JP5968111B2 - Block polyisocyanate composition and curable composition - Google Patents

Description

  The present invention relates to a block polyisocyanate composition and a curable composition containing the block polyisocyanate composition.

  A polyisocyanate composed of an aliphatic diisocyanate or an alicyclic diisocyanate is known to be a non-yellowing type and a crosslinking agent that gives a crosslinked product excellent in weather resistance, chemical resistance, and flexibility. However, since the isocyanate group is rich in activity, it must be mixed with the active hydrogen compound, which is the main agent, before use, which is cumbersome in terms of workability.

  On the other hand, the blocked polyisocyanate in which the isocyanate group of the polyisocyanate is blocked with a heat dissociable blocking agent (hereinafter also simply referred to as “blocking agent”) does not react at room temperature even when mixed with the polyol as the main agent, By heating, the blocking agent is dissociated, the isocyanate group is regenerated, and curing proceeds. For this reason, it is not necessary to mix the curing agent and the main agent immediately before use, and since it can be stored in a single liquid state in which the main agent and the curing agent are mixed in advance, there is no trouble in terms of workability, It is especially used in the industrial coating field.

  However, the blocked polyisocyanate is increased in viscosity due to intermolecular hydrogen bonding caused by urethane bonds or urea bonds generated by blocking isocyanate groups. Therefore, the block polyisocyanate is usually used after being diluted with an organic solvent to lower the viscosity. In general, a polyurethane resin-based coating agent is used by diluting a main agent composed of an active hydrogen compound with an organic solvent or water, so that a dilute curing agent is easier to handle such as mixing with the main agent. There is an advantage of advantage.

  On the other hand, in recent years, reduction of the amount of organic solvent used has become an urgent task from the viewpoint of environmental protection and resource saving against air pollution. In addition, in thick coating applications such as thick coating agents, casting agents, sealing agents, etc., there was a problem that volume shrinkage due to volatilization of organic solvents and generation of voids (bubbles) in the crosslinked product became prominent. .

  Blocks of biuret-type polyisocyanates and isocyanurate-type polyisocyanates are blocked polyisocyanates in which active isocyanate groups possessed by aliphatic isocyanates excellent in weather resistance, especially polyisocyanates derived from hexamethylene diisocyanate, are blocked with a blocking agent. The body is known. For example, Patent Document 1 describes a block body of an isocyanurate type polyisocyanate.

  On the other hand, in recent years, a completely solvent-free polyurethane resin that does not use an organic solvent in the main agent and the curing agent as raw materials has attracted attention. Accordingly, several bifunctional block urethane prepolymers that are liquid at room temperature and can be used without solvent are known. For example, Patent Document 2 describes a urethane prepolymer obtained by reacting a lactone-modified diol with a polyfunctional isocyanate and further blocking the isocyanate group. Patent Document 3 proposes a urethane prepolymer having polycarbonate diol and diisocyanate as raw material components and having an isocyanate group blocked at the end.

  Patent Document 4 describes a urethane prepolymer block of polycaprolactone polyol.

  Further, Patent Document 5 discloses a one-component polyurethane thermosetting coating composition comprising a polycaprolactone polyol urethane prepolymer block and / or a polytetramethylene glycol urethane prepolymer block and a polyhydroxy compound. Is described.

JP-A-2-260 JP 2002-121255 A JP 2006-70058 A JP-A-63-126855 JP-A-2-276878

  However, it is not assumed that the blocked isocyanate described in Patent Document 1 is used without a solvent, and the viscosity may be too high without a solvent.

  In addition, the urethane prepolymers described in Patent Documents 2 and 3 are not intended for use as a cross-linking agent, and because diol is used as a raw material, the number of functional groups is about 2, thereby providing a cross-linking agent. When used, the crosslinkability may not be sufficient. Moreover, since the content rate of NCO group is very low, the compounding quantity with respect to a main ingredient may have to be very increased. Furthermore, the viscosity may be too high to use these block urethane prepolymers as crosslinking agents.

  Furthermore, the urethane prepolymer of Patent Document 4 may not have sufficient crosslinkability to be used as a crosslinking agent. Further, there is no description suggesting the use without a solvent, and the viscosity may be too high when used without a solvent.

  Moreover, the urethane prepolymer of Patent Document 5 may not have sufficient crosslinkability to be used as a crosslinking agent, as in Patent Document 3. Moreover, there is no description which suggests using a crosslinking agent without a solvent, and when using it without a solvent, a viscosity may be too high. Moreover, there is no description which suggests including the case where the polyhydric hydroxy compound and the one-component polyurethane thermosetting coating composition of Patent Document 5 contain no solvent.

  The present invention can provide a crosslinked product having low viscosity, excellent crosslinkability and workability of an active hydrogen compound, and having flexibility and few voids, even if it does not substantially contain an organic solvent. An object is to provide a block polyisocyanate composition and a curable composition containing the composition and an active hydrogen compound.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have a block polyisocyanate having a specific structure, although the viscosity of the polyisocyanate before the block reaction is relatively high, After the block reaction, it has been found that among the isocyanurate type polyisocyanates that are commonly used in general, the viscosity is lower than that of the low viscosity type block polyisocyanate. Even when an organic solvent is not included, the present invention has been completed by finding that it is excellent in workability, has good crosslinkability, and gives a cross-linked product having flexibility and few voids. That is, the present invention is as follows.

[1]
A block polyisocyanate composition substantially free of organic solvent,
The block polyisocyanate is obtained by reacting an aliphatic diisocyanate and / or an alicyclic diisocyanate with a polycaprolactone polyol and / or a polyether polyol, a polyisocyanate having an isocyanate group at a terminal, and a thermally dissociable block. Is obtained by reacting the agent,
The polycaprolactone polyol and / or the polyether polyol has an average functional group number of 2.4 to 3.0, and a number average molecular weight of 500 to 1,000.
The polyether polyol has an oxytetramethylene group and / or an oxypropylene group,
The content of the organic solvent is 0 to 5% by mass.
A curable composition containing a block polyisocyanate composition and an active hydrogen compound and substantially free of an organic solvent (excluding an aqueous coating composition).
[2]
The curable composition according to [1], wherein the thermally dissociable blocking agent is at least one selected from the group consisting of oxime compounds, pyrazole compounds, amide compounds, amine compounds, and active methylene compounds. object.
[3]
The curable composition according to [1] or [2], wherein the aliphatic diisocyanate is hexamethylene diisocyanate.
[4]
The curable composition according to any one of [1] to [3], wherein the active hydrogen compound is a polyol compound.

