Adhesive materials and adhesive sheets

Abstract

An adhesive material is provided, which has excellent adhesion, excellent flexibility and excellent resilience. The adhesive material is characterized by containing a polymer (X) with a cross-linked structure, having a shear storage modulus of 0.15 MPa or less at a temperature of 25°C, a glass transfer temperature of 0°C or less, a gelation rate of 50% to 95% by mass, and the differential molecular weight distribution curve of the colloidal component satisfies the following requirements: (1) the ratio (W1) of the peak area of ​​molecular weight of 10,000 or more but less than 100,000 to the peak area of ​​molecular weight of 10,000 to 30 million is less than 20%; (2) the ratio (W2) of the peak area of ​​molecular weight of 100,000 or more but less than 560,000 to the peak area of ​​molecular weight of 10,000 to 30 million is more than 40%; and (3) the ratio (W3) of the peak area of ​​molecular weight of 560,000 or more to the peak area of ​​molecular weight of 10,000 to 30 million is less than 40%.

Description

[Technical Field]

[0001] This invention relates to an adhesive material and adhesive sheet, and more particularly to an adhesive material and adhesive sheet for bonding a flexible member with other flexible members. [Previous Technology]

[0002] In various displays or touch panels such as televisions, mobile phones, and smartphones, adhesives are typically used to join the components together. The adhesive is provided in the form of a substrate-attached adhesive sheet with an adhesive layer on a supporting substrate, or in the form of a substrate-free adhesive sheet without a supporting substrate, so that the components can be bonded together.

[0003] On the other hand, flexible displays that can be repeatedly flexed have attracted attention in image display devices such as liquid crystal display devices or organic electroluminescent (organic EL) display devices. Flexible displays include foldable displays that can be folded, rollable displays that can be rolled into a tube, etc., and are expected to be used in mobile terminals such as smartphones and tablet terminals, as well as retractable fixed displays.

[0004] In such flexible displays, the adhesive material used to bond the flexible member constituting the member of repeated flexing and stretching to other flexible members, for example, Patent Document 1 discloses an adhesive material for a repeated flexing element, which controls the ratio of the shear stress after 60 seconds when 1000% displacement to the maximum shear stress when one side of the adhesive layer is changed by 1000% displacement in opposite directions, and the gelation rate within a predetermined range (see Patent Document 1 (claim 1)).

[0005] [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2019-108498 [Summary of the Invention]

[0006] [Problem to be solved by the invention] In the case of repeated bending, conventional adhesives cannot fully recover from the bent state to the original state. Therefore, when conventional adhesives are used to join flexible components, there is a risk of bulging or peeling at the interface between the adhesive and the flexible component at the bending point during repeated bending.

[0007] In view of the above circumstances, the present invention aims to provide an adhesive material having excellent adhesion, excellent flexibility and excellent resilience.

[0008] [Technical means to solve the problem] The adhesive material system of the present invention, which can solve the above-mentioned problem, contains a polymer (X) having a cross-linked structure, characterized in that: the shear storage modulus at a temperature of 25°C is 0.15 MPa or less; the glass transfer temperature is 0°C or less; the gelation rate is 50% to 95% by mass; and the differential molecular weight distribution curve of the colloidal component satisfies the requirements of (1), (2) and (3): (1) the ratio (W1) of the peak area of ​​molecular weight of 10,000 or more but less than 100,000 to the peak area of ​​molecular weight of 10,000 to 30 million is less than 20%; (2) the ratio (W2) of the peak area of ​​molecular weight of 100,000 or more but less than 560,000 to the peak area of ​​molecular weight of 10,000 to 30 million is more than 40%; and (3) the ratio (W3) of the peak area of ​​molecular weight of 560,000 or more to the peak area of ​​molecular weight of 10,000 to 30 million is less than 40%.

[0009] [Effects of the Invention] The adhesive material of the present invention has excellent adhesion, excellent flexibility and resilience. Therefore, by using the adhesive material of the present invention for bonding flexible components, even with repeated bending, it is possible to prevent protrusion or peeling of the adhesive material at the interface between the adhesive material and the flexible component at the bending point.

Implementation Method

[0011] The following describes a preferred embodiment of the present invention. However, the following embodiments are merely illustrative. The present invention is not limited to the following embodiments.

[0012] The term "~" in this application is used to include the numerical values ​​before and after it as the lower and upper limits. "(Meth)acrylate" refers to "at least one of acrylate and methacrylate". "(Meth)acrylate" refers to "at least one of acrylate and methacrylate". "(Meth)acryl" refers to "at least one of acrylonitrile and methacryl". "Ethylene monomer" refers to a monomer having a carbon-carbon double bond with a polymerizable free radical. "Building unit from ethylene monomer" refers to a building unit that polymerizes the carbon-carbon double bond of a polymerizable free radical of an ethylene monomer to form a carbon-carbon single bond. "Building unit from (meth)acrylate" refers to a building unit that polymerizes the carbon-carbon double bond of a polymerizable free radical of a (meth)acrylate to form a carbon-carbon single bond. "Building units derived from (meth)acrylic acid monomers" refers to the building units that polymerize the carbon-carbon double bonds of the polymerizable free radicals of (meth)acrylic acid monomers to form carbon-carbon single bonds.

[0013] [Adhesive Material] The adhesive material of the present invention contains a polymer (X) with a cross-linked structure, a shear storage modulus of 0.15 MPa or less at a temperature of 25°C, a glass transfer temperature of 0°C or less, and a gelation rate of 50% to 95% by mass.

[0014] The shear storage modulus of the adhesive material at a temperature of 25°C is preferably 0.15 MPa or less, more preferably 0.10 MPa or less, and most preferably 0.08 MPa or less. If the shear storage modulus is below 0.15 MPa, the increased flexibility of the adhesive material improves its ability to track deformation, thus preventing protrusion or peeling at the interface between the adhesive material and the flexible member at the flexural point, even with repeated flexing. The shear storage modulus of the adhesive material at a temperature of 25°C is preferably 0.01 MPa or more, and more preferably 0.02 MPa or more. If the shear storage modulus is above 0.01 MPa, the adhesion retention force when the adhesive sheet and the bonded body are bonded is improved.

[0015] The glass transition temperature (Tg) of the adhesive is preferably below 0°C, more preferably below -20°C, and most preferably below -30°C. If the glass transition temperature is below 0°C, the adhesion of the formed adhesive to the substrate will be improved, and durability will be enhanced by suppressing peeling at low temperatures. The lower limit of the glass transition temperature of the adhesive is not particularly limited, but is typically around -50°C.

[0016] The gelation rate of this adhesive material is preferably 50% by mass or more, more preferably 55% by mass or more, most preferably 60% by mass or more, preferably 95% by mass or less, more preferably 90% by mass or less, and most preferably 80% by mass or less. An adhesive material with excellent flexibility and resilience can be formed when the gelation rate is between 50% by mass and 95% by mass. The gelation rate can be controlled by the content of the first crosslinking group in the components described later, the type of crosslinking agent, and the amount of crosslinking agent.

[0017] The adhesive material contains a colloidal component. This colloidal component is the component that dissolves into the solvent when the adhesive material is extracted with ethyl acetate at 25°C for 72 hours. The adhesive material is characterized in that the differential molecular weight distribution curve of the colloidal component satisfies the requirements of (1), (2), and (3). Furthermore, the differential molecular weight distribution curve is prepared using a chromatography chromatogram obtained by GPC (gel chromatography). Specifically, an integral molecular weight distribution curve is prepared with the horizontal axis representing the molecular weight (logarithmic value) and the vertical axis representing the cumulative value of the concentration fraction. Next, the slope (differential value) of the curve for each molecular weight is obtained. Finally, a differential molecular weight distribution curve is prepared with the horizontal axis representing the molecular weight (logarithmic value) and the horizontal axis representing the differential value.

[0018] (1) The ratio (W1) of the peak area with a molecular weight of 10,000 or more but less than 100,000 to the peak area with a molecular weight of 10,000 to 30 million is less than 20%. (2) The ratio (W2) of the peak area with a molecular weight of 100,000 or more but less than 560,000 to the peak area with a molecular weight of 10,000 to 30 million is more than 40%. (3) The ratio (W3) of the peak area with a molecular weight of 560,000 or more to the peak area with a molecular weight of 10,000 to 30 million is less than 40%. By satisfying the above requirements (1) to (3), an adhesive material with excellent adhesion, excellent flexibility and excellent resilience can be formed.

[0019] The content of W1 is preferably 15% or less, more preferably 10% or less, and most preferably 7% or less. If the content of W1 is 15% or less, the decrease in adhesion caused by the plasticity effect of the colloidal component can be suppressed. The content of W1 is preferably 0%, but it can also be 0% or more. In this case, the content of W1 is preferably 1.0% or more, more preferably 1.6% or more, and most preferably 1.8% or more. If the content of W1 is 1.0% or more, the wettability of the interface between the adhesive material and the substrate due to the colloidal component can be improved, thereby improving the adhesion.

[0020] The W2 content is preferably 50% or more, more preferably 60% or more, and most preferably 70% or more. If the W2 content is 50% or more, an adhesive material with excellent adhesion can be formed. The W2 content is preferably 100%, but may not reach 100%. In this case, the W2 content is preferably 98% or less, more preferably 95.4% or less, and most preferably 88.2% or less.

[0021] The W3 content is preferably 30% or less, more preferably 25% or less, and most preferably 20% or less. When the W3 content is below 30%, the entanglement effect of the colloidal components can be suppressed, resulting in better recovery during repeated flexing. The W3 content is preferably 0%, but can also be above 0%. In this case, the W3 content is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 3.0% or more, and most preferably 10% or more. When the W3 content is above 0.5%, the cohesion of the adhesive material can be improved, resulting in better adhesion.

[0022] The ratio of W1 to W3 (W1 / W3) is preferably 0.07 or higher, more preferably 0.10 or higher, most preferably 0.15 or higher, preferably 26.0 or lower, more preferably 6.5 or lower, even more preferably 5.5 or lower, and most preferably 4.0 or lower. If the ratio (W1 / W3) is 0.07 or higher, the wettability of the interface between the adhesive material and the flexible component caused by the colloidal component can be improved, resulting in good adhesion. If it is 26.0 or lower, the decrease in adhesion caused by the plasticity effect of the colloidal component can be suppressed.

[0023] Preferably, the differential molecular weight distribution curve of the colloidal component of the adhesive material further satisfies the requirements of (2a) and (2b): (2a) The ratio of the peak area of ​​the molecular weight of 100,000 or more but less than 150,000 to the peak area of ​​the molecular weight of 10,000 to 30 million (W2a) is more than 15%. (2b) The ratio of the peak area of ​​the molecular weight of 150,000 or more but less than 560,000 to the peak area of ​​the molecular weight of 10,000 to 30 million (W2b) is more than 20%. By satisfying the requirements of (2a) and (2b), an adhesive material with excellent adhesion that achieves a balance between cohesiveness and wettability caused by the colloidal component can be formed.

[0024] The content of W2a is preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, most preferably 35% or more, preferably 46% or less, more preferably 45.4% or less, and most preferably 44.9% or less. If the content of W2a is 20% or more, the entanglement effect of the colloidal components can be suppressed, resulting in excellent softness and resilience. If the content is 46% or less, the decrease in adhesion caused by the plasticity effect of the colloidal components can be suppressed.

[0025] The W2b content is preferably 25% or higher, more preferably 30% or higher, most preferably 35% or higher, preferably 52% or lower, more preferably 50% or lower, and most preferably 43.3% or lower. When the W2b content is above 25%, excellent adhesion is observed due to the increased cohesiveness of the colloidal components. When it is below 52%, excellent softness and resilience are observed by suppressing the entanglement effect of the colloidal components.

[0026] The ratio of W2 to W2a (W2a / W2) is preferably 0.30 or higher, more preferably 0.35 or higher, most preferably 0.45 or higher, preferably 0.60 or lower, more preferably 0.55 or lower, and most preferably 0.53 or lower.

[0027] In the differential molecular weight distribution curve of the colloidal component, the highest peak molecular weight (Mp) in the range of 10,000 to 30 million is preferably above 100,000, preferably below 500,000, more preferably below 300,000, and most preferably below 200,000. If the peak molecular weight (Mp) is within this range, there is a tendency to form an adhesive material with excellent adhesion.

[0028] The weight average molecular weight of the colloidal component is preferably 100,000 or more, more preferably 150,000 or more, most preferably 200,000 or more, preferably 560,000 or less, more preferably 450,000 or less, and most preferably 400,000 or less. If the weight average molecular weight is within this range, an adhesive material with excellent adhesion can be formed.

[0029] The molecular weight distribution (Mw / Mn) of the colloidal component is preferably 6.0 or less, more preferably 4.0 or less, and most preferably 3.0 or less. If the molecular weight distribution is 6.0 or less, the content of larger and smaller molecular weights will be reduced compared to the molecular weight of the designed polymer, thereby obtaining an adhesive material with excellent adhesion, flexibility, and resilience. The molecular weight distribution is 1.0 or more. The smaller the molecular weight distribution, the narrower the width of the molecular weight distribution, and the width of the molecular weight distribution is narrowest when the value is 1.0. In addition, in this invention, the molecular weight distribution is a value calculated by (weight average molecular weight (Mw)) / (number average molecular weight (Mn)), and the methods for measuring Mw and Mn will be described later.

[0030] (Polymer with cross-linked structure (X)) The adhesive material contains a polymer (X) with a cross-linked structure. The polymer (X) with the cross-linked structure is obtained by subjecting an adhesive composition to a cross-linking reaction, the adhesive composition containing: a polymer component containing a polymer having a first reactive group and a cross-linking component having a second reactive group that reacts with the first reactive group.

[0031] The polymer (X) having the crosslinking structure is preferably obtained by subjecting an adhesive composition to a crosslinking reaction, the adhesive composition comprising: a (meth)acrylic polymer (A) having a first reactive group with a weight average molecular weight of 600,000 or more and 3 million or less (hereinafter referred to as "(meth)acrylic polymer (A)"); a (meth)acrylic polymer (B) having a weight average molecular weight (Mw) of 100,000 or more and 800,000 or less (hereinafter referred to as "(meth)acrylic polymer (B)"); and a crosslinking agent having a second reactive group that reacts with the first reactive group.

[0032] The difference (MwA - MwB) between the weight average molecular weight (MwA) of the (meth)acrylic polymer (A) and the weight average molecular weight (MwB) of the (meth)acrylic polymer (B) is preferably 500,000 or more, more preferably 700,000 or more, most preferably 1,000,000 or more, more preferably 2,900,000 or less, more preferably 2,500,000 or less, and most preferably 2,200,000 or less. If the difference (MwA - MwB) is 500,000 or more, then even if the (meth)acrylic polymer (B) has a first reactive group, it can selectively allow a crosslinking agent with a second reactive group to react with the (meth)acrylic polymer (A). If it is 2,900,000 or less, then the (meth)acrylic polymer (A) and the (meth)acrylic polymer (B) can be uniformly mixed.

[0033] The weight average molecular weight (MwA) of the (meth)acrylic polymer (A) to the weight average molecular weight (MwB) of the (meth)acrylic polymer (B) (MwA / MwB) is preferably 1.9 or more, more preferably 3.6 or more, most preferably 6.0 or more, more preferably 18.0 or less, more preferably 15.0 or less, and most preferably 13.0 or less. If the ratio (MwA / MwB) is 1.9 or more, the (meth)acrylic polymer (B) can selectively react with the (meth)acrylic polymer (A) even if it has a first reactive group. If it is 18.0 or less, the (meth)acrylic polymer (A) and the (meth)acrylic polymer (B) can be uniformly mixed during coating.

[0034] The (meth)acrylic polymer (B) may or may not have a first reactive group. That is, as a combination of the (meth)acrylic polymer (A) and the (meth)acrylic polymer (B), examples include a (meth)acrylic polymer (A) having a first reactive group with a weight average molecular weight of 600,000 or more and 3 million or less, and a (meth)acrylic polymer (B) having a weight average molecular weight (Mw) of 100,000 or more and 800,000 or less, and not having a first reactive group; and a (meth)acrylic polymer (A) having a first reactive group with a weight average molecular weight of 600,000 or more and 3 million or less, and a (meth)acrylic polymer (B) having a first reactive group with a weight average molecular weight (Mw) of 100,000 or more and 800,000 or less.

