Carbodiimide composition, curing agent composition, coating composition and cured resin

Abstract

The present invention provides a carbodiimide composition comprising a water-soluble modified polycarbodiimide (A) and a water-insoluble polycarbodiimide (B), a curing agent composition, a coating composition, and a cured resin using the same.

Description

Technical Field

[0001] The present invention relates to a carbodiimide composition, a curing agent composition, a coating composition and a cured resin. Background Art

[0002] The coating process in automobile manufacturing is said to account for about one-third of energy consumption. From the perspective of environmental protection and reducing manufacturing costs, there is a push to reduce the temperature of coating firing and the number of coating processes. In particular, the carboxylic acid (or carboxyl group) contained in the main agent can reduce the water resistance of the coating, so it is required to consume the carboxylic acid during coating firing. In addition, as the temperature of coating firing decreases, the carboxylic acid consumption reaction is required to occur in a low-temperature environment. On the other hand, the coating composition also needs to have storage stability under the storage environment. As a candidate compound that meets these conditions, carbodiimide compounds have attracted attention.

[0003] Patent Document 1 discloses a carbodiimide-based crosslinking agent in which the terminal isocyanate groups are capped with hydrophilic groups containing polyoxyethylene repeating units. It is stated that this carbodiimide-based crosslinking agent has excellent water solubility or water dispersibility. Furthermore, Patent Document 2 discloses a carbodiimide-based waterborne resin crosslinking agent in which two specific polycarbodiimides are present in a specific ratio in an aqueous medium. It is stated that this carbodiimide-based waterborne resin crosslinking agent can crosslink a waterborne resin even when it coexists with the waterborne resin for a long period of time.

[0004] On the other hand, as the attempt of improving the storage stability of carbodiimide group, made carbodiimide and can react with the reactive group of carbodiimide reaction and converted into the attempt that has reduced the reactive functional group with carboxylic acid.For example, a kind of resin crosslinking agent that carbodiimide group is formed by amine modification is pointed out in patent documentation 3.In addition, a kind of resin curing agent with uretonimine group that carbodiimide group is utilized to be modified by isocyanate group is pointed out in patent documentation 4.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 10-316930

[0008] Patent Document 2: Japanese Patent No. 6255114

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2013-112755

[0010] Patent Document 4: International Publication No. 2019 / 221173 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] However, the carbodiimide-based water-based resin crosslinking agents described in Patent Documents 1 and 2 contain carbodiimide groups that react with carboxylic acids in the water-based resin. Therefore, thickening or gelation is observed during long-term storage after mixing with the water-based resin, and storage stability still needs to be improved.

[0013] Furthermore, the modified carbodiimide-based water-based resin crosslinkers described in Patent Documents 3 and 4 have excellent storage stability. However, the reactivity of the modified resin crosslinkers significantly decreases at low temperatures of around 80°C, and the modifiers dissociate only at high temperatures of 100°C or higher. Therefore, there is room for improvement in low-temperature curing properties.

[0014] The present invention has been made in view of the above circumstances and aims to provide a carbodiimide composition having excellent storage stability and low-temperature curability after being prepared as a coating composition, as well as a curing agent composition, a coating composition, and a cured resin using the carbodiimide composition.

[0015] Means for solving problems

[0016] That is, the present invention includes the following aspects.

[0017] (1) A carbodiimide composition comprising a water-soluble modified polycarbodiimide (A) and a water-insoluble polycarbodiimide (B).

[0018] (2) The carbodiimide composition according to (1), wherein the modification rate of the water-soluble modified polycarbodiimide (A) is 5% or more and 100% or less.

[0019] (3) The carbodiimide composition according to (1) or (2), wherein the average number of carbodiimide groups per molecule of the water-soluble modified polycarbodiimide (A) is 4.0 or less.

[0020] (4) The carbodiimide composition according to any one of (1) to (3), wherein the mass ratio (A) / (B) of the water-soluble modified polycarbodiimide (A) to the water-insoluble polycarbodiimide (B) is 90 / 10 or less.

[0021] (5) The carbodiimide composition according to any one of (1) to (4), wherein the modification rate of the water-insoluble polycarbodiimide (B) is 70% or less.

[0022] (6) The carbodiimide composition according to any one of (1) to (5), wherein the modification rate of the water-insoluble polycarbodiimide (B) is lower than the modification rate of the water-soluble modified polycarbodiimide (A).

[0023] (7) The carbodiimide composition according to any one of (1) to (6), wherein the average number of carbodiimide groups per molecule of the water-insoluble polycarbodiimide (B) is greater than the average number of carbodiimide groups per molecule of the modified polycarbodiimide (A).

[0024] (8) The carbodiimide composition according to any one of (1) to (7), wherein the isocyanate of the water-soluble modified polycarbodiimide (A) is blocked with a polyalkylene glycol monoalkyl ether and / or an alkylene glycol monoalkyl ether.

[0025] (9) The carbodiimide composition according to any one of (1) to (8), wherein the molar ratio of the isocyanate-terminated polyalkylene glycol monoalkyl ether and the alkylene glycol monoalkyl ether of the water-soluble modified polycarbodiimide (A) is 20 / 80 or more.

[0026] (10) A carbodiimide composition as described in any one of (1) to (9), wherein the modifier of the water-soluble modified polycarbodiimide (A) or the water-insoluble polycarbodiimide (B) comprises at least one selected from the group consisting of isocyanates, hydroxyl-containing compounds, mercapto-containing compounds, non-cyclic amines, cyclic amines, carboxylic acids, and carboxylic acid derivatives.

[0027] (11) The carbodiimide composition according to (10), wherein the skeleton of the modifier contains at least one electron-withdrawing functional group.

[0028] (12) A carbodiimide composition as described in (10) or (11), wherein any one of a cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, a non-cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, an unsaturated hydrocarbon group having 2 to 8 carbon atoms, and a halogen atom is bonded to the skeleton of the above-mentioned modifier.

[0029] (13) The carbodiimide composition according to any one of (10) to (12), wherein any one of a hydroxyl group, an amino group, an ether group, and a carbonyl group is bonded to the skeleton of the modifier.

[0030] (14) The carbodiimide composition according to any one of (10) to (13), wherein the modifier of the water-soluble polycarbodiimide (A) or the water-insoluble polycarbodiimide (B) comprises at least one hydroxyl-containing compound having a pKa in water of 7 or more and 16 or less.

[0031] (15) A carbodiimide composition as described in any one of (1) to (14), wherein the modifier of the water-soluble polycarbodiimide (A) or the water-insoluble polycarbodiimide (B) contains at least one carboxylic acid compound having a pKa of 4.8 or less in water.

[0032] (16) A curing agent composition comprising the carbodiimide composition according to any one of (1) to (15) and water.

[0033] (17) The curing agent composition according to (16), further comprising a surfactant.

[0034] (18) A coating composition comprising the curing agent composition according to (16) or (17) and a compound having a carboxyl group.

[0035] (19) A resin cured product obtained by curing the coating composition described in (18).

[0036] Effects of the Invention

[0037] According to the carbodiimide composition of the above embodiment, a carbodiimide composition having excellent storage stability and low-temperature curing properties after being prepared as a coating composition can be provided. The curing agent composition of the above embodiment comprises the carbodiimide composition, and has excellent storage stability and low-temperature curing properties after being prepared as a coating composition. The coating composition of the above embodiment comprises the curing agent composition, and has excellent storage stability and low-temperature curing properties. The resin cured product of the above embodiment is formed by curing the coating composition, and has excellent water resistance (structure retention, whitening resistance) (hereinafter sometimes referred to as "water resistance"). DETAILED DESCRIPTION

[0038] The following is a detailed description of a specific embodiment of the present invention (hereinafter referred to as "this embodiment"). The following embodiment is an example for illustrating the present invention and does not limit the present invention to the following embodiment. The present invention can be implemented by appropriately deforming within the scope of its main points.

[0039] Carbodiimide Compositions

[0040] The carbodiimide composition of the present embodiment contains a water-soluble modified polycarbodiimide (A) and a water-insoluble polycarbodiimide (B).

[0041] It is speculated that in the carbodiimide composition of this embodiment, an association structure (association body) is formed in water in which the water-soluble modified polycarbodiimide (A) covers the water-insoluble polycarbodiimide (B). In this case, in the association structure, the carbodiimide groups of the water-soluble modified polycarbodiimide (A) present on the outside are modified, thereby becoming less reactive, and the highly reactive water-insoluble polycarbodiimide (B) is present on the inside of the association structure. Therefore, even when stored as a coating composition mixed with a main component, the carbodiimide groups do not react with the reactive groups in the main component that can react with carbodiimide groups, and can be stored in a stable state. On the other hand, when the coating composition is cured at a low temperature of approximately 80°C, the association structure is destroyed by heating, thereby exposing the highly reactive unmodified carbodiimide groups, which can react with the reactive groups of the main component. Furthermore, a sufficient cross-linked structure can be formed thereby, and the water resistance of the obtained coating film can be improved.

[0042] The water solubility of the water-soluble modified polycarbodiimide (A) refers to the property of being dispersed in water without forming aggregates. On the other hand, the water-insoluble polycarbodiimide (B) refers to the property of being dispersed in water without forming aggregates. By mixing the water-soluble modified polycarbodiimide (A) and the water-insoluble polycarbodiimide (B) at a specific mass ratio, an association can be formed in water in which the water-soluble modified polycarbodiimide (A) covers the water-insoluble polycarbodiimide (B).

[0043] As an indicator of water solubility and water insolubility, the solubility relative to 100g of water can be expressed. In this application, a water-soluble substance means a substance with a solubility of 10g or more relative to 100g of water, and a water-insoluble substance means a substance with a solubility of less than 10g relative to 100g of water.

[0044] The solubility of the water-soluble modified polycarbodiimide (A) in 100 g of water is preferably 10 g or more, more preferably 30 g or more, further preferably 40 g or more, and particularly preferably more than 40 g.

[0045] The solubility of the water-insoluble polycarbodiimide (B) in 100 g of water is preferably less than 10 g, more preferably less than 5 g, and even more preferably less than 1 g.

[0046] The solubility of the water-soluble modified polycarbodiimide (A) and the water-insoluble polycarbodiimide (B) in 100 g of water can be measured, for example, by the method described in the Examples below.

[0047] In the carbodiimide composition of this embodiment, by appropriately adjusting the modification rate of the water-soluble modified polycarbodiimide (A), the reactivity with the carboxylic acid (carboxyl group) derived from the main component can be adjusted, thereby further improving the storage stability of the coating composition after preparation. Specifically, by increasing the modification rate of the water-soluble modified polycarbodiimide (A), the reactivity of the water-soluble modified polycarbodiimide (A) with the compound having a carboxyl group as the main component can be reduced. On the other hand, by reducing the modification rate, the reactivity of the water-soluble modified polycarbodiimide (A) with the compound having a carboxyl group can be increased.

[0048] More specifically, the lower limit of the modification rate of the water-soluble modified polycarbodiimide (A) is preferably 5% or more, more preferably 50% or more, further preferably 60% or more, and further preferably 70% or more. By setting the modification rate within the above lower limit, the storage stability of the coating composition after preparation can be improved. On the other hand, from the perspective of curing performance when prepared as a curing agent composition, the upper limit of the modification rate is preferably 100% or less, more preferably 95% or less, further preferably 90% or less, and further preferably 85% or less. In addition, from the perspective of preventing unreacted water-soluble modified polycarbodiimide (A) from eluting from the curing agent composition, the modification rate is preferably not 100%, more preferably 95% or less, further preferably 90% or less, and further preferably 85% or less.

[0049] The modification rate of the water-soluble modified polycarbodiimide (A) represents the ratio of carbodiimide functional groups in the pre-modified polycarbodiimide that have been converted to functional groups having reduced reactivity with carboxylic acids, and can be calculated, for example, using the following method. It should be noted that the modification rate can be determined by any analytical method that can quantify the carbodiimide functional groups, including spectroscopic methods such as NMR, titration, and elemental analysis.

[0050] First, the water-soluble polycarbodiimide before and after modification was measured by infrared absorption spectrum to determine the concentration of the carbodiimide group at a wavelength of 2150 cm -1 Next, the modification rate can be calculated based on the obtained integral value according to the following formula. Specifically, it can be calculated using the method shown in the examples below.

[0051] Modification rate (%) = (modified water-soluble polycarbodiimide at a wavelength of 2150 cm -1 The integral value of the absorption peak near the wavelength of 2150cm) / (the integral value of the absorption peak near the wavelength of 2150cm) of the water-soluble polycarbodiimide before modification -1 The integral value of the absorption peak near

[0052] In the carbodiimide composition of the present embodiment, by appropriately adjusting the mass ratio (A) / (B) of the water-soluble modified polycarbodiimide (A) to the water-insoluble polycarbodiimide (B), the reactivity of the carbodiimide composition as a curing agent component with the carboxylic acid (carboxyl group) derived from the main component in a coating composition containing the carbodiimide composition of the present embodiment can be adjusted, thereby better maintaining a balance between storage stability and low-temperature curability after the coating composition is prepared. Specifically, by increasing the mass ratio (A) / (B), that is, increasing the proportion of the water-soluble modified polycarbodiimide (A), the reactivity with the compound having a carboxyl group as the main component in water can be reduced, thereby further improving storage stability. On the other hand, by reducing the mass ratio (A) / (B), that is, increasing the proportion of the water-insoluble polycarbodiimide (B), the reactivity with the compound having a carboxyl group as the main component during heat curing can be further improved, thereby further improving the low-temperature curability of the coating composition. More specifically, the upper limit of the mass ratio (A) / (B) of the water-soluble modified polycarbodiimide (A) relative to the water-insoluble polycarbodiimide (B) is preferably 90 / 10 or less, more preferably 80 / 20 or less, and even more preferably 70 / 30 or less. By setting the mass ratio (A) / (B) to be below the above upper limit, the low-temperature curing property after being prepared into a coating composition can be made more excellent. On the other hand, the lower limit is preferably 10 / 90 or more, more preferably 20 / 80 or more, and even more preferably 30 / 70 or more. By setting the mass ratio (A) / (B) to be above the above lower limit, the storage stability after being prepared into a coating composition can be made even better. In particular, from the perspective of balancing the storage stability and low-temperature curing property after being prepared into a coating composition, the mass ratio (A) / (B) is more preferably 10 / 90 or more and 90 / 10 or less, even more preferably 20 / 80 or more and 80 / 20 or less, and particularly preferably 30 / 70 or more and 70 / 30 or less. By setting the mass ratio (A) / (B) within the above range, it is possible to better maintain a balance between storage stability and low-temperature curability after preparing the coating composition.

