Block isocyanate composition, powder composition containing the block isocyanate composition, method for producing the block isocyanate composition, method for producing the powder composition containing the block isocyanate composition, and powder coating agent containing the block isocyanate composition

Abstract

To enable solidification and powderization even in the case of a blocked isocyanate obtained by blocking by using a blocking agent not causing problems such as result from the case of using ε-caprolactam as a blocking agent and blocking a polyisocyanate component not causing the problem of yellow discoloration with the blocking agent.SOLUTION: A blocked isocyanate composition is synthesized from an isocyanate compound and a thermally dissociable blocking agent in which the thermally dissociable blocking agent is composed of a first blocking agent comprising ammonia and a second blocking agent different from the first blocking agent.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blocked isocyanate composition, a powder composition containing the blocked isocyanate composition, a method for producing the blocked isocyanate composition, a method for producing a powder composition containing the blocked isocyanate composition, and a powder coating composition containing the blocked isocyanate. In particular, it relates to a powdery blocked isocyanate composition applicable to powder materials such as coating materials (coating materials) and adhesives including powder coatings, a powdery powder composition containing the powdery blocked isocyanate composition, a method for producing the powdery blocked isocyanate composition, a method for producing the powdery powder composition containing the powdery blocked isocyanate composition, and a powder coating agent such as a powder coating composition containing the powdery blocked isocyanate.

Background Art

[0002] Conventionally, as paints using blocked isocyanates as curing agents, there are powder paints in addition to liquid paints. Among these, liquid paints have organic solvents that disperse into the environment (atmosphere) and become elements that do not form a film (coating layer), which are wasteful elements. In addition, from the perspective of regulations on the emission of VOCs (volatile organic compounds) and environmental considerations in recent years, powder paints that do not contain organic solvents have attracted attention.

[0003] Regarding such powder paints, for example, Patent Document 1 (Japanese Patent Laid-Open No. 54-40382), Patent Document 2 (Japanese Patent Laid-Open No. 60-13862), Patent Document 3 (Japanese Patent Laid-Open No. 57-78460), Patent Document 4 (Japanese Patent Laid-Open No. 6-179840), and Patent Document 5 (Japanese Patent Publication No. 3-504140) each have related descriptions.

[0004] Patent Document 1 discloses a powder polyurethane paint using a blocked isocyanate obtained by blocking isophorone diisocyanate (hereinafter sometimes referred to as "IPDI") as a polyisocyanate component with ε-caprolactam as a blocking agent as a curing agent. (See "Claims" and page 1 of this document.)

[0005] However, in the case of a powder paint using a blocked isocyanate obtained by blocking IPDI with ε-caprolactam as a curing agent as described in Patent Document 1, as a problem caused by ε-caprolactam as a blocking agent, in the baking process of applying the powder paint to an object to be coated (adherend) and heating it, after ε-caprolactam is thermally dissociated from the blocked isocyanate component in the powder paint, a problem arises due to a considerable amount of this thermally dissociated ε-caprolactam being generated and released into the atmosphere. For example, usually, the operation of applying the powder paint to the object to be coated is carried out in the internal space of a container (furnace) of a manufacturing plant. However, in the baking process after applying the powder paint to the object to be coated, the ε-caprolactam released from the powder paint as described above may adhere to the inside of the container of the manufacturing plant and become varnish, causing problems such as contamination inside the container of the manufacturing plant due to the varnish.

[0006] Therefore, in order to prevent such problems, the development of a blocked polyisocyanate using a blocking agent that does not cause problems such as ε-caprolactam as a blocking agent for the polyisocyanate component is desired.

[0007] On the other hand, in order for the powder paint to exhibit a desired color after baking and coating on the object to be coated, a predetermined pigment that exhibits the color is mixed. However, for example, a polyisocyanate having a benzene ring in one molecule, such as diphenylmethane diisocyanate (hereinafter sometimes referred to as "MDI"), itself turns yellow upon heating. Therefore, when a blocked polyisocyanate composed of such a polyisocyanate component is used as a curing agent for the powder paint, a problem occurs in that the powder paint cannot exhibit the inherent color due to the pigment because of the yellowing of the polyisocyanate component.

[0008] Therefore, as the polyisocyanate component constituting the blocked polyisocyanate of the curing agent for powder coatings, a polyisocyanate component that does not turn yellow upon heating (without having a benzene ring in one molecule), such as IPDI or HDI, for example, a non-yellowing polyisocyanate such as an aliphatic polyisocyanate (e.g., HDI) or an alicyclic polyisocyanate (e.g., IPDI), etc., needs to be used.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0010] However, regarding IPDI, in the case of blocked IPDI using a blocking agent other than the above-mentioned ε-caprolactam, it is known that the same solidification as blocked IPDI blocked with ε-caprolactam cannot be achieved.

[0011] Regarding HDI, as described in Patent Documents 2 and 3, it is known that due to problems caused by the nature of HDI itself, it is difficult or impossible to solidify (and powderize) blocked HDI. That is, according to Patent Documents 2 and 3, although there have been attempts to use HDI and / or its adducts (mixed trimers of HDI and IPDI) in a blocked state in polyurethane powder coatings, it has been confirmed that it is impossible to use HDI alone as a powder curing agent. (See the second line from the bottom left column to the sixth line from the bottom right column on page 2 of Patent Document 2, and the eighth line from the bottom right column on page 2 to the first line from the top left column on page 3 of Patent Document 3, the twenty-ninth line from the top right column to the third line from the bottom left column on page 4 of Patent Document 3, and the seventh line from the bottom right column to the eighteenth line on page 7 of Patent Document 3.)

[0012] Also, Patent Document 4 discloses a polyurethane powder coating in which HDI (similar to Patent Document 3) is used as the polyisocyanate component of a blocked polyisocyanate that is a curing agent for powder coatings. However, (since it is known that HDI cannot be solidified alone as described above,) it does not use HDI alone, but uses a blocked isocyanate in which a mixed trimer of HDI and IPDI is blocked with a ketoxime (acetone oxime, butanone oxime, cyclohexanone oxime) as a blocking agent as the curing agent. (See "Summary" and paragraphs

[0001] -

[0004] , paragraph

[0014] .)

[0013] In addition, Patent Document 5 discloses that a blocked polyisocyanate obtained by blocking tetramethylxylylene diisocyanate (hereinafter sometimes referred to as "TXMDI") with acetone oxime is used as a crosslinking agent (curing agent) for powder coatings, adhesives, and high-solids baking coatings (see claim 1 of the claims). However, TXMDI has a benzene ring in one molecule, and when a blocked polyisocyanate composed of TMXDI is used as a curing agent for powder coatings, there is a problem of yellowing caused by TMXDII as described above. Summary of the Invention Problems to be Solved by the Invention

[0014] In view of the above, an object of the present invention is to provide a blocked isocyanate composition that does not cause problems such as those that occur when ε-caprolactam is used as a blocking agent, and that can be solidified and powdered even when the polyisocyanate component that does not cause the problem of yellowing is blocked with the blocking agent, a powder composition using the blocked isocyanate composition, a method for producing the blocked isocyanate composition, a method for producing a powder composition using the blocked isocyanate composition, and a powder coating agent such as a powder coating composition containing the blocked isocyanate composition.

Means for Solving the Problems

[0015] The blocked isocyanate composition according to claim 1 is a blocked isocyanate composition synthesized from an isocyanate compound and a thermally dissociable blocking agent, wherein the thermally dissociable blocking agent comprises a first blocking agent composed of ammonia and a second blocking agent different from the first blocking agent. and the isocyanate compound consists of hexamethylene diisocyanate, and the second blocking agent is selected from amine-based blocking agents or oxime-based blocking agents It is characterized by the above.

[0016] The blocked isocyanate composition according to claim 2 is characterized in that, in the configuration of claim 1, the second blocking agent is an amine-based blocking agent.

[0017] The blocked isocyanate composition according to claim 3 is characterized in that, in the configuration of claim 1 or 2, the second blocking agent is diisopropylamine.

[0018] The blocked isocyanate composition according to claim 4 is characterized in that, in any of the configurations of claims 1 to 3, the isocyanate compound is hexamethylene diisocyanate. trimer It is characterized by the above.

[0019] The blocked isocyanate composition according to claim 5 is characterized in that, in any of the configurations of claims 1 to 4, the ratio of the first blocking agent to the second blocking agent is in the range of 10:90 to 60:40.

[0020] The blocked isocyanate composition according to claim 6 is a blocked isocyanate composition synthesized from an isocyanate compound and a thermally dissociable blocking agent, wherein the isocyanate compound consists of an aliphatic isocyanate, and the thermally dissociable blocking agent consists of a first blocking agent composed of ammonia and an amine-based blocking agent or an oxime-based blocking agent as a second blocking agent different from the first blocking agent and the isocyanate compound consists of hexamethylene diisocyanate and contains a trimer of hexamethylene diisocyanate, and the second blocking agent is selected from amine-based blocking agents or oxime-based blocking agents and is characterized by this.

[0021] The blocked isocyanate composition according to claim 7 is a blocked isocyanate composition synthesized from an isocyanate compound and a thermally dissociable blocking agent, wherein the isocyanate compound consists of an isocyanate compound having a plurality of isocyanate groups, and the thermally dissociable blocking agent consists of a first blocking agent composed of ammonia and a second blocking agent different from the first blocking agent, the isocyanate compound consists of a trimer of hexamethylene diisocyanate, and the second blocking agent consists of an amine-based blocking agent or an oxime-based blocking agent the second blocking agent blocks some of the isocyanate groups among the plurality of isocyanate groups of the isocyanate compound, and the first blocking agent blocks the remaining isocyanate groups among the plurality of isocyanate groups of the isocyanate compound that are not blocked by the second blocking agent, and is characterized by this.

[0022] The blocked isocyanate composition according to claim 8 is characterized in that, in the configuration of claim 6 or 7, the second blocking agent is an amine-based blocking agent, and the ratio of ammonia as the first blocking agent to the amine-based blocking agent as the second blocking agent is in the range of 10:90 to 60:40.

[0023] The blocked isocyanate composition according to claim 9, in the configuration of claim 6 or 7, is characterized in that the second blocking agent is an oxime-based blocking agent, and the ratio of ammonia as the first blocking agent to the oxime-based blocking agent as the second blocking agent is in the range of 50:50 to 60:40.

[0024] The blocked isocyanate composition according to claim 10, in the configuration of claim 7, said the second blocking agent blocks two of the three isocyanate groups in one molecule of the isocyanate compound, and the first blocking agent blocks the remaining one isocyanate group that the second blocking agent has not blocked among the three isocyanate groups of the isocyanate compound.

Advantages of the Invention

[0025] According to the present invention, in a blocked isocyanate composition, a powder composition using the blocked isocyanate composition, a method for producing the blocked isocyanate composition, a method for producing the powder composition, and a powder coating agent such as a powder coating composition containing the blocked isocyanate composition, it is possible to use a blocking agent that does not cause problems such as when ε-caprolactam is used as the blocking agent, and a blocked isocyanate in which a polyisocyanate component that does not cause the problem of yellowing is blocked by the blocking agent can also be solidified.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

[0027] [Overview] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described. In the present application documents, the term "isocyanate-reactive compound" is used in the sense of a compound having high reactivity with an isocyanate compound (typically, a polyol such as glycol). However, the term "isocyanate-reactive compound" is used in a meaning corresponding to the term "active hydrogen compound" (polyol, polyamine, polycarboxylic acid, etc.) which is a compound having two or more active hydrogens reactive with an isocyanate group in one molecule.

