JPH07103347B2 - Paint composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coating composition. More specifically, it relates to a chipping resistant coating composition.

[Prior Art] Conventionally, there is a chipping-resistant coating composition comprising an alkylene oxide adduct of alkylene diamine and a blocked isocyanate urethane prepolymer (for example, JP-A-57-168957).

[Problems to be Solved by the Invention] However, when the above composition is coated and cured, blister, armpit,
There is a problem with the appearance of the coating such as pinholes.

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of extensive studies on a chipping-resistant coating composition having an excellent coating film appearance when the coating is cured. That is, the present invention contains a blocked NCO urethane prepolymer and an amine compound selected from the group consisting of (poly) alkylene polyamines, (poly) cycloalkylene polyamines and aromatic polyamines, and a ketimine from a ketone, and a solvent-type one-pack type A chipping-resistant coating composition characterized by being a heat-resistant and bake-curable type.

Examples of ketimines in the present invention include (poly) alkylene polyamines, (poly) cycloalkylene polyamines or ketimines from aromatic polyamines and aliphatic ketones.

Examples of the (poly) alkylene polyamine include ethylenediamine, diethylenetriamine, propylenediamine, and hexamethylenediamine. Examples of (poly) cycloalkylene polyamines are 1,8-p-methanediamine, isophoronediamine, diaminocyclohexane, 4,
4'-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane, 3-aminomethyl-3,3,5-trimethylcyclohexylamine and the like can be mentioned.

Examples of aromatic polyamines include xylylenediamine, diaminodiphenylmethane, and tolylenediamine.

Of these polyamines, aliphatic polyamines are preferable, and diethylenetriamine is particularly preferable.

Examples of the aliphatic ketone include acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, diisopropyl ketone, dibutyl ketone and diisobutyl ketone. Preferred is methyl isobutyl ketone.

The specific examples of ketimine are as follows.

(CH ₃ ) ₂ C = NC ₂ H ₄ NC (CH ₃ ) ₂ CH ₃ (C ₄ H ₉ ) C = NC ₂ H ₄ N = C (C ₄ H ₉ ) CH ₃ , CH ₃ (C ₄ H ₉ ) C = NC ₄ NH ₉ N = C (C ₄ H ₉ ) CH ₃ , CH ₃ (C ₄ H ₉ ) C = NC ₆ H ₁₂ NC (C ₄ H ₉ ) CH ₃ CH ₃ (C ₄ H ₉ ) _{C = N (Cyh) C 2} H 4 N = C (C 4 H 9) CH 3 CH 3 (C 4 H 9) C = N (4,4'-Dcyhm) N = C (C 4 H 9) CH _{3 CH 3 (C 4 H 9} ) C = N (3,3'-Dcyhm) N = C (C 4 H 9) CH 3 Note) (CyH) cyclohexylene group, (4,4'-Dcyhm)
Is a 4,4'-dicyclohexylmethane group, (3,3'-Dcyh
m) represents a 3,3'-dicyclohexylmethane group.

Among these, preferred ones are CH ₃ (C ₄ H ₉ ) C = NC ₄ NH ₉ NC (C ₄ H ₉ ) CH ₃ and CH ₃ (C ₄ H ₉ ) C = N (4,4′-Dcyhm) N = C (C ₄ H ₉ ) CH ₃
Is.

Ketimine can be produced by dehydration condensation of polyamine and ketone. The above condensation reaction is usually carried out while distilling water in the presence of a water absorbing agent. Specifically, polyamine and a stoichiometric excess of ketone are added, and an appropriate solvent (toluene,
(Xylene, etc.), and then dehydration condensation is performed under heating and reflux while separating water, and excess ketone and solvent may be taken out if necessary.

As a blocked NCO urethane prepolymer,
Examples thereof include a blocked product of an NCO urethane prepolymer formed from a high-molecular polyol and, if necessary, a low-molecular polyol having an average functional group of 2.01 or more and an organic polyisocyanate compound.

As a high-molecular polyol, the molecular weight per hydroxyl group is 200-2
500 high molecular weight polyols may be mentioned.

Examples of the polymer polyols include polyether polyols, polyester polyols, polymer polyols, polycarbonate polyols and mixtures of two or more thereof.

Examples of the polyether polyol include polytetramethylene glycol which can be obtained by ring-opening polymerization of tetrahydrofuran. Polytetramethylene glycol is described in JP-A-58-11518. Also, an alkylene oxide adduct of a low molecular weight polyol can be used. As the low-molecular polyol, a diol having a molecular weight per hydroxyl group of usually 30 to 200, preferably 30 to 100, such as ethylene glycol, propylene glycol, 1,4-butanediol and 1,6-hexanediol; a molecular weight of 30 to 150 per hydroxyl group. And preferably 40 to 100 low molecular weight triols such as glycerin, trimethylolpropane, and mixtures of two or more thereof. As the alkylene oxide, ethylene oxide, propylene oxide, 1,2-, 1,3- or 2,3-butylene oxide, tetrahydrofuran, styrene oxide,
Epichlorohydrin and two or more of these.

Examples of the polyester polyol include a polyester polyol obtained by polycondensing a dicarboxylic acid, its ester or halide, and a low molecular weight polyol. Examples of the dicarboxylic acid include aliphatic dicarboxylic acids (adipic acid, sebacic acid, maleic acid, dimer acid, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, etc.) and their anhydrides. Among the dicarboxylic acids, preferred are the aliphatic dicarboxylic acids, and particularly preferred is adipic acid.

