that a higher refractive index can be easily obtained. From this point of view, it is preferable that it is 80% by weight or more, may be 85% by weight or more, may be 90% by weight or more, 91% by weight or more, 92% by weight or more, 93% by weight or more, 94% by weight or more, 95% by weight or more, It may be 96% by weight or more, 97% by weight or more, 98% by weight or more, or 99% by weight or more. The content of monomer (A1) in the monomer component is typically less than 100% by weight, and from the viewpoint of achieving both high refractive index and flexibility (low elastic modulus) in a good balance, it is advantageous to be approximately 99% by weight or less, and 98% by weight. % or less may be sufficient, 96 weight% or less may be sufficient, 93 weight% or less may be sufficient, and 90 weight% or less may be sufficient. In some embodiments, from the viewpoint of making it easier to realize higher adhesive properties and/or optical properties (e.g. transparency), the content of monomer (A1) in the monomer component may be less than 90% by weight. , may be less than 85% by weight, or may be less than 80% by weight.

(Monomer (A2))

In some preferred embodiments, the monomer component constituting the acrylic polymer may further contain a monomer (A2) in addition to the monomer (A1). The monomer (A2) is a monomer corresponding to at least one of a monomer having a hydroxyl group (hydroxyl group-containing monomer) and a monomer having a carboxyl group (carboxylic group-containing monomer). The hydroxyl group-containing monomer is a compound having at least one hydroxyl group and at least one ethylenically unsaturated group in one molecule. The carboxyl group-containing monomer is a compound containing at least one carboxyl group and at least one ethylenically unsaturated group in one molecule. The monomer (A2) can be helpful for introducing crosslinking points into the acrylic polymer or providing appropriate cohesiveness to the adhesive. Monomer (A2) can be used individually or in combination of two or more types. The monomer (A2) may contain an aromatic ring or may not contain an aromatic ring. As the monomer (A2), a monomer containing no aromatic ring is preferably used. In addition, the monomer (A2) is defined as a monomer different from the monomer (A1) described above. For example, the monomer (A1) described above may be defined as a monomer that does not have a hydroxyl group or a carboxyl group.

Examples of the ethylenically unsaturated group contained in the monomer (A2) include (meth)acryloyl group, vinyl group, and (meth)allyl group. A (meth)acryloyl group is preferable from the viewpoint of polymerization reactivity, and an acryloyl group is more preferable from the viewpoint of improved flexibility and adhesiveness. From the viewpoint of improving the flexibility of the adhesive, a compound (i.e., a monofunctional monomer) in which the number of ethylenically unsaturated groups contained in one molecule is 1 is preferably used as the monomer (A2).

In some embodiments, as the monomer (A2), a monomer having a relatively long distance between an ethylenically unsaturated group (for example, a (meth)acryloyl group) and a hydroxyl group and/or a carboxyl group can be used. As a result, in the embodiment in which the hydroxyl group and/or carboxyl group is used in the crosslinking reaction, a highly flexible crosslinked structure can be easily obtained. For example, the number of atoms (typically carbon atoms or oxygen atoms) constituting the chain (connected chain) connecting the ethylenically unsaturated group and the hydroxyl group and/or carboxyl group is 3 or more (for example, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more) as monomer (A2). You can use it. The upper limit of the number of atoms in the linking chain is, for example, 45 or less, and 20 or less (e.g., 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, It may be 10 or less, 9 or less, or 8 or less). In addition, the number of atoms forming the connecting chain connecting the ethylenically unsaturated group and the hydroxyl group and/or the carboxyl group refers to the minimum number of atoms required to reach the hydroxyl group or the carboxyl group from the ethylenically unsaturated group. For example, when the linking chain consists of a straight chain alkylene group (i.e. -(CH ₂ ) _n -group), the number of n becomes the number of atoms constituting the linking chain. Also, for example, when the linking chain is an oxyethylene group (i.e. -(C ₂ H ₄ O) _n -group), the product of 3 and n, which is the sum of the number of carbon atoms 2 and the number of oxygen atoms 1 constituting the oxyethylene group, is (3n) is the number of atoms constituting the linking chain. Although not particularly limited, such monomer (A2) includes, for example, an alkylene unit represented by -(CH ₂ ) _n - or -( C _m H _2m O) - An oxyalkylene unit (e.g., an oxyethylene unit where m is 2 in the above formula, an oxypropylene unit where m is 3 in the above formula, and oxybutyl where m is 4 in the above formula) Those having at least one ren unit) can be used. The number of the alkylene units or oxyalkylene units is not particularly limited and may be 1 or more (for example, 1 to 15, 1 to 10, 2 to 6, or 2 to 4). In addition, n in the formula representing the alkylene unit is, for example, an integer of 1 to 10, and may be 2 or more, 3 or more, 4 or more, 6 or less, or 5 or less. In the formula representing the oxyalkylene unit, m is an integer of 2 or more, for example, an integer of 2 to 4. In addition to the ethylenically unsaturated group, hydroxyl group and/or carboxyl group, alkylene unit and/or oxyalkylene unit, the monomer (A2) contains an ester bond, an ether bond, a thioether bond, an aromatic ring, an aliphatic ring, and a hetero ring ( For example, it may contain a ring containing a nitrogen atom (N), an oxygen atom (O), or a sulfur atom (S). Additionally, the alkylene unit or oxyalkylene unit may have a substituent.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 4-hydroxybutyl (meth)acrylic acid, 6-hydroxyhexyl (meth)acrylic acid, and (meth)acrylic acid. Hydroxy (meth)acrylate such as 8-hydroxyoctyl, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. alkyl; Polyalkylene glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and polybutylene glycol mono(meth)acrylate; These may be mentioned, but are not limited to these. Examples of hydroxyl group-containing monomers that can be preferably used include 4-hydroxybutyl acrylate (Tg: -40°C) and 2-hydroxyethyl acrylate (Tg: -15°C). From the viewpoint of improving flexibility in the room temperature range, 4-hydroxybutyl acrylate with a lower Tg is more preferable. In some preferred embodiments, at least 50 weight percent (e.g., greater than 50 weight percent, greater than 70 weight percent, or greater than 85 weight percent) of monomer (A2) may be 4-hydroxybutyl acrylate. Hydroxyl group-containing monomers can be used individually or in combination of two or more types.

In some embodiments of using a hydroxyl group-containing monomer as the monomer (A2), the hydroxyl group-containing monomer may be one or two or more types selected from compounds without a methacryloyl group. Suitable examples of hydroxyl group-containing monomers that do not have a methacryloyl group include the various hydroxyalkyl acrylates described above. For example, it is preferable that more than 50% by weight, more than 70% by weight, or more than 85% by weight of the hydroxyl group-containing monomer used as the monomer (A2) is hydroxyalkyl acrylate. By using hydroxyalkyl acrylate, a hydroxy group that is helpful in providing crosslinking points and providing appropriate cohesion can be introduced into the acrylic polymer, and also in the room temperature range compared to the case of using only the corresponding hydroxyalkyl methacrylate. It is easy to obtain an adhesive with good flexibility and adhesion.

Examples of carboxylic acid-containing monomers include acrylic monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate, as well as itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. It is not limited to these. Examples of carboxyl group-containing monomers that can be preferably used include acrylic acid and methacrylic acid. Additionally, in some embodiments, from the viewpoint of improving the flexibility of the adhesive, it is preferable to use, for example, a compound represented by the following formula (1) as the carboxyl group-containing monomer.

CH ₂ =CR ¹ -COO-R ² -OCO-R ³ -COOH (1)

Here, R ¹ in the formula (1) is hydrogen or a methyl group. R ² and R ³ are divalent linking groups (specifically, organic groups having 1 to 20 carbon atoms (for example, 2 to 10, preferably 2 to 5)), and may be the same or different from each other. R ² and R ³ in the above formula (1) may be, for example, a divalent aliphatic hydrocarbon group, an aromatic hydrocarbon group, or an alicyclic hydrocarbon group. For example, R ² and R ³ may be alkylene having 2 to 5 carbon atoms. Specific examples of the carboxyl group-containing monomer represented by the formula (1) include, for example, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl-phthalic acid, and 2-(meth) Acryloyloxyethyl-2-hydroxyethyl-phthalic acid, 2-(meth)acryloyloxyethyl-succinic acid, 2-(meth)acryloyloxypropylhexahydrohydrogenphthalate, 2-(meth)acrylo One oxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate, etc. can be mentioned. Carboxyl group-containing monomers can be used individually or in combination of two or more types. A hydroxyl group-containing monomer and a carboxyl group-containing monomer may be used together.

The content of monomer (A2) in the monomer component constituting the acrylic polymer is not particularly limited and can be set depending on the purpose. In some embodiments, the content of the monomer (A2) is, for example, 0.01% by weight or more, preferably 0.1% by weight or more, and preferably 0.5% by weight or more. From the viewpoint of obtaining higher usage effects, in some embodiments, the content of the monomer (A2) may be 1% by weight or more, 2% by weight or more, or 4% by weight or more. The upper limit of the content of the monomer (A2) in the monomer component is set so that the total of the content of the monomer (A1) does not exceed 100% by weight. In some embodiments, it is appropriate that the content of the monomer (A2) is, for example, 30% by weight or less or 25% by weight or less, and by increasing the content of the monomer (A1) relatively, it is easy to achieve a high refractive index. From the viewpoint of doing so, it is preferable to set it to 20% by weight or less, more preferably to 15% by weight or less, and may be less than 12% by weight, less than 10% by weight, or less than 7% by weight. In some preferred embodiments, from the viewpoint of reducing the elastic modulus of the adhesive, the content of the monomer (A2) is less than 5% by weight, more preferably less than 3% by weight, and may be 1.5% by weight or less.

(Monomer A3)

In some embodiments, the monomer component constituting the acrylic polymer may further contain an alkyl (meth)acrylate (hereinafter also referred to as “monomer (A3)”) in addition to the monomer (A1). Monomer (A3) can help reduce the elastic modulus of the adhesive. In addition, it can be helpful in improving adhesive properties such as compatibility of additives in the adhesive and adhesive strength. Monomer (A3) can be used individually or in combination of two or more types.

As the monomer (A3), an alkyl (meth)acrylate having a straight-chain or branched alkyl group of 1 to 20 carbon atoms (i.e., C _1-20 ) at the ester terminal can be preferably used. Specific examples of C _1-20 alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and (meth) _acrylate . Isobutyl acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate , 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate , dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, Examples include isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate, but are not limited to these.

In some embodiments, at least a portion of the monomer (A3) is an alkyl (meth)acrylate whose Tg of the homopolymer is -20°C or lower (more preferably -40°C or lower, for example -50°C or lower). can be preferably employed. Such low Tg alkyl (meth)acrylate can help improve the flexibility of the adhesive. In addition, it can be helpful in improving adhesive properties such as adhesion. The lower limit of Tg of the alkyl (meth)acrylate is not particularly limited, and may be, for example, -85°C or higher, -75°C or higher, -65°C or higher, or -60°C or higher. Specific examples of the low Tg alkyl (meth)acrylate include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), heptyl acrylate, octyl acrylate, and isononyl acrylate (iNA). . In several other embodiments, an alkyl (meth)acrylate whose homopolymer Tg is more than -20°C (for example, -10°C or more) can be employed as at least a part of the monomer (A3). The upper limit of Tg of the alkyl (meth)acrylate is, for example, 10°C or less, may be 5°C or less, or may be 0°C or less. Alkyl (meth)acrylates with a Tg in this range can be helpful in adjusting the flexibility of the adhesive. Although there is no particular limitation, it is preferable to use the alkyl (meth)acrylate having the above Tg in combination with the above low Tg alkyl (meth)acrylate. Specific examples of the alkyl (meth)acrylate having the above Tg include lauryl acrylate (LA).

In some embodiments of using monomer (A3), it is preferable to use C _4-8 alkyl (meth)acrylate as monomer (A3). Among them, use of C _4-8 alkyl acrylate is more preferable. C _4-8 alkyl (meth)acrylate can be used individually or in combination _of two or more types. By using C _{4 -8} alkyl (meth)acrylate, it is easy to improve the flexibility of the adhesive, and it is also easy to obtain good adhesive properties (adhesion, etc.). In the aspect of using C _4-8 alkyl (meth)acrylate as the monomer (A3), among the alkyl (meth)acrylates contained in the monomer component (i.e., in the entire monomer (A3)) C _4-8 alkyl ( The proportion of meth)acrylate is suitably 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more, further preferably 90% by weight or more, and may be substantially 100% by weight. .

In some embodiments using monomer (A3), C _1-6 alkyl (meth)acrylate may be used as monomer (A3). By using C _1-6 alkyl (meth)acrylate, the storage modulus of each temperature _range can be adjusted. For example, the storage elastic modulus in the high temperature range can be set to be relatively high, or the difference in storage elastic modulus between the low temperature range and the high temperature range can be suppressed from increasing. Additionally, C _1-6 alkyl (meth)acrylate tends to have excellent copolymerization with monomer (A1). C _1-6 alkyl (meth)acrylate can be used individually or in combination of two or _more types. As C _1-6 alkyl (meth)acrylate, C _1-6 alkyl acrylate is preferable, C _2-6 alkyl acrylate is more preferable, and C _4-6 alkyl acrylate is still more preferable _. In several other embodiments, the C _1-6 alkyl (meth)acrylate is preferably C _1-4 alkyl (meth)acrylate, more preferably C _2-4 alkyl (meth)acrylate, More preferably, it is C _2-4 alkyl acrylate. A _suitable example of C _1-6 alkyl (meth)acrylate includes BA.

The content of C _1-6 alkyl (meth)acrylate in the monomer component constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 8% by weight. It may be % or more. In some embodiments, the content of the C _1-6 alkyl (meth)acrylate may be 10% by weight or more, 15% by weight or more, or 20% by weight or more from the viewpoint of improved flexibility, adhesive strength, etc. It may be 25% by weight or more (for example, 30% by weight or more). The upper limit of the content of C _1-6 alkyl (meth)acrylate in the monomer component is, for example, less than 50% by weight, and may be less than 35% by weight. In some embodiments, from the viewpoint of maintaining a high refractive index, the content of the C _1-6 alkyl (meth)acrylate is, for example, 24% by weight or less, preferably less than 20% by weight, and less than 17% by weight. It is more preferable, and may be less than 12% by weight, less than 7% by weight, less than 3% by weight, or less than 1% by weight. The technology disclosed herein can also be practiced without substantially using C _1-6 alkyl (meth)acrylate.

In several other embodiments of using monomer (A3), C _7-12 alkyl (meth)acrylate can be preferably used as monomer (A3). The storage modulus can be preferably reduced by using C _{7 -12} alkyl (meth)acrylate. C _{7 -12} Alkyl (meth)acrylate can be used individually or in combination of two or more types. As C _7-12 alkyl (meth)acrylate, C _7-10 alkyl acrylate is preferable, C _7-9 alkyl acrylate is more preferable, and C ₈ alkyl acrylate is still more preferable _. Examples of C _{7 -12} alkyl (meth)acrylate include 2EHA, iNA, and LA, and a suitable example includes 2EHA.

The content of C _7-12 alkyl (meth)acrylate in the monomer component constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 8% by weight. It may be % or more. In some embodiments, the content of the C _7-12 alkyl (meth)acrylate may be 10% by weight or more, 15% by weight or more, or 20% by weight or more from the viewpoint of improved flexibility, adhesive strength, etc. It may be 25% by weight or more (for example, 30% by weight or more). The upper limit of the content of C _7-12 alkyl (meth)acrylate in the monomer component is, for example, less than 50% by weight, and may be less than 35% by weight. In some embodiments, from the viewpoint of maintaining a high refractive index, the content of the C _7-12 alkyl (meth)acrylate is, for example, 24% by weight or less, preferably less than 20% by weight, and less than 17% by weight. It is more preferable, and may be less than 12% by weight, less than 7% by weight, less than 3% by weight, or less than 1% by weight. The technology disclosed herein can also be practiced without substantially using C _7-12 alkyl (meth)acrylate.

In some embodiments of using the monomer (A3), it is preferable that at least a part of the monomer (A3) is an alkyl acrylate from the viewpoint of improving flexibility. The use of alkyl acrylate is also advantageous in terms of adhesive properties such as adhesive strength. For example, it is preferable that 50% by weight or more of monomer (A3) is alkyl acrylate, and the proportion of alkyl acrylate in monomer (A3) is more preferably 75% by weight or more, and even more preferably 90% by weight. It is % by weight or more, and substantially 100 % by weight of the monomer (A3) may be an alkyl acrylate. As the monomer (A3), only one type or two or more types of alkyl acrylate may be used, and an alkyl methacrylate may not be used.

In an embodiment in which the monomer component contains alkyl (meth)acrylate, the content of the alkyl (meth)acrylate in the monomer component can be set so that the use effect is appropriately exhibited. In some embodiments, the content of the alkyl (meth)acrylate may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 8% by weight or more. The upper limit of the content of monomer (A3) in the monomer component is set so that the total of the contents of monomer (A1) and (A2) does not exceed 100% by weight, for example, less than 50% by weight, and 35% by weight. It may be less than %. In some embodiments, the content of the monomer (A3) may be, for example, 24% by weight or less. Generally, the refractive index of alkyl (meth)acrylate is relatively low, so in order to increase the refractive index, it is advantageous to limit the content of monomer (A3) in the monomer component and increase the content of monomer (A1) relatively. . From this viewpoint, the content of monomer (A3) is suitably less than 23% by weight of the monomer component, preferably less than 20% by weight, more preferably less than 17% by weight, less than 12% by weight, and may be 7% by weight. It may be less than 3% by weight, or less than 1% by weight. The technology disclosed herein can also be preferably implemented in an embodiment in which monomer (A3) is not substantially used.

