JPH02620A - Blocked polyisocyanate and coating composition containing the same - Google Patents

Abstract

PURPOSE:To obtain a blocked polyisocyanate improved in compatibility with polyol and heat stability by blocking the NCO groups of a specified isocyanurate polyisocyanate by reaction with an active hydrogen compound. CONSTITUTION:Hexamethylene diisocyanate (a) is trimerized in the presence of 10ppm-1.0%, based on component (a), catalyst at 20-160 deg.C and this reaction is stopped at a conversion <=25%. The product is purified by removing excessive component (a) to obtain an isocyanurate polyisocyanate (A) of a viscosity (at 25 deg.C in a state free of component (a) and solvent) <=1600cps, an isocyanurate cyclic trimer content >=60% and a uretedione dimer content <=10%. Component A is reacted with an active hydrogen compound, as a blocking agent, ion such an amount as to give an equivalent ratio of the NCO groups of component A to the active hydrogen atoms of component B of 0.9-1.0 to obtain a blocked polyisocyanate in which the NCO groups are blocked.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides hexamethylene diisocyanate (hereinafter referred to as H
A block polyisocyanate obtained by bronching a polyisocyanate obtained by cyclic trimerization of (abbreviated as MD I) with an active hydrogen-containing compound, especially a block polyisocyanate with improved compatibility with polyols,
A one-component polyurethane thermosetting coating composition composed of a block polyisocyanate and a polyvalent hydroxyl compound, and a composition composed of a block polyisocyanate, a polyvalent hydroxyl compound, and a specific thermosetting coating resin.
The present invention relates to a liquid polyurethane thermosetting coating composition. More specifically, the present invention relates to a composition that dramatically improves the flexibility (particularly the bending resistance) of a coating film obtained from a melamine-based thermosetting resin coating without reducing its hardness.

(Conventional technology) Conventionally, polyurethane resin paints have excellent abrasion resistance,
In addition to having chemical resistance and stain resistance, aliphatic, especially H
Polyurethane resin paints using polyisocyanates derived from MDI have even better weather resistance, and the demand for them is on the rise.

However, since the -C polyurethane resin paint is two-component, it is quite inconvenient to use.

That is, a typical urethane paint consists of two components, a polyol component and a polyisocyanate, and it is necessary to store them separately and mix the two components at the time of coating.

Furthermore, the current situation is that paints mixed with -tan become gelled within several hours to several days and become unusable. This makes it extremely difficult to perform automatic painting in fields where line painting is performed, such as automobile or light electrical painting.

Furthermore, since it is necessary to thoroughly clean the coating machine and coating tank after the work is completed, work efficiency is significantly reduced. Conventionally, in order to improve the above-mentioned drawbacks, all of the active isocyanate groups were treated with an active hydrogen-containing compound (hereinafter referred to as a blocking agent).
It has been proposed to use blocked polyisocyanates. This block polyisocyanate is
Although it does not react with the polyol at room temperature, at relatively high temperatures the blocking agent is dissociated and the active isocyanate groups are regenerated and react with the polyol to cause a crosslinking reaction, so the above-mentioned drawbacks can be improved. . Therefore, many blocked polyisocyanates have been investigated. For example, as a blocked polyisocyanate in which the active isocyanate groups of a polyisocyanate derived from an aliphatic compound having excellent weather resistance, particularly HMD I, are blocked with a blocking agent, a block form of biuret-type polyisocyanate (for example, JP-A 1982-144021), isocyanurate-type polyisocyanate blocks (for example, JP-A-55-38380), urethane-modified isocyanurate-type polyisocyanate blocks (for example, JP-A-60-149572) Publications) etc. are known. In addition, many active hydrogen-containing compounds such as phenol-based, lactam-based, and oxime-based blocking agents are known. Furthermore, since melamine-cured paints form extremely hard coatings, they are widely used in high-grade coating applications (top coats for automobile steel plates, top coats for home appliance steel plates, etc.).

(Problems to be Solved by the Invention) Conventionally known blocks of billet-type polyisocyanate, blocks of isocyanurate-type polyisocyanate, and blocks of urethane-modified isocyanurate-type polyisocyanate are relatively difficult to solve. It has a problem of poor compatibility with polyols of low polarity, especially fluorine-containing polyols.

Further, in the case of blocked polyisocyanate, the blocking agent dissociates from -Jl at a high temperature of 150'C or more, and active isocyanate groups are regenerated and recombined with the hydrogen groups of the polyol to form crosslinks. However, in the case of blocks of urethane-modified isocyanate-type polyisocyanates, the skeleton contains not only isocyanurate rings with good thermal stability but also urethane bonds and allophanate bonds with poor thermal stability, which is undesirable because side reactions occur during baking.

Furthermore, since the block body of billet type polyisocyanate also contains bonds with poor thermal stability, side reactions occur during baking, which poses a problem.