  According to the present invention, a block polyisocyanate composition that has a low viscosity, is excellent in crosslinkability and workability of an active hydrogen compound, and can provide a cross-linked product with few voids, even if it does not substantially contain an organic solvent. And a curable composition containing the composition and an active hydrogen compound.

  Hereinafter, modes for carrying out the present invention (hereinafter also simply referred to as “this embodiment”) will be described in detail. The present embodiment is not limited to this, and various modifications can be made without departing from the scope of the present embodiment.

[Block polyisocyanate composition]
The block polyisocyanate composition of this embodiment is
Substantially free of organic solvents,
The block polyisocyanate is obtained by reacting an aliphatic diisocyanate and / or an alicyclic diisocyanate with a polycaprolactone polyol and / or a polyether polyol, a polyisocyanate having an isocyanate group at a terminal, and a thermally dissociable block. Is obtained by reacting the agent,
The polycaprolactone polyol and / or the polyether polyol has an average functional group number of 2.4 to 3.0, and a number average molecular weight of 500 to 1,000.
The polyether polyol has an oxytetramethylene group and / or an oxypropylene group,
Content of the said organic solvent is 0-5 mass%.

  The viscosity at 25 ° C. of the block polyisocyanate composition in the present embodiment is preferably 10,000 to 150,000 mPa · s, preferably 10,000 to 150,000 mPa · s from the viewpoints of handleability and miscibility with the active hydrogen compound as the main agent. 100,000 mPa · s is more preferable, and 10,000 to 80,000 mPa · s is further preferable. Viscosity of the block polyisocyanate composition and the block polyisocyanate can be measured with an E-type viscometer up to 25600 mPa · s, and further with a rheometer (RS-1 manufactured by HAAKE). Moreover, a roller can be selected according to a viscosity.

[Block polyisocyanate]
The block polyisocyanate according to this embodiment is obtained by reacting a polyisocyanate having an isocyanate group at a terminal with a thermally dissociable blocking agent. Hereinafter, the polyisocyanate and the heat dissociable blocking agent will be described.

  The viscosity at 25 ° C. of the block polyisocyanate in the present embodiment is preferably 10,000 to 150,000 mPa · s from the viewpoint of reducing the content of the organic solvent and lowering the viscosity, and is 10,000 to 100,000 mPa. -S is more preferable and 10,000-80,000 mPa-s is still more preferable. The block polyisocyanate composition and the viscosity of the block polyisocyanate can be measured using a rheometer (RS-1 manufactured by HAAKE). Moreover, a roller can be selected according to a viscosity.

[Polyisocyanate]
The polyisocyanate according to the present embodiment has an isocyanate group at the terminal and is an aliphatic diisocyanate, an alicyclic diisocyanate, or a mixture of an aliphatic diisocyanate and an alicyclic diisocyanate (hereinafter also referred to as “diisocyanate”). , Polycaprolactone polyol, polyether polyol, or a mixture of polycaprolactone polyol and polyether polyol (hereinafter collectively referred to as “polyol”).

  Examples of the raw material of the polyisocyanate that is an intermediate of the block polyisocyanate composition of the present invention include aliphatic diisocyanate, alicyclic diisocyanate, polycaprolactone polyol, and oxypropylene group and / or oxytetramethylene group described below. The polyether polyol having is used.

(Aliphatic diisocyanate)
The aliphatic diisocyanate is not particularly limited, and specific examples include butane diisocyanate, pentane diisocyanate, hexamethylene diisocyanate (hereinafter also referred to as “HDI”), trimethylhexamethylene diisocyanate, and lysine diisocyanate. Of these, HDI is preferred because of its industrial availability. The said aliphatic diisocyanate may be used independently and may use 2 or more types together.

(Alicyclic diisocyanate)
Further, the alicyclic diisocyanate is not particularly limited, and specifically, isophorone diisocyanate (hereinafter also referred to as “IPDI”), hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and 1,4-cyclohexane diisocyanate. Etc. Of these, IPDI is preferred because of its industrial availability. The said alicyclic diisocyanate may be used independently and may use 2 or more types together.

  One of the aliphatic diisocyanate and the alicyclic diisocyanate may be used alone, or two or more of the aliphatic diisocyanate and the alicyclic diisocyanate may be used in combination.

(Polycaprolactone polyol)
The polycaprolactone polyol used in the present embodiment is not particularly limited. Specifically, the polycaprolactone polyol is obtained by ring-opening polymerization in the presence of a catalyst using ε-caprolactone as a divalent or higher, preferably trivalent alcohol as an initiator. be able to. Such initiators are not particularly limited, and specifically, dihydric alcohols such as ethylene glycol, propylene glycol, 1,3-butylene glycol, and neopentylbricol; trivalents such as trimethylolpropane and glycerin. Alcohol or the like is used. In terms of obtaining a low-viscosity polyisocyanate, a branched polycaprolactone polyol is preferred. Such polycaprolactone polyol can be obtained by using a trihydric or higher alcohol as an initiator.

  Although it does not specifically limit as a catalyst, Specifically, Organo titanium system compounds, such as tetrabutyl titanate, tetrapropyl titanate, and tetraethyl titanate; Tin octylate, dibutyltin oxide, dibutyltin laurate, stannous chloride, bromide A tin compound such as monotin is used.

  The ring-opening polymerization of ε-caprolactone is not particularly limited. Specifically, the molar ratio of ε-caprolactone and the initiator is set so as to obtain a desired molecular weight under a nitrogen gas atmosphere. The catalyst can be added by adding 0.1 to 100 ppm of the catalyst to caprolactone and reacting at a temperature of 150 to 200 ° C. for 4 to 10 hours.

  The number average molecular weight of the polycaprolactone polyol used is preferably 500 to 1,000, more preferably 500 to 800. By setting the number average molecular weight to 500 or more, it is possible to prevent the polycaprolactone polyol from becoming waxy in some cases and difficult to handle, and reacting a block polyisocyanate composition composed of polycaprolactone polyol and diisocyanate with an active hydrogen compound. The obtained cross-linked product is excellent in flexibility. In addition, when the number average molecular weight is 1,000 or less, the viscosity of the block polyisocyanate composition containing substantially no organic solvent using polycaprolactone polyol and diisocyanate tends to be low, and the handling property tends to be excellent. It is in. Furthermore, the effective NCO group content of the block polyisocyanate tends to be high, and the utility as a crosslinking agent tends to be excellent.

