JP7761509B2 - Polyisocyanate composition and coating agent - Google Patents

Description

The present invention relates to a polyisocyanate composition and a coating agent.

Polyurethane resins are typically produced by reacting polyisocyanates with active hydrogen group-containing compounds. They are widely used in a variety of industrial fields, including as coating materials, adhesive materials, pressure-sensitive adhesive materials, and elastomers. For example, polyurethane resins are applied to any substrate to form a coating film. This allows the polyurethane resin to impart various physical properties to the substrate.

As a polyisocyanate, for example, a polyisocyanate composition obtained by the following method has been proposed. That is, first, hexamethylene diisocyanate is reacted with a monohydric alcohol, followed by an isocyanuration reaction. Next, the reaction product obtained by the isocyanuration reaction is reacted with a polyester polyol (see, for example, Patent Document 1 (Synthesis Example 2, Example 5))).

Japanese Patent Application Laid-Open No. 2020-139017

On the other hand, polyurethane resins are required to have both breaking strength, breaking elongation, and solvent resistance, depending on the application. However, when the above-mentioned polyisocyanate composition is used, the breaking strength and solvent resistance of the polyurethane resin may not be sufficient.

The present invention relates to a polyisocyanate composition and coating agent that can produce a polyurethane resin that combines breaking strength, breaking elongation, and solvent resistance.

The present invention [1] relates to a polyisocyanate composition comprising an isocyanate-terminated prepolymer, wherein the isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component and a polyol component, the polyisocyanate component comprises an isocyanurate derivative of pentamethylene diisocyanate, and the isocyanurate derivative of pentamethylene diisocyanate comprises an isocyanurate-modified product of pentamethylene diisocyanate partially modified with an alcohol component, the first equivalent ratio (NCO/OH) of the isocyanate groups of the polyisocyanate component to the hydroxyl groups of the polyol component is 3.0 or more and 8.0 or less, and the second equivalent ratio (NCO/OH) of the isocyanate groups of the pentamethylene diisocyanate to the hydroxyl groups of the alcohol component is 60 or more and 600 or less.

The present invention [2] includes the polyisocyanate composition according to [1] above, wherein the isocyanurate derivative of pentamethylene diisocyanate includes a mono-isocyanurate unit of pentamethylene diisocyanate, the mono-isocyanurate unit of pentamethylene diisocyanate containing one isocyanurate group and a derivative compound containing three molecules of pentamethylene diisocyanate, and in a chromatogram obtained by measuring the isocyanurate derivative of pentamethylene diisocyanate by gel permeation chromatography, the area ratio of the peak area corresponding to the mono-isocyanurate unit of pentamethylene diisocyanate to the area of all peaks is 40% or more.

The present invention [3] includes the polyisocyanate composition described in [1] or [2] above, in which the number average molecular weight of the polyol component is 200 or more and 1,000 or less.

The present invention [4] includes the polyisocyanate composition according to any one of [1] to [3] above, in which the average number of hydroxyl groups in the polyol component is 2.

The present invention [5] includes a coating agent comprising a base agent and a curing agent, wherein the base agent comprises a macropolyol, and the curing agent comprises the polyisocyanate composition described in any one of [1] to [4] above.

In the polyisocyanate composition of the present invention, the polyisocyanate component used to obtain the isocyanate-terminated prepolymer contains an isocyanurate derivative of pentamethylene diisocyanate. The isocyanurate derivative of pentamethylene diisocyanate contains an isocyanurate-modified product of pentamethylene diisocyanate that has been partially modified with an alcohol component. Furthermore, in the isocyanurate derivative of pentamethylene diisocyanate, the ratio (equivalent ratio) of pentamethylene diisocyanate to the alcohol component is within a specified range. The isocyanate-terminated prepolymer contains a reaction product obtained by reacting the above-mentioned polyisocyanate component with a polyol component at a specified ratio (equivalent ratio).

As a result, the above polyisocyanate composition produces a polyurethane resin with excellent breaking strength, breaking elongation, and solvent resistance.

The coating agent of the present invention also contains the polyisocyanate composition described above. Therefore, such a coating agent can produce a polyurethane resin with excellent breaking strength, breaking elongation, and solvent resistance.

FIG. 1 is a chromatogram obtained by measuring the isocyanurate derivative of pentamethylene diisocyanate in Synthesis Example 1 by gel permeation chromatography.

The polyisocyanate composition of the present invention contains an isocyanate-terminated prepolymer. The polyisocyanate composition preferably consists of an isocyanate-terminated prepolymer.

The isocyanate-terminated prepolymer comprises a reaction product of a polyisocyanate component and a polyol component. Preferably, the isocyanate-terminated prepolymer consists of a reaction product of a polyisocyanate component and a polyol component.

The polyisocyanate component contains an isocyanurate derivative of pentamethylene diisocyanate (PDI).

Isocyanurate derivatives of pentamethylene diisocyanate include isocyanurate-modified pentamethylene diisocyanate that has been partially modified with an alcohol component.

Pentamethylene diisocyanates include 1,2-pentamethylene diisocyanate (1,2-pentane diisocyanate), 1,3-pentamethylene diisocyanate (1,3-pentane diisocyanate), 1,4-pentamethylene diisocyanate (1,4-pentane diisocyanate), and 1,5-pentamethylene diisocyanate (1,5-pentane diisocyanate). These can be used alone or in combination of two or more types. A preferred pentamethylene diisocyanate is 1,5-pentamethylene diisocyanate (1,5-pentane diisocyanate).

Examples of alcohol components include low-molecular-weight alcohols. Low-molecular-weight alcohols are organic compounds with one or more hydroxyl groups per molecule and a relatively low molecular weight. Note that a relatively low molecular weight refers to a molecular weight of less than 200 (the same applies below).

Examples of low molecular weight alcohols include aliphatic low molecular weight alcohols and aromatic low molecular weight alcohols, with aliphatic low molecular weight alcohols being preferred. Examples of aliphatic low molecular weight alcohols include aliphatic low molecular weight alcohols having 1 to 12 carbon atoms. Examples of aliphatic low molecular weight alcohols include aliphatic low molecular weight monools (monohydric alcohols) and aliphatic low molecular weight polyols (dihydric or higher alcohols).

Aliphatic low-molecular-weight monools are aliphatic organic compounds with a relatively low molecular weight and one hydroxyl group per molecule. Examples of aliphatic low-molecular-weight monools include aliphatic low-molecular-weight monohydric alcohols having 1 to 12 carbon atoms. Examples of aliphatic low-molecular-weight monohydric alcohols having 1 to 12 carbon atoms include alkyl alcohols having 1 to 12 carbon atoms. Examples of alkyl alcohols having 1 to 12 carbon atoms include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, s-butanol, t-butanol, 2-ethylhexyl alcohol, and lauryl alcohol. These can be used alone or in combination of two or more types.

