Resin composition, substrate for flexible devices, flexible device, and sheet

Abstract

This resin composition contains a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a radical photopolymerization initiator. The urethane (meth)acrylate is a reaction product of: a polyol component that contains a specific polypropylene glycol; a polyisocyanate component that contains at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate; and a hydroxyl group-containing (meth)acrylate. In the dynamic viscoelasticity measurement of a cured product of the resin composition, there are two or more specific peaks of the loss factor tanδ.

Description

Resin composition, substrate for flexible device, flexible device and sheet

[0001] The present invention relates to a resin composition, a substrate for flexible devices, a flexible device, and a sheet, and more particularly to a resin composition, a substrate for flexible devices containing a cured product of the resin composition, a flexible device including the substrate for flexible devices, and a sheet.

[0002] BACKGROUND ART Flexible substrates have conventionally been used in the manufacture of devices that require flexibility (for example, wearable devices, flexible sensors, flexible solar cells, flexible displays, etc.).

[0003] The flexible substrate is made of a cured product of a resin composition. As such a resin composition, an active energy ray-curable composition containing a monofunctional (meth)acrylate, a (meth)acrylate having a urethane bond, and a photoradical polymerization initiator has been proposed (see, for example, Patent Document 1). In Patent Document 1, the (meth)acrylate having a urethane bond is produced using polypropylene glycol (number average molecular weight 1000), dicyclohexylmethane-4,4'-diisocyanate, and 2-hydroxyethyl acrylate (see Production Example 1 in Patent Document 1).

[0004] JP 2019-172785 A

[0005] On the other hand, flexible substrates are required to have flexibility and elongation properties depending on the application and purpose.

[0006] Furthermore, flexible substrates are required to have strength against deformation.

[0007] The present invention provides a resin composition having excellent flexibility, elongation performance, and strength, a substrate for flexible devices including a cured product of the resin composition, and a flexible device and a sheet including the substrate for flexible devices.

[0008] The present invention [1] is a resin composition comprising a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator, wherein the urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate, the polyol component comprises polypropylene glycol, and the polypropylene glycol has a number average molecular weight of 2000 or more, the polyisocyanate component comprises at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and wherein, in dynamic viscoelasticity measurement of a cured product of the resin composition, there are two or more peaks of loss factor tan δ, the peaks including a first peak having a peak top position below −20°C and a second peak having a peak top position at 60°C or higher.

[0009] The present invention [2] includes the resin composition according to the above [1], in which the number average molecular weight of the polypropylene glycol is 3,000 or more.

[0010] The present invention [3] includes the resin composition according to the above [1] or [2], in which the monofunctional (meth)acrylate has an alicyclic structure.

[0011] The present invention [4] includes the resin composition according to any one of the above [1] to [3], wherein the content ratio of the monofunctional (meth)acrylate is 60 parts by mass to 320 parts by mass per 100 parts by mass of the urethane (meth)acrylate.

[0012] The present invention [5] includes the resin composition according to any one of the above [1] to [4], wherein the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 70°C or higher and 300°C or lower.

[0013] The present invention [6] further includes the resin composition according to any one of the above [1] to [5], which contains a bifunctional (meth)acrylate.

[0014] The present invention [7] includes the resin composition according to the above [6], in which the content ratio of the bifunctional (meth)acrylate is 3 parts by mass to 30 parts by mass per 100 parts by mass of the urethane (meth)acrylate.

[0015] The present invention [8] includes the resin composition according to any one of the above [1] to [7], wherein the difference between the peak top position of the first peak and the peak top position of the second peak (peak top position of the second peak - peak top position of the first peak) is 80°C or more and 300°C or less.

[0016] The present invention [9] includes the resin composition according to any one of the above [1] to [8], wherein the double bond equivalent of the urethane (meth)acrylate is 1000 g / eq. or more.

[0017] The present invention

[10] includes a substrate for flexible devices, which includes a cured product of the resin composition according to any one of the above [1] to [9].

[0018] The present invention

[11] includes a flexible device comprising the substrate for flexible devices according to the above

[10] .

[0019] The present invention

[12] is a sheet comprising a cured product of a resin composition comprising a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator, wherein the urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate, the polyol component comprises polypropylene glycol, and the polypropylene glycol has a number average molecular weight of 2000 or more, the polyisocyanate component comprises at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and wherein, in dynamic viscoelasticity measurement of the cured product of the resin composition, there are two or more peaks of loss factor tan δ, the peaks including a first peak having a peak top position below −20°C and a second peak having a peak top position at 60°C or higher.

[0020] The present invention

[13] is a sheet comprising a cured product of a resin composition comprising a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator, wherein the urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate, the polyol component comprises polypropylene glycol, and the polypropylene glycol has a number average molecular weight of 2000 or more, the polyisocyanate component comprises at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and the sheet has a phase-separated structure in which a layer predominantly composed of the urethane (meth)acrylate and a layer predominantly composed of the monofunctional (meth)acrylate are separate phases.

[0021] The present invention

[14] includes the sheet according to the above

[12] or

[13] , wherein the number average molecular weight of the polypropylene glycol is 3,000 or more.

[0022] The present invention

[15] includes the sheet according to any one of the above

[12] to

[14] , wherein the monofunctional (meth)acrylate has an alicyclic structure.

[0023] The present invention

[16] includes the sheet according to any one of the above

[12] to

[15] , wherein the content ratio of the monofunctional (meth)acrylate is 60 parts by mass to 320 parts by mass per 100 parts by mass of the urethane (meth)acrylate.