(Other monomers)

The monomer component constituting the acrylic polymer may, if necessary, contain monomers other than the above monomers (A1), (A2), and (A3) (hereinafter referred to as “other monomers”). The other monomers mentioned above can be used for purposes such as adjusting the Tg of the acrylic polymer, adjusting adhesive performance, and improving compatibility in the adhesive layer. The other monomers mentioned above can be used individually or in combination of two or more types.

Examples of the other monomers include monomers (functional group-containing monomers) having functional groups other than hydroxyl groups and carboxyl groups. For example, other monomers that can improve the cohesion and heat resistance of the adhesive include a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, and a cyano group-containing monomer. In addition, as a monomer that can introduce a functional group that can serve as a crosslinking origin into an acrylic polymer, or can contribute to improving adhesion to an adherend or improving compatibility in an adhesive, an amide group-containing monomer (e.g., (meth)acrylamide, N-methylol (meth)acrylamide, etc.), amino group-containing monomers (e.g., aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, etc.), nitrogen Monomers having atom-containing rings (e.g., N-vinyl-2-pyrrolidone, N-(meth)acryloylmorpholine, etc.), imide group-containing monomers, epoxy group-containing monomers, keto group-containing monomers, isocyanate groups Containing monomers, alkoxysilyl group-containing monomers, etc. can be mentioned. In addition, among the monomers having a nitrogen atom-containing ring, there are also monomers containing an amide group, such as N-vinyl-2-pyrrolidone. The same applies to the relationship between the monomer having the nitrogen atom-containing ring and the monomer containing an amino group.

Other monomers that can be used other than the functional group-containing monomers include vinyl ester monomers such as vinyl acetate; Non-aromatic ring-containing (meth)acrylates such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; Olefin-based monomers such as ethylene, butadiene, and isobutylene; Chlorine-containing monomers such as vinyl chloride; Alkoxy group-containing monomers such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and ethoxyethoxyethyl (meth)acrylate; Vinyl ether-based monomers such as methyl vinyl ether; etc. can be mentioned. A suitable example of another monomer that can be used for purposes such as improving the flexibility of the adhesive includes ethoxyethoxyethyl acrylate (alias: ethylcarbitol acrylate, homopolymer Tg: -67°C).

When using the other monomers mentioned above, the amount used is not particularly limited and can be appropriately set within the range where the total amount of monomer components does not exceed 100% by weight. From the viewpoint of facilitating the effect of improving the refractive index by using the monomer (A1), the content of the other monomers in the monomer component can be, for example, approximately 35% by weight or less, and approximately 25% by weight or less. It is appropriate to set it to (for example, 0 to 25% by weight), approximately 20% by weight or less (for example, 0 to 20% by weight) may be sufficient, and approximately 10% by weight or less (for example, 0 to 10% by weight). It is advantageous, and preferably approximately 5% by weight or less, for example approximately 1% by weight or less. The technology disclosed herein can be preferably implemented in a manner in which the monomer component does not substantially contain the other monomers described above.

In some embodiments, the monomer component constituting the acrylic polymer may have a composition in which the amount of methacryloyl group-containing monomer used is suppressed to a predetermined level or less. The usage amount of the methacryloyl group-containing monomer in the monomer component may be, for example, less than 5% by weight, less than 3% by weight, less than 1% by weight, or less than 0.5% by weight. Limiting the amount of methacryloyl group-containing monomer used in this way can be advantageous from the viewpoint of realizing an adhesive that has both flexibility and adhesiveness and a high refractive index in a good balance. The monomer component constituting the acrylic polymer may be a composition that does not contain a methacryloyl group-containing monomer (for example, a composition consisting only of an acryloyl group-containing monomer).

(Acrylic polymer without monomer (A1) as an essential monomer unit)

The silicone-based plasticizer disclosed herein is useful as a plasticizer that stably exerts the action of plasticizing the adhesive when mixed with an acrylic adhesive, regardless of whether the acrylic polymer, which is the base polymer, contains the monomer (A1) as a monomer unit. do. In some embodiments, the base polymer of the acrylic adhesive contains at least an alkyl (meth)acrylate and does not contain monomer (A1) as an essential component (i.e., may or may not contain monomer (A1)). It may be an acrylic polymer (which does not need to be used). Alkyl (meth)acrylates can be helpful in adjusting the balance between flexibility and cohesiveness of the adhesive by selecting the type and amount used. In addition, it can be helpful in improving adhesive properties such as compatibility of additives in the adhesive and adhesive strength. Alkyl (meth)acrylate can be used individually or in combination of two or more types.

As the alkyl (meth)acrylate, C _1-20 alkyl (meth)acrylate can be preferably used. C _1-20 alkyl (meth)acrylate, C _4-8 alkyl (meth)acrylate, C _1-6 alkyl (meth)acrylate, C _7-12 alkyl (meth)acrylate that can be used as alkyl (meth)acrylate. ) Specific examples and suitable examples of acrylates include those similar to the monomer (A3) described above. Use of low Tg alkyl (meth)acrylates with a homopolymer Tg of a predetermined level or less and specific examples thereof, use of alkyl (meth)acrylates with a homopolymer Tg of a predetermined level or higher than a predetermined level and specific examples thereof, such alkyl (meth)acrylates ) The same applies to the monomer (A3) described above regarding the ability to use acrylate and low Tg alkyl (meth)acrylate together. In some embodiments, at least a portion of the alkyl (meth)acrylate may be C _4-9 alkyl (meth)acrylate. Examples of C _4-9 alkyl (meth)acrylate in this embodiment include, in addition to the C _4-8 alkyl (meth)acrylate, n-nonyl (meth)acrylate and isononyl (meth)acrylate ( For example, isononyl acrylate).

In an acrylic polymer that does not have monomer (A1) as an essential monomer unit, the content of alkyl (meth)acrylate in the monomer component constituting the acrylic polymer may be, for example, 30% by weight or more, and 40% by weight. % or more is appropriate, preferably 50% by weight or more (for example, more than 50% by weight), may be 60% by weight or more, may be 70% by weight or more, may be 80% by weight or more, and may be 90% by weight or more. It may be 95% by weight or more, and may be 97% by weight or more. The content of alkyl (meth)acrylate in the monomer component may be 100% by weight, but from the viewpoint of cohesiveness and heat characteristics (e.g. heat resistance characteristics) of the adhesive, it is appropriate to be 99.8% by weight or less, and 99.5% by weight. It is advantageous to be less than 99% by weight, preferably 98% by weight or less, 95% by weight or less, 90% by weight or less, 80% by weight or less, and 75% by weight or less.

In some embodiments, it is preferable to use at least C _4-9 alkyl (meth)acrylate as the alkyl (meth)acrylate. Among them, use of C _4-9 alkyl acrylate is more preferable. C _4-9 alkyl (meth)acrylate can be used individually or in combination of two or _more types. By using C _{4 -9} alkyl (meth)acrylate, it is easy to improve the flexibility of the adhesive, and it is also easy to obtain good adhesive properties (adhesion, etc.).

The content of C _4-9 alkyl (meth)acrylate in the monomer component constituting the acrylic polymer may be, for example, 5% by weight or more, and is preferably 10% by weight or more from the viewpoint of obtaining higher usage effects. It is preferably 20% by weight or more, more preferably 30% by weight or more, may be 40% by weight or more, may be 50% by weight or more, may be 60% by weight or more, may be 70% by weight or more, and may be 80% by weight or more. It may be 85% by weight or more. The content of C _4-9 alkyl (meth)acrylate in the monomer component may be 100% by weight, but from the viewpoint of cohesiveness and thermal characteristics of the adhesive, it is preferably 99% by weight or less, and may be 95% by weight or less. , may be 90% by weight or less, may be 80% by weight or less, and may be 75% by weight or less.

In addition, the proportion of C _4-9 alkyl (meth)acrylate in the alkyl (meth)acrylate contained in the monomer component is suitably 30% by weight or more, preferably 50% by weight or more, more preferably 60% by weight. % or more, more preferably 75% by weight or more, and may be 85% by weight or more, 90% by weight or more, or 95% by weight or more, and may be substantially 100% by weight.

In some embodiments, it is preferred that the C _4-9 alkyl acrylate contained in the monomer component includes at least C _7-9 alkyl acrylate (for example, 2EHA). The proportion of C _7-9 alkyl acrylate in C _4-9 alkyl acrylate may be, for example, 30% by weight or more, preferably more than 50 _% by weight, 70% by weight or more, or 85% by weight or more. It may be 100% by weight.

In an acrylic polymer that does not have a monomer (A1) as an essential monomer unit, the monomer components constituting the acrylic polymer include alkyl (meth)acrylate and other monomers copolymerizable with alkyl (meth)acrylate (copolymerizable monomer ) may be included. As the copolymerizable monomer, one or two or more types selected from the group consisting of the monomers corresponding to the above-mentioned monomers (A2) and/or (A1) and the monomers exemplified as the other monomers above can be used.

In some embodiments, the monomer component constituting the acrylic polymer preferably contains a monomer corresponding to the monomer (A2). Specific examples, suitable examples, usage amounts, etc. of the monomer corresponding to the monomer (A2) may be the same as those of the acrylic polymer containing the monomer (A1) as a monomer unit. It is preferable to use at least a hydroxyl group-containing monomer. Suitable examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA). The amount of the hydroxyl-containing monomer used in the monomer component may be, for example, 0.01% by weight or more. From the viewpoint of obtaining higher usage effects, it is suitably 0.1% by weight or more, preferably 0.5% by weight or more, and 1% by weight. It may be more than 1.5% by weight, 3% by weight or more, 5% by weight or more, 8% by weight or more, or 10% by weight or more. In addition, the amount of the hydroxyl group-containing monomer used in the monomer component may be, for example, 30% by weight or less, and from the viewpoint of the low-temperature characteristics of the adhesive, etc., it is advantageous to be 25% by weight or less, preferably 20% by weight or less, and 15% by weight or less. It may be % or less, 10 weight% or less, 7 weight% or less, 4 weight% or less, and 2 weight% or less. There is no need to use hydroxyl-containing monomers.

In some embodiments, the monomer component constituting the acrylic polymer preferably contains a monomer having a nitrogen atom-containing ring. A monomer having a nitrogen atom-containing ring can be helpful in adjusting the cohesive force of the adhesive and improving compatibility between the acrylic polymer and other components in the adhesive. As the monomer having a nitrogen atom-containing ring, N-vinyl cyclic amide, cyclic amide having a (meth)acryloyl group, etc. can be preferably used. The monomer having a nitrogen atom-containing ring can be used individually or in combination of two or more types.

Specific examples of N-vinyl cyclic amides include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, and N-vinyl-2-caprolactam. -1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, etc. are mentioned. Particularly preferable examples include N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam.

Specific examples of cyclic amides having a (meth)acryloyl group include N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine. , N-(meth)acryloylmorpholine, etc. A suitable example includes N-acryloylmorpholine (ACMO).

The usage amount of the monomer having a nitrogen atom-containing ring in the monomer component may be, for example, 0.1% by weight or more. From the viewpoint of obtaining a higher usage effect, it is suitably 1% by weight or more, and is preferably 3% by weight or more. , it may be 5% by weight or more, may be 7% by weight or more, may be 10% by weight or more, and may be 12% by weight or more. In addition, the amount of the monomer having a nitrogen atom-containing ring in the monomer component may be, for example, 30% by weight or less, and may be 25% by weight from the viewpoint of the low-temperature characteristics of the adhesive (e.g., flexibility under low temperature). It is advantageous to be less than 22% by weight, preferably 22% by weight or less, 17% by weight or less, 13% by weight or less, and 10% by weight or less. It is not necessary to use a monomer having a nitrogen atom-containing ring.

In some embodiments, as the copolymerizable monomer, a monomer having a nitrogen atom-containing ring and a hydroxyl group-containing monomer can be used in combination. In this case, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group can be, for example, 0.1% by weight or more of the monomer component constituting the acrylic polymer, preferably 1% by weight or more, more preferably 1% by weight or more. It is 3% by weight or more, more preferably 5% by weight or more, especially preferably 7% by weight or more (for example, 9% by weight or more), may be 10% by weight or more, may be 15% by weight or more, and may be 20% by weight or more. It may be % by weight or more, and may be 25 % by weight or more. In addition, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group can be, for example, 50% by weight or less of the monomer component, or less than 50% by weight, and is preferably 40% by weight or less, and is 35% by weight. It may be less than or equal to 30% by weight. In some embodiments, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group may be 20% by weight or less, or 15% by weight or less (for example, 12% by weight or less) of the monomer component.

In acrylic polymers that do not use monomer (A1) as an essential monomer unit, the content of monomer (A1) in the monomer component is not particularly limited and can be set so that the total content of monomer (A1) does not exceed 100% by weight. You can. From the viewpoint of making it easier to obtain the effect of using the monomer (A1), in some embodiments, the content of the monomer (A1) in the monomer component is 1% by weight or more, 3% by weight or more, or 5% by weight. It could be more than that. In addition, from the viewpoint of improving the flexibility of the adhesive, in some embodiments, the content of the monomer (A1) may be, for example, less than 70% by weight, less than 50% by weight, or less than 30% by weight, It may be 20% by weight or less, 10% by weight or less, 5% by weight or less, 3% by weight or less, and 1% by weight or less. The monomer component may be an acrylic polymer that substantially does not contain monomer (A1).

(Base polymer containing monomer (A _UH ) as monomer unit)

In some embodiments of the technology disclosed herein, the base polymer of the adhesive is polymerized with a ring structure corresponding to at least one of a double bond-containing ring and a heterocycle (hereinafter, such ring structure is also referred to as a “UH ring”). A monomer containing a functional group in one molecule (hereinafter, such a monomer is also referred to as “monomer (A _UH )”) can be preferably used as a monomer unit. That is, it is preferable that the monomer component constituting the base polymer (for example, an acrylic polymer) contains a monomer (A _UH ).

Here, in this specification, the term “double bond-containing ring” is a concept including a conjugated double bond-containing ring and a non-conjugated double bond-containing ring, and preferably corresponds to at least one of an aromatic ring and a heterocycle (heterocycle). It's a circle. The same applies to the double bond-containing ring that any plasticizer described later may have. The heterocycle may have a structure contained in an aromatic ring (heteroaromatic ring), or may have a double bond-containing heterocycle structure different from the aromatic ring. In the above heterocycle, the heteroatom included as a ring constituent atom may be, for example, one or two or more selected from the group consisting of nitrogen (N), sulfur (S), and oxygen (O). Non-limiting examples of the double bond-containing ring include a benzene ring; Condensed rings of naphthalene ring, indene ring, azulene ring, anthracene ring, and phenanthrene ring; carbon rings such as pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, isoxazole ring, thiazole ring, Thiophene ring; Complex rings such as The double bond-containing ring may be a non-fused ring (benzene ring, triazine ring, etc.) or a condensed ring. The condensed ring may have a structure in which 1 or 2 or more carbon rings and 1 or 2 or more heterocycles are condensed, such as a dinaphthothiophene structure or a benzotriazole structure.

Unless otherwise specified, the double bond-containing ring in this specification may have one or two or more substituents on the ring constituent atoms, or may not have a substituent. In this specification, examples of “substituents” include alkyl groups (e.g., alkyl groups having 1 to 12 carbon atoms), aryl groups (phenyl groups, naphthyl groups, biphenyl groups, etc.), and alkyl groups and halogen groups on ring atoms. Atoms (fluorine atom, chlorine atom, bromine atom, etc.), hydroxyl group, amino group, monoalkylamino group, dialkylamino group, cyano group (may have 1 or 2 or more acyclic substituents), cycloalkyl group, hydroxyalkyl group, monoalkyl Amino group, dialkylamino group, glycidyl group, aralkyl group (e.g., a group in which one or two or more hydrogen atoms of an alkyl group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, are substituted with the aryl group), alkene Ethylenically unsaturated groups such as a nyl group (e.g., vinyl group, allyl group) or (meth)acryloyl group, and a bond selected from the group consisting of an ether bond, a thioether bond, and an ester bond in the chain structure of these groups is 1. or two or more intervening groups (e.g., ethoxyethyl group, ethoxyethoxyethyl group, phenoxyethyl group), in which some or all of the hydrogen bonded to carbon is a halogen atom (fluorine atom, chlorine atom, bromine atom) etc.), groups having heteroatoms such as O, S, N at the end of the double bond-containing ring side of these groups (e.g., alkoxy group, aryloxy group, cycloalkyloxy group, hydroxyalkyloxy group) group, glycidyloxy group, alkylthio group, (meth)acryloyloxy group. When the hetero atom is N, the remaining valence of N is bonded to a hydrogen atom or another substituent), hydroxyl group, amino group, cyanogroup. Nogi, halogen atoms (fluorine atom, chlorine atom, bromine atom, etc.) are examples, but are not limited to these. Examples of the above substituents include those having a double bond-containing ring (e.g., aryl group, aralkyl group, and groups having heteroatoms such as O, S, N, etc. at the end of these groups on the side of the ring constituent atom); Both those that do not have a bond-containing ring (for example, an alkyl group, an alkoxy group, an alkylthio group, etc.) are included.

