JPS5830904B2 - 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 consisting of a polyester resin containing two or more hydroxyl groups and a polyisocyanate blocked with a phenol such as phenol or cresol or an alcohol such as ethyl alcohol or cellosolve can be used as a powder coating. .

However, the disadvantage of these compositions is that the baking temperature is 180-2.
The temperature is as high as 20℃, and phenomena such as bubbles or discoloration may occur in the coating, which may render the coating worthless. It is also known that powder compositions with polyisocyanates blocked with ε-caprolactam can be used as powder coatings.

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 discovered that aromatic diisocyanates were blocked with a specific blocking agent. We unexpectedly discovered that a powder coating composition using polyisocyanate as a polyisocyanate component can be baked in a relatively short time even at temperatures as low as 160°C or less, and based on this new knowledge, we Based on this, the present invention was completed.

That is, the present invention is
In formula 2C, OH R1 is hydrogen, lower alkyl group, aryl group, R300C
! -CH2-1R,00C-OH- or OH R500C-.

R2, R3, R, and R5 represent an alkyl group having 1 to 8 carbon atoms.

This is a powder coating composition comprising an aromatic diisocyanate blocked with an α-oxycarboxylic acid ester represented by the following formula or an adduct thereof, and (2) a polyol resin having a melting point of 40° C. or higher.

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

Moreover, it is possible to perform baking coating in a short time at a low temperature of about 160° C. or less, and the resulting coating film does not cause any fading or foaming, and has good physical properties.

Such excellent effects can be attributed to methanol, ethanol, and
This cannot be obtained when alcohols such as butanol and ethyl cellosolve are used as blocking agents.

The α-oxycarboxylic acid esters used in the present invention generally have the formula R1-CHC00Rz (formula H, where R1 is hydrogen, lower alkyl group, aryl group, aralkyl group, R300C-CH2-1R,0OC-OH-O
Indicates H or R500C-.

R2 and R3, R4. R5 represents an alkyl group having 1-8 carbon atoms.

) is a compound represented by

Examples of the lower alkyl group represented by R1 include linear and branched alkyl groups having about 1 to 4 carbon atoms.

Examples of the aryl group represented by R1 include phenyl, tolyl, and naphthyl groups.

The alkyl groups of R2, R3, R4, and R may be either linear or branched.

Specific examples of α-oxycarboxylic acid esters represented by the above general formula include glycolic acid esters such as methyl glycolate, ethyl glycolate, propyl glycolate, amyl glycolate, methyl α-hydroxybutyrate, α- α-hydroxybutyrate esters such as ethyl hydroxybutyrate and amyl α-hydroxybutyrate;
Methyl lactate, ethyl lactate, propyl lactate, butyl lactate,
Lactic acid esters such as amyl lactate and octyl lactate, tartronic acid diesters such as dimethyl tartronate, diethyl tartronate, and dipropyl tartronate, malic acid diesters such as dimethyl malate and diethyl malate, dimethyl tartrate, diethyl tartrate, and tartaric acid. Examples include diesters of tartrate such as dibutyl and dioctyl tartrate, and mandelate esters such as methyl mandelate and ethylnato mandelate.

Among these α-oxycarboxylic acid esters, those having a boiling point of about 120 to 350°C are particularly preferable, and specifically lactic acid esters such as methyl lactate, ethyl lactate, and butyl lactate are preferable.

Aromatic diisocyanates or adducts thereof used in the present invention include, for example, tolylene diisocyanate, diphenylmethane diisocyanate, natutaleno diisocyanate, diphenyl diisocyanate, dimethyldiphenyl diisocyanate, dimethyldiphenylmethane diisocyanate, dimethoxydiphenyl diisocyanate, phenylene diisocyanate, and triphenyl diisocyanate. Methanetriincyanate and any monomer or excess of this diisocyanate, such as ethylene glycol, furopylene gellicol, cyfropylene glycol, butylene glycol, trimethylolpropane, hexanetriol, chrycerin, sorbitol, penquerythritol, castor oil, Ethylenediamine, hexamethylenediamine, ethanolamine, jetanolamine,
Triethanolamine, water, ammonia, urea f, f
Polyisocyanates obtained by reacting with low-molecular active hydrogen compounds such as polyols, or high-molecular active hydrogen compounds such as various polyether polyols, polyester polyols, and acrylic polyols, or allophanates and biuret compounds of these, or condensed amines of aniline and formalin. and polyinsyanate obtained by phosgenating.

