JPH08325353A - New blocked polyisocyanate - Google Patents

Abstract

PURPOSE: To obtain a blocked polyisocyanate capable of providing polyurethane resin coating materials capable of giving coating films excellent in physical properties such as low temperature curability, weatherability, flexibility, etc. CONSTITUTION: This blocked polyisocyanate is derived from a polyisocyanate having (1) 4.0 to 20 isocyanate functional groups on the average, (2) isocyanate concentration of 5 to 20wt.%, (3) a viscosity of 2000 to 200,000mPa.s/25 deg.C, and (4) an isocyanate cyclic trimer content of 10wt.%, or less, and obtained by reaction between an aliphatic and/or alicyclic diisocyanate and at least one kind of polyhydric hydroxy compound having 4 to 10 hydroxyl functional groups on the average, followed by substantially eliminating the unreacted monomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-yellowing type block polyisocyanate used for polyurethane paint.

[0002]

2. Description of the Related Art Non-yellowing type polyisocyanate has good weather resistance, and when it is used as a curing agent for urethane paints, the resulting coating film has excellent physical properties such as chemical resistance and flexibility. Therefore, it is extremely useful, such as being applied to metals, plastics, etc., in the fields of automobile paints, architectural paints, pre-coated metals, paints for cans and the like.

In addition to diisocyanate, a modifying agent such as polyol is used depending on the application. For example, in Japanese Patent Publication No. 6-70120, in order to provide more flexibility, the number average molecular weight is 400 to having a carbon number of 2 to 30.
1,500, a polyester having an average number of hydroxyl groups in the molecule of 2 to 3 is used, and in JP-A-3-40048, polycaprolactone diol and / or triol having a number average molecular weight of 500 to 1,500 is used as a modifier. There is.

Further, in order to improve the drying property, for example, in JP-A-48-1099, a hydroxyl group-containing acrylic copolymer is reacted with a polyisocyanate. Further, in order to improve the sagging resistance to a vertical surface, JP-A-57-102918 proposes a specific molecular weight, a specific hydroxyl value, and a specific hydroxyl group / isocyanate equivalent ratio.

Further, since polyurethane resin paints are generally two-component, it is extremely inconvenient to use them. That is, a normal urethane resin coating consists of two components, a polyol and a polyisocyanate, and it is necessary to store them separately and mix them at the time of coating. Once mixed, the coating gels in a short time and cannot be used. Is. This is the line of pre-coat metal and post-coat etc. including anti-corrosion steel plate by spray coating, dipping coating, roll coating, electrodeposition coating etc. performed on automobiles, home appliances, office equipment, metal products in construction etc., plastic molded products etc. It is extremely difficult to automate the coating field or the field of using an adhesive containing polyisocyanate, an adhesiveness-imparting agent, or a sealing agent. Furthermore, since it is necessary to sufficiently wash the coating machine and the coating tank at the end of the work, the work efficiency is significantly reduced.

In order to improve the above-mentioned drawbacks, it has been conventionally proposed to use a blocked polyisocinenate in which active isocyanate groups are blocked with a blocking agent. Although this blocked polyisocyanate does not react with the polyol at room temperature, it has the property of dissociating the blocking agent at high temperature and regenerating an active isocyanate group to react with the polyol to cause a cross-linking reaction. be able to.

However, the above crosslinking reaction requires a high baking temperature such as 150 to 200 ° C.
A high baking temperature not only increases energy costs, but also increases air pollution that accompanies it. I am using tools, but sometimes special jigs cannot be used.

Accordingly, there has been a strong demand for a blocked polyisocyanate which is capable of forming an excellent one-pack type polyurethane-based coating material and which is particularly curable at low temperatures.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a blocked polyisocyanate which makes it possible to realize a one-pack type polyurethane coating composition having excellent performance overcoming the above-mentioned problems.

[0010]

As a result of earnest studies, the present inventors have surprisingly found that a specific polyisocyanate obtained from a specific polyhydric hydroxy compound having 4 to 10 functional groups and a specific diisocyanate has an isocyanate group. It has been discovered that a blocked polyisocyanate in which is blocked with a heat-dissociative blocking agent overcomes the above-mentioned problems, and the present invention has been reached.

