Active energy ray-curable resin composition

Abstract

To provide an active energy ray-curable resin composition excellent in dischargeability, very low in hardness of a cured product, capable of showing a high aspect ratio, and capable of showing excellent reworkability of a cured product.SOLUTION: An active energy ray-curable resin composition contains the following (A) component, (B) component, (C) component, and (D) component, wherein (A) is an urethane acrylate oligomer with a weight average molecular weight of 40,000 to 80,000, composed of an urethane backbone having an ether bond, (B) is a monofunctional acrylic acid ester monomer, (C) is a photopolymerization initiator, and (D) is fumed silica. The component (C) contains a benzophenone compound. A cured product obtained by irradiating the active energy ray-curable resin composition with ultraviolet light under the conditions of a cumulative light quantity of 5000 mJ / cm2 using a high-pressure mercury lamp, which has a thickness of 2 mm, has a storage modulus G' at 25°C of 400,000 Pa or less measured under conditions of a dynamic viscoelasticity device in a rotational shear mode with a vibration frequency of 1 Hz, a heating rate of 5°C / min, and a temperature range from -70°C to 70°C. The peak temperature of Tanδ is -10°C or below, and the peak height of Tanδ is 1.5 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an active energy ray-curable resin composition.

Background Art

[0002] Conventionally, since active energy ray-curable resin compositions have the property of being curable in a short time, they have been widely used in coating applications, adhesive applications, field-molded liquid gasket (CIPG) applications, and the like.

[0003] In the active energy ray-curable resin composition used for the above-mentioned applications, when the cured surface is exposed to air (oxygen) during photocuring, it is subject to oxygen inhibition, and the curing of the cured surface may be insufficient and tack may occur. In particular, in the active energy ray-curable resin composition used for coating applications and CIPG applications, in order to prevent dirt from adhering to the cured surface and the substrates from sticking to each other, the cured surface is required to be tack-free. Being tack-free enables easy peeling in the case of a component where CIPG applied to a housing on which a device is mounted is further bonded with a cover case when a problem occurs, and plays an important role in reworkability.

[0004] As such an active energy ray-curable resin composition, a photocurable composition containing specific components such as elastomer (A), monomer (B) having a (meth)acryloyl group, and photopolymerization initiator (C) has been proposed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in recent years, as an alternative to molded foam gaskets, on-site applied CIPGs have attracted attention. Conventional molded foam gaskets are very low in hardness due to being foamed, and since they have an extremely low hardness, the CIPG used as an alternative is also required to have a very low hardness. The photocurable composition described in Patent Document 1 uses a specific elastomer (A) and a monomer (B) having a (meth)acryloyl group. Since the Tg of the monomer having a (meth)acryloyl group is high, it is expected to have a high hardness. In addition, in order to improve the tack-free property and reworkability of the cured product surface, a polyfunctional acrylate or a low molecular weight urethane acrylate is used, and a means of increasing the crosslink density is used. However, even when the above means are used, there is a problem that the hardness of the cured product becomes high. Such a cured product is not suitable as an alternative to a molded foam gasket (also referred to as a sponge gasket, sponge packing, rubber sponge, etc.).

[0007] In addition, it is possible to form a cured product with a low hardness and softness by incorporating a thiol compound into the active energy ray-curable resin composition, selecting an oligomer skeleton, etc. However, there is a problem that the cured product is likely to have a sticky surface tack and the reworkability deteriorates. In particular, in the case of CIPG used as an alternative to a molded foam gasket, since the hardness is extremely low, there is a problem that the deterioration of the reworkability is remarkable.

[0008] In addition, the photocurable composition described in Patent Document 1 has not been sufficiently studied regarding its suitability for CIPG applications such as dischargeability and high aspect ratio. The active energy ray-curable resin composition used for CIPG applications is required to be applicable to the desired shape when applied at a certain discharge pressure to the location where CIPG is to be formed, that is, to have excellent dischargeability. If the discharge amount at a certain discharge pressure is small, in CIPG applications, the coating amount is limited, and the bead width and bead height are limited, which is not suitable.

[0009] In addition, the above-described active energy ray-curable resin composition is required to be able to form a desired shape, and the cured product formed is required to exhibit a high aspect ratio.

[0010] In view of the above circumstances, an object of the present invention is to provide an active energy ray-curable resin composition that is excellent in dischargeability, has a very low hardness of the cured product, can exhibit a high aspect ratio, and can exhibit good reworkability of the cured product.

