Polyurethane-forming composition

Abstract

To provide an urethane-forming composition that contains a polyol or the like necessary for expressing high strength and contributes to forming a polyurethane having high curability and compatibility as well as high strength, transparency, and wettability; and a cured urethane that has high transparency, high wettability to an adherend and little surface tackiness.SOLUTION: An urethane-forming composition (G) contains a polyol and polyisocyanate (F). The urethane-forming composition contains, as the polyol, at least polyalkylene oxide (A) and a polyol (B) different from the polyalkylene oxide (A). The polyisocyanate (F) includes an allophanate structure. The average number of isocyanate functional groups is 2.01-3.19 as calculated by gel permeation chromatography (GPC).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to polyurethane-forming compositions. [Background technology]

[0002] Polyalkylene oxides containing a large amount of by-produced monools having an unsaturated group at one end (hereinafter referred to as unsaturated monools) are used as raw materials for polyurethanes. However, when attempting to obtain polyurethanes using these polyalkylene oxides, there is a problem that the curing (solidification) associated with the reaction with an isocyanate compound takes time, resulting in a loss of productivity.

[0003] Furthermore, polyurethanes obtained from polyalkylene oxides containing a large amount of such unsaturated monools are unlikely to have a high molecular weight, and have low tensile break elongation and low tensile break strength. In contrast, even polyalkylene oxides containing a large amount of unsaturated monools can be reacted with an isocyanate compound having a large average number of isocyanate groups to obtain high molecular weight polyurethanes. However, in this case, the polyurethane does not become linear and highly molecular weight, but becomes a crosslinked product having a dense crosslinked structure, resulting in low tensile break elongation and low tensile break strength.

[0004] In response to this, in order to improve productivity and increase tensile strength at break, there is a method of introducing relatively rigid polyols, such as highly reactive polyoxytetramethylene glycol, polyols having sugar residues with a high number of functional groups, and highly reactive polyols having aromatic amine residues with a high number of functional groups, into the urethane prepolymer in addition to polyalkylene oxides with a low unsaturated monool content.

[0005] Patent Document 1 discloses a polyurethane having good coatability and productivity and high tensile strength, which is produced using a urethane-forming composition containing a polyalkylene oxide with a small amount of unsaturated monool, a polyalkylene oxide having an aromatic amine residue, and a polyalkylene oxide having one hydroxyl group and an ethylene oxide residue, and a urethane-forming composition containing a urethane prepolymer using the composition and a polyisocyanate crosslinking agent having an isocyanurate structure.

[0006] However, these polyurethane-forming compositions described in Patent Document 1 essentially contain a high-molecular-weight, low-reactivity polyalkylene oxide component with little low-molecular-weight unsaturated monool that easily acts as a compatibilizer, and use a low-molecular-weight polyol component having a rigid aromatic amine residue to develop strength, and a crosslinker having a rigid isocyanurate structure as its main structure. Therefore, there is insufficient compatibility between the three components of the polyalkylene oxide component, aromatic amine polyol component, and isocyanurate crosslinker component, and depending on the amount of solvent and crosslinking conditions, the transparency of the urethane-forming composition and the cured urethane product may deteriorate, making it difficult to consistently obtain highly transparent polyurethane. In addition, due to the rigid aromatic amine structure and isocyanurate structure, the cured urethane product has little surface tack but is hard and does not wet easily to an adherend, which causes problems such as time-consuming bonding and poor productivity.

[0007] Therefore, there has been a demand for a urethane-forming composition that has good curability and compatibility regardless of conditions such as the amount of solvent, even when it contains polyols and the like necessary to achieve high strength, and that contributes to the formation of a polyurethane that is strong, highly transparent, and has high wettability, as well as a polyurethane that has little surface tack and high strength, yet has remarkably good wettability to adherends, and that is highly productive when bonded together. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-158551 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention provides a urethane-forming composition that contains a polyol and the like necessary for achieving high strength, and that contributes to the formation of polyurethane with good curability and compatibility, transparency, and wettability, as well as a cured urethane product that is highly transparent, has good wettability to adherends, and has little surface tack. [Means for solving the problem]

[0010] The embodiments of the present invention are as follows [1] to

[15] . [1] A urethane-forming composition comprising a polyol and a polyisocyanate (F), The polyol contains at least a polyalkylene oxide (A) and a polyol (B) different from the polyalkylene oxide (A), A urethane-forming composition (G), wherein the polyisocyanate (F) contains an allophanate structure and has an average number of isocyanate functional groups in the range of 2.01 to 3.19 as calculated by gel permeation chromatography (GPC). [2] The urethane-forming composition (G) according to [1], wherein the polyisocyanate (F) contains a nurate structure. [3] The urethane-forming composition (G) according to [2], wherein the molar ratio of the allophanate structure to the nurate structure in the polyisocyanate (F) is in the range of 10 / 90 to 90 / 10. [4] A composition comprising an active hydrogen group-terminated urethane prepolymer (E) and a polyisocyanate (F2), the urethane prepolymer (E) is a reaction product of at least a polyalkylene oxide (A), a polyol containing a polyol (B) different from the polyalkylene oxide (A), and a polyisocyanate (F1); A urethane-forming composition (G), wherein either the polyisocyanate (F1) or the polyisocyanate (F2) contains an allophanate structure, and the average number of isocyanate functional groups of the polyisocyanate (F1) and the polyisocyanate (F2) calculated by gel permeation chromatography (GPC) is in the range of 2.01 to 3.19. [5] The urethane-forming composition (G) according to [4], wherein either the polyisocyanate (F1) or the polyisocyanate (F2) contains a nurate structure. [6] The urethane-forming composition (G) according to [5], wherein the molar ratio of allophanate structures to nurate structures in the polyisocyanate (F) obtained by combining the polyisocyanate (F1) and the polyisocyanate (F2) is in the range of 10 / 90 to 90 / 10. [7] The urethane-forming composition (G) according to any one of [4] to [6], wherein the viscosity of the polyisocyanate (F2) is in the range of 150 to 1900 mPa·s. [8] The urethane-forming composition (G) according to any one of [4] to [7], wherein the weight ratio of the urethane prepolymer (E) to the polyisocyanate (F2) is in the range of 80 / 20 to 1 / 99. [9] The urethane-forming composition (G) according to any one of [1] to [8], wherein the polyalkylene oxide (A) has a molecular weight of 2,500 or more, and the polyol (B) has a molecular weight of less than 2,500.

[10] A urethane-forming composition (G) according to any one of [1] to [9], wherein the polyol (B) has one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues.

[11] The urethane-forming composition (G) according to any one of [1] to

[10] , wherein the polyalkylene oxide (A) has a degree of unsaturation of 0.01 meq / g or less.

[12] The urethane-forming composition (G) according to any one of [1] to

[11] , wherein the urethane-forming composition (G) contains a keto-enol tautomer compound and a hindered phenol-based antioxidant.

[13] A polyurethane (H) which is a cured product of the urethane-forming composition (G) according to any one of [1] to

[12] .

[14] A polyurethane sheet comprising the polyurethane (H) according to

[13] and a substrate.

[15] A urethane pressure-sensitive adhesive sheet comprising the polyurethane (H) according to

[13] , having a thickness of 1 to 200 μm, and having a peel strength of 0.20 N / 25 mm or less when attached to alkali-free glass and peeled at 2,500 mm / min. [Effects of the Invention]

[0011] The urethane-forming composition of one embodiment of the present invention is a urethane-forming composition that exhibits good compatibility and curability, regardless of crosslinking conditions, solvent amount, etc., even when it contains a polyol or the like necessary to exhibit high strength, and it is possible to provide a urethane-forming composition that has high transparency, remarkably excellent wettability, and low surface tack using the same. DETAILED DESCRIPTION OF THE INVENTION

[0012] Exemplary embodiments for carrying out the present invention are described in detail below. <Urethane-forming composition (G)> The urethane-forming composition (G) according to one embodiment of the present invention is a composition comprising a polyol and a polyisocyanate (F), wherein the polyol comprises at least a polyalkylene oxide (A) and a polyol (B) different from the polyalkylene oxide (A), and the polyisocyanate (F) has an allophanate structure and has an average number of isocyanate functional groups in the range of 2.01 to 3.19 as calculated by gel permeation chromatography (GPC).

[0013] The polyalkylene oxide (A) and the polyol (B) different from the polyalkylene oxide (A) may react with the polyisocyanate (F1) used for chain extension in the polyisocyanate (F) to form a part or all of the urethane prepolymer (E) having an active hydrogen group terminal, which will be described later; the urethane-forming composition (G) contains the active hydrogen group-terminated urethane prepolymer (E) and a polyisocyanate (F2), the urethane prepolymer (E) being a reaction product of the polyisocyanate (F1), and a polyol containing at least the polyalkylene oxide (A) and a polyol (B) different from the polyalkylene oxide (A), and the polyisocyanate (F1), the polyisocyanate (F2) containing an allophanate structure, and having an average number of isocyanate functional groups in the range of 2.01 to 3.19 as calculated by gel permeation chromatography (GPC). Alternatively, the urethane-forming composition (G) may be a polyisocyanate (F) containing an allophanate structure as a whole, and having an average number of isocyanate functional groups of the entire polyisocyanate (F) calculated by gel permeation chromatography (GPC) in the range of 2.01 to 3.19.

[0014] The contents of the polyol and polyisocyanate (F) in the urethane-forming composition (G) are not particularly limited. However, to more easily achieve both high strength and good wettability to the adherend, the weight ratio of the total amount of two or more different polyols to the polyisocyanate (F) is preferably in the range of 80 / 20 to 1 / 99, more preferably 70 / 30 to 15 / 85, and most preferably 60 / 40 to 25 / 75. The molar ratio (equivalent number) of NCO groups in the polyisocyanate (F) to the total amount of active hydrogen groups in the active hydrogen compound containing the polyalkylene oxide (A) and polyol (B) is not particularly limited, but is typically in the range of 0.1 to 10. In particular, the molar ratio is preferably in the range of 0.5 to 4, more preferably 1.01 to 2, to more easily achieve low surface tack and high wettability in the cured urethane.

[0015] The preparation of the urethane-forming composition (G) is not particularly limited as long as it is a method capable of uniformly dispersing the prepolymer and raw materials, and examples thereof include stirring methods using various conventionally known stirring methods. Examples of stirrers include general-purpose stirrers, planetary mixers, disperser dispersers, kneaders, mixers, Labo Plastomills, and planetary mixers. When the urethane-forming composition (K) is liquid at the stirring temperature, general-purpose stirrers, planetary mixers, disperser dispersers, and dissolvers are preferably used.

[0016] The viscosity of the urethane-forming composition (G) at 25°C is not particularly limited, but is typically from 0.001 to 100 Pa·s, preferably from 0.2 to 30 Pa·s, and more preferably from 0.3 to 10 Pa·s. A viscosity of the urethane-forming composition (G) at 25°C within this range is preferred because it facilitates stirring and handling of the urethane-forming composition (G) when stirring with various stirrers for preparation or when stirring as a preliminary step before coating with a coating machine or the like.

[0017] The urethane-forming composition (G) may contain, but is not limited to, a solvent, a chain extender, an antistatic agent, a plasticizer, a reaction retarder, a leveling agent, a catalyst, and other additives. It may also contain catalysts such as an isocyanate-modifying catalyst and a urethanization catalyst used in forming the raw material polyol, urethane prepolymer (E), and polyisocyanate (F), solvents, additives, and residual polyol.

[0018] The chain extender is not particularly limited, and examples thereof include glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, pentaerythritol, and low-molecular-weight polyalkylene glycols having a molecular weight of 1,000 or less; and polyvalent amines such as ethylenediamine, N-aminoethylethanolamine, piperazine, isophoronediamine, and xylylenediamine.

[0019] The antistatic agent is not particularly limited, but examples thereof include alkali metal salts and ionic liquids, such as lithium salts such as lithium bis(trifluoromethanesulfonyl)imide, quaternary ammonium salts, imidazolium salts, phosphonium salts, and pyridinium salts.

[0020] The plasticizer is not particularly limited, but examples thereof include fatty acid esters, alicyclic esters, polyether esters, and the like, such as epoxidized fatty acid esters, myristate esters, and terminal ester-modified compounds of polyalkylene glycols.

[0021] Examples of solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, benzene, dioxane, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, glycol ether solvents, etc. Among these, glycol ether solvents, ethyl acetate, toluene, methyl ethyl ketone, or mixed solvents thereof are preferred because they are easy to handle, such as in terms of solubility and the boiling point of the organic solvent, and also because the resulting urethane cured product tends to exhibit higher transparency.

[0022] Among these, glycol ether solvents having an sp value of 8.0 or more are preferred because they remain in the system during drying and curing for a longer period of time, maintaining compatibility, and stably suppressing cure shrinkage that tends to occur during reaction curing, making it easier to form urethane with good moldability and a wrinkle-free, good appearance. Examples of glycol ether solvents include diethylene glycol diethyl ether (sp value 8.2, boiling point 189°C), triethylene glycol dimethyl ether (sp value 8.4, boiling point 216°C), diethylene glycol ethyl methyl ether (sp value 8.1, boiling point 176°C), diethylene glycol dimethyl ether (sp value 8.1, boiling point 162°C), tetraethylene glycol dimethyl ether (sp value 8.5, boiling point 275°C), and propanediol. Examples include pyrene glycol monomethyl ether acetate (sp value 8.7, boiling point 146 ° C), ethylene glycol monomethyl ether acetate (sp value 9.0, boiling point 145 ° C), ethylene glycol monobutyl ether acetate (sp value 8.9, boiling point 188 ° C), methoxybutyl acetate (sp value 8.7, boiling point 171 ° C), triacetin (sp value 10.2, boiling point 260 ° C), and the like. Among these, diethylene glycol diethyl ether (sp value 8.2, boiling point 189 ° C), triethylene glycol dimethyl ether (sp value 8.4, boiling point 216 ° C), and ethylene glycol monobutyl ether acetate (sp value 8.9, boiling point 188 ° C) are most preferred. Furthermore, the use of ethyl acetate, toluene, and methyl ethyl ketone in combination makes it easy to adjust the moldability.

[0023] The urethanization catalyst may include, but is not limited to, amine catalysts and metal catalysts. To facilitate efficient formation of a cured urethane product, minimize side reactions, and yield a more transparent urethane prepolymer and cured urethane product, a metal-containing urethanization catalyst is preferably used in an amount of 0.001 to 0.2 wt %, more preferably 0.003 to 0.1 wt %, and most preferably 0.005 to 0.05 wt %. The metal-containing urethanization catalyst is not particularly limited as long as it contains a metal component and exhibits urethanization activity. However, organometallic compounds containing one or more of Fe, Sn, Zr, Ti, and Al are preferred. Among these, Sn catalysts, which are readily available and have low temperature dependence of catalytic activity, and one or more metal chelate catalysts, such as Fe chelate catalysts, Zr chelate catalysts, Ti chelate catalysts, and Al chelate catalysts, which are easily adjustable in reactivity, are more preferred, as they facilitate efficient formation of NCO-terminated urethane prepolymers. Most preferably, an Fe chelate catalyst is used alone.

[0024] The Sn catalyst is not particularly limited, but examples thereof include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diversatate, and dibutyltin bis(acetylacetonate). The Fe chelate catalyst is not particularly limited, but examples thereof include iron trisacetylacetonate, etc.; Zr chelate catalysts include zirconium tetraacetylacetonate and zirconium ethylacetoacetate, etc.; Ti chelate catalysts include titanium acetylacetonate and titanium ethylacetoacetate, etc.; and Al chelate catalysts include aluminum trisacetylacetonate, etc.

[0025] The reaction retarder is not particularly limited, and various retarders can be used, such as additives that have the effect of suppressing the activity of the urethanization catalyst (acid retarders, chelating compounds, etc.), additives that prevent the molecular weight of the main component from increasing during the reaction (thickening inhibitors, etc.), and additives that reduce the reactivity of isocyanates or polyol prepolymers (acid retarders, stabilizers, etc.), and it is preferable to use a combination of such retarders.