Aliphatic low-molecular-weight polyols are aliphatic organic compounds with relatively low molecular weights that have two or more hydroxyl groups per molecule. Examples of aliphatic low-molecular-weight polyols include aliphatic low-molecular-weight polyols having 1 to 12 carbon atoms. Other examples of aliphatic low-molecular-weight polyols include aliphatic low-molecular-weight dihydric alcohols, aliphatic low-molecular-weight trihydric alcohols, and aliphatic low-molecular-weight tetrahydric or higher alcohols.

More specifically, examples of aliphatic low-molecular-weight polyols include aliphatic low-molecular-weight dihydric alcohols having 1 to 12 carbon atoms, aliphatic low-molecular-weight trihydric alcohols having 1 to 12 carbon atoms, and aliphatic low-molecular-weight tetrahydric or higher alcohols having 1 to 12 carbon atoms. Examples of aliphatic low-molecular-weight dihydric alcohols having 1 to 12 carbon atoms include alkylene diols having 1 to 12 carbon atoms. Examples of alkylene diols having 1 to 12 carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol. Examples of aliphatic low-molecular-weight trihydric alcohols having 1 to 12 carbon atoms include glycerin and trimethylolpropane. Examples of aliphatic low-molecular-weight tetrahydric or higher alcohols having 1 to 12 carbon atoms include pentaerythritol and diglycerin. These can be used alone or in combination of two or more types.

Low molecular weight alcohols can be used alone or in combination of two or more types. The molecular weight of the low molecular weight alcohol (or, if used in combination, the average molecular weight (hereinafter the same)) is, for example, less than 200, preferably less than 150. The molecular weight of the low molecular weight alcohol is, for example, 40 or more, preferably 50 or more.

From the viewpoint of breaking elongation, the average number of hydroxyl groups in the alcohol component is, for example, 1 or more. Furthermore, the average number of hydroxyl groups in the polyol component is, for example, 3 or less, preferably 2 or less. The average number of hydroxyl groups in the polyol component is particularly preferably 1.

More specifically, from the viewpoint of obtaining a polyurethane resin that combines breaking strength, breaking elongation, and solvent resistance, the alcohol component is preferably an aliphatic low-molecular-weight alcohol having 1 to 12 carbon atoms, more preferably an aliphatic low-molecular-weight monohydric alcohol having 1 to 12 carbon atoms, and an aliphatic low-molecular-weight dihydric alcohol having 1 to 12 carbon atoms, even more preferably an aliphatic low-molecular-weight monohydric alcohol having 1 to 8 carbon atoms, even more preferably an aliphatic low-molecular-weight monohydric alcohol having 1 to 4 carbon atoms, and particularly preferably isobutyl alcohol.

Isocyanurate derivatives of pentamethylene diisocyanate can be obtained, for example, by the following method. In this method, pentamethylene diisocyanate is first partially modified with an alcohol component (alcohol-modified). The partially modified pentamethylene diisocyanate is then subjected to an isocyanurate-forming reaction.

More specifically, in this method, pentamethylene diisocyanate and an alcohol component are first mixed in a predetermined ratio, and the pentamethylene diisocyanate is partially modified with the alcohol component.

In the isocyanurate derivative of pentamethylene diisocyanate, the blending ratio of pentamethylene diisocyanate to the alcohol component is adjusted so that the equivalent ratio (second equivalent ratio, NCO/OH) of the isocyanate groups of pentamethylene diisocyanate to the hydroxyl groups of the alcohol component falls within a specified range.

More specifically, the second equivalent ratio (NCO/OH) of the isocyanate groups of pentamethylene diisocyanate to the hydroxyl groups of the alcohol component is 60 or greater, preferably 65 or greater. Furthermore, the second equivalent ratio (NCO/OH) of the isocyanate groups of pentamethylene diisocyanate to the hydroxyl groups of the alcohol component is 600 or less, preferably 500 or less, more preferably 400 or less, even more preferably 300 or less, even more preferably 200 or less, and particularly preferably 100 or less.

The modification conditions (reaction conditions) for alcohol modification are not particularly limited and may be set appropriately. Examples of reaction methods include bulk polymerization and solution polymerization. The environmental conditions are an inert gas atmosphere and normal (atmospheric) pressure. The reaction temperature is, for example, 20°C or higher, preferably 50°C or higher, and more preferably 70°C or higher. The reaction temperature is, for example, 100°C or lower, preferably 90°C or lower, and more preferably 80°C or lower. The reaction time is, for example, 30 minutes or longer, preferably 1 hour or longer. The reaction time is, for example, 12 hours or shorter, preferably 6 hours or shorter.

Furthermore, in alcohol modification, known organic solvents can be added in appropriate proportions as needed. Also, in alcohol modification, known urethane catalysts can be added in appropriate proportions as needed. Furthermore, in alcohol modification, known additives can be added in appropriate proportions as needed. Examples of additives include antioxidants, heat stabilizers, light stabilizers, and co-catalysts. These can be used alone or in combination of two or more types.

This produces an alcohol-modified reaction product liquid (hereinafter referred to as alcohol-modified liquid). The alcohol-modified liquid is a partially modified product of pentamethylene diisocyanate with the alcohol component.

More specifically, in the alcohol-modified process, some of the pentamethylene diisocyanate molecules are alcohol-modified. In other words, the alcohol-modified liquid contains alcohol-modified pentamethylene diisocyanate (alcohol-modified PDI).

Furthermore, in the above-mentioned alcohol-modification, the remaining pentamethylene diisocyanate molecules (the remainder relative to the portion that is alcohol-modified) remain unalcohol-modified. In other words, the alcohol-modified liquid contains pentamethylene diisocyanate that has not been alcohol-modified (alcohol-unmodified PDI).

That is, the alcohol-modified liquid contains a PDI composition that includes alcohol-modified PDI and alcohol-unmodified PDI. In other words, the PDI composition is a partially modified product of pentamethylene diisocyanate with an alcohol component, and is contained in the alcohol-modified liquid.

Next, in this method, an isocyanuration catalyst is added to the alcohol-modified liquid, and the liquid is heated if necessary. This causes the isocyanate groups contained in the alcohol-modified liquid (the isocyanate groups of the alcohol-modified pentamethylene diisocyanate and the isocyanate groups of unmodified pentamethylene diisocyanate) to undergo an isocyanuration reaction.

