Urethane composition, cured product, and heat dissipation adhesive

Abstract

The purpose of the present invention is to provide a urethane composition which is excellent in terms of handleability at normal temperature, has flexibility when cured, and is capable of maintaining high mechanical properties.　A urethane composition according to the present disclosure contains an ester-based polyol and a polyisocyanate, the ester-based polyol contains at least two or more kinds of diol compounds, the difference in SP value between a diol compound (A) that has the lowest SP value among the diol compounds and the other diol compounds (B) is 1.3 or less, and the content of the diol compound (A) is 1-55 mass% of the total amount of the ester-based polyol.

Description

Urethane composition, cured product, and heat-dissipating adhesive

[0001] This disclosure relates to a urethane composition, a cured product, and a heat-dissipating adhesive. This application claims priority from Japanese Patent Application No. 2024-093292, filed on June 7, 2024, the contents of which are incorporated herein by reference.

[0002] It is known to use a urethane-based composition containing a specific ester-based polyol, polyisocyanate, and filler to support large electronic components such as EV batteries while dissipating (radiating) heat generated by the components to the outside (for example, Patent Document 1).

[0003] Special Publication No. 2020-533467

[0004] However, the urethane-based composition disclosed in Patent Document 1 has the problem that the resin becomes too hard after curing and is still susceptible to breakage due to vibration or impact.

[0005] In addition, while it is conceivable to polymerize the ester polyol to impart flexibility, there is a concern that the polymerized ester polyol will be prone to crystallization and will be less easy to handle. Furthermore, when the ester polyol is polymerized, the content of polyisocyanate is relatively reduced, which causes a problem of reduced mechanical properties such as tensile strength and tensile elongation.

[0006] Therefore, an object of the present disclosure is to provide a urethane composition that has excellent handleability at room temperature, flexibility when cured, and can maintain high mechanical properties.

[0007] As a result of earnest efforts to solve the above problems, the inventors of the present disclosure have found that a composition containing an ester polyol and a polyisocyanate, wherein the ester polyol contains at least two or more diol compounds, and wherein the difference in SP value between a diol compound (A) having the lowest SP value among the diol compounds and other diol compounds (B) and the content of the diol compound (A) are within specific ranges, can provide excellent handleability at room temperature, flexibility when cured, and high mechanical properties. The present disclosure relates to a composition completed based on these findings.

[0008] That is, the present disclosure provides a urethane composition comprising an ester-based polyol and a polyisocyanate, wherein the ester-based polyol comprises at least two or more diol compounds, wherein the difference in SP value between a diol compound (A) having the lowest SP value among the diol compounds and other diol compounds (B) is 1.3 or less, and the content of the diol compound having the lowest SP value is 1 to 55 mass% of the total amount of the ester-based polyol.

[0009] The urethane composition contains an ester polyol and a polyisocyanate, the ester polyol containing at least two or more diol compounds, and the difference in SP value between the diol compound (A) having the lowest SP value among the diol compounds and the other diol compounds (B) is 1.3 or less, thereby enabling the diol compounds to be compatible with each other and maintaining excellent mechanical properties after curing. Furthermore, the content of the diol compound (A) is 1 to 55 mass% of the total amount of the ester polyol, thereby enabling the composition to have flexibility when cured and excellent room temperature handleability.

[0010] In the urethane composition, the content of the diol compound (B) is preferably 45 to 99% by mass based on the total amount of the ester polyol.

[0011] The number average molecular weight of the diol compound (A) is preferably 1,000 to 3,000.

[0012] The diol compound (B) preferably contains a structural moiety derived from an alicyclic diol compound.

[0013] The urethane composition preferably contains a filler.

[0014] The present disclosure provides a cured product of the urethane composition.

[0015] The present disclosure also provides a heat-dissipating adhesive comprising the above-described cured product.

[0016] The urethane composition of the present disclosure has excellent handleability at room temperature, and when cured, it has flexibility and can maintain high mechanical properties.

[0017] [Urethane Composition] A urethane composition according to one embodiment of the present disclosure (hereinafter, may be referred to as the "urethane composition of the present disclosure") comprises an ester polyol and a polyisocyanate, the ester polyol comprises at least two or more diol compounds, the difference in SP value between a diol compound (A) having the lowest SP value among the diol compounds and the other diol compounds (B) is 1.3 or less, and the content of the diol compound (A) is 1 to 55% by mass of the total amount of the ester polyol.

[0018] In the urethane composition of the present disclosure, the ester polyol contains at least two or more diol compounds, and the difference in SP value between the diol compound (A) with the lowest SP value among the diol compounds and the other diol compounds (B) is 1.3 or less, thereby enabling the diol compounds to be compatible with each other and maintaining excellent mechanical properties after curing. Furthermore, the content of the diol compound (A) with the lowest SP value is 1 to 55 mass% of the total amount of the ester polyol, thereby enabling the composition to have flexibility when cured and excellent room-temperature handleability.

[0019] In the present disclosure, the SP value means the Hildebrand solubility parameter (δ) at 25°C.