  Examples of commercially available polycaprolactone polyols include Plaxel 305, Plaxel 308, Plaxel 205H, and Plaxel 210CP (manufactured by Daicel Chemical Industries, Ltd., trade names); Polylite OD-X-2735, Polylite OD-X-2586. And Polylite OD-X-2587 (above, DIC Corporation, trade name).

(Polyether polyol)
The polyether polyol used in the present embodiment is not particularly limited as long as it has an oxytetramethylene group and / or an oxypropylene group, and specific examples include polyoxytetramethylene polyol and polyoxypropylene polyol.

(Polyoxytetramethylene polyol)
The polyoxytetramethylene polyol used in the present embodiment is produced by cationic polymerization of tetrahydrofuran using a catalyst. Although it does not specifically limit as a catalyst to be used, Specifically, an acetic anhydride-perchloric acid, a fluorosulfonic acid, or fuming sulfuric acid etc. are used. For example, the production of polyoxytetremethylene glycol is not particularly limited. Specifically, usually, approximately 1 to 30% by mass of fluorosulfonic acid is added to tetrahydrofuran as a raw material, and at a temperature of 5 to 65 ° C. The reaction can be carried out under conditions of reacting for several minutes to several tens of hours. Moreover, it can obtain by adding butylene oxide using a polybasic alcohol etc. as an initiator and a strongly basic catalyst etc. similarly to the manufacturing method of the polyoxypropylene polyol mentioned later. Furthermore, the molecular weight of the produced polyoxytetramethylene polyol is adjusted by changing the polymerization temperature, polymerization time, amount of catalyst used, and the like.

  The number average molecular weight of the polyoxytetramethylene polyol used is preferably 500 to 1,000, more preferably 800 to 1,000. By setting the number average molecular weight to 500 or more, a crosslinked product obtained by reacting a block polyisocyanate composition composed of polyoxytetramethylene polyol and diisocyanate with an active hydrogen compound tends to be excellent in flexibility. In addition, by setting the number average molecular weight to 1,000 or less, the viscosity of the block polyisocyanate composition containing substantially no organic solvent using polyoxytetramethylene polyol and diisocyanate tends to be low, and handling is easy. It tends to be excellent. Furthermore, the effective NCO group content of the block polyisocyanate tends to be high, and the utility as a crosslinking agent tends to be excellent.

  Commercially available polyoxytetramethylene diols include PTG650, PTG1000, and PTG-L1000 (above, manufactured by Hodogaya Chemical Co., Ltd., trade names); PTGM650, PTGM850, and PTGM-1000 (above, Mitsubishi Chemical ( Product name) and the like.

(Polyoxypropylene polyol)
The polyoxypropylene polyol used in the present embodiment is not particularly limited. Specifically, polyoxypropylene diol or triol; a so-called pluronic type polysiloxane obtained by addition polymerization of ethylene oxide at the terminal of polyoxypropylene diol or triol. And oxypropylene diol or triol; or polyoxypropylene polyoxyethylene polymer diol or triol. Among these, the pluronic type polyoxypropylene diol or triol is preferable because of its excellent reactivity with diisocyanate.

  Examples of the method for producing the polyoxypropylene polyol include a method in which propylene oxide, ethylene oxide or the like is added singly or as a mixture to the initiator and the catalyst, if necessary. The initiator is not particularly limited, and specific examples include polyhydric alcohols, polyhydric phenols, polyamines, alkanolamines, or mixtures thereof. More specifically, ethylene glycol, diethylene glycol, propylene glycol, Dihydric alcohols such as dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, bisphenol A; trihydric alcohols such as glycerin and trimethylolpropane; diamines such as ethylenediamine; or a mixture thereof Is mentioned. Further, the catalyst is not particularly limited, and specifically, hydroxides such as lithium, sodium and potassium; strong basic catalysts such as alcoholate and alkylamine; or metal porphyrin, double metal cyanide complex, metal and Examples of the complex include a complex with a chelating agent having a tridentate or more, and a complex metal complex such as a zinc hexacyanocobaltate complex. In addition, the method etc. which obtain polyoxypropylene polyol by dehydrating and condensing polyhydric alcohol are mentioned.

  The number average molecular weight of the polyoxypropylene polyol used is preferably 500 to 1,000, more preferably 800 to 1,000. By setting the number average molecular weight to 500 or more, a crosslinked product obtained by reacting a block polyisocyanate composition composed of polyoxypropylene polyol and diisocyanate with an active hydrogen compound tends to be excellent in flexibility. Further, by setting the number average molecular weight to 1,000 or less, the viscosity of the block polyisocyanate composition containing substantially no organic solvent using polyoxypropylene polyol and diisocyanate tends to be low, and the handling property is excellent. There is a tendency. Furthermore, the effective NCO group content of the block polyisocyanate tends to be high, and the utility as a crosslinking agent tends to be excellent.

  Examples of the commercially available polyoxypropylene polyol include Exenol 720, Exenol 1020, Exenol 1030 (above, manufactured by Asahi Glass Co., Ltd., trade name) and the like.

  In the present embodiment, the polyether polyol having at least one oxyalkylene group selected from polycaprolactone polyol, oxytetramethylene group and oxypropylene group is used alone or as a mixture. When used as a mixture, it may be mixed before reacting with diisocyanate, or each polyol may be reacted with diisocyanate alone to form polyisocyanate and then mixed. Furthermore, it is also possible to mix a single polyisocyanate after reacting with a blocking agent to form a blocked polyisocyanate.

(Number average molecular weight)
The number average molecular weight of the above-mentioned polycaprolactone polyol, polyether polyol, or a mixture of polycaprolactone polyol and polyether polyol is 500 to 1,000, preferably 500 to 800. When the number average molecular weight is less than 500, the crosslinked product obtained by reacting the block polyisocyanate composition with the active hydrogen compound is inferior in flexibility. On the other hand, when the number average molecular weight exceeds 1,000, the viscosity of the block polyisocyanate composition becomes high and handling becomes difficult. Furthermore, the effective NCO group content of the block polyisocyanate becomes too low, and the practicality as a crosslinking agent is poor. In addition, when mixing and using 2 or more types of polycaprolactone polyol or polyether polyol, or when using the mixture of polycaprolactone polyol and polyether polyol, the number average molecular weight of the mixture is calculated.