The concept of the monomer (A _UH ) includes, in addition to the aromatic ring-containing monomer corresponding to the above-described monomer (A1), a double bond-containing ring-containing monomer that does not correspond to the monomer (A1), and a double bond-containing ring-containing monomer that does not correspond to the double bond-containing ring. Monomers having subunits may be included. Specific examples of the monomer having a heterocycle that does not correspond to a double bond-containing ring include the above-mentioned N-vinyl cyclic amide and cyclic amide having a (meth)acryloyl group, but are not limited to these. Monomer (A _UH ) can be used individually or in combination of two or more types. In an adhesive where the base polymer (e.g., an acrylic polymer) contains a monomer (A _UH ) as a monomer unit, the effect of using the silicone-based plasticizer disclosed herein (e.g., the effect of providing good stability and flexibility) can be exerted appropriately. The reason for this is not to be particularly limited, but the affinity (interaction) between the double bond-containing ring of the silicone-based plasticizer disclosed herein and the UH ring derived from the monomer (A _UH ) and contained in the base polymer is the affinity (interaction) of the adhesive. It is thought that it contributes advantageously to plasticization and improvement of its stability. In some embodiments, a base polymer having a UH ring in the side chain can be preferably employed because of the ease of the above interaction. Additionally, in some embodiments, it is preferable that at least part of the UH ring of the base polymer is a double bond-containing ring, and both the double bond-containing ring of the silicone-based plasticizer and the UH ring of the base polymer are aromatic rings (e.g., benzene ring). It is particularly preferable to include a carbon aromatic ring, etc.).

An example of a base polymer containing a monomer (A _UH ) as a monomer unit is a monomer (A _UH ) having a ring structure (i.e. UH ring) corresponding to at least one of a double bond-containing ring and a heterocycle and an ethylenically unsaturated group within one molecule. An acrylic polymer (e.g., an acrylic polymer that is a polymer of a monomer component containing monomer (A1)) or a rubber-based polymer (e.g., styrene-butadiene block copolymer or styrene) containing one or more types of as monomer units. block copolymers of a monovinyl-substituted aromatic compound and a conjugated diene compound, such as an isoprene block copolymer); Dicarboxylic acids having a UH ring (e.g., aromatic dicarboxylic acids such as isophthalic acid, terephtha, etc.) and polyols having a UH ring (e.g., aromatic dihydroxybenzene, p-xylenediol, etc.) polyester-based polymer obtained from raw materials containing at least one of (diol); Polyisocyanates having a UH ring (e.g., aromatic polyisocyanates such as phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, trimethylolpropane/tolylene diisocyanate trimer adduct, etc.) A urethane-based polymer obtained from a raw material containing at least one of polyols having a UH ring (for example, aromatic polyether polyol, aromatic polyester polyol, etc.); A silicone-based polymer formed from an addition reaction type silicone-based adhesive composition containing an organopolysiloxane having a UH ring (e.g., polyalkylphenylsiloxane such as polymethylphenylsiloxane or polyethylphenylsiloxane) or a commercially available phenyl-based silicone. Base polymers in adhesives; etc. can be mentioned. The technology disclosed herein can be preferably carried out in an embodiment in which the base polymer is a non-silicone polymer (for example, an acrylic polymer or a rubber polymer, preferably an acrylic polymer).

The content of the monomer (A _UH ) in the monomer component constituting the base polymer may be, for example, 1% by weight or more, or 5% by weight or more. From the viewpoint of making it easy to achieve a good and stable plasticizing effect by the silicone-based plasticizer disclosed herein, in some embodiments, the content of monomer (A _UH ) in the monomer component is suitably 7% by weight or more. , it is advantageous to be 12% by weight or more, preferably 20% by weight or more (e.g. 30% by weight or more), more preferably 50% by weight or more, may be 60% by weight or more, and 70% by weight or more (e.g. (e.g., exceeding 70% by weight), 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, 91% by weight or more, 92% by weight or more, 93% by weight or more. It may be 94% by weight or more, 95% by weight or more, 96% by weight or more, 97% by weight or more, 98% by weight or more, or 99% by weight or more. The content of monomer (A _UH ) in the monomer component is typically less than 100% by weight, and from the viewpoint of making it easier to balance the properties, it is advantageous to be approximately 99% by weight or less, and may be 98% by weight or less, It may be 96 weight% or less, 93 weight% or less, and 90 weight% or less. In some embodiments, from the viewpoint of lowering the elastic modulus of the adhesive and making it easier to realize higher adhesive properties and/or optical properties (for example, transparency), the monomer (A _UH ) in the monomer component is The content may be less than 90% by weight, less than 85% by weight, less than 80% by weight, less than 50% by weight, less than 30% by weight, less than 25% by weight, and less than 22% by weight. It may be 17% by weight or less, 13% by weight or less, or 10% by weight or less. The above description regarding the top and bottom of the content of the monomer (A _UH ) in the monomer component also includes the top and bottom of the content of the aromatic ring-containing monomer (for example, a monomer containing an aromatic carbocyclic ring) in the monomer component. It can be applied.

(Amount of monomer containing carboxyl group used)

In some embodiments, the monomer component constituting the base polymer (e.g., acrylic polymer) of the adhesive is limited in the amount of carboxyl group-containing monomer used from the viewpoint of suppressing coloring or discoloration (e.g., yellowing) of the adhesive. there is. The amount of the carboxyl group-containing monomer used in the monomer component may be, for example, less than 1% by weight, less than 0.5% by weight, less than 0.3% by weight, less than 0.1% by weight, or less than 0.05% by weight. This limitation in the amount of carboxyl group-containing monomer is due to corrosion of metal materials (for example, metal wiring or metal films that may be present on the adherend) that may be placed in contact with or close to the adhesive disclosed herein. It is also advantageous from the perspective of suppressing . The technology disclosed herein can be practiced in an embodiment in which the monomer component does not contain a carboxyl group-containing monomer.

For the same reason, in some embodiments, the monomer component constituting the base polymer of the adhesive may have a limited amount of monomer having an acidic functional group (including a sulfonic acid group, a phosphoric acid group, etc. in addition to a carboxyl group). As the usage amount of the acidic functional group-containing monomer in the monomer component of this aspect, the above-mentioned preferable usage amount of the carboxyl group-containing monomer can be applied. The technology disclosed herein can be practiced in an embodiment in which the monomer component does not contain an acidic group-containing monomer (that is, the base polymer of the adhesive is acid-free).

(Glass transition temperature)

The monomer component constituting the base polymer (for example, an acrylic polymer) of the adhesive preferably has a composition such that the glass transition temperature (Tg) based on the composition of the monomer component is approximately 15°C or lower. In some embodiments, the glass transition temperature Tg is preferably 10°C or lower, more preferably 5°C or lower, further preferably 1°C or lower, and may be 0°C or lower. In several other embodiments, the Tg may be -10°C or lower, -20°C or lower, -25°C or lower, -30°C or lower, and -35°C or lower. A low Tg can be advantageous from the viewpoint of improving the flexibility of the adhesive. In addition, the Tg may be, for example, -60°C or higher, and from the viewpoint of facilitating high refractive index of the adhesive, it is preferably -50°C or higher, more preferably -45°C or higher, and exceeds -40°C. It's okay. In some embodiments, the Tg may be greater than -30°C, greater than -20°C, greater than -10°C, or greater than -5°C. An adhesive that has both high refractive index and flexibility can be suitably formed by using a base polymer with a composition having a Tg in the above range.

Here, Tg, which is based on the composition of the monomer component constituting the base polymer (for example, an acrylic polymer), unless otherwise specified, refers to the glass transition temperature determined by Fox's equation based on the composition of the monomer component. . As described below, the Fox equation is a relationship between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by independently polymerizing each of the monomers constituting the copolymer.

1/Tg=Σ(Wi/Tgi)

In the Fox equation, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio by weight), and Tgi is the homopolymer of monomer i. Indicates the glass transition temperature (unit: K).

As the glass transition temperature of the homopolymer used to calculate Tg, the value described in known materials such as “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989) is used. For monomers for which multiple types of values are described in the Polymer Handbook, the highest value is adopted. If the nominal value of the glass transition temperature of the homopolymer is provided by the manufacturer, etc., the nominal value can be adopted. If the Tg of the homopolymer is not described in the known data, the value obtained by the measurement method described in Japanese Patent Application Laid-Open No. 2007-51271 is used.

(Weight average molecular weight of base polymer)

In the adhesive disclosed herein, the weight average molecular weight (Mw) of the base polymer (for example, an acrylic polymer) is not particularly limited, and may be, for example, approximately 1×10 ⁴ or greater, and approximately 2×10 ⁴ or greater. It is suitable, and is preferably approximately 5 × 10 ⁴ or more, more preferably approximately 10 × 10 ⁴ or more, may be approximately 20 × 10 ⁴ or more, may be approximately 30 × 10 ⁴ or more, and may be approximately 40 × 10 ⁴ or more. , may be approximately 45×10 ⁴ or more. By using a base polymer whose Mw is a predetermined value or more, it is easy to obtain an appropriate cohesive force that can exhibit the desired adhesive properties. Additionally, a larger amount of additives (for example, silicone-based plasticizer) can be contained, and the desired flexibility tends to be easily achieved. In some embodiments, the Mw of the base polymer may be approximately 50×10 ⁴ or greater, approximately 70×10 ⁴ or greater, or approximately 80×10 ⁴ or greater. In addition, the upper limit of the Mw of the base polymer is, for example, approximately 500 × 10 ⁴ or less, and from the viewpoint of adhesion performance, it is suitably approximately 400 × 10 ⁴ or less, and approximately 300 × 10 ⁴ or less (more preferably approximately 150 × 10 4 or less). ×10 ⁴ or less, for example, approximately 130×10 ⁴ or less) is preferred. In some embodiments, the Mw may be less than 100×10 ⁴ , 80×10 ⁴ or less, or 60×10 ⁴ or less. The effects achieved by the technology disclosed herein can be suitably realized in an embodiment using a base polymer having Mw in the above range.

Here, the Mw of the base polymer (for example, an acrylic polymer) can be calculated by converting it to polystyrene using gel permeation chromatography (GPC). Specifically, it can be obtained by measuring under the following conditions using the product name "HLC-8220GPC" (manufactured by Tosoh Corporation) as a GPC measuring device.

[GPC measurement conditions]

Sample concentration: 0.2% by weight (tetrahydrofuran solution)

Sample injection volume: 10μL

Eluent: Tetrahydrofuran (THF)

Flow rate (flow rate): 0.6mL/min

Column temperature (measurement temperature): 40℃

column:

Sample column: 1 unit of product name “TSKguardcolumn SuperHZ-H” + 2 units of product name “TSKgel SuperHZM-H” (manufactured by Tosoh Corporation)

Reference column: 1 product name “TSKgel SuperH-RC” (manufactured by Tosoh Corporation)

Detector: Differential refractometer (RI)

Standard sample: polystyrene

Although not particularly limited, the ratio of the Mw of the base polymer to the molecular weight of the silicone-based plasticizer contained in the adhesive (hereinafter also referred to as “ratio (P/S)”) may be, for example, in the range of 15 to 10,000. . It is preferable that the ratio (P/S) is more than a predetermined value from the viewpoint of compatibility of the silicone-based plasticizer in the adhesive. Additionally, the adhesive can contain a larger amount of silicone-based plasticizer, which tends to make it easier to achieve the desired flexibility. In some embodiments, the ratio (P/S) is suitably, for example, 30 or more, preferably 70 or more, more preferably 150 or more, 300 or more, 400 or more, or 500 or more. It may be 600 or more, 700 or more, 800 or more, 850 or more, or 900 or more. In addition, the fact that the ratio (P/S) is below a predetermined value can be advantageous from the viewpoint of enhancing the softening (low-elasticity-modifying) effect of the silicone-based plasticizer. In some embodiments, the ratio (P/S) is suitably, for example, 7000 or less, preferably 6000 or less, more preferably 5000 or less, may be 4000 or less, may be 3000 or less, and may be 2500 or less. It may be 2000 or less, 1500 or less, or 1000 or less.

(Amount of silicone plasticizer used)

In the technology disclosed herein, the amount of silicone-based plasticizer used is not particularly limited, and can be set to obtain an adhesive having desired properties (flexibility (e.g., storage modulus), optical properties (e.g., refractive index), etc.) . In some embodiments, the amount of silicone plasticizer used per 100 parts by weight of the base polymer (e.g., acrylic polymer) of the adhesive may be, for example, 0.1 part by weight or more, and from the viewpoint of obtaining a higher effect, 0.5 part by weight. It is appropriate to use at least 1 part by weight, it is advantageous to use at least 1 part by weight, it is preferable to use at least 5 parts by weight, it may be at least 10 parts by weight, it may be at least 15 parts by weight, it may be at least 25 parts by weight, and it may be at least 40 parts by weight. It may be more than 50 parts by weight, 60 parts by weight or more, 75 parts by weight or more, 85 parts by weight or more, or 95 parts by weight or more. In addition, the amount of silicone plasticizer used per 100 parts by weight of the base polymer can be, for example, 200 parts by weight or less, and from the viewpoint of making it easy to maintain a balance with the adhesive properties (e.g., cohesiveness), it is 150 parts by weight or less. It is advantageous, and it is preferable to set it to 120 parts by weight or less, may be 100 parts by weight or less, may be 90 parts by weight or less, may be 70 parts by weight or less, may be 55 parts by weight or less, may be 45 parts by weight or less, and may be 35 parts by weight or less. It may be less than or equal to 25 parts by weight, or less than or equal to 15 parts by weight (for example, less than or equal to 10 parts by weight).

(Additive (H _RO ))

The adhesive disclosed herein may contain an organic material with a higher refractive index than the base polymer (for example, an acrylic polymer) as an additive used as desired. Hereinafter, such organic materials may be referred to as “additive (H _RO ).” Here, “H _RO ” indicates that it is an organic material with a high refractive index. By using an additive (H _RO ), an adhesive that more appropriately achieves both refractive index and adhesive properties (peel strength, flexibility, etc.) can be realized. The organic material used as the additive ( _HRO ) may be a polymer or a non-polymer. Additionally, it may or may not have a polymerizable functional group. In addition, in this specification, the additive (H _RO ) is defined as being different from the compound used as the silicone-based plasticizer described above or the optional plasticizer described later. For example, the additive (H _RO ) may not be liquid at 30°C (eg, 25°C or 20°C). Additives (H _RO ) can be used individually or in combination of two or more types.

The refractive index of the additive (H _RO ) can be set in an appropriate range in relation to the refractive index of the base polymer (for example, acrylic polymer), and is therefore not limited to a specific range. The refractive index of the additive (H _RO ) is, for example, greater than 1.55, greater than 1.56, or greater than 1.57, and can be selected from a range higher than the refractive index of the base polymer. From the viewpoint of increasing the refractive index of the adhesive, in some embodiments, the refractive index of the additive ( _HRO ) is advantageously 1.58 or more, preferably 1.60 or more, more preferably 1.63 or more, 1.65 or more, and may be 1.70 or more. It may be more than 1.75. By using an additive (H _RO ) with a higher refractive index, the target refractive index can be achieved even by using a smaller amount of the additive (H _RO ). This is desirable from the viewpoint of suppressing deterioration of adhesive properties and optical properties. The upper limit of the refractive index of the additive ( _HRO ) is not particularly limited, but is, for example, 3.000 or less, and may be 2.500 or less, from the viewpoint of compatibility in the adhesive and ease of coexistence of high refractive index and flexibility suitable as an adhesive. It may be 2.000 or less, 1.950 or less, 1.900 or less, and 1.850 or less.

In addition, the refractive index of the additive (H _RO ), like the refractive index of the monomer, is measured using an Abbe refractometer under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. If the nominal value of the refractive index at 25°C is provided by the manufacturer, etc., the nominal value can be adopted.

The molecular weight of the organic material used as the additive ( _HRO ) is not particularly limited and can be selected depending on the purpose. From the viewpoint of achieving a good balance between the effect of increasing the refractive index and other properties (e.g., optical properties such as flexibility and haze suitable for an adhesive), in some embodiments, the molecular weight of the additive ( _HRO ) is approximately 10000. It is suitable to be less than 5000, more preferably less than 3000 (for example, less than 1000), less than 800, less than 600, less than 500, and less than 400. The fact that the molecular weight of the additive ( _HRO ) is not too large can be advantageous from the viewpoint of improving compatibility in the adhesive. In addition, the molecular weight of the additive ( _HRO ) may be, for example, 130 or more, or 150 or more. In some embodiments, the molecular weight of the additive ( _HRO ) is preferably 170 or more, more preferably 200 or more, may be 230 or more, or 250 or more from the viewpoint of increasing the refractive index of the additive ( _HRO ). It may be 270 or more, 300 or more, 500 or more, 1000 or more, or 2000 or more. In some embodiments, a polymer having a molecular weight of about 1,000 to 10,000 (for example, 1,000 to 5,000) can be used as the additive (H _RO ).