[0020] (Ester polyol) The ester polyol contains at least two or more diol compounds, and the difference in SP value between the diol compound with the lowest SP value and the other diol compounds is 1.3 or less. In the present disclosure, "ester polyol" refers to a compound in which two or more monomer units containing an ester bond in the molecule are polymerized and have two or more hydroxyl groups. In addition, the ester polyol may contain one or more ester polyols other than the diol compound.

[0021] In the above-mentioned ester-based polyol, the difference in SP value between the diol compound (A) with the lowest SP value and the other diol compounds (B) is 1.3 or less, preferably 1.25 or less, and more preferably 1.22 or less. The above-mentioned structure allows the diol compounds to be compatible with each other, and excellent mechanical properties can be exhibited when cured. The lower limit is not particularly limited, but may be 0 or more. When three or more diol compounds are contained, the SP value of the diol compound (A) with the lowest SP value is compared with the SP value calculated as the mass average value of the other diol compounds (B).

[0022] The viscosity of the ester polyol as a mixture at 25°C is preferably 5000 mPa s or less, more preferably 4000 mPa s or less, and even more preferably 3000 mPa s or less. A viscosity of 5000 mPa s or less ensures sufficient fluidity and superior room temperature handleability. The lower limit is not particularly limited, but is preferably 10 mPa s or more, more preferably 100 mPa s or more. The viscosity is measured using an E-type viscometer.

[0023] When the ester polyol mixture is mixed with a filler in a proportion of 70 to 80% by mass, the viscosity at 25°C at at least one measurement point is preferably 30 Pa·s or less, more preferably 25 Pa·s or less, and even more preferably 21 Pa·s or less. A viscosity of 30 Pa·s or less ensures sufficient fluidity and superior room temperature handleability. The lower limit is not particularly limited, but may be 0.1 Pa·s or more. It is also preferable that the above viscosity be satisfied over the entire range when the filler is mixed in a proportion of 70 to 80% by mass. The viscosity when the filler is mixed is measured using a rheometer.

[0024] The ester polyol preferably has a transparent appearance when mixed. A transparent appearance makes it possible to confirm that the ester polyols contained therein are compatible with each other, and makes it easier for the polyol to exhibit excellent mechanical properties when cured.

[0025] The mixture of ester-based polyols is preferably liquid at any one of room temperatures. In the present disclosure, "room temperature" means 20 to 30°C.

[0026] <Diol Compound (A) with the Lowest SP Value> The diol compound (A) with the lowest SP value is a component that imparts hydrolysis resistance and flexibility to the urethane composition after curing. Hereinafter, the "diol compound (A) with the lowest SP value" may be simply referred to as the "diol compound (A)." Specific examples of the diol compound (A) include polyols that are condensation polymers of polyhydric alcohols and polycarboxylic acids, and polyols that are ring-opening polymers of cyclic esters (lactones). When two or more compounds corresponding to the diol compound (A) are contained, any one of them is treated as the diol compound (A), and the others are treated as other diol compounds (B).

[0027] The SP value of the diol compound (A) is preferably 10 or less, more preferably 9.8 or less, and even more preferably 9.7 or less. The lower limit is preferably 9.0 or more. When the SP value is within the above range, the difference in SP value with the other diol compound (B) can be adjusted, making it easier to achieve compatibility.

[0028] The number average molecular weight of the diol compound (A) is not particularly limited, but is preferably 1000 to 3000, more preferably 1300 to 2700, and even more preferably 1600 to 2400. When the number average molecular weight is within the above range, the urethane composition of the present disclosure has excellent handleability at room temperature and is more likely to be imparted with flexibility when cured.

[0029] The hydroxyl value of the diol compound (A) is preferably 20 to 80 KOHmg / g, more preferably 30 to 70 KOHmg / g, and even more preferably 40 to 60 KOHmg / g.

[0030] The acid value of the diol compound (A) is preferably 1.0 KOHmg / g or less, more preferably 0.5 KOHmg / g or less. When the acid value is within the above range, hydrolysis can be suppressed.

[0031] The content of the diol compound (A) is 1 to 55% by mass, preferably 1.5 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 15 to 40% by mass, based on the total amount (100% by mass) of the ester polyol. By having the content of the diol compound (A) be 1% by mass or more, flexibility and hydrolysis resistance can be exhibited when cured. Furthermore, by having the content be 55% by mass or less, excellent room temperature handleability can be achieved, and mechanical properties can be maintained when cured.

[0032] <Other Diol Compounds (B)> The other diol compound (B) is a component added to the urethane composition of the present disclosure to impart mechanical properties such as tensile strength and tensile elongation and to exhibit impact resistance. Hereinafter, "other diol compound (B)" may be simply referred to as "diol compound (B)." Examples of the diol compound (B) include polyols that are condensation polymers of polyhydric alcohols and polycarboxylic acids, and polyols that are ring-opening polymers of cyclic esters (lactones), but are not included in the diol compound (A). Among these, the diol compound (B) preferably contains a polyol that is a ring-opening polymer of cyclic esters (lactones), and more preferably contains a structural moiety derived from an alicyclic diol compound to exhibit excellent mechanical properties upon curing. Specifically, the diol compound (B) preferably contains one obtained by ring-opening polymerization of lactones using the alicyclic diol compound as an initiator. The diol compound (B) may be used alone or in combination of two or more types.