[0035] The (meth)acrylic polymer (A) and the crosslinking agent are the main components that form the crosslinked structure. Additionally, the colloidal component contains components in the (meth)acrylic polymer (A) that were not crosslinked during the crosslinking reaction, or components with a low degree of crosslinking that can be extracted by solvents. The (meth)acrylic polymer (B) that does not have a first reactive group mainly becomes the colloidal component. If the (meth)acrylic polymer (B) has a first reactive group, the colloidal component contains components in the (meth)acrylic polymer (B) that were not crosslinked during the crosslinking reaction, or components with a low degree of crosslinking that can be extracted by solvents.

[0036] ((Meth)acrylate polymer (A)) The (meth)acrylate polymer (A) is mainly composed of building units derived from (meth)acrylate monomers (50% by mass or more). The (meth)acrylate polymer (A) may be one type or two or more types. Furthermore, the (meth)acrylate polymer (A) may contain building units derived from vinyl monomers other than (meth)acrylate monomers. The content of building units derived from (meth)acrylate monomers in the (meth)acrylate polymer (A) is preferably 80% by mass or more, and more preferably 90% by mass or more per 100% by mass of the polymer. Alternatively, the (meth)acrylate polymer (A) may also be composed solely of building units derived from (meth)acrylate monomers.

[0037] The (meth)acrylate polymer (A) is preferably a (meth)acrylate copolymer. The (meth)acrylate copolymer is any copolymer in which the building units derived from (meth)acrylate are the main component (50% by mass), and may contain building units derived from vinyl monomers other than (meth)acrylate. The (meth)acrylate is an ester compound in which the hydrogen atoms of the carboxyl groups of (meth)acrylate are replaced with organic groups. The content of building units derived from (meth)acrylate in the (meth)acrylate polymer (A) is preferably 80% by mass or more, and more preferably 90% by mass or more, out of 100% by mass of the polymer.

[0038] The (meth)acrylic acid polymer (A) has a first reactive group. This first reactive group is a functional group that is reactive with the second reactive group of the crosslinking agent described later. Examples of functional groups that can be the first reactive group include reactive functional groups. Examples of the first reactive group include hydroxyl, carboxyl, and epoxy groups, with hydroxyl and / or carboxyl groups being more preferred.

[0039] The amount of the first reactive group in the (meth)acrylic polymer (A) is preferably 0.002 mmol / g or more, more preferably 0.005 mmol / g or more, most preferably 0.010 mmol / g or more, more preferably 1.0 mmol / g or less, more preferably 0.8 mmol / g or less, and most preferably 0.7 mmol / g or less. If the amount of the first reactive group is 0.002 mmol / g or more, the resulting adhesive will be appropriately cross-linked and exhibit suitable resilience. If it is 1.0 mmol / g or less, the distance between the cross-linking points of the resulting adhesive will be sufficiently long, resulting in excellent flexibility.

[0040] In the case where the hydroxyl group is the first reactive group, the (meth)acrylic polymer (A) preferably further has a carboxyl group as a functional group other than the first reactive group. In this case, the amount of carboxyl group in the (meth)acrylic polymer (A) is preferably 0.08 mmol / g or more, more preferably 0.16 mmol / g or more, most preferably 0.32 mmol / g or more, preferably 1.3 mmol / g or less, more preferably 0.8 mmol / g or less, and most preferably 0.6 mmol / g or less.

[0041] Furthermore, when the hydroxyl group is the first reactive group, and the (meth)acrylic polymer (A) has both carboxyl and hydroxyl groups, the molar ratio (carboxyl / hydroxyl) of the (meth)acrylic polymer (A) per unit mass of carboxyl to hydroxyl groups is preferably 4 or more, more preferably 8 or more, most preferably 16 or more, more preferably 60 or less, more preferably 40 or less, and most preferably 30 or less. If the molar ratio (carboxyl / hydroxyl) is within the above range, it will have high resilience and become an adhesive layer with a good balance of adhesion and flexibility.

[0042] In the case where the carboxyl group is the first reactive group, the (meth)acrylic polymer (A) preferably further has a hydroxyl group as a functional group other than the first reactive group. In this case, the amount of hydroxyl group in the (meth)acrylic polymer (A) is preferably 0.01 mmol / g or more, more preferably 0.02 mmol / g or more, most preferably 0.04 mmol / g or more, preferably 0.25 mmol / g or less, more preferably 0.20 mmol / g or less, and most preferably 0.15 mmol / g or less.

[0043] Furthermore, since the carboxyl group is the first reactive group, and the (meth)acrylic polymer (A) has both carboxyl and hydroxyl groups, the molar ratio (carboxyl / hydroxyl) of the (meth)acrylic polymer (A) per unit mass is preferably 3.0 or more, more preferably 3.5 or more, most preferably 4.0 or more, more preferably 30.0 or less, more preferably 25.0 or less, and most preferably 20.0 or less. If the molar ratio (carboxyl / hydroxyl) is within the above range, it will have high resilience and become an adhesive layer with a good balance between adhesion and flexibility.

[0044] The (meth)acrylic polymer (A) can be any of a random copolymer, a block copolymer, or a graft copolymer, preferably a random copolymer.

[0045] The weight average molecular weight (MwA) of the (meth)acrylic polymer (A) is preferably 600,000 or more, more preferably 750,000 or more, even more preferably 900,000 or more, most preferably 1,000,000 or more, preferably 3,000,000 or less, more preferably 2,800,000 or less, and most preferably 2,600,000 or less. If the MwA of the (meth)acrylic polymer (A) is 600,000 or more, the number of primary reactive groups per branch of the (meth)acrylic polymer (A) will increase, making it easier to meet the aforementioned gelation rate. If it is 3,000,000 or less, the coating workability of the adhesive composition will become better. The method for determining the weight average molecular weight (Mw) will be described later.

[0046] The molecular weight distribution (Mw / Mn) of the (meth)acrylic polymer (A) is 3.0 or less, preferably 2.7 or less, more preferably 2.5 or less, and most preferably 2.1 or less. The smaller the Mw / Mn, the narrower the molecular weight distribution, with the narrowest width at a value of 1.0. If the Mw / Mn is 3.0 or less, the content of larger and smaller molecular weights will be reduced relative to the designed molecular weight of the polymer, thereby obtaining an adhesive material with excellent adhesion and resilience.

[0047] The glass transition temperature (Tg) of the (meth)acrylic polymer (A) is preferably above -70°C, more preferably above -60°C, more preferably below 0°C, more preferably below -10°C, and most preferably below -20°C. If the Tg is above -70°C, the adhesive will have sufficient cohesion, which will improve the durability of the formed adhesive. If the Tg is below 0°C, the adhesion of the adhesive to the substrate will be improved, and peeling at low temperatures will be suppressed, thereby improving durability.

[0048] The Tg of the (meth)acrylic polymer (A) is a value calculated using the following FOX formula (Equation (1)). In Equation (1), Tg represents the glass transition temperature (°C) of the polymer. Tgi shows the glass transition temperature (°C) at which vinyl monomer i forms the polymer. Wi shows the mass ratio of vinyl monomer i among all vinyl monomers forming the polymer, ΣWi = 1. i is a natural number from 1 to n.

[0049] (Formula 1)

[0050] ((Meth)acrylate polymer (B)) The (meth)acrylate polymer (B) is mainly composed of building units derived from (meth)acrylate monomers (50% by mass or more). The (meth)acrylate polymer (B) may be one type or two or more types. Furthermore, the (meth)acrylate polymer (B) may contain building units derived from vinyl monomers other than (meth)acrylate monomers. The content of building units derived from (meth)acrylate monomers in the (meth)acrylate polymer (B) is preferably 80% by mass or more, and more preferably 90% by mass or more per 100% by mass of the polymer. Alternatively, the (meth)acrylate polymer (B) may be composed solely of building units derived from (meth)acrylate monomers.

[0051] The (meth)acrylate polymer (B) is preferably a (meth)acrylate copolymer. The (meth)acrylate copolymer is any copolymer in which the building units derived from (meth)acrylate are the main component (50% by mass), and may contain building units derived from vinyl monomers other than (meth)acrylate. The content of building units derived from (meth)acrylate in the (meth)acrylate polymer (B) is preferably 80% by mass or more, and more preferably 90% by mass or more per 100% by mass of the polymer.

[0052] The (meth)acrylic polymer (B) can be any of a random copolymer, a block copolymer, or a graft copolymer, preferably a random copolymer.

[0053] The weight average molecular weight (MwB) of the (meth)acrylic polymer (B) is preferably 100,000 or more, more preferably 130,000 or more, most preferably 150,000 or more, more preferably 800,000 or less, more preferably less than 600,000, even more preferably less than 500,000, and most preferably less than 400,000. If the MwB of the (meth)acrylic polymer (B) is within this range, it tends to form an adhesive material with excellent adhesion.

[0054] The molecular weight distribution (Mw / Mn) of the (meth)acrylic polymer (B) is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and most preferably 2.5 or less. The smaller the Mw / Mn, the narrower the molecular weight distribution, resulting in a polymer with uniform molecular weight. The narrowest molecular weight distribution is achieved when the Mw / Mn value is 1.0. If the Mw / Mn is 5.0 or less, the content of larger and smaller molecular weight molecules will be reduced compared to the designed molecular weight of the polymer, thereby obtaining an adhesive material with excellent adhesion.

[0055] The glass transition temperature (Tg) of the (meth)acrylic polymer (B) is preferably above -70°C, more preferably above -60°C, more preferably below 0°C, more preferably below -10°C, and most preferably below -20°C. If the Tg is above -70°C, the adhesive will have sufficient cohesion, which will improve the durability of the formed adhesive. If the Tg is below 0°C, the adhesion of the adhesive to the substrate will be improved, and peeling at low temperatures will be suppressed, thereby improving durability.

[0056] In this adhesive composition, the amount of (meth)acrylic polymer (B) relative to 100 parts by weight of (meth)acrylic polymer (A) is preferably 30 parts by weight or more, more preferably 50 parts by weight or more, most preferably 70 parts by weight or more, more preferably 300 parts by weight or less, more preferably 250 parts by weight or less, and most preferably 200 parts by weight or less. If the amount of (meth)acrylic polymer (B) is 30 parts by weight or more, an adhesive material with excellent flexibility can be formed; if it is 300 parts by weight or less, an adhesive material with excellent resilience can be formed.

[0057] The (meth)acrylic polymer (B) may or may not have a first reactive group. The (meth)acrylic polymer (B) may be used in combination to obtain polymers having the first reactive group and polymers not having the first reactive group. Examples of the first reactive group include hydroxyl, carboxyl, and epoxy groups, with hydroxyl and / or carboxyl groups being preferred.

[0058] When the (meth)acrylic polymer (B) has a first reactive group, the amount of the first reactive group in the (meth)acrylic polymer (B) is preferably 0.002 mmol / g or more, more preferably 0.005 mmol / g or more, most preferably 0.010 mmol / g or more, preferably 1.0 mmol / g or less, more preferably 0.8 mmol / g or less, and most preferably 0.7 mmol / g or less. If the amount of the first reactive group is 0.002 mmol / g or more, the adhesive material will be appropriately crosslinked and suitable resilience will be found. If it is 1.0 mmol / g or less, the distance between the crosslinking points of the formed adhesive material will be sufficiently long and have excellent flexibility.

[0059] When the (meth)acrylic polymer (B) has a first reactive group, the total amount of the first reactive group in the (meth)acrylic polymer (A) and (meth)acrylic polymer (B) is preferably 0.002 mmol / g or more, more preferably 0.005 mmol / g or more, most preferably 0.010 mmol / g or more, preferably 1.0 mmol / g or less, more preferably 0.8 mmol / g or less, and most preferably 0.7 mmol / g or less. If the amount of the first reactive group is 0.002 mmol / g or more, the adhesive material will be appropriately crosslinked and suitable resilience will be found. If it is 1.0 mmol / g or less, the distance between the crosslinking points of the formed adhesive material will be sufficiently long and have excellent flexibility.

[0060] In the case where the hydroxyl group is the first reactive group, the (meth)acrylic polymer (B) preferably has a carboxyl group. Adhesive materials formed from the (meth)acrylic polymer (B) having carboxyl groups exhibit excellent adhesion. In this case, the amount of carboxyl groups in the (meth)acrylic polymer (B) is preferably 0.002 mmol / g, more preferably 0.005 mmol / g, most preferably 0.010 mmol / g or more, preferably 1.0 mmol / g or less, more preferably 0.8 mmol / g or less, and most preferably 0.7 mmol / g or less.

[0061] The adhesive composition may also contain other polymer components besides the (meth)acrylate polymer (A) and (meth)acrylate polymer (B). The total content of the (meth)acrylate polymer (A) and (meth)acrylate polymer (B) in the adhesive composition is preferably 70% by mass or more, more preferably 80% by mass or more, and most preferably 90% by mass or more. The adhesive composition may also contain only the (meth)acrylate polymer (A) and (meth)acrylate polymer (B) as polymer components.

[0062] Hereinafter, the constituent units that constitute the (meth)acrylic polymer (A) and (meth)acrylic polymer (B) will be explained.

[0063] The (meth)acrylic polymer (A) has a first reactive group. That is, the (meth)acrylic polymer (A) contains a building unit (a-1) having a first reactive group in its structure. The (meth)acrylic polymer (B) may or may not contain a building unit (a-1) having a first reactive group in its structure.

[0064] The structural unit (a-1) having the first reactive group may be only one type, or it may be two or more types. The first reactive group may have a structural unit derived from a (meth)acrylic acid monomer (preferably a (meth)acrylate monomer and / or (meth)acrylic acid) or a structural unit derived from an vinyl monomer other than a (meth)acrylic acid monomer. That is, the structural unit (a-1) having the first reactive group includes a structural unit derived from a (meth)acrylic acid monomer (preferably an acrylate monomer and / or (meth)acrylic acid) having the first reactive group, or a structural unit derived from an vinyl monomer other than a (meth)acrylic acid monomer having the first reactive group.

[0065] The content of the building unit (building unit (a-1) with the first reactive group) from the vinyl monomer having the first reactive group in the (meth)acrylic polymer (A) is preferably 0.03% by mass or more, more preferably 0.09% by mass or more, most preferably 0.15% by mass or more, more preferably 6% by mass or less, more preferably 4% by mass or less, and most preferably 3% by mass or less in 100% by mass of the polymer content. If the content of the building unit (a-1) in the (meth)acrylic polymer (A) is within the above range, an adhesive material with an excellent balance between adhesion and durability relative to the adhesive can be formed. In addition, the vinyl monomer having the first reactive group includes vinyl monomers other than (meth)acrylic monomers having the first reactive group.

[0066] When the (meth)acrylic polymer (B) has a first reactive group, the content of the building unit (building unit (a-1) with the first reactive group) from the vinyl monomer having the first reactive group in the (meth)acrylic polymer (B) is preferably 0.03% by mass or more, more preferably 0.09% by mass or more, most preferably 0.15% by mass or more, preferably 6% by mass or less, more preferably 4% by mass or less, and most preferably 3% by mass or less. If the content of the building unit (a-1) in the (meth)acrylic polymer (B) is within the above range, an adhesive material with an excellent balance between adhesion and durability relative to the adherend can be formed. In addition, the vinyl monomer having the first reactive group includes vinyl monomers other than (meth)acrylic monomers having the first reactive group.

[0067] Examples of the (meth)acrylic acid monomer include (b1): a (meth)acrylic acid monomer without a functional group that can be a first reactive group; and (b2): a (meth)acrylic acid monomer with a functional group that can be a first reactive group. These monomers can be used alone or in combination of two or more. Preferably, the (b1) (meth)acrylic acid monomer is (b1-1): a (meth)acrylic ester monomer without a functional group that can be a first reactive group. Examples of the (b2) (meth)acrylic acid monomer include (b2-1): a (meth)acrylic ester monomer with a functional group that can be a first reactive group, and (meth)acrylic acid.

[0068] As in (b1): Examples of (meth)acrylate monomers that do not have a functional group that can be a first reactive group include: (meth)acrylates having a straight-chain alkyl group, (meth)acrylates having a branched-chain alkyl group, (meth)acrylates having an alkoxy group, (meth)acrylates having an alicyclic hydrocarbon group, (meth)acrylates having an aromatic group, (meth)acrylates having a tertiary amino group, and (meth)acrylamides. Preferably, they are selected from at least one of the following groups: (meth)acrylates having a straight-chain alkyl group, (meth)acrylates having a branched-chain alkyl group, (meth)acrylates having an alicyclic hydrocarbon group, (meth)acrylates having an aromatic group, and (meth)acrylamides.