As the molecular weight of the additive ( _HRO ), for non-polymers or polymers with a low degree of polymerization (for example, about 2 to 5 polymers), the molecular weight calculated based on the chemical structure or matrix-assisted laser desorption ionization time-of-flight mass spectrometry ( Measurements using MALDI-TOF-MS) can be used. When the additive (H _RO ) is a polymer with a higher degree of polymerization, the weight average molecular weight (Mw) based on GPC conducted under appropriate conditions can be used. If a nominal value of molecular weight is provided by a manufacturer, etc., that nominal value can be adopted.

Examples of organic materials that can be selected as an additive (H _RO ) include organic compounds having an aromatic ring, organic compounds having a heterocycle (may be an aromatic ring, or may be a non-aromatic heterocycle), etc. It is not limited to.

The aromatic ring possessed by the organic compound having the aromatic ring (hereinafter also referred to as “aromatic ring-containing compound”) used as the additive (H _RO ) may be selected from the same group as the aromatic ring possessed by the compound used as the monomer (A1). You can.

The aromatic ring may have one or two or more substituents on the ring constituent atoms, and may not have any substituents. When having a substituent, the substituent includes an alkyl group, alkoxy group, aryloxy group, hydroxyl group, halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), hydroxyalkyl group, hydroxyalkyloxy group, glycidyloxy group, etc. Illustrative, but not limited to these. In the substituent containing a carbon atom, the number of carbon atoms contained in the substituent is, for example, 1 to 10, advantageously 1 to 6, preferably 1 to 4, more preferably 1 to 10. 3, and may be 1 or 2, for example. In some embodiments, the aromatic ring is an aromatic ring that has no substituents on ring constituent atoms or has one or two or more substituents selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom (for example, a bromine atom). You can.

Examples of aromatic ring-containing compounds that can be used as additives (H _RO ) include: compounds that can be used as monomers (A1); An oligomer containing a compound that can be used as a monomer (A1) as a monomer unit; From the compounds that can be used as monomer (A1), a group having an ethylenically unsaturated group (which may be a substituent bonded to a ring-forming atom) or a hydrogen atom or an ethylenically unsaturated group, excluding the portion constituting the ethylenically unsaturated group in the group, Compounds with a structure substituted with a group that it does not have (for example, a hydroxyl group, an amino group, a halogen atom, an alkyl group, an alkoxy group, a hydroxyalkyl group, a hydroxyalkyloxy group, a glycidyloxy group, etc.); etc., and those that do not correspond to the plasticizers disclosed herein may be mentioned, but are not limited to these.

In some embodiments, the additive ( _HRO ) is an organic compound having two or more aromatic rings in one molecule (hereinafter also referred to as a “compound containing multiple aromatic rings”) because a high refractive index effect can easily be obtained. ) can be preferably employed. The compound containing multiple aromatic rings may or may not have a polymerizable functional group such as an ethylenically unsaturated group. In addition, the compound containing multiple aromatic rings may be a polymer or a non-polymer. In addition, the polymer is an oligomer containing a plurality of aromatic ring-containing monomers as monomer units (preferably an oligomer with a molecular weight of approximately 5000 or less, more preferably approximately 1000 or less. For example, a low polymer of about 2 to 5 polymers). You can. The oligomers include, for example: homopolymers of monomers containing multiple aromatic rings; A copolymer of one or more types of aromatic ring-containing monomers; copolymers of one or more types of aromatic ring-containing monomers and other monomers; It may be, etc. The other monomer may be an aromatic ring-containing monomer that does not correspond to a monomer containing multiple aromatic rings, may be a monomer that does not have an aromatic ring, or may be a combination thereof. In the aspect of using an oligomer as an additive ( _HRO ), the oligomer can be obtained by polymerizing the corresponding monomer component by a known method.

Non-limiting examples of compounds containing multiple aromatic rings include compounds having a structure in which two or more non-fused aromatic rings are bonded through a linking group, compounds having a structure in which two or more non-fused aromatic rings are chemically bonded directly (i.e., without passing through other atoms), A compound having a condensed aromatic ring structure, a compound having a fluorene structure, a compound having a dinaphthothiophene structure, a compound having a dibenzothiophene structure, etc. can be mentioned. A compound containing multiple aromatic rings can be used individually or in combination of two or more types.

Examples of organic compounds having a heterocycle (hereinafter also referred to as heterocycle-containing organic compounds) that can be an option for the additive (H _RO ) include thioepoxy compounds and compounds having a triazine ring. Examples of thioepoxy compounds include bis(2,3-epithiopropyl)disulfide and its polymer (refractive index 1.74) described in Japanese Patent No. 3712653. Examples of compounds having a triazine ring include compounds having at least one triazine ring (for example, 3 to 40, preferably 5 to 20) in one molecule. In addition, since the triazine ring has aromaticity, a compound having a triazine ring is also included in the concept of the aromatic ring-containing compound, and a compound having a plurality of triazine rings is also included in the concept of the compound containing a plurality of aromatic rings.

In some embodiments, a compound that does not have an ethylenically unsaturated group can be preferably used as the additive (H _RO ). As a result, deterioration of the adhesive composition due to heat or light (deterioration of leveling properties due to progression of gelation or increase in viscosity) can be suppressed, and storage stability can be improved. Adopting an additive (H _RO ) that does not have an ethylenically unsaturated group means that, in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the additive (H _RO ), dimensional changes or deformations (bending, It is also desirable from the viewpoint of suppressing the occurrence of optical distortion, etc.

The additive (H _RO ) may be used in an appropriate amount within the range in which the effect of the technology disclosed herein is not significantly impaired. In some embodiments, the amount of additive (H _RO ) used (if multiple types of compounds are used, their total amount) per 100 parts by weight of the base polymer (for example, an acrylic polymer) exceeds 0 parts by weight. It is not particularly limited and can be set depending on the purpose. In some embodiments, the amount of additive ( _HRO ) used per 100 parts by weight of the base polymer can be, for example, 80 parts by weight or less to increase the refractive index of the adhesive and suppress deterioration of the adhesive properties and optical properties. From the viewpoint of achieving good balance, it is advantageous to set it to 60 parts by weight or less, and preferably to set it to 45 parts by weight or less. In some embodiments that place more emphasis on adhesive properties or optical properties, the amount of additive ( _HRO ) used per 100 parts by weight of the base polymer may be, for example, 30 parts by weight or less, 10 parts by weight or less, or 3. It may be less than 1 part by weight or less than 1 part by weight. The technology disclosed herein can be preferably implemented using an adhesive that does not contain an additive ( _HRO ). In addition, from the viewpoint of increasing the refractive index of the adhesive, the amount of additive (H _RO ) used per 100 parts by weight of the base polymer can be, for example, 1 part by weight or more, and it is advantageous to set it to 3 parts by weight or more, and 5 It is preferably more than 7 parts by weight, 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, and 20 parts by weight or more.

(Cross-linking agent)

In the technology disclosed herein, the adhesive composition used to form the adhesive may contain a crosslinking agent as needed for purposes such as adjusting the cohesive force of the adhesive. As the crosslinking agent, crosslinking agents known in the adhesive field can be used, such as isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, melamine-based resins, and metal chelate-based crosslinking agents. Among them, isocyanate-based crosslinking agents and epoxy-based crosslinking agents can be preferably employed. Other examples of crosslinking agents include monomers having two or more ethylenically unsaturated groups in one molecule, that is, polyfunctional monomers. The crosslinking agent can be used individually or in combination of two or more types.

As the isocyanate-based crosslinking agent, bifunctional or higher isocyanate compounds can be used, for example, aliphatic polys such as trimethylene diisocyanate, butylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), and dimer acid diisocyanate. isocyanates; Alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), and 1,3-bis(isocyanatomethyl)cyclohexane; Aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate (XDI); Polyisocyanate modified product ( For example, isocyanurate form of HDI, allophanate form of HDI, etc.); etc. can be mentioned. Examples of commercial products include Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N, Takenate D178NL (manufactured by Mitsui Chemicals), Sumidur T80, Sumidur L, and Desmodur N3400 ( (above, manufactured by Sumika Bayer Urethane Corporation), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX, Coronate 2770 (above, manufactured by Tosoh Corporation), brand name Duranate A201H (above, Asahi Kasei Corporation) j), etc. Isocyanate compounds can be used individually or in combination of two or more types. You may use a bifunctional isocyanate compound and a trifunctional or more isocyanate compound together.

As an epoxy-based crosslinking agent, for example, bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6 -hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N', N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, etc. are mentioned. These can be used individually or in combination of two or more types.

Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and neopentyl glycol di( Meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexane Dioldi(meth)acrylate, 1,12-dodecanedioldi(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl (meth)acrylate, divinylbenzene, bisphenol A di(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, butyldiol (meth)acrylate, hexyldiol di(meth)acrylate, etc. I can hear it. Polyfunctional monomers can be used individually or in combination of two or more types.

In some embodiments, a bifunctional crosslinking agent having two crosslinking reactive groups (for example, isocyanate groups) per molecule can be used as at least a part of the crosslinking agent. By using a bifunctional crosslinking agent, it is easy to form a flexible crosslinked structure. Bifunctional crosslinking agents can be used individually or in combination of two or more types. In addition, the bifunctional crosslinking agent may be used in combination with a trifunctional or higher crosslinking agent.

In some embodiments, an acyclic crosslinking agent (also referred to as a chain crosslinking agent) that does not have a ring structure such as an aromatic ring or an aliphatic ring is preferably used as the crosslinking agent. For example, among the above-mentioned isocyanate-based crosslinking agents, it is preferable to use isocyanate-based compounds that do not have ring structures such as aromatic rings and isocyanurate rings. By using an acyclic isocyanate-based compound as a crosslinking agent, it is easy to form a crosslinking agent with high flexibility. Specific examples of the acyclic isocyanate include aliphatic isocyanate compounds (e.g., PDI and HDI) and modified forms of aliphatic isocyanate compounds (e.g., allophanate linkage, biuret linkage, urea linkage, and carbodiyl compound of PDI and HDI). and polyisocyanate modified products modified by mead bonds. Acyclic crosslinking agents can be used individually or in combination of two or more types. In some preferred embodiments, an acyclic bifunctional crosslinking agent may be used as the crosslinking agent.

In some embodiments, a crosslinking agent in which the distance between one crosslinking reactive group (for example, an isocyanate group) and the other crosslinking reactive group in one molecule is relatively long can be used. As a result, a flexible crosslinked structure having a length of a predetermined length or more is formed. For example, in one molecule of the crosslinking agent, a compound in which the number of atoms constituting the linking chain connecting one crosslinking reactive group to another crosslinking reactive group is 10 or more (for example, 12 or more or 14 or more) can be used as the crosslinking agent. The upper limit of the number of atoms forming the linking chain is not particularly limited because it can be prepared by polymerization or the like depending on the purpose, and is, for example, 2000 or less, may be 1000 or less, may be 500 or less, may be 100 or less, and may be 50 or less. It may be 20 or less, or it may be 30 or less, or it may be 20 or less. In addition, the number of atoms in the linking chain connecting the crosslinking reactive groups refers to the number of atoms from one crosslinking reactive group to another crosslinking reactive group in one molecule of the crosslinking agent (when having 3 or more crosslinking reactive groups, the crosslinking reactive group closest to the one crosslinking reactive group refers to the minimum number of atoms required to reach a reactive group. The crosslinking agent having the above linking chain can be used individually or in combination of two or more types. In some preferred embodiments, an acyclic bifunctional crosslinking agent may be used as the crosslinking agent. Examples of commercial products of the crosslinking agent include Coronate 2770 (manufactured by Tosoh Corporation), Takenate D178NL (manufactured by Mitsui Chemicals), Duranate A201H (Asahi Kasei Corporation), and the like.

When using a crosslinking agent, the amount used is not particularly limited, and can be, for example, in the range of 0.001 parts by weight to 5.0 parts by weight based on 100 parts by weight of the base polymer. From the viewpoint of improving the flexibility of the adhesive and its adhesion to the adherend, in some embodiments, the amount of crosslinking agent used per 100 parts by weight of the base polymer is preferably 3.0 parts by weight or less, more preferably 2.0 parts by weight or less. , may be 1.0 parts by weight or less, and may be 0.5 parts by weight or less. In some preferred embodiments, the amount of crosslinking agent used per 100 parts by weight of the base polymer is less than 0.5 parts by weight, may be less than 0.4 parts by weight, may be less than 0.3 parts by weight, may be less than 0.2 parts by weight, and may be 0.1 parts by weight. It may be less than (for example, less than 0.1 part by weight), less than 0.08 part by weight, or less than 0.07 part by weight. In addition, from the viewpoint of appropriately demonstrating the effect of using the crosslinking agent, in some embodiments, the amount of the crosslinking agent used per 100 parts by weight of the base polymer may be, for example, 0.005 parts by weight or more, or 0.01 parts by weight or more, It may be 0.02 part by weight or more, 0.03 part by weight or more, 0.05 part by weight or more, 0.08 part by weight or more, and 0.1 part by weight or more. According to the technology disclosed herein, by using an appropriate amount of crosslinking agent in the above range, an adhesive with good retention of the silicone-based plasticizer (for example, an adhesive with suppressed loss due to volatilization of the silicone-based plasticizer) can be preferably formed. In some embodiments, the amount of crosslinking agent used per 100 parts by weight of the base polymer may be greater than 0.1 part by weight, may be 0.2 part by weight or more, may be 0.3 part by weight or more, or may be 0.4 part by weight or more.

In order to advance the crosslinking reaction more effectively, a crosslinking catalyst may be used. Examples of crosslinking catalysts include metal crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, zirconium tetraacetylacetonate, ferric nasem, butyltin oxide, and dioctyltin dilaurate. . Among them, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferable. The amount of crosslinking catalyst used is not particularly limited. The amount of crosslinking catalyst used per 100 parts by weight of the base polymer can be, for example, in the range of approximately 0.0001 part by weight to 1 part by weight, taking into account the balance between the speed of the crosslinking reaction rate and the length of the pot life of the adhesive composition. , it is desirable to set it in the range of 0.001 parts by weight or more and 0.5 parts by weight or less.

The adhesive composition may contain a compound that generates keto-enol tautomerism as a crosslinking retardant. Thereby, the effect of extending the pot life of the adhesive composition can be realized. For example, in an adhesive composition containing an isocyanate-based crosslinking agent, a compound that generates keto-enol tautomerism can be preferably used. As a compound that generates keto-enol tautomerism, various β-dicarbonyl compounds can be used. For example, β-diketones (acetylacetone, 2,4-hexanedione, etc.) or acetoacetate esters (methyl acetoacetate, ethyl acetoacetate, etc.) can be preferably used. Compounds that generate keto-enol tautomerism can be used individually or in combination of two or more types. The amount of the compound that generates keto-enol tautomerism may be, for example, 0.1 to 20 parts by weight, 0.5 to 10 parts by weight, or 100 parts by weight of the base polymer. It may be more than 5 parts by weight and less than 5 parts by weight.

(Tackifier)

The adhesive disclosed herein may contain a tackifier. As a tackifier, rosin-based tackifying resin, terpene-based tackifying resin, phenol-based tackifying resin, hydrocarbon-based tackifying resin, ketone-based tackifying resin, polyamide-based tackifying resin, epoxy-based tackifying resin, and elastomer-based tackifier. Known tackifying resins such as tackifying resin can be used. These can be used individually or in combination of two or more types. The amount of tackifying resin used is not particularly limited and can be set to achieve appropriate adhesive performance depending on the purpose or use. In some embodiments, from the viewpoint of refractive index and transparency, the amount of tackifier used per 100 parts by weight of the base polymer is appropriately 30 parts by weight or less, preferably 10 parts by weight or less, and 5 parts by weight or less. It is more preferable to set it to 10 or less. The technology disclosed herein can be preferably implemented without using a tackifier.

(High refractive index particles)

The adhesive disclosed herein may contain high refractive index particles as an optional component. Here, high refractive index particles mean particles that can increase the refractive index of the adhesive by including them in the adhesive. Hereinafter, high refractive index particles may be expressed as “particle P _HRI ”. HRI stands for high refractive index. The type of particle P _HRI is not particularly limited, and one or two or more types of materials that can improve the refractive index of the adhesive are selected from metal particles, metal compound particles, organic particles, and organic-inorganic composite particles. , can be used. As the particles P _HRI , those that can improve the refractive index of the adhesive from inorganic oxides (for example, metal oxides) can be preferably used. Suitable examples of materials constituting particle P _HRI include titania (titanium oxide, TiO ₂ ), zirconia (zirconium oxide, ZrO ₂ ), aluminum oxide, zinc oxide, tin oxide, copper oxide, barium titanate, and niobium oxide (Nb _{2 )} . O ₅ , etc.) and inorganic oxides (specifically, metal oxides) can be mentioned. Particles made of these inorganic oxides (for example, metal oxides) can be used individually or in combination of two or more types. The average particle diameter (referring to the 50% volume average particle diameter based on laser scattering/diffraction method) of the particles P _HRI is not particularly limited and can be selected from the range of approximately 1 nm to 1000 nm, for example.

The content of particles P _HRI in the adhesive can be used in an appropriate amount within a range that does not impair the effect of the technology disclosed here. Additionally, the content of the particles P _HRI may vary depending on the target refractive index. For example, the content of the particles P _HRI can be appropriately set to have a refractive index of a predetermined or higher level, taking into account required adhesive properties, etc. In some embodiments, the content of particles P _HRI in the adhesive may be, for example, less than 10% by weight, less than 1% by weight, or less than 0.1% by weight. The technology disclosed herein can be practiced in an embodiment in which the adhesive does not substantially contain particles P _HRI .