Examples of isocyanuration catalysts include tetraalkylammonium hydroxides, trialkylhydroxyalkylammonium hydroxides, weak organic acid salts thereof, metal salts of alkylcarboxylic acids, metal chelate compounds of β-diketones, Friedel-Crafts catalysts, organometallic compounds, and aminosilyl group-containing compounds. Metal salts of alkylcarboxylic acids are preferred. Examples of alkylcarboxylic acids include acetic acid, caproic acid, octylic acid, myristic acid, and naphthenic acid. Examples of metal salts include sodium salts, potassium salts, calcium salts, magnesium salts, tin salts, zinc salts, and lead salts. These can be used alone or in combination of two or more.

The isocyanuration catalyst may be used as a solution and/or dispersion. The solution and/or dispersion of the isocyanuration catalyst contains the above-mentioned isocyanuration catalyst and a known organic solvent. Examples of organic solvents include alkyl esters, alcohols, ethers, ketones, and nitriles. These can be used alone or in combination of two or more. The solids concentration of the solution (isocyanuration catalyst content) is set appropriately depending on the purpose and application.

When the isocyanuration catalyst solution contains an alcohol, the alcohol acts as a solvent for the catalyst. The alcohol as a solvent is distinct from the alcohol component described above. More specifically, the amount of the alcohol as a solvent is small compared to the amount of the alcohol component. More specifically, the amount of the alcohol as a solvent is, for example, 1 part by mass or less, preferably 0.5 parts by mass or less, per 100 parts by mass of pentamethylene diisocyanate.

The addition ratio of the isocyanurate catalyst (solids content equivalent) is, for example, 0.001 parts by mass or more, preferably 0.01 parts by mass or more, per 100 parts by mass of pentamethylene diisocyanate. The addition ratio of the isocyanurate catalyst (solids content equivalent) is, for example, 3.0 parts by mass or less, preferably 1.0 part by mass or less, per 100 parts by mass of pentamethylene diisocyanate. The isocyanurate catalyst may be added all at once or in portions.

The reaction conditions for the isocyanuration reaction are not particularly limited and may be set appropriately. Examples of reaction methods include bulk polymerization and solution polymerization. The environmental conditions are an inert gas atmosphere and normal (atmospheric) pressure. The reaction temperature is, for example, 20°C or higher, preferably 50°C or higher, and more preferably 70°C or higher. The reaction temperature is, for example, 200°C or lower, preferably 150°C or lower, and more preferably 130°C or lower. The reaction time is, for example, 30 minutes or longer, preferably 1 hour or longer. The reaction time is, for example, 12 hours or shorter, preferably 6 hours or shorter.

In addition, in the isocyanurate reaction, known organic solvents can be added in appropriate proportions as needed.In addition, in the isocyanurate reaction, known additives can be added in appropriate proportions as needed.Examples of additives include antioxidants, heat stabilizers, light stabilizers, and co-catalysts.These can be used alone or in combination of two or more types.

In the above-mentioned isocyanurate formation reaction, a catalyst deactivator is preferably added at any time. This stops the isocyanurate formation reaction. Examples of catalyst deactivators include phosphoric acid, monochloroacetic acid, dodecylbenzenesulfonic acid, paratoluenesulfonic acid, orthotoluenesulfonic acid, benzoyl chloride, p-toluenesulfonamide, and o-toluenesulfonamide. These can be used alone or in combination of two or more. The blend ratio of the catalyst deactivator is not particularly limited and can be set appropriately depending on the purpose and application.

The catalyst deactivator is added, for example, when the isocyanate group to isocyanurate conversion rate (hereinafter referred to as the isocyanate group conversion rate) reaches a predetermined value. The isocyanate group conversion rate is, for example, 2% by mass or more, preferably 5% by mass or more, and more preferably 8% by mass or more. The isocyanate group conversion rate is, for example, 30% by mass or less, preferably 25% by mass or less, and more preferably 15% by mass or less. The isocyanate group conversion rate can be determined using known measurement methods. Examples of measurement methods include titration with di-n-butylamine and FT-IR analysis (the same applies below).

This results in a reaction product liquid of the isocyanurate reaction (hereinafter referred to as the isocyanurate reaction liquid).

The isocyanurate reaction liquid contains an isocyanurate derivative of pentamethylene diisocyanate.

The isocyanurate derivative of pentamethylene diisocyanate is an isocyanurate composition obtained by isocyanating the alcohol-modified liquid (a PDI composition containing alcohol-modified PDI and alcohol-unmodified PDI) described above.

In other words, an isocyanurate derivative of pentamethylene diisocyanate is an isocyanurate composition obtained by isocyanating pentamethylene diisocyanate that has been partially modified with an alcohol component.

In other words, isocyanurate derivatives of pentamethylene diisocyanate include isocyanurates of alcohol-modified pentamethylene diisocyanate and isocyanurates of pentamethylene diisocyanate that are not alcohol-modified.

The isocyanurate derivative of pentamethylene diisocyanate preferably contains a specified proportion of mono-isocyanurate units of pentamethylene diisocyanate. The mono-isocyanurate unit is a derivative compound containing one isocyanurate group and three molecules of pentamethylene diisocyanate. In other words, the mono-isocyanurate unit is an isocyanate trimolecular unit containing three molecules of pentamethylene diisocyanate.

Note that each of the three pentamethylene diisocyanate molecules may be alcohol-modified PDI or alcohol-unmodified PDI.

From the viewpoint of breaking strength and solvent resistance, the content of mono-isocyanurate units in pentamethylene diisocyanate is, for example, 20% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more, relative to the total amount of isocyanurate derivatives of pentamethylene diisocyanate. Furthermore, the content of mono-isocyanurate units in pentamethylene diisocyanate is, for example, 70% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less, relative to the total amount of isocyanurate derivatives of pentamethylene diisocyanate.

The content of mononuclear isocyanurate in pentamethylene diisocyanate is calculated based on the chromatogram obtained when the isocyanurate derivative of pentamethylene diisocyanate is measured by gel permeation chromatography (GPC measurement).

In GPC measurement, there are no particular limitations on the GPC measurement device or method, and any device and method with the resolution necessary to calculate the area ratio of each peak may be used as appropriate.

The method for calculating the area ratio of each peak is not particularly limited, but typically, each peak in the chromatogram obtained by GPC measurement is vertically divided, and the area ratio of each vertically divided peak is calculated using the area percentage method.

Then, in the chromatogram obtained by GPC measurement of the isocyanurate derivative of pentamethylene diisocyanate, the peak attributable to the isocyanurate mononuclear unit is identified, and the area ratio of that peak is taken as the isocyanurate mononuclear unit content.

More specifically, the peak derived from the mono-isocyanurate nucleus is identified, for example, based on the polystyrene-equivalent molecular weight (average molecular weight). For example, a peak having a peak top in the polystyrene-equivalent molecular weight (number average molecular weight) range of 400 or more and less than 480 is identified as a peak derived from the mono-isocyanurate nucleus of pentamethylene diisocyanate.

