Active energy ray-curable composition, cured product thereof, and laminate

Abstract

To provide an active energy ray-curable composition which has a low viscosity and is capable of yielding a cured product having excellent transparency as well as excellent flexibility and heat resistance; a cured product thereof; and a layered product.SOLUTION: An active energy ray-curable composition contains: a urethane (meth)acrylate (X) having a structural unit derived from farnesene; a (meth)acrylate (Y) other than the urethane (meth)acrylate (X); and a photopolymerization initiator (Z). Also provided are: a cured product of the active energy ray-curable composition; and a layered product that comprises a layer containing at least one of the active energy ray-curable composition and the cured product, and two or more transparent base materials.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable composition, a cured product thereof, and a laminate. [Background technology]

[0002] In optical components such as displays for electronic devices, a transparent resin composition is filled between layers of a transparent substrate to improve visibility. Furthermore, liquid gaskets are filled into joints of automobile parts and the like to fill gaps between the parts, and transparent liquid gaskets are used from the viewpoints of visibility and appearance. For such resin compositions for optical components and liquid gaskets, resin materials that can form cured products that are not only transparent but also have excellent flexibility and good heat resistance are required.

[0003] Patent Document 1 proposes a curable composition containing a hydrogenated polybutadiene polyol-based urethane (meth)acrylate as a highly transparent resin material (for example, Patent Document 1, etc.), and Patent Document 2 proposes a curable composition containing a polypropylene glycol-based urethane (meth)acrylate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-265402 [Patent Document 2] International Publication No. 2009 / 142237 Summary of the Invention [Problem to be solved by the invention]

[0005] Hydrogenated polybutadiene polyol-based urethane (meth)acrylates have high viscosity, and therefore require the addition of a large amount of monomer to adjust the viscosity. If the amount of monomer added is too large, the cohesive strength of the cured product weakens, resulting in a coating film with reduced flexibility. Therefore, it is difficult to obtain a curable composition with low viscosity while maintaining the flexibility of the coating film.

[0006] On the other hand, polypropylene glycol-based urethane (meth)acrylates have low viscosity, so they can be formulated with a small amount of monomer, but they have the problem of low heat resistance of the cured product.

[0007] An object of the present disclosure is to provide an active energy ray-curable composition that has a low viscosity and that can give a cured product that is excellent in transparency, flexibility, and heat resistance, as well as a cured product thereof, and a laminate. [Means for solving the problem]

[0008] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by an active energy ray-curable composition containing a urethane (meth)acrylate (X) containing a structural unit derived from farnesene, a (meth)acrylate (Y) other than the urethane (meth)acrylate (X), and a photopolymerization initiator (Z). [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide an active energy ray-curable composition having a low viscosity, which can give a cured product having excellent transparency, flexibility, and heat resistance, a cured product thereof, and a laminate. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a test piece for evaluating transparency in an example. [Figure 2] FIG. 2 is a top view of a laminate 20 for evaluating heat resistance in an example. [Figure 3] FIG. 2 is a side view of a laminate 20 for evaluating heat resistance in an example. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed herein can be combined with any other feature disclosed herein. Furthermore, when multiple upper and lower limits are described for a particular parameter, any of these upper and lower limits can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limits of a numerical range described in this disclosure are numerical values ​​within that range and may be replaced with numerical values ​​shown in the examples. The expression "1 to 10" indicating a numerical range means "1 or more and 10 or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0012] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the gist of the present disclosure. The present disclosure is not limited to the embodiments.

[0013] Each feature disclosed herein may be combined with any other feature disclosed herein.

[0014] [Active energy ray-curable composition] A first embodiment of the present disclosure relates to an active energy ray-curable composition. The active energy ray-curable composition according to the first embodiment comprises a urethane (meth)acrylate (X) containing a structural unit derived from farnesene, a (meth)acrylate (Y) other than the urethane (meth)acrylate (X), and a photopolymerization initiator (Z). The active energy ray-curable composition according to the first embodiment (hereinafter simply referred to as "curable composition") provides a cured product that has low viscosity yet is excellent in transparency, flexibility, and heat resistance.

[0015] The curable composition according to the first embodiment contains a urethane (meth)acrylate (X) containing a structural unit derived from farnesene (hereinafter, sometimes referred to as "component (X)"). The urethane (meth)acrylate (X) containing a structural unit derived from farnesene has a small side chain molecular weight and weak intermolecular interactions, making it difficult to increase viscosity. Therefore, a low-viscosity curable composition can be obtained with a small amount of monomer. Even more surprisingly, a curable composition with low viscosity obtained by combining component (X) with a (meth)acrylate (Y) other than component (X) (hereinafter, sometimes referred to as "component (Y)") can be obtained, resulting in a cured product with excellent flexibility and heat resistance. Furthermore, the cured product obtained from such a curable composition containing component (X) and component (Y) also has good transparency.

[0016] <Urethane (meth)acrylate (X)> The curable composition according to the first embodiment contains the component (X). As described above, the component (X) is resistant to high viscosity due to its structure. The component (X) may be used alone or in combination of two or more.

[0017] Component (X) is a compound containing a structural unit derived from farnesene, one or more urethane bonds, and one or more acryloyl groups. In one embodiment, component (X) is preferably a compound containing a structural unit derived from farnesene, two or more urethane bonds, and one or less acryloyl groups.

[0018] (Physical Properties) ·viscosity In one embodiment, from the viewpoint of achieving a low viscosity of the curable composition, the viscosity of component (X) at 60°C is preferably 10 to 10,000 mPa·s, more preferably 100 to 8,000 mPa·s, even more preferably 500 to 5,000 mPa·s, and particularly preferably 1,000 to 4,000 mPa·s. The viscosity of component (X) can be measured at 60°C using an E-type viscometer (for example, product name "TV-25" manufactured by Toki Sangyo Co., Ltd.).

[0019] ·Weight average molecular weight (Mw) In one embodiment, the weight average molecular weight (Mw) of the (X) component is preferably 5,000 to 30,000, more preferably 5,000 to 20,000, and even more preferably 8,000 to 18,000. When Mw is 5,000 or more, the flexibility of the cured product tends to be good. Furthermore, fewer by-products are produced during the production of the (X) component, and the appearance of the curable composition tends to be good. Furthermore, when Mw is 30,000 or less, deterioration of curability and changes in shape (melt) due to a decrease in crosslink density are less likely to occur. The "weight average molecular weight (Mw)" of the (X) component is a value measured in terms of polystyrene using GPC, specifically, a value measured by the method described below. In one embodiment, the Mw of component (X) may be greater than 12,000, greater than 12,000 and not greater than 30,000, or greater than 12,000 and not greater than 18,000. When the Mw of component (X) is greater than 12,000, the appearance of the curable composition tends to be better, and the flexibility of the cured product tends to be better.

[0020] In one embodiment, the component (X) is preferably a reaction product of a polyol (A) containing structural units derived from farnesene, a polyisocyanate (B), and a (meth)acrylate (C) having a hydroxyl group. Alternatively, the component (X) may be a reaction product of a urethane prepolymer having an isocyanate group, which is a reaction product of the polyol (A) containing structural units derived from farnesene and the polyisocyanate (B), and a (meth)acrylate (C) having a hydroxyl group. The component (X) may also be a reaction product of a polyol (A) containing a structural unit derived from farnesene, a polyisocyanate (B), a (meth)acrylate having a hydroxyl group (C), and an alcohol having one hydroxyl group (D).