[0053] The mass ratio (A) / (B) can be calculated, for example, based on the masses of the water-soluble modified polycarbodiimide (A) and the water-insoluble polycarbodiimide (B) contained in the carbodiimide composition.

[0054] Furthermore, by appropriately adjusting the difference between the average number of carbodiimide groups per molecule of the water-soluble modified polycarbodiimide (A) and the average number of carbodiimide groups per molecule of the water-insoluble polycarbodiimide (B) after the carbodiimide composition is prepared, the crosslinked structure after the reaction with the carboxylic acid (carboxyl) group derived from the main component can be adjusted. From the perspectives of storage stability and curability of the coating composition after preparation, and gel fraction, water resistance, and appearance of the cured resin after preparation, the average number of carbodiimide groups per molecule of the water-insoluble polycarbodiimide (B) is preferably greater than the average number of carbodiimide groups per molecule of the hydrophilic modified polycarbodiimide (A). The average number of carbodiimide groups per molecule of the polycarbodiimide (B) is preferably greater than the average number of carbodiimide groups per molecule of the hydrophilic modified polycarbodiimide (A) by one or more, more preferably greater than the average number of carbodiimide groups per molecule of the polycarbodiimide (B) by two or more, and particularly preferably greater than the average number of carbodiimide groups per molecule of the polycarbodiimide (B) by three or more. By setting the average number of carbodiimide groups within the above range, the storage stability and curability of the coating composition, which have conventionally been in a trade-off relationship, can be balanced, and a cured resin having excellent gel fraction, water resistance, and appearance can be obtained.

[0055] Next, the details of each component constituting the carbodiimide composition of this embodiment will be described.

[0056] <Water-soluble modified polycarbodiimide (A)>

[0057] The water-soluble modified polycarbodiimide (A) is not particularly limited, and similar to commonly known water-soluble modified polycarbodiimides, it is preferably a polycarbodiimide compound having a terminal structure composed of a hydrophilic group and at least a portion of the carbodiimide groups modified with a modifier.

[0058] In water-soluble modified polycarbodiimide (A), at least a portion of carbodiimide groups is converted (modified) into a functional group that has reduced the reactivity with the carboxylic acid (carboxyl) in the main agent component. As a functional group that has reduced the reactivity with the carboxylic acid (carboxyl) in the main agent component, uretonimine group, isourea group, thioisourea group, guanidine group, N-acylurea group, urea group, thiourea group, carboxyimide amide group etc. can be enumerated. In the functional group that has reduced reactivity, there is a balance between uretonimine group, isourea group, thioisourea group, guanidine group, carboxyimide amide group and carbodiimide, can generate carbodiimide groups by heating, can improve curability. In addition, the temperature required for the generation of carbodiimide groups is lower, can improve curability, thus preferably. From this aspect, preferably uretonimine group, isourea group, guanidine group, more preferably uretonimine group, isourea group, particularly preferably uretonimine group.

[0059] When these functional groups are present, excellent curability can be achieved even when the mass ratio (A) / (B) of the modified polycarbodiimide (A) to the water-insoluble polycarbodiimide (B) is high. Furthermore, excellent curability can be achieved even when the modification rate of the modified polycarbodiimide (A) is high.

[0060] On the other hand, among functional groups with reduced reactivity, N-acylurea groups, urea groups, and thiourea groups have a high effect of reducing reactivity with carboxylic acids because the balance between these groups and carbodiimides is non-existent or negligibly small. Therefore, the presence of these functional groups can achieve excellent storage stability.

[0061] The polycarbodiimide serving as a raw material of the water-soluble modified polycarbodiimide (A) is derived by subjecting an isocyanate compound to polycarbodiimidization in the presence of a carbodiimidization catalyst.

[0062] Examples of the isocyanate compound include diisocyanates and polyisocyanates derived from the diisocyanates. In addition to the diisocyanates, the isocyanate compound may also partially contain diisocyanates or higher valence isocyanates.

[0063] Examples of the diisocyanate include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate.

[0064] Examples of the aliphatic diisocyanate include 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, HDI, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, and lysine diisocyanate.

[0065] Examples of the alicyclic diisocyanate include IPDI, 4,4′-methylenebiscyclohexyl diisocyanate (hereinafter sometimes referred to as “hydrogenated MDI”), and dimethylcyclohexane diisocyanate (hereinafter sometimes referred to as “hydrogenated XDI”).

[0066] Examples of the aromatic diisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and mixtures thereof (hereinafter sometimes referred to as “TDIs”), diphenylmethane-4,4′-diisocyanate (hereinafter sometimes referred to as “MDI”), naphthalene-1,5-diisocyanate (hereinafter sometimes referred to as “NDI”), 3,3-dimethyl-4,4-diphenyl diisocyanate (hereinafter sometimes referred to as “TODI”), crude TDIs, polymethylene polyphenyl diisocyanate, crude MDI, phenylene diisocyanate, xylylene diisocyanate (hereinafter sometimes referred to as “XDI”), and tetramethylxylylene diisocyanate (hereinafter sometimes referred to as “TMXDI”).

[0067] Among these, as the diisocyanate, 1,5-pentamethylene diisocyanate, HDI, alicyclic diisocyanate, or aromatic diisocyanate is preferred, IPDI, hydrogenated MDI, MDI, or TMXDI is more preferred, and IPDI or hydrogenated MDI is particularly preferred.

[0068] Examples of the polyisocyanate include those having at least one functional group selected from the group consisting of an isocyanurate group, an allophanate group, a biuret group, a uretdione group, an iminooxadiazinedione group, and a carbamate group. Among these, the polyisocyanate is preferably a polyisocyanate having an isocyanurate group.

[0069] The number average molecular weight of the polycarbodiimide used as the raw material of the water-soluble modified polycarbodiimide (A), that is, the polycarbodiimide before the isocyanate groups are blocked, is preferably 300 to 6000, more preferably 400 to 5000, and even more preferably 600 to 4000. By setting the number average molecular weight within the above range, the dispersibility of the water-soluble modified polycarbodiimide (A) in water can be further improved, and the storage stability of the carbodiimide composition of this embodiment after being prepared as a coating composition can be further improved.

[0070] The number average molecular weight of the polycarbodiimide before the isocyanate groups are blocked can be measured, for example, by gel permeation chromatography (GPC). Specifically, it can be measured using the method described in the examples below.

[0071] The bonding form between the polycarbodiimide and the hydrophilic group at the end of the water-soluble modified polycarbodiimide (A) is not particularly limited, and examples thereof include a urethane bond, a urea bond, a carbodiimide group, and an amide bond.

[0072] The hydrophilic group is not particularly limited as long as it is a functional group that can impart water solubility to the polycarbodiimide. Examples thereof include ethylene oxide, propylene oxide, hydroxyl groups, sulfonic acid groups, quaternary ammonium groups, and phosphoric acid groups. Of these, ethylene oxide and propylene oxide are preferred. These hydrophilic groups may be present alone or in combination of two or more.

[0073] In addition, as long as the water solubility of the water-soluble modified polycarbodiimide (A) can be ensured, a portion of the terminal structure of the water-soluble modified polycarbodiimide (A) may also be composed of functional groups other than hydrophilic groups. Among them, from the perspective of compatibility of the water-soluble modified polycarbodiimide (A) with the coating containing a carboxyl group, the terminal structure of the water-soluble modified polycarbodiimide (A) is preferably end-capped with polyalkylene glycol monoalkyl ether and / or alkylene glycol monoalkyl ether, and more preferably end-capped with polyalkylene glycol monoalkyl ether and alkylene glycol monoalkyl ether. The molar ratio of polyalkylene glycol monoalkyl ether to alkylene glycol monoalkyl ether (polyalkylene glycol monoalkyl ether / alkylene glycol monoalkyl ether) is preferably 20 / 80 or more, more preferably 20 / 80 or more and less than 95 / 5, further preferably 20 / 80 or more and less than 85 / 15, and particularly preferably 20 / 80 or more and less than 75 / 25. By setting the molar ratio within the above range, the compatibility with the carboxyl group-containing coating material is improved, and the water resistance and appearance of the cured resin are improved, which is preferred.

[0074] Furthermore, by appropriately adjusting the average number of carbodiimide groups per molecule of the water-soluble modified polycarbodiimide (A), the crosslinking structure formed during reaction with the carboxylic acid (carboxyl) groups from the main component can be adjusted. From the perspective of storage stability after the coating composition is prepared, the average number of carbodiimide groups per molecule of the water-soluble modified polycarbodiimide (A) is preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.0 or less, and even more preferably 1.0 or less. By adjusting the average number of carbodiimide groups within the above range, the molecular weight of the high molecular weight product generated by the reaction with the main component can be reduced, thereby suppressing undesirable effects such as increased viscosity of the coating composition, decreased water resistance of the cured resin, and poor appearance caused by the increased molecular weight.

[0075] On the other hand, the lower limit of the average number of carbodiimide groups per molecule is not particularly limited and may be 0, but is preferably not 0, more preferably 0.5 or greater, even more preferably 1.0 or greater, even more preferably 1.5 or greater, and particularly preferably 2.0 or greater. By setting the average number of carbodiimide groups within the above range, the water-soluble modified polycarbodiimide (A) chemically bonds with the carboxylic acid (carboxyl) groups derived from the main component when the cured resin is prepared, thereby suppressing the elution of the water-soluble modified polycarbodiimide (A) from the cured resin.

[0076] [Synthesis Method of Water-Soluble Modified Polycarbodiimide (A)]

[0077] The water-soluble modified polycarbodiimide (A) is obtained, for example, by a production method comprising the following steps: Step 2A and Step 3A may be performed in an appropriately altered order depending on the type of the modifier, but are usually performed in that order.

[0078] (1) a step of polycarbodiimidizing an isocyanate compound in the presence of a carbodiimidization catalyst to obtain a polycarbodiimide (hereinafter sometimes referred to as "step 1A");

[0079] (2) a step of capping the terminal isocyanate groups of the polycarbodiimide obtained in step 1A with a compound having a hydrophilic group to obtain a hydrophilic group-terminated polycarbodiimide (hereinafter sometimes referred to as "step 2A");

[0080] (3) A step of modifying at least a portion of the carbodiimide groups of the hydrophilic group-terminated polycarbodiimide obtained in step 2A with a modifying agent to obtain a water-soluble modified polycarbodiimide (A) (hereinafter sometimes referred to as "step 3A")

[0081] (Process 1A)

[0082] In step 1A, an isocyanate compound is subjected to a decarboxylation condensation reaction in the presence of a carbodiimidization catalyst to obtain a polycarbodiimide.

[0083] Examples of the isocyanate compound used in step 1A include the same isocyanate compounds as exemplified in the above-mentioned “water-soluble modified polycarbodiimide (A)”.

[0084] The reaction temperature can be, for example, 100°C or higher and 250°C or lower.

[0085] The reaction time is not particularly limited, but is preferably a time period until the number average molecular weight of the polycarbodiimide reaches a polymerization degree within the above range.

[0086] The decarboxylation condensation reaction can be carried out in the presence of a solvent or in the absence of a solvent. The solvent is not particularly limited, and examples thereof include hydrocarbons, ethers, compounds having an amide bond, and halogenated hydrocarbons. Examples of hydrocarbons include benzene, toluene, and xylene. Examples of ethers include tetrahydrofuran (hereinafter sometimes referred to as "THF") and diethyl ether. Examples of compounds having an amide bond include N,N-dimethylformamide. Examples of halogenated hydrocarbons include dichloromethane and chlorobenzene. One solvent may be used alone, or two or more solvents may be used in combination. When two or more solvents are used in combination, their combination and ratio may be selected arbitrarily.

[0087] Examples of the carbodiimidization catalyst include phospholene oxides, and examples of the phospholene oxides include 1-phenyl-2-phospholene-1-oxide and 3-methyl-1-phenyl-2-phospholene-1-oxide.

[0088] In step 1A, after the reaction is completed, post-treatment can be performed as needed using known methods to remove the polycarbodiimide. Specifically, any one of post-treatment operations such as filtration, washing, extraction, pH adjustment, dehydration, and concentration, or a combination of two or more, can be appropriately performed as needed, and the polycarbodiimide can be removed by concentration, crystallization, reprecipitation, column chromatography, or the like. Furthermore, the removed polycarbodiimide can be further subjected to crystallization, reprecipitation, column chromatography, extraction, stirring and washing of crystals using a solvent, or a combination of two or more, and these operations can be repeated one or more times to purify the product.

[0089] In step 1A, the polycarbodiimide may be used in the next step without being removed after the reaction is completed. However, from the perspective of increasing the yield of the target water-soluble modified polycarbodiimide (A), it is preferred to remove the polycarbodiimide by the above method.

[0090] (Process 2A)

[0091] In step 2A, the terminal isocyanate groups of the polycarbodiimide obtained in step 1A are blocked with a compound having a hydrophilic group to obtain a hydrophilic group-terminated polycarbodiimide.

[0092] Examples of the compound having a hydrophilic group include ethylene oxide, propylene oxide, and polymers or copolymers thereof; alcohols, sulfonates, quaternary ammonium salts, and phosphates.

[0093] In step 2A, a compound having a hydrophilic group and a compound not having a hydrophilic group may be mixed and used as long as the water solubility of the obtained water-soluble modified polycarbodiimide (A) can be ensured.

[0094] The amount of the compound having a hydrophilic group added can be appropriately adjusted according to the molar amount of the terminal isocyanate groups of the polycarbodiimide.

[0095] The reaction temperature can be, for example, 100°C or higher and 250°C or lower.

[0096] The reaction can be carried out in the presence or absence of a solvent. Examples of the solvent include the same solvents as exemplified in the above step 1A.

[0097] In step 2A, after completion of the reaction, the hydrophilic group-terminated polycarbodiimide can be removed by the same method as in step 1A, and the removed hydrophilic group-terminated polycarbodiimide can be further purified by the same method.

[0098] (Process 3A)

[0099] In step 3A, at least a portion of the carbodiimide groups of the hydrophilic group-terminated polycarbodiimide obtained in step 2A is modified with a modifying agent to obtain a water-soluble modified polycarbodiimide (A) in which at least a portion of the carbodiimide groups are converted into functional groups having reduced reactivity with carboxylic acid (carboxyl) groups contained in the main agent component. Examples of the functional groups having reduced reactivity with carboxylic acid (carboxyl) groups contained in the main agent component include the same functional groups as exemplified in the above-mentioned "water-soluble modified polycarbodiimide (A)."

[0100] The modifier may be any compound having a reactive group that can react with a carbodiimide group, and examples thereof include isocyanates, alcohols, phenols, thiols, acyclic amines, cyclic amines, oximes, active methylene groups, carboxylic acids, and water.

