WO2020162245A1

WO2020162245A1 - Polymer, curable composition, cured object, adhesive sheet, laminate, and flexible display

Info

Publication number: WO2020162245A1
Application number: PCT/JP2020/002716
Authority: WO
Inventors: 牧人中村; 尚也菊川; 鈴木　千登志
Original assignee: Ａｇｃ株式会社
Priority date: 2019-02-05
Filing date: 2020-01-27
Publication date: 2020-08-13
Also published as: TW202035480A; JPWO2020162245A1; CN113329874A; KR20210122777A; CN113329874B; JP7415957B2

Abstract

Provided are: a polymer that enables the formation of a flexible laminate having excellent shape recoverability and bending durability, a curable composition, a cured object, an adhesive sheet, a laminate, and a flexible display. The polymer includes a unit based on a first monomer and a unit based on a second monomer, wherein and the proportion of the unit based on the second monomer with respect to the total constituent units is 0.1-50 mass%, the first monomer is a (meth)acrylic ester having a molecular weight of 1,000 or less, and the second monomer is a (meth)acrylic ester having a molecular weight of 5,000-25,000 and including a single (meth)acryloyloxy group and one or more polyoxyalkylene chains per molecule.

Description

Polymer, curable composition, cured product, adhesive sheet, laminate and flexible display

The present invention relates to a polymer, a curable composition, a cured product, an adhesive sheet, a laminate and a flexible display.

In recent years, in addition to a rigid display panel, a flexible display panel having bendability or bendability has been developed.
The flexible display panel includes a flexible laminate in which a flexible member is laminated on a flexible display panel body via an adhesive layer. The flexible display panel body is, for example, an organic EL (Electronic Luminescent) display panel. The flexible member is, for example, an optical film or a protective film.

Patent Documents

1 and 2 describe a composition containing a (meth)acrylic acid ester copolymer having a specific monomer composition and a cross-linking agent as an adhesive suitable for forming a flexible laminate.

Japanese Patent Laid-Open No. 2017-95654 International Publication No. 2018/173896

Due to the development of peripheral technology, the required standard for bending durability and shape recovery of flexible laminates has become higher and higher. Folding durability is a characteristic that defects such as peeling, floating, or cracks of the flexible laminate due to bending are unlikely to occur. The shape recoverability is a characteristic that permanent deformation of the flexible laminate due to bending stress or tensile stress is unlikely to occur.
However, the flexible laminate formed using the pressure-sensitive adhesive described in

Patent Documents

1 and 2 does not have these characteristics sufficiently.
An object of the present invention is to provide a polymer, a curable composition, a cured product, an adhesive sheet, a laminate and a flexible display capable of forming a flexible laminate having excellent bending durability and shape recovery.

[1] A unit based on the first monomer and a unit based on the second monomer are included, and the ratio of the unit based on the second monomer to all structural units is 0.1 to 50% by mass. A polymer,
The first monomer is a (meth)acrylic acid ester having a molecular weight of 1,000 or less,
The second monomer has a molecular weight of 5,000 to 25,000, and has one or more polyoxyalkylene chains and one (meth)acryloyloxy group in one molecule, (meth) A polymer that is an acrylic ester.
[2] The polymer according to [1], wherein the molecular weight of the second monomer is a number average molecular weight.
[3] The polymer as described in [1] or [2], wherein the glass transition temperature of the polymer is −80 to −40° C.
[4] The polymer as described in any one of [1] to [3], wherein the polymer has a number average molecular weight of 25,000 to 1,000,000.
[5] A curable composition containing the polymer according to any one of [1] to [4].
[6] The curable composition according to [5], further containing a crosslinking agent.
[7] The curable composition according to [5] or [6], which further contains a photopolymerization initiator.
[8] The curable composition according to any one of [5] to [7], wherein the ratio of the total amount of the polymer to the total amount of the curable composition is 80% by mass or more.
[9] A cured product of the curable composition according to any one of [5] to [8].
[10] E′(−20° C.)/E′ representing the ratio of storage elastic modulus E′ (−20° C.) (kPa) at −20° C. to storage elastic modulus E′ (80° C.) (kPa) at 80° C. (80° C.) is a cured product according to [9], which is 1.5 to 4.
[11] A pressure-sensitive adhesive sheet, comprising a pressure-sensitive adhesive layer made of the cured product according to [9] or [10].
[12] The pressure-sensitive adhesive sheet according to [11], wherein the pressure-sensitive adhesive layer has a thickness of 10 to 150 μm.
[13] A laminate having an adhesive layer made of the cured product according to [9] or [10] and a flexible member laminated via the adhesive layer.
[14] The laminate according to [13], wherein the adhesive layer has a thickness of 10 to 150 μm.
[15] The laminate according to [13] or [14], wherein the flexible member is at least one selected from the group consisting of a surface protection panel, an optical film, a touch panel, and a display panel body.
[16] A flexible display including the laminate according to any one of [13] to [14].

The present invention provides a polymer, a curable composition, a cured product, an adhesive sheet, a laminate and a flexible display capable of forming a flexible laminate having excellent bending durability and shape recovery.

FIG. 1A is a front view showing an example of a sample before a tensile test in a method for measuring a creep recovery rate. FIG. 1B is a front view showing an example of the sample after the tensile test in the method for measuring the creep recovery rate.

In this specification, the compound represented by Formula 1 is referred to as Compound 1. The same applies to compounds represented by other formulas.
The definition of the term in this specification is as follows.
The “unit” means an atomic group formed directly by polymerizing a monomer (hereinafter, also referred to as “monomer”).
"Polyoxyalkylene chain" means a polymeric chain formed from units based on alkylene oxide monomers.
“(Meth)acrylate” means either or both of acrylate and methacrylate.
“(Meth)acryloyloxy” means either or both of acryloyloxy and methacryloyloxy.
The “number of functional groups” means the number of (meth)acryloyloxy groups in one molecule unless otherwise specified.
Unless otherwise specified, the “average number of functional groups” refers to the number of average (meth)acryloyloxy groups per molecular weight represented by the formula weight obtained based on the chemical formula or the number average molecular weight in one molecule. Means the average number of (meth)acryloyloxy groups.
“Prepolymer” means a urethane prepolymer having an isocyanate group at the terminal, unless otherwise specified.
The “index” is a value obtained by multiplying a value obtained by dividing the number of moles of isocyanate groups of an isocyanate compound by the number of moles of hydroxyl groups of an oxyalkylene polymer by 100 times.
“Sheet” conceptually encompasses sheets, films and tapes.
"Flexible" means a bendable or bendable property. “Flexible” means, for example, a property that the shape is recovered even when folded to a bending radius of less than 3 mm (Foldable), a property that the shape is recovered even when bent or rolled to a bending radius of 3 mm or more (Rollable), and fixed in a curved state. Includes properties that do not break (Bendable).

The hydroxyl value of the polyol is a value obtained by measurement according to JIS K 1557:2007.
The hydroxyl group-converted molecular weight is a value calculated by applying the hydroxyl value to the formula of “{56100/(hydroxyl value)}×(number of hydroxyl groups of initiator)”.
The number average molecular weight (hereinafter, also referred to as “Mn”) is a polystyrene-equivalent molecular weight obtained by measurement by gel permeation chromatography (GPC) using a calibration curve prepared using a standard polystyrene sample of known molecular weight. Is. The molecular weight distribution is a value obtained by dividing a mass average molecular weight (hereinafter also referred to as “Mw”. Mw is a polystyrene-equivalent molecular weight obtained by measurement by GPC similarly to Mn) by Mn (hereinafter also referred to as “Mw/Mn”). I say.). When a peak of an unreacted low molecular weight component (for example, a monomer) appears in the GPC measurement, the peak is excluded to determine Mn and Mw.
When Mw/Mn does not exist when the molecular weight of the compound is defined by Mn, the molecular weight represented by the formula weight obtained based on the chemical formula of the compound is regarded as Mn.

The glass transition temperature of the cured product is the tan δ peak temperature obtained in the dynamic viscoelasticity measurement of the cured product.
The glass transition temperature of a polymer is the value obtained by differential scanning calorimetry (DSC) of the polymer.
The glass transition temperature of a reactive oligomer is a tan δ peak temperature obtained in dynamic viscoelasticity measurement of a cured product of the reactive oligomer. The cured product of the reactive oligomer is a cured product obtained by adding a photoinitiator to only the reactive oligomer and curing it.
The storage elastic modulus of the cured product is the storage elastic modulus E′ (kPa) under the condition that the strain of the test sample is 1%. The test sample is prepared by curing the curable composition into a size of width 5 mm×length 15 mm×thickness 2 mm. The storage elastic modulus E′ is measured under the following measurement conditions using a dynamic viscoelasticity measuring device (EXSTAR 6100, Seiko Instruments Inc. product name) using the above test sample.
Mode: Tensile mode Temperature range: -80 to 130°C
Temperature rising rate: 3°C/min
Measurement frequency: 1 Hz

[Polymer]
The polymer of the present invention (hereinafter also referred to as “polymer X”) includes a unit based on a first monomer (hereinafter also referred to as “monomer A”) and a second monomer (hereinafter also referred to as “monomer B”). The unit based on

<Monomer A>
Monomer A is a (meth)acrylic acid ester whose Mn is 1,000 or less.
Examples of the monomer A include alkyl (meth)acrylates, carboxy group-containing monomers, hydroxyl group-containing monomers, amino group-containing monomers, and epoxy group-containing compounds described in International Publication No. 2018/173896 [0095] to [0110]. Examples thereof include monomers, amide group-containing monomers, vinyl monomers and macromonomers.
The monomer A may be used in combination of two or more kinds.