[0021] (Polyol (A)) The polyol (A) is a polyol containing structural units derived from farnesene. In the present disclosure, the term "polyol" refers to a compound having two or more hydroxyl groups in its structure. A preferred example of the polyol (A) is a diol containing structural units derived from α-farnesene and / or β-farnesene. From the viewpoint of ease of production, it is preferable that the polyol (A) contains structural units derived from β-farnesene. α-Farnesene and β-farnesene may be used in combination.

[0022] The polyol (A) may contain structural units (other structural units) other than the structural units derived from farnesene. Examples of the other structural units include structural units derived from conjugated dienes having 12 or less carbon atoms. In a preferred embodiment, the polyol (A) may be a polyol containing structural units derived from farnesene and structural units derived from conjugated dienes having 12 or less carbon atoms.

[0023] The conjugated diene having 12 or less carbon atoms is not particularly limited, and examples thereof include butadiene, isoprene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, chloroprene, etc. These conjugated dienes may be used alone or in combination of two or more.

[0024] In one embodiment, the polyol (A) is preferably a diol represented by the following formula (1) or a diol obtained by reducing (hydrogenating) the diol, and more preferably a diol represented by the following formula (1).

[0025] [ka]

[0026] In the above formula (I), m and n each independently represent an integer of 1 to 7.

[0027] The polyol (A) represented by the formula (I) is preferably polyfarnesene glycol. As the polyfarnesene glycol, a commercially available product may be used, for example, "KRASOL (registered trademark) F3000" manufactured by Cray Valley.

[0028] In one embodiment, the weight average molecular weight (Mw) of the polyol (A) is preferably 1,000 to 4,000, and more preferably 1,000 to 3,000. When the Mw of the polyol (A) is 1,000 to 4,000, the Tg of the (X) component does not become too high, and the flexibility of the cured product tends to be good. In addition, the amount of by-products in the (X) component tends to be small. Furthermore, the compatibility of the (X) component with other components including the (Y) component is less likely to deteriorate. The "weight average molecular weight (Mw)" of the polyol (A) is a value measured in polystyrene equivalent terms by GPC, specifically, a value measured by the method described below. In one embodiment, the Mw of the polyol (A) may be less than 2,000, or may be 1,000 or more and less than 2,000. When the Mw of the polyol (A) is less than 2,000, it is easy to obtain a component (X) with a lower viscosity, and it is easy to adjust the viscosity of the curable composition.

[0029] (Other polyols) In one embodiment, component (X) may contain a polyol other than polyol (A) as a raw material. Examples of other polyols include polyolefin polyols, hydrogenated polyolefin polyols, polyester polyols, trimethylolpropane, pentaerythritol, glycerin, and modified compounds thereof. From the viewpoint of easily obtaining a component (X) with a lower viscosity, it is preferable to contain only polyol (A).

[0030] (Polyisocyanate (B)) In the present disclosure, "polyisocyanate" refers to a compound having two or more isocyanate groups in its structure. The polyisocyanate (B) is not particularly limited, and is preferably, for example, at least one diisocyanate selected from the group consisting of alicyclic diisocyanates, branched aliphatic diisocyanates, and diisocyanate compounds obtained by hydrogenating aromatic diisocyanates. The alicyclic diisocyanate is not particularly limited, but examples thereof include isophorone diisocyanate. The branched chain aliphatic diisocyanate is not particularly limited, but examples thereof include 2,2,4-trimethylhexamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate. The diisocyanate compounds obtained by hydrogenating the aromatic isocyanates are not particularly limited, but examples thereof include hydrogenated xylylene diisocyanate and hydrogenated diphenylmethane diisocyanate.

[0031] ((Meth)acrylate (C) having a hydroxyl group) The (meth)acrylate (C) having a hydroxyl group (hereinafter sometimes referred to as "(meth)acrylate (C)") is not particularly limited as long as it is a compound having one or more hydroxyl groups and one or more acryloyl groups. In one embodiment, a (meth)acrylate of an aliphatic alcohol is preferred, and from the viewpoint of good compatibility with the polyol (A), a monofunctional (meth)acrylate of an aliphatic alcohol having one hydroxyl group and one acryloyl group is particularly preferred. Preferred examples of such a (meth)acrylate (C) include, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxy-n-propyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The (meth)acrylate (C) having a hydroxyl group may be used alone or in combination of two or more.

[0032] (Alcohol (D) having one hydroxyl group) In one embodiment, the component (X) may contain, as a raw material, an alcohol (D) having one hydroxyl group (hereinafter, sometimes referred to as "alcohol (D)"). By containing the alcohol (D) as a raw material, it becomes easier to adjust the acryloyl group concentration of the component (X), as described below. Examples of such alcohols (D) include aliphatic or alicyclic primary alcohols having 3 or more carbon atoms, and their molecular weight is preferably 70 to 400. Alcohols (D) having 3 or more carbon atoms or a molecular weight of 70 or more are preferred because they are less likely to volatilize during the synthesis of the component (X). Furthermore, if the molecular weight is 400 or less, the reactivity with the polyisocyanate (B) is less likely to decrease, and the production time is not too long. Furthermore, if the alcohol is an aliphatic or alicyclic alcohol, the hue of the component (X) will not be too high, and weather resistance is likely to be good. Specific examples include 1-butanol, 1-heptanol, 1-hexanol, normal octyl alcohol, 2-ethylhexyl alcohol, cyclohexanemethanol, capryl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol (cetanol), stearyl alcohol, and mixtures thereof. Among these, 2-ethylhexyl alcohol is preferred from the viewpoints of boiling point, price, and availability. The alcohol (D) may be used alone or in combination of two or more.

[0033] <Method for producing urethane (meth)acrylate (X)> The method for producing the component (X) includes reacting (urethanization reaction) a polyol (A), a polyisocyanate (B), and a (meth)acrylate (C). Although the reaction method is not particularly limited, in one embodiment, a preferred method is to prepare a urethane isocyanate prepolymer by reacting a polyol (A) with a polyisocyanate (B) (step (1)), and then react the urethane isocyanate prepolymer with a (meth)acrylate (C) (step (2)) to obtain the component (X). When reacting the urethane isocyanate prepolymer with the (meth)acrylate (C), the (meth)acrylate (C) may be used in combination with an alcohol (D).

[0034] (Process (1)) Compared to conventional production methods such as "a method of mixing and reacting polyol (A), polyisocyanate (B), and (meth)acrylate (C), or (A) to (C) and alcohol (D) all at once," or "a method of reacting polyisocyanate (B), (meth)acrylate (C), and alcohol (D) to form a urethane isocyanate prepolymer containing an isocyanate group, and then reacting the prepolymer with polyol (A)," step (1) is more likely to prevent an increase in viscosity, improve the appearance of component (X), suppress the production of by-products, and improve the transparency and heat resistance of the cured product.

[0035] Specifically, when a curable composition is produced by a method in which polyol (A), polyisocyanate (B), and (meth)acrylate (C), or (A), (B), and (C) and alcohol (D) are mixed together and reacted, the resulting component (X) tends to have a high viscosity. As a result, a large amount of monomer must be added to adjust the viscosity of the curable composition. Furthermore, stirring can be difficult or the reaction can proceed unevenly, increasing the likelihood of partial gelation. Furthermore, the amount of by-products that do not have polyol (A) in their skeletons tends to increase, resulting in reduced transparency and flexibility. Furthermore, the tendency for various complex compounds to be irregularly produced makes quality control of curable compositions containing component (X) difficult.