[0028] The blocked isocyanate composition according to the present invention can be applied as a curing agent for powder coating agents (fine powder coating agents) such as powder coating compositions. The blocked isocyanate composition according to the present invention blocks a predetermined polyisocyanate component such as HDI with two types of blocking agents (ammonia as the first blocking agent and a blocking agent such as an amine as the second blocking agent) while maintaining a high NCO content (high isocyanate group concentration (high NCO% (mass%), hereinafter sometimes simply referred to as "high NCO").), and solidifies and powders a blocked isocyanate compound such as this blocked HDI (hexamethylene diisocyanate). Here, as described in relation to the problems of the above invention, when the blocked isocyanate composition according to the present invention is embodied as a blocked isocyanate composition that is required not to have an unintended coating color (coating color) after application (coating) to an object to be coated such as a powder coating composition, as the isocyanate compound, a non-yellowing isocyanate compound such as HDI or IPDI (which does not cause problems such as yellowing described in the explanation of the background art) is used, and a yellowing isocyanate compound such as MDI is not used. In the present application documents, non-yellowing isocyanate compounds such as HDI and IPDI may sometimes be referred to as "non-yellowing isocyanate compounds" for convenience of explanation. Generally, such non-yellowing isocyanate compounds are composed of aliphatic isocyanate compounds such as HDI or alicyclic isocyanate compounds such as IPDI. Here, in the present invention, ammonia is used as a blocking agent for blocking the NCO groups of the isocyanate compound, but a blocked isocyanate composition using ammonia as a blocking agent for isocyanate (hereinafter sometimes simply referred to as "ammonia-blocked isocyanate") is not common and is only based on the unique findings and intensive research and development of the present inventors. Regarding the blocked isocyanate composition using ammonia as a blocking agent for isocyanate, Patent No. 6188576 according to the invention of the present inventors (and related to the ownership of the applicant of the present application) has a detailed description including its configuration and action effects, and can be referred to as necessary.

[0029] When the blocked isocyanate composition according to the present invention is applied as a curing agent for a powder coating agent such as a powder coating composition, it enables curing acceleration in a medium-low temperature range (for example, a medium-low temperature range of about 120 ° C), and can suppress the generation of soot. Here, the term "medium-low temperature range" is used in the sense of a medium temperature range in the "low temperature range" when the low temperature range is defined as 100 ° C to 150 ° C and the medium temperature range is defined as 150 ° C to 200 ° C.

[0030] [Powder composition] The blocked isocyanate composition according to the present invention is mixed with a predetermined polyol and a predetermined catalyst (organometallic catalyst) to constitute the powder composition according to the present invention.

[0031] [Powder coating composition] The blocked isocyanate composition according to the present invention is mixed with a predetermined polyol to constitute the powder composition according to the present invention. This powder composition constitutes the powder coating composition according to the present invention by adding and mixing a predetermined pigment, wax, leveling agent (and other optional components). Further, the blocked isocyanate composition according to the present invention is mixed with a predetermined polyol to constitute the powder composition according to the present invention. This powder composition constitutes the powder coating agent according to the present invention by adding and mixing a predetermined wax, leveling agent (and other optional components).

[0032] [Description of embodiments] Next, the blocked isocyanate composition according to the embodiment of the present invention will be described.

[0033] [Embodiment 1] [Blocked isocyanate composition] The blocked isocyanate composition according to Embodiment 1 is a blocked isocyanate composition synthesized from an isocyanate compound (isocyanate component) and a thermally dissociable blocking agent, and the thermally dissociable blocking agent comprises a first blocking agent composed of ammonia and a second blocking agent different from the first blocking agent. The blocked isocyanate composition according to Embodiment 1 comprises a first blocked isocyanate component in which the terminal isocyanate groups (NCO groups) of some of the isocyanate components are protected (blocked) by ammonia as the first blocking agent, and a second blocked isocyanate component in which the terminal isocyanate groups (NCO groups) of the other isocyanate components are protected (blocked) by the second blocking agent.

[0034] [Isocyanate component] As the isocyanate component (isocyanate compound) of the blocked isocyanate composition according to Embodiment 1, an aliphatic isocyanate and / or an alicyclic (alicyclic) isocyanate can be preferably used. In particular, when the blocked isocyanate composition according to Embodiment 1 is used as a curing agent for a composition such as a powder coating that needs to avoid the influence of yellowing of the isocyanate component, as the isocyanate component, a non-yellowing isocyanate that does not cause the problem of yellowing, such as an aliphatic isocyanate and / or an alicyclic (alicyclic) isocyanate, needs to be used.

[0035] Here, as the aliphatic isocyanate, for example, aliphatic diisocyanates such as trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate can be used.

[0036] Examples of the alicyclic polyisocyanate include alicyclic diisocyanates such as 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, i.e., IPDI), methylene bis(cyclohexyl isocyanate) (4,4'-, 2,4'- or 2,2'-methylene bis(cyclohexyl isocyanate), their Trans,Trans-form, Trans,Cis-form, Cis,Cis-form, or a mixture thereof), methylcyclohexane diisocyanate (methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), norbornane diisocyanate (various isomers or a mixture thereof), bis(isocyanatomethyl)cyclohexane (1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof).

[0037] In addition, as the isocyanate compound, for example, the above-mentioned aliphatic polyisocyanate and / or derivatives of alicyclic polyisocyanate can also be used. As the above-mentioned aliphatic polyisocyanate and / or derivatives of alicyclic polyisocyanate, for example, multimers of the above-mentioned isocyanate compound (for example, dimers such as uretdione-modified products, trimers such as isocyanurate-modified products or iminooxadiazinedione-modified products, etc.), allophanate-modified products (for example, allophanate-modified products produced by the reaction of the above-mentioned polyisocyanate and alcohols, etc.), urethane-modified products (for example, urethane-modified products produced by the reaction of polyisocyanate and polyol, etc.), biuret-modified products (for example, biuret-modified products produced by the reaction of the above-mentioned polyisocyanate and water or amines, etc.), urea-modified products (for example, urea-modified products produced by the reaction of the above-mentioned polyisocyanate and diamine, etc.), oxadiazinetrione-modified products (for example, oxadiazinetrione produced by the reaction of the above-mentioned polyisocyanate and carbon dioxide gas, etc.), carbodiimide-modified products (carbodiimide-modified products produced by the decarboxylation condensation reaction of the above-mentioned polyisocyanate, etc.), uretonimine-modified products, etc. can be used.

[0038] Here, as the derivative of the isocyanate compound, preferably, trimers of the isocyanate compound can be used, and more preferably, isocyanurate-modified products can be used.

[0039] In addition, when the blocked isocyanate composition according to Embodiment 1 is used as a curing agent for a composition (such as an adhesive) that does not require avoiding the influence of yellowing of the isocyanate component, such as a powder coating, as the isocyanate component, in addition to aliphatic isocyanate and / or alicyclic (alicyclic) isocyanate, etc., yellowing isocyanate can also be used. For example, as such an isocyanate compound, an isocyanate compound having a benzene ring can be used. For example, aromatic polyisocyanate, araliphatic polyisocyanate, etc. can be used.

[0040] Examples of the aromatic polyisocyanate include tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or a mixture thereof) (hereinafter sometimes referred to as "TDI"), phenylene diisocyanate (m-, p-phenylene diisocyanate or a mixture thereof), 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (hereinafter sometimes referred to as "NDI"), diphenylmethane diisocyanate (4,4'-, 2,4'- or 2,2'-diphenylmethane diisocyanate or a mixture thereof) (hereinafter sometimes referred to as "MDI"), 4,4'-toluidine diisocyanate (hereinafter sometimes referred to as "TODI"), 4,4'-diphenyl ether diisocyanate and other aromatic diisocyanates.

[0041] Examples of the aromatic aliphatic polyisocyanate include xylylene diisocyanate (1,3- or 1,4-xylylene diisocyanate or a mixture thereof) (hereinafter sometimes referred to as "XDI"), tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethylxylylene diisocyanate or a mixture thereof) (hereinafter sometimes referred to as "TMXDI"), ω,ω'-diisocyanate-1,4-diethylbenzene and other aromatic aliphatic diisocyanates.

[0042] Examples of the isocyanate compound include derivatives of the above-mentioned aromatic polyisocyanate and / or aromatic aliphatic polyisocyanate.

[0043] Examples of the derivative of the isocyanate compound include multimers of the isocyanate compound, allophanate-modified products, urethane-modified products, biuret-modified products, urea-modified products, oxadiazinetrione-modified products, carbodiimide-modified products, uretonimine-modified products and the like.

[0044] The above-mentioned isocyanate compounds can be used alone or in combination of two or more.

[0045] [Two types of blocking agents] The blocking agent of the blocked isocyanate composition according to the present invention consists of two types of blocking agents, and is composed of ammonia as the first blocking agent and a blocking agent other than ammonia as the second blocking agent. As the second blocking agent, a blocking agent having a lower reactivity (activity) with respect to the isocyanate group (NCO group) than ammonia can be used.

[0046] [The first blocking agent] As the first blocking agent of the blocked isocyanate composition according to the present invention, ammonia is used.

[0047] [The second blocking agent] As the second blocking agent, an amine-based blocking agent (hereinafter sometimes referred to as "amine-based blocking agent") can be preferably used. As the amine-based blocking agent, diphenylamine, carbazole, di-n-propylamine, and diisopropylamine can be used.

[0048] In addition to the above, examples of the amine-based blocking agent include dibutylamine, aniline, N-methylaniline, bis(2,2,6,6-tetramethylpiperidinyl)amine, isopropylethylamine, 2,2,4-, or 2,2,5-trimethylhexamethyleneamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis(3,5,5-trimethylcyclohexyl)amine, piperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, (dimethylamino)-2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethyl-4-piperidine, 6-methyl-2-piperidine, 6-aminocaproic acid, etc. can be used.

[0049] In addition to amine-based blocking agents, phenolic blocking agents, lactam-based blocking agents, alcohol-based blocking agents, oxime-based blocking agents, active methylene-based blocking agents, imidazole-based blocking agents, triazole-based blocking agents, pyrazole-based blocking agents, and bisulfite-based blocking agents can be used as the second blocking agent.

[0050] As the phenolic blocking agent, phenol, n-propylphenol, n-nonylphenol, and di-n-propylphenol can be used.

[0051] In addition to the above, for example, cresol, ethylphenol, isopropylphenol, n-butylphenol, s-butylphenol, t-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-s-butylphenol, di-t-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol, nitrophenol, bromophenol, chlorophenol, fluorophenol, dimethylphenol, styrenated phenol, methyl salicylate, methyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 2-ethylhexyl hydroxybenzoate, 4-[(dimethylamino)methyl]phenol, 4-[(dimethylamino)methyl]nonylphenol, bis(4-hydroxyphenyl)acetic acid, pyridinol, 2- or 8-hydroxyquinoline, 2-chloro-3-pyridinol, pyridine-2-thiol, etc. can be used as the phenolic blocking agent.

[0052] As the lactam-based blocking agent, ε-caprolactam and δ-valerolactam can be used.

[0053] As the alcohol-based blocking agent, ethanol, n-propylphenol, n-nonylphenol, and di-n-propylphenol can be used.

