JP2003048951A - Blocked polyisocyanate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blocked polyisocyanate obtained by reacting an amine having a large steric hindrance in combination with imidazoles, with a polyisocyanate, and further to provide a one-pack type coating agent. SOLUTION: This blocked polyisocyanate is obtained by reacting the amine having the large steric hindrance in combination with the imidazoles, with the polyisocyanate. The one-pack type coating agent is produced by mixing the blocked polyisocyanate with a polyol and/or a polyamine.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a blocked isocyanate having excellent low-temperature dissociation performance.

[0002]

2. Description of the Related Art Polyurethane utilizes its elasticity, tough mechanical properties, chemical stability, etc., for paints, adhesives, binders, synthetic leather, artificial leather, foams, moldings, fiber treatment agents, Widely used in flooring materials, sealants, clothing materials, etc. The method for producing a polyurethane resin is roughly classified into a one-shot method and a prepolymer method. The one-shot method is a method in which polymer polyol (polymer polyhydric alcohol), polyisocyanate (polyhydric isocyanate), chain extender (polyhydric alcohol, polyhydric amine), and other additives are charged all at once. The prepolymer method is a method in which a terminal isocyanate prepolymer composed of a high molecular polyol and a polyisocyanate is once synthesized, and then a high molecular weight is obtained with a chain extender.

In polyurethane coatings, for example, polyisocyanates such as isocyanurate-based polyisocyanates are generally reacted with polymer polyols such as polyacrylate-based polyols or polymethacrylate-based polyols to form coating films. . The isocyanate group and the hydroxyl group react immediately to form a polyurethane resin. For this reason, generally, a two-pack type coating is used in which the polyisocyanate and the polyol are mixed immediately before the application to the substrate. As a special method, blocked polyisocyanate in which the reactivity of polyisocyanate is suppressed by a blocking agent is mixed with a polyol and / or a polyamine in advance, and the mixture is applied to a substrate, and then the blocking agent is heated by heating. There is a one-pack type paint that cures urethane by desorbing and regenerating the isocyanate group. Even if a blocked polyisocyanate is mixed with a polyol and / or a polyamine at room temperature, the curing reaction does not substantially proceed and the pot life (time until thickening) is long, so that a one-pack type coating becomes possible. As the blocking agent, as described in Polyurethane Resin Handbook (Keiji Iwata 1991 Nikkan Kogyo Shimbun p420), methyl alcohol, caprolactam, phenol, MEK oxime, ethyl acetoacetate and the like are generally known. Is an oxime-based blocking agent. The one-pack type coating agent comprising a mixture of blocked isocyanate and chain extender has an advantage over the two-pack type in that the coating process can be simplified.

However, in general, a paint / coating agent using a blocked isocyanate has a long pot life, but has a drawback that it has a high curing temperature and a long curing time. JP-A-8-283376 discloses an amine-type blocking agent, but the reaction rate of polyurethane formation at low temperature is still insufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a novel blocked polyisocyanate which is advantageous in handleability because the blocking agent has a low dissociation temperature and therefore the reaction rate with a chain extender is fast. To do. It also provides a novel blocked polyisocyanate using a polyol-modified polyisocyanate as a raw material for the blocked polyisocyanate. Further, the present invention provides a novel one-pack type coating agent obtained by mixing the blocked polyisocyanate with a polyol and / or a polyamine.

[0006]

The present inventors have found that a combination of amines having a specific structure is effective as a blocking agent having a low temperature dissociation type property and completed the present invention. That is, the first aspect of the present invention is the following general formula (1)
Combining one or more amines selected from (2) and amines selected from the structure of the following general formula (3),
It is a blocked polyisocyanate obtained by reacting with polyisocyanate.

