Butane diisocyanate derivative, method for producing butane diisocyanate derivative, polyisocyanate composition, polyurethane resin-forming composition, coating composition and coating film

Abstract

The present invention provides a butane diisocyanate derivative which has an isocyanurate group and a uretdione group, wherein: the molar ratio of the isocyanurate group to the uretdione group is 20 / 80 to 80 / 20; and the weight average molecular weight as determined by gel permeation chromatography is 790 g / mol or less.

Description

[Technical field]

[0001] The present disclosure relates to a butane diisocyanate derivative, a method for producing a butane diisocyanate derivative, a polyisocyanate composition, a polyurethane resin-forming composition, a coating composition, and a coating film. [Background technology]

[0002] From the viewpoint of reducing the environmental burden, there has been active development of polyisocyanate compositions that pursue low viscosity and quick drying. By reducing the viscosity of polyisocyanate compositions, the amount of organic solvent used in the coating composition can be reduced. By having polyisocyanate compositions with excellent drying properties, the thermal energy required for the curing reaction can be reduced.

[0003] Here, Patent Document 1 discloses a coating composition in which the binder contains (a) an isocyanurate group-containing polyisocyanate made from 1,4-diisocyanatobutane (BDI) and having an isocyanate content of 20-30% by weight and a monomeric BDI content of less than 2% by weight, and (b) a polyol component in a predetermined ratio. According to Patent Document 1, this isocyanurate group-containing polyisocyanate can be rapidly dried under mild curing conditions to form a coating.

[0004] Patent Document 2 discloses a polyisocyanate composition containing a copolymer polyisocyanate consisting of an aliphatic diisocyanate unit and an alicyclic diisocyanate unit, and / or an aliphatic polyisocyanate consisting of an aliphatic diisocyanate unit and an alicyclic polyisocyanate consisting of an alicyclic diisocyanate unit, the molar ratio of the aliphatic diisocyanate unit / the alicyclic diisocyanate unit in the polyisocyanate composition being a predetermined ratio, the polyisocyanate composition containing a polyisocyanate having a predetermined content of isocyanurate groups, and having a predetermined viscosity. According to Patent Document 2, this polyisocyanate composition has low viscosity and excellent quick-drying properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-132751 [Patent Document 2] JP 2015-127368 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the isocyanurate group-containing polyisocyanate described in Patent Document 1 has a problem that the viscosity is high and the amount of dilution solvent used is increased. In addition, the polyisocyanate composition described in Patent Document 2 does not consider the hardness of the resulting coating film, and does not sufficiently achieve both low viscosity and high hardness.

[0007] Here, although there has been an extremely strong demand from the market for reducing the environmental load, particularly in recent years, as described above, it has been difficult to realize a polyisocyanate composition that has low viscosity, excellent quick-drying properties, and is useful for producing a coating film with high hardness.

[0008] Therefore, one aspect of the present disclosure is directed to providing a polyisocyanate composition that has low viscosity, is excellent in quick drying property, and contributes to the preparation of a coating film with high hardness. Other aspects of the present disclosure are directed to providing a butane diisocyanate derivative that contributes to the preparation of the polyisocyanate composition and a method for producing the butane diisocyanate derivative. Still other aspects of the present disclosure are directed to providing a polyurethane resin-forming composition, a coating composition, and a coating film using the polyisocyanate composition. [Means for solving the problem]

[0009] In some aspects, the present disclosure provides the following [1] to

[11] .

[0010] [1] A butane diisocyanate derivative having an isocyanurate group and a uretdione group, a molar ratio of the isocyanurate groups to the uretdione groups is 20 / 80 to 80 / 20; A butane diisocyanate derivative having a weight average molecular weight of 790 g / mol or less based on gel permeation chromatography.

[0011] [2] Contains butane diisocyanate trimer and butane diisocyanate dimer, The butane diisocyanate derivative according to [1], wherein a total content of the butane diisocyanate trimer and the butane diisocyanate dimer is 45 to 95 mass% based on the total mass of the butane diisocyanate derivative.

[0012] [3] The butane diisocyanate derivative according to [1] or [2], wherein a molar ratio of the isocyanurate groups to the uretdione groups is 50 / 50 or more.

[0013] [4] The butane diisocyanate derivative according to any one of [1] to [3], wherein a molar ratio of the isocyanurate groups to the uretdione groups is 60 / 40 or less.

[0014] [5] A method for producing the butane diisocyanate derivative according to any one of [1] to [4], A first heating step of heating a reactant containing butane diisocyanate to 80° C. or higher; a second heating step of heating the reaction product obtained in the first heating step at 80 to 180° C. in the presence of an isocyanurate catalyst.

[0015] [6] The method for producing a butane diisocyanate derivative according to [5], wherein the isocyanurate catalyst contains an aminosilyl group-containing compound.

[0016] [7] A polyisocyanate composition comprising the butane diisocyanate derivative according to any one of [1] to [4].

[0017] [8] The polyisocyanate composition according to [7], having a viscosity at 25°C of 2500 mPa s or less.

[0018] [9] A polyurethane resin-forming composition comprising the polyisocyanate composition according to [7] or [8] and a polyol.

[0019]

[10] A coating composition comprising the polyisocyanate composition according to [8] and a compound having two or more isocyanate-reactive groups.

[0020]

[11] A coating film comprising a cured product of the coating composition according to

[10] . Effect of the Invention

[0021] According to one aspect of the present disclosure, it is possible to provide a polyisocyanate composition that has low viscosity, is excellent in quick-drying property, and contributes to the preparation of a coating film with high hardness. According to some other aspects of the present disclosure, it is possible to provide a butane diisocyanate derivative that contributes to the preparation of the polyisocyanate composition, and a method for producing the butane diisocyanate derivative. According to still other aspects of the present disclosure, it is possible to provide a polyurethane resin-forming composition, a coating composition, and a coating film using the polyisocyanate composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In this specification, a numerical range indicated using "~" indicates a range including the numerical values ​​described before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range in a certain stage may be replaced with the upper limit or lower limit of a numerical range in another stage. In addition, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples. Furthermore, the upper limit and lower limit values ​​described individually can be combined in any combination.

[0023] Preferred embodiments of each aspect of the present disclosure will be described below. However, each aspect of the present disclosure is not limited to the following embodiments.

[0024] <Butane diisocyanate derivative and polyisocyanate composition> The butane diisocyanate derivative according to one embodiment of the present disclosure has an isocyanurate group and a uretdione group, the molar ratio of the isocyanurate group to the uretdione group (total number of moles of isocyanurate group / total number of moles of uretdione group) is 20 / 80 to 80 / 20, and the weight average molecular weight based on gel permeation chromatography is 790 g / mol or less. In the following description, butane diisocyanate may be abbreviated as "BDI", and the molar ratio of the isocyanurate group to the uretdione group may be abbreviated as "molar ratio (I / U)".