Suitable examples of the monomer A include the monomer a1, the monomer a2, the monomer a3, and the monomer a4.
Monomer a1: An alkyl(meth)acrylate in which an alkyl group having 4 to 18 carbon atoms is bonded to a (meth)acryloyloxy group. The alkyl group having 4 to 18 carbon atoms is preferably linear or branched.
Monomer a2: A monomer having a carboxy group and copolymerizable with the monomer a1.
Monomer a3: A monomer having an organic functional group and copolymerizable with the monomer a1. The organic functional group is preferably at least one selected from the group consisting of a hydroxy group and an amide group, more preferably a hydroxy group.
Monomer a4: (meth)acrylic acid ester of polyoxyalkylene monool.

Specific examples of the monomer a1 include n-butyl(meth)acrylate, isobutyl(meth)acrylate, sec-butyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, isopentyl(meth)acrylate, neopentyl. (Meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate and Isostearyl (meth)acrylate.
When an alkyl (meth)acrylate in which a linear alkyl group having 4 to 18 carbon atoms is bonded to a (meth)acryloyloxy group is used as the monomer A, the cured product of the present invention tends to be flexible.

Specific examples of the monomer a2 include (meth)acrylic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyl Oxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid and itaconic acid.
When the monomer a2 is used as the monomer A, the cured product of the present invention is unlikely to become cloudy under high temperature and high humidity conditions (wet heat resistance). Further, the adhesive strength of the cured product of the present invention is likely to be improved.

Specific examples of the monomer a3 include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, (meth)acrylamide, N, N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylolpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide , Diacetone (meth)acrylamide, maleic acid amide and maleimide.
When the monomer a3 is used as the monomer A, the wet heat resistance of the cured product of the present invention is easily improved. A hydroxyalkyl (meth)acrylate is particularly preferable as the monomer a3.

Specific examples of the monomer a4 include methoxy polyethylene glycol (meth)acrylate, ethoxy polyethylene glycol (meth)acrylate, 2-ethylhexyl polyethylene glycol (meth)acrylate, octoxy polyethylene glycol (meth)acrylate, lauroxy polyethylene glycol (meth)acrylate. , Stearoxy polyethylene glycol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, methoxy polypropylene glycol (meth)acrylate, ethoxy polypropylene glycol (meth)acrylate, 2-ethylhexyl polypropylene glycol (meth)acrylate, octoxy polypropylene glycol (meth) ) Acrylate, lauroxy polypropylene glycol (meth)acrylate, stearoxy polypropylene glycol (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, methoxy polyethylene glycol-polypropylene glycol (meth)acrylate, ethoxy polyethylene glycol-polypropylene glycol (meth)acrylate 2-ethylhexyl polyethylene glycol-polypropylene glycol (meth)acrylate, octoxy polyethylene glycol-polypropylene glycol (meth)acrylate, lauroxy polyethylene glycol-polypropylene glycol (meth)acrylate, stearoxy polyethylene glycol-polypropylene glycol (meth)acrylate and Phenoxy polyethylene glycol-polypropylene glycol (meth)acrylate.

As the polyoxyalkylene monool constituting the monomer a4, the compound 3a described later, which has a hydroxyl value of 56.1 mgKOH/g or more, is preferable.
The monomer a4 is preferably at least one selected from the group consisting of polyoxyethylene monool (meth)acrylic acid ester and polyoxypropylene monool (meth)acrylic acid ester.

The constitution of the unit based on the monomer A in the polymer X is preferably the following aspect (1) or (2).
(1) The proportion of the units based on the monomer a1 is 50 to 99.9 mass% and the proportion of the units based on the monomer a2 is 0.1 to 5.0 mass% with respect to the total amount of the units based on the monomer A. And the total ratio of these is 50.1 to 100 mass %.
(2) The proportion of the units based on the monomer a1 is 50 to 99.9 mass% and the proportion of the units based on the monomer a3 is 1.0 to 20.0 mass% with respect to the total amount of the units based on the monomer A. And the total proportion of these is 51.0 to 100% by mass.

The molecular weight based on the formula weight of the monomer A is 1,000 or less, preferably 70 to 1,000, more preferably 70 to 700, and further preferably 80 to 400. When the molecular weight based on the formula weight of the monomer A is not more than the upper limit of the above range, the cured product of the present invention tends to be flexible.
When two or more kinds of the monomer A are used, it is preferable that the molecular weights of the two or more kinds of the monomer A based on the formula weight are each within the above range.
The Mn of the monomer A is 1,000 or less, preferably 70 to 1,000, more preferably 70 to 700, and further preferably 80 to 400. When Mn of the monomer A is at most the upper limit value of the above range, the cured product of the present invention tends to be flexible.
When using 2 or more types of monomer A, it is preferable that each of Mn of the 2 or more types of monomer A is in the said range.

<Monomer B>
Monomer B is a (meth)acrylic acid ester having an Mn of 5,000 to 25,000 and having one or more polyoxyalkylene chains and one (meth)acryloyloxy group in one molecule. ..
The monomer B may use 2 or more types together.
The unit based on the monomer B in the polymer X contributes to reduction of shrinkage of the curable composition of the present invention during curing, and contributes to reduction of elastic modulus and reduction of Tg of the cured product of the present invention. By using the cured product of the present invention as an adhesive layer of a laminate, the bending durability and shape recovery of the laminate of the present invention can be improved.

As the monomer B, an oligomer having one or more urethane bonds in one molecule (hereinafter, also referred to as “oligomer B′”) is preferable. The number of urethane bonds in one molecule of the oligomer B′ is preferably one. When the number of urethane bonds in one molecule of the oligomer B′ is 1, shrinkage during curing of the curable composition of the present invention is likely to be reduced, and elastic modulus of the cured product of the present invention is likely to be reduced.
The proportion of urethane bonds with respect to the total weight of the oligomer B′ is preferably 0.3 to 1.9% by mass, more preferably 0.32 to 1.6% by mass, and further preferably 0.35 to 1.3% by mass. .. When the ratio of urethane bond to the total mass of the oligomer B'is within the above range, the cured product of the present invention can easily obtain good tackiness.
The ratio of urethane bond to the total mass of the oligomer B′ is calculated by the following calculation formula.
Ratio of urethane bond (unit: %)={Mi×59/Wb}×100
Wb: total mass of the monomer B Mi: total number of moles of isocyanate groups present in the isocyanate compound used to produce the monomer B having a mass of Wb However, if all of the isocyanate groups present in the isocyanate compound used to produce the oligomer B′ are It is considered that a urethane bond (molecular weight 59) is formed.

In the manufacturing process of the monomer B, a by-product other than the monomer B may be mixed in the product (hereinafter, also referred to as “product B”).
The ratio of the monomer B to the total mass of the product B is preferably 80% by mass or more, more preferably 85 to 100% by mass. When the ratio of the monomer B to the total mass of the product B is 80% by mass or more, the product B can sufficiently exhibit the function as the monomer B. When the product B contains 80% by mass or more of the monomer B based on the total mass of the product B, the product B can sufficiently exhibit the function of the monomer B, and thus the product B can be regarded as the monomer B.

When the product B can be regarded as the monomer B, the average functional group number of the product B obtained from the Mn of the product B and the functional group number can be regarded as the average functional group number of the monomer B. In this case, the average functional group number of the product B is preferably 0.8 to 1.3, more preferably 0.9 to 1.2. When the average number of functional groups of the product B is within the above range, the product B is likely to sufficiently exhibit the function of the monomer B. The average number of functional groups of the product B can be adjusted by the amount of impurities contained in the raw material for producing the monomer B and the index described later. In addition, in the present specification, the average number of (meth)acryloyloxy groups can be calculated by using the average number of functional groups and index of raw materials described later.

The Mn of the monomer B is 5,000 to 25,000, preferably 6,000 to 24,500, and more preferably 7,000 to 24,000. When the Mn of the monomer B is within the above range, the viscosity of the curable composition of the present invention can be easily adjusted. Further, when the Mn of the monomer B is at least the lower limit value of the above range, the curing shrinkage rate during curing of the curable composition of the present invention is likely to be reduced.
When using 2 or more types of monomer B, it is preferable that each of Mn of the 2 or more types of monomer B is in the said range.
The Mw/Mn of the monomer B is preferably 1.03 to 1.2, more preferably 1.04 to 1.15, and further preferably 1.05 to 1.14.
When using 2 or more types of monomer B, it is preferable that each of Mw/Mn of the 2 or more types of monomer B is in the said range.
The glass transition temperature of the monomer B is preferably −55° C. or lower, more preferably −58° C. or lower, and even more preferably −60° C. or lower. When the glass transition temperature of the monomer B is not more than the upper limit value of the above range, the bending durability of the laminate of the present invention at low temperature is more excellent.
The glass transition temperature of the monomer B is preferably −85° C. or higher, more preferably −80° C. or higher, even more preferably −75° C. or higher. When the glass transition temperature of the monomer B is at least the lower limit value of the above range, the creep recovery rate of the laminate of the present invention is likely to be improved.
The glass transition temperature of the monomer B is preferably −85° C. to −55° C., more preferably −80° C. to −58° C., further preferably −75° C. to −60° C. When the glass transition temperature of the monomer B is not more than the upper limit value of the above range, the bending durability of the laminate of the present invention at low temperature is more excellent.
When two or more monomers B are used, the glass transition temperatures of the two or more monomers B are preferably in the range of -85 to -55°C.

Specific examples of the monomer B are the monomer B-1, the monomer B-2, and the monomer B-3 described below. Two or more kinds of the monomer B-1, the monomer B-2 and the monomer B-3 may be used in combination.

Monomer B preferably contains at least one selected from the group consisting of monomer B-1 and monomer B-2.
The total ratio of the monomer B-1 and the monomer B-2 to the total mass of the monomer B is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 100% by mass. When the ratio of the total amount of the monomer B-1 and the monomer B-2 to the total mass of the monomer B is at least the lower limit value of the above range, the curing shrinkage rate during curing of the curable composition of the present invention is easily reduced. .. Further, the flexibility of the cured product of the present invention is easily improved. The ratio (B-1):(B-2) representing the mass ratio of the monomer B-1 and the monomer B-2 is preferably 1:0 to 1:1.