[0026] Among them, it is preferable to use one or more of acid retarders, chelating compounds, thickening inhibitors, and stabilizers as the reaction retarder, more preferably two to four of acid retarders, chelating compounds, thickening inhibitors, and stabilizers in combination, and most preferably three to four of acid retarders, chelating compounds, and thickening inhibitors, each including one or more.Furthermore, the acid retarders, chelating compounds, and thickening inhibitors are not limited to one type each, and two or more types can be used in combination, which is preferable.

[0027] In particular, when the polyol (B) has an aromatic amine residue, it is preferable to include an acid retarder, since it is easier to suppress the catalytic activity derived from the amine structure, extend the usable time, and easily suppress sudden gelation during drying, aging, and coating, and it is easier to stably suppress wrinkles and improve moldability. Therefore, it is preferable to include an acid retarder, and although not particularly limited, it is preferable to include an acid having a pKa of 5.0 or less.

[0028] Examples of such acids with a pKa of 5.0 or less include hydrochloric acid, nitric acid, phosphoric acid, and phosphorus-based acid retarders such as acidic phosphate esters having 2 to 20 carbon atoms, such as ethyl acid phosphate and 2-ethylhexyl acid phosphate. Among these, phosphorus-based acid retarders are preferred because they tend to provide a good balance between reactivity and physical properties. When an acid retarder is used, its content is preferably in the range of 0.001 to 1 part by weight, more preferably 0.005 to 0.1 part by weight, per 100 parts by weight of the total amount of polyol components. Furthermore, when an acid retarder is used, the pH of the polyol components is preferably in the range of 4 to 9, as this tends to result in high curability and low corrosiveness. The pH of the polyol components refers to the value measured with a pH meter after dispersing the polyol components at 7% solids in a 5:3 mixture of water and IPA.

[0029] The chelating compound preferably contains one or more of a keto-enol tautomer compound and a triazole derivative, because it is easy to adjust the catalytic activity and suppress thickening after mixing with a crosslinking agent, and also easy to improve moldability. It is more preferable to use one or more of each of a keto-enol tautomer compound and a triazole derivative (two or more in total) as the chelating compound.

[0030] The keto-enol tautomeric compound is not particularly limited, but is preferably one or more of ethyl acetoacetate or acetylacetone, which can more easily adjust the catalytic activity and improve moldability. When such a keto-enol tautomeric compound is contained, the molar ratio (keto-enol tautomeric compound / metal catalyst) relative to the urethanization catalyst containing a metal component is preferably 10 times or more, more preferably 50 to 5,000 times, in order to more easily improve moldability, and is preferably 0.01 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of the total amount of the polyol components.

[0031] The triazole derivative is not particularly limited, but is preferably a benzotriazole derivative having a phenolic hydroxyl group, as it has a high effect of suppressing cure shrinkage and is easy to form a urethane with good coating film appearance. More preferably, it is a benzotriazole derivative having a phenolic hydroxyl group, which is liquid at room temperature, has a molecular weight in the range of 300 to 700, and has an aryl group having a phenolic hydroxyl group directly bonded to the benzotriazole, as it tends to increase the transparency of the urethane. Examples of the above compound include, but are not limited to, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571 manufactured by BASF), and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-benzenepropionic acid (C7-9 alkyl ester) (TINUVIN 99-2, TINUVIN 384-2 manufactured by BASF). When a triazole derivative is used, the content is preferably in the range of 0.1 to 3 parts by weight per 100 parts by weight of the total amount of the polyol components, and more preferably in the range of 0.2 to 2 parts by weight, and most preferably in the range of 0.3 to 1.5 parts by weight, since this makes it easier to form a coating film with higher transparency and better appearance.

[0032] When a keto-enol tautomeric compound and a triazole derivative are used in combination as chelate compounds, the weight ratio of the keto-enol tautomeric compound to the triazole derivative (keto-enol tautomeric compound / triazole derivative) is preferably 0.5 or more and 50 or less, and more preferably 2 or more and 20 or less, because this tends to suppress wrinkles in the resulting urethane and improve moldability.

[0033] The thickening inhibitor is not particularly limited, but examples thereof include compounds that delay the increase in molecular weight or crosslinking degree that is associated with thickening during the reaction, and compounds that suppress thickening even when the molecular weight increases due to the reaction.

[0034] Examples of such compounds include a compound that is reactive with an isocyanate crosslinking agent and that delays the increase in molecular weight by proceeding in parallel with or prior to the reaction between the polyol or prepolymer (E) and the polyisocyanate (F), and a compound that suppresses or reduces the increase in viscosity of the system by improving affinity or changing structure due to the increase in molecular weight.

[0035] Among these, it is preferable that the thickening inhibitor is a compound having a lower molecular weight than the polyol or prepolymer (E) and having an active hydrogen group reactive with the polyisocyanate (F). By including such a thickening inhibitor, the reaction proceeds in parallel with and / or prior to the reaction between the polyol or prepolymer (E) and the polyisocyanate (F), which makes it easier to suppress crosslinking between the polyols or prepolymers and thereby suppress thickening.

[0036] Such thickening inhibitors are preferably compounds with a molecular weight of 1000 or less, which tend to have high active hydrogen group reactivity, because they react more readily than the base compound and inhibit crosslinking between polyols or prepolymers, thereby inhibiting thickening. In particular, if the molecular weight is too low, the reactivity of the active hydrogen groups may be too high, resulting in premature reaction and consumption, shortening the period during which thickening can be inhibited, reducing the reaction delay effect, or they may be partially or completely removed during the drying process, resulting in unstable physical properties. If the molecular weight is too high, thickening may occur during the reaction, reducing the reactivity of the active hydrogen groups, facilitating reaction between base compounds and reducing the thickening inhibition effect. Therefore, the molecular weight is preferably in the range of 60 to 700, more preferably in the range of 90 to 300, and most preferably in the range of 100 to 160. Furthermore, it is preferable for such thickening inhibitors to have 2 to 8 active hydrogen groups, such as hydroxyl groups, amino groups, or thiol groups, per molecule, because this reduces the degree of crosslinking during the reaction and the tensile strength. In particular, since too many active hydrogen groups tend to increase the degree of crosslinking during the reaction between the thickening inhibitor and the polyisocyanate (F) and reduce the thickening inhibitory effect, it is preferable for the thickening inhibitor to have 2 to 4 active hydrogen groups such as hydroxyl groups, amino groups, or thiol groups per molecule, more preferably 2 to 3 hydroxyl groups per molecule, and most preferably a diol having two primary hydroxyl groups per molecule, as this has moderate reactivity and tends to significantly enhance the thickening inhibitory effect.When a thickening inhibitor is used, its content is preferably in the range of 0.1 to 3 parts by weight per 100 parts by weight of the total polyol components, more preferably 0.2 to 2 parts by weight per 100 parts by weight of the total polyol components, and most preferably 0.3 to 1.5 parts by weight per 100 parts by weight of the total polyol components, as this tends to form a urethane with higher transparency and better physical properties. Furthermore, when the thickening inhibitor has an active hydrogen group, the thickening inhibitor is likely to have a high thickening inhibitory effect while maintaining the urethane properties, so it is preferable to add the thickening inhibitor in an amount within the range of 3 to 30 mol % relative to 100 mol % of the active hydrogen groups in the polyol component, and more preferably within the range of 5 to 20 mol %.

[0037] The stabilizer is not particularly limited, but examples include compounds that suppress the reactivity of isocyanates and polyol prepolymers, such as phenolic antioxidants. Furthermore, in this embodiment, triazole derivatives are not included as stabilizers. Using such antioxidants in an increased amount of 1,000 ppm or more, preferably 3,000 ppm or more, and most preferably in the range of 5,000 ppm to 20,000 ppm, stabilizes the isocyanates and polyol prepolymers, reduces their reactivity, and inhibits thickening. Among these, BHT and hindered phenolic antioxidants with molecular weights of 1,000 or less (such as the Irganox series), which are readily available and have good compatibility with urethanes, are preferred. Room-temperature liquids such as Irganox 1135 and Irganox 1726 are preferred because they tend to increase the transparency of the resulting urethane. However, highly compatible structures such as BHT, Irganox 1076, and Irganox 1010 are also suitable because they are uniformly dispersed in the prepolymer and do not impair transparency during urethane formation.

[0038] When a stabilizer is used, its content is preferably in the range of 0.1 to 3 parts by weight per 100 parts by weight of the total amount of the polyol components. In particular, the content of the stabilizer is more preferably in the range of 0.2 to 2.5 parts by weight, and most preferably in the range of 0.5 to 2 parts by weight, since this makes it easier to form a urethane with higher transparency and better physical properties.

[0039] Among these, the urethane-forming composition (G) preferably contains a keto-enol tautomeric compound and a hindered phenol-based antioxidant, and the pot life of the composition is 12 hours or longer, as this facilitates improved productivity and yield during the manufacturing process. More preferably, the urethane-forming composition (G) contains 0.5 to 10 parts by weight of the keto-enol tautomeric compound and 0.1 to 2 parts by weight of the hindered phenol-based antioxidant per 100 parts by weight of the total polyol components, and the pot life of the composition is 15 hours or longer. This composition facilitates the production of compositions with such properties, resulting in significantly superior productivity. The pot life refers to the period during which the urethane-forming composition (G) containing both a polyol, a prepolymer, and an isocyanate can be left at room temperature after preparation and remain in a state suitable for coating and use. In this specification, the pot life refers to the period during which a viscosity increase of 30% or less can be maintained and coatability can be maintained without unevenness.

[0040] The urethane-forming composition (G) can be a urethane-forming composition solution containing the urethane-forming composition (G), an organic solvent, and additives. To facilitate easy handling, the mixture is preferably mixed in an amount ratio that results in a solids concentration in the range of 10 to 99% by weight, more preferably 40 to 97% by weight, and most preferably 70 to 95% by weight. Furthermore, to facilitate easy handling during mixing with a crosslinking agent and coating, and to facilitate the stable production of a highly transparent cured urethane product, the viscosity at 25°C is preferably in the range of 3 to 50 Pa·s, more preferably 5 to 30 Pa·s.

[0041] The transparency of the urethane-forming composition (G) and the urethane-forming composition solution is not particularly limited, but since the urethane cured product tends to be transparent regardless of the crosslinking conditions, it is preferable that the urethane-forming composition (G) is also generally transparent, and more preferably the haze at a thickness of 100 μm is 15% or less, and such properties are easily obtained by using the urethane-forming composition (G). In particular, the haze at a thickness of 100 μm is preferably 5% or less, and most preferably 1% or less, and if the average number of functional groups of the isocyanate compound (F) is less than 3.0, compatibility is improved and such properties are easily obtained.

[0042] Furthermore, when the polyalkylene oxide (A) and polyol (B) components form an active hydrogen group-terminated urethane prepolymer (E), although this is not particularly limited, it is more preferable that the active hydrogen group-terminated urethane prepolymer (E), which is a reaction product of the polyalkylene oxide (A), the polyol (B), and the polyisocyanate (F1), and the crosslinking agent polyisocyanate (F2) are contained, and that the polyisocyanate (F1) and the polyisocyanate (F2) have an average number of isocyanate functional groups in the range of 2.01 to 3.19 as calculated by gel permeation chromatography (GPC). This is because the resulting urethane prepolymer (E) has a more appropriate viscosity, excellent moldability, and good curability.

[0043] When polyalkylene oxide (A) and polyol (B) form an active hydrogen group-terminated urethane prepolymer (E), the contents of the active hydrogen group-terminated urethane prepolymer (E) and polyisocyanate (F2) in the urethane-forming composition (G) are not particularly limited. However, to more easily achieve both high strength and good wettability to the adherend, the weight ratio of the urethane prepolymer (E) to the polyisocyanate (F2) is preferably in the range of 80 / 20 to 1 / 99, more preferably 70 / 30 to 15 / 85, and most preferably 60 / 40 to 25 / 75. The molar ratio (equivalents) of NCO groups in the polyisocyanate (F2) to the active hydrogen groups in the urethane prepolymer (E) is not particularly limited, but is usually in the range of 0.1 to 10. In particular, a range of 0.5 to 4 is preferred, more preferably 1.01 to 2, to easily achieve low surface tack and high wettability in the cured urethane. <Polyol> The urethane-forming composition (G) contains a polyalkylene oxide (A), a polyol (B), and a polyisocyanate (F). The polyalkylene oxide (A) and the polyol (B) may react, as necessary, with the polyisocyanate (F) or a polyisocyanate (F1) used for chain extension in the polyisocyanate (F) to form a urethane prepolymer (E) having an active hydrogen group at its terminal.

[0044] The polyalkylene oxide (A) and the polyol (B) are not particularly limited as long as they contain polyalkylene oxides (A) and polyols (B) that differ in structure, such as initiator structure, monomer structure, monomer composition ratio, and molecular weight. However, they may contain polyols or monools other than the polyalkylene oxide (A) and the polyol (B), as this makes it easier to achieve both better low tack and high wettability. <Polyalkylene oxide (A)> Examples of such polyalkylene oxides (A) include, but are not limited to, structures having alkylene oxide residues and active hydrogen groups. However, the number-average molecular weight of the polyalkylene oxide (A) is preferably 2,500 or more, because this ensures that the urethane-forming composition (G) containing the polyalkylene oxide (A) or a urethane prepolymer obtained therefrom has a suitable viscosity, leading to excellent handleability and coatability, and that the resulting cured urethane product tends to have good wettability. Among these, the number-average molecular weight is preferably 3,000 or more but less than 30,000, more preferably 3,500 or more but less than 13,000, and most preferably 3,600 or more but less than 9,000. The number-average molecular weight of the polyalkylene oxide (A) can be calculated from the hydroxyl value of the polyalkylene oxide (A) calculated by the method described in JIS K-1557-1 and the number of hydroxyl groups per molecule of the polyalkylene oxide (A). The hydroxyl value (mgKOH / g) of the polyalkylene oxide (A) is not particularly limited, but is preferably 3 or more and 250 or less, more preferably 5 or more and 180 or less, and most preferably 8 or more and 70 or less.

[0045] The viscosity of the polyalkylene oxide (A) at 25°C is not particularly limited and can be selected appropriately depending on the application. However, it is preferably 100 mPa·s or more and 200,000 mPa·s or less, and more preferably 200 mPa·s or more and 10,000 mPa·s or less. A viscosity of 100 mPa·s or more and 200,000 mPa·s or less at 25°C is preferred because it facilitates coating when applied using a coating machine or the like to obtain a polyurethane product. Here, the "viscosity" at 25°C is the value measured using a cone-plate rotational viscometer at a shear rate of 0.1 (1 / s) in accordance with JIS K1557-5, Section 6.2.3.

[0046] The polyalkylene oxide (A) preferably contains an alkylene oxide residue having 3 or more carbon atoms because it has low viscosity and excellent fluidity from low to high temperatures, and tends to provide good urethane physical properties such as strength, elongation, and durability. The alkylene oxide residue having 3 or more carbon atoms is not particularly limited, and examples thereof include alkylene oxide residues having 3 to 20 carbon atoms. Specific examples include propylene oxide residue, 1,2-butylene oxide residue, 2,3-butylene oxide residue, isobutylene oxide residue, butadiene monoxide residue, pentene oxide residue, styrene oxide residue, and cyclohexene oxide residue. Among these alkylene oxide residues, propylene oxide residue is preferred because the raw materials for obtaining the polyalkylene oxide (A) are easily available and the resulting polyalkylene oxide (A) has high industrial value.

[0047] Furthermore, the polyalkylene oxide (A) may contain only a single alkylene oxide residue as the alkylene oxide residue having 3 or more carbon atoms, or may contain two or more types of alkylene oxide residues. When two or more types of alkylene oxide residues are contained, for example, one type of alkylene oxide residue may be linked in a chain to another alkylene oxide residue, or two or more types of alkylene oxide residues may be linked randomly. Furthermore, the polyalkylene oxide (A) may contain an ethylene oxide residue having 2 carbon atoms in addition to the alkylene oxide residue having 3 or more carbon atoms.