In the present embodiment, the “number average molecular weight” is a value obtained by measuring the hydroxyl value of a polyol and calculating the following formula.
Number average molecular weight = hydroxyl value × N × 1,000 / 56.11
Hydroxyl value: Value measured according to 6.4 of JIS K-1577 N: Average number of functional groups of polyol (number average number of hydroxyl groups in one molecule of polyol)

(Average number of functional groups)
The average functional group number of polycaprolactone polyol, polyether polyol, or a mixture of polycaprolactone polyol and polyether polyol is 2.4 to 3.0, preferably 2.6 to 3.0. If the average number of functional groups is 2.4 or more, the crosslinking property as a crosslinking agent is sufficient. Moreover, if an average functional group number is 3.0 or less, the viscosity of a block polyisocyanate composition will become low, and it is excellent in handleability. The “average functional group number” refers to the number of OH groups per molecule in polycaprolactone polyol, polyether polyol, or a mixture of polycaprolactone polyol and polyether polyol. The average number of functional groups can be controlled by the number of functional groups in the initiator. In addition, when mixing and using 2 or more types of polycaprolactone polyol or polyether polyol, or when using the mixture of polycaprolactone polyol and polyether polyol, an average functional group number is calculated with respect to the mixture.

(Method for producing polyisocyanate having an isocyanate group at the terminal)
The polyisocyanate according to this embodiment is obtained by reacting the diisocyanate with the polyol. Reaction of a polyol and diisocyanate is performed as follows. The reaction temperature is usually in the range of room temperature to 200 ° C, preferably in the range of 80 to 120 ° C. If reaction temperature is room temperature or more, reaction time will become short, and if it is 200 degrees C or less, the raise of the viscosity of the polyisocyanate by an undesirable side reaction can be avoided, and coloring of the polyisocyanate to produce | generate can also be avoided.

  The reaction may be performed in the absence of a solvent, or may be performed using any solvent inert to the isocyanate group. If necessary, a known catalyst may be used to promote the reaction between the isocyanate group and the hydroxyl group.

  In the reaction, the charging equivalent ratio of diisocyanate and polyol is preferably an NCO group / OH group equivalent ratio of 5 to 40. If this equivalent ratio is 5 or more, an increase in the viscosity of the polyisocyanate due to the sequential addition reaction between the diisocyanate and the polyol can be avoided. Further, it is preferable that the NCO group / OH group equivalent ratio is 40 or less because productivity is improved.

  At the end of the reaction, unreacted diisocyanate in the reaction mixture is recovered by a known method such as a thin film distillation apparatus or solvent extraction. If the residual amount of unreacted diisocyanate is small, odor, toxicity, or irritation caused by diisocyanate during heat curing can be avoided.

  The isocyanate group content (hereinafter referred to as NCO group content) of the polyisocyanate is preferably 7 to 15% by mass, more preferably 8 to 13% by mass, and substantially no solvent or diisocyanate. 12 mass% is more preferable. The NCO group content can be determined, for example, by reacting the isocyanate group of the polyisocyanate composition with an excess of amine (such as dibutylamine) and back-titration the remaining amine with an acid such as hydrochloric acid.

The viscosity of the polyisocyanate at 25 ° C. is preferably 800 to 8000 mPa · s in a state that does not substantially contain a solvent or diisocyanate. s, more preferably 800 to 6500 mPa.s. s, more preferably 800 to 5500 mPa.s. s. The viscosity was measured with an E-type viscometer (manufactured by Tokimec Co., Ltd.), and a standard rotor (1 ° 34 ′ × R24) was used as the rotor. The number of rotations is as follows.
100r. p. m. (If less than 128 mPa · s)
50r. p. m. (In the case of 128 mPa · s or more and less than 256 mPa · s)
20r. p. m. (In the case of 256 mPa · s or more and less than 640 mPa · s)
10r. p. m. (In the case of 640 mPa · s or more and less than 1280 mPa · s)
5r. p. m. (In the case of 1280 mPa · s or more and less than 2560 mPa · s)
2.5r. p. m. (In the case of 2560 mPa · s or more and less than 5120 mPa · s)
1.0r. p. m. (5120 mPa · s or more and less than 12800 mPa · s)
0.5r. p. m. (In the case of 12800 mPa · s or more and less than 25600 mPa · s)

[Thermal dissociable blocking agent]
The block polyisocyanate in the present embodiment blocks the isocyanate group of the polyisocyanate by reacting with a heat dissociable blocking agent. “Thermal dissociation” means a property of dissociating from the block polyisocyanate by heating.

  The thermally dissociable blocking agent according to this embodiment reacts with the isocyanate group of the polyisocyanate to block an isocyanate group rich in activity. Such a heat dissociable blocking agent is not particularly limited, and specifically includes oxime compounds, pyrazole compounds, amide compounds, amine compounds, active methylene compounds, alcohol compounds, acid amide compounds. And at least one selected from the group consisting of acid imide compounds, phenolic compounds, and imidazole compounds.

  Although it does not specifically limit as an oxime type compound, Specifically, formal oxime, aceto ald oxime, aceto oxime, methyl ethyl ketoxime, cyclohexanone oxime etc. are mentioned.

  Although it does not specifically limit as a pyrazole type compound, Specifically, a pyrazole, 3-methyl pyrazole, 3, 5- dimethyl pyrazole, etc. are mentioned.

  Although it does not specifically limit as an amide type compound, Specifically, acetoacetamide etc. are mentioned.

  The amine compound is not particularly limited, and specific examples include diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, and isopropylethylamine.

  The active methylene compound is not particularly limited, and specific examples include diethyl malonate, dimethyl malonate, and ethyl acetoacetate.

  Although it does not specifically limit as an alcohol type compound, Specifically, methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-etokasiethanol , 2-butoxyethanol and the like.

  Although it does not specifically limit as an acid amide type compound, Specifically, acetanilide, acetic acid amide, (epsilon) -caprolactam, (delta) -valerocactam, (gamma) -butyrolactam etc. are mentioned.

  Although it does not specifically limit as an acid imide type compound, Specifically, a succinic acid imide, a maleic acid imide, etc. are mentioned.

  Although it does not specifically limit as a phenol type compound, Specifically, phenol, cresol, ethylphenol, butylphenol, nonylphenol, dinonylphenol, styrenated phenol, hydroxybenzoic acid ester, etc. are mentioned.

  The imidazole compound is not particularly limited, and specific examples include imidazole and 2-methylimidazole.