[0007]

[Chemical 2]

[0008] (wherein, R _1, R ₂ is an alkyl group or a phenyl _{group, R 3, R 4, R} 5, R 6 is hydrogen, an alkyl group or .R _1, R _2, R ₃ representing a phenyl group, two or all inner can may be part of the same cyclic alkyl group, R _4, R _5, two or all of R ₆ is may be part of the same cyclic alkyl group .R _7, Is an alkyl group or a phenyl group, R ₈ , R ₉ , R ₁₀
Represents hydrogen, an alkyl group, or a phenyl group. R ₇ , R ₈
May be part of the same cyclic alkyl group, and R ₉ and R ₁₀
May be part of the same cyclic alkyl group. n represents an integer of 1 or more. R ₁₁ , R ₁₂ , and R ₁₃ represent an alkyl group or a phenyl group. )

The second invention is the first blocked isocyanate of the invention, wherein the polyisocyanate is a polyol-modified polyisocyanate. A third invention is the second blocked polyisocyanate of the invention, wherein the polyol is a polycarbonate diol. A fourth aspect of the invention is a one-pack type coating agent obtained by mixing the blocked polyisocyanate according to the first, second or third aspect of the invention with a polyol and / or a polyamine.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a polyisocyanate is a compound having two or more isocyanate groups in one molecule. The diisocyanate, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate (XDI), naphthalene diisocyanate (NDI), tolidine diisocyanate ( TODI), hydrogenated diphenylmethane diisocyanate (H12MDI), hydrogenated xylylene diisocyanate (H6XDI), hydrogenated tolylene diisocyanate (H6TDI), transcyclohexane 1,4-diisocyanate, hexamethylene diisocyanate (HDI) ),
Examples thereof include isophorone diisocyanate (IPDI). Examples of trifunctional or higher polyisocyanates include compounds derived from triphenylmethane triisocyanate and diisocyanates. Specific examples of the polyisocyanate derived from a diisocyanate compound include isocyanurate modified products, alohanate modified products,
Examples include modified burette and modified urea.
Polyol-modified polyisocyanate obtained by modifying these polyisocyanates with polyol is preferable because it has a wide adjustment range of physical properties of polyurethane film, and high-molecular polyol-modified polyisocyanate (prepolymer) obtained from high-molecular polyol and polyisocyanate is More preferable.

The term “polyol-modified” means that a polyol and a polyisocyanate are charged and reacted at a ratio in which the equivalence ratio (isocyanate equivalent / hydroxyl equivalent) exceeds 1, to obtain a compound having isocyanate groups at both ends of the molecule. This reaction usually proceeds at room temperature, but it may be carried out at a temperature up to about 150 ° C. The urethanization catalyst may or may not be used. The solvent may or may not be used. As the solvent, aromatic solvents, hydrocarbon solvents, ketone solvents, amide solvents, sulfoxide solvents, ester solvents, alcohol solvents, ether solvents can be used.

The polyol used herein is a polyhydric alcohol compound and has a low molecular weight diol or a high molecular weight diol having two hydroxyl groups in the molecule, or an average number of hydroxyl groups exceeding 2 in the molecule. It is a low molecular weight polyol or a high molecular weight polyol. These polyols may be used alone or as a mixture. The low molecular weight diol is a compound that can be represented by the general formula HO-R-OH (R is an alkylene group or an oxyalkylene group). Among these, R in the general formula
Is preferably an alkylene group having 2 to 12 carbon atoms or an oxyalkylene group. Specific examples include ethylene glycol, diethylene glycol, 1,3-propanediol,
1,4-butanediol, propylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl 1,5-
Examples include pentanediol and 1.6-hexanediol.

