Composition and two-component adhesive using the same

Abstract

To provide a composition applicable to a urethane-based adhesive, a cured material of which has excellent resin strength at room temperature and also has a sufficiently high glass transition temperature (Tg).SOLUTION: Provided is a composition, comprising: a component (A) containing an isocyanate-terminated polyisocyanate; and a component (B) containing a polyol, where the isocyanate-terminated polyisocyanate is a compound having an allophanate group, which is a reaction product of a monool having a molecular weight of 33-250 and 4,4'-diphenylmethane diisocyanate and is liquid at 23°C. A content of the allophanate group, calculated as a number of moles (mmol) of the monool having a molecular weight of 33-250 relative to a total amount (g) of the isocyanate-terminated polyisocyanate and the polyol is 0.35 mmol / g or more, and the component (B) comprises a carbonate group-containing polyol (b1) and a crosslinking agent (b2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition and a two-component adhesive using the same. [Background technology]

[0002] There are many types of adhesives known, including epoxy adhesives and urethane adhesives. Structural adhesives require strength and durability, and in particular for automotive applications, a high glass transition temperature (Tg) is required to ensure strength stability over the operating temperature range. Generally, epoxy adhesives have a higher Tg and are stronger than urethane adhesives, but their brittleness is an issue.

[0003] For this reason, urethane adhesives have attracted attention as structural adhesives that require toughness. Reactive two-component adhesives are sometimes used as urethane adhesives, and examples of such adhesives include those disclosed in Patent Document 1. The two-component urethane adhesive composition of Patent Document 1 is said to have excellent storage stability of the first component while maintaining the effect of obtaining good adhesive performance without the need for primer treatment or sanding treatment.

[0004] The composition disclosed in Patent Document 1 consists of a first liquid containing a prepolymer obtained by reacting a polyisocyanate with a polyol, and a second liquid containing a polyol and a catalyst. The first liquid contains a prepolymer obtained by reacting a polyisocyanate with a high-molecular-weight polyol (I) having a number-average molecular weight of 1000 or more, and a filler as constituent components. The second liquid contains a high-molecular-weight polyol (II) having a number-average molecular weight of 1000 or more and a low-molecular-weight polyol having a number-average molecular weight of less than 1000, and the molar ratios of (I), (II), and the low-molecular-weight polyol are predetermined. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2009 / 047962 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while conventional urethane adhesives, including those described in Patent Document 1, have sufficient toughness, the current situation is that no adhesives have been obtained that exhibit sufficient strength over a wide temperature range from room temperature to high temperatures and are applicable as structural adhesives.

[0007] Therefore, an object of the present invention is to provide a composition that can be used as a urethane adhesive, which has excellent resin strength at room temperature after curing, and also has a sufficiently high glass transition temperature (Tg). [Means for solving the problem]

[0008] A composition according to one embodiment of the present disclosure comprises component (A) containing an isocyanate-terminated polyisocyanate and component (B) containing a polyol, wherein the isocyanate-terminated polyisocyanate is a compound having an allophanate group that is liquid at 23°C and is a reaction product of a monool having a molecular weight of 33 to 250 and 4,4'-diphenylmethane diisocyanate, and the content of the allophanate group, calculated as the number of moles (mmol) of the monool having a molecular weight of 33 to 250 relative to the total amount (g) of the isocyanate-terminated polyisocyanate and the polyol, is 0.35 mmol / g or more, and component (B) is a composition comprising a carbonate group-containing polyol (b1) and a crosslinking agent (b2).

[0009] Other embodiments of the composition of the present disclosure include the composition in which the carbonate group-containing polyol (b1) is liquid at 23°C, the composition in which the content of 4,4'-diphenylmethane diisocyanate is 30 mass% based on the total amount of the composition (which can also be calculated based on the total amount of the reaction products of components (A) and (B)), the composition in which the content of the crosslinking agent (b2) is 0.50 mmol / g or more based on the total amount of the composition (which can also be calculated based on the total amount of the reaction products of components (A) and (B)). (When the crosslinking agent (b2) forms one crosslink per molecule, this also corresponds to the crosslink density derived from the crosslinking agent (b2) of the reaction product of components (A) and (B)).