[0036] Furthermore, in the case of "a method of reacting a polyisocyanate (B) with a (meth)acrylate (C) and an alcohol (D) to form a urethane isocyanate prepolymer containing an isocyanate group, and then reacting the prepolymer with a polyol (A)," a compound in which all of the isocyanate groups of the polyisocyanate (B) have reacted with the (meth)acrylate (C) or the alcohol (D) is likely to be produced as a by-product. This by-product exhibits crystallinity because it does not contain the skeleton of the polyol (A), and as a result, transparency is likely to decrease and the possibility of gelation is increased.

[0037] From the above viewpoints, a preferred method is to react the polyol (A) with the polyisocyanate (B) to form a urethane isocyanate prepolymer, and then react the urethane isocyanate prepolymer with the (meth)acrylate (C). That is, the following methods 1 to 3 can also be used in step (1). [Method 1] Polyol (A) and polyisocyanate (B) are mixed together and reacted. [Method 2] A method in which polyol (A) is added dropwise to polyisocyanate (B) to cause a reaction. [Method 3] A method in which polyisocyanate (B) is added dropwise to polyol (A) to cause a reaction.

[0038] In the case of [Method 3], polyisocyanate (B) is added dropwise to a large amount of polyol (A) while reacting, and the isocyanate groups on both sides of polyisocyanate (B) undergo urethane reaction with the hydroxyl groups of two moles of polyol (A), which is likely to produce a diol with hydroxyl groups at both ends, typically an ABA type, as a by-product. When two more moles of polyisocyanate (B) react with this diol, a compound with isocyanate groups at both ends, typically a BABAB type, as a by-product, is likely to be produced. Repeating a similar reaction may result in a large amount of a compound with the following structure, typically: B-[AB]nAB (n = an integer greater than or equal to 1) If a urethane prepolymer containing a large amount of such by-products is reacted with a (meth)acrylate (C) and an alcohol (D), the acrylic density of the resulting component (X) will be low, making it difficult to obtain a cured product with sufficient crosslink density. Therefore, from the viewpoint of easily obtaining a cured product having excellent flexibility and heat resistance, it is preferable to synthesize the urethane isocyanate prepolymer by [Method 1] or [Method 2].

[0039] A preferred method for producing a urethane isocyanate prepolymer by [Method 1] is as follows. First, polyol (A) is charged into a reactor and stirred until homogeneous, and then polyisocyanate (B) is further charged and homogenized. When preparing a component (X) with a relatively large Mw, a (meth)acrylate (Y) may be added to polyol (A) as a diluent, and the polyol (A) and component (Y) may be stirred until homogeneous, followed by charging of polyisocyanate (B). This allows the viscosity of the reaction solution to be kept low. It is then desirable to continue stirring, raise the temperature as needed, and then add a urethanization catalyst to initiate urethanization. After adding the urethanization catalyst, the temperature may be raised as needed.

[0040] If the urethane-forming catalyst is added from the beginning before the polyol (A) and polyisocyanate (B) become uniform, the urethane-forming reaction will proceed in a non-uniform state when the polyisocyanate (B) is being charged, which may result in changes in the molecular weight and viscosity of the resulting urethane prepolymer and the reaction ending with unreacted polyisocyanate (B) remaining in the system. In such cases, the (meth)acrylate (C) and alcohol (D) used later will react with the remaining polyisocyanate (B), easily producing by-products and easily reducing the transmittance of the resulting cured product.

[0041] In one embodiment, the content of the aforementioned by-products in component (X) is preferably less than 7 wt % relative to the total weight of component (X). If the content of by-products is less than 7 wt %, the transparency of the cured product tends to be good.

[0042] [Method 1] is preferable in that when the polyol (A) has a high viscosity or the polyisocyanate (B) is a solid, these raw materials can be charged directly into the reactor, and the component (X) can be produced in one pot.

[0043] A preferred method for producing a urethane isocyanate prepolymer by [Method 2] is as follows. A reactor is charged with polyisocyanate (B), a urethane catalyst, and, if necessary, a portion of the (meth)acrylate (Y), and the mixture is stirred until homogeneous. While stirring, the temperature is raised as necessary, and the homogeneous mixture of polyol (A) and (meth)acrylate (Y) is added dropwise to react them. [Method 2] is a method suitable for the case where the polyol (A) has a high viscosity. A homogeneous mixture of the polyol (A) and the (meth)acrylate (Y) is prepared to have a low viscosity, and this mixture is then added dropwise to the polyisocyanate (B), thereby making it difficult for the by-products described in [Method 3] to be produced.

[0044] In either method, it is preferable to carry out the reaction in step (1) until all hydroxyl groups are urethane-converted. The end point of the reaction can be confirmed by measuring the isocyanate group concentration (hereinafter also referred to as "NCO group concentration") in the reaction solution, and checking whether the isocyanate group concentration is equal to or less than the isocyanate group concentration (theoretical NCO concentration) when all hydroxyl groups charged into the system are urethane-converted, or whether the isocyanate group concentration no longer changes.

[0045] In one embodiment, the molar ratio of the isocyanate groups of the polyisocyanate (B) relative to 1 mole of the hydroxyl groups of the polyol (A) is preferably from 1.1 to 2.0 moles, more preferably from 1.1 to 1.6 moles.

[0046] In one embodiment, step (1) is preferably carried out in the presence of a polymerization inhibitor. Preferred examples of polymerization inhibitors include dibutylhydroxytoluene, hydroquinone, hydroquinone monomethyl ether, and phenothiazine. These may be used alone or in combination of two or more. The amount of these polymerization inhibitors added is preferably 1 to 10,000 ppm (by weight) of the resulting component (X), more preferably 100 to 1,000 ppm, and even more preferably 400 to 1,000 ppm. When the amount of polymerization inhibitor added is within the above range, sufficient polymerization inhibition effect is easily obtained and the physical properties of the component (X) are less likely to be adversely affected.

[0047] (Process (2)) The urethane isocyanate prepolymer obtained in the above step (1) is reacted with a (meth)acrylate (C) (in one embodiment, the (meth)acrylate (C) and an alcohol (D)) to obtain the component (X). If a large amount of unreacted isocyanate groups remains in the reaction solution at this time, problems such as gelation or poor curing of the coating film may occur. To avoid these problems, it is preferable that in step (2), the reaction is carried out so that the number of moles of hydroxyl groups in the (meth)acrylate (C) is in excess relative to the number of moles of isocyanate groups in the urethane isocyanate prepolymer, and the reaction is continued until the concentration of residual isocyanate groups in the reaction solution reaches 0.05% by weight or less. In the reaction, the number of moles of hydroxyl groups in the (meth)acrylate (C) per mole of isocyanate groups in the urethane isocyanate prepolymer is preferably 1.005 to 1.1 moles, more preferably 1.01 to 1.05. In one embodiment, the molar ratio ((B):(C)) of the polyisocyanate (B) to the (meth)acrylate (C) may be 3.00:2.00 to 3.00:2.09.

[0048] For the same purpose, the production of component (X) is preferably carried out in an atmosphere of a molecular oxygen-containing gas, the oxygen concentration being appropriately selected taking safety into consideration.

[0049] In one embodiment, a catalyst (urethanation catalyst) may be used to achieve a sufficient reaction rate. Examples of catalysts that can be used include dibutyltin dilaurate, tin octoate, tin chloride, bismuth(III) neodecanoate, bismuth(III) 2-ethylhexanoate, zinc neodecanoate, and zinc octoate, with dibutyltin dilaurate being preferred from the standpoint of reaction rate. The amount of these catalysts added is typically 1 to 3,000 ppm (by weight) of the resulting component (X), and more preferably 50 to 1,000 ppm. When the amount of catalyst added is within the above range, a sufficient reaction rate is likely to be achieved and the physical properties of the component (X) are unlikely to be adversely affected.