[0101] By providing the modifier with an electron-withdrawing functional group in its skeleton, the reactivity of the polycarbodiimide with the modifier can be adjusted. When isocyanates, hydroxyl-containing compounds, sulfhydryl-containing compounds, non-cyclic amines, cyclic amines, active methylene groups, carboxylic acids, and / or carboxylic acid derivatives are used as modifiers, the electron-withdrawing functional group preferably has at least one of an unsaturated hydrocarbon group, a halogen group, and a carbonyl group, more preferably at least one of a halogen group and a carbonyl group, and particularly preferably at least one carbonyl group. By bonding to an electron-withdrawing functional group, the reactivity with the carbodiimide can be increased, making it easy to obtain a modified polycarbodiimide with reduced side reaction products, and thus preferred.

[0102] In addition, by having a highly hydrophobic functional group in the skeleton of the modifier, the hydrophobicity of the modified polycarbodiimide can be adjusted, thereby adjusting the water resistance and appearance of the cured resin. From this perspective, it is preferred that the modifier contain at least one of a saturated hydrocarbon group, an unsaturated hydrocarbon group, and a halogen group, more preferably at least one of a cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, an acyclic saturated hydrocarbon group having 1 to 12 carbon atoms, an unsaturated hydrocarbon group having 2 to 8 carbon atoms, and a halogen atom. It is further preferred that the modifier contain at least one halogen atom, and particularly preferably contains at least one fluorine atom. By using a modifier having the above-mentioned functional groups, the water resistance and appearance of the cured resin can be improved.

[0103] Furthermore, by including a functional group highly compatible with a compound having a carboxylic acid group in the modifier's backbone, the compatibility of the modified polycarbodiimide with the compound having a carboxylic acid (carboxyl) group can be adjusted, thereby adjusting the water resistance and appearance of the resulting cured resin. From this perspective, the modifier preferably includes at least one of a hydroxyl group, an amino group, an ether group, and a carbonyl group, more preferably includes at least one of an ether group and a carbonyl group, and particularly preferably includes at least one carbonyl group.

[0104] As the isocyanates, monovalent isocyanate compounds are preferred, and examples thereof include ethyl isocyanate, propyl isocyanate (each isomer), butyl isocyanate (each isomer), amyl isocyanate (each isomer), hexyl isocyanate (each isomer), dodecyl isocyanate (each isomer), ethyl isocyanate (each isomer), butyl isocyanate (each isomer), isocyanate, and the like. Cyclopentyl ester (each isomer), cyclohexyl isocyanate, 2-isocyanatoethyl acrylate as isocyanates having an unsaturated hydrocarbon group, 2-isocyanatoethyl methacrylate, phenyl isocyanate, benzyl isocyanate, phenyl isocyanate, (S)-2-isocyanato-3-tert-butoxymethyl propionate as isocyanates having an ether group, (S)-2-isocyanato-3-tert-butoxyethyl propionate, (S)-2-isocyanato-3-tert-butoxyethyl propionate, Isocyanato-3-tert-butoxypropyl propionate (each isomer), (S)-2-isocyanato-3-tert-butoxybutyl propionate (each isomer), (S)-2-isocyanato-3-tert-butoxypentyl propionate (each isomer), (S)-2-isocyanato-3-tert-butoxyhexyl propionate (each isomer), (S)-2-isocyanato-3-tert-butoxydodecyl propionate (each isomer), etc. Isocyanates having a halogen group such as 2-fluorophenyl isocyanate, 2-chlorophenyl isocyanate, 2-bromophenyl isocyanate, 2-iodophenyl isocyanate, 3-fluorophenyl isocyanate, 3-chlorophenyl isocyanate, 3-bromophenyl isocyanate, 3-iodophenyl isocyanate, 4-fluorophenyl isocyanate, 4-chlorophenyl isocyanate, 4-bromophenyl isocyanate, 4-iodophenyl isocyanate, and isocyanates having a carbonyl group such as glycine methyl isocyanate (Methyl Isocyanatoacetate), Glycine ethyl isocyanate (Ethyl Isocyanatoacetate), Glycine propyl isocyanate, Glycine butyl isocyanate (each isomer), Glycine hexyl isocyanate (each isomer), Glycine dodecyl isocyanate (each isomer), Leucine methyl isocyanate (Methyl 2-isocyanato-4-methyl pentanoate), Leucine ethyl isocyanate (Ethyl 2-isocyanato-4-methyl pentanoate), Leucine propyl isocyanate (each isomer), Leucine pentyl isocyanate (each isomer), Leucine hexyl isocyanate (each isomer), Leucine dodecyl isocyanate (each isomer), Ethyl Isocyanatoacetate, etc.

[0105] As the alcohols, monohydric alcohol compounds (monoalcohols) are preferred, and examples thereof include methanol, ethanol, propanol (isomers), butanol (isomers), pentanol (isomers), hexanol (isomers), heptanol (isomers), octanol (isomers), nonanol (isomers), decanol (isomers), and dodecanol (isomers) as alcohols having a saturated hydrocarbon group; and 2-propene-1-ol, 2-butene-1-ol, 3-butene-1-ol, 2-pentene-1-ol, 3-pentene-1-ol, 4-pentene-1-ol, 2-hexene-1-ol, 3-hexene-1-ol, 4- Hexen-1-ol, 5-hexen-1-ol, benzyl alcohol, etc.; alcohols having an ether group such as 1-methoxy-2-propanol, 1-methoxyethanol, 1-ethoxyethanol, 1-propoxyethanol, 1-butoxyethanol, 1-pentyloxyethanol, 1-hexyloxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, 1-butoxy-2-propanol, 1-pentyloxy-2-propanol, 1-butoxy-2-propanol; alcohols having a halogen group such as fluoromethanol, chloromethanol, bromomethanol, iodomethanol, difluoromethanol, dichloromethanol, dibromomethanol, diiodomethanol, trifluoromethanol, trichloromethanol, tribromomethanol Methanol, triiodoethanol, 2-fluoroethanol, 2-chloroethanol, 2-bromoethanol, 2-iodoethanol, 2,2-difluoroethanol, 2,2-dichloroethanol, 2,2-dibromoethanol, 2,2-diiodoethanol, 2,2,2-trifluoroethanol, 2,2,2-trichloroethanol, 2,2,2-tribromoethanol, 2,2,2-triiodoethanol, 2,2,3,3,3-pentafluoropropanol, 2,2,3,3,3-pentachloropropanol, 2,2,3,3,3-pentabromopropanol, 2,2,3,3,3-pentaiodopropanol, 2,2,2-trifluoro-1-trifluoromethylethanol, 2,2,2-trichloro-1-trichloromethylethanol, 2,2,2 -Tribromo-1-tribromomethylethanol, 2,2,2-triiodo-1-triiodomethylethanol, 1,1,1,3,3,3-hexafluoro-2-trifluoromethylpropanol, 1,1,1,3,3,3-hexachloro-2-trichloromethylpropanol, 1,1,1,3,3,3-hexabromo-2-tribromomethylpropanol, 1,1,1,3,3,3-hexaiodo-2-triiodomethylpropanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 2,2,3,3,4,4,5,5-octachloro-1-pentanol, 2,2,3,3,4,4,5,5-octabromo-1-pentanol, 2,2,3,3,4,4,5,5-octabromo-1-pentanol, 2,2,3,3,4,4,5,55-octaiodo-1-pentanol, hexafluoroisopropanol, hexachloroisopropanol, hexabromoisopropanol, hexaiodoisopropanol, 2-fluorobenzyl alcohol, 2-chlorobenzyl alcohol, 2-bromobenzyl alcohol, 2-iodobenzyl alcohol, 3-fluorobenzyl alcohol, 3-chlorobenzyl alcohol, 3-bromobenzyl alcohol, 3-iodobenzyl alcohol, 4-fluorobenzyl alcohol, 4-chlorobenzyl alcohol, 4-bromobenzyl alcohol, 4-iodobenzyl alcohol, etc., hydroxy acid esters of alcohols having a carbonyl group, etc., methyl glycolate, ethyl glycolate, propyl glycolate (each isomer), butyl glycolate (each isomer), amyl glycolate (each isomer), hexyl glycolate (each isomer), dodecyl glycolate (each isomer), methyl lactate, ethyl lactate, propyl lactate (each isomer), butyl glycolate (each isomer), glycolic acid Amyl ester (each isomer), hexyl glycolate (each isomer), dodecyl glycolate (each isomer), methyl propanol, ethyl propanol, propyl propanol (each isomer), butyl propanol (each isomer), pentyl propanol (each isomer), hexyl propanol (each isomer), dodecyl propanol (each isomer), methyl 2-hydroxybutyrate, ethyl 2-hydroxybutyrate, propyl 2-hydroxybutyrate (each isomer), butyl 2-hydroxybutyrate (each isomer), pentyl 2-hydroxybutyrate (each isomer), hexyl 2-hydroxybutyrate (each isomer), dodecyl 2-hydroxybutyrate (each isomer), methyl 3-hydroxybutyrate, ethyl 3-hydroxybutyrate, propyl 3-hydroxybutyrate (each isomer), Butyl 3-hydroxybutyrate (each isomer), pentyl 3-hydroxybutyrate (each isomer), hexyl 3-hydroxybutyrate (each isomer), dodecyl 3-hydroxybutyrate (each isomer), methyl 4-hydroxybutyrate, ethyl 4-hydroxybutyrate, propyl 4-hydroxybutyrate (each isomer), butyl 4-hydroxybutyrate (each isomer), pentyl 4-hydroxybutyrate (each isomer), hexyl 4-hydroxybutyrate (each isomer), dodecyl 4-hydroxybutyrate (each isomer), dimethyl malate, diethyl malate, dipropyl malate (each isomer), dipentyl malate (each isomer), dihexyl malate (each isomer), didodecyl malate (each isomer), trimethyl citrate, triethyl citrate, citric acid Tripropyl citrate (each isomer), tributyl citrate (each isomer), tripentyl citrate (each isomer), trihexyl citrate (each isomer), trilauryl citrate (each isomer), trimethyl isocitrate, triethyl isocitrate, tripropyl isocitrate (each isomer), tripentyl isocitrate (each isomer), trihexyl isocitrate (each isomer), trilauryl isocitrate (each isomer), hydroxy-2-propanone, hydroxy-2-butanone, hydroxy-2-pentanone, hydroxy-2-hexanone, hydroxy-3-butanone, hydroxy-3-pentanone, hydroxy-3-hexanone, and the like; and 2-(dimethylamino)ethanol, 3-(dimethylamino)propanol, 4-(dimethylamino)pentanol, 5-(dimethylamino)hexanol, and the like as alcohols having an amino group.

[0106] Examples of phenols include phenol, methylphenol (each isomer), ethylphenol (each isomer), propylphenol (each isomer), butylphenol (each isomer), pentylphenol (each isomer), hexylphenol (each isomer), heptylphenol (each isomer), octylphenol (each isomer), nonylphenol (each isomer), dimethylphenol (each isomer), diethylphenol (each isomer), dipropylphenol (each isomer), dibutylphenol ( isomers), diamylphenol (each isomer), trimethylphenol (each isomer), triethylphenol (each isomer), tripropylphenol (each isomer), tributylphenol (each isomer), methoxyphenol (each isomer), ethoxyphenol (each isomer), phenoxyphenol (each isomer), (phenylmethyl)phenol (each isomer), (phenylpropyl)phenol (each isomer), phenylphenol (each isomer), naphthol (each isomer), etc.Examples of phenols having a halogen group include 2-fluorophenol, 3-fluorophenol, 4-fluorophenol, 2,4-difluorophenol, 2,6-difluorophenol, 3,4-difluorophenol, 3,5-difluorophenol, 2,4,6-trifluorophenol, 3,4,5-trifluorophenol, 2,3,5,6-tetrafluorophenol, pentafluorophenol, 2,3,5,6-tetrafluoro-4-trifluoromethylphenol, 2,3,5,6-tetrafluoro-4-pentafluorophenylphenol, perfluoro-1-naphthol, perfluoro-2-naphthol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 3,4- Dichlorophenol, 3,5-dichlorophenol, 2,4,6-trichlorophenol, 3,4,5-trichlorophenol, 2,3,5,6-tetrachlorophenol, pentachlorophenol, 2,3,5,6-tetrachloro-4-trichloromethylphenol, 2,3,5,6-tetrachloro-4-pentachlorophenylphenol, perchloro-1-naphthol, perchloro-2-naphthol, 2-bromophenol, 3-bromophenol, 4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, 3,4-dibromophenol, 3,5-dibromophenol, 2,4,6-tribromophenol, 3,4,5-tribromophenol, 2,3,5,6-tetrabromophenol, pentabromophenol, 2,3,5,6-Tetrabromo-4-tribromomethylphenol, 2,3,5,6-Tetrabromo-4-pentabromophenylphenol, Perbromo-1-naphthol, Perbromo-2-naphthol, 2-iodophenol, 3-iodophenol, 4-iodophenol, 2,4-diiodophenol, 2,6-diiodophenol, 3,4-diiodophenol, 3,5-diiodophenol, 2,4,6-triiodophenol, 3,4,5-triiodophenol, 2,3,5,6-tetraiodophenol, pentaiodophenol, 2,3,5,6-tetraiodo-4-triiodomethylphenol, 2,3,5,6-tetraiodo-4-pentaiodophenylphenol, Periodo-1-naphthol, Periodo-2-naphthol Phenol, 2-(trifluoromethyl)phenol, 3-(trifluoromethyl)phenol, 4-(trifluoromethyl)phenol, 2,6-bis(trifluoromethyl)phenol, 3,5-bis(trifluoromethyl)phenol, 2,4,6-tris(trifluoromethyl)phenol, 3,4,5-tris(trifluoromethyl)phenol, etc.; phenols having a carbonyl group such as methyl salicylate, ethyl salicylate, propyl salicylate, butyl salicylate, pentyl salicylate, hexyl salicylate, dodecyl salicylate, 2-acetylphenol, 3-acetylphenol, 4-acetylphenol, etc.; phenols having an amino group such as 1-acetyl-4-(4-hydroxyphenyl)piperazine, etc.