(Leveling system)

In some embodiments, the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer is provided for the purpose of improving the appearance of the pressure-sensitive adhesive layer formed from the composition (for example, improving uniformity of thickness) or improving the coatability of the pressure-sensitive adhesive composition. , a leveling agent may be contained as needed. Non-limiting examples of the leveling agent include an acrylic leveling agent, a fluorine-based leveling agent, and a silicone-based leveling agent. The leveling agent can be used, for example, by selecting an appropriate leveling agent from commercially available leveling agents and using a conventional method.

(optional plasticizer)

In addition to the silicone-based plasticizer described above, the adhesive disclosed herein may or may not contain other plasticizers as needed. When such a plasticizer (hereinafter also referred to as “optional plasticizer”) is used as an optional component, the optional plasticizer can be selected and used as an appropriate one depending on the purpose, for example from the examples given below.

As the optional plasticizer, an unsaturated organic compound that is a non-silicon compound (i.e., a compound that does not have a siloxane bond) and has two or more double bond-containing rings (preferably an aromatic ring, for example, a benzene ring with or without a substituent). , that is, compounds having two or more double bond-containing rings in one molecule are exemplified. The compound may be an ethylene glycol-based compound having two or more double bond-containing rings in one molecule, or a compound having a structure in which two or more non-fused double bond-containing rings (for example, benzene rings) are bonded through a linking group. From the viewpoint of exerting a plasticizing effect, the number of double bond-containing rings in the optional plasticizer is preferably 6 or less, may be 4 or less, and may be 3 or less.

Examples of ethylene glycol-based compounds having two or more double bond-containing rings in one molecule include those having a structure in which two or more non-fused double bond-containing rings are bonded through an oxyethylene unit (i.e. -(C ₂ H ₄ O)- unit) Compounds may be mentioned. The number of oxyethylene units in the ethylene glycol-based compound is, for example, 1 or more, preferably 2 or more, preferably 3 or more, more preferably 4 or more (for example, 5 or more). In addition, the upper limit of the number of oxyethylene units is, for example, 10 or less, may be 8 or less, and may be 6 or less. The ethylene glycol-based compound, for example, has two or more non-fused double bond-containing rings (preferably aromatic rings) having a repeating number of about 2 to 10 (preferably about 3 to 6) oxyethylene units and an ester bond. It may be a compound having a structure connected by . Preferred examples from the viewpoint of plasticizing effect include diethylene glycol dibenzoate, triethylene glycol dibenzoate, and polyethylene glycol dibenzoate. From the viewpoint of low volatility, triethylene glycol dibenzoate or polyethylene glycol dibenzoate is more preferable.

In the compound having a structure in which two or more non-fused double bond-containing rings are bonded through a linking group, the linking group is, for example, an oxy group (-O-), a thioxy group (-S-), an oxyalkylene group (e.g. For example -O-(CH ₂ ) _n -group, where n is 1 to 3, preferably 1), straight chain alkylene group (i.e. -(CH ₂ ) _n -group, where n is 1 to 6, preferably may be 1 to 3), etc. Specific examples of the above compounds include phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), phenoxybenzyl alcohol, oxybis[(alkoxyalkyl)benzene] (e.g., 4,4'-oxybis[(methoxymethyl)benzene]) and the like.

Other examples of materials that can be used as an optional plasticizer include liquid rosins such as liquid rosin ester, and liquid camphene phenol. As an optional plasticizer, one or two or more types of known plasticizers (e.g., plasticizers such as phthalate ester plasticizer, terephthalate ester, adipic acid ester, adipic acid polyester, and benzoic acid glycol ester) may be used. do.

The molecular weight of the optional plasticizer is not particularly limited, but one having a molecular weight smaller than that of the base polymer (for example, an acrylic polymer) is usually used. From the viewpoint of facilitating the plasticization effect, the molecular weight of the optional plasticizer is suitably less than 10,000, preferably less than 5,000, and may be less than 3,000. In some embodiments, the molecular weight of the optional plasticizer is preferably 2000 or less, more preferably 1200 or less, even more preferably 900 or less, and may be 600 or less, 500 or less, 400 or less, or 300 or less. It may be less than or equal to 250 (for example, 220 or less). The fact that the molecular weight of the optional plasticizer is not too large can be advantageous from the viewpoint of improving compatibility within the adhesive layer. In addition, the molecular weight of the optional plasticizer is suitably 100 or more, preferably 130 or more, more preferably 150 or more, may be 170 or more, may be 200 or more, and may be 220 or more from the viewpoint of making it easy to exert the plasticizing effect. It can be 250 or more. It is desirable that the molecular weight of the optional plasticizer is not too low from the viewpoint of heat resistance performance of the adhesive sheet and suppression of contamination of the adherend. In some embodiments, the molecular weight of the optional plasticizer is suitably 315 or more, and may be 350 or more. Since a plasticizer with a large molecular weight is difficult to vaporize, an adhesive that can exhibit stable properties can easily be obtained by using an optional plasticizer with a large molecular weight in the adhesive. Additionally, any plasticizer with a large molecular weight has difficulty moving within the adhesive. Therefore, for example, it is difficult for any plasticizer to migrate to the surface of the adhesive and cause events that affect the adhesive properties. The molecular weight of the optional plasticizer may be 400 or more, 450 or more, 500 or more, or 530 or more.

Additionally, as the molecular weight of the optional plasticizer, the molecular weight calculated based on the chemical structure is used. If a nominal value of molecular weight is provided by a manufacturer, etc., that nominal value can be adopted.

From the viewpoint of plasticizing effect and compatibility, the optional plasticizer is suitably a compound that is liquid at at least 30°C, preferably a compound that is liquid at 25°C, and is a compound that is liquid at 23°C (for example, 20°C). It is more preferable. In addition, the optional plasticizer is used from the viewpoint of storage stability of the adhesive and the adhesive sheet containing the adhesive (e.g., adhesive layer), changes in elastic modulus due to reaction of ethylenically unsaturated groups, dimensional changes and deformations (bending, waviness). etc.), from the viewpoint of suppressing the occurrence of optical distortion, etc., it is preferable not to have an ethylenically unsaturated group.

In some embodiments, as an optional plasticizer, a high refractive index plasticizer with a refractive index of approximately 1.50 or more can be preferably used from the viewpoint of providing flexibility while suppressing a decrease in the refractive index of the adhesive. The refractive index of the optional plasticizer is preferably approximately 1.51 or greater, more preferably approximately 1.53 or greater, further preferably approximately 1.55 or greater, may be approximately 1.56 or greater, may be approximately 1.58 or greater, may be approximately 1.60 or greater, and may be approximately 1.62 or greater. It can be more than that. In some embodiments, from the viewpoint of ease of preparation of the adhesive composition, compatibility in the adhesive, etc., the refractive index of the optional plasticizer is suitably 2.50 or less, advantageously 2.00 or less, may be 1.90 or less, and may be 1.80 or less. It can be 1.70 or less.

In addition, the refractive index of the optional plasticizer, like the refractive index of the monomer, is measured using an Abbe refractometer under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. If the nominal value of the refractive index at 25°C is provided by the manufacturer, etc., the nominal value can be adopted.

Optional plasticizers may be used in appropriate amounts within the range in which the effects of the technology disclosed herein are not significantly impaired. The amount of optional plasticizer used per 100 parts by weight of the base polymer can be, for example, 0.01 parts by weight or more, 0.1 parts by weight or more, 1 part by weight or more, 5 parts by weight or more, or 10 parts by weight or more, and may be 80 parts by weight or more. Hereinafter, it can be 60 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, or 20 parts by weight or less. In some embodiments, from the viewpoint of stability of the plasticizing effect, it is appropriate that the amount of optional plasticizer used is less than 15 parts by weight, preferably less than 10 parts by weight, and 5 parts by weight per 100 parts by weight of the base polymer. It is more preferable to set it to less than (for example, less than 3 parts by weight or less than 1 part by weight).

In addition, from the viewpoint of making better use of the advantages of using the silicone-based plasticizer disclosed herein, in some embodiments, the amount of plasticizers other than the silicone-based plasticizer used is less than 50% by weight of the total plasticizer used in the adhesive. It is suitable, preferably less than 30% by weight, more preferably less than 10% by weight, even more preferably less than 3% by weight, especially preferably less than 1% by weight. The technology disclosed herein can be preferably implemented using an adhesive that substantially does not contain plasticizers other than the silicone-based plasticizer.

(Other additives)

In the technology disclosed herein, the adhesive composition used to form the adhesive includes softeners, colorants (dyes, pigments, etc.), fillers, antistatic agents, anti-aging agents, and ultraviolet rays, to the extent that the effect of the present invention is not significantly impaired. Known additives that can be used in the adhesive composition, such as absorbents, antioxidants, light stabilizers, and preservatives, may be included as needed. Regarding these various additives, conventionally known ones can be used by conventional methods, and since they do not particularly characterize the present invention, detailed descriptions are omitted.

Although not particularly limited, the effects achieved by the technology disclosed herein can be preferably achieved by using an adhesive containing the above-described base polymer (typically an acrylic polymer) and a silicone-based plasticizer. The technology disclosed herein can be preferably implemented in an aspect that uses an adhesive mainly composed of the base polymer and the silicone-based plasticizer. Accordingly, in some preferred embodiments, a composition in which the content of components other than the base polymer and the silicone-based plasticizer (other components) is limited can be adopted. For example, the total amount of the base polymer and the silicone-based plasticizer in the adhesive can be 75% by weight or more (for example, 75% by weight or more and 100% by weight or less or less than 100% by weight), and 85% by weight. It may be % or more, may be 90% by weight or more, may be 95% by weight or more, may be 98% by weight or more, and may be 99% by weight or more (for example, exceeding 99% by weight). Limiting the use of components other than the base polymer and the silicone-based plasticizer may be advantageous from the viewpoint of performance stability of the adhesive.

(Formation of adhesive)

The adhesive disclosed herein can be formed using an adhesive composition containing a silicone-based plasticizer (typically, an adhesive composition containing at least a base polymer and a silicone-based plasticizer). The form of the adhesive composition is not particularly limited, and for example, a solvent-based adhesive composition containing an adhesive-forming component in an organic solvent is cured (viscoelasticized) by active energy rays such as ultraviolet rays or radiation to form an adhesive. Various forms such as active energy ray-curable adhesive compositions prepared to do so, water-dispersible adhesive compositions in which the adhesive-forming ingredients are dispersed in water, and hot melt-type adhesive compositions that are applied in a heated and molten state and form an adhesive when cooled to around room temperature. It can be. Although not particularly limited, the silicone-based plasticizer disclosed herein is preferably used in a solvent-based pressure-sensitive adhesive composition and an adhesive formed from the solvent-based pressure-sensitive adhesive composition from the viewpoint of ease of mixing, etc., to achieve the effect of using the silicone-based plasticizer. It can be performed appropriately. The solvent-based adhesive composition can typically be dried (preferably, further cross-linked) to form an adhesive. The active energy ray-curable adhesive composition is typically formed by irradiating active energy rays to advance a polymerization reaction and/or a crosslinking reaction. If it is necessary to dry the active energy ray-curable adhesive composition, the active energy ray may be irradiated after drying.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein can be formed by applying (for example, applying) a pressure-sensitive adhesive composition to a suitable surface and then curing the composition. Application of the adhesive composition can be performed using a common coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, or spray coater.

The thickness of the adhesive (specifically, the thickness of the adhesive film (adhesive film), for example, the thickness of the adhesive layer constituting the adhesive sheet) is not particularly limited and can be, for example, 3 μm or more. In some embodiments, the thickness of the adhesive layer is suitably, for example, 5 μm or more, may be 10 μm or more, may be 15 μm or more, may be 20 μm or more, may be 30 μm or more, or may be 50 μm or more. It may be 70 μm or more or 85 μm or more. As the thickness of the adhesive layer increases, the adhesive strength tends to increase. In addition, in some embodiments, the thickness of the adhesive layer may be, for example, 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 120 μm or less. In some preferred embodiments, the thickness of the adhesive layer is 100 μm or less, more preferably 75 μm or less, further preferably 70 μm or less, and may be 50 μm or less, or 30 μm or less. The fact that the thickness of the adhesive layer is not too large can be advantageous from the viewpoint of reducing the thickness of the adhesive sheet, etc. Additionally, a thin adhesive layer tends to have excellent followability to the adherend. The technology disclosed herein is preferably carried out in such a way that the thickness of the adhesive layer ranges from 3 ㎛ to 200 ㎛ (more preferably 5 ㎛ to 100 ㎛, more preferably 5 ㎛ to 75 ㎛). It can be. Additionally, in the case of a pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on the first and second sides of the substrate, the thickness of the pressure-sensitive adhesive layer described above can be applied to at least the thickness of the first pressure-sensitive adhesive layer. The thickness of the second adhesive layer can also be selected from the same range. Additionally, in the case of an inorganic adhesive sheet, the thickness of the adhesive sheet matches the thickness of the adhesive layer.

(refractive index)

The refractive index of the adhesive disclosed herein is not particularly limited and can be set depending on the purpose (for example, taking into account the refractive index of the adherend). The refractive index of the adhesive disclosed herein may be, for example, about 1.300 to 1.900 or about 1.350 to 1.800 (preferably about 1.450 to 1.800). In some embodiments, the refractive index of the adhesive is higher than that of conventional general acrylic adhesives. According to the technology disclosed herein, an adhesive having a refractive index of, for example, 1.480 or more (preferably 1.490 or more, more preferably 1.500 or more), an adhesive composition capable of forming the adhesive, and an adhesive sheet containing the adhesive. may be provided. The refractive index of the adhesive may be 1.510 or more, 1.520 or more, 1.530 or more, 1.540 or more, and 1.550 or more. In some embodiments, the refractive index of the adhesive is suitably 1.560 or more (for example, more than 1.570). In some preferred embodiments, the refractive index of the adhesive may be 1.575 or more, 1.580 or more, 1.585 or more, 1.590 or more, or 1.595 or more. According to the adhesive having such a refractive index, light reflection at the interface with the adherend can be appropriately suppressed in a usage mode where the adhesive is attached to a material with a high refractive index. The preferable upper limit of the refractive index of the adhesive may differ depending on the refractive index of the adherend, so it is not limited to a specific range. For example, it may be 1.700 or less, 1.670 or less, 1.650 or less, 1.620 or less, and 1.600 or less. It's okay. In some embodiments where flexibility or low-temperature properties are more important, the refractive index of the adhesive may be, for example, less than 1.550, less than 1.530, or less than 1.510.

The refractive index of the adhesive can be adjusted, for example, by the composition of the adhesive. For example, an adhesive showing a predetermined refractive index can be prepared by selecting the type of plasticizer or, in the case of an acrylic adhesive, the amount of monomer (A1) used in the monomer component.

In addition, in this specification, the refractive index of the adhesive refers to the refractive index of the surface (adhesive surface) of the adhesive. The refractive index of the adhesive can be measured using a commercially available refractive index measuring device (Abbe refractometer) under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. As an Abbe refractometer, for example, model "DR-M4" manufactured by ATAGO or its equivalent is used. As a measurement sample, an adhesive layer made of the adhesive to be evaluated can be used. Specifically, the refractive index of the adhesive can be measured by the method described in the Examples described later.

(Haze value)

In some embodiments, the haze value of the adhesive layer (for example, the adhesive layer constituting the adhesive sheet) may be, for example, 10% or less, or less than 10%, and in some embodiments, it is appropriate to be 5.0% or less. It is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and especially preferably less than 1.0% (for example, 0.9% or less). Such a pressure-sensitive adhesive sheet having a highly transparent pressure-sensitive adhesive layer can be used for applications requiring high light transparency (for example, optical applications), with or without a base material, and for good adhesion to adherends through the pressure-sensitive adhesive sheet. It can be preferably applied to applications requiring recognizable performance. The lower limit of the haze value of the adhesive layer is not particularly limited, and from the viewpoint of improving transparency, a smaller haze value is more preferable. On the other hand, in some embodiments, taking flexibility and adhesive properties into consideration, the haze value may be, for example, 0.05% or more, or 0.10% or more. These haze values for the adhesive layer are preferably applied to the haze value of the adhesive sheet when the technology disclosed herein is implemented in the form of an inorganic adhesive sheet (typically, an adhesive sheet made of an adhesive layer). You can.

Here, “haze value” refers to the ratio of diffuse transmitted light to the total transmitted light when visible light is irradiated to the measurement object. Also called cloudiness. The haze value can be expressed by the following equation.

Th(%)=Td/Tt×100

In the above formula, Th is the haze value (%), Td is the scattered light transmittance, and Tt is the total light transmittance. Haze value can be measured according to the method described in the Examples described later. The haze value of the adhesive layer can be adjusted, for example, by selecting the composition or thickness of the adhesive layer.