  Among these, oxime compounds, acid amide compounds, amine compounds, and pyrazole compounds are preferable from the viewpoints of availability and viscosity of the produced block polyisocyanate, reaction temperature, reaction time, methyl ethyl ketoxime, ε-caprolactam, Diisopropylamine and 3,5-dimethylpyrazole are more preferable, and methylethylketoxime is still more preferable. The said heat dissociable block agent may be used individually by 1 type, and may use 2 or more types together by a desired ratio.

[Method for producing block polyisocyanate]
The block polyisocyanate according to this embodiment is obtained by reacting a polyisocyanate having an isocyanate group at a terminal with a thermally dissociable blocking agent. The blocked polyisocyanate may be one in which isocyanate groups are completely blocked by a known method, or one in which isocyanate groups are partially blocked, but it is preferable that all isocyanate groups are blocked. When all the isocyanate groups are blocked, (number of moles of blocking agent) / (number of moles of isocyanate group) is preferably 1.0 to 1.5, and preferably 1.0 to 1.3. More preferably, it is 1.0-1.1. The reaction for blocking the isocyanate group with the heat dissociable blocking agent can be generally carried out at -20 to 150 ° C, but preferably 0 to 100 ° C from the viewpoint of reaction rate and side reaction. The reaction may be performed in the absence of a solvent, or may be performed using any solvent inert to the isocyanate group. If necessary, a known catalyst may be used to promote the reaction between the isocyanate group and the blocking agent.

〔Organic solvent〕
The block polyisocyanate composition in this embodiment contains substantially no organic solvent. “Substantially free of organic solvent” means that the upper limit is 5% by mass, preferably 3% by mass, more preferably 1% by mass, and the lower limit is 0% by mass. By being “substantially free”, voids are hardly observed in the crosslinked product when heat-cured with the active hydrogen compound as the main agent.

  Although it does not specifically limit as an organic solvent, Specifically, a butyl acetate, propylene glycol monomethyl ether acetate, etc. are mentioned.

[Method for producing block polyisocyanate composition]
The manufacturing method of a block polyisocyanate composition is not specifically limited, It can carry out by mixing block polyisocyanate and an organic solvent by the well-known method using a twin-screw extruder etc.

(Curable composition)
The curable composition of this embodiment contains a block polyisocyanate composition and an active hydrogen compound. By heating a curable composition in which an active hydrogen compound substantially free of an organic solvent as a main ingredient was mixed with the block polyisocyanate composition, the thermally dissociable blocking agent bonded to the isocyanate group was dissociated and exposed. The isocyanate group reacts with active hydrogen in the active hydrogen compound to form a crosslinked product (cured product).

(Active hydrogen compound)
Although it does not specifically limit as said active hydrogen compound, Specifically, the compound in which two or more active hydrogen is couple | bonded in the molecule | numerator is mentioned, A polyol compound, a polyamine compound, a polythiol compound, etc. are mentioned. Among these, a polyol compound is preferable from the viewpoint of toughness. In particular, when a polyol is used as the active hydrogen compound, the curable composition is also referred to as a polyurethane composition.

  Although it does not specifically limit as said polyol compound, Specifically, polyester polyol, acrylic polyol, polyether polyol, polyolefin polyol, fluorine polyol, polycarbonate polyol, an epoxy resin, etc. are mentioned.

  Although it does not specifically limit as a polyester polyol, Specifically, it is obtained by the ring-opening polymerization of (epsilon) -caprolactone using the polyester polyol obtained by the condensation reaction of a dibasic acid and a polyhydric alcohol, for example, a polyhydric alcohol. Examples include polycaprolactones. The dibasic acid is not particularly limited, and is specifically selected from the group of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid. Single compounds or mixtures thereof. In addition, the polyhydric alcohol is not particularly limited, and specific examples include a single compound or a mixture selected from the group of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin and the like. .

  The acrylic polyol is not particularly limited, and specifically, an ethylenically unsaturated bond-containing monomer having a hydroxyl group, or a homopolymer of a mixture of two or more, or an ethylenically unsaturated group having a hydroxyl group. Examples thereof include a copolymer of a bond-containing monomer alone or a mixture of two or more types and another ethylenically unsaturated bond-containing monomer that can be copolymerized therewith or a mixture of two or more types.

  Although it does not specifically limit as an ethylenically unsaturated bond containing monomer which has a hydroxyl group, Specifically, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate , And hydroxybutyl methacrylate. Of these, hydroxyethyl acrylate and hydroxyethyl methacrylate are preferred.

  Other ethylenically unsaturated bond-containing monomers copolymerizable with the above monomers are not particularly limited, and specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, acrylic Acrylic acid esters such as acid-n-butyl, isobutyl acrylate, acrylic acid-n-hexyl, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, and phenyl acrylate; methyl methacrylate, methacryl Ethyl acetate, propyl methacrylate, isopropyl methacrylate, methacrylate-n-butyl, methacrylate-isobutyl, methacrylate-n-hexyl, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, benzyl methacrylate, Methacrylic acid esters such as phenyl chlorate; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid; acrylamide, methacrylamide, N, N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, malee Unsaturated amides such as acid amides and maleimides; vinyl monomers such as glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, dibutyl fumarate; and vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ- (meta And vinyl monomers having a hydrolyzable silyl group such as acryloxypropyltrimethoxysilane.

  The polyether polyol is not particularly limited. Specifically, for example, a hydroxide or a hydroxide such as lithium, sodium or potassium, a strong basic catalyst such as an alcoholate or an alkylamine is used for a single or mixture of polyvalent hydroxy compounds. Then, an alkylene oxide is reacted with a polyether polyol obtained by adding a single or mixture of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide, and a polyfunctional compound such as ethylenediamine. Polyether polyols obtained in this manner, and so-called polymer polyols obtained by polymerizing acrylamide or the like using these polyethers as a medium are included.

  The polyvalent hydroxy compound is not particularly limited, and specifically, polyhydric alcohol compounds such as diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol; erythritol, D-threitol, L-arabinitol, Sugar alcohol compounds such as ribitol, xylitol, sorbitol, mannitol, galactitol, rhamnitol; monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodesource; trehalose, sucrose, Disaccharides such as maltose, cellobiose, gentiobiose, lactose, and melibiose; trisaccharides such as raffinose, gentianose, and meletitose; tetrasaccharides such as stachyose And the like.

  The polyolefin polyol is not particularly limited, and specific examples include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

  The fluorine polyol is a polyol containing fluorine in the molecule and is not particularly limited. Specifically, the fluoroolefin and cyclovinyl ether disclosed in JP-A-57-34107 and JP-A-61-275111 are disclosed. And copolymers such as hydroxyalkyl vinyl ether and monocarboxylic acid vinyl ester.