The above aromatic diisocyanate or its adduct and α-
The reaction with the oxycarboxylic acid ester is carried out by a known method in a solvent that does not contain 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. Then, 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, a coating composition is prepared by mixing this block polyisocyanate with a polyol resin having a melting point of 40°C or higher, and the mixing ratio of the two is determined by the equivalent ratio of recycled incyanate groups and hydroxyl groups in the block polyisocyanate. 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 fluorocarbon. Pyrene gelicol, dipropylene glycol, ■, 3-butanediol, 1,4-butanediol, ■, 5-bentanediol, neopentyl glycol, hexamethylene glycol, decamethylene glycol, hydroquinone bis(hydroxyethyl ether), hydrogenated Bisphenol A1 trimethylolethane, trimethylolpropane, hexanetriol,
It can be obtained by condensing polyols such as glycerin, pentaerythritol, tris(hydroxyethyl)in cyanurate, and cyclohexane dimetatool under conditions with an excess of hydroxyl groups by a conventional method.

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

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

The polyester resin obtained by combining the above raw materials has a molecular weight of 500 to 4,000, preferably i, ooo
~3,000, hydroxyl value 10-300, preferably 20
-200°C, acid value 1-30, and melting point 60-120°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, modified 2-hydroxypropyl methacrylate, allyl alcohol,
Keihi alcohol, crotonyl alcohol, or
For example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, etc. and ethylene glycol, ethylene oxide, propylene gellicol, propylene oxide, butylene glycol, ■, 4-cyclohexyl dimetatool , phenyl glycidyl ether, glycidyl decanoate) ff, etc., and (2) for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-acrylate. Acrylic acid esters such as -butyl, tert-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl meccrylate, tert- methacrylate Butyl, methacrylic acid 2
- Methacrylic acid esters such as ethylhexyl, styrenic monomers such as styrene, vinyltoluene, α-methylstyrene; vinyl acetate, vinyl fropionate,
Acrylonidonyl, vinyl stearate, acrylic acetate, diallyl adipate, dimethyl itaconate, diethyl maleate, vinyl chloride, vinylidene chloride, ethylene, glycidyl methacrylate, N-methylolacrylamide, N-butoxymethylacrylamide, acrylamide, diacetone acrylamide, etc. It is obtained by copolymerizing with a copolymerizable α,β-ethylenically unsaturated monomer, and its hydroxyl value is about 10 to 300, preferably about 20 to 200.

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 preferable, while the epoxy equivalent is 42
5 to 10,000, particularly preferably 425 to 4,000.

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 paraformaldehyde, α-polyoxymethylene, eupolyoxymethylene, and trioxane, polytetramethylene ether glycol, and polyhexamethylene ether glycol, and the molecular weight thereof is approximately 500 to 4. ,000
, a hydroxyl value of about 20 to 200, and a melting point of about 60 to 120°C are preferably used.

Examples of polyether ester resins include (1) polyether polyols having 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, (3) obtained by reacting with an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, phenyl glycidyl ether, allyl glycidyl ether, etc. by a known method. It is preferably used having a molecular weight of about 500 to 4,000, a hydroxyl value of about 20 to 200, and a melting point of about 60 to 1208C.

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, pigments, leveling agents, dissociation catalysts, stabilizers, etc. are mixed, and then this is made into a fine powder using a spray dryer. A method is adopted in which both components of the mold are heated and mixed at 80 to 140 DEG C. in a molten state, the pigment and the additives are kneaded therein, and the mixture is cooled to solidify and then pulverized.

The particle size of the powder is 5 to 500 microns, more preferably 1
0 to 300 microns In the practice of the present invention, it is desirable to use a block polyisocyanate dissociation catalyst for the purpose of lowering the baking temperature.

Further, it is desirable to use a stabilizer for the purpose of improving heat resistance and weather resistance.