[0069] Preferably, the (meth)acrylate having a straight-chain alkyl group is a (meth)acrylate having a straight-chain alkyl group with 1 to 20 carbon atoms, more preferably, it is a (meth)acrylate having a straight-chain alkyl group with 1 to 15 carbon atoms, even more preferably, it is a (meth)acrylate having a straight-chain alkyl group with 1 to 12 carbon atoms, and most preferably, it is a (meth)acrylate having a straight-chain alkyl group with 4 to 12 carbon atoms. Examples of (meth)acrylates having straight-chain alkyl groups include: meth (meth)acrylates, ethyl (meth)acrylates, n-propyl (meth)acrylates, n-butyl (meth)acrylates, n-hexyl (meth)acrylates, n-octyl (meth)acrylates, n-nonyl (meth)acrylates, n-decyl (meth)acrylates, n-dodecyl (meth)acrylates, n-octadecyl (meth)acrylates, and other straight-chain alkyl (meth)acrylates.

[0070] As the (meth)acrylate having branched alkyl groups, it is preferable to be a (meth)acrylate having branched alkyl groups with 3 to 20 carbon atoms, more preferably a (meth)acrylate having branched alkyl groups with 3 to 12 carbon atoms, and most preferably a (meth)acrylate having branched alkyl groups with 3 to 10 carbon atoms. Examples of such (meth)acrylates having branched alkyl groups include isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, and other (meth)acrylate branched alkyl esters.

[0071] Examples of (meth)acrylates having alkoxy groups include methoxyethyl methacrylate, ethoxyethyl methacrylate, and other (meth)acrylate oxyalkyl alkyl esters.

[0072] Examples of (meth)acrylates having an alicyclic hydrocarbon group include: (meth)acrylates having a cyclic alkyl group and (meth)acrylates having a polycyclic structure. Preferably, the (meth)acrylate having a cyclic alkyl group is a (meth)acrylate having a cyclic alkyl group with 6 to 12 carbon atoms. Examples of cyclic alkyl groups include those having a monocyclic structure (e.g., cycloalkyl groups), and may also have a chain portion. Specific examples of (meth)acrylates having a monocyclic alkyl group include cyclohexyl methacrylate, methylcyclohexyl methacrylate, cyclododecyl methacrylate, and other cyclic alkyl methacrylates.

[0073] Preferably, the (meth)acrylate having a polycyclic structure is a (meth)acrylate having a polycyclic structure with 6 to 12 carbon atoms. Examples of polycyclic structures include cyclic alkyl groups with bridged ring structures (e.g., adamantyl, norcamphenyl, isocamphenyl), and chain-like portions may also be present. Specific examples of (meth)acrylates having a polycyclic structure include: camphenyl methacrylate, isocamphenyl methacrylate, 1-adamantyl methacrylate, 2-adamantyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, norcamphenyl methacrylate, dicyclopentyl methacrylate, dicyclopentenyl ethyl methacrylate, dicyclopentadienyloxyethyl methacrylate, etc.

[0074] Preferably, the (meth)acrylate having an aromatic group is a (meth)acrylate having an aromatic group with 6 to 12 carbon atoms. Examples of the aromatic group include aromatic groups, and also those having a chain-like portion such as alkyl aromatic groups, propylamino alkyl groups, or aryloxyalkyl groups. Examples of the (meth)acrylate having an aromatic group include compounds with an aromatic group directly bonded to an acryloxy group, compounds with an aryl alkyl group directly bonded to an acryloxy group, and compounds with an alkyl aromatic group directly bonded to an acryloxy group. The aromatic group preferably has 6 to 12 carbon atoms. The aryl alkyl group preferably has 6 to 12 carbon atoms. The alkyl aromatic group preferably has 6 to 12 carbon atoms. Examples of (meth)acrylates having an aromatic group include benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate isobutyrate.

[0075] Examples of meth acrylates having tertiary amino groups include: 2-(dimethylamine)ethyl methacrylate, N,N-dimethylaminepropyl methacrylate, etc.

[0076] Examples of this (meth)acrylamide class include: N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-triisopropyl (meth)acrylamide, (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-tert-butyl (meth)acrylamide, N-octyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, 4-(meth)acrylamide, etc. The (meth)acrylamide is a (meth)acrylamide acid body, but is not contained in the (meth)acrylate monomer.

[0077] Examples of (meth)acrylic acid monomers having a functional group that can serve as the first reactive group in (b2) include: (meth)acrylic acid monomers having a hydroxyl group (preferably (meth)acrylate monomers), (meth)acrylic acid monomers having a carboxyl group (preferably (meth)acrylic acid), and (meth)acrylic acid monomers having an epoxy group (preferably (meth)acrylate monomers). Among these, (meth)acrylic acid monomers having a hydroxyl group and / or (meth)acrylic acid monomers having a carboxyl group are preferred, and (meth)acrylic acid monomers having an epoxy group are even more preferred.

[0078] Examples of hydroxyl-containing (meth)acrylate monomers include: hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; hydroxyalkylcyclohexyl (meth)acrylates such as (4-hydroxymethylcyclohexyl)meth (meth)acrylate; and caprolactone additives of hydroxyalkyl (meth)acrylates. Among these, hydroxyalkyl (meth)acrylates are preferred, and (meth)acrylates having a hydroxyalkyl group having 1 to 5 carbon atoms are even more preferred.

[0079] Examples of the (meth)acrylic acid monomer having a carboxyl group include: carboxyethyl (meth)acrylic acid ester, carboxypentyl (meth)acrylic acid ester, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl acetal ester, 2-(meth)acryloyloxyethyl phthalate, etc., monomers formed by reacting carboxyethyl (meth)acrylic acid esters with anhydrides of dehydrated maleic acid, dehydrated succinic acid, dehydrated phthalic acid, etc. (e.g., 2-acryloyloxyethyl hydrosuccinate, 2-methacryloyloxyethyl hydrosuccinate, 2-(acryloyloxyethyl)ethyl hexahydrobenzoic acid, 2-methacryloyloxyethyl hexahydrobenzoic acid, 1-(2-acryloyloxyethyl) phthalic acid, 1-(methacryloyloxyethyl) phthalic acid), (meth)acrylic acid, etc.). Among these, (meth)acrylic acid ester is preferred.

[0080] Examples of (meth)acrylates having the epoxy group include: glycidyl (meth)acrylate, 3,4-epoxycyclohexyl meth (meth)acrylate, etc.

[0081] Examples of vinyl monomers other than the (meth)acrylic acid monomer include: (b3) vinyl monomers other than the (meth)acrylic acid monomer that do not have a functional group that can be a first reactive group, and (b4) vinyl monomers other than the (meth)acrylic acid monomer that have a functional group that can be a first reactive group. These monomers may be used alone or in combination of two or more.

[0082] As for the (b3) vinyl monomer other than the (meth)acrylic acid monomer that does not have a functional group that can be the first reactive group, examples include: aromatic vinyl monomers, heterocyclic vinyl monomers, vinyl carboxylic acids, vinyl monomers containing tertiary amine groups, vinyl amines, α-olefins, dienes, halogenated vinyl monomers, etc.

[0083] Examples of aromatic vinyl monomers include: styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 1-vinylnaphthalene, etc. Examples of heterocyclic vinyl monomers include: vinylthiophene, N-methyl-2-vinylpyrrole, 2-vinylpyridine, 4-vinylpyridine, etc. Examples of vinyl carboxylic acids include: vinyl acetate, trimethylvinyl acetate, vinyl benzoate, etc. Examples of tertiary amine-containing vinyl monomers include: N,N-dimethylallylamine, etc. Examples of vinyl amines include: N-vinylformamide, N-vinylacetamide, N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, etc. Examples of α-enyl hydroxyl groups include: 1-hexene, 1-octene, 1-decene, etc. Examples of this type of diene include: butadiene, isoprene, 4-methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene. Examples of this type of halogenated vinyl monomer include: vinyl fluoride, difluoroethylene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, tetrafluoropropylene, vinylidene chloride, vinyl chloride, 1-chloro-1-fluoroethylene, and 1,2-dichloro-1,2-difluoroethylene.

[0084] Examples of vinyl monomers other than (meth)acrylic acid monomers having a functional group that can be a first reactive group include: vinyl monomers having a hydroxyl group, vinyl monomers having a carboxyl group, vinyl monomers having an epoxy group, etc.

[0085] Examples of ethylene monomers having hydroxyl groups include p-hydroxystyrene and allyl alcohol. Examples of ethylene monomers having carboxyl groups include butenoic acid, maleic acid, itaconic acid, pyrocitric acid, and cinnamic acid. Examples of ethylene monomers having epoxy groups include 2-allyl ethylene oxide, glycidyl divinyl ether, and 3,4-epoxycyclohexyl divinyl ether.

[0086] The (meth)acrylate polymer (A) preferably contains (meth)acrylate building units having alkyl groups having 1 to 12 carbon atoms at a content of 70% by mass or more, more preferably 80% by mass or more, most preferably 90% by mass or more, more preferably 99% by mass or less, more preferably 97% by mass or less, and most preferably 96% by mass or less. As for the (meth)acrylate having alkyl groups having 1 to 12 carbon atoms, it is preferably a (meth)acrylate having a straight-chain alkyl group having 1 to 12 carbon atoms or a (meth)acrylate having a branched-chain alkyl group having 1 to 12 carbon atoms.

[0087] The polymerization method used to polymerize the monomer composition can be either free radical polymerization or living radical polymerization. The polymerization method for the (meth)acrylic acid polymer (A) is preferably living radical polymerization. That is, the (meth)acrylic acid polymer (A) is preferably polymerized by living radical polymerization. Similarly, the polymerization method for the (meth)acrylic acid polymer (B) is preferably living radical polymerization. That is, the (meth)acrylic acid polymer (B) is preferably polymerized by living radical polymerization. Living radical polymerization retains the simplicity and versatility of conventional free radical polymerization methods, and it is less prone to stopping reactions or chain reactions. The growth ends are not hindered by side reactions that deactivate them, thus it is preferable to easily manufacture polymers with precisely controlled molecular weight distribution and uniform composition.

[0088] (Living Radical Polymerization) Living radical polymerization methods vary depending on the method used to stabilize the polymer growth ends, and include the following methods: methods using compounds that generate nitrile radicals (nitrile radical method; NMP method); methods using metal complexes such as copper or ruthenium, with a halide compound as the polymerization initiator, where the polymerization initiator compound is used for active polymerization (ATRP method); methods using dithiocarboxylic acid esters or xanthate compounds (RAFT method); methods using organotelluric acid compounds (TERP method); methods using organoiodine compounds (ITP method); and methods using iodine compounds as the polymerization initiator compound and organic compounds such as phosphorus compounds, nitrogen compounds, oxygen compounds, or hydrocarbons as catalysts (reversible mobile catalyst polymerization; RTCP method, reversible catalyst-mediated polymerization; RCMP method), etc. Among these methods, the TEP method is preferred from the perspectives of the diversity of monomers that can be used, molecular weight control in the polymer region, and uniform composition or coloring.

[0089] The TEP method is a method that uses an organotellurium compound as a chain moving agent to polymerize a free radical polymerizable compound (ethylene monomer), such as the methods described in International Publication No. 2004 / 14848, International Publication No. 2004 / 14962, International Publication No. 2004 / 072126 and International Publication No. 2004 / 096870.

[0090] Specific polymerization methods of the TEP method are given below (a) to (d). (a) A method for polymerizing ethylene monomers using an organotellurium compound represented by formula (1). (b) A method for polymerizing ethylene monomers using a mixture of an organotellurium compound represented by formula (1) and an azo polymerization initiator. (c) A method for polymerizing ethylene monomers using a mixture of an organotellurium compound represented by formula (1) and an organoditellurium compound represented by formula (2). (d) A method for polymerizing ethylene monomers using a mixture of an organotellurium compound represented by formula (1), an azo polymerization initiator, and an organoditellurium compound represented by formula (2).

[0091] (Chemical 1) In formula (1), R1 is an alkyl, aromatic or aromatic heterocyclic group having 1 to 8 carbon atoms. R2 and R3 are each independent hydrogen atoms or alkyl groups having 1 to 8 carbon atoms. R4 is an alkyl, aromatic, aromatic heterocyclic group, alkoxy, acetyl, acetamino, oxycarbonyl, cyano, allyl or propargyl group having 1 to 8 carbon atoms. In formula (2), R1 is an alkyl, aromatic or aromatic heterocyclic group having 1 to 8 carbon atoms.

[0092] Specific examples of the organotelluric compounds represented by formula (1) include: ethyl=2-methyl-2-n-butylethanol telluryl propionate, ethyl=2-n-butylethanol telluryl propionate, (2-hydroxyethyl)=2-methyl-methylethanol telluryl propionate, etc., as described in International Publications Nos. 2004 / 14848, 2004 / 14962, 2004 / 072126 and 2004 / 096870. Specific examples of the organotelluric compounds represented by formula (2) include: dimethyl ditelluride, dibutyl ditelluride, etc. Azo polymer initiators can be used without any particular restrictions, as long as they are the same azo polymer initiators commonly used in free radical polymerization, such as 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvalerate) (ADVN), 1,1'-azobis(1-cyclohexanenitrile) (ACHN), and 2,2'-azobis(4-methoxy-2,4-dimethylvalerate) (V-70), etc.

[0093] The polymerization process involves further mixing an azo polymerization initiator and / or an organic ditellurium compound of formula (2) in a container purged with an inert gas, with the vinyl monomer and the organic tellurium compound of formula (1) for the purposes of promoting the reaction, controlling the molecular weight and molecular weight distribution corresponding to the type of vinyl monomer. Examples of inert gases include nitrogen, argon, and helium. Argon and nitrogen are preferred. The amount of vinyl monomer used in (a), (b), (c), and (d) can be adjusted appropriately according to the physical properties of the desired polymer.

[0094] The polymerization reaction can be carried out even without a solvent, but it can also be carried out by stirring the mixture using a non-protic or protic solvent commonly used in free radical polymerization. Examples of usable non-protic solvents include: acetonitrile, methyl ethyl ketone, anisole, benzene, toluene, propylene glycol methyl ether acetate, ethyl acetate, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), acetone, dioxane, chloroform, carbon tetrachloride, etc. Examples of protic solvents include: water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, hexafluoroisopropanol, diacetone alcohol, etc. Solvents can be used alone or in combination of two or more. The amount of solvent used can be adjusted appropriately; for example, it is preferably 0.01 ml to 50 ml relative to 1 g of vinyl monomer. The reaction temperature and time can be adjusted according to the molecular weight or molecular weight distribution of the resulting polymer, typically stirred for 1 minute to 100 hours at 0°C to 150°C. During this process, the pressure is usually at atmospheric pressure, but pressure can also be increased or decreased. After the polymerization reaction is complete, the desired polymer can be separated from the resulting reaction mixture by conventional separation and purification methods, removing the used solvent and residual vinyl monomer.

[0095] The growth end of the polymer obtained by the polymerization reaction is TeR1 from the tellurium compound (where R1 is the same as above). Although it may be deactivated by handling in the air after the polymerization reaction, there may still be residual tellurium atoms. Since polymers with residual tellurium atoms at the end are prone to staining and have poor thermal stability, it is preferable to remove the tellurium atoms. As methods for removing tellurium atoms, examples include: free radical reduction methods; adsorption methods using activated carbon, etc.; adsorption methods using ion exchange resins, etc., and these methods can also be combined. In addition, the other end of the polymer obtained by the polymerization reaction (the end opposite to the growth end) is in the form of -CR2R3R4 from the tellurium compound (where R2, R3 and R4 are the same as R2, R3 and R4 in formula (1)).

[0096] (Free Radical Polymerization Method) The free radical polymerization method can employ conventional methods. Examples of polymerization initiators used in the free radical polymerization method include azo-based polymerization initiators and peroxide-based polymerization initiators. Examples of azo-based polymerization initiators include: 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2-methylbutyronitrile) (AMBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis(1-cyclohexanenitrile) (ACHN), dimethyl-2,2'-azobisisobutyrate (MAIB), 4,4'-azobis(4-cyanovaleric acid) (ACVA), 1,1'-azobis(1-acetoxy-1-acetophenone), and 2,2'-azobis(2-methylbutyronitrile). (Amine), 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile) (V-70), 2,2'-azobis(2-methylformamidinylpropane) dichloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propenylamine], 2,2'-azobis(2,4,4-trimethylpentane), 2-cyano-2-propylazomethine, 2,2'-azobis(N-butyl-2-methylpropenylamine), or 2,2'-azobis(N-cyclohexyl-2-methylpropenylamine), etc.