[0107] The non-cyclic amines are preferably non-cyclic secondary amines, and examples thereof include dimethylamine, diethylamine, dipropylamine, diisopropylamine, diisobutylamine, N-ethylmethylamine, N-ethylisopropylamine, N-ethylpropylamine, and N-tert-butylethylamine as non-cyclic amines having a saturated hydrocarbon group; N-methylbenzylamine, N-ethylbenzylamine, N-propylbenzylamine, and N-butylbenzylamine as non-cyclic amines having an unsaturated hydrocarbon group; and N-(2-methoxyethyl)methylamine, N-(2-ethoxyethyl)methylamine, N-(2-propoxyethyl)methylamine, N-(2-butoxyethyl)methylamine, N-(2-pentyloxyethyl)methylamine, N-(2-hexyloxyethyl)methylamine, and N-(2- bis(trifluoromethyl)amine, bis(trichloromethyl)amine, bis(tribromomethyl)amine, bis(triiodomethyl)amine, bis(2,2,2-trifluoroethyl)amine, bis(2,2,2-trichloroethyl)amine, bis(2,2,2-tribromoethyl)amine, bis(2,2,2- ...fluoromethyl)amine, bis(2,2,2-tribromoethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trichloroethyl)amine, bis(2,2,2-tribromoethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trichloroethyl)amine, bis(2,2,2-tribromoethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trichloromethyl)amine, bis(2,2,2-tribromoethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-tribromomethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trichloromethyl)amine, bis(2,2,2-tribromoethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-trifluoromethyl)amine, bis(2,2,2-tribromomethyl) -triiodoethyl)amine, bis(2,2,3,3,3-pentafluoropropyl)amine, bis(2,2,3,3,3-pentachloropropyl)amine, bis(2,2,3,3,3-pentabromopropyl)amine, bis(2,2,3,3,3-pentaiodopropyl)amine, bis(2,2,2-trifluoro-1-trifluoromethylethyl)amine, bis(2,2,2-trichloro-1-trichloromethylethyl)amine, bis(2,2,2-tribromo-1-tribromomethylethyl)amine, bis(2,2,2-triiodo-1-triiodomethylethyl)amine, bis(1,1,1,3,3,3-hexafluoro-2-trifluoromethylpropyl)amine, bis(1,1,1,3,3,3-hexachloro-2-trichloromethylpropyl)amine, bis(1,1,1,3,3,3-hexabromo-2-tribromo methylpropyl)amine, bis(1,1,1,3,3,3-hexaiodo-2-triiodomethylpropyl)amine, bis(2-fluorophenyl)amine, bis(3-fluorophenyl)amine, bis(4-fluorophenyl)amine, bis(2-chlorophenyl)amine, bis(3-chlorophenyl)amine, bis(4-chlorophenyl)amine, bis(2-bromophenyl)amine, bis(3-bromophenyl)amine, bis(4-bromophenyl)amine, bis(2-iodophenyl)amine, bis(3-iodophenyl)amine, bis(4-iodophenyl)amine, bis(2,6-difluorophenyl)amine, bis(3,5-difluorophenyl)amine, bis(2,6-dichlorophenyl)amine, bis(3,5-dichlorophenyl)amine, bis(2,6-dibromophenyl)amine, di(3,5-dibromophenyl)amine, bis(2,6-diiodophenyl)amine, bis(3,5-diiodophenyl)amine, bis(2,4,6-trifluorophenyl)amine, bis(2,4,6-trichlorophenyl)amine, bis(2,4,6-tribromophenyl)amine, bis(2,4,6-triiodophenyl)amine, bis(pentafluorophenyl)amine, bis(pentachlorophenyl)amine, bis(pentabromophenyl)amine, bis(pentaiodophenyl)amine, bis(2-(trifluoromethyl)phenyl)amine, bis(3-(trifluoromethyl)phenyl)amine, bis(4-(trifluoromethyl)phenyl)amine, bis(2,6-bis(trifluoromethyl)phenyl)amine, bis(3,5-bis(trifluoromethyl)phenyl)amine, bis(2,4,6-tri(trifluoromethyl)phenyl)amine Amines having a carbonyl group such as dimethyliminodiacetate, diethyliminodiacetate, dipropyliminodiacetate, dibutyliminodiacetate, dipentyliminodiacetate, dihexyliminodiacetate, N-methylglycine ethyl ester, and N-ethylglycine ethyl ester; non-cyclic amines having an amino group such as N,N,N'-trimethylethylenediamine; and non-cyclic amines having a hydroxyl group such as 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 1-(methylamino)-2-propanol, and 1-(ethylamino)-2-propanol.

[0108] The cyclic amines are preferably cyclic secondary amines, and examples thereof include cyclic amines having a saturated hydrocarbon group such as pyrrolidine and piperidine; cyclic amines having an unsaturated hydrocarbon group such as imidazole, pyrazole, pyrrole, 1,2,4-triazole, 1,2,3-triazole, and indole; cyclic amines having an ether group such as morpholine; and cyclic amines having a halogen group such as 1-fluoropiperidine, 1-chloropiperidine, 1-bromopiperidine, 1-iodopiperidine, 2-fluoropiperidine, 2-chloropiperidine, 2-bromopiperidine, 2-iodopiperidine, 3-fluoropiperidine, 3-chloropiperidine, 3-bromopiperidine, 3-iodopiperidine, 4-fluoropiperidine, 4-chloropiperidine, 4-bromopiperidine, 4-iodopiperidine, 5-fluoroindole, 5-chloroindole, 5-bromoindole, and 5-iodoindole. Indole, etc.; cyclic amines having a carbonyl group such as methyl 4-piperidinecarboxylate, ethyl 4-piperidinecarboxylate, propyl 4-piperidinecarboxylate (each isomer), butyl 4-piperidinecarboxylate (each isomer), pentyl 4-piperidinecarboxylate (each isomer), hexyl 4-piperidinecarboxylate (each isomer), dodecyl 4-piperidinecarboxylate (each isomer), etc.; cyclic amines having an amino group such as 1-methylpiperazine, 1-ethylpiperazine, 1-propylpiperazine (each isomer), 1-butylpiperazine (each isomer), 1-pentylpiperazine (each isomer), 1-hexylpiperazine (each isomer), 1-dodecylpiperazine (each isomer), etc.; cyclic amines having a hydroxyl group such as 3-hydroxypiperidine and 4-hydroxypiperidine.

[0109] Examples of the oximes include formaldehyde oxime, acetaldehyde oxime, acetaldehyde oxime, methyl ethyl ketoxime, 2-butanone oxime, and cyclohexanone oxime as oximes having a saturated hydrocarbon group; α-phenylaldehyde oxime as oximes having an unsaturated hydrocarbon group; and 2-fluorophenylaldehyde oxime, 2-chlorophenylaldehyde oxime, 2-bromophenylaldehyde oxime, and 2-iodophenylaldehyde as oximes having a halogen group. Oxime, 3-fluorobenzaldehyde oxime, 3-chlorobenzaldehyde oxime, 3-bromobenzaldehyde oxime, 3-iodobenzaldehyde oxime, 4-fluorobenzaldehyde oxime, 4-chlorobenzaldehyde oxime, 4-bromobenzaldehyde oxime, 4-iodobenzaldehyde oxime, etc., oximes having a carbonyl group such as 1-phenyl-1,2-propanedione-2-oxime, and cyclic amines having a hydroxyl group such as 1,3-dihydroxyacetone oxime.

[0110] Examples of other hydroxyl group-containing compounds include hydroxylamines represented by diethylhydroxylamine, hydroxysuccinimides represented by N-hydroxysuccinimide, and hydroxyphthalimides represented by N-hydroxyphthalimide.

[0111] Examples of the thiols include methyl mercaptan, ethyl mercaptan, propanethiol (each isomer), pentanethiol (each isomer), hexanethiol (each isomer), heptanethiol (each isomer), octanethiol (each isomer), nonanethiol (each isomer), decanethiol (each isomer), undecanethiol (each isomer), dodecanethiol (each isomer), cyclopentanethiol, cyclohexanethiol, and the like as thiols having a saturated hydrocarbon group; and 2-propylene-1,1,2-diol as thiols having an unsaturated hydrocarbon group. 1-thiol, benzylthiol, thiophenol, etc.; 3-fluoro-1-propanethiol, 3-chloro-1-propanethiol, 3-bromo-1-propanethiol, 3-iodo-1-propanethiol, 2-fluorothiophenol, 2-chlorothiophenol, 2-bromothiophenol, 2-iodothiophenol, 3-fluorothiophenol, 3-chlorothiophenol, 3-bromothiophenol, 3-iodothiophenol, 4-fluorothiophenol, 4-chlorothiophenol, 4-bromothiophenol, 4-iodothiophenol, etc. as thiols having a halogen group; Thiols such as methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate (each isomer), amyl thioglycolate (each isomer), hexyl thioglycolate (each isomer), dodecyl thioglycolate (each isomer), methyl thiolactate, ethyl thiolactate, propyl thiolactate (each isomer), amyl thiolactate (each isomer), hexyl thiolactate (each isomer), dodecyl thiolactate (each isomer), and the like, as thiols having an amino group 2-dimethylaminoethanethiol, 2-diethylaminoethanethiol, 2-dipropylaminoethanethiol, 2-dibutylaminoethanethiol, 2-dipentylaminoethanethiol, 2-dihexylaminoethanethiol, 2-didodecylaminoethanethiol, etc. as thiols having a hydroxyl group; 2-mercaptoethanol, 3-mercapto-1-propanol, 4-mercapto-1-butanol, 5-mercapto-1-pentanol, 5-mercapto-1-hexanol, 5-mercapto-1-dodecanol, etc.

[0112] Examples of the active methylene groups include dimethyl malonate, diethyl malonate, dipropyl malonate (each isomer), dipentyl malonate (each isomer), dihexyl malonate (each isomer), didodecyl malonate (each isomer), methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate (each isomer), amyl acetoacetate (each isomer), hexyl acetoacetate (each isomer), dodecyl acetoacetate (each isomer), acetylacetone, isopropyl acetoacetate, ... Di-sec-butyl malonate, di-tert-butyl malonate, di-tert-amyl malonate, diisopropyl malonate, tert-butyl ethyl malonate, isopropyl ethyl malonate, etc.; active methylene groups having an unsaturated hydrocarbon group such as dibenzyl malonate and benzyl acetoacetate; active methylene groups having an ether group such as bis(2-methoxyethyl) malonate and 2-methoxyethyl acetoacetate; active methylene groups having a halogen group such as methyl 4-fluoroacetoacetate, methyl 4-chloroacetoacetate, methyl 4-bromoacetoacetate, methyl 4-iodoacetoacetate, and ethyl 4-fluoroacetoacetate , methyl 4-chloroacetoacetate, ethyl 4-bromoacetoacetate, ethyl 4-iodoacetoacetate, propyl 4-fluoroacetoacetate (each isomer), propyl 4-chloroacetoacetate (each isomer), propyl 4-bromoacetoacetate (each isomer), propyl 4-iodoacetoacetate (each isomer), butyl 4-fluoroacetoacetate (each isomer), butyl 4-chloroacetoacetate (each isomer), butyl 4-bromoacetoacetate (each isomer), butyl 4-iodoacetoacetate (each isomer), pentyl 4-fluoroacetoacetate (each isomer), pentyl 4-chloroacetoacetate (each isomer). isomers), 4-bromoacetoacetate pentyl ester (each isomer), 4-iodoacetoacetate pentyl ester (each isomer), 4-fluoroacetoacetate hexyl ester (each isomer), 4-chloroacetoacetate hexyl ester (each isomer), 4-bromoacetoacetate hexyl ester (each isomer), 4-iodoacetoacetate hexyl ester (each isomer), 4-fluoroacetoacetate dodecyl ester (each isomer), 4-chloroacetoacetate dodecyl ester, 4-bromoacetoacetate dodecyl ester, 4-iodoacetoacetate dodecyl ester, trifluoroacetylacetone, trichloroacetylacetone, tribromoacetylacetone, triiodoacetylacetone, and the like.

[0113] When a hydroxyl-containing compound is used as a modifier for a water-soluble polycarbodiimide (A) or a water-insoluble polycarbodiimide (B), the lower limit of the pKa of the modifier in water is preferably 6, more preferably 7, further preferably 8, further preferably 9. On the other hand, the upper limit is preferably 16, more preferably 15, further preferably 14, further preferably 13, and particularly preferably 12. By having a pKa above the above lower limit, the urea formed by the reaction of the structure formed by the reaction of the carbodiimide group with the hydroxyl-containing compound and water can be reduced, thereby improving the water resistance of the cured resin. On the other hand, by having a pKa below the above upper limit, the reactivity of the carbodiimide group with the hydroxyl-containing compound is improved, and the modification of the polycarbodiimide can be carried out under mild conditions. It should be noted that the pKa in water is not necessarily limited to the pKa measured in water, and the value measured in other solvents can also be converted to the pKa in water. In addition, it is known that pKa has temperature dependence, but is generally a value near room temperature. For example, it is generally known that the pKa of ethanol is 16 and the pKa of phenol is 10.