[0025] According to the above BDI derivative, it is possible to prepare a polyisocyanate composition that has low viscosity, is excellent in quick drying, and contributes to the preparation of a coating film with high hardness. The low viscosity of the polyisocyanate composition can be confirmed, for example, by the viscosity at 25°C measured by a rheometer. The excellent quick drying property of the polyisocyanate composition can be confirmed, for example, by the curing initiation temperature of a coating film made of a coating composition prepared using the polyisocyanate composition. The high hardness of the coating film obtained using the polyisocyanate composition can be confirmed, for example, by the Martens hardness of the coating film at 23°C.

[0026] The polyisocyanate composition according to another embodiment of the present disclosure includes a BDI derivative having an isocyanurate group and a uretdione group, and a molar ratio (I / U) of 20 / 80 to 80 / 20. The weight average molecular weight of the BDI derivative based on gel permeation chromatography is preferably 790 g / mol or less. That is, the BDI derivative is preferably the BDI derivative described above.

[0027] The polyisocyanate composition tends to have a low viscosity and a quick-drying property. Furthermore, the polyisocyanate composition is likely to give a coating film with high hardness.

[0028] The BDI derivative is a mixture of a plurality of compounds derived from a BDI monomer. The BDI derivative includes, for example, an isocyanurate of BDI and a uretdione of BDI. The isocyanurate of BDI is a compound derived from a BDI monomer that has an isocyanurate group (a group formed by cyclopolymerization of three BDI monomer molecules). The uretdione of BDI is a compound derived from a BDI monomer that has a uretdione group (a group formed by cyclopolymerization of two BDI monomer molecules). The BDI derivative may include a compound derived from a BDI monomer that has an isocyanurate group and a uretdione group (a compound that is both an isocyanurate and a uretdione). Such a compound corresponds to both an isocyanurate of BDI and a uretdione of BDI.

[0029] Examples of BDI monomers that are raw materials for the isocyanurate and uretdione compounds of BDI include 1,2-butane diisocyanate, 1,3-butane diisocyanate, 1,4-butane diisocyanate, 2,3-butane diisocyanate, and mixtures thereof. The raw materials for the isocyanurate and uretdione compounds of BDI preferably contain 1,4-butane diisocyanate because the isocyanate groups bonded to the primary carbons have high reactivity. The ratio of 1,4-butane diisocyanate in the raw materials for the isocyanurate and uretdione compounds of BDI may be 90% by mass or more, 95% by mass or more, or 100% by mass. In the following, an embodiment in which 1,4-butane diisocyanate is used as the BDI monomer will be described as an example, but unless otherwise specified, the present invention is not limited to this.

[0030] The isocyanurate of BDI preferably contains an isocyanurate trimer of BDI. The isocyanurate trimer of BDI is, for example, a compound represented by the following formula (1).

[0031] [ka]

[0032] The isocyanurate of BDI may contain a tetramer or higher polymer formed by further polymerization of an isocyanate group (hereinafter sometimes abbreviated as "NCO group") in the isocyanurate trimer of BDI with an NCO group in another BDI monomer (or a compound derived from another BDI monomer). The isocyanurate of BDI more preferably contains the isocyanurate trimer of BDI and the above-mentioned tetramer or higher polymer, and further more preferably contains the isocyanurate trimer of BDI, an isocyanurate pentamer of BDI (a compound formed by cyclopolymerization of one NCO group in the isocyanurate trimer of BDI with two other BDI monomer molecules), and an isocyanurate heptamer of BDI (a compound formed by cyclopolymerization of each of the two NCO groups in the isocyanurate trimer of BDI with two other BDI monomer molecules). As described above, the isocyanurate of BDI may contain, as the tetramer or higher polymer, a compound having a uretdione group (for example, a compound formed by cyclopolymerization of one or two NCO groups in an isocyanurate trimer of BDI with one molecule of another BDI monomer).

[0033] The uretdione derivative of BDI preferably includes a uretdione dimer of BDI. The uretdione dimer of BDI is, for example, a compound represented by the following formula (2).

[0034] [ka]

[0035] The uretdione compound of BDI may contain a trimer or higher polymer formed by further polymerization of an NCO group in a uretdione dimer of BDI with an NCO group in another BDI monomer (or a compound derived from another BDI monomer). The uretdione compound of BDI more preferably contains a uretdione dimer of BDI and the trimer or higher polymer, and further preferably contains a uretdione dimer of BDI, a uretdione trimer of BDI (a compound formed by cyclopolymerization of one NCO group in a uretdione dimer of BDI with one molecule of another BDI monomer), and a uretdione tetramer of BDI (a compound formed by cyclopolymerization of each of two NCO groups in a uretdione dimer of BDI with one molecule of another BDI monomer). As described above, the uretdione derivative of BDI may contain, as the trimer or higher polymer, a compound having an isocyanurate group (for example, a compound formed by cyclopolymerization of one or each of two NCO groups in a uretdione dimer of BDI with two other BDI monomer molecules).

[0036] The BDI derivative has a molar ratio (I / U). The molar ratio (I / U) is the molar ratio of isocyanurate groups to uretdione groups in the BDI derivative, and can be rephrased as the molar ratio of isocyanurate groups in the isocyanurate body of BDI to uretdione groups in the uretdione body of BDI. The molar ratio (I / U) of the BDI derivative is 20 / 80 to 80 / 20, and may be 25 / 75 or more, 30 / 70 or more, or 50 / 50 or more, and may be 75 / 25 or less, 70 / 30 or less, or 60 / 40 or less. When the molar ratio (I / U) is 50 / 50 or more, a coating film with higher hardness tends to be obtained, and when the molar ratio (I / U) is 60 / 40 or less, the viscosity tends to be further reduced. The molar ratio (I / U) can be, for example, measured by a nuclear magnetic resonance (NMR) apparatus. 1 It can be measured by H-NMR method. More specifically, it can be measured in accordance with the examples described later.

[0037] The BDI derivative and polyisocyanate composition preferably contains a BDI trimer (e.g., an isocyanurate trimer of BDI and a uretdione trimer of BDI) and a BDI dimer (e.g., a uretdione dimer of BDI).In this case, the viscosity of the polyisocyanate composition tends to be lower and the workability tends to be better.

[0038] The total content of the BDI trimer and the BDI dimer is preferably 45% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, from the viewpoint of promoting a decrease in viscosity of the polyisocyanate composition. The total content of the BDI trimer and the BDI dimer is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, from the viewpoint of increasing the crosslink density of the resin. From these viewpoints, the total content of the BDI trimer and the BDI dimer may be, for example, 45 to 95% by mass. The total content of the BDI trimer and the BDI dimer may be 60% by mass or more, 65% by mass or more, 75% by mass or more, or 80% by mass or more, or 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less.

[0039] The content of the BDI trimer may be 20% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more, from the viewpoint of promoting high hardness of the coating film. The content of the BDI trimer may be 90% by mass or less, 65% by mass or less, 55% by mass or less, or 45% by mass or less, from the viewpoint of promoting low viscosity of the polyisocyanate composition. From these viewpoints, the content of the BDI trimer may be, for example, 20 to 90% by mass, or 20 to 65% by mass.

