JP2023016176A - Composition and two-liquid type adhesive using the same - Google Patents

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

The present invention relates to a composition and a two-part adhesive using the same.

Various types of adhesives, such as epoxy adhesives and urethane adhesives, are known. Structural adhesives are required to have strength and durability, and especially for automotive applications, a high glass transition temperature (Tg) is required from the viewpoint of strength stability in the operating temperature range. Epoxy-based adhesives generally have a higher Tg and higher strength than urethane-based adhesives, but have the problem of being brittle.

For this reason, urethane-based adhesives are attracting attention as structural adhesives that require toughness. As the urethane-based adhesive, a reactive two-liquid type adhesive is sometimes used, and one example of such an adhesive is disclosed in Patent Document 1. According to the two-liquid type urethane-based adhesive composition of Patent Document 1, the storage stability of the first liquid is improved while maintaining the effect of obtaining good adhesion performance without applying a primer treatment or sanding treatment. is also considered to be superior.

The composition disclosed in Patent Document 1 consists of a first liquid containing a prepolymer obtained by reacting a polyisocyanate and a polyol, and a second liquid containing a polyol and a catalyst. , 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, and the second liquid is a high molecular weight polyol having a number average molecular weight of 1000 or more (II ) and a low-molecular-weight polyol having a number average molecular weight of less than 1000, and the molar ratio of (I), (II) and the low-molecular-weight polyol is a predetermined amount.

WO2009/047962

However, conventional urethane-based adhesives, including those described in Patent Document 1, exhibit sufficient strength in a wide temperature range from room temperature to high temperatures even if they have sufficient toughness, and can be applied as structural adhesives. The current situation is that nothing has been obtained.

Accordingly, an object of the present invention is to provide a composition that is applicable to urethane-based adhesives, has excellent resin strength at room temperature as a cured product, and has a sufficiently high glass transition temperature (Tg). be.

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

Compositions according to other embodiments of the present disclosure include the composition in which the carbonate group-containing polyol (b1) is liquid at 23° C., the composition based on the total amount of the composition (component (A) and component (B) It can also be calculated based on the total amount of the reaction product.), the above composition containing 30% by mass of 4,4'-diphenylmethane diisocyanate, and the total amount of the above composition (Component (A) and Component (B) ), the content of the cross-linking agent (b2) (when the cross-linking agent (b2) forms one cross-link per molecule, the above component (A) and component (B) It also corresponds to the cross-linking density derived from the cross-linking agent (b2) of the reactant of 1) is 0.50 mmol/g or more, and the solvent-free composition is included.

A two-part adhesive according to another embodiment of the present disclosure comprises the above composition.

ADVANTAGE OF THE INVENTION According to this invention, the composition which is applicable to a urethane-type adhesive agent, and is excellent in the resin strength in the normal temperature of the hardened|cured material, and the glass transition temperature (Tg) is also provided sufficiently high composition. Here, the "resin" means a substance obtained by reacting an unreacted composition (a cured adhesive when the composition is used as an adhesive), and according to the configuration of the present invention, , the reaction product (cured product) of component (A) and component (B) corresponds to the resin.

DETAILED DESCRIPTION Exemplary embodiments for carrying out the present disclosure are described in detail below.

Embodiment compositions comprise component (A) comprising an isocyanate-terminated polyisocyanate and component (B) comprising a polyol. The composition may be a two-component type in which component (A) and component (B) exist separately, or may be a one-component type in which component (A) and component (B) are combined. If the one-liquid type requires long-term storage, it is preferable to take known measures such as blocking the isocyanate-terminated polyisocyanate so that the functional groups do not react in the one-liquid state.

[Component (A)]
Component (A) comprises an isocyanate-terminated polyisocyanate. In addition to the isocyanate-terminated polyisocyanate, component (A) may contain additives, catalysts, reaction terminator and the like. The isocyanate-terminated polyisocyanate is preferably the main component of component (A). % by weight, 95-100% by weight, or 100% by weight.

The isocyanate-terminated polyisocyanate is a reaction product of a monol having a molecular weight of 33-250 and 4,4'-diphenylmethane diisocyanate and is a compound having allophanate groups which is liquid at 23°C. This compound has an allophanate group content (theoretical amount) of 0.35 mmol/ g or more. Here, the liquid state means having fluidity at 23 ° C. (specifically, the material is contained in a flat-bottomed cylindrical glass test tube with an inner diameter of 30 mm and a height of 120 mm, and the height of the material is 55 mm. Keep the test tube at 23 ° C, hold the test tube horizontally, and the tip of the liquid surface of the material passes through the part 85 mm from the bottom of the test tube within 90 seconds.), Ingredients ( There are no restrictions on the viscosity, etc., as long as it can be mixed with B).