[0024] The present invention

[17] includes the sheet according to any one of the above

[12] to

[16] , wherein the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 70°C or higher and 300°C or lower.

[0025] The present invention

[18] includes the sheet according to any one of the above

[12] to

[17] , which further contains a bifunctional (meth)acrylate.

[0026] The present invention

[19] includes the sheet according to the above

[18] , wherein the content ratio of the bifunctional (meth)acrylate is 3 to 30 parts by mass relative to 100 parts by mass of the urethane (meth)acrylate.

[0027] The present invention

[20] includes the sheet according to any one of the above

[12] to

[19] , wherein the difference between the peak top position of the first peak and the peak top position of the second peak (peak top position of the second peak - peak top position of the first peak) is 80°C or more and 300°C or less.

[0028] The present invention

[21] includes the sheet according to any one of the above

[12] to

[20] , wherein the double bond equivalent of the urethane (meth)acrylate is 1000 g / eq. or more.

[0029] In dynamic viscoelasticity measurement of a cured product of the resin composition of the present invention, there are two or more peaks of loss factor tan δ, including a first peak having a peak top position below −20° C. and a second peak having a peak top position above 60° C. In a cured product of such a resin composition, the urethane (meth)acrylate and the monofunctional (meth)acrylate undergo phase separation. As a result, the cured product of the resin composition possesses both the performance derived from the urethane (meth)acrylate and the performance derived from the monofunctional (meth)acrylate.

[0030] The urethane (meth)acrylate is a reaction product of a polyol component containing polypropylene glycol having a number average molecular weight of 2000 or more, a polyisocyanate component containing at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and a hydroxyl group-containing (meth)acrylate. Such a urethane (meth)acrylate can improve flexibility and elongation performance. Specifically, the flexibility and elongation performance can be improved even at low temperatures (-20°C).

[0031] The resin composition also contains a monofunctional (meth)acrylate, which can improve strength against deformation.

[0032] As described above, the cured product of the resin composition has both the properties derived from the urethane (meth)acrylate and the properties derived from the monofunctional (meth)acrylate, and therefore has excellent flexibility, elongation, and strength against deformation.

[0033] The substrate for flexible devices of the present invention contains a cured product of the resin composition of the present invention, and therefore has excellent flexibility, elongation performance, and strength.

[0034] The flexible device of the present invention includes the flexible device of the present invention, and therefore has excellent flexibility, elongation performance, and strength.

[0035] The sheet of the present invention has two or more peaks of loss factor tan δ, including a first peak having a peak top position below −20° C. and a second peak having a peak top position above 60° C. In a cured product of such a resin composition, the urethane (meth)acrylate and the monofunctional (meth)acrylate undergo phase separation. This allows the sheet to possess both the performance derived from the urethane (meth)acrylate and the performance derived from the monofunctional (meth)acrylate. Therefore, the sheet has excellent flexibility, elongation, and strength against deformation.

[0036] The sheet of the present invention has a phase-separated structure in which a layer mainly made of urethane (meth)acrylate and a layer mainly made of monofunctional (meth)acrylate are separate phases. This allows the sheet to have both the properties derived from the urethane (meth)acrylate and the properties derived from the monofunctional (meth)acrylate. Therefore, the sheet has excellent flexibility, elongation, and strength against deformation.

[0037] 1. Resin Composition The resin composition contains a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator.

[0038] <Urethane (meth)acrylate> The urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate. The (meth)acrylate is a methacrylate and / or an acrylate.

[0039] (Polyol Component) The polyol component contains polypropylene glycol. When the polyol component contains polypropylene glycol, the elongation performance is improved.

[0040] The number average molecular weight (Mn) of the polypropylene glycol is 2,000 or more, preferably 3,000 or more, more preferably 4,000 or more, even more preferably 5,000 or more, particularly preferably 8,000 or more, most preferably 9,000 or more, or even 10,000 or more, and for example, 50,000 or less, preferably 3,000 or less, more preferably 15,000 or less.

[0041] When the number average molecular weight (Mn) of the polypropylene glycol is equal to or greater than the lower limit, the elongation performance (particularly the elongation performance at low temperatures) is improved.

[0042] On the other hand, if the number average molecular weight (Mn) of the polypropylene glycol is less than the lower limit, the elongation performance will decrease.

[0043] The number average molecular weight is a molecular weight measured by gel permeation chromatography (GPC) and converted into standard polystyrene (the same applies hereinafter).

[0044] The content of polypropylene glycol relative to the polyol component is, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0045] The polyol component may include other polyols besides polypropylene glycol.

[0046] The other polyols include, for example, low molecular weight polyols and high molecular weight polyols.

[0047] The low molecular weight polyol is a compound having two or more hydroxyl groups and a number average molecular weight of 40 or more and less than 400, preferably 300 or less.

[0048] Low molecular weight polyols include, for example, dihydric alcohols and trihydric alcohols.

[0049] Examples of dihydric alcohols include aliphatic diols, alicyclic diols, and aromatic diols.

[0050] Examples of aliphatic diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol.

[0051] Examples of alicyclic diols include cyclohexanediol and hydrogenated bisphenol A.

[0052] Examples of aromatic diols include bisphenol A and 1,4-bis(2-hydroxyethoxy)benzene.

[0053] Examples of trihydric alcohols include glycerin, trimethylolpropane, and triisopropanolamine.