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

The amount of catalyst added is from 0.01 to 51 to 5 parts by weight of the coating composition.

As the stabilizer, any known stabilizer such as phenol type, phosphorus type, etc. can be used.
represents an integer of 1 to 5] is desirable.

The amount of stabilizer added is from 0.01 to 51 to 5 parts by weight of the coating composition.

Examples of the phosphorus compounds include tetraphenyldipropylene glycol diphosphite, tetraphenylbutylene glycol diphosphite, and tetraphenylbutylene glycol diphosphite.

The resin composition obtained in this way is useful as a powder coating, and when powder coating is applied to the object to be coated by a method such as fluid coating or electrostatic coating, it is coated with a coating material of about 150 to 17
If baking is performed at 0°C, crosslinking will occur due to the reaction between the regenerated incyanate groups and hydroxyl groups, resulting in a tough film.

The resulting coating film shows no so-called discoloration or thermal deterioration, and has good physical properties.

EXAMPLES The present invention will be specifically explained below using Examples.

In the examples, parts and excellent indicate parts by weight, respectively. Example 1 388 parts of dimethyl terephthalate, 93 parts of ethylene glycol, 135 parts of 1,3-butylene glycol, and 36 parts of trimethylolpropane were heated at 180°C to 220°C. 4 while continuously removing the generated methanol from the system.
After reacting for an hour, 148 parts of phthalic anhydride was added and the reaction was further carried out at 240°C for 4 hours while separating and removing by-product water to obtain a polyester resin having an acid value of 8.0, a hydroxyl value of 77, and a melting point of 72°C.

On the other hand, a 75% ethyl acetate solution of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane
Add 124 parts of ethyl lactate to 92 parts and heat at 75 to 80°C for 4 hours.
After reacting for a period of time, the free NCO groups became less than 0.1%.

Then, ethyl acetate was completely removed by heating at 120°C or lower under reduced pressure to obtain a blocked isocyanate with a melting point of 100-110°C.

343 parts of this blocked isocyanate, 728 parts of the above-mentioned polyester resin (NCO10H ratio is 1.0), 540 parts of titanium oxide (Tie Bake R-930, manufactured by Ishiya Sangyo ■), 5 parts of Modaflow (leveling agent, manufactured by Monsando),
3 parts of 1.1,3.3-tetrabutyl-1,3-diacetoxydistanoxane and 2 parts of tetraphenyldipropylene glycol diphosphite were premixed for 5 minutes using a Henschel mixer.

The mixture was melt-blended in an extruder set at 100 to 110°C, cooled, and then ground to a particle size of 100μ or less in an atomizer.
Electrostatically coated to a film thickness of 100μ and heated at 160℃ for 30 minutes.
After baking, a solid, glossy white coating was obtained.

The coating performance is shown in Table 1. Example 2 174 parts of tolylene diisocyanate, 31 parts of trimethylolpropane, 14 parts of 1,3-butylene glycol, 174 parts of methyl mandelate, and 140 parts of ethyl acetate were added to Example 1.
The reaction was carried out in the same manner as above to obtain floc incyanate having a melting point of 90 to 100°C.

393 parts of this block incyanate, 730 parts of the polyester resin of Example 1 (NOO10H ratio is 1.0), titanium oxide (Tybake R, -930, manufactured by Ishiya Sangyo ■), 5
65 copies, Modaflow 5.5 copies, ■.

1.3.3.5 parts of 3-tetrabutyl-1,3-diacetoxydistanoxane and 2 parts of tetraphenyldipropylene glycol diphosphite were melt-mixed and powdered in the same manner as in Example 1 to form a mild steel plate. 80~100μ at 60KV
The film was electrostatically coated to a film thickness of , and baked at 160°C for 30 minutes to obtain a robust, glossy white film.

The coating performance is shown in Table 1.

Example 3 292 parts of the adduct of tolylene diisocyanate and trimethylolpropane used in Example 1, 190 parts of ethyl mandelate, 10.1 parts of dibutyltin dilauret, and 60 parts of butyl acetate were reacted in the same manner as in Example 1. Melting point: 95~
A blocked incyanate at 105°C was obtained.