The content of allophanate groups is calculated assuming that 100% of the urethane in the isocyanate-terminated polyisocyanate is allophanated, and the number of moles of monol contained in the isocyanate-terminated polyisocyanate (monool amount/monool molecular weight) is the resin It represents the amount (mmol/g) contained therein.

The content of allophanate groups can be, for example, 0.35-1.50 mmol/g, 0.40-1.25 mmol/g, 0.45-1.20 mmol/g. The content of allophanate groups is particularly preferably 0.45 mmol/g to 1.10 mmol/g from the viewpoint of exhibiting excellent tensile properties and high Tg. The higher the allophanate group content, the better the mechanical properties, but the lower the content, the better the moldability.

The isocyanate group-terminated polyisocyanate can be produced by any production method. For example, after adding 4,4'-diphenylmethane diisocyanate and an allophanatization catalyst (zinc acetylacetone, etc.) into a stirring vessel, a monool having a molecular weight of 33 to 250 is added and stirred while maintaining the temperature in the vessel at 40 to 70°C. . Subsequently, while maintaining the temperature in the stirring vessel at 90° C., the urethanization reaction and allophanatization reaction were advanced for about 2 to 5 hours, and then the reaction was stopped by adding a catalyst poison to obtain 4,4′-diphenylmethane diisocyanate. An isocyanate group-terminated polyisocyanate containing allophanate groups containing the backbone can be obtained.

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. As a source of 4,4'-diphenylmethane diisocyanate, a mixture of 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate (for example, 4,4'-diphenylmethane diisocyanate having a purity of about 45%) is used. You can also

The content of 4,4'-diphenylmethane diisocyanate in the composition consisting of component (A) and component (B) is preferably 30% by mass or more, more preferably 40% by mass or more, based on the total amount of the composition. Furthermore, it is 45% by mass or more. 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 further preferably 55% by mass or less, based on the total amount of the composition. It is preferable that the content of 4,4'-diphenylmethane diisocyanate in the composition is 30% by mass or more because the strength and Tg of the resin are increased.

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 (that is, 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, 1-hexadecanol, etc., and mixtures thereof can also be used. When methanol, which is a monool with a molecular weight of less than 33, is used, the liquid property deteriorates (solidifies or separates) at room temperature (23° C.), making it unusable. If the molecular weight exceeds 250, the rigidity around the allophanate group is lost, the Tg is lowered, and physical properties cannot be secured.

Examples of allophanatization catalysts 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 allophanatization catalyst to be added is preferably 1 ppm or more and 1000 ppm or less, more preferably 10 ppm or more and 500 ppm or less, relative to the total amount of the isocyanate group-terminated polyisocyanate.

Suitable catalyst poisons for deactivating the allophanatization reaction catalyst include acidic substances such as anhydrous hydrogen chloride, sulfuric acid, phosphoric acid, monoalkylsulfuric acid esters, alkylsulfonic acids, alkylbenzenesulfonic acids, mono- or dialkylphosphoric acids. Esters, benzoyl chloride, Lewis acids. The amount to be added is preferably equal to or more than the number of moles of the allophanatization catalyst, and is preferably 1.0 to 1.5 times the molar equivalent.

[Component (B)]
Component (B) contains a polyol, and the polyol includes a carbonate group-containing polyol (b1). Component (B) further includes a cross-linking agent (b2). The cross-linking agent is a compound that reacts with the isocyanate-terminated polyisocyanate of component (A) to introduce a cross-linked structure, and a cross-linking agent having an average number of functional groups of 3 or more is preferred. Component (B) may contain reaction inhibitors, antioxidants, antifoaming agents, etc., in addition to these. These may be added to component (A) instead of component (B), or may be added to both component (A) and component (B).

The total content of the carbonate group-containing polyol (b1) and the cross-linking agent (b2) relative to the total amount of component (B) is, for example, 80 to 100% by mass, 85 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass. Or it can be 100% by mass.

The carbonate group-containing polyol (b1) is used from the viewpoint of strength, heat resistance, weather resistance, and durability, and when considering its use as an adhesive, it is a liquid polycarbonate that can be handled as a liquid at room temperature (23 ° C.). Polyols are particularly preferred.