That is, in the present invention, a polyhydric hydroxy compound having an average hydroxyl group functional group number of 4 to 10 is reacted with an aliphatic or alicyclic diisocyanate alone or in a mixture, and then unreacted monomers are substantially removed. Isocyanate: (1) Isocyanate average number of functional groups: 4.0 to 20 (2) Isocyanate concentration: 5 to 20% by weight (3) Viscosity: 2000 to 200,000 mPa.s. s / 2
5 ° C. (4) Concentration of isocyanate cyclic trimer: 10% by weight or less The present invention relates to a blocked polyisocyanate in which 50 to 100% of an isocyanate group of a polyisocyanate is blocked with a heat dissociable blocking agent.

The diisocyanate used in the present invention is preferably an aliphatic or alicyclic diisocyanate. Aromatic isocyanates can also be used for applications where light resistance is not particularly required. As the aliphatic diisocyanate,
An alicyclic diisocyanate having 4 to 30 carbon atoms is preferably one having 8 to 30 carbon atoms, and examples thereof include tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene diisocyanate, and 2 , 2,4-trimethyl-hexamethylene-
1,6-diisocyanate, lysine diisocyanate,
Examples thereof include isophorone diisocyanate, 1,3-bis (isocyanatomethyl) -cyclohexane, and 4,4′-dicyclohexylmethane diisocyanate. Of these, hexamethylene diisocyanate (hereinafter referred to as HMDI) and isophorone diisocyanate (hereinafter referred to as IPDI) are preferable from the viewpoint of weather resistance and industrial availability, and they may be used alone or in combination.

The polyhydric hydroxy compound used in the present invention has an average number of hydroxyl functional groups of 4 to 10, preferably 4 to 8.
Is. The average number of hydroxyl groups is the number of hydroxyl groups statistically possessed by one molecule of the polyvalent hydroxy compound, and the number average molecular weight of the polyvalent hydroxy compound and the number of parts by weight of all hydroxyl groups contained in 1 part by weight of the polyvalent hydroxy compound (hereinafter referred to as hydroxyl group). The concentration is calculated by the following general formula (1).

[0014]

[Equation 1]

Specific examples of such polyhydroxy compounds include, for example, diglycerin, ditrimethylolpropane,
Pentaerythritol, dipentaerythritol and the like, for example, erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, glycidol, mannitol, galactitol,
Sugar alcohol compounds such as rhamnitol, for example, arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodeose and other monosaccharides, for example, trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose. , Disaccharides such as melibiose, trisaccharides such as raffinose, gentianose, and melezitose, and tetrasaccharides such as stachyose.

In addition to the polyhydroxy compound,
There are also polyether polyols, polyester polyols, epoxy polyols, and the like, which use the polyhydric hydroxy compound as a raw material. As the polyether polyols, in the polyhydric hydroxy compound alone or in a mixture,
For example, hydroxides such as lithium, sodium and potassium, alcoholates, strong base catalysts such as alkylamines are used to prepare ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide,
Polyether polyols obtained by adding alkylene oxide such as styrene oxide alone or in a mixture, polyether polyols obtained by further reacting alkylene oxide with a polyfunctional compound such as ethylenediamine, and these polyethers The medium includes so-called polymer polyols obtained by polymerizing acrylamide and the like.

As the polyester polyols, for example, a single dibasic acid 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 is used alone. Alternatively, a polyester polyol resin obtained by a condensation reaction of a mixture and a polyhydric alcohol selected from the group of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc., alone or in a mixture, and, for example, Examples thereof include polycaprolactone polyols obtained by ring-opening polymerization addition of ε-caprolactone to a polyhydric alcohol.

The epoxy polyols include, for example, novolac type, β-methyl epichloro type, cyclic oxirane type, glycidyl ether type, glycol ether type, epoxy type of aliphatic unsaturated compound, epoxidized fatty acid ester type, polyvalent carboxylic acid ester. Examples thereof include epoxy polyols such as type, aminoglycidyl type, halogenated type and resorcin type.

Among these polyols, the above-mentioned polyether polyols and polyester polyols are preferable, the polyether polyols are more preferable, and the polyether polyol to which propylene oxide is added is particularly preferable. The number average molecular weight is preferably 500 to 5000, more preferably 600.
~ 3000.

These may be used alone or in combination of two or more, and may be modified with urethane or the like.
When reacting a polyhydric hydroxy compound and diisocyanate, the equivalent ratio of isocyanate group / hydroxyl group is 2/1 to 3
0/1 is preferred. If it is less than 2/1, the viscosity of the reaction liquid after the reaction will be high, and the equipment investment for industrial production will be large, and if it exceeds 30/1, the productivity will be reduced. It is preferably 5/1 to 20/1. The polyhydric hydroxy compound and the diisocyanate may be mixed before heating the reaction solution, or the diisocyanate may be charged into the reactor first,
After reaching the predetermined temperature, the polyhydroxy compound may be added all at once or in portions.