[0048] The number of hydroxyl groups in the polyalkylene oxide (A) is not particularly limited, but it is preferable that one molecule contains two or more hydroxyl groups, more preferably two to six, and most preferably two to three. When the number of hydroxyl groups in one molecule of the polyalkylene oxide (A) is six or less, the crosslinked structure of the resulting urethane cured product is less likely to become dense, and the tensile elongation at break and strength are further increased, which is preferable.

[0049] The primary hydroxyl group ratio of the polyalkylene oxide (A) is not particularly limited, but is preferably in the range of 0 to 90% because it tends to be excellent in productivity. In particular, although not particularly limited, when an active hydrogen group-terminated urethane prepolymer (E) is not formed, particularly when two-stage polymerization such as forming an NCO group-terminated prepolymer and then adding a polyol (B) is not performed, increasing the primary hydroxyl group ratio of the polyalkylene oxide (A) makes it easier for the reaction with the polyol used in combination to proceed uniformly even in one shot, and tends to improve compatibility, transparency, and curability, so the primary ratio is more preferably in the range of 50 to 90%, and even more preferably in the range of 75 to 90%.

[0050] When synthesis is carried out using a cationic polymerization system such as trifluoroborane or trispentafluorophenylborane as a catalyst, the primary ratio tends to be high even when propylene oxide or the like other than ethylene oxide is used as the alkylene oxide, whereas the primary ratio tends to be low when a base catalyst such as potassium hydroxide or a metal catalyst such as a complex metal cyanide (DMC) catalyst is used, but there are no particular limitations, including on the terminal structure, and either can be suitably used.

[0051] The polyalkylene oxide (A) is preferably liquid at room temperature, as this facilitates the production of a urethane prepolymer or a urethane-forming composition.

[0052] The degree of unsaturation of the polyalkylene oxide (A) is not particularly limited because it is easy to achieve high transparency in prepolymers and urethane cured products regardless of whether or not a polyalkylene oxide with a low unsaturated monool is used, but because it is likely to require an increase in the amount of a multifunctional polyol such as a polyalkylene oxide (B) having a rigid residue such as an aromatic amine residue, or a large amount of a bifunctional polyol having a more rigid skeleton than polypropylene oxide (such as polyoxytetramethylene glycol or polyester polyol), the degree of unsaturation is preferably 0.01 meq / g or less, more preferably 0.007 meq / g or less, and most preferably 0.004 meq / g or less. Such a polyalkylene oxide (A) with a low degree of unsaturation is not particularly limited, but can be produced by adding an alkylene oxide to an active hydrogen compound using an iminophosphazenium salt and a Lewis acid catalyst.

[0053] The molecular weight distribution (Mw / Mn) of the polyalkylene oxide (A) is not particularly limited because it is easy to achieve high transparency in prepolymers and urethane cured products regardless of whether or not a polyalkylene oxide with a narrow molecular weight distribution is used. However, since the molecular weight distribution of the prepolymer tends to narrow and handleability tends to be excellent, it is preferably 1.059 or less, more preferably 1.039 or less, and most preferably 1.004 to 1.029. The polyalkylene oxide (A) preferably has a water content of 2000 ppm or less, but since dehydration procedures and the like can be complicated, the water content can be selected depending on the intended use. <Polyol (B)> The polyol (B) preferably used in the urethane-forming composition (G) is not particularly limited as long as it has a hydroxyl group and is different from the polyalkylene oxide (A) in terms of the initiator structure, monomer structure, monomer composition ratio, molecular weight, etc., but examples thereof include polyether polyols obtained by ring-opening polymerization of alkylene oxide or tetrahydrofuran, polymer polyols obtained by radical polymerization of vinyl monomers in polyether polyols, polyester polyols obtained by polycondensation of polyhydric alcohols and polycarboxylic acids, and copolymers of polyhydric alcohols and polyhydric Examples of such polyols include polyesteramide polyols obtained by polycondensation of carboxylic acids and amino alcohols, polylactone polyols obtained by ring-opening polymerization of lactones, polycarbonate polyols obtained by polycondensation of polyhydric alcohols and carbonates, acrylic polyols, polybutadiene polyols and hydrogenated products thereof, polyisoprene polyols and hydrogenated products thereof, partially saponified ethylene-vinyl acetate copolymers, natural oil-based polyols such as soybean oil and castor oil, halogen- and / or phosphorus-based polyols, and phenol-based polyols. These polyols may be used singly or in combination.

[0054] The number average molecular weight of the polyol (B) is not particularly limited, but is preferably less than 2500. If the number average molecular weight is less than 2500, many urethane structures with high cohesive strength are formed, which tends to make the composition rigid, and the content of rigid residues tends to be high, which tends to further improve strength, and the reactivity is improved, which tends to make it difficult for a large amount of unreacted polyol (B) to remain, which tends to more stably achieve high transparency.

[0055] Among these, the molecular weight is preferably 200 or more and less than 2100, more preferably 400 or more and less than 1500, and most preferably 450 or more and less than 1000, because this makes the composition less susceptible to instability due to evaporation or the like, and the content of rigid residues is increased, resulting in stable high strength and excellent fluidity. When a polyol having an acrylic residue is used, the weight average molecular weight of the polyol is usually relatively high, ie, not less than 400 and less than 2,000,000, and the number of functional groups may also be high, but it can be suitably used.

[0056] The number average molecular weight of the polyol (B) can be calculated from the hydroxyl value of the polyol (B) calculated by the method described in JIS K-1557-1 and the number of hydroxyl groups in one molecule of the polyol (B). In the case of commercially available products, the nominal number of functional groups and hydroxyl value can be used.

[0057] The polyol (B) preferably has one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues, because this tends to increase the curability of the urethane-forming composition and tends to enable the resulting cured urethane to exhibit good easy releasability regardless of high strength, hardness, and release speed. Suitable examples of the polyol (B) having such residues include, but are not limited to, polyoxytetramethylene glycol, sugar-based polyols having a sugar residue of 6 or more carbon atoms, aromatic amine-based polyols, polyester polyols, acrylic polyols, and polyolefin polyols.

[0058] By including the above-mentioned residues, which are more rigid than alkylene oxide residues, in the polyol (B), the hardness and strength of the resulting polyurethane tend to be significantly increased. Among these, it is more preferable for the polyol (B) to include one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, and polyester residues, because these residues tend to exhibit good fluidity, resulting in excellent moldability and wettability, and also tend to have high hardness and strength, resulting in excellent urethane physical properties. Most preferable is a polyol (B) having an aromatic amine residue.

[0059] Examples of polyols having a polyoxytetramethylene residue include polyoxytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran alone, polyether polyols obtained by ring-opening addition polymerization of tetrahydrofuran to an initiator such as ethylenediamine, tolylenediamine, sucrose, sorbitol, aminoalcohols, glycerin, diethylene glycol, or low-molecular-weight polypropylene glycol having a molecular weight of 1,000 or less, and polyether polyols obtained by ring-opening addition polymerization of alkylene oxides such as ethylene oxide and propylene oxide to polyoxytetramethylene glycol, and any of these can be suitably used. When a polyol (B) having a polyoxytetramethylene residue is contained, it is not particularly limited, but it is preferable that it contains a polyoxytetramethylene residue and has two or more hydroxyl groups in one molecule, and it may be a continuous polymer of oxytetramethylene, or a block, graft, or random copolymer containing an oxytetramethylene structure. When a polyol having a polyoxytetramethylene residue is contained, the content of the oxytetramethylene residue in the polyol (B) is not particularly limited and is appropriately selected depending on the application, but is preferably in the range of 70 to 100%, more preferably in the range of 90 to 100%. If the content of the oxytetramethylene residue is 70% or more, the desired strength is easily achieved, which is preferable.

[0060] Examples of polyols having a polyester residue include compounds derived from polybasic acids and polyhydric alcohols. Examples of suitable polyols include, but are not limited to, polyester polyols derived from polybasic acids such as adipic acid, orthophthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, succinic acid, azelaic acid, sebacic acid, linosylic acid, trimellitic acid, dimethyl terephthalate, and polyethylene terephthalate, and polyhydric alcohols such as ethylene glycol, diethylene glycol, 3-methyl-1-5-pentanediol, hexanediol, neopentyl glycol, methylpropanediol, butylethylpropanediol, trimethylolpropane, and glycerin, as well as lactone-based polyester polyols obtained by ring-opening polymerization of cyclic esters such as ε-caprolactone and methylvalerolactone.

[0061] Other examples include polyester polyether polyols obtained by ring-opening addition polymerization of an alkylene oxide, such as ethylene oxide or propylene oxide, or tetrahydrofuran to a polyester polyol. When a polyol (B) having a polyester residue is contained, it is not particularly limited, but preferably contains an ester residue and has two or more hydroxyl groups in one molecule, and may be a continuous polyester polymer or a block, graft, or random copolymer containing a polyester. When a polyol having a polyester residue is contained, the content of the ester residue in the polyol (B) is not particularly limited and may be selected appropriately depending on the application, but is preferably in the range of 30 to 100%, more preferably 70 to 100%. An ester residue content of 30% or more is preferred because it facilitates the development of the desired strength.

[0062] The polyol having a sugar residue having 6 or more carbon atoms is not particularly limited, but is preferably a polyol containing a sugar residue having 6 or more carbon atoms in one molecule and having an alkylene oxide residue and four or more hydroxyl groups, and may be any of those in which one type of alkylene oxide is linked in a chain to a sugar having 6 or more carbon atoms, or those in which multiple alkylene oxides are linked in a chain or randomly to a sugar having 6 or more carbon atoms. Among these, because alkylene oxide is easily available industrially and synthesis is easy, those in which only propylene oxide is linked in a chain to a sugar having 6 or more carbon atoms, those in which only ethylene oxide is linked in a chain to a sugar having 6 or more carbon atoms, and those in which propylene oxide and ethylene oxide are linked in a chain or randomly to a sugar having 6 or more carbon atoms are preferred.

[0063] When polyol (B) having a sugar residue with 6 or more carbon atoms per molecule is contained, polyol (B) preferably further has 4 or more hydroxyl groups per molecule, more preferably 4 to 12 hydroxyl groups per molecule, and most preferably 5 to 8 hydroxyl groups per molecule. When polyol (B) having a sugar residue with 6 or more carbon atoms per molecule has 4 to 12 hydroxyl groups per molecule, the crosslinked structure of the resulting polyurethane tends to be uniform, and the strength is further increased, which is preferable.

[0064] The polyol (B) containing a sugar residue having 6 or more carbon atoms per molecule is not particularly limited in structure, but is preferably a sugar residue having 6 to 20 carbon atoms per molecule, more preferably 6 to 12 carbon atoms per molecule. Examples of such sugar residues include maltitol residue, maltose residue, glucose residue, fructose residue, sucrose residue, and sorbitol residue. Preferred are sucrose residue and sorbitol residue, which are readily available as raw materials and tend to exhibit good curability and tensile strength at break. Of these, it is most preferred to contain a sucrose residue because it has a cyclic structure and is likely to exhibit high strength.

[0065] Polyol (B) containing sugar residues having 6 or more carbon atoms per molecule is generally obtained by ring-opening polymerization of alkylene oxide using a sugar having 6 or more carbon atoms, such as sucrose or sorbitol, as an initiator, but may also be synthesized by using a low-viscosity active hydrogen compound that does not contain a sugar residue having 6 or more carbon atoms, such as diethylenetriamine, triethanolamine, diethylene glycol, glycerin, or propylene glycol, in combination with the initiator, and may contain components having such residues. For example, sorbitol typically has 6 hydroxyl groups, and sucrose typically has 8 hydroxyl groups, but the number of hydroxyl groups can be reduced by using an initiator that does not contain a sucrose or sorbitol residue, or by terminal blocking, for example.

[0066] Commercially available polyalkylene oxides containing sucrose residues include Huntsman's JEFFOLS A-499 (nominal functionality 4.3, hydroxyl value 495), JEFFOL SD-361 (nominal functionality 4.4, hydroxyl value 360), and JEFFOLS G-522 (nominal functionality 5.0, hydroxyl value 520), and Toho Chemical Industry's Toho Polyol O-850 (nominal functionality 8, hydroxyl value 380). Examples of polyalkylene oxides containing sorbitol residues include Huntsman's JEFFOLS-490 (nominal functionality 4.7, hydroxyl value 490), and these can be suitably used.

[0067] The polyol having an aromatic amine residue is not particularly limited, but is preferably a polyol containing an aromatic amine residue in one molecule and having an alkylene oxide residue and two or more hydroxyl groups, and may be any of those in which one type of alkylene oxide is linked in a chain to an aromatic amine, or those in which multiple alkylene oxides are linked in a chain or randomly to an aromatic amine.

[0068] Among these, alkylene oxides are preferably those in which only propylene oxide is linked in a chain to an aromatic amine, those in which only ethylene oxide is linked in a chain to an aromatic amine, or those in which propylene oxide and ethylene oxide are linked in a chain or randomly to an aromatic amine, because alkylene oxides are easily available industrially and synthesis is easy. Among these, those having propylene oxide residues are preferred because they are resistant to crystallization from low to high temperatures and tend to have particularly excellent fluidity, and most preferably 40% by weight or more of the alkylene oxide residues contained in the polyalkylene oxide (B) are propylene oxide residues.

[0069] When the polyol (B) contains an aromatic amine residue, the polyol (B) preferably has two or more hydroxyl groups per molecule, more preferably 3 to 12 hydroxyl groups per molecule, and most preferably 4 to 6 hydroxyl groups per molecule. When the polyol (B) containing an aromatic amine residue per molecule has 3 to 12 hydroxyl groups per molecule, the crosslinked structure of the polyurethane is more likely to be uniform, and the strength is further increased, which is preferable.

[0070] The structure of the aromatic amine residue of the polyol (B) containing an aromatic amine residue in one molecule is not particularly limited, but is preferably an aromatic amine residue having 1 to 20 aromatic rings in one molecule, more preferably 1 to 3 aromatic amine residues.

[0071] Examples of such aromatic amine residues include aniline residues, 2,4-tolylenediamine residues, 2,6-tolylenediamine residues, 2,4'-diphenylmethanediamine residues, 4,4'-diphenylmethanediamine residues, polyphenylenepolyamine residues, 1,5-naphthalenediamine residues, tolidinediamine residues, xylylenediamine residues, 1,3-phenylenediamine residues, 1,4-phenylenediamine residues, and mixed residues of two or more of these. Preferred are 2,4-tolylenediamine residues, 2,6-tolylenediamine residues, and mixed residues of two or more of these, which are readily available as raw materials and tend to exhibit good curability and tensile strength at break.

[0072] The polyol (B) containing an aromatic amine residue in one molecule is generally obtained by ring-opening polymerization of an alkylene oxide using an aromatic amine such as tolylenediamine or diphenylmethanediamine as an initiator, but it may also be synthesized by using a low-viscosity active hydrogen compound that does not contain an aromatic amine residue, such as ethylenediamine, diethylenetriamine, triethanolamine, diethylene glycol, glycerin, or propylene glycol, in combination with the initiator, and may contain a component having the above residue.

[0073] For example, typically, a tolylenediamine-initiated polyol has four hydroxyl groups, and an aniline-initiated polyol has two hydroxyl groups. However, the number of hydroxyl groups may decrease due to the combined use of an initiator that does not contain a tolylenediamine residue or an aniline residue, or due to the presence of residual amino groups to which no alkylene oxide has been added.

[0074] Commercially available polyols containing aromatic amine residues include JEFFOLAD-310 (nominal functionality 3.2, hydroxyl value 310) and JEFFOLAD-500 (nominal functionality 3.2, hydroxyl value 360) manufactured by Huntsman, TOHO POLYOL AB-250 (nominal functionality 2.0, hydroxyl value 440) manufactured by Toho Chemical Industry Co., Ltd., AR-2589 (nominal functionality 4.0, hydroxyl value 360) manufactured by Toho Chemical Industry Co., Ltd., and AR-750 (nominal functionality 4.0, hydroxyl value 300) manufactured by Toho Chemical Industry Co., Ltd., and these can be suitably used.