[0054] As alcohol-based blocking agents, in addition to those described above, for example, methanol, 2-propanol, n-butanol, s-butanol, 2-ethylhexyl alcohol, 1- or 2-octanol, cyclohexyl alcohol, ethylene glycol, benzyl alcohol, 2,2,2-trifluoroethanol, 2,2,2-trichloroethanol, 2-(hydroxymethyl)furan, 2-methoxyethanol, methoxypropanol, 2-ethoxyethanol, n-propoxyethanol, 2-butoxyethanol, 2-ethoxyethoxyethanol, 2-ethoxybutoxyethanol, butoxyethoxyethanol, 2-ethylhexyloxyethanol, 2-butoxyethyl ethanol, 2-butoxyethoxyethanol, N,N-dibutyl-2-hydroxyacetamide, N-hydroxysuccinimide, N-morpholineethanol, 2,2-dimethyl-1,3-dioxolan-4-methanol, 3-oxazolidineethanol, 2-hydroxymethylpyridine, furfuryl alcohol, 12-hydroxystearic acid, triphenylsilanol, 2-hydroxyethyl methacrylate, etc. can be used.

[0055] As oxime-based blocking agents, formaldoxime, acetaldoxime, acetoxime (acetone oxime), methyl ethyl ketoxime (methyl ethyl ketone oxime), diacetyl monoxime, benzophenone oxime, cyclohexanone oxime can be used. Among these, as the oxime-based blocking agent, methyl ethyl ketoxime (MEKO) can be preferably used.

[0056] As oxime-based blocking agents, in addition to the above, for example, 2,2,6,6-tetramethylcyclohexanone oxime, diisopropyl ketone oxime, methyl t-butyl ketone oxime, diisobutyl ketone oxime, methyl isobutyl ketone oxime, methyl isopropyl ketone oxime, methyl 2,4-dimethylpentyl ketone oxime, methyl 3-ethylheptyl ketone oxime, methyl isoamyl ketone oxime, n-amyl ketone oxime, 2,2,4,4-tetramethyl-1,3-cyclobutanedione monooxime, 4,4'-dimethoxybenzophenone oxime, 2-heptanone oxime, etc. can be used.

[0057] As active methylene-based blocking agents, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone can be used.

[0058] As active methylene-based blocking agents, in addition to the above, for example, Meldrum's acid, dialkyl malonates (e.g., di-n-butyl malonate, di-t-butyl malonate, di-2-ethylhexyl malonate, methyl n-butyl malonate, ethyl n-butyl malonate, methyl s-butyl malonate, ethyl s-butyl malonate, methyl t-butyl malonate, ethyl t-butyl malonate, diethyl methylmalonate, dibenzyl malonate, diphenyl malonate, benzyl methyl malonate, ethyl phenyl malonate, t-butyl phenyl malonate, isopropylidene malonate, etc.), alkyl acetoacetates (e.g., n-propyl acetoacetate, isopropyl acetoacetate, n-butyl acetoacetate, t-butyl acetoacetate, benzyl acetoacetate, phenyl acetoacetate, etc.), 2-acetoxyethyl methacrylate, ethyl cyanoacetate, etc. can be used.

[0059] As imidazole-based blocking agents, imidazole, 2-methylimidazole can be used.

[0060] As imidazole-based blocking agents, in addition to the above, for example, benzimidazole, 4-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, etc. can be used.

[0061] As triazole-based blocking agents, triazole can be used.

[0062] As triazole-based blocking agents, in addition to the above, for example, 1,2,4-triazole, 4-amino-1,2,4-triazole, benzotriazole, etc. can be used.

[0063] As pyrazole-based blocking agents, pyrazole and 3,5-dimethylpyrazole can be used.

[0064] As pyrazole-based blocking agents, in addition to the above, for example, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, 3-methyl-5-phenylpyrazole, etc. can be used.

[0065] As bisulfite-based blocking agents, sodium bisulfite can be used.

[0066] As the second blocking agent, in addition to the above, imine-based blocking agents, carbamic acid-based blocking agents, urea-based blocking agents, acid imide-based blocking agents, etc. can be used.

[0067] As imine-based blocking agents, for example, ethyleneimine, polyethyleneimine, 1,4,5,6-tetrahydropyrimidine, guanidine, etc. can be used.

[0068] As carbamic acid-based blocking agents, for example, phenyl N-phenylcarbamate, etc. can be used.

[0069] As the urea-based blocking agent, for example, urea, thiourea, ethylene urea, etc. can be used.

[0070] As the acid imide-based blocking agent, for example, succinimide, maleimide, phthalimide, etc. can be used.

[0071] The second blocking agent can be used alone or in combination of two or more of the above blocking agents.

[0072] In the blocked isocyanate composition according to this embodiment, first, a second blocking agent blocks the isocyanate groups (NCO groups) of some of the isocyanate components among the isocyanate components, and ammonia as the first blocking agent blocks the isocyanate groups (NCO groups) of the remaining isocyanate components among the isocyanate components. As a result, overall, two types of blocking agents (the first blocking agent and the second blocking agent) block the isocyanate groups of the isocyanate component. In particular, when the first blocking agent and the second blocking agent are mixed with the isocyanate compound to block the isocyanate groups of the isocyanate compound, in the blocked isocyanate composition according to this embodiment, by mixing the second blocking agent prior to the first blocking agent (ammonia), first, the second blocking agent blocks some of the isocyanate groups (NCO groups) of the isocyanate components among the isocyanate components, and then (i.e., after the blocking by the second blocking agent), ammonia as the first blocking agent blocks the remaining isocyanate groups (NCO groups) of the isocyanate component. Thus, overall, two types of blocking agents (the first blocking agent and the second blocking agent) block the isocyanate groups of the isocyanate component, which is regarded as one of the preferred embodiments. Also, the first blocking agent and the second blocking agent each have characteristics such as their own thermal dissociation temperatures. When the blocked isocyanate composition according to this embodiment is heated, they dissociate from the isocyanate groups of the isocyanate component at their respective specific thermal dissociation temperatures. Further, the inventors have actually confirmed that the blocked isocyanate composition according to this embodiment, in which the isocyanate groups of the isocyanate component are blocked by the first blocking agent and the second blocking agent, can solidify the isocyanate component even when an isocyanate such as HDI, which was conventionally difficult to solidify, is used as the isocyanate component, mainly due to the characteristics of ammonia as the first blocking agent (see Examples).

[0073] Specifically, conventionally, isocyanate compounds that are difficult to yellow, such as HDI, are difficult to solidify as described above (except for ε-caprolactam-blocked IPDI). Although it is known that an isocyanate compound can be solidified by water by adding water (H2O) to the isocyanate group of the isocyanate compound, in this case, the NCO ratio of the water-added isocyanate compound decreases. Since the powder coating composition is desired to have a high NCO, solidifying the isocyanate compound with water has low practicality from this perspective. On the other hand, as described above, the isocyanate compound according to the present invention can maintain a high NCO by blocking the isocyanate component with the first blocking agent and the second blocking agent.

[0074] Further, in the blocked isocyanate composition according to the present embodiment, when an amine-based blocking agent is used as the second blocking agent (particularly, when diisopropylamine is used as the amine-based blocking agent), the melting temperature of the blocked isocyanate composition becomes a melting temperature in a relatively low temperature range. Therefore, when preparing a powder composition such as a powder coating using the blocked isocyanate composition according to the present embodiment as a curing agent, the blocked isocyanate composition can be smoothly mixed with a predetermined isocyanate-reactive compound such as a polyol component having a melting temperature in a relatively low temperature range. In particular, when using a polyester polyol as the isocyanate-reactive compound, it is necessary to set the melting temperature of the blocked isocyanate composition to a corresponding low temperature range in accordance with the melting temperature of the polyester polyol. However, the melting temperature of the polyisocyanate composition according to the present embodiment is in a low temperature range equivalent to the melting temperature of the polyester polyol as described above when an amine-based blocking agent is used as the second blocking agent (particularly, when diisopropylamine is used as the amine-based blocking agent). Therefore, the polyisocyanate composition according to the present embodiment is smoothly compatible with the polyester polyol. In addition, in order to ensure compatibility with the polyol, when using a blocking agent other than the amine-based blocking agent as the second blocking agent, it is desirable to use a blocking agent having a melting temperature in a temperature range equivalent to the melting temperature of the polyol to be used.

[0075] Regarding MDI, which was cited as an example of the above isocyanate compound, monomeric MDI solidifies regardless of the added blocking agent, but it is unclear whether polymeric MDI solidifies or not. However, blocked MDI obtained by blocking monomeric MDI with a predetermined blocking agent has a melting temperature (softening point) of about 140°C. Therefore, the temperature difference from the melting temperature (softening point) of a polyol having a melting temperature in a low temperature range, such as polyester polyol, is large (because it is far on the high temperature range side), and there is no compatibility with such a polyol. Even when it is necessary to prepare a powder coating composition by mixing with such a polyol, it is difficult or impossible to prepare such a powder coating composition.

[0076] Also, as described above, when the isocyanate compound is solidified by water, the water molecules added to the isocyanate groups of the isocyanate do not dissociate from the isocyanate groups even when heated, and form urea bonds, so it is impossible to maintain a high NCO of the isocyanate composition. On the other hand, in the blocked isocyanate composition according to the present invention, ammonia used as the first blocking agent smoothly dissociates from the isocyanate groups when the blocked isocyanate composition reaches a predetermined temperature or higher by heating, so it is possible to maintain a high NCO of the isocyanate composition.

[0077] [Ratio of the first blocking agent and the second blocking agent] Ammonia as the first blocking agent and the second blocking agent (typically an amine-based blocking agent) can be, for example, in a molar ratio of 30:70, and in extreme cases, can range from 99:1 (99 parts ammonia to 1 part amine-based blocking agent) to 1:99 (1 part ammonia to 99 parts amine-based blocking agent). However, the inventors have actually confirmed that the blocked isocyanate composition of the present invention is difficult or impossible to solidify when only the second blocking agent is used as the blocking agent (i.e., when the second blocking agent is 100% as the blocking agent and the ammonia of the first blocking agent is 0%). That is, the blocked isocyanate composition of the present invention is characterized in that ammonia as the first blocking agent is essential and the first blocking agent is used in combination with the second blocking agent.

[0078] In addition, the inventors have actually confirmed that the blocked isocyanate composition of the present invention becomes easier and more certain to solidify as the relative content of ammonia as the first blocking agent as the blocking agent increases (i.e., as the ratio of ammonia as the first blocking agent in the total amount of ammonia as the first blocking agent and the second blocking agent (such as an amine-based blocking agent) increases). For example, when the blocked isocyanate composition of the present invention uses the first blocking agent (a blocking agent composed of ammonia) and the second blocking agent (such as an amine-based blocking agent) in combination as the blocking agent, the closer the content of the first blocking agent (ammonia) is to 100% with respect to the total amount of the blocking agent (i.e., the ratio to the total amount of the blocking agent which is the total amount of the first blocking agent and the second blocking agent), the more firmly it can be solidified. However, in that case, the resulting blocked isocyanate composition becomes very difficult to melt.

[0079] On the one hand, the inventors of the present invention have confirmed that when hexamethylene diisocyanate (HDI) is used as the isocyanate compound and a first blocking agent composed of ammonia (a blocking agent composed of ammonia) and a second blocking agent (for example, an amine-based blocking agent) are used in combination as the blocking agent, as long as even a small amount of ammonia is contained, the blocked isocyanate composition solidifies into a solid (that is, solidifies). On the other hand, the inventors of the present invention have confirmed that when hexamethylene diisocyanate (HDI) is used as the isocyanate compound and the blocking agent composed of ammonia is not used in combination, for example, when an amine-based blocking agent is used alone (that is, when no blocking agent composed of ammonia is contained at all), the blocked isocyanate composition becomes liquid without solidifying (that is, does not solidify). Furthermore, according to the findings of the inventors of the present invention, in the blocked isocyanate composition of the present invention, as the content of the first blocking agent (ammonia) in the blocking agent increases and approaches 100%, the reactivity with the polyol deteriorates, and after the blocking of ammonia as the first blocking agent is removed from the isocyanate group (NCO group) of the isocyanate compound (such as HDI), the isocyanate compound is more likely to self-polymerize due to the reaction of ammonia.