[0033] Examples of the alicyclic diol compound include cyclohexanediols such as 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 2-methyl-1,4-cyclohexanediol, cyclohexanedimethanols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol, norbornanedimethanols such as 2,3-norbornanedimethanol and 2,5-norbornanedimethanol, tricyclodecane dimethanol, pentacyclopentadecanedimethanol, 1,3-adamantanediol, 2,2-adamantanediol, decalindimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and isosorbide, with cyclohexanedimethanols being preferred, and 1,4-cyclohexanedimethanol being particularly preferred. Note that the alicyclic diol compound may be used alone or in combination of two or more.

[0034] Specific examples of the lactones include β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, δ-caprolactone, ε-caprolactone, γ-valerolactone, γ-caprolactone, γ-caprylolactone, γ-laurolactone, enantholactone, dodecanolactone, stearolactone, alkyl-ε-caprolactone [for example, monomethyl-ε-caprolactone (α-methyl-ε-caprolactone, β-methyl- Examples of suitable lactones include lactones having 4 to 20 carbon atoms (preferably lactones having 4 to 15 carbon atoms, more preferably lactones having 4 to 10 carbon atoms), such as methyl-ε-caprolactones such as ε-caprolactone, γ-methyl-ε-caprolactone, dimethyl-ε-caprolactone (β,δ-dimethyl-ε-caprolactone), and trimethyl-ε-caprolactone (3,3,5-trimethyl-ε-caprolactone), and ε-caprolactone is preferred. That is, the lactone polyol of the present disclosure is preferably a polycaprolactone polyol. Note that only one type of lactone may be used, or two or more types may be used.

[0035] The number average molecular weight of the diol compound (B) is not particularly limited, but is preferably 300 to 800, more preferably 350 to 700, and even more preferably 400 to 600. When the number average molecular weight of the diol compound (B) is 800 or less, excellent room temperature handleability can be obtained.

[0036] The SP value of the diol compound (B) is preferably 11.3 or less, more preferably 11 or less, and even more preferably 10.7 or less. The lower limit is preferably more than 10. When the SP value is within the above range, the difference in SP value with the diol compound (A) can be adjusted, making it easier to achieve compatibility. When two or more types of diol compounds (B) are contained, it is preferable that the SP value calculated as the mass average thereof falls within the above range.

[0037] The content of the diol compound (B) is preferably 45 to 99 mass%, more preferably 50 to 98.5 mass%, even more preferably 60 to 95 mass%, and particularly preferably 60 to 85 mass%, of the total amount (100 mass%) of the ester polyol. When the content of the diol compound (B) is 45 mass% or more, excellent mechanical properties can be exhibited when cured. Furthermore, when the content is 99 mass% or less, excellent room temperature handleability can be achieved, and excellent flexibility can be imparted when cured.

[0038] The total content of the diol compound (A) and the diol compound (B) is preferably 95% by mass or more, more preferably 99% by mass or more, and may be 100% by mass, based on the total amount (100% by mass) of the ester polyol.

[0039] (Polyisocyanate) The urethane composition of the present disclosure contains a polyisocyanate. The polyisocyanate acts as a curable component in the urethane composition of the present disclosure. In the urethane composition of the present disclosure, only one type of polyisocyanate may be used, or two or more types may be used. In this disclosure, "polyisocyanate" refers to a compound having two or more isocyanate groups (i.e., bifunctional or higher).

[0040] From the viewpoint of ease of handling, the polyisocyanate is preferably a non-aromatic polyisocyanate, more preferably an aliphatic polyisocyanate or an alicyclic polyisocyanate, and particularly preferably an aliphatic polyisocyanate.

[0041] Furthermore, from the viewpoint of reducing the crystallinity of the urethane composition, the polyisocyanate preferably contains a tri- or higher functional isocyanate, and from the viewpoint of exhibiting tensile strength and elongation of the cured product, it is more preferable that the polyisocyanate contains a bifunctional isocyanate and a tri- or higher functional isocyanate, and it is particularly preferable that the polyisocyanate contains a bifunctional isocyanate and a trifunctional isocyanate.

[0042] Specific examples of the bifunctional isocyanate include aliphatic polyisocyanates such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and decamethylene diisocyanate; and alicyclic polyisocyanates such as 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, 1,4-bis(isocyanatemethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and norbornene diisocyanate.

[0043] Examples of the tri- or higher functional isocyanates include oligomers of the compounds exemplified as the bifunctional isocyanates, and trimers of the bifunctional isocyanates are particularly preferred.

[0044] The urethane composition of the present disclosure preferably contains hexamethylene diisocyanate and hexamethylene diisocyanate trimer.

[0045] Furthermore, when the polyisocyanate contains a trifunctional isocyanate, its content is preferably less than 45% by mass, more preferably 40% by mass or less, and even more preferably 35% by mass or less, based on the total amount of polyisocyanate (100% by mass). A trifunctional isocyanate content of less than 45% by mass makes it easier for the cured product to exhibit sufficient tensile strength and elongation. Furthermore, since trifunctional isocyanates are usually expensive, costs can also be reduced. The lower limit is preferably 5% by mass or more, more preferably 10% by mass or more. A content of 5% by mass or more makes it easier to suppress crystallization of the urethane composition.

