Photocurable resin composition, cured product, and laminate

Abstract

This invention provides a photocurable resin composition that yields a cured product with low reaction force over a wide range of compression ratios (compression range). The photocurable resin composition of this invention is characterized in that the reaction force of the cured product at 10% compression is 1–300 kPa, and the reaction force at 50% compression is 1–500 kPa. It contains a hollow organic resin filler as component (A) and does not contain monofunctional acrylic monomers with hydroxyl groups.

Description

Technical Field

[0001] This invention relates to photocurable resin compositions, cured products, and laminates. Background Technology

[0002] In recent years, laminated lithium-ion rechargeable batteries have been widely used as power sources for portable devices such as multifunctional portable phones and digital cameras, with the aim of miniaturization and weight reduction.

[0003] Japanese Patent Publication No. 2008-235170 discloses a laminated lithium-ion secondary battery. From the viewpoint of long-term reliability, a certain load is applied in the stacking direction to fix the batteries to each other so that they remain stationary. Summary of the Invention

[0004] The problem to be solved by the present invention

[0005] Japanese Patent Publication No. 2008-235170 discloses a structure for a laminated lithium-ion secondary battery in which a buffer material is sandwiched between the batteries to generate uniform surface pressure. However, when using conventional buffer materials, the following disadvantages exist: if the compression ratio is too high, the surface of the battery pack casing may deform due to the reaction force generated in the buffer material or the expansion of the battery itself.

[0006] The present invention was made in view of the above-described situation, and its object is to provide a photocurable resin composition in which a cured product with low reaction force can be obtained over a wide range of compression ratios (compression range). Another object of the present invention is to provide a cured product obtained by curing the above-described photocurable resin composition. Furthermore, yet another object of the present invention is to provide a laminate formed by bonding the above-described cured product to substrates.

[0007] Problem-solving methods

[0008] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that, according to the photocurable resin composition described in detail below, it is possible to obtain a cured product with low reaction force over a wide range of compression ratios (compression range), thereby completing the present invention.

[0009] In order to achieve at least one of the above objectives, the photocurable resin composition of one aspect of the present invention has a reaction force of 1 kPa to 300 kPa at 10% compression of the cured product and a reaction force of 1 kPa to 500 kPa at 50% compression of the cured product, contains a hollow organic resin filler as component (A), and does not contain monofunctional (meth)acrylic monomers having hydroxyl groups.

[0010] Furthermore, in order to achieve at least one of the above objectives, another aspect of the present invention provides a photocurable resin composition that does not contain a monofunctional (meth)acrylic acid monomer having hydroxyl groups, but contains a hollow organic resin filler as component (A), wherein the cured product of the photocurable resin composition has a reaction force of 1 kPa to 300 kPa at 10% compression and a reaction force of 1 kPa to 500 kPa at 50% compression. Detailed Implementation

[0011] The following describes embodiments of the present invention. However, this disclosure is not limited to these embodiments. In this specification, "X to Y" refers to a range including the values ​​(X and Y) described before and after it as a lower and upper limit value, respectively, meaning "above X and below Y". Furthermore, unless otherwise specified, concentration and % refer to mass concentration and mass percentage, respectively, and ratio refers to mass ratio unless otherwise specified. Additionally, unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20–25°C) and relative humidity 40–55% RH. Furthermore, "A and / or B" refers to each of A and B, and combinations thereof.

[0012] [Photocurable resin composition]

[0013] A photocurable resin composition (hereinafter also referred to as "photocurable resin composition" or simply "resin composition") of one aspect of the present invention is characterized in that the reaction force at 10% compression of the cured product is 1 to 300 kPa, the reaction force at 50% compression of the cured product is 1 to 500 kPa, the cured product contains a hollow organic resin filler (A) component as component (A), and does not contain monofunctional (meth)acrylic monomers having hydroxyl groups.

[0014] According to one aspect of the photocurable resin composition of the present invention, a cured product with low reaction force can be obtained at a wide range of compression ratios. That is, when the cured product obtained by using the photocurable resin composition is compressed at a wide range of compression ratios, the reaction force generated in the cured product can be reduced. Specifically, the cured product obtained by using the photocurable resin composition has a reaction force of 1 to 300 kPa at 10% compression and a reaction force of 1 to 500 kPa at 50% compression.

[0015] Thus, according to the photocurable resin composition of the present invention, when the cured product is compressed at a wide range of compression ratios, the reaction force generated in the cured product is small. Although the details of this mechanism are not clear, it is believed that this is because the hollow organic resin filler contained as component (A) is softer than, for example, glass fillers, and because it is a hollow body, it acts as a buffer material, thus reducing the reaction force generated when the cured product is compressed (especially when compressed at a high compression ratio). In addition, although the detailed mechanism is not yet clear, if a monofunctional (meth)acrylic acid monomer with hydroxyl groups is contained, the photocurability is reduced, and a good cured product cannot be obtained (see Comparative Examples 3 and 4 described later).

[0016] Furthermore, the above mechanism is based on speculation, and the correctness of the mechanism will not affect the technical scope of the present invention.

[0017] The photocurable resin composition according to the preferred embodiment of the present invention further comprises the following components (B) to (D);

[0018] (B) Ingredients: Monofunctional carbamate (meth)acrylate

[0019] (C) Components: Monofunctional (meth)acrylic acid monomers other than those in (B) above.

[0020] (D) Component: Photoradical polymerization initiator.

[0021] In addition, the photocurable resin composition of the preferred embodiment of the present invention further comprises a plasticizer without (meth)acryloyl groups as component (E).

[0022] Furthermore, the photocurable resin composition of the preferred embodiment of the present invention further contains a polyfunctional (meth)acrylic acid monomer with two or more functions as component (F).

[0023] The components contained in a photocurable resin composition according to one aspect of the present invention will be described below.

[0024] <Monofunctional (meth)acrylic acid monomers with hydroxyl groups>

[0025] The photocurable resin composition of the present invention does not contain monofunctional (meth)acrylic monomers having hydroxyl groups. This configuration improves the photocurability of the photocurable resin composition. On the other hand, when the photocurable resin composition contains monofunctional (meth)acrylic monomers having hydroxyl groups, photocuring cannot proceed sufficiently, making it impractical (see Comparative Examples 3 and 4 described below).

[0026] In addition, the composition does not contain monofunctional (meth)acrylic acid monomers with hydroxyl groups, which can be achieved by using... 1 HNMR and 13The determination is made using C NMR.

[0027] Furthermore, in this specification, "free from" an ingredient means "substantially free from" that ingredient, including the presence of the substance as the target by means of contaminants. Specifically, this means that the substance in question may be present in a proportion not exceeding 0.1% by weight (lower limit: 0% by weight) relative to the total weight of the composition.

[0028] In this specification, "(meth)acrylic monomers" refers to monomers having one or more (meth)acryloyl groups. Furthermore, the term "(meth)acryloyl" includes both acryloyl and methacryloyl. Therefore, for example, the term "(meth)acryloyl" includes both acryloyl (H₂C=CH⁻C(=O)⁻) and methacryloyl (H₂C=C(CH₃)⁻C(=O)⁻). Similarly, the term "(meth)acrylate" includes both acrylate and methacrylate, and the term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0029] Furthermore, "monofunctional (meth)acrylic acid monomers having hydroxyl groups" refers to monomers having one or more hydroxyl groups and one acryloyl group or one methacryloyl group. Examples of such monomers include 2-hydroxyethyl (meth)acrylic acid.