[0050] The production of component (X) can be carried out in the presence of a known volatile organic solvent. After the production of component (X), the volatile organic solvent can be distilled off under reduced pressure. Alternatively, the volatile organic solvent remaining in the active energy ray-curable resin composition can be applied to a transparent substrate and then removed by drying. The volatile organic solvent refers to an organic solvent whose boiling point does not exceed 200°C.

[0051] In one embodiment, when the composition is applied to a field where curing is performed in a sealed environment, it is preferable that substantially no volatile organic solvents be used from the time of producing the component (X) to the time of preparing the final curable composition. That is, when the composition is applied to such a field, the proportion of volatile organic solvents contained in the curable composition according to the first embodiment is preferably 0.5 wt % or less, and more preferably 0.1 wt % or less, based on the total weight of the curable composition.

[0052] In one embodiment, the reaction temperature in step (1) and / or step (2) is preferably 130° C. or lower, more preferably 40 to 130° C. If the reaction temperature is within the above range, it is easy to suppress the generation of gelled matter while maintaining a practically sufficient reaction rate.

[0053] Step (2) is preferably carried out until the concentration of residual isocyanate groups reaches 0.1% by weight or less. The concentration of residual isocyanate groups can be analyzed by gas chromatography, titration, or the like.

[0054] In one embodiment, the acryloyl group concentration in component (X), calculated using the following formula (3), is preferably 0.10 mol / kg or more and less than 1.0 mol / kg, and more preferably 0.2 mol / kg or more and less than 0.60 mol / kg. Acryloyl group concentration (mol / kg) = weight of (meth)acrylate (C) (g) × number of (meth)acryloyl groups in (meth)acrylate (C) molecule ÷ molecular weight of (meth)acrylate (C) × 1000 ÷ weight of component (X) (g) (3) Here, the number of acryloyl groups in the (meth)acrylate (C) is, for example, 1 in the case of 2-hydroxyethyl acrylate, and 3 in the case of pentaerythritol triacrylate.

[0055] If the acryloyl group concentration is 0.10 mol / kg or more, the composition is sufficiently cured upon irradiation with active energy rays, and the cohesive strength and initial adhesion to the substrate are not likely to decrease. Furthermore, if the concentration is less than 1.0 mol / kg, the heat resistance of the resulting cured product is not likely to decrease. In this disclosure, "excellent heat resistance" means that when the cured product is stored at 95°C for 1,000 hours, the coating film does not increase in hardness, the adhesion to the substrate is not reduced, and curing shrinkage and changes in shape do not occur. In other words, from the perspective of improving the heat resistance of the resulting cured product, it is effective to keep the acryloyl group concentration in component (X) low and reduce curing shrinkage. However, this will result in a decrease in coating film hardness and a tendency for adhesion to the substrate to decrease. In one embodiment, from the viewpoint of preventing a decrease in coating film hardness while keeping the acryloyl group concentration of component (X) low (preferably less than 1.0 mol / kg), the aforementioned alcohol (D) may be reacted with component (X) to alkoxylate some of the terminal acryloyl groups of component (X).

[0056] <(Meth)acrylate (Y)> The curable composition according to the first embodiment contains a (meth)acrylate (Y) other than the component (X). The component (Y) is selected from the viewpoint of adjusting the viscosity of the curable composition and various physical properties of the cured product. In one embodiment, from the viewpoint of easily adjusting viscosity, improving the appearance of the curable composition, suppressing by-products, and improving the transparency and heat resistance of the cured product, the component (Y) preferably contains a monofunctional (meth)acrylate.

[0057] As monofunctional (meth)acrylates, from the viewpoint of ease of adjusting viscosity and physical properties of the cured product, methyl (meth)acrylate, ethyl (meth)acrylate, glycerin mono(meth)acrylate, glycidyl (meth)acrylate, dicyclopentenyl (meth)acrylate, n-butyl (meth)acrylate, β-carboxyethyl (meth)acrylate, isobornyl (meth)acrylate, octyl / decyl (meth)acrylate (mixture of octyl (meth)acrylate and decyl (meth)acrylate), Examples of the acrylates include acrylates (meth)acrylates), n-octyl (meth)acrylate, isooctyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and β-carboxyethyl acrylate. These may be used alone or in combination of two or more. Among these, from the viewpoints of high dilution efficiency and easy viscosity adjustment of the curable composition, aliphatic (meth)acrylates in which the alkyl group has 1 to 15 carbon atoms are preferred, n-octyl (meth)acrylate and octyl / decyl (meth)acrylate are more preferred, and n-octyl acrylate (NOA) is even more preferred. Furthermore, from the viewpoint of easily improving the toughness and stretchability of the cured product, alicyclic (meth)acrylates are preferred, isobornyl (meth)acrylate is more preferred, and isobornyl acrylate (IBOA) is even more preferred. In one embodiment, the (Y) component may contain one or more selected from n-octyl acrylate (NOA), isobornyl acrylate (IBOA), and octyl / decyl (meth)acrylate.

[0058] The curable composition according to the first embodiment can achieve low viscosity at least with the amount of component (Y). In one embodiment, the viscosity of the curable composition at 25°C may be 600 mPa·s or less. In addition, the content of component (Y) in the curable composition at this time is preferably 90 wt% or less, based on the total weight of the curable composition. In one embodiment, the proportion of component (Y) relative to the total weight of the curable composition may be 60 wt% or less, or may be 55 wt% or less. In another embodiment, when component (Y) includes at least one selected from NOA and IBOA, the proportion of component (Y) relative to the total weight of the curable composition having the aforementioned viscosity may be 20 to 55 wt%, or may be 25 to 55 wt%.

[0059] <Photopolymerization initiator (Z)> The curable composition according to the first embodiment contains a photopolymerization initiator (Z) (hereinafter, also referred to as "component (Z)"). As the component (Z), a known photoradical polymerization initiator or photocationic polymerization initiator can be used depending on the type of active energy ray and the component (X). Examples of the (Z) component include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, diethoxyacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, and benzoin. Examples of the (Z) component include methyl dimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, methylphenyl glyoxylate, benzil, camphorquinone, etc. These (Z) components may be used alone or in combination of two or more.

[0060] The content of component (Z) is not particularly limited. In one embodiment, it is preferably 1 to 20 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the total of components (X) and (Y). When the content of component (Z) is within the above range, poor curing is unlikely to occur, and a curable composition with little odor originating from component (Z) is likely to be obtained.

[0061] <Additives> The curable composition according to the first embodiment may contain various additives as needed. Examples of such additives include organic and / or inorganic fillers, dyes and pigments, leveling agents, UV absorbers, light stabilizers, antifoaming agents, dispersants, and thixotropy-imparting agents. The content of these additives is not particularly limited, but may be, for example, 0 to 10 parts by weight or 0.05 to 5 parts by weight per 100 parts by weight of the curable composition.

[0062] As described above, the curable composition according to the first embodiment has a low viscosity and can give a cured product that is excellent in transparency, heat resistance, and flexibility. In one embodiment, the cured product obtained by curing the curable composition under the following conditions preferably has a transmittance of 95% or more at a wavelength of 400 nm. (Ultraviolet irradiation conditions) Irradiation intensity: 120W / cm Irradiation distance: 10cm Conveyor speed: 5m / min Number of irradiations: 2 times

[0063] <Method for producing curable composition> The curable composition according to the first embodiment can be produced by mixing the components (X) to (Z) with the additives. Known or commonly used mixing means, such as various mixers such as dissolvers and homogenizers, kneaders, rolls, bead mills, and planetary stirrers, can be used. The mixing conditions, such as the temperature and rotation speed, are not particularly limited and can be set appropriately. In one embodiment, the method for producing the curable composition may include blending the (Y) component with the (X) component to obtain a viscosity adjusting liquid, and blending the (Z) component with the viscosity adjusting liquid to obtain the curable composition.