Therefore, it is freely compatible with relatively low polarity polyols,
In addition, there has been a long-awaited demand for an aliphatic polyisocyanate block with good thermal stability, which is less likely to cause side reactions other than dissociation of the blocking agent during baking.

Furthermore, the coating film obtained from the melamine cured paint has extremely high hardness and extremely poor flexibility, and has the disadvantage that, for example, even if a baked coating on a steel plate is bent slightly, it will crack or peel. In particular, as a recent trend, there has been a remarkable shift to pre-painted metals (a method of applying baking paint to steel plates before they take the form of products) in applications such as home appliances, steel furniture, and other high-grade steel products. There are strict requirements for bending resistance, which is called workability, and it is extremely difficult to apply conventional thermosetting resin paints as they are. In addition, pitting resistance (
Cracks in the paint film when pebbles, etc. fly off and hit the paint film surface,
Requirements have become particularly strict in recent years regarding durability against peeling) and ability to follow deformation of the base material in plastic coatings (flexibility of the coating film when the base plastic deforms), and conventional melamine-cured paints cannot meet these requirements. could not be satisfied.

(Means for Solving the Problems) As a result of extensive research into these points, the present inventors have developed a hexamethylene diisocyanate-based polyisocyanate having a specific structure, physical properties, and composition distribution, and an active Intensive research has been carried out to solve the above drawbacks using blocked polyisocyanate whose isocyanate groups are substantially blocked by a reaction product with a hydrogen-containing compound, and to improve the drawbacks of the conventional thermosetting resin coatings. As a result, it was discovered that a composition that dramatically improves the flex resistance of a coating film without degrading other properties can be obtained by using the blocked polyisocyanate of the present invention, and the present invention was completed.

That is, the present invention provides a polyisocyanate obtained by cyclic trimerization of hexamethylene diisocyanate, which has a viscosity of 1 at 25°C in a state substantially free of hexamethylene diisocyanate monomer and solvent.
, 600 cps or less, and has an isocyanurate cyclic trimer content of 60% or more and a uretdione dimer content of 10% or less, and a reaction product of an active hydrogen-containing compound. A block polyisocyanate in which isocyanate groups are blocked, a one-wave type polyurethane thermosetting coating composition comprising the block polyisocyanate and a polyhydric hydroxyl compound, and the above-mentioned block polyisocyanate and the following melon formula A one-wave type polyurethane thermosetting coating composition consisting of a compound represented by the following formula and a polyhydric hydroxyl compound, in which the weight ratio of the blocked polyisocyanate to the compound represented by the following formula is 0.2 to 2. .

／　　＼ R,R.

(At least one of Rl''-R6 is an alkyl etherified methylol group, and the others represent hydrogen and/or methylol groups.) The above-mentioned uretdione dimer and isocyanurate trimer can be It is measured by the area percentage of each mer peak obtained by gel permeation chromatography (GPC).

The blocked polyisocyanate of the present invention has a viscosity of 1,600 cps or less at 25°C and isocyanurate cyclic trimer content of 60% or more. , surprisingly improved compatibility with relatively less polar polyols, especially fluorine-containing polyols. Furthermore, by achieving a uretdione dimer content of 10% or less, good thermal stability of the polyisocyanate skeleton is achieved. If the isocyanurate cyclic trimer content is less than 60%, the compatibility with various polyols and melamine curing agents and the solubility with poor solvents will decrease, which is not preferable. Further, polyisocyanates having a uretdione dimer content of more than 10% are not preferred because residual monomers substantially increase during storage of the curing agent.

Furthermore, if the viscosity at 25°C exceeds 1.6 QOcps, the viscosity during preparation of the paint increases and the appearance of the resulting paint film also deteriorates.

The isocyanurate type polyisocyanate used in the production of the block polyisocyanate of the present invention is HMD
It is produced by performing a trimerization reaction of I using a catalyst. The reaction is stopped when the conversion rate of this trimerization reaction is approximately 25% or less, and excess HMDI is removed and purified. Examples of the catalyst used for trimerization include tetraalkylammonium hydroxide, organic acid salts, organic acid salts of alkylcarboxylic acids, aminosilyl group-containing compounds, and the like.

The catalyst concentration varies depending on the catalyst used and the reaction temperature, but is usually selected from the range of 10 ppm to 1.0% based on HMDI.

The reaction may be carried out with or without a solvent. When using a solvent, it is natural to select a solvent that does not have reactive activity toward isocyanate groups.

The reaction temperature is usually 20-160°C, preferably 40-12°C.
0''C2, more preferably selected from the range of 60 to 90'C.

The progress of the reaction was measured by NC0% measurement of the reaction solution, infrared spectrometry,
It can be tracked by refractive index measurement, etc.

If the conversion reaction of HMD I to isocyanurate proceeds too much, the viscosity of the product increases and the isocyanurate cyclic 3
Since the polymer content decreases and a product with the desired physical properties cannot be obtained, the conversion rate of the reaction needs to be kept at about 25% or less.