[0040] The content of the BDI dimer may be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 35% by mass or more, from the viewpoint of promoting a low viscosity of the polyisocyanate composition. The content of the BDI dimer may be 80% by mass or less, 65% by mass or less, 50% by mass or less, or 40% by mass or less, from the viewpoint of promoting a high hardness of the coating film. From these viewpoints, the content of the BDI dimer may be, for example, 10 to 80% by mass, or 10 to 65% by mass.

[0041] The total content of the BDI trimer and BDI dimer, and the respective contents of the BDI trimer and BDI dimer are based on the total mass of the BDI derivatives or the total mass of the solid content in the polyisocyanate composition, and are values ​​calculated from the differential refractive index peaks of the BDI derivatives or the polyisocyanate composition by gel permeation chromatography (GPC). More specifically, these amounts can be measured in accordance with the examples described later.

[0042] The BDI derivative and polyisocyanate composition may contain compounds derived from BDI monomers (such as biuret forms of BDI) in addition to the isocyanurate form of BDI and the uretdione form of BDI, but the content of such compounds (hereinafter also referred to as "other BDI derivatives") is preferably 20 mol% or less, and more preferably 1 mol% or less (substantially free of the above compounds). The above content is based on the sum of the moles of isocyanurate groups, uretdione groups, and other BDI derivatives (such as biuret forms of BDI) in the BDI derivative.

[0043] The NCO content of the BDI derivative may be 10% by mass or more, 20% by mass or more, or 25% by mass or more based on the total mass of the solid content in the polyisocyanate composition, from the viewpoint of increasing the number of NCO groups used for crosslinking of the polyurethane resin. The NCO content of the BDI derivative may be 36% by mass or less, 33% by mass or less, or 30% by mass or less based on the total mass of the solid content in the polyisocyanate composition, from the viewpoint of reducing the content of low molecular weight components such as BDI monomers to suppress odor. From these viewpoints, the NCO content of the BDI derivative may be, for example, 10 to 36% by mass based on the total mass of the solid content in the polyisocyanate composition.

[0044] The BDI derivative may be blocked with a known blocking agent for the purpose of extending the pot life and forming a one-component coating composition. That is, some or all of the NCO groups in the isocyanurate of BDI may be blocked with a blocking agent, and some or all of the NCO groups in the uretdione of BDI may be blocked with a blocking agent. The blocked polyisocyanate is inactive at room temperature, but when heated, the blocking agent dissociates and the isocyanate group is activated again, so that it reacts with the active hydrogen group. The blocking agent is a compound having one active hydrogen in the molecule, and known blocking agents such as alcohols, alkylphenols, phenols, active methylene, mercaptans, acid amides, acid imides, imidazoles, ureas, oximes, amines, imides, and pyrazoles can be used. In addition, when the BDI derivative is blocked, the weight average molecular weight and viscosity described below are measured after the blocking agent is dissociated.

[0045] The weight average molecular weight of the BDI derivative based on gel permeation chromatography (GPC) is 790 g / mol or less, preferably 750 g / mol or less, more preferably 710 g / mol or less. By the weight average molecular weight of the BDI derivative being in the above range, it is possible to obtain a polyisocyanate composition having good compatibility with the base agent and further low viscosity. The weight average molecular weight may be 690 g / mol or less, 650 g / mol or less, 600 g / mol or less, or 550 g / mol or less. From the viewpoint of promoting high hardness of the coating film, the weight average molecular weight may be 400 g / mol or more, 450 g / mol or more, 500 g / mol or more, 550 g / mol or more, or 600 g / mol or more. From the same viewpoint, the weight average molecular weight of the polyisocyanate composition based on gel permeation chromatography may also be in the above range. More specifically, the weight average molecular weight can be measured according to the examples described later.

[0046] The polyisocyanate composition may contain components other than the BDI derivative, or may consist only of the BDI derivative. Examples of the other components include 1,6-hexane diisocyanate (hereinafter sometimes abbreviated as "HDI") and its derivatives.

[0047] The polyisocyanate composition may contain isocyanate compounds other than BDI derivatives (e.g. polyisocyanates such as BDI monomer, HDI monomer, and HDI derivatives) as other components, but the content of BDI monomer in the polyisocyanate composition is preferably 5% by mass or less, more preferably 1% by mass or less (substantially does not contain BDI monomer). The content of isocyanate compounds other than BDI derivatives in the polyisocyanate composition is preferably 50% by mass or less, more preferably 1% by mass or less (substantially does not contain isocyanate compounds other than BDI derivatives). The above content is based on the total mass of solids in the polyisocyanate composition.

[0048] The polyisocyanate composition may contain an organic solvent described below as other components, but the content of the organic solvent in the polyisocyanate composition is preferably 50% by mass or less, more preferably 20% by mass or less (substantially free of an organic solvent). The above content is the content based on the total mass of the solid content in the polyisocyanate composition.

[0049] The viscosity of the polyisocyanate composition at 25 °C is preferably 3000 mPa·s or less, more preferably 2500 mPa·s or less, still more preferably 2000 mPa·s or less, even more preferably 1000 mPa·s or less, and particularly preferably 500 mPa·s or less. When the above viscosity is 2500 mPa·s or less, the polyisocyanate composition has good workability without being diluted by a large amount of solvent, and the solid content concentration of the coating composition can be increased. The viscosity of the polyisocyanate composition at 25 °C may be, for example, 50 mPa·s or more, 100 mPa·s or more, or 150 mPa·s or more. When the viscosity is 50 mPa·s or more, the resulting coating film tends to have higher hardness. In terms of the ease of obtaining the polyisocyanate composition with the above viscosity, the preferred range of the viscosity of the BDI derivative at 25 °C is the same as the above range.

[0050] The BDI derivative and the polyisocyanate composition described above are suitably used as a curing agent component of a coating composition. That is, another embodiment of the present disclosure is a coating curing agent containing the above BDI derivative, and still another embodiment of the present disclosure is a coating curing agent comprising the above polyisocyanate composition. As the main agent for these coating curing agents, an isocyanate-reactive compound (such as a polyol) described below can be used.

[0051] <Method for Producing BDI Derivative> Another aspect of the present disclosure is a method for producing the BDI derivative of the above embodiment, which includes a polymerization step of obtaining a BDI polymer (an isocyanurate derivative of BDI and a uretdione derivative of BDI) by carrying out an isocyanurate reaction to form an isocyanurate group and a uretdione reaction to form a uretdione group.

[0052] The isocyanuration reaction may be carried out in the presence of, for example, a commonly known isocyanuration catalyst. Examples of the isocyanuration catalyst include quaternary onium salts, metal carboxylates, and aminosilyl group-containing compounds. The isocyanuration catalyst may be used alone or in combination of two or more.