(Storage modulus G')

The storage modulus G' (23°C) at 23°C of the adhesive disclosed herein is not particularly limited, and is suitably, for example, less than 1000 kPa, preferably less than 500 kPa, more preferably less than 300 kPa, and 200 kPa. It may be less than 100 kPa, or less than 50 kPa. The adhesive with a limited storage modulus G' (23°C) as described above has good flexibility at normal use temperatures, such as a room temperature environment. The lower limit of the storage modulus G' (23°C) is not particularly limited. For example, it is preferably 0.1 kPa or more, preferably 0.5 kPa or more, may be 1.0 kPa or more, may be 3.0 kPa or more, or may be 5.0 kPa or more. , may be 10 kPa or more. The adhesive having the storage elastic modulus G' (23°C) is preferred because it tends to have appropriate cohesion at normal use temperatures and excellent heat resistance. The above description regarding the top and bottom of the storage modulus G' (23°C) is after applying the wet heat treatment described in the Examples described later to the adhesive disclosed herein (hereinafter sometimes abbreviated as “after wet heat”). ) can also be applied to the top and bottom of the storage modulus G' (23°C). An adhesive whose storage modulus G' (23°C) after wet heat treatment is within the above range is preferable because it exhibits the above-mentioned properties even over time or after storage in a moist heat environment.

In addition, in the following, in order to distinguish it from the storage modulus G'(23°C) after moist heat, the storage modulus G'(23°C) measured for an adhesive that has not been subjected to wet heat treatment is referred to as the "initial storage modulus." there is. The same applies to the storage modulus G' (0°C) described below.

The storage modulus G'(0°C) of the adhesive disclosed herein is not particularly limited and may be, for example, in the range of 5 kPa to 10000 kPa. In some embodiments, the storage modulus G' (0°C) of the adhesive is suitably 8000 kPa or less, advantageously 6000 kPa or less, preferably 5000 kPa or less, more preferably 4000 or less, 3000 kPa or less, and may be 2500 kPa or less. It may be less than or equal to 2000 kPa. According to the above adhesive, the range of storage elastic modulus G' (0°C) is suppressed to a low range, and therefore the desired flexibility can be exhibited even in a low temperature range. In some preferred embodiments, the storage modulus G' (0°C) of the adhesive may be, for example, 1500 kPa or less, 1000 kPa or less, 900 kPa or less, 800 kPa or less, 700 kPa or less, or 600 kPa or less. It may be 500 kPa or less, 400 kPa or less, 300 kPa or less, 200 kPa or less, 100 kPa or less, 70 kPa or less, or 50 kPa or less. In addition, the storage modulus G' (0°C) is preferably 10 kPa or more, more preferably 20 kPa or more, and may be 30 kPa or more, or 40 kPa or more. The above description regarding the upper and lower ends of the storage elastic modulus G' (0°C) can also be applied to the upper and lower ends of the storage elastic modulus G' (0°C) after wet heat of the adhesive disclosed herein. An adhesive whose storage modulus G' (0°C) after wet heat treatment is within the above range is preferable because it exhibits the above properties even over time or after storage in a moist heat environment.

With respect to the initial storage modulus G'(23°C) of the adhesive at 23°C, the rate of change (rate of increase) of the storage modulus G'(23°C) after moist heat at 23°C may be, for example, 30% or less. 25 % or less is appropriate, 20% or less is advantageous, 15% or less is preferable, 10% or less is more preferable, and 8.5% or less is more preferable. The fact that the rate of change (i.e., the rate of change in storage elastic modulus due to exposure to a moist heat environment) is smaller means that the plasticization effect of the adhesive at 23°C is better maintained (the stability of the plasticization effect) with respect to storage under moist heat. means higher). In some embodiments, the rate of change may be 8.0% or less, 7.5% or less, 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, or 5.0% or less. The rate of change may be 0% or more and may be greater than 0%. From the viewpoint of facilitating compatibility with other properties such as adhesive properties and refractive index, in some embodiments, the rate of change may be, for example, 0.1% or more, 0.2% or more, or 0.5% or more, It may be 0.7% or more, 1.0% or more, 1.5% or more, 2.0% or more, 3.0% or more, 4.0% or more, or 5.0% or more.

In addition, the rate of change of the storage elastic modulus G' (23°C) after wet heat with respect to the initial storage elastic modulus G' (23°C) is X% or less, assuming that the initial storage elastic modulus G' (23°C) is 100% and stored after wet heat. It means that the elastic modulus G' (23°C) is (100+X)% or less. The same applies to the rate of change of the storage elastic modulus G'(0°C) after moist heat with respect to the initial storage modulus G'(0°C) described below.

With respect to the initial storage modulus G'(0°C) of the adhesive at 0°C, the rate of change (rate of increase) of the storage modulus G'(0°C) after moist heat at 0°C is suitably, for example, 25% or less, and is 20% or less. It is advantageous that it is % or less, it is preferable that it is 15% or less, it is more preferable that it is 10% or less, and it is more preferable that it is 8.5% or less. A smaller change rate means that the plasticizing effect of the adhesive at low temperature is better maintained (higher stability of the plasticizing effect) when stored under moist heat. In some embodiments, the rate of change may be 8.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 4.0% or less, 3.0 or less, 2.0% or less, 1.5% or less, or It may be 1.0% or less, and may be less than 1.0% (for example, less than 0.7%). The rate of change may be 0% or more and may be greater than 0%. From the viewpoint of facilitating compatibility with other properties such as adhesive properties and refractive index, in some embodiments, the rate of change may be 0.1% or more, 0.2% or more, 0.5% or more, or 0.7% or more. It may be 1.0% or more.

In the adhesive disclosed herein, the ratio of the initial storage modulus G'(0°C) to the initial storage modulus G'(23°C) (G'(0°C)/G'(23°C)) is, for example, It is preferably within the range of 1 to 1000. According to an adhesive that satisfies the above properties, the change in elastic modulus is suppressed over a wide temperature range from 0° C. to room temperature, so it is easy to exhibit stable properties (flexibility, etc.) with respect to temperature changes. The ratio (G'(0°C)/G'(23°C)) is suitably 300 or less (e.g., 200 or less), preferably 100 or less, more preferably 60 or less, and may be 40 or less. , may be 30 or less, may be 20 or less, and may be 10 or less. The lower limit of the ratio (G'(0°C)/G'(23°C)) is typically greater than 1.0, and may be 1.5 or more, 3.0 or more, or 5.0 or more.

The storage elastic modulus G' of the adhesive at each temperature at the initial stage and after wet heat can be measured by the dynamic viscoelasticity measurement method described in the Examples described later, and from the results, the change rate (rise rate) of the storage elastic modulus and the storage elastic modulus ratio can be determined. It can be calculated. The storage elastic modulus G', change rate, and storage elastic modulus ratio of the adhesive are, for example, selection of the composition of the monomer component constituting the base polymer, setting of Mw of the base polymer, selection of plasticizer type and amount used, presence or absence of crosslinking agent, and type. It can be adjusted by selection of usage amount, presence or absence of additives, selection of type and usage amount, etc.

(23℃ storage modulus of control adhesive)

In some embodiments of the adhesive disclosed herein, the adhesive is initially stored at 23°C as an adhesive of the same composition (hereinafter also referred to as “control adhesive”) except that it does not contain the silicone-based plasticizer disclosed herein. The elastic modulus G' (23°C) may be, for example, 1 kPa or more, 10 kPa or more, 20 kPa or more, or 30 kPa or more. From the viewpoint of better demonstrating the effect of using the silicone-based plasticizer disclosed herein, the initial storage modulus G' (23°C) of the control adhesive is suitably 50 kPa or more, preferably 100 kPa or more, and may be 150 kPa or more. , may be 200 kPa or more. In this way, the control pressure-sensitive adhesive having an initial storage modulus G' (23° C.) of a predetermined or higher level is suitable as an object for imparting a stable plasticizing effect by use of the silicone-based plasticizer disclosed herein. In some preferred embodiments, the initial storage modulus G' (23°C) of the control adhesive is suitably 250 kPa or more, advantageously 300 kPa or more (e.g., more than 300 kPa), may be 320 kPa or more, or 340 kPa or more. It may be 350 kPa or more. The upper limit of the initial storage modulus G' (23°C) of the control adhesive is not particularly limited, and may be, for example, 2000 kPa or less, 1500 kPa or less, 1000 kPa or less, 800 kPa or less, 600 kPa or less, or 400 kPa or less. The reason that the initial storage modulus G' (23°C) of the control adhesive is not too high is that the adhesive disclosed herein (i.e., an adhesive with a composition of adding a silicone-based plasticizer to the control adhesive) achieves a good balance between flexibility and other properties. From this point of view, it is desirable.

For any of the adhesives do. For example, in the examples described below, Example 19 corresponds to the control adhesives of Examples 1, 2, and 17, and Examples 20 and 21 correspond to the control adhesives of Examples 15 and 16, respectively.

<Adhesive sheet>

According to this specification, an adhesive sheet having any of the adhesives disclosed herein (which may be an adhesive formed from any of the adhesive compositions disclosed herein, for example, a cured product of the adhesive composition), preferably in the form of an adhesive layer. provided.

The pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet provided with a base material having the pressure-sensitive adhesive layer on one or both sides of a non-peelable base material (support base material), and the pressure-sensitive adhesive layer may be an adhesive sheet of an inorganic material, such as a form in which the pressure-sensitive adhesive layer is held by a release liner. A sheet (i.e., an adhesive sheet without a non-removable base material, typically consisting of an adhesive layer) may be used. The concept of adhesive sheet referred to herein may include what is referred to as adhesive tape, adhesive label, adhesive film, etc. The adhesive sheet disclosed here may be in roll shape or in sheet form. Alternatively, it may be an adhesive sheet processed into more diverse shapes.

A structural example of a double-sided adhesive type inorganic adhesive sheet (baseless double-sided adhesive sheet) is shown in Figs. 1 and 2. In the adhesive sheet 1 shown in FIG. 1, both surfaces 21A and 21B of the inorganic adhesive layer 21 are protected by release liners 31 and 32, respectively, with at least the adhesive layer side being the release surface. It has a composition. The adhesive sheet 2 shown in FIG. 2 has a configuration in which one surface (adhesive surface) 21A of the inorganic adhesive layer 21 is protected by a release liner 31 on both sides of which are release surfaces. When this is wound, the other surface (adhesive surface) 21B of the adhesive layer 21 comes into contact with the back surface of the release liner 31, and the other surface 21B is also protected by the release liner 31. It can be done with the configured configuration. The technology disclosed herein is preferably implemented in the form of an inorganic adhesive sheet made of an adhesive layer from the viewpoint of flexibility (for example, flexibility that can follow an adherend that is repeatedly bent). The above-mentioned inorganic adhesive sheet is preferable, for example, from the viewpoint of reducing the thickness of the adhesive sheet and from the viewpoint of increasing the transparency of the adhesive sheet.

The adhesive sheet disclosed herein may have, for example, a cross-sectional structure schematically shown in FIG. 3. The adhesive sheet 3 shown in FIG. 3 includes a support substrate 10 and a first adhesive layer 21 supported on the first surface 10A and the second surface 10B of the support substrate 10, respectively. and a second adhesive layer (22). The first surface 10A and the second surface 10B are both non-peelable surfaces (non-peel surfaces). The adhesive sheet 3 attaches the surface (first adhesive surface) 21A of the first adhesive layer 21 and the surface (second adhesive surface) 22A of the second adhesive layer 22 to the adherend, respectively. It is used. That is, the adhesive sheet 3 is configured as a double-sided adhesive sheet (double-sided adhesive adhesive sheet). The adhesive sheet 3 before use has release liners 31 and 32 in which the first adhesive surface 21A and the second adhesive surface 22A are peelable surfaces (release surfaces) at least on the adhesive surface side. Each has a protected configuration. Alternatively, the release liner 32 may be omitted, and a release liner 31 having both sides as release surfaces may be used, and the adhesive sheet 3 may be wound to form a second adhesive surface 22A of the release liner 31. By contacting the back surface, the second adhesive surface 22A may also be protected by the release liner 31.

The technology disclosed herein is preferably implemented in the form of a double-sided adhesive sheet provided with the above-described inorganic material or base material for fixing or joining members (for example, optical members). Alternatively, although not specifically shown, the adhesive sheet disclosed herein may be in the form of a single-sided adhesive sheet provided with a base material having an adhesive layer on only one side of a non-removable base material (support base material). As an example of the form of the single-sided pressure-sensitive adhesive sheet, there is a form that does not have either the first pressure-sensitive adhesive layer 21 or the second pressure-sensitive adhesive layer 22 in the structure shown in FIG. 3.

In some embodiments, the haze value of the adhesive sheet may be, for example, 5.0% or less, preferably 3.0% or less, more preferably 2.0% or less, further preferably 1.0% or less, and less than 1.0% ( For example, 0.9% or less) is particularly preferable. Such highly transparent adhesive sheets can be suitably applied to applications that require high light transparency (for example, optical applications) or to applications that require the performance of good visibility of the adherend through the adhesive sheet. . The lower limit of the haze value of the adhesive sheet is not particularly limited, and from the viewpoint of improving transparency, a smaller haze value is more preferable. On the other hand, in some embodiments, taking the refractive index and adhesive properties into consideration, the haze value may be, for example, 0.05% or more, or 0.10% or more. The haze value of the adhesive sheet can be measured by a method similar to the measurement of the haze value of the adhesive layer. The above-mentioned haze value of the adhesive sheet can be obtained by the composition of the adhesive layer described above, etc., or, in the case of a structure having a substrate, by selection of the substrate species and substrate thickness.

In some embodiments, the total light transmittance of the adhesive sheet is preferably 85.0% or more (for example, 88.0% or more, 89.0% or more, or 90.0% or more). Such highly transparent adhesive sheets can be suitably applied to applications that require high light transparency (for example, optical applications) or to applications that require the performance of good visibility of the adherend through the adhesive sheet. . For practical purposes, the upper limit of the total light transmittance may be approximately 98% or less, approximately 96% or less, or approximately 95% or less. In some embodiments, taking into account the refractive index and adhesive properties, the total light transmittance of the adhesive sheet may be approximately 94% or less, approximately 93% or less, or approximately 92% or less. The total light transmittance of the adhesive sheet can be measured by a method similar to the measurement of the total light transmittance of the adhesive layer. The total light transmittance of the adhesive sheet can be obtained by the composition of the adhesive layer described above, etc., or, in the case of a structure having a substrate, by selecting the substrate species or substrate thickness.

(Peel Strength)

The peeling strength of the adhesive sheet from the glass plate is not particularly limited. In some embodiments, the adhesive sheet has a peeling strength from a glass plate of, for example, 0.1 N/25 mm or more, and may be 0.5 N/25 mm or more. In some preferred embodiments, the peeling strength for the glass plate is 1.0 N/25 mm or more, more preferably 1.5 N/25 mm or more, further preferably 2.0 N/25 mm or more, and 3.0 N/25 mm or more. It may be 25 mm or more, 5.0 N/25 mm or more, or 10 N/25 mm or more. In this way, an adhesive sheet having a peeling strength from a glass plate of a predetermined value or more is suitable for, for example, joining or fixing glass members. The upper limit of the peel strength is not particularly limited, and may be, for example, 30 N/25 mm or less, 25 N/25 mm or less, or 20 N/25 mm or less. In addition, in the case where the adhesive sheet is an inorganic adhesive sheet consisting only of an adhesive layer, the peeling strength to the glass plate can be said to be the peeling strength of the adhesive to the glass plate.

Here, the peel strength is determined by pressing an alkali glass plate as an adherend, leaving it in an environment of 23° C. and 50% RH for 30 minutes, and then measuring the peel strength under the conditions of a peel angle of 180 degrees and a tensile speed of 300 mm/min. do. In the measurement, if necessary, the adhesive sheet to be measured can be reinforced by attaching an appropriate backing material (for example, a polyethylene terephthalate (PET) film with a thickness of about 25 μm to about 50 μm).

(Thickness of adhesive sheet)

The thickness of the adhesive sheet disclosed herein (a baseless adhesive sheet or an adhesive sheet with a base material) may be, for example, 1000 μm or less, 350 μm or less, 200 μm or less, or 120 μm or less. It may be 75㎛ or less, 50㎛ or less, or 30㎛ or less. In addition, from the viewpoint of handling, etc., the thickness of the adhesive sheet may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 25 μm or more, 80 μm or more, or 130 μm. It can be more than that.

In addition, the thickness of the adhesive sheet refers to the thickness of the portion attached to the adherend. For example, in the adhesive sheet 3 of the configuration shown in FIG. 3, the thickness refers to the thickness from the first adhesive surface 21A to the second adhesive surface 22A, and does not include the thickness of the release liners 31 and 32. No.

<Supporting description>

The pressure-sensitive adhesive sheet according to some embodiments may be in the form of a pressure-sensitive adhesive sheet provided with a base material including an adhesive layer on one or both sides of the support base material. The material of the support base material is not particularly limited and can be appropriately selected depending on the purpose of use or usage mode of the adhesive sheet. Non-limiting examples of substrates that can be used include polyolefin films mainly containing polyolefins such as polypropylene (PP) and ethylene-propylene copolymer, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene film. Plastic films such as polyester films containing polyester such as phthalate (PEN) as a main ingredient, and polyvinyl chloride films containing polyvinyl chloride as a main ingredient; Foam sheets made of foam such as polyurethane foam, polyethylene (PE) foam, and polychloroprene foam; Woven fabrics and non-woven fabrics made by spinning alone or in a blend of various fibrous materials (which may be natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate); Paper such as Japanese paper, fine paper, kraft paper, and crepe paper; Metal foil such as aluminum foil and copper foil; etc. can be mentioned. It may be a base material composed of a combination of these. Examples of such composite substrates include, for example, a substrate having a structure in which metal foil and the above plastic film are laminated, a plastic substrate reinforced with inorganic fibers such as glass cloth, etc.