When the reaction reaches the desired conversion rate, a catalyst deactivator such as sulfuric acid or phosphoric acid is added to stop the reaction. After stopping the reaction and removing the deactivated catalyst if necessary, excess HMD I and solvent are removed to obtain the product. This H
Removal of MDI and solvent is performed, for example, by a thin film evaporation can or a solvent extraction method.

In the synthesis of the polyisocyanate used in the production of the block polyisocyanate of the present invention, alcohols such as methanol, ethanol, methanol, ethylene glycol, 1,3-butanediol,
Neopentyl glycol, 2-ethyl-1,3 hexanediol, trimethylolpropane, polypropylene glycol, phenol, etc. may also be used. However, if the amount of co-catalyst is increased, the polyisocyanate skeleton will have more urethane bonds and allophanate bonds, which have lower thermal stability than isocyanate, which is not preferable.

The thermal stability of various bonds related to isocyanate groups is
Advan-ces in the order of isocyanate, urea, urethane, billet, and allophanate.
Urethane 5science and Tec
hnology Vol 6P175.

The blocked polyisocyanate of the present invention can be obtained by reacting the above-mentioned isocyanurate type polyisocyanate with various blocking agents by a known method. Blocking agents used in this reaction include, for example, phenol-based, lactam-based, oxime-based, active methylene-based, alcohol-based, mercaptan-based, acid amide-based, imide-based, amine-based, imidazole-based, and urea-based blocking agents. Although any block may be used, phenolic, lactam, oxime, etc. blocks are advantageously used. Specific examples of blocking agents include the following.

Phenol-based bronching agents Phenol, cresol, xylenol, ethylphenol, etc. Lactam-based blocking agents ε-caprolactam, δ-parellolactam, γ-butyrolactam, β-propiolactam, etc. Oxime-based blocking agents Formamide oxime, acetaldoxime, acetoxime, methyl ethyl ketoxime , diacetyl monooxime, benzophenone oxime, cyclohexanone oxime, methylpropyl ketoxime, 2-pentanone oxime, isobutyl ketoxime, etc. Active methylene blocking agents diethyl malonate, dimethyl malonate, ethyl acetoacetate, methyl acetoacetate, Alcohol-based bronchants such as acetylacetone, methanol, ethanol, propatool, isoproptool, butanol, 2-ethylhexanol, alkyl ether alkylene glycol monoalcohol [e.g., R, -OCHz CHOH (RI= C+ to C1 alkyl group, R2 -HorC1-C4 alkyl group)]
As a specific method for producing the blocked polyisocyanate of the present invention, the polyisocyanate and the blocking agent are mixed in an equivalent ratio of isocyanate group/active hydrogen in the blocking agent -0,
9 to 1.0, preferably 0.95 to 1.0, and is reacted by a known method. Although the blocking reaction can be performed without a solvent, ester-based, ether-based,
It is preferable to carry out the reaction in a suitable solvent such as a ketone type or an aromatic type solvent. Furthermore, in the reaction, organic metals such as tin, zinc, and lead, tertiary amines, and the like may be used as catalysts.

The one-wave type polyurethane thermosetting coating composition comprising a bronch polyisocyanate and a polyhydric hydroxyl compound of the present invention has good compatibility with polyols, and the cured product thereof forms a coating film with excellent physical properties.

In this composition, the molar ratio of the blocked isocyanate groups in the blocked polyisocyanate to the hydroxyl groups in the polyhydric hydroxy compound is preferably in the range of 0.4:1 to 2:1.

The polyhydric hydroxy compound contains at least 2 molecules in one molecule.
These compounds include aliphatic hydrocarbon polyols, polyether polyols, polycarbonate polyols, polyester polyols, epoxy resins and acrylic polyols, fluorine-containing polyols, etc. Can be mentioned. These polyols can also be used as a mixture as appropriate.

Specific examples of aliphatic hydrocarbon polyols include terminal hydroxyl-terminated polybutadiene and hydrogenated products thereof, and examples of polyether polyols include polyhydric alcohols such as glycerin and propylene glycol alone or Polyether polyols and polytetramethylene glycols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide alone or as a mixture to a mixture, and polyfunctional compounds obtained by reacting alkylene oxides with polyfunctional compounds such as ethylenediamine and ethanolamines. and so-called polymer polyols obtained by polymerizing acrylamide or the like using these polyethers as a medium.

Examples of polyester polyols include succinic acid,
A single or mixture of dibasic acids selected from the group of carboxylic acids such as adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid, and ethylene glycol, propylene glycol, and diethylene glycol. , butylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc., and polyester polyol resins obtained by condensation reaction with polyhydric alcohols selected from the group such as butylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc., and e.g. Examples include polycaprolactones obtained by ring-opening polymerization.

In addition, examples of epoxy resins include novolak type,
β-methylepicro type, cyclic oxirane type, glycidyl ether type, glycidyl ester type, glycol ether type, epoxidized type of aliphatic unsaturated compound, epoxidized aliphatic ester type, polyvalent carboxylic acid ester type, aminoglycidyl type, halogen Examples include epoxy resins such as chemical type and resorcin type.