Means for Solving the Problems

[0011] As a result of intensive studies, the present inventors have found that an active energy ray-curable resin composition containing specific components (A) to (D), wherein the component (C) contains a benzophenone compound, and the active energy ray-curable resin composition is irradiated with ultraviolet rays using a high-pressure mercury lamp under the condition of an integrated light amount of 5000 mJ / cm 2 The cured product with a thickness of 2 mm obtained by irradiation has a storage elastic modulus G' at 25°C measured under the conditions of a rotational shear mode with a vibration frequency of 1 Hz, a temperature rising rate of 5°C / min, and a temperature range of -70°C to 70°C using a dynamic viscoelasticity measuring apparatus of 400000 Pa or less, the peak temperature of Tanδ is -10°C or less, and the peak height of Tanδ is 1.5 or less. It has been found that the above object can be achieved by the active energy ray-curable resin composition, and the present invention has been completed.

[0012] That is, the present invention relates to the following active energy ray-curable resin composition. 1. An active energy ray-curable resin composition containing the following components (A), (B), (C), and (D), (A) A urethane acrylate oligomer having a urethane skeleton having an ether bond and a weight average molecular weight of 40000 to 80000, (B) A monofunctional acrylate monomer, (C) A photopolymerization initiator, (D) Fumed silica, The component (C) contains a benzophenone compound, The active energy ray-curable resin composition is irradiated with ultraviolet rays using a high-pressure mercury lamp under the condition of an integrated light amount of 5000 mJ / cm2 The cured product with a thickness of 2 mm obtained by irradiating with ultraviolet rays under the conditions of is an active energy ray-curable resin composition characterized in that 2. The hardness at 25°C of the cured product measured with a type OO durometer by a measurement method conforming to ASTM D2240 is 70 or less, and the active energy ray-curable resin composition according to item 1. 3. The content of the component (A) is 15 to 30% by mass based on the total content of the component (A) and the component (B) being 100% by mass, and the active energy ray-curable resin composition according to item 1 or 2. 4. The component (B) contains the following component (B1), component (B2), and component (B3). (B1) Phenoxyethyl acrylate (B2) An alkyl acrylate having a diethylene glycol skeleton (B3) An alkyl acrylate having 8 or more carbon atoms The content of the component (B2) is 30% by mass or less based on the total content of the component (B1), the component (B2), and the component (B3) being 100% by mass, and the content of the component (B3) is 35% by mass or less based on the total content of the component (B1), the component (B2), and the component (B3) being 100% by mass, and the active energy ray-curable resin composition according to any one of items 1 to 3.

Advantages of the Invention

[0013] An object of the active energy ray-curable resin composition of the present invention is to provide an active energy ray-curable resin composition having excellent dischargeability, a very low hardness of the cured product, capable of showing a high aspect ratio, and the cured product capable of showing good reworkability.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described in detail.

[0015] 1. Active energy ray-curable resin composition The active energy ray-curable resin composition of the present invention is an active energy ray-curable resin composition containing the following components (A), (B), (C), and (D). (A) A urethane acrylate oligomer having a urethane skeleton with an ether bond and a weight average molecular weight of 40,000 to 80,000. (B) A monofunctional acrylate monomer. (C) A photopolymerization initiator. (D) Fumed silica. The component (C) contains a benzophenone compound. When the active energy ray-curable resin composition is irradiated with ultraviolet rays under the condition of an integrated light amount of 5000 mJ / cm 2 to obtain a cured product with a thickness of 2 mm, the storage elastic modulus G' at 25°C measured under the conditions of a rotational shear mode with a vibration frequency of 1 Hz, a heating rate of 5°C / min, and a temperature range of -70°C to 70°C using a dynamic viscoelasticity apparatus is 400,000 Pa or less, the peak temperature of Tanδ is -10°C or less, and the peak height of Tanδ is 1.5 or less. It is an active energy ray-curable resin composition.

[0016] The active energy ray-curable resin composition having the above characteristics contains the above specific components (A) to (D), the component (C) contains a benzophenone compound, and the cured product cured under specific conditions exhibits the above characteristics. Thus, the active energy ray-curable resin composition has excellent dischargeability, the hardness of the cured product is very low, it can exhibit a high aspect ratio, and further, the cured product can exhibit good reworkability.

[0017] In this specification, "dischargeability" means that when it is applied at a certain discharge pressure to a location where a cured product such as CIPG is desired to be formed, it can be applied in the desired shape (such as a bead shape), and it can be applied under a wide range of conditions. Specifically, it does not mean that it can be applied to a wide range of bead widths and bead heights.

[0018] Furthermore, since the active energy ray-curable resin composition of the present invention has the above-described configuration, the cured product has a very low hardness and excellent flexibility, and the cured product can exhibit a high aspect ratio and good reworkability.

[0019] The active energy ray-curable resin composition of the present invention as described above has a very low hardness and excellent flexibility of the cured product. Therefore, as an alternative to the molded foamed gasket, it can be suitably used, for example, in control devices such as sensors, devices of home electric appliances, digital cameras, etc.

[0020] Hereinafter, the active energy ray-curable resin composition of the present invention will be described in detail.