[0080] Therefore, in order to ensure sufficient reactivity with the polyol, the blocked isocyanate composition of the present invention essentially comprises reducing the content ratio of ammonia as the first blocking agent (from 100%) and using in combination an amine-based blocking agent or the like as the second blocking agent. As will be described later, in order to achieve complete "solidification", the blocked isocyanate composition of the present invention sets the ratio of ammonia and amine used in combination as the first and second blocking agents to a predetermined ratio (any ratio within the range of ammonia:amine = 10:90 to 60:40, preferably ammonia:amine = 30:70 or ammonia:amine = 20:80 (or any ratio within the range of ammonia:amine = 30:70 to 20:80)).

[0081] In addition, after solidification, the blocked isocyanate composition of the present invention needs to be pulverized into a fine powder or powder form by a pulverization process so as to have the particle size required for the powder composition to be mixed. However, for such fine pulverization or the like, the blocked isocyanate composition of the present invention needs to ensure that its hardness is above a certain level. Therefore, from this perspective, the blocked isocyanate composition of the present invention has a content of the second blocking agent (amine-based blocking agent) of 60% or more. From this perspective, the content of the second blocking agent (amine-based blocking agent) in the blocked isocyanate composition of the present invention is preferably 60% to 80%, but it can also be 80% or more, and can also be 90%. On the other hand, from this perspective, if the content of the second blocking agent (amine-based blocking agent) in the blocked isocyanate composition of the present invention is less than 60%, for example, 50% or 50% or less, as a result, the ammonia content of the first blocking agent increases to 50% or 50% or more, so that the blocked isocyanate composition is likely to self-polymerize after thermal dissociation of the blocking agent.

[0082] The weight loss (weight loss rate) during curing of the blocked isocyanate composition according to Examples 1-3 of the present invention is, for example, 28%.

[0083] As described above, the blocked isocyanate composition of the present invention can be smoothly mixed with the polyol component even when HDI is used as the isocyanate component by using the first blocking agent and the second blocking agent in combination, and becomes a blocked isocyanate composition that can be surely solidified and powdered after heating. Here, as long as the blocked isocyanate composition of the present invention is an isocyanate compound other than IPDI as the isocyanate component, any isocyanate compound can be used for solidification. Regarding monomeric MDI, as described above, it can be solidified even when ammonia is not used as the blocking agent, but there is a problem of yellowing.

[0084] Here, the mechanism of solidification of the block isocyanate composition of the present invention can be considered to be due to crystallization, but can also be considered to be due to aggregation and / or precipitation. This will be described in detail later.

[0085] [Solidification (Crystallization)] As described above, the block isocyanate composition of the present invention can achieve solidification and solid-state formation as the finally prepared block isocyanate composition even when using isocyanate compounds such as HDI, which were conventionally difficult to solidify, as the isocyanate compound, by using ammonia as the first blocking agent and an amine-based blocking agent as the second blocking agent in combination. However, the mechanism of this solidification and solid-state formation is considered to be as follows. In the present invention, "solidification" refers to the state of being "solidified" to a desired order by means of pulverization such as a pulverizer at normal temperature (for example, an ambient temperature in the vicinity of about 25°C, or an ambient temperature of 20°C ± 15°C (5 to 35°C) according to Japanese Industrial Standard (JIS Z 8703)) as the final product or end product. Therefore, the "solidified" block isocyanate composition in the present invention (sometimes referred to as "solidified block isocyanate composition" in these documents) refers to the block isocyanate composition solidified to a state where it can be pulverized or finely pulverized to a desired order by means of pulverization such as a pulverizer at normal temperature as the final product or end product. That is, even substances (objects) generally regarded as solids such as wax and rubber, if they cannot be pulverized or finely pulverized by means of pulverization such as a pulverizer at normal temperature, their solidification is not included in the "solidification" of the present invention.

[0086] Here, the solidified block isocyanate composition of the present invention is finally in a "solidified" state as described above so that it can be ground to a predetermined particle size by a grinder either alone (or even in a state mixed with a solid polyol). Therefore, for the solidification (solidification as a grindable solid) of such a block isocyanate composition of the present invention, the presence of three elements, namely hardness, crystallization, and glass transition temperature (Tg) in the final product is necessary. Wax and rubber do not satisfy the "solidification" conditions of the present invention in this regard. Also, in the solidification of the block isocyanate composition of the present invention, the glass transition temperature (Tg) needs to be in a temperature range higher than room temperature.

[0087] Also, when manufacturing a powder coating agent or the like using the block isocyanate composition according to the present invention, when using, for example, a polyester polyol as the polyol, as described above, the melting point of the polyester polyol is slightly less than 120°C. The ground product of the solidified block isocyanate composition according to the present invention (hereinafter sometimes referred to as "powdered block isocyanate composition") will be mixed at a temperature adjusted to the temperature at which the polyester polyol softens, that is, at a temperature around about 120°C. Here, the powdered block isocyanate composition according to the present invention has a melting temperature (melting point) in a low temperature range corresponding to the melting temperature (melting point) of the polyester polyol (specifically, as shown in the examples described later, considerably lower than the melting point of the polyester polyol). Therefore, in the temperature range around 120°C, which is the melting point of the polyester polyol, it can melt without problems and can be smoothly mixed with the polyester polyol.

[0088] And the blocked isocyanate composition according to the present invention is a solid formed by the above solidification. In this regard, this solidification and solid state formation can be considered to be due to either aggregation or crystallization of the blocked isocyanate composition. However, according to various experimental results conducted by the present inventors, this solidification and solid state formation can be considered to be due to crystallization of the blocked isocyanate composition. That is, according to various experimental results conducted by the present inventors, when the blocked isocyanate composition according to the present invention is finally solidified and solidified, (although it is difficult to determine whether it is actually crystallized), it can be confirmed that the structure is regularized and firmly solidified, and since the glass transition point (Tg) actually appears, it can be considered to be crystallized, and it can be considered that solidification (in the above sense) is realized by this crystallization. That is, since the Tg (glass transition point) in the solidified blocked isocyanate composition in this case can be considered to be almost the same as the softening point of the solidified blocked isocyanate composition, the fact that the Tg (glass transition point) appears in the solidified blocked isocyanate composition means that the solidified blocked isocyanate composition is in a state where the Tg (glass transition point) occurs and there is a softening point (although the melting point is unknown). In the case of aggregation, the Tg (glass transition point) does not appear. Therefore, the solidified blocked isocyanate composition according to the present invention can be considered to be crystallized and solidified.

[0089] [Glass Transition Point and Crystallization] Regarding the solidification by crystallization of the block isocyanate composition according to the present invention as described above, the inventors have confirmed it through experiments using DSC (Differential Scanning Calorimetry). That is, as shown in FIG. 11, according to the DSC chart obtained in the experiment, the glass transition point (Tg) of the solidified block isocyanate composition according to the present invention (typically, the solidified block isocyanate composition of the examples described later) is 65.9 °C, and the melting point (mp) is 73.0 °C. That is, since the glass transition point (Tg) of the solidified block isocyanate composition according to the present invention could be clearly measured by DSC, it can be said that the solidified block isocyanate composition according to the present invention is crystallized and solidified by this crystallization.

[0090] As described above, the block isocyanate composition of the present invention is, for example, a nurate (isocyanurate) of isocyanate and / or an adduct of isocyanate.

[0091] [Manufacturing method (preparation method)] The block isocyanate composition of the present invention is prepared by putting a predetermined isocyanate compound into a predetermined solvent, then adding a second blocking agent (for example, an amine-based blocking agent), and then adding a first blocking agent (ammonia), so that the isocyanate component precipitates (or crystallizes) and solidifies in the solvent. Therefore, thereafter, the solid matter precipitated in the solvent is volatilized to obtain a solidified block isocyanate composition (that is, the above-mentioned solidified block isocyanate composition). Thereafter, the solidified block isocyanate composition is pulverized to a desired particle size to obtain a desired powdery block isocyanate composition.

[0092] As described above, the blocked isocyanate composition of the present invention obtained as described above comprises a first terminal structure in which a part of the terminal isocyanate groups (NCO groups) of the isocyanate component (isocyanate compound) (the remaining NCO groups other than the NCO groups blocked by the second blocking agent as described above) are protected (blocked) by ammonia as the first blocking agent, and a second terminal structure in which a part of the terminal isocyanate groups (NCO groups) of the isocyanate component (isocyanate compound) (the NCO groups blocked by the second blocking agent before being blocked by the first blocking agent) are protected (blocked) by the second blocking agent.

[0093] That is, according to the method for producing a blocked isocyanate composition of the present invention, a predetermined isocyanate compound is put into a predetermined solvent to prepare a solution of the isocyanate compound (hereinafter referred to as "isocyanate solution"), and then a second blocking agent (for example, an amine-based blocking agent) is put into the isocyanate solution and mixed to block a part of the NCO groups of the isocyanate compound in the isocyanate solution with the second blocking agent. Next, a first blocking agent (ammonia) is put into the isocyanate solution and mixed to block the remaining NCO groups (NCO groups not blocked by the second blocking agent) of the isocyanate compound in the isocyanate solution with the first blocking agent.

[0094] <Reaction order of blocking> Regarding the reaction order of the NCO groups of the isocyanate compound with the first blocking agent and the second blocking agent in this case, the reaction order is as follows. That is, in the method for producing the blocked isocyanate composition of the present invention, first, the second blocking agent is first added to the isocyanate solution and mixed. At this time, for example, the case where an isocyanurate form (trimer) of isocyanate is used as the isocyanate compound and an amine-based blocking agent is mixed as the second blocking agent will be described. For the sake of convenience in explanation, the amine-based blocking agent may simply be referred to as "amine". In this case, one amine of the amine-based blocking agent first adds to one of the three NCO groups of each isocyanate compound (trimer) molecule in the isocyanate solution (that is, one by one to each molecule of the isocyanate compound) to block the NCO group. At this time, in one molecule of the isocyanate compound (trimer), there is a place where an amine is attached (one NCO group blocked by the addition of an amine) and a place where an amine is not attached (two NCO groups not blocked by the amine). That is, at this time, in the case of the trimeric isocyanate compound, for one molecule, one of the three NCO groups is blocked by the amine, while the remaining two NCO groups are in an unblocked state.

[0095] Next, when the reaction of the amine with the trimer of the isocyanate compound proceeds in the isocyanate solution, a second amine adds to the two unblocked NCO groups (the remaining unblocked NCO groups) in one molecule of the isocyanate compound (trimer) to block the NCO groups. At this time, in one molecule of the isocyanate compound (trimer), there is a place where an amine is attached (two NCO groups blocked by the addition of an amine) and a place where an amine is not attached (one NCO group not blocked by the amine). That is, at this time, in the case of the trimeric isocyanate compound, for one molecule, two of the three NCO groups are blocked by the amine, while the remaining one NCO group is in an unblocked state.

[0096] At this time, in the isocyanate solution, the reaction of the amine with the trimer of the isocyanate compound further proceeds, and the third amine may be added to and block the last unblocked NCO group in one molecule of the isocyanate compound (trimer). That is, in this case, in one molecule of the isocyanate compound (trimer), amines are added to and block all three NCO groups. In this case, when an amine-based blocking agent is first mixed into the isocyanate solution, as a whole, the isocyanate compound has two types of molecules: one type is a molecule of the isocyanate compound in which amines are added to and block two of the three NCO groups in one molecule of the isocyanate compound (that is, one NCO group is in a state not blocked by an amine), and the other type is a molecule of the isocyanate compound in which amines are added to and block all three NCO groups in one molecule of the isocyanate compound (that is, all three NCO groups are blocked by amines and there is no unblocked NCO group).