Acrylic polyols are obtained by copolymerizing a polymerizable monomer having one or more active hydrogens in one molecule and other monomers that can be copolymerized therewith. Examples of such substances include acrylic esters with active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl methacrylate. -2-hydroxypropyl, methacrylic acid-
Methacrylic acid esters having active hydrogen such as 2-hydroxybutyl, acrylic acid monoesters or methacrylic acid monoesters of glycerin, acrylic acid monoesters or methacrylic acid monoesters of trimethylolpropane, singly or in mixtures. Acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, -0-butyl acrylate, and 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and methacrylate. unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, In the presence of unsaturated amides such as N-methylolacrylamide, diacetone acrylamide, and other polymerizable monomers such as glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, alone or in the presence of a mixture, or in the absence of Examples include acrylic polyol resins obtained by polymerization in the presence of acrylic polyols.

Examples of polycarbonate polyols include those obtained by known methods using aromatic polyhydric alcohols such as bisphenol A and aliphatic and alicyclic polyhydric alcohols such as 1,6-hexanediol as raw materials.

Furthermore, the fluorine-containing polyol is, for example, JP-A-57-
34107, JP-A-57-34108, JP-A-61-176620, etc., containing fluoroolefin as a constituent, JP-A-594
1321, JP-A No. 59-96177, and JP-A-61-118466, further modified fluorine-containing polyols containing the above-mentioned fluoroolefins, JP-A-58 Examples include those in which an unsaturated monomer having a fluorine-containing group in the side chain is used as a constituent component, as seen in Japanese Patent No. 34866.

In addition, as a commercially available fluorine-containing polyol, Lumiflon L
F-100, Lumiflon LF-200 (manufactured by Asahi Glass, trade name), K-700, K-701 (manufactured by Dainippon Ink & Chemicals, trade name), and the like. Preferred among these polyhydric hydroxy compounds are acrylic polyols.

The single-wave polyurethane thermosetting coating composition of the present invention comprising a blocked polyisocyanate (a), a compound (b) represented by the following formula, and a polyhydric hydroxy compound (c) has compatibility with a polyol. The cured product becomes a coating film with excellent physical properties. In this composition, the compound (
When mixing a), the amount added must be 0.2 to 2 in weight ratio to compound (b). If the weight ratio is less than 0.2, the desired improvement in flexibility will be insufficient, and if it is more than 2, the hardness of the coating may decrease,
This is not preferable because the dependence of the coating film on the initial curing temperature increases.

／　　＼ R3R.

(However, at least one of R3 to R5 is an alkyl etherified methylol group, and the others represent hydrogen and/or a methylol group.) In addition, as a method for producing the composition, compound (c) itself may be It is of course possible to add and mix (a) and (b), but compound (c)
It is more preferable to mix compounds (a) and (b) in advance.

In addition, when mixing compounds (a), (b) and compound (c), there is no particular limitation on using a solvent, but it is more preferable to mix compounds (a), (b) and compound (c).
It is desirable to use a common parent solvent for c).

Furthermore, the compound (b) used in the composition includes:
Commercially available butylated melamine resins (Dainippon Ink & Chemicals Co., Ltd. Super Henokamine/J820--60) are mentioned.

In the composition of the present invention, when mixing each component, a suitable solvent such as benzene, toluene, xylene, cyclohexane, mineral spirit, hydrocarbons such as naphtha, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. Depending on the purpose and use, it can be appropriately selected and used from the group of ketones, esters such as ethyl acetate, n-butyl acetate, and cellosolve acetate. These solvents may be used alone or in combination.

Furthermore, various additives used in the technical field, such as catalysts, pigments, leveling agents, antioxidants, plasticizers, and surfactants, may be mixed and used depending on the purpose and use.

It is also possible to add stabilizers such as hindered phenols, hensitriazoles, and hindered amines to the composition of the present invention. Examples of hindered amine stabilizers include pentaerythrityl-tetrakis(3-(3,5-di-tert-butyl 4-hydroxyphenyl)propionate), 2,2'-thiodiethylbis-(3-(3,5-
di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3-(3,5- di-tert-butyl-4-hydroxyphenyl) propionate,
1,3.5-tris(4-tert-butyl-3-hydroxy-2,6-dimethyl)isocyanuric acid, etc., henctriazole stabilizers include 2-(2-hydroxy-5-methylphenyl)-2H -benzotriazole,
2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-henztriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl) 2H-
Examples of hindered amine stabilizers such as benzotriazole include bis(1,2,2,6,6-bentamethyl-4-
piperidyl) sebacate, bis(2°2.6.6-tetramethyl-4-piperidyl) sepaket, 4-hendyloxy-2,2,6,6-titramethylbiperidine, and the like.