410 parts of this block incyanate, epoxy resin (
Product name: Epicoat 1004, manufactured by Shell Chemical Co., epoxy equivalent: approximately 1.000, melting point: 95-104°G) 320
(NOO10H ratio is 1.0), 365 parts of titanium oxide,
4 parts of Modaflow, 2 parts of 1,1,3.3-tetrabutyl-1°3-diacetoxydistanoxane, and 1.4 parts of tetraphenylbutylene glycol diphosphite were melt-mixed and powdered in the same manner as in Example 1. 60KV on mild steel plate
Electrostatically coated to a film thickness of 80-100μ,
After baking at 0° C. for 30 minutes, a robust, glossy white coating was obtained.

The coating performance is shown in Table 1.

Example 4 125 parts of diphenylmethane diisocyanate, 104 parts of ethyl glycolate, 0.1 part of dibutyltin dilaurate, and 40 parts of ethyl acetate were reacted in the same manner as in Example 1,
A block polyinsyanate with a melting point of 80-90°C was obtained.

660 parts of an acrylic polyol with a melting point of 77-84°C and a hydroxyl value of 85 obtained by copolymerizing 50 parts of styrene, 30 parts of n-butyl acrylate, and 20 parts of 2-hydroxyethyl methacrylate by a conventional method, and 229 parts of the above blocked isocyanate. (NOOLo) (ratio is 1.0), 450 parts of titanium oxide, 4 parts of Modaflow, 1,1,3°3-tetrabutyl-1,3-diacetoxydistanoxane 2.5
1 part and 2 parts of tetraphenyldipropylene glycol diphosphite were melt-mixed, powdered in the same manner as in Example 1, electrostatically coated on a mild steel plate at 60 KV to a film thickness of 80 to 100 μ, and heated at 160°C. After baking for 30 minutes, a solid, glossy white coating was obtained.

The coating performance is shown in Table 1. Example 5 210 parts of naphthalene diisocyanate, 31 parts of trimethylolpropane, 14 parts of 1,3-butylene glycol, and 190 parts of diethyl malate were reacted in the same manner as in Example 1 to produce a blocked incyanate with a melting point of 75 to 85°C. Obtained.

445 parts of this blocked isocyanate, 730 parts of the polyester resin of Example 1 (NC!010H ratio is 1.0),
Titanium oxide 590 parts, Modaflow 5.5 parts, 1,1,3
．． 73.5 parts of 3-tetrabutyl-1,3-diacetoxydistanoxa and 2 parts of tetraphenyldiethylene glycol diphosphite were melt-mixed, powdered in the same manner as in Example 1, and powdered on a mild steel plate at 60 KV to a thickness of 80 to 100 μm. It was electrostatically coated to a film thickness of , and baked at 160°C for 30 minutes to obtain a robust and glossy white coating.

The coating performance is shown in Table 1. Example 6 132 parts of dimethyldiphenyl diisocyanate and 155 parts of diethyl tartrate were reacted in the same manner as in Example 1,
A blocked isocyanate having a melting point of 100 to 110°C was obtained.

428 parts of this block in shear hole, 730 parts of the polyester resin of Example 1 (N0010H ratio is 1.0), 505 parts of titanium oxide, 5 parts of Modaflow, 1,1,3.3-
Tetrabutyl-1,3-diacetoxydistanoxane 3
and 2 parts of tetraphenylschiff pyrene glycol diphosphite were melt-mixed, 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 100μ. After baking at 160° C. for 30 minutes, a robust and glossy white coating was obtained.

The coating performance is shown in Table 1.

Example 7 292 parts of the adduct of tolylene diisocyanate and trimethylolpropane used in Example 1, 176 parts of diethyl tartronate, 0.1 part of dibutyltin dilaurate, and 60 parts of ethyl acetate were reacted in the same manner as in Example 1. melting point 9
A blocked isocyanate having a temperature of 0 to 100°C was obtained.

395 parts of this blocked isocyanate, 660 parts of the acrylic polyol of Example 4 (NCo10H ratio is 1.0),
530 parts of titanium oxide, 4 parts of Modaflow, 1, 1, 3.3
-Tetrabutyl-1,3-diacetoxydistanoxane (3 parts) and tetraphenyldipropylene glycol diphosphite (2 parts) were melt-mixed and powdered in the same manner as in Example 1. Electrostatic coating was applied to the desired film thickness, and baking was performed at 160°C for 30 minutes to obtain a robust and glossy white coating.