  Although it does not specifically limit as polycarbonate polyol, Specifically, Dialkyl carbonates, such as dimethyl carbonate; Alkylene carbonates, such as ethylene carbonate; Low molecular carbonate compounds, such as diaryl carbonates, such as diphenyl carbonate, and the above-mentioned polyester polyol are used. Examples thereof include those obtained by condensation polymerization of a low molecular polyol.

  Epoxy resins are not particularly limited, and specifically include novolac type epoxy resins, glycidyl ether type epoxy resins, glycol ether type epoxy resins, aliphatic unsaturated compound epoxy resins, fatty acid ester type epoxy resins, polyvalent resins. Examples thereof include carboxylic acid ester type epoxy resins, aminoglycidyl type epoxy resins, β-methyl epichloro type epoxy resins, cyclic oxirane type epoxy resins, halogen type epoxy resins, and resorcin type epoxy resins.

  The hydroxyl value of the polyol compound is preferably from 5 to 300 mgKOH / g, more preferably from 15 to 250 mgKOH / g, more preferably from 20 to 200 mgKOH / g, from the viewpoint of crosslink density and mechanical properties of the cured resin. More preferably, it is g.

  In the curable composition of this embodiment, the equivalent ratio of blocked isocyanate groups to active hydrogen groups is usually set to 10: 1 to 1:10, preferably 5: 1 to 1: 5, more preferably 2: 1. Set to ~ 1: 2.

(Other curing agents)
In the curable composition of this embodiment, other curing agents such as a melamine curing agent and an epoxy curing agent can be used in combination. The melamine curing agent is not particularly limited, and specific examples thereof include a fully alkyl etherified melamine resin, a methylol group melamine resin, and an imino group melamine resin partially having an imino group. .

  When a melamine curing agent is used in combination, the addition of an acidic compound is effective. Although it does not specifically limit as an acidic compound, Specifically, carboxylic acid, a sulfonic acid, acidic phosphoric acid ester, and phosphorous acid ester are mentioned.

  Although it does not specifically limit as carboxylic acid, Specifically, an acetic acid, lactic acid, succinic acid, oxalic acid, maleic acid, and decanedicarboxylic acid are mentioned as a representative example. Although it does not specifically limit as sulfonic acid, Specifically, paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonyl naphthalene disulfonic acid is mentioned. The acidic phosphate ester is not particularly limited, and specifically, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, dilauryl phosphate, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate Can be mentioned. Further, the phosphite ester is not particularly limited, and specifically, diethyl phosphite, dibutyl phosphite, dioctyl phosphite, dilauryl phosphite, monoethyl phosphite, monobutyl phosphite, monooctyl phosphite Fight, monolauryl phosphite.

(Other additives)
Various additions such as curing accelerators, antioxidants, UV absorbers, light stabilizers, pigments, leveling agents, plasticizers, and surfactants are added to the block polyisocyanate composition and the polyol depending on the purpose and application. A mixture of agents can be used.

  Although it does not specifically limit as a hardening acceleration | stimulation catalyst, Specifically, tin-type compounds, such as dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, dimethyltin dineodecanoate, bis (2-ethylhexanoic acid) tin; Zinc compounds such as zinc 2-ethylhexanoate and zinc naphthenate; titanium compounds such as titanium 2-ethylhexanoate and titanium diisopropoxybis (ethylacetonate); cobalt such as cobalt 2-ethylhexanoate and cobalt naphthenate Compounds; Bismuth compounds such as bismuth 2-ethylhexanoate and bismuth naphthenate; Zirconium compounds such as zirconium tetraacetylacetonate, zirconyl 2-ethylhexanoate and zirconyl naphthenate; amine compounds and the like.

  The antioxidant is not particularly limited, and specific examples include hindered phenol compounds, phosphorus compounds, sulfur compounds, and the like.

  Although it does not specifically limit as a ultraviolet absorber, Specifically, a benzotriazole type compound, a triazine type compound, a benzophenone type compound etc. are mentioned.

  Further, the light stabilizer is not particularly limited, and specific examples include hindered amine compounds, benzotriazole compounds, triazine compounds, benzophenone compounds, benzoate compounds, and the like.

  Although it does not specifically limit as a pigment, Specifically, a titanium oxide, carbon black, indigo, pearl mica, aluminum, etc. are mentioned.

  Further, the leveling agent is not particularly limited, and specific examples include silicone oil.

  Although it does not specifically limit as a plasticizer, Specifically, phthalic acid esters, a phosphoric acid type compound, a polyester type compound, etc. are mentioned.

  Although it does not specifically limit as surfactant, Specifically, polyethyleneglycol etc. are mentioned.

[Method for producing curable composition]
The method for producing the curable composition is not particularly limited, and the block polyisocyanate composition and the active hydrogen compound may be mixed by a known method such as mixing in a mixing tank equipped with a stirrer. it can.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited at all by these. The measurement methods and evaluation methods used in the examples and comparative examples are as follows. Below, the synthesis example of block polyisocyanate is shown.

[Measurement method of NCO group content of polyisocyanate]
Dissolve 2 to 3 g of polyisocyanate in 20 mL of toluene, add 20 mL of 2N di-n-butylamine toluene solution, mix and leave for 15 minutes. 70 ml of isopropanol was added and back titrated with 1N hydrochloric acid. The NCO group content (% by mass) of the polyisocyanate was determined from the result of this back titration.

[Measurement method of effective NCO group content]
The effective NCO group content was calculated from the amount of polyisocyanate charged, the amount of NCO group, and the amount of blocking agent charged.

[Method for measuring viscosity of polyisocyanate]
The viscosity of the polyisocyanate was measured at 25 ° C. using an E-type viscometer (manufactured by Tokimec Co., Ltd.), and a standard rotor (1 ° 34 ′ × R24) was used as the rotor. The number of rotations is as follows.
100r. p. m. (If less than 128 mPa · s)
50r. p. m. (In the case of 128 mPa · s or more and less than 256 mPa · s)
20r. p. m. (In the case of 256 mPa · s or more and less than 640 mPa · s)
10r. p. m. (In the case of 640 mPa · s or more and less than 1280 mPa · s)
5r. p. m. (In the case of 1280 mPa · s or more and less than 2560 mPa · s)
2.5r. p. m. (In the case of 2560 mPa · s or more and less than 5120 mPa · s)
1.0r. p. m. (5120 mPa · s or more and less than 12800 mPa · s)
0.5r. p. m. (In the case of 12800 mPa · s or more and less than 25600 mPa · s)

[Method for measuring viscosity of block polyisocyanate]
The viscosity of the block polyisocyanate was measured at 25 ° C. using a rheometer (RS-1 manufactured by HAAKE). The rotor used was 2 ° × R10.