(Monomer B-1)
Monomer B-1 is an equimolar reaction product of polyoxyalkylene monool and a compound having an isocyanate group and a (meth)acryloyloxy group.
The polyoxyalkylene monool is a compound obtained by ring-opening polymerization of an alkylene oxide with an initiator having one active hydrogen. The polyoxyalkylene monool has an initiator residue, a polyoxyalkylene chain and a hydroxyl group corresponding to the number of active hydrogens in the initiator.
The alkylene oxide is preferably an alkylene oxide having 2 to 4 carbon atoms. Specific examples of the alkylene oxide are propylene oxide, ethylene oxide, 1,2-butylene oxide and 2,3-butylene oxide.
Examples of the active hydrogen-containing group in the above initiator are a hydroxyl group, a carboxy group, and an amino group having one hydrogen atom bonded to a nitrogen atom. The active hydrogen-containing group is preferably at least one selected from the group consisting of a hydroxyl group and a carboxy group, more preferably a hydroxyl group, and even more preferably an alcoholic hydroxyl group.
Examples of the above-mentioned initiator having one active hydrogen are a monohydric alcohol, a monohydric phenol, a monovalent carboxylic acid, and an amine compound having one hydrogen atom bonded to a nitrogen atom. The initiator having one active hydrogen is preferably at least one selected from the group consisting of monohydric aliphatic alcohols and monohydric aliphatic carboxylic acids. As the initiator having one active hydrogen, a polyoxyalkylene monool having a lower molecular weight than the target polyoxyalkylene monool (hereinafter, also referred to as "low molecular weight polyoxyalkylene monool") may be used. Good.
The monohydric aliphatic alcohol preferably has 1 to 20 carbon atoms, more preferably 2 to 8 carbon atoms.
The carbon number of the monovalent aliphatic carboxylic acid, including the carbon atom in the carboxy group, is preferably 2 to 20, and more preferably 2 to 8.
The oxyalkylene group in the polyoxyalkylene monool is preferably composed of only an oxypropylene group or a combination of an oxypropylene group and another group, and as the oxyalkylene group other than the oxypropylene group, An oxyethylene group is preferred. The ratio of oxypropylene groups to the total oxyalkylene groups in the polyoxyalkylene monool is preferably 50 to 100% by mass, more preferably 80 to 100% by mass. When the low molecular weight polyoxyalkylene monool is used as the initiator, the oxyalkylene group in the low molecular weight polyoxyalkylene monool is regarded as the oxyalkylene group in the obtained polyoxyalkylene monool.

The low hydroxyl value (that is, high molecular weight) polyoxyalkylene monool is obtained by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms (particularly propylene oxide) as an initiator in the presence of a double metal cyanide complex catalyst. Can be manufactured.
The polyoxyalkylene monool having an oxyethylene group and having a low hydroxyl value is obtained by using a polyoxyalkylene monool having an oxyethylene group and having a high hydroxyl value (preferably 50 mgKOH/g or more) as an initiator. It can be produced by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms (particularly propylene oxide) in the presence.
The polyoxyalkylene monool having a high hydroxyl value can be produced by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms with an initiator in the presence of an alkali catalyst such as KOH.
The polyoxyalkylene monool used for producing the monomer B-1 may be a mixture of two or more polyoxyalkylene monools. In this case, each polyoxyalkylene monool is preferably a polyoxyalkylene monool included in the above category.
In the production of the above-mentioned polyoxyalkylene monool, the initiator and the alkylene oxide to be added into the reaction system are usually those having a low water content, which have been dewatered by means such as degassing under reduced pressure.
The smaller the water content of the initiator in the production of polyoxyalkylene monool, the more preferable. Specifically, the water content of the initiator is preferably 500 mass ppm or less, and more preferably 300 mass ppm or less, based on the total amount of the initiator. When the water content of the initiator is 500 ppm by mass or less based on the total amount of the initiator, the amount of polyoxyalkylene diol produced from water is sufficiently suppressed, and thus the polyoxyalkylene is finally obtained. The amount of by-products generated from the diol is reduced, and it is easy to adjust the upper limit of the average number of hydroxyl groups of the resulting polyoxyalkylene monool to 1.2 or less.
It is preferable that the water content of the polyoxyalkylene monool used as a raw material in the production of the polyoxyalkylene monool is smaller. Specifically, the water content of the polyoxyalkylene monool is preferably 300 mass ppm or less, more preferably 250 mass ppm or less, and further preferably 50 to 200 mass ppm with respect to the total amount of the polyoxyalkylene monool. preferable. When the water content of the polyoxyalkylene monool is 300 mass ppm or less with respect to the total amount of the polyoxyalkylene monool, a by-product which is a reaction product of water and an isocyanate group-containing compound is produced. Less, the stability of the reaction product is improved. Furthermore, changes in the appearance of the curable composition of the present invention with time are easily suppressed, and the elastic modulus of the cured product of the present invention tends to be good.
The compound having an isocyanate group and a (meth)acryloyloxy group used for producing the monomer B-1 is preferably a (meth)acrylate having one isocyanate group, more preferably an isocyanate alkyl (meth)acrylate.
As the (meth)acrylate having one isocyanate group, a (meth)acrylate having an isocyanate group bonded to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group is preferable, and an isocyanate group alkyl (meth)acrylate is particularly preferable. .. 8 or less is preferable and, as for carbon number of the alkyl group except an isocyanate group of an isocyanate group alkyl group, 4 or less is more preferable.
Specific examples of the (meth)acrylate having one isocyanate group are 2-isocyanatoethyl (meth)acrylate and isocyanate methyl methacrylate. Examples of commercially available (meth)acrylates having one isocyanate group include Karenz-AOI and Karenz-MOI (both are Showa Denko KK product names).
The preferable range of Mn of the monomer B-1 is the same as that of the monomer B.
The monomer B-1 is preferably the compound 3 described below.

The monomer B-1 is preferably the compound 3 obtained by reacting the compound 3a with the compound 3b. Since the compound 3a and the compound 3b each have one group capable of urethanization reaction present in one molecule, it is easy to control one urethane bond in one molecule of the monomer B-1. When the number of urethane bonds in one molecule of the monomer B-1 is small, the viscosity of the curable composition of the present invention tends to be low. Therefore, it is more preferable that the monomer B contains the monomer B-1 from the viewpoint that the curable composition of the present invention has a lower viscosity and the cured product of the present invention has more excellent flexibility.

In

equations

3, 3a and 3b:
R ¹¹ is a hydrogen atom or a methyl group, and preferably a hydrogen atom.
R ¹² is an alkylene group having 2 to 4 carbon atoms, and a plurality of R ¹² present in one molecule may be the same as or different from each other. When two or more types of R ¹² are present in one molecule, the —OR ¹² — chain may be block or random. R ¹² is preferably an ethylene group and/or a propylene group.
R ¹³ represents an alkyl group having 1 to 20 carbon atoms or a carboxylic acid residue having 1 to 20 carbon atoms together with an oxygen atom bonded to R ¹³ . The carboxylic acid residue is a monovalent group obtained by removing one hydrogen atom in the carboxy group from a monocarboxylic acid having 1 to 20 carbon atoms, which includes the carbon atom in the carboxy group. R ¹³ is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 2 to 8 carbon atoms from the viewpoint of easy reaction.
b is an integer of 1 to 8, preferably an integer of 1 to 4.
c is an integer of 20 to 600, preferably an integer of 35 to 500, and more preferably an integer of 65 to 250.

Compound 3a is a polyoxyalkylene monool. The compound 3a is obtained by a known method of ring-opening polymerizing an alkylene oxide with an alcohol or a compound obtained by adding an alkylene oxide to an alcohol as an initiator, or a known method of ring-opening polymerizing an alkylene oxide with a carboxy group of a monocarboxylic acid. ..
The hydroxyl value of the compound 3a is preferably 2.3 mgKOH/g or more and less than 56.1 mgKOH/g, more preferably 3 to 14 mgKOH/g.
The hydroxyl group-equivalent molecular weight of the compound 3a is preferably more than 1,000 and 25,000 or less, more preferably 4,000 to 15,000. When the hydroxyl group-converted molecular weight of the compound 3a is within the above range, the Mn of the monomer B-1 can be adjusted within the range of 5,000 to 25,000. When the compound 3a has a hydroxyl group-converted molecular weight within the above range, the average number of functional groups of the resulting monomer B-1 can be easily adjusted within the range of 0.8 to 1.3. The smaller the hydroxyl group-converted molecular weight, the easier it is to adjust the upper limit of the average number of functional groups to 1.3 or less.

In the production of compound 3a, it is not particularly necessary to remove water by a means such as degassing under reduced pressure, and the amount of water normally contained in the raw materials and the like fed into the reaction system is acceptable. The smaller the amount of water in the system, the better. The water content in the system is preferably 500 ppm or less, more preferably 300 ppm or less. When the amount of water in the system is not more than the above upper limit, the amount of diol produced from water is suppressed. As a result, the amount of the by-product formed by finally adding the (meth)acryloyloxy group to the diol is suppressed, and the upper limit of the average number of functional groups of the by-product and the product B containing the monomer B is 1.2. Easy to adjust below.

As the compound 3b, a commercially available product can be used. Specific examples of commercially available compounds 3b include Karenz-AOI (R ¹¹ =H, b=1 in Formula 3b) and Karenz-MOI (R ¹¹ =CH ₃ , b=1 in Formula 3b) (all are Showa Denko). Company product name).
In the production process of the monomer B-1, a by-product other than the monomer B-1 may be mixed in the product (hereinafter also referred to as “product B-1”).
The reaction between the compound 3a and the compound 3b is a urethanization reaction, and can be performed using a known method.
When the compound 3a and the compound 3b are reacted, the compounding ratio of the compound 3b to the compound 3a is preferably 80 to 100, more preferably 90 to 100, and most preferably 100 in terms of index (NCO/OH ratio). When the index is within the above range, it is easy to adjust the average number of functional groups of the product B-1 within the range of 0.8 to 1.2.