[0064] <Uses of the curable composition> The curable composition according to the first embodiment is characterized by low viscosity at least when the amount of component (Y) is high. Furthermore, the curable composition can produce a cured product with excellent transparency, flexibility, and heat resistance. Such a curable composition can be suitably used, for example, as a curable composition for optical components or liquid gaskets. Naturally, the applications of the curable composition are not limited to optical components and liquid gaskets.

[0065] [Cured product] The second embodiment of the present disclosure is a cured product of the curable composition according to the first embodiment. The curable composition according to the first embodiment can be cured by irradiation with active energy rays. The cured product according to the second embodiment includes both a product obtained by irradiating the above-mentioned curable composition with active energy rays described below to promote the curing reaction, and a product obtained by irradiating the curable composition with active energy rays to completely cure it. In addition, a "semi-cured product" in which the curable composition has been cured to the extent that it no longer has fluidity is also included in the cured product of this embodiment.

[0066] The cured product according to the second embodiment can be obtained as a cured coating film, for example, by applying the curable composition according to the first embodiment to an object such as a substrate, and then irradiating the applied curable composition with active energy rays.

[0067] The method for applying the curable composition is not particularly limited, and conventionally known methods can be used, such as spraying, airless spraying, air spraying, roll coating, bar coating, and gravure coating. Among these, roll coating is most preferably used from the viewpoints of aesthetics, cost, workability, and the like. The application of the curable composition may be a so-called in-line coating method, in which the application is carried out during the production process of a plastic film or the like, or a so-called offline coating method, in which the application is carried out in a separate process on an already manufactured substrate. From the viewpoint of production efficiency, the offline coating method is preferred.

[0068] <Active energy rays> Examples of the active energy rays include ultraviolet rays and electron beams. Examples of light sources used for ultraviolet irradiation include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, and metal halide lamps. The irradiation time varies depending on the type of light source, the distance between the light source and the coating surface, and other conditions, but is at most several tens of seconds, and is usually several seconds. Typically, an irradiation source with a lamp output of about 80 to 300 W / cm is used. In the case of electron beam irradiation, it is preferable to use electron beams having an energy in the range of 50 to 1000 KeV and an irradiation dose of 2 to 5 Mrad. After irradiation with active energy rays, heating may be carried out as necessary to promote curing.

[0069] The thickness of the cured coating film is not particularly limited and can be adjusted as desired depending on the application, for example, within the range of 0.5 to 1,000 μm, preferably 2 to 500 μm.

[0070] The object (subject to be coated) onto which the curable composition is applied is not particularly limited, and examples thereof include various articles such as plastic articles, articles whose plastic surfaces have been subjected to metal vapor deposition, glass, wood, metal plates, and paper. The coated surface may be subjected to a release treatment. When the curable composition according to the first embodiment is used for optical components, particularly as an interlayer filler for transparent substrates (curable composition for interlayer filling), it is preferable to apply it to a transparent substrate. Details of the transparent substrate will be described later.

[0071] [Laminate] A third embodiment of the present disclosure is a laminate comprising a layer containing one or more selected from the curable composition according to the first embodiment and the cured product according to the second embodiment. In one embodiment, the laminate may comprise a layer containing one or more selected from the curable composition according to the first embodiment and the cured product according to the second embodiment, and two or more transparent substrates. Furthermore, a layer containing one or more selected from the curable composition according to the first embodiment and the cured product according to the second embodiment may be disposed between the two or more transparent substrates.

[0072] <Transparent base material> When the laminate has a transparent substrate, the transparent substrate may be a glass substrate such as a transparent glass plate, or a plastic substrate such as a transparent plastic film.

[0073] The plastic substrate can be any existing transparent material and is not particularly limited, but examples thereof include polyolefin resins such as polyethylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, acrylic resins, polycarbonate resins, etc. Among these, polycarbonate resins and acrylic resins are particularly preferably used.

[0074] <Method of manufacturing laminate> A method for producing a laminate according to the third embodiment includes a method comprising applying the curable composition according to the first embodiment onto one or more substrates. In one embodiment, the method may comprise irradiating the curable composition with active energy rays after application of the curable composition. Furthermore, when the transparent substrate described above is used as the substrate, the method may comprise irradiating the curable composition with active energy rays from the transparent substrate side. As the application method of the curable composition and the active energy rays, those described in the section on the cured product can be preferably used.

[0075] In one embodiment, the method for producing a laminate according to the third embodiment may include injecting the curable composition according to the first embodiment between two or more transparent substrates. The method may also include irradiating the curable composition according to the first embodiment from the transparent substrate side after the injecting with active energy rays. In this case, it is preferable to use a cartridge to prevent the generation of bubbles.

[0076] In the laminate, the thickness of the layer containing one or more selected from the curable composition according to the first embodiment and the cured product according to the second embodiment is preferably 30 to 300 μm, more preferably 50 to 200 μm. If the layer thickness is within the above range, the cost is not too high, and the layer thickness tends to be uniform. In addition, flexibility tends to be good. [Example]

[0077] The present invention will be described in more detail below based on synthesis examples and working examples, but the present invention is not limited to these examples in any way.

[0078] Synthesis examples and comparative synthesis examples are described below. The concentration notations "ppm" and "wt%" refer to concentrations relative to the (theoretically) obtained urethane (meth)acrylate (X) unless otherwise specified. Additionally, methods for measuring the isocyanate group concentration, viscosity, and weight-average molecular weight are described.

[0079] (Measurement of isocyanate group concentration) The isocyanate group concentration was measured as follows: The measurement was carried out in a 100 mL glass flask while stirring with a stirrer. Blank value measurement To 15 mL of THF, 15 mL of a 0.1 N dibutylamine THF solution was added, and three drops of bromophenol blue (1% methanol diluted solution) were added to turn the solution blue. The solution was then titrated with a 0.1 N HCl solution. The titer of the HCl solution at the point where a color change was observed was defined as Vb (mL). Measurement of actual isocyanate group concentration A sample (Ws) (g) was weighed and dissolved in 15 mL of THF, followed by the addition of 15 mL of a 0.1 N dibutylamine THF solution. After confirming that the solution had been dissolved, three drops of bromophenol blue (1% methanol diluted solution) were added to turn the solution blue. The solution was then titrated with a 0.1 N HCl aqueous solution. The titration volume of the HCl aqueous solution at the point when a color change was observed was recorded as Vs (mL). The isocyanate group concentration in the sample was calculated using the following formula. Isocyanate group concentration (wt%) = (Vb - Vs) × 1.005 × 0.42 ÷ Ws

[0080] (Viscosity measurement method) Urethane (meth)acrylate (X) The viscosity of the urethane (meth)acrylate (X) was measured at 60°C using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name "TV-25 Model"). ·Curable composition The viscosity of the curable composition was measured at 25°C using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name "TV-25 Model").