[0010] A two-component adhesive according to another embodiment of the present disclosure comprises the above composition. [Effects of the Invention]

[0011] According to the present invention, a composition applicable to urethane adhesives is provided, which has excellent resin strength at room temperature after curing and a sufficiently high glass transition temperature (Tg). Here, "resin" refers to a substance formed by the reaction of unreacted components (or the cured adhesive when the composition is used as an adhesive). In terms of the structure of the present invention, the reaction product (cured product) of components (A) and (B) corresponds to the resin. DETAILED DESCRIPTION OF THE INVENTION

[0012] Exemplary embodiments for carrying out the present disclosure are described in detail below.

[0013] The composition according to the present embodiment comprises component (A) containing an isocyanate-terminated polyisocyanate and component (B) containing a polyol. The composition may be a two-component type in which components (A) and (B) are present separately, or a one-component type in which components (A) and (B) are combined. If a one-component composition is required for long-term storage, it is preferable to take a known measure to prevent functional groups from reacting in the one-component state, such as blocking the isocyanate-terminated polyisocyanate.

[0014] [Component (A)] Component (A) contains an isocyanate-terminated polyisocyanate. Component (A) may contain additives, catalysts, reaction terminators, etc. in addition to the isocyanate-terminated polyisocyanate. The isocyanate-terminated polyisocyanate is preferably the main component of component (A), and the content of the isocyanate-terminated polyisocyanate relative to the total amount of component (A) can be, for example, 80 to 100 mass%, 85 to 100 mass%, 90 to 100 mass%, 95 to 100 mass%, or 100 mass%.

[0015] The isocyanate-terminated polyisocyanate is a reaction product of a monool having a molecular weight of 33 to 250 and 4,4'-diphenylmethane diisocyanate, and is a compound having an allophanate group that is liquid at 23°C. This compound has an allophanate group content (theoretical amount) of 0.35 mmol / g or more, calculated as the number of moles (mmol) of the monool having a molecular weight of 33 to 250 relative to the total amount (g) of the isocyanate-terminated polyisocyanate and polyol. Here, "liquid" refers to fluidity at 23°C. (Specifically, the material is placed in a flat-bottomed cylindrical glass test tube with an inner diameter of 30 mm and a height of 120 mm, and the material is placed so that the height of the material is 55 mm. The test tube is maintained at 23°C and held horizontally. The material is considered liquid if the liquid surface passes 85 mm from the bottom of the test tube within 90 seconds.) There are no limitations on viscosity, etc., as long as it is miscible with component (B).

[0016] The allophanate group content is calculated assuming that 100% of the urethane in the isocyanate-terminated polyisocyanate is allophanated, and is expressed as the amount (mmol / g) of the number of moles of monool contained in the isocyanate-terminated polyisocyanate (monool amount / monool molecular weight) contained in the resin.

[0017] The content of the allophanate group can be, for example, 0.35 to 1.50 mmol / g, 0.40 to 1.25 mmol / g, or 0.45 to 1.20 mmol / g. The content of the allophanate group is particularly preferably 0.45 mmol / g to 1.10 mmol / g in order to achieve excellent tensile properties and a high Tg. The higher the content of the allophanate group, the better the mechanical properties tend to be, but the lower the content, the better the moldability becomes.

[0018] Isocyanate-terminated polyisocyanates can be produced by any method. For example, 4,4'-diphenylmethane diisocyanate and an allophanate catalyst (such as zinc acetylacetonate) are placed in a stirring vessel, and then a monool having a molecular weight of 33 to 250 is added and stirred while maintaining the temperature inside the vessel at 40 to 70°C. Next, while maintaining the temperature inside the stirring vessel at 90°C, the urethanization reaction and allophanate reaction are allowed to proceed for about 2 to 5 hours, and then a catalyst poison is added to terminate the reaction, thereby obtaining an isocyanate-terminated polyisocyanate containing allophanate groups that contain a 4,4'-diphenylmethane diisocyanate skeleton.

