Disclosed is a carboxy group-containing aqueous resin composition containing a carboxy group-containing aqueous resin and a polycarbodiimide compound (X) represented by the following general formula (1):

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wherein R.sup.1 represents a residue obtained by removing a functional group capable of reacting with an isocyanate from a hydrophilic compound having the functional group capable of reacting with an isocyanate; R.sup.2 represents a divalent residue obtained by removing isocyanate groups from a diisocyanate compound; R.sup.3 represents a divalent residue obtained by removing hydroxy groups from a glycol compound; X represents a group to be formed through a reaction between the hydrophilic compound and the diisocyanate compound; n1 represents a number of 1 to 10; n2 represents a number of 1 to 10; m represents a number of 1 to 5; and plural R.sup.1's may be the same or different and plural R.sup.2's may be the same or different.

The present invention provides a method for producing an aqueous carbodiimide having excellent crosslinking reactivity with a crosslinking group, such as an alcoholic hydroxy group of an aqueous resin. The method for producing an aqueous carbodiimide-containing liquid includes a step (1) of mixing an isocyanate group-containing carbodiimide (A), a terminal blocking agent, and at least one organic metal compound selected from an organic titanium compound, an organic zirconium compound, and an organic aluminum compound and allowing them to react with each other, to obtain a terminal-blocked carbodiimide (B) in which the isocyanate group is blocked with the terminal blocking agent; and a step (2) of dissolving or dispersing the terminal-blocked carbodiimide (B) in an aqueous solvent, to obtain an aqueous carbodiimide-containing liquid, wherein the terminal blocking agent contains a hydrophilic compound (X) having a functional group having reactivity with the isocyanate group and a hydrophilic group other than the functional group.

The modified polycarbodiimide compound of the present invention is obtained by modifying a polycarbodiimide compound derived from a diisocyanate compound with at least one aliphatic amine selected from the group consisting of diethylamine, methylisopropylamine, tert-butylethylamine, di-sec-butylamine, dicyclohexylamine, 2-methylpiperidine and 2,6-dimethylpiperidine. The curing agent of the present invention comprises the modified polycarbodiimide compound of the present invention. The thermosetting resin composition of the present invention comprises a carboxyl group-containing resin having a carboxyl group in a molecule or an epoxy resin having two or more epoxy groups in one molecule, and the curing agent of the present invention. Thus, a modified polycarbodiimide compound that can allow a resin composition to be cured at a relatively low temperature and that can suppress curing of a resin composition in a drying step before a thermal curing step of a resin composition, a curing agent comprising the modified polycarbodiimide compound, and a thermosetting resin composition comprising the curing agent can be provided.

A method of producing a polycarbodiimide polymer comprises heating a precursor compound at a desired temperature. The method further comprises combining the precursor compound, a diisocyanate compound, and a carbodiimidization catalyst to form a reaction mixture. Finally, the method comprises heating the reaction mixture for a first period of time at a first temperature, thereby reacting the precursor compound and the diisocyanate compound in the presence of the carbodiimidization catalyst to produce the polycarbodiimide polymer.

To provide a polycarbodiimide copolymer and a modified polycarbodiimide copolymer each suitable for a curing agent that can allow a cured product of a carboxy group-containing resin composition to be improved in flexibility without any loss of water resistance, as well as a curing agent of a carboxy group-containing resin composition, and a carboxy group-containing resin composition. The present invention enables a cured product to be enhanced in water resistance due to introduction of a predetermined soft segment into a polycarbodiimide molecule, in use for a curing agent, and also enables a carboxy group-containing resin composition to be enhanced in storage stability due to modification with an aliphatic amine or an aromatic heterocyclic amine.

Coated substrates and methods may comprise a multi-unit carbodiimide. The multi-unit carbodiimide may also be combined with a siloxane. The multi-unit carbodiimide and/or the siloxane may be used in a surface coating applied to a substrate, and an overcoat may be applied to the surface coating. The surface coating may chemically interact with the overcoat and/or the substrate to improve corrosion resistance and other properties of the coated substrate.

The modified polycarbodiimide compound of the present invention is obtained by modifying a polycarbodiimide compound derived from a diisocyanate compound with an aromatic heterocyclic compound having endocyclic secondary amine nitrogen. The curing agent of the present invention comprises the modified polycarbodiimide compound of the present invention. Thus, a modified polycarbodiimide compound that allows amine dissociation to start at a low temperature as compared with a modified polycarbodiimide compound obtained by modifying a polycarbodiimide compound derived from a diisocyanate compound with diisopropylamine, and a curing agent comprising the modified polycarbodiimide compound can be provided.

A flexible polyurethane foam article exhibiting flame resistance comprises the reaction product of an isocyanate and an isocyanate-reactive component comprising a polyol reactive with the isocyanate. The isocyanate and the isocyanate-reactive component are reacted in the presence of a blowing agent and a phospholene oxide. A method of producing the flexible polyurethane foam article includes the step of reacting the isocyanate and the isocyanate-reactive component in the presence of the blowing agent and an effective amount of the phospholene oxide to form the flexible polyurethane foam article which is flame resistant.

The invention relates to a novel process for preparing carbodiimides comprising the steps of a) carbodiimidization of isocyanates in the presence of a catalyst, b) separation of the catalyst and/or monomeric isocyanate from the carbodiimide by distillation or extraction to obtain a crude carbodiimide comprising monomeric isocyanate, c) addition of one or more alcohols and partial or complete reaction of the alcohol with the monomeric isocyanate of the crude carbodiimide.

A process can be used for the preparation of a carbodiimide and/or a polycarbodiimide, where the process is particularly essentially free of an alkali metal. The carbodiimide and/or polycarbodiimide obtained and/or obtainable by the process and uses thereof are also provided.