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, neo Pentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, glycerin, trimethylolpropane, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, one or more polyols such as xylylene glycol; dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; alkylene carbonates such as ethylene carbonate and propylene carbonate; diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, and diphenanthryl One or more kinds of carbonates such as carbonate and diindanyl carbonate may be obtained from dealcoholization reaction or dephenolation reaction. One of these may be contained, or two or more may be contained.

Examples of the cross-linking agent (b2) include polyols having an average functionality of 3 or more, such as glycerin, trimethylolpropane, pentaerythritol, N,N-bishydroxypropyl-N-hydroxyethylamine, triethanolamine, triisopropanolamine, ethylenediamine. Propylene oxide modified monomer polyol, trimethylolpropane propylene oxide modified monomer polyol, pentaerythritol propylene oxide modified; Polycaprolactone polyol obtained by ring-opening addition of cyclic esters such as butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone; and the like. These may be used individually by 1 type, and may be used in mixture of 2 or more types. In addition, when the carbonate group-containing polyol is a polyol having an average number of functional groups exceeding 2, the polyol is included in the carbonate group-containing polyol (b1) instead of the cross-linking agent (b2).

[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 type containing substantially no solvent is particularly preferred. The solvent-free type, which does not substantially contain a solvent, includes the case where the solvent component is contained as an impurity, and the case where the solvent component is contained in an amount that cannot be removed even by purification. When the solvent content in the composition is 1% by mass or less, it is possible to further suppress the occurrence of dripping due to excessively low viscosity.

A catalyst can also be used for the purpose of accelerating the reaction between the isocyanate group-terminated polyisocyanate and the polyol. That is, at least one of component (A) and component (B) may contain a catalyst. It is particularly preferable from the viewpoint of reactivity control that the content of the catalyst is 0.05% by mass or less in the composition. Examples of catalysts include isocyanurate-forming catalysts and urethanization-catalysts, and specific examples are shown below.

The isocyanurate catalyst includes, for example, triethylamine, N-ethylpiperidine, N,N'-dimethylpiperazine, N-ethylmorpholine, tertiary amines such as Mannich bases of phenolic compounds, potassium acetate and the like. Moreover, these isocyanurate-forming catalysts can be used alone or in combination of two or more.

The urethanization catalyst can be appropriately selected from known catalysts and used, and examples thereof include amine-based catalysts, imidazole-based catalysts, metal catalysts, and the like.

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''-pentamethyl Examples include dipropylenetriamine, N,N,N',N'-tetramethylhexamethylenediamine, bis(2-dimethylaminoethyl)ether and the like.

Examples of imidazole catalysts include 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, 1-dimethylaminopropylimidazole and the like.

Examples of metal-based catalysts include organic tin catalysts such as stannus diacetate, stannus dioctoate, stannus dioleate, stannus dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, and dioctyltin dilaurate. etc. can be mentioned.

The compositions according to the above embodiments can exhibit high Tg (80° C. or higher) and excellent tensile strength (55 MPa or higher) at room temperature. In addition, Tg was measured by DMA7100 (manufactured by Hitachi High-Tech Science Co., Ltd.) and evaluated by the tan δ peak temperature at a measurement frequency of 10 Hz. Normal temperature means 15° C. or more and 35° C. or less, and particularly means 20° C. or more and 30° C. or less. Tensile strength conforms to JIS K7312:1996.

The composition described above can also be used as an adhesive (especially a two-pack type adhesive) for various purposes, and the application fields include, for example, the automobile field, the display field, the recording medium field, the electronic material field, and the battery field. , optical parts, construction, electronic equipment, aviation, etc.

In the automotive field, for example, it can be used for automobile structural parts, switch parts, headlamps, internal engine parts, electrical parts, drive engines, and brake oil tanks. In the display field, for example, it can be used in liquid crystal displays, organic electroluminescence, and light-emitting diode displays. In the field of recording media, for example, it can be used for video discs, CDs, DVDs, MDs, pickup lenses, VCM magnets, spindle motors, hard disk peripheral members, and Blu-ray discs.