[0019] Any commonly available 4,4'-diphenylmethane diisocyanate monomer can be used for the isocyanate-terminated polyisocyanate. The purity of the 4,4'-diphenylmethane diisocyanate is generally 95% or higher. The source of 4,4'-diphenylmethane diisocyanate can also be a mixture of 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate (e.g., a mixture with a purity of 4,4'-diphenylmethane diisocyanate of about 45%).

[0020] The content of 4,4'-diphenylmethane diisocyanate in the composition comprising components (A) and (B) is preferably 30% by mass or more, more preferably 40% by mass or more, and even 45% by mass or more, based on the total amount of the composition. The upper limit of the content of 4,4'-diphenylmethane diisocyanate is preferably 70% by mass or less, more preferably 60% by mass or less, and even 55% by mass or less, based on the total amount of the composition. Note that a content of 4,4'-diphenylmethane diisocyanate in the composition of 30% by mass or more is preferred because it increases the resin strength and Tg.

[0021] Examples of monools having a molecular weight of 33 to 250 that react with 4,4'-diphenylmethane diisocyanate to form an isocyanate group-terminated polyisocyanate (i.e., modify 4,4'-diphenylmethane diisocyanate) include ethanol, 1- and 2-propanol, 1- and 2-butanol, 1-pentanol, 1-hexanol, 2-methyl-1-heptanol, 4-methyl-2-pentanol, 2-ethylhexanol, 3,5-dimethyl-1-hexanol, 2,2,4-trimethyl-1-pentanol, 1-nonanol, 2,6-dimethyl-4-heptanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 1-pentadecanol, and 1-hexadecanol, and mixtures thereof can also be used. When methanol, a monool with a molecular weight of less than 33, is used, the liquid properties deteriorate (solidify or separate) at room temperature (23°C) and it becomes unusable. When the molecular weight exceeds 250, the rigidity around the allophanate group is lost, Tg decreases, and physical properties cannot be guaranteed.

[0022] Examples of the allophanate catalyst include metal carboxylates such as zinc acetylacetone, lead acetylacetone, tin acetylacetone, copper acetylacetone, and cobalt acetylacetone, tertiary amino alcohols, quaternary ammonium salts, and compounds thereof. The amount of the allophanate catalyst added is preferably in the range of 1 ppm to 1000 ppm, more preferably 10 ppm to 500 ppm, relative to the total amount of the isocyanate-terminated polyisocyanate.

[0023] When deactivating the allophanate reaction catalyst, an acidic substance is suitable as a catalyst poison, and examples thereof include anhydrous hydrogen chloride, sulfuric acid, phosphoric acid, monoalkyl sulfate ester, alkyl sulfonic acid, alkyl benzene sulfonic acid, mono- or dialkyl phosphate ester, benzoyl chloride, and Lewis acid. The amount of the acidic substance added is preferably at least equivalent to the number of moles of the allophanate reaction catalyst, and more preferably 1.0 to 1.5 times the molar equivalent.

[0024] [Component (B)] Component (B) contains a polyol, and the polyol contains a carbonate group-containing polyol (b1). Component (B) also contains a crosslinking agent (b2). The crosslinking agent is a compound that reacts with the isocyanate-terminated polyisocyanate of component (A) to introduce a crosslinked structure, and a crosslinking agent with an average functionality of 3 or more is preferred. Component (B) may also contain a reaction inhibitor, antioxidant, antifoaming agent, etc. These may be added to component (A) rather than component (B), or to both components (A) and (B).

[0025] The total content of the carbonate group-containing polyol (b1) and the crosslinking agent (b2) relative to the total amount of component (B) can be, for example, 80 to 100 mass%, 85 to 100 mass%, 90 to 100 mass%, 95 to 100 mass%, or 100 mass%.