These may be used alone or in combination. Particularly preferred is a combination of a hindered amine and a hindered phenol or a hindered amine and a benzotriazole. The amount of stabilizer added is 1 to the prepolymer.
100pp-20000ppm, preferably 500p
pm to 5000 ppm.

When the composition of the present invention is used in paint applications, the baking temperature is selected to be higher than the dissociation temperature of the blocking agent and less than 200°C. For example, when the blocking agent is methyl ethyl ketoxime, it is commonly used to harden by baking at a temperature of 150° C. or higher, and when using ethyl acetoacetate, the blocking agent is baked at a temperature of 120° C. or higher.

(Effects of the Invention) The blocked polyisocyanate of the present invention has excellent compatibility with relatively low polarity polyols, especially fluorine-containing polyols. Furthermore, since it is derived from isocyanurate type polyisocyanate which has good thermal stability, side reactions other than dissociation of the blocking agent during baking are unlikely to occur. A one-wave type polyurethane thermosetting coating composition made by blending a block polyisocyanate and a polyhydric hydroxyl compound with such excellent properties can be applied to, for example, metals, resin products, leather, concrete I
It can be applied to a wide range of objects such as wood and wood. Further, the composition is commonly used in the presence of a solvent and has a coating concentration of 10 to 90% by weight.

Particularly preferred are applications such as pre-coated metals that require post-processability, automotive steel plate coatings that require chip resistance, and plastic coatings that require flexibility.

Furthermore, the specific block polyisocyanate (a)
A one-molded polyurethane thermosetting coating composition consisting of a compound (b) and a polyvalent stroxy compound (c) has various coating properties (e.g., high hardness, high gloss) that conventional thermosetting resin coatings have. , good durability, etc.), the bending resistance, which is a drawback, can be dramatically improved.

(Examples) Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples in any way.

In addition, various measurements in Examples were carried out by the methods shown below.

1) The content of dimers, trimers, etc. was determined from the area percentage of each peak obtained by GPC measurement using the following apparatus.

Equipment: Toyo Soda HLC-802A column:
Toyo Soda ■ G 1000 HxLx 1 bottle Toyo Soda ■ G 200011XLX 1 bottle G 3000 HX
LX 1 carrier: THF Detection method: Differential refractometer Data processing: Toyo Soda ■ CP-8000 (2) Free HMD in the product [The content was measured using gas chromatography.

(3) Product viscosity was measured using an Emira type rotational viscometer.

(4) The infrared absorption spectrum of the product was measured using a Fourier transform infrared spectrophotometer model FT/IR5M manufactured by JASCO θKosha.

Example I-1 A four-eye flask equipped with a stirrer, a thermometer, and a reflux condenser was charged with 1000 g of HMD I and 300 g of xylene, and 0.3 g of tetramethylammonium cabriate was divided into portions as a catalyst under stirring at 60'CPA. and added every 30 minutes.

The reaction was continued at 60°C, and after 4 hours, when the conversion rate of HMDI to isocyanurate reached 21% by measuring the NC○ content and refractive index of the reaction solution, 0.2% of phosphoric acid was added.
The reaction was stopped by adding g.

After that, heating was continued at 90°C for 1 hour, and then
When cooled to room temperature, tetramethylammonium phosphate, a deactivated catalyst, precipitated as crystals.

After removing this precipitate by filtration, the solvent and unreacted HMD r were removed using a falling film evaporation can under the conditions of 0.8 mmHg/160°C for the first time and 0.1 mmHg/160°C for the 12th time. Removed and collected.

The obtained product was a pale yellow, transparent liquid, with a yield of 21
Viscosity at 0 g and 25°C is 1.300 cps, NC
O content is 23.5%, uretdione dimer content is 1
%, the isocyanurate trimer content was 70%. Also, the free HMD I monomer content was 0.2%.

50 g of the obtained product, 14.7 g of cellosolve acetate,
24.9 g of methyl ethyl ketoxime was added in portions over 30 minutes to a mixture of 14.7 g of xylene. The reaction temperature was maintained at 50° C., and the reaction was continued for an additional 90 minutes after the addition of methyl ethyl ketoxime was completed. It was confirmed by infrared absorption spectrum that there was no absorption of isocyanate groups.

Appearance, solid content, and
Table 1 shows the measurement results of the viscosity at 25°C and the content of blocked isocyanate groups.

Moreover, the infrared absorption spectrum of the obtained blocked polyisocyanate is shown in FIG.

Example 1-2 HMD 1 1000 g in the same device as Example I-1
was charged, and 0.2 g of choline was added as a catalyst in the same manner as in Example 1 while stirring at 50°C.

After 3 hours, when the conversion rate of HMD I reached 12%, the reaction was stopped with phosphoric acid.

Next, purification was performed in the same manner as in Example I-1.

The obtained product was a pale yellow, transparent liquid, with a yield of 12
0g, viscosity at 25°C is 1,000 cps, NC
O content is 23.8%, uretdione dimer content is 1
%, the content of 31 isocyanurates was 75%. Also, the free HMDI monomer content was 0.1%.