[0046] In the urethane composition of the present disclosure, the ratio of the number of moles of isocyanate groups in the polyisocyanate to the number of moles of hydroxyl groups in the ester polyol [NCO / hydroxyl] is preferably in the range of 0.8 to 1.5, more preferably 0.85 to 1.4, and even more preferably 0.9 to 1.3. That is, in the urethane composition of the present disclosure, the ratio of the number of moles of structural units derived from isocyanate groups to the number of moles of structural units derived from hydroxyl groups other than those forming ester bonds in the ester polyol is preferably within the above range.

[0047] The urethane composition of the present disclosure preferably contains a catalyst to promote the reaction between the ester polyol and the polyisocyanate. Known or conventional catalysts can be used as the catalyst, including amine catalysts, imidazole catalysts, and metal catalysts. Only one type of catalyst may be used, or two or more types may be used.

[0048] Examples of the amine catalyst include triethylenediamine, 2-methyltriethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropylenediamine, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N',N",N"-pentamethyl-(3-aminopropyl)ethylenediamine, N,N,N',N",N"-pentamethyldipropylenetriamine, N,N,N',N"-tetramethylhexamethylenediamine, and bis(2-dimethylaminoethyl)ether.

[0049] Examples of the imidazole catalyst include 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, and 1-dimethylaminopropylimidazole.

[0050] Examples of the metal catalyst include organotin catalysts such as stannous diacetate, stannous dioctoate, stannous dioleate, stannous dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, and dioctyltin dilaurate.

[0051] The content of the catalyst is preferably 10 to 10,000 ppm, and more preferably 50 to 5,000 ppm, based on the total amount (100 parts by mass) of the resin components in the urethane composition.

[0052] The urethane composition of the present disclosure may also contain a filler to ensure sufficient heat dissipation when cured. Only one type of filler may be used, or two or more types may be used.

[0053] As the filler, known or commonly used fillers can be used, such as metal fillers, carbon fillers, and metal oxide fillers. Examples of metal fillers include metal fillers made of gold, silver, copper, nickel, palladium, tin, aluminum, or alloys thereof. The metal filler may be made of a single metal, or may be made of two or more metals, such as a core-shell structure.

[0054] The shape of the filler may be spherical, irregular, flake (flat), needle, fiber, rod, etc. The average particle size (median size) is preferably 1 nm to 100 μm, more preferably 10 nm to 50 μm, even more preferably 30 nm to 35 μm, and particularly preferably 50 nm to 10 μm.

[0055] When the filler is contained, the content thereof is preferably 50 to 95 mass %, more preferably 60 to 93 mass %, and even more preferably 70 to 90 mass %, of the total amount (100 mass %) of the urethane composition. When the filler content is within the above range, heat dissipation properties are easily exhibited.

[0056] (Other Components) The urethane composition of the present disclosure may contain other components in addition to the ester polyol, polyisocyanate, catalyst, and filler. Examples of the other components include polyols other than the ester polyols, light stabilizers, UV absorbers, antioxidants, solvents, flame retardants, pigments, antimicrobial agents, antistatic agents, processing aids, and viscosity improvers. The content of the other compounds is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass, relative to the total amount (100% by mass) of the urethane composition of the present disclosure.

[0057] Furthermore, of the total amount (100% by mass) of polyols contained in the urethane composition of the present disclosure, the content of the above-mentioned ester-based polyol is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.

[0058] The urethane composition of the present disclosure can be prepared by mixing the above-described components by a known or conventional method. In particular, the urethane composition of the present disclosure is preferably a two-component urethane composition containing the above-described ester polyol as a base component and the above-described polyisocyanate as a curing agent.

[0059] [Cured Product] A cured product of the urethane composition can be produced by curing the urethane composition of the present disclosure by a known or conventional method. In particular, when the urethane composition of the present disclosure is a two-component urethane composition, it may be cured by heating or at room temperature. When curing by heating, the heating temperature is preferably 25 to 150°C. The curing time may be 0.5 to 20 hours.

[0060] The cured product preferably has an A hardness of 40 to 69, more preferably 43 to 66, and even more preferably 46 to 63, when measured at a thickness of 6 mm or more. An A hardness of 69 or less provides flexibility to the cured product, making it easier to exhibit impact resistance. Furthermore, an A hardness of 40 or more can prevent the cured product from breaking due to being too soft.

[0061] Furthermore, when the cured product contains 70 to 80% by mass of filler, the A hardness measured by the same method as above is preferably 70 to 89, more preferably 75 to 85. Having an A hardness of 89 or less while containing filler makes it easier for the cured product to have flexibility and exhibit impact resistance. Furthermore, having an A hardness of 70 or more can prevent the cured product from being too soft and breaking. Note that it is preferable for the above range to be satisfied at at least one measurement point when the filler is mixed at a ratio of 70 to 80% by mass, and it is more preferable for the above viscosity to be satisfied over the entire range when the filler is mixed at a ratio of 70 to 80% by mass.