[0026] The carbonate group-containing polyol (b1) is used from the viewpoints of strength, heat resistance, weather resistance, and durability, and when considering use as an adhesive, a liquid polycarbonate polyol that can be handled in a liquid state at room temperature (23°C) is particularly preferred.

[0027] Examples of carbonate group-containing polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, glycerin, trimethylolpropane, dimer Examples of such polyols include those obtained by dealcoholization or dephenolization of one or more polyols such as diols, ethylene oxide or propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, and xylylene glycol with one or more dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, and carbonates such as diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, and diindanyl carbonate. These may be contained alone or in combination of two or more.

[0028] Examples of the crosslinking agent (b2) include polyols having an average functionality of 3 or more, such as glycerin, trimethylolpropane, pentaerythritol, N,N-bishydroxypropyl-N-hydroxyethylamine, triethanolamine, triisopropanolamine, monomer polyols of ethylenediamine propylene oxide modified compounds, monomer polyols of trimethylolpropane propylene oxide modified compounds, pentaerythritol propylene oxide modified compounds, and polycaprolactone polyols obtained by ring-opening addition of cyclic esters such as ε-caprolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, and δ-valerolactone to a polyol such as glycerin, trimethylolpropane, or pentaerythritol as an initiator. These may be used alone or in combination of two or more. When the carbonate group-containing polyol has an average functionality of more than 2, the polyol is included in the carbonate group-containing polyol (b1) rather than the crosslinking agent (b2).

[0029] [Composition] The composition may contain a solvent. That is, at least one of component (A) and component (B) may contain a solvent. The total solvent content is preferably 1% by mass or less, and a solvent-free composition that is substantially free of solvent is particularly preferred. The term "solvent-free composition that is substantially free of solvent" includes compositions that contain solvent components as impurities or that contain solvent components in amounts that cannot be removed even by purification. When the solvent content in the composition is 1% by mass or less, the viscosity becomes too low, which further prevents dripping.

[0030] A catalyst can be used to promote the reaction between the isocyanate-terminated polyisocyanate and the polyol. That is, at least one of component (A) and component (B) may contain a catalyst. From the viewpoint of reactivity control, it is particularly preferable that the catalyst content in the composition is 0.05 mass% or less. Examples of catalysts include isocyanuration catalysts and urethanization catalysts, and specific examples are shown below.

[0031] Examples of the isocyanurate catalyst include tertiary amines such as triethylamine, N-ethylpiperidine, N,N'-dimethylpiperazine, N-ethylmorpholine, Mannich bases of phenolic compounds, potassium acetate, etc. These isocyanurate catalysts can be used alone or in combination of two or more.

[0032] The urethanization catalyst can be appropriately selected from known catalysts, and examples thereof include amine-based catalysts, imidazole-based catalysts, and metal catalysts.

[0033] Examples of amine catalysts 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",N"-tetramethylhexamethylenediamine, and bis(2-dimethylaminoethyl)ether.

[0034] Examples of imidazole catalysts include 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, and 1-dimethylaminopropylimidazole.

[0035] 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.

[0036] The compositions according to the above embodiments can exhibit a high Tg (80°C or higher) and excellent tensile strength (55 MPa or higher) at room temperature. Tg was measured using a DMA7100 (manufactured by Hitachi High-Tech Science Corporation) and evaluated as the tan δ peak temperature at a measurement frequency of 10 Hz. Room temperature means 15°C or higher and 35°C or lower, and particularly 20°C or higher and 30°C or lower. In the examples described below, room temperature was set to 23°C. Tensile strength was measured in accordance with JIS K7312:1996.

[0037] The above-mentioned composition can also be used as an adhesive (particularly a two-component adhesive) for various applications, and examples of application fields include the automotive field, the display field, the recording medium field, the electronic materials field, the battery field, the optical components field, the construction field, the electronic equipment field, and the aviation field.