The coating performance is shown in Table 1. Example 8 174 parts of tolylene diisocyanate, 1 part of diethyl tartrate
After first reacting 3 parts of ethyl lactate, 120 parts of ethyl lactate was reacted to obtain a blocked isocyanate having a melting point of 70 to 80°C.

200 parts of this blocked isocyanate, 728 parts of the polyester resin of Example 1 (NCo10H ratio is 1.0), 465 parts of titanium oxide, 4 parts of Modaflow, 2.5 parts of dibutyltin dilaurate, and 2 parts of tetraphenylbutylene glycol diphosphite. Melt and mix, powder by the same method as in Example 1, electrostatically coated on a mild steel plate at 60KV to a film thickness of 80-100μ, and baked at 160℃ for 30 minutes to form a solid and glossy white coating. A membrane was obtained.

The coating performance is shown in Table 1. Comparative Example 1 292 parts of a 75% ethyl acetate solution of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane was reacted with 46 parts of ethanol in the same manner as in Example 1 to produce a blocked isocyanate with a melting point of 90 to 100°C. I got it.

265 parts of this flocked isocyanate, 730 parts of the polyester resin of Example 1 (NCo10H ratio is 1.0), 500 parts of titanium oxide, 5 parts of Modaflow, 1,1,3.3tetrabutyl-1,3-diacetoxydistanoxane 3 parts of tetraphenyl dipropylene glycol diphosphite and 2 parts of tetraphenyl dipropylene glycol diphosphite were melt-mixed and powdered in the same manner as in Example 1.
A white coating film was obtained by electrostatically coating a mild steel plate at 60 KV to a film thickness of 80 to 100 μm and baking at 160° C. for 30 minutes.

The coating performance is shown in Table 1.

Example 9 1550 parts of dimethyl terephthalate, 560 parts of polypropylene glycol with a molecular weight of 560, 680 parts of hydrogenated bisphenol Al, and 134 parts of trimethylolpropane were mixed into 18
Heating at 0 to 220°C and reacting for 8 hours while continuously removing generated methanol from the system, acid value of 1 or less,
A polyetherester resin having a hydroxyl value of 50 and a melting point of 70°C was obtained.

On the other hand, a 75% ethyl acetate solution of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane
Add 132 parts of ethyl α-hydroxybutyrate to 92 parts and add 75 parts.
After 6 hours of reaction at ~80°C, free NCO groups were reduced to 0.
It became less than 1%.

Ethyl acetate was then completely removed by heating at 120 to 130°C under reduced pressure to obtain a blocked isocyanate with a melting point of 100°C.

350 parts of this block incyanate, 1100 parts of the above polyether polyester resin (NC!010H ratio is 1.0), 600 parts of titanium oxide, 6 parts of Modaflow, 1,
3 parts of 1,3.3-tetrabutyl 1,3-diacetoxydiscutuxane and 1.5 parts of tetraphenylbutylene glycol diphosphite were melt-mixed, powdered in the same manner as in Example 1, and made into a mild steel plate. Electrostatic coating was applied at 60 KV to a film thickness of 80 to 100 μm, and baking was performed at 160° C. for 30 minutes to obtain a robust and glossy white coating.

Gloss (60° specular reflection) 95% hardness (pencil) H Flex test Rice 10M, φ Passed Erichsen test 871gl1 Solvent resistance Rice (ethyl acetate) Passed LIIS K-5400
It was carried out according to.

Claims (1)

[Claims] 1(1) General formula Rr (EH000R2 (wherein, R8
(ROH is hydrogen, lower alkyl group, aryl group, R300C-C
Indicates H2-1R4000-CH- or R,000-OH. R2s R3s R4 and R6 represent an alkyl group having 1 to 8 carbon atoms. A powder coating composition comprising an aromatic diincyanate blocked with an α-oxycarboxylic acid ester represented by the following formula or an adduct thereof, and (2) a polyol resin having a melting point of 40°C or higher.