[0021] For the cured product with a thickness of 2 mm obtained by irradiating the active energy ray-curable resin composition of the present invention with ultraviolet rays under the condition of an integrated light amount of 5000 mJ / cm 2 using a high-pressure mercury lamp, the storage elastic modulus G' at 25°C measured under the conditions of a rotational shear mode with a vibration frequency of 1 Hz, a temperature rising rate of 5°C / min, and a temperature range of -70°C to 70°C using a dynamic viscoelasticity apparatus is 400000 Pa or less. When the storage elastic modulus G' of the above cured product exceeds 400000 Pa, the aspect ratio and reworkability decrease, and the hardness increases. The storage elastic modulus G' is preferably 350000 Pa or less, more preferably 320000 Pa or less, and even more preferably 300000 Pa or less. Also, the lower limit of the storage elastic modulus G' is not particularly limited, and may be, for example, 50000 Pa, 100000 Pa, or 200000 Pa.

[0022] For the active energy ray-curable resin composition of the present invention, an integrated light amount of 5000 mJ / cm 2The cured product with a thickness of 2 mm obtained by irradiating with ultraviolet rays under the conditions has a peak temperature of Tanδ of -10°C or lower when measured under the conditions of a rotational shear mode with a vibration frequency of 1 Hz, a temperature increase rate of 5°C / min, and a temperature range of -70°C to 70°C using a dynamic viscoelasticity apparatus. The peak temperature of Tanδ is preferably -15°C or lower, more preferably -20°C or lower. Also, the lower limit of the peak temperature of Tanδ is not particularly limited and may be -60°C, -50°C, or -40°C.

[0023] The cured product with a thickness of 2 mm obtained by irradiating the active energy ray-curable resin composition of the present invention with ultraviolet rays using a high-pressure mercury lamp under an integrated light amount of 5000 mJ / cm 2 has a peak height of 1.5 or less when measured under the conditions of a rotational shear mode with a vibration frequency of 1 Hz, a temperature increase rate of 5°C / min, and a temperature range of -70°C to 70°C using a dynamic viscoelasticity apparatus. When the peak height of Tanδ exceeds 1.5, the reworkability deteriorates. The peak height of Tanδ is preferably 1.4 or less. Also, the lower limit of the peak height of Tanδ is not particularly limited and may be 0.8, 0.9, 1.0, 1.1, etc.

[0024] In the present invention, specifically, the above-described storage elastic modulus G', the peak temperature of Tanδ, and the peak height of Tanδ are measured by the following measurement methods.

[0025] Method for measuring dynamic viscoelasticity (storage elastic modulus G', peak temperature of Tanδ, peak height of Tanδ) Prepare a silicon rubber sheet with a thickness of 2 mm in a rectangular frame shape as a spacer. Next, place the spacer on a release-treated aluminum plate and pour the active energy ray-curable resin composition into the frame of the spacer. Prepare a quartz glass, stack it so as to be in contact with the active energy ray-curable resin composition, compress it, and in that state, under an integrated light amount of 5000 mJ / cm 2Under the conditions of [[ID=]], ultraviolet irradiation is performed. The quartz glass is peeled off, and a sample for measuring dynamic viscoelasticity is prepared. Using the sample prepared as described above, a dynamic viscoelasticity measurement (heating process) is performed in a rotational shear mode at a frequency of 1 Hz, in a temperature range from -70 °C to 70 °C, and under a heating condition of a heating rate of 5 °C / min using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, model HR-10). The peak temperature of Tanδ, the peak height, and the storage elastic modulus G' at 25 °C obtained by the measurement are taken as the measured values.

[0026] Hereinafter, each component constituting the active energy ray-curable resin composition of the present invention will be described in detail.

[0027] Component (A) Component (A) is a urethane acrylate oligomer having a urethane skeleton with an ether bond and a weight average molecular weight of 40,000 to 80,000.

[0028] The weight average molecular weight (Mw) of component (A) is 40,000 to 80,000. When the weight average molecular weight is less than 40,000, the hardness of the cured product of the active energy ray-curable resin composition becomes too high. When the weight average molecular weight exceeds 80,000, the cured product of the active energy ray-curable resin composition becomes too soft and is not suitable for applications such as CIPG applications that necessarily involve compression. The weight average molecular weight is preferably 45,000 to 78,000, and more preferably 48,000 to 75,000.

[0029] In the present invention, the weight average molecular weight (Mw) is a measured value obtained by conversion with standard polystyrene using a gel permeation chromatography (GPC) measuring device.

[0030] (A) component urethane acrylate oligomer has a urethane skeleton having an ether bond and is not particularly limited as long as the weight average molecular weight is within the above range. Examples of such urethane acrylate oligomers include those having a polytetramethylene ether glycol derivative skeleton, 1,3 - polypropanediol derivative skeleton, polypropylene glycol skeleton, polyethylene glycol skeleton, propylene oxide - modified bisphenol A skeleton, ethylene oxide - modified bisphenol A skeleton, etc.