[0030] <(A)Component>

[0031] The photocurable resin composition contains component (A), which is a hollow resin filler (hollow organic resin filler). A hollow resin filler refers to a hollow body having a hollow portion, and is a particle formed from resin. By including component (A), the cured product obtained by curing the photocurable resin composition of the present invention exhibits low reaction force even when compressed at a wide range of compression ratios (especially high compression ratios). Furthermore, by combining component (A) with other components described below (preferably components (B) to (F)), not only can a cured product exhibiting the low reaction force described above be obtained, but the photocurable resin composition can also be rapidly cured by photocuring.

[0032] The shape of the hollow resin filler is not particularly limited and can be any shape such as spherical, needle-like, fibrous, or plate-like. However, from the viewpoint of not only reducing the reaction force during compression of the cured product but also easily and uniformly dispersing it in the resin composition, a spherical shape is preferred. Here, "spherical" refers to a shape with an aspect ratio of 1.0 to 2.0, preferably 1.0 to 1.5, and does not necessarily mean a perfect sphere. In addition, the aspect ratio of spherical filler refers to the length-to-diameter ratio.

[0033] The average particle size of the hollow resin filler as component (A) is not particularly limited, but is preferably 5 to 300 μm, more preferably 10 to 200 μm, even more preferably 50 to 150 μm, particularly preferably 60 to 130 μm, and most preferably 70 to 100 μm. Furthermore, the average particle size of component (A) can be determined using a particle size analyzer employing analytical methods such as laser diffraction. By ensuring that the average particle size of component (A) is within the above range, a cured product with low reaction force can be obtained over a wider range of compressibility ratios (compression range).

[0034] Component (A) is formed from resin (organic resin). There are no particular limitations on the resin constituting component (A), but thermoplastic resins are preferred, and polymers (homopolymers) of at least one monomer selected from the group consisting of vinylidene chloride, acrylonitrile, methacrylonitrile, acrylate, and methacrylate, or copolymers (copolymers) of two or more monomers selected from the above monomers, are more preferred. These resins can be used alone or in combination of two or more. From the viewpoint of the strength and toughness of the hollow resin filler, the resin constituting the hollow resin filler is preferably a polymer (polyacrylonitrile resin) or copolymer containing acrylonitrile as a constituent unit, more preferably a copolymer containing acrylonitrile as a constituent unit, and particularly preferably an acrylonitrile-methacrylonitrile-methyl methacrylate copolymer. That is, the hollow resin filler is preferably composed of an acrylonitrile-methacrylonitrile-methyl methacrylate copolymer.

[0035] From the viewpoint of easily integrating with other components such as components (B) to (F) described below, the hollow resin filler (component A) is preferably surface-treated. There are no particular limitations on the type of surface treatment; the hollow resin filler can be surface-treated using silane coupling agents, fatty acids, etc., or calcium carbonate can be deposited on its surface. Among these, component (A) is more preferably a hollow resin filler with calcium carbonate deposited on its surface. These types of surface treatments can be used individually or in combination.

[0036] Furthermore, there are no particular limitations on the true specific gravity of component (A), but it is preferably 0.03 to 0.50 g / cm³. 3 More preferably, it is 0.05–0.40 g / cm³. 3 The preferred value is 0.07–0.30 g / cm³. 3 The true specific gravity of component (A) can be determined according to JIS Z8807:2012. By keeping the true specific gravity of component (A) within the above range, a cured product with a wider range of compressibility (compression range) and lower reaction force can be obtained.

[0037] (A) The content of the component is not particularly limited, but is preferably 3 to 80 parts by mass relative to 100 parts by mass of the total mass of the photocurable resin composition, more preferably 5 to 50 parts by mass, particularly preferably 8 to 30 parts by mass, and most preferably 10 to 20 parts by mass.

[0038] Furthermore, there is no particular limitation on the content of component (A), but it is preferably 3 to 70 parts by mass relative to the total of 100 parts by mass of components (B) and (C) described later, more preferably 5 to 60 parts by mass, particularly preferably 10 to 50 parts by mass, and most preferably 20 to 30 parts by mass.

[0039] The hollow resin filler used as component (A) can be either synthetic or commercially available. Examples of commercially available products used as component (A) include EMC-40B, EMC-80B, and EMC-120α (manufactured by Fillite Co., Ltd., Japan).

[0040] The hollow resin filler used as component (A) above can be used alone or in combination with two or more types. Furthermore, when two or more types are used in combination, the content of component (A) refers to the total amount.

[0041] <(B) Ingredients>

[0042] The photocurable resin composition of the present invention preferably contains a monofunctional urethane (meth)acrylate as component (B). By combining component (B) with component (A), the reaction forces generated in the cured product can be further reduced even when the cured product is compressed at a wide range of compression rates (compression range).

[0043] Here, urethane (meth)acrylate refers to an ester compound having an urethane bond formed by reacting an isocyanate group with a hydroxyl group and a (meth)acryloyl group. That is, urethane (meth)acrylate refers to a (meth)acrylate having an urethane bond. In the monofunctional urethane (meth)acrylate as component (B), the number of urethane bonds is one or more per molecule, and the number of (meth)acryloyl groups is one per molecule. Furthermore, the (meth)acryloyl group can also be included in the compound in the form of (meth)acryloyloxy group. When using urethane (meth)acrylate having two or more (meth)acryloyl groups, the reaction force of the cured product of the photocurable resin composition becomes higher, which is not preferred. In addition, from the viewpoint of reducing the compression set of the obtained cured product, the (meth)acryloyl group contained in component (B) is preferably an acryloyl group. Here, "low compression set" of a certain material means that the material has a high recovery force when compressed for a long time. This property is important when the photocurable resin composition (and its cured product) of the present invention is used as a buffer material for laminated lithium-ion secondary batteries. Since the acryloyl group has a higher reactivity than the methacryloyl group, it is assumed that the (meth)acryloyl group contained in component (B) is an acryloyl group, resulting in a smaller compression set as described above.

[0044] To enhance the desired effect, the monofunctional urethane (meth)acrylate as component (B) is preferably a monofunctional urethane (meth)acrylate oligomer. In this specification, "oligomer" refers to a polymer in which monomer units (including monomer units other than (meth)acrylate monomers) are repeated 2 to several tens, and the weight-average molecular weight is 1000 (0.1 million) or more.

[0045] The monofunctional urethane (meth)acrylate as component (B) may contain structures other than urethane bonds and (meth)acryloyl groups, such as polyester backbones, polycaprolactone backbones, polycarbonate backbones, polyether backbones, etc. One of these backbones may be present in one molecule, or two or more may be present in combination. From the viewpoint of further enhancing the desired effect, component (B) preferably has a polyether backbone. It should be noted that, in this specification, "polyether backbone" refers to a backbone having, for example, epoxides such as polyethylene oxide, polypropylene oxide, or polybutane oxide as repeating units.

[0046] From the viewpoint of further improving the desired effect, component (B) is preferably a monofunctional urethane (meth)acrylate oligomer with a polyether backbone (polyether-based monofunctional urethane (meth)acrylate oligomer), and more preferably a monofunctional urethane acrylate oligomer with a polyether backbone.

[0047] On the other hand, from the viewpoint of photocurability, component (B) is preferably a monofunctional urethane (meth) acrylate that does not have hydroxyl groups.

[0048] The monofunctional urethane (meth)acrylate (monofunctional urethane (meth)acrylate oligomer) as component (B) can be either synthetic or commercially available.

[0049] There are no particular limitations on the manufacturing method of component (B). For example, methods such as reacting a polyol compound having hydroxyl groups with a (meth)acrylate having isocyanate groups, or reacting a polyol compound having hydroxyl groups, a polyisocyanate compound, and a (meth)acrylate having hydroxyl groups are given. These reactions are preferably carried out in the presence of a catalyst.