[0114] Examples of the carboxylic acids include acetic acid, propionic acid, butyric acid, hexanoic acid, heptanoic acid, octanoic acid, pivalic acid, valeric acid, and isovaleric acid as carboxylic acids having a saturated hydrocarbon group; benzoic acid, anisic acid, acrylic acid, methacrylic acid, crotonic acid, pentenoic acid, tiliac acid, 3-methylcrotonic acid, and sorbic acid as carboxylic acids having an unsaturated hydrocarbon group; methoxyacetic acid, ethoxyacetic acid, propoxyacetic acid, butoxyacetic acid, pentyloxyacetic acid, hexyloxyacetic acid, methoxylactic acid, ethoxylactic acid, propoxylactic acid, butoxylactic acid, pentyloxylactic acid, and hexyloxylactic acid as carboxylic acids having an ether group; and fluoroacetic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, difluoroacetic acid, dichloroacetic acid, and dibromoacetic acid as carboxylic acids having a halogen group. Acid, diiodoacetic acid, trifluoroacetic acid, trichloroacetic acid, tribromoacetic acid, triiodoacetic acid, pentafluoropropionic acid, pentachloropropionic acid, pentabromopropionic acid, pentaiodopropionic acid, 2,2-bis(trifluoromethyl)propionic acid, 2,2-bis(trichloromethyl)propionic acid, 2,2-bis(tribromomethyl)propionic acid, 2,2-bis(triiodomethyl)propionic acid, 4,4,4-trifluorobutyric acid, 4,4,4-trichlorobutyric acid, 4,4,4-tribromobutyric acid, 4,4,4-triiodobutyric acid, heptafluorobutyric acid, heptachlorobutyric acid, heptabromobutyric acid, heptaiodobutyric acid, 4,4,5,5,6,6,6-heptafluorohexanoic acid, 4,4,5,5,6,6,6-heptachlorohexanoic acid, 4,4,5,5,6,6,6-heptabromohexanoic acid, 4,4,5,5,6,6,66-Heptaiodohexanoic acid, 2-fluorobenzoic acid, 2-chlorobenzoic acid, 2-bromobenzoic acid, 2-iodobenzoic acid, 3-fluorobenzoic acid, 3-chlorobenzoic acid, 3-bromobenzoic acid, 3-iodobenzoic acid, 4-fluorobenzoic acid, 4-chlorobenzoic acid, 4-bromobenzoic acid, 4-iodobenzoic acid, etc.; pyruvic acid as a carboxylic acid having a carbonyl group; malonic acid, monomethyl malonate, monoethyl malonate, monopropyl malonate (each isomer), monobutyl malonate (each isomer), monopentyl malonate (each isomer), monohexyl malonate (each isomer), monododecyl malonate (each isomer); acetoacetic acid, monomethyl maleate, monoethyl maleate, monopropyl maleate (each isomer), monopentyl maleate (each isomer), monohexyl maleate (each isomer) , monododecyl maleate (each isomer), monomethyl fumarate, monoethyl fumarate, monopropyl fumarate (each isomer), monopentyl fumarate (each isomer), monohexyl fumarate (each isomer), monododecyl fumarate (each isomer), monomethyl phthalate, monoethyl phthalate, monopropyl phthalate, monobutyl phthalate (each isomer), monopentyl phthalate (each isomer), monohexyl phthalate (each isomer), monododecyl phthalate (each isomer), monomethyl isophthalate, monoethyl isophthalate, monopropyl isophthalate (each isomer), monobutyl isophthalate (each isomer), monopentyl isophthalate (each isomer), monohexyl isophthalate (each isomer). isomers), monododecyl isophthalate (each isomer), monomethyl terephthalate, monoethyl terephthalate, monopropyl terephthalate (each isomer), monobutyl terephthalate (each isomer), monopentyl terephthalate (each isomer), monohexyl terephthalate (each isomer), monododecyl terephthalate (each isomer), hydroxy acids such as carboxylic acids having a hydroxy group, glycolic acid, lactic acid, tartronic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, monomethyl malate, monoethyl malate, monopropyl malate (each isomer), monopentyl malate (each isomer), monohexyl malate (each isomer), monododecyl malate (each isomer), monomethyl citrate, monoethyl citrate, Monopropyl citrate (each isomer), monopentyl citrate (each isomer), monohexyl citrate (each isomer), monododecyl citrate (each isomer), monomethyl isocitrate, monoethyl isocitrate, monopropyl isocitrate (each isomer), monopentyl isocitrate (each isomer), monohexyl isocitrate (each isomer), monododecyl isocitrate (each isomer), carboxylic acids having an amino group such as N,N-dimethylglycine, N,N-diethylglycine, N,N-dipropylglycine, N,N-dibutylglycine, N,N-dipentylglycine, N,N-dihexylglycine, N,N-dimethylalanine, diethylalanine, N,N-dipropylalanine, N,N-dibutylalanine, N,N-dipentylalanine, N,N-dihexylalanine, etc.

[0115] When a carboxylic acid is used as a modifier for a water-soluble polycarbodiimide (A) or a water-insoluble polycarbodiimide (B), the upper limit of the pKa of the modifier in water is preferably 4.8, more preferably 4.2, and particularly preferably 3.7. By setting the pKa below the above upper limit, the reaction of the O-acylurea structure obtained by the reaction of the carbodiimide group with the carboxylic acid to form a urea structure before changing to an N-acylurea structure can be suppressed, and the urea structure can be reduced, thereby improving the water resistance of the cured resin. As mentioned above, the pKa in water is not necessarily limited to the pKa measured in water, and the value measured in other solvents can also be converted to the pKa in water. In addition, it is known that the pKa has temperature dependence, but is generally a value near room temperature. For example, it is generally known that the pKa of acetic acid is 4.8 and the pKa of benzoic acid is 4.2.

[0116] The amount of the modifier added can be appropriately adjusted according to the molar amount of the carbodiimide groups contained in the hydrophilic group-terminated polycarbodiimide so that the modification rate of the water-soluble modified polycarbodiimide (A) falls within the above range.

[0117] The reaction temperature may be, for example, 20°C to 250°C, or 30°C to 80°C.

[0118] The reaction can be carried out in the presence or absence of a solvent. Examples of the solvent include the same solvents as exemplified in the above step 1A.

[0119] In step 3A, after completion of the reaction, the water-soluble modified polycarbodiimide (A) can be taken out by the same method as in step 1A, and the taken out water-soluble modified polycarbodiimide (A) can be further purified by the same method.

[0120] The structures of the polycarbodiimide obtained in step 1A, the hydrophilic group-terminated polycarbodiimide obtained in step 2A, and the water-soluble modified polycarbodiimide (A) obtained in step 3A can be confirmed by known methods such as nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and infrared spectroscopy (IR).

[0121] <Water-insoluble polycarbodiimide (B)>

[0122] The water-insoluble polycarbodiimide (B) is not particularly limited and is the same as the generally known water-insoluble polycarbodiimide. However, it is preferably a polycarbodiimide compound having a terminal structure composed of a non-hydrophilic group (hydrophobic group).

[0123] The polycarbodiimide serving as a raw material of the water-insoluble polycarbodiimide (B) is derived by polycarbodiimidizing an isocyanate compound in the presence of a carbodiimidization catalyst.

[0124] Examples of the isocyanate compound include the same isocyanate compounds exemplified in the above-mentioned "water-soluble modified polycarbodiimide (A)." Among them, when the isocyanate compound is a diisocyanate, 1,5-pentamethylene diisocyanate, HDI, an alicyclic diisocyanate, or an aromatic diisocyanate is preferred, IPDI, hydrogenated MDI, MDI, or TMXDI is more preferred, and IPDI or hydrogenated MDI is particularly preferred.

[0125] When the isocyanate compound is a polyisocyanate, it is preferably a polyisocyanate having at least one functional group selected from the group consisting of an isocyanurate group, a carbamate group, and an iminooxadiazinedione group.

[0126] The number average molecular weight of the polycarbodiimide used as the raw material of the water-insoluble polycarbodiimide (B), that is, the polycarbodiimide before the isocyanate groups are terminated, is preferably 300 to 6000, more preferably 400 to 5000, and even more preferably 600 to 4000. By setting the number average molecular weight within the above range, the particle size of the aggregate (micelle) formed by the water-insoluble polycarbodiimide (B) covering the water-soluble modified polycarbodiimide (A) can be effectively prevented from becoming excessively large, thereby causing aggregation and precipitation. As a result, the water dispersibility of the aggregate can be further improved, and the storage stability of the carbodiimide composition of this embodiment after being prepared as a coating composition can be further improved.

[0127] The number average molecular weight of the polycarbodiimide before the isocyanate groups are blocked can be measured, for example, by GPC measurement. Specifically, it can be measured using the method described in the examples below.

[0128] The bonding method of the polycarbodiimide and the non-hydrophilic group (sometimes referred to as a "hydrophobic group") at the end of the water-insoluble polycarbodiimide (B) is not particularly limited, and examples thereof include a urethane bond, a urea bond, a carbodiimide group, and an amide bond.

[0129] The non-hydrophilic group (hydrophobic group) is not particularly limited as long as it is a functional group that can impart water-insolubility to the polycarbodiimide. Examples thereof include aliphatic alkyl groups, alicyclic alkyl groups, aliphatic alkenyl groups, alicyclic alkenyl groups, and aliphatic alkynyl groups that may contain an ether bond, an ester bond, an amide bond, or a urethane bond. Among them, aliphatic alkyl groups or alicyclic alkyl groups that may contain an ether bond are preferred. These non-hydrophilic groups (hydrophobic groups) may be present alone or in combination of two or more.

[0130] Furthermore, as long as the water-insoluble property of the water-insoluble polycarbodiimide (B) can be ensured, a part of the terminal structure of the water-insoluble polycarbodiimide (B) may be composed of a hydrophilic group.

[0131] In the water-insoluble polycarbodiimide (B), at least a portion of the carbodiimide groups may be modified or unmodified. To improve compatibility with the water-soluble modified polycarbodiimide (A), it is preferred that at least a portion of the carbodiimide groups in the water-insoluble polycarbodiimide (B) be modified. Improving the compatibility between the water-soluble modified polycarbodiimide (A) and the water-insoluble polycarbodiimide (B) improves the dispersion stability of the curing agent composition after preparation. Furthermore, after preparation of the cured resin, the polycarbodiimide component is uniformly dispersed in the cured resin and reacts with the carboxylic acid, thereby contributing to improved water resistance. Specifically, the lower limit of the modification rate of the water-insoluble polycarbodiimide (B) may be 0%, but is preferably not 0%, more preferably 1% or greater, even more preferably 5% or greater, and even more preferably 10% or greater. On the other hand, reducing the modification rate of the polycarbodiimide (B) can improve the low-temperature curability of the resulting coating composition and the water resistance of the resulting coating film. From this perspective, the upper limit of the modification rate of the water-insoluble polycarbodiimide (B) is preferably 70% or less, more preferably 50% or less, even more preferably 35% or less, further preferably less than 5%, particularly preferably less than 1%, and most preferably 0%.

[0132] Furthermore, by appropriately adjusting the difference between the modification rate of the water-insoluble polycarbodiimide (B) and the modification rate of the water-soluble modified polycarbodiimide (A) after the carbodiimide composition is prepared, the reactivity with the carboxylic acid (carboxyl) groups derived from the main component can be adjusted. From the perspectives of storage stability and curability of the coating composition after preparation, and gel fraction, water resistance, and appearance of the cured resin after preparation, the modification rate of the water-insoluble polycarbodiimide (B) is preferably lower than that of the water-soluble modified polycarbodiimide (A), more preferably at least 10% lower than that of the water-soluble modified polycarbodiimide (A), even more preferably at least 30% lower than that of the water-soluble modified polycarbodiimide (A), and particularly preferably at least 50% lower than that of the water-soluble modified polycarbodiimide (A). By setting the modification ratio within the above range, the storage stability and curability of the coating composition, which have been in a trade-off relationship, can be balanced, and a cured resin having excellent gel fraction, water resistance, and appearance can be obtained.

[0133] The modification rate of the water-insoluble polycarbodiimide (B) can be calculated using the same method as that for the modification rate of the water-soluble modified polycarbodiimide (A).

[0134] [Synthesis Method of Water-Insoluble Polycarbodiimide (B)]

[0135] The water-insoluble polycarbodiimide (B) can be obtained, for example, by a production method comprising the following steps:

[0136] A process (hereinafter sometimes referred to as "process 1B") in which an isocyanate compound is polycarbodiimidized in the presence of a carbodiimidization catalyst, and the terminal isocyanate groups of the resulting polycarbodiimide are capped with a compound having a hydrophobic group to obtain a water-insoluble polycarbodiimide (B) (also referred to as a hydrophobic group-terminated polycarbodiimide).

[0137] (Process 1B)

[0138] In step 1B, polycarbodiimide formation by decarboxylation condensation of an isocyanate compound in the presence of a carbodiimidization catalyst and blocking of the terminal isocyanate groups of the obtained polycarbodiimide with a compound having a hydrophobic group are simultaneously carried out to obtain a water-insoluble polycarbodiimide (B).

[0139] It should be noted that in process 1B,

[0140] A step of polycarbodiimidizing an isocyanate compound in the presence of a carbodiimidization catalyst to obtain a polycarbodiimide (hereinafter sometimes referred to as "step 1B-1"), and

[0141] A step of capping the polycarbodiimide obtained in step 1B-1 with a compound having a hydrophobic group to obtain a water-insoluble polycarbodiimide (B) (hereinafter sometimes referred to as "step 1B-2")

[0142] Although they can be performed separately, it is preferable to perform the above-mentioned step 1B-1 and the above-mentioned step 1B-2 simultaneously from the viewpoint of production efficiency.

[0143] Examples of the isocyanate compound used in step 1B include the same isocyanate compounds as exemplified in the above-mentioned “water-soluble modified polycarbodiimide (A)”.

[0144] Examples of the compound having a hydrophobic group include aliphatic alkanes, alicyclic alkanes, aliphatic olefins, alicyclic olefins, and aliphatic alkynes which may contain an ether bond, an ester bond, an amide bond, or a urethane bond.

[0145] In step 1B, a compound having a hydrophobic group and a compound having a hydrophilic group may be mixed and used as long as the water-insolubility of the obtained water-insoluble polycarbodiimide (B) can be ensured.

[0146] The amount of the compound having a hydrophobic group added can be appropriately adjusted according to the molar amount of the terminal isocyanate groups of the polycarbodiimide generated during the reaction.

[0147] The reaction temperature can be, for example, 100°C or higher and 200°C or lower.

[0148] The reaction time is not particularly limited, but is preferably a time period until the number average molecular weight of the polycarbodiimide reaches a polymerization degree within the above range.

[0149] The decarboxylation condensation reaction can be carried out in the presence or absence of a solvent. Examples of the solvent include the same solvents as exemplified in step 1A of the above-mentioned "Method for synthesizing water-soluble modified polycarbodiimide (A)".

[0150] Examples of the carbodiimidization catalyst include the same ones as those exemplified in step 1A of the above-mentioned "method for synthesizing water-soluble modified polycarbodiimide (A)".

[0151] In step 1B, after completion of the reaction, the water-insoluble polycarbodiimide (B) can be removed by the same method as in step 1A of the above-mentioned "Method for synthesizing a water-soluble modified polycarbodiimide (A)", and the removed water-insoluble polycarbodiimide (B) can be further purified by the same method.

[0152] The production of the water-insoluble polycarbodiimide (B) may further include a step of modifying at least a portion of the carbodiimide groups of the hydrophobic group-terminated polycarbodiimide obtained in step 1B with a modifying agent to obtain a water-insoluble modified polycarbodiimide (B') (hereinafter sometimes referred to as "step 2B").

[0153] In step 2B, at least a portion of the carbodiimide groups of the hydrophobic group-terminated polycarbodiimide obtained in step 1B is modified with a modifying agent to obtain a water-insoluble modified polycarbodiimide (B') in which at least a portion of the carbodiimide groups are converted into functional groups having reduced reactivity with carboxylic acid (carboxyl) groups contained in the main agent component. Examples of the functional groups contained in the main agent component having reduced reactivity with carboxylic acid (carboxyl) groups include the same functional groups exemplified in the "water-soluble modified polycarbodiimide (A)" described above.

[0154] Examples of the modifier include the same modifiers as those exemplified in step 3A of the above-mentioned "Method for synthesizing water-soluble modified polycarbodiimide (A)".

[0155] The amount of the modifier added can be appropriately adjusted according to the molar amount of the carbodiimide groups in the hydrophobic group-terminated polycarbodiimide so that the modification rate of the water-insoluble modified polycarbodiimide (B') falls within the above range.

[0156] The reaction temperature may be, for example, 20°C to 100°C, or 30°C to 80°C.