In a mixture of 50 g of the obtained product, 25.1 g of cellosolve acetate, and 25.1 g of xylene, 25.1 g of methyl ethyl ketoxime was converted and reacted in the same manner as in Example 1-1.

Appearance, solid content, and
Table 1 shows the measurement results of the viscosity at 25°C and the content of blocked isocyanate groups.

Comparative Example I-1 The reaction was carried out in the same manner as in Example 1-1 except that the amount of catalyst was 0.4 g and the reaction time was 6 hours. After stopping the reaction at a conversion rate of 33%, the same reaction as in Example 1 was carried out. A purification operation was performed.

The obtained product was a pale yellow, transparent liquid, and the yield was 33.
Viscosity at 0g and 25°C is 2,700 cps.

The NCO content was 22.0%, the uretdione dimer content was 1% or less, and the isocyanurate trimer content was 55%. In addition, the free HMD I monomer content is 0.1
%Met.

In a mixture of 50 g of the obtained product, 24.4 g of cellosolve acetate, and 24.4 g of xylene, 23.2 g of methyl ethyl ketoxime was added and reacted in the same manner as in Example [-1].

Appearance, solid content, and
Table 1 shows the measurement results of the content of viscosity-blocked isocyanate groups in 25"C.

Comparative Example [-2] 880 g of HMDI and 9 g of water were reacted at 160° C. for 1 hour using 300 g of methyl cellosolve acetate as a solvent, and then purified in the same manner as in Example 1-1 using a thin film evaporation can.

The resulting billet type polyisocyanate had a viscosity of 2,000 cps at 25°C and an NCO content of 23
．． 5%, and the amount of free HMD I was 0.2%.

In a mixture of 50 g of the obtained product, 24.9 g of cellosolve acetate, and 24.9 g of xylene, 24.8 g of methyl ethyl ketoxime was added and reacted in the same manner as in Example 1-1.

Appearance, solid content, and
Table 1 shows the measurement results of the viscosity at 25°C and the content of blocked isocyanate groups.

Examples r-3 to 10 Isocyanurate type polyisocyanate with isocyanate content of 123.1% by weight and solid content of 100% obtained from HMD I [manufactured by Asahi Kasei Kogyo ■, trade name: Duranate TPA-1oo] Blocking agents shown in 1 were mixed and reacted to obtain a blocked polyisocyanate.

Appearance, solid content, and
Table 1 shows the measurement results of viscosity and blocked isocyanate at 25°C.

(Left below) (Compatibility with resin) The block polyisocyanates obtained in Examples 1-1 and 1-2 and Comparative Examples 1-1 and 1-2 were mixed with a fluorine-containing polyol for coatings (
Manufactured by Asahi Glass Co., Ltd., Lumiflon LF-100, LF60
1) were blended so that the ratio of blocked isocyanal equivalent to polyol hydroxyl equivalent was 1, and turbidity in the solution state was observed, and the results are summarized in Table 2.

Table 2 ○: Transparent Δ: Slight turbidity ×: White turbidity (thermal stability) Isocyanurate-type polyisocyanurate produced in Example 1-1 and its block polyisocyanate, produced in Comparative Example I-2 The thermal stability of the billet type polyisocyanate and its block polyisocyanate was measured by thermogravimetric analysis, and the results are shown in FIG. Example 1-1
The thermal stability of the isocyanurate type polyisocyanate is good, but in the blocked polyisocyanate of Comparative Example 1-2, not only the blocking agent dissociates but also the backbone polyisocyanate decomposes considerably.

Measuring device: Rigaku Denki 808SDI model Air flow rate: 0.2 L/min Temperature increase rate: 10°C/min Example 11-1 and Comparative Example H~1 Acrydike A-80 as a polyvalent hydroxyl compound
1 (Acrylic polyol resin manufactured by Dainippon Ink Co., Ltd.)
The blocked polyisocyanates obtained in Example 1-1 and Comparative Example 1-2 were blended so that the ratio of blocked isocyanate equivalent/polyol hydroxyl group equivalent was 1, and ethyl acetate was added as a thinner. /toluene/butyl acetate/xylene/cellosolve acetate (weight ratio 30/3
0/20/1515) and photo cup #
4 for 20 seconds to obtain a one-wave type polyurethane thermosetting coating composition of the present invention. This was coated in two coats with an air spray gun to a dry film thickness of 50 μm, and cured at 150°C for 30 minutes. Various tests shown in Table 3 were conducted and the results are summarized in the same table.

(Margin below) table Slightly cloudy According to 8741.

According to.

Conforms to K 54006.15.

1) ○: Good, △: 2) 60 degree gloss JIS Z 3) JIS K 5400 6.144) Goban test JIS ○ means no peeling.

5) Methyl ethyl ketone rubbing test, no change.