The ratio of the monomer B-1 to the total mass of the product B-1 is preferably 80% by mass or more, more preferably 85 to 100% by mass. When the ratio of the monomer B-1 to the total mass of the product B-1 is 80% by mass or more, the product B-1 can sufficiently exhibit the function of the monomer B-1. Can be considered

When the product B-1 can be regarded as the monomer B-1, the average functional group number of the product B-1 calculated from Mn and the functional group number of the product B-1 is the average functional group of the monomer B-1. It can be regarded as a radix. In this case, the average number of functional groups of the product B-1 is preferably 0.8 to 1.3, more preferably 0.9 to 1.2. When the average number of functional groups of the product B-1 is within the above range, shrinkage during curing of the curable composition of the present invention is likely to be reduced, and the elastic modulus of the cured product of the present invention is likely to be reduced.

The monomer B-1 preferably contains the compound 3 and the monomer B-1-PO containing 50 to 100 mol% of a propylene group with respect to the total amount of R ¹² present in one molecule.

In the monomer B-1-PO, the proportion of propylene groups relative to the total amount of R ¹² is more preferably 80 to 100 mol%, particularly preferably 100 mol%. Of R ¹² existing in one molecule, the alkylene group other than the propylene group is preferably an ethylene group.

When using the monomer B-1-PO, the ratio of the monomer B-1-PO to the total amount of the monomer B is preferably 50 to 100% by mass, more preferably 80 to 100% by mass. When the ratio of the monomer B-1-PO to the total amount of the monomer B is at least the lower limit value of the above range, the curable composition of the present invention has a lower viscosity and the cured product of the present invention is more flexible. ..

(Monomer B-2)
Monomer B-2 is an equimolar reaction product of polyoxyalkylene monool, diisocyanate, and a compound having a group that reacts with an isocyanate group and a (meth)acryloyloxy group.
The polyoxyalkylene monool in the monomer B-2 is the same as the polyoxyalkylene monool in the monomer B-1 described above.
Examples of the group reactive with an isocyanate group and the group reactive with an isocyanate group in a compound having a (meth)acryloyloxy group are a hydroxyl group, an amino group having a nitrogen atom bonded to a hydrogen atom, and the like. The number of hydroxyl groups in the group that reacts with the isocyanate group or the number of hydrogen atoms bonded to nitrogen atoms is preferably 1. As the group that reacts with the isocyanate group, a hydroxyl group bonded to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group is preferable.
Examples of the compound having a group that reacts with the isocyanate group and a (meth)acryloyloxy group are hydroxyalkyl(meth)acrylate and hydroxycycloalkyl(meth)acrylate. The compound having a group that reacts with an isocyanate group and a (meth)acryloyloxy group is preferably a hydroxyalkyl (meth)acrylate or a hydroxycycloalkyl (meth)acrylate, and a hydroxyalkyl having a hydroxyalkyl group having 8 or less carbon atoms. (Meth)acrylate is particularly preferred. Specific examples of the hydroxyalkyl (meth)acrylate having a hydroxyalkyl group having 8 or less carbon atoms include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Hydroxybutyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate.
Commercially available products of the above-mentioned compound having a group capable of reacting with an isocyanate group and a (meth)acryloyloxy group are light ester HO-250(N), light ester HOP(N), light ester HOA(N), light ester HOP- Examples include A(N) and light ester HOB(N) (both are product names of Kyoei Chemical Co., Ltd.), and 4-HBA (product name of Osaka Organic Chemical Industry Co., Ltd.).
The preferable range of Mn of the monomer B-2 is the same as that of the monomer B.
The monomer B-2 is preferably the compound 4 described below.
Monomer B-2 is prepared by reacting compound 4a with compound 4b to obtain a prepolymer having an isocyanate group at the terminal (isocyanate group-terminated urethane prepolymer), and then reacting compound 4c with the isocyanate group of the above prepolymer. Compound 4 thus obtained is preferred.

In equations 4, 4a, 4b and 4c:
R ²¹ is a hydrogen atom or a methyl group, and preferably a hydrogen atom.
R ²² is an alkylene group having 2 to 4 carbon atoms, and a plurality of R ²² existing in one molecule may be the same as or different from each other. When two or more kinds of R ²² are present in one molecule, the chain of —OR ²² — may be block or random. R ²² is preferably an ethylene group and/or a propylene group.
R ²³ represents an alkyl group having 1 to 20 carbon atoms or a carboxylic acid residue having 1 to 20 carbon atoms together with an oxygen atom bonded to R ²³ . The carboxylic acid residue is a monovalent group obtained by removing one hydrogen atom in the carboxy group from a monocarboxylic acid having 1 to 20 carbon atoms, which includes the carbon atom in the carboxy group. R ²³ is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 2 to 8 carbon atoms from the viewpoint of easy reaction.

R ²⁴ is a divalent group obtained by removing the isocyanate group from compound 4b. Examples of the compound 4b include compounds having two isocyanate groups, and isophorone diisocyanate and hexamethylene diisocyanate are preferable.
d is an integer of 1 to 8, preferably an integer of 1 to 4.
e is an integer of 20 to 600, preferably an integer of 35 to 500, and more preferably an integer of 65 to 250.

Compound 4a is a polyoxyalkylene monool. The compound 4a is obtained by a known method of ring-opening polymerization of an alkylene oxide using an alcohol or a compound obtained by adding an alkylene oxide to an alcohol as an initiator, or a known method of ring-opening polymerization of an alkylene oxide at a carboxy group of a monocarboxylic acid. ..
The hydroxyl value of the compound 4a is preferably 2.3 mgKOH/g or more and less than 56.1 mgKOH/g, more preferably 3 to 14 mgKOH/g.
The compound 4a has a hydroxyl group-equivalent molecular weight of preferably more than 1,000 and not more than 25,000, more preferably 4,000 to 15,000. When the hydroxyl group-converted molecular weight of the compound 4a is within the above range, the Mn of the monomer B-2 can be adjusted within the range of 5,000 to 25,000.

The water content and molecular weight when producing compound 4a are the same as when producing compound 3a. Also in the case of producing the compound 4a, as in the case of producing the compound 3a, a product containing a monomer B-2 and a by-product obtained by adding a (meth)acryloyloxy group to a diol produced from water contained in the raw material. (Hereinafter, also referred to as “product B-2”) may be obtained.

The reaction of reacting the compound 4a with the compound 4b to obtain a prepolymer having an isocyanate group at the terminal (isocyanate group-terminated urethane prepolymer) is a urethanization reaction and can be carried out using a known method.
When the compound 4a and the compound 4b are reacted, the compounding ratio of the compound 4b to the compound 4a is preferably 100 to 200, more preferably 180 to 200, and most preferably 200 in terms of index (NCO/OH ratio).

By setting the index within the above range, the average number of functional groups of the product B-2 can be adjusted within the range of 0.8 to 1.3.

The reaction between the isocyanate group-terminated urethane prepolymer and the compound 4c is a urethanization reaction, and can be performed using a known method.

When the isocyanate group-terminated urethane prepolymer and the compound 4c are reacted, the compounding ratio of the isocyanate group-terminated urethane prepolymer and the compound 4c is such that the number of moles of isocyanate groups in the isocyanate group-terminated urethane prepolymer: in the compound 4c. In terms of the number of moles of the hydroxyl group, the ratio is preferably from 1:1.0 to 1.1, more preferably from 1:1.0 to 1.05. When the compounding ratio is within the above range, it is easy to adjust the average number of functional groups of the product B-2 within the range of 0.8 to 1.2.
The ratio of the monomer B-2 to the total mass of the product B-2 is preferably 80% by mass or more, more preferably 85 to 100% by mass. When the ratio of the monomer B-2 to the total mass of the product B-2 is 80% by mass or more, the product B-2 can sufficiently exhibit the function as the monomer B-2, so that the product B-2 is It can be regarded as the monomer B-2.

When the product B-2 can be regarded as the monomer B-2, the average number of functional groups obtained from Mn and the number of functional groups of the product B-2 can be regarded as the average number of functional groups of the monomer B-2. .. In this case, the average number of functional groups of the product B-2 is preferably 0.8 to 1.3, more preferably 0.9 to 1.2. When the average number of functional groups of the product B-2 is within the above range, shrinkage during curing of the curable composition of the present invention is likely to be reduced, and the elastic modulus of the cured product of the present invention is likely to be reduced.

The monomer B-2 preferably contains the compound 4 and the monomer B-2-PO containing 50 to 100 mol% of a propylene group with respect to the total amount of R ²² present in one molecule.

In the monomer B-2-PO, the proportion of propylene groups relative to the total amount of R ²² is more preferably 80 to 100 mol%, particularly preferably 100 mol%. Of R ²² existing in one molecule, the alkylene group other than the propylene group is preferably an ethylene group.

When using the monomer B-2-PO, the ratio of the monomer B-2-PO to the total amount of the monomer B is preferably 50 to 100% by mass, more preferably 80 to 100% by mass. When the ratio of the monomer B-2-PO to the total amount of the monomer B is at least the lower limit value of the above range, the curable composition of the present invention has a lower viscosity and the cured product of the present invention is more flexible. ..

