JPS5830348B2 - Fuck you - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyurethane coating composition suitable for powder coating.

More specifically, the present invention relates to a polyurethane powder coating composition that has a lower baking temperature and superior coating performance than conventional polyurethane powder coating compositions.

It is known that a powder composition comprising a polyester resin containing two or more hydroxyl groups and a polyisocyanate blocked with phenol or cresol can be used as a powder coating.

However, the disadvantage of these compositions is that the baking temperature
The temperature is as high as 220°C, and phenomena such as bubble formation or discoloration are observed in the coating, which causes a decrease in the value of the coating.

It is also known that a powder composition of a polyester resin containing two or more hydroxyl groups and having a melting point of 40 DEG C. or higher and a polyisocyanate blocked with ε-prolactam can be used as a powder coating.

The disadvantage of this composition is that the baking temperature is 200-220℃.
Moreover, the performance of the resulting coating film is poor.

In view of these circumstances, the present inventors conducted research and development on a powder coating composition that has a low baking temperature (and excellent coating performance), and found that it is possible to develop a powder coating composition that is blocked with a specific blocking agent as a polyisocyanate component. The inventors have discovered that a powder coating composition that completely satisfies the above objectives can be obtained by using polyisocyanate, and based on this new knowledge, the present invention has been completed.

That is, the present invention is directed to (1) the general formula [wherein R1 represents hydrogen, an alkyl group or a cycloalkyl group, and R2 and R3 represent an alkyl group or a cycloalkyl group].

] or [wherein 4 is an esterified carboxyl group (excluding an alkyl esterified carboxyl group having 10 or less carbon atoms) or a hydroxyl group acylated by a lower aliphatic acyl] blocked with a phenol. Polyisocyanate and (2) melting point 40
It is a powdery coating composition containing a polyol resin having a temperature of at least ℃.

The composition of the present invention does not undergo gelation during storage,
It is extremely stable.

Moreover, it is possible to bake paint in a short time at a low temperature of approximately 140℃ or less, and the resulting coating film does not cause any fading or foaming, and has good physical performance and weather resistance, making it suitable as a paint for electrical products and road products. It is extremely useful as a

The polyisocyanate blocking agent used in the present invention generally has the formula (wherein R1 represents hydrogen, an alkyl group or a cycloalkyl group, and R2 and R3 represent an alkyl group or a cycloalkyl group).

) or [wherein R4 is an esterified carboxyl group (excluding an alkyl esterified carboxyl group having 10 or less carbon atoms) or a hydroxyl group acylated with a lower aliphatic acyl].

The alkyl groups represented by R1, R2, and R3 may be either linear or branched alkyl groups having 1 to 8 carbon atoms.

Examples of the cycloalkyl group represented by R1, R2, and R3 include those having 3 to 7 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

The esterified carboxyl group represented by R4 generally refers to a straight-chain or branched alkyl group having 11 to 15 carbon atoms, an aryl group such as a naphthyl group, an aryl group such as a diphenylmethyl group, Indicates an aralkyl group such as a trityl group.

The hydroxyl group acylated by lower aliphatic acyl represented by R4 is generally represented by the formula -0R6, and R6 is a linear or branched alkyl group having 1 to 8 carbon atoms. , a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group (eg, phenyl, tolyl group, etc.).

It represents a hydrocarbon group such as an aralkyl group (eg, benzyl, phenethyl group, etc.), an allyl group, or a lower aliphatic acyl group (eg, formyl, acetyl, propionyl, butyryl, 2-methyl-2-butenoyl group, etc.).

Among the compounds represented by the above general formula, the boiling point is particularly about 1
A temperature of 20 to 350°C is preferred.

Specific examples of the compound represented by general formula (1) include thymol, 2.4-xylenol, 3.5-xylenol, 2.6-di-t-butylphenol, 2-methyl-
6-t-butylphenol, 4-methyl-2,6-di-t-amylphenol, 2,4,6-tri-t-butylphenol, 2,4-dioctylphenol, 3-methyl-4-cyclohexylphenol, 4-methyl -2・
Examples include 6-cyclohexylphenol.

Specific examples of the compound represented by the general formula (2) include phenyl D-hydroxybenzoate, benzyl salicylate, phenyl salicylate, and p-t-salicylate.
butylphenyl, p-octylphenyl salicylate,
Examples include resorcinol monoacetate.