[0157] The reaction can be carried out in the presence or absence of a solvent. Examples of the solvent include the same solvents as exemplified in step 1A of the above-mentioned "Method for synthesizing water-soluble modified polycarbodiimide (A)".

[0158] In step 2B, after the reaction is completed, the water-insoluble modified polycarbodiimide (B') can be removed by the same method as in step 1A of the above-mentioned "Method for synthesizing a water-soluble modified polycarbodiimide (A)", and the removed water-insoluble modified polycarbodiimide (B') can be further purified by the same method.

[0159] The structures of the water-insoluble polycarbodiimide (B) (hydrophobic group-terminated polycarbodiimide) obtained in step 1B and the water-insoluble modified polycarbodiimide (B') obtained in step 2B can be confirmed by known methods such as nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and infrared spectroscopy (IR).

[0160] <Method for producing carbodiimide composition>

[0161] The carbodiimide composition of the present embodiment can be produced by mixing a water-soluble modified polycarbodiimide (A), a water-insoluble polycarbodiimide (B), and, if necessary, a solvent.

[0162] The solvent may be water or an organic solvent.

[0163] As an organic solvent, any solvent that is not reactive with a carbodiimide group may be used, and examples thereof include hydrocarbons, diethyl ether, compounds having an amide bond, an ester bond, or a urea bond, and halogenated hydrocarbons. Examples of hydrocarbons include hexane, benzene, toluene, and xylene. Examples of ethers include THF and diethyl ether. Examples of compounds having an amide bond include N,N-dimethylformamide. Examples of compounds having an ester bond include ethyl acetate. Examples of compounds having a urea bond include 1,3-dimethylimidazolidinone. Examples of halogenated hydrocarbons include dichloromethane and chlorobenzene. In addition, when stored at low temperatures, the organic solvent may be reactive with a carbodiimide group, and the organic solvent may have active hydrogen.

[0164] The solvent may be used alone or in combination of two or more. When two or more solvents are used in combination, the combination and ratio thereof may be arbitrarily selected.

[0165] Curing agent composition

[0166] The carbodiimide composition has good water dispersibility and can be suitably used as a water-based curing agent composition.

[0167] That is, in one embodiment, the present invention provides a curing agent composition comprising the above-mentioned carbodiimide composition and water.

[0168] <Surfactant>

[0169] The curing agent composition of this embodiment preferably further contains a surfactant in order to improve the dispersion stability of the above-mentioned carbodiimide composition in water, that is, to improve the dispersion stability in water of the aggregate formed by the water-soluble modified polycarbodiimide (A) in the above-mentioned carbodiimide composition covering the water-insoluble polycarbodiimide (B).

[0170] The surfactant is not particularly limited, and examples thereof include anionic surfactants, cationic surfactants, nonionic surfactants, and betaine-based surfactants.

[0171] <Other curing agent ingredients>

[0172] The curing agent composition of the present embodiment may further comprise other curing agent components (crosslinking agent components) in addition to the above-mentioned carbodiimide composition. Examples of other curing agent components include oxazoline compounds, epoxy compounds, melamine compounds, isocyanate compounds, hydrazine compounds, and semicarbazide compounds.

[0173] Examples of the oxazoline compound include polymeric compounds having at least two oxazoline groups in a side chain, monomeric compounds having at least two oxazoline groups in one molecule, etc. Commercially available oxazoline compounds include, for example, Epocros WS-500 (manufactured by Nippon Shokubai, standard product name).

[0174] The epoxy compound may be any resin having two or more epoxy groups per molecule. Specific examples of epoxy-containing compounds include bisphenol-type epoxy-containing compounds obtained by adding epichlorohydrin to bisphenol, novolac-type epoxy-containing compounds obtained by adding epichlorohydrin to a novolac resin, and polyethylene glycol diglycidyl ether. The epoxy-containing compound may be prepared in a water-dispersible form as needed.

[0175] Examples of the melamine compound include partially or completely methylolated melamine resins obtained by a reaction between melamine and aldehyde.

[0176] Examples of the aldehyde include formaldehyde and paraformaldehyde.

[0177] Alternatively, the melamine compound may be a compound in which the methylol groups of the methylolated melamine resin are partially or completely etherified with an alcohol. Examples of the alcohol used for etherification include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, 2-ethylbutanol, and 2-ethylhexanol.

[0178] Examples of commercially available melamine compounds include Cymel 303, Cymel 323, Cymel 325, Cymel 327, Cymel 350, Cymel 370, Cymel 380, Cymel 385, Cymel 212, Cymel 251, Cymel 254, and Mycoat 776 (all manufactured by Allnex, trade names).

[0179] The isocyanate compound is a diisocyanate or polyisocyanate having an aliphatic, alicyclic or aromatic hydrocarbon group and an isocyanate group. Examples of the diisocyanate include tetramethylene diisocyanate (TMDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane-1,6-diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI), 1,3-bis(isocyanatomethyl)-cyclohexane (1,3-H6-XDI), 3(4)-isocyanatomethyl-1-methyl-cyclohexyl isocyanate (IMCI), isophorone diisocyanate (IPDI), bis(isocyanatomethyl)-norbornane (NBDI), 1,3-bis(isocyanatomethyl)-benzene, 1,3-bis(2-isocyanatopropyl-2-)benzene, 4,4'-dicyclohexylmethane diisocyanate (H12MDI), and lysine diisocyanate (LDI). Among them, HDI or IPDI is preferred from the viewpoint of weather resistance and industrial availability.

[0180] The polyisocyanate is obtained by polymerizing the diisocyanate using a catalyst or heating, and includes an isocyanurate structure, a uretdione structure, an allophanate structure, an iminodioxadiazinedione structure, a carbamate structure, a biuret structure, etc. in the molecule. Among them, the polyisocyanate preferably has an isocyanurate structure from the perspective of weather resistance.

[0181] Examples of other isocyanate compounds include triisocyanates such as 4-isocyanatemethyl-1,8-octamethylene diisocyanate (NTI), 1,3,6-hexamethylene triisocyanate (HTI), bis(2-isocyanatoethyl)-2-isocyanatoglutarate (GTI), and lysine triisocyanate (LTI).

[0182] These isocyanate compounds may be used in combination of two or more.

[0183] Furthermore, blocked isocyanate compounds obtained by blocking the above-mentioned isocyanate compounds with one or more blocking agents selected from the group consisting of known active methylene blocking agents, known oxime blocking agents, known amine blocking agents, and known pyrazole blocking agents may also be used.

[0184] Among them, as other curing agent components, melamine compounds or (blocked) isocyanate compounds are preferred from the viewpoints of industrial availability, low-temperature curing properties, and storage properties of the coating material.

[0185] Coating composition

[0186] The curing agent composition can be used in combination with a compound having a carboxyl group as a main component to form a coating composition such as an electrodeposition coating.

[0187] That is, in one embodiment, the present invention provides a coating composition comprising the above-mentioned curing agent composition and a compound having a carboxyl group.

[0188] The coating composition of the present embodiment contains the carbodiimide composition as a curing agent component, thereby achieving excellent storage stability and low-temperature curability.

[0189] <Compounds having a carboxyl group>

[0190] Examples of the compound having a carboxyl group include polyesters having a carboxyl group, polyamides having a carboxyl group, polyurethanes having a carboxyl group, acrylic acids having a carboxyl group, and polyolefins having a carboxyl group. Examples of the polyolefin constituting the polyolefin having a carboxyl group include polypropylene, polyethylene, polypropylene-polyethylene (random / block) copolymers, and other polyolefins having 4 or more carbon atoms in the repeating unit.

[0191] These compounds having a carboxyl group may be used alone or in combination of two or more.

[0192] In the coating composition of the present embodiment, the compound having a carboxyl group can be used in the form of a main agent composition mixed with other components.

[0193] In the coating composition of this embodiment, the lower limit of the molar equivalent ratio of the carbodiimide groups in the carbodiimide composition to the carboxyl groups in the compound having a carboxyl group (carbodiimide group / carboxyl group) is, for example, 0.1, preferably 0.2, and more preferably 0.5. On the other hand, the upper limit of the carbodiimide group / carboxyl group ratio is, for example, 5.0, preferably 2.0, and more preferably 1.5.

[0194] That is, the ratio of carbodiimide group / carboxyl group is 0.1 to 5.0, preferably 0.2 to 2.0, and more preferably 0.5 to 1.5.

[0195] When the ratio of carbodiimide groups to carboxyl groups falls within the above range, the resulting cured resin tends to have more excellent water resistance and a higher crosslinking density.

[0196] <Additives>

[0197] The coating composition of the present embodiment may further contain additives such as epoxy resins, catalysts, coating improvers, leveling agents, defoamers, antioxidants, stabilizers such as ultraviolet absorbers, plasticizers, surfactants, pigments, fillers, organic or inorganic microparticles, mildew inhibitors, and silane coupling agents as needed. The amount of these additives is appropriately determined according to their purpose and use.

[0198] Resin Curing

[0199] By curing the above-mentioned coating composition, a cured resin can be obtained.

[0200] That is, in one embodiment, the present invention provides a cured resin material obtained by curing the above-mentioned coating composition. The cured resin material of this embodiment has excellent water resistance.

[0201] There is no particular limitation on the method for manufacturing a cured resin. For example, when the coating composition is a single component, a method of directly applying the coating composition to the object to be coated or adhered can be cited. In addition, when the coating composition is a two-liquid type, a method of mixing the curing agent composition with a compound having a carboxyl group and, if necessary, an additive, and applying the resulting coating composition to the object to be coated or adhered can be cited. Next, the coating composition applied to the object to be coated or adhered is heat-cured to obtain a cured resin. In addition, the chemical structure of the polycarbodiimide in the cured resin can be analyzed by various analytical methods. In the cured resin, when the curing agent composition described in the present invention is in a state of reacting with or not reacting with carboxylic acid, functional groups, functional group ratios, etc. can be clearly determined by solid-state NMR measurement, LC analysis, GC analysis, IR measurement, Raman measurement, XPS measurement, etc. Furthermore, when a functional group in equilibrium with the carbodiimide contained in the curing agent composition described in the present invention remains in the cured resin, the structure can be clarified by analyzing the thermal decomposition product by methods such as thermal decomposition GC-MS.

[0202] The upper limit of the curing temperature of the coating composition is, for example, 140°C, preferably 100°C, and more preferably 80°C. On the other hand, the lower limit of the curing temperature is, for example, 20°C, preferably 30°C, and more preferably 40°C.

[0203] That is, the curing temperature of the coating composition is 20°C to 140°C, preferably 30°C to 100°C, and more preferably 40°C to 80°C.

[0204] Examples of a coating method for the coating composition include roller coating, curtain coating, spray coating, rotary cup coating, and electrostatic coating.

[0205] Example

[0206] The present invention will be described in more detail below with reference to specific examples. However, the present invention is not limited to the following examples unless the gist of the invention is exceeded.

[0207] <Measurement Methods of Physical Properties>

[0208] [Physical properties 1]

[0209] (number average molecular weight)

[0210] The number average molecular weight of the polycarbodiimide before isocyanate group end-capping (isocyanate-terminated polycarbodiimide) was determined by GPC measurement using the following measurement conditions, and the number average molecular weight was calculated as a polystyrene-based molecular weight. Note that polystyrene with a molecular weight of 300 to 40,000 was used for the preparation of the calibration curve.

[0211] (Measurement conditions)

[0212] Device: HLC-8320GPC (TOSOH)

[0213] Column: TSKgel Super H3000 × 1 (TOSOH)

[0214] TSKgel Super H2000×1 stick (TOSOH)

[0215] TSKgel Super H1000×1 stick (TOSOH)

[0216] Carrier: Tetrahydrofuran

[0217] Flow rate: 0.6 mL / min

[0218] Sample concentration: 1.0 mass%

[0219] Injection volume: 20 μL

[0220] Temperature: 40℃

[0221] Detection method: Differential refractometer

[0222] In addition, in water-insoluble polycarbodiimide, for the end-blocking reaction and the polycarbodiimide reaction of carrying out terminal isocyanate group simultaneously and synthesized sample, the number average molecular weight after end-blocking is measured using GPC, the end-blocking structure is deducted by the number average molecular weight obtained, the number average molecular weight of the polycarbodiimide before isocyanate group end-blocking is calculated.It should be noted that, in the case where monoisocyanate is used to carry out end-blocking, when the structure before end-blocking is converted into the structure after end-blocking, the departure of carbon dioxide will be produced, so its contribution is included in calculating.On the other hand, in the case where the alcohols such as PGME are used to carry out end-blocking, when the structure before end-blocking is converted into the structure after end-blocking, the departure of carbon dioxide will not be produced, so contribution is not considered in calculating.

[0223] Specifically, the calculation is performed using the following formula.

[0224] (1) When end-capping is performed using cyclohexyl isocyanate

[0225] (Number average molecular weight of polycarbodiimide (PCI) before isocyanate end-capping) = (Number average molecular weight of polycarbodiimide determined by GPC after end-capping) - 2 × (molecular weight of cyclohexyl isocyanate: 125 g / mol) + 2 × (molecular weight of carbon dioxide: 44 g / mol)

[0226] (2) End-capping with propylene glycol monomethyl ether (PGME)

[0227] (Number average molecular weight of polycarbodiimide (PCI) before isocyanate end-capping) = (Number average molecular weight of polycarbodiimide determined by GPC after end-capping) - 2 × (PGME molecular weight: 90 g / mol)

[0228] [Physical Properties 2]

[0229] (Modification rate)

[0230] The wavelength 2150 cm derived from the carbodiimide group was determined by infrared absorption spectroscopy for the hydrophilic group-terminated polycarbodiimide obtained in step 2A of "Synthesis of a water-soluble modified polycarbodiimide" described later immediately after the addition of the modifier (i.e., the hydrophilic group-terminated polycarbodiimide before modification (the water-soluble polycarbodiimide before modification)) and the water-soluble modified polycarbodiimide obtained in step 3A of "Synthesis of a water-soluble modified polycarbodiimide". -1 The modification rate was calculated based on the following formula using the integrated value of the absorption peak near .

[0231] Modification rate (%) = (water-soluble modified polycarbodiimide at a wavelength of 2150 cm -1The integral value of the absorption peak near the hydrophilic group terminal polycarbodiimide at a wavelength of 2150 cm -1 absorption peak integral value near the

[0232] [Physical Properties 3]

[0233] (Solubility relative to 100g of water)

[0234] To a 300 mL glass stirring tank equipped with a mechanical stirrer, each water-soluble modified polycarbodiimide or each water-insoluble polycarbodiimide was added in amounts ranging from 1 g to 41 g. Subsequently, 100 g of water was added, and after stirring at 40°C for 48 hours, the mixture was visually inspected for the presence of precipitation. For each water-soluble modified polycarbodiimide or each water-insoluble polycarbodiimide, the boundary between the mass at which precipitation was observed and the mass at which no precipitation was observed was determined with an accuracy of 1 g. The maximum mass at which no precipitation was observed was taken as the solubility in 100 g of water. This method revealed that the solubility of each water-soluble modified polycarbodiimide in 100 g of water was greater than 10 g. On the other hand, the solubility of each water-insoluble polycarbodiimide in 100 g of water was less than 1 g.