[0081] (Weight average molecular weight (Mw)) The weight average molecular weight was determined by GPC (gel permeation gas chromatography) under the following measurement conditions using standard polystyrene as the standard. Equipment used: High-speed GPC device (Tosoh Corporation, product name "HLC-8220GPC") Pump: DP-8020 Detector: RI-8020 Column type: Super HZM-M, Super HZ4000, Super HZ3000, Super HZ2000 Solvent: Tetrahydrofuran Phase flow rate: 1mL / min Column pressure: 5.0 MPa Column temperature: 40℃ Sample injection volume: 10 μL Sample concentration: 0.2 mg / mL

[0082] <Material> The materials used in the examples and comparative examples are as follows. Polyol (A) (A1): Polyfarnesene glycol (manufactured by Cray Valley, product name "KRASOL F3000" (Mw: 1488, hydroxyl value: 0.672 mmol / g, non-volatile content: 99.91%). Polyol (A') (A'1): Polypropylene glycol (manufactured by Sanyo Chemical Industries, Ltd., product name "Sannyx (registered trademark) PT2001", Mw: 1964, hydroxyl value: 57.1 mgKOH / g). (A'2): Polyester polyol (manufactured by Mitsui Chemicals, Inc., product name "Takelac (registered trademark) U2710", Mw: 988, hydroxyl value: 113.5 mgKOH / g). (A'3): Hydrogenated polybutadiene glycol (manufactured by Nippon Soda Co., Ltd., product name "NISSO PB GI3000" (Mw: 3965, hydroxyl value: 28.3 mg KOH / g). The Mw of the polyol (A) and the polyol (A') is a value calculated from the following formula (4) or (5) based on the hydroxyl value. Mw = 56.1 ÷ hydroxyl value (mgKOH / g) × 2,000 (4) Mw = 2,000 ÷ hydroxyl number (mmol / g) (5)

[0083] Polyisocyanate (B) (B1): Isophorone diisocyanate (IPDI) (manufactured by Evonik Corporation, product name "VESTANAT (registered trademark) IPDI", Mw: 222). (B2): Hexamethylene diisocyanate (HDI) (manufactured by Tosoh Corporation, product name "HDI", Mw: 168). (B3): 2,2,4-trimethylhexamethylene diisocyanate (TMHDI) (manufactured by Evonik Corporation, product name "TMDI", Mw: 210). (B4): Diphenylmethane diisocyanate (MDI) (manufactured by Tosoh Corporation, product name "MDI", Mw: 250). (B5): Methylenebis(4-cyclohexylisocyanate) (hydrogenated MDI) (manufactured by Evonik Corporation, product name "DESMODUR (registered trademark) W", Mw: 262). (B6): Toluene diisocyanate (TDI) (manufactured by Tosoh Corporation, product name "TDI", Mw: 174).

[0084] (Meth)acrylate with hydroxyl group (C) (C1): 2-hydroxyethyl acrylate (manufactured by Nippon Shokubai Co., Ltd., product name "HEA"). Alcohols with one hydroxyl group (D) (D1): 2-Ethylhexyl alcohol (manufactured by Sankyo Chemical Co., Ltd., product name "2-Ethylhexanol"). (Meth)acrylate (Y) (Y1): n-octyl acrylate (NOA) (manufactured by Osaka Organic Chemical Co., Ltd., product name "NOAA"). (Y2): Isobornyl acrylate (IBOA) (manufactured by Daicel-Allnex Co., Ltd., product name "IBOA-B"). Photopolymerization initiator (Z) 1-Hydroxycyclohexyl phenyl ketone (manufactured by IGM, product name "Omnirad (registered trademark) 184").

[0085] <Synthesis of urethane (meth)acrylate (X)> (Synthesis example 1 / (X-1)) The polyol (A1), polyisocyanate (B1), and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.02. The actual amounts charged and reaction conditions are described below. A separable flask equipped with a thermometer and a stirrer was charged with 303.0 g of polyol (A1) (polyfarnesene glycol) and 800 ppm of dibutylhydroxytoluene (BHT). The internal temperature was raised to 50°C, and after homogenizing the system, 34 g of polyol (B1) (IPDI) was added. 300 ppm of a urethane catalyst (dibutyltin dilaurate (DBTDL)) was then added, and the internal temperature was set to 70°C to prepare a urethane isocyanate prepolymer. Completion of the reaction was confirmed when the isocyanate group concentration in the reaction solution was below the theoretical NCO concentration (the same applies to other synthesis examples). In this example, the next step was performed after confirming that the isocyanate group concentration in the reaction solution was below the theoretical endpoint isocyanate group concentration (1.27 wt%). The theoretical NCO concentration (prepolymer) was calculated using the following equation (6). Theoretical NCO concentration = 42 × 2 × 100 ÷ (Polyol Mw × 2 + Isocyanate Mw × 3) (6) After confirming the isocyanate group concentration in the reaction solution, 12.4 g of (meth)acrylate (C1) was added all at once to the reaction solution. After aging for 2 hours, it was confirmed that the isocyanate group concentration was less than 0.05 wt %, and then the reaction was terminated to obtain urethane (meth)acrylate (X-1). The acryloyl group concentration of the obtained urethane (meth)acrylate (X-1) was 1,918 g / mol (0.52 mol / kg).

[0086] (Synthesis example 2 / (X-2)) Urethane (meth)acrylate (X-2) was obtained by the same synthesis procedure as in Synthesis Example 1, except that polyol (A1), polyisocyanate (B2), and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.02. The acryloyl group concentration of the obtained urethane (meth)acrylate (X-2) was 1,838 g / mol (0.54 mol / kg).

[0087] (Synthesis example 3 / (X-3)) Urethane (meth)acrylate (X-3) was obtained by the same synthesis procedure as in Synthesis Example 1, except that polyol (A1), polyisocyanate (B3), and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.02. The acryloyl group concentration of the obtained urethane (meth)acrylate (X-3) was 1,901 g / mol (0.53 mol / kg).

[0088] (Synthesis example 4 / (X-4)) Urethane (meth)acrylate (X-4) was obtained by the same synthesis procedure as in Synthesis Example 1, except that polyol (A1), polyisocyanate (B4), and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.02. The acryloyl group concentration of the obtained urethane (meth)acrylate (X-4) was 1,950 g / mol (0.51 mol / kg).

[0089] (Synthesis example 5 / (X-5)) Urethane (meth)acrylate (X-5) was obtained by the same synthesis procedure as in Synthesis Example 1, except that polyol (A1), polyisocyanate (B5), and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.02. The acryloyl group concentration of the obtained urethane (meth)acrylate (X-5) was 1,978 g / mol (0.51 mol / kg).

[0090] (Synthesis example 6 / (X-6)) Urethane (meth)acrylate (X-6) was obtained by the same synthesis procedure as in Synthesis Example 1, except that polyol (A1), polyisocyanate (B6), and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.02. The acryloyl group concentration of the obtained urethane (meth)acrylate (X-6) was 1,847 g / mol (0.54 mol / kg).

[0091] (Synthesis example 7 / (X-7)) Polyol (A1), polyisocyanate (B1), (meth)acrylate (C1), and alcohol (D1) were reacted in a molar ratio of 2.0:3.0:1.80:0.20. The actual amounts charged and reaction conditions are described below. A separable flask equipped with a thermometer and a stirrer was charged with 404.1 g of polyol (A1) (polyfarnesene glycol) and 800 ppm of dibutylhydroxytoluene (BHT). The internal temperature was raised to 50°C, and after homogenizing the system, 34 g of polyol (B1) (IPDI) was added. 300 ppm of a urethane catalyst (dibutyltin dilaurate (DBTDL)) was then added, and the internal temperature was set to 70°C to prepare a urethane isocyanate prepolymer. Completion of the reaction was confirmed when the isocyanate group concentration in the reaction solution was below the theoretical NCO concentration (the same applies to other synthesis examples). In this example, the next step was performed after confirming that the isocyanate group concentration in the reaction solution was below the theoretical endpoint isocyanate group concentration (0.98 wt%). The theoretical NCO concentration (prepolymer) was calculated using the above formula (6). After confirming the isocyanate group concentration in the reaction solution, 10.6 g of (meth)acrylate (C1) and 1.3 g of alcohol (D1) were added all at once to the reaction solution. After aging for 2 hours, it was confirmed that the isocyanate group concentration was less than 0.05 wt %, and then the reaction was terminated to obtain urethane (meth)acrylate (X-7). The acryloyl group concentration of the obtained urethane (meth)acrylate (X-7) was 2,052 g / mol (0.49 mol / kg).