Example lll-1 (1) Preparation of thermosetting resin paint (melamine alkyd resin ○ means paint) (A-1) Commercially available alkyd resin (manufactured by Dainippon Ink & Chemicals Co., Ltd., trade name: Bencosol M 7600) 280 Commercially available butylated melamine resin (N, Y, = 60% by weight, manufactured by the same company, trade name: Superbencamine J 820-
60) 140 parts rutile titanium
250 parts xylene 330
A thermosetting resin paint was obtained from a total of 1000 parts.

(2) Polyisocyanate with isocyanate content of 23.1% by weight and solid content of 100% by weight obtained from 3-periphery HMD I of block polyisocyanate compound (B-1) [manufactured by Asahi Kasei Kogyo (l!0), Product name: Duranate TPA-100
'l and 2-heptanone oxime N COlo H ratio=
They were mixed at a ratio of 1/1.02 and reacted in methyl ethyl ketone to obtain a blocked polyisocyanate compound (B-1) with a solid content of 75% by weight.

(3) Preparation of composition and formation of coating film After adding and mixing 22.4 parts of the above blocked isocyanate compound to 1000 parts of the above thermosetting resin coating, pure thinner (ethyl acetate/toluene/acetic acid Butyl/
Xylene/cellosolve acetate = 20/30/30/151
5: weight ratio) for 15 seconds/F-C#4 and spray-painted it on a bonded steel plate (150x50x0.6T [1I11). After setting it at room temperature for about 20 minutes, it was placed in a hot air circulation dryer. Baking was performed at 150°C for 30 minutes.

As a result, a baked coating film with an average thickness of 31 μm was obtained.

Example lll-2 Example I [[[-1] Except that the amount of the blocked polyisocyanate compound (B-1) was changed to 89.6 parts, the same procedure as Example m-1 was carried out, except that the average film thickness was 30 μm. A baked coating film was obtained.

Example I-3 Baking with an average film thickness of 30μ was carried out in the same manner as in Example I11-1 except that the amount of the blocked polyisocyanate compound (B-1) in Example I11-1 was changed to 179.2 parts. A coating film was obtained.

Example II [-4 (1) Preparation of thermosetting resin paint (melamine acrylic resin paint) (A-2) Commercially available thermosetting acrylic resin (manufactured by Dainippon Ink and Chemicals Co., Ltd., trade name: Beccosol M7600)
320 urban version butylated melamine resin (N, V, = 60%, manufactured by the same company, product name: Super Bencamine J 820-60)
160 parts rutile type titanium white
A thermosetting resin paint was obtained from 220 parts and 1000 parts in total.

(2) Preparation of blocked polyisocyanate compound (B-2) The duranate used in Example 1-1 above and methylpropyl ketoxime were mixed at a N0O10H ratio = 171.02, and reacted in methyl ethyl ketone, solid content 75. A block polyisocyanate compound (B-2) of % by weight was obtained.

(3) Preparation of I acid and formation of coating film All procedures were carried out in the same manner as in Example 1-1, except that 1000 parts of the above thermosetting resin paint and 230.4 parts of the above blocked polyisocyanate compound were used. A baked coating film with an average thickness of 32 μm was obtained.

Example I[1-5] The block polyisocyanate compound (B-1) 22. used in Example 1-1 was added to the butylated melamine resin, which is a component of the thermosetting resin coating in Example ll-1.
A baked coating film having an average thickness of 31 μm was obtained in the same manner as in Example 111-1 except that 4 parts of the above solution were added and mixed.

Example 111-6 Duranate and ethyl acetoacetate used in Example 1-1 were added to the butylated melamine resin, which is a component of the thermosetting resin paint in Example 111-1, at a N COlo H ratio of -
171,02 and reacted in ethyl acetate, 51.2 parts of a blocked polyisocyanate compound (B-3) with a solid content of 75% by weight was added and mixed in advance. Same as Example l11-1, average coating film 31μ
A baked coating film was obtained.

Example 111-7 Example I [Other than adding and mixing 51.2 parts of the blocked polyisocyanate compound (B-1) in r-5,
A baked coating film with an average coating thickness of 32 μm was obtained in the same manner as in Example 111-5.

Example ■-8 Instead of the blocked polyisocyanate compound (B-1) in Example 11-7, duranate and propylene glycol 7-methyl ether (C11:10 CH□Cll011) used in Example 11-1 were replaced with NCO /
"C) Except for using 51.2 parts of a blocked polyisocyanate compound (B-4) with a solid content of 70% by weight obtained by mixing at a 13OH ratio = 1 / 1.02 and reacting in cellosolve acetate, Average coating film 3 was prepared in the same manner as in Example 111-7.
A baked coating film of 0μ was obtained.

Comparative Example lll-1 Thermosetting resin paint (A-2) in Example I [[-4
A baked coating film having an average film thickness of 30 μm was obtained in exactly the same manner as in Example [-1] using only the following.