In some embodiments, various film substrates can be preferably used. The film substrate may be a porous substrate such as a foam film or a non-woven fabric sheet, may be a non-porous substrate, or may be a substrate having a structure in which a porous layer and a non-porous layer are laminated. In some embodiments, the film substrate may preferably include a resin film capable of independently maintaining its shape (self-supporting or non-dependent) as a base film. Here, “resin film” means a resin film that has a non-porous structure and typically contains substantially no air bubbles (voidless). Therefore, the resin film is a concept that is distinct from foam films or nonwoven fabrics. As the resin film, one that can independently maintain its shape (self-supporting or non-dependent) can be preferably used. The resin film may have a single-layer structure or a multi-layer structure of two or more layers (for example, a three-layer structure).

Examples of the resin material constituting the resin film include polyester; polyolefin; Polycycloolefins derived from monomers having an aliphatic ring structure such as a norbornene structure; Polyamides (PA) such as nylon 6, nylon 66, and partially aromatic polyamide; Polyimide (PI) such as transparent polyimide (CPI); polyamideimide (PAI); polyetheretherketone (PEEK); polyethersulfone (PES); polyphenylene sulfide (PPS); polycarbonate (PC); polyurethane (PU); ethylene-vinyl acetate copolymer (EVA); Fluororesins such as polytetrafluoroethylene (PTFE); Acrylic resin; Cellulose-based polymers such as triacetylcellulose (TAC); polyarylate; polystyrene; polyvinyl chloride; polyvinylidene chloride; Resins such as these can be used.

The resin film may be formed using a resin material that contains one type of such resin alone, or may be formed using a resin material that is a blend of two or more types. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched). For example, PET film, PBT film, PEN film, non-oriented polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, PP/ PE blend film, cycloolefin polymer (COP) film, CPI film, TAC film, etc. can be preferably used. Examples of preferable resin films from the viewpoint of strength and dimensional stability include PET film, PEN film, PPS film, and PEEK film. PET film and PPS film are particularly preferable from the viewpoint of ease of availability, etc., and among these, PET film is preferable.

The resin film needs to contain known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, and anti-blocking agents, to the extent that the effects of the present invention are not significantly impaired. It can be mixed accordingly. The amount of additives is not particularly limited and can be set appropriately depending on the purpose of the adhesive sheet.

The manufacturing method of the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T die cast molding, and calendar roll molding can be appropriately employed.

The substrate may be substantially composed of such a base film. Alternatively, the substrate may include an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjustment layer (e.g., a colored layer, an anti-reflection layer), a surface treatment layer such as a printing layer, a laminate layer, an antistatic layer, an undercoating layer, and a peeling layer for giving the substrate a desired appearance. I can hear it.

In some embodiments, a substrate having light transparency (hereinafter also referred to as a light transparency substrate) can be preferably used as the support substrate. This makes it possible to construct an adhesive sheet provided with a light-transmitting substrate. The total light transmittance of the light-transmitting substrate may be, for example, more than 50% or 70% or more. In some preferred embodiments, the total light transmittance of the support substrate is 80% or more, more preferably 90% or more, and may be 95% or more (for example, 95 to 100%). The total light transmittance is measured using a commercially available transmittance meter based on JIS K 7136:2000. As a transmittance meter, the product name "HAZEMETER HM-150" manufactured by Murakami Shikisai Kijutsu Kenkyujo or its equivalent is used. A suitable example of the light-transmitting substrate includes a resin film having light transparency. The light-transmitting substrate may be an optical film.

The thickness of the base material is not particularly limited and can be selected depending on the purpose of use or usage mode of the adhesive sheet. The thickness of the substrate may be, for example, 500 μm or less, preferably 300 μm or less from the viewpoint of handling and processability of the adhesive sheet, 150 μm or less, 100 μm or less, 50 μm or less, and 25 μm or less. It may be ㎛ or less, and may be 10 ㎛ or less. As the thickness of the substrate decreases, followability to the surface shape of the adherend tends to improve. Additionally, from the viewpoint of handling, processability, etc., the thickness of the substrate may be, for example, 2 μm or more, 10 μm or more, or 25 μm or more.

The surface of the substrate on which the adhesive layer is laminated is subjected to conventional treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and formation of an undercoat layer by applying an undercoat (primer), as needed. Known surface treatment may be performed. Such surface treatment may be a treatment to improve the anchoring properties of the adhesive layer to the substrate. The composition of the primer used to form the undercoat layer is not particularly limited and can be appropriately selected from known ones. The thickness of the undercoating layer is not particularly limited, but is usually about 0.01 μm to 1 μm, and is preferably about 0.1 μm to 1 μm. Other treatments that can be performed on the substrate as needed include antistatic layer formation treatment, colored layer formation treatment, and printing treatment. These treatments can be applied singly or in combination.

<Adhesive sheet with release liner>

The adhesive sheet disclosed herein may take the form of an adhesive product in which the surface (adhesive surface) of the adhesive layer is brought into contact with the release surface of the release liner. Accordingly, this specification provides an adhesive sheet (adhesive product) provided with a release liner including any of the adhesive sheets disclosed herein and a release liner having a release surface that contacts the adhesive surface of the adhesive sheet.

The release liner is not particularly limited and includes, for example, a release liner having a release layer on the surface of a liner base material such as a resin film or paper (possibly paper laminated with a resin such as polyethylene), or a fluorine-based polymer (polymer). A release liner made of a resin film formed of a low-adhesion material such as tetrafluoroethylene or polyolefin resin (polyethylene, polypropylene, etc.) can be used. Since the surface smoothness is excellent, a release liner having a release layer on the surface of a resin film as the liner base material or a release liner made of a resin film formed of a low-adhesive material can be preferably employed. The resin film is not particularly limited as long as it is a film that can protect the adhesive layer. For example, polyethylene (PE) film, polypropylene (PP) film, polybutene film, polybutadiene film, polymethylpentene film, poly Examples include vinyl chloride film, vinyl chloride copolymer film, polyester film (PET film, PBT film, etc.), polyurethane film, and ethylene-vinyl acetate copolymer film. For forming the peeling layer, known peeling agents such as silicone-based peeling agents, long-chain alkyl-based peeling agents, olefin-based peeling agents, fluorine-based peeling agents, fatty acid amide-based peeling agents, molybdenum sulfide, and silica powder can be used. there is.

<Use>

The uses of the adhesive or adhesive sheet disclosed here are not limited and can be used for various purposes. The adhesive or adhesive sheet disclosed herein has improved flexibility by using the silicone-based plasticizer, and the stability of the flexibility improvement effect (e.g., a decrease in flexibility due to long-term storage or storage under high temperature or moist heat conditions) By having good suppressing performance, it can be suitable for various uses. The adhesive sheet according to several embodiments is provided with an adhesive having a high refractive index and stably improved flexibility by including the silicone-based plasticizer, and can be used for various applications requiring high refractive index and flexibility by taking advantage of its characteristics. there is. For example, in electronic devices such as portable electronic devices, display devices (image display devices) such as liquid crystal display devices, organic EL (electroluminescence) display devices, PDP (plasma display panels), electronic paper, and touch display devices. It is suitable as an adhesive or adhesive sheet for devices such as input devices such as panels (optical devices), especially foldable displays and rollable displays. For example, in foldable displays or rollable displays, it is preferably used as a means of bonding, fixing, or protecting members with a high refractive index. The adhesive sheet disclosed herein has a high refractive index and can have good flexibility (for example, flexibility that can withstand repeated bending operations), so that it can be used repeatedly when attached to a foldable display or rollable display. It can follow the bent adherend (foldable display, etc.) well. Examples of objects to be attached in this form of use include glass members such as window glass and cover glass used in foldable displays and rollable displays. In addition, the adhesive or adhesive sheet disclosed herein easily follows and adheres to a curved surface, such as a three-dimensional shape of a portable electronic device, and is therefore suitable for use in electronic devices having such a curved shape. Additionally, the adhesive has improved stability in properties such as elastic modulus. Since the above-described portable electronic devices are sometimes used in high-temperature environments and their internal space may become heated due to heat generation from electronic components, it is advantageous to use an adhesive or adhesive sheet with good stability of the above properties. is big.

Examples of the above-mentioned portable electronic devices include, for example, mobile phones, smartphones, tablet-type personal computers, notebook-type personal computers, and various wearable devices (e.g., wristwear type worn on the wrist such as a wristwatch, clips, straps, etc.) Modular type that is attached to a part of the body, eyewear type including glasses type (monocular or binocular type, including head-mounted type), clothing type that is attached as an accessory to a shirt, socks, hat, etc., earphones and Earwear type worn on the ear, etc.), digital cameras, digital video cameras, audio devices (portable music players, IC recorders, etc.), calculators (electronic calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, vehicles Includes onboard information devices, portable radios, portable TVs, portable printers, portable scanners, portable modems, etc. In addition, in this specification, “carrying” is not sufficient simply to be able to carry, but means having a level of portability that allows an individual (a standard adult) to carry around with relative ease.

The material (adherent material) to which the adhesive or adhesive sheet disclosed herein is attached is not particularly limited, but includes, for example, copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, chromium, zinc, etc. , or metal materials such as alloys containing two or more types thereof, for example, polyimide resin, acrylic resin, polyethernitrile resin, polyether sulfone resin, polyester resin (PET resin, polyethylene naphthalate-based resin, etc.), polyvinyl chloride-based resin, polyphenylene sulfide-based resin, polyether ether ketone-based resin, polyamide-based resin (so-called aramid resin, etc.), polyarylate-based resin, polycarbonate-based resin, Cellulose-based polymers such as diacetylcellulose and triacetylcellulose, various resin materials (typically plastic materials) such as vinyl butyral polymers and liquid crystal polymers, alumina, zirconia, alkali glass, alkali-free glass, quartz glass, carbon, etc. Inorganic materials, etc. can be mentioned. The adhesive or adhesive sheet disclosed herein can be used by being attached to a member (for example, an optical member) made of the above material.

The member or material to which the adhesive or adhesive sheet disclosed herein is attached (in the case of a double-sided adhesive sheet, at least one adherend) may be made of a material with a higher refractive index than a general acrylic adhesive. The refractive index of the adherend material is, for example, 1.50 or more. Among them, there are adherend materials with a refractive index of 1.55 or more or 1.58 or more, and there are also those with a refractive index of 1.62 or more (for example, about 1.66). Such a high refractive index adherend material is typically a resin material. More specifically, it may be polyester-based resin such as PET, polyimide-based resin, aramid resin, polyphenylene sulfide-based resin, polycarbonate-based resin, etc. For such materials, the effect of using the adhesive or adhesive sheet disclosed herein (suppression of reflection of light due to a difference in refractive index) can be advantageously exhibited. The upper limit of the refractive index of the adherend material is, for example, 1.80 or less, and may be 1.70 or less. The adhesive or adhesive sheet disclosed herein can be suitably used in the form of attaching it to an adherend (for example, member) with a high refractive index as described above. A suitable example of such an adherend includes a resin film having a refractive index of 1.50 to 1.80 (preferably 1.55 to 1.75, for example, 1.60 to 1.70). The refractive index can be measured by the same method as the refractive index of the adhesive.

The member or material to which the adhesive or adhesive sheet is to be attached (in the case of a double-sided adhesive sheet, at least one adherend) may have light transparency. With such an adherend, it is easy to obtain the advantage of the effect (suppression of light reflection at the interface between the adherend and the adhesive sheet) by the technology disclosed herein. The total light transmittance of the adherend may be, for example, greater than 50%, and preferably greater than 70%. In some preferred embodiments, the total light transmittance of the adherend is 80% or more, more preferably 90% or more, and may be 95% or more (for example, 95 to 100%). The technology disclosed herein can be suitably used in the form of attaching an adhesive or an adhesive sheet to a member (for example, an optical member) whose total light transmittance is a predetermined value or more. The total light transmittance is measured using a commercially available transmittance meter based on JIS K 7136:2000. As a transmittance meter, the product name "HAZEMETER HM-150" manufactured by Murakami Shikisai Kijutsu Kenkyujo or its equivalent is used.

In some preferred embodiments, the object to which the adhesive or adhesive sheet is attached (adherent, for example, member) may have the above-described refractive index and may have the above-described total light transmittance. Specifically, the refractive index is 1.50 or more (e.g., 1.55 or more, 1.58 or more, 1.62 or more, about 1.66, etc.), and the total light transmittance is greater than 50% (e.g., 70% or more, preferably 80% or more, More preferably, it may be 90% or more, and further 95% or more.) The adhesive or adhesive sheet disclosed herein can be preferably used in the form of sticking to an adherend, for example, a member. In the aspect where it is attached to such a member, the effect achieved by the technique disclosed herein is particularly preferably exhibited.

The adhesive disclosed herein can be formed on the adherend described above by applying (typically applying) the adhesive composition to the adherend and drying and/or curing the adhesive composition. Therefore, in the above examples, descriptions such as the object to which the adhesive or the adhesive sheet is attached, the adhesive or the adhesive sheet is attached, and the adhesive or the adhesive sheet are attached refer to the object on which the adhesive is formed by applying the adhesive composition, the adhesive composition, respectively. The pressure-sensitive adhesive is formed by applying the pressure-sensitive adhesive composition. It can be replaced with the pressure-sensitive adhesive composition.

An example of a preferable use is optical use. More specifically, it is an optical adhesive or optical adhesive sheet used, for example, for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the optical members. The disclosed adhesive or adhesive sheet can be preferably used.

The optical member refers to a member having optical properties (e.g., polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, light rotation, visibility, etc.). The optical member is not particularly limited as long as it has optical properties, but examples include members constituting devices (optical devices) such as display devices (image display devices) and input devices, or members used in these devices. For example, polarizer, wave plate, retardation plate, optical compensation film, brightness enhancement film, light guide plate, reflective film, anti-reflection film, hard coat (HC) film, shock absorption film, antifouling film, photochromic film, Illuminated films, transparent conductive films (ITO films), design films, decorative films, surface protection plates, prisms, lenses, color filters, transparent substrates, and even members in which they are laminated (sometimes these are collectively referred to as “functional films”) ), etc. In addition, the above-mentioned “plate” and “film” include forms such as plate, film, and sheet, respectively. For example, “polarizing film” includes “polarizing plate” and “polarizing sheet”, etc. , “Light guide plate” shall include “light guide film”, “light guide sheet”, etc. In addition, the above-mentioned “polarizing plate” shall include a circularly polarizing plate.

Examples of the display device include a liquid crystal display device, an organic EL display device, micro LED (μLED), mini LED (miniLED), PDP, electronic paper, etc. Additionally, examples of the input device include a touch panel and the like.

The optical member is not particularly limited, but includes, for example, members made of glass, acrylic resin, polycarbonate, PET, metal thin film, etc. (e.g., sheet-shaped, film-shaped, plate-shaped members). there is. In addition, “optical members” in this specification shall also include members (such as decoration films, decorative films, and surface protection films) that play a role in decoration or protection while maintaining the visibility of the display device or input device.

The technology disclosed herein, for example, uses optical films such as films or fluorescent films having one or two or more functions such as light transmission, reflection, diffusion, wave guidance, light collection, and diffraction to other optical members (which may be other optical films). It can be preferably used to join). Among them, in the case of bonding optical films that have at least one of the functions of light guiding, condensing, and diffraction, it is preferable that the entire bulk of the bonding layer has a high refractive index, and the technology disclosed herein can be preferably applied.

The adhesive disclosed herein can be preferably used for bonding optical films such as light guide films, diffusion films, fluorescent films, tinting films, prism sheets, lenticular films, and microlens array films. In these applications, from the viewpoint of the trend towards miniaturization and improved performance of optical members, reduction in thickness and improvement in light extraction efficiency are required. As an adhesive that can meet these requests, the adhesive disclosed herein can be preferably used. More specifically, for example, in bonding a light guide film or a diffusion film, adjusting the refractive index of the adhesive layer as a bonding layer (for example, increasing the refractive index) can contribute to thinning. In the bonding of fluorescent films, light extraction efficiency (which can also be understood as luminous efficiency) can be improved by appropriately adjusting the refractive index difference between the fluorescent emitter and the adhesive. In bonding of a coloring film, the scattering component can be reduced by appropriately adjusting the refractive index of the adhesive so that the difference in refractive index with the coloring pigment is small, thereby contributing to the improvement of light transmittance. In bonding prism sheets, lenticular films, microlens array films, etc., diffraction of light can be controlled by appropriately adjusting the refractive index of the adhesive, contributing to improvement of brightness and/or viewing angle.

The adhesive or adhesive sheet disclosed herein is preferably used in the form of being affixed to a high refractive index adherend (which may be a high refractive index layer or member, etc.), and can suppress reflection at the interface with the adherend. As described above, the adhesive or adhesive sheet used in this manner preferably has a small difference in refractive index with the adherend and has high adhesion at the interface with the adherend. Additionally, from the viewpoint of enhancing the uniformity of appearance, it is desirable that the thickness of the adhesive (layer) be highly uniform, and for example, it is desirable that the surface smoothness of the adhesive surface is high. When the thickness of the high refractive index adherend is relatively small (for example, 5 ㎛ or less, 4 ㎛ or less, or 2 ㎛ or less), from the viewpoint of suppressing coloring or color unevenness due to interference of reflected light, reflection at the interface It is particularly meaningful to suppress . As an example of such a usage mode, in a polarizing plate provided with a retardation layer including a polarizer, a first retardation layer, and a second retardation layer in this order, bonding of the polarizer and the first retardation layer and/or the first retardation layer An aspect used for bonding a layer and the second phase difference layer can be mentioned.