[0097] The polymerization reaction can be carried out even without a solvent, but it can also be carried out by stirring the mixture using a non-protic or protic solvent commonly used in free radical polymerization. Examples of usable non-protic solvents include: acetonitrile, anisole, benzene, toluene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), acetone, 2-butanone (methyl ethyl ketone), dioxane, chloroform, carbon tetrachloride, tetrahydrofuran (THF), ethyl acetate, propylene glycol methyl ether acetate, or trifluorotoluene, etc. Examples of protic solvents include: water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, hexafluoroisopropanol, or diacetone alcohol, etc.

[0098] The amount of solvent used can be adjusted appropriately. For example, it is preferably 0.01 ml or more relative to 1 g of ethylene monomer, more preferably 0.05 ml or more, most preferably 0.1 ml or more, preferably 50 ml or less, more preferably 10 ml or less, and most preferably 1 ml or less.

[0099] The reaction temperature and reaction time can be adjusted appropriately according to the molecular weight or molecular weight distribution of the obtained polymer components. Typically, stirring is carried out at 0°C to 150°C for 1 minute to 100 hours. During this time, the pressure is usually at atmospheric pressure, but pressure can also be increased or decreased. After the polymerization reaction is complete, the desired polymer composition can be separated by using conventional separation and purification methods to remove the used solvent and residual vinyl monomers.

[0100] (Crosslinking agent) The adhesive composition contains a crosslinking agent. The crosslinking agent is a compound having two or more second reactive groups in one molecule that react with the first reactive group of the (meth)acrylic acid polymer described above. The crosslinking agent is not particularly limited, and examples include: isocyanate-based crosslinking agents, epoxy resin-based crosslinking agents, azirmonopropane-based crosslinking agents, metal chelate-based crosslinking agents, melamine resin-based crosslinking agents, urea resin-based crosslinking agents, etc. The crosslinking agent can be used alone or in combination with two or more. Among these, isocyanate-based crosslinking agents and epoxy resin-based crosslinking agents are preferred.

[0101] The crosslinking agent has an average number of 2 or more, more preferably 8 or less, and even more preferably 6 or less per molecule. The molecular weight of the crosslinking agent is preferably 200 or more, more preferably 300 or more, most preferably 400 or more, more preferably 1500 or less, more preferably 1000 or less, and most preferably 700 or less.

[0102] The content of the second reactive group of the crosslinking agent is preferably 1.5 mmol / g or more, more preferably 3 mmol / g or more, most preferably 3.7 mmol / g or more, more preferably 10 mmol / g or less, and more preferably 8 mmol / g or less. When the content of the second reactive group of the crosslinking agent is within this range, the valence of the crosslinking agent will be lower, resulting in a more uniform distribution of crosslinking points within the adhesive material, and thus a longer average distance between crosslinking points. Therefore, the resulting adhesive material will exhibit lower initial stress and higher resilience.

[0103] Examples of combinations of the first reactive group in the (A) (meth)acrylic polymer and the (B) (meth)acrylic polymer, and the second reactive group in the crosslinking agent include the following: When the second reactive group of the crosslinking agent is an isocyanate group, a hydroxyl group is an example of the first reactive group. When the second reactive group of the crosslinking agent is an epoxy group, a carboxyl group is an example of the first reactive group.

[0104] The combination of the first reactive group of the (meth)acrylic polymer (A) and the (meth)acrylic polymer (B) and the second reactive group of the crosslinking agent is preferably: (1) the first reactive group is a combination of a hydroxyl group and the second reactive group is an isocyanate group; (2) the first reactive group is a carboxyl group and the second reactive group is an epoxy group.

[0105] (Isocyanate-based crosslinking agent) An isocyanate-based crosslinking agent is a compound having two isocyanate groups as second reactive groups in one molecule (including isocyanate regenerated functional groups that temporarily protect the isocyanate groups by means of plugging agents or quantitative separation). The isocyanate-based crosslinking agent can be used alone or in combination of two or more.

[0106] Examples of isocyanate-based crosslinking agents include: aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and multifunctionalized polyisocyanates that are adducts of these polyols, are bonded to isocyanurates, biurets, urethanes, etc. Specifically, examples include: compounds having two isocyanate groups in one molecule (including isocyanate regenerated functional groups that temporarily protect the isocyanate groups by means of plugging agents or quantitative expansion) (difunctional isocyanate crosslinking agents); compounds having three isocyanate groups in one molecule (including isocyanate regenerated functional groups that temporarily protect the isocyanate groups by means of plugging agents or quantitative expansion) (trifunctional isocyanate crosslinking agents); and compounds having six isocyanate groups in one molecule (including isocyanate regenerated functional groups that temporarily protect the isocyanate groups by means of plugging agents or quantitative expansion) (hexafunctional isocyanate crosslinking agents).

[0107] Examples of diisocyanate-based crosslinking agents with difunctional groups include aliphatic diisocyanate compounds, alicyclic diisocyanate compounds, and aromatic diisocyanate compounds. Additions of these diisocyanate compounds to diol compounds can also be used. Diisocyanate compounds are compounds represented by the general formula "O=C=N-X-N=C=O" (where X is a divalent aliphatic group, a divalent alicyclic group, or a divalent aromatic group). Diol compounds are compounds represented by the general formula "HO-Y-OH" (where Y is a divalent aliphatic group, a divalent alicyclic group, or a divalent aromatic group).

[0108] Examples of aliphatic diisocyanate compounds include: ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, etc., preferably aliphatic diisocyanate compounds with 4 to 30 carbon atoms, and more preferably aliphatic diisocyanate compounds with 4 to 10 carbon atoms.

[0109] Examples of alicyclic diisocyanate compounds include isoflavone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylene diisocyanate, hydrogenated methylene phenyl diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate, among which alicyclic diisocyanate compounds having 7 to 30 carbon atoms are preferred.

[0110] Examples of aromatic diisocyanate compounds include: phenylene diisocyanate, toluene diisocyanate, xylene diisocyanate, naphthyl diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, diphenylpropane diisocyanate, etc., preferably aromatic diisocyanate compounds with 8 to 30 carbon atoms.

[0111] Examples of such diol compounds include aliphatic diol compounds such as 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, polyethylene glycol, and polypropylene glycol, preferably aliphatic diol compounds having 3 to 10 carbon atoms.

[0112] Examples of trifunctional isocyanate crosslinking agents and hexafunctional isocyanate crosslinking agents include: adducts of diisocyanate compounds, biuret bodies of diisocyanate compounds, and isocyanurate bodies of diisocyanate compounds (cyclic polymorphs of diisocyanate compounds).

[0113] Preferably, the isocyanate-based crosslinking agent does not have an aromatic ring. In particular, the isocyanate-based crosslinking agent is preferably: a difunctional isocyanate-based crosslinking agent selected from aliphatic diisocyanate compounds and adducts of aliphatic diisocyanate compounds and aliphatic diol compounds; or a trifunctional or hexafunctional isocyanate-based crosslinking agent selected from adducts of aliphatic diisocyanate compounds, biuret forms of aliphatic diisocyanate compounds, and isocyanurate forms of aliphatic diisocyanate compounds.

[0114] (Epoxy Resin-based Crosslinking Agent) An epoxy resin-based crosslinking agent is a compound having two or more epoxy groups as second reactive groups in one molecule. This epoxy resin-based crosslinking agent can be used alone or in combination of two or more.

[0115] Examples of epoxy resin crosslinking agents include: aliphatic epoxy resin compounds, alicyclic epoxy resin compounds, aromatic epoxy resin compounds, heterocyclic epoxy resin compounds, etc.

[0116] Examples of aliphatic epoxy resin compounds include: ethylene glycol propylene dioxide ether, diethylene glycol propylene dioxide ether, trimethylolpropane propylene dioxide ether, trimethylolpropane polyoxypropylene ether, diglycidylamine, neopentyl glycol propylene dioxide ether, propylene glycol propylene dioxide ether, polyethylene glycol propylene dioxide ether, polypropylene glycol propylene dioxide ether, sorbitol polyoxypropylene ether, glycerol polyoxypropylene ether, neopentyl tetrahydric alcohol polyoxypropylene ether, glycerol dioxypropylene ether, glycerol trioxypropylene ether, polyglycerol polyoxypropylene ether, adipic acid dioxypropylene ether, 1,3-bis(N,N-diepoxypropylaminomethyl)cyclohexane, etc.

[0117] Examples of this alicyclic epoxy resin compound include: 1,3-bis(N,N'-diepoxypropylaminomethyl)cyclohexane, 1,6-hexanediol diepoxypropyl ether, N,N,N',N'-tetraepoxypropyl-m-phenylenediamine, etc.

[0118] Examples of aromatic epoxy resin compounds include: bisphenol A epichlorohydrin type epoxy resin, diglycidyl aniline, o-phthalic acid diglycidyl ether, resorcinol diglycidyl ether, bisphenol-S-d-diclycidyl ether, etc.

[0119] Examples of this heterocyclic epoxy resin compound include: triepoxypropyltris(2-hydroxyethyl) isocyanate, 1,3,5-tris-(2,3-epoxybutyl)-isocyanate, 1,3,5-tris(3,4-epoxybutyl)-isocyanate, 1,3,5-tris-(4,5-epoxypentyl)-isocyanate, sorbitan polyglycidyl ester, etc.

[0120] Preferably, the epoxy resin crosslinking agent is a compound having two epoxy groups per molecule (difunctional epoxy resin crosslinking agent), a compound having three epoxy groups per molecule (trifunctional epoxy resin crosslinking agent), or a compound having four epoxy groups per molecule (tetrafunctional epoxy resin crosslinking agent). As long as the crosslinking agent is a difunctional, trifunctional, or tetrafunctional epoxy resin crosslinking agent, the crosslinking points will be uniformly distributed within the adhesive material, resulting in a longer average distance between crosslinking points. Therefore, the resulting adhesive material will exhibit lower initial stress and higher resilience.

[0121] The adhesive composition preferably contains only an isocyanate-based crosslinking agent or an epoxy resin-based crosslinking agent as the crosslinking agent. When only an isocyanate-based crosslinking agent is used as the crosslinking agent, it is preferable that one molecule contains only a difunctional isocyanate crosslinking agent having two isocyanate groups, one molecule contains only a trifunctional isocyanate crosslinking agent having three isocyanate groups, or one molecule contains only a hexafunctional isocyanate crosslinking agent having six isocyanate groups. Furthermore, when only an epoxy resin-based crosslinking agent is used as the crosslinking agent, it is preferable that one molecule contains only a difunctional epoxy resin crosslinking agent having two epoxy groups, one molecule contains only a trifunctional epoxy resin crosslinking agent having three epoxy groups, or one molecule contains only a tetrafunctional epoxy resin crosslinking agent having four epoxy groups.

[0122] The content of the crosslinking agent in the adhesive composition is preferably 0.05 parts by mass or more, more preferably 0.07 parts by mass or more, more preferably 0.4 parts by mass or less, and more preferably 0.3 parts by mass or less, relative to 100 parts by mass of the total polymer components. As long as the content of the crosslinking agent is within the above range, the flexibility and resilience will be within an appropriate range.

[0123] The molar ratio (molar amount of first reactive group / molar amount of second reactive group) between the second reactive group of the crosslinking agent and the first reactive group of the (meth)acrylic polymer in the polymer component is preferably 1 or more, more preferably 1.5 or more, most preferably 2.0 or more, preferably 80 or less, more preferably 50 or less, even more preferably 30 or less, and most preferably 20 or less. When the molar ratio is 1 or more, the crosslinking agent will not react excessively or insufficiently, resulting in no excess of the second reactive group and thus high flexibility. When it is 80 or less, the reaction can proceed sufficiently, resulting in high resilience.

[0124] (Other Additives) This adhesive composition may be used with the addition of other additives besides the polymer component and crosslinking agent. Examples of other additives include: crosslinking accelerators, crosslinking retarders, tackifiers, polymerizable compounds, photopolymerization initiators, silane coupling agents, plasticizers, softeners, release agents, dyes, pigments, colorants, fluorescent whitening agents, antistatic agents, wetting agents, surfactants, tackifiers, mildew inhibitors, preservatives, oxygen absorbers, ultraviolet absorbers, antioxidants, near-infrared absorbers, water-soluble matting agents, fragrances, metal non-reactive agents, nucleating agents, alkylating agents, flame retardants, lubricants, processing aids, etc. These can be appropriately selected and used in combination according to the application or purpose of the adhesive material.

[0125] (Cross-linking accelerator) This adhesive composition can be used in conjunction with a cross-linking accelerator as needed. Examples of cross-linking accelerators include organotin compounds and metal chelating compounds. The cross-linking accelerator can be used alone or in combination with two or more.

[0126] Examples of such organotin compounds include dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dioctyl ester. This metal chelate is a complex in which ligands with two or more coordinating atoms form a ring and bind to a central metal.

[0127] The amount of crosslinking accelerator in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, most preferably 0.04 parts by mass or more, preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and most preferably 0.3 parts by mass or less, relative to 100 parts by mass of the polymer component. By ensuring that the crosslinking accelerator is within this range, excellent crosslinking promotion effect can be obtained.

[0128] (Crosslinking Delay Agent) A crosslinking delay agent may be used in conjunction with this adhesive composition as needed. This crosslinking delay agent is a compound that, by blocking the functional groups of the crosslinking agent in the adhesive composition containing the crosslinking agent, can suppress excessive viscosity increases in the adhesive composition. The type of crosslinking delay agent is not particularly limited; for example, β-diketones such as acetone, hexane-2,4-dione, heptane-2,4-dione, and octane-2,4-dione can be used; β-keto esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, octyl acetate, oleyl acetate, dodecyl acetate, and octadecyl acetate; and benzoacetone, etc. Preferably, the crosslinking delay agent can be used as a chelating agent, and is preferably a β-diketone or β-keto ester.

[0129] The content of the crosslinking delay agent that can be incorporated into the adhesive composition is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, most preferably 0.5% by weight or more, more preferably 4.0% by weight or less, more preferably 3.0% by weight or less, and most preferably 1.5% by weight or less, relative to 100% by weight of the polymer component. By adjusting the content of the crosslinking delay agent to this range, excessive viscosity increase or gelation of the adhesive composition after incorporating the crosslinking agent into the adhesive composition can be suppressed, thereby extending the storage stability (pot life) of the adhesive composition.

[0130] (Adhesion-imparting resin) This adhesive composition may be used in combination with an adhesion-imparting resin, in addition to the polymer component, as needed. The adhesion-imparting resin is not particularly limited, and examples include: rosin-based adhesion-imparting resin, terpene-based adhesion-imparting resin, phenol-based adhesion-imparting resin, hydrocarbon-based adhesion-imparting resin, etc.

[0131] As a rosin-based adhesive resin, examples include: unmodified rosin (raw rosin) such as resin rosin, wood rosin, and oil rosin; modified rosin (polymerized rosin, stabilized rosin, non-homogenized rosin, fully hydrogenated rosin, partially hydrogenated rosin, and other chemically modified rosin) by polymerizing, homogenizing, or adding hydrogen to these unmodified rosin; and various rosin derivatives.

[0132] Examples of rosin derivatives include: rosin phenolic resins obtained by oxygen-catalyzed phenol reheat polymerization of rosin (unmodified rosin, modified rosin); rosin ester resins containing ester compounds of rosin obtained by esterifying unmodified rosin with alcohols (unmodified rosin esters); and rosin ester resins containing ester compounds of modified rosin obtained by esterifying modified rosin with alcohols (polymerized rosin esters, stabilized rosin esters, non-homogenized rosin esters, fully hydrogenated rosin esters, partially hydrogenated rosin esters, etc.); Modified rosin or unsaturated fatty acid modified rosin resin after modification with unsaturated fatty acids; unsaturated fatty acid modified rosin ester resin after modification with unsaturated fatty acids; rosin alcohol resin after carboxyl reduction treatment of unmodified rosin, modified rosin, unsaturated fatty acid modified rosin resin or unsaturated fatty acid modified rosin ester resin; metal salts of rosin resins (especially rosin ester resins) such as unmodified rosin and modified rosin.

[0133] As terpene-based adhesive resins, examples include terpene-based resins such as α-pinene polymers, β-pinene polymers, and diene polymers; modified terpene-based resins (e.g., terpene-phenol resins, styrene-modified terpene resins, aromatic-modified terpene resins, and hydrogen-modified terpene resins) obtained by modifying such terpene-based resins (phenol-modified, aromatic-modified, hydrocarbon-modified, etc.).

[0134] Examples of phenolic adhesive resins include: condensates of various phenols (e.g., phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcinol) and formaldehyde (e.g., alkylphenol resins, xylene-formaldehyde resins); soluble phenolic resins obtained by adding the phenol and formaldehyde in an alkaline catalyst; and phenolic resins obtained by condensing the phenol and formaldehyde in an acid catalyst.