[0050] There are no particular limitations on the aforementioned polyol compounds containing hydroxyl groups, and examples include polyester polyols, polycarbonate polyols, and polyether polyols such as polyethylene oxide, polypropylene oxide, and polybutane glycol. There are no particular limitations on the number of repeating units of the epoxide contained in the polyether polyol, for example, it is 3 to 500, more preferably 5 to 100, and particularly preferably 10 to 50.

[0051] There are no particular limitations on the (meth)acrylates having the isocyanate group, for example, ethyl (meth)acrylate 2-isocyanate and 2-(2-(meth)acryloyloxyethoxy)ethyl isocyanate can be listed.

[0052] There are no particular limitations on the aforementioned polyisocyanate compounds; examples include aromatic polyisocyanates such as 2,4-methylphenylene diisocyanate, 2,6-methylphenylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, tetramethylxylene diisocyanate, diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, and triphenylmethane triisocyanate; isoflavones... Alicyclic polyisocyanates such as ketone diisocyanate, bis(4-isocyanatocyclohexyl)methane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, norcamphene diisocyanate, and dicycloheptane triisocyanate; and straight-chain or branched aliphatic polyisocyanates such as hexamethylene diisocyanate, 1,3,6-hexamethylene triisocyanate, and 1,6,11-undecane triisocyanate. From the viewpoint of obtaining a flexible cured product, the aforementioned polyisocyanate compounds are preferably selected from straight-chain or branched aliphatic polyisocyanates and alicyclic polyisocyanates. These can be used alone or in combination.

[0053] There are no particular limitations on the hydroxyl-containing (meth)acrylates mentioned above, and examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, neopentyl glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, etc. From the viewpoint of obtaining a cured product with excellent flexibility, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxycyclohexyl (meth)acrylate are preferred. These can be used alone or in combination.

[0054] Furthermore, catalysts used in the synthesis of component (B) include, for example, lead oleate, antimony trichloride, triphenylaluminum, trioctylaluminum, tetrabutyltin, dibutyltin dilaurate, copper naphthenate, zinc naphthenate, zinc octanoate, zinc octenate, zirconium naphthenate, cobalt naphthenate, tetra-n-butyl-1,3-diacetoxydistanoxane, triethylamine, 1,4-diaza[2,2,2]bicyclooctane, and N-ethylmorpholine. Among these, dibutyltin dilaurate, zinc naphthenate, zinc octanoate, and zinc octenate are preferred from the perspective of rapid curing even with low cumulative light intensity to obtain a cured product with low elasticity. The amount of these catalysts added is preferably 0.0001 to 10 parts by mass relative to 100 parts by mass of the total reactants. Furthermore, the reaction temperature is typically 10 to 100°C, and is particularly preferably carried out at 30 to 90°C.

[0055] (B) The weight-average molecular weight is not particularly limited. However, considering the ability to rapidly obtain a cured product by photocuring and to obtain a cured product with low reaction force over a wide range of compressibility (compression range), the weight-average molecular weight of (B) is preferably, for example, 0.1 million to 300,000 (1,000 or more and 300,000 or less), more preferably 0.3 million to 50,000 (3,000 or more and 50,000 or less), and particularly preferably 0.5 million to 40,000 (5,000 or more and 40,000 or less). Furthermore, in this specification, unless otherwise specified, the weight-average molecular weight is the value calculated using the standard polystyrene conversion method obtained by size exclusion chromatography (SEC).

[0056] The content of component (B) is not particularly limited, but is preferably 20 to 90 parts by mass relative to the total of component (B) and component (C) described later, 100 parts by mass; more preferably 30 to 85 parts by mass; even more preferably 40 to 80 parts by mass; particularly preferably 50 to 75 parts by mass; and most preferably 60 to 70 parts by mass. Within the above ranges, a photocurable resin composition can be obtained that can be further rapidly cured by light curing and that exhibits low reaction force over a wide range of compression ratios (compression ranges).

[0057] The monofunctional urethane (meth)acrylates used as component (B) above can be used alone or in combination with two or more. Furthermore, when two or more are used in combination, the content of component (B) refers to the total amount.

[0058] <(C) Ingredients>

[0059] The photocurable resin composition of the present invention preferably contains a monofunctional (meth)acrylic monomer other than component (B) as component (C). By combining component (C) with component (A), a cured product can be rapidly obtained by photocuring, and a cured product with low reaction force over a wide range of compression ratios (compression range) can be obtained.

[0060] Here, monofunctional (meth)acrylic acid monomers refer to compounds having one (meth)acryloyl group. The (meth)acryloyl group may also be included in the monomer in the form of (meth)acryloyloxy group. In addition, compounds having one or more carbamate bonds and one (meth)acryloyl group per molecule (wherein, ester compounds) are included in component (B) above, but not in component (C).

[0061] Furthermore, for the purpose of good photocurability, the (meth)acryloyl group contained in component (C) is preferably an acryloyl group. In addition, such a configuration also has the advantages of higher reaction rate and lower compression set of the cured product.

[0062] To enhance the desired effect, the monofunctional (meth)acrylic monomer as component (C) is preferably a monofunctional (meth)acrylate monomer (i.e., an ester compound having one (meth)acryloyloxy group, a (meth)acrylate).

[0063] Component (C) may also contain structures other than (meth)acryloyl groups. From the viewpoint of further enhancing the desired effect, component (C) preferably has a polyether backbone. The definition of "polyether backbone" is as described in component (B) above. The number of repeating units of the epoxide constituting the polyether backbone is not particularly limited, for example, 2 to 300, preferably 2 to 100, more preferably 2 to 30, and particularly preferably 2 to 10. Furthermore, the number of carbon atoms constituting the olefinic oxygen is not particularly limited, but the number of carbon atoms in one repeating unit is preferably 2 to 10, more preferably 2 to 5, particularly preferably 2 to 4, and most preferably 2. That is, the polyether backbone contained in component (C) is preferably a polyethylene oxide backbone.

[0064] The molecular weight of component (C) is not particularly limited, but from the viewpoint of ensuring good curability of the photocurable resin composition, it is preferably less than 1000, more preferably 500 or less, and particularly preferably 300 or less. Furthermore, from the viewpoint of excellent compatibility with component (B), the molecular weight of the compound of component (C) is preferably greater than 100, more preferably 130 or more. In addition, in this specification, the molecular weight of the compound (low molecular weight compound) can be determined by known methods such as gas chromatography-mass spectrometry (GC-MS). Alternatively, if this method is not feasible, the structure of the compound can be determined by methods such as NMR, and the molecular weight can be determined based on that structure.

[0065] On the other hand, from the viewpoint of photocurability, component (C) is preferably a monofunctional (meth)acrylic monomer without hydroxyl groups, more preferably a monofunctional (meth)acrylate monomer without hydroxyl groups, and particularly preferably a monofunctional acrylate monomer without hydroxyl groups.