[0075] The polyol (B) may be used in combination of two or more kinds, and is not particularly limited. Examples include a combination of a polyol having an oxytetramethylene residue and a polyol containing a sugar residue having 6 or more carbon atoms, a combination of a polyol having an oxytetramethylene residue and a polyol having an aromatic amine residue, a combination of a polyol containing a sugar residue having 6 or more carbon atoms and a polyol having an aromatic amine residue, a combination of a polyol having a polyester residue and a polyol having an oxytetramethylene residue, and the like. Three or more kinds of the above may also be combined.

[0076] Examples of polyols having a polyolefin residue include polymers and copolymers of diolefins having 4 to 12 carbon atoms, such as butadiene and isoprene, and copolymers of diolefins having 4 to 12 carbon atoms and α-olefins having 2 to 22 carbon atoms, which contain hydroxyl groups. The method for incorporating hydroxyl groups is not particularly limited, but for example, a method of reacting a diene monomer with hydrogen peroxide is available. Furthermore, the remaining double bonds may be hydrogenated to form saturated aliphatic compounds. Among these, polybutadiene polyols, polyisobutylene polyols, polyisoprene polyols, and the like are preferred because they tend to exhibit higher urethane strength and are readily available.

[0077] Examples of polyols having an acrylic residue include acrylic resins having a hydroxyl group, and are not particularly limited. For example, those obtained by polymerizing or copolymerizing hydroxyethyl acrylate, hydroxybutyl acrylate, and various other acrylic acid esters can be preferably used. Among them, although not particularly limited, acrylic oligomers having a hydroxyl group can be preferably used because they have excellent moldability and tend to exhibit high durability, and examples thereof include the ARUFON-UH series manufactured by Toagosei Co., Ltd. <Other polyols and monools (C)> The urethane-forming composition (G) is not particularly limited, but may contain other polyols and monools (C) in addition to the polyalkylene oxide (A), polyol (B), and polyisocyanate (F) exemplified above, in order to improve curability and coatability, improve desired properties of the resulting urethane cured product, and adjust the ratio of NCO groups in the polyisocyanate (F) to the total amount of active hydrogen groups in the polyol.

[0078] The other polyols and monools (C) can be appropriately selected from those that do not impair the transparency and various physical properties of the prepolymer, and are not particularly limited. Examples include commercially available polyols such as polycarbonate polyol, polytetramethylene glycol, polyolefin polyol, acrylic polyol, polyester polyol, Mannich polyol, sucrose polyol, aliphatic diamine polyol, polyethylene glycol, polycaprolactone polyol, fluorinated polyol, silicone-containing polyol, and phosphorus-based polyol; monools such as polyoxyalkylene glycol monoalkyl ether, polyoxyalkylene glycol monoalkenyl ether, polyoxyalkylene glycol monophenyl ether, and silicone-containing monool; and low-molecular-weight organic compounds such as cyclohexanedimethanol, tetraethylene glycol, tripropylene glycol, and tripropylene glycol monobutyl ether.

[0079] Among these, one or more selected from the group consisting of polyoxyalkylene glycol monoalkyl ethers, polyoxyalkylene glycol monoalkenyl ethers, and polyoxyalkylene glycol monophenyl ethers are preferred because they provide particularly excellent coatability when applied using a coater or the like, and among these, it is preferred to add polyoxyethylene glycol monomethyl ether having a molecular weight of 250 or more and 1300 or less because this tends to provide excellent coatability, maintain high transparency, and reduce the staining and tackiness of the resulting urethane.

[0080] <Polyisocyanate (F)> The polyisocyanate (F) used in the urethane-forming composition (G) contains an allophanate structure and has an average number of isocyanate functional groups in the range of 2.01 to 3.19 as calculated by gel permeation chromatography (GPC). If the polyisocyanate (F) does not contain an allophanate structure or if the average number of isocyanate functional groups of the polyisocyanate (F) exceeds 3.19, the effect of improving wettability to the adherend due to dangling chains derived from the allophanate groups and the like and the desired compatibility cannot be obtained, resulting in insufficient wettability, low productivity during lamination and difficult use. If the average number of isocyanate functional groups is less than 2.01, the polyisocyanate becomes too flexible, does not exhibit low tackiness and has poor curability, making it difficult to use.

[0081] The allophanate structure is not particularly limited, but examples thereof include, and are preferably, those represented by the following chemical formula (1).

[0082] [ka]

[0083] [R1 in the chemical formula (1) is a monool residue or a polyol residue.] Furthermore, when R1 in the chemical formula (1) is a polyol residue, it is not particularly limited, but examples thereof include, and are preferably, the structure shown in the following chemical formula (2).

[0084] [ka]

[0085] [R1 in the chemical formula (2) is a polyol residue, and typically has a structure in which an n-valent hydroxyl group is removed from a polyol, where n typically ranges from 2 to 100.] An allophanate structure that is more preferably contained in the polyisocyanate (F) is a structure represented by the following chemical formula (3), and by containing this structure, better transparency is likely to be exhibited.

[0086] [ka]

[0087] [In the chemical formula (3), R1 is a monool residue or a polyol residue, which is a residue obtained by removing a hydroxyl group from a monool or a polyol. R2 and R3 are residues of a polyisocyanate, which are residues obtained by removing an NCO group from a polyisocyanate, and R2 and R3 may be the same or different. When there are a plurality of R2s and R3s, they may be the same or different, and are not particularly limited. The n is usually in the range of 1 to 100.] R1 in chemical formula (3) is preferably a monol residue or polyol residue having 1 to 50 carbon atoms, as this tends to provide better compatibility, more preferably a monol residue or polyol residue having 2 to 30 carbon atoms, and most preferably a monol residue or polyol residue having a saturated hydrocarbon residue having 2 to 30 carbon atoms, as this tends to provide significantly better compatibility.

[0088] R2 and R3 in chemical formula (3) are preferably any one or more of an aromatic isocyanate residue, an aliphatic isocyanate residue, an alicyclic isocyanate residue, or a residue of a modified product of these isocyanates, because these are highly versatile and tend to exhibit good physical properties; more preferably any one or more of an aliphatic isocyanate residue, an alicyclic isocyanate residue, or a residue of a modified product of these isocyanates, because these tend to have excellent transparency; and most preferably any one or more of residues of 1,6-hexamethylene diisocyanate, isophorone diisocyanate, allophanate-modified products and / or isocyanurate-modified products of these isocyanates.

[0089] In chemical formula (3), n is preferably in the range of 1 to 10, since this increases mobility and tends to provide better wettability, more preferably an integer in the range of 1 to 2 (R1 is a monool residue or a diol residue), and most preferably n=1 (R1 is a monool residue).

[0090] The polyisocyanate (F) may contain other modified structures in addition to the allophanate structure, and although not particularly limited, preferred examples include urethane-modified structures with polyols such as trimethylolpropane and polyoxytetramethylene glycol, and monools such as polyethylene glycol monoalkyl ether, urea-modified structures with polyamines, carbodiimide-modified structures, uretdione-modified structures, and isocyanurate-modified structures.

[0091] Among these, it is preferable for the polyisocyanate (F) to contain both an allophanate structure and a nurate structure, since this tends to exhibit higher curability and low tack while maintaining good wettability. It is more preferable to use a polyisocyanate (F) containing both structures in one molecule, but this is not particularly limited, and any polyisocyanate (F) containing both an allophanate structure and a nurate structure throughout the entire molecule can be suitably used. That is, a polyisocyanate (F) containing both structures may be used, for example, by modifying the polyisocyanate through concerted allophanation and nuration, or a polyisocyanate (F) containing both components may be used, for example, by mixing a polyisocyanate having an allophanate structure with a polyisocyanate containing a nurate structure. Both of these tend to exhibit good wettability and high curability.

[0092] The molar ratio of the allophanate structure to the nurate structure in the polyisocyanate (F) is preferably in the range of 10 / 90 to 90 / 10, more preferably in the range of 15 / 85 to 70 / 30, and most preferably in the range of 20 / 80 to 50 / 50, because this makes it easier to achieve both wettability and low tackiness.

[0093] Two or more types of polyisocyanate may be used as the polyisocyanate (F). When multiple polyisocyanates are used, it is sufficient that at least one of the raw materials contains an allophanate structure. There are no particular limitations on the average number of isocyanate functional groups in the entire polyisocyanate, as long as it is in the range of 2.01 to 3.19. The average number of isocyanate functional groups in the entire polyisocyanate (F) and the presence or absence of allophanate structures may be determined by, for example, decomposing the obtained polyurethane cured product as needed and analyzing the structure of the isocyanate fraction. The average number of isocyanate functional groups in the polyisocyanate (F) was calculated using the number average molecular weight of the polyisocyanate calculated by gel permeation chromatography (GPC) and the isocyanate content (isocyanate group concentration) according to the following formula:

[0094] Number of isocyanate functional groups = (number average molecular weight of polyisocyanate × isocyanate group concentration) / (42 × 100) When a plurality of polyisocyanates are used, the average number of isocyanate functional groups in the entire polyisocyanate (F) may be determined from the amount of each raw material used, the average number of isocyanate functional groups in each raw material, and the number average molecular weight of the polyisocyanate.

[0095] The average number of isocyanate functional groups of the polyisocyanate (F), calculated by gel permeation chromatography (GPC), is preferably in the range of 2.10 to 2.99, more preferably in the range of 2.20 to 2.90, even more preferably in the range of 2.30 to 2.80, and most preferably in the range of 2.40 to 2.70, since this makes it easier to achieve both high strength and wettability.

[0096] The isocyanate content in the polyisocyanate (F) is preferably in the range of 1 to 50% by weight, more preferably in the range of 5 to 30% by weight, and most preferably in the range of 12 to 19% by weight, since it has a moderate viscosity, excellent handleability, and is likely to contain a modified structure that exhibits high strength and wettability. The isocyanate content in the polyisocyanate (F) was calculated by a back titration method in which isocyanate groups were consumed using excess dibutylamine and the amine residue was titrated with hydrochloric acid, according to a conventional method, and this value was used to calculate the average number of functional groups.

[0097] Examples of the polyisocyanate (F) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexyl methyl acrylate, methyl acrylate, methyl acrylate copolymer, methyl acrylate copolymer, methyl acrylate copolymer, methyl acrylate copolymer, methyl acrylate copolymer Examples of the isocyanate include xylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, norbornane diisocyanate, lysine ester triisocyanate, 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate, modified isocyanates obtained by reacting these with polyalkylene oxides, and mixtures of two or more of these. Further examples include modified products of these isocyanates containing a urethane group, a carbodiimide group, an allophanate group, a urea group, a biuret group, an isocyanurate group, an amide group, an imide group, a uretonimine group, a uretdione group, or an oxazolidone group, and condensates such as polymethylene polyphenylene polyisocyanate (polymeric MDI).

[0098] Among these, aliphatic isocyanates, alicyclic isocyanates, or modified products thereof are preferred because they are highly productive and allow for the easy production of a highly transparent and minimally colored urethane-forming composition (G) and a highly transparent and minimally colored urethane cured product using the same. For example, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, aliphatic isocyanate-containing prepolymers, alicyclic isocyanate-containing prepolymers, and modified products of these isocyanates containing urethane groups, carbodiimide groups, allophanate groups, urea groups, biuret groups, isocyanurate groups, amide groups, imide groups, uretonimine groups, uretdione groups, or oxazolidone groups are more preferred. These isocyanates may be used alone or in combination of two or more.

[0099] Among these, 1,6-hexamethylene diisocyanate and its modified products are preferred because they have high reactivity, good productivity, and excellent storage stability with little increase in viscosity of the urethane prepolymer (E) over time. Isophorone diisocyanate is also preferred because it contains primary and secondary NCO groups with different reactivities, which helps to suppress polymerization due to chain reactions, provides excellent coatability and viscosity, and significantly improves the transparency of the urethane-forming composition and the urethane cured product obtained using the same. Therefore, at least one selected from 1,6-hexamethylene diisocyanate, its modified products, and isophorone diisocyanate is preferred.

[0100] In the case where the polyalkylene oxide (A) and polyol (B) in the urethane-forming composition (G) are partially or entirely prepolymerized, the polyisocyanates can be divided into, but are not limited to, polyisocyanates (F1) used for prepolymer chain extension and polyisocyanates (F2) used for crosslinking prepolymers, which may be the same or different, and at least one of them preferably contains an allophanate structure. When polyisocyanates (F1) and (F2) are used, the average number of isocyanate functional groups may be in the range of 2.01 to 3.19, but it is sufficient that at least one of them has an average number of isocyanate functional groups of 2.01 or more and the overall average number of isocyanate functional groups is in the range of 2.01 to 3.19. Furthermore, when the number of functional groups of the polyisocyanate (F1) used for chain extension is low, better handleability is exhibited, and when the number of functional groups of the polyisocyanate (F2) used for crosslinking is high, high curability is exhibited, and it is therefore easier to achieve both properties at the same time. Therefore, it is more preferable that the average number of functional groups of the polyisocyanate (F2) is in the range of 2.01 to 3.19 and the average number of functional groups of the polyisocyanate (F1) is in the range of 2.00 to 2.90, and the overall average number of isocyanate functional groups is in the range of 2.10 to 2.99.

[0101] Among these, it is preferable that the number of functional groups of the polyisocyanate (F1) used for chain extension is lower than that of the polyisocyanate (F2) used for crosslinking, since this tends to maintain good handleability while exhibiting significantly good curability upon crosslinking, thereby exhibiting both properties at a higher level.

[0102] As the polyisocyanate used for the polyisocyanate (F1) and the polyisocyanate (F2), the polyisocyanates exemplified in the section on the polyisocyanate (F) can be mentioned and can be suitably used.

[0103] Among these, the polyisocyanate (F1) used for chain extension is not particularly limited, but preferably contains a bifunctional polyisocyanate because it is less likely to gel during prepolymer formation and the structure is easier to control, more preferably contains one or more selected from 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and allophanate-modified products thereof, and most preferably contains one or more selected from 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and allophanate-modified products thereof in an amount of 70 to 100 mol % in the polyisocyanate (F1).

[0104] The average number of isocyanate functional groups of the polyisocyanate (F1) is not particularly limited, but is preferably in the range of 2.0 to 2.9, more preferably in the range of 2.0 to 2.6, and most preferably in the range of 2.0 to 2.3, in order to prevent gelation during prepolymer formation and to make it easier to control the structure.

[0105] The isocyanate content in the polyisocyanate (F1) is preferably in the range of 1 to 50% by weight, more preferably in the range of 5 to 50% by weight, and most preferably in the range of 15 to 50% by weight, because the prepolymer is less likely to gel, has excellent handleability, and is easy to design with an appropriate viscosity.

[0106] The polyisocyanate (F2) used for crosslinking the prepolymers is not particularly limited, but preferably contains a trifunctional or higher polyisocyanate, since this improves the curing property during the crosslinking reaction and makes it easier to obtain a urethane cured product with lower tack and higher strength. Among these, it is preferable to contain one or more selected from an isocyanurate-modified product of 1,6-hexamethylene diisocyanate and an isocyanurate-modified product of isophorone diisocyanate, and more preferably, the polyisocyanate (F2) contains one or more selected from an isocyanurate-modified product of 1,6-hexamethylene diisocyanate and an isocyanurate-modified product of isophorone diisocyanate, since this makes it easier to exhibit significantly better wettability while maintaining high curability and low tack. The preferred range is 10 to 90 mol% of the above, and 10 to 90 mol% of one or more selected from the group consisting of allophanate-modified 1,6-hexamethylene diisocyanate and allophanate-modified isophorone diisocyanate. The most preferred range is 30 to 85 mol% of isocyanurate-modified 1,6-hexamethylene diisocyanate, and 15 to 70 mol% of allophanate-modified 1,6-hexamethylene diisocyanate.