[0054] The low molecular weight polyols can be used alone or in combination of two or more kinds.

[0055] The content of the low-molecular-weight polyol relative to the polyol component is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass. That is, particularly preferably, the polyol component does not contain a low-molecular-weight polyol.

[0056] The high molecular weight polyol is a compound having two or more hydroxyl groups and a number average molecular weight of 400 or more, preferably 500 or more and 10,000 or less.

[0057] Examples of high molecular weight polyols include polyether polyols (e.g., polyoxyalkylene polyols (excluding polypropylene glycol), polytetramethylene ether polyols), polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols.

[0058] The high molecular weight polyols can be used alone or in combination of two or more kinds.

[0059] The content of the high-molecular-weight polyol relative to the polyol component is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass. That is, particularly preferably, the polyol component does not contain a high-molecular-weight polyol.

[0060] The polyol component preferably consists of polypropylene glycol without any other polyols.

[0061] (Polyisocyanate Component) The polyisocyanate component includes at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate. When the polyisocyanate component includes at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, flexibility can be improved.

[0062] Examples of alicyclic polyisocyanates include alicyclic diisocyanates, such as 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 4,4'-, 2,4'-, or 2,2'-methylenebis(cyclohexyl isocyanate), or mixtures thereof (H １２ MDI), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof (H ６ bis(isocyanatomethyl)norbornane (NBDI), 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, and methyl-2,6-cyclohexane diisocyanate.

[0063] As the alicyclic polyisocyanate, IPDI, H １２ MDI, 1,3- or 1,4-H ６ As the alicyclic polyisocyanate, from the viewpoint of further improving flexibility at low temperatures, 1,3- or 1,4-H ６ XDI is an example.

[0064] As the alicyclic polyisocyanate, from the viewpoint of further improving flexibility at low temperatures, 1,3-H ６ XDI. ６ XDI has a linear molecular structure, whereas 1,3-H ６ XDI has a flexible molecular structure, which can further improve flexibility at low temperatures.

[0065] The alicyclic polyisocyanate includes derivatives of the above-mentioned alicyclic polyisocyanates.

[0066] Examples of the derivatives of alicyclic polyisocyanates include the above-mentioned alicyclic polyisocyanate polymers, allophanate derivatives, polyol derivatives, biuret derivatives, urea derivatives, oxadiazinetrione derivatives, carbodiimide derivatives, uretdione derivatives, and uretonimine derivatives.

[0067] The alicyclic polyisocyanates can be used alone or in combination of two or more kinds.

[0068] The content of the alicyclic polyisocyanate relative to the polyisocyanate component is, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0069] Examples of aliphatic polyisocyanates include aliphatic diisocyanates, such as 1,6-hexamethylene diisocyanate (1,6-HDI), 1,5-pentamethylene diisocyanate (1,5-PDI), tetramethylene diisocyanate, trimethylene diisocyanate, 1,2-, 2,3-, or 1,3-butylene diisocyanate, and 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate.

[0070] Aliphatic polyisocyanates include derivatives of the above-mentioned aliphatic polyisocyanates.

[0071] The derivatives of the aliphatic polyisocyanate are the same as those listed as the derivatives of the alicyclic polyisocyanate.

[0072] As the aliphatic polyisocyanate, from the viewpoint of further improving flexibility at low temperatures, 1,6-hexamethylene diisocyanate is preferable.

[0073] The aliphatic polyisocyanates can be used alone or in combination of two or more kinds.

[0074] The content of the aliphatic polyisocyanate relative to the polyisocyanate component is, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0075] The polyisocyanate component may include polyisocyanates other than alicyclic polyisocyanates and aliphatic polyisocyanates.

[0076] Other polyisocyanates include, for example, aromatic polyisocyanates and araliphatic polyisocyanates.

[0077] Examples of aromatic polyisocyanates include aromatic diisocyanates, such as 4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or a mixture thereof (MDI), 2,4- or 2,6-tolylene diisocyanate or a mixture thereof (TDI), o-tolidine diisocyanate, 1,5-naphthalene diisocyanate (NDI), m- or p-phenylene diisocyanate or a mixture thereof, 4,4'-diphenyl diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0078] Examples of araliphatic polyisocyanates include araliphatic diisocyanates, such as xylylene diisocyanate (1,2-, 1,3-, or 1,4-xylylene diisocyanate or a mixture thereof) (XDI), 1,3- or 1,4-tetramethylxylylene diisocyanate or a mixture thereof (TMXDI), and ω,ω'-diisocyanato-1,4-diethylbenzene.

[0079] Other polyisocyanates include derivatives of the other polyisocyanates mentioned above.

[0080] The derivatives of other polyisocyanates are the same as those listed as the derivatives of alicyclic polyisocyanates.

[0081] The other polyisocyanates may be used alone or in combination of two or more kinds.

[0082] The content of the other polyisocyanate relative to the polyisocyanate component is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass. That is, particularly preferably, the polyisocyanate component does not contain other polyisocyanates and is composed of at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate. More preferably, the polyisocyanate component is composed of an alicyclic polyisocyanate or an aliphatic polyisocyanate. Most preferably, the polyisocyanate component is composed of an alicyclic polyisocyanate.

[0083] (Hydroxyl Group-Containing (Meth)acrylate) Examples of the hydroxyl group-containing (meth)acrylate include hydroxyl group-containing mono(meth)acrylate, hydroxyl group-containing di(meth)acrylate, and hydroxyl group-containing tri(meth)acrylate.