[0038] In the automotive field, it can be used for, for example, automobile structural parts, switches, headlamps, internal engine parts, electrical parts, drive engines, and brake oil tanks. In the display field, it can be used for, for example, liquid crystal displays, organic electroluminescence, and light-emitting diode display devices. In the recording medium field, it can be used for, for example, video discs, CDs, DVDs, MDs, pickup lenses, VCM magnets, spindle motors, hard disk peripherals, and Blu-ray discs.

[0039] In the field of electronic materials, the material can be used, for example, in electronic components, electrical circuits, electrical contacts, or semiconductor elements. More specific examples of these applications include sealing materials, die bonding agents, conductive adhesives, anisotropic conductive adhesives, and interlayer adhesives for multilayer substrates, including build-up substrates. In the field of batteries, the material can be used, for example, in lithium-ion batteries, manganese batteries, alkaline batteries, nickel-based batteries, fuel cells, silicon-based solar cells, dye-sensitized solar cells, and organic solar cells. In the field of optical components, the material can be used, for example, in optical fiber materials, optical passive components, optical circuit components, and optoelectronic integrated circuits, in the periphery of optical switches and optical connectors in optical communication systems. In the field of electronic devices, the material can be used, for example, in camera modules.

[0040] Components (A) and (B) are mixed and reacted before use. After mixing, the mixture may be stored at room temperature (23°C) to cure, or may be heated at 80 to 180°C for 1 to 60 minutes to cure. [Example]

[0041] The present invention will be explained in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples at all.

[0042] The isocyanate-terminated polyisocyanate and polyol were produced by the methods described below. The information and abbreviations of the raw materials used are as follows: [Raw materials] (1) Raw material for isocyanate-terminated polyisocyanates "MT": Millionate MT (manufactured by Tosoh Corporation) 4,4'-Diphenylmethane diisocyanate ≥ 99.5%, NCO content = 33.5%, number of functional groups (f) = 2 "NM": Millionate NM (manufactured by Tosoh Corporation) 4,4'-Diphenylmethane diisocyanate / 2,4'-Diphenylmethane diisocyanate mixture, NCO content = 33.5%, functionality (f) = 2 "MeOH": Methanol (Tokyo Chemical Industry Co., Ltd.), molecular weight = 32.1 g / m ol "EtOH": EtOH (Tokyo Chemical Industry Co., Ltd.), molecular weight = 46.1 g / m ol 1-ProOH: 1-propanol (Tokyo Chemical Industry Co., Ltd.), molecular weight = 60.1 g / m ol 2-ProOH: 2-propanol (Tokyo Chemical Industry Co., Ltd.), molecular weight = 60.1 g / m ol "BuOH": 1-butanol (Tokyo Chemical Industry Co., Ltd.), molecular weight = 74.1 g / m ol 2-EtHexOH: 2-Ethylhexanol (Tokyo Chemical Industry Co., Ltd.), molecular weight = 130.2 g / m mol "TDOH": Tridecanol (KH Neochem), molecular weight = 200.4g / m ol [catalyst] Zinc acetylacetonate (Tokyo Chemical Industry Co., Ltd.) [Catalyst poison] Benzoyl chloride (Tokyo Chemical Industry Co., Ltd.)

[0043] (2) Raw materials for polyols "PCD-1000": Kuraray Polyol C-1090 (Kuraray Co., Ltd.), polycarbonate polyol, hydroxyl value = 112 KOH mg / g, number of functional groups (f) = 2 "PPG-1000": P-1010 (ADEKA), polypropylene glycol, hydroxyl value = 112 KOH mg / g, functionality (f) = 2 "MA-170": Leocon MA-170 (manufactured by Lion Specialty Chemicals), N,N-bishydroxypropyl-N-hydroxyethylamine, hydroxyl value = 950 KOH mg / g, functionality (f) = 3