A solvent may be used in the above reaction. In that case a solvent inert to the isocyanate groups should be used. The reaction temperature is 60 to 200 ° C, preferably 130 to 180 ° C. If the temperature is lower than 60 ° C, the reaction rate is slow and the increase in the average number of functional groups of isocyanate, which is presumed to be due to the allophanatization reaction, is unlikely to occur. If it exceeds 200 ° C, an undesirable side reaction such as coloring of the obtained polyol occurs.

The reaction time varies depending on the reaction temperature, but is 1 to
It is 8 hours, preferably 2 to 6 hours. Upon reaction,
A catalyst can also be used. As the catalyst, those having basicity are generally preferable, and examples thereof include quaternary amine compounds such as hydroxide of tetraalkylammonium and weak organic acid salts such as acetic acid and capric acid, for example, trioctylamine and 1,4-diazabicyclo. Tertiary amine compounds such as (2,2,2) octane, 1,8-diazabicyclo (5,4,0) undecene-7, 1,5-diazabicyclo (4,3,0) nonene-5, for example, A catalyst that promotes the allophanatization reaction of a metal organic weak acid salt such as zinc, tin, lead, and iron such as acetylacetone metal salt such as zinc is also effective.

The catalyst concentration is usually selected from the range of 10 ppm to 1.0% based on the isocyanate compound.
A part of the urethane bond existing in the reaction solution is converted into an allophanate bond, and the obtained polyisocyanate has both the urethane bond and the allophanate bond. The conversion of urethane bonds to allophanate bonds is 10 to 90%, preferably 20 to 80%. When the above value is less than 10%, it is difficult to increase the average number of functional groups of the isocyanate, and the viscosity of the polyisocyanate may be too high. If it exceeds 90%, mechanical properties such as toughness, which are excellent physical properties of the urethane bond, are difficult to develop, and heat resistance may be poor.

The yield is approximately 20% by weight or more and 70% by weight or less. Remove unreacted diisocyanate and solvent,
A polyisocyanate of the invention is obtained. The average number of isocyanate functional groups in the polyisocyanate referred to in the present invention is the number of isocyanate functional groups statistically possessed by one molecule of polyisocyanate, and the number average molecular weight of polyisocyanate and all isocyanate functional groups contained in 1 part by weight of polyisocyanate. It can be calculated by the following general formula (2) from the number of parts by weight (hereinafter, referred to as isocyanate concentration).

[0025]

[Equation 2]

The polyisocyanate thus obtained has an average isocyanate functional group number of 4.0 to 20, preferably 5 to 14, and more preferably 6 to 12. When the value is less than 4.0, the curability is insufficient when used in a coating composition, and when it exceeds 20, the surface property of the coating film may be adversely affected. As a disclosed polyisocyanate having a high average number of functional groups, JP-A-2-132116 discloses a specific polyisocyanate structure. From the structure, the number of isocyanate groups per molecule of polyisocyanate is 3 to 6.
However, these polyisocyanates having the above-mentioned value of 4 or more do not have sufficient durability because they contain an aromatic isocyanate.

The inventors of the present invention previously disclosed in Japanese Unexamined Patent Publication No. Hei 6-31296.
No. 9, the average number of functional groups of isocyanate is 4.5 to 1
A urethane-based coating composition using a blocked polyisocyanate having an isocyanurate structure of 0 has been proposed.
The present invention is a blocked polyisocyanate having a limited isocyanate cyclic trimer. The polyisocyanate of the present invention has an isocyanate concentration of 5 to 20% by weight.
If it is less than 5% by weight, a sufficient crosslinking density cannot be obtained. If it exceeds 20% by weight, the crosslink density becomes too high.

The viscosity of polyisocyanate is 2,000 to
200,000 mPa · s / 25 ° C, preferably 5,0
It is 00-100,000 mPa * s / 25 degreeC. Two
If it is less than 000 mPa · s / 25 ° C, sagging is likely to occur during coating on a vertical surface, and 200,000 mPa · s / 2
When the temperature exceeds 5 ° C, the appearance of the coating film deteriorates, which is not preferable. The isocyanate cyclic trimer is 10% by weight or less based on the product. When it exceeds 10% by weight, the average number of functional groups of isocyanate is lowered, and in addition, the cyclic trimer itself is not high in crosslinkability and may be eluted in a solvent or the like after baking. In the case of low temperature baking, this tendency is further increased. This concentration is indicated by the area percent of the isocyanate cyclic trimer peak obtained by gel permeation chromatography using tetrahydrofuran as the carrier and refractive index as the detector.