[0084] Examples of hydroxyl group-containing mono(meth)acrylates include hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 3-chloro-2-hydroxypropyl(meth)acrylate, butanediol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, 2-(6-hydrohexanoyloxy)ethyl acrylate, glycerin mono(meth)acrylate, trimethylolpropane mono(meth)acrylate, and pentaerythritol mono(meth)acrylate.

[0085] Examples of hydroxyl group-containing di(meth)acrylates include glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, and pentaerythritol di(meth)acrylate.

[0086] An example of the hydroxyl group-containing tri(meth)acrylate is pentaerythritol tri(meth)acrylate.

[0087] The hydroxyl group-containing (meth)acrylate is preferably a hydroxyl group-containing mono(meth)acrylate. The hydroxyl group-containing (meth)acrylate is more preferably hydroxyethyl (meth)acrylate. The hydroxyl group-containing (meth)acrylate is even more preferably hydroxyethyl acrylate.

[0088] The hydroxyl group-containing (meth)acrylates can be used alone or in combination of two or more kinds.

[0089] (Method for Producing Urethane (Meth)acrylate) In the method for producing urethane (meth)acrylate, first, a polyol component and a polyisocyanate component are reacted to prepare an isocyanate group-terminated prepolymer.

[0090] As a method for reacting the polyisocyanate component with the polyol component, a known polymerization method (for example, bulk polymerization or solution polymerization) is selected, and bulk polymerization is preferably selected.

[0091] In bulk polymerization, for example, a polyisocyanate component and a polyol component are mixed and reacted in a nitrogen atmosphere.

[0092] In this reaction, the equivalent ratio of isocyanate groups in the polyisocyanate component to active hydrogen groups (hydroxyl groups) in the polyol component (isocyanate groups / active hydrogen groups) exceeds 1, and is, for example, 1.2 or more, preferably 1.3 or more, and for example, 10.0 or less, preferably 9 or less, more preferably 5 or less, and even more preferably 3 or less. In such a case, the terminal functional group of the resulting reaction product is an isocyanate group. In other words, an isocyanate-terminated prepolymer is obtained.

[0093] As for reaction conditions, the reaction temperature is, for example, 20° C. to 110° C., preferably 60° C. to 90° C. The reaction time is 1 hour to 20 hours, preferably 2 hours to 10 hours.

[0094] In the above reaction, if necessary, a reaction catalyst (for example, an amine-based, tin-based, or lead-based catalyst) can be added.

[0095] In the above reaction, unreacted polyisocyanate components and / or unreacted polyol components can be removed by known methods such as distillation or extraction.

[0096] This produces an isocyanate-terminated prepolymer, which is a reaction product of the polyisocyanate component and the polyol component.

[0097] Next, the isocyanate group-terminated prepolymer is reacted with a hydroxyl group-containing (meth)acrylate.

[0098] In this reaction, the equivalent ratio (isocyanate group / active hydrogen group) of the isocyanate group in the isocyanate group-terminated prepolymer to the active hydrogen group (hydroxyl group) in the hydroxyl group-containing (meth)acrylate is, for example, 0.8 to 1.2, preferably 0.9 to 1.1, and more preferably 1.0.

[0099] As for reaction conditions, the reaction temperature is, for example, 20° C. to 110° C., preferably 60° C. to 90° C. The reaction time is 1 hour to 20 hours, preferably 2 hours to 10 hours.

[0100] In the above reaction, if necessary, a reaction catalyst (for example, an amine-based, tin-based, or lead-based catalyst) can be added.

[0101] This gives a urethane (meth)acrylate, which is a reaction product of the isocyanate-terminated prepolymer and the hydroxyl-containing (meth)acrylate.

[0102] The double bond equivalent of the urethane (meth)acrylate is, for example, 1000 g / eq. or more, preferably 2000 g / eq. or more, more preferably 3000 g / eq. or more, even more preferably 4000 g / eq. or more, particularly preferably 5000 g / eq. or more, and for example, 20000 g / eq. or less, preferably 15000 g / eq. or less, more preferably 10000 g / eq. or less, even more preferably 7000 g / eq. or less, particularly preferably 6000 g / eq. or less.

[0103] When the double bond equivalent of the urethane (meth)acrylate is equal to or greater than the lower limit, flexibility can be improved.

[0104] Furthermore, when the double bond equivalent of the urethane (meth)acrylate is equal to or less than the upper limit, the elongation at break can be improved.

[0105] The double bond equivalent weight of the urethane (meth)acrylate can be adjusted by adjusting the formulation of the polyisocyanate component and the polyol component (for example, the number average molecular weight of the polypropylene glycol).

[0106] The double bond equivalent of the urethane (meth)acrylate can be calculated from the charged amount.

[0107] <Monofunctional (meth)acrylate> The monofunctional (meth)acrylate has one (meth)acryloyl group.

[0108] Examples of the monofunctional (meth)acrylate include a ring-structure-containing monofunctional (meth)acrylate and a ring-free monofunctional (meth)acrylate.

[0109] Examples of the ring structure-containing monofunctional (meth)acrylate include alicyclic structure-containing monofunctional (meth)acrylate, aliphatic heterocycle-containing monofunctional (meth)acrylate, and aromatic ring structure-containing monofunctional (meth)acrylate.