[0135] Examples of hydrocarbon-based adhesive resins (petroleum-based adhesive resins) include: aliphatic hydrocarbon resins [polymers of aliphatic hydrocarbons such as 4-5 carbon hydroxyl groups or (dienes) (butene-1, isobutene, pentene-1, etc.; butadiene, 1,3-pentadiene, isoprene, etc.); aliphatic cyclic hydrocarbon resins [i.e., alicyclic hydrocarbon resins obtained by reducing and dimerizing [C4 petroleum fractions] or [C5 petroleum fractions], and cyclic diene compounds (cyclopentadiene, sesquicyclopentadiene, ethylenediene)]. Norbornene, dipeptene, etc.) aliphatic polymers or their hydrogenated additives; alicyclic hydrocarbon resins or aliphatic / aromatic petroleum resins with hydrogenated aromatic rings, etc.; aromatic hydrocarbon resins [polymers containing vinyl aromatic hydrocarbons (styrene, vinyltoluene, α-methylstyrene, indene, methylindene, etc.) with 8 to 10 carbon atoms, etc.]; aliphatic / aromatic petroleum resins (styrene-olefinic copolymers, etc.); aliphatic / alicyclic petroleum resins; hydrogenated hydrocarbon resins; coumarone resins; coumarone-indene resins, etc.

[0136] The amount of adhesive-imparting resin that can be used in the adhesive composition is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, most preferably 20 parts by weight or more, more preferably 60 parts by weight or less, more preferably 50 parts by weight or less, and most preferably 40 parts by weight or less, relative to 100 parts by weight of the polymer component. By adjusting the amount of adhesive-imparting resin to this range, sufficient adhesion to the substrate can be ensured.

[0137] (Polymerizable compound) This adhesive composition can also be combined with a polymerizable compound. By combining with a polymerizable compound, the adhesive material can be given flexibility by polymerizing the polymerizable compound in the adhesive material.

[0138] Examples of polymerizable compounds include those having two or more polymerizable groups within a single molecule. Examples of polymerizable groups include, for example, vinyl unsaturated groups. Furthermore, the polymerizable compound can be used alone or in combination with two or more types. Examples of polymerizable compounds include those having two or more (meth)acrylic groups, preferably polyfunctional monomers or polyfunctional oligomers. The number of vinyl unsaturated groups in a single molecule of the polymerizable compound is preferably two or more, preferably four or less, and more preferably three or less.

[0139] Examples of compounds having two or more (meth)acrylic groups include: hexanediol di(meth)acrylate, butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentyl tetraethylene di(meth)acrylate, neopentyl tetraethylene tri(meth)acrylate, dinepentyl tetraethylene hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, ethylene oxide isocyanate modified tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, or urea (meth)acrylate, etc.

[0140] In the case where the adhesive composition is combined with a polymeric compound, the content of the polymeric compound is preferably 0.1 parts by mass or more, more preferably 2.5 parts by mass or more, more preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, relative to 100 parts by mass of the polymer component.

[0141] (Photopolymerization Initiator) When the polymerizable compound is hardened by an active energy line, it is preferable to use a photopolymerization initiator in the adhesive component. By using a photopolymerization initiator, the reaction under active energy line irradiation can be stabilized. The photopolymerization initiator is not particularly limited to any substance that generates free radicals under light, such as acetophenones, benzoin-based initiators, diphenyl ketones, thioxanthones, and acetophosphine oxides. These photopolymerization initiators can be used alone or in combination of two or more. Furthermore, from the viewpoint of efficiently crosslinking between or within molecules, dehydrogenated diphenyl ketones and intramolecularly cleaving acetophenones are preferred photopolymerization initiators.

[0142] When the adhesive component is combined with a photopolymerization initiator, the content of the photopolymerization initiator relative to 100 parts by weight of the polymer component is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, most preferably 0.5 parts by weight or more, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and most preferably 2 parts by weight or less. As long as the content of the photopolymerization initiator is within the above range, the curing speed can be increased, and insufficient curing can be prevented.

[0143] Furthermore, the adhesive composition may also be combined with an adjuvant of the photopolymerization initiator. Examples of such adjuvants include: triethanolamine, triisopropanolamine, 4,4'-dimethylaminodiphenyl ketone (Mischel ketone), 4,4'-diethylaminodiphenyl ketone, ethyl 2-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, ethyl (n-butoxy) 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, etc. These adjuvants may be used alone or in combination of two or more.

[0144] (Silane Coupling Agent) This composition can be used in combination with a silane coupling agent as needed. There are no particular limitations on the silane coupling agent, examples of which include epoxy-containing silane coupling agents such as 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-propylaminomethyldimethoxysilane... Amino-containing silane coupling agents such as 3-methoxysilane-N-(1,3-dimethylbutylene)propylamine and N-phenyl-γ-propylaminotrimethoxysilane; methacrylic acid-containing silane coupling agents such as 3-propenyloxytrimethoxysilane and 3-methpropenyloxypropyltrimethoxysilane; isocyanate-containing silane coupling agents such as 3-isocyanatepropyltrimethoxysilane, etc.

[0145] The content of the silane coupling agent that can be incorporated into the adhesive composition is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, more preferably 1 part by weight or less, more preferably 0.8 parts by weight or less, and most preferably 0.6 parts by weight or less, relative to 100 parts by weight of the polymer composition. By adjusting the content of the silane coupling agent to this range, the water resistance at the interface when the adhesive is applied to a hydrophilic substrate such as glass can be improved.

[0146] (Plasticizer) The adhesive composition may be combined with a plasticizer in sequence. The plasticizer is not particularly limited, and examples include: oils such as paraffin oil and processing oil; liquid rubbers such as liquid polyisoprene, liquid polybutadiene, and liquid ethylene-propylene rubber; tetrahydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, butenedioic acid, maleic acid, iconic acid, citric acid, and their derivatives; dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate, diisononyl adipate (DINA), isodecanyl succinic acid, etc. One plasticizer may be used alone, or two or more may be used in combination. Among these, liquid rubber is preferred.

[0147] The weight-average molecular weight (Mw) of the liquid rubber is preferably 5,000 or more, more preferably 10,000 or more, more preferably 60,000 or less, and more preferably 50,000 or less. By adjusting the Mw of the liquid rubber to this range, an adhesive material with excellent flexibility can be formed. The method for determining the weight-average molecular weight (Mw) will be described later.

[0148] When a plasticizer is incorporated into the adhesive composition, the amount of plasticizer relative to 100 parts by weight of the polymer component is preferably 1 part by weight or more, more preferably 5 parts by weight or more, most preferably 10 parts by weight or more, preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and most preferably 30 parts by weight or less. By adjusting the amount of plasticizer to this range, an adhesive material with excellent adhesion and resilience can be formed.

[0149] (Method for manufacturing adhesive composition) The adhesive composition can be manufactured by mixing the polymer component, a crosslinking agent, and other additives as needed. The adhesive composition may contain a solvent from the manufacture of the polymer component, with further addition of appropriate solvents to form a diluted solution with a viscosity suitable for forming an adhesive layer.

[0150] Examples of solvents include: aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellulose solvents such as ethyl cellulose; and ethylene glycol ether solvents such as propylene glycol monomethyl ether. One of these solvents may be used alone, or two or more may be mixed.

[0151] The amount of solvent used should be adjusted appropriately so that the adhesive composition has a viscosity suitable for coating. Although there is no particular limitation, from the point of view of coating properties, it is preferred to be 1% to 90% by mass, more preferably 10% to 80% by mass, and most preferably 20% to 70% by mass.

[0152] The adhesive material of the present invention can be formed by coating and drying the adhesive composition. Furthermore, the coating film can be heated as needed to promote the formation of a cross-linked structure.

[0153] [Adhesive Sheet] The adhesive sheet of the present invention has a substrate sheet and an adhesive layer formed on at least one side of the substrate sheet, characterized in that the adhesive layer is the adhesive material. The adhesive layer is formed on at least one side or at least a portion of the substrate sheet. The adhesive layer may be a single layer or a multilayer structure.

[0154] Generally speaking, the term "sheet" in JIS refers to a thin, flat product whose thickness is generally small in proportion to its length and width. The term "film" generally refers to a thin, flat product whose thickness is extremely small in proportion to its length and width, and whose maximum thickness is arbitrarily defined. It is usually supplied in roll form (Japanese Industrial Standard JIS K6900). For example, in terms of thickness, narrowly defined, those with a thickness of 100 μm or more are called sheets, and those with a thickness of less than 100 μm are called films. However, the distinction between sheets and films is not fixed, and there is no need to distinguish between them in the context of this invention. Therefore, the term "sheet" in this invention also includes "film," and the term "film" also includes "sheet."

[0155] (Substrate Sheet) The substrate sheet can be appropriately selected and used according to the application of the adhesive sheet. Examples of substrate sheets include sheets composed of the following polymer materials: polyimide resin; polyester resins such as polyethylene terephthalate (PET) resin and polyethylene naphthalate (PEN) resin; polycarbonate resin; poly(meth)acrylate resin; polystyrene resin; polyamide resin; polyacrylonitrile resin; polyolefin hydroxyl resins such as polypropylene resin, polystyrene resin, polycyclic cycloene resin, and cycloolefin copolymer resin; polyphenylene sulfide resin; polyurethane resin; polyether ether resin; polyether ether ketone; polyacrylate resin; polyetherimide resin; cellulose resins such as cellulose triacetate (TAC) resin and diacetyl cellulose resin; polyvinyl chloride resin; polyvinylidene chloride resin; polyvinyl alcohol resin; polyvinyl acetate resin; fluoropolymers, etc. These polymer materials can be used alone or in combination of two or more. Of these, PET resin is preferred from the viewpoint of excellent mechanical strength or dimensional stability. Furthermore, polyimide resin is preferred from the viewpoint of excellent heat resistance. That is, PET sheets (especially biaxially stretched PET sheets) and polyimide sheets are preferred as the substrate sheet.

[0156] The thickness of the substrate sheet is not particularly limited and can be appropriately selected. Generally, it is preferred to be 5μm or more, more preferably 10μm or more, best 20μm or more, preferably less than 200μm, more preferably less than 100μm, and best 50μm or less. When the thickness is thinner than 5μm, the strength of the substrate sheet will be insufficient, and problems such as breakage may occur during peeling. Furthermore, when the thickness of the substrate sheet is greater than 200μm, problems such as high cost of the sheet itself will occur.

[0157] To improve the adhesion between the substrate sheet and the layers on its surface, surface treatments such as oxidation and texturing can be applied to one or both sides of the substrate sheet as needed. Examples of oxidation methods include corona discharge treatment, plasma treatment, wet chromic acid treatment, flame treatment, hot air treatment, and ozone / ultraviolet irradiation treatment. Examples of texturing methods include sandblasting and solvent treatment. These surface treatment methods can be appropriately selected according to the type of substrate sheet. Generally speaking, corona discharge treatment is more suitable in terms of effect and operability. Furthermore, the substrate sheet can be primed on one or both sides.

[0158] The thickness of the adhesive material (adhesive layer) formed on the substrate sheet can be appropriately set, for example, according to the required adhesion of the adhesive sheet. The thickness of the adhesive layer is generally preferably 1 μm or more, more preferably 5 μm or more, most preferably 10 μm or more, preferably 100 μm or less, more preferably 70 μm or less, and most preferably 50 μm or less.

[0159] (Formation of Adhesive Layer) The method for forming the adhesive layer is not particularly limited. For example, the following methods (1) and (2) are used to coat the adhesive composition and dry it. (1) A method in which the adhesive composition is coated on one or both sides of a substrate sheet using various coating apparatus, the solvent is removed, and the material is hardened as needed. (2) A method in which the adhesive composition is coated on the release surface of a release sheet after a release treatment is applied to the surface using various coating apparatus, the solvent is removed after drying, and the material is transferred to one or both sides of a substrate sheet and then hardened as needed.

[0160] As examples of such coating apparatus, there are: reverse coating machine, gravure printing coating machine, forward coating machine, doctor blade coating machine, wire rod coating machine, doctor blade coating machine, slot coating machine, curtain coating machine, dip coating machine, etc.

[0161] The drying temperature for removing the solvent is preferably 40°C or higher, more preferably 60°C or higher, preferably 150°C or lower, more preferably 140°C or lower, and most preferably 130°C or lower. The drying time is preferably 5 seconds to 20 minutes, more preferably 10 seconds to 10 minutes. Examples of drying methods include hot air, near-infrared radiation, infrared radiation, and high frequency. Furthermore, examples of curing conditions include drying at 30°C to 60°C for approximately 3 to 7 days.

[0162] (Release Sheet) The adhesive sheet may also have a release sheet (release liner) on the surface of the adhesive layer before use. Alternatively, instead of using other release sheets, a release layer may be provided on the opposite side of the substrate sheet to the adhesive layer lamination surface, with the surface of the release layer contacting the exposed side of the adhesive layer before being rolled into a roll or stacked. The release sheet is used as a protective layer for the adhesive layer and is removed when the adhesive sheet of the present invention is attached to the substrate.

[0163] Examples of release sheets include: cellophane, coated paper, laminated paper, etc., and release agents such as silicone resin coated on various plastic sheets. The plastic sheet used as the base material can be any of the examples mentioned above. The thickness of the release sheet is not particularly limited, and is typically 10 μm to 150 μm.

[0164] (Application of Adhesive Material) The adhesive material of the present invention is suitable for use as an adhesive layer (adhesive material) in flexible displays that can be repeatedly flexibly used. Examples of such flexible displays include foldable displays and rollable displays that can be rolled into a cylindrical shape. Flexible displays can be used in portable terminals such as smartphones or tablets, or in retractable display types.

[0165] [Adhesive material for flexible display, adhesive sheet for flexible display] As an adhesive material for flexible display, it is suitable for bonding one flexible member constituting a flexible display to another flexible member.

[0166] The adhesive sheet for flexible display has an adhesive layer for bonding one flexible member constituting a flexible display with another flexible member, and a flexible sheet member attached to at least one side of the adhesive layer, the adhesive layer being formed of the adhesive material.

[0167] Examples of the adhesive sheet for the flexible display include: a form having an adhesive layer and a first flexible sheet member attached to one side of the adhesive layer; and a form having an adhesive layer, a first flexible sheet member attached to one side of the adhesive layer, and a second flexible sheet member attached to the other side of the adhesive layer.

[0168] FIG1 shows an example of an adhesive sheet for a flexible display according to the present invention. The adhesive sheet 10 for a flexible display in FIG1 is composed of an adhesive layer 12, a first flexible sheet member 14 and a second flexible sheet member 16 sandwiching the adhesive layer 12. The adhesive layer 12 is in contact with the release surfaces of the first flexible sheet member and the second flexible sheet member 16.

[0169] (Adhesive Layer) The adhesive layer is formed from the adhesive material. From the viewpoint of sufficiently ensuring adhesion to the substrate, the film thickness of the adhesive layer is preferably 1 μm or more, more preferably 5 μm or more, and most preferably 10 μm or more. Furthermore, from the viewpoint of suppressing adhesive layer protrusion, the thickness of the adhesive layer is preferably 100 μm or less, more preferably 70 μm or less, and most preferably 50 μm or less.

[0170] (Flexible Sheet Component) Examples of such flexible sheet components include: a flexible substrate sheet, a release liner, etc. The substrate sheet is a sheet component that supports the adhesive layer, and this sheet component can be a functional sheet component. Examples of such functional sheet components include: a cover film, a barrier film, a polarizing film, a phase difference film, an optical compensation film, a brightness enhancement film, a diffusion film, an anti-reflection film, etc. The release liner is used to protect the adhesive layer before it is attached to the substrate, and is peeled off from the adhesive layer before it is attached to the substrate.

[0171] Examples of flexible sheet components include sheets made of polymer materials and glass sheets. The thickness of the flexible sheet component is not particularly limited, but from the viewpoint of excellent processability, it is preferably 2μm to 500μm, and more preferably 2μm to 200μm.

[0172] Examples of such polymer materials include: polyimide resin; polyester resins such as polyethylene terephthalate resin and polyethylene naphthalate (PEN) resin; polycarbonate resin; poly(meth)acrylate resin; polystyrene resin; polyamide resin; polyacrylonitrile resin; polyolefin hydroxyl resins such as polypropylene resin, polystyrene resin, polycyclic cycloene resin, and cycloolefin copolymer resin; polyphenylene sulfide resin; polyvinyl chloride resin; polyvinylidene chloride resin; and polyvinyl alcohol resin. These polymer materials can be used alone or in combination of two or more.