[0097] Next, when ammonia as the first blocking agent is added to and mixed with the isocyanate solution, ammonia reacts with and adds to the remaining one NCO group of the isocyanate compound (trimer) in which two NCO groups are blocked by amines as described above (that is, one NCO group is in an unblocked state), and becomes a primary amine (NH2) to block the NCO group by a urea terminal structure, thereby blocking the remaining one NCO group.

[0098] At this time, as described above, when amines are added to and block two of the three NCO groups in one molecule of the isocyanate compound (trimer), ammonia is added to and blocks the third NCO group (with a urea terminal structure formed by a primary amine). For one molecule of the isocyanate compound, two of the three NCO groups are blocked by amines, and the remaining one NCO group is blocked by ammonia (a urea terminal structure formed by a primary amine).

[0099] That is, in this case, among the three NCO groups of one molecule of the isocyanate compound, 2 / 3 of the NCO groups are blocked by the attachment of an amine (that is, 2 / 3 of the NCO groups of one molecule of the isocyanate compound in the state where nothing is attached are blocked by the amine), and ammonia (urea terminal structure by primary amine) is attached to the remaining 1 / 3 of the NCO groups to block them (that is, the remaining 1 / 3 of the NCO groups are blocked by ammonia (urea terminal structure by primary amine)).

[0100] Also, as described above, at the stage where ammonia is mixed into the isocyanate solution, as a whole of the isocyanate compound, among the three NCO groups of each molecule of the isocyanate compound, there are those in which an amine is added and blocked to the third NCO group, and those in which an amine is not added to the third NCO group and the third NCO group remains. In this case, ammonia (urea terminal structure by primary amine) (added after the amine) is added to and blocks the third NCO group of the remaining isocyanate compound at this stage.

[0101] <Relationship between ammonia addition and solidification> Here, in the method for producing the blocked isocyanate composition of the present invention, first, when an amine is put into the isocyanate solution first, the amine attaches evenly to the NCO groups of the isocyanate compound (blocks the NCO groups evenly), and then, by putting ammonia into the isocyanate solution, ammonia (urea terminal structure by primary amine due to ammonia) attaches to (blocks) the remaining NCO groups (without the attachment of the amine), so that, as described above, a crystal structure is generated in the blocked isocyanate composition (that is, the blocked isocyanate composition solidifies to become a solidified blocked isocyanate composition).

[0102] In this ammonia addition step, by introducing an excessive amount of ammonia gas into the isocyanate solution by blowing, ammonia is made to completely react with the NCO groups of the isocyanate compounds (without an attached amine). At this time, ammonia gas that does not attach to the NCO groups of the isocyanate compounds volatilizes. However, it has been confirmed that if the addition amount of the amine added prior to the addition of ammonia is excessively large compared to the addition amount of ammonia, ammonia does not volatilize at this time. (The ratio of amine to ammonia will be described later.) From this perspective, in the present invention, the addition amount of ammonia added to the isocyanate solution is not the calculated addition amount (hereinafter, "required addition amount") necessary to block the NCO groups of the isocyanate compounds remaining at the time of ammonia addition with ammonia, but an amount in excess of the required addition amount (hereinafter, "excessive addition amount"). Thus, by setting the addition amount of ammonia added to the isocyanate solution as the excessive addition amount, all of the NCO groups of the isocyanate compounds remaining when ammonia is added can be blocked with ammonia (urea terminal structure by primary amine). At this time, the ammonia remaining without contributing to the blocking of the NCO groups of the isocyanate compounds volatilizes.

[0103] Also, according to the method for producing the blocked isocyanate composition of the present invention, when adding this ammonia to block the remaining NCO groups of the isocyanate compound, a crystal structure is laminated on the blocked isocyanate compound. And due to this laminated crystal structure, as described above, a solidified blocked isocyanate composition is produced.

[0104] [Ratio of Amine to Ammonia] Regarding the blocked isocyanate composition of the present invention, the relative addition amount of the amine mixed in the isocyanate solution (relative to the addition amount of ammonia), that is, the ratio of ammonia as the first blocking agent to the amine as the second blocking agent, determines the amount of NCO groups of the isocyanate compound to which the amine is attached (that is, the amount of the remaining NCO groups to which no amine is attached). Therefore, in the present invention, the ratio of ammonia as the first blocking agent to the amine as the second blocking agent is set as follows.

[0105] That is, preferably, the ratio of ammonia to amine is ammonia:amine = 30:70, or ammonia:amine = 20:80. Alternatively, preferably, the ratio of ammonia to amine is any ratio within the range of ammonia:amine = 30:70 to 20:80. In addition, if only preparing the blocked isocyanate composition, it is also possible to set the ratio of ammonia to 99% (that is, ammonia:amine = 99:1 and minimize the ratio of amine to 1%), but such a blocked isocyanate composition does not react with the polyol. On the other hand, when the ratio of ammonia to amine is ammonia:amine = 10:90 (that is, when maximizing the ratio of amine), although it takes time for the blocked isocyanate composition to solidify, it can finally solidify. Therefore, in the case of the blocked isocyanate composition of the present invention, the practical range of the ratio of ammonia to amine is any ratio within the range of ammonia:amine = 10:90 to 60:40.

[0106] [Self-polymerization] Next, the mechanism of self-polymerization caused by the above ammonia will be described in detail. As shown in FIG. 12, when ammonia as the first blocking agent is blown into the isocyanate solution (as ammonia gas) in the blocked isocyanate composition of the present invention, the isocyanate compound becomes a blocked isocyanate with a terminal NH2 (that is, a terminal urea structure), as shown in FIG. 12. This is as described in Patent No. 6158776 owned by the applicant of the present application.

[0107] That is, at this stage, since the terminal of the isocyanate compound (blocked isocyanate compound) is a primary amine, as shown in FIG. 13, when the isocyanate compound is heated and the block of the primary amine is removed from the NCO group and the NCO group (isocyanate group) is revived, the isocyanate having the NCO group from which the block has been removed reacts with the primary amine of the isocyanate whose block has not been removed from the NCO group, and self-polymerization proceeds. Since the reaction between the primary amine and the isocyanate (NCO group) is much faster than the reaction between the hydroxyl group and the isocyanate, it is considered that self-polymerization preferentially reacts even if a hydroxyl group is present around. The reaction or mechanism in this case is schematically illustrated in FIG. 13.

[0108] Also, as described above, in the blocked isocyanate composition of the present invention, as the isocyanate component, in addition to the nurate form of isocyanate, an adduct form of isocyanate can also be used. For example, when this blocked isocyanate composition is mixed with a polyol, it can be configured such that the nurate form of isocyanate chemically bonds to the polyol.

[0109] [When an oxime-based blocking agent is used as the second blocking agent] In the blocked isocyanate composition of the present invention, when an oxime-based blocking agent is used as the second blocking agent, since oxime is a blocking agent that is less likely to crystallize, if ammonia as the first blocking agent is not added in an amount of 50% or more, it is considered that the finally obtained blocked isocyanate composition will not solidify sufficiently. Therefore, in the blocked isocyanate composition of the present invention, when an oxime-based blocking agent is used as the second blocking agent, the practical range is ammonia:oxime = 50:50 to 60:40. If a blocked isocyanate composition is prepared (without considering sufficient solidification), ammonia:oxime = 90:10 is also possible. In the blocked isocyanate composition of the present invention, the case where an oxime-based blocking agent is used as the second blocking agent will be described in the description of the following examples (as Example 5).

[0110] [Specific examples of amine-based blocking agents] As the amine-based blocking agent, the following can be preferably used. That is, as the amine-based blocking agent as the second blocking agent, dibutylamine, diphenylamine, aniline, N-methylaniline, carbazole, bis(2,2,6,6-tetramethylpiperidinyl)amine, di-n-propylamine, diisopropylamine, isopropylethylamine, 2,2,4- or 2,2,5-trimethylhexamethyleneamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis(3,5,5-trimethylcyclohexyl)amine, piperidine, 2,6-dimethylpiperidine, t-butylmethylamine, t-butylethylamine, t-butylpropylamine, t-butylisopropylamine, t-butylbutylamine, t-butylbenzylamine, t-butylphenylamine, 2,2,6-trimethylpiperidine, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidin-4-one, (dimethylamino)-2,2,6,6-tetramethylpiperidine, 6-methyl-2-piperidine, 6-aminocaproic acid, and the like can be preferably used.

[0111] [Other second blocking agents] Examples of the blocking agent for the blocked isocyanate composition include caproic blocking agents and phenolic blocking agents. However, in the blocked isocyanate composition of the present invention, as the second blocking agent, it is preferable to use those other than caproic blocking agents and phenolic blocking agents, such as the above amine-based blocking agents and oxime-based blocking agents. [Examples]

[0112] Hereinafter, the manufacturing method (manufacturing example) of the blocked isocyanate composition according to the examples of the present invention, the manufacturing method (manufacturing example) of the powder composition containing the blocked isocyanate composition, and the manufacturing method (manufacturing example) of the blocked isocyanate composition according to the comparative examples and the manufacturing method (manufacturing example) of the powder composition containing the blocked isocyanate composition are shown respectively. The blocked isocyanate composition and the powder composition containing the blocked isocyanate according to the examples of the present invention are compared with the blocked isocyanate composition and the powder composition containing the blocked isocyanate composition according to the comparative examples, and the specific action effects thereof are specifically described. In the following, "parts" and "%" are "parts by weight" and "weight%" unless otherwise specified.

[0113] [Example 1] a) First step First, 68.5 g of HDI nurate (DURANATE TKA100 manufactured by Asahi Kasei Corporation) as an isocyanate component was placed in a separable flask equipped with a reflux condenser, and dissolved in 68.5 g of tetrahydrofuran (hereinafter sometimes referred to as "THF") as a solvent to prepare a first solution (isocyanate solution) (dissolution step).

[0114] b) Second step Next, this first solution is stirred at a temperature of 50°C. At this time, the rotation speed of the stirrer is set to 500 rpm (stirring step). Into the first solution in this stirred state, 8.2 g of diisopropylamine (DiPA) (manufactured by Tokyo Chemical Industry Co., Ltd.), which is an amine-based blocking agent as the second blocking agent, is gradually dropped and stirred for 10 minutes (10 min) (stirring and dropping step). As a result, a part of the NCO groups of the isocyanate component composed of HDI is blocked by diisopropylamine, and as a result, a first blocked isocyanate solution is obtained (first blocking step).

[0115] In this first isocyanate solution, as described above, in the whole of the isocyanate component (HDI as an isocyanate compound), in one molecule of HDI, 2 out of 3 NCO groups are blocked by diisopropylamine. Also, at this time, as described above, it is considered that there may be cases where all 3 NCO groups in one molecule of HDI in the whole of the isocyanate compound HDI are blocked by diisopropylamine.

[0116] That is, at this time, in the whole of the isocyanate component (HDI as an isocyanate compound), for each molecule of HDI, 2 out of 3 NCO groups are blocked by diisopropylamine in a ratio corresponding to the ratio of the second blocking agent (DiPA) to the first blocking agent (ammonia). On the other hand, in the whole of the isocyanate compound HDI, for each molecule of HDI, 1 out of 3 NCO groups remains unblocked by diisopropylamine. For example, when the ratio of the first blocking agent (ammonia) to the second blocking agent (DiPA) is 30:70 or 20:80, in the whole of the isocyanate compound HDI, for each molecule of HDI, 2 out of 3 NCO groups are blocked by diisopropylamine, while 1 out of 3 NCO groups remains unblocked by diisopropylamine.