[0031] (A) component urethane acrylate oligomer can be obtained by reacting a polyol having the above - mentioned polytetramethylene ether glycol derivative skeleton, polyether polycarbonate skeleton, polypropylene glycol skeleton, polyethylene glycol skeleton, propylene oxide - modified bisphenol A skeleton, ethylene oxide - modified bisphenol A skeleton, etc. with at least one diisocyanate compound selected from alicyclic diisocyanate compounds, aliphatic diisocyanate compounds, and aromatic diisocyanate compounds, and then subjecting the isocyanate group and the hydroxyl group of an acrylate having a hydroxyl group to an addition reaction (also called a urethanization reaction).

[0032] As the above - mentioned diisocyanate compound, alicyclic diisocyanate is preferable, and examples thereof include 4,4’ - methylenebis(cyclohexyl isocyanate), 1,3 - (isocyanatomethyl)cyclohexane, isophorone diisocyanate, etc.

[0033] (A) component urethane acrylate oligomer can use commercially available products. Examples of such commercially available products include UV3700B (manufactured by Mitsubishi Chemical Corporation), etc.

[0034] The content of component (A) is preferably 5 to 43% by mass, more preferably 10 to 38% by mass, and still more preferably 11 to 33% by mass, with the active energy ray-curable resin composition being 100% by mass. When the content of component (A) is within the above range, the dischargeability of the active energy ray-curable resin composition is further improved, the hardness of the cured product is lower, a higher aspect ratio can be exhibited, and better reworkability can be shown.

[0035] The content of component (A) relative to the total of component (A) and component (B) described below is preferably 7 to 45% by mass, more preferably 10 to 40% by mass, still more preferably 12 to 35% by mass, and particularly preferably 15 to 30% by mass. When the content of component (A) is within the above range, the dischargeability of the active energy ray-curable resin composition is further improved, the hardness of the cured product is lower, a higher aspect ratio can be exhibited, and better reworkability can be shown.

[0036] Component (B) Component (B) is a monofunctional acrylate monomer. By containing the above component (B), the hardness of the cured product of the active energy ray-curable resin composition becomes very low, the dischargeability is further improved, and it can be suitably used for CIPG applications and the like as an alternative to molded foam gaskets. In addition, the active energy ray-curable resin composition of the present invention can exhibit excellent reworkability despite the low hardness of the cured product.

[0037] Component (B) is not particularly limited as long as it is a monofunctional acrylate monomer. Examples of such monofunctional acrylate monomers include monofunctional (meth)acrylate monomers having one unsaturated bond in the molecule.

[0038] Specific examples of the above monofunctional (meth)acrylate monomer include chain alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 1-ethylheptyl (meth)acrylate, nonyl (meth)acrylate, n-octyl acrylate, isononyl (meth)acrylate, isodecyl acrylate, 1-butylamyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, and (meth)acrylates having a cyclic structure such as isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenoxy (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxy (meth)acrylate, alkylphenoxyethyl (meth)acrylate; hydroxyalkyl (meth)acrylates having a hydroxyl group such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxylauryl (meth)acrylate, or 2-hydroxy-3-phenoxypropyl acrylate;and mono(meth)acrylates of oligo- or polyoxyalkylene glycols such as diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, trimethylene glycol mono(meth)acrylate, polypropylene glycol (meth)acrylate, etc. These may be used alone, or two or more of them may be used in combination.;

[0039] Among these, it is preferable to use at least one selected from the group consisting of (meth)acrylate monomers having an alicyclic structure, (meth)acrylate monomers having a cyclic structure such as an aromatic skeleton, (meth)acrylate monomers having an aromatic skeleton and modified with ethylene oxide, (meth)acrylate monomers having a hydroxyl group in the molecule, and linear alkyl (meth)acrylates. Among these, from the viewpoint of making the cured product of the active energy ray-curable resin composition more flexible, it is particularly preferable to use linear alkyl (meth)acrylates.

[0040] Examples of the (meth)acrylate monomer having an alicyclic structure include isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate. Examples of the (meth)acrylate having an aromatic skeleton and modified with ethylene oxide include phenoxy polyethylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, and examples of the (meth)acrylate monomer having a cyclic structure such as an aromatic skeleton include phenoxyethyl (meth)acrylate.

[0041] Among these, phenoxy polyethylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, etc. are particularly preferable.

[0042] (B) The glass transition temperature (Tg) of the monofunctional acrylate monomer of component (B) is preferably from -80 to 15°C, more preferably from -70 to 5°C. Since the glass transition temperature of component (B) is within the above range, the cured product obtained by curing the active energy ray-curable resin composition of the present invention has a very low hardness and excellent flexibility, so it can be more preferably used as an alternative to a molded foam gasket and also as a field-molded CIPG.