Among these blocking agents, 2.6-di-t-butylphenol, benzyl salicylate, resorcinol monoacetate, and the like are particularly preferred.

The polyisocyanate used in the present invention may be aromatic, aliphatic, alicyclic, or araliphatic.

For example, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), ω・ω'-diisocyanate dimethylcyclohexane (H6MDI), dicyclohexylmethane diisocyanate (H12MDI)
, isophorone diisocyanate (IPDI), ω・J-
Diisocyanates such as dimethylbenzene (MDI), methylcyclohexylene diisocyanate, lysine diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, or an excess of these polyisocyanates, such as ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, trimethylolpropane, hexane triol, glycerin, sorbitol, pentaerythritol,
Low-molecular active hydrogen compounds such as castor oil, ethylenediamine, hexamethylenediamine, ethanolamine, jetanolamine, triethanolamine, water, ammonia, and urea, or high-molecular active hydrogen compounds such as various polyether polyols, polyester polyols, and acrylic polyols. Suitable are polyisocyanates obtained by reacting with compounds, or biuret-formed and allophanated-formed products thereof.

The reaction between the above-mentioned polyisocyanate and phenol is carried out by a known method in a solvent having no active hydrogen or without a solvent.

In the reaction, known catalysts such as tertiary amines and organic metals may be used.

If a solvent is used and it is necessary to remove it after the reaction is completed, it can be distilled off using a spray dryer, drum dryer, thin film evaporator, etc.

In this way, a solid block polyisocyanate is produced.

The melting point of this block polyisocyanate is about 40-20
0°C, preferably about 60-150°C.

In the present invention, this block polyisocyanate and a polyol resin having a melting point of 40° C. or higher are mixed to form a coating composition, and the mixing ratio of both is such that the equivalent ratio of recycled isocyanate groups to hydroxyl groups of the block polyisocyanate is 0.
It is adjusted to 5 to 2.0, preferably 0.6 to 1.5.

Examples of the polyol resin having a melting point of 40° C. or higher used in the present invention include polyester resins, acrylic polyol resins, epoxy resins, polyether resins, polyether ester resins, and mixtures thereof.

Examples of polyester resins include polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, adipic acid, sepacic acid, azelaic acid, and trimethic acid, and polybasic acids such as ethylene glycol, diethylene glycol, and propylene glycol. , dipropylene glycol, 1,3-butanediol, 1,4-butanediol, ■,5-hentanediol, neopentyl glycol, hexamethylene glycol, decamethylene glycol, hydroquinone bis(hydroxyethyl ether), hydrogenated bisphenol A , trimethylolethane, trimethylolpropane, hexanetriol, glycerin, pentaerythritol, tris(hydroxyethyl)in cyanurate, cyclohexane dimetatool, etc. by a conventional method under conditions with an excess of hydroxyl groups.

In this case, it is also possible to use two or more acids or polyols in combination.

Also, castor oil, higher fatty acids, etc. may be used in combination to form a so-called oil-modified polyether polyol.

The polyester resin obtained by combining the above raw materials has a molecular weight of 500 to 4000, preferably 1000 to 3.
000, hydroxyl value 10-300, preferably 20-20
0. Acid value 1-30. Those having a melting point of 60 to 120°C are preferably used.

If the melting point is below 40°C, blocking of the composition will occur, and if it is above 120°C, gelation will occur easily during melt blending.

Examples of the acrylic polyol resin include (1) 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, cinnamon alcohol, chloryl alcohol, or, for example, acrylic acids, unsaturated carboxylic acids such as methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, and ethylene glycol, ethylene oxide, propylene glycol, propylene oxide, butylene glycol,
A hydroxyl group-containing monomer which is a reaction product of 1,4 cyclohexyl dimetatool, phenylcricidyl ether, glycidyl decanoate, etc. and (2) for example, methyl acrylate, ethyl acrylate, n-propyl acrylate,
Acrylic acid esters such as isopropyl acrylate, n-butyl acrylate, tert-methyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate,
Methacrylic acid esters such as ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-7thyl methacrylate, tert-butyl methacrylate, and 2-ethylhexyl methacrylate, styrene such as styrene, vinyltoluene, and α-methylstyrene. Other monomers: Vinyl acetate, vinyl propionate, acrylonitrile, vinyl stearate, acrylic acetate, diallyl adipate, dimethyl itaconate, diethyl maleate, vinyl chloride, vinylidene chloride, ethylene, glycidyl methacrylate, N-methylolacrylate ☆☆ Copolymerizable α such as ruamide, N-butoxymethylacrylamide, acrylamide, diaseptone acrylamide, etc.
- It is obtained by copolymerizing with a β-ethylenically unsaturated monomer, and has about 10 to 300 hydroxyl groups, preferably about 20 to 200 hydroxyl groups.