[0107] The average number of isocyanate functional groups in the polyisocyanate (F2) is not particularly limited, but is preferably in the range of 2.01 to 3.19, more preferably 2.2 to 2.99, and most preferably 2.4 to 2.89, because this improves curing during the crosslinking reaction and facilitates the production of a urethane cured product with lower tack and higher strength. Commonly used isocyanurate crosslinkers that are substantially free of allophanate structures (e.g., Tosoh's Coronate HX, Coronate HXR, Coronate HXLV, and Coronate HK) contain not only trifunctional trimer structures but also tetrafunctional pentamers and pentafunctional or higher oligomers, and therefore generally have a functionality greater than three, typically 3.2 or greater. Similarly, urethane-modified isocyanate crosslinkers using trimethylolpropane also contain not only trifunctional units but also tetrafunctional or higher units linked via isocyanates, and therefore generally have a functionality greater than three, typically 3.2 or greater.

[0108] The isocyanate content in the polyisocyanate (F2) is preferably in the range of 1 to 50% by weight, more preferably in the range of 5 to 30% by weight, and most preferably in the range of 10 to 19% by weight, because the urethane-forming composition has an appropriate viscosity, is excellent in coatability, is less likely to have poor appearance such as cissing, and can easily introduce a large number of modified structures, thereby easily exhibiting higher curability and wettability.

[0109] The viscosity of the polyisocyanate (F2) is not particularly limited, but is preferably in the range of 150 to 1900 mPa·s. Difunctional polyisocyanates having only allophanate groups in the modified structure typically have a low viscosity of less than 150 mPa·s, which can cause the urethane-forming composition to flow and result in poor moldability due to cissing during curing and drying. General-purpose polyisocyanates having a functionality of more than 3.2 and having only isocyanurate groups in the modified structure typically have a high viscosity of more than 1900 mPa·s, which can easily result in poor moldability during application of the urethane-forming composition. Therefore, using a polyisocyanate (F2) having a viscosity in the above range is preferred, as it makes it easier to obtain a urethane-forming composition (G) with better moldability.

[0110] In particular, the viscosity of the polyisocyanate (F2) is preferably in the range of 250 to 1500 mPa·s, more preferably 350 to 1300 mPa·s, and most preferably 400 to 1200 mPa·s, because it has a suitable viscosity and tends to have excellent moldability. In particular, in the present invention, since the modified structure contains an allophanate group, the compatibility with the urethane-forming composition is excellent and transparency tends to be high, and designing the isocyanate (F2) to have a viscosity in the above range is preferable, because it tends to exhibit high curability while further improving transparency and moldability. <Urethane prepolymer (E)> The polyalkylene oxide (A) and polyol (B) in the urethane-forming composition (G) may form a urethane prepolymer (E), and are not particularly limited thereto. However, it is preferable that they form a urethane prepolymer (E) because this provides an appropriate viscosity and excellent moldability.

[0111] The urethane prepolymer (E) is not particularly limited, but preferably contains a reaction product of a polyalkylene oxide (A) having a molecular weight of 2500 or more, a polyol (B) having a molecular weight of less than 2500, and a polyisocyanate (F1), as this tends to achieve both better wettability and higher strength.

[0112] The weight ratio of the polyalkylene oxide (A) residue content to the polyol (B) residue content in the urethane prepolymer (E) is preferably in the range of 90 / 10 to 10 / 90 (polyalkylene oxide (A) residue / polyol (B) residue), more preferably in the range of 80 / 20 to 20 / 80, and most preferably in the range of 70 / 30 to 35 / 65.

[0113] The method for producing the urethane prepolymer (E) is not particularly limited, but it is preferable to produce an active hydrogen group-terminated urethane prepolymer (E) by mixing the polyisocyanate components in a ratio such that the molar ratio of the total amount of NCO groups in the polyisocyanate component to the total amount of active hydrogen groups in the polyol component (NCO / OH molar ratio) is 0.05 to 0.70. Also, when an NCO group-terminated urethane prepolymer is formed in advance and then a polyol component is newly added to form the active hydrogen group-terminated urethane prepolymer (E), it is preferable to mix the polyisocyanate components in a ratio such that the molar ratio of the total amount of polyisocyanate groups in all raw materials to the total amount of active hydrogen groups in all raw materials (total NCO / total OH molar ratio) is 0.05 to 0.70.

[0114] By mixing the raw materials in a quantity ratio such that the NCO / OH ratio of all raw materials is 0.05 to 0.70, it becomes easier to stably form a urethane prepolymer (E) with terminal hydroxyl groups, moderate viscosity, and better coatability, as well as a more transparent cured urethane product.

[0115] Among these, it is preferable to mix them in an amount that results in a final NCO / OH ratio of 0.10 to 0.60, and more preferably in the range of 0.15 to 0.50, because this provides excellent handleability due to an appropriate viscosity while suppressing gelation and high viscosity, reduces the amount of unreacted polyol remaining in the urethane prepolymer (E), and the urethane prepolymer (E) and the cured urethane product tend to have higher transparency and an excellent appearance, and are more likely to exhibit significant strength and low tack.

[0116] Furthermore, when an NCO-terminated urethane prepolymer is used as an intermediate, it is preferable to mix them in a ratio such that the ratio of NCO groups in the polyisocyanate component to the total amount of active hydrogen groups in the polyol component (NCO / OH ratio) is 1.30 to 5.00. Mixing in a ratio such that the NCO / OH ratio is 1.30 to 5.00 makes the product less likely to gel, has a moderate viscosity, and is easy to handle, and the transparency of the resulting cured urethane product is likely to be improved. In particular, when an NCO-terminated urethane prepolymer is used, it is preferable that the ratio of NCO groups in the polyisocyanate component to the total amount of active hydrogen groups in the polyol component (NCO / OH ratio) is in the range of 1.60 to 4.40, and more preferably in the range of 1.90 to 3.60.

[0117] When forming the urethane prepolymer (E), it is preferable to contain an alkylene oxide residue having 3 or more carbon atoms. By containing an alkylene oxide residue having 3 or more carbon atoms, the strength of the resulting urethane cured product tends to increase, and the storage stability and handleability tend to improve. Furthermore, by containing an alkylene oxide residue having 3 or more carbon atoms, the crystallinity tends to decrease compared to when only alkylene oxide residues having 2 carbon atoms are contained, and the transparency of the urethane prepolymer (E) and the resulting urethane cured product, as well as the storage stability and handleability of the urethane prepolymer (E), tend to improve.

[0118] The alkylene oxide residue having 3 or more carbon atoms is not particularly limited, and examples thereof include alkylene oxide residues having 3 to 20 carbon atoms. Specific examples include propylene oxide residue, 1,2-butylene oxide residue, 2,3-butylene oxide residue, isobutylene oxide residue, butadiene monoxide residue, pentene oxide residue, styrene oxide residue, cyclohexene oxide residue, etc. Among these alkylene oxide residues, propylene oxide residue is preferred because the raw material polyalkylene oxide is easily available, and a liquid urethane prepolymer (E) having low crystallinity and appropriate viscosity can be easily produced, making it highly industrially valuable.

[0119] The alkylene oxide residue having 3 or more carbon atoms may contain only a single alkylene oxide residue, or may contain two or more types of alkylene oxide residues. When two or more types of alkylene oxide residues are contained, for example, one type of alkylene oxide residue may be linked in a chain to another alkylene oxide residue, or two or more types of alkylene oxide residues may be linked randomly. Furthermore, it is sufficient that the alkylene oxide residue has 3 or more carbon atoms, and in addition to this, an ethylene oxide residue having 2 carbon atoms may be contained. When an ethylene oxide residue having two carbon atoms is contained, its content is not particularly limited, but in order to easily achieve excellent fluidity and high coatability, the weight ratio of alkylene oxide residues having three or more carbon atoms to ethylene oxide residues having two carbon atoms (alkylene oxide residues having three or more carbon atoms / ethylene oxide residues having two carbon atoms) is preferably in the range of 10 / 90 to 99.9 / 0.1, more preferably in the range of 30 / 70 to 99.7 / 0.3, and most preferably in the range of 50 / 50 to 99.5 / 0.5. When an ethylene oxide residue having two carbon atoms is contained, it is not particularly limited, but in order to easily achieve excellent coatability, it is preferable that the composition has a chain structure of ethylene oxide residues having two carbon atoms, such as a polyoxyethylene glycol monoalkyl ether residue.

[0120] The content of alkylene oxide residues having 3 or more carbon atoms that are preferably contained in the urethane prepolymer (E) is not particularly limited, but is preferably 30% by weight to 99% by weight to facilitate the development of good coating properties and high transparency, more preferably 50% by weight to 95% by weight to facilitate the realization of both higher transparency and high strength, and most preferably 70% by weight to 90% by weight. The content can be calculated by analysis using NMR or Corisch decomposition, or if the raw materials are known, it may be calculated from the amounts added or the structure of the raw materials.

[0121] In addition to alkylene oxide residues, the urethane prepolymer (E) preferably contains one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues. The inclusion of these residues, which are more rigid than alkylene oxide residues, improves the strength of the urethane prepolymer (E) and the resulting cured urethane product, significantly improving strength-related physical properties such as easy peelability and durability, and also improving the curability of the urethane prepolymer, resulting in good productivity. In other words, the presence of these residues, which form a rigid skeleton, improves the curability of the urethane prepolymer and the strength of the resulting cured urethane product.

[0122] The content of one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues, which are preferably contained in the urethane prepolymer (E), is not particularly limited, but is preferably 0.5 to 55% by weight to facilitate the development of high strength, more preferably 1 to 35% by weight to facilitate the compatibility of higher strength with the handleability of the cured product, and most preferably 3 to 15% by weight. The content can be calculated by analysis such as NMR or Colish degradation, but if the raw materials are known, it can also be calculated from the molecular weight of the polyalkylene oxide calculated from the hydroxyl value, the nominal initiator structure, and the amount added.

[0123] The urethane prepolymer (E) preferably contains one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues, and the residues contained in the polyols exemplified in the section on polyol (B) having such rigid residues are preferred as residues, and these raw material compositions can also be exemplified as preferred structures. Among these, it is more preferred to contain one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, and polyester residues, and most preferably an aromatic amine residue, because these residues tend to exhibit good fluidity, resulting in excellent moldability and wettability, and also tend to have high hardness and strength, resulting in excellent urethane physical properties.

[0124] The introduction site of the rigid residue preferably contained in the urethane prepolymer (E) into the prepolymer may be either inside the molecule or at the molecular end, and is not particularly limited. However, since this tends to result in excellent compatibility and higher transparency, it is preferable to have a polyol structure or residue having the rigid residue at the molecular end. The method for producing such a urethane prepolymer (E) is not particularly limited. For example, a production method in which an NCO-terminated prepolymer is formed from a polyalkylene oxide (A) and a polyisocyanate (F) to be used in combination, and then a polyol (B) having the rigid residue is reacted with the prepolymer in the latter stage of a multi-stage reaction, or a method in which a highly reactive active hydrogen group such as a primary hydroxyl group or an amino group is introduced into the polyalkylene oxide (A) to be used in combination with the polyol (B) having the rigid residue to improve reactivity, thereby facilitating the addition of the polyol (B) having the rigid residue in the latter stage of the reaction, thereby introducing the prepolymer near the molecular end, which is easily obtainable.

[0125] When the urethane prepolymer (E) is formed, it contains a polyisocyanate residue. The polyisocyanate residue preferably has an average functionality of 2.0 or more, but is not particularly limited thereto. The structure of the polyisocyanate residue is not particularly limited, and examples thereof include the residues of polyisocyanate (F) exemplified in the section on polyisocyanate (F) as preferred residues, and the raw material compositions thereof can also be exemplified as preferred structures. Among these, the residues of polyisocyanate (F1) exemplified as the polyisocyanate (F1) used for chain extension can also be exemplified as preferred residues, and the raw material compositions thereof can also be exemplified as preferred structures. Specifically, for example, it is preferable that the polyisocyanate contains a residue of a bifunctional polyisocyanate, more preferably a residue of one or more selected from 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and allophanate-modified products thereof, and most preferably a residue of one or more selected from 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and allophanate-modified products thereof in the polyisocyanate residue in an amount of 70 to 100 mol %. The average number of original isocyanate functional groups in the polyisocyanate residue is not particularly limited, but is preferably in the range of 2.0 to 2.9, more preferably in the range of 2.0 to 2.6, and most preferably in the range of 2.0 to 2.3, in order to reduce gelation during prepolymer formation and to facilitate structural control.

[0126] The content of polyisocyanate residues contained in the urethane prepolymer (E) is not particularly limited, but is preferably 0.5% by weight to 30% by weight to facilitate the development of high strength, more preferably 2% by weight to 20% by weight to facilitate the realization of both higher transparency and high strength, and most preferably 4% by weight to 12% by weight. The content can be calculated by analysis using NMR or Corisch decomposition, or if the raw materials are known, it may be calculated from the amounts added.

[0127] The urethane prepolymer (E) may contain other residues in addition to the alkylene oxide residues and polyisocyanate residues having 3 or more carbon atoms, which are exemplified as essential components, and the preferred residues, which are exemplified as polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues, and ethylene oxide residues having 2 carbon atoms. Examples of residues that may be preferably contained include, but are not limited to, carbonate residues, oxetane residues, caprolactone residues, alkyl ether residues, Mannich polyol residues, silicone residues, fluorine residues, phosphate ester residues, aliphatic amine residues, imine residues, quaternary ammonium residues, and isocyanurate residues. Among these, alkyl ether residues are preferred because the urethane prepolymer (E) exhibits higher curability and good coatability, making it easier to obtain a high-strength urethane cured product. When the exemplified residues are contained, their content is not particularly limited, but is preferably in the range of 0.01% by weight to 70% by weight, more preferably in the range of 0.1% by weight to 50% by weight, and most preferably in the range of 0.5% by weight to 20% by weight, since this makes it easier to achieve both high curability and coatability.

[0128] Furthermore, the urethane prepolymer (E) may contain a monool structure having an unsaturated group in the polyalkylene oxide used, and may contain an unsaturated group that is the residue thereof.

[0129] Since the urethane prepolymer (E) exhibits high curability regardless of whether or not a polyalkylene oxide with a low unsaturated monool content is used, the unsaturated group content is not particularly limited and varies depending on the raw materials used, but since it tends to exhibit higher curability, it is preferable that the unsaturated group content be in the range of 0.0001 meq / g to 100 meq / g. When it does not substantially contain highly reactive unsaturated groups such as urethane acrylate groups or urethane methacrylate groups that can act as reactive groups, it tends to exhibit higher curability, so the unsaturated group content is preferably in the range of 0.0003 meq / g to 0.050 meq / g, more preferably in the range of 0.0005 meq / g to 0.010 meq / g, and most preferably in the range of 0.0007 meq / g to 0.002 meq / g. The unsaturated group content can be analyzed by various analytical methods such as NMR.

[0130] The molecular weight of the urethane prepolymer (E) is not particularly limited, but the weight average molecular weight measured by gel permeation chromatography is preferably in the range of 2,500 or more and 500,000 or less, more preferably in the range of 5,000 or more and 200,000 or less, and more preferably in the range of 10,000 or more and 100,000 or less, because this tends to improve handleability.

[0131] When the urethane prepolymer (E) contains an aromatic amine residue, the structure of the aromatic amine residue is not particularly limited, but is preferably an aromatic amine residue having 1 to 20 aromatic rings per molecule, and more preferably an aromatic amine residue having 1 to 3 aromatic rings. Examples of such aromatic amine residues include aniline residues, 2,4-tolylenediamine residues, 2,6-tolylenediamine residues, 2,2'-diphenylmethanediamine residues, 2,4'-diphenylmethanediamine residues, 4,4'-diphenylmethanediamine residues, polyphenylenepolyamine residues, 1,5-naphthalenediamine residues, tolidinediamine residues, xylylenediamine residues, 1,3-phenylenediamine residues, 1,4-phenylenediamine residues, and residues of two or more of these. Preferred are 2,4-tolylenediamine residues, 2,6-tolylenediamine residues, and residues of two or more of these, which are readily available as raw materials and tend to exhibit good curability and high strength. The structure of the aromatic amine residue can be analyzed by MALDI-TOF-MS or the like.