The area ratio of the area of the peak having a peak top in the polystyrene-equivalent molecular weight (number average molecular weight) range of 400 or more but less than 480 to the area of all peaks attributable to the isocyanurate derivative of pentamethylene diisocyanate (excluding peaks attributable to unreacted pentamethylene diisocyanate) (hereinafter sometimes referred to as the Mn400-480 area ratio or the isocyanurate mononuclear unit area ratio) is defined as the isocyanurate mononuclear unit content.

The area ratio of isocyanurate mononuclear bodies (e.g., Mn400-480 area ratio) is, for example, 20% or more, preferably 30% or more, and more preferably 40% or more. Furthermore, the area ratio of isocyanurate mononuclear bodies (e.g., Mn400-480 area ratio) is, for example, 70% or less, preferably 60% or less, and more preferably 50% or less.

The isocyanuration reaction liquid (i.e., the isocyanurate derivative of pentamethylene diisocyanate) may also contain an allophanate of pentamethylene diisocyanate.

More specifically, the above-mentioned isocyanuration catalyst may also function as an allophanation catalyst. That is, the isocyanuration reaction may produce an allophanate of pentamethylene diisocyanate along with the isocyanurate of pentamethylene diisocyanate. In such cases, the isocyanurate derivative of pentamethylene diisocyanate (including the isocyanurate of alcohol-modified pentamethylene diisocyanate and the isocyanurate of pentamethylene diisocyanate that is not modified with alcohol) contains the allophanate of pentamethylene diisocyanate.

In other words, the isocyanurate derivative of pentamethylene diisocyanate may be an isocyanurate derivative composition containing an isocyanurate and an allophanate. In the isocyanurate derivative composition, the content of allophanate groups is, for example, less than 50% by mass, preferably less than 45% by mass, and more preferably less than 40% by mass, based on the total amount of isocyanurate groups and allophanate groups (the same applies hereinafter).

In addition to the isocyanurate derivative of pentamethylene diisocyanate, the isocyanurate reaction liquid may also contain, for example, unreacted pentamethylene diisocyanate.

Unreacted pentamethylene diisocyanate is pentamethylene diisocyanate that has not been isocyanurated, and may be alcohol-modified PDI or alcohol-unmodified PDI.

If the isocyanurate reaction liquid contains unreacted pentamethylene diisocyanate, the unreacted pentamethylene diisocyanate can be separated from the isocyanurate reaction liquid by a known method, if necessary. Separation methods include, for example, distillation and extraction. Separation conditions are set appropriately depending on the purpose and application.

The isocyanurate reaction liquid may also contain an organic solvent, a urethane-forming catalyst, and/or an isocyanurate catalyst. In such cases, if necessary, the organic solvent, the urethane-forming catalyst, and/or the isocyanurate catalyst can be separated from the isocyanurate reaction liquid using a known method. Examples of separation methods include distillation and extraction. Separation conditions are set appropriately depending on the purpose and application.

Preferably, unreacted pentamethylene diisocyanate, organic solvent, urethane-forming catalyst, and/or isocyanuration catalyst are separated from the isocyanuration reaction liquid. As a result, the isocyanuration reaction liquid preferably consists of an isocyanurate derivative of pentamethylene diisocyanate.

The isocyanate group concentration of the isocyanurate reaction liquid is, for example, 5.0% by mass or more, preferably 10.0% by mass or more. The isocyanate group concentration of the isocyanurate reaction liquid is, for example, 40.0% by mass or less, preferably 35.0% by mass or less, and more preferably 30.0% by mass or less. The isocyanate group concentration can be determined by known measurement methods. Examples of measurement methods include titration with di-n-butylamine and FT-IR analysis (the same applies below).

Furthermore, as long as the polyisocyanate component contains the above-mentioned isocyanurate derivative of pentamethylene diisocyanate, it can also contain other polyisocyanates.

The other polyisocyanates are polyisocyanates other than isocyanurate derivatives of pentamethylene diisocyanate. Examples of other polyisocyanates include known polyisocyanate monomers and known polyisocyanate derivatives.

Examples of polyisocyanate monomers include polyisocyanate monomers excluding pentamethylene diisocyanate monomers, and more specifically, examples include known aliphatic polyisocyanates (excluding pentamethylene diisocyanate), known alicyclic polyisocyanates, known araliphatic polyisocyanates, and known aromatic polyisocyanates.

Polyisocyanate derivatives include polyisocyanate derivatives excluding isocyanurate derivatives of pentamethylene diisocyanate, and more specifically, derivatives of the above polyisocyanate monomers. Examples of derivatives include polymers, isocyanurate derivatives, allophanate derivatives, biuret derivatives, uretdione derivatives, polyol adducts, urea derivatives, oxadiazinetrione derivatives, and carbodiimide derivatives. Polyisocyanate derivatives can be used alone or in combination of two or more types.

The content of the other polyisocyanates is set appropriately within a range that does not impair the excellent effects of the present invention. The content of the other polyisocyanates is, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 0% by mass, based on the total amount of polyisocyanate components.

In other words, the polyisocyanate component preferably does not contain any other polyisocyanates and consists of an isocyanurate derivative of pentamethylene diisocyanate.

As an example of a polyol component, a high-molecular-weight polyol is an organic compound with two or more hydroxyl groups per molecule and a relatively high molecular weight. Note that a relatively high molecular weight refers to a number-average molecular weight of 200 or more, preferably 300 or more (the same applies below).

Examples of high molecular weight polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, fluorine polyols, and vinyl monomer-modified polyols. These can be used alone or in combination of two or more. Preferred high molecular weight polyols include polyether polyols, polyester polyols, and polycarbonate polyols, and more preferably polycarbonate polyols.

High molecular weight polyols can be used alone or in combination of two or more types. The number average molecular weight of the high molecular weight polyol is, for example, 200 or more, preferably 300 or more, and more preferably 400 or more. The number average molecular weight of the high molecular weight polyol is, for example, 5000 or less, preferably 2000 or less, more preferably 1000 or less, even more preferably 800 or less, and particularly preferably 600 or less.

The low-molecular-weight polyols listed above can also be used as the polyol component. These can be used alone or in combination of two or more types.

The polyol component can be used alone or in combination of two or more types. A preferred polyol component is a high-molecular-weight polyol. The polyol component preferably consists of a high-molecular-weight polyol.

In other words, the number average molecular weight of the polyol component is, for example, 200 or more, preferably 300 or more, and more preferably 400 or more. The number average molecular weight of the polyol component is, for example, 5,000 or less, preferably 2,000 or less, more preferably 1,000 or less, even more preferably 800 or less, and particularly preferably 600 or less.