[0043] (B) The content of component (B) is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and still more preferably 70 to 90% by mass based on 100% by mass in total of components (A) and (B). Since the content of component (B) is within the above range, the cured product obtained by curing the active energy ray-curable resin composition of the present invention has a very low hardness and excellent flexibility, so it can be more preferably used as an alternative to a molded foam gasket and in a field-applied type CIPG.

[0044] Component (B) preferably contains phenoxyethyl acrylate as component (B1), an alkyl acrylate having a diethylene glycol skeleton as component (B2), and an alkyl acrylate having 8 or more carbon atoms as component (B3). When component (B) has a configuration containing the above-mentioned components (B1), (B2), and (B3), the dischargeability of the active energy ray-curable resin composition is further improved, the hardness of the cured product is lower, a higher aspect ratio can be shown, and better reworkability can be shown.

[0045] When component (B) has a configuration containing the above-mentioned components (B1), (B2), and (B3), the content of component (B2) is preferably 40% by mass or less, more preferably 30% by mass or less, based on 100% by mass in total of the contents of components (B1), (B2), and (B3). Also, the content of component (B2) is preferably 10% by mass or more, more preferably 20% by mass or more, based on 100% by mass in total of the contents of components (B1), (B2), and (B3).

[0046] When the component (B) has a configuration containing the above-mentioned components (B1), (B2), and (B3), the content of the component (B3) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, with the total content of the components (B1), (B2), and (B3) being 100% by mass. Further, the content of the component (B3) is preferably 10% by mass or more, more preferably 20% by mass or more, with the total content of the components (B1), (B2), and (B3) being 100% by mass.

[0047] When the component (B) has a configuration containing the above-mentioned components (B1), (B2), and (B3), it is preferable that the content of the component (B2) is 30% by mass or less and the content of the component (B3) is 35% by mass or less, with the total content of the components (B1), (B2), and (B3) being 100% by mass. By setting the content of the component (B2) and the content of the component (B3) within the above ranges, the dischargeability of the active energy ray-curable resin composition can be further improved, the hardness of the cured product can be lower, a higher aspect ratio can be exhibited, and better reworkability can be shown.

[0048] Component (C) The component (C) is a photoinitiator. In the present invention, the component (C) contains a benzophenone compound. By containing the component (C), the benzophenone compound extracts hydrogen through a triplet excited state by light using an oligomer and / or a (meth)acrylate monomer as a donor, and the oligomer and / or the (meth)acrylate monomer from which hydrogen has been extracted generates radicals, and the radicals efficiently initiate radical polymerization and / or crosslinking reactions with the oligomer and the (meth)acrylate monomer, thereby further improving the curability of the surface.

[0049] Examples of the benzophenone compound include benzophenone, 4-methylbenzophenone, 4-phenylbenzophenone, benzophenone derivatives, and the like.

[0050] Specific examples of the benzophenone derivative include 4-(4-methylphenylthio)benzophenone, 4,4'-bis(diethylamino)benzophenone, methyl 2-benzoylbenzoate, and the like.

[0051] As the benzophenone compound contained in the component (C), commercially available products may be used. Examples of such commercially available products include those manufactured by iGM RESIN: product names such as "Ommiad BP-FLAKES", "Omnirad 4MBZ-FLAKES", "Omnirad BMS", "Omnirad EMK", "Omnirad OMBB", "Omnirad 4PBZ", and the like.

[0052] In addition to the benzophenone compound, the component (C) may further contain other photoinitiators. Examples of such other photoinitiators include compounds having a benzoyl group, α-hydroxyacetophenone derivatives, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethylphenyl(2,4,6-trimethylbenzoyl)phosphinate, benzyl ketal compounds, and the like.

[0053] Specific examples of the compound having a benzoyl group include methyl benzoylformate (methyl benzoylformate), and the like.

[0054] As the compound having a benzoyl group, commercially available products may be used. Examples of such commercially available products include those manufactured by iGM RESIN: product names such as "Omnirad MBF", and the like.

[0055] Specific examples of the α-hydroxyacetophenone derivative include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2,2'-dihydroxy-2,2'-dimethyl-1,1'-[methylenebis(4,1-phenylene)]bis(propan-1-one), and the like.

[0056] Examples of the benzyl ketal compound include 2,2-dimethoxy-2-phenylacetophenone and the like.

[0057] Among these, from the viewpoint of further improving the surface curability, the component (C) preferably contains a benzophenone compound and a compound having a benzoyl group, and more preferably contains a benzophenone compound and methyl benzoyl formate.

[0058] The above component (C) can be used alone or in combination of two or more.

[0059] The content of the component (C) is preferably 0.5 to 10 parts by mass, more preferably 1.0 to 8 parts by mass, and still more preferably 1.5 to 5 parts by mass with respect to 100 parts by mass in total of the components (A) and (B). When the content of the component (C) is within the above range, the active energy ray-curable resin composition can appropriately adjust the hardness after curing and can exhibit better reworkability.