[0235] [Physical Properties 4]

[0236] (Average number of carbodiimide functional groups per molecule)

[0237] The average number of carbodiimide functional groups per polycarbodiimide molecule was determined by infrared absorption (IR) spectroscopy at 2150 cm-1 derived from carbodiimide groups. -1 The carbodiimide group content (NCN%) was calculated from the integral value of the absorption peak near π / π, and then the NCN equivalent (g / mol) (chemical formula weight per 1 mol of carbodiimide group) was calculated. From the NCN equivalent and the number average molecular weight (g / mol) calculated by GPC, the number of functional groups was calculated based on the following formula.

[0238] Average number of carbodiimide functional groups per molecule = number average molecular weight (g / mol) / NCN equivalent (g / mol)

[0239] <Evaluation Method>

[0240] [Evaluation 1]

[0241] (Storage stability)

[0242] The storage stability of coating compositions prepared by mixing the carbodiimide compositions obtained in Examples and Comparative Examples with a main component was evaluated by measuring changes in viscosity.

[0243] Specifically, 36 g of each carbodiimide composition, adjusted to a solids content of 10% by mass, was added to 80 g of the acrylic polyol-based main agent, SETAQUA 6510, and stirred to form a homogeneous solution (coating composition). This homogeneous solution (coating composition) was heated at 40°C for 10 days, and the viscosity before and after heating was measured. Next, the viscosity after heating was divided by the viscosity before heating, and the resulting percentage was used as the viscosity increase rate. Storage stability was evaluated based on the obtained viscosity increase rate according to the following evaluation criteria.

[0244] (Evaluation Criteria)

[0245] ○: Viscosity increase rate is less than 120%

[0246] △: Viscosity increase rate is 120% or more and less than 140%

[0247] ×: Viscosity increase rate is 140% or more

[0248] [Evaluation 2]

[0249] (Low temperature curing)

[0250] The low-temperature curing properties of coating compositions prepared by mixing the carbodiimide compositions obtained in Examples and Comparative Examples with a main component were evaluated by measuring the gel fraction increase rate.

[0251] Specifically, 8g of ion-exchanged water was first added to 49g of a polyurethane aqueous dispersion (SUPERFLEX 150, manufactured by Daiichi Kogyo Seiyaku) and stirred to form a homogeneous solution. This homogeneous solution was then coated onto a polystyrene plate (hereinafter sometimes referred to as a "PS plate") and cured by baking in a dryer at 80°C for 30 minutes. The coating was then cut from the PS plate and placed on a plain woven metal mesh. After immersing the film in an acetone solution for 20 hours, the film was removed along with the plain woven metal mesh and dried in a dryer. The change in mass of the film before and after immersion in the acetone solution was then measured. The change in mass was divided by the mass of the film before immersion, and the resulting value was used as a percentage as the reference gel fraction.

[0252] Next, 8 g of each carbodiimide composition, adjusted to a solids content of 10% by mass, was added to 49 g of a polyurethane aqueous dispersion (SUPERFLEX 150, manufactured by Daiichi Kogyo Seiyaku) and stirred to form a homogeneous solution (coating composition). This homogeneous solution (coating composition) was applied to a PS plate and cured in the same manner as above. The gel fraction was then measured using the same method as above. The gel fraction increase was calculated by subtracting the reference gel fraction from the obtained gel fraction. Low-temperature curability was then evaluated based on the obtained gel fraction increase according to the following evaluation criteria.

[0253] (Evaluation Criteria)

[0254] ○: Gel fraction increase rate is 2% by mass or more

[0255] △: Gel fraction increase rate is 0% by mass or more and less than 2% by mass

[0256] ×: Gel fraction increase rate is less than 0% by mass

[0257] [Evaluation 3]

[0258] (Water resistance-structural retention)

[0259] The water resistance of the coating films using the carbodiimide compositions obtained in Examples and Comparative Examples was evaluated by the method shown below.

[0260] Specifically, first, 8 g of ion-exchanged water was added to 49 g of a polyurethane aqueous dispersion (manufactured by Daiichi Kogyo Pharmaceutical, SUPERFLEX 150), and then stirred to form a uniform solution (coating composition). The uniform solution (coating composition) was applied to a PS plate and cured in a dryer at 80°C for 30 minutes. An O-shaped ring (inner diameter: 1.78 mm, wire diameter: 1.78 mm) was then placed on the coating, and 1 mL of ion-exchanged water was dripped into the O-shaped ring. To prevent water volatilization, the ring was covered with a polyvinylidene chloride film. The plate was then left to stand at room temperature for 144 hours, and the morphology of the coating was visually confirmed for reference.

[0261] Next, 8g of each carbodiimide composition, adjusted to a solids content of 40% by mass, was added to 49g of a polyurethane aqueous dispersion (SUPERFLEX 150, manufactured by Daiichi Kogyo Seiyaku) and stirred to form a homogeneous solution (coating composition). This homogeneous solution (coating composition) was applied to a PS plate and cured in the same manner as above. The morphology of the coating film was then visually inspected using the same method as above and compared with a reference. Based on the results of this comparison, the water resistance (structure retention) of the coating film was evaluated according to the following evaluation criteria.

[0262] (Evaluation Criteria)

[0263] ○: The film state was maintained (compared to the reference coating film, no damage at all)

[0264] △: The film is partially damaged (the degree of damage is smaller than that of the reference coating film)

[0265] ×: Film destroyed (destroyed to the same degree as or more than the reference coating film)

[0266] [Evaluation 4]

[0267] (Water resistance-whitening resistance)

[0268] The water resistance of the coating films using the carbodiimide compositions obtained in Examples and Comparative Examples was evaluated by the method shown below.

[0269] Specifically, 8g of ion-exchanged water was first added to 49g of a polyurethane aqueous dispersion (manufactured by Daiichi Kogyo Seiyaku, SUPERFLEX 150) and stirred to form a uniform solution (coating composition). This uniform solution (coating composition) was applied to a PS plate and cured in a dryer at 80°C for 30 minutes. An O-ring (inner diameter: 1.78mm, wire diameter: 1.78mm) was then placed on the coating, and 1mL of ion-exchanged water was dripped into the O-ring. To prevent water evaporation, the ring was covered with a polyvinylidene chloride film. The coating was then left to stand at room temperature for 144 hours, and the degree of whitening of the coating was visually confirmed for reference.

[0270] Next, 8 g of each carbodiimide composition, adjusted to a solid content of 40% by mass, was added to 49 g of a polyurethane aqueous dispersion (manufactured by Daiichi Kogyo Pharmaceutical, SUPERFLEX 150), followed by stirring to form a uniform solution (coating composition). This uniform solution (coating composition) was applied to a PS plate in the same manner as above and allowed to cure. The degree of whitening of the coating was then visually confirmed using the same method as above and compared with a reference. Furthermore, after wiping off the ion-exchanged water, the coating was allowed to stand at room temperature, and the degree of whitening was visually confirmed again. Next, based on the results of this comparison, the water resistance (whitening resistance) of the coating was evaluated according to the following evaluation criteria.

[0271] (Evaluation Criteria)

[0272] ◎: No bleaching confirmed

[0273] ○: Although whitening was slightly observed, no whitening was observed after 1 hour after wiping off the ion exchange water.

[0274] △: Although whitening was clearly observed, no whitening was observed 24 hours after wiping off the ion-exchanged water.

[0275] ×: Whitening was clearly observed, and whitening was still observed 24 hours after wiping off the ion exchange water.

[0276] <Synthesis of Carbodiimide Compounds>

[0277] [Synthesis example 1]

[0278] (Synthesis of Water-Soluble Modified Polycarbodiimide A-1)

[0279] (1) Step 1A: Synthesis of isocyanate-terminated polycarbodiimide

[0280] In a 1 L SUS316 stirred tank, 100 g of dicyclohexylmethane-4,4'-diisocyanate and 0.5 g of 3-methyl-1-phenyl-2-phosphopentene-1-oxide (carbodiimidization catalyst) were added and reacted at 190°C for 20 hours under a nitrogen atmosphere to obtain an isocyanate-terminated polycarbodiimide. After the reaction, the isocyanate group-derived carbonyl group (CPO) at 2250 cm-1 was measured by infrared absorption (IR) spectroscopy. -1 The isocyanate group content (NCO%) was measured from the integrated value of the absorption peak near 5.7 mass % (polymerization degree 5.6). The number average molecular weight of the obtained isocyanate-terminated polycarbodiimide was 1485 g / mol.

[0281] (2) Step 2A: Synthesis of Hydrophilic Group-Terminated Polycarbodiimide

[0282] 64 g of polyethylene glycol monomethyl ether (number average molecular weight: 550) as a compound having a hydrophilic group (hereinafter sometimes referred to as "hydrophilic group-containing compound") was added to the isocyanate-terminated polycarbodiimide obtained in the above step 1A, and the mixture was reacted at 160°C for 48 hours under a nitrogen atmosphere to obtain a hydrophilic group-terminated polycarbodiimide. After the reaction, infrared absorption (IR) spectroscopy confirmed the presence of a 2250 cm-1 molecule derived from the isocyanate group. -1 The disappearance of the absorption peak near .

[0283] (3) Step 3A: Synthesis of Water-Soluble Modified Polycarbodiimide A-1

[0284] 33 g of 2,2,2-trifluoroethanol (TFE) was added as a modifier to the hydrophilic group-terminated polycarbodiimide obtained in step 2A above, and the mixture was reacted at 40°C for 72 hours under a nitrogen atmosphere to obtain water-soluble modified polycarbodiimide A-1. After the reaction, infrared absorption (IR) spectroscopy confirmed the presence of a wavelength of 2150 cm-1 derived from the carbodiimide group. -1 Therefore, the NCN% is 0%, and the average number of carbodiimide functional groups per molecule is 0.0.

[0285] [Synthesis Examples 2 to 144]

[0286] (Synthesis of Water-Soluble Modified Polycarbodiimides A-2 to A-144)

[0287] Each water-soluble modified polycarbodiimide was obtained using the same method as Synthesis Example 1, except that the diisocyanates, compounds serving as terminal structure sources, and modifiers shown in Tables 1 to 5 were used, and the number average molecular weight of the isocyanate-terminated polycarbodiimide (polycarbodiimide before isocyanate group end-capping) and the modification rate of the resulting water-soluble modified polycarbodiimide were adjusted to the values ​​shown in Tables 1 to 5. It should be noted that when two compounds serving as terminal structure sources were used, they were blended in a ratio corresponding to the molar ratios shown in Tables 1 to 5. In Tables 1 to 5, the abbreviations refer to the following compounds.

[0288] (diisocyanate)

[0289] hMDI: dicyclohexylmethane-4,4'-diisocyanate

[0290] IPDI: Isophorone diisocyanate

[0291] HDI: Hexamethylene diisocyanate

[0292] TDI: Toluene diisocyanate

[0293] TMXDI: 1,3-bis(2-isocyanato-2-propyl)benzene

[0294] (Compound as a source of terminal structure)

[0295] MPEG400: Polyethylene glycol monomethyl ether (number average molecular weight: 400)

[0296] MPEG500: Polyethylene glycol monomethyl ether (number average molecular weight: 500)

[0297] MPEG550: Polyethylene glycol monomethyl ether (number average molecular weight: 550)

[0298] MPEG1000: polyethylene glycol monomethyl ether (number average molecular weight: 1000)

[0299] MPEG2000: polyethylene glycol monomethyl ether (number average molecular weight: 2000)

[0300] MPEG5000: Polyethylene glycol monomethyl ether (number average molecular weight: 5000)

[0301] PGME: Propylene glycol monomethyl ether

[0302] PO-EO(970): Poly(ethylene glycol, propylene glycol) monobutyl ether (number average molecular weight: 970) (a compound represented by the following general formula (I); wherein n1 represents the number of repetitions (average number of polymerization) of oxypropylene groups, and n2 represents the number of repetitions (average number of polymerization) of oxyethylene groups. n1 and n2 are any numbers that allow the number average molecular weight to reach the above values.)

[0303] [Chemistry 1]

[0304]

[0305] (Modifier)

[0306] TFE: 2,2,2-trifluoroethanol

[0307] HFIP: Hexafluoroisopropanol

[0308] BuNCO: butyl isocyanate

[0309] DIPA: diisopropylamine

[0310] Hexanol: 1-hexanol

[0311] FB: 4-Fluorobenzyl alcohol

[0312] PhOH: phenol

[0313] FP: 4-fluorophenol

[0314] BL: Butyl lactate

[0315] DBM: DL-dibutyl malate

[0316] TBC: tributyl citrate

[0317] DEHA: Diethylhydroxylamine

[0318] BO: 2-Butanone oxime

[0319] DT: 1-dodecanethiol

[0320] BE: 2-bromoethanol

[0321] IE: 2-iodoethanol

[0322] TCE: 2,2,2-trichloroethanol

[0323] TFA: trifluoroacetic acid

[0324] TCA: trichloroacetic acid

[0325] CA: 2-chloroacetic acid

[0326] BBA: 2-bromoacetic acid

[0327] MAA: methoxyacetic acid

[0328] AA: Acetic acid

[0329] PA: pyruvate

[0330] EI: Ethyl isocyanate

[0331] MM: Methyl thioglycolate

[0332] DEIA: Diethyl iminodiacetate

[0333] PI: Piperidine

[0334] EPIA: ethyl 4-piperidinic acid ester

[0335] ACAC: Acetylacetone

[0336] TFAC: trifluoroacetylacetone

[0337] BA: Benzoic acid

[0338] NHS: N-hydroxysuccinimide

[0339] NHP: N-hydroxyphthalimide

[0340] LA: DL-lactic acid

[0341] DG: N,N-dimethylglycine

[0342] [Table 1]

[0343]

[0344] [Table 2]

[0345]

[0346] [Table 3]

[0347]

[0348] [Table 4]

[0349]

[0350] [Table 5]

[0351]

[0352] [Synthesis Example 145]

[0353] (Synthesis of Water-Insoluble Polycarbodiimide B-1)

[0354] In a 1 L SUS316 stirred tank, 100 g of dicyclohexylmethane-4,4'-diisocyanate, 58 g of cyclohexyl isocyanate (CHI), and 0.5 g of 3-methyl-1-phenyl-2-phospholene-1-oxide (carbodiimidization catalyst) were added and reacted at 190°C for 72 hours under a nitrogen atmosphere to obtain water-insoluble polycarbodiimide B-1. After the reaction, no isocyanate group-derived ions at 2250 cm were observed in infrared absorption (IR) spectroscopy. -1 The absorption peak near 2150 cm-1 derived from the carbodiimide group was confirmed. -1 The number average molecular weight of the obtained polycarbodiimide was 567 g / mol. The number average molecular weight of the polycarbodiimide (PCI) before the isocyanate end-capping was calculated based on the following formula after subtracting the end-capping structure from the number average molecular weight. The result was 405 g / mol. -1 The NCN equivalent weight determined from the absorption peak near the molecule was 212 g / mol, and the average number of carbodiimide groups per molecule was 2.7.