From the viewpoint of elongation at break, the average number of hydroxyl groups in the polyol component is, for example, 2 or more. Furthermore, the average number of hydroxyl groups in the polyol component is, for example, 4 or less, preferably 3 or less. The average number of hydroxyl groups in the polyol component is particularly preferably 2.

More specifically, from the viewpoint of obtaining a polyurethane resin that combines high breaking strength, high breaking elongation, and solvent resistance, preferred polyol components include divalent polyether polyols, divalent polyester polyols, and divalent polycarbonate polyols, with divalent polycarbonate polyols being even more preferred.

In the polyisocyanate composition, the isocyanate-terminated prepolymer is obtained, for example, as a reaction product between the above-mentioned polyisocyanate component and the above-mentioned polyol component. Preferably, the isocyanate-terminated prepolymer is a reaction product of a prepolymerization reaction between the polyisocyanate component and the polyol component. The polyisocyanate component and the polyol component are prepolymerized, for example, by the following method.

More specifically, in the production of isocyanate-terminated prepolymers, a polyisocyanate component and a polyol component are blended in a predetermined ratio and subjected to a prepolymerization reaction. The blending ratios in the prepolymerization reaction are adjusted so that the equivalent ratio (first equivalent ratio, NCO/OH) of the isocyanate groups of the polyisocyanate component to the hydroxyl groups of the polyol component falls within a predetermined range.

More specifically, the first equivalent ratio (NCO/OH) of the isocyanate groups of the polyisocyanate component to the hydroxyl groups of the polyol component is 3.0 or greater, preferably 4.0 or greater, more preferably 5.0 or greater, and even more preferably 5.5 or greater. Furthermore, the first equivalent ratio (NCO/OH) of the isocyanate groups of the polyisocyanate component to the hydroxyl groups of the polyol component is 8.0 or less, preferably 7.5 or less, more preferably 7.0 or less, and even more preferably 6.5 or less.

The reaction conditions for the prepolymerization reaction are not particularly limited and can be set appropriately. Examples of reaction methods include bulk polymerization and solution polymerization. The environmental conditions are an inert gas atmosphere and normal (atmospheric) pressure. The reaction temperature is, for example, 20°C or higher, preferably 50°C or higher, and more preferably 70°C or higher. The reaction temperature is, for example, 150°C or lower, preferably 120°C or lower, and more preferably 100°C or lower. The reaction time is, for example, 30 minutes or longer, preferably 1 hour or longer. The reaction time is, for example, 12 hours or shorter, preferably 6 hours or shorter.

In the prepolymerization reaction, a known organic solvent can be added in an appropriate ratio, if necessary. In the prepolymerization reaction, a known prepolymerization catalyst can be added in an appropriate ratio, if necessary. In the prepolymerization reaction, a known additive can be added in an appropriate ratio, if necessary. Examples of additives include antioxidants, heat stabilizers, light stabilizers, and co-catalysts. These can be used alone or in combination of two or more types.

This results in a reaction product liquid of the prepolymerization reaction (hereinafter referred to as the prepolymerization reaction liquid). The prepolymerization reaction liquid contains a prepolymerization reaction product of the polyisocyanate component and the polyol component. The prepolymerization reaction liquid may also contain, for example, unreacted polyisocyanate component.

If the prepolymerization reaction liquid contains unreacted polyisocyanate components, the unreacted polyisocyanate components can be separated from the prepolymerization reaction liquid as needed using a known method. Separation methods include, for example, distillation and extraction. Separation conditions are appropriately set depending on the purpose and application.

The prepolymerization reaction liquid may also contain an organic solvent and/or a urethane-forming catalyst. In such cases, the organic solvent and/or the urethane-forming catalyst can be separated from the prepolymerization reaction liquid as needed using a known method. Examples of separation methods include distillation and extraction. Separation conditions are set appropriately depending on the purpose and application.

The isocyanate group concentration of the prepolymerization reaction liquid is, for example, 3.0% by mass or more, preferably 5.0% by mass or more. The isocyanate group concentration of the prepolymerization reaction liquid is, for example, 20.0% by mass or less, preferably 18.0% by mass or less, and more preferably 16.0% by mass or less.

The polyisocyanate composition contains the isocyanate-terminated prepolymer described above. The polyisocyanate composition may also contain additives. The additives may be included as optional components. Examples of additives include urethane catalysts, catalyst activity modifiers, antioxidants, heat stabilizers, light stabilizers, UV absorbers, antiblocking agents, mold release agents, pigments, dyes, lubricants, fillers, hydrolysis inhibitors, rust inhibitors, and bluing agents. The amount and timing of addition of the additives are determined appropriately depending on the purpose and application.

The polyisocyanate composition may or may not contain an organic solvent. Preferably, the polyisocyanate composition does not contain a solvent. The solids concentration of the polyisocyanate composition is, for example, 95% by mass or more, preferably 99% by mass or more. The solids concentration of the polyisocyanate composition is, for example, 100% by mass or less.

In addition, in the polyisocyanate composition (solid content (hereinafter the same)), the isocyanate monomer concentration (concentration of unreacted pentamethylene diisocyanate) is, for example, 5% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less. In addition, the isocyanate monomer concentration (concentration of unreacted pentamethylene diisocyanate) is typically 0% by mass or more.

The isocyanate group concentration (based on solids content) of the polyisocyanate composition is, for example, 10% by mass or more, preferably 15% by mass or more. The isocyanate group concentration of the polyisocyanate composition is, for example, 30% by mass or less, preferably 25% by mass or less. The isocyanate group concentration can be determined by known measurement methods.

In the above polyisocyanate composition, the polyisocyanate component used to obtain the isocyanate-terminated prepolymer contains an isocyanurate derivative of pentamethylene diisocyanate. The isocyanurate derivative of pentamethylene diisocyanate contains an isocyanurate of pentamethylene diisocyanate partially modified with an alcohol component. In the isocyanurate derivative of pentamethylene diisocyanate, the ratio (equivalent ratio) of pentamethylene diisocyanate to the alcohol component is within a specified range. The isocyanate-terminated prepolymer contains a reaction product obtained by reacting the above polyisocyanate component with a polyol component at a specified ratio (equivalent ratio).

As a result, the above polyisocyanate composition produces a polyurethane resin with excellent breaking strength, breaking elongation, and solvent resistance.

The above-described polyisocyanate composition is suitable for use as a raw material component for polyurethane resins. The form of the polyurethane resin is not particularly limited, but examples include one-component curing polyurethanes and two-component curing polyurethanes, with two-component curing polyurethanes being preferred. Examples of two-component curing polyurethanes include paints, adhesives, and coating agents, with coating agents being preferred.

The coating agent is a resin kit containing a base agent and a curing agent. The base agent and curing agent are prepared in separate packages and mixed at the time of use. The mixture is then applied and cured to form a polyurethane resin.