Examples of low molecular weight triols include trimethylolethane, trimethylolpropane, glycerin, sorbitol, and quadrol. Examples of the polymer diol include polycarbonate diol, polyether diol, polyester diol, and polycaprolactone diol. Among them, polycarbonate diol is particularly preferable because it is superior in chemical stability and physical stability to other polymer diols. Polycarbonate diols can be represented by the general formula HO- [R-OCOO] _n R-OH, where R is a divalent straight-chain, branched or cyclic alkylene group, of which the number of carbon atoms is 2 Preferred are alkylene groups from 1 to 12. As R more preferred in the general _{formula, - (CH 2) n -} (n = 2-6), - CH 2 -CH 2
_{-CH (CH 3) -CH 2 -CH} 2 -, - CH 2 -CH 2 -CH (CH 3) -, - CH 2 -C (C
H _{3) 2} -CH ₂ -, cyclohexenyl group. A copolymerized polycarbonate diol containing two or more kinds of these repeating units may also be used.

Polycarbonate having an average number of hydroxyl groups exceeding 2
As the polyol, the above-mentioned polycarbonate diol
In addition to repeating units, trimethylol as a copolymerization component
Ruethane, trimethylolpropane, glycerin, sol
Using low molecular weight triols such as bitol and quadrol
An example is a polycarbonate polyol produced by
The polyether diol has the general formula HO- [RO]_n−H And R in the formula is a divalent straight chain, branched chain,
Or a cyclic alkylene group, of which carbon is
Alkylene groups of 2 to 12 in number are preferred. More preferred
R in the general formula is-(CH₂)_n− (N = 2−6), −CH₂−
CH₂-CH (CH₃) −CH ₂-CH₂-, -CH₂-CH₂-CH (CH₃)-,-CH₂-
C (CH₃)₂-CH₂-, A cyclohexenyl group. Also this
Copolymer containing two or more types of repeating units
It may be ether diol.

Polyester diols can be represented by the general formula HO- [R-O-OC-R'-CO-O] _n- R-OH, where R is divalent linear, branched or cyclic. It is an alkylene group, and among these, an alkylene group having 2 to 12 carbon atoms is preferable. As R more preferred in the general _{formula, - (CH 2) n -} (n = 2-6), - CH 2 -CH 2
_{-CH (CH 3) -CH 2 -CH} 2 -, - CH 2 -CH 2 -CH (CH 3) -, - CH 2 -C (C
H _{3) 2} -CH ₂ -, cyclohexenyl group. A copolyester diol containing two or more kinds of these repeating units may also be used. In the formula, R ′ is a divalent linear, branched or cyclic alkylene group or a phenylene group, and among these, an alkylene group having 2 to 12 carbon atoms is preferable. More preferred formula _{-R'-, - (CH 2) n} -
(n = 2-10), a cyclohexenyl group. Also, a copolymerized polyester diol containing two or more kinds of these repeating units may be used.

As the polyester polyol having an average number of hydroxyl groups of 2 or more, in addition to the repeating unit of the above polyester diol, a low molecular weight triol such as trimethylolethane, trimethylolpropane, glycerin, sorbitol or quadrol is used as a copolymerization component. Examples thereof include polyester polyols. In the present invention, one or more amines selected from the following (1) and (2) and amines selected from the following structure (3) are used in combination.

[0017]

[Chemical 3]

[0018] (wherein, R _1, R ₂ is an alkyl group or a phenyl _{group, R 3, R 4, R} 5, R 6 is hydrogen, an alkyl group or .R _1, R _2, R ₃ representing a phenyl group, two or all inner can may be part of the same cyclic alkyl group, R _4, R _5, two or all of R ₆ is may be part of the same cyclic alkyl group .R _7, Is an alkyl group or a phenyl group, R ₈ , R ₉ , R ₁₀
Represents hydrogen, an alkyl group, or a phenyl group. R ₇ , R ₈
May be part of the same cyclic alkyl group, and R ₉ and R ₁₀
May be part of the same cyclic alkyl group. n represents an integer of 1 or more. R ₁₁ , R ₁₂ , and R ₁₃ represent an alkyl group or a phenyl group. )

The compounds of the general formulas (1) and (2) are compounds having a large steric hindrance substituent on one or both carbons adjacent to the nitrogen atom as described above. The compound of general formula (3) is imidazole or a derivative thereof. The amine compounds of the general formulas (1) and (2) may be used alone or in a mixture of two or more, and the amine compounds of the general formula (3) may be used alone or in a mixture of two or more. Regarding the substituents R _{1 to} R ₁₃ of each compound, in the case of an alkyl group,
Included are straight-chain, branched, and cyclic alkyl groups, and in the case of phenyl groups, alkyl-substituted phenyl groups and condensed rings are included. These amines react with an isocyanate to form a urea compound, which is called a blocked polyisocyanate (blocked prepolymer).