[0060] Component (D) The component (D) is fumed silica.

[0061] The fumed silica is not particularly limited, and known fumed silicas such as hydrophilic fumed silica having a large number of hydrophilic silanol groups (Si-OH) on the surface and hydrophobic fumed silica having a large number of hydrophobic siloxane groups (Si-O-Si) on the surface can be used.

[0062] In the active energy ray-curable resin composition of the present invention, since it contains a urethane acrylate having an ether bond as the component (A), it is preferable to use hydrophilic fumed silica as the component (D). By using hydrophilic fumed silica as the component (D), the aspect ratio of the active energy ray-curable resin composition can be made higher.

[0063] The average primary particle diameter of the fumed silica is preferably from 5 nm to 50 μm. By using such fumed silica, good thixotropy can be imparted to the active energy ray-curable resin composition of the present invention, and the coating property is excellent. Further, the active energy ray-curable resin composition of the present invention can be made transparent, and sufficient curability can be obtained even when irradiated with ultraviolet rays or the like.

[0064] In the present invention, the content of the component (D) is preferably 4 parts by mass or more, more preferably 4.5 parts by mass or more, and still more preferably 5 parts by mass or more with respect to 100 parts by mass in total of the components (A) and (B). When the lower limit of the content of the component (D) is within the above range, the cured product can exhibit better reworkability. Further, the upper limit of the content of the component (D) is not particularly limited, and may be 20 parts by mass, 15 parts by mass, 10 parts by mass, or 8 parts by mass with respect to 100 parts by mass in total of the components (A) and (B).

[0065] Other components The active energy ray-curable resin composition of the present invention may be appropriately added with a polymerization inhibitor, an adhesion promoter, a leveling agent, an antifoaming agent, an antioxidant, a flame retardant, a colorant (pigment, dye), etc. according to its purpose and the like.

[0066] The viscosity of the active energy ray-curable resin composition of the present invention measured at 25 °C using a Brookfield RV viscometer (spindle No. 67) under the condition of a rotation speed of 1 rpm is preferably from 200,000 to 700,000 mPa·s, and more preferably from 300,000 to 600,000 mPa·s. When the viscosity is within the above range, the dischargeability of the active energy ray-curable resin composition is further improved, and a higher aspect ratio can be exhibited.

[0067] The viscosity of the active energy ray-curable resin composition of the present invention, measured at 25°C using a Brookfield RV viscometer (spindle No. 7) under the condition of a rotation speed of 10 rpm, is preferably 30,000 to 80,000 Pa·s, and more preferably 40,000 to 70,000 mPa·s. When the viscosity is within the above range, the dischargeability of the active energy ray-curable resin composition is further improved, the hardness of the cured product is lower, and a higher aspect ratio can be exhibited.

[0068] The TI value of the active energy ray-curable resin composition of the present invention is preferably 5.0 to 8.0, and more preferably 6.0 to 7.0. When the Ti value is within the above range, the dischargeability of the active energy ray-curable resin composition is further improved, and a higher aspect ratio can be exhibited.

[0069] In this specification, the viscosity measured under the above conditions of rotation speeds of 1 rpm and 10 rpm, and the measurement of the TI value are carried out according to the measurement methods described in the examples.

[0070] The aspect ratio of the cured product of the active energy ray-curable resin composition of the present invention is preferably 0.60 or more, and more preferably 0.70 or more. When the aspect ratio is within the above range, it is possible to obtain the bead height of the cured product under a wide range of coating conditions, and as an alternative to the molded foamed gasket, it is easier to adjust the shape of parts such as those for CIPG applications formed by the cured product to a desired shape. Also, the upper limit of the aspect ratio is not particularly limited and may be 1.0 or the like.

[0071] In this specification, the measurement of the aspect ratio of the above-mentioned cured product is carried out according to the measurement method described in the examples.

[0072] The hardness of the cured product of the active energy ray-curable resin composition of the present invention, measured by a measurement method compliant with ASTM D2240, is preferably 80 or less, and more preferably 70 or less. When the hardness is within the above range, creep deformation of the component housing where the CIPG is applied and bonded can be further suppressed.

[0073] In this specification, the measurement of the above-mentioned hardness is carried out according to the measurement method described in the examples.

[0074] The method for producing the active energy ray-curable resin composition of the present invention is not particularly limited and can be produced by a conventional method. For example, the above components (A) to (D) and, if necessary, other components can be kneaded using a kneader capable of adjusting the temperature, such as a planetary mixer, a twin-screw mixer, a high-shear mixer, a butterfly mixer, etc., to produce the composition.

[0075] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to such examples, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Examples

[0076] Examples and comparative examples are shown below to explain the present invention in more detail. However, the present invention is not limited to the examples.

[0077] The raw materials used in the examples and comparative examples are as follows.