In addition, since the adhesive or adhesive sheet disclosed herein is suitable for high refractive index, it can be preferably used in the form of being attached to a light-emitting layer of an optical semiconductor or the like (e.g., a high-refractive light-emitting layer mainly composed of an inorganic material). there is. By reducing the difference in refractive index between the light-emitting layer and the adhesive (layer), reflection at their interface can be suppressed and light extraction efficiency can be improved. The adhesive or adhesive sheet used in this manner preferably includes an adhesive (layer) with a high refractive index. Additionally, from the viewpoint of improving brightness, it is preferable that the adhesive or adhesive sheet be low-colored. This can also be advantageous from the viewpoint of suppressing unintentional coloring caused by the adhesive or adhesive sheet.

The adhesive sheet disclosed herein can be suitably used in a light-emitting device including a self-luminous element as a component in an arrangement placed on a viewing side of the self-luminous element. Here, a self-luminous device refers to a light-emitting device whose luminance can be controlled by the flowing current value. The self-luminous element may be composed of a single entity or an aggregate. Specific examples of self-luminous devices include, but are not limited to, light emitting diodes (LEDs) and organic ELs. Examples of light-emitting devices including the self-luminous element as a component include, but are not limited to, light source module devices used as lighting (e.g., planar light-emitting body modules) and display devices in which pixels are formed. .

The adhesive disclosed herein can be applied to microlenses and other lens members used as structural members of cameras, light emitting devices, etc. (for example, lens members such as microlenses constituting a microlens array film and microlenses for cameras). Preferred as a coating layer covering the lens surface, a bonding layer with a member opposing the lens surface (for example, a member having a surface shape corresponding to the lens surface), a filling layer filled between the lens surface and the member, etc. It can be used effectively. Since the adhesive disclosed herein is suitable for increasing the refractive index, even if it is a high refractive index lens (for example, a lens made of a high refractive index resin or a lens having a surface layer made of a high refractive index resin), the adhesive has a high refractive index compared to the lens. The car can be reduced. This is advantageous from the viewpoint of reducing the thickness of the lens and products equipped with the lens, and can also contribute to suppressing aberrations and improving the Abbe number. The adhesive disclosed herein can also be used as a lens resin by itself, for example, in the form of filling the recesses or voids of a suitable transparent member.

The mode of bonding optical members using the adhesive or adhesive sheet disclosed herein is not particularly limited, but examples include (1) the mode of bonding optical members to each other using the adhesive or adhesive sheet disclosed herein; (2) The optical member may be bonded to a member other than the optical member through the adhesive or adhesive sheet disclosed herein, and (3) the adhesive sheet disclosed herein may be in a form including an optical member, and the adhesive sheet may be used as an optical member. The form of joining to a member or a member other than an optical member may be sufficient. Additionally, in the aspect (3) above, the pressure-sensitive adhesive sheet including an optical member may be, for example, a pressure-sensitive adhesive sheet whose support is an optical member (eg, an optical film). In this way, a pressure-sensitive adhesive sheet including an optical member as a support can also be considered as a pressure-sensitive adhesive optical member (for example, a pressure-sensitive adhesive optical film). In addition, when the adhesive sheet disclosed herein is a type of adhesive sheet having a support and the functional film is used as the support, the adhesive sheet disclosed herein has an adhesive layer disclosed herein on at least one side of the functional film. It can also be understood as an “adhesive functional film” having .

From the above, according to the technology disclosed herein, a laminate including the adhesive sheet disclosed herein and a member to which the adhesive sheet is attached is provided. The member to which the adhesive sheet is attached may have the refractive index of the adherend material described above. Additionally, the difference between the refractive index of the adhesive sheet and the refractive index of the member (refractive index difference) may be the difference in refractive index between the adherend and the adhesive sheet described above. The members constituting the laminate are as described above as members, materials, and adherends, so overlapping explanations will not be repeated.

[Example]

Hereinafter, several examples of the present invention will be described, but it is not intended to limit the present invention to these specific examples. In addition, in the following description, “part” and “%” indicating the usage amount or content are based on weight unless otherwise specified.

<Example 1>

(Preparation of polymer solution)

In a four-neck flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser, m-phenoxybenzyl acrylate (manufactured by Kyoesha Chemical Co., Ltd., brand name “Light Acrylate POB-A”) as a monomer component, refractive index: 1.566. (hereinafter referred to as “POB-A”) 95 parts and 5 parts of 4-hydroxybutylacrylate (4HBA), 0.2 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator, and acetic acid as a polymerization solvent. 150 parts of ethyl was added, nitrogen gas was introduced with gentle stirring, the liquid temperature in the flask was maintained at around 60°C, and polymerization reaction was performed for 6 hours to prepare a solution (40%) of polymer P1. The Mw of polymer P1 was 500,000.

(Preparation of adhesive composition)

The solution of polymer P1 was diluted with ethyl acetate to a polymer concentration of 30%, and 1,3,5-trimethyl-1,1,3,5,5-pentaphenyltri was added to 334 parts of this solution (100 parts of non-volatile matter). 30 parts of siloxane (manufactured by Shinetsu Chemical Co., Ltd., brand name “HIVAC F-5”, refractive index: 1.575, liquid at 20°C. Hereinafter also referred to as plasticizer S1), isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name “Coronate HX”, hexagonal 0.05 parts of methylene diisocyanate (HDI) isocyanurate (hereinafter also referred to as cross-linking agent C1), 2 parts of acetylacetone as a cross-linking retardant, and 0.01 part of ferric nasem as a cross-linking catalyst were added and mixed with stirring. An adhesive composition was prepared.

(Production of adhesive sheet)

The adhesive composition prepared above was applied to the silicone-treated side of polyethylene terephthalate (PET) film R1 (50㎛ thick), one side of which was silicone-treated, and heated at 130°C for 2 minutes to form an adhesive layer with a thickness of 20㎛. formed. Next, the silicone-treated side of PET film R2 (thickness 25 μm), on which one side was silicone-treated, was bonded to the surface of the adhesive layer. In this way, 1 consisting of the adhesive layer was obtained. Both sides of this adhesive sheet are protected by PET films (release liners) R1 and R2.

<Example 2>

In the preparation of the adhesive composition in Example 1, 1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name “HIVAC F”) was used instead of plasticizer S1. -4", refractive index: 1.555, liquid at 20°C. (hereinafter also referred to as plasticizer S2) was used. Otherwise, in the same manner as Example 1, the adhesive composition according to this example was prepared.

An adhesive sheet according to this example (an inorganic double-sided adhesive sheet consisting of an adhesive layer) was produced in the same manner as the production of the adhesive sheet in Example 1 except that the obtained adhesive composition was used.

<Example 3>

Example 1 except that the composition of the monomer components was changed to 95 parts of POB-A, 3.1 parts of 4HBA, and 1.9 parts of 2-acryloyloxyethyl-succinic acid (manufactured by Kyoesha Chemical Company, brand name “HOA-MS(N)”). In the same manner as the preparation of the polymer solution, a solution (40%) of polymer P2 was prepared. The Mw of polymer P2 was 500,000.

The solution of the polymer P2 was diluted with ethyl acetate to a polymer concentration of 30%, and to 334 parts of this solution (100 parts of non-volatile matter), 1.0 part of the plasticizer S1 (HIVAC F-5) and 0.05 part of the crosslinking agent C1 were crosslinked. 2 parts of acetylacetone as a retardant and 0.01 part of ferric nasem as a crosslinking catalyst were added and mixed with stirring to prepare the pressure-sensitive adhesive composition according to this example.

An adhesive sheet according to this example (an inorganic double-sided adhesive sheet consisting of an adhesive layer) was produced in the same manner as the production of the adhesive sheet in Example 1 except that the obtained adhesive composition was used.

<Examples 4 to 14>

The pressure-sensitive adhesive compositions for each example were prepared in the same manner as in Example 3, except that the type and amount of the plasticizer used in the preparation of the pressure-sensitive adhesive composition were changed as shown in Table 1.

An adhesive sheet (inorganic double-sided adhesive sheet consisting of an adhesive layer) for each example was produced in the same manner as the production of the adhesive sheet in Example 1, except that each of the obtained adhesive compositions was used.

<Example 15>

The composition of the monomer component is 63 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinylpyrrolidone (NVP), 9 parts of methyl methacrylate (MMA), and 13 parts of 2-hydroxyethyl acrylate (HEA). A solution (40%) of polymer P3 was prepared in the same manner as the preparation of the polymer solution in Example 1 except for the changes. The Mw of polymer P3 was 1 million.

The solution of the polymer P3 was diluted with ethyl acetate to a polymer concentration of 30%, and to 334 parts of this solution (100 parts of non-volatile matter), 10 parts of the plasticizer S1 (HIVAC F-5) and 0.10 parts of the crosslinking agent C1 were added for crosslinking. 2 parts of acetylacetone as a retardant and 0.01 part of ferric nasem as a crosslinking catalyst were added and mixed with stirring to prepare the pressure-sensitive adhesive composition according to this example.

An adhesive sheet according to this example (an inorganic double-sided adhesive sheet consisting of an adhesive layer) was produced in the same manner as the production of the adhesive sheet in Example 1 except that the obtained adhesive composition was used.

<Example 16>

A solution (40%) of polymer P4 was prepared in the same manner as the preparation of the polymer solution in Example 1, except that the composition of the monomer components was changed to 89.3 parts of 2EHA, 8.9 parts of NVP, and 1.8 parts of 4-hydroxybutylacrylate (4HBA). It was prepared. The Mw of polymer P4 was 1 million.

The solution of the polymer P4 was diluted with ethyl acetate to a polymer concentration of 30%, and to 334 parts of this solution (100 parts of non-volatile matter), 10 parts of the plasticizer S1 (HIVAC F-5) and 0.10 parts of the crosslinker C1 were added for crosslinking. 2 parts of acetylacetone as a retardant and 0.01 part of ferric nasem as a crosslinking catalyst were added and mixed with stirring to prepare the pressure-sensitive adhesive composition according to this example.

An adhesive sheet according to this example (an inorganic double-sided adhesive sheet consisting of an adhesive layer) was produced in the same manner as the production of the adhesive sheet in Example 1 except that the obtained adhesive composition was used.

<Example 17>

In the preparation of the adhesive composition in Example 1, diethylene glycol dibenzoate (non-silicone compound with a refractive index of 1.535. Liquid at 20°C. Hereinafter also referred to as plasticizer S3) was used instead of plasticizer S1, and a solution of the polymer P1 was used. 10 parts were used for 334 parts (100 parts of non-volatile matter) of a solution diluted with ethyl acetate to a polymer concentration of 30%. Otherwise, in the same manner as Example 1, the adhesive composition according to this example was prepared.

An adhesive sheet according to this example (an inorganic double-sided adhesive sheet consisting of an adhesive layer) was produced in the same manner as the production of the adhesive sheet in Example 1 except that the obtained adhesive composition was used.

<Example 18>

In preparing the adhesive composition in Example 5, plasticizer S3 was used instead of plasticizer S1. Otherwise, in the same manner as Example 5, the adhesive composition according to this example was prepared.

An adhesive sheet according to this example (an inorganic double-sided adhesive sheet consisting of an adhesive layer) was produced in the same manner as the production of the adhesive sheet in Example 1 except that the obtained adhesive composition was used.

<Examples 19 to 21>

The pressure-sensitive adhesive compositions for each example were prepared in the same manner as the preparation of the pressure-sensitive adhesive compositions for Examples 1, 15, and 16, except that plasticizer S1 was not used.

An adhesive sheet (inorganic double-sided adhesive sheet consisting of an adhesive layer) for each example was produced in the same manner as the production of the adhesive sheet in Example 1, except that each of the obtained adhesive compositions was used.

<Evaluation method>

(refractive index)

For the adhesive layer (baseless double-sided adhesive sheet) for each example, the refractive index was measured using an Abbe refractometer (manufactured by ATAGO, model "DR-M4") under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C. . The results are shown in Table 1.

(Storage modulus G' and rate of change due to moist heat)

(1) Initial storage modulus

The adhesive layers for each example were laminated to a thickness of about 1.5 mm, and punched into a disc shape with a diameter of 7.9 mm were used as samples for measurement. Dynamic viscoelasticity measurements were performed using the “Advanced Rheometric Expansion System (ARES)” manufactured by Rheometric Scientific under the following conditions. From the measurement results, the storage modulus G' [kPa] of the adhesive at each temperature (0°C and 23°C) was determined. The results are shown in Table 1.

[Measuring conditions]

Deformation Mode: Torsion

Measurement frequency: 1Hz

Temperature range: -50℃ to 150℃

Temperature increase rate: 5℃/min

Shape: Parallel plate 7.9mmϕ

(2) Storage modulus G' after moist heat

After applying moist heat treatment to the adhesive layer in each example in the form of an inorganic double-sided adhesive sheet with both sides protected by release liners R1 and R2, maintained for 500 hours in a moist heat environment of 85°C and 85% relative humidity, It was taken out from the above moist heat environment and kept in an environment of 23°C and 50% relative humidity for 24 hours. The pressure-sensitive adhesive layer after wet heat was laminated to a thickness of about 1.5 mm and punched into a disk with a diameter of 7.9 mm as a sample for measurement. In the same manner as the measurement of the initial storage modulus, each temperature of the adhesive after wet heat (0 The storage elastic modulus G'[kPa] at (°C and 23°C) was determined. The results are shown in Table 1.

(3) Rate of change due to moist heat

From the obtained initial storage elastic modulus E ₀ [kPa] and storage elastic modulus E ₁ [kPa] after wet heat, the rate of change [%] of storage elastic modulus due to wet heat was calculated for each temperature (0°C and 23°C) using the following equation. . The results are shown in Table 1.

Rate of change [%]=[(E ₁ -E ₀ )/E ₀ ]×100

(Hayes)

A test piece was used in which the adhesive layer for each example was bonded to alkali-free glass (thickness 0.8 to 1.0 mm, total light transmittance 92%, haze 0.4%), and a haze meter (Murakami Shikisai Kijutsu Kenkyu) was used in a measurement environment of 23°C. Haze was measured using the preparation "HM-150"). The value obtained by subtracting the haze of the alkali-free glass from the measured value was taken as the haze [%] of the adhesive layer. As a result, the haze of the adhesive layers according to Examples 1 to 21 was all within the range of 0.2% or more and less than 1.0%.

As shown in Table 1, by adding plasticizer S1 or S2, which is a silicone-based plasticizer that satisfies predetermined structural requirements, the effect of lowering the storage modulus G' was obtained at both 0°C and 23°C (Examples 1 to 23) 16). In addition, the adhesives of Examples 1 to 16 all showed a small change rate (increase rate) in the storage elastic modulus G' upon storage under moist heat conditions, and a highly stable plasticization effect was shown by using the plasticizer S1 or S2. In an adhesive using polymer P1 or P2 as a base polymer, which is a non-silicon polymer containing a repeating unit having a double bond-containing ring (here, an aromatic ring), compared to an adhesive using polymer P3 or P4 as a base polymer, plasticizer S1 or S2 The effect of lowering the storage modulus G' was more significant.

On the other hand, in Examples 17 and 18 using plasticizer S3, which is a non-silicone plasticizer, the change rate (increase rate) of the storage modulus G' was obviously larger than in Examples 1 to 16, and the stability of the plasticizing effect for storage under moist heat was low.

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

1, 2, 3: Adhesive sheet
10: Supporting substrate
10A: side 1
10B: Side 2
21: Adhesive layer, first adhesive layer
21A: Adhesive side, first adhesive side
21B: Adhesive side
22: Second adhesive layer
22A: Second adhesive side
31, 32: release liner

Claims (10)

It is a silicone-based plasticizer made of siloxane compounds,
The number of Si atoms contained in the siloxane compound is 2 or more and 5 or less,
A silicone-based plasticizer in which at least one of the Si atoms has two or more double bond-containing rings bonded to the Si atom. According to paragraph 1,
The siloxane compound is a trisiloxane compound, a silicone-based plasticizer. According to claim 1 or 2,
A silicone-based plasticizer wherein the number of double bond-containing rings contained in the siloxane compound is 4 or more and 6 or less. According to any one of claims 1 to 3,
A silicone-based plasticizer wherein the number of Si atoms to which the two or more double bond-containing rings are bonded is two or more. According to any one of claims 1 to 4,
A silicone-based plasticizer wherein the molecular weight of the siloxane compound is 450 or more and 750 or less. According to any one of claims 1 to 5,
Silicone-based plasticizer that is liquid at 25°C. According to any one of claims 1 to 6,
A silicone-based plasticizer used as a plasticizer for adhesives. An adhesive comprising the silicone-based plasticizer according to any one of claims 1 to 7. According to clause 8,
The adhesive contains as a base polymer a polymer containing a repeating unit having a double bond-containing ring. According to clause 8 or 9,
The adhesive contains an acrylic polymer as a base polymer.