[0132] The aromatic amine residues preferably contained in the urethane prepolymer (E) are usually obtained by adding an aromatic amine or aromatic amine polyol to the terminal or internal portion of the molecule, but the inclusion of a polyol structure having an aromatic amine residue or a residue thereof is preferred because it tends to have excellent compatibility and higher transparency. The content of the polyol structure having an aromatic amine residue or a residue thereof is preferably 5 to 70 wt %, more preferably 10 to 55 wt %, and most preferably 20 to 50 wt %, because this tends to result in significantly higher strength and improved coatability. The content of the polyol structure having an aromatic amine residue or a residue thereof can be calculated by analysis such as alkaline decomposition or Corisch decomposition, or, if the raw materials are known, it may be calculated from the added amounts.

[0133] The urethane prepolymer (E) may be used as needed to reduce viscosity, inhibit cure shrinkage, improve coatability, etc. by using a solvent before or after urethane prepolymer formation to form a urethane prepolymer solution, or by using a catalyst or additive to form a urethane prepolymer composition or a urethane prepolymer composition solution, which are preferred. <Method for producing polyurethane (H) and urethane coating> The urethane-forming composition (G) can be reacted and cured (solidified) by various methods to produce polyurethane (H). The method for producing polyurethane (H) is not particularly limited, but for example, polyurethane (H) can be produced by subjecting a composition containing the urethane-forming composition (G) to a urethane-forming reaction and a urea-forming reaction at room temperature or a high temperature of 150°C or less in the presence of a urethane-forming catalyst, a solvent, an antioxidant, a light stabilizer, a chain extender, a crosslinking agent, other additives, etc., as necessary, and then drying the resulting mixture as necessary.

[0134] Here, since the coating properties when applied using a coating machine or the like are remarkably excellent, a urethane coating film of uniform thickness can be obtained, and although not particularly limited, forming and curing a coating film is preferred. A coating film of the polyurethane (H) can be formed on a base substrate such as a PET film or a COP film by various methods, and if necessary, laminated or molded with another substrate such as release PET or release paper, to form a polyurethane sheet having the urethane coating film on the substrate. Also, by forming a coating film on a releasable substrate such as release PET or release paper, and if necessary, laminated or molded with another substrate such as release PET or release paper, a polyurethane sheet having the urethane coating film inside with double-sided release layers can be formed, and by peeling off the release layers, a polyurethane sheet consisting of the urethane coating film alone can also be formed.

[0135] Among these, the process is preferred because it allows for the highly productive production of a urethane coating film made of a highly transparent, low-tack polyurethane (H) through a process of mixing the raw materials to produce a urethane-forming composition (G), a process of applying the composition to a substrate in a thickness of 1 to 500 μm, and a process of drying and curing the composition at 70 to 160° C. for 30 seconds to 10 minutes.More preferably, the process includes a process of applying the composition to a thickness of 150 μm or less, and more preferably a process of applying the composition to a thickness in the range of 10 to 100 μm, because this process is more likely to produce a coating film that is excellent in curability, highly transparent, and has better wettability.

[0136] Furthermore, the urethane-forming composition (G) is not particularly limited, but because it has a relatively low viscosity and contains allophanate residues that tend to have high wettability, it is preferably dried and cured at 80 to 150°C for 1 to 30 minutes to prevent flow during drying and to rapidly cure, and more preferably dried and cured at 110 to 145°C for 2 to 10 minutes, which is more likely to result in superior productivity for urethane coating films.

[0137] The applications of polyurethane (H) and urethane coatings are not particularly limited, and they can be used in any application where ordinary polyurethanes are used, but they are particularly suitable for applications requiring mechanical properties, wettability, transparency, tackiness and adhesive properties, etc. Specific examples of applications where they can be used preferably include sealing materials for construction and civil engineering, adhesives such as elastic adhesives for construction, packing tapes and surface protection films, various pressure-sensitive adhesives typically for optical applications, paints, elastomers, waterproof coating materials, flooring materials, plasticizers, flexible polyurethane foams, semi-rigid polyurethane foams, and rigid polyurethane foams.

[0138] Among these, polyurethanes are particularly preferred for use as sealants, paints, pressure-sensitive adhesives, adhesives, and elastomer materials, as they are required to have strong mechanical properties and adhesive / bonding properties, and are also required to have good workability and coatability. <Urethane adhesive sheet> The polyurethane (H) obtained using the urethane-forming composition (G) has excellent wettability and low tack, and therefore quickly conforms to various articles when attached to them. It also has good air release properties, which makes it highly productive, and it is particularly suitable for use as a urethane pressure-sensitive adhesive sheet. Among these, because it has the characteristic properties of exhibiting good wettability even in a thin film and excellent low tack, it is likely to exhibit remarkable easy releasability when peeled off at a certain speed or higher, and the polyurethane (H) layer thickness is 1 to 200 μm, and when attached to non-alkali glass, the peel force when peeled off at 2,500 mm / min is likely to be 0.20 N / 25 mm or less, making it suitable for use in applications requiring such properties. Furthermore, it has high transparency and excellent visibility, and has an optically transparent PET substrate, a polyurethane (H) layer thickness of 10 to 120 μm, and when attached to non-alkali glass, the peel force when peeled off at 2,500 mm / min is likely to be 0.05 N / 25 mm or less, and a haze of 3% or less, making it particularly suitable for use in applications requiring such properties.

[0139] That is, since the composition exhibits good wettability, low tackiness, excellent releasability, and excellent compatibility, an adherend having a polyurethane (H) layer can be rapidly formed, and even after use, the composition exhibits good releasability when peeled at a peeling speed of at least a certain speed, resulting in good productivity. Furthermore, the composition tends to have characteristically good transparency, making it suitable for use in applications where such properties are required. [Example]

[0140] The present invention will be explained in more detail below with reference to examples, but the present invention should not be construed as being limited to the following examples as long as the gist of the invention is not exceeded. The raw materials and evaluation methods used in the following examples and comparative examples are as follows. (Polyol properties) The properties of the polyalkylene oxide (A), polyol (B) and polyalkylene oxide (C) used in the examples and comparative examples were determined by the following methods. <Unsaturation degree> The measurement was carried out in accordance with the NMR method described in Polymer Research, 1993, 50, 2, 121-126, with 800 scans. NMR measurements were carried out using deuterated chloroform as the heavy solvent and a JEOL 400 MHz NMR ECZS as the measuring device. <Hydroxyl value and number average molecular weight> The measurement was performed in accordance with the method described in JIS-K1557-1. The number average molecular weight was calculated from the hydroxyl value of the polyol or the like and the number of hydroxyl groups in one molecule of the polyol or the like. <Viscosity> The viscosity was measured in accordance with the method described in JIS K-1557-5 using a cone-plate rotational viscometer at a temperature of 25°C and a shear rate of 0.1 (1 / s), using an Anton-Paar MCR-300 measuring device. (Polyisocyanate properties) The properties of the polyisocyanate (F2) used in the examples and comparative examples were determined by the following methods. The properties of the polyisocyanate monomers (F1-1) and (F1-2) were determined based on their monomer structure and purity. When mixed, the properties were calculated based on the properties, composition, and mixing ratio of each raw material before mixing.

[0141] <Number of polyisocyanate functional groups> The calculation was performed using the number average molecular weight of the polyisocyanate calculated by gel permeation chromatography (GPC) and the isocyanate content (isocyanate group concentration) according to the following formula.

[0142] Number of isocyanate functional groups = (number average molecular weight of polyisocyanate × isocyanate group concentration) / (42 × 100) The measurement was carried out at 30°C using a Tosoh HLC-8320GPC, standard polystyrene as the calibration curve, tetrahydrofuran as the developing solvent, and an RI detector (differential refraction). <Allophanate group / Nurate group ratio> Calculation was performed using a method using 1H-NMR in accordance with the method described in Japanese Patent Application No. 2010-509119. Specifically, using deuterated dimethyl sulfoxide as the deuterated solvent and a JEOL 400 MHz NMR ECZS as the measuring device, calculation was performed from the area ratio of the proton bonded to the nitrogen atom of the allophanate group to the proton of the methylene group adjacent to the isocyanurate group. (Raw Material 1-1) Polyalkylene Oxide (A) Used in Examples and Comparative Examples Polyalkylene oxide (A1) was obtained by using an imino group-containing phosphazenium salt (hereinafter referred to as IPZ catalyst) in combination with triisopropoxyaluminum, thoroughly dehydrating and removing the solvent, and then adding thoroughly dehydrated propylene oxide to a bifunctional polyoxypropylene glycol with a molecular weight of 400. (A1) is a polyoxypropylene glycol (diol) that has only propylene oxide groups as alkylene oxide groups and has two hydroxyl groups per molecule.

[0143] Polyalkylene oxide (A2) is prepared in the same manner as (A1), using an IPZ catalyst and triisopropoxyaluminum in combination to add propylene oxide groups as alkylene oxide groups, and then removing the propylene oxide remaining in the system, followed by block-wise addition of ethylene oxide; it is a diol containing a primary hydroxyl group and having a low degree of unsaturation.

[0144] Polyalkylene oxide (A3) is prepared by using a trifunctional polyoxypropylene triol with a molecular weight of 600 as an initiator, and using an IPZ catalyst and triisopropoxyaluminum in combination as in (A2). Propylene oxide groups are added as alkylene oxide groups, and after removing the propylene oxide remaining in the system, ethylene oxide is added in blocks. This polyalkylene oxide is a triol containing primary hydroxyl groups and having a low degree of unsaturation. The polyalkylene oxides (A1) to (A3) used in the examples were all heated and vacuum dehydrated before use, and the catalyst, including aluminum, was removed before use.

[0145] [Table 1]

[0146] (Raw Material 1-2) Polyol (B) Used in Examples and Comparative Examples The polyol (B1) used was Toho Polyol AR-2589, a commercially available tolylenediamine-based polypropylene glycol manufactured by Toho Chemical Industry Co., Ltd., with a nominal functionality of 4.0, a hydroxyl value of 356 mg KOH / g, and a viscosity of 9,500 mPa·s at 25°C. The molecular weight calculated from this property is 630, and the aromatic amine residue content is 19%.

[0147] The polyol (B2) used was Sannix HM-551, a commercially available tolylenediamine-based polypropylene glycol / polyethylene glycol copolymer manufactured by Sanyo Chemical Industries, Ltd., with a nominal functionality of 4.0, a hydroxyl value of 413 mg KOH / g, and a viscosity of 15,000 mPa·s at 25°C. The number average molecular weight calculated from this property is 540, and the aromatic amine residue content is 22%.

[0148] The polyol (B3) used was O-855W, a commercially available sucrose-based polypropylene glycol manufactured by Toho Chemical Industry Co., Ltd., with a nominal functionality of 8.0, a hydroxyl value of 377 mgKOH / g, and a viscosity of 15,620 mPa·s at 25°C. The molecular weight calculated from this property is 1,190, and the sucrose residue content is 29%.

[0149] The polyol (B4) is a commercially available polytetramethylene glycol, PTG-1000SN manufactured by Hodogaya Chemical Co., Ltd., having a nominal functionality of 2.0, a hydroxyl value of 112 mgKOH / g, and a number average molecular weight of 1000.

[0150] The polyol (B5) is a commercially available polyester polyol, Nipporan 5711 manufactured by Tosoh Corporation, having a nominal functionality of 2.0, a hydroxyl value of 56 mgKOH / g, and a molecular weight of 2000. (Raw materials 1-3) Other polyols and monools (C) As the polyalkylene oxide (C1), polyethylene glycol monomethyl ether having a hydroxyl value of 80 mgKOH / g and a number average molecular weight of 700 was used. (Raw Material 2) Isocyanate Compound (F) Used in Examples and Comparative Examples In the examples and comparative examples, the following isocyanate compounds (F1) and (F2) were used in combination as necessary.

[0151] Isocyanate compound (F1-1): isophorone diisocyanate (IPDI). (C1) is a bifunctional isocyanate having a primary NCO group and a secondary NCO group as the isocyanate group.

[0152] Isocyanate compound (F1-2): 1,6-hexamethylene diisocyanate (HDI). (C2) is a difunctional isocyanate having only primary NCO groups as isocyanate groups.

[0153] Isocyanate compound (F2-1): Coronate 2770 manufactured by Tosoh Corporation, a 1,6-hexamethylene diisocyanate (HDI)-based allophanate-modified compound. (F2-2) has an average functionality of 2.0 isocyanate groups, a low viscosity of 100 mPa·s, and is a compound that contains substantially no isocyanurate residues.

[0154] Isocyanate compound (F2-2): Coronate HXLV manufactured by Tosoh Corporation, a 1,6-hexamethylene diisocyanate (HDI)-based isocyanurate-modified compound with a low oligomer ratio. The average functionality of the isocyanate groups in (F2-1) is 3.2, and the viscosity is 1010 mPa·s, which is lower than that of ordinary isocyanurate-modified compounds (e.g., Coronate HX, 2300 mPa·s), and the compound is substantially free of allophanate residues.

[0155] Isocyanate compound (F2-3): Coronate HL, a 1,6-hexamethylene diisocyanate (HDI) / trimethylolpropane urethane-modified compound manufactured by Tosoh Corporation. The average functionality of the isocyanate groups in (F2-3) is 3.3, the solids content is 75%, and the viscosity is 300 mPa·s. The compound is substantially free of isocyanurate residues and allophanate residues.

[0156] Isocyanate compound (F2-4): An allophanate / isocyanurate modified product of 1,6-hexamethylene diisocyanate (HDI), synthesized by simultaneously converting it to an allophanate and an isocyanurate using standard methods (e.g., Patent Application No. 2010-509119). The average functionality of the isocyanate groups in (F2-4) is 2.8, and the viscosity is moderate at 680 mPa·s. This compound contains both allophanate residues and isocyanurate residues in one component.

[0157] (Raw material 3) Urethane catalyst In the examples and comparative examples, a urethane catalyst was added. The urethane catalyst used was trisacetylacetonatoiron (abbreviated as Fe(acac)3), manufactured by Nippon Chemical Industries, Ltd., called Nacem Iron. This catalyst was added as a masterbatch of a 5% solution to improve workability. The amounts added in the tables do not include the solvent. (Raw material 4) Solvent In the examples and comparative examples, methyl ethyl ketone (abbreviated as MEK) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. and triethylene glycol dimethyl ether (abbreviated as TEGD) manufactured by Toho Chemical Industry Co., Ltd. were used as solvents. (Raw material 5) Additive (D) In the examples and comparative examples, the following compounds were added as additives to extend the pot life of the urethane-forming composition and to improve the handling and moldability. Additive (D1): Irganox 1010 (manufactured by BASF Japan) Additive (D2): Acetylacetone (manufactured by Daicel Corporation) (Production Example of Polyol Composition) The polyol compositions were produced by adding the raw materials to a glass sample container according to the synthesis examples in the table, mixing them in a sealed state, and leaving them to stand overnight. If there were visible irregularities and the mixture was not mixed properly, the mixture was mixed and degassed using a planetary centrifugal mixer manufactured by Thinky Corporation until it was visually uniform. (Production example of urethane prepolymer (E)) Urethane prepolymers (E1) to (E5) were prepared according to the synthesis examples in the table by adding polyalkylene oxide (A) and polyol (B) to a four-necked recovery flask and vacuum dehydrating at 100°C for at least one hour to remove moisture. The mixture was then cooled to below 50°C, and for solvent-based systems, the solvent, isocyanate, and catalyst masterbatch were added. The mixture was then heated to the specified temperature, and the reaction began when the specified temperature was reached. After three hours of reaction, FT-IR confirmed the disappearance of the NCO groups, yielding urethane prepolymer (E) terminated with active hydrogen groups.