(Monomer B-3)
Monomer B-3 is an equimolar reaction product of a polyoxyalkylene polyol and a compound having an isocyanate group and a (meth)acryloyloxy group.
The polyoxyalkylene polyol is a compound obtained by ring-opening polymerization of an alkylene oxide with an initiator having two or more active hydrogens. The polyoxyalkylene polyol has an initiator residue, a polyoxyalkylene chain and hydroxyl groups corresponding to the number of active hydrogens in the initiator.
The alkylene oxide is preferably an alkylene oxide having 2 to 4 carbon atoms. Specific examples of the alkylene oxide are propylene oxide, ethylene oxide, 1,2-butylene oxide and 2,3-butylene oxide.
The initiator having two or more active hydrogens has an active hydrogen-containing group. Examples of the active hydrogen-containing group are a hydroxyl group, a carboxy group, and an amino group having a hydrogen atom bonded to a nitrogen atom. The active hydrogen-containing group is preferably a hydroxyl group, more preferably an alcoholic hydroxyl group.
Examples of the above-mentioned initiator having two or more active hydrogens are polyhydric alcohols, polyhydric phenols, polyhydric carboxylic acids, and amine compounds having two or more hydrogen atoms bonded to nitrogen atoms. As the initiator having two or more active hydrogens, a compound having two or more hydroxyl groups is preferable, and a dihydric aliphatic alcohol is more preferable. As the initiator having two or more active hydrogens, a polyoxyalkylene polyol having a lower molecular weight than the target polyoxyalkylene polyol (hereinafter, also referred to as “low molecular weight polyoxyalkylene polyol”) may be used.
The dihydric aliphatic alcohol preferably has 2 to 8 carbon atoms.
Specific examples of the dihydric aliphatic alcohol include polypropylene glycol such as ethylene glycol, propylene glycol, dipropylene glycol, and 1,4-butanediol.

The oxyalkylene group in the polyoxyalkylene polyol is preferably composed of only an oxypropylene group or a combination of an oxypropylene group and another group, and an oxyalkylene group other than oxypropylene group is oxy. Ethylene groups are preferred. The ratio of oxypropylene groups to all oxyalkylene groups in the above polyoxyalkylene polyol is preferably 50 to 100% by mass, more preferably 80 to 100% by mass. When the low molecular weight polyoxyalkylene polyol is used as an initiator, the oxyalkylene group in the low molecular weight polyoxyalkylene polyol is regarded as the oxyalkylene group in the resulting polyoxyalkylene polyol.

A low hydroxyl value (that is, high molecular weight) polyoxyalkylene polyol is produced by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms (particularly propylene oxide) as an initiator in the presence of a double metal cyanide complex catalyst. it can. Examples of the polyoxyalkylene polyol having a low hydroxyl value include polyoxyalkylene polyols having a hydroxyl value of 40 mgKOH/g or less.
The polyoxyalkylene polyol having a low hydroxyl value having an oxyethylene group is obtained by using a polyoxyalkylene polyol having a high hydroxyl value having an oxyethylene group (preferably 50 mgKOH/g or more) as an initiator in the presence of a double metal cyanide complex catalyst. Can be produced by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms (particularly propylene oxide).
The high hydroxyl value polyoxyalkylene polyol can be produced by ring-opening polymerization of an alkylene oxide having 3 or more carbon atoms with an initiator in the presence of an alkali catalyst such as KOH.

The polyoxyalkylene polyol used for producing the monomer B-3 may be a mixture of two or more polyoxyalkylene polyols. In this case, each polyoxyalkylene polyol is preferably a polyoxyalkylene polyol included in the above category, and more preferably a polyoxyalkylene diol included in the above category.
The compound having an isocyanate group and a (meth)acryloyloxy group used for producing the monomer B-3 is the same as the compound having an isocyanate group and a (meth)acryloyloxy group used for producing the monomer B-1. be able to.
The preferable range of Mn of the monomer B-3 is the same as that of the monomer B.
As the monomer B-3, a compound represented by the formula (V) is preferable.
R ³² -NH-C(=O)-Z... (V)
In formula (V):
R ³² represents a monovalent organic group having one (meth)acryloyloxy group.
Z is a residue of the polyoxyalkylene polyol obtained by removing one hydrogen atom from one hydroxyl group in the polyoxyalkylene polyol.

The monomer B-3 is more preferably an oligomer having one functional group, which is obtained by reacting the compound 5a and the compound 3b.

In equation 5a:
R ³² is an alkylene group having 2 to 8 carbon atoms, and a plurality of R ³² existing in one molecule may be the same as or different from each other. When two or more types of R ³² are present in one molecule, the —OR ³² — chain may be block or random. R ³² is preferably an ethylene group and/or a propylene group. The proportion of propylene groups relative to the total amount of R ³² is preferably 50 to 100 mol %, more preferably 80 to 100 mol %. Of R ³² existing in one molecule, an alkylene group other than a propylene group is preferably an ethylene group.

F is an integer of 20 to 600, preferably an integer of 35 to 500, and more preferably an integer of 65 to 250. When f is an integer of 20 to 600, Mn of the monomer B-3 can be adjusted within the range of 5,000 to 25,000.

The reaction between the compound 5a and the compound 3b is a urethanization reaction, and can be performed using a known method.
In the reaction between the compound 5a and the compound 3b, hydroxyl groups at both ends of the compound 5a can react with the compound 3b. Therefore, in addition to the oligomer having a functional group of 1, an oligomer having a functional group of 2 as a by-product. In some cases, a product containing (hereinafter, also referred to as “product B-3”) is obtained.
The average number of functional groups of the product B-3 is preferably 0.8 to 1.3, more preferably 0.9 to 1.2.

When the compound 5a and the compound 3b are reacted, the compounding ratio of the compound 3b to the compound 5a is preferably 30 to 50, more preferably 40 to 50, and most preferably 50 in terms of index (NCO/OH ratio). When the index is within the above range, a compound in which one molecule of the compound 5a is reacted with one molecule of the compound 3b is easily obtained, and the average number of functional groups of the product B-3 falls within the range of 0.8 to 1.2. Easy to adjust.

The ratio of the monomer B-3 to the total mass of the product B-3 is preferably 80% by mass or more, more preferably 85 to 100% by mass. When the ratio of the monomer B-3 to the total mass of the product B-3 is 80% by mass or more, the product B-3 can sufficiently exhibit the function as the monomer B-3, so that the product B-3 is It can be regarded as the monomer B-3.

When the product B-3 can be regarded as the monomer B-3, the average number of functional groups obtained from Mn and the number of functional groups of the product B-3 can be regarded as the average number of functional groups of the monomer B-3. .. In this case, the average functional group number of the product B-3 is preferably 0.8 to 1.3, more preferably 0.9 to 1.2. When the average number of functional groups of the product B-3 is within the above range, shrinkage during curing of the curable composition of the present invention is likely to be reduced, and the elastic modulus of the cured product of the present invention is likely to be reduced.

<Polymer X>
The ratio of the units based on the polymer B to all the constituent units of the polymer X is 0.1 to 50% by mass, preferably 5 to 45% by mass, more preferably 10 to 40% by mass, and further preferably 15 to 40% by mass. preferable. When the ratio of the units based on the polymer B to all the constituent units of the polymer X is at least the lower limit value of the above range, the bending durability of the cured product of the present invention at low temperature is improved. When the ratio of the units based on the polymer B to the total constitutional units of the polymer X is not more than the upper limit value of the above range, the curable composition of the present invention has low viscosity and the coatability is more excellent.

The polymer X may contain units based on other monomers in addition to the units based on the monomer A and the units based on the monomer B.
The above-mentioned other monomer may be copolymerizable with the monomer A and the monomer B. The total ratio of the units based on the monomer A and the units based on the monomer B with respect to all the structural units of the polymer X is preferably 70% by mass or more, more preferably 80% by mass or more, and may be 100% by mass.

The polymer X is obtained by copolymerizing a monomer mixture containing the monomer A and the monomer B. As the copolymerization method, a known method in which a monomer having a (meth)acryloyloxy group is polymerized using a radical polymerization initiator can be applied. As the polymerization method, known polymerization methods such as a solution polymerization method, a suspension polymerization method, a bulk polymerization method and an emulsion polymerization method can be applied.

The Mw of the polymer X is preferably more than 200,000 and not more than 2,000,000, more preferably 240,000 to 1,600,000, further preferably 280,000 to 1,200,000, and 280,000 to 960. 1,000 is even more preferred. When the Mw of the polymer X is at least the lower limit value of the above range, the cured product of the present invention tends to have better creep recovery rate and curl residual rate. When the Mw of the polymer X is at most the upper limit value of the above range, the curable composition of the present invention tends to have a lower viscosity, and good coatability is likely to be obtained.
When the curable composition of the present invention contains two or more kinds of polymer X, it is preferable that the Mw of each of the two or more kinds of polymer X is within the above range.
The Mn of the polymer X is preferably from 25,000 to 1,000,000, more preferably from 30,000 to 500,000, further preferably from 35,000 to 200,000, further preferably from 35,000 to 120,000. .. When Mn of the polymer X is at least the lower limit value of the above range, the cured product of the present invention tends to have better creep recovery rate and curl residual rate. When the Mn of the polymer X is at most the upper limit value of the above range, the curable composition of the present invention tends to have a lower viscosity, and good coatability is likely to be obtained.
When the curable composition of the present invention contains two or more kinds of polymer X, each Mn of the two or more kinds of polymer X is preferably within the above range.
The Mw/Mn of the polymer X is preferably 2.0 to 8.0, more preferably 2.1 to 7.8, even more preferably 2.2 to 7.5. When the Mw/Mn of the polymer X is at least the lower limit value of the above range, the adhesive strength of the cured product of the present invention tends to be better. When the Mw/Mn of the polymer X is not more than the upper limit of the above range, the cured product of the present invention tends to have a better creep recovery rate.
When the curable composition of the present invention contains two or more types of polymer X, it is preferable that the Mw/Mn of each of the two or more types of polymer X be within the above range.