[0110] Examples of the alicyclic structure-containing monofunctional (meth)acrylate include cyclohexyl (meth)acrylate and isobornyl (meth)acrylate. Preferred examples of the alicyclic structure-containing monofunctional (meth)acrylate include isobornyl (meth)acrylate. More preferred examples of the alicyclic structure-containing monofunctional (meth)acrylate include isobornyl methacrylate.

[0111] Examples of the aliphatic heterocycle-containing monofunctional (meth)acrylate include (meth)acryloylmorpholine.

[0112] Examples of aromatic ring structure-containing monofunctional (meth)acrylates include phenyl (meth)acrylate and benzyl (meth)acrylate.

[0113] Examples of the monofunctional (meth)acrylate not containing a ring structure include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate. Methyl (meth)acrylate is preferred as the monofunctional (meth)acrylate not containing a ring structure. Methyl methacrylate is more preferred as the monofunctional (meth)acrylate not containing a ring structure.

[0114] As the monofunctional (meth)acrylate, from the viewpoints of flexibility and elongation performance, preferably, a ring structure-containing monofunctional (meth)acrylate is used. As the monofunctional (meth)acrylate, from the viewpoints of flexibility and elongation performance, more preferably, an alicyclic structure-containing monofunctional (meth)acrylate is used. In other words, more preferably, the monofunctional (meth)acrylate has an alicyclic structure.

[0115] Moreover, from the viewpoint of flexibility and elongation performance, the monofunctional (meth)acrylate preferably does not contain an aliphatic heterocycle-containing monofunctional (meth)acrylate.

[0116] The glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is, for example, 70° C. or higher. The glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is preferably 70° C. or higher and lower than 150° C. from the viewpoint of strength against deformation, and 150° C. or higher and 300° C. or lower from the viewpoint of recovery rate.

[0117] From the viewpoint of achieving both strength and recovery rate against deformation, the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is preferably 80 to 300°C, more preferably 90 to 260°C, and even more preferably 150 to 220°C.

[0118] Specifically, the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is, for example, 70°C or higher, preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 150°C or higher, and for example, 300°C or lower, preferably 260°C or lower, and more preferably 220°C or lower.

[0119] When the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is equal to or higher than the lower limit, the strength against deformation can be improved.

[0120] The content of the monofunctional (meth)acrylate is, for example, 60 to 320 parts by mass with respect to 100 parts by mass of the urethane (meth)acrylate.

[0121] Specifically, when the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 70°C or higher and lower than 150°C, the content of the monofunctional (meth)acrylate relative to 100 parts by mass of the urethane (meth)acrylate is, for example, 60 parts by mass to 320 parts by mass, preferably 125 parts by mass to 270 parts by mass, more preferably 130 parts by mass to 220 parts by mass, and even more preferably 140 parts by mass to 200 parts by mass.

[0122] More specifically, when the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 70°C or higher and lower than 150°C, the content of the monofunctional (meth)acrylate is, relative to 100 parts by mass of the urethane (meth)acrylate, for example, 60 parts by mass or higher, preferably 125 parts by mass or higher, more preferably 130 parts by mass or higher, even more preferably 140 parts by mass or higher, and for example, 320 parts by mass or lower, preferably 270 parts by mass or lower, more preferably 220 parts by mass or lower, even more preferably 200 parts by mass or lower.

[0123] On the other hand, when the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 150°C or higher and 300°C or lower, the amount is, for example, 60 parts by mass to 320 parts by mass, preferably 62 parts by mass to 250 parts by mass, more preferably 65 parts by mass to 200 parts by mass, and even more preferably 70 parts by mass to 150 parts by mass.

[0124] Specifically, when the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 150°C or higher and 300°C or lower, the amount is, for example, 60 parts by mass or higher, preferably 62 parts by mass or higher, more preferably 65 parts by mass or higher, even more preferably 70 parts by mass or higher, and for example, 320 parts by mass or lower, preferably 250 parts by mass or lower, more preferably 200 parts by mass or lower, even more preferably 150 parts by mass or lower.

[0125] When the content of the monofunctional (meth)acrylate is equal to or greater than the above lower limit, the elongation performance can be improved.

[0126] Furthermore, if the content of the monofunctional (meth)acrylate is equal to or less than the upper limit, the recovery rate can be improved.

[0127] The monofunctional (meth)acrylates can be used alone or in combination of two or more kinds.

[0128] <Photoradical Polymerization Initiator> Examples of the photoradical polymerization initiator include alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin compounds, acetophenone compounds, benzophenone compounds, thioxanthone compounds, α-acyloxime ester compounds, phenyl glyoxylate compounds, benzyl compounds, azo compounds, diphenyl sulfide compounds, organic dye compounds, iron-phthalocyanine compounds, benzoin ether compounds, and anthraquinone compounds. Acetophenone compounds are preferred as the photoradical polymerization initiator.

[0129] Commercially available photopolymerization initiators may also be used, such as Omnirad 127 (an acetophenone-based compound), Omnirad 184, Omnirad 1173, Omnirad 500, Omnirad 819, and Omnirad TPO (all manufactured by IGM resins B.V.).

[0130] The photoradical polymerization initiators can be used alone or in combination of two or more kinds.

[0131] The content ratio of the photoradical polymerization initiator is, for example, 0.1 to 5 parts by mass, preferably 1 to 3 parts by mass, relative to 100 parts by mass of the total amount of the urethane (meth)acrylate, the monofunctional (meth)acrylate, and the bifunctional (meth)acrylate (described later) that is blended as needed.