In addition, its melting point is about 40 to 150°C, preferably about 60°C.
~120°C.

The epoxy resin has at least two hydroxyl groups in one molecule, and is usually a condensed epoxy resin obtained by reacting bisphenol A and epichlorohydrin.

This epoxy resin has the following chemical structure.

Among the above epoxy resins, n is about 2 to 12, especially 2
~10 is preferred, while the epoxy equivalent is 425
-1oooo, particularly preferably 425-4000.

Further, its melting point is about 40 to 200°C, preferably about 60 to 200°C.
The temperature is 150°C.

Furthermore, in addition to the above-mentioned epoxy resins, for example, epoxy ester resins obtained by reacting soybean oil fatty acids and epoxy resins can also be used.

Examples of the polyether resin include polymers such as boraformaldehyde, α-polyoxymethylene, eupolyoxymethylene, and trioxane, or polytetramethylene ether glycol and polyhexamethylene ether glycol, which have a molecular weight of about 500 to 4,000. ,
Those having a hydroxyl value of about 20 to 200 and a melting point of about 60 to 120°C are preferably used.

As polyether ester resins, (1) for example,
Polyether polyol with a hydroxyl value of about 45 to 200, (
2) For example, phthalic anhydride, maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, 3,6-nindomethylenetetrahydrophthalic anhydride, 3,6-nindomethylenetetrachlorophthalic anhydride, tetrachlorophthalic anhydride , a dibasic acid anhydride such as tetrabromo-phthalic anhydride, and (3) an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, phenyl glycidyl ether, allyl glycidyl ether, etc. by a known method. The molecular weight is about 500 to 4000,
Those having a hydroxyl value of about 20 to 200 and a melting point of about 60 to 120°C are preferably used.

Any conventionally known method may be used to produce a composition suitable for powder coating from a blocked polyisocyanate and a polyol resin.

That is, the two components are dissolved and mixed in the presence of a solvent, and if necessary, a pigment, a leveling agent, a dissociation catalyst, etc. are mixed therein, and then this is made into a fine powder using a spray dryer. A method is adopted in which both components are heated and mixed at 80 to 140° C. in a molten state, raw materials and other additives are kneaded therein, cooled to solidify, and then finely pulverized.

The particle size of the powder is 5 to 500 microns, more preferably 1
It is 0 to 300 microns.

In practicing the present invention, it is desirable to use a block polyisocyanate dissociation catalyst for the purpose of lowering the baking temperature.

As the catalyst, any known catalyst such as amine type, metal type, etc. can be used.

The amount of catalyst added is preferably 0.01 to 5% by weight of the coating composition.

The resin composition thus obtained is useful as a powder coating, and for powder coating, it is applied to the object by a method such as flow coating or electrostatic coating, and then applied to the object at a coating temperature of about 120-14 mm.
It can be baked at an extremely low temperature of 0°C, and crosslinking occurs due to the reaction between the regenerated isocyanate groups and hydroxyl groups, resulting in a tough film.

The resulting coating film shows no so-called fading or thermal deterioration, has good physical performance, and retains good gloss and color tone over a long period of time.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Parts or % indicate parts by weight or % by weight, respectively.

Example 1 In a reaction vessel equipped with a stirrer, a thermometer, and a separator, 592 parts of phthalic anhydride, 212 parts of neopentyl glycol, and 723 parts of hydrogenated bisphenol A were charged and melted by heating.

After melting, the mixture was reacted for 8 hours while stirring at 180-200°C while continuously removing the water generated, resulting in a melting point of 75-200°C.
A polyester resin having an acid value of 5.5 and a hydroxyl value of 77.0 was obtained at 85°C.

On the other hand, 111 parts of inphorone diisocyanate, 18 parts of 2,6-diisopropylphenol, 0.
When 15 parts of ethyl acetate and 100 parts of ethyl acetate were reacted at 78 to 80°C for 8 hours, the free NCO group became 0.1% or less.