The base agent contains, for example, a macropolyol. Examples of macropolyols include the high molecular weight polyols described above. More specific examples of macropolyols include the polyether polyols described above, polyester polyols described above, polycarbonate polyols described above, polyurethane polyols described above, epoxy polyols described above, vegetable oil polyols described above, polyolefin polyols described above, acrylic polyols described above, fluorine polyols described above, and vinyl monomer-modified polyols described above. These can be used alone or in combination of two or more types. Preferred examples of macropolyols include acrylic polyols and fluorine polyols, and more preferably acrylic polyols.

The curing agent contains the polyisocyanate composition described above. If necessary, the polyisocyanate composition may be dissolved in a known solvent.

The base agent and curing agent are prepared separately and mixed at the time of use. The mixing ratio of the base agent and curing agent is adjusted, for example, according to the equivalent ratio (third equivalent ratio, NCO/OH) of the isocyanate groups in the curing agent (polyisocyanate composition) to the hydroxyl groups in the base agent (macropolyol).

More specifically, the third equivalent ratio (NCO/OH) of the isocyanate groups in the curing agent (polyisocyanate composition) to the hydroxyl groups in the base compound (macropolyol) is, for example, 0.5 or more, preferably 0.8 or more. Furthermore, the third equivalent ratio (NCO/OH) of the isocyanate groups in the curing agent (polyisocyanate composition) to the hydroxyl groups in the base compound (macropolyol) is, for example, 1.5 or less, preferably 1.2 or less.

The mixture of base agent and curing agent is then applied to the substrate using any coating method. Examples of coating methods include spray coating, air spray coating, brush coating, dipping, roll coating, flow coating, dry lamination, wet lamination, and direct coating. There are no particular restrictions on the substrate, but examples include plastic film, fiber-reinforced plastic, metal foil, metal-deposited film, and steel. The amount of coating is determined appropriately depending on the purpose and application.

The mixture of base resin and curing agent then dries and hardens, resulting in a cured polyurethane resin.

Such coating agents contain the above-mentioned polyisocyanate composition as a curing agent. Therefore, the above-mentioned coating agent produces polyurethane resins with excellent breaking strength, breaking elongation, and solvent resistance.

As a result, the polyisocyanate composition and coating agent described above are suitable for use in a variety of industrial fields. Examples of applications for the polyisocyanate composition and coating agent include automotive paints, paints for electronic devices, and architectural paints.

Next, the present invention will be described based on manufacturing examples, working examples, and comparative examples, but the present invention is not limited to these examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values for blending ratios (content ratios), physical properties, parameters, etc. used in the following description can be substituted with the corresponding upper limit values (numeric values defined as "equal to or less than") or lower limit values (numeric values defined as "equal to or greater than" or "exceeding") of the blending ratios (content ratios), physical properties, parameters, etc. described in the "Description of the Invention" above.

1. GPC
The sample was subjected to gel permeation chromatography (GPC) measurement, and the area ratio of each peak area to the total peak area in the resulting chromatogram (chart) was calculated.

The area ratio of the peak having a peak top in the range of polystyrene-equivalent molecular weight of 400 or more but less than 480 (Mn400-480 area ratio) was taken as the mononuclear content in the isocyanurate derivative of pentamethylene diisocyanate.

Approximately 0.03 g of sample was dissolved in 10 mL of tetrahydrofuran. The resulting solution was then subjected to GPC measurement.

<GPC Measurement>
・Analyzer: High-speed GPC device HLC-8320 (manufactured by Tosoh Corporation)
Detector: Differential refractive index detector Eluent: Tetrahydrofuran Separation column: The following (1) to (4) were connected in series: (1) TSKgel guard column HXL-L 6.0 x 40 (manufactured by Tosoh Corporation)
(2) TSKgel G1000HXL 7.8 x 300 (manufactured by Tosoh Corporation)
(3) TSKgel G2000HXL 7.8 x 300 (manufactured by Tosoh Corporation)
(4) TSKgel G3000HXL 7.8 x 300 (manufactured by Tosoh Corporation)
・Measurement temperature: 40℃
・Flow rate: 1mL/min
・Injection volume: 100μL
・Analysis device: Eco SEC (manufactured by Tosoh Corporation)
<System Correction>
・Standard substance name: Polystyrene ・Calibration curve creation method: A graph of retention time and molecular weight was created using TSKstandard polystyrenes with different molecular weights manufactured by TOSOH Corporation.
・Polystyrene injection volume: 100 μL
Polystyrene injection concentration: 1 mg/mL

The chromatogram obtained by gel permeation chromatography using the isocyanurate derivative of pentamethylene diisocyanate from Synthesis Example 1 as a sample is shown in Figure 1.

2. Polyisocyanate Component Synthesis Example 1
The following components were placed in a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and the temperature was raised to 80°C.
1,5-pentamethylene diisocyanate (PDI) 100 parts by mass Irganox 1076 (antioxidant, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, product name, manufactured by BASF) 0.05 parts by mass JP-310 (cocatalyst, tridecyl phosphite, product name, manufactured by Johoku Chemical Co., Ltd.) 0.1 parts by mass

Next, isobutanol (IBA, alcohol component) was added to the flask and heated at 80°C for 3 hours to partially modify the PDI with IBA. The amount of IBA was adjusted so that the equivalent ratio of the isocyanate groups of the PDI to the hydroxyl groups of the IBA (second equivalent ratio, NCO/OH) was 70.

Next, 0.01 parts by mass of N-(2-hydroxypropyl)-N,N,N-trimethylammonium-2-ethylhexanoate was dissolved in 0.03 parts by mass of propylene glycol methyl ether acetate to prepare a catalyst solution. The catalyst solution was then added to the flask.

The temperature inside the flask was then raised using the heat of reaction. As a result, the PDI partially modified with IBA was converted into an isocyanurate. Then, when the following reaction termination conditions were met, 0.01 parts by mass of o-toluenesulfonamide (reaction terminator) was added to the flask to terminate the reaction.
Reaction termination conditions: Flask temperature: 120°C
Isocyanate group conversion rate: 10.7% by mass

The reaction product liquid in the flask was subjected to thin-film distillation (vacuum degree 50 Pa, temperature 150°C) to remove unreacted PDI. This yielded a pentamethylene diisocyanate derivative.

Synthesis Examples 2 to 5
The amount of isobutanol added was changed so that the second equivalent ratio (the equivalent ratio of the isocyanate group of PDI to the hydroxyl group of IBA) would be the value shown in Tables 1 to 5. Other than this, pentamethylene diisocyanate derivatives were obtained in the same manner as in Synthesis Example 1.

Synthesis Example 6
A derivative of hexamethylene diisocyanate was obtained in the same manner as in Synthesis Example 1, except that 1,6-hexamethylene diisocyanate (HDI) was used instead of PDI.