[0132] <Bifunctional (meth)acrylate> The resin composition may also contain a bifunctional (meth)acrylate. When the resin composition contains a bifunctional (meth)acrylate, the restoring force can be improved.

[0133] The difunctional (meth)acrylate has two (meth)acryloyl groups.

[0134] Examples of bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, trimethylolethane di(meth)acrylate, trimethylolpropane di(meth)acrylate, glycerol di(meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol di(meth)acrylate, and dimethyloltricyclodecane di(meth)acrylate.

[0135] As the bifunctional (meth)acrylate, preferably, dimethyloltricyclodecane di(meth)acrylate is used, and more preferably, dimethyloltricyclodecane dimethacrylate is used.

[0136] The bifunctional (meth)acrylates can be used alone or in combination of two or more kinds.

[0137] The content ratio of the bifunctional (meth)acrylate relative to 100 parts by mass of the urethane (meth)acrylate is, for example, 0.5 parts by mass to 40 parts by mass, preferably 3 parts by mass to 30 parts by mass, more preferably 5 parts by mass to 28 parts by mass, even more preferably 10 parts by mass to 25 parts by mass, particularly preferably 16 parts by mass to 24 parts by mass, and most preferably 21 parts by mass to 23 parts by mass.

[0138] Specifically, the content of the bifunctional (meth)acrylate is, relative to 100 parts by mass of the urethane (meth)acrylate, for example, 0.5 parts by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, particularly preferably 16 parts by mass or more, and most preferably 21 parts by mass or more, and for example, 40 parts by mass or less, preferably 30 parts by mass or less, more preferably 28 parts by mass or less, even more preferably 25 parts by mass or less, particularly preferably 24 parts by mass or less, and most preferably 23 parts by mass or less.

[0139] When the content of the bifunctional (meth)acrylate is equal to or greater than the above lower limit, the restoring force can be improved.

[0140] Furthermore, when the content of the bifunctional (meth)acrylate is equal to or less than the upper limit, flexibility can be improved.

[0141] <Additives> The resin composition may contain additives as needed.

[0142] Examples of additives include antioxidants, sensitizers, fillers, antistatic agents, coupling agents, stabilizers, and surfactants.

[0143] <Method for producing resin composition> The resin composition can be produced by mixing a urethane (meth)acrylate, a monofunctional (meth)acrylate, a photoradical polymerization initiator, a bifunctional (meth)acrylate that is blended as needed, and an additive that is blended as needed, and stirring the mixture as needed.

[0144] Stirring can be carried out using, for example, a known stirring device (e.g., a propeller mixer, a planetary mixer, a hybrid mixer, a kneader, an emulsifying homogenizer, a three-roll mill, a bead mill, or an ultrasonic homogenizer). If necessary, stirring can be carried out while heating or cooling.

[0145] In this way, a resin composition is produced.

[0146] The resin composition can also be diluted with a known solvent.

[0147] <Cured Product of Resin Composition> The cured product of the resin composition is obtained by curing the resin composition.

[0148] To cure the resin composition, the resin composition is irradiated with active energy rays (preferably ultraviolet rays). The irradiation conditions for the active energy rays include an illuminance of, for example, 50 mW / cm ２ ~5000mw / cm ２ The irradiation time is, for example, 0.5 seconds to 5000 seconds.

[0149] In this way, a cured product of the resin composition is produced.

[0150] In addition, in a dynamic viscoelasticity measurement of a cured product of the resin composition, the loss factor tan δ has two or more peaks.

[0151] Specifically, the peaks include a first peak and a second peak.

[0152] The peak top position of the first peak is below -20°C, preferably -30°C or lower, more preferably -40°C or lower, and for example, -70°C or higher, preferably -60°C or higher.

[0153] The peak top position of the second peak is 60°C or higher, preferably 70°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, particularly preferably 130°C or higher, and, for example, 220°C or lower, more preferably 200°C or lower, even more preferably 190°C or lower, particularly preferably 180°C or lower.

[0154] The difference between the peak top position of the first peak and the peak top position of the second peak (peak top position of the second peak - peak top position of the first peak) is, for example, 80°C to 300°C, preferably 100°C to 250°C, more preferably 130°C to 250°C, even more preferably 140°C to 250°C, and particularly preferably 180°C to 250°C.

[0155] Specifically, the difference between the peak top position of the first peak and the peak top position of the second peak (peak top position of the second peak - peak top position of the first peak) is, from the viewpoints of low-temperature properties and recovery rate, for example, 80°C or higher, preferably 100°C or higher, more preferably 130°C or higher, even more preferably 140°C or higher, and particularly preferably 180°C or higher, and from the viewpoints of low-temperature properties and recovery rate, for example, 300°C or lower, preferably 250°C or lower.

[0156] If the cured product of the resin composition has the above-mentioned peaks (first peak and second peak), the urethane (meth)acrylate and the monofunctional (meth)acrylate are phase-separated in the cured product of the resin composition. Specifically, the first peak is a peak derived from the urethane (meth)acrylate, and the second peak is a peak derived from the monofunctional (meth)acrylate.

[0157] Furthermore, the cured product of the resin composition has a phase-separated structure in which a layer mainly made of urethane (meth)acrylate and a layer mainly made of monofunctional (meth)acrylate are separate phases.