The blocked polyisocyanate of the present invention can be obtained from the above polyisocyanate and the heat dissociative blocking agent. Examples of the heat dissociable blocking agent include alcohol-based, alkylphenol-based, phenol-based, active methylene, mercaptan-based, acid amide-based, acid imide-based, imidazole-based, urea-based, oxime-based, amine-based, imide-based,
Examples include pyrazole compounds. Examples of more specific blocking agents are shown below. (1) Methanol, ethanol, 2-propanol, n
-Butanol, sec-butanol, 2-ethyl-1-
Alcohols such as hexanol, 2-methoxyethanol, 2-etokashiethanol, 2-butoxyethanol, (2) alkylphenols; mono- and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent, For example, n-propylphenol, i
-Propylphenol, n-butylphenol, sec
-Butylphenol, t-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-
Monoalkylphenols such as octylphenol and n-nonylphenol, di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-t-butylphenol,
Di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-
Dialkylphenols such as nonylphenol, (3) phenolic; phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester, etc. (4) active methylene; dimethyl malonate, diethyl malonate, methyl acetoacetate, aceto Ethyl acetate, acetylacetone, etc. (5) Mercaptan type; butyl mercaptan, dodecyl mercaptan, etc. (6) Acid amide type; Acetanilide, acetic acid amide, ε-
Caprolactam, δ-valerolactam, γ-butyrolactam, etc. (7) Acid imide type; succinimide, maleic imide, etc. (8) Imidazole type; imidazole, 2-methylimidazole, etc. (9) Urea type; urea, Thiourea, ethyleneurea, etc. (10) oxime type; formaldoxime, acetoaldoxime, acetoxime, methylethylketoxime, cyclohexanone oxime, etc. (11) amine type; diphenylamine, aniline, carbazole, di-n-propylamine, diisopropyl Amine, isopropylethylamine, etc., (12) imine type; ethyleneimine, polyethyleneimine, etc., (13) bisulfite; sodium bisulfite, etc., (14) pyrazole type; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole Zo Etc., there is.

Among them, alkylphenol type, oxime type, acid amide type and active methylene type are preferable, and nonylphenol, acetoxime, methylethylketoxime, ε-caprolactam, ethyl acetoacetate and dialkyl malonate are preferable, and oxime type and active methylene type. Two or more types may be mixed, such as the use of two types of active methylene compounds.

The above heat dissociative blocking agent preferably blocks 50 to 100% of the isocyanate groups of the polyisocyanate. As a matter of course, a polyisocyanate capped only at less than 50% has insufficient paint storage properties that a blocked polyisocyanate must have. The blocking reaction between the polyisocyanate and the blocking agent can be carried out regardless of the presence or absence of the solvent.
When using a solvent, it is necessary to use a solvent which is inert to the isocyanate group.

In the blocking reaction, organic metal salts such as tin, zinc and lead and alkali metal alcoholates such as tertiary amine and sodium may be used as catalysts. The reaction can generally be carried out at -20 to 150 ° C,
It is preferably 30 to 100 ° C. If the temperature exceeds 150 ° C, a side reaction may occur. On the other hand, if the temperature is lower than -20 ° C, the reaction rate becomes low, which is disadvantageous.

The blocked polyisocyanate thus obtained is useful as, for example, a curing agent for polyurethane coatings, in combination with a polyvalent hydroxyl compound. As the polyvalent hydroxyl compound, for example, a hydroxyl value of 10 to 500 mgK
Acrylic polyols, polyester polyols and epoxy polyols having an OH / g, an acid value of 0 to 200 mgKOH / g and a number average molecular weight of 300 to 60,000 are particularly preferably used.