[Hydroxyl value]
The hydroxyl value was measured according to 6.4 of JIS K-1577.

[Number average molecular weight]
The number average molecular weight was determined by the following formula by measuring the hydroxyl value of the polyol.
Number average molecular weight = hydroxyl value × N × 1,000 / 56.11
N: Average number of functional groups of polyol (number average number of hydroxyl groups in one molecule of polyol)

[Viscosity increase ratio]
The viscosity increase ratio was determined by the following formula. The viscosities obtained by the above measuring methods were used.
Viscosity increase ratio = viscosity of block polyisocyanate ÷ viscosity of polyisocyanate

[Synthesis Example 1]
(Synthesis of block polyisocyanate A-1)
To a 2 L flask equipped with a stirrer, thermometer, condenser, and nitrogen blowing tube, 1,000 g of HDI and polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation, trifunctional, number 237 g of an average molecular weight of 850 and a hydroxyl value of 202 mg KOH / g was charged, and the reaction was performed by stirring at 95 ° C. for 1 hour in a nitrogen atmosphere. By removing unreacted HDI from the obtained reaction solution under the conditions of 160 ° C. (27 Pa) for the first time and 150 ° C. (13 Pa) for the second time using a flow-down type thin film distillation apparatus, polyisocyanate a-1 was obtained. Obtained. The obtained polyisocyanate a-1 was a pale yellow transparent liquid, yield 350 g, viscosity at 25 ° C. was 5400 mPa · s, and NCO group content was 9.1 mass%.

  Next, 100 g of the obtained polyisocyanate a-1 was charged into a 0.5 L flask equipped with a stirrer, a thermometer, and a cooling pipe, and methyl ethyl ketoxime was added as a blocking agent to the NCO-containing molar amount of the polyisocyanate. .05 times molar amount was gradually added. After all was added, warmed to 60 ° C. and stirred for 2 hours. After confirming that absorption due to isocyanate disappeared by FT-IR, stirring was stopped and block polyisocyanate A-1 was obtained. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Synthesis Example 2]
(Synthesis of block polyisocyanate A-2)
100 g of polyisocyanate a-1 obtained in the same manner as in Synthesis Example 1 was charged into a 0.5 L flask equipped with a stirrer, thermometer, and condenser and heated to 80 ° C., and 3,5-dimethylpyrazole was The polyisocyanate was gradually added in an amount of 1.05 times the molar amount of the NCO-containing polyisocyanate. After all was added, the mixture was further stirred for 2 hours. After confirming that absorption due to isocyanate disappeared by FT-IR, stirring was stopped to obtain block polyisocyanate A-2. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Synthesis Example 3]
(Synthesis of block polyisocyanate A-3)
Instead of 237 g of polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation), polycaprolactone (PCL) triol (product name: Plaxel 305, manufactured by Daicel Corporation, trifunctional, number average) A polyisocyanate a-3 was obtained in the same manner as in Synthesis Example 1 except that 150 g of a molecular weight of 550 and a hydroxyl value of 308 mg KOH / g was used. The obtained polyisocyanate a-3 was a pale yellow transparent liquid, yield 270 g, viscosity at 25 ° C. was 5000 mPa · s, and NCO group content was 11.5 mass%.

  Moreover, except having used polyisocyanate a-3 instead of polyisocyanate a-1, the process similar to the synthesis example 1 was performed and block polyisocyanate A-3 was obtained. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Synthesis Example 4]
(Synthesis of block polyisocyanate A-4)
Instead of 237 g of polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation), polycaprolactone (PCL) triol (product name: Polylite OD-X-2735, manufactured by DIC Corporation, 3 Functionality, number average molecular weight 500, hydroxyl value 307 mgKOH / g) 65 g, and polyoxytetramethylene (POT) diol (product name: PTG1000, manufactured by Hodogaya Chemical Industries, difunctional, number average molecular weight 1,000, hydroxyl value 115 mgKOH / g) A polyisocyanate a-4 was obtained in the same manner as in Synthesis Example 1 except that 130 g of the mixture (from the above, the average functional group number of polyol 2.5 and the number average molecular weight 750) was used. The obtained polyisocyanate a-4 was a pale yellow transparent liquid, yield 295 g, viscosity at 25 ° C. was 2800 mPa · s, and NCO group content was 8.8% by mass.

  Moreover, except having used polyisocyanate a-4 instead of polyisocyanate a-1, the process similar to the synthesis example 1 was performed and block polyisocyanate A-4 was obtained. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Synthesis Example 5]
(Synthesis of block polyisocyanate A-5)
Instead of 237 g of polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation), polyoxypropylene (POP) triol (product name: Exenol 720 (manufactured by Asahi Glass Co., Ltd., trifunctional, number) Except having used 190g of average molecular weight 700 and hydroxyl value 160mgKOH / g), it processed similarly to the synthesis example 1 and obtained polyisocyanate a-5. The obtained polyisocyanate a-5 was light yellow transparent. The yield was 310 g, the viscosity at 25 ° C. was 2500 mPa · s, and the NCO group content was 10.1% by mass.

  Next, except having used polyisocyanate a-5 instead of polyisocyanate a-1, the process similar to the synthesis example 1 was performed and block polyisocyanate A-5 was obtained. The effective NCO group content, viscosity, and viscosity increase ratio are shown in Table 1.

[Comparative Synthesis Example 1]
(Synthesis of block polyisocyanate B-1)
To a 2 L flask equipped with a stirrer, a thermometer, a condenser tube, and a nitrogen blowing tube, 1,000 g of HDI was charged, and 0.08 g of tetramethylammonium capriate was added with stirring at 60 ° C. The reaction was allowed to proceed at 60 ° C., and after 4 hours, when the conversion rate to polyisocyanate reached 20% by measuring the isocyanate group content and refractive index of the reaction solution, 0.2 g of phosphoric acid was added to react. Stopped. After the reaction solution was filtered, unreacted HDI was removed in the same manner as in Synthesis Example 1 to obtain isocyanurate type polyisocyanate b-1. The obtained polyisocyanate b-1 was a light yellow transparent liquid, the yield was 200 g, the viscosity at 25 ° C. was 1400 mPa · s, and the NCO group content was 23.3 mass%.