[0053] As the isocyanurate catalyst, from the viewpoint of suppressing the production of high molecular weight substances, it is preferable to use an aminosilyl group-containing compound such as aminosilane or silyl urea, it is more preferable to use a disilazane such as hexamethyldisilazane or heptamethyldisilazane, and it is even more preferable to use hexamethyldisilazane.

[0054] The amount of the isocyanurate catalyst used is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the charged amount of BDI. The molar ratio (I / U) tends to increase as the amount of the isocyanurate catalyst used increases.

[0055] The reaction temperature of the isocyanurate reaction is preferably 80 to 180° C., and more preferably 100 to 160° C. When the reaction temperature of the isocyanurate reaction is 80° C. or higher, the reaction time can be shortened, and coloration of the polyisocyanate composition can be further suppressed. In addition, when the reaction temperature of the isocyanurate reaction is 80 to 180° C., it is easy to adjust the molar ratio (I / U) to 20 / 80 to 80 / 20.

[0056] The isocyanurate reaction may be terminated by adding a reaction terminator when the target isocyanate group content and molecular weight are reached. When the reaction temperature of the isocyanurate reaction is 80 to 180° C., the reaction time of the isocyanurate reaction is, for example, 1 to 5 hours.

[0057] The reaction terminator is a compound that has the effect of deactivating the catalyst. For example, water, a compound having a hydroxyl group, etc. can be used as the reaction terminator. The reaction terminator is preferably an alcohol. The reaction terminator can be used alone or in combination of two or more. It is preferable to add the reaction terminator promptly after the target isocyanate group content and molecular weight are reached.

[0058] The amount of the reaction terminator added varies depending on the type of reaction terminator and the type of isocyanurate catalyst used, but is preferably 0.1 to 3.5 equivalents relative to 1 equivalent of the isocyanurate catalyst, and particularly preferably 0.8 to 2.5 equivalents. When the amount of the reaction terminator used is 0.1 equivalent or more relative to 1 equivalent of the isocyanurate catalyst, the storage stability of the resulting polyisocyanate composition is further improved. When the amount of the reaction terminator used is 3.5 equivalents or less relative to 1 equivalent of the isocyanurate catalyst, the generation of a reaction product between the reaction terminator and BDI can be suppressed, so that the decrease in the isocyanate group content can be suppressed to a higher degree.

[0059] The uretdione reaction may be carried out in the presence of a generally known uretdione catalyst, for example, a tertiary phosphine such as trialkylphosphine or tribenzylphosphine, or a Lewis acid such as boron trifluoride or zinc trichloride.

[0060] When a uretdione-forming catalyst is used, the uretdione-forming reaction may be terminated by adding phosphoric acid, methyl paratoluenesulfonate, or the like, when the molar ratio (I / U) reaches a desired ratio.

[0061] The uretdione reaction can also be carried out by heating the reactants (e.g., BDI monomer) without using a uretdione catalyst as described above. From the viewpoint of suppressing the production of by-products, it is preferable to carry out the uretdione reaction only by heating without using a uretdione reaction catalyst. The heating temperature is preferably 80°C or higher, more preferably 100 to 170°C, and even more preferably 110 to 160°C. When the heating temperature is 80 to 170°C, it is easy to adjust the molar ratio (I / U) to 20 / 80 to 80 / 20 while suppressing the production of by-products.

[0062] The isocyanurate formation reaction and the uretdione formation reaction may be carried out under an inert gas atmosphere such as nitrogen, argon, etc. Specifically, BDI may be introduced into a reaction vessel, and an inert gas such as nitrogen, argon, etc. may be introduced into the vessel to make the reaction atmosphere an inert gas atmosphere, and then the isocyanurate formation reaction and the uretdione formation reaction may be carried out by the above-mentioned method.

[0063] The isocyanurate reaction and the uretdione reaction may be carried out in the absence of an organic solvent or in the presence of an organic solvent. When the reaction is carried out in the presence of an organic solvent, it is preferable to use an organic solvent that does not affect the reaction and has a boiling point equal to or higher than the reaction temperature. Examples of the organic solvent include aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, ketones such as methyl isobutyl ketone and cyclohexanone, esters such as butyl acetate and isobutyl acetate, glycol ether esters such as ethylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, and ethyl-3-ethoxypropionate, ethers such as dioxane, halogenated hydrocarbons such as methylene iodide and monochlorobenzene, polar aprotic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, and hexamethylphosphonylamide. The organic solvent may be used alone or in combination of two or more.

[0064] The isocyanurate formation reaction and the uretdione formation reaction can be carried out sequentially or in parallel. When the isocyanurate formation reaction and the uretdione formation reaction are carried out in parallel, the timing of the reaction start and the reaction termination can be simultaneous or different. For example, the uretdione formation reaction of BDI can be started to advance the uretdione formation of BDI, and then the uretdione formation reaction and the isocyanurate reaction can be carried out on a reactant containing a uretdione body of BDI. In the polymerization step, the isocyanurate formation reaction and the uretdione formation reaction are preferably carried out simultaneously. In the polymerization step, the isocyanurate formation reaction and the termination reaction are more preferably carried out after the uretdione formation reaction by heat (after the start of the reaction). If a uretdione conversion reaction is carried out by heat after the termination reaction of the isocyanurate conversion reaction, a side reaction between a catalyst decomposition product produced as a by-product during the termination reaction and isocyanate is promoted, which may result in viscosity increase, a decrease in the isocyanate group content, etc., and therefore it is preferable not to carry out a uretdione conversion reaction after the termination reaction of the isocyanurate conversion reaction.

[0065] More specifically, the polymerization step is preferably a step including a first heating step in which a reactant containing BDI (BDI monomer) is heated to 80° C. or higher, and a second heating step in which the reactant that has been subjected to the first heating step is heated at 80 to 180° C. in the presence of the isocyanurate catalyst. In this method, at least the uretdione reaction of BDI proceeds in the first heating step, and the isocyanurate reaction of a reactant containing a uretdione form of BDI (for example, a mixture of unreacted BDI monomer and a uretdione form of BDI) proceeds in the second heating step. The heating conditions of the first heating step are the same as the preferred range of the heating temperature of the uretdione reaction described above, and the heating conditions of the second heating step are the same as the preferred range of the reaction temperature of the isocyanurate reaction described above. In the second heating step, the uretdione reaction may proceed simultaneously with the isocyanurate reaction.

[0066] From the viewpoint of increasing the amount of uretdione, the first heating step may be a step of heating the reaction mixture to 80° C. or higher and then holding the reaction mixture at a temperature of 80° C. or higher. The holding temperature is the same as the preferred range of the heating temperature for the uretdione formation reaction. The holding time is preferably 1 to 6 hours, more preferably 2 to 5 hours.