[0092] (Comparative synthesis example 1 / (X'-1)) The polyol (A'1), polyisocyanate (B1) and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.10. The actual amounts charged and reaction conditions are described below. A separable flask equipped with a thermometer and a stirrer was charged with 307.8 g of polyol (A'1), 67.5 g of polyisocyanate (B1), and 800 ppm of dibutylhydroxytoluene (BHT). After stirring for 1 hour to homogenize the system, 300 ppm of urethane catalyst (DBTDL) was added. After confirming that the internal temperature had risen, the temperature was raised to 70°C and the mixture was aged for 3 hours to prepare a urethane isocyanate prepolymer. After confirming that the isocyanate group concentration in the reaction solution was below the theoretical value (2.27 wt%), 24.7 g of (meth)acrylate (C1) was added. The mixture was aged for another 2 hours to obtain urethane (meth)acrylate (X'-1). The acryloyl group concentration of the resulting urethane (meth)acrylate (X'-1) was 2,303 g / mol (0.43 mol / kg).

[0093] <Comparative synthesis example 2 / X'-2> The polyol (A'2), polyisocyanate (B1) and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.10. The actual amounts charged and reaction conditions are described below. A separable flask equipped with a thermometer and a stirrer was charged with 269.1 g of polyol (A'2), 22.6 g of polyisocyanate (B1), and 129 g of (meth)acrylate (Y1) as a diluent monomer. Furthermore, 800 ppm of dibutylhydroxytoluene (BHT) based on the reaction components excluding (meth)acrylate (Y1) was added. The internal temperature was raised to 50°C, and the mixture was stirred for 1 hour to homogenize the system. Then, a urethane catalyst (DBTDL) (300 ppm based on the reaction components excluding (meth)acrylate (Y1)) was added. After confirming that the internal temperature had risen, the temperature was raised to 70°C and the mixture was aged for 2 hours to prepare a urethane isocyanate prepolymer. After confirming that the isocyanate group concentration in the reaction solution was below the theoretical value (0.68 wt%), 8.3 g of (meth)acrylate (C1) was added. After further aging for 2 hours, urethane (meth)acrylate (X'-2) was obtained. The proportion of (meth)acrylate (Y1) in urethane (meth)acrylate (X'-2) was 30% by weight ((X'-2) / (Y1)=70 / 30). The acryloyl group concentration of the obtained urethane (meth)acrylate (X'-2) was 1,374 g / mol (0.73 mol / kg).

[0094] <Comparative synthesis example 3 / X'-3> The polyol (A'2), polyisocyanate (B1) and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.10. The actual amounts charged and reaction conditions are described below. A separable flask equipped with a thermometer and a stirrer was charged with 269.1 g of polyol (A'2), 22.6 g of polyisocyanate (B1), and 129 g of (meth)acrylate (Y2) as a diluent monomer. Furthermore, 800 ppm of dibutylhydroxytoluene (BHT) based on the reaction components excluding (meth)acrylate (Y2) was added. The internal temperature was raised to 50°C, and the mixture was stirred for 1 hour to homogenize the system. Then, a urethane catalyst (DBTDL) (300 ppm based on the reaction components excluding (meth)acrylate (Y2)) was added. After confirming that the internal temperature had risen, the temperature was raised to 70°C and the mixture was aged for 2 hours. After confirming that the isocyanate group concentration in the reaction solution was below the theoretical value (0.68 wt%), 8.3 g of (meth)acrylate (C1) was added. The mixture was aged for another 2 hours to obtain urethane (meth)acrylate (X'-3). The proportion of (meth)acrylate (Y2) in urethane (meth)acrylate (X'-3) was 30% by weight ((X'-3) / (Y2)=70 / 30). The acryloyl group concentration of the obtained urethane (meth)acrylate (X'-3) was 1,374 g / mol (0.73 mol / kg).

[0095] <Comparative synthesis example 4 / X'-4> The polyol (A'3), polyisocyanate (B1) and (meth)acrylate (C1) were reacted in a molar ratio of 2.0:3.0:2.10. The actual amounts charged and reaction conditions are described below. A separable flask equipped with a thermometer and a stirrer was charged with 103.9 g of polyisocyanate (B1), 800 ppm of dibutylhydroxytoluene (BHT) relative to the reaction components, and a urethane catalyst (DBTDL) (300 ppm relative to the reaction components). The internal temperature was raised to 50°C, and 308.2 g of polyol (A'3) was added dropwise over 4 hours. The reaction was continued while gradually heating with cooling water to prevent the internal temperature from exceeding 80°C. After the addition of polyol (A'3) was completed, the reaction solution was aged for 2 hours. After confirming that the isocyanate group concentration in the reaction solution was below the theoretical value (3.18 wt%), 38 g of (meth)acrylate (C1) was added. The reaction solution was aged for an additional 4 hours, yielding urethane (meth)acrylate (X'-4). The acryloyl group concentration of the obtained urethane (meth)acrylate (X'-4) was 4,209 g / mol (0.24 mol / kg).

[0096] The viscosity (60°C) and Mw of the urethane (meth)acrylate obtained in each synthesis example and comparative synthesis example were measured by the methods described above. A summary of each example is shown in Table 1.

[0097] [Table 1]

[0098] [Examples 1 to 8 and Comparative Examples 1 to 7] The urethane (meth)acrylate (X) obtained in each Synthesis Example and Comparative Synthesis Example was mixed with a (meth)acrylate (Y) as a viscosity-adjusting monomer until the viscosity of the curable composition at 25°C reached 600 mPa·s or less. Then, 3 wt% of a photopolymerization initiator (Z) was mixed with the resulting mixture, based on the total weight of the mixture, to obtain the curable composition of each example. Tables 2 and 3 show the blending ratios of the (X) and (Y) components. The viscosity of the curable composition obtained in each example was measured by the method described above. The appearance of the curable composition obtained in each example, and the transparency, heat resistance, and flexibility of the cured product were evaluated under the following conditions. The results are shown in Tables 2 and 3.

[0099] <Appearance Evaluation of Curable Composition> The curable composition obtained in each example was stored at −30° C. for 1 hour, and the presence or absence of cloudiness or coloration due to crystallization or the like was visually evaluated according to the following evaluation criteria. (Evaluation criteria: appearance) Pass: Neither cloudiness nor coloration was observed by visual inspection. Fail: Cloudiness and / or coloration was confirmed by visual inspection.

[0100] <Transparency evaluation of cured product> As shown in Fig. 1, a square frame (inner dimensions: 1.0 x 40 x 10 mm) was made of silicone rubber 12 on a micro glass sheet 11 (dimensions: 1.0 x 76 x 26 mm), and 1.0 g of curable composition 13 was dropped into the frame. The frame was then heated to 70°C, and once the surface became smooth, it was cured by irradiating it with ultraviolet light under the following conditions to obtain a test piece of the cured product. (Ultraviolet irradiation conditions) Irradiation intensity: 120W / cm Irradiation distance: 10cm Conveyor speed: 5m / min Number of irradiations: 2 times Next, the transmittance was measured using a spectrophotometer (manufactured by Shimadzu Corporation, product name "UV-VISIBLE SPECTROPHOTO METER") with the micro glass alone as a reference, and evaluated according to the following evaluation criteria. (Evaluation criteria: transparency) Pass: Transmittance at 400 nm was 95% or more. Fail: The transmittance at 400 nm was less than 95%.