The present inventors have proposed that a blocked polyisocyanate obtained by combining these specific amines is a general blocking agent, and a temperature lower than the dissociation temperature of the blocked polyisocyanate obtained by using an oxime type blocking agent. It was found that the blocking agent dissociates and reacts easily with the chain extender to form polyurethane and / or polyurea. It is presumed that the urea compound formed by the reaction of the specific amine with isocyanate has a property that the bond between the carbonyl carbon and the nitrogen atom on the amine side is easily broken due to the steric hindrance or electronic reasons. The present inventors have found that the polyurethane reaction is faster when the compound of the general formula (1) or (2) is used in combination with the compound of the general formula (3) than when the compound of the general formula (1) or (2) is used alone. Is heading. Although the reason for this is not clear, there is a possibility that the amine shown in the compound of the general formula (3) may act as a catalyst for the polyurethane reaction. Further, when the compound of the general formula (3) is used alone, a phenomenon such as gelation due to an excessively high rate of polyurethane formation is observed, and it may be difficult to use from a practical viewpoint. When the blocked polyisocyanate of the present invention is heated to 100 to 150 ° C, the isocyanate easily regenerates and reacts with the chain extender to form a polyurethane and / or polyurea resin.

Specific examples of the amines represented by the general formulas (1) and (2) include 2,6-dimethylpiperidine, diisopropylamine, N-ethyl t-butylamine, 2,2,6,6, -tetramethylpiperidine, Examples thereof include N-methylcyclohexylamine, N-propylsec-butylamine, N-methylbenzylamine, N-isopropylcyclohexylamine, N-isopropylbenzylamine, Nt-butylbenzylamine, dicyclohexylamine and di-t-butylamine. Among these, 2,6-dimethylpiperidine, N-ethyl t-butylamine, diisopropylamine, and Nt-butylbenzylamine are particularly preferable because of their low dissociation temperature of the blocking agent.

The compounds represented by the general formula (3) include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl. -4-Methylimidazole etc. can be illustrated. The dissociation temperature of the blocked isocyanate can be adjusted by the mixing ratio of the amine represented by the general formula (1) or (2) and the amine represented by the general formula (3). For example, when diisopropylamine and imidazole are mixed and used as a blocking agent,
The dissociation temperature of the blocked isocyanate (the urethane urea formation reaction rate when the blocked isocyanate and a chain extender such as a diamine are mixed) depends on the mixing ratio of both amines (blocking agents). The urea reaction speed becomes faster.

The blocked isocyanate is prepared by mixing the polyisocyanate with the specific amine compound of the present invention.
Obtained when the reaction is carried out at a ratio of (amine equivalent / isocyanate equivalent) exceeding 1. This reaction is usually carried out at room temperature, but it may be carried out at a temperature up to about 100 ° C. The one-pack type coating agent obtained by mixing the blocked polyisocyanate of the present invention with a polyol and / or a polyamine can be used as a coating material or a coating agent for synthetic leather. The one-pack type coating agent does not substantially cure at room temperature, and can be easily heated by heating at about 100 ° C. or higher to cause the blocking agent to dissociate and react with the curing agent at a practically sufficient rate, thereby removing polyurethane. Form. A solvent may or may not be used, but if a solvent is used,
Examples of usable solvents include aromatic solvents, hydrocarbon solvents, ketone solvents, amide solvents, sulfoxide solvents, ester solvents, alcohol solvents and ether solvents.