[0067] After the reaction is completed, unreacted BDI monomer (free BDI) may be removed from the reaction solution containing the reaction product. That is, the method for producing a BDI derivative may further include a BDI removal step of removing free BDI after the polymerization step. In order to remove free BDI, for example, a removal method by thin film distillation at 90 to 130°C under a high vacuum of 10 to 100 Pa, an extraction method using an organic solvent, etc. are used. The above removal is preferably performed so that the residual content of free BDI present in the reaction solution is 5% by mass or less. If the residual content of free BDI is 5% by mass or less, the generation of odor can be further suppressed and the decrease in storage stability can be further suppressed. When an organic solvent is used in the above reaction, the organic solvent can be removed simultaneously with the removal of the free BDI.

[0068] The method for producing a BDI derivative may further include a step of blocking the BDI derivative with the above-mentioned blocking agent after the multimerization step or the BDI removal step.

[0069] The BDI derivative (or the reaction solution containing the BDI derivative) obtained by the above method can be used as a polyisocyanate composition as it is or after mixing with the other components described above. The polyurethane resin-forming composition according to one embodiment of the present disclosure can be obtained by blending the polyisocyanate composition obtained in this manner with a polyol.

[0070] <Polyurethane resin-forming composition> A polyurethane resin-forming composition according to one aspect of the present disclosure includes the polyisocyanate composition of the above embodiment and a polyol. The composition has a polyurethane resin-forming property, and the polyurethane resin is formed as a reaction product of the polyisocyanate and the polyol by reacting the polyisocyanate (e.g., a BDI derivative) and the polyol in the composition.

[0071] The polyol is a compound having two or more hydroxyl groups, which are active hydrogen groups, as reactive groups with isocyanate groups. The polyol is not particularly limited, but polyester polyol, polyether polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, silicone polyol, castor oil polyol, fluorine polyol, ester exchange product of two or more polyols, hydroxyl group-terminated prepolymers that have been subjected to urethane reaction with polyisocyanate, etc. can be suitably used. The polyol can be used alone or in combination of two or more.

[0072] (Polyester polyol) Examples of polyester polyols include those obtained by a condensation polymerization reaction between one or more dicarboxylic acids or anhydrides thereof and one or more low molecular weight polyols having a molecular weight of not more than 500. Examples of dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,β-diethylsuccinic acid, maleic acid, and fumaric acid. Examples of low molecular weight polyols having a molecular weight of 500 or less include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer diol, bisphenol A, ethylene oxide or propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, and pentaerythritol. Also usable are lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester (so-called lactone) monomers such as ε-caprolactone, alkyl-substituted ε-caprolactone, δ-valerolactone, alkyl-substituted δ-valerolactone, etc. Furthermore, it is also possible to use polyester-amide polyols obtained by replacing a part of the low molecular weight polyol with a low molecular weight polyamine or low molecular weight amino alcohol such as hexamethylenediamine, isophoronediamine, monoethanolamine, etc.

[0073] (Polyether polyol) Examples of polyether polyols include polyether polyols obtained by addition polymerization of alkylene oxides using compounds having two or more, preferably two to three, active hydrogen groups, such as low molecular weight polyols and low molecular weight polyamines, as initiators. Examples of low molecular weight polyols include the same compounds exemplified as the low molecular weight polyols having a molecular weight of 500 or less. Examples of low molecular weight polyamines include ethylene diamine, propylene diamine, toluene diamine, metaphenylene diamine, diphenylmethane diamine, xylylene diamine, etc. Examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, etc. In addition, polyether polyols obtained by ring-opening polymerization of alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether, and cyclic ether monomers such as tetrahydrofuran can also be used.

[0074] (Polycarbonate polyol) Examples of polycarbonate polyols include those obtained by a dealcoholization reaction or a dephenolation reaction between one or more low molecular weight polyols and diaryl carbonates. Examples of low molecular weight polyols include the same compounds as those exemplified as low molecular weight polyols having a molecular weight of 500 or less. Examples of diaryl carbonates include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, diindanyl carbonate, and tetrahydronaphthyl carbonate. In addition, examples of polycarbonate polyols include polyols obtained by ester exchange reaction between polycarbonate polyol, polyester polyol, and low molecular weight polyol.

[0075] (Polyolefin polyol) Examples of polyolefin polyols include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

[0076] (Acrylic polyol) Examples of acrylic polyols include those obtained by polymerizing or copolymerizing an acrylic ester and / or a methacrylic ester (hereinafter referred to as a (meth)acrylic ester), an acrylic acid hydroxy compound and / or a methacrylic acid hydroxy compound (hereinafter referred to as a (meth)acrylic acid hydroxy compound), and a polymerization initiator using light energy such as ultraviolet light or an electron beam, or heat energy.

[0077] [(Meth)acrylic acid ester] Examples of (meth)acrylic acid esters include alkyl esters having 1 to 20 carbon atoms. Examples of such (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate; esters of (meth)acrylic acid with alicyclic alcohols such as cyclohexyl (meth)acrylate; and (meth)acrylic acid aryl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate. The (meth)acrylic acid esters can be used alone or in combination of two or more.

[0078] [(Meth)acrylic acid hydroxy compound] The (meth)acrylic acid hydroxy compound has at least one hydroxyl group in the molecule that can be a reaction site with polyisocyanate. Examples of the (meth)acrylic acid hydroxy compound include acrylic acid hydroxy compounds such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, and pentaerythritol triacrylate. In addition, methacrylic acid hydroxy compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, and pentaerythritol trimethacrylate can also be used. The (meth)acrylic acid hydroxy compound can be used alone or in combination of two or more.

[0079] (Silicone polyol) Examples of silicone polyols include vinyl group-containing silicone compounds obtained by polymerizing γ-methacryloxypropyltrimethoxysilane, and polysiloxanes having at least one terminal hydroxyl group in the molecule, such as α,ω-dihydroxypolydimethylsiloxane and α,ω-dihydroxypolydiphenylsiloxane.

[0080] (Castor oil-based polyol) Examples of castor oil-based polyols include linear or branched polyester polyols obtained by reacting castor oil fatty acids with polyols. In addition, dehydrated castor oil, partially dehydrated castor oil, and hydrogenated castor oil can also be used.

[0081] (Fluorine-based polyol) The fluorine-based polyol may be, for example, a linear or branched polyol obtained by copolymerization of a fluorine-containing monomer and a monomer having a hydroxyl group as essential components. Here, the fluorine-containing monomer is preferably a fluoroolefin. Examples of the fluorine-containing monomer include tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyltrifluoroethylene, etc. In addition, examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and cyclohexanediol monovinyl ether, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, hydroxyl group-containing vinyl carboxylates such as hydroxyalkyl vinyl crotonates, and hydroxyl group-containing allyl esters.

[0082] The number of active hydrogen groups (average number of functional groups) in one molecule of the polyol is preferably 1.9 to 6.0. If the number of active hydrogen groups is within the above range, the resulting coating film tends to exhibit superior hardness.