[0117] Then, the NCO value of the thus obtained first blocked isocyanate solution was measured (first NCO measurement step).

[0118] c) Third step Thereafter, ammonia gas was blown into the first blocked isocyanate solution to add ammonia as the first blocking agent, whereby the remaining NCO groups (the remaining one NCO group) in each molecule of HDI in the whole of the HDI as the isocyanate compound, which were not blocked by diisopropylamine, were blocked (with a urea terminal structure by a primary amine) by ammonia, and as a result, a second blocked isocyanate solution was obtained (second blocking step).

[0119] In this second isocyanate solution, as described above, in one molecule of HDI in the whole of the isocyanate component (HDI as the isocyanate compound), two of the three NCO groups are blocked by diisopropylamine, and the remaining one of the three NCO groups is blocked by ammonia (a urea terminal structure by a primary amine resulting from ammonia).

[0120] That is, at this time, in the whole isocyanate component (HDI as an isocyanate compound), for each molecule of HDI, two of the three NCO groups are blocked by diisopropylamine and the remaining one of the three NCO groups is blocked by ammonia (urea terminal structure formed by a primary amine derived from ammonia) in a ratio corresponding to the ratio of the second blocking agent (DiPA) to the first blocking agent (ammonia). For example, when the ratio of the first blocking agent (ammonia) to the second blocking agent (DiPA) is 30:70 or 20:80, in the whole HDI as an isocyanate compound, for each molecule of HDI, two of the three NCO groups are blocked by diisopropylamine, while one of the three NCO groups is blocked by ammonia (urea terminal structure formed by a primary amine derived from ammonia).

[0121] Then, the NCO value of the blocked isocyanate solution thus obtained was measured (second NCO measurement step), and it was confirmed that the NCO measured value was "0 (zero)" (residual NCO confirmation step).

[0122] d) Fourth step Thereafter, stirring was stopped and it was allowed to stand. (That is, ammonia was added and stirring was continued until the NCO value of the blocked isocyanate solution became "0 (zero)". Then, a blocked isocyanate composed of blocked HDI precipitated in the blocked isocyanate solution (precipitation step).

[0123] e) Fifth step Thereafter, this blocked isocyanate solution was subjected to solid-liquid separation by filter filtration to obtain a solid of the blocked isocyanate (first solid). This first solid contains a certain amount of solvent inside. Next, THF was removed from this solid of the blocked isocyanate by drying under vacuum at normal temperature to obtain a solid blocked isocyanate (solidification step).

[0124] f) Step 6 Subsequently, this solid block isocyanate was pulverized using a small pulverizer such as a hammer mill to obtain a powder having a predetermined particle size (powder-like block isocyanate composition) (pulverization step).

[0125] [Measurement of properties] The melting point and glass transition point of this powder-like block isocyanate composition were measured using a DSC (differential scanning calorimeter, manufactured by PerkinElmer Japan Co., Ltd.). The measurement results are shown in FIG. 10.

[0126] Next, the obtained powder-like block isocyanate, Yupika Coat GV110 (manufactured by Nippon Yupika Co., Ltd.) as a polyol (polyester polyol), and 1% of DBTDL (dibutyltin dilaurate) as a catalyst in the whole were put into an extruder (small twin-screw extruder), and these mixtures were kneaded and extruded at 120° C. to obtain a rod-shaped solid (kneading and extrusion step). This rod-shaped solid corresponds to the solidified product of the powder composition containing the block isocyanate composition of the present invention.

[0127] For this rod-shaped solid, after heat treatment under heating conditions of 150° C. for 30 minutes (30 min), acetone extraction was performed using a Soxhlet type extractor, and the gel fraction as a characteristic value was measured. The measurement results (measured values) are shown in FIG. 10. In addition, as other characteristic values (measured values), the glass transition point, melting point, and blocking agent dissociation temperature of the block isocyanate composition are also shown in FIG. 10.

[0128] [Examples 2-4] Examples 2 to 4 are different from Example 1 only in the addition amount of diisopropylamine as the second blocking agent. Therefore, in Examples 2 to 4, only the steps corresponding to the first step - the third step of Example 1 will be described.

[0129] [Example 2] a) The first step First, 68.5 g of HDI nurate (DURANATE TKA100 manufactured by Asahi Kasei Corporation), which is an isocyanate component, was placed in a separable flask equipped with a reflux condenser, and dissolved in 68.5 g of tetrahydrofuran (hereinafter sometimes referred to as "THF") as a solvent to prepare a first solution (isocyanate solution) (dissolution step).

[0130] b) Second step Next, this first solution was stirred at a temperature of 50°C. At this time, the rotation speed of the stirrer was set to 500 rpm (stirring step). 16.4 g (twice the amount in Example 1) of diisopropylamine (DiPA) (manufactured by Tokyo Chemical Industry Co., Ltd.), which is an amine-based blocking agent as the second blocking agent, was gradually dropped into the first solution in this stirred state and stirred for 10 minutes (10 min) (stirring and dropping step). As a result, a part of the NCO groups of the isocyanate component composed of HDI was blocked by diisopropylamine, and as a result, a first blocked isocyanate solution was obtained (first blocking step).

[0131] In this first isocyanate solution, as described in Example 1, in the whole of the isocyanate component (HDI as an isocyanate compound), in one molecule of HDI, 2 out of 3 NCO groups are blocked by diisopropylamine. Also, at this time, as described above, it is considered that there may be cases where all 3 NCO groups in one molecule of HDI in the whole of the isocyanate compound HDI are blocked by diisopropylamine.

[0132] Then, the NCO value of the first blocked isocyanate solution thus obtained was measured (first NCO measurement step). This NCO value becomes a constant value in about 10 minutes (10 min).

[0133] c) Third step Thereafter, ammonia gas was blown into the first blocked isocyanate solution to add ammonia as the first blocking agent, whereby the NCO groups of the remaining isocyanate components (unblocked isocyanate components) not blocked by diisopropylamine were blocked by ammonia, and as a result, a second blocked isocyanate solution was obtained (the second blocking step).

[0134] As described in Example 1, in this second isocyanate solution, out of the three NCO groups in one molecule of HDI in the whole isocyanate component (HDI as the isocyanate compound), two of the three NCO groups are blocked by diisopropylamine, and the remaining one of the three NCO groups is blocked by ammonia (urea terminal structure by the primary amine resulting from ammonia).

[0135] Then, the NCO value of the blocked isocyanate solution thus obtained was measured (the second NCO measurement step), and it was confirmed that the NCO measurement value was "0 (zero)" (the residual NCO confirmation step).

[0136] [Example 3] a) The first step First, 68.5 g of HDI nurate (DURANATE TKA100 manufactured by Asahi Kasei Corporation) as the isocyanate component was placed in a separable flask equipped with a reflux condenser and dissolved in 68.5 g of tetrahydrofuran (hereinafter sometimes referred to as "THF") as the solvent to prepare a first solution (isocyanate solution) (dissolution step).

[0137] b) The second step Next, this first solution is stirred at a temperature of 50°C. At this time, the rotation speed of the stirrer is set to 500 rpm (stirring step). Into the first solution in this stirred state, 25 g of diisopropylamine (DiPA) (manufactured by Tokyo Chemical Industry Co., Ltd.), which is an amine-based blocking agent as the second blocking agent, about three times the amount of Example 1, is gradually dropped and stirred for 10 minutes (10 min) (stirring and dropping step). As a result, a part of the isocyanate groups of the isocyanate component composed of HDI, that is, the NCO groups of some of the isocyanate components, are blocked by diisopropylamine, and as a result, a first blocked isocyanate solution is obtained (first blocking step).

[0138] In this first isocyanate solution, as described in Example 1, in the whole of the isocyanate component (HDI as the isocyanate compound), in one molecule of HDI, two of the three NCO groups are blocked by diisopropylamine. Also, at this time, as described above, it is considered that there may be cases where all three NCO groups in one molecule of HDI in the whole of the HDI as the isocyanate compound are blocked by diisopropylamine.

[0139] Then, the NCO value of the first blocked isocyanate solution thus obtained is measured (first NCO measurement step). This NCO value becomes a constant value in about 10 minutes (10 min).

[0140] c) Third step Thereafter, in order to add ammonia as the first blocking agent to the first blocked isocyanate solution, ammonia gas is blown in. As a result, the NCO groups of the remaining isocyanate components (unblocked isocyanate components) that were not blocked by diisopropylamine are blocked by ammonia, and as a result, a second blocked isocyanate solution is obtained (second blocking step).

[0141] In this second isocyanate solution, as described in Example 1, in one molecule of HDI out of the entire isocyanate component (HDI as the isocyanate compound), two of the three NCO groups are blocked by diisopropylamine, and the remaining one of the three NCO groups is blocked by ammonia (urea terminal structure by the primary amine resulting from ammonia).

[0142] Then, the NCO value of the blocked isocyanate solution thus obtained was measured (second NCO measurement step), and it was confirmed that the NCO measured value was "0 (zero)" (residual NCO confirmation step).

[0143] [Example 4] a) First step First, 68.5 g of HDI nurate (DURANATE TKA100 manufactured by Asahi Kasei Corporation) as the isocyanate component was placed in a separable flask equipped with a reflux condenser and dissolved in 68.5 g of tetrahydrofuran (hereinafter sometimes referred to as "THF") as the solvent to prepare a first solution (isocyanate solution) (dissolution step).

[0144] b) Second step Next, this first solution was stirred at a temperature of 50°C. At this time, the rotation speed of the stirrer was set to 500 rpm (stirring step). 32.8 g (4 times the amount in Example 1) of diisopropylamine (DiPA) as an amine-based blocking agent, which is a second blocking agent, was gradually dropped into the first solution in this stirred state and stirred for 10 minutes (10 min) (stirring and dropping step). As a result, the NCO groups of a part of the isocyanate component composed of HDI were blocked by diisopropylamine, and a first blocked isocyanate solution was obtained (first blocking step).

[0145] In this first isocyanate solution, as described in Example 1, in the whole isocyanate component (HDI as the isocyanate compound), in one molecule of HDI, 2 out of 3 NCO groups are blocked by diisopropylamine. Also, at this time, as described above, it is considered that there may be a case where all 3 NCO groups in one molecule of HDI in the whole HDI as the isocyanate compound are blocked by diisopropylamine.

[0146] Then, the NCO value of the first blocked isocyanate solution thus obtained was measured (the first NCO measurement step). This NCO value becomes a constant value in about 10 minutes (10 min).

[0147] c) The third step Thereafter, in order to add ammonia as the first blocking agent to the first blocked isocyanate solution, ammonia gas was blown in. As a result, the remaining isocyanate component (unblocked isocyanate component) whose NCO groups were not blocked by diisopropylamine was blocked by ammonia, and as a result, a second blocked isocyanate solution was obtained (the second blocking step).

[0148] In this second isocyanate solution, as described in Example 1, in the whole isocyanate component (HDI as the isocyanate compound), in one molecule of HDI, 2 out of 3 NCO groups are blocked by diisopropylamine, and the remaining 1 out of 3 NCO groups is blocked by ammonia (urea terminal structure by the primary amine resulting from ammonia).

[0149] Then, the NCO value of the blocked isocyanate solution thus obtained was measured (the second NCO measurement step), and it was confirmed that the NCO measurement value was "0 (zero)" (the remaining NCO confirmation step).