Ethyl acetate was then completely removed by heating at 120°C or lower under reduced pressure to obtain blocked incyanate with a melting point of 80 to 88°C.

298 parts of this blocked isocyanate, 729 parts of the above-mentioned polyester resin (NCOlOH ratio is 1.0), 500 parts of titanium oxide (Tiebake R-930, manufactured by Ishihara Sangyo ■), 5 parts of a leveling agent (Modaflow, manufactured by Monosand Co., Ltd.),
3.5 parts of 1,1,3,3-tetrabutyl-1,3-diacetoxydistanoxane were premixed for 5 minutes using a Henschel mixer.

The mixture was melt-blended using an extruder set at 100-110°C, and after cooling, an atomizer was used to melt and blend the mixture.
Grind to a particle size of 00μ or less and place it on a mild steel plate.
Electrostatically coated to a film thickness of 80 to 100μ with 130
After baking for 30 minutes at ℃, a solid and glossy white coating was obtained.

The coating performance is shown in Table 1.

Example 2 98 parts of H6XDI, 215 parts of phenyl salicylate, ■
・0.15 parts of 1,3,3-tetrabutyl-1,3-diacetoxydistanoxane in ethyl acetate at 78-80°C
After 10 hours of reaction, the free NCO groups became less than 10%.

Free diincyanate and ethyl acetate were then removed to obtain a blocked isocyanate with a melting point of 75-85°C.

It is obtained by copolymerizing 50 parts of styrene, 30 parts of n-butyl acrylate, and 20 parts of 2-hydroxyethyl methacrylate by a conventional method.

660 parts of an acrylic polyol resin with a melting point of 77 to 84°C, 313 parts of the above blocked isocyanate (NGOloH ratio is 1.0), 487 parts of titanium oxide, and 5 parts of Modaflow were powdered in the same manner as in Example 1, and a mild steel plate was heated at 60 KV. and 80
Electrostatic coating was applied to a film thickness of ~100 μm, and baking was performed at 140° C. for 20 minutes to obtain a robust and glossy white paint film.

The coating performance is shown in Table 1. Example 3 To 380 parts of a 75% ethyl acetate solution of an adduct of 3 moles of H, MDI and 1 mole of trimethylolpropane, 215 parts of phenyl salicylate and 1,1,3,3-tetrabutyl-1,3 were added.
- When 0.25 parts of diacetoxydistanoxane is reacted in ethyl acetate at 78-80°C for 10 hours, free NC
The O group content was 8% or less.

Subsequently, free diisocyanate and ethyl acetate were removed to obtain blocked incyanate having a melting point of 80 to 88°C.

500 parts of this block incyanate and epoxy resin (
Manufactured by Shell Chemical Company, epoxy equivalent approximately 1000) 320
parts (NCO10H ratio is 1.0), 410 parts of titanium oxide,
Powderize 4 parts of Modaflow in the same manner as in Example 1, electrostatically coat it on a mild steel plate with 60% ■ to a film thickness of 80~100μ, and bake at 130℃ for 30 minutes to make it solid and shiny. A white coating film was obtained.

The coating performance is shown in Table 1. Example 4 When 131 parts of H1□MDI, 160 parts of resorcinol monoacetate, and 0.15 parts of dibutyltin dilaure were reacted in ethyl acetate at 75-80°C for 15 hours, free NCO groups were reduced to 79J. .

Subsequently, free diincyanate and ethyl acetate were removed to obtain a blocked isocyanate having a melting point of 75 to 85°C.

290 parts of this blocked isocyanate, 729 parts of the polyester resin of Example 1 (NGOloH ratio is 1.0), 510 parts of titanium oxide, 5 parts of Modaflow, ■・1・3・3−
Tetrabutyl-1,3-diacetoxydistanoxane 3
．． 5 parts were powdered in the same manner as in Example 1, and 60 parts were powdered on a mild steel plate.
Electrostatically coated with KV to a film thickness of 80 to 100μ,
After baking at 130° C. for 30 minutes, a robust and glossy white coating was obtained.

The coating performance is shown in Table 1.

Example I of H6
75-8 parts, add 0.15 parts of dibutyltin dilauret)
After reacting at 0° C. for 8 hours, the free NCO groups became 0.1% or less.

Then, ethyl acetate was completely removed by heating at 120°C or lower under reduced pressure to obtain a flocked isocyanate with a melting point of 80 to 90°C.