[0034]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples. All percentages are by weight and all parts are by weight. The evaluation was performed according to the following. (Measurement of number average molecular weight) The number average molecular weight is determined by gel permeation chromatograph (hereinafter referred to as GP
This is the number average molecular weight based on polystyrene measured. Equipment: Tosoh Corporation HLC-802A Carrier: Tetrahydrofuran Detection method: Differential refractometer (Isocyanate cyclic trimer concentration) The peak concentration of the molecular weight (for example, 504 in the case of HMDI) corresponding to the diisocyanate cyclic trimer obtained by the GPC measurement is the area percent thereof. Expressed as (Measurement of allophanate binding concentration) FT-N of JEOL
MR "FX90Q" was used, acetone-d6 was used as the solvent, and as a result of H-NMR measurement, the peak integrated value of the allophanate bond and the urethane bond was expressed by allophanate bond / (allophanate bond + urethane bond). 9
The above is ◎, less than 0.9 0.1 or more is ○, less than 0.1 is ×
Indicated by. . (Viscosity measurement) The viscosity was measured at 25 ° C using an Emila type rotational viscometer. (Gel Fraction) A value of the undissolved part weight when the cured coating film was immersed in acetone at 20 ° C. for 24 hours was calculated with respect to the weight before immersion, and 80% or less was ×, 80% or more and less than 90% was ◯,
90% or more is represented by ⊚.

When the main component was an epoxy polyol, methanol was used as the solvent.

[0036]

[Production Example 1] A 4-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing tube, and a dropping funnel was filled with a nitrogen atmosphere, and 600 parts of HMDI was used as a polyether polyol (Asahi Denka Co., Ltd.). Of ADEKA NEW POLYOL WR-474) (trade name of "Adeka New Polyol WR-474") (isocyanate group / hydroxyl group equivalent ratio 5/1) was charged, and the temperature inside the reactor was maintained at 120 ° C for 5 hours while stirring.
Unreacted HMD by reducing the temperature of the reaction solution and using a thin film evaporator.
I was removed. The molecular weight of the reaction product is measured by GPC,
It was confirmed that the polyisocyanate of the present invention was produced by measuring the isocyanate concentration by titration. The viscosity of the obtained polyisocyanate at 25 ° C. is 20,000 mPa · s, and the isocyanate content is 1
3.2%, the number average molecular weight was 1,690, the average number of isocyanate functional groups was 5.3, and the isocyanate cyclic trimer concentration was 1.7%. The allophanate bond concentration of this polyisocyanate was ◯.

[0037]

[Production Examples 2-8],

[Comparative Production Examples 1 and 2] Using the same apparatus as in Production Example 1,
The reaction was carried out under the reaction conditions shown in Tables 1 and 2 (however, Table 2 is an annotation of Table 1. The same applies hereinafter), and unreacted HMDI was removed in the same manner as in Production Example 1. The physical properties of the obtained polyisocyanate are shown in Tables 1 and 2.

[0038]

[Comparative Production Example 3] HMDI was installed in the same device as in Production Example 1.
Charge 600 g and 11 g of 1,3-butanediol,
The temperature in the reactor was maintained at 80 ° C. for 2 hours while stirring under a nitrogen atmosphere. After that, the temperature inside the reactor was maintained at 60 ° C., an isocyanurate-forming reaction catalyst tetramethylammonium capryate was added, and when the yield reached 28%, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HMDI was removed using a thin film evaporator. The physical properties of the obtained polyisocyanate are shown in Tables 1 and 2.

[0039]

Example 1 (Production of Block Polyisocyanate) A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen blowing tube, and a dropping funnel was filled with a nitrogen atmosphere,
100 parts of the polyisocyanate obtained in Preparation Example 1 and 30 parts of methyl isobutyl ketone were charged, and methyl ethyl ketoxime was added dropwise until the characteristic absorption of isocyanate in the infrared spectrum disappeared so that the reaction temperature did not exceed 50 ° C. A 80% min blocked polyisocyanate solution was obtained.

[0040]

Examples 2 to 8 (Production of Block Polyisocyanate) Block polyisocyanate solutions having a solid content of 80% were obtained in the same manner as in Example 1 except that the polyisocyanates obtained in Production Examples 2 to 8 were used.

[0041]

[Comparative Examples 1 to 3] (Production of Block Polyisocyanate) The procedure of Example 1 was repeated except that the polyisocyanates obtained in Comparative Production Examples 1 to 3 were used to obtain a blocked polyisocyanate solution having a solid content of 80%. It was

[0042]

[Comparative Example 4] HMDI-based polyisocyanate "Duranate TPA-100" (trade name of Asahi Kasei Corporation, isocyanate average number of functional groups 3.2, viscosity 1,400 mPa · s
/ 25 ° C) was carried out in the same manner as in Example 1 to obtain a blocked polyisocyanate solution having a solid content of 80%.

[0043]

[Comparative Example 5] HMDI-based polyisocyanate "Sumijour N3500" (trade name of Sumitomo Bayer Urethane, isocyanate average number of functional groups 3.3, viscosity 2,500 mP
a · s / 25 ° C.) was carried out in the same manner as in Example 1 to obtain a blocked polyisocyanate solution having a solid content of 80%.