[0158] Urethane prepolymers (E6) to (E10), which are prepared via NCO-terminated urethane prepolymers, were prepared by adding polyalkylene oxide (A) and, if necessary, polyol (B) to a four-necked recovery flask according to the synthesis example in the table and vacuum dehydrating at 100°C for at least one hour to remove water. The mixture was then cooled to below 50°C. For solvent-based systems, the solvent, isocyanate, and catalyst masterbatch were added, and the mixture was then heated to the specified temperature. The reaction began when the temperature was reached. After three hours of reaction, FT-IR analysis confirmed that the NCO groups remained and that there was no change in the liquid properties or the amount of NCO group. This indicated the intermediate NCO-terminated urethane prepolymer was obtained.

[0159] After cooling to below 60°C, a predetermined amount of polyol (B) was added to the intermediate NCO group-terminated urethane prepolymer. After visually confirming uniform stirring and no significant heat generation, the mixture was heated to the predetermined temperature to initiate the reaction. After 3 hours of reaction, FT-IR confirmed that the NCO groups had disappeared and that no changes in the liquid properties were observed, yielding active hydrogen group-terminated urethane prepolymer (E). (Example of production of urethane-forming composition, polyurethane) The polyol composition or urethane prepolymer (E) was measured into a 30 ml sample bottle, and if necessary, predetermined amounts of additives (D1) and (D2) were added. The mixture was mixed and degassed in advance using a planetary centrifugal mixer manufactured by Thinky Corporation until it was visually uniform. A predetermined amount of polyisocyanate (F2) was added thereto, and the mixture was mixed using a pencil mixer for about 5 minutes until it was visually uniform. The mixture was then stirred and degassed using a planetary centrifugal mixer manufactured by Thinky Corporation, to obtain a urethane-forming composition.

[0160] The urethane-forming composition was applied to a 38-μm-thick PET film using a Baker applicator so that the thickness after drying would be 80 μm. The film was then placed in an explosion-proof oven set to 130°C for 5 minutes to volatilize the solvent, and a release PET film was attached using a 5 kg roller. The film was then left to stand for 1 week in an environment of 23°C and 50% relative humidity to obtain a polyurethane sheet having a polyurethane coating on a PET substrate. (Evaluation items for urethane-forming compositions) <Curability> The urethane-forming composition was dried at 130° C. for 5 minutes, and the cured urethane was evaluated by touching with a finger according to the following criteria.

[0161] ◎ (Pass): When tack is barely noticeable, and significantly higher strength and easy peelability can be expected.

[0162] ○ (Pass): Tack is clearly felt but only slightly, and significantly high strength and easy peelability can be expected.

[0163] × (Fail): When the tack is large and the hardening is insufficient, and significantly high strength and easy peelability cannot be expected. <compatibility> ⊚ (Pass): The urethane-forming composition is generally transparent to the naked eye, and the resulting cured urethane product is uniformly transparent with no visible unevenness.

[0164] ○ (Pass): The urethane-forming composition is uniformly cloudy, but the resulting cured urethane product is uniformly transparent with no visible unevenness.

[0165] △ (Fail): The urethane-forming composition is generally transparent to the naked eye, but slight drag marks appear on the resulting cured urethane product (determined to be unevenness due to insufficient compatibility during crosslinking and solvent removal).

[0166] × (fail): The urethane-forming composition becomes cloudy and the resulting cured urethane has drag marks or becomes cloudy, or the urethane-forming composition becomes cloudy and separates upon standing. <Wettability to substrate> The release PET was peeled off from a urethane sheet (2.5 cm x 9 cm) having a polyurethane layer on a PET substrate obtained according to the manufacturing example, and immediately 0.5 cm of the urethane edge was placed on an alkali-free glass whose surface had been washed with acetone and dried. The sheet was wetted under its own weight and evaluated based on the time it took for the wetness to spread to the opposite urethane edge, according to the following criteria.

[0167] ◎ (Pass): When the wetting spreads and reaches the edge within 20 seconds.

[0168] ○ (Pass): If the end is reached within 20 to 60 seconds. △ (Fail): When it takes more than 60 seconds to reach the end.

[0169] × (Fail): If the edge is not reached. <Low tack> After drying and primary curing, a release PET sheet was attached and left to stand at room temperature for one week for aging. After secondary curing, the tackiness of the cured urethane was evaluated according to the following criteria, and this was used as a measure of the strength of the cured product when fully cured, and the ease of peeling when peeled at a certain speed or faster.

[0170] ◎ (Pass): If you cannot feel any tack at all.

[0171] ○ (Pass): When tack is not felt at all (significantly small tack equal to or greater than the hardening evaluation standard ◎).

[0172] × (fail): Tackiness is clearly noticeable (curability evaluation standard: ○ or lower).

[0173] Those that passed both the curability and compatibility were judged to be urethane-forming compositions that can be expected to exhibit significantly high strength, easy releasability, and transparency, and those that passed both the adherend wettability and low tack were judged to be polyurethanes that can be expected to have excellent productivity when attached to articles and significantly high strength and easy releasability. In other words, those that passed all of the above four items were judged to be urethane-forming compositions that can solve the problems of this specification and were judged to pass. (Example of manufacturing and evaluation of urethane adhesive sheets) A representative urethane-forming composition of the present invention was applied to an optically transparent PET film (Toyobo's Cosmoshine A4360, 38μm) at a dry thickness of 50μm using a Baker applicator and an A3-type coater at a speed of 3m / min or less, under the same conditions as for preparing the polyurethane coating, to prepare a urethane pressure-sensitive adhesive sheet having a polyurethane coating film on an optically transparent PET substrate.The adhesive was evaluated for its applicability, and its properties were evaluated according to the following criteria. 1. Adhesive formability <Coatability> ◎ (Pass): Good coatability.

[0174] ○ (Pass): Slightly high viscosity, but can be applied well by reducing the coating speed.

[0175] △ (Fail): Slightly low viscosity with slight liquid flow.

[0176] × (fail): Coating defects occurred (clear coating unevenness, curing unevenness, etc.). <Curability> The evaluation was carried out according to the same criteria as for the urethane-forming composition. 2.Properties <haze> ◎(Pass): 1.5% or less ○(Pass): More than 1.5%~3.0% △(Fail): More than 3.0%~7.0% ×(Fail): More than 7.0% <Seat appearance> ◎ (Pass): Visually uniform and good coating appearance across the entire surface.

[0177] ○ (Pass): Slight deterioration only at the beginning and / or end of coating.

[0178] × (Fail) Overall drag marks and / or large amount of bubbles and wrinkles. 2. Adhesive properties <Lamination productivity> ◎ (Pass): The area that comes into contact with the alkali-free glass quickly gets wet regardless of whether it passes through the roll, and does not shift even when pressure is applied with a finger.

[0179] ○ (Pass): Demonstrates wettability that allows lamination to alkali-free glass by roll compression (the area passing through the roll quickly becomes wet), and does not shift position even when pressure is applied with a finger.

[0180] × (fail): Insufficient wettability when roll-pressed onto alkali-free glass (many air bubbles trapped, floating, misalignment when pressure is applied with fingers, etc.). <Removability at 2,500 mm / min (removal productivity)> ◎ (Pass): Peelability of 0.05N / 25mm or less ○ (Pass): Peelability of 0.05 to 0.20 N / 25 mm × (Fail): Peelability of more than 0.20 N / 25 mm (determined to be poor productivity) Products that passed the test for productivity and peelability during lamination were judged to be adhesives with excellent productivity during lamination, as they wet quickly and are less likely to shift position during actual use, and also have good reworkability (removability), as they are easy to remove after use, thereby shortening usage time and significantly improving productivity.

[0181] Furthermore, compositions that met the criteria for coatability, curing, transparency, and sheet appearance were judged to be good urethane-forming compositions that can be produced at high speed because the coating speed and curing time of the urethane adhesive can be shortened, and that have good defect visibility and yield, allowing for high-quality urethane adhesives to be obtained with high productivity. <Example> (Synthesis Example 1, Example 1) According to the composition ratios described in the urethane-forming composition, polyurethane production examples, and synthesis example 1 in Table 2, a polyol composition was produced by adding 60 parts by weight of dehydrated polyalkylene oxide (A1), 40 parts by weight of polyol (B1), 0.02 parts by weight of iron trisacetylacetonate as a urethane-forming catalyst, and methyl ethyl ketone as a solvent to a solids concentration of 85%.

[0182] To the obtained polyol composition, 0.1 parts by weight of additive (D1) and 4 parts by weight of additive (D2) were added and mixed, and polyisocyanates (F2-1) and (F2-2) were added thereto in an amount of 0.1 parts by weight of additive (D1) and 4 parts by weight of additive (D2). OH ) and the amount of isocyanate groups derived from (F2-1) and (F2-2) (M NCO ) are expressed as mole ratios M NCO / M OH =0.65(total M NCO / M OH =1.30 equivalents) to obtain a urethane-forming composition (G1).

[0183] The results are shown in Table 4. The urethane-forming composition (G1) contained a mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, and also contained two different types of polyols, a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, it had excellent curability and compatibility, and the resulting polyurethane (H1) had the characteristic properties of being remarkably excellent in both wettability and low tack. (Synthesis Example 2, Example 2) In comparison with Example 1, the total amount of hydroxyl groups in the polyalkylene oxide (A1) and the polyol (B1) (M OH ) and the amount of isocyanate groups derived from (F2-1) and (F2-2) (M NCO ) are expressed as mole ratios M NCO / M OH =0.85(Total M NCO / M OH = 1.70 equivalents) to obtain a urethane-forming composition (G2).

[0184] The results are shown in Table 4. The urethane-forming composition (G2) contained a mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, and also contained two different types of polyols, a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, it had excellent curability and compatibility, and the resulting polyurethane (H2) had the distinctive properties of being remarkably excellent in both wettability and low tack. (Synthesis Examples 3 and 4, Examples 3 and 4) These are urethane-forming compositions (G3) and (G4) in which the ratio of polyisocyanates (F2-1) and (F2-2) was changed from Example 1, and the average number of functional groups in the entire polyisocyanate (F) was changed from 2.60 to 2.90 and 2.30. The results are shown in Table 4. The urethane-forming composition (G3) with a higher average functionality had slightly lower wettability than Example 1 but was still good, while the urethane-forming composition (G4) with a lower average functionality had slightly lower curability and low tackiness but was still good. Both compositions contained a mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, and both contained two different polyols: a high-molecular-weight polyol and a relatively low-molecular-weight polyol. As a result, they had excellent curability and compatibility, and the resulting polyurethanes (H3) and (H4) possessed the characteristic properties of both excellent wettability and low tackiness. (Synthesis Example 5, Example 5) This is a urethane-forming composition (G5) obtained by using a polyisocyanate (F2-4) having both allophanate residues and isocyanurate residues in Example 1, but omitting the additives (D1) and (D2).

[0185] The results are shown in Table 4. The urethane-forming composition (G5) contains a polyisocyanate (F2-4) having an allophanate residue and an average functionality of more than 2.01, and also contains two different types of polyols, a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, it has excellent curability and compatibility, and the resulting polyurethane (H5) has the characteristic properties of being remarkably excellent in both wettability and low tack. (Synthesis Examples 6 to 9, Examples 6 to 9) In comparison with Example 1, the urethane-forming compositions (G6) to (G9) were obtained by using polyalkylene oxide (A2) in which ethylene oxide was added to increase the reactivity as the polyalkylene oxide (A), lowering the solid content concentration to improve compatibility, and changing the type and composition ratio of the polyol used in combination.

[0186] The results are shown in Table 5. The urethane-forming composition contained a mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, and also contained two different types of polyols, a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, both had excellent curability and compatibility, and the resulting polyurethanes (H6) to (H9) all possessed the characteristic properties of excellent wettability and low tack. (Synthesis Examples 10 to 13, Examples 10 to 13) In contrast to Examples 6 to 9, in which the polyol composition was used without prepolymerization, these urethane-forming compositions (G10) to (G13) were obtained by using a urethane prepolymer (E) that had been prepolymerized and chain-extended, and by changing the structure and composition of the polyol (B) to be introduced.

[0187] The results are shown in Table 5. The urethane-forming compositions used chain-extended prepolymers, so that their compatibility was slightly lower than that of Examples 6 to 9, but was still good. All of the compositions had allophanate residues, and the average number of functional groups in the entire polyisocyanate (F) exceeded 2.01. In addition, they contained prepolymers incorporating two different types of polyols, a high-molecular-weight polyol and a relatively low-molecular-weight polyol. Therefore, all of the compositions exhibited excellent curability and compatibility, and the resulting polyurethanes (H10) to (H13) all possessed the characteristic properties of excellent wettability and low tack.

[0188] [Table 2]

[0189] [Table 3]

[0190] [Table 4]

[0191] [Table 5]

[0192] (Synthesis Example 14, Comparative Example 1) In contrast to Example 1, this is a urethane-forming composition (GC1) obtained without using polyol (B) in addition to polyalkylene oxide (A).

[0193] The results are shown in Table 8. The urethane-forming composition (GC1) contains a polyisocyanate (F) having an allophanate residue and an average functionality of more than 2.01, but does not contain a polyol used in combination to exhibit curability, etc., and does not use two different types of polyols in combination. Therefore, the composition has insufficient curability and cannot be expected to have strength or easy releasability. The resulting polyurethane (HC1) also had poor low tack and was difficult to use. (Synthesis Example 15, Comparative Example 2) In contrast to Comparative Example 1, this is a urethane-forming composition (GC2) obtained by using a polyol (B) that has a relatively low molecular weight and is easily curable, but without using a polyalkylene oxide (A) that has a relatively high molecular weight.

[0194] The results are shown in Table 8. The urethane-forming composition (GC2) contains a polyisocyanate (F) having an allophanate residue and an average functionality of more than 2.01, but does not contain a polyol used in combination to improve compatibility or wettability, and does not use two different types of polyols in combination. Therefore, the compatibility is insufficient and strength and transparency cannot be expected to be good for the composition. The resulting polyurethane (HC1) also had a slight tackiness, which is thought to be the result of not being uniformly crosslinked, and was hard, brittle, and had poor wettability, making it difficult to use. (Synthesis Examples 16 and 17, Comparative Examples 3 and 4) In Example 1, instead of the mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, a urethane-forming composition (GC3) containing polyisocyanates (F2-1) and (F2-2) alone, with an overall polyisocyanate functionality of less than 2.01, and a urethane-forming composition (GC4) containing no allophanate residues in the polyisocyanate were used.

[0195] The results are shown in Table 8. The urethane-forming compositions (GC3) and (GC4) did not contain a polyisocyanate (F) having an allophanate residue and an average functionality exceeding 2.01, and therefore it was difficult to achieve both curability and compatibility, as well as wettability and low tackiness, making them difficult to use. (Synthesis Examples 18 to 21, Comparative Examples 5 to 8) The composition was changed from Examples 6 to 9, and instead of the mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality exceeding 2.01, urethane-forming compositions (GC5) to (GC8) were used which did not contain allophanate residues and had an average isocyanate functionality exceeding 3.19, although this functionality was lower than that of a typical isocyanurate crosslinker (e.g., Coronate HX).

[0196] The results are shown in Table 8. The urethane-forming composition (GC) had an average isocyanate functionality of more than 3.19, and therefore the resulting polyurethanes (HC) were all poor in wettability and difficult to use. Furthermore, the compositions did not contain an allophanate structure, which has high mobility and is easily compatible, and therefore had low compatibility. (Synthesis Examples 22 to 24, Comparative Examples 9 to 11) The same urethane prepolymer (E1) as in Example 10 was used, and the urethane-forming compositions (GC9) to (GC11) were designed to have allophanate residues and the average functionality of the entire polyisocyanate exceeding 2.01, but these compositions either did not contain allophanate residues or had an average functionality of less than 2.01 for the entire polyisocyanate.