The glass transition temperature of the polymer X is preferably −80 to −40° C., more preferably −75 to −45° C., further preferably −75 to −60° C. When the glass transition temperature of the polymer X is within the above range, the cured product of the present invention is less likely to peel off in a bending test at a low temperature.
When the curable composition of the present invention contains two or more kinds of polymer X, each of the glass transition temperatures of the two or more kinds of polymer X is preferably within the above range.

Since the curable composition of the present invention contains the polymer X, when cured, a cured product with little change in physical properties due to temperature can be obtained. By using this cured product as the adhesive layer of the laminate, the bending durability and shape recovery of the laminate can be improved.

[Curable composition]
The curable composition of the present invention comprises Polymer X.
The curable composition of the present invention may contain, in addition to the polymer X, a crosslinking agent, a photopolymerization initiator and other components, if necessary.

<Crosslinking agent>
The curable composition of the present invention preferably contains a crosslinking agent. The cross-linking agent is a compound having two or more cross-linkable functional groups. When the curable composition of the present invention is blended with the crosslinking agent, the heat resistance of the cured product of the present invention can be more easily improved.
The crosslinkable functional group is selected from the group consisting of (meth)acryloyl group, epoxy group, isocyanato group, carboxy group, hydroxy group, carbodiimide group, oxazoline group, aziridine group, vinyl group, amino group, imino group and amide group. At least one selected is preferred.
The number of the crosslinkable functional groups in one molecule of the crosslinker is preferably 2 to 4, more preferably 2 or 3, and even more preferably 2.
The crosslinkable functional group may be protected with a deprotectable protecting group.

As the crosslinking agent, polyfunctional (meth)acrylates and polyfunctional isocyanate compounds are preferable. Examples of the polyfunctional (meth)acrylate include the polyfunctional (meth)acrylates described in [0136] of International Publication No. 2018/173896. Examples of the polyfunctional isocyanate compound include the compounds described in [0062] of Japanese Patent No. 6375467.
The above-mentioned cross-linking agent is more preferably a polyfunctional (meth)acrylate, and 1,4-butanediol di(meth)acrylate and 1,6-hexanediol diacrylate are preferred because the cured product of the present invention can easily improve the creep recovery rate. At least selected from the group consisting of (meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate and tris(acryloxyethyl)isocyanurate. One kind is more preferable.
You may use together 2 or more types of the said crosslinking agent.

The amount of the cross-linking agent used is preferably 0.3 to 5 parts by mass, and more preferably 0.5 to 2 parts by mass, relative to 100 parts by mass of the polymer X. When the amount of the cross-linking agent used is at least the lower limit of the above range, the cured product of the present invention tends to have good heat resistance. When the amount of the cross-linking agent used is not more than the upper limit of the above range, the creep recovery rate of the cured product of the present invention is likely to be improved.

<Photopolymerization initiator>
The curable composition of the present invention may be a photocurable resin composition or a thermosetting resin composition. The curable composition of the present invention is preferably a photocurable resin composition because it can be cured at a low temperature and has a high curing rate.
When the curable composition of the present invention is a photocurable resin composition, the curable composition of the present invention preferably contains a photopolymerization initiator. If the curable composition of the present invention is a photocurable resin composition, for example, since it does not require a high temperature when used for manufacturing a display device, there is little risk of damage to the display device due to a high temperature. ..

The photopolymerization initiator functions as a reaction initiation aid in the crosslinking reaction of the crosslinking agent. As the photopolymerization initiator, a photopolymerization initiator which is sensitive to ultraviolet rays having a wavelength of 380 nm or less is preferable from the viewpoint of easy control of the crosslinking reaction.
Specific examples of the above photopolymerization initiator are the photopolymerization initiators described in [0147] to [0151] of International Publication No. 2018/173896.
As the photopolymerization initiator, a hydrogen abstraction type photopolymerization initiator in which the photoexcited initiator and the hydrogen donor in the system form an exciplex to transfer hydrogen of the hydrogen donor is preferable. Specific examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3′-dimethyl-4-methoxybenzophenone, and 4-(meta ) Acryloyloxybenzophenone, 4-[2-((meth)acryloyloxy)ethoxy]benzophenone, 4-(meth)acryloyloxy-4′-methoxybenzophenone, methyl 2-benzoylbenzoate and methyl benzoylformate.
You may use together 2 or more types of said photoinitiator.

The amount of the photopolymerization initiator used is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, relative to 100 parts by mass of the crosslinking agent. When the amount of the photopolymerization initiator used is within the above range, the curable composition of the present invention can easily obtain appropriate reaction sensitivity to active energy rays.

<Other ingredients>
The curable composition of the present invention may contain a conventionally known component, if necessary, as a component other than the polymer X, the crosslinking agent, and the photopolymerization initiator.
Examples of the above-mentioned other components include silane coupling agents, tackifying resins, antioxidants, light stabilizers, metal deactivators, rust inhibitors, antiaging agents, hygroscopic agents, hydrolysis inhibitors, antistatic agents. Agents, defoamers and inorganic particles.
The curable composition of the present invention may contain a reaction catalyst (a tertiary amine compound, a quaternary ammonium compound, a tin laurate compound or the like), if necessary.
The curable composition of the present invention may contain a solvent, if necessary.

The curable composition of the present invention cures a mixture of polymer X, an optional cross-linking agent, a photopolymerization initiator, and other components to obtain a desired cured product.
The polymer X in the curable composition of the present invention may be one type or two or more types.
The mixing order of each component when preparing the curable composition of the present invention is not particularly limited. After mixing the respective components, ultraviolet rays may be irradiated or heat treatment may be performed.
The components contained in the curable composition of the present invention may be mixed in advance or may be mixed immediately before curing. For example, the photopolymerization initiator may be added to the pre-mixture in which components other than the photopolymerization initiator are mixed in advance just before curing.
The curable composition of the present invention can be used without containing a solvent. The curable composition of the present invention may contain a solvent, if necessary. When the curable composition of the present invention contains a solvent, it is preferable to remove the solvent during or after curing.

The total ratio of the polymer of the present invention to the curable composition is preferably 80% by mass or more, more preferably 85% or more, still more preferably 90% or more.

[Cured product]
The cured product of the present invention is a cured product of the curable composition of the present invention.
The cured product of the present invention is obtained, for example, by molding the curable composition of the present invention into a desired shape and irradiating it with ultraviolet light to cure the composition.
Examples of the method for molding the curable composition of the present invention into a desired shape include a method of coating on a substrate, a method of extrusion molding, and a method of injecting into a mold.
The irradiation amount of ultraviolet rays when photocuring the curable composition of the present invention is preferably 0.1 to 5 J/cm ² , more preferably 0.3 to 4 J/cm ² , and even more preferably 0.5 to 3 J/cm ^2. Is more preferable. When the irradiation amount is at least the lower limit value of the above range, the cured product of the present invention has better heat resistance and creep recovery rate. When the irradiation dose is less than or equal to the upper limit of the above range, the cured product of the present invention is less likely to be colored.

The glass transition temperature of the cured product of the present invention is preferably −35° C. or lower, more preferably −37° C. or lower, further preferably −38° C. or lower, and particularly preferably −40° C. or lower. When the glass transition temperature of the cured product of the present invention is not more than the upper limit value of the above range, the cured product of the present invention is more excellent in bending durability at low temperatures. The glass transition temperature of the cured product of the present invention is preferably −80° C. or higher, more preferably −70° C. or higher, and even more preferably −60° C. or higher. For example, the glass transition temperature of the cured product is preferably −80° C. to −35° C., more preferably −70° C. to −37° C., further preferably −60° C. to −38° C., and −60° C. to −40° C. Particularly preferred. When the glass transition temperature of the cured product of the present invention is at least the lower limit value of the above range, the residual curl rate of the cured product of the present invention tends to be good. The glass transition temperature of the cured product of the present invention is the tan δ peak temperature of the dynamic viscoelasticity of the cured product of the present invention.

“E′(−20) representing the ratio of the storage elastic modulus E′ (−20° C.) (kPa) at −20° C. to the storage elastic modulus E′ (80° C.) (kPa) at 80° C. of the cured product of the present invention. [Deg.]C/E'(80[deg.]C)" is preferably 1.5 to 4, more preferably 1.6 to 3.9, and even more preferably 1.8 to 3.8. When the “E′ (−20° C.)/E′ (80° C.)” of the cured product of the present invention is within the range of 1.5 to 4, there is little change in the elastic modulus of the cured product of the present invention with temperature, Flexibility can be easily maintained, and when used for a pressure-sensitive adhesive sheet of a laminate, the bending durability and shape recovery of the laminate can be further improved.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes an adhesive layer made of the cured product of the present invention.
The cured product of the present invention can be used as an adhesive layer. The pressure-sensitive adhesive sheet of the present invention has a sheet-shaped pressure-sensitive adhesive layer made of the cured product of the present invention. In the pressure-sensitive adhesive sheet of the present invention, it is preferable to provide a release film so as to contact both surfaces of the pressure-sensitive adhesive layer. A known release film can be used as the release film.
The pressure-sensitive adhesive sheet of the present invention can be produced by, for example, a method of coating the curable composition of the present invention on the first release film and curing the composition, and then laminating the second release film thereon.
The pressure-sensitive adhesive sheet of the present invention can also be produced by a method in which the curable composition of the present invention is applied onto the first release film, the second release film is laminated thereon, and then the composition is cured.

In the pressure-sensitive adhesive sheet of the present invention, the thickness of the pressure-sensitive adhesive layer is preferably 10 to 150 μm, more preferably 20 to 120 μm, further preferably 25 to 100 μm. When the thickness of the pressure-sensitive adhesive layer is at least the lower limit value of the above range, the pressure-sensitive adhesive layer tends to be smooth, and when it is at most the upper limit value of the above range, the repeated bending durability of the pressure-sensitive adhesive sheet of the present invention is more excellent.