[0066] As component (C), there are no particular restrictions, including methoxydiethylene glycol mono(meth)acrylate, methoxytriethylene glycol mono(meth)acrylate, methoxytetraethylene glycol mono(meth)acrylate, methoxypentethylene glycol mono(meth)acrylate, methoxyhexaethylene glycol mono(meth)acrylate, methoxyheptaethylene glycol mono(meth)acrylate, methoxyoctaethylene glycol mono(meth)acrylate, methoxyoctaethylene glycol mono(meth)acrylate, methoxynonethylene glycol mono(meth)acrylate, methoxydeethylene glycol mono(meth)acrylate, methoxytripropylene glycol mono(meth)acrylate, methoxytetrapropylene glycol mono(meth)acrylate, methoxypentethylene glycol mono(meth)acrylate, methoxyhexapropylene glycol mono(meth)acrylate, etc. Methoxy-7-propanediol mono(meth)acrylate, methoxy-8-propanediol mono(meth)acrylate, methoxy-8-propanediol mono(meth)acrylate, methoxy-9-propanediol mono(meth)acrylate, methoxy-10-propanediol mono(meth)acrylate, methoxy-10-propanediol mono(meth)acrylate, methoxy-10-but ... Ethoxydiethylene glycol mono(meth)acrylate, ethoxytriethylene glycol mono(meth)acrylate, ethoxytetraethylene glycol mono(meth)acrylate, ethoxypentaethylene glycol mono(meth)acrylate, ethoxyhexaethylene glycol mono(meth)acrylate, ethoxyheptaethylene glycol mono(meth)acrylate, ethoxyoctaethylene glycol mono(meth)acrylate, ethoxyoctaethylene glycol mono(meth)acrylate, ethoxynonethylene glycol mono(meth)acrylate, ethoxydeethylene glycol mono(meth)acrylate, ethoxytripropylene glycol mono(meth)acrylate, ethoxytetrapropylene glycol mono(meth)acrylate, ethoxypentapropylene glycol mono(meth)acrylate, ethoxyhexapropylene glycol mono(meth)acrylate Ester, ethoxyheptapropylene glycol mono(meth)acrylate, ethoxyoctapropylene glycol mono(meth)acrylate, ethoxyoctapropylene glycol mono(meth)acrylate, ethoxynonpropylene glycol mono(meth)acrylate, ethoxydepropanediol mono(meth)acrylate, ethoxytributylene glycol mono(meth)acrylate, ethoxytetrabutylene glycol mono(meth)acrylate, ethoxypentabutylene glycol mono(meth)acrylate, ethoxyhexabutylene glycol mono(meth)acrylate, ethoxyheptabutylene glycol mono(meth)acrylate, ethoxyoctabutylene glycol mono(meth)acrylate, ethoxyoctabutylene glycol mono(meth)acrylate, ethoxynonbutanediol mono(meth)acrylate, ethoxydebutanediol mono(meth)acrylate, etc.Among them, the preferred esters are ethoxydiethylene glycol mono(meth)acrylate, ethoxytriethylene glycol mono(meth)acrylate, ethoxytetraethylene glycol mono(meth)acrylate, ethoxypentethylene glycol mono(meth)acrylate, ethoxyhexaethylene glycol mono(meth)acrylate, ethoxyheptaethylene glycol mono(meth)acrylate, ethoxyoctaethylene glycol mono(meth)acrylate, ethoxyoctaethylene glycol mono(meth)acrylate, ethoxynonethylene glycol mono(meth)acrylate, ethoxydeethylene glycol mono(meth)acrylate, ethoxytripropylene glycol mono(meth)acrylate, ethoxytetrapropylene glycol mono(meth)acrylate, ethoxypentethylene glycol mono(meth)acrylate, and ethoxyhexapropylene glycol mono(meth)acrylate. Esters, including ethoxyheptapropylene glycol mono(meth)acrylate, ethoxyoctanepropylene glycol mono(meth)acrylate, ethoxyoctanepropylene glycol mono(meth)acrylate, ethoxynonpropylene glycol mono(meth)acrylate, ethoxydepropanepropylene glycol mono(meth)acrylate, ethoxytributylene glycol mono(meth)acrylate, ethoxytetrabutylene glycol mono(meth)acrylate, ethoxypentabutylene glycol mono(meth)acrylate, ethoxyhexabutylene glycol mono(meth)acrylate, ethoxyheptabutylene glycol mono(meth)acrylate, ethoxyoctanepropylene glycol mono(meth)acrylate, ethoxyoctanepropylene glycol mono(meth)acrylate, ethoxynonbutanepropylene glycol mono(meth)acrylate, and ethoxydebutanepropylene glycol mono(meth)acrylate. These can be used alone or in combination of two or more.

[0067] The content of component (C) is not particularly limited, but is preferably in the range of 10 to 80 parts by mass relative to the total of 100 parts by mass of components (B) and (C), more preferably 20 to 70 parts by mass, even more preferably 25 to 60 parts by mass, and particularly preferably 30 to 50 parts by mass. Within the above range, a photocurable resin composition can be obtained that can be further rapidly cured by light curing and can obtain a cured product with low reaction force over a wide range of compression ratios (compression range).

[0068] The content (total) of components (B) and (C) is not particularly limited, but is preferably 30 to 90 parts by mass relative to 100 parts by mass of the total mass of the photocurable resin composition, more preferably 40 to 80 parts by mass, and particularly preferably 50 to 70 parts by mass.

[0069] The monofunctional (meth)acrylate monomers used as component (C) above can be used alone or in combination with two or more. Furthermore, when two or more are used in combination, the content of component (C) refers to the total amount.

[0070] <(D) Ingredients>

[0071] The photocurable resin composition of the present invention preferably contains a photoradical polymerization initiator as component (D). As component (D), a compound that generates free radicals upon irradiation by active energy lines such as visible light, ultraviolet light, or electron beams can be used. Examples of such photoradical polymerization initiators include acetophenone-based photoradical polymerization initiators, benzoin-based photoradical polymerization initiators, thioxanone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, and titanium oxide-based photoradical polymerization initiators. Since a photocurable resin composition with a fast curing speed even with low cumulative light intensity can be obtained, component (D) is preferably an acetophenone-based photoradical polymerization initiator and / or an acylphosphine oxide-based photoradical polymerization initiator, more preferably an acetophenone-based photoradical polymerization initiator. These can be used alone or in combination of two or more.

[0072] Examples of acetophenone-based photoradical polymerization initiators include, but are not limited to, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoylayldimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)one, 1-hydroxy-cyclohexyl-phenyl-one, 2-methyl-2-morpholino(4-thiomethylphenyl)propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone oligomers. Commercially available products that serve as acetophenone-based photoradical polymerization initiators include Omnirad 184 (registered trademark, hereinafter the same), Omnirad 1173, Omnirad 2959, Omnirad 127 (manufactured by IGM Resins BV) and ESACURE KIP-150 (registered trademark, hereinafter the same) (manufactured by IGM Resins B.V.).

[0073] Examples of acylphosphine oxide-based photoradical polymerization initiators include, but are not limited to, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Commercially available acylphosphine oxide-based photoradical polymerization initiators include Omnirad TPO, Omnirad 819, and Omnirad 819DW (manufactured by IGM Resins BV).

[0074] The content of component (D) is not particularly limited, but is preferably 0.1 to 15 parts by weight, more preferably 0.3 to 7.0 parts by weight, particularly preferably 0.5 to 5.0 parts by weight, and most preferably 1.0 to 3.0 parts by weight, relative to a total of 100 parts by weight of components (B) and (C) above. Within the above range, a photocurable resin composition in which a cured material with low reaction force can be obtained with a wider range of compression ratios (compression range) can be obtained.

[0075] The photoradical polymerization initiator used as component (D) above can be used alone or in combination with two or more. Furthermore, when two or more are used in combination, the content of component (D) refers to the total amount.

[0076] <(E) Components>

[0077] The photocurable resin composition of the present invention preferably contains a plasticizer without a (meth)acrylyl group as component (E). By using a plasticizer without a (meth)acrylyl group, the following effect can be obtained: the reaction force generated in the obtained cured product is reduced over a wide range of compression ratios (compression range). By combining component (E) with component (A), a photocurable resin composition can be obtained that can be rapidly cured by light curing and that produces a cured product with low reaction force over a wide range of compression ratios (compression range).