[0101] <Evaluation of heat resistance of cured product> A laminate 20 as shown in Figures 2 and 3 was produced and evaluated for heat resistance. Figure 2 is a top view of the laminate 20 as seen from directly above, and Figure 3 is a side view of the laminate 20. First, 0.50 g (±0.01 g) of the curable composition was accurately weighed and dropped onto the center of a glass plate 21 (1 mm thick, 5 cm square). Another glass plate 21 of the same shape was placed over it, and the curable composition was spread in a circle (4 cm diameter), to obtain a laminate 20 in which the glass laminate 21 / curable composition 13 / glass laminate 21 were laminated in this order. Thereafter, ultraviolet light was irradiated from one side of the glass laminate 21 using a high-pressure mercury lamp (manufactured by Eye Graphics Co., Ltd.) under the following conditions to cure the curable composition 13. (Ultraviolet irradiation conditions) Irradiation intensity: 120W / cm Irradiation distance: 10cm Conveyor speed: 5m / min Number of irradiations: 8 times (4 times on each side) Next, the cured laminate 20 was stored in a small environmental test chamber (manufactured by Espec Corporation, product name "SH-641") for 1000 hours at a temperature of 95° C. The shape of the laminate 20 after storage was evaluated according to the following evaluation criteria. (Evaluation criteria: heat resistance) Pass: There was no change in the shape of the laminate 20 after storage. Failed: The shape of the laminate 20 was changed after storage (wrinkles were formed in the cured product and / or the glass plates were displaced).

[0102] <Flexibility evaluation of cured product> A square frame (inner dimensions: 7 × 40 × 40 mm) was made of silicone rubber on a glass plate, and the curable composition was poured into the frame so that the void volume was filled to the brim. The curable composition was preheated and poured slowly to minimize the generation of air bubbles. If air bubbles were present in the curable composition, it was stored in an oven at 80°C until the bubbles were removed. The sample was heated at 80°C, and once the surface became smooth, it was cured by irradiating it with ultraviolet light under the following conditions. (Ultraviolet irradiation conditions) Irradiation intensity: 120W / cm Irradiation distance: 10cm Conveyor speed: 3.5m / min Number of irradiations: 5 times After curing, the cured product was removed from the silicone rubber, turned upside down, and further irradiated with ultraviolet light under the same conditions as above. This resulted in a test piece of the cured product approximately 7 mm thick. Then, hardness measurements were performed in accordance with JIS K 6253 using an automatic constant pressure loader (manufactured by Teclock Corporation, product name "GS-610"). A Type A hardness tester was used. The load was 500 g, and the load drop rate was 9 mm / s. After unloading, the mark left by the indenter was observed and evaluated according to the following evaluation criteria. (Evaluation criteria: flexibility) Pass: There was no damage such as cracking at the contact point with the indenter, or there was damage such as cracking at the contact point with the indenter, but it recovered within 24 hours. Failed: There was a crack or other damage at the contact point with the indenter, and it did not recover within 24 hours.

[0103] [Table 2]

[0104] [Table 3]

[0105] As shown in Table 2, the curable compositions of Examples 1 to 8, which satisfied the configuration of the first embodiment, were able to obtain low-viscosity curable compositions with a small amount of monomer (component (Y)), and also had good appearance. Furthermore, the cured products obtained from the curable compositions were also excellent in transparency, heat resistance, and flexibility. On the other hand, as shown in Table 3, the curable compositions of Comparative Examples 1 to 4, which contained a urethane (meth)acrylate not containing a structural unit derived from farnesene, were able to prepare low-viscosity curable compositions with a relatively small amount of monomer (component (Y)), and the resulting compositions had good appearance, but the heat resistance or flexibility of the cured products was poor. Furthermore, the curable compositions of Comparative Examples 5 and 6 became cloudy and exhibited phase separation over time, making it impossible to measure the viscosity of the curable compositions or evaluate the cured products. Note that, as shown in Table 3, in Comparative Examples 5 and 6, when the blending amount of component (Y) was less than 30 wt %, the appearance was good, but the viscosity of the curable compositions was so high that neither viscosity measurement nor evaluation of the cured products could be performed. Furthermore, the curable composition of Comparative Example 7 containing only the urethane (meth)acrylate (X-1) and the photopolymerization initiator (Z) had a very high viscosity (25° C.) and was difficult to handle. From the above results, it was found that the curable composition according to the first embodiment is a low-viscosity active energy ray-curable composition, and can give a cured product that is excellent in transparency, flexibility, and heat resistance.

[0106] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure are set forth below. [1] A urethane (meth)acrylate (X) containing a structural unit derived from farnesene; a (meth)acrylate (Y) other than the urethane (meth)acrylate (X); and a photopolymerization initiator (Z). [2] The active energy ray-curable composition according to [1], wherein the urethane (meth)acrylate (X) is a reaction product of a polyol (A) containing a structural unit derived from farnesene, a polyisocyanate (B), and a (meth)acrylate having a hydroxyl group (C). [3] The active energy ray-curable composition according to [1] or [2], wherein the urethane (meth)acrylate (X) has a weight average molecular weight (Mw) of 5,000 to 30,000. [4] The urethane (meth)acrylate (X) is a reaction product of a polyol (A) containing a structural unit derived from farnesene, a polyisocyanate (B), and a (meth)acrylate having a hydroxyl group (C), The active energy ray-curable composition according to any one of [1] to [3], wherein the polyol (A) contains a diol represented by the following formula (I): [ka] (In formula (I), m and n each independently represent an integer of 1 to 7.) [5] A cured product of the active energy ray-curable composition according to any one of [1] to [4]. [6] A laminate comprising a layer containing one or more layers selected from the active energy ray-curable composition according to any one of [1] to [4] and the cured product according to [5]. [Explanation of symbols]

[0107] 11: Micro glass 12: Silicone rubber 13: Active energy ray curable composition 20: Laminate 21: Glass plate

Claims

1. a urethane (meth)acrylate (X) which is a reaction product of a polyol (A) containing a structural unit derived from farnesene, a polyisocyanate (B), and a (meth)acrylate (C) having a hydroxyl group, and which has a weight average molecular weight of more than 12,000 and not more than 30,000; one or more monofunctional (meth)acrylates (Y) selected from aliphatic (meth)acrylates and alicyclic (meth)acrylates having an alkyl group with 1 to 15 carbon atoms; and a photopolymerization initiator (Z), wherein the polyol (A) comprises a diol represented by the following formula (I) and having a weight average molecular weight of 1,000 or more and less than 2,000: 【Chemistry 1】 (In formula (I), m and n each independently represent an integer of 1 to 7.)

2. 2. The active energy ray-curable composition according to claim 1, wherein the monofunctional (meth)acrylate (Y) comprises one or more selected from n-octyl acrylate (NOA), isobornyl acrylate (IBOA), and octyl / decyl (meth)acrylate.

3. 3. The active energy ray-curable composition according to claim 1, wherein a proportion of the monofunctional (meth)acrylate (Y) relative to the total mass of the curable composition is 20 to 55 mass%.

4. A cured product of the active energy ray-curable composition according to claim 1.

5. A laminate comprising a layer containing one or more layers selected from the active energy ray-curable composition according to claim 1 and the cured product according to claim 4.

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