380 parts of this floc incyanate, 729 parts of the polyester resin of Example 1 (NGO10H ratio 1.0), 550 parts of titanium oxide, 5.5 parts of Modaflow, 1.1.3.
3.5 parts of 3-tetrabutyl-1,3-di☆☆acetoxydistanoxane was powdered in the same manner as in Example 1, and electrostatically applied to a mild steel plate at 60°C to a film thickness of 80 to 100μ. A white coating film was obtained by painting and baking at 170°C for 30 minutes.

The coating performance is shown in Table 1.

Comparative Example 2 Cresol 11 was added to 380 parts of a 75% ethyl acetate solution of an adduct of 3 moles of H6MDI and 1 mole of trimethylolpropane.
0 parts, add 0.18 parts of dibutyltin dilaurate to 78~
When reacted at 80℃ for 6 hours, free NCO groups were reduced to 0.2%.
Became.

This ethyl acetate solution was concentrated to dryness at 85°C under a reduced pressure of 20 iiHg to obtain a blocked isocyanate with a melting point of 60 to 70°C.

400 parts of this block incyanate, 729 parts of the polyester resin of Example 1 (NGOloH ratio is 1.O), 540 parts of titanium oxide, 5.4 parts of Modaflow, ■・1・3・
3.5 parts of 3-tetrabutyl-1,3-diacetoxydistanoxane was powdered in the same manner as in Example 1, and electrostatically coated on a mild steel plate at 60 KV to a film thickness of 80 to 100 μm. A white coating film was obtained by baking at ℃ for 30 minutes.

The coating performance is shown in Table 1.

- 75% ethyl acetate solution of adduct of 1 mole of propane 3
To 20 parts, 275 parts of 4-methyl 2,6 dicyclohexylphenol was added and reacted at 75 to 80°C for 8 hours, resulting in a free NCO group content of 5% or less.

Subsequently, free incyanate and ethyl acetate were removed to obtain blocked incyanate with a melting point of 90°C.

520 parts of this blocked isocyanate), 730 parts of the polyester resin of Example 1 (NCO10H ratio is 1.0), 600 parts of titanium oxide, 6 parts of Modaflow, 1.1.3.3tetrabutyl-1.3-diacetoxydistano. 4 parts of xane was powdered in the same manner as in Example 1, and 8 parts of xane was powdered at 60 KV on a mild steel plate.
Electrostatically coated to a film thickness of 0-100μ and heated at 130℃
After baking for 30 minutes, a solid and glossy white coating was obtained.

The coating performance is shown in Table 2. Example 6 1,550 parts of dimethyl terephthalate, 560 parts of polypropylene glycol with a molecular weight of 560, and 1,920 parts of hydrogenated bisphenol A were kept at 180°C to ☆☆220°C and reacted for 8 hours while continuously removing the generated methanol, resulting in a melting point of 70°C. A polyetherester resin having a hydroxyl value of 32 was obtained.

On the other hand, when 280 parts of a 75% ethyl acetate solution of an adduct of 3 moles of hexamethylene diisocyanate and 1 mole of trimethylolpropane was reacted with 215 parts of phenyl p-hydroxybenzoate at 80°C for 10 hours, free NCO groups were reduced to 0.
．． It fell below 6%.

Ethyl acetate was extracted from this ethyl acetate solution at 90°C for 50 min.
Hg was distilled off under reduced pressure to obtain a blocked isocyanate with a melting point of 70°C.

Example 1 430 parts of this blocked isocyanate, 1750 parts of the above polyether ester resin, 700 parts of titanium oxide, 7 parts of Modaflow, and 5 parts of dibutyltin dilaurate were added.
Powder it in the same way as above, and put it on a mild steel plate at 60 to 80 to 10.
Electrostatic coating was applied to a film thickness of 0 μm, and baking at 130° C. for 30 minutes yielded a robust and glossy white coating.

The coating film performance is shown in Table 2.

Claims (1)

[Claims] R2 and R3 represent an alkyl group or a cycloalkyl group. ] or bohoxyl (however, the alkyl esterified carboxyl group having 10 or less carbon atoms is removed (.) or the hydroxyl group acylated with a lower aliphatic acyl)] and a polyisocyanate blocked with a phenol represented by (2) melting point A powder coating composition comprising a polyol resin having a temperature of 40°C or higher.