[0173] The flexible sheet component may be composed of a single layer consisting of one or more layers containing the polymer material, or it may be composed of two or more layers consisting of one or more layers containing the polymer material and one or more layers containing a different polymer material than the single layer.

[0174] Preferably, the flexible sheet component is a release sheet after a release treatment is applied to the surface in contact with the adhesive layer. Examples of release agents used in the release treatment include silicone-based, fluorine-based, alkyd-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

[0175] The adhesive sheet for the flexible display has a first flexible sheet member attached to one side of the adhesive layer and a second flexible sheet member attached to the other side of the adhesive layer. The first flexible sheet member is a first release tab, and the second flexible sheet member is a second release tab. Preferably, the release surfaces of the first and second release tabs contact the adhesive layer for adhesion. In addition, when the adhesive layer is sandwiched between two release tabs, it is preferable to use one release tab as a heavy-duty release tab with a larger release force and the other release tab as a light-duty release tab with a smaller release force.

[0176] The adhesive sheet for flexible displays can be manufactured by, for example, applying the above-mentioned adhesive composition onto a flexible sheet component, and then hardening it by drying and heating as needed to form an adhesive layer.

[0177] The coating of the adhesive component can be achieved using various coating methods, such as reverse gravure printing coating, direct gravure printing coating, die coating, rod coating, silk rod coating, roller coating, spin coating, dip coating, spray coating, doctor blade coating, dot coating, etc.; inkjet printing; offset printing, screen printing, flexographic printing, etc. Furthermore, before coating the adhesive component, surface treatments such as corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment can be applied to the surface of the release sheet.

[0178] The drying and heating process is not particularly limited as long as it removes the solvents used to bind the components and hardens them. It is preferable to perform the process at a temperature of 60°C to 150°C for about 20 to 600 seconds. In particular, the heating temperature is preferably 100°C to 150°C.

[0179] When a first flexible sheet member is disposed on one side of the adhesive layer and a second flexible sheet member is disposed on the other side, the adhesive composition is applied to the first flexible sheet member, an adhesive layer is formed on the first flexible sheet member, and then the second flexible sheet member is attached to this adhesive layer. Furthermore, the adhesive layer can also be cured as needed. Examples of such curing conditions include curing at 60°C for approximately 3 to 7 days.

[0180] [Flexible Laminated Member] The flexible laminated member of the present invention comprises a first flexible member, a second flexible member, and an adhesive layer for bonding the first flexible member and the second flexible member together. The adhesive layer is characterized in that it is composed of an adhesive material. Since the adhesive layer of the flexible laminated member is formed of the adhesive material, even when the flexible laminated member is repeatedly bent, appearance defects such as ripples at the bending points can be suppressed.

[0181] FIG2 shows an example of a flexible laminated member of the present invention. The flexible laminated member 20 of FIG2 includes a first flexible member 22, a second flexible member 24, and an adhesive layer 12 located between the first flexible member 22 and the second flexible member 24 to bond the flexible members together.

[0182] Examples of the flexible laminated member include: a first flexible member and a second flexible member both being flexible devices; the second flexible member being a flexible device, and the first flexible member being a functional sheet member attached to the flexible device. Examples of the flexible device include a foldable display and a rollable display that can be rolled into a tube. Examples of the functional sheet member include: a cover film, a barrier film, a polarizing film, a phase difference film, an optical compensation film, a brightness enhancement film, a diffusion film, an anti-reflective film, a transparent conductive film, a metal screen film, and a buffer film.

[0183] The first flexible member and the second flexible member are members that can be repeatedly flexed or bent. Examples of the first flexible member and the second flexible member include flexible substrate materials, functional sheet members, and display elements (organic EL modules, electronic paper modules, etc.). At least one of the first flexible member and the second flexible member is preferably a display element. The flexible laminated member can be used in flexible displays.

[0184] (Method for manufacturing flexible laminated member) The method for manufacturing flexible laminated member of the present invention is not particularly limited, for example, the following methods (1) to (4) are given.

[0185] (1) A method of obtaining a flexible laminate by peeling off a release sheet attached to one side of an adhesive sheet, attaching the exposed adhesive layer to a first flexible member, peeling off a release sheet attached to the other side of the adhesive sheet, and attaching the exposed adhesive layer to a second flexible member. (2) A method of applying an adhesive composition to one side of a first flexible member, hardening it by drying and heating as needed to form an adhesive layer, and attaching the release-type side of a release sheet to this adhesive layer. Then, peeling off the release sheet to attach the exposed adhesive layer to a second flexible member to obtain a flexible laminate. (3) A method of obtaining a flexible laminate by applying an adhesive composition to one side of a first flexible member, hardening it by drying and heating as needed to form an adhesive layer, and attaching a second flexible member to this adhesive layer. (4) A method of applying an adhesive composition to the release surface of a release sheet, drying and heating it as needed to harden it into an adhesive layer, and then attaching a first flexible member to the adhesive layer. Then, peeling off the release sheet to expose the adhesive layer and attaching it to a second flexible member to obtain a flexible laminated member.

[0186] In addition, even in any of the cases (1) to (4) above, the order of use of the first flexible member and the second flexible member can be replaced. The adhesive layer can be formed using various coating methods or printing methods that are the same as those used in the manufacture of the adhesive sheet, and the drying and heating process is also the same. Furthermore, hardening can be performed as needed. Furthermore, the release liner used in the manufacture of the flexible laminate can be the same as the release liner used in the adhesive sheet.

[0187] (Example) Hereinafter, the present invention will be further described in detail based on specific examples. The present invention is not limited to the following examples, and can be implemented by appropriate modifications without changing its essential meaning. In addition, the polymerization rate of the polymer, the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn), the thickness of the adhesive layer, and the evaluation of the adhesive material and the analysis of the colloidal composition are evaluated by the following methods.

[0188] In addition, the meanings of the abbreviations are as follows: EHA: 2-ethylenehexyl acrylate; LA: n-dodecyl acrylate; HA: n-hexyl acrylate; BA: n-butyl acrylate; VP: N-vinyl-2-pyrrolidone; ACMO: acrylmorpholine; AA: acrylic acid; HBA: 4-hydroxybutyl acrylate; BTEE: ethyl-2-methyl-2-n-butylethanol telluryl propionate; AIBN: azobisisobutyronitrile; AcOEt: ethyl acetate.

[0189] (Polymerization Rate) ¹H-NMR was measured using a nuclear magnetic resonance (NMR) apparatus (Bruker BioSpin, model: AVANCE500 (frequency 500MHz)) (solvent: CDCl₃, internal standard: trimethylsilane (TMS)). The polymerization rate of the monomer was calculated by determining the integral ratio of the signals from the monomer and the polymer from the obtained NMR spectrum.

[0190] (Weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn)) Gel permeation chromatography (GPC) was performed using a high-performance liquid chromatography system (TOSOH, model HLC-8320GPC). Two TSKgel Super HZM-H (TOSHO) tubes were used, with tetrahydrofuran solution as the mobile phase and a differential refractometer as the detector. The measurement conditions were: tube temperature 40℃, sample concentration 0.5 mg / ml, sample injection volume 10 μm, and flow rate 0.6 ml / min. Polystyrene (molecular weights 9,840,000, 5,480,000, 2,890,000, 1,090,000, 775,000, 427,000, 190,000, 96,400, 37,900, 10,200, 2,630,440) was used as a standard to construct a calibration curve to determine the number mean molecular weight (Mn). The molecular weight distribution (Mw / Mn) was then calculated from these measurements.

[0191] (Adhesive material thickness (film thickness)) The total thickness of the adhesive sheet is measured using a thickness measuring machine (TESTER SANGYO, 'TH-104'), and the thickness of the release sheet is subtracted from the total thickness to obtain the thickness of the adhesive material.

[0192] (Dynamic Viscoelasticity Test) The adhesive layer (adhesive material) constituting the adhesive sheet was laminated using a hand roller to create a 600 μm thick laminate, which was used as the test piece. The test was conducted using a dynamic viscoelasticity measuring apparatus (Anton Paar, MCR702) with the sample clamped between parallel plates of 8 mm diameter. The test conditions were a temperature range of -60℃ to 150℃, a heating rate of 3℃ / min, and a frequency of 1 Hz. The strain changed in stages due to the elastic modulus: 0.1% at ~10 MPa, 0.2% at 0.5 MPa, 0.5% at 0.09 MPa, 1.5% at 0.05 MPa, and 3% before reaching 0.05 MPa. (Glass Transition Temperature Tg) Based on the dynamic viscoelasticity test results, the temperature at which the loss tangent (tanδ) is maximized was taken as the glass transition temperature Tg of the adhesive material. (Shear storage modulus G') Based on the dynamic viscoelasticity measurement results, the shear storage modulus G' at 25°C is read.

[0193] (Gel Rate) The mass M2 of a gold mesh (400 sieve) cut into pieces 50 mm wide and 120 mm long was measured. 80 mg to 120 mg of the adhesive layer (adhesive material) was collected from the adhesive sheet to determine its mass M1. Test pieces were prepared by wrapping the gold mesh in a manner that prevented the adhesive material from falling off. The test pieces were placed in a glass bottle, 40 g of ethyl acetate was added, and the mixture was gently shaken and allowed to stand at room temperature (25°C) for 72 hours. After standing, the test pieces were removed from the glass bottle and placed at a test temperature for 12 hours, followed by drying in a vacuum oven at 100°C for 4 hours. The dried test pieces were cooled to room temperature, and their mass M3 was measured. The gel rate was calculated using the following formula: Gel rate (mass %) = (M3 - M2) / M1 × 100

[0194] (Colloidal Components) After removing the gelation test piece from the glass bottle, the ethyl acetate solution containing the extracted colloidal components is dried to obtain the sample for testing. The solid in the glass bottle is diluted with tetrahydrofuran to adjust the sample concentration to 0.5 mg / ml. Using this sample, gel permeation chromatography (GPC) is performed in the same manner as when determining the weight-average molecular weight (Mw). The weight-average molecular weight (Mw) and number-average molecular weight (Mn) are determined from the measured molecular weight distribution curve, and the molecular weight distribution (Mw / Mn) is calculated from these weight-average molecular weight (Mw) and number-average molecular weight (Mn). The molecular weight at which the molecular weight distribution curve reaches its maximum is taken as the peak molecular weight (Mp). Furthermore, the proportions of peak areas with molecular weights above 10,000 but below 100,000 to those with molecular weights between 10,000 and 30 million were calculated (W1), the proportions of peak areas with molecular weights above 100,000 but below 560,000 to those with molecular weights between 10,000 and 30 million were calculated (W2), the proportions of peak areas with molecular weights above 560,000 to those with molecular weights between 10,000 and 30 million were calculated (W3), the proportions of peak areas with molecular weights above 100,000 but below 150,000 to those with molecular weights between 10,000 and 30 million were calculated (W2a), and the proportions of peak areas with molecular weights above 150,000 but below 560,000 to those with molecular weights between 10,000 and 30 million were calculated (W2b).

[0195] (Stress Relief Time at 400% Strain, Recovery Rate after 400% Strain) The adhesive layer (adhesive material) constituting the adhesive sheet was laminated using a hand roller to create a 600 μm thick laminate, which served as the test piece. Measurements were performed using a viscoelasticity measuring apparatus (Anton Paar, MCR302), with the sample clamped between parallel plates of 8 mm diameter (the bonding surfaces were roughened with 240 grit sandpaper), under conditions of 25°C. Measurements were performed by placing the test piece under axial force of 1 N for 10 minutes, then changing the axial force to 0.05 N, and immediately applying shear stress to induce a 400% strain. The strain was then maintained at 400% for 10 minutes, and the change in shear stress and stress relief time were measured. Next, the shear stress was released (0 kPa) and the piece was left to stand for 10 minutes. The final strain after 10 minutes was measured to determine the recovery rate. The stress relief time is the time it takes for the shear stress to become 0.368 times the initial stress after the strain reaches 400%. The shear stress is the initial stress, measured 0.1 seconds after the initial application of shear stress. The recovery rate is calculated based on the following formula: Recovery rate (%) = {(400 - final strain) / 400} × 100

[0196] (Strain at 20 kPa stress, recovery rate after 20 kPa stress) The adhesive layer (adhesive material) constituting the adhesive sheet was laminated using a hand roller to create a 600 μm thick laminate, which served as the test piece. Measurements were performed using a viscoelasticity measuring apparatus (Anton Paar, MCR302), with the sample clamped between parallel plates of 8 mm diameter (the bonding surfaces were roughened with 240 grit sandpaper), at 25°C. Measurements were performed by placing the test piece under 1 N axial force compression for 10 minutes, then changing the axial force to 0.05 N, and applying a shear stress of 20 kPa for a 10-minute creep test. The strain (20 kPa strain) after 10 minutes was then measured. Next, the shear stress was released (0 kPa) and the piece was left to stand for 10 minutes. The final strain after 10 minutes was measured to obtain the recovery rate. The recovery rate was calculated based on the following formula. Recovery rate (%) = {(20kPa strain - final strain) / 20kPa strain} × 100

[0197] (Determination of Adhesion) One side of the adhesive sheet is peeled off from the adhesive layer, and a corona-treated surface of a polyethylene terephthalate (PET) film (Toyobo E5100, manufactured by Toyobo, 50 μm thick) is bonded to the adhesive surface to create a substrate adhesive sheet cut to a width of 25 mm and a length of 100 mm. The adhesion to polyimide film or glass is determined based on the method of JIS Z 0237 (2009). Specifically, the release sheet is peeled off from the adhesive layer, and the adhesive layer is pressed twice back and forth onto a polyimide (PI) film (Kapton 100V, manufactured by DU PONT-TORAY, 25 μm thick) or white glass (S9112, manufactured by Matsunami Glass Industry, 1.0~1.2 mm thick) using a 2 kg roller. The samples pressed onto the polyimide (PI) film were further subjected to an automated autoclave treatment at 60°C, 5 atm, and 30 minutes. Next, the adhesion of the adhesive layer was measured using a Shimadzu precision universal testing machine, AUTOGRAPH (registered trademark) AGS-1kNX, 50N force gauge, at a peel speed of 300 mm / min and a peel angle of 180°.

[0198] <Preparation of (Meth)acrylic Acid Polymer> (Synthesis Example 1: Polymer No. 1) EHA (278.4 g), LA (240.0 g), HA (60.0 g), AA (18.0 g), HBA (3.6 g), AIBN (17.4 mg), and AcOEt (400.0 g) were placed in a flask equipped with an argon inlet tube and a stirrer. After argon was replaced, BTEE (105.8 mg) was added, and polymerization was carried out at 60°C for 65 hours. The polymerization rate was 89%. After the reaction was completed, AcOEt was added to the reaction solution to obtain a solution containing Polymer No. 1. The Mw of the obtained Polymer No. 1 was 1,532,000, and the Mw / Mn ratio was 1.86.

[0199] (Synthesis Examples 2-10, 13-21: Polymers No. 2-10, 13-21) Polymers No. 2-10 and 13-21 were prepared in the same manner as polymer No. 1. Tables 1 and 2 show the polymers, organotelluric compounds, azo polymerization initiators, solvents, reaction conditions, and polymerization rates used.

[0200] (Synthesis Example 11: Polymer No. 11) EHA (1,425.0 g), LA (1,000.0 g), AA (75.0 g), and AcOEt (1,666.7 g) were placed in a flask equipped with an argon inlet tube and a stirrer. After purging with argon, the temperature was raised to 82°C. AIBN (1,094.7 mg) dissolved in AcOEt (50 g) was added dropwise over 2 hours, and the reaction was continued for 4 hours to polymerize. After the reaction was completed, AcOEt was added to the reaction solution to obtain a solution containing polymer No. 11.

[0201] (Synthesis Example 12: Polymer No. 12) BA (380.0 g), AA (20.0 g), and AcOEt (533.3 g) were placed in a flask equipped with an argon inlet tube and a stirrer. After purging with argon, the temperature was raised to 80°C. AIBN (86.7 mg) dissolved in AcOEt (266.7 g) was added dropwise over 4 hours, and the reaction was further carried out for 2.5 hours to polymerize. After the reaction was completed, AcOEt was added to the reaction solution to obtain a solution containing polymer No. 12.

[0202] The polymerization conditions for each polymer are shown in Tables 1 and 2. In addition, the amount of carboxyl groups, the amount of hydroxyl groups, and the glass transition temperature are calculated from the preparation rate and polymerization rate of the monomers used in the polymerization reaction.