Comparative Example 111-2 Thermosetting resin paint (A-2) in Example 111-4
1000 parts and 2.56 parts of the blocked isocyanate compound (B-2) in Example lff-4,
A baked coating film having an average thickness of 32 μm was obtained in exactly the same manner as in Example 111-1.

Comparative Example I[[-3 Thermosetting resin paint (A-2) in Example l11-4
A baked coating film with an average thickness of 31 μm was obtained in the same manner as in Example I [[-1] except that 384 parts of the blocked isocyanate compound (B-2) in Example I [[-4] was used. Ta.

Comparative Example 11-4 Instead of the blocked polyisocyanate compound (B-1) in Example 11-1, duranate and acetoxime used in Example 1-1 were used at an NGO/OH ratio of −1/1.0.
Example I-1 except that 34.4 parts of a blocked polyisocyanate compound (B-5) with a solid content of 75% by weight obtained by mixing in Example I-2 and reacting in methyl ethyl ketone was used.
A baked coating film with an average thickness of 30 μm was obtained in the same manner as above.

Comparative Example II[-5 In place of the blocked polyisocyanate compound (B-1) in Example ■-1, duranate and isobutylhexyl ketoxime used in Example I[I-1 were replaced with N COI
Example 4 except that 384 parts of a blocked polyisocyanate compound (B-6) with a solid content of 75% by weight obtained by mixing at a H ratio of 1/1.02 and reacting in methyl ethyl ketone was used. In the same manner, a baked coating film with an average thickness of 32 μm was obtained.

Comparative Example 111-6 Instead of the blocked polyisocyanate compound (B-1) in Example 111-1, duranate and ε-caprolactum used in Example 111-4 were used at an NC010H ratio of -1
Example I[1-] except that 344 parts of a blocked polyisocyanate compound (B-7) with a solid content of 75% by weight obtained by mixing the mixture at 1.02% and reacting it in ethyl acetate was used.
A baked coating film having an average thickness of 30 μm was obtained in the same manner as in Example 1.

Comparative Example I[[-7 In place of the blocked polyisocyanate compound (B-1) in Example 11[-1, duranate and phenol used in Example I[-1 were used at a N0C1011 ratio of 1/1.
A blocked polyisocyanate compound (B-8) with a solid content of 75% by weight obtained by mixing in
) A baked coating film having an average coating thickness of 32 μm was obtained in the same manner as in Example II [-4, except that 384 parts of the coating film was used.

As mentioned above, pencil hardness and bending tests were conducted according to JIS K 5400 for the baked coating films obtained in Examples I [[-1 to 8 and Comparative Examples 1-1 to 7]. The results are shown in Table 4.

(Margin below)

[Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum after removing the solvent from the blocked polyisocyanate obtained in Example 1-1. FIG. 2 is a curve of heating weight residual ratio and temperature calculated from thermogravimetric analysis of the polyisocyanates produced in Example 1-1 and Comparative Example I-2 and the desolvent-free block polyisocyanates. . ■Polyisocyanate of Example 1-1 ■Blocked polyisocyanate of Example 1-1 ■Polyisocyanate of Comparative Example 1-2

Claims (3)

[Claims] (1) A polyisocyanate obtained by cyclic trimerization of hexamethylene diisocyanate, which has a viscosity of 1,600 cps or less at 25°C in a state substantially free of hexamethylene diisocyanate monomer and solvent, and isocyanurate cyclic trimer content is 6
A block polyisocyanate whose isocyanurate groups are blocked by a reaction product of an isocyanurate-type polyisocyanate with a uretdione dimer content of 0% or more and 10% or less and an active hydrogen-containing compound. (2) A polyisocyanate obtained by cyclic trimerization of hexamethylene diisocyanate, which has a viscosity of 1,600 cps at 25°C in a state substantially free of hexamethylene diisocyanate monomer and solvent.
A reaction product of an isocyanurate-type polyisocyanate with an active hydrogen-containing compound and an isocyanurate cyclic trimer content of 60% or more and a uretdione dimer content of 10% or less and an isocyanate group. A one-component polyurethane thermosetting coating composition comprising a blocked blocked polyisocyanate and a polyhydric hydroxyl compound. (3) A polyisocyanate obtained by cyclic trimerization of hexamethylene diisocyanate, which has a viscosity of 1,600 cps at 25°C in a state substantially free of hexamethylene diisocyanate monomer and solvent.
A reaction product of an isocyanurate-type polyisocyanate with an active hydrogen-containing compound and an isocyanurate cyclic trimer content of 60% or more and a uretdione dimer content of 10% or less and an isocyanate group. Blocked block polyisocyanate (a) and general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, at least one of R_1 to R_6 is an alkyl etherified methylol group, and the others are hydrogen and/or methylol The compound (b) represented by (representing a group), and these compounds (a) and (b)
A flexible one-component polyurethane consisting of a polyhydric hydroxy compound (c) as a main component with which the compound (a) reacts with the compound (b) in a weight ratio of 0.2 to 2. Thermosetting coating composition