[0078] Component (A) ·(A1): Urethane acrylate (polyether-based skeleton), Mw 50000, product name Art Resin PMH-101B ·(A2): Urethane acrylate (polyether-based skeleton), Mw 75000, product name Art Resin PMH-201B

[0079] Component (B) ·(B1): Phenoxyethyl acrylate, product name: Light Acrylate PO-A (manufactured by Kyoeisha Chemical Co., Ltd.), Tg -22°C ·(B2): Ethoxy·diethylene glycol acrylate, product name: Light Acrylate EC-A (manufactured by Kyoeisha Chemical Co., Ltd.), Tg -70°C ·(B3-1): Isodecyl acrylate (C10), product name: IDAA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), Tg -62°C ·(B3-2): Lauryl acrylate (C12), Product name: LA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), Tg -23°C

[0080] Component (C) ·(C1): Type II, Methyl benzoylformate, Product name Omnirad-MBF (manufactured by iGM RESINS) ·(C2): Type II, 4-Methylbenzophenone, Product name Omnirad 4MBZ-FLAKES (manufactured by iGM RESINS) ·(C3): α-Hydroxyacetophenone type (1-Hydroxycyclohexyl phenyl ketone), Product name Omnirad-184 (manufactured by iGM RESINS) ·(C4): Acylphosphine oxide type (Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, Product name Omnirad-819 (manufactured by iGM RESINS)

[0081] Component (D) ·(D1): Hydrophilic fumed silica, Product name Rheole Seal QS-20L (manufactured by Tokuyama)

[0082] (Examples and Comparative Examples) Using a rotation-revolution mixer model ARE-310 (manufactured by Shin-Kee) and the above-mentioned raw materials in the blending amounts shown in Table 1, first, components (A), (B), and (C) were mixed and stirred at room temperature at 2000 rpm for 15 minutes. Next, component (D) was added and mixed and stirred for 15 minutes, and further stirred for 2 minutes and 30 seconds in the degassing mode to perform degassing, thereby producing an active energy ray-curable resin composition.

[0083] (Evaluation Method) The following evaluations were performed on the examples and comparative examples.

[0084] Viscosity · TI value The viscosity at 25°C was measured using a Brookfield RV viscometer (Spindle No. 6) under the conditions of a rotation speed of 1 rpm and 10 rpm. Based on the measurement results, the ratio (η1 / η2) of the viscosity at 1 rpm (η1) to the viscosity at 10 rpm (η2) was calculated and used as the TI value. These were measured after leaving the active energy ray-curable resin composition standing in an environment of 25°C for 1 day after production.

[0085] Aspect ratio Using a dispenser (model ML-6000X) manufactured by Musashi Engineering Co., Ltd., after temperature-adjusting the active energy ray-curable resin composition to 25.0°C, it was applied at a coating speed of 30 mm / s with a bead width of 1000 μm ± 100 μm at a discharge pressure between 30 and 150 Kpa using an 18G needle (inner diameter 0.92 mm). After UV irradiation, the cross-section of the bead was cut, and the width and height of the cross-sectional shape were measured using a microscope (manufactured by Keyence Corporation), and the aspect ratio was calculated by the following formula. Aspect ratio = H / W H: Bead height W: Bead width Based on the calculated aspect ratio, evaluation was carried out according to the following evaluation criteria. Note that if the evaluation is Δ or above, it is evaluated that there is no problem in actual use. 〇: 0.70 or more △: Less than 0.60 to 0.70 ×: Less than 0.60

[0086] Hardness The active energy ray-curable resin composition adjusted to a thickness of 2 mm was irradiated with UV using a high-pressure mercury lamp as a light source using a UV irradiation device (LIGHT HAMMER 6 manufactured by Fusion UV systems) at an illuminance of 300 mW / cm 2 at 5000 mJ / cm 2It was irradiated so as to obtain an integrated light quantity and cured to prepare a cured product. The cured product was cut into a size of 2 cm × 3 cm, and five pieces were stacked to prepare a test piece with a thickness of about 10 mm. After the test piece was equilibrated in a thermostat at 25°C, the hardness of the test piece was measured using a Type OO durometer by a measurement method conforming to ASTM D2240.

[0087] Reworkability An active energy ray-curable resin composition was applied to a SUS plate (size: 5 cm × 15 cm) so that the width was 1000 ± 150 μm, the height was 750 μm ± 50 μm, and the length was 11 cm under the same apparatus and conditions as the measurement method of the above aspect ratio. The application was performed by applying two beads of the active energy ray-curable resin composition in parallel at an interval of 2 cm. Next, with the same UV irradiation apparatus and light source as in the above hardness measurement, the illuminance was 300 mW / cm 2 and it was irradiated so as to obtain an integrated light quantity of 5000 mJ / cm 2 and cured to prepare a cured product. Both ends of 5 mm were cut so that the length of the bead-shaped cured product became 10 cm. Next, using an aluminum spacer with a thickness of 0.5 mm, it was sandwiched with a SUS plate of the same size so that the compression ratio was about 30%, and clamped and fixed until the SUS plate adhered to the spacer to prepare a test piece. Next, the test piece was exposed in an oven at 70°C for 3 hours and then left in an environment at 25°C for 69 days. The clamp was removed and evaluated according to the following evaluation criteria. 〇: The SUS plate can be easily peeled off by hand without resistance, and no residue remains on the peeled surface of the SUS plate. △: It can be peeled off with resistance but can be peeled off by applying force by hand, and no residue remains on the peeled surface of the SUS plate. ×: The adhesion is strong and the SUS plate cannot be peeled off even by applying force by hand.