[0078] As a plasticizer in component (E), it is preferable to have a polyether backbone to improve the desired effect. The definition of "polyether backbone" is as described in component (B) above. There is no particular limitation on the number of carbon atoms constituting the olefinic oxygen, but the number of carbon atoms in a repeating unit is preferably 2 to 10, more preferably 2 to 5, particularly preferably 2 to 4, and most preferably 3. That is, the polyether backbone contained in component (E) is preferably a polyoxypropylene backbone.

[0079] The number of repeating units of the epoxide constituting the polyether backbone is not particularly limited, for example, 3 to 300, more preferably 5 to 100, particularly preferably 10 to 60, and most preferably 20 to 50.

[0080] The number-average molecular weight of component (E) is not particularly limited, but is, for example, 200 to 30,000, preferably 350 to 10,000, particularly preferably 500 to 5,000, and most preferably 1,000 to 3,000. Furthermore, in this specification, unless otherwise specified, the number-average molecular weight is the value calculated using the standard polystyrene conversion method by size exclusion chromatography (SEC). Within the above ranges, it is possible to obtain a photocurable resin composition that can be further rapidly cured by light curing and that exhibits low reaction force over a wide range of compression ratios (compression ranges).

[0081] Examples of plasticizers that can be used as component (E) include polyols and their condensates, such as glycerol, diglycerol, triglyceride, ethylene glycol, propylene glycol, polyethylene glycol, etc.

[0082] The plasticizer used as component (E) can be either synthetic or commercially available. There are no particular restrictions on commercially available products used as component (E), and examples include PEG#300, PEG#400, PEG#600, PEG#1000, PEG#1500, PEG#15400, PEG#2000, PEG#4000, PEG#6000, PEG#1100, PEG#2000, UNIOL (registered trademark) D-700, D-1000, D1200, D2000, D4000, PB-500, PB-700, PB-1000, PB-2000 (manufactured by Nippon Oil Co., Ltd.), etc.

[0083] The content of component (E) is not particularly limited, but is preferably 20 to 200 parts by mass relative to the total of 100 parts by mass of components (B) and (C), more preferably 25 to 150 parts by mass, particularly preferably 30 to 100 parts by mass, and most preferably 35 to 70 parts by mass. Within the above range, a photocurable resin composition can be obtained that can be further rapidly cured by light curing and can produce a cured product with low reaction force over a wide range of compression ratios (compression range).

[0084] The plasticizer used as component (E) above can be used alone or in combination with two or more. Furthermore, when two or more are used in combination, the content of component (E) refers to the total amount.

[0085] <(F)Component>

[0086] The photocurable resin composition of the present invention preferably contains a polyfunctional (meth)acrylic acid monomer with two or more functions as component (F). By combining component (F) with component (A), a photocurable resin composition can be obtained that can be rapidly cured by photocuring and has low reaction force over a wide range of compression ratios (compression range).

[0087] Here, polyfunctional (meth)acrylic acid monomers refer to compounds having two or more (meth)acryloyl groups. The (meth)acryloyl group can also be included in the monomer in the form of (meth)acryloyloxy group.

[0088] There is no particular limitation on the number of (meth)acryloyl groups contained in the multifunctional (meth)acrylic acid monomer of component (F). From the viewpoint of obtaining a photocurable resin composition with fast curing speed even with low cumulative light intensity, it is preferable to have 3 or more (3 functional groups or more), more preferably 4 or more (4 functional groups or more), and particularly preferably 5 or more (5 functional groups or more). On the other hand, there is no particular limitation on the upper limit of the number of (meth)acryloyl groups, for example, it is 8 or less (8 functional groups or less). In addition, for the purpose of good photocurability and low compression set of the resulting cured product, it is preferable that the (meth)acryloyl groups contained in component (F) are acryloyl groups.

[0089] As the polyfunctional (meth)acrylate monomer of component (F), in order to improve the desired effect, a polyfunctional (meth)acrylate monomer (i.e., an ester compound having two or more (meth)acryloyl groups, (meth)acrylate) is preferred. Furthermore, the preferred number of (meth)acryloyl groups contained in the polyfunctional (meth)acrylate monomer is the same as described above.

[0090] The molecular weight of component (F) is not particularly limited, but from the viewpoint of ensuring good curability of the photocurable resin composition, it is preferably less than 1000, and more preferably 600 or less. In addition, from the viewpoint of excellent compatibility with component (A), the molecular weight of the compound of component (F) is preferably more than 200, and more preferably 300 or more.

[0091] On the other hand, from the viewpoint of photocurability, component (F) is preferably a polyfunctional (meth)acrylate monomer without hydroxyl groups, more preferably a polyfunctional (meth)acrylate monomer without hydroxyl groups, and particularly preferably a polyfunctional (meth)acrylate monomer without hydroxyl groups.

[0092] (F) There are no particular limitations on the components. Examples include tetrafunctional (meth)acrylate monomers such as dimethylolpropane tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; pentafunctional (meth)acrylate monomers such as dipentaerythritol monohydroxypenta(meth)acrylate and alkyl-modified dipentaerythritol penta(meth)acrylate; and hexafunctional (meth)acrylate monomers such as dipentaerythritol hexa(meth)acrylate. Among these, dipentaerythritol monohydroxypenta(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate are preferred. These monomers can be used alone or in combination of two or more.

[0093] The content of component (F) is not particularly limited, but is preferably in the range of 0.1 to 15 parts by mass relative to the total of 100 parts by mass of components (B) and (C), more preferably in the range of 0.2 to 5 parts by mass, and particularly preferably in the range of 0.3 to 3 parts by mass. Within the above range, a photocurable resin composition can be obtained that can be further rapidly cured by light curing and has low reaction force over a wide range of compression ratios (compression range).

[0094] The polyfunctional (meth)acrylic acid monomers used as component (F) above can be used alone or in combination with two or more. Furthermore, when two or more are used in combination, the content of component (F) refers to the total amount.

[0095] <(G) component>

[0096] The photocurable resin composition of the present invention preferably contains an inorganic filler as component (G). Component (G) is not particularly limited, and examples include glass, calcined silica, alumina, talc, mica, ceramics, silicone powder, calcium carbonate, aluminum hydroxide, aluminum nitride, carbon powder, kaolin, dried clay minerals, dried diatomaceous earth, etc. Among these, calcined silica and talc are preferred from the perspective of obtaining a photocurable resin composition that produces a cured product with low reaction force over a wide range of compression ratios (compression range). These can be used alone or in combination of two or more.

[0097] From the aim of obtaining a photocurable resin composition that produces a cured product with low reaction force over a wide range of compressibility (compression range), the aforementioned calcined silica is preferably calcined silica that has undergone hydrophobic treatment using at least one surface treatment agent selected from organochlorosilanes, dimethylsiloxanes, and hexamethyldisilazanes. Specific examples of silica include Aerosil (registered trademark) R974, R972, R972V, R972CF, R805, R812, R812S, R816, R8200, RY200, RX200, RY200S, and R202 (manufactured by Aerosil Japan). These can be used alone or in combination of two or more.

[0098] The content of component (G) is not particularly limited, but is preferably in the range of 0.01 to 100 parts by mass relative to the total of components (B) and (C) above 100 parts by mass, more preferably 0.1 to 50 parts by mass, particularly preferably 0.5 to 20 parts by mass, and particularly preferably 3 to 10 parts by mass. Within the above range, a photocurable resin composition in which a cured material with low reaction force in a wider range of compression ratios (compression range) can be obtained.

[0099] The inorganic filler material used as component (G) above can be used alone or in combination with two or more. Furthermore, when two or more are used in combination, the content of component (G) refers to the total amount.