[0158] Examples of phase-separated structures include sea-island structures and co-continuous structures. In a sea-island structure, one polymer forms the matrix and the other the dispersed phase in a high-order structure of an incompatible polymer blend. In a co-continuous structure, a phase transition occurs under conditions in which the composition of the polymers constituting the sea-island blend and the ratio of their melt viscosities are approximately proportional, and the co-continuous structure is a high-order structure that appears near the conditions under which the relationship between the sea and islands is reversed due to changes in composition and viscosity ratio, in which two types of polymers form continuous phases with each other.

[0159] Furthermore, as will be described in detail in the Examples below, the phase-separated structure in the cured product of the resin composition can be confirmed by atomic force microscopy.

[0160] <Substrate for Flexible Device and Flexible Device> The substrate for flexible device is a substrate used in the manufacture of a flexible device, such as a foldable display.

[0161] The substrate for flexible devices includes a cured product of a resin composition.

[0162] Such a substrate for a flexible device can be obtained by curing the resin composition by the above-mentioned method and molding it into a sheet.

[0163] A flexible device is obtained using the substrate for a flexible device. Specifically, the flexible device includes the substrate for a flexible device and electronic components disposed on the substrate for a flexible device.

[0164] <Effects> Because the cured product of the resin composition has the above-mentioned peaks (first peak and second peak), the urethane (meth)acrylate and the monofunctional (meth)acrylate are phase-separated in the cured product of the resin composition. Therefore, the cured product of the resin composition has both the performance derived from the urethane (meth)acrylate and the performance derived from the monofunctional (meth)acrylate.

[0165] The urethane (meth)acrylate is a reaction product of a polyol component containing polypropylene glycol having a number average molecular weight of 2000 or more, a polyisocyanate component containing at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and a hydroxyl group-containing (meth)acrylate. Such a urethane (meth)acrylate can improve flexibility and elongation performance. Specifically, the flexibility and elongation performance can be improved even at low temperatures (-20°C).

[0166] The resin composition also contains a homopolymer of a monofunctional (meth)acrylate, which can improve strength against deformation.

[0167] As described above, the cured product of the resin composition has both the properties derived from the urethane (meth)acrylate and the properties derived from the monofunctional (meth)acrylate, and therefore has excellent flexibility, elongation, and strength against deformation.

[0168] The substrate for flexible devices contains a cured product of the resin composition, and therefore has excellent flexibility, elongation performance, and strength against deformation.

[0169] The flexible device includes the flexible device described above, and therefore has excellent flexibility, elongation performance, and strength against deformation.

[0170] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical property values, and parameters used in the following description can be substituted with the upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or more than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, and parameters described in the above "Description of the Invention."

[0171] <Details of Components> The trade names and abbreviations of the components used in each example and each comparative example are detailed below. PPG: Polypropylene glycol PTMEG: Polytetramethylene ether glycol 1,3-H ６ XDI: 1,3-bis(isocyanatomethyl)cyclohexane IPDI: isophorone diisocyanate H １２ MDI: methylenebis(cyclohexyl isocyanate) XDI: xylylene diisocyanate HDI: 1,6-hexamethylene diisocyanate HEA: hydroxyethyl acrylate IBX: isobornyl methacrylate MMA: methyl methacrylate ACMO: acryloylmorpholine IBXA: isobornyl acrylate EBECRYL114: phenoxyethyl acrylate, manufactured by Daicel Allnex Co., Ltd. DCPA: dimethyloltricyclodecane diacrylate DCP: dimethyloltricyclodecane dimethacrylate Omnirad184: photopolymerization initiator, manufactured by IGM resins B.V. Irganox245: antioxidant

[0172] Production Examples 1 to 12 <Production of urethane (meth)acrylate> Under a nitrogen atmosphere, a polyol component and a polyisocyanate component were mixed into a separable glass flask based on the formulation shown in Table 1. Next, the temperature was raised to 80°C, and a urethane-forming catalyst (Stanoct (tin(II) ethylhexanoate)) was mixed in such that the amount was 10 ppm relative to the mixture of the polyol component and the polyisocyanate component. Thereafter, the mixture was allowed to react for 4 hours. This resulted in a reaction liquid containing an isocyanate-terminated prepolymer.

[0173] Next, the reaction liquid containing the isocyanate-terminated prepolymer was placed in a Smith thin-film distillation apparatus, and the isocyanate-terminated prepolymer and unreacted polyisocyanate components were separated under the following conditions. In this way, the isocyanate-terminated prepolymer was purified. {Conditions} Temperature condition: 160 to 170°C Pressure condition: 70 to 100 Pa Supply flow rate: 3.5 to 4 g / min

[0174] Next, in the atmosphere (under dry air), the isocyanate group-terminated prepolymer and the hydroxyl group-containing (meth)acrylate were mixed into the separable flask based on the formulation shown in Table 1 so that the equivalent ratio of the isocyanate groups in the isocyanate group-terminated prepolymer to the active hydrogen groups (hydroxyl groups) in the hydroxyl group-containing (meth)acrylate (isocyanate groups / active hydrogen groups) was 1.0.

[0175] Next, the temperature was raised to 70°C, and Stanoct (tin(II) ethylhexanoate) as a urethanization catalyst was added in a proportion of 200 ppm relative to the isocyanate group-terminated prepolymer, and the reaction was carried out for 4 hours until the isocyanate group concentration reached 0.01% or less, thereby producing a urethane (meth)acrylate.

[0176] <Production of Resin Compositions> Examples 1 to 21 and Comparative Examples 1 to 6 Components were mixed based on Tables 2 to 5. In this way, resin compositions were produced.