[0062] The tensile strength at break of the cured product, measured using a No. 3 dumbbell at a pulling speed of 500 mm / min and a chuck distance of 60 mm, is preferably 5 MPa or more, more preferably 7 MPa or more, and even more preferably 10 MPa or more. A tensile strength of 5 MPa or more ensures sufficient strength. There is no particular upper limit, but a value of 50 MPa or less is preferred.

[0063] Furthermore, when the cured product contains 70 to 80% by mass of filler, the tensile strength at break, measured by the same method as above, is preferably 4 MPa or more, more preferably 4.5 MPa or more. A tensile strength of 4 MPa or more ensures sufficient strength. The upper limit is not particularly limited, but is preferably 30 MPa or less. It is preferable that the above range is satisfied at at least one measurement point when the filler is mixed at a ratio of 70 to 80% by mass, and it is more preferable that the above viscosity is satisfied over the entire range when the filler is mixed at a ratio of 70 to 80% by mass.

[0064] The cured product preferably has an elongation at break of 200% or more, more preferably 250% or more, and even more preferably 300% or more, measured under the same conditions as the tensile strength. Having an elongation of 200% or more makes it easier for the cured product to exhibit impact resistance. While there is no particular upper limit, it is preferably 600% or less.

[0065] Furthermore, when the cured product contains 70 to 80% by mass of filler, the elongation at break measured under the same conditions is preferably 100% or more, more preferably 140% or more, and even more preferably 160% or more. Having an elongation of 100% or more can facilitate the cured product's impact resistance. While there is no particular upper limit, a value of 400% or less is preferred. It is preferable that the viscosity satisfy the above range at at least one measurement point when the filler is mixed at a ratio of 70 to 80% by mass, and it is more preferable that the viscosity satisfy the above range over the entire range when the filler is mixed at a ratio of 70 to 80% by mass.

[0066] The cured product preferably has a shear adhesive strength of 2.0 MPa or more, more preferably 2.2 MPa or more, measured on a test piece prepared by bonding two Al substrates together at a test speed of 5 mm / min and a chuck distance of 112.5 mm according to JIS K 6850. The upper limit is not particularly limited, but is preferably 10 MPa or less.

[0067] Furthermore, when the cured product contains 70 to 80% by mass of filler, the shear adhesive strength between aluminum substrates measured under the same conditions is preferably 1.5 MPa or more, more preferably 1.7 MPa or more. The upper limit is not particularly limited, but is preferably 10 MPa or less. It is preferable that the viscosity satisfy the above range at at least one measurement point when the filler is mixed at a ratio of 70 to 80% by mass, and it is more preferable that the viscosity satisfy the above range over the entire range when the filler is mixed at a ratio of 70 to 80% by mass.

[0068] The cured product preferably has a shear adhesive strength of 1.9 MPa or more, more preferably 2.0 MPa or more, measured on a test piece prepared by laminating an Al substrate and a PET substrate at a test speed of 5 mm / min and a chuck distance of 112.5 mm according to JIS K 6850. The upper limit is not particularly limited, but is preferably 10 MPa or less.

[0069] Furthermore, when the cured product contains 70 to 80% by mass of filler, the shear adhesive strength to an Al substrate and a PET substrate measured under similar conditions is preferably 1.5 MPa or more, more preferably 1.7 MPa or more. The upper limit is not particularly limited, but is preferably 10 MPa or less. It is preferable that the above range be satisfied at at least one measurement point when the filler is mixed at a ratio of 70 to 80% by mass, and it is more preferable that the above viscosity be satisfied over the entire range when the filler is mixed at a ratio of 70 to 80% by mass.

[0070] The cured product preferably exhibits a shear adhesive strength of at least 50% of the shear adhesive strength before storage when measured under the same conditions after 500 hours at 85°C and 85% RH using a test piece formed by bonding two Al substrates together.

[0071] The cured product has excellent flexibility while maintaining sufficient mechanical properties, and can therefore be used as an impact-resistant adhesive, and is particularly suitable as an impact-resistant adhesive for use in large, highly vibrating devices such as automobiles, trains, and aircraft. Furthermore, the cured product maintains sufficient mechanical properties and flexibility even when it contains a filler, and furthermore has heat dissipation properties, and can therefore be suitably used as a power semiconductor sealant or heat-dissipating adhesive that generates a large amount of heat and has a high output.

[0072] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, and other modifications of configurations are possible as appropriate within the scope of the present disclosure. The present disclosure is not limited by the embodiments, but is limited only by the claims.

[0073] Hereinafter, one embodiment of the present disclosure will be described in more detail based on examples.