[0100] <Optional Ingredients>

[0101] The photocurable resin composition of the present invention may contain, without prejudice to the purpose of the present invention, epoxy-modified (meth)acrylate oligomers (excluding monofunctional (meth)acrylate oligomers having urethane bonds), polyfunctional (two or more functional) urethane-modified (meth)acrylate oligomers; various elastomers such as styrene copolymers; organic peroxides; polythiols; silane coupling agents such as silane compounds having (meth)acryloyl groups; preservation stabilizers; antioxidants; light stabilizers; rust inhibitors; solvents; pigments; dyes; flame retardants; and may also contain additives such as tackifiers and surfactants.

[0102] <Manufacturing Method of Photocurable Resins>

[0103] The photocurable resin composition of the present invention can be manufactured by conventionally known methods. For example, a predetermined amount of component (A) and other optional components are weighed and mixed using a mixing apparatus such as a planetary mixer, thereby obtaining the photocurable resin composition of the present invention. There are no particular limitations on the manufacturing conditions, but it is preferable to carry out the process under light-shielding conditions to suppress viscosity increases. Furthermore, there are no particular limitations on the mixing conditions, but the mixing temperature is preferably 10–70°C, more preferably 20–50°C, and particularly preferably room temperature (25°C), and the mixing time is preferably 0.1–5 hours, more preferably 30 minutes to 3 hours, and particularly preferably about 60 minutes.

[0104] [cured material]

[0105] Another aspect of the present invention is a cured product (cured product of the photocurable resin composition) obtained by curing the above-mentioned photocurable resin composition. As described in detail below, the cured product is preferably obtained by irradiating the above-mentioned photocurable resin composition with light (e.g., active energy rays such as ultraviolet light or visible light). More specifically, the cured product according to one aspect of the present invention is preferably obtained by applying the above-mentioned photocurable resin composition to an adherend and then irradiating the applied photocurable resin composition with light.

[0106] <Coating Method>

[0107] There are no particular limitations on the method for applying the photocurable resin composition of the present invention to a substrate or other adherend. Known adhesives and coating methods can be used. For example, methods such as dispensing using an automatic coating machine, spraying, inkjet printing, screen printing, gravure printing, dipping, spin coating, etc., can be used.

[0108] In addition, there are no particular restrictions on the coating thickness, but it is preferable to adjust the film thickness after drying to be 0.1 to 5 mm, and more preferably 0.5 to 3 mm.

[0109] <Curing Method>

[0110] The photocurable resin composition of the present invention can be cured by irradiation with light (e.g., active energy rays such as ultraviolet light and visible light). The light referred to here is a broad term including various active energy rays such as radiation such as alpha or beta rays, electromagnetic waves such as gamma or X-rays, electron beams (EB), ultraviolet light with a wavelength of about 100 to 400 nm, and visible light with a wavelength of about 400 to 800 nm.

[0111] The light source used to cure the photocurable resin composition is not particularly limited, and examples include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, black lights, microwave-excited mercury lamps, metal halide lamps, sodium lamps, halogen lamps, xenon lamps, LEDs, fluorescent lamps, sunlight, and electron beam irradiation devices. Furthermore, as an apparatus for curing the photocurable resin composition of the present invention by light irradiation (active energy ray irradiation), an irradiation device having the above-mentioned light sources (high-pressure mercury lamps, LEDs, etc.) can be used. Specific examples of such an apparatus include belt conveyor type irradiators and spot irradiators, but it is not limited to these. In addition, there is no particular limitation on the lower limit of the cumulative light intensity, but 0.5 kJ / m² is preferred. 2 The above, more preferably 1.0 kJ / m 2 That's all. Thus, the photocurable resin composition of the present invention can cure sufficiently even with a low cumulative light intensity, and the resulting cured product exhibits excellent properties. Furthermore, there is no particular limitation on the upper limit of the cumulative light intensity, but 50 kJ / m² is preferred. 2 The following is more preferably 30 kJ / m 2 the following.

[0112] Regarding the reaction force during compression of the cured material of the present invention, the reaction force at 10% compression is 1 to 300 kPa, and the reaction force at 50% compression is 1 to 500 kPa. Furthermore, in this specification, "reaction force at 10% compression" refers to the reaction force when the cured material is compressed to a thickness of 90% relative to its initial thickness. Similarly, "reaction force at 50% compression" refers to the reaction force when the cured material is compressed to a thickness of 50% relative to its initial thickness. Regarding the method for measuring the reaction force, specifically, it follows the method described in the following section on "Reaction Force During Compression of Cured Material".

[0113] Furthermore, the cured product of the photocurable resin composition of the present invention has the advantage of low reaction force even when compressed at a high compression ratio. Specifically, the reaction force at 10% compression is preferably 2 to 250 kPa, more preferably 2 to 100 kPa, particularly preferably 2 to 50 kPa, and most preferably 2 to 10 kPa. Additionally, the reaction force at 50% compression is preferably 2 to 400 kPa, more preferably 50 to 400 kPa, particularly preferably 110 to 400 kPa, and most preferably 120 to 380 kPa. Moreover, it is preferable that the reaction force at 10% compression and the reaction force at 50% compression are both within any combination of the above ranges.

[0114] (Preferred composition of the photocurable resin composition)

[0115] In order to obtain a cured product that generates the above-mentioned reaction force, the photocurable resin composition of the present invention preferably has the following composition.

[0116] That is, the photocurable resin composition of the present invention is a photocurable resin composition containing a hollow organic resin filler as component (A) but not containing a monofunctional (meth)acrylic acid monomer having hydroxyl groups, and preferably also contains components (B) to (E) as described above. Furthermore, components (B), (C), and (E) are preferably compounds containing a polyether backbone. Additionally, the polyether backbones contained in components (B), (C), and (E) can be all the same or different. Furthermore, the preferred contents of components (A) to (E) in the above embodiment can be selected and combined by referring to the content ranges described in the descriptions related to each component.

[0117] Furthermore, in order to obtain a cured product that generates the aforementioned reaction force, the photocurable resin composition of the present invention does not contain monofunctional (meth)acrylic acid monomers having hydroxyl groups, but is a photocurable resin composition containing hollow organic resin filler as component (A), and preferably also contains components (B) to (F). Moreover, in this case, components (B), (C), and (F) preferably have acryloyl groups. By forming such a configuration, compared with the case where one or more of components (B), (C), and (F) contain compounds having methacryloyl groups, it is possible to obtain the effect of improved photocurability of the resin composition and reduced compression set of the resulting cured product. In addition, the preferred contents of components (A) to (F) in the above embodiment can be selected and combined by referring to the content ranges described in the description related to each component.

[0118] Furthermore, in order to obtain a cured product that generates the aforementioned reaction force, the photocurable resin composition of the present invention preferably does not contain monofunctional (meth)acrylic acid monomers with hydroxyl groups, but is composed of the aforementioned components (A) to (G). Additionally, "composed of the aforementioned components (A) to (G)" means "substantially composed only of the aforementioned components (A) to (G)," allowing for the inclusion of impurities of 1% by mass or less. Furthermore, the preferred contents of the aforementioned components (A) to (G) in the above-described manner are respectively referred to the content ranges described in the descriptions related to each of the aforementioned components, and these preferred ranges can be selected and combined.

[0119] Furthermore, in order to obtain a cured product that generates the aforementioned reaction force, the photocurable resin composition of the present invention does not contain monofunctional (meth)acrylic monomers with hydroxyl groups, but contains a hollow organic resin filler as component (A). The content of the hydroxyl-containing compound is preferably less than 7.6 parts by mass relative to 100 parts by mass of the total mass of the photocurable resin composition.

[0120] <Reaction force during compression of solidified material>

[0121] In this specification, the reaction force of the cured material is determined by the following steps.