[0203] (Table 1) Polymer No. 1 2 3 4 5 6 7 8 9 10 Aggregation conditions Ethylene monomers type EHA EHA EHA EHA - EHA EHA EHA EHA EHA Dosage (g) 278.4 2256.0 336.0 433.8 - 333.0 330.0 240.0 583.2 591.0 type LA LA LA - - LA LA LA - - Dosage (g) 240.0 1600.0 240.0 - - 240.0 240.0 240.0 - - type HA - - - - - - - - - Usage amount (g) 60.0 - - - - - - - - - kinds - - - BA BA - - BA - - Usage amount (g) - - - 144.6 564.0 - - 93.0 - - kinds AA AA AA AA AA AA AA AA - AA Usage amount (g) 18.0 120.0 18.0 18.0 30.0 18.0 18.0 18.0 - 9.0 kinds HBA HBA HBA HBA HBA HBA HBA HBA HBA - Dosage (g) 3.6 24.0 6.0 3.6 6.0 9.0 12.0 9.0 16.8 - Organic tellurium compounds type BTEE BTEE BTEE BTEE BTEE BTEE BTEE BTEE BTEE BTEE Dosage (mg) 105.8 444.3 81.8 81.8 224.9 81.8 81.8 81.8 81.8 81.8 Azo polymerization initiators type AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN Dosage (mg) 17.4 87.6 18.8 16.1 44.3 21.5 21.5 21.5 24.2 21.5 solvent type AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt Dosage (g) 400.0 2349.2 367.7 367.7 452.6 367.7 367.7 352.4 352.4 352.4 Temperature (°C) 60 60 60 60 60 60 60 60 60 60 Reaction time (hours) 65 64 90 60 25 68 68 65 60 60 Polymerization rate (%) 89 80 84 89 88 94 95 90 88 94 Percentage (mass%) of carboxyl-containing building units in a polymer. 3.0 3.0 3.0 3.0 5.0 3.0 3.0 3.0 - 1.5 Carboxyl groups (mmol / g) in 1g of polymer 0.42 0.42 0.42 0.42 0.69 0.42 0.42 0.42 - 0.21 Percentage (mass%) of hydroxyl-containing building units in polymers. 0.6 0.6 1.0 0.6 1.0 1.5 2.0 1.5 2.8 - Hydroxyl groups (mmol / g) in 1g of polymer 0.04 0.04 0.07 0.04 0.07 0.10 0.14 0.10 0.19 - Glass transition temperature Tg (°C) of polymers -47 -50 -50 -63 -50 -50 -49 -47 -69 -69 Weight-average molecular weight (Mw) (×10) 4 ) 153.2 214.7 220.8 195.1 75.7 212.1 217.9 268.6 200.2 210.5 Molecular weight distribution (Mw / Mn) 1.86 2.07 2.61 1.83 1.41 2.45 2.69 2.56 2.71 2.34

[0204] (Table 2) Polymer No. 11 12 13 14 15 16 17 18 19 20 twenty one Aggregation conditions Ethylene monomers Kind EHA - EHA EHA EHA EHA EHA EHA EHA EHA EHA Dosage (g) 1425.0 - 399.0 324.0 436.5 390.0 180.0 150.0 631.8 631.8 624.0 Kind LA - LA LA - LA LA LA - - - Dosage (g) 1000.0 - 280.0 240.0 - 180.0 240.0 200.0 - - - type - BA - - BA - BA BA - - - Dosage (g) - 380.0 - - 145.5 - 153.0 127.5 - - - type - - - - - - VP VP VP VP ACMO Dosage (g) - - - - - - 18.0 15.0 18.2 18.2 26.0 kinds AA AA AA AA AA - - - - - - Usage amount (g) 75.0 20.0 21.0 36.0 18.0 - - - - - - kinds - - - - - HBA HBA HBA - - - Usage amount (g) - - - - - 30.0 9.0 7.5 - - - organic compound kinds - - BTEE BTEE BTEE BTEE BTEE BTEE BTEE BTEE BTEE Dosage (mg) - - 1049.7 899.7 899.7 359.9 899.7 299.9 974.7 389.9 974.7 Azo polymerization initiators type AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN AIBN Dosage (mg) 1094.7 86.7 86.2 88.7 106.4 70.9 147.8 59.1 160.1 76.9 160.1 solvent type AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt AcOEt Dosage (g) 1716.7 800.0 300.0 257.1 323.1 452.6 400.0 333.3 365.6 365.6 365.6 Temperature (°C) 82 80 60 60 60 60 60 60 60 60 60 Reaction time (hours) 6 6.5 25 twenty four twenty four twenty four twenty four twenty four twenty one twenty one 15 Polymerization rate (%) 97 97 94 93 94 91 92 95 95 93 91 Percentage (mass%) of carboxyl-containing building units in a polymer. 3.0 5.0 3.0 6.0 3.0 - - - - - - Carboxyl groups (mmol / g) in 1g of polymer 0.42 0.69 0.42 0.83 0.42 - - - - - - Percentage (mass%) of hydroxyl-containing building units in polymers. - - - - - 5.0 1.5 1.5 - - - Hydroxyl groups in the polymer (mmol / g) - - - - - 0.35 0.10 0.10 - - - Glass transition temperature Tg (°C) of polymers -50 -50 -50 -47 -64 -56 -45 -45 -67 -67 -66 Weight-average molecular weight (Mw) (×10) 4 ) 79.5 20.7 17.5 17.9 16.3 50.6 18.5 50.3 17.2 43.4 16.4 Molecular weight distribution (Mw / Mn) 4.91 3.97 1.23 1.23 1.25 1.63 1.28 1.53 1.27 1.39 1.22

[0205] <Preparation of Adhesive Composition> (Adhesive Composition No. 1) 0.222 parts by weight of crosslinking agent (Duranate (registered trademark) D101) and butyl acetate were added to a solution of polymer No. 1 obtained in Synthesis Example 1 (polymer component 100 parts by weight) and a solution of polymer No. 11 obtained in Synthesis Example 11 (polymer component 100 parts by weight). The mixture was stirred to obtain adhesive composition No. 1 with a solid content of 24% by weight. Adhesive composition No. 1 is a (meth)acrylic polymer (A) (copolymer No. 1), and its first reactive group is a hydroxyl group, while the second reactive group of the crosslinking agent is an isocyanate group.

[0206] (Adhesive Compositions No. 2~35) Adhesive compositions No. 2~35 are prepared in the same manner as adhesive composition No. 1, except that the formulation is changed as described in Tables 3~5. Furthermore, the amount of crosslinking agent shown in Tables 3~5 is the amount calculated based on solid content. Solid content refers to components other than solvents. Adhesive compositions No. 2~24 and 30~35 are (meth)acrylic polymers (A) with a hydroxyl group as the first reactive group and an isocyanate group as the second reactive group in the crosslinking agent. Adhesive compositions No. 25~29 are (meth)acrylic polymers (A) with a carboxyl group as the first reactive group and an epoxy group as the second reactive group in the crosslinking agent.

[0207] (Table 3) Adhesive component No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Cooperate with (Quality Department) copolymer No.1 100 - - - - - - - - - - - - - - No.2 - 100 100 100 100 100 100 100 100 100 100 100 100 100 100 No. 11 100 - - - - - - - - - - - - - - No. 13 - 125 125 125 100 131 150 75 100 75 100 75 33 150 186 Cross-linking agent A 0.222 0.592 0.444 0.355 0.296 0.296 0.296 0.222 0.222 0.177 0.148 0.148 0.111 - - B - - - - - - - - - - - - - 0.607 0.607 Mörby (OH / NCO) 4.0 1.5 2.0 2.5 3.0 3.0 3.0 4.0 4.0 5.0 6.0 6.0 8.0 1.5 1.5 Mörby (COOH / EPOXY) - - - - - - - - - - - - - - -

[0208] (Table 4) Adhesive composition No. 16 17 18 19 20 twenty one twenty two twenty three twenty four 25 26 27 28 29 Cooperate with (Quality Department) copolymer No.2 - - - - - - - - - 100 100 100 - - No. 3 100 100 100 - - - - - - - - - - - No. 4 - - - 100 100 - - - - - - - - - No. 5 - - - - - 100 - - - - - - - - No. 6 - - - - - - 100 - - - - - - - No. 7 - - - - - - - 100 - - - - - - No. 8 - - - - - - - - - - - - 100 - No. 9 - - - - - - - - 100 - - - - - No. 10 - - - - - - - - - - - - - 100 No. 12 - - - - - 50 - - - - - - - - No. 13 186 233 186 - - - 186 186 - 150 40 40 - - No. 14 - - - - - - - - - - - - - - No. 15 - - - 125 100 - - - - - - - - - No. 16 - - - - - - - - - - 50 50 - - No. 17 - - - - - - - - - - - - 81.45 - No. 18 - - - - - - - - - - - - 40.25 - No. 19 - - - - - - - - - - - - - 100 No. 20 - - - - - - - - - - - - - 50 No. 21 - - - - - - - - 122 - - - - - Crosslinking agent B 1.012 1.012 0.607 0.303 0.182 0.228 0.607 0.607 - - - - - - C - - - - - - - - 0.252 - - - - - D - - - - - - - - - - - - - - E - - - - - - - - - 0.142 0.102 0.152 0.112 0.107 Mörby (OH / NCO) 1.5 1.5 2.5 3.0 5.0 6.6 3.7 5.0 14.0 - - - - - Mörby (COOH / EPOXY) - - - - - - - - - 75 59 39 38 20

[0209] (Table 5) Adhesive component No. 30 31 32 33 34 35 Cooperate with (Quality Department) copolymer No.1 100 - - - - - No.2 - 100 - - 100 100 No. 5 - - 100 100 - - No. 12 - - 100 - - - No. 14 - 100 - - - - Crosslinking agent A 0.222 0.148 - - - - B - - 0.228 0.228 - - D - - - - 0.029 0.014 Mörby (OH / NCO) 4.0 6.0 6.6 6.6 32 66 Mörby (COOH / EPOXY) - - - - - -

[0210] Cross-linking agent A: Durnate (registered trademark) D101 (manufactured by Asahi Kasei, isocyanate-based cross-linking agent (hexamethyl diisocyanate-1,6-hexanediol adduct, functional group 2, solid content concentration 100% by mass, NCO content 4.7 mmol / g (solid content conversion)) Cross-linking agent B: D178NL (manufactured by Mitsui Chemicals, isocyanate-based cross-linking agent (hexamethyl diisocyanate urea form, functional group 2, solid content concentration 100% by mass, NCO content 4.6 mmol / g (solid content conversion)) Cross-linking agent C: Durnate (registered trademark) TPA-100 (manufactured by Asahi Kasei, isocyanate-based cross-linking agent (hexamethyl diisocyanate cyclic trimer, functional group 3, solid content concentration 100% by mass, NCO content 5.5 mmol / g (solid content conversion))) Crosslinking agent D: Durnate (registered trademark) MHG-80B (manufactured by Asahi Kasei, isocyanate-based crosslinking agent (isocyanurate form of hexamethyl diisocyanate, functional group 6, solid content concentration 80% by mass, NCO content 4.5 mmol / g (solid content conversion)) Crosslinking agent E: TETRAD (registered trademark)-C (manufactured by Mitsubishi Gas Chemical, epoxy resin-based crosslinking agent (1,3-bis(N,N-dioxypropylene aminomethyl)cyclohexane, functional group 4, solid content concentration 100% by mass, epoxy group content 9.8 mmol / g (solid content conversion)))

[0211] <Preparation of Adhesive Sheets> Adhesive components were applied to the release surface of the first release sheet (a PET film with a release treatment applied to its surface, CleanSepa (registered trademark) HY-US20: manufactured by Dongshan Film, 75μm thick) using a Becker applicator to achieve a film thickness of 50μm after drying. The film was then heated in a constant temperature dryer at 60°C for 4 minutes, followed by heating at 150°C for 5 minutes. Next, the adhesive layer formed on the first release sheet was bonded to the release surface of the second release sheet (a PET film with a release treatment applied to its surface, CleanSepa (registered trademark) HY-S10: manufactured by Dongshan Film, 38μm thick). The layers were then cured at 60°C for 3 days to create an adhesive layer sandwiched between the two release sheets. Evaluation results of the adhesive layers (adhesive materials) formed from each adhesive component are shown in Tables 6-8.

[0212] (Table 6) Adhesive material No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Film thickness (μm) 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 Gel yield (mass%) 74.0 69.5 61.6 63.1 62.1 59.5 51.3 70.0 68.5 67.6 65.2 68.0 76.1 70.0 65.8 Glass transition temperature Tg (°C) -44 -49 -46 -46 -44 -45 -45 -45 -45 -44 -46 -45 -46 -45 -44 Shear storage modulus G' (MPa) 0.045 0.050 0.039 0.044 0.041 0.037 0.038 0.043 0.049 0.041 0.038 0.043 0.049 0.043 0.042 colloidal components Weight average molecular weight (×10) 4 ) 38.3 18.9 19.7 20.0 24.6 23.3 26.1 24.4 23.2 26.3 28.6 26.6 33.2 22.1 23.6 Molecular weight distribution 5.91 1.43 1.51 1.55 1.68 1.73 1.83 1.63 1.63 1.71 1.97 1.79 2.14 1.44 1.57 Molecular weight distribution of colloidal components (area %) (W1) 10,000 or more, but less than 100,000 18.4 3.3 3.6 3.9 2.8 4.0 3.1 2.1 2.8 1.7 2.8 2.2 3.0 1.9 3.1 (W2) More than 100,000, but less than 560,000 41.7 85.4 84.8 83.9 80.0 79.6 79.0 80.4 82.6 79.7 79.6 80.4 71.2 80.2 76.4 (W2a) More than 100,000, but less than 150,000 21.0 45.4 45.3 45.4 38.2 39.8 39.1 39.8 41.1 39.8 41.2 41.3 34.3 36.8 35.1 (W2b) More than 150,000, but less than 560,000 20.7 39.9 39.5 38.5 41.9 39.8 39.9 40.6 41.4 39.9 38.5 39.2 36.9 43.4 41.4 (W3) More than 560,000 39.9 11.3 11.6 12.2 17.2 16.4 17.8 17.5 14.7 18.6 17.6 17.4 25.7 18.0 20.5 Compare {(W1) / (W3)} 0.46 0.29 0.31 0.32 0.16 0.24 0.18 0.12 0.19 0.09 0.16 0.13 0.12 0.10 0.15 Ratio {(W2a) / (W2)} 0.50 0.53 0.53 0.54 0.48 0.50 0.50 0.49 0.50 0.50 0.52 0.51 0.48 0.46 0.46 Peak molecular weight of colloidal components (×10) 4 ) 41.8 14.5 14.3 14.4 15.5 15.5 15.4 15.1 15.6 15.1 14.8 14.9 15.7 16.3 16.1 400% strain Recovery rate (%) 95.7 79.2 93.7 90.9 94.0 87.5 81.8 93.3 91.5 89.7 85.0 86.3 89.9 90.0 85.9 Temporary easing time (s) 26.2 17.6 17.3 7.5 14.8 2.6 1.7 9.3 7.7 6.4 3.3 5.3 41.6 9.2 3.9 Stress 20 kPa Recovery rate (%) 90.7 91.3 90.1 88.7 89.3 85.7 83.7 92.0 87.1 90.9 82.3 84.4 87.8 92.2 88.4 Response rate after 10 minutes (%) 340 256 426 521 475 746 856 416 605 551 765 602 288 352 538 Adhesion (N / 25mm) Adhesive: Polyimide 10.86 8.93 10.55 10.76 11.77 15.71 20.48 12.47 14.19 12.89 15.31 13.17 10.23 14.89 16.12 Adhesive: Glass 7.37 7.23 9.51 10.27 9.06 13.51 15.64 10.78 9.83 11.11 11.07 10.08 7.97 12.84 14.07