[0083] The number average molecular weight of the polyol is preferably in the range of 750 to 50,000. When the number average molecular weight of the polyol is equal to or more than the lower limit, the adhesion tends to be further improved. When the number average molecular weight of the polyol is equal to or less than the upper limit, the solubility in low polarity organic solvents tends to be further improved, and the adhesion tends to be further improved.

[0084] In the polyurethane resin forming composition, the content ratio of the polyisocyanate composition and the polyol is not particularly limited, but the molar ratio R (isocyanate group / hydroxyl group) of the isocyanate group in the polyisocyanate composition and the hydroxyl group in the polyol is preferably 0.5 to 2.5. When the molar ratio R is equal to or greater than the lower limit, the hydroxyl group does not become too excessive, so that the adhesion tends to be further improved, and the decrease in crosslink density is suppressed, so that the durability and mechanical strength of the coating film tend to be further improved. When the molar ratio R is equal to or less than the upper limit, the isocyanate group does not become too excessive, so that the reaction with moisture in the air is suppressed, so that the swelling of the coating film is further reduced, and the associated decrease in adhesion tends to be further suppressed.

[0085] The polyurethane resin-forming composition may be a one-liquid type composition in which all of the constituent components are contained in one liquid, or a multi-liquid type composition in which the constituent components are present separately in multiple liquids. The multi-liquid type composition may, for example, comprise a first liquid (base agent) containing a polyol and a second liquid (curing agent) consisting of a polyisocyanate composition.

[0086] The polyurethane resin forming composition may contain a dilution solvent. When the polyurethane resin forming composition is a multi-liquid type, the dilution solvent may be contained in either the first liquid or the second liquid, or may be contained in both. The dilution solvent is, for example, an organic solvent. Examples of the dilution solvent include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, esters such as ethyl acetate, butyl acetate, and cellosolve acetate, alcohols such as butanol and isopropyl alcohol, and hydrocarbons such as toluene, xylene, cyclohexane, mineral spirits, and naphtha. The dilution solvent can be appropriately selected and used depending on the purpose and application. The dilution solvent can be used alone or in combination of two or more.

[0087] The polyurethane resin forming composition may contain a urethanization catalyst. As the urethanization catalyst, a known urethanization catalyst can be used appropriately in consideration of pot life, curing conditions, working conditions, etc. Specific examples of the urethanization catalyst include organometallic compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate, and organic amines such as triethylenediamine and triethylamine or salts thereof. The urethanization catalyst can be used alone or in combination of two or more.

[0088] The polyurethane resin-forming composition may contain, as necessary, additives such as antioxidants such as 2,6-di-tert-butyl-4-methylphenol, ultraviolet absorbers, pigments, dyes, solvents, flame retardants, hydrolysis inhibitors, lubricants, plasticizers, fillers, antistatic agents, dispersants, catalysts, storage stabilizers, surfactants, leveling agents, etc. When the polyurethane resin-forming composition is a multi-liquid type, these additives may be contained in either the first liquid or the second liquid, or in both.

[0089] The polyurethane resin-forming composition can be suitably used as a coating composition.

[0090] <Paint composition and coating> A coating composition according to one aspect of the present disclosure includes the polyisocyanate composition of the above embodiment and a compound having two or more isocyanate-reactive groups (hereinafter, referred to as an isocyanate-reactive compound). A coating film according to one aspect of the present disclosure includes a cured product of the coating composition described above.

[0091] The isocyanate-reactive compound may be a polyol. That is, the coating composition may contain the polyurethane resin-forming composition of the above embodiment. The isocyanate-reactive compound may be a polyamine, an amino alcohol, or the like, as long as it has two or more isocyanate-reactive groups (e.g., active hydrogen groups).

[0092] The coating film has high hardness because the coating composition contains the polyisocyanate composition of the above embodiment. The Martens hardness of the coating film at 23° C. is preferably 100 N / mm 2 More preferably, 104N / mm 2 More preferably, 110N / mm 2 The Martens hardness can be measured in accordance with JIS Z2255.

[0093] The coating film can be formed by applying the coating composition onto the surface of the adherend by a known method such as spraying, brushing, dipping, or using a coater, and then curing the composition.

[0094] The adherend is not particularly limited, and examples thereof include stainless steel, phosphate-treated steel, galvanized steel, iron, copper, aluminum, brass, glass, slate, acrylic resin, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenol resin, melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, and SEBS resin. Adherends made of such materials, polyethylene and polypropylene that have been subjected to corona discharge treatment or other surface treatment, and adherends having a coating layer formed on the surface of the adherend that can be an intermediate layer, can be used.

[0095] The curing conditions for the coating composition are not particularly limited, but preferably the curing temperature is −5 to 150° C., the humidity is 10 to 95% RH, and the curing time is 0.5 to 336 hours.

[0096] The coating film formed on the surface layer of the adherend has excellent recoatability and durability, so it is sufficient to form a coating film of at least 10 micrometers on the adherend. If the coating film is 10 micrometers or more, durability is improved and the occurrence of breakage of the coating film due to impact can be further suppressed. EXAMPLES

[0097] The contents of the present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to the following examples.

[0098] <Example 1> (Preparation of Polyisocyanate Composition) A 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube was charged with 800 g of BDI (butane diisocyanate, NCO content: 60.0% by mass), heated to 100°C, added with 9.6 g of hexamethyldisilazane as an isocyanurate catalyst, heated to 140°C, and stirred for 2.6 hours. The temperature was then lowered to 50°C in a water bath, and 6.0 g of ethanol as a reaction terminator was added, and the termination reaction was carried out at 50°C for 0.5 hours. After cooling the reaction solution, the excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04 kPa) to obtain 179 g of polyisocyanate composition P-1 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-1 are shown in Table 1. In this example, the properties of the polyisocyanate composition were measured by the following method.

[0099] (Measurement of molar ratio (I / U)) The respective contents (unit: mol%) of the isocyanurate group and the uretdione group in the BDI derivative, where the total of the isocyanurate group and the uretdione group in the BDI derivative is taken as 100 mol%, were measured using ECX400M (trade name) manufactured by JEOL Ltd. 1 The molar ratio of isocyanurate groups to uretdione groups (molar ratio (I / U)) was calculated from these contents.