The polyol that can be used at this time is not particularly limited, but low molecular weight polyols and high molecular weight polyols can be used. The polyol used here is a polyhydric alcohol compound, and is a low-molecular diol or high-molecular diol having two hydroxyl groups in the molecule, or a low-molecular polyol having an average number of hydroxyl groups exceeding 2 in the molecule. Alternatively, it is a polymer polyol. These polyols may be used alone or as a mixture. The low molecular weight diol is a compound that can be represented by the general formula HO-R-OH (R is an alkylene group or an oxyalkylene group). Among these, in the general formula
An alkylene group or an oxyalkylene group having 2 to 6 carbon atoms in R is preferable. More preferably, ethylene glycol, diethylene glycol, 1,3-propanediol,
1,4-butanediol, propylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl 1,5-
Examples include pentanediol and hexamethylene glycol.

Examples of low molecular weight triols include trimethylolethane, trimethylolpropane, glycerin, sorbitol, quadrol and the like. Examples of the polymer diol include polycarbonate diol, polyether diol, polyester diol, polycaprolactone diol, polyacrylate-based polyol, and polymethacrylate-based polyol. The polyamine that can be used as a mixture with the blocked isocyanate is a polyvalent amine compound, and is a low molecular weight amine or high molecular weight amine having two amino groups in the molecule, or 2 in the molecule. A low molecular weight amine or a high molecular weight amine having an average number of amino groups exceeding. These polyamines may be used alone or as a mixture.

The low molecular weight polyamine is not particularly limited, but ethylenediamine, hexamethylenediamine, bis
(Aminophenyl) methane, bis (alkylaminophenyl) methane, phenylenediamine, hydrogenated phenylenediamine, tolylenediamine, hydrogenated tolylenediamine,
Examples include xylylenediamine, hydrogenated xylylenediamine, isophoronediamine, and 4-aminomethyloctamethylenediamine. Examples of the polymer polyamine include polyacrylate-based polyamine and polymethacrylate-based polyamine.

Generally, in order to form a polyurethane film, polyurethane is dissolved in a solvent and applied onto a substrate. The solid content concentration at this time is adjusted to a viscosity that facilitates application, but is usually about 20 to 50% by weight. Therefore, in the process of drying the film, a large amount of solvent volatilizes, which easily causes a problem of environmental pollution. As another method, separately prepare the terminal isocyanate prepolymer and the curing agent,
A method of mixing immediately before coating on the substrate is also used, but in this case, since it is a two-component type, it is a complicated method in terms of equipment and procedure. Since the one-pack type coating agent of the present invention is a precursor of polyurethane, it has a much lower viscosity than the polyurethane solution, and can be solvent-free or highly solidified, and the one-pack type coating agent Therefore, it is possible to provide a very simple method in terms of equipment and procedure. Hereinafter, the present invention will be described in more detail with reference to examples.

[0028]

Example 1 Preparation of Blocked Isocyanate (Blocked Prepolymer) Solution In a 1 L separable flask equipped with a stirrer, polycarbonate diol (L-5651 manufactured by Asahi Kasei Co., number average molecular weight 101) was added.
0, hydroxyl value (OHV) = 111 mg KOH / g, copolymerized polycarbonate diol made from 1,6-hexanediol and 1,5-pentanediol as raw materials, 200 g and dimethylformamide (DM
F) 30 g was charged and the temperature was raised to 40 ° C. with stirring. MDI
74.26 g (0.297 mol) was dissolved in 30 g of DMF, and this was added dropwise to the above polycarbonate diol solution at a temperature of 40 ° C. over 10 minutes, and then the temperature was maintained at 40 ° C. for 30 minutes. At this time, NC
O group reaction rate (NCO group reaction rate = NCO group reaction amount (mol)
/ The amount of hydroxyl groups (mol) x 100 in the charged polyol is 104
%, The NCO group concentration of the prepolymer solution is 0.545 mmol / g
Became. The amine determination method was used for the NCO group concentration. 300 g of this prepolymer solution was collected, and 18.23 g of a mixed block agent consisting of 70 mol% of diisopropylamine and 30 mol% of 2-methylimidazole (1.05 times the amount of NCO group) was dissolved in 30 g of DMF at 40 ° C. for 30 minutes. After the addition, the mixture was stirred at 40 ° C. for 30 minutes and then taken out. This blocked prepolymer solution is liquid and fluid, and the blocked NCO group concentration is
It was 0.472 mmol / g in terms of group and the solid content was 75.6%. In the infrared absorption spectrum, the characteristic absorption peak of the NCO group was not detected, and the NCO group was completely blocked. Curing test