Synthesis Examples 7 to 9
The amount of isobutanol added was changed so that the second equivalent ratio (the equivalent ratio of the isocyanate group of HDI to the hydroxyl group of IBA) would be the value shown in Tables 1 to 5. Other than this, a hexamethylene diisocyanate derivative was obtained in the same manner as in Synthesis Example 6.

Synthesis Example 10
The reaction termination conditions were changed as follows: A pentamethylene diisocyanate derivative was obtained in the same manner as in Synthesis Example 1, except for the following.
Reaction termination conditions Temperature inside flask: 100°C
Isocyanate group conversion rate: 5.0% by mass

Reference synthesis example 1
A hexamethylene diisocyanate derivative was obtained by the same method as in Synthesis Example 2 of JP-A-2020-139017.

That is, in a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, 1,000 parts by mass of 1,6-hexamethylene diisocyanate and 30 parts by mass of 2-ethylhexanol (2-EH) were alcohol-denatured at 90°C for 1 hour.

Next, a catalyst solution was prepared by diluting tetramethylammonium caprate with isobutanol to 5% by mass. One part by mass of the catalyst solution was then added to a flask, and the isocyanuration reaction was carried out. Next, phosphoric acid was added to the flask at the specified time to stop the reaction. The reaction product was then purified by filtration and thin-film distillation. This yielded a hexamethylene diisocyanate derivative.

Reference synthesis example 2
A pentamethylene diisocyanate derivative was obtained in the same manner as in Example 1 of WO 2016/098771 (Patent No. 6386085).

That is, the following components were charged into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and a prepolymerization reaction was carried out at 80° C. for 2 hours.
1,5-pentamethylene diisocyanate (PDI) 1000 parts by mass PCD500 (polycarbonate diol, trade name ETERNACOLL UH-50, manufactured by Ube Industries, functional group number 2, number average molecular weight 500) 129.7 parts by mass 2,6-di(tert-butyl)-4-methylphenol 0.6 parts by mass Tris(tridecyl)phosphite 0.6 parts by mass

The flask was then cooled to 60°C. 0.15 parts by mass of an isocyanuration catalyst (N-(2-hydroxypropyl)-N,N,N-trimethylammonium-2-ethylhexanoate) was then added to the flask, and the isocyanuration reaction was carried out for approximately 40 minutes. After that, 0.15 parts by mass of o-toluenesulfonamide was added to the flask. The isocyanate group conversion rate was 20% by mass.

The resulting reaction product liquid was then purified by thin-film distillation (vacuum degree 0.093 KPa, temperature 150°C). Furthermore, 0.02 parts by mass of o-toluenesulfonamide was added per 100 parts by mass of the purified product. This yielded a pentamethylene diisocyanate derivative.

Reference synthesis example 3
A pentamethylene diisocyanate derivative was obtained in the same manner as in Example 12 of WO 2016/098771 (Patent No. 6386085).

That is, the following components were charged into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and a prepolymerization reaction was carried out at 85° C. for 3 hours.
1,5-pentamethylene diisocyanate (PDI) 1000 parts by mass PCD500 (polycarbonate diol, trade name ETERNACOLL UH-50, manufactured by Ube Industries, functional group number 2, number average molecular weight 500) 162.2 parts by mass 2,6-di(tert-butyl)-4-methylphenol 0.6 parts by mass Tris(tridecyl)phosphite 0.6 parts by mass

The flask was then heated to 100°C. 0.05 parts by mass of an allophanation catalyst (lead octoate) was then added to the flask, and the allophanation reaction was carried out. 0.15 parts by mass of o-toluenesulfonamide was then added to the flask.

The resulting reaction product liquid was then purified by thin-film distillation (vacuum degree 0.093 KPa, temperature 150°C). Furthermore, 0.02 parts by mass of o-toluenesulfonamide was added per 100 parts by mass of the purified product. This yielded a pentamethylene diisocyanate derivative.

3. Polyisocyanate Compositions Examples 1 to 15, Comparative Examples 1 to 10, and Reference Example 1
According to the formulations shown in Tables 1 to 5, a polyisocyanate component and a polyol component were charged into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube.

The amounts of the polyisocyanate component and the polyol component were adjusted so that the equivalent ratio (first equivalent ratio, NCO/OH) of the isocyanate groups of the polyisocyanate component to the hydroxyl groups of the polyol component would be the values shown in Tables 1 to 5.

Next, the polyisocyanate component and the polyol component were subjected to a prepolymerization reaction at 90°C for 3 hours. It was then confirmed that the isocyanate group concentration in the reaction solution was equal to or less than the isocyanate group concentration calculated from the blending ratio of the polyisocyanate component and the polyol component. In other words, it was confirmed that all hydroxyl groups had reacted. This resulted in a polyisocyanate composition containing an isocyanate-terminated prepolymer.

Reference examples 2-3
The pentamethylene diisocyanate derivatives obtained in Reference Synthesis Examples 2 and 3 were used as polyisocyanate compositions.

4. Evaluation (1) Appearance of Polyurethane Resin Composition (a) Turbidity Upon completion of the synthesis of the polyisocyanate composition, the turbidity of the reaction product liquid was visually confirmed and evaluated according to the following criteria.
◯: No turbidity (floating microgel particles) was observed.
×: Turbidity (floating microgel particles) was observed.

(2) Physical Properties of Polyurethane Resin (a) Formation of Coating Film Each polyisocyanate composition was prepared as a curing agent. An acrylic polyol was prepared as a base resin. The acrylic polyol was Olester Q182 (trade name, manufactured by Mitsui Chemicals, Inc., hydroxyl value 45 mg KOH/g, solids concentration 50%).

Next, the base resin and curing agent were mixed so that the equivalent ratio (NCO/OH) of the isocyanate groups in the curing agent to the hydroxyl groups in the base resin was 1.0. Furthermore, a mixed solvent was added to the mixture, and the mixture was mixed at 23°C for 5 minutes to adjust the solids concentration to 50% by mass. The mixed solvent was a mixture of 100 parts by mass of ethyl acetate, 100 parts by mass of butyl acetate, and 100 parts by mass of propylene glycol monomethyl ether acetate.

The mixture was then ultrasonicated for 10 minutes and degassed, yielding a coating solution. The coating solution was then applied to a polypropylene plate and a steel plate (SPCC steel plate, PBN-144 treated) to obtain a coating film. A 4-mil applicator was used for application. The coating film was then heated in an oven at 80°C for 60 minutes to obtain a cured coating film (polyurethane resin). The cured coating film was then aged for 7 days in a constant temperature room at 23°C and 55% humidity.