[0044] [Production of isocyanate-terminated prepolymer] 4,4'-Diphenylmethane diisocyanate was placed in a nitrogen-filled stirring vessel in the proportions shown in Tables 1 to 5. While maintaining the temperature inside the stirring vessel at 40 to 70°C, a monool with a molecular weight of 33 to 250 was added, and a predetermined amount of catalyst (zinc acetylacetonate) was added. The mixture was then mixed and stirred for approximately 1 to 5 hours. The reaction was then stopped by adding a catalyst poison, yielding an isocyanate-terminated prepolymer (component (A)) containing a 4,4'-diphenylmethane diisocyanate skeleton and allophanate groups (a1). The properties of the isocyanate-terminated prepolymer at room temperature (23°C) are shown in Tables 1 to 5.

[0045] [Table 1]

[0046] [Table 2]

[0047] [Table 3]

[0048] [Table 4]

[0049] [Table 5]

[0050] [Production of polyols] Each material was placed in a nitrogen-filled stirring vessel and stirred according to the blending ratios shown in the "Polyol" column in Tables 6 to 9. The temperature inside the stirring vessel was then maintained at 40 to 70°C, and the materials were mixed for approximately 1 to 3 hours to obtain a polyol (component (B)).

[0051] [Production of Compositions: Examples 1 to 13, Comparative Examples 1 to 7] Compositions were prepared by combining an isocyanate-terminated prepolymer and a polyol in the ratios shown in the "Formulation" section of Tables 6 to 9. Cured products were then prepared according to the "Preparation of Test Pieces and Evaluation Criteria" below, and the hardness, tensile strength (TB), and Tg were measured by the methods described below, with the results shown in Tables 6 to 9. Note that evaluation could not be performed for Comparative Examples 2 and 3 because the isocyanate-terminated polyisocyanate was solid at room temperature (23°C).

[0052] The urethane group concentration, crosslink density, allophanate group concentration, and amount of 4,4'-diphenylmethane diisocyanate are shown in Tables 6 to 9. The values ​​in these tables are for the composition (the resin that is the cured product obtained by reacting component (A) and component (B)).

[0053] The urethane group concentration is a calculated value for the cured product and can be calculated from the amount of isocyanate groups contained in component (A) and the amount of hydroxyl groups contained in component (B). However, the amount of isocyanate groups does not include allophanate groups. The crosslink density was determined from the amount of polyol with three or more hydroxyl groups in the total amount of the cured product. It is possible.

[0054] As mentioned above, the allophanate group concentration is the theoretical amount of allophanate groups calculated as the number of moles (mmol) of monool constituting the isocyanate-terminated polyisocyanate relative to the total amount (g) of isocyanate-terminated polyisocyanate and polyol. In other words, it is calculated assuming that 100% of the urethane in the isocyanate-terminated polyisocyanate is allophanated, and the number of moles of monool contained in the isocyanate-terminated polyisocyanate (monool amount / monool molecular weight) is expressed as the amount contained in the resin (mmol / g). The calculation formula is as follows: Allophanate group concentration (mmol / g) = [monol amount shown in Tables 1 to 5 / monol molecular weight] × [isocyanate-terminated polyisocyanate amount shown in Tables 6 to 9] / 1000

[0055] The amount (%) of 4,4'-diphenylmethane diisocyanate in the resin was calculated using the following formula. [MT amount × isocyanate-terminated polyisocyanate amount in resin / 10] / [total amount of resin (component (A) + component (B))] The purity of 4,4'-diphenylmethane diisocyanate in MT was calculated as 99.8%, and the purity of 4,4'-diphenylmethane diisocyanate in NM was calculated as 45%.

[0056] [Test specimen preparation and evaluation criteria] (1) Tensile strength at room temperature The composition was mixed and stored at 23°C for 16 hours, then baked at 180°C for 20 minutes and aged at 23°C for 1 week to obtain a 2 mm thick resin sheet. The tensile strength (TB) of this resin sheet was measured using a tensile tester (product name: Autocom Universal Tester AC-10kN-C, manufactured by TSE Corporation). This measurement was performed in accordance with JIS K7312:1996. The measurement conditions were a temperature of 23°C and a test speed of 500 mm / min. A tensile strength (TB) of 55 MPa or greater was considered sufficient.