In the field of electronic materials, for example, it can be used for electronic components, electric circuits, electrical contacts, or semiconductor elements. Conductive adhesives, interlayer adhesives for multilayer substrates including build-up substrates, and the like. In the battery field, for example, it can be used in lithium ion batteries, manganese batteries, alkaline batteries, nickel batteries, fuel cells, silicon solar cells, dye-sensitized solar cells, and organic solar cells. In the field of optical parts, for example, it can be used around optical switches in optical communication systems, optical fiber materials around optical connectors, optical passive parts, optical circuit parts, and around optoelectronic integrated circuits. In the field of electronic equipment, for example, it can be used for camera modules.

Component (A) and component (B) are mixed and reacted before use. After mixing, the mixture may be stored at room temperature (23° C.) for curing, or may be cured by heating at 80 to 180° C. for about 1 to 60 minutes.

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Isocyanate group-terminated polyisocyanates and polyols were produced by the methods described below. The information and abbreviations of the raw materials used are as follows.
[material]
(1) Raw material for isocyanate group-terminated polyisocyanate "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 / mmol
・ “EtOH”; Etal (Tokyo Chemical Industry Co., Ltd.), molecular weight = 46.1 g / mmol
・ “1-ProOH”; 1-propanol (manufactured by Tokyo Chemical Industry Co., Ltd.), molecular weight = 60.1 g / mmol
・ “2-ProOH”; 2-propanol (manufactured by Tokyo Chemical Industry Co., Ltd.), molecular weight = 60.1 g / mmol
・ “BuOH”; 1-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.), molecular weight = 74.1 g / mmol
・ “2-EtHexOH”; 2-ethylhexanol (manufactured by Tokyo Chemical Industry Co., Ltd.), molecular weight = 130.2 g / mmol
・"TDOH"; tridecanol (manufactured by KH Neochem), molecular weight = 200.4 g/mmol
[catalyst]
・ Acetylacetone zinc (manufactured by Tokyo Chemical Industry Co., Ltd.)
[catalyst poison]
・Benzoyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd.)

(2) Raw material for polyol ・"PCD-1000"; Kuraray Polyol C-1090 (manufactured by Kuraray Co., Ltd.), polycarbonate polyol, hydroxyl value = 112 KOHmg / g, number of functional groups (f) = 2
· "PPG-1000"; P-1010 (manufactured by ADEKA), polypropylene glycol, hydroxyl value = 112 KOHmg / g, number of functional groups (f) = 2
· "MA-170"; Leocon MA-170 (manufactured by Lion Specialty Chemicals), N,N-bishydroxypropyl-N-hydroxyethylamine, hydroxyl value = 950 KOHmg / g, number of functional groups (f) = 3

[Production of isocyanate group-terminated prepolymer]
Into a stirring vessel filled with nitrogen, 4,4'-diphenylmethane diisocyanate is charged according to the formulation shown in Tables 1 to 5, and while maintaining the temperature in the stirring vessel at 40 to 70 ° C., All was added, a predetermined amount of catalyst (zinc acetylacetonate) was added, and the mixture was mixed and stirred for about 1 to 5 hours. After that, a catalyst poison was added to stop the reaction, and an isocyanate group-terminated prepolymer (component (A)) containing allophanate groups (a1) and containing a 4,4′-diphenylmethane diisocyanate skeleton was obtained. Tables 1 to 5 show the properties of the isocyanate group-terminated prepolymers at room temperature (23°C).

[Production of polyol]
According to the compounding ratio described in the column of "polyol" in Tables 6 to 9, each material was put into a stirring vessel filled with nitrogen and stirred. After that, the mixture was mixed for about 1 to 3 hours while maintaining the temperature in the stirring vessel at 40 to 70° C. to obtain a polyol (component (B)).

[Production of compositions: Examples 1 to 13, Comparative Examples 1 to 7]
A composition was prepared by combining an isocyanate group-terminated prepolymer and a polyol at the ratios described in Tables 6 to 9 under "Composition". Then, a cured product was prepared according to the following "Preparation of test piece and evaluation criteria", and the hardness, tensile strength (TB), and Tg were measured by the methods described below, and the results are shown in Tables 6 to 9. . In Comparative Examples 2 and 3, since the isocyanate group-terminated polyisocyanate was solid at normal temperature (23° C.), evaluation could not be performed.

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

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, regarding the amount of isocyanate groups, those forming allophanate groups are excluded. The crosslink density was obtained from the amount of polyol having 3 or more hydroxyl groups in the total amount of the cured product.
be able to.