[0074] Example 1 41 parts by mass of polyol 1 (1,4-cyclohexanedimethanol-modified polycaprolactone diol Mw: 530, SP value: 10.61, other diol compound (B)), 2 parts by mass of polyol 2 (liquid bifunctional polyol Mw: 2000, hydroxyl value: 56.8 KOHmg / g, SP value: 9.66, diol compound (A) with the lowest SP value), 12 parts by mass of hexamethylene diisocyanate (HDI: manufactured by Tosoh Corporation), 5 parts by mass of HDI trimer (trade name "Duranate", manufactured by Asahi Kasei Corporation), and a catalyst DBTDL concentration of 100 ppm were weighed into a measuring vessel for stirring. The blended raw materials were stirred and vacuum degassed for 60 seconds using a vacuum degassing mixer (trade name "Vacuum Foam Mixer", manufactured by Thinky Corporation), to produce the urethane composition of Example 1. The urethane composition of Example 1 was then poured into a casting mold prepared by sandwiching a silicone spacer between glass plates, and after pouring, the composition was cured for 16 hours or more in a gear oven set at 30°C to obtain a cured product. The cured product was released from the glass mold, aged for 2 days or more, and then used to measure various physical properties.

[0075] Examples 2 and 3, Comparative Examples 1 to 6 Urethane compositions and their cured products were prepared in the same manner as in Example 1, except that the contents shown in Table 1 were used.

[0076] Example 4 27 parts by mass of polyol 1 (1,4-cyclohexanedimethanol-modified polycaprolactone diol, Mw: 530, SP value: 10.61, other diol compound (B)), 7 parts by mass of polyol 2 (liquid bifunctional polyol, Mw: 2000, hydroxyl value: 56.8 KOHmg / g, SP value: 9.66, diol compound (A) with the lowest SP value), 8 parts by mass of hexamethylene diisocyanate (HDI: manufactured by Tosoh Corporation), 3 parts by mass of HDI trimer (trade name "Duranate" manufactured by Asahi Kasei Corporation), 105 parts by mass of alumina filler (trade name "AS-40" manufactured by Resonac Corporation), and the catalyst DBTDL were weighed into a measuring vessel for stirring so as to be 100 ppm relative to the total amount of resin components. The blended raw materials were stirred and vacuum degassed for 60 seconds using a vacuum degassing mixer (product name "Vacuum Foam Mixer", manufactured by Thinky Corporation) to produce the urethane composition of Example 4. The urethane composition of Example 4 was then poured into a casting mold prepared by sandwiching a silicone spacer between glass plates, and after pouring, the composition was cured for 16 hours or more in a gear oven set at 30°C to produce a cured product (heat-dissipating adhesive). The cured product was released from the glass mold and then aged for 2 days or more before being used to measure various physical properties.

[0077] Example 5 and Comparative Examples 7 to 9 Urethane compositions and their cured products were prepared in the same manner as in Example 4, except that the contents shown in Table 2 were used.

[0078] [Evaluation] The urethane compositions and their cured products obtained in Examples 1 to 5 and Comparative Examples 1 to 9 were evaluated as follows, and the results are shown in Tables 1 and 2.

[0079] (1) Viscosity For Examples 1 to 3 and Comparative Examples 1 to 6, the viscosity at 25°C of only the ester-based polyol listed in Table 1 was measured using an E-type viscometer (trade name "VISCOMETER TV-22", manufactured by Toki Sangyo Co., Ltd.).

[0080] For Examples 4 and 5 and Comparative Examples 7 to 9, the viscosity of the mixture of the polyol and the filler, in which the alumina filler was blended to the ester polyol used in the amount shown in Table 2, was measured using a rheometer (product name "MCR302", manufactured by Anton Paar Japan Co., Ltd.) The measured shear viscosity was recorded at a shear rate of 10 (1 / s).

[0081] (2) Appearance For Examples 1 to 3 and Comparative Examples 1 to 6, the appearance was checked when only the ester-based polyol listed in Table 1 was blended, and transparent ones were evaluated as "transparent", and cloudy ones were evaluated as "opaque".

[0082] (3) A Hardness Three sheets of the cured products of Examples 1 to 5 and Comparative Examples 1 to 9 were stacked together to a thickness of 6 mm or more, and the A hardness was measured using a durometer (product name "GS-610", manufactured by Teclock Corporation).

[0083] (4) Tensile Strength and Elongation No. 3 dumbbell test pieces were cut out from the cured products of Examples 1 to 5 and Comparative Examples 1 to 9 using a dumbbell cutter, and tensile tests were carried out using a tensile tester (trade name "RTC-1350A", manufactured by A&D Co., Ltd.) at a pulling speed of 500 mm / min and a chuck distance of 60 mm, to measure the tensile strength and elongation at the time when the cured products broke.

[0084] (5) Shear Adhesion Strength The urethane compositions of Examples 1 to 5 and Comparative Examples 1 to 9 were spread on an Al substrate or a PET substrate based on the test piece dimensions specified in JIS K 6850, and the Al substrates were bonded to each other or to a PET substrate, followed by curing for 16 hours or more in a Geer oven at 30°C to obtain test pieces. The tensile shear adhesive strength of the obtained test pieces was measured using a tensile tester (product name "RTC-1350A", manufactured by A&D Co., Ltd.) at a test speed of 5 mm / min and a chuck distance of 112.5 mm.

[0085] (6) Hydrolysis Resistance For Examples 4 and 5 and Comparative Examples 7 to 9, test pieces were prepared by bonding together Al substrates in the same manner as those prepared in the section on shear adhesive strength above, and the test pieces were placed in an environmental testing machine (trade name "SH-641", manufactured by ESPEC Corporation) under conditions of 85°C and 85% RH for 500 hours. The shear adhesive strength was then measured before and after the test under the same conditions as above, and the retention rate was calculated. A retention rate of 50% or more was evaluated as ○, and a retention rate of less than 50% was evaluated as ×.