[0057] (2) Tg evaluation The composition was mixed, stored at 23°C for 16 hours, baked at 180°C for 20 minutes, and then aged at 23°C for 1 week. A 2mm-thick resin sheet was then subjected to dynamic viscoelasticity measurements using a viscoelasticity measuring device (trade name: DMA7100, manufactured by Hitachi High-Tech Science) to measure the viscoelasticity by temperature dispersion. The measurement temperature range was -100°C to 250°C, the heating rate was 2mm / min, and the measurement frequency was 10Hz. The peak temperature of tan δ was defined as Tg. A Tg value of 80°C or higher was considered to be sufficiently high.

[0058] (3)Hardness The composition was mixed and stored at 23°C for 16 hours, then baked at 180°C for 20 minutes, and then aged at 23°C for 1 week to obtain a 2 mm thick resin sheet. The Shore-D hardness of this resin sheet was measured at 23°C after 10 seconds of sample contact according to JIS K7312:1996.

[0059] [Table 6]

[0060] [Table 7]

[0061] [Table 8]

[0062] [Table 9]

[0063] In Examples 1 to 13, since the polyol component contained carbonate group-containing polyol (b1), the tensile strength was high, the allophanate group consisting of 4,4'-diphenylmethane diisocyanate was contained in an amount of 0.35 mmol / g or more, and the Tg was 80°C or more.

[0064] On the other hand, in Comparative Example 1, the allophanate group concentration in the resin was less than 0.35 mmol / g, and the Tg was less than 80°C, making it unsuitable for use as a structural adhesive. Furthermore, in Comparative Examples 2 and 3, allophanate group modification was performed with methanol having a molecular weight of less than 33, so the isocyanate-terminated polyisocyanate was solid at room temperature and evaluation itself was impossible. In Comparative Example 4, although the allophanate group consisting of 4,4'-diphenylmethane diisocyanate was contained at 0.35 mmol / g or more, the polyol did not contain carbonate group-containing polyol (b1), and the strength was 34 MPa, which was not strong enough for use as a structural adhesive.

[0065] In Comparative Examples 5 and 6, although the polyol skeleton contained a carbonate group-containing polyol (b1), it did not contain an allophanate group, and the Tg was less than 80° C. and the strength was less than 55 MPa. Furthermore, in Comparative Example 7, the allophanate group concentration was less than 0.35 mmol / g, the isocyanate used was a high isomer product, the 4,4′-diphenylmethane diisocyanate component was low at 20% in the resin, and the strength did not reach 55 MPa, and both the strength and Tg were lower than in Comparative Example 1.

Claims

1. A composition comprising: a component (A) comprising an isocyanate-terminated polyisocyanate; and a component (B) comprising a polyol, The isocyanate-terminated polyisocyanate is a compound having an allophanate group that is liquid at 23°C and is a reaction product of a monool having a molecular weight of 33 to 250 and 4,4'-diphenylmethane diisocyanate, The content of the 4,4'-diphenylmethane diisocyanate is 30 mass% or more based on the total amount of the composition, the content of the allophanate group, calculated as the number of moles (mmol) of the monool having a molecular weight of 33 to 250 relative to the total amount (g) of the isocyanate-terminated polyisocyanate and the polyol, is 0.35 mmol / g or more; The component (B) is a composition containing a carbonate group-containing polyol (b1) and a crosslinking agent (b2).

2. The composition according to claim 1, wherein the carbonate group-containing polyol (b1) is liquid at 23°C.

3. The composition according to claim 1 or 2, wherein the content of the crosslinking agent (b2) is 0.50 mmol / g or more based on the total amount of the composition.

4. The composition according to any one of claims 1 to 3, which is solvent-free.

5. A two-component adhesive comprising the composition according to any one of claims 1 to 4.

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