[0197] The results are shown in Table 9. The urethane-forming compositions (GC9) and (GC11) using polyisocyanates with only isocyanurate- or urethane-modified structures used a difunctional polyisocyanate for chain extension, so the average functionality of the entire polyisocyanate was 3.19 or less. However, because they contained no allophanate residues, the resulting polyurethanes (HC) were poor in wettability and compatibility, making them difficult to use. On the other hand, the urethane-forming composition (GC10) used a difunctional allophanate-modified compound in this system, so the average functionality of the entire polyisocyanate was less than 2.01. Although the wettability and compatibility were remarkably good, the mobility was too high, making it difficult to achieve low tack, and the initial cure was slow, making it difficult to use. (Synthesis Examples 25 to 27, Comparative Examples 12 to 14) These are urethane-forming compositions (GC12) to (GC14), which use the same prepolymers (E2) to (E4) as in Examples 11 to 13, but change the design of the polyisocyanate from one having an allophanate residue to one not having an allophanate residue.

[0198] The results are shown in Table 9. Although the average number of functional groups in the entire polyisocyanate was within the range of 2.01 to 3.19, the resulting polyurethanes (HC) did not contain allophanate residues and therefore had poor wettability and compatibility, making them difficult to use. (Synthesis Example 28, Comparative Example 15) As in Comparative Examples 12 to 14, this polyisocyanate was designed to form a urethane prepolymer and have allophanate residues, so that the average number of functional groups in the entire polyisocyanate was 2.01 to 3.19. However, as in Comparative Example 1, it did not contain a polyol used in combination to express curability, and two different types of polyols were not used in combination, so the initial curing was insufficient, the prepolymer chain length of the composition was long (NCO / OH=0.85), and the resulting cured urethane product had high adhesion and was reworkable, but it also had significantly strong tack, so it was not possible to expect good removability, productivity for removability, or strength of the cured urethane product, and easy removability, making it difficult to use in applications where the above properties were required.

[0199] Therefore, in this system, to achieve both curability and compatibility, as well as wettability and low tack, it was necessary to use two different types of polyols in combination and a polyisocyanate with allophanate residues and an average functionality of more than 2.01.

[0200] [Table 6]

[0201] [Table 7]

[0202] [Table 8]

[0203] [Table 9]

[0204] (Synthesis Example 29, Example 14) In contrast to Example 1, which used a polyol composition containing a large amount of polyalkylene oxide (A1) to which no ethylene oxide was added and polyol (B1) having an aromatic amine residue, a urethane-forming composition (G14) was obtained using a urethane prepolymer (E6) whose structure was controlled by two-stage polymerization via an NCO-terminated intermediate prepolymer in order to achieve good handleability and high solid content.

[0205] The results are shown in Table 12. The urethane-forming composition (G14) contains a mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, and also contains two different types of polyols: a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, even though the prepolymer was formed at a high solids content, it had remarkably excellent compatibility and good curing properties, and the resulting polyurethane (H14) had the characteristic properties of remarkably excellent wettability and low tack. (Synthesis Examples 30 and 31, Examples 15 and 16) These are urethane-forming compositions (G15) and (G16) in which the number of functional groups, type and amount ratio of polyisocyanate (F) having an allophanate residue and an average functionality in the range of 2.01 to 3.19 were changed compared to Example 14, and the additive formulation was adjusted.

[0206] The results are shown in Table 12. The urethane-forming composition (G15) had a high overall polyisocyanate (F) functionality, formed a prepolymer, and did not contain the low-viscosity additive (D2), so it had a higher solids concentration, and therefore showed good compatibility, although compatibility was slightly reduced. Both (G15) and (G16) contained polyisocyanate (F) having allophanate residues and an average functionality of more than 2.01, and also contained two different types of polyols: a high-molecular-weight polyol and a relatively low-molecular-weight polyol. Therefore, even though a prepolymer was formed at a high solids content, they had excellent compatibility and good curing properties, and the resulting polyurethanes (H15) and (H16) had the characteristic properties of being remarkably excellent in both wettability and low tack. (Synthesis Example 32, Example 17) In comparison with Examples 14 to 16, polyol (B1) was changed to polyol (B2), which has a higher viscosity and a higher aromatic amine content and is therefore likely to have low compatibility, and the amount used was increased from 40 parts by weight to 55 parts by weight, but instead a small amount of glycol ether solvent was used as the solvent, resulting in a urethane-forming composition (G17).

[0207] The results are shown in Table 12. The urethane-forming composition (G17) contains a mixture of polyisocyanates (F2-1) and (F2-2) having allophanate residues and an average functionality of more than 2.01, and also contains two different types of polyols: a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, even when using a prepolymer with a high solids content that tends to have low compatibility, it has remarkably excellent compatibility and good curing properties, and the resulting polyurethane (H17) has the characteristic properties of remarkably excellent wettability and low tack. (Synthesis Examples 33 to 35, Examples 18 to 20) These urethane-forming compositions (G18) to (G20) were obtained by using urethane prepolymers (E8) to (E10) with different structures, which were obtained by changing the combination of two types of polyols used and the compositions of the multi-stage design compared to Example 17, and by changing the number of functional groups in the polyisocyanate (F).

[0208] The results are shown in Table 12. The urethane-forming compositions (G18) to (G20) were composed of polyisocyanate (F2) having allophanate residues and an overall average number of functional groups in the range of 2.01 to 3.19, and contained two different types of polyols: a high molecular weight polyol and a relatively low molecular weight polyol. Therefore, even though the prepolymer was formed at a high solids content, they had remarkably excellent compatibility and good curing properties, and the resulting polyurethane (H17) had the characteristic properties of both excellent wettability and low tack. (Synthesis Examples 36 to 41, Comparative Examples 16 to 21) These urethane-forming compositions (GC16) to (GC21) were obtained by changing the design of polyisocyanate (F) in Examples 16 to 20 from one having an allophanate residue and an average functionality in the range of 2.01 to 3.19 to one having no allophanate residue or having an average functionality outside the range of 2.01 to 3.19.

[0209] The results are shown in Table 13. Regardless of the prepolymer structure, all of the polyisocyanates that did not contain allophanate residues had poor compatibility and wettability, making them difficult to use. Furthermore, all of the polyisocyanates with an average functionality outside the range of 2.01 to 3.19 had difficulty achieving both curability and compatibility, as well as wettability and low tack, regardless of the prepolymer structure.

[0210] The viscosity of the compositions containing the urethane-forming composition (G) in all Examples was in the range of 1 to 100 Pa·s, and the remaining liquid of the composition after sheet production showed good fluidity even after 12 hours had passed, and the usable time was also 12 hours or more.

[0211] As shown above in the Examples and Comparative Examples, regardless of whether a prepolymer structure is formed or not, achieving both curability and compatibility, as well as wettability and low tack, required the combined use of two different types of polyols and the use of a polyisocyanate having allophanate residues and an average functionality of more than 2.01.

[0212] Furthermore, the urethane-forming composition (G) of the present invention is a urethane-forming composition that has excellent compatibility and curability and is highly productive. By using this urethane-forming composition (G), it was possible to stably form a high-strength, easy-to-release urethane coating film that was highly transparent overall, had significantly high wettability to the substrate, and had high strength and little surface tack.

[0213] By utilizing this characteristic, it has been shown that polyurethanes obtained using the urethane-forming composition (G) can be suitably used for sealing materials, paints, pressure-sensitive adhesives, adhesives, elastomer materials, etc.

[0214] [Table 10]

[0215] [Table 11]

[0216] [Table 12]

[0217] [Table 13]

[0218] <Example of urethane adhesive manufacturing> Using a representative urethane-forming composition (G) of the present invention and a urethane-forming composition (GC) outside the scope of the present invention, the properties as a urethane adhesive were simply evaluated. Specifically, 100 parts by weight of the solids content of the urethane-forming composition (G) or (GC) of Synthesis Examples 8, 31, 34, 36, 37, or 40 was mixed and dispersed with 600 ppm of an acidic phosphate ester (JP508 manufactured by Johoku Chemical Industry Co., Ltd.) as a reaction retarder, 0.8 parts by weight of the triazole stabilizer Tinuvin 99-2, 0.2 parts by weight of diethylene glycol, 10 parts by weight of hexadecyl 2-ethylhexanoate as a plasticizer, 1.5 parts by weight of 1-ethyl-3-methylimidazolium bis(fluoromethanesulfonyl)imide as an antistatic agent, and 0.05 parts by weight of F-571 manufactured by DIC as a leveling agent, to produce a urethane adhesive according to the Production and Evaluation Examples for Urethane Adhesive Sheets, and its performance was simply evaluated. Example 21 A urethane adhesive was produced according to the Urethane Adhesive Sheet Production Example using the polyol composition obtained in Synthesis Example 8 that did not form a prepolymer, and a urethane-forming composition (G8) containing a mixture of polyisocyanates (F2-1) and (F2-2) that had allophanate residues and whose average functionality in the entire polyisocyanate was in the range of 2.01 to 3.19, and its performance was simply evaluated.

[0219] The urethane-forming composition (G8) had remarkably excellent coating and curing properties, and the resulting urethane sheet, consisting of two layers of a transparent PET substrate and a cured urethane material, was highly transparent and had excellent sheet appearance, and was judged to be usable as a urethane adhesive because it had excellent productivity and peelability when bonding. Example 22 A urethane adhesive was produced according to the Urethane Adhesive Sheet Production Example using the urethane prepolymer (E6) obtained in Synthesis Example 31 and a urethane-forming composition (G16) containing a polyisocyanate (F2-4) having an allophanate residue and an average functionality of more than 2.01, and its performance was simply evaluated.

[0220] Although the urethane-forming composition (G16) forms a prepolymer without solvent, it has outstanding coatability and curing properties. The resulting urethane sheet, consisting of two layers of a transparent PET substrate and a cured urethane product, is highly transparent and has outstanding sheet appearance. It also has excellent productivity during lamination and peelability, so it was determined that it can be used as a urethane adhesive. Example 23 A urethane adhesive was produced according to the Urethane Adhesive Sheet Production Example using the urethane-forming composition (G19) obtained in Synthesis Example 34, which contained a urethane prepolymer (E9) that was prepared using a small amount of solvent and a small amount of polyol (B) and had a longer chain length, and a polyisocyanate (F2-4) that had allophanate residues and an average functionality of more than 2.01, and the performance was then simply evaluated.

[0221] Although the urethane-forming composition (G19) uses a prepolymer with a longer chain length, it has remarkably excellent coatability and curing properties. The resulting urethane sheet, consisting of two layers of a transparent PET substrate and a cured urethane product, is highly transparent and has a remarkably excellent sheet appearance. It also has excellent productivity during lamination and peelability, and it was therefore determined that it could be used as a urethane adhesive. (Comparative Example 16) In contrast to Example 22, a urethane adhesive was prepared according to the urethane adhesive sheet manufacturing example in the same manner as in the example, using the urethane-forming composition (GC16) of Synthesis Example 36, in which the polyisocyanate (F) used was designed to have no allophanate residues, and its performance was simply evaluated.

[0222] The urethane-forming composition (GC16) does not contain any allophanate residues and has only isocyanurate as the modified structure. Therefore, the number of functional groups as an isocyanurate modified product is low, and the average number of functional groups of the entire polyisocyanate is below 3.19. However, compatibility is low, and the obtained urethane sheet consisting of two layers of a transparent PET substrate and a cured urethane product showed white drag marks, indicating that the urethane adhesive had insufficient productivity when bonding. (Comparative Example 17) In contrast to Example 22, a urethane adhesive was prepared according to the urethane adhesive sheet manufacturing example in the same manner as in the example, using the urethane-forming composition (GC17) of Synthesis Example 37, in which the average functionality of the polyisocyanate (F) used was designed to be outside the range of 2.01 to 3.19, and its performance was simply evaluated.

[0223] Although the urethane-forming composition (GC17) contains allophanate residues, it is designed so that the average number of functional groups in the entire polyisocyanate (F) is less than 2.01. The crosslinking agent component polyisocyanate (F2-1) has a low viscosity, and the urethane-forming composition containing it tends to flow slightly during coating, drying, and curing, resulting in slightly inferior coatability and insufficient curing. The resulting urethane adhesive was highly tacky, resulting in poor productivity when peeling it off. (Comparative Example 18) In contrast to Example 23, a urethane adhesive was prepared according to the urethane adhesive sheet manufacturing example in the same manner as in the example, using the urethane-forming composition (GC20) of Synthesis Example 40, in which the polyisocyanate (F) used was designed to have no allophanate residues, and its performance was simply evaluated.

[0224] The urethane-forming composition (GC20) does not contain any allophanate residues and has only isocyanurate as the modified structure. Therefore, the number of functional groups as an isocyanurate modified product is low, and the average number of functional groups of the entire polyisocyanate is below 3.19. However, compatibility is low, and the obtained urethane sheet consisting of two layers of a transparent PET substrate and a cured urethane product showed white drag marks, making it a urethane pressure-sensitive adhesive with insufficient productivity when bonding.

[0225] The viscosities of the compositions containing the urethane-forming composition (G) in all of the Examples described in the Urethane Pressure-Sensitive Adhesive Manufacturing Examples were in the range of 1 to 100 Pa·s, and the residual liquid of the composition after sheet production showed good fluidity even after 12 hours had passed, with a usable life of 12 hours or more. The urethane pressure-sensitive adhesives obtained in the Examples had remarkably good wettability under their own weight, high transparency / good appearance, and excellent productivity during lamination / peel-off, making them suitable for use as pressure-sensitive adhesives, etc.

[0226] [Table 14] < / haze>

Claims

1. The composition comprises an active hydrogen group-terminated urethane prepolymer (E) and a polyisocyanate (F2), the urethane prepolymer (E) is a reaction product of at least a polyalkylene oxide (A), a polyol containing a polyol (B) different from the polyalkylene oxide (A), and a polyisocyanate (F1); A urethane-forming composition (G) in which either the polyisocyanate (F1) or the polyisocyanate (F2) contains an allophanate structure, and the average number of isocyanate functional groups of the polyisocyanate (F1) and the polyisocyanate (F2) calculated by gel permeation chromatography (GPC) is in the range of 2.01 to 3.

19.

2. The urethane-forming composition (G) according to claim 1, wherein either the polyisocyanate (F1) or the polyisocyanate (F2) contains a nurate structure.

3. The urethane-forming composition (G) according to claim 2, wherein the polyisocyanate (F) obtained by combining the polyisocyanate (F1) and the polyisocyanate (F2) has a molar ratio of allophanate structures to nurate structures in the range of 10 / 90 to 90 / 10.

4. The urethane-forming composition (G) according to any one of claims 1 to 3, wherein the viscosity of the polyisocyanate (F2) is in the range of 150 to 1900 mPa·s.

5. The urethane-forming composition (G) according to any one of claims 1 to 4, wherein the weight ratio of the urethane prepolymer (E) to the polyisocyanate (F2) is in the range of 80 / 20 to 1 / 99.

6. 6. The urethane-forming composition (G) according to claim 1, wherein the polyalkylene oxide (A) has a molecular weight of 2,500 or more, and the polyol (B) has a molecular weight of less than 2,500.

7. 7. The urethane-forming composition (G) according to any one of claims 1 to 6, wherein the polyol (B) has one or more residues selected from the group consisting of polyoxytetramethylene residues, sugar residues having 6 or more carbon atoms, aromatic amine residues, polyester residues, acrylic residues, and polyolefin residues.

8. The urethane-forming composition (G) according to any one of claims 1 to 7, wherein the polyol (B) has a sugar residue or an aromatic amine residue having 6 or more carbon atoms.

9. 9. The urethane-forming composition (G) according to claim 1, wherein the polyalkylene oxide (A) has a degree of unsaturation of 0.01 meq / g or less.

10. The urethane-forming composition (G) according to any one of claims 1 to 9, wherein the urethane-forming composition (G) contains a keto-enol tautomer compound and a hindered phenol-based antioxidant.

11. A polyurethane (H) which is a cured product of the urethane-forming composition (G) according to any one of claims 1 to 10.

12. A polyurethane sheet comprising the polyurethane (H) according to claim 11 and a substrate.

13. A urethane pressure-sensitive adhesive sheet comprising the polyurethane (H) according to claim 11, having a thickness of 1 to 200 μm, and having a peel strength of 0.20 N / 25 mm or less when attached to alkali-free glass and peeled at 2,500 mm / min.

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