[0100] Specifically, the polyisocyanate composition was first dissolved in deuterated chloroform containing 0.2 mass% of tetramethylsilane to prepare a measurement sample. The sample concentration was 0.02 g / 1 mL mass%. The chemical shift reference was set to the signal of the hydrogen atom of tetramethylsilane at 0 ppm. 1 H-NMR measurement was performed to determine the signal areas of the hydrogen atoms of the methylene groups adjacent to the nitrogen atoms of the isocyanurate ring and uretdione ring, and the contents of the isocyanurate group and uretdione group were calculated according to the following formula. Isocyanurate group content (unit: mol%)=(signal area around 3.9 ppm / 6) / (signal area around 3.9 ppm / 6+signal area around 3.3 ppm / 4)×100 Uretdione group content (unit: mol%)=(signal area around 3.3 ppm / 4) / (signal area around 3.9 ppm / 6+signal area around 3.3 ppm / 4)×100

[0101] (Measurement of content of other BDI derivatives) The content of compounds derived from BDI monomers other than isocyanurate and uretdione (other BDI derivatives) can be calculated in the same manner as the molar ratio (I / U). 1 The content of other BDI derivatives was calculated by the following formula: Content of other BDI derivatives (unit: mol%) = (signal area around 6.5-8.5 ppm + signal area around 4.4 ppm-5.4 ppm) / (signal area around 3.9 ppm / 6 + signal area around 3.3 ppm / 4 + signal area around 6.5-8.5 ppm + signal area around 4.4 ppm-5.4 ppm) x 100

[0102] (Measurement of BDI trimer and BDI dimer content) The sum of the contents of BDI trimer and BDI dimer (total content) was measured by GPC using the following apparatus. Equipment: HLC-8420 (Tosoh Corporation) Column: TSKgel (Tosoh Corporation) G3000H-XL, G2000H-XL, G1000H-XL, one of each connected in series Carrier: Tetrahydrofuran Detection method: Differential refractive index detector The refractive index peak of the BDI trimer appears at a retention time of about 23.8 minutes, and the refractive index peak of the BDI dimer appears at a retention time of about 24.9 minutes. The areas of these peaks were determined, and the total contents of the BDI trimer and the BDI dimer were calculated according to the following formula. Total content of BDI trimer and BDI dimer (mass%)=(peak area at retention time 23.8 minutes+peak area at retention time 24.9 minutes) / total area of ​​all peaks×100

[0103] (Measurement of weight average molecular weight) The weight average molecular weight of the resulting polyisocyanate composition (BDI derivative) was measured using the above-mentioned GPC apparatus with polystyrene as the molecular weight standard.

[0104] (Measurement of NCO content) The NCO content of the polyisocyanate composition (BDI derivative) was determined by reacting the composition with a secondary amine and then back titrating the unreacted secondary amine with hydrochloric acid.

[0105] (Viscosity measurement) The viscosity of the obtained polyisocyanate composition (BDI derivative) was measured in a 25° C. environment using a rheometer (HAAKE MARS60, manufactured by Thermo Fisher Scientific).

[0106] <Example 2> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 150°C and stirred for 4 hours. Then, 8.0g of hexamethyldisilazane, an isocyanurate catalyst, was added, and the mixture was stirred for 3.6 hours. The temperature was then lowered to 50°C in a water bath, and 5.0g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, the excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 227g of polyisocyanate composition P-2 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-2 are shown in Table 1.

[0107] <Example 3> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 100°C, 8.0g of hexamethyldisilazane, an isocyanurate catalyst, was added, and the mixture was heated to 140°C and stirred for 3.0 hours. The mixture was then cooled to 50°C in a water bath, and 5.0g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, the excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 184g of polyisocyanate composition P-3 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-3 are shown in Table 1.

[0108] <Example 4> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 150°C and stirred for 3 hours. Then, 6.4g of hexamethyldisilazane, an isocyanurate catalyst, was added and stirred for 2.0 hours. The temperature was then lowered to 50°C in a water bath, 4.0g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 161g of polyisocyanate composition P-4 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-4 are shown in Table 1.

[0109] <Example 5> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 100°C, 3.2g of hexamethyldisilazane, an isocyanurate catalyst, was added, and the mixture was heated to 140°C and stirred for 4.0 hours. The mixture was then cooled to 50°C in a water bath, and 2.0g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, the excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 112g of polyisocyanate composition P-5 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-5 are shown in Table 1.

[0110] <Example 6> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and this was heated to 100°C, 1.6g of hexamethyldisilazane, which is an isocyanurate catalyst, was added, and the temperature was raised to 140°C and stirred for 5.0 hours. Then, the temperature was lowered to 50°C in a water bath, 1.0g of ethanol, which is a reaction terminator, was added, and the termination reaction was carried out at 50°C for 0.5 hours. After cooling the reaction solution, excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 88g of polyisocyanate composition P-6 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-6 are shown in Table 1.

[0111] <Example 7> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and this was heated to 100°C, 0.8g of hexamethyldisilazane, which is an isocyanurate catalyst, was added, and the temperature was raised to 140°C and stirred for 6.0 hours. Then, the temperature was lowered to 50°C in a water bath, 0.5g of ethanol, which is a reaction terminator, was added, and the termination reaction was carried out at 50°C for 0.5 hours. After cooling the reaction solution, excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 83g of polyisocyanate composition P-7 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-7 are shown in Table 1.

[0112] <Comparative Example 1> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and this was heated to 90°C, and 11.2g of N-trimethylsilyl-tertiary butylamine, an isocyanurate catalyst, was added, and the mixture was stirred for 3.5 hours. The temperature was then lowered to 50°C in a water bath, and 3.9g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 84g of polyisocyanate composition P-8 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-8 are shown in Table 1.

[0113] <Comparative Example 2> 800 g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 160°C and stirred for 1 hour. Then, 12.0 g of hexamethyldisilazane, an isocyanurate catalyst, was added, and the mixture was stirred for 5.6 hours. The temperature was then lowered to 50°C in a water bath, and 7.5 g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04 kPa) to obtain 339 g of polyisocyanate composition P-9 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-9 are shown in Table 1.

[0114] <Comparative Example 3> 800g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 160°C and stirred for 3 hours. The mixture was then cooled to 90°C, and 7.2g of N-trimethylsilyl-diethylamine, an isocyanurate catalyst, was added, and the mixture was stirred for 4.3 hours. The mixture was then cooled to 50°C in a water bath, and 2.5g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, the excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04kPa) to obtain 139g of polyisocyanate composition P-10 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-10 are shown in Table 1. Since P-10 contained precipitates, the viscosity was not measured. For the same reason, the compatibility with the base resin was poor, and therefore the Martens hardness and curing start temperature were not evaluated.

[0115] <Comparative Example 4> 800 g of BDI was charged into a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, and the mixture was heated to 140°C and stirred for 3 hours. Then, 0.8 g of hexamethyldisilazane, an isocyanurate catalyst, was added, and the mixture was stirred for 2.0 hours. The temperature was then lowered to 50°C in a water bath, and 0.5 g of ethanol, a reaction terminator, was added, and the reaction was stopped at 50°C for 0.5 hours. After cooling the reaction solution, excess BDI was removed by thin-film distillation (conditions: 110°C, 0.04 kPa), to obtain 60 g of polyisocyanate composition P-11 consisting of a BDI derivative. The properties of the obtained polyisocyanate composition P-11 are shown in Table 1.