[0213] (Table 7) Adhesive material No. 16 17 18 19 20 twenty one twenty two twenty three twenty four 25 26 27 28 29 Film thickness (μm) 50 50 50 50 50 50 50 50 50 50 50 50 50 50 Gel yield (mass%) 73.6 68.5 62.0 59.2 66.4 70.1 67.8 66.1 51.8 64.8 71.6 78.7 56.3 51.7 Glass transition temperature Tg (°C) -44 -44 -44 -39 -38 -28 -43 -43 -44 -46 -45 -45 -46 -46 Shear storage modulus G' (MPa) 0.043 0.044 0.038 0.077 0.078 0.127 0.041 0.039 0.049 0.035 0.050 0.052 0.055 0.066 colloidal components Weight average molecular weight (×10) 4 ) 19.7 20.4 21.6 23.6 32.0 32.2 20.5 20.0 17.9 21.7 29.8 28.6 27.0 24.5 Molecular weight distribution 1.40 1.48 1.47 1.67 2.37 3.11 1.54 1.47 1.28 1.61 1.69 1.82 1.51 1.55 Molecular weight distribution of colloidal components (area %) (W1) 10,000 or more, but less than 100,000 2.4 3.4 2.6 3.0 4.5 14.1 16.8 16.6 15.1 17.9 12.1 14.6 9.4 13.0 (W2) More than 100,000, but less than 560,000 83.5 80.5 80.2 81.8 77.0 50.3 80.0 80.8 84.3 77.2 75.9 75.0 81.7 80.8 (W2a) More than 100,000, but less than 150,000 43.6 41.7 39.1 41.4 40.7 27.9 26.2 26.9 29.1 27.1 18.7 18.0 20.5 22.2 (W2b) More than 150,000, but less than 560,000 39.9 38.8 41.0 40.4 36.4 22.4 53.8 53.9 55.2 50.1 57.2 56.9 61.1 58.5 (W3) More than 560,000 14.1 16.1 17.3 15.2 18.4 35.6 3.2 2.6 0.6 4.9 12.0 10.4 9.0 6.2 Compare {(W1) / (W3)} 0.17 0.21 0.15 0.19 0.25 0.39 5.26 6.34 25.52 3.65 1.00 1.40 1.04 2.09 Ratio {(W2a) / (W2)} 0.52 0.52 0.49 0.51 0.53 0.56 0.33 0.33 0.35 0.35 0.25 0.24 0.25 0.28 Peak molecular weight of colloidal components (×10) 4 ) 14.6 14.5 15.3 15.1 14.7 12.9 15.2 15.3 16.0 15.1 15.3 15.2 17.3 16.0 400% strain Recovery rate (%) 90.6 92.6 92.0 84.9 81.0 84.6 92.2 92.8 93.3 88.0 90.2 93.3 93.5 89.9 Temporary easing time (s) 12.0 7.5 3.6 4.4 4.7 5.7 4.2 5.4 2.2 2.0 7.4 17.3 8.5 2.2 Stress 20 kPa Recovery rate (%) 95.6 93.4 93.5 85.9 83.9 86.2 93.0 93.4 94.0 90.4 90.7 93.4 93.5 91.3 Response rate after 10 minutes (%) 306 392 531 237 239 55 469 408 505 640 327 249 283 409 Adhesion (N / 25mm) Adhesive: Polyimide 11.79 14.20 20.73 28.15 26.01 16.18 26.90 19.45 12.90 18.93 10.27 10.03 10.97 16.71 Adhesive: Glass 11.05 12.45 14.30 17.31 16.68 14.50 12.41 11.57 7.89 13.27 13.92 12.99 7.18 12.86

[0214] (Table 8) Adhesive material No. 30 31 32 33 34 35 Film thickness (μm) 50 50 50 50 50 50 Gel yield (mass%) 97.2 20.1 49.6 96.6 87.6 83.2 Glass transition temperature Tg (°C) -45 -41 -28 -28 -45 -45 Shear storage modulus G' (MPa) 0.050 0.050 0.131 0.179 0.046 0.047 colloidal components Weight average molecular weight (×10) 4 ) 35.7 94.8 45.2 31.4 99.1 121.2 Molecular weight distribution 3.05 4.72 4.42 1.65 2.23 2.45 Molecular weight distribution of colloidal components (area %) (W1) 10,000 or more, but less than 100,000 10.0 2.9 13.6 1.9 0.4 0.3 (W2) More than 100,000, but less than 560,000 50.2 46.6 47.7 54.4 18.4 15.7 (W2a) More than 100,000, but less than 150,000 24.3 21.5 26.8 23.6 6.1 5.6 (W2b) More than 150,000, but less than 560,000 25.9 25.1 20.9 30.9 12.3 10.1 (W3) More than 560,000 39.8 50.5 38.7 43.7 81.2 83.9 Compare {(W1) / (W3)} 0.25 0.06 0.35 0.04 0.01 0.00 Ratio {(W2a) / (W2)} 0.48 0.46 0.56 0.43 0.33 0.36 Peak molecular weight of colloidal components (×10) 4 ) 32.6 16.0 13.5 39.1 93.9 142.6 400% strain Recovery rate (%) 73.8 67.8 70.8 35.2 83.9 89.1 Temporary easing time (s) 15.3 1.9 3.0 3.4 18.9 14.5 Stress 20 kPa Recovery rate (%) 95.7 40.4 77.5 93.1 75.5 77.9 Response rate after 10 minutes (%) 88 1614 130 twenty two 409 334 Adhesion (N / 25mm) Adhesive: Polyimide 8.06 14.88 18.55 14.61 7.19 9.12 Adhesive: Glass 7.36 11.40 15.91 13.49 7.94 8.72

[0215] Adhesive materials No. 1 to 29 have a shear storage modulus of 0.15 MPa or less at 25°C, a glass transfer temperature of 0°C or less, a gelation rate of 50% to 95% by mass, and a differential molecular weight distribution curve of the colloidal components that satisfies the requirements of (1), (2), and (3). These adhesive materials No. 1 to 29 exhibit good recovery rate after 400% strain distortion and good strain under applied shear stress of 20 kPa. Furthermore, they have good adhesion to both glass and PI films.

[0216] Adhesive No. 30 has a gelation rate exceeding 95% by mass, indicating insufficient colloidal content. This adhesive No. 30 exhibits poor adhesion to both glass and PI film. Adhesives No. 31 and 32 have gelation rates below 50% by mass. Both adhesives No. 31 and 32 show poor recovery rates after twisting to 400% strain and under applied shear stress of 20 kPa.

[0217] Adhesive No. 33 has a shear storage modulus exceeding 0.15 MPa at 25°C. This adhesive No. 33 exhibits poor recovery rate after twisting to a strain of 400%. Adhesives No. 34 and 35 have differential molecular weight distribution curves of colloidal components that do not meet the requirements of (2) and (3). These adhesives No. 34 and 35 exhibit poor recovery rate when a shear stress of 20 kPa is applied, and also have poor adhesion to both glass and PI film.

[0218] The present invention includes the following features.

[0219] (Sample 1) An adhesive material containing a polymer (X) having a cross-linked structure, characterized in that: the shear storage modulus at a temperature of 25°C is 0.15 MPa or less; the glass transfer temperature is 0°C or less; the gelation rate is 50% to 95% by mass; and the differential molecular weight distribution curve of the colloidal component satisfies the requirements of (1), (2) and (3): (1) the ratio (W1) of the peak area of ​​molecular weight of 10,000 or more but less than 100,000 to the peak area of ​​molecular weight of 10,000 to 30 million is less than 20%; (2) the ratio (W2) of the peak area of ​​molecular weight of 100,000 or more but less than 560,000 to the peak area of ​​molecular weight of 10,000 to 30 million is more than 40%; and (3) the ratio (W3) of the peak area of ​​molecular weight of 560,000 or more to the peak area of ​​molecular weight of 10,000 to 30 million is less than 40%.

[0220] (Sample 2) The adhesive material as described in Sample 1, wherein the differential molecular weight distribution curve of the colloidal component further satisfies the requirements of (2a) and (2b): (2a) the ratio of the peak area of ​​molecular weight of 100,000 or more but less than 150,000 to the peak area of ​​molecular weight of 10,000 to 30 million (W2a) is more than 15%; and (2b) the ratio of the peak area of ​​molecular weight of 150,000 or more but less than 560,000 to the peak area of ​​molecular weight of 10,000 to 30 million (W2b) is more than 20%.

[0221] (Sample 3) The adhesive material as described in Sample 2, wherein in the differential molecular weight distribution curve of the colloidal component, the ratio (W2a / W2) of the peak area of ​​molecular weight above 100,000 but below 560,000 is 0.30 to 0.60.

[0222] (Style 4) An adhesive material as described in any one of styles 1 to 3, wherein the weight average molecular weight (Mw) of the colloidal component is 100,000 to 560,000.

[0223] (Sample 5) The adhesive material as described in any one of Samples 1 to 4, wherein the peak molecular weight of the differential molecular weight distribution curve of the colloidal component is between 100,000 and 30 million, and the highest peak molecular weight (Mp) is between 100,000 and 500,000.

[0224] (Example 6) An adhesive material as described in any one of Examples 1 to 5, wherein the polymer (X) having a crosslinked structure is obtained by subjecting an adhesive composition to a crosslinking reaction, the adhesive composition comprising: a (meth)acrylic polymer (A) having a first reactive group with a weight average molecular weight of 600,000 or more and 3 million or less, a (meth)acrylic polymer (B) having a weight average molecular weight (Mw) of 100,000 or more and 800,000 or less, and a crosslinking agent having a second reactive group that reacts with the first reactive group.

[0225] (Sample 7) The adhesive material as described in Sample 6, wherein the content of the first reactive group in the (meth)acrylic polymer (A) is 0.002 mmol / g to 1.0 mmol / g.

[0226] (Example 8) An adhesive material as described in Example 6 or 7, wherein the molar ratio (molar amount of the first reactive group / molar amount of the second reactive group) of the adhesive composition to the first reactive group is 1 to 80.

[0227] (Example 9) An adhesive material as described in any one of Examples 6 to 8, wherein the combination of the first reactive group and the second reactive group is a combination of the first reactive group being a hydroxyl group and the second reactive group being an isocyanate group, or a combination of the first reactive group being a carboxyl group and the second reactive group being an epoxy group.

[0228] (Sample 10) An adhesive material as described in any one of Samples 6 to 9, wherein the (meth)acrylate polymer (A) is derived from (meth)acrylate building units having alkyl groups having 1 to 12 carbon atoms in a content of 70% to 99% by mass.

[0229] (Example 11) An adhesive sheet having a substrate sheet and an adhesive layer formed on at least one side of the substrate sheet, the adhesive layer being an adhesive material as described in any one of Examples 1 to 10.

[0230] (Example 12) An adhesive for a flexible display, which is used to bond a flexible member constituting a flexible display with other flexible members, the adhesive being an adhesive as described in any one of Examples 1 to 10.

[0231] (Example 13) An adhesive sheet for a flexible display, comprising: an adhesive layer for attaching a flexible member constituting a flexible display to other flexible members; and a flexible sheet member attached to at least one side of the adhesive layer; the adhesive layer is formed of an adhesive material as described in any one of Examples 1 to 10.

[0232] (Example 14) An adhesive sheet for a flexible display as described in Example 13, wherein the adhesive sheet has a first flexible sheet member attached to one side of the adhesive layer and a second flexible sheet member attached to the other side of the adhesive layer; the first flexible sheet member is a first release tab and the second flexible sheet member is a second release tab; the first release tab and the second release tab are attached in such a way that their respective release surfaces contact the adhesive layer.

[0233] (Example 15) A flexible laminated member comprising a first flexible member, a second flexible member, and an adhesive layer for bonding the first flexible member and the second flexible member together; the adhesive layer is formed of an adhesive material as described in any one of Examples 1 to 10. [Simplified Explanation of the Diagram]

[0010] [Figure 1] is a schematic cross-sectional view of an example of the adhesive sheet of the present invention. [Figure 2] is a schematic cross-sectional view of an example of the flexible laminated member of the present invention. [Biomaterial Storage]

[0235] None.

Claims

1. An adhesive material comprising a polymer (X) having a cross-linked structure, characterized in that: the shear storage modulus at a temperature of 25°C is 0.15 MPa or less; the glass transfer temperature is 0°C or less; the gelation rate is 50% to 95% by mass; and the differential molecular weight distribution curve of the colloidal component satisfies the requirements of (1), (2) and (3): (1) the ratio (W1) of the peak area of ​​molecular weight of 10,000 or more but less than 100,000 to the peak area of ​​molecular weight of 10,000 to 30 million is less than 20%; (2) the ratio (W2) of the peak area of ​​molecular weight of 100,000 or more but less than 560,000 to the peak area of ​​molecular weight of 10,000 to 30 million is more than 40%; and (3) the ratio (W3) of the peak area of ​​molecular weight of 560,000 or more to the peak area of ​​molecular weight of 10,000 to 30 million is less than 40%. The polymer (X) with the crosslinked structure is obtained by subjecting the adhesive composition to a crosslinking reaction in such a way that the molar ratio of the second reactive group to the first reactive group in the adhesive composition (molar amount of the first reactive group / molar amount of the second reactive group) is 1 to 80; the adhesive composition contains: a (meth)acrylic polymer (A) having a first reactive group with a weight average molecular weight of 600,000 or more and 3 million or less, a (meth)acrylic polymer (B) having a weight average molecular weight of 100,000 or more and 800,000 or less, and a crosslinking agent having a second reactive group that reacts with the first reactive group.

2. The adhesive material as claimed in claim 1, wherein the differential molecular weight distribution curve of the colloidal component further satisfies the requirements of (2a) and (2b): (2a) the ratio of the peak area of ​​molecular weight of 100,000 or more but less than 150,000 to the peak area of ​​molecular weight of 10,000 to 30 million (W2a) is more than 15%; and (2b) the ratio of the peak area of ​​molecular weight of 150,000 or more but less than 560,000 to the peak area of ​​molecular weight of 10,000 to 30 million (W2b) is more than 20%.

3. The adhesive material as described in claim 2, wherein in the differential molecular weight distribution curve of the colloidal component, the ratio (W2a / W2) of the proportion of peak areas with molecular weights of 100,000 or more but less than 560,000 to the proportion of peak areas with molecular weights of 100,000 or more but less than 150,000 is 0.30 to 0.

60.

4. The adhesive material as described in claim 1, wherein the weight average molecular weight (Mw) of the colloidal component is between 100,000 and 560,000.

5. The adhesive material as claimed in claim 1, wherein the peak molecular weight of the differential molecular weight distribution curve of the colloidal component is between 100,000 and 30 million, and the highest peak molecular weight (Mp) is between 100,000 and 500,000.

6. The adhesive material as claimed in claim 1, wherein in the adhesive composition, the amount of (meth)acrylate polymer (B) relative to 100% by mass of (meth)acrylate polymer (A) is 30% by mass or more and 300% by mass or less; the total content of (meth)acrylate polymer (A) and (meth)acrylate polymer (B) in the polymer component contained in the adhesive composition is 70% by mass to 100% by mass.

7. The adhesive material as claimed in claim 1, wherein the content of the first reactive group in the (meth)acrylic polymer (A) is 0.002 mmol / g to 1.0 mmol / g.

8. The adhesive material as claimed in claim 1, wherein the difference (MwA - MwB) between the weight average molecular weight (MwA) of the (meth)acrylic polymer (A) and the weight average molecular weight (MwB) of the (meth)acrylic polymer (B) is between 500,000 and 2,900,000.

9. The adhesive material as claimed in claim 1, wherein the combination of the first reactive group and the second reactive group is a combination of the first reactive group being a hydroxyl group and the second reactive group being an isocyanate group, or a combination of the first reactive group being a carboxyl group and the second reactive group being an epoxy group.

10. The adhesive material as claimed in claim 1, wherein the (meth)acrylate polymer (A) is derived from (meth)acrylate building units having alkyl groups having 1 to 12 carbon atoms in a content of 70% to 99% by mass.

11. An adhesive sheet having a substrate sheet and an adhesive layer formed on at least one side of the substrate sheet, the adhesive layer being an adhesive material as described in any one of claims 1 to 10.

12. An adhesive for a flexible display, used to bond a flexible member constituting a flexible display with other flexible members, the adhesive being the adhesive described in any one of claims 1 to 10.

13. An adhesive sheet for a flexible display, comprising: an adhesive layer for attaching a flexible member constituting a flexible display to other flexible members; and a flexible sheet member attached to at least one side of the adhesive layer; the adhesive layer being formed of an adhesive material as described in any one of claims 1 to 10.

14. The adhesive sheet for a flexible display as claimed in claim 13, wherein the adhesive sheet has a first flexible sheet member attached to one side of the adhesive layer and a second flexible sheet member attached to the other side of the adhesive layer; the first flexible sheet member is a first release tab, and the second flexible sheet member is a second release tab; the first release tab and the second release tab are attached in such a way that their respective release surfaces contact the adhesive layer.

15. A flexible laminated member comprising a first flexible member, a second flexible member, and an adhesive layer for bonding the first flexible member and the second flexible member together; the adhesive layer being formed of an adhesive material as described in any one of claims 1 to 10.

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