[0177] <Production of cured resin composition> The resin composition of each example and each comparative example was applied to a PET film using a doctor blade to obtain a coating film having a thickness of 100 μm. Then, this coating film was irradiated with active energy rays (illuminance 200 mW / cm ２ The irradiation time was 60 seconds. In this way, a cured product of the resin composition was produced.

[0178] <Evaluation> (Storage Modulus) The storage modulus (-20°C) and storage modulus (25°C) of the cured resin compositions of each Example and Comparative Example were measured. Specifically, the dynamic viscoelasticity of the cured resin compositions was measured in accordance with JIS K7244 (1998) under the following conditions. That is, a dumbbell test piece type A was used as the measurement sample. The measurement mode was a tension mode. The measurement frequency was 10 Hz. The measurement temperature range was -100 to 250°C. The temperature rise rate was 5°C / min, and the storage modulus was measured at -20°C and 25°C. The results are shown in Tables 2 to 5.

[0179] (Tensile Test) A tensile test was carried out on the cured resin compositions of each Example and Comparative Example. Specifically, a 201X universal testing machine, stretch tester (manufactured by Intesco Corporation), was used to measure the strength and elongation at break by pulling at a chuck distance of 30 mm and a rate of 300 mm / min. The results are shown in Tables 2 to 5.

[0180] (Restoration Rate) The restoration rate was measured for the cured resin compositions of each Example and Comparative Example. Specifically, using a 201X universal testing machine (manufactured by Intesco Corporation) with a chuck distance of 30 mm and a speed of 1 Hz, the cured resin was stretched by 5% and held for 5 minutes, then returned to 0% and left to stand for 10 minutes, and the length was measured using calipers to calculate the elongation. The results are shown in Tables 2 to 5.

[0181] (Atomic Force Microscopy Measurement) Atomic force microscopy measurements were performed on the cured products of the resin compositions of Examples 16 and 17. Specifically, hardness was measured by atomic force microscopy phase difference detection at a resolution of 19.5 nm on the 2 μm side and 7.8 nm on the 1 μm side within a measurement range of 2 μm × 1 μm near the center in the thickness direction of a cross section of the cured product of the resin composition. As a result, it was found that the cured products of the resin compositions of Examples 16 and 17 had a phase-separated structure.

[0182]

[0183]

[0184]

[0185]

[0186]

[0187] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0188] The resin composition, substrate for flexible devices, flexible device and sheet of the present invention can be suitably used in the production of flexible devices such as wearable devices, flexible sensors, flexible solar cells and flexible displays.

Claims

1. A resin composition comprising a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator, wherein the urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate, the polyol component comprises polypropylene glycol, and the polypropylene glycol has a number average molecular weight of 2000 or more, the polyisocyanate component comprises at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and a cured product of the resin composition has two or more peaks of loss factor tan δ in dynamic viscoelasticity measurement, the peaks including a first peak having a peak top position of less than -20°C and a second peak having a peak top position of 60°C or higher.

2. The resin composition according to claim 1, wherein the number average molecular weight of the polypropylene glycol is 3,000 or more.

3. The resin composition according to claim 1, wherein the monofunctional (meth)acrylate has an alicyclic structure.

4. The resin composition according to claim 1, wherein the content of the monofunctional (meth)acrylate is 60 to 320 parts by mass per 100 parts by mass of the urethane (meth)acrylate.

5. The resin composition according to claim 1, wherein the glass transition temperature of the homopolymer of the monofunctional (meth)acrylate is 70° C. or higher and 300° C. or lower.

6. The resin composition according to claim 1, further comprising a difunctional (meth)acrylate.

7. The resin composition according to claim 6, wherein the content of the bifunctional (meth)acrylate is 3 to 30 parts by mass per 100 parts by mass of the urethane (meth)acrylate.

8. The resin composition according to claim 1, wherein the difference between the peak top position of the first peak and the peak top position of the second peak (peak top position of the second peak - peak top position of the first peak) is 80°C or more and 300°C or less.

9. The resin composition according to claim 1, wherein the urethane (meth)acrylate has a double bond equivalent of 1000 g / eq. or more.

10. A substrate for flexible devices comprising a cured product of the resin composition according to any one of claims 1 to 9.

11. A flexible device comprising the substrate for flexible devices according to claim 10.

12. A sheet comprising a cured product of a resin composition comprising a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator, wherein the urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate, the polyol component comprises polypropylene glycol, and the polypropylene glycol has a number average molecular weight of 2000 or more, the polyisocyanate component comprises at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and in dynamic viscoelasticity measurement of the cured product of the resin composition, there are two or more peaks of loss factor tan δ, and the peaks include a first peak having a peak top position of less than -20°C and a second peak having a peak top position of 60°C or higher.

13. A sheet comprising a cured product of a resin composition comprising a urethane (meth)acrylate, a monofunctional (meth)acrylate, and a photoradical polymerization initiator, wherein the urethane (meth)acrylate is a reaction product of a polyol component, a polyisocyanate component, and a hydroxyl group-containing (meth)acrylate, the polyol component comprises polypropylene glycol, the polypropylene glycol has a number average molecular weight of 2000 or more, the polyisocyanate component comprises at least one of an alicyclic polyisocyanate and an aliphatic polyisocyanate, and the sheet has a phase separation structure in which a layer predominantly composed of the urethane (meth)acrylate and a layer predominantly composed of the monofunctional (meth)acrylate are separate phases.

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