[0044]

[Comparative Example 6] HMDI-based polyisocyanate "Coronate HX" (trade name of Nippon Polyurethane, isocyanate average number of functional groups 3.4, viscosity 2,000 mPa · s / 25
℃) was used in the same manner as in Example 1 except that the solid content was 80
% Blocked polyisocyanate solution was obtained.

[0045]

[Reference Example 1] The blocked polyisocyanate obtained in Example 1 and an acrylic polyol (Dainippon Ink's trade name Acridic A-801) were blended so that the equivalent ratio of blocked isocyanate group / hydroxyl group would be 1.0. Then, 0.5% of dibutyltin dilaurate was added to the coating resin content, and as a thinner, a weight ratio of ethyl acetate / toluene / butyl acetate / xylene / propylene glycol monomethyl ether acetate was 30/30/20/15 /
Add the mixture of 5 and for 20 seconds / 20 with Ford Cup # 4
The temperature was adjusted to ° C. Spray paint the resulting paint solution and
After setting for 0 minutes at room temperature, it was baked for 30 minutes in an oven maintained at 120 ° C. Table 3 shows the obtained coating film physical property measurement results.

[0046]

[Reference Examples 2-8] The procedure of Reference Example 1 was repeated except that the blocked polyisocyanates obtained in Examples 2-8 were used. Table 3 shows the obtained coating film physical property measurement results.

[0047]

[Comparative Reference Examples 1 to 6] Comparative Reference Examples 1 to 6 were carried out in the same manner as in Reference Example 1 except that shown in Table 3. Table 3 shows the obtained results.

[0048]

Reference Example A (Production of Epoxy Polyol) A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen blowing tube, and a dropping funnel was placed in a nitrogen atmosphere,
Bisphenol A type epoxy resin (Asahi Ciba brand name AE
R6071, 100 parts of epoxy equivalent 460) and 82 parts of methyl isobutyl ketone were charged, the reactor internal temperature was set to 90 ° C., and then 23 parts of diethanolamine was added dropwise over 30 minutes while maintaining the reaction temperature at 90 ° C. 30 minutes after the end of dropping,
The reaction temperature was raised to 120 ° C. and kept for 1 hour. An epoxy polyol solution having a resin solid content of 60% and a resin content of hydroxyl group of 400 mgKOH / g was obtained.

[0049]

Reference Example 9 The epoxy polyol of Reference Example A and Example 1
The block polyisocyanate of 1 was used and blended so that the equivalent ratio of block isocyanate / hydroxyl group would be 0.5, and applicator coating was performed. After setting at room temperature for 30 minutes, 3 in an oven maintained at 120 ° C
Bake for 0 minutes. Table 3 shows the obtained results.

[0050]

[Reference Examples 10 to 16] The same operation as in Reference Example 9 was carried out except that the results shown in Table 3 were used. The results are shown in Table 3.

[0051]

[Comparative Reference Examples 7 to 12] The same procedure as in Reference Example 9 was carried out except that the blocked polyisocyanates obtained in Comparative Examples 1 to 6 were used. The results are shown in Table 3.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

The block polyisocyanate of the present invention is
It is useful as a raw material for a one-component polyurethane-based paint having excellent coating film properties such as low-temperature curability, light resistance, and flexibility.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area C09D 175/04 PHV C09D 175/04 PHV // C07C 265/14 9451-4H C07C 265/14

Claims (3)

[Claims] 1. A polyisocyanate obtained by reacting an aliphatic or alicyclic diisocyanate alone or a mixture with a polyvalent hydroxy compound having an average hydroxyl functional group of 4 to 10 and then substantially removing unreacted monomers. , (1) average number of functional groups of isocyanate: 4.0 to 20 (2) concentration of isocyanate: 5 to 20% by weight (3) viscosity: 2000 to 200,000 mPa.s. s / 2
5 [deg.] C. (4) Isocyanate cyclic trimer concentration: 10% by weight or less The blocked polyisocyanate in which 50 to 100% of the isocyanate groups of the polyisocyanate are blocked with a heat dissociable blocking agent. 2. The blocked polyisocyanate according to claim 1, wherein the polyisocyanate has both an allophanate bond and a urethane bond. 3. The blocked polyisocyanate according to claim 1, wherein the polyhydric hydroxy compound is a propylene oxide adduct polyether polyol and / or polyester.