(b) Tensile Test: A 1 cm wide x 10 cm long evaluation sample was prepared using a cured coating film formed on a polypropylene plate. The film thickness was measured at three points near the center of the sample using a film thickness meter (dual type film thickness meter LZ990, manufactured by Kett Electric Laboratory), and the average value was taken as the film thickness of the sample. It was confirmed that the film thickness of each sample was approximately the same (approximately 40 μm).

The breaking strength and breaking elongation of each sample were then measured five times under the following conditions, and the average values were calculated. The average values are shown in Tables 1 to 5.
Tensile tester: Model 201B (manufactured by Intesco)
Chuck spacing: 5cm
Tensile speed: 50 mm/min
Temperature: 23℃
Humidity: 55%

The evaluation criteria for breaking strength are as follows.
◎: 35 MPa or more ◯: 30 MPa or more but less than 35 MPa △: 25 MPa or more but less than 30 MPa ×: less than 25 MPa

The evaluation criteria for breaking elongation are as follows.
◎: 45% or more 〇: 30% or more but less than 45% △: 10% or more but less than 30% ×: Less than 10%

(c) Solvent Resistance The cured coating film formed on the steel plate was set in a rubbing tester (Model IMC-0717, manufactured by Imoto Manufacturing Co., Ltd.). Absorbent cotton moistened with methyl ethyl ketone was placed on the end of a 2 kg weight. The cured coating film was then rubbed. The number of rubbing strokes at which the cured coating film broke and the steel plate was exposed was then measured.

The evaluation criteria for solvent resistance are as follows.
◎: 50 or more round trips ○: 40 to less than 50 round trips △: 30 to less than 40 round trips ×: Less than 30 round trips

(3) Discussion (a) First Equivalent Ratio As seen in Examples 1 to 3 and Comparative Examples 1 and 2, when pentamethylene diisocyanate was used, significant changes in the physical properties of the polyurethane resin were confirmed by changing the first equivalent ratio. More specifically, by adjusting the first equivalent ratio within a predetermined range, a polyurethane resin having good breaking strength, breaking elongation, and solvent resistance was obtained.

On the other hand, as can be seen from Comparative Examples 1 to 3, when hexamethylene diisocyanate was used instead of pentamethylene diisocyanate, no significant changes in the physical properties of the polyurethane resin were observed even when the first equivalent ratio was changed.

(b) Second Equivalent Ratio As seen in Examples 16 to 17 and Comparative Examples 6 and 7, when pentamethylene diisocyanate was used, changing the second equivalent ratio was confirmed to significantly change the physical properties of the polyurethane resin. More specifically, by adjusting the second equivalent ratio within a predetermined range, a polyurethane resin having good breaking strength, breaking elongation, and solvent resistance was obtained.

On the other hand, as can be seen from Comparative Examples 8 to 10, when hexamethylene diisocyanate was used instead of pentamethylene diisocyanate, no significant changes in the physical properties of the polyurethane resin were observed even when the second equivalent ratio was changed.

Details of the abbreviations in the table are given below.
PDI: Pentamethylene diisocyanate HDI: Hexamethylene diisocyanate 1,3BG: 1,3-butanediol IBA: Isobutyl alcohol 2-EH: 2-ethylhexanol PCD (number average molecular weight 500): Polycarbonate diol ETERNACOLL UH-50 manufactured by Ube Industries, Ltd.
PCD (number average molecular weight 1000): Polycarbonate diol, ETERNACOLL UH-100 manufactured by Ube Industries, Ltd.
PCD (number average molecular weight 2000): Polycarbonate diol, ETERNACOLL UH-200 manufactured by Ube Industries, Ltd.
PCL (bifunctional, number average molecular weight 530): polycaprolactone diol (polyester diol) manufactured by Daicel Corporation, Plaxel 205
PCL (trifunctional, number average molecular weight 550): Polycaprolactone diol (polyester triol) manufactured by Daicel Corporation, Plaxel 305
PCL (bifunctional, number average molecular weight 1000): polycaprolactone diol (polyester diol) manufactured by Daicel Corporation, Plaxel 210
PCL (bifunctional, number average molecular weight 1250): polycaprolactone diol (polyester diol) manufactured by Daicel Corporation, Plaxel 212
PCL (bifunctional, number average molecular weight 2000): polycaprolactone diol (polyester diol) manufactured by Daicel Corporation, Plaxel 220
PTMG (number average molecular weight 225): Polytetramethylene ether glycol, PTMG250 manufactured by Mitsubishi Chemical Corporation
PTMG (number average molecular weight 650): Polytetramethylene ether glycol, manufactured by Mitsubishi Chemical Corporation, PTMG650
PTMG (number average molecular weight 1000): Polytetramethylene ether glycol, manufactured by Mitsubishi Chemical Corporation, PTMG1000
PTMG (number average molecular weight 2000): Polytetramethylene ether glycol, PTMG2000 manufactured by Mitsubishi Chemical Corporation

Claims (5)

A polyisocyanate composition comprising an isocyanate group-terminated prepolymer,
the isocyanate group-terminated prepolymer comprises a reaction product of a polyisocyanate component and a polyol component,
The polyisocyanate component comprises an isocyanurate derivative of pentamethylene diisocyanate;
The isocyanurate derivative of the pentamethylene diisocyanate includes an isocyanurate-modified product of pentamethylene diisocyanate partially modified with an alcohol component,
In the isocyanate group-terminated prepolymer, a first equivalent ratio (NCO/OH) of an isocyanate group of the polyisocyanate component to a hydroxyl group of the polyol component is 3.0 or more and 8.0 or less;
a second equivalent ratio (NCO/OH) of the isocyanate groups of the pentamethylene diisocyanate to the hydroxyl groups of the alcohol component in the isocyanurate derivative of the pentamethylene diisocyanate is 60 or more and 600 or less. The isocyanurate derivative of the pentamethylene diisocyanate includes a mononuclear isocyanurate of pentamethylene diisocyanate,
The isocyanurate mononuclear compound of the pentamethylene diisocyanate is a derivative compound containing one isocyanurate group and three molecules of pentamethylene diisocyanate,
In the chromatogram obtained by measuring the isocyanurate derivative of the pentamethylene diisocyanate by gel permeation chromatography,
2. The polyisocyanate composition according to claim 1, wherein the area ratio of the peak area corresponding to the isocyanurate mononuclear unit of the pentamethylene diisocyanate to the area of all peaks is 40% or more. The polyisocyanate composition according to claim 1 or 2, wherein the number average molecular weight of the polyol component is 200 or more and 1,000 or less. The polyisocyanate composition according to any one of claims 1 to 3, wherein the average number of hydroxyl groups in the polyol component is 2. Contains a base agent and a hardener,
The base material contains a macropolyol,
A coating agent, wherein the curing agent comprises the polyisocyanate composition according to any one of claims 1 to 4.