To the blocked prepolymer solution at room temperature, a diamine curing agent C-260 (bis (2-methylaminocyclohexyl) methane) manufactured by Bayer was added, and the amino group equivalent number / NC
The one-component coating agent having a concentration of 65% was prepared by adding DMF so that the O group equivalent was 1.00 and further adding DMF. 5g of this
Collect in a test tube, insert a glass stir bar with a diameter of 8 mm to a position of about 5 mm from the bottom of the test tube, stir the glass stir bar at 100 rpm while heating to 120 ° C. in an oil bath, and The time from the time of heating until it hardened and wound around a glass rod and rising 10 mm from the position of the first liquid surface was measured. This time was 2 minutes. It was judged that the dissociation rate of the blocking agent was relatively high (the dissociation temperature was low) when the rising time was relatively short after heating. The dissociation rate of the blocking agent was faster than in Comparative Examples 2, 3, and 4.

[0030]

Examples 2 to 4 A blocked prepolymer solution was prepared under the conditions shown in Table 1 in the same manner as in Example 1 using various amine blocking agents. Further, the blocked prepolymer was subjected to a curing test in the same manner as in Example 1. The results are shown in Table 1.
It was shown to.

[0031]

Example 5 As a polyol, Asahi Kasei Corporation L-5652 (1,6-
Copolymerized polycarbonate diol made from hexanediol and 1,5-pentanediol, number average molecular weight M _n = 200
Using 5), a one-pack type coating material was prepared under the conditions shown in Table 1 in the same manner as in Example 1, and a curing test was conducted. The results are shown in Table 1.

[0032]

Example 6 As a polyol, Asahi Kasei Corporation L-6002 (1,6-
Using polycarbonate diol made from hexanediol as a raw material, M _n = 2000), a one-pack type coating material was prepared in the same manner as in Example 1 under the conditions shown in Table 1, and a curing test was conducted. The results are shown in Table 1.

[0033]

[Example 7] Polytetramethylene glycol ( _Mn = 1830) manufactured by Asahi Kasei Co., Ltd. was used as a polyol, and under the conditions shown in Table 1, a one-pack type paint was prepared in the same manner as in Example 1 and a curing test was conducted.
The results are shown in Table 1.

[0034]

Example 8 Preparation of Polyurethane Film The one-component coating solution used in the curing test of Example 5 was further added.
After adding DMF to make the concentration 50%, apply it on the glass plate,
The mixture was heated on a hot plate at 120 ° C. for 15 minutes to promote a urethanization reaction while volatilizing DMF to obtain a polyurethane film. The time until the tack disappeared was measured while touching the surface of the film with the tip of the spatula during the dry curing of the film, and it was 4 minutes. The time until the tack disappeared was shorter than that in Comparative Example 5, which was in agreement with the ease of dissociation of the blocking agent obtained in the curing test of Example 5. Of this film
100% modulus is 106kgf / cm ² , breaking strength is 596kgf / cm ² ,
The breaking elongation was 411%. This tensile test was conducted under the following conditions. Film shape width 10 mm, chuck distance 50 mm, film thickness approx. 80-120 μm pulling speed 100 mm / min

[0035]

Comparative Example 1 Using imidazole alone as a blocking agent, a one-pack type coating material was prepared under the conditions shown in Table 1 in the same manner as in Example 1 and a curing test was conducted. Since the rate of curing with polyurethane was fast and gelation was observed, it was judged that handling might be difficult from a practical viewpoint.