[0355] (Number average molecular weight of polycarbodiimide (PCI) before isocyanate end-capping) = (Number average molecular weight of polycarbodiimide determined by GPC after end-capping) - 2 × (molecular weight of cyclohexyl isocyanate: 125 g / mol) + 2 × (molecular weight of carbon dioxide: 44 g / mol)

[0356] [Synthesis Examples 146 to 162]

[0357] (Synthesis of Water-Insoluble Polycarbodiimides B-2 to B-18)

[0358] Using the diisocyanates shown in Table 6 and the compounds serving as the source of the terminal structure, the number average molecular weight of the isocyanate-terminated polycarbodiimide (polycarbodiimide before isocyanate group terminal blocking) and the modification rate of the obtained water-insoluble polycarbodiimide were adjusted to the values ​​shown in Table 6. Except for this, the same method as in Synthesis Example 145 was used to obtain each water-insoluble polycarbodiimide.

[0359] It should be noted that, regarding the water-insoluble modified polycarbodiimide using a modifier, after obtaining a water-insoluble polycarbodiimide with blocked isocyanate groups at the ends by the method shown in Synthesis Example 145, the modifier shown in Table 6 was added, and the mixture was reacted at 40°C under a nitrogen atmosphere for 72 hours to obtain a water-insoluble modified polycarbodiimide. After the reaction, infrared absorption (IR) spectroscopy confirmed that a wavelength of 2150 cm-1 derived from the carbodiimide group was detected. -1 near the absorption peak.

[0360] In Table 6, each abbreviation refers to the following compound.

[0361] (diisocyanate)

[0362] HDI: Hexamethylene diisocyanate

[0363] hMDI: dicyclohexylmethane-4,4'-diisocyanate

[0364] IPDI: Isophorone diisocyanate (mixture of isomers)

[0365] TMXDI: 1,3-bis(2-isocyanato-2-propyl)benzene

[0366] (Compound as a source of terminal structure)

[0367] CHI: Cyclohexyl Isocyanate

[0368] IDBI: 3-Isopropenyl-α,α-dimethylbenzyl isocyanate

[0369] [Table 6]

[0370]

[0371] [Example 1]

[0372] (Production of Carbodiimide Composition PC-a1)

[0373] In a 100 mL eggplant-shaped flask, 4 g of a water-soluble modified polycarbodiimide A-1 and 4 g of a water-insoluble polycarbodiimide B-1 were weighed and added with 20 g of tetrahydrofuran (THF) to prepare a polycarbodiimide THF solution. Next, 30 g of ion-exchanged water was added to the THF solution of the polycarbodiimide to obtain a milky white solution. The remaining THF and ion-exchanged water were removed by reduced pressure distillation at a liquid temperature of 40°C and a vacuum of 5 kPa. Ion-exchanged water was then added to obtain a milky white carbodiimide composition PC-a1 having a solids content of 10% by mass.

[0374] [Examples 2 to 171 and Comparative Examples 1 to 11]

[0375] (Manufacturing of Carbodiimide Compositions PC-a2 to PC-a171 and PC-b1 to PC-b11)

[0376] Each carbodiimide composition was obtained by the same method as in Example 1 except that the types and blending ratios of the water-soluble modified polycarbodiimide and the water-insoluble polycarbodiimide were as shown in Tables 7 to 13.

[0377] In the carbodiimide composition using sodium dodecylbenzenesulfonate (DBS) as a surfactant, DBS was added simultaneously with the addition of ion-exchanged water in amounts shown in Tables 9 and 13.

[0378] [Table 7]

[0379]

[0380] [Table 8]

[0381]

[0382] [Table 9]

[0383]

[0384] [Table 10]

[0385]

[0386] [Table 11]

[0387]

[0388] [Table 12]

[0389]

[0390] [Table 13]

[0391]

[0392] According to Tables 7 to 12, the carbodiimide compositions PC-a1 to PC-a171 (Examples 1 to 171) exhibited good storage stability and low-temperature curing properties after being prepared as coating compositions, and also exhibited good water resistance (structural retention, whitening resistance) after being prepared as coating films.

[0393] In addition, when comparing carbodiimide compositions PC-a12 and PC-a13 (Examples 12 and 13) using water-soluble modified polycarbodiimides having different number average molecular weights of compounds that serve as a source of terminal structures, a tendency was observed that the smaller the number average molecular weight of the compound that serves as a source of terminal structures, the better the storage stability of the coating composition after being prepared.

[0394] In addition, when comparing the carbodiimide compositions PC-a14 and PC-a15 (Examples 14 and 15), and PC-a16 and PC-a17 (Examples 16 and 17), each using a water-soluble modified polycarbodiimide having different number average molecular weights of the polycarbodiimide before isocyanate group terminal blocking, it was observed that the smaller the number average molecular weight of the polycarbodiimide before isocyanate group terminal blocking, the better the storage stability of the coating composition after being prepared.

[0395] In addition, when comparing the carbodiimide compositions PC-a15 and PC-a17 (Examples 15 and 17), and PC-a16 and PC-a18 (Examples 16 and 18), each using a water-soluble modified polycarbodiimide having different modification ratios, it was observed that the storage stability of the coating composition after preparation increased as the modification ratio of the water-soluble modified polycarbodiimide increased.

[0396] In addition, when comparing the carbodiimide compositions PC-a50 to PC-a53 (Examples 50 to 53) using water-insoluble polycarbodiimides with different modification rates, it was observed that the lower the modification rate of the water-insoluble polycarbodiimide, the better the low-temperature curing properties of the coating composition and the water resistance (structure retention) of the coating film.

[0397] In addition, when comparing carbodiimide compositions PC-a54 and PC-a55 (Examples 54 and 55), which use water-insoluble polycarbodiimides having different types of diisocyanates (main chain skeleton structures) used in production, it was observed that the carbodiimide composition PC-a54, which uses a water-insoluble polycarbodiimide whose main chain skeleton structure is derived solely from alicyclic isocyanate, tends to have better water resistance (structure retention) after forming a coating film.

[0398] On the other hand, the carbodiimide compositions PC-b1 (Comparative Example 1), PC-b6 (Comparative Example 6), PC-b7 (Comparative Example 7), PC-b8 (Comparative Example 8), PC-b9 (Comparative Example 9), PC-b10 (Comparative Example 10), and PC-b11 (Comparative Example 11) exhibited good low-temperature curability after being prepared as coating compositions and good water resistance (structure retention) after being prepared as coating films, but exhibited poor storage stability after being prepared as coating compositions. This is presumably because the modification rate of the water-soluble polycarbodiimides A-27, A-138, and A-139 contained in the carbodiimide compositions PC-b1 (Comparative Example 1), PC-b6 (Comparative Example 6), PC-b7 (Comparative Example 7), PC-b8 (Comparative Example 8), PC-b9 (Comparative Example 9), PC-b10 (Comparative Example 10), and PC-b11 (Comparative Example 11) was 0%, and the carbodiimide groups of the water-soluble polycarbodiimides A-27, A-138, and A-139 reacted with the main component during storage.

[0399] Furthermore, the carbodiimide compositions PC-b2 to PC-b4 (Comparative Examples 2 to 4) exhibited good storage stability after being prepared as coating compositions, but exhibited poor low-temperature curability and poor water resistance (structural retention and whitening resistance) after being prepared as coating films. This is presumably because the water-soluble modified polycarbodiimides A-28, A-6, and A-1 contained in the carbodiimide compositions PC-b2 to PC-b4 (Comparative Examples 2 to 4) had a modification rate of 100%, resulting in all carbodiimide groups being modified, reducing reactivity and preventing them from forming a crosslinked structure with the main component during curing.

[0400] Furthermore, the carbodiimide composition PC-b5 (Comparative Example 5) exhibited good low-temperature curability after forming a coating composition and good water resistance (structural retention) after forming a coating film. However, the storage stability after forming a coating composition and the water resistance (whitening resistance) after forming a coating film were poor. This is presumably because the polycarbodiimides contained in the carbodiimide composition PC-b5 (Comparative Example 5) were all water-soluble, and the individual water-soluble polycarbodiimides were dispersed without forming an association structure. Consequently, the water-soluble unmodified polycarbodiimide A-29, which had a modification rate of 0%, reacted with the main agent component during storage.

[0401] Industrial Applicability

[0402] The carbodiimide composition of this embodiment can provide a carbodiimide composition having excellent storage stability and low-temperature curability after being prepared as a coating composition. The polycarbodiimide composition of this embodiment is suitable for use as a curing agent for a water-based coating composition.

Claims

1. A carbodiimide composition comprising a water-soluble modified polycarbodiimide (A) and a water-insoluble polycarbodiimide (B), wherein the modifier of the water-soluble modified polycarbodiimide (A) comprises at least one selected from the group consisting of 2,2,2-trifluoroethanol, hexafluoroisopropanol, 4-fluorobenzyl alcohol, 4-fluorophenol, trifluoroacetic acid, and trifluoroacetylacetone. The water-soluble modified polycarbodiimide (A) has an average carbodiimide group number per molecule of 2.3 or less.

2. The carbodiimide composition according to claim 1, wherein The modification rate of the water-soluble modified polycarbodiimide (A) is 5% to 100%.

3. The carbodiimide composition according to claim 1 or 2, wherein The mass ratio (A) / (B) of the water-soluble modified polycarbodiimide (A) to the water-insoluble polycarbodiimide (B) is 90 / 10 or less.

4. The carbodiimide composition according to claim 1 or 2, wherein The modification rate of the water-insoluble polycarbodiimide (B) is 70% or less.

5. The carbodiimide composition according to claim 1 or 2, wherein The modification rate of the water-insoluble polycarbodiimide (B) is lower than the modification rate of the water-soluble modified polycarbodiimide (A).

6. The carbodiimide composition according to claim 1 or 2, wherein The average number of carbodiimide groups per molecule of the water-insoluble polycarbodiimide (B) is greater than the average number of carbodiimide groups per molecule of the modified polycarbodiimide (A).

7. The carbodiimide composition according to claim 1 or 2, wherein The isocyanate of the water-soluble modified polycarbodiimide (A) is blocked with polyalkylene glycol monoalkyl ether and / or alkylene glycol monoalkyl ether.

8. The carbodiimide composition according to claim 1 or 2, wherein The molar ratio of the isocyanate-terminated polyalkylene glycol monoalkyl ether and the alkylene glycol monoalkyl ether of the water-soluble modified polycarbodiimide (A) is 20 / 80 or more.

9. The carbodiimide composition according to claim 1, wherein The water-insoluble polycarbodiimide (B) modifier includes at least one selected from the group consisting of isocyanate, a hydroxyl-containing compound, a mercapto-containing compound, a non-cyclic amine, a cyclic amine, a carboxylic acid, and a carboxylic acid derivative.

10. The carbodiimide composition according to claim 1 or 9, wherein The water-insoluble polycarbodiimide (B) modifier contains at least one electron-withdrawing functional group in its skeleton.

11. The carbodiimide composition according to claim 1 or 9, wherein The water-insoluble polycarbodiimide (B) modifier has a skeleton bonded with any one of a cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, an acyclic saturated hydrocarbon group having 1 to 12 carbon atoms, an unsaturated hydrocarbon group having 2 to 8 carbon atoms, and a halogen atom.

12. The carbodiimide composition according to claim 1 or 9, wherein Any one of a hydroxyl group, an amino group, an ether group, and a carbonyl group is bonded to the skeleton of the water-insoluble polycarbodiimide (B) modifier.

13. The carbodiimide composition according to claim 1 or 9, wherein The water-insoluble polycarbodiimide (B) modifier contains at least one hydroxyl group-containing compound having a pKa in water of 7 to 16.

14. The carbodiimide composition according to claim 1 or 2, wherein The water-insoluble polycarbodiimide (B) modifier contains at least one carboxylic acid compound having a pKa of 4.8 or less in water.

15. The carbodiimide composition according to claim 1 or 2, wherein The solubility of the water-soluble modified polycarbodiimide (A) in 100 g of water is 10 g or more, and the solubility of the water-insoluble polycarbodiimide (B) in 100 g of water is less than 1 g.

16. The carbodiimide composition according to claim 1 or 2, wherein The mass ratio (A) / (B) of the water-soluble modified polycarbodiimide (A) to the water-insoluble polycarbodiimide (B) is 10 / 90 or more and 90 / 10 or less.

17. The carbodiimide composition according to claim 1 or 2, wherein The average number of carbodiimide groups per molecule of the water-insoluble polycarbodiimide (B) is greater than the average number of carbodiimide groups per molecule of the water-soluble modified polycarbodiimide (A) by 1 or more.

18. The carbodiimide composition according to claim 1 or 2, wherein The number average molecular weight of the polycarbodiimide serving as a raw material of the water-soluble modified polycarbodiimide (A), that is, the polycarbodiimide before the isocyanate groups are blocked, is 400 or more and 5000 or less.

19. The carbodiimide composition according to claim 1 or 2, wherein The number average molecular weight of the polycarbodiimide serving as a raw material for the water-insoluble polycarbodiimide (B), that is, the polycarbodiimide before the isocyanate groups are blocked, is 400 or more and 5000 or less.

20. The carbodiimide composition according to claim 1 or 2, wherein The modification rate of the water-insoluble polycarbodiimide (B) is 50% or less.

21. The carbodiimide composition according to claim 1 or 2, wherein The modification rate of the water-insoluble polycarbodiimide (B) is lower than the modification rate of the water-soluble modified polycarbodiimide (A) by 10% or more. 22 . A curing agent composition comprising the carbodiimide composition according to claim 1 , and water.

23. The curing agent composition according to claim 22, further comprising a surfactant. 24 . A coating composition comprising the curing agent composition according to claim 22 or 23 and a compound having a carboxyl group.

25. A cured resin obtained by curing the coating composition according to claim 24.

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