[0122] A photocurable resin composition was sandwiched between two release terephthalate (PET) films, and a 1 mm thick separator was used to form a film. Then, an ultraviolet irradiation device was used with a cumulative light dose of 15 kJ / m². 2 The photocurable resin composition between the films was cured by irradiating it with ultraviolet light (wavelength 365nm), resulting in a product (i.e., a cured product) with the release terephthalic acid (PET) film removed. A sample (a disc with a thickness of 1 mm and a diameter of 35 mm) was prepared from this cured product. Next, using a tensile compression apparatus (Shimadzu Corporation, model AGX-50kNV), at a temperature of 25°C and a test compression speed of 50 mm / min, the stress (in kPa) applied to the sensor by the test piece (sample) under compression relative to the sample thickness of 1 mm at either 10% (i.e., compression to a thickness of 0.9 mm) or 50% (i.e., compression to a thickness of 0.5 mm) was measured as the reaction force. The reaction force of the cured product was determined according to JIS K7181:2011.

[0123] In this invention, the reaction force at 10% compression of the cured material is preferably 1 to 300 kPa, more preferably 2 to 250 kPa. Furthermore, the reaction force at 50% compression of the cured material is preferably 1 to 500 kPa, more preferably 2 to 400 kPa. By reducing the reaction force generated in the cured material within the above ranges, deformation of the battery pack casing surface can be effectively suppressed when the cured material of the photocurable resin composition of this invention is sandwiched between batteries as a buffer material.

[0124] [Layered Body]

[0125] Another aspect of the present invention is a laminate formed by laminating the above-described photocurable resin composition. Specifically, a laminate according to one embodiment of the present invention comprises a first adherend, a second adherend, and the above-described cured product, and has a structure in which the first adherend and the second adherend are bonded to each other by the cured product. That is, a laminate according to one aspect of the present invention is a laminate formed by sequentially laminating a first adherend, a cured product of the above-described photocurable resin composition, and a second adherend.

[0126] There are no particular limitations on the materials constituting the first and second adherends; for example, materials that can be used in the fields described in the "Uses" section below can be applied.

[0127] There are no particular limitations on the manufacturing method of the laminate. For example, one method is to coat a first substrate with the photocurable resin composition of the present invention, then overlap a second substrate on the coated resin composition, and then irradiate the coated resin composition with light.

[0128] [use]

[0129] The photocurable resin composition of the present invention can be used in various fields such as the automotive industry, the electrical and electronic components industry, and the aerospace industry. Among them, from the perspective of obtaining a cured product with low reaction force over a wide range of compression ratios (compression range), particularly preferred applications include resins for bonding liquid crystal display display parts and protective panels; elastically curable resins for adjusting the sealing of fuel cells and sensors, and for applying surface pressure in the stacking direction between battery cells when stacking battery cells of secondary batteries (for example, see Japanese Patent Publication No. 2009-158381).

[0130] Although embodiments of the invention have been described in detail, it should be understood that the scope of the invention should be interpreted by the appended claims, rather than being restrictive, as they are illustrative and exemplary.

[0131] The present invention includes the following methods and approaches.

[0132] [1] A photocurable resin composition having a reaction force of 1 to 300 kPa at 10% compression of the cured product and a reaction force of 1 to 500 kPa at 50% compression of the cured product, containing hollow organic resin filler as component (A), and not containing monofunctional (meth)acrylic monomers with hydroxyl groups.

[0133] [2] The photocurable resin composition according to [1] further comprises the following components (B) to (D);

[0134] (B) Ingredients: Monofunctional carbamate (meth)acrylate

[0135] (C) Components: Monofunctional (meth)acrylic acid monomers other than those in (B) above.

[0136] (D) Component: Photoradical polymerization initiator.

[0137] [3] The photocurable resin composition according to [2] includes 3 to 70 parts by mass of component (A) above, relative to a total of 100 parts by mass of component (B) and component (C) above.

[0138] [4] The photocurable resin composition according to [2] or [3], wherein the weight-average molecular weight of component (B) is 0.1 million to 300,000.

[0139] [5] The photocurable resin composition according to any one of [1] to [4] further comprises a plasticizer without (meth)acryloyl group as component (E).

[0140] [6] According to the photocurable resin composition of [5], wherein the above-mentioned component (B), component (C) and component (E) are compounds containing a polyether backbone.

[0141] [7] The photocurable resin composition according to any one of [1] to [6], wherein the average particle size of component (A) is 5 to 300 μm.

[0142] [8] The photocurable resin composition according to any one of [1] to [7], wherein the organic resin of the (A) component comprises an acrylonitrile-methacrylonitrile-methyl methacrylate copolymer.

[0143] [9] The photocurable resin composition according to any one of [1] to [8] further contains a polyfunctional (meth)acrylic acid monomer with two or more functions as component (F).

[0144]

[10] The cured product of the photocurable resin composition according to any one of [1] to [9].

[0145]

[11] A laminate comprising: a first adherend; a second adherend; and a cured material according to

[10] , the laminate having a configuration in which the first adherend and the second adherend are bonded together by the cured material.

[0146] In addition, the present invention includes the following methods.

[0147] [1'] A photocurable resin composition, which does not contain monofunctional (meth)acrylic monomers with hydroxyl groups, but contains hollow organic resin filler as component (A), wherein the reaction force of the cured product of the photocurable resin composition at 10% compression is 1 to 300 kPa, and the reaction force at 50% compression is 1 to 500 kPa.

[0148] Furthermore, the present invention can also adopt the methods described in [2] to

[11] in the above-described [1'] manner.

[0149]

Example

[0150] The following examples illustrate the invention in more detail, but the invention is not limited to these examples. Furthermore, unless otherwise specified, operations, tests, etc., are conducted at 25°C and 55% RH.

[0151] <Preparation of Photocurable Resin Compositions>

[0152] Example 1

[0153] Weigh the following components (A) to (G) and mix them in a light-shielding environment at 25°C for 60 minutes using a mixer to obtain a light-curing resin composition that is liquid at 25°C (Example 1);

[0154] As component (A), component (a1) is used: average particle size of 80 μm, true specific gravity of 0.13 g / cm³. 3 20 parts by weight of hollow filler (microspheres) formed from acrylonitrile-methacrylonitrile-methyl methacrylate copolymer with calcium carbonate adhering to the surface (manufactured by Fillite Co., Ltd., Japan, EMC-80B).

[0155] As component (B), use (b1): 80 parts by weight of monofunctional polyether polyurethane acrylate (manufactured by Nejou Kogyo Co., Ltd.) with a weight-average molecular weight of 30,000.

[0156] As component (C), use (c1): 35 parts by weight of ethoxydiethylene glycol monoacrylate (manufactured by Toyo Chemical Co., Ltd., Miramer (registered trademark) M170, molecular weight 188).

[0157] As component (D), use (d1): 3 parts by weight of 2-hydroxy-2-methyl-1-phenyl-propane-1-one (manufactured by DOUBLE BONDCHEMICAL IND.CO.,LTD., DOUBLE CURE (registered trademark) 173).

[0158] As component (E), (e1) is used: 44 parts by weight of polypropylene glycol (manufactured by Nippon Oil Co., Ltd., UNIOL (registered trademark) D2000) with a number average molecular weight of 2000 and an epoxy alkyl repeat number of 34.

[0159] As component (F), 1.6 parts by weight of dipentaerythritol hexaacrylate (manufactured by Daicel-Ornex Co., Ltd., DPHA, molecular weight 579) was used.

[0160] As component (G), component (g1) is used: 7 parts by mass of silica particles (calcined silica) that have been surface-treated with dimethyl silicone.

[0161] Example 2

[0162] In Example 1, except that the content of component (a1) was changed from 20 parts by mass to 25 parts by mass, a photocurable resin composition that is liquid at 25°C was obtained in the same manner as in Example 1 (Example 2).