[0150] [Example 5] a) The first step First, 68.5 g of HDI nurate (DURANATE TKA100 manufactured by Asahi Kasei Corporation), which is an isocyanate component, was placed in a separable flask equipped with a reflux condenser and dissolved in 68.5 g of tetrahydrofuran (hereinafter sometimes referred to as "THF") as a solvent to prepare a first solution (isocyanate solution) (dissolution step).

[0151] b) Second step Next, this first solution was stirred at a temperature of 50°C. At this time, the rotation speed of the stirrer was set to 500 rpm (stirring step). 15.4 g of methyl ethyl ketoxime (MEKO), which is an oxime-based blocking agent as the second blocking agent, was gradually dropped into the first solution in this stirred state and stirred for 10 minutes (10 min) (stirring and dropping step). As a result, a part of the NCO groups (in one molecule of the isocyanate compound) of the isocyanate component composed of HDI was blocked by methyl ethyl ketoxime, and as a result, a first blocked isocyanate solution was obtained (first blocking step).

[0152] In this first isocyanate solution, it is considered that 1 or 2 of the 3 NCO groups in one molecule of HDI are blocked by MEKO in the whole of the isocyanate component (HDI as the isocyanate compound). Also, at this time, it is considered that there may be cases where all 3 NCO groups in one molecule of HDI are blocked by MEKO in the whole of the isocyanate compound HDI.

[0153] Then, the NCO value of the first blocked isocyanate solution thus obtained was measured (first NCO measurement step). This NCO value becomes a constant value in about 10 minutes (10 min).

[0154] c) Third step Thereafter, ammonia gas was blown into the first blocked isocyanate solution to add ammonia as the first blocking agent, whereby the remaining isocyanate components (unblocked isocyanate components) whose NCO groups were not blocked by MEKO were blocked by ammonia (urea terminal structure due to primary amine resulting from ammonia), and as a result, a second blocked isocyanate solution was obtained (second blocking step). At this time, the ratio of ammonia to MEKO was 50:50.

[0155] In this second isocyanate solution, it is considered that out of the three NCO groups in one molecule of HDI, one or two NCO groups are blocked by MEKO, and the remaining one or two of the three NCO groups are blocked by ammonia (urea terminal structure due to primary amine resulting from ammonia) in the entire isocyanate component (HDI as the isocyanate compound).

[0156] Then, the NCO value of the blocked isocyanate solution thus obtained was measured (second NCO measurement step), and it was confirmed that the NCO measured value was "0 (zero)" (residual NCO confirmation step).

[0157] The blocked isocyanate solution obtained as described above had an NCO content of 15.8%, a glass transition point (Tg) of 45°C, a melting point of 70°C, a dissociation temperature of the blocking agent of 140°C, a gel fraction (150°C · 30 min) of 22%, and a gel fraction (180°C · 30 min) of 72%.

[0158] [Comparative Example] a) First step First, 95.1 g of IPDI nurate (Desmodur Z 4470 BA manufactured by Sumika Covestro Urethane Co., Ltd.) as the isocyanate component was placed in a separable flask equipped with a reflux condenser and dissolved in 66.6 g of tetrahydrofuran (hereinafter sometimes referred to as "THF") as a solvent to prepare a first solution (isocyanate solution) (dissolution step).

[0159] b) Second step Next, this first solution is stirred at a temperature of 50°C. At this time, the rotation speed of the stirrer is set to 500 rpm (stirring step). Into the first solution in this stirred state, 33.9 g of ε-caprolactam (manufactured by Tokyo Chemical Industry Co., Ltd.) as a blocking agent is gradually added and stirred for 60 minutes (60 min) (stirring step). As a result, the NCO groups of the isocyanate component composed of IPDI are blocked by ε-caprolactam, and a blocked isocyanate solution is obtained (blocking step).

[0160] Then, the NCO value of the blocked isocyanate solution thus obtained is measured (NCO measurement step), and it is confirmed that the NCO measurement value is "0 (zero)" (residual NCO confirmation step).

[0161] d) Third step Thereafter, stirring is stopped, and the solvent is removed from the blocked isocyanate solution by vacuum drying at 50°C to obtain solid blocked isocyanate (solidification step).

[0162] f) Fourth step Thereafter, this solid blocked isocyanate is pulverized with a small pulverizer such as a hammer mill to obtain a powder with a predetermined particle size (powder-like blocked isocyanate composition) (pulverization step).

[0163] [Measurement of properties] The melting point and glass transition point of this powder-like blocked isocyanate composition were measured using a DSC (Differential Scanning Calorimeter, manufactured by PerkinElmer Japan Co., Ltd.). The measurement results are shown in Figure 10.

[0164] Next, the obtained powder-like blocked isocyanate, Yupica Coat GV110 (manufactured by Nippon Yupica Co., Ltd.) as a polyol (polyester polyol), and 1% of DBTDL (dibutyltin dilaurate) as a catalyst in the whole amount are put into an extruder (small twin-screw extruder), and these mixtures are kneaded and extruded at 120°C to obtain a rod-shaped solid (kneading and extrusion step).

[0165] For this rod-shaped solid, after heat treatment under heating conditions of 150°C for 30 minutes (30 min), acetone extraction was performed using a Soxhlet extractor, and the gel fraction as a characteristic value was measured. The measurement results (measured values) are shown in FIG. 10. In addition, as other characteristic values, the glass transition point, melting point, and blocking agent dissociation temperature of the block isocyanate composition are also shown in FIG. 10.

[0166] [Summary of characteristics] The characteristics of the block isocyanate composition according to the embodiments (Examples 1-4) of the present invention are as follows. That is, the block isocyanate composition according to the embodiments (Examples 1-4) of the present invention has a component of amine-blocked polyisocyanate (HDI), a property of being a white solid, and an NCO content of 15.7%.

[0167] [Usage method (usage example)] As shown in FIG. 1, the block isocyanate composition according to the present invention (the "BL-IS composition" in FIG. 1) is mixed with other components such as a predetermined polyol, a predetermined pigment, and a predetermined catalyst (a predetermined organometallic catalyst) to form the powder coating composition according to the present invention. After being coated on an adherend (coated object) by a predetermined spraying method (such as electrostatic coating) (spraying step), it is heated in a predetermined temperature range and baked (baking step), and then, after cooling for a predetermined time (cooling at room temperature) (cooling step), a coating film exhibiting the color of the corresponding pigment can be fixed on the surface of the adherend (that is, coated), thereby constituting a coated product.

[0168] [Curing characteristics] When the blocked isocyanate composition according to the present invention is mixed with a predetermined polyol and a predetermined catalyst (organometallic catalyst) to form the powder composition according to the present invention, it has the curing characteristics as shown in FIG. 2. That is, in FIG. 2, the gray range (the filled range above the curve in the figure, the region marked "standard curing conditions") is 80 parts by weight of GV-110 (polyester polyol: manufactured by Nippon Yupica Co., Ltd.) as the polyol, and 20 parts by weight of the blocked isocyanate composition according to the present invention (the blocked isocyanate compositions of Examples 1-3) and 1 part by weight of DBTDL (dibutyltin dilaurate) are mixed (i.e., mixed at a ratio of 80:20:1), and the curing characteristics are shown when the gel fraction of the mixture becomes 100% as the curing condition.

[0169] [Storage method] The powder composition according to the present invention is stored and preserved in a temperature environment of 30°C or lower so as not to cause blocking by the blocking agent.

[0170] [Details of characteristics (comparison with comparative examples)] Figure 3 shows a comparison of the properties of the blocked isocyanate compositions according to Examples 1 to 3 of the present invention (hereinafter simply referred to as "Examples") with the properties of the blocked isocyanate compositions of Comparative Example 1 and Comparative Example 2. Note that Comparative Example 1 and Comparative Example 2 described with reference to Figure 3 are different from the comparative examples described in comparison with Examples 1 to 4 above. That is, in the samples in Figure 3, "Examples" correspond to the blocked isocyanate compositions according to Examples 1 to 3 of the present invention (hereinafter sometimes referred to as "HDI / amine·ammonia blocked polyisocyanate"). Further, "Comparative Example 1" uses an isocyanurate of HDI as the isocyanate compound and uses isopropylamine (hereinafter sometimes simply referred to as "amine") alone as the blocking agent. That is, unlike Examples 1 to 4 above, Comparative Example 1 does not contain any ammonia as a blocking agent different from amine. Hereinafter, the blocked isocyanate composition of Comparative Example 2 may be simply referred to as "HDI / amine blocked polyisocyanate". Furthermore, "Comparative Example 2" corresponds to a blocked isocyanate composition (hereinafter sometimes referred to as "IPDI / ε-caprolactam blocked polyisocyanate") related to an isocyanate resin (manufactured by Kuraray Co., Ltd.) blocked with IPDI / ε-caprolactam. In the table, "N" and "NCO%" are in terms of KOH conversion.

[0171] Regarding the properties of the cured product of the powder composition containing the block isocyanate composition according to Examples 1 to 4 of the present invention as a curing agent, further explanation is as follows. The cured product can be embodied as the cured product of the powder composition shown in FIG. 2 using the block isocyanate composition according to Examples 1 to 3 ( "Examples") of the present invention shown in FIG. 3 above as a curing agent, and can be embodied as the cured product of the powder composition with the mixing ratio of GV-110 as a polyol, the block isocyanate composition of Examples 1-3 of the present invention, and DBTDL being 1:4:0.01. When the physical properties of the cured product in this case were measured, it was confirmed that the pencil hardness was 8H, the alkali resistance (by 5% NaOH rt / 240h) was good, the acid resistance (by 5% H2SO4 rt / 240h) was good, and the glass transition point (Tg) was 58°C. On the other hand, as a comparative example corresponding to this example, when the same properties were measured for Comparative Example 1 above, it was confirmed that the pencil hardness was 8H, the alkali resistance (by 5% NaOH rt / 240h) was good, the acid resistance (by 5% H2SO4 rt / 240h) was good, and the glass transition point (Tg) was 64°C. However, the inventors have confirmed by experimental results that the block isocyanate composition (HDI / amine block polyisocyanate) according to Comparative Example 1 uses amine alone as a blocking agent, so it is liquid and cannot be solidified. However, although the HDI / amine block polyisocyanate of Comparative Example 1 is liquid, the measurement of physical properties is possible in the same manner as the solid isocyanate composition (HDI / amine·ammonia block polyisocyanate) of the present invention, so it has been confirmed to have the above physical properties.

[0172] FIG. 4 shows the optimum catalyst amount of the powder composition containing the block isocyanate composition according to Examples 1 to 3 of the present invention as a curing agent. In FIG. 4, the heating condition is 150°C for 30 minutes. In this case, it can be seen that a catalyst amount of 0.5-1.0% is suitable (optimum) for the active ingredient.