Examples of the low molecular weight polyol include those described in the section of polyether polyol, and preferable ones are ethylene glycol and 1,4-butanediol. A polylactone polyol obtained by ring-opening polymerization of a lactone (eg, ε-caprolactone) in the presence of a low molecular weight polyol (such as ethylene glycol) can also be used.

As the polymer polyol, those described in JP-A-55-118948 can be used.

Examples of the polycarbonate polyol include those obtained from the low molecular weight polyol (dihydric alcohol) and carbonic acid diester (dimethyl carbonate, diethyl carbonate, etc.).

Among the polymeric polyols, preferred are polytetramethylene glycol and polyester polyols (especially polyethylene adipate diol and polycaprolactone polyol).

Examples of the low molecular weight polyol include those described in the section of polyether polyol, low molar addition products of alkylene oxides (low molecular weight ones), and mixtures of two or more kinds thereof. Of these, preferred are ethylene glycol and trimethylolpropane.

Examples of polyols having an average number of functional groups of 2.01 or more include (a) a polyol composed of a high molecular weight polyol having a molecular weight per hydroxyl group of 250 to 2500 and a low molecular weight polyol having a molecular weight per hydroxyl group of 30 to 150, and (b) per hydroxyl group. Examples thereof include a trifunctional high molecular weight polyol having a molecular weight of 200 to 1500 and a low molecular weight diol having a molecular weight of 30 to 200 per hydroxyl group.

In the present invention, as the organic polyisocyanate compound, aliphatic isocyanate (hexamethylene diisocyanate, lysine diisocyanate, etc.), alicyclic isosaanaate [hydrogenated diphenylmethane diisocyanate (hydrogen
MDZI), isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, etc.], aromatic diisocyanate [tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, xylylene diisocyanate, etc.] and these two types The above mixture may be mentioned. Among these, preferred are aromatic diisocyanates, and particularly preferred are TDI and MDI.

In NCO urethane prepolymer, NCO / OH equivalent ratio of organic polyisocyanate compound and polyol is usually 1.3-
It is 3.0, preferably 1.6 to 2.0.

The prepolymer can be obtained by a usual method. For example, the reaction temperature is usually 40 to 140 ° C, preferably 60 to 120 ° C.
Is. In carrying out the prepolymer formation reaction, known polymerization catalysts for promoting the reaction, for example, dibutyltin dilaurate, stannous octoate, organometallic compounds such as stannas octoate, triethylenediamine, triethylamine, 1,8-diazabicyclo [ It is also possible to use a tertiary amine compound such as 5,4,0] undecene-7.

The reaction is usually performed in the presence of a solvent. As the solvent, aromatic hydrocarbon (toluene, xylene, etc.), ester type (ethyl acetate, butyl acetate, etc.), ether type (dioxane, cellosolve acetate, etc.), ketone type (acetone, methyl ethyl ketone, etc.) and two or more of these A mixed solvent can be used.

The molecular weight of the obtained prepolymer is usually 1,000 to 7,000, preferably 1,500 to 5,000. When the molecular weight is less than 1,000, the resin is hard and brittle, and thus the physical properties of the coating film tend to deteriorate, and when it exceeds 7,000, the viscosity is high and the coating workability deteriorates.

The NCO% of this prepolymer is usually 2 to 12, preferably 3 to 10. When the NCO% is less than 2, the resin is soft and the physical properties of the coating film are deteriorated. When the NCO% is more than 12, the resin is hard and brittle and the physical properties of the coating film are deteriorated.

Examples of the blocking agent used for obtaining the blocked urethane prepolymer include oxime compounds [acetoxime, ketoxime such as methyl ethyl ketone oxime (MEK oxime), methyl isobutyl ketoxime (M
IBK oxime), etc.]; lactams (ε-caprolactam, etc.); active methylene compounds [malonic acid diester (diethyl malonate, etc.) acetyl ketone, acetoacetic acid ester (ethyl acetoacetate, etc.); phenols (phenol, m-cresol) Etc.); alcohols (methanol, ethanol, n-butanol, etc.); hydroxyl group-containing ethers (methyl cellosolve, butyl cellosolve, etc.); hydroxyl group-containing esters (ethyl lactate, amyl lactate, etc.); mercaptans (butyl mercaptan, hexyl mercaptan, etc.); Acid amide (acetanilide,
Acrylic amide, dimer acid amide, etc.); imidazoles (imidazole, 2-ethylimidazole, etc.); acid imides (succinimide, phthalimide, etc.), and mixtures of two or more thereof.

Of these, preferred are oxime compounds and lactams, and particularly preferred are MEK oxime and ε-caprolactam.

The blocking agent can be added and reacted at any stage of the above reaction to obtain the blocked urethane prepolymer (a). As a method of addition, it is possible to add at the end of a predetermined polymerization, or at the beginning of the polymerization, or to add a part at the beginning of the polymerization and to add the balance at the end of the polymerization. The preferred method is to add at the end of the polymerization. The amount added is NCO when added at the end of polymerization.
It is usually 1 equivalent or more and less than 2 equivalents, preferably 1.05 to 1.5 equivalents, relative to the free isocyanate groups of the prepolymer. When the blocking agent is added midway, it is preferable to use the equivalent of the NCO equivalent of the raw material polyisocyanate minus the equivalent of the polyol and the blocking agent.

When the blocking agent is added, the reaction temperature is usually 50 to 150.
℃. During the reaction, a known urethane polymerization catalyst may be added to accelerate the reaction.

In the present invention