[Laminate]
The laminate of the present invention comprises an adhesive layer made of the cured product of the present invention and a flexible member laminated via the adhesive layer.
Examples of the flexible member include members that form a flexible display panel. The flexible member is, for example, at least one selected from the group consisting of a surface protection panel, an optical film, a touch panel, and a display panel body.
Examples of the surface protection panel include a thin cover glass and a cover film.
The optical film is a member having an optical function, and examples thereof include a polarizing film, a retardation film, an optical filter, an antireflection film, a near infrared ray cut film, and an electromagnetic wave shield film.
The touch panel has a configuration in which a touch sensor is mounted on, for example, a thin glass substrate or a plastic substrate.
Examples of the display panel body include an organic EL display panel.

The layered product of the present invention is flexible and has a property of not being damaged even if it is fixed to a curved shape in a stationary state (Bendable), and a property of recovering the shape even when bent or rolled to a bending radius of 3 mm or more (Rollable). ), and a property (Foldable) that the shape recovers even when folded to a bending radius of less than 3 mm (Foldable).

In the laminate of the present invention, the thickness of the adhesive layer is preferably 10 to 150 μm, more preferably 20 to 120 μm, further preferably 25 to 100 μm. When the thickness of the pressure-sensitive adhesive layer is at least the lower limit of the above range, the pressure-sensitive adhesive layer tends to be smooth, and when it is at most the upper limit of the above range, the repeated bending durability of the laminate of the present invention is more excellent.

[Flexible display]
The flexible display of the present invention includes the laminate of the present invention.
By containing the polymer X, the curable composition of the present invention lowers the elastic modulus of the cured product, reduces the change in elastic modulus with temperature, and lowers the glass transition temperature, as will be shown in Examples below. it can. Therefore, for example, even when it is used as an adhesive layer between members forming a flexible display, both bending durability and shape recovery can be achieved.
As the flexible display, a foldable display having a structure capable of folding the display screen is particularly suitable.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.
[Measurement method/Evaluation method]
<Measurement of molecular weight>
The mass average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were measured by gel permeation chromatography (GPC) under the following conditions.
・Analyzer: HLC-8120GPC (Product name of Tosoh Corporation)
・Column: G7000HXL+GMHXL+GMHXL (Product name of Tosoh Corporation)
・Column size: 7.8 mmφ×30 cm each, total 90 cm
・Column temperature: 40℃
・Flow rate: 0.8 mL/min
・Injection volume: 100 μL
・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI)
・Standard sample: polystyrene

<Measurement of glass transition temperature of polymer A>
The polymer A obtained in each example was analyzed by using a differential scanning calorimeter (EXSTAR 6000 DSC 6200, product name of Seiko Instruments Inc.) to obtain a sample amount of about 10 mg, a heating rate of 10° C./min, and a temperature range of −80 to −80. The glass transition temperature was measured under the condition of 25°C.

<Measurement of storage elastic modulus and glass transition temperature of cured product>
The curable composition produced in each example was poured into a silicone mold having a width of 5 mm, a length of 15 mm, and a thickness of 2 mm, and a HgXe lamp with an illuminance of 100 mW/using a conveyor type UV irradiator (manufactured by ORC) under a nitrogen environment. It was cured under the conditions of cm ² and integrated light quantity of 1 J/cm ² . The obtained cured product was used as a test sample.
For the test sample, a dynamic viscoelasticity measuring device (EXSTAR 6000 DMS 6100, product name of Seiko Instruments Inc.) was used in a tensile mode in a temperature range of −80° C. to 130° C., a heating rate of 3° C./min, The storage elastic modulus E′ (kPa) was measured under the conditions of a measurement frequency of 1 Hz and a strain of 1%. Further, the temperature at which tan δ obtained by the measurement shows the maximum value (tan δ peak temperature) was defined as the glass transition temperature.
As a measurement result, “E′ (−20° C.)/expressing storage modulus E′ at −20° C., 25° C. and 80° C., glass transition temperature, and ratio of E′ at −20° C. to E′ at 80° C. “E′ (80° C.)” is shown in the table.

<Evaluation method of bending durability and shape recovery of laminated body>
The following films were used.
Silicone-treated PET: A polyethylene terephthalate film (SP-PET-01-75BU, product name of Mitsui Chemicals Tohcello, Inc.) having a thickness of 75 μm and subjected to silicone treatment (release treatment).
Kapton film: 200 EN (thickness 50 μm; product name of DuPont Toray).
Corona-treated PET: Lumirror S10 (polyethylene terephthalate film having a thickness of 50 μm; product name of Toray Industries, Inc.) subjected to corona treatment.

(Repeated bending test)
An automatic coating machine (PI1210, product name of Tester Sangyo Co., Ltd.) in which the curable composition of each example was set on the silicone-treated surface of silicone-treated PET with a doctor blade so that the thickness of the adhesive layer after curing was 25 μm ) Was used for coating. Then, using a conveyor type UV irradiator (manufactured by ORC) under a nitrogen environment, curing was performed under the conditions of an HgXe lamp, an illuminance of 100 mW/cm ² and an integrated light amount of 1 J/cm ² to form an adhesive layer. The adhesive layer side was attached to a Kapton film. Next, after peeling off the silicone-treated PET, the corona-treated surface of the corona-treated PET was attached to the adhesive layer that appeared, to prepare a test laminate.
Using a U-shaped planar bending tester (DLDM111LH, product name of Yuasa System Equipment Co., Ltd.), the operation of bending the obtained test laminate was repeated. Specifically, the operation (180 degree opening) of bending in a U-shape so that the bending radius is 1.5 mm and the Kapton film side is inside and then releasing the bending force is one operation. Repeated 100,000 times at a rate of 60 times per minute. The appearance of the test laminate after the test was visually observed and evaluated according to the following criteria.
A: No whitening, peeling, floating or cracking occurred, and there was no change in appearance.
B: One or more of whitening, peeling, floating and cracks occurred, but it was slight and there was no problem in practical use.
C: One or more of whitening, peeling, floating and cracks remarkably occur, which is a problem in practical use.

(Static bending test)
The test laminate prepared in the same manner as the repeated bending test was used as a static bending test sample. The test laminate had a width of 50 mm, a length of 100 mm and a thickness of 0.125 mm. A sample for static bending test was adhered along the outer shape of a plate having a thickness of 3 mm whose end surface was processed into a curved surface (bending radius of 1.5 mm) so that the Kapton film side would be the inner side, and was fixed with tape. After standing for 20 days at −20° C. or room temperature (25° C.), the appearance of the test laminate after the test was visually observed and evaluated according to the same criteria as the repeated bending test.

(Curl test, curl residual rate)
The test laminate prepared in the same manner as the repeated bending test was cut into a width 10 mm and a length 50 mm to obtain a curl test sample. The curl test sample was bent at the center position in the length direction along the outer shape of a plate having a thickness of 4 mm whose end surface was processed into a curved surface (bending radius 2 mm), fixed with tape, and left at room temperature for 1 day. Then, the curl test sample was removed from the plate and placed on a horizontal surface with the bent surface facing upward, and the height h (mm) from the horizontal surface to the bent surface was measured. The curl residual rate (unit: %) was calculated by the following formula. The lower the residual curl rate, the better the shape recovery. In addition, what peeled off during the test was described as N.
Curling residual rate (%)={h/25}×100

(Creep recovery rate)
The creep test sample shown in FIG. 1A was prepared in the same procedure as the repeated bending test. In the figure, reference numeral 1 is a Kapton film, 2 is an adhesive layer, and 3 is corona-treated PET. In the shearing direction (X direction), the length of each of the Kapton film 1 and the corona-treated PET3 is 60 mm, and the length from the end portion 1a of the Kapton film 1 to the end portion 3a of the corona-treated PET3 (hereinafter referred to as the total length in the X direction). .) was 110 mm. The thickness of the adhesive layer 2 was 25 μm. The width of each of the Kapton film 1 and the corona-treated PET 3 was 10 mm in the direction perpendicular to both the X direction and the thickness direction.
As shown in FIG. 1B, the end 1a of the Kapton film 1 and the end 3a of the corona-treated PET 3 were fixed to a tensile tester, respectively, and extended in the X direction so that the total length in the X direction was 300 μm longer than the initial value. After that, the operation of releasing the stretched force was once, repeated 10 times, and then allowed to stand for 1 minute. The residual strain amount after standing was observed with an optical microscope (microscope VHX-1000, product name of KEYENCE), and the creep recovery rate (unit: %) was calculated by the following formula. The higher the creep recovery rate, the better the shape recovery.
Creep recovery rate (%)={(deviation from initial position (μm)−300 μm)/300 μm}×100

[Production Example 1-1]
To a pressure resistant reaction vessel equipped with a stirrer and a nitrogen introducing tube, 0.2 g of zinc hexacyanocobaltate-tert-butyl alcohol complex (hereinafter also referred to as “DMC-TBA catalyst”) and 30 g of n-butanol were added. In a nitrogen atmosphere at 130° C., 3970 g of propylene oxide (hereinafter also referred to as “PO”) was charged at a constant rate over 7 hours. Next, after confirming that the internal pressure in the pressure-resistant reaction vessel had stopped decreasing, the product was extracted and treated with a polyoxyalkylene monool (monool 1) having a hydroxyl value of 5.6 mgKOH/g (hydroxyl group-converted molecular weight: 10,000). 4,000 g was obtained.