[0036]

[Comparative Example 2] Using diisopropylamine alone as a blocking agent, a one-pack type coating material was prepared in the same manner as in Example 1 under the conditions shown in Table 1, and a curing test was conducted. The rising time was 3 minutes.

[0037]

Comparative Examples 3 and 4 Using an oxime-based blocking agent, a prepolymer solution was prepared in the same manner as in Example 1 under the conditions shown in Table 1. Further, the blocked prepolymer was subjected to a curing test in the same manner as in Example 1. The results are shown in Table 1.

[0038]

Comparative Example 5 A polyurethane film was prepared in the same manner as in Example 8 using the one-pack type coating solution used in the curing test of Comparative Example 3. The time until the tack disappeared was measured while touching the surface of the film with the tip of the spatula during the drying and curing of the film, and it was 11 minutes.

[0039]

[Table 1]

[0040]

Since the blocked prepolymer of the present invention has a low temperature dissociation property, it can form a polyurethane film at a low temperature for a short time. Further, the one-pack type curing agent of the present invention can provide a simple coating method with a high solid content. In the present invention, since the isocyanate group of the terminal isocyanate prepolymer using a high molecular weight polyhydric alcohol as a raw material is blocked, the prepolymer has the same design concept of mechanical properties as the polyurethane of the normal prepolymer method. The curing agent can be made into a one-pack type, and the short pot life (time to thickening) when the prepolymer and the curing agent are mixed is improved as in the conventional prepolymer method. It is much easier to handle than the prepolymer method. When combined with polycarbonate diol, it becomes a durable polyurethane raw material.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J034 AA02 AA03 AA05 BA02 BA03                       CA01 CA04 CA05 CA15 CB02                       CC03 DA01 DA03 DB01 DB04                       DF01 DF02 DF12 DG01 DG02                       DG03 DG04 DG05 DP18 HA01                       HA02 HA07 HA08 HC03 HC12                       HC17 HC46 HC52 HC61 HC64                       HC71 HC73 HD07 JA02 JA42                       KB03 KD12 LA06 LA32 QA03                       QB12 QB19 RA07                 4J038 DG031 DG051 DG061 DG111                       DG121 DG301

Claims (4)

[Claims] 1. A block obtained by combining one or more amines selected from the following general formulas (1) and (2) and an amine selected from the structure of the following general formula (3) and reacting them with a polyisocyanate. Depolitianate. [Chemical 1] (However, R ₁ and R ₂ are an alkyl group or a phenyl group, R ₃ and
R ₄ , R ₅ , and R ₆ represent hydrogen, an alkyl group, or a phenyl group. Two or all of R ₁ , R ₂ and R ₃ may be part of the same cyclic alkyl group, and two or all of R ₄ , R ₅ and R ₆ may be part of the same cyclic alkyl group. May be R ₇ represents an alkyl group or a phenyl group, and R ₈ , R ₉ and R ₁₀ represent hydrogen, an alkyl group or a phenyl group. R ₇ and R ₈ may be part of the same cyclic alkyl group, and R ₉ and R ₁₀ may be part of the same cyclic alkyl group. n represents an integer of 1 or more. R ₁₁ , R ₁₂ , and R ₁₃ represent an alkyl group or a phenyl group. ) 2. The blocked isocyanate according to claim 1, wherein the polyisocyanate is a polyol-modified polyisocyanate. 3. The blocked polyisocyanate according to claim 2, wherein the polyol is a polycarbonate diol. 4. A one-pack type coating agent obtained by mixing the blocked polyisocyanate according to claim 1, 2 or 3 with a polyol and / or a polyamine.