[0173] Figure 5 shows a comparison of the BL-isocyanate residual rate (corrected) of the block isocyanate compositions according to Examples 1 to 3 of the present invention with the BL-isocyanate residual rate (corrected) of the block isocyanate compositions of the comparative examples. In the description with reference to Figure 5, "Example" corresponds to the "Example" (HDI / amine·ammonia-blocked polyisocyanate) described with reference to Figure 3, and "Comparative Example 1" and "Comparative Example 2" correspond to "Comparative Example 1" (HDI / amine-blocked polyisocyanate) and "Comparative Example 2" (IPDI / ε-caprolactam-blocked polyisocyanate) described with reference to Figure 3, respectively. That is, in Figure 5, two bar graphs are taken as a set (a pair), and a total of three sets of BL-isocyanate residual rates (corrected) of polyisocyanate compositions are shown. In Figure 5, the bar graph on the left side of the set shows the BL-isocyanate residual rate (corrected) of the HDI / amine·ammonia-blocked polyisocyanate according to the example of the present invention, the bar graph in the middle of the set shows the BL-isocyanate residual rate (corrected) of the HDI / amine-blocked polyisocyanate as Comparative Example 1, and the bar graph on the right side of the set shows the BL-isocyanate residual rate (corrected) of the IPDI / ε-caprolactam-blocked polyisocyanate as Comparative Example 2. Also, in the composition of the HDI / amine·ammonia-blocked polyisocyanate according to the example of the present invention, the white bar on the left side shows the BL-isocyanate residual rate (corrected) under the heating condition of 150 °C for 30 minutes, and the gray bar on the right side shows the BL-isocyanate residual rate (corrected) under the heating condition of 150 °C for 60 minutes. Also, in the composition of the HDI / amine-blocked polyisocyanate of Comparative Example 1, the white bar on the left side shows the BL-isocyanate residual rate (corrected) under the heating condition of 150 °C for 30 minutes, and the gray bar on the right side shows the BL-isocyanate residual rate (corrected) under the heating condition of 150 °C for 60 minutes. On the other hand, in the composition of the IPDI / ε-caprolactam-blocked polyisocyanate of Comparative Example 2, the white bar on the left side shows the BL-isocyanate residual rate (corrected) under the heating condition of 180 °C for 30 minutes, and the gray bar on the right side shows the BL-isocyanate residual rate (corrected) under the heating condition of 180 °C for 60 minutes.

[0174] That is, regarding the HDI / amine·ammonia-blocked polyisocyanate according to the example of the present invention and the HDI / amine-blocked polyisocyanate as Comparative Example 1, the blocking agent dissociates at a temperature of 150°C. However, regarding the IPDI / ε-caprolactam-blocked polyisocyanate of Comparative Example 2, the blocking agent dissociates at 180°C (i.e., it does not dissociate at 150°C).

[0175] From this, it can be seen that in the HDI / amine·ammonia-blocked polyisocyanate according to the example of the present invention, under the above heating conditions, NH3-BL (ammonia block) also dissociates and is involved in the curing of the cured product. On the other hand, regarding the IPDI / ε-caprolactam-blocked polyisocyanate of Comparative Example 2, it can be seen that ε-caprolactam does not dissociate at 150°C but dissociates at 180°C.

[0176] Figure 6 shows the properties of the blocked isocyanate compositions according to Examples 1 to 3 of the present invention at 100% gel fraction in comparison with the properties of the blocked isocyanate composition of the comparative example at 100% gel fraction. In the description with reference to Figure 6, "Example" corresponds to the "Example" (HDI / amine·ammonia blocked polyisocyanate) described with reference to Figure 3, and "Comparative Example 1" and "Comparative Example 2" correspond to "Comparative Example 1" (HDI / amine blocked polyisocyanate) and "Comparative Example 2" (IPDI / ε-caprolactam blocked polyisocyanate) described with reference to Figure 3, respectively. That is, in Figure 6, the upper curve (approximate curve connecting circular points) among the two left curves shows the properties of the HDI / amine·ammonia blocked polyisocyanate according to the example of the present invention at 100% gel fraction, the lower curve (approximate curve connecting square points) among the two left curves shows the properties of the HDI / amine blocked polyisocyanate as Comparative Example 1 at 100% gel fraction, and the single right curve (approximate curve connecting triangular points) shows the properties of the IPDI / ε-caprolactam blocked polyisocyanate of Comparative Example 2 at 100% gel fraction. From Figure 6, it can be seen that in the case of the HDI / amine·ammonia blocked polyisocyanate according to the example of the present invention, ammonia is difficult to dissociate in a short time. Also, from Figure 6, it can be seen that the HDI / amine·ammonia blocked polyisocyanate according to the example of the present invention can significantly shorten the curing time compared to the IPDI / ε-caprolactam blocked polyisocyanate of Comparative Example 2.

[0177] Figure 7 shows the molecular structure of the HDI-DiPA block portion (HDI blocked with diisopropylamine) of the blocked isocyanate composition according to the embodiment of the present invention.

[0178] Figure 8 shows the molecular structure of the HDI-ammonia block portion (where HDI is blocked with ammonia (terminal urea structure by primary amine)) of the blocked isocyanate composition according to the embodiment of the present invention. In FIG. 7, a state where all three NCO groups of the isocyanurate form (trimer) of HDI are blocked with diisopropylamine is depicted. In FIG. 8, a state where all three NCO groups of the isocyanurate form (trimer) of HDI are blocked with a terminal urea structure by a primary amine resulting from ammonia is depicted, but this is for the sake of convenience of explanation only. Actually, as shown in FIG. 9, basically, two of the three NCO groups of the isocyanurate form (trimer) of HDI are blocked with diisopropylamine, and the remaining one NCO group is blocked with a terminal urea structure by a primary amine resulting from ammonia.

[0179] [Specific effects] Further, according to the present invention, in a blocked isocyanate composition, a powder composition using the blocked isocyanate composition, a method for producing the blocked isocyanate composition, a method for producing the powder composition, and a powder coating agent such as a powder coating composition containing the blocked isocyanate composition, the following specific effects are exhibited. It is a powder at room temperature. It is difficult to contaminate the furnace interior. It has a high NCO. It has an effect performance equal to or better than that of conventional products. It has physical properties equal to or better than those of conventional products. The melting temperature is 100 ° C or lower. It is compatible with polyester polyol.

[0180] As described above, when the present inventors solidified HDI using only ammonia (the first blocking agent) as the blocking agent, the melting point (softening point) of the resulting blocked isocyanate composition became high. Therefore, the inventors invented a blocked polyisocyanate in which the blocking agent was improved (typically, an amine-based blocking agent was added) so that the melting point could be lowered to a temperature compatible with polyester polyol.

[0181] [Content] Summarizing the blocked isocyanate composition according to the present invention, it is as follows. That is, the blocked isocyanate composition according to the present invention is a blocked isocyanate obtained by blocking HDI or the like with two types of blocking agents. Further, in the blocked isocyanate composition according to the present invention, the ratio of the ammonia block to the amine block is, for example, 30:70 to 20:80. Further, in the blocked isocyanate composition according to the present invention, the amine block of the isocyanate component (HDI or the like) is preferably a block by diisopropylamine.

[0182] [Order of addition of the first and second blocking agents] Regarding the order of addition of the first blocking agent (ammonia) and the second blocking agent (amine-based blocking agent or the like) to the isocyanate compound, it is essential to first add the second blocking agent (amine-based blocking agent or the like) and block a part of the NCO groups of the isocyanate component (the part corresponding to the ratio of the second blocking agent) with the second blocking agent, and then add the first blocking agent (ammonia). If not, (that is, if ammonia, which is the first blocking agent, is added first), ammonia, which is the first blocking agent, will add to and block all the NCO groups of the isocyanate component, and even if the second blocking agent is added later, it is impossible to produce a blocked isocyanate composition in which the NCO groups of the isocyanate component (at least some of the NCO groups in one molecule of the isocyanate component) are blocked by the second blocking agent. The inventors have confirmed this.

[0183] [Isocyanate-reactive compound] The isocyanate-reactive compound consists of a polyol or a polyamine. Specifically, it is a monosaccharide, disaccharide, oligosaccharide, oligosaccharide, polysaccharide, or an aqueous polysaccharide, polyhydric alcohol, aromatic polyol, primary amine compound, secondary amine compound, carboxylic acid compound, water, or a mixture thereof. Examples of monosaccharides include glucose, fructose, galactose, mannose, ribose, etc. Examples of disaccharides include maltose, sucrose, trehalose, lactose, cellobiose, isomaltose, gentiobiose, etc. Examples of oligosaccharides include gentianose, raffinose, panose, melezitose (the above trisaccharides), stachyose (tetrasaccharide), etc. Examples of oligosaccharides include fructooligosaccharide, isomaltooligosaccharide, soybean oligosaccharide, etc. Examples of polysaccharides include starch, cellulose, etc. Examples of starches include tapioca, potato, corn, wheat, sweet potato, rice, sago, etc. Examples of aqueous polysaccharides include dextrin, alpha-starch, etc. Preferably, the isocyanate-reactive compound of this embodiment consists of polyvinyl alcohol (PVA) as a polyol and polyester polyol.

Industrial Applicability

[0184] The blocked isocyanate composition of the present invention can typically be applied as a curing agent to powder compositions such as powder coatings, but can also be applied to curing agents for adhesives and coating agents (other than paints) (preferably powder coating agents).

Claims

1. A blocked isocyanate composition synthesized from an isocyanate compound and a thermally dissociable blocking agent, wherein the thermally dissociable blocking agent consists of a first blocking agent composed of ammonia and a second blocking agent different from the first blocking agent, the isocyanate compound consists of hexamethylene diisocyanate, and the second blocking agent consists of an amine-based blocking agent or an oxime-based blocking agent, characterized by the blocked isocyanate composition.

2. The blocked isocyanate composition according to claim 1, wherein the second blocking agent is an amine-based blocking agent.

3. The blocked isocyanate composition according to claim 1 or 2, wherein the second blocking agent is diisopropylamine.

4. The blocked isocyanate composition according to any one of claims 1 to 3, wherein the isocyanate compound is a trimer of hexamethylene diisocyanate.

5. The blocked isocyanate composition according to any one of claims 1 to 4, wherein the ratio of the first blocking agent to the second blocking agent is in the range of 10:90 to 60:

40.

6. A blocked isocyanate composition synthesized from an isocyanate compound and a thermally dissociable blocking agent, wherein the isocyanate compound consists of an aliphatic isocyanate, the thermally dissociable blocking agent consists of a first blocking agent composed of ammonia and an amine-based blocking agent or an oxime-based blocking agent as a second blocking agent different from the first blocking agent, the isocyanate compound consists of hexamethylene diisocyanate and contains a trimer of the hexamethylene diisocyanate, The blocked isocyanate composition, wherein the second blocking agent is an amine-based blocking agent or an oxime-based blocking agent.

7. A blocked isocyanate composition synthesized from an isocyanate compound and a thermally dissociable blocking agent, wherein the isocyanate compound consists of an isocyanate compound having a plurality of isocyanate groups, the thermally dissociable blocking agent consists of a first blocking agent composed of ammonia and a second blocking agent different from the first blocking agent, the isocyanate compound consists of a trimer (0037) of hexamethylene diisocyanate, the second blocking agent consists of an amine-based blocking agent or an oxime-based blocking agent, the second blocking agent blocks some of the isocyanate groups among the plurality of isocyanate groups of the isocyanate compound, and the first blocking agent blocks the remaining isocyanate groups among the plurality of isocyanate groups of the isocyanate compound that are not blocked by the second blocking agent. The blocked isocyanate composition is characterized by this.

8. The blocked isocyanate composition according to claim 6 or 7, wherein the second blocking agent is an amine-based blocking agent, and the ratio of ammonia as the first blocking agent to the amine-based blocking agent as the second blocking agent is in the range of 10:90 to 60:

40.

9. The blocked isocyanate composition according to claim 6 or 7, wherein the second blocking agent is an oxime-based blocking agent, and the ratio of ammonia as the first blocking agent to the oxime-based blocking agent as the second blocking agent is in the range of 50:50 to 60:

40.

10. The second blocking agent blocks two of the three isocyanate groups in one molecule of the isocyanate compound, and the first blocking agent blocks the remaining one isocyanate group that the second blocking agent has not blocked among the three isocyanate groups of the isocyanate compound. The blocked isocyanate composition according to claim 7, characterized in that.

Images