  Next, the process similar to the synthesis example 1 was performed except having used polyisocyanate b-1 instead of polyisocyanate a-1, and block polyisocyanate B-1 was obtained. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Comparative Synthesis Example 2]
(Synthesis of block polyisocyanate B-2)
Polycaprolactone (PCL) triol (product name: OD-X-2588, manufactured by DIC Corporation) instead of 237 g of polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation), trifunctional The polyisocyanate b-2 was obtained in the same manner as in Synthesis Example 1 except that 325 g of a number average molecular weight of 1250 and a hydroxyl value of 135 mg KOH / g was used. The obtained polyisocyanate b-2 was a pale yellow transparent liquid, yield 440 g, viscosity at 25 ° C. was 11,000 mPa · s, and NCO group content was 7.5% by mass.

  Next, except having used polyisocyanate b-2 instead of polyisocyanate a-1, the process similar to the synthesis example 1 was performed, and block polyisocyanate B-2 was obtained. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Comparative Synthesis Example 3]
(Synthesis of block polyisocyanate B-3)
Instead of 237 g of polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation), polycaprolactone (PCL) diol (product name: Plaxel 205U, manufactured by Daicel Corporation, bifunctional, number average) A polyisocyanate b-3 was obtained in the same manner as in Synthesis Example 1 except that 217 g of a molecular weight of 530 and a hydroxyl value of 212 mgKOH / g was used. The obtained polyisocyanate b-3 was a pale yellow transparent liquid, yield 340 g, viscosity at 25 ° C. was 1500 mPa · s, and NCO group content was 9.9 mass%.

  Next, except having used polyisocyanate b-3 instead of polyisocyanate a-1, the process similar to the synthesis example 1 was performed, and block polyisocyanate B-3 was obtained. The effective NCO group content, viscosity, and viscosity increase ratio are shown in Table 1.

[Comparative Synthesis Example 4]
(Synthesis of block polyisocyanate B-4)
Instead of 237 g of polycaprolactone (PCL) triol (product name: Polylite OD-X-2586, manufactured by DIC Corporation), polyoxypropylene (POP) tetraol (product name: Exenol 410 NE, manufactured by Asahi Glass Co., Ltd., tetrafunctional, A polyisocyanate b-4 was obtained in the same manner as in Synthesis Example 1 except that 112 g of a number average molecular weight of 550 and a hydroxyl value of 410 mg KOH / g was used. The obtained polyisocyanate b-4 was a pale yellow transparent liquid, yield 270 g, viscosity at 25 ° C. was 15000 mPa · s, and NCO group content was 15.3% by mass.

  Next, except having used polyisocyanate b-4 instead of polyisocyanate a-1, the process similar to the synthesis example 1 was performed, and block polyisocyanate B-4 was obtained. Table 1 shows the effective NCO group content, viscosity, and viscosity increase ratio.

[Examples 1 to 5, Comparative Examples 1 to 4]
(Curing test)
Block polyisocyanates A-1 to 5 and B-1 to 4 obtained in Synthesis Examples 1 to 5 and Comparative Synthesis Examples 1 to 4 and a polyol (a polycarbonate diol manufactured by Asahi Kasei Chemicals Corporation, product name: Duranol (registered trademark) T5652 And a hydroxyl value of 56 mgKOH / g, a number average molecular weight of 2,000) were prepared so that the equivalent ratio of effective NCO groups / OH groups was 1.0, and each curable composition was obtained. Each curable composition was applied on a special coated plate (made of polypropylene) with an applicator to form a coating film. After baking in an oven at the temperature shown in Table 1 for 30 minutes, the coating film was peeled off, and the remaining film ratio (gel fraction) when immersed in acetone at 23 ° C. for 24 hours was measured. A gel fraction of 90% or more was rated as ◯, and a gel fraction of less than 90% as x. The obtained results are shown in Table 1.
Residual film ratio (gel fraction) = coating weight after acetone immersion / coating weight before acetone immersion × 100

[Examples 6 to 25, Comparative Examples 5 to 9]
(Void observation of cross-linked product)
Each curable composition was poured into an aluminum pan having a diameter of 50 mm and a height of 10 mm to a height of 8 mm. After heating in an oven maintained at 160 ° C. for 30 minutes, the cross-linked product was taken out and the cross section was observed. In the case where voids having a diameter of 100 μm or more were not observed, the mark was ◯. The obtained results are shown in Table 2.

  Furthermore, butyl acetate was added as an organic solvent to each of the block polyisocyanates A-1 to 5 obtained in Synthesis Examples 1 to 5 so that the content was 8% by mass, 5% by mass, 3% by mass, and 1% by mass. Then, a crosslinked product was produced in the same manner as described above. Then, the void observation in each crosslinked material was performed. The obtained results are shown in Table 2.

  The block polyisocyanate composition of the present invention is suitable for use as a solventless crosslinking agent. Moreover, even if the thickness of a crosslinked material is thick, the curable composition of this invention can avoid generation | occurrence | production of a void by not containing an organic solvent substantially. Therefore, the block polyisocyanate composition and the curable composition of the present invention are excellent as paints, adhesives, pressure-sensitive adhesives, inks, sealing agents, casting agents, sealants, surface modifiers, coating agents and the like. Demonstrate performance.

Claims (4)

A block polyisocyanate composition substantially free of organic solvent,
The block polyisocyanate is obtained by reacting an aliphatic diisocyanate and / or an alicyclic diisocyanate with a polycaprolactone polyol and / or a polyether polyol, a polyisocyanate having an isocyanate group at a terminal, and a thermally dissociable block. Is obtained by reacting the agent,
The polycaprolactone polyol and / or the polyether polyol has an average functional group number of 2.4 to 3.0, and a number average molecular weight of 500 to 1,000.
The polyether polyol has an oxytetramethylene group and / or an oxypropylene group,
The content of the organic solvent is 0 to 5% by mass.
A curable composition containing a block polyisocyanate composition and an active hydrogen compound and substantially free of an organic solvent (excluding an aqueous coating composition) . The curable composition according to claim 1, wherein the thermally dissociable blocking agent is at least one selected from the group consisting of an oxime compound, a pyrazole compound, an amide compound, an amine compound, and an active methylene compound. object. The curable composition according to claim 1 or 2, wherein the aliphatic diisocyanate is hexamethylene diisocyanate. The curable composition according to any one of claims 1 to 3 , wherein the active hydrogen compound is a polyol compound.