[0086]

[0087]

[0088] The components listed in Tables 1 and 2 are explained below. Polyol 1: 1,4-cyclohexanedimethanol-modified polycaprolactone diol, Mw: 530, SP value: 10.61, other diol compound (B) Polyol 2: liquid bifunctional polyol, Mw: 2000, hydroxyl value: 56.8 KOH mg / g, SP value: 9.66, diol compound (A) with the lowest SP value Polyol 3: 1,4-BG-modified polycaprolactone diol, Mw: 400, SP value: 11.52, other diol compound (B) Polyol 4: liquid polycaprolactone diol, Mw: 1250, hydroxyl value: 90.2 KOH mg / g DBTDL: dibutyltin dilaurate

[0089] The urethane compositions of Examples 1 to 3 had excellent room-temperature handleability due to their low viscosity, and when cured, their A hardness did not become too high, so they maintained flexibility while maintaining sufficient tensile strength and tensile elongation, thereby maintaining high mechanical properties. Furthermore, in Examples 4 and 5, even when a filler was added, the viscosity did not increase excessively, and the compositions still had excellent room-temperature handleability and excellent hydrolysis resistance. On the other hand, when two or more polyols with an SP value difference of 1.3 or less were not used in combination, the hardness became too high depending on the type of resin contained, resulting in poor flexibility (Comparative Example 1). Furthermore, when only another resin was included, the mechanical properties were insufficient (Comparative Examples 4 and 5). Furthermore, when the content of the diol compound with the lowest SP value exceeded 55% by mass of the total polyol, the viscosity became too high, resulting in poor room-temperature handleability (Comparative Examples 2 and 3). Furthermore, when polyols with an SP value difference of more than 1.3 were used in combination, the mechanical properties were poor (Comparative Example 6). Furthermore, when a filler was contained, if the diol compound (A) having the lowest SP value and the other diol compound (B) were not contained, the mechanical properties were poor (Comparative Example 7) or the flexibility was poor (Comparative Examples 8 and 9), depending on the type of resin contained.