The allophanate group concentration is, as described above, calculated by the number of moles (mmol) of monools constituting the isocyanate-terminated polyisocyanate with respect to the total amount (g) of the isocyanate-terminated polyisocyanate and polyol. The theoretical amount of allophanate groups. be. That is, it is calculated assuming that urethane in the isocyanate-terminated polyisocyanate is 100% allophanated, and the number of moles of monol contained in the isocyanate-terminated polyisocyanate (monool amount/monool molecular weight) is the amount contained in the resin. (mmol/g). The calculation formula is as follows.
Allophanate group concentration (mmol/g) = [monool amount shown in Tables 1 to 5/monool molecular weight] × [blended amount of isocyanate-terminated polyisocyanate shown in Tables 6 to 9]/1000

The amount (%) of 4,4'-diphenylmethane diisocyanate in the resin was calculated by the following formula.
[MT amount x amount of isocyanate-terminated polyisocyanate 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%.

[Preparation of test piece and evaluation criteria]
(1) Tensile Strength at Room Temperature The composition was mixed and stored at 23° C. for 16 hours, baked at 180° C. for 20 minutes, and cured at 23° C. for 1 week to obtain a resin sheet with a thickness of 2 mm. The tensile strength (TB) of this resin sheet was measured using a tensile tester (trade name: Autocom Universal Tester AC-10kN-C, manufactured by TSE Co., Ltd.). This measurement was performed according to JIS K7312:1996. The measurement conditions were a temperature of 23° C. and a test speed of 500 mm/min. The strength was judged to be sufficient when the tensile strength (TB)≧55 MPa.

(2) Tg evaluation The composition was mixed, stored at 23°C for 16 hours, baked at 180°C for 20 minutes, and cured at 23°C for 1 week. The viscoelasticity was measured by temperature dispersion using an elasticity measuring machine (trade name: DMA7100, manufactured by Hitachi High-Tech Science). The measurement temperature range was −100° C. to 250° C., the temperature increase rate was 2 mm/min, the measurement frequency was 10 Hz, and the peak temperature of tan δ was defined as Tg. When the Tg was 80°C or higher, the value was judged to be sufficiently high.

(3) Hardness The composition was mixed and stored at 23°C for 16 hours, baked at 180°C for 20 minutes, and cured at 23°C for 1 week to obtain a resin sheet with a thickness of 2 mm. The shore-D hardness of this resin sheet was measured according to JISK7312:1996 at 23° C. 10 seconds after the sample was adhered.

Since Examples 1 to 13 contain a carbonate group-containing polyol (b1) as a polyol component, they have high tensile strength and contain 0.35 mmol/g or more of allophanate groups composed of 4,4′-diphenylmethane diisocyanate. , Tg was also 80° C. or higher.

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., which was unsuitable as a structural adhesive. In Comparative Examples 2 and 3, since the allophanate group modification was performed with methanol having a molecular weight of less than 33, the isocyanate-terminated polyisocyanate was solid at room temperature and could not be evaluated. Comparative Example 4 contains 0.35 mmol/g or more of allophanate groups made of 4,4'-diphenylmethane diisocyanate, but the polyol does not contain a carbonate group-containing polyol (b1), and the strength is 34 MPa. There is concern about strength when used as a structural adhesive.

In Comparative Examples 5 and 6, although the polyol skeleton contained the carbonate group-containing polyol (b1), it contained no allophanate group, and had a Tg of less than 80°C and a strength of less than 55 MPa. Furthermore, in Comparative Example 7, the allophanate group concentration did not contain 0.35 mmol / g or more, and the isocyanate used was a high isomer product, and the 4,4'-diphenylmethane diisocyanate component was 20% in the resin. , and the strength does not reach 55 MPa.

Claims (6)

A composition comprising component (A) comprising an isocyanate-terminated polyisocyanate and component (B) comprising a polyol,
The isocyanate-terminated polyisocyanate is a compound having an allophanate group that is liquid at 23° C., which is a reaction product of a monool having a molecular weight of 33 to 250 and 4,4′-diphenylmethane diisocyanate,
The content of the allophanate group, calculated by 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 cross-linking agent (b2). 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, wherein the content of said 4,4'-diphenylmethane diisocyanate is 30% by mass or more based on the total amount of said composition. The composition according to any one of claims 1 to 3, wherein the content of the cross-linking agent (b2) is 0.50 mmol/g or more based on the total amount of the composition. The composition according to any one of claims 1 to 4, which is solvent-free. A two-component adhesive comprising the composition according to any one of claims 1 to 5.