[0116] <Comparative Example 5> In a 1-liter four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet tube, 800 g of HDI (1,6-hexane diisocyanate, NCO content: 49.9% by mass) was charged, heated to 140°C, and stirred for 2 hours. Then, 2.4 g of hexamethyldisilazane, an isocyanurate catalyst, was added, and stirred for 3.0 hours. Then, the temperature was lowered to 50°C in a water bath, 1.5 g of ethanol, a reaction terminator, was added, and the termination reaction was carried out at 50°C for 0.5 hours. After cooling the reaction solution, excess HDI was removed by thin-film distillation (conditions: 140°C, 0.04 kPa) to obtain 252 g of polyisocyanate composition P-12 consisting of HDI derivatives. The properties of the obtained polyisocyanate composition P-12 are shown in Table 1.

[0117] <Comparative Examples 6 and 7> In Comparative Examples 6 and 7, C-HXLV (manufactured by Tosoh Corporation) produced from HDI (1,6-hexane diisocyanate) and STABIO D-370 (manufactured by Mitsui Chemicals Inc.) produced from PDI (1,5-pentane diisocyanate) were used, respectively. The properties of each are shown in Table 1.

[0118] <Evaluation> (Quick-drying rating) A coating composition (two-liquid coating composition) consisting of the obtained polyisocyanate composition and acrylic polyol was prepared, and the curing initiation temperature of the coating composition was measured by a rigid pendulum test using RPT-3000W (trade name, manufactured by A&D Co., Ltd.) to evaluate the quick-drying property of the polyisocyanate composition. Specifically, first, an acrylic polyol (trade name: Acrydic A-801, hydroxyl value: 50 mg KOH / resin g, solid content: 50 mass%, manufactured by DIC Co., Ltd.) and a polyisocyanate composition were mixed so that the hydroxyl group and isocyanate group equivalent ratio was 1:1, and then the coating solid content was adjusted to 50 mass% with butyl acetate to obtain a coating composition. Next, the coating composition was applied to a steel plate (JIS G3141, trade name: SPCC-SB, manufactured by Paltec Co., Ltd.) so that the coating thickness was 20 μm. The steel plate was then heated at a temperature increase rate of 2.5° C. / min, and the temperature at which the period of the pendulum (frame: FRB-300, edge: RBE-160) began to decay was determined, and this temperature was taken as the curing start temperature of the coating film.

[0119] (Coating hardness evaluation) A coating composition (two-liquid coating composition) consisting of the obtained polyisocyanate composition and acrylic polyol was prepared, a coating film (cured film) was formed using the coating composition, and the Martens hardness of the cured film was measured. Specifically, first, an acrylic polyol (trade name: Dianale JR5689, hydroxyl value: 67 mg KOH / resin g, solid content: 61 mass%, manufactured by Mitsubishi Chemical Corporation) and a polyisocyanate composition were mixed so that the hydroxyl group and isocyanate group equivalent ratio was 1:1, and then the coating solid content was adjusted to 40 mass% with butyl acetate to obtain a coating composition. Next, the coating composition was applied to a steel plate (JIS G3141, trade name: SPCC-SB, processing method: PF-1077, manufactured by Paltec Co., Ltd.) so that the thickness of the coating film (uncured film) was 20 μm. The coating film was then dried for 1 hour under an environment of 23°C and 50% relative humidity, and the dried coating film was then heat-treated for 30 minutes in a dryer at 150°C. The heat-treated coating film was then aged for 7 days or more under an environment of 23°C and 50% relative humidity to obtain a coating film (cured film) containing a cured product of the coating composition. The Martens hardness of the obtained coating film (cured film) was measured using HM2000 (trade name, manufactured by Fisher Instruments) in accordance with JIS Z2255.

[0120] [Table 1]

[0121] (Evaluation Results) As shown in Table 1, the polyisocyanate compositions P-1 to P-7 have low viscosity, and the coating films thereof have good quick-drying properties and good hardness. In particular, the polyisocyanate compositions P-4 to P-6 have high viscosity, good hardness, and good quick-drying properties. The polyisocyanate compositions P-8 and P-9 have high viscosity and poor workability. The polyisocyanate composition P-10 has poor compatibility with the base resin, making it difficult to prepare a coating film. The polyisocyanate composition P-11 has low viscosity and good quick-drying properties, but the hardness of the coating film is insufficient. The polyisocyanate composition P-12 has low viscosity, but is poor in both quick-drying properties and hardness of the coating film. The polyisocyanate compositions P-13 and P-14 have insufficient quick-drying properties. From these facts, it can be said that the polyisocyanate compositions of Examples 1 to 7 have low viscosity, excellent workability and quick-drying properties, and the hardness of the coating film obtained is excellent.

Claims

1. A butane diisocyanate derivative which is a mixture of compounds derived from butane diisocyanate monomer, comprising two or more compounds selected from the group consisting of an isocyanurate compound having an isocyanurate group, a uretdione compound having a uretdione group, a biuret compound having a biuret group, and a urethane compound having a urethane group; The composition contains at least the isocyanurate and the uretdione, the molar ratio of the isocyanurate groups to the uretdione groups is 20 / 80 to 80 / 20; A butane diisocyanate derivative having a weight average molecular weight based on gel permeation chromatography of 790 g / mol or less.

2. Contains butane diisocyanate trimer and butane diisocyanate dimer, The butane diisocyanate derivative according to claim 1, wherein the total content of the butane diisocyanate trimer and the butane diisocyanate dimer is 45 to 95 mass% based on the total mass of the butane diisocyanate derivative.

3. 2. The butane diisocyanate derivative of claim 1, wherein the molar ratio of said isocyanurate groups to said uretdione groups is 50 / 50 or greater.

4. 2. The butane diisocyanate derivative of claim 1, wherein the molar ratio of said isocyanurate groups to said uretdione groups is 60 / 40 or less.

5. A method for producing the butane diisocyanate derivative according to any one of claims 1 to 4, A first heating step of heating a reaction mixture containing butane diisocyanate to 80° C. or higher; and a second heating step of heating the reaction product obtained in the first heating step at 80 to 180° C. in the presence of an isocyanurate catalyst.

6. The method for producing a butane diisocyanate derivative according to claim 5 , wherein the isocyanurate catalyst comprises an aminosilyl group-containing compound.

7. A polyisocyanate composition comprising the butane diisocyanate derivative of claim 1.

8. The composition contains at least an isocyanurate compound of butane diisocyanate having an isocyanurate group and a uretdione compound of butane diisocyanate having a uretdione group, the molar ratio of the isocyanurate groups to the uretdione groups is 20 / 80 to 80 / 20; A polyisocyanate composition having a weight average molecular weight based on gel permeation chromatography of 790 g / mol or less.

9. The polyisocyanate composition according to claim 7 or 8, having a viscosity at 25°C of 2500 mPa·s or less.

10. A polyurethane resin-forming composition comprising the polyisocyanate composition according to claim 7 or 8 and a polyol.

11. A coating composition comprising the polyisocyanate composition according to claim 7 or 8 and a compound having two or more isocyanate-reactive groups.

12. A coating film comprising a cured product of the coating composition according to claim 11.

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