[0090] Variations of the present disclosure are described below. [Appendix 1] A urethane composition comprising an ester polyol and a polyisocyanate, wherein the ester polyol comprises at least two or more diol compounds, wherein the difference in SP value between a diol compound (A) having the lowest SP value among the diol compounds and the other diol compounds (B) is 1.3 or less, and wherein the content of the diol compound (A) is 1 to 55 mass% of the total amount of the ester polyol. [Appendix 2] The urethane composition according to Appendices 1, wherein the viscosity of the ester polyol as a mixture at 25°C is 5,000 mPa·s or less. [Appendix 3] The urethane composition according to Appendices 1 or 2, wherein the viscosity of the ester polyol as a mixture at 25°C is 10 mPa·s or more. [Appendix 4] The urethane composition according to any one of Appendices 1 to 3, wherein the viscosity at 25°C is 30 Pa·s or less when a filler is mixed with the ester polyol mixture in an amount of 70 to 80 mass%. [Appendix 5] The urethane composition according to any one of Appendices 1 to 4, wherein the ester-based polyol has a transparent appearance when mixed. [Appendix 6] The urethane composition according to any one of Appendices 1 to 5, wherein the diol compound (A) has an SP value of 10 or less. [Appendix 7] The urethane composition according to any one of Appendices 1 to 6, wherein the diol compound (A) has an SP value of 9 or more. [Appendix 8] The urethane composition according to any one of Appendices 1 to 7, wherein the diol compound (A) has a hydroxyl value of 20 to 80 KOHmg / g. [Appendix 9] The urethane composition according to any one of Appendices 1 to 8, wherein the diol compound (A) has an acid value of 1.0 KOHmg / g or less. [Appendix 10] The urethane composition according to any one of Appendices 1 to 9, wherein the content of the diol compound (A) is 1 to 55 mass% of the total amount of the ester-based polyol. [Appendix 11] The urethane composition according to any one of Appendices 1 to 10, wherein the content of the diol compound (B) is 45 to 99 mass% of the total amount of the ester-based polyol. [Appendix 12] The urethane composition according to any one of Appendices 1 to 11, wherein the number average molecular weight of the diol compound (A) is 1,000 to 3,000.[Appendix 13] The urethane composition according to any one of Appendices 1 to 12, wherein the diol compound (B) contains a structural moiety derived from an alicyclic diol compound. [Appendix 14] The urethane composition according to any one of Appendices 1 to 13, wherein the number average molecular weight of the diol compound (B) is 300 to 800. [Appendix 15] The urethane composition according to any one of Appendices 1 to 14, wherein the SP value of the diol compound (B) is 11.3 or less. [Appendix 16] The urethane composition according to any one of Appendices 1 to 15, wherein the SP value of the diol compound (B) is greater than 10. [Appendix 17] The urethane composition according to any one of Appendices 1 to 16, wherein the polyisocyanate is an aliphatic polyisocyanate. [Appendix 18] The urethane composition according to any one of Appendices 1 to 17, wherein the polyisocyanate contains a tri- or higher functional isocyanate. [Appendix 19] The urethane composition according to Appendice 18, further containing a difunctional isocyanate. [Appendix 20] The urethane composition according to Appendices 18 or 19, containing a trimer of a bifunctional isocyanate as the tri- or higher functional isocyanate. [Appendix 21] The urethane composition according to any one of Appendices 1 to 20, containing hexamethylene diisocyanate and hexamethylene diisocyanate trimer as the polyisocyanate. [Appendix 22] The urethane composition according to any one of Appendices 18 to 21, wherein the content of the trifunctional isocyanate is less than 45% by mass of the total amount of polyisocyanate. [Appendix 23] The urethane composition according to any one of Appendices 18 to 22, wherein the content of the trifunctional isocyanate is 5% by mass or more of the total amount of polyisocyanate. [Appendix 24] The urethane composition according to any one of Appendices 1 to 23, further containing a catalyst. [Appendix 25] The urethane composition according to Appendices 24, wherein the content of the catalyst is 10 to 10,000 ppm relative to the total amount of resin components in the urethane composition. [Appendix 26] The urethane composition according to any one of Appendices 1 to 25, which contains a filler. [Appendix 27] The urethane composition according to Appendices 26, in which the content of the filler is 50 to 95 mass% of the total amount of the urethane composition. [Appendix 28] A cured product of the urethane composition according to any one of Appendices 1 to 27.[Appendix 29] The cured product according to Appendices 28, having an A-hardness of 40 to 69 when measured at a thickness of 6 mm or more. [Appendix 30] The cured product according to Appendices 28 or 29, having an A-hardness of 70 to 89 when measured at a thickness of 6 mm or more when the filler content is 70 to 80% by mass. [Appendix 31] The cured product according to any one of Appendices 28 to 30, having a tensile strength at break of 5 MPa or more when measured using a No. 3 dumbbell at a pulling rate of 500 mm / min and a chuck distance of 60 mm. [Appendix 32] The cured product according to any one of Appendices 28 to 31, having a tensile strength at break of 4 MPa or more when measured using a No. 3 dumbbell at a pulling rate of 500 mm / min and a chuck distance of 60 mm when the filler content is 70 to 80% by mass. [Appendix 33] The cured product according to any one of Appendices 28 to 32, having an elongation at break of 200% or more when measured using a No. 3 dumbbell at a tensile speed of 500 mm / min and a chuck distance of 60 mm. [Appendix 34] The cured product according to any one of Appendices 28 to 33, having an elongation at break of 100% or more when measured using a No. 3 dumbbell at a tensile speed of 500 mm / min and a chuck distance of 60 mm, when containing a filler in an amount of 70 to 80 mass%. [Appendix 35] The cured product according to any one of Appendices 28 to 34, having a shear adhesive strength of 2.0 MPa or more when measured using a test piece prepared by bonding two Al substrates together at a test speed of 5 mm / min and a chuck distance of 112.5 mm, according to JIS K 6850. [Appendix 36] The cured product according to any one of Appendices 28 to 35, which contains 70 to 80 mass% of filler and has a shear adhesive strength of 1.5 MPa or more when measured at a test speed of 5 mm / min and a chuck distance of 112.5 mm on a test piece prepared by bonding two Al substrates together in accordance with JIS K 6850. [Appendix 37] The cured product according to any one of Appendices 28 to 36, which has a shear adhesive strength of 1.9 MPa or more when measured at a test speed of 5 mm / min and a chuck distance of 112.5 mm on a test piece prepared by bonding an Al substrate and a PET substrate in accordance with JIS K 6850.[Appendix 38] The cured product according to any one of Appendices 28 to 37, which contains 70 to 80 mass% of filler and has a shear adhesive strength of 1.5 MPa or more when measured at a test speed of 5 mm / min and a chuck distance of 112.5 mm on a test piece prepared by bonding an Al substrate and a PET substrate in accordance with JIS K 6850. [Appendix 39] A thermally conductive adhesive comprising the cured product according to any one of Appendices 28 to 38.

Claims

1. A urethane composition comprising an ester polyol and a polyisocyanate, wherein the ester polyol comprises at least two or more diol compounds, wherein the difference in SP value between a diol compound (A) having the lowest SP value among the diol compounds and other diol compounds (B) is 1.3 or less, and wherein the content of the diol compound (A) is 1 to 55 mass% of the total amount of the ester polyol.

2. The urethane composition according to claim 1, wherein the content of said diol compound (B) is 45 to 99% by mass of the total amount of said ester-based polyol.

3. The urethane composition according to claim 1 or 2, wherein the number average molecular weight of the diol compound (A) is 1,000 to 3,000.

4. The urethane composition according to claim 1 or 2, wherein the diol compound (B) contains a structural moiety derived from an alicyclic diol compound.

5. The urethane composition according to claim 1 or 2, which contains a filler.

6. A cured product of the urethane composition according to claim 1 or 2.

7. A cured product of the urethane composition according to claim 5.

8. A heat-dissipating adhesive comprising the cured product according to claim 7.

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