[0163] Example 3

[0164] In Example 2, component (a2) was added: average particle size 120 μm, true specific gravity 0.10 g / cm³. 3 The hollow filler (microspheres) (manufactured by Fillite Co., Ltd., Japan: 120α) with calcium carbonate attached to its surface was used to replace component (a1). Otherwise, it was prepared in the same manner as in Example 2 to obtain a photocurable resin composition that is liquid at 25°C (Example 3).

[0165] Example 4

[0166] In Example 3, instead of 80 parts by weight of component (b1), 70 parts by weight of component (b2) were replaced with monofunctional polyether urethane acrylate (manufactured by Negami Kogyo Co., Ltd.) with a weight average molecular weight of 20,000. The content of component (e1) was changed from 44 parts by weight to 60 parts by weight. Otherwise, the same as in Example 3, a photocurable resin composition that is liquid at 25°C was obtained (Example 4).

[0167] Example 5

[0168] In Example 4, except that the content of component (f1) was changed from 1.6 parts by mass to 3.2 parts by mass, the same as in Example 4 was obtained, resulting in a light-curable resin composition that is liquid at 25°C (Example 5).

[0169] Comparative Example 1

[0170] In Example 1, except that component (a1) was not added, a photocurable resin composition that is liquid at 25°C was obtained in the same manner as in Example 1 (Comparative Example 1).

[0171] Comparative Example 2

[0172] In Example 1, instead of component (a1), component (a'1) was replaced with glass hollow filler (made by 3M; glass bulb K1) with an average particle size of 65 μm and a true specific gravity of 0.13 g / cm3. Otherwise, a photocurable resin composition that is liquid at 25°C was obtained in the same manner as in Example 1 (Comparative Example 2).

[0173] Comparative Example 3

[0174] In Example 4, except that component (c1) was changed to 2-hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Industry) (c'1), the same as in Example 4 was obtained, resulting in a light-curable resin composition that is liquid at 25°C (Comparative Example 3).

[0175] Comparative Example 4

[0176] In Example 4, the content of component (c1) was changed from 35 parts by mass to 15 parts by mass, and then changed to contain 15 parts by mass of component (c'1). Otherwise, the same procedure as in Example 4 was followed to obtain a light-curable resin composition that is liquid at 25°C (Comparative Example 4).

[0177] Table 1 below shows the components and contents of the photocurable resin compositions of each embodiment and comparative example. Blank columns indicate that no corresponding component was added.

[0178] The photocurable resin compositions involved in the above embodiments and comparative examples were subjected to the following tests (1) and (2). The test methods for tests (1) and (2) are described below.

[0179] Experiment (1): Reaction force during compression of a solidified material

[0180] Various photocurable resin compositions are sandwiched between two release films made of polyethylene terephthalate, and a 1 mm thick separator is used to form a film. Next, ultraviolet light (wavelength 365 nm) is applied using an ultraviolet irradiation device to achieve a cumulative light intensity of 15 kJ / m². 2The photocurable resin composition between the films was cured, and then the material obtained by removing the polyethylene terephthalate film used for peeling (i.e., the cured product) was obtained. A 1 mm thick, 35 mm diameter disc was cut from this cured product and used as a sample. Next, using a compression apparatus (Shimadzu Corporation; model AGX-50kNV), at a temperature of 25°C and a compression speed of 50 mm / min, the reaction force applied to the sensor was measured when the sample thickness was compressed at 10% (i.e., compressed to a thickness of 0.9 mm) or 50% (i.e., compressed to a thickness of 0.5 mm) relative to a thickness of 1 mm. The reaction force of the cured product of each sample was measured according to JIS K 7181:2011. The results are shown in Table 1. Furthermore, "uncured" in the table means that it remains liquid even when irradiated with ultraviolet light.

[0181] Experiment (2): Photocurability Test

[0182] 0.01 g of each photocurable resin composition was dropped onto a glass specimen measuring 25 mm wide × 100 mm long × 5 mm thick. Then, an ultraviolet irradiation machine (conveyor UV irradiation device, LED light source, UV wavelength 365 nm, peak illuminance 650 mW / cm²) was used. 2 The cumulative light intensity during irradiation is 1.5 kJ / m². 2 The active energy rays were used to obtain test pieces. Next, a glass rod with a sharp tip was brought into contact with the test pieces, and the curability of each photocurable resin composition was evaluated based on the following criteria:

[0183] Evaluation criteria

[0184] ○: There is no residue on the stick.

[0185] ×: There are attached substances on the rod.

[0186] [Table 1]

[0187]

[0188] As shown in Table 1, based on the photocurable resin compositions of Examples 1 to 5, it can be confirmed that cured products can be obtained rapidly by photocuring and that cured products with low reaction forces can be obtained over a wide range of compression ratios (compression ranges).

[0189] On the other hand, Comparative Example 1, a photocurable resin composition not containing component (A) of the present invention, resulted in excessively high reaction force at 50% compression of the cured product. Furthermore, Comparative Example 2, a photocurable resin composition containing component (a'1) as a glass hollow filler instead of component (A) of the present invention, also resulted in excessively high reaction force at 50% compression of the cured product. Moreover, Comparative Examples 3 and 4, photocurable resin compositions containing a monofunctional acrylic monomer with hydroxyl groups, i.e., component (c'1), resulted in significantly deteriorated photocurability.

[0190] Industrial availability

[0191] The photocurable resin composition of the present invention is useful in industry because it provides a cured product with low reaction force over a wide range of compression ratios (compression ranges), making it applicable in various fields. Furthermore, the photocurable resin composition of the present invention not only provides a cured product rapidly through photocuring, but also remains liquid before curing. Therefore, when obtaining the cured product, it is possible to choose methods such as surface coating or screen printing, which can contribute to increased productivity.

[0192] This application is based on Japanese Patent Application No. 2020-187535, filed on November 10, 2020, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A photocurable resin composition, the reaction force at 10% compression of a cured product being 1 to 300 kPa, the reaction force at 50% compression of the cured product being 1 to 500 kPa, containing a hollow organic resin filler as a (A) component, further containing (B) to (D) components below, and not containing a monofunctional (meth)acrylic monomer having a hydroxyl group: (B) component: a monofunctional urethane (meth)acrylate (C) component: a monofunctional (meth)acrylic monomer other than the (B) component (D) component: a photoradical polymerization initiator, the hollow organic resin filler being a hollow organic resin filler containing an acrylonitrile-methacrylonitrile-methyl methacrylate copolymer with calcium carbonate attached to the surface, and having an average particle diameter of 70 to 100 μm. The (A) component is contained in an amount of 3 to 70 parts by mass with respect to 100 parts by mass of the total of the (B) component and the (C) component. The weight average molecular weight of the (B) component is 0.1 to 300 thousand. A plasticizer not having a (meth)acryl group is further contained as an (E) component. wherein The (B) component, the (C) component, and the (E) component are each a compound containing a polyether skeleton.

2. The photocurable resin composition according to claim 1, wherein, A multifunctional (meth)acrylic monomer having a functionality of 2 or more is further contained as an (F) component.

3. The photocurable resin composition according to claim 1 or 2, wherein, 7. A cured product of the photocurable resin composition according to any one of claims 1 to 6.

4. The photocurable resin composition according to claim 1 or 2, wherein, 8. A laminate comprising: a first adherend; a second adherend; and the cured product according to claim 7, the laminate having a configuration in which the first adherend and the second adherend are attached to each other via the cured product.

5. The photocurable resin composition according to claim 4, wherein, ​ 6. The photocurable resin composition according to claim 1 or 2, wherein ​ ​ ​

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