[Production Example 1-2]
Polyoxyalkylene monool (monool 2) having a hydroxyl value of 4.1 mg KOH/g (hydroxyl-converted molecular weight: 13,680) was prepared in the same manner as in Production Example 1-1 except that 21 g of n-butanol and 3979 g of PO were used. Was obtained.
[Production Example 1-3]
In a pressure-resistant reaction vessel equipped with a stirrer and a nitrogen inlet tube, 0.5 g of DMC-TBA catalyst and 74 g of n-butanol were added, and a nitrogen atmosphere at 130° C. was obtained, 7941 g of PO and ethylene oxide (hereinafter referred to as EO). 1985 g) of the mixed solution was added at a constant rate for 15 hours. Next, after confirming that the internal pressure in the pressure-resistant reaction vessel had stopped decreasing, the product was extracted, and a polyoxyalkylene monool (monool 3) having a hydroxyl value of 5.2 mgKOH/g (hydroxyl-converted molecular weight: 10,790) was prepared. 10000 g was obtained. In Monool 3, the ratio of PO to the total of PO and EO was about 74 mol %.
[Production Example 1-4]
Polyoxyalkylene mono with a hydroxyl value of 11.8 mg KOH/g (hydroxyl-converted molecular weight: 4,750) was prepared in the same manner as in Production Example 1-3 except that DMC-TBA was 0.25 g, PO was 3743 g, and EO was 1182 g. 5000 g of all (monoall 4) was obtained. In Monool 4, the ratio of PO to the total of PO and EO was about 71 mol %.

[Production Example 2-1]
2-Acryloyloxyethyl isocyanate (Karenz-AOI, product name of Showa Denko KK: hereinafter also referred to as "AOI") was used as the isocyanate compound 1.
In a reaction vessel equipped with a stirrer and a nitrogen introducing tube, 964.9 g of Monool 1 (average number of hydroxyl groups: 1.08) and 13.1 g of 2-acryloyloxyethyl isocyanate were added, and 2-ethylhexanoic acid was added. In the presence of 0.08 g of a 25% toluene solution of bismuth, the mixture was stirred at 70° C. for 3 hours to obtain a monomer B1. The ratio of NCO groups of 2-acryloyloxyethyl isocyanate to the OH groups of Monool 1 (index (number of NCO groups/number of OH groups)) was 100. The ratio of the monomer B1 in the product was 84% by mass.
Table 1 shows Mn, Mw/Mn, the average number of functional groups, the proportion of urethane bonds, and the glass transition temperature of the obtained monomer B1 (the same applies hereinafter).

[Production Example 2-2]
Monomer B2 was obtained in the same manner as in Production Example 2-1, except that 928.1 g of monool 2 (average number of hydroxyl groups: 1.11) and 8.6 g of AOI were used instead of monool 1. The ratio of the monomer B2 in the product was 80% by mass.
[Production Example 2-3]
A product containing a monomer B3 was prepared in the same manner as in Production Example 2-1, except that 500.2 g of monool 3 (average number of hydroxyl groups: 1.11) and 6.6 g of AOI were used instead of monool 1. Obtained. The ratio of the monomer B3 in the product was 96% by mass.
[Production Example 2-4]
A product containing Monomer B4 was prepared in the same manner as in Production Example 2-1, except that 501.0 g of Monool 4 (average number of hydroxyl groups: 1.11) and 14.9 g of AOI were used instead of Monool 1. Obtained. The ratio of the monomer B4 in the product was 89% by mass.

[Production Example 3-1]
In a reaction vessel equipped with a stirrer and a nitrogen introducing tube, 200 g of ethyl acetate was added and maintained at 70°C. Next, 156.8 g of butyl acrylate (hereinafter, referred to as BA. Molecular weight (formula weight) is 128) and 4.0 g of acrylic acid (hereinafter, referred to as AA. Molecular weight (formula weight) is 86). , 2-ethylhexyl acrylate (hereinafter referred to as 2-EHA, molecular weight (formula weight) is 184) 39.2 g and 2,2'-azobis(2,4-dimethylvaleronitrile) (hereinafter referred to as V- 65 g) was added dropwise to the reaction vessel maintained at 70±2° C. over 2 hours at a constant rate. After completion of the dropping, the mixture was maintained at 70±2° C. for 2 hours, and then degassed under reduced pressure at 130° C. for 2 hours to remove ethyl acetate and unreacted monomers to obtain a polymer 1.
The Mw, Mn, Mw/Mn, and glass transition temperature of the obtained polymer 1 are shown in Table 2 (the same applies hereinafter).

[Production Example 3-2]
In a reaction vessel equipped with a stirrer and a nitrogen introducing tube, 100 g of ethyl acetate was added and maintained at 70°C. Then, a mixed solution of 196 g of 2-EHA, 4.0 g of AA and 0.2 g of V-65 was added dropwise at a constant rate over 2 hours into a reaction container maintained at 70±2°C. After the completion of dropping, the mixture was maintained at 70±2° C. for 2 hours, and then degassed under reduced pressure at 130° C. for 2 hours to remove ethyl acetate and unreacted monomers, to obtain a polymer 2.

[Production Example 3-3]
Polymer 3 was obtained in the same manner as in Production Example 3-1, except that 39.2 g of Monomer B1 obtained in Production Example 2-1 was used instead of 2-EHA.

[Production Example 3-4]
Polymer 4 was obtained in the same manner as in Production Example 3-3, except that the amount of BA used was 116.8 g and the amount of monomer B1 used was 78.4 g.

[Production Example 3-5]
In a reaction vessel equipped with a stirrer and a nitrogen introducing tube, 500 g of ethyl acetate was added and maintained at 70°C. Then, a mixed solution of 78.0 g of BA, 4.0 g of AA, 78.0 g of 2-EHA, 39.2 g of the monomer B1 obtained in Production Example 2-1 and 0.2 g of V-65 was added to 70± It dripped at a constant rate over 2 hours in the reaction container maintained at 2 degreeC. After the dropping was completed, the mixture was maintained at 70±2° C. for 2 hours, and then degassed under reduced pressure at 130° C. for 2 hours to remove ethyl acetate and unreacted monomers to obtain a polymer 5.

[Production Example 3-6]
Polymer 6 was obtained in the same manner as in Production Example 3-1, except that 39.2 g of Monomer B2 obtained in Production Example 2-2 was used instead of 2-EHA.
[Production Example 3-7]
In a reaction vessel equipped with a stirrer and a nitrogen introducing tube, 400 g of ethyl acetate was added and the temperature was maintained at 70°C. Next, 52.8 g of BA, 92.0 g of 2-EHA, and 16.0 g of 4-hydroxybutyl acrylate (hereinafter, also referred to as "4-HBA". The molecular weight (formula weight) is 144.). A mixed solution of 39.2 g of the monomer B3 obtained in -3 and 0.2 g of V-65 was dropped into the reaction vessel kept at 70±2° C. over 2 hours at a constant rate. After the completion of dropping, the mixture was maintained at 70±2° C. for 2 hours, and then degassed under reduced pressure at 130° C. for 2 hours to remove ethyl acetate and unreacted monomers, to obtain a polymer 7.

[Examples 1 to 7]
Examples 1 and 2 are comparative examples, and Examples 3 to 7 are examples.
With the composition (unit: parts by mass) shown in Table 3, all components were mixed using a planetary stirrer (manufactured by EMC) to produce a curable composition. In the table, the crosslinking agent 1 is 1,9-nonanediol diacrylate, and the photopolymerization initiator 1 is 4-methylbenzophenone.
The items shown in the table were measured or evaluated by the above-mentioned measurement method and evaluation method. The results are shown in Table 3.

As shown in the results of Table 3, the curable compositions of Examples 3 to 6 containing the polymers containing the units based on the monomer A and the units based on the monomer B have low glass transition temperatures of the cured products, It has a low elastic modulus and is excellent in both bending durability and shape recovery of the laminate. Further, the curable composition of Example 7, which also contains a polymer containing units based on the monomer A and units based on the monomer B, has a low glass transition temperature of the cured product, and has excellent bending durability and shape of the laminate. Excellent in both recoverability.

The present application claims priority based on Japanese Patent Application No. 2019-018958 filed in Japan on February 5, 2019, and the content thereof is incorporated herein.

1 Kapton film 2 Adhesive layer 3 Corona treated PET
4 Deviation from the initial value

Claims

A polymer containing a unit based on a first monomer and a unit based on a second monomer, wherein the ratio of the unit based on the second monomer to all structural units is 0.1 to 50% by mass. And
The first monomer is a (meth)acrylic acid ester having a molecular weight of 1,000 or less,
The second monomer has a molecular weight of 5,000 to 25,000, and has one or more polyoxyalkylene chains and one (meth)acryloyloxy group in one molecule, (meth) A polymer that is an acrylic ester.
The polymer according to claim 1, wherein the molecular weight of the second monomer is a number average molecular weight.
The polymer according to claim 1 or 2, wherein the glass transition temperature of the polymer is -80 to -40°C.
The polymer according to any one of claims 1 to 3, wherein the number average molecular weight of the polymer is 25,000 to 1,000,000.
A curable composition comprising the polymer according to any one of claims 1 to 4.
The curable composition according to claim 5, further comprising a crosslinking agent.
The curable composition according to claim 5 or 6, further comprising a photopolymerization initiator.
The curable composition according to any one of claims 5 to 7, wherein a ratio of the total amount of the polymer to the total amount of the curable composition is 80% by mass or more.
A cured product of the curable composition according to any one of claims 5 to 8.
E′(−20° C.)/E′(80° C.), which represents the ratio of the storage elastic modulus E′ (−20° C.) (kPa) at −20° C. to the storage elastic modulus E′ (80° C.) (kPa) at 80° C. The cured product according to claim 9, wherein) is 1.5 to 4.
An adhesive sheet comprising an adhesive layer made of the cured product according to claim 9 or 10.
The pressure-sensitive adhesive sheet according to claim 11, wherein the thickness of the pressure-sensitive adhesive layer is 10 to 150 μm.
A laminate having an adhesive layer made of the cured product according to claim 9 or 10, and a flexible member laminated via the adhesive layer.
The laminate according to claim 13, wherein the adhesive layer has a thickness of 10 to 150 μm.
The laminate according to claim 13 or 14, wherein the flexible member is at least one selected from the group consisting of a surface protection panel, an optical film, a touch panel, and a display panel body.
A flexible display comprising the laminate according to any one of claims 13 to 14.