[0088] Dynamic viscoelasticity (storage elastic modulus G', peak temperature of Tanδ, peak height of Tanδ) A silicon rubber sheet with a thickness of 2 mm was prepared in a rectangular frame shape as a spacer. Next, the spacer was placed on a release-treated aluminum plate, and an active energy ray-curable resin composition was poured into the frame of the spacer. Quartz glass was prepared and superimposed so as to be in contact with the active energy ray-curable resin composition, and compressed. In this state, with the same UV irradiation device and light source as in the above hardness measurement, the integrated light quantity was 5000 mJ / cm 2 at an illuminance of 300 mW / cm 2 and ultraviolet irradiation was performed under the condition of becoming. The quartz glass was peeled off, and a sample for measuring dynamic viscoelasticity was prepared. Using the sample prepared as described above, with a dynamic viscoelasticity measuring device (manufactured by TA Instruments: model HR-10), in a rotational shear mode at a frequency of 1 Hz, in a temperature range of -70 °C to 70 °C, a temperature increase rate of 5 °C / min Dynamic viscoelasticity measurement (heating process) was performed under the heating condition. The peak temperature of Tanδ, the peak height, and the storage elastic modulus G' at 25 °C obtained by the measurement were used as the measured values.

[0089] Extrudability In the same manner as the above-described method for measuring the aspect ratio, an apparatus and a SUS plate were prepared. After the temperature of the active energy ray-curable resin composition was adjusted to 25.0 °C, under the conditions of using a coating spatula at a coating pressure of 150 kPa and a 18G nozzle at 30 mm / s, the gap between the SUS plate and the nozzle tip was adjusted to 6.0 mm, and the active energy ray-curable resin composition was applied to a length of 11 cm. The weight of the applied active energy ray-curable resin composition was measured, and the dischargeability was evaluated according to the following evaluation criteria using this as the discharge amount. ◎: Discharge amount of 0.3 g or more 〇: Discharge amount of 0.15 or more and less than 0.3 g △: Discharge amount of 0.05 g or more and less than 0.15 g ×: Discharge amount of less than 0.05 g

[0090] The results are shown in Table 1. In Table 1, the numerical values of the formulation represent parts by mass, and the total of component (A) and component (B) is 100 parts by mass.

[0091]

Table 1

Claims

1. An active energy ray-curable resin composition containing the following components (A), (B), (C), and (D), (A) A urethane acrylate oligomer having a urethane skeleton with an ether bond and a weight average molecular weight of 40,000 to 80,000, (B) A monofunctional acrylate monomer, (C) A photopolymerization initiator, (D) Fumed silica, wherein the component (C) contains a benzophenone compound, The cured product with a thickness of 2 mm obtained by irradiating the active energy ray-curable resin composition with ultraviolet rays under the condition of an integrated light quantity of 5000 mJ / cm 2 using a high-pressure mercury lamp has a storage elastic modulus G' at 25°C measured under the conditions of a rotational shear mode with a vibration frequency of 1 Hz, a temperature increase rate of 5°C / min, and a temperature range of -70°C to 70°C using a dynamic viscoelasticity apparatus of 400000 Pa or less, a peak temperature of Tanδ of -10°C or less, and a peak height of Tanδ of 1.5 or less. and being characterized by the above. An active energy ray-curable resin composition.

2. The active energy ray-curable resin composition according to Claim 1, wherein the cured product has a hardness at 25°C of 70 or less as measured with a Type OO durometer by a measuring method conforming to ASTM D2240.

3. The active energy ray-curable resin composition according to Claim 1, wherein the content of the component (A) is 15 to 30% by mass based on 100% by mass of the total content of the component (A) and the component (B).

4. The component (B) contains the following components (B1), (B2), and (B3), (B1) Phenoxyethyl acrylate, (B2) An alkyl acrylate having a diethylene glycol skeleton, (B3) An alkyl acrylate having 8 or more carbon atoms, wherein the content of the component (B2) is 30% by mass or less based on 100% by mass of the total content of the components (B1), (B2), and (B3), and the content of the component (B3) is 35% by mass or less based on 100% by mass of the total content of the components (B1), (B2), and (B3). The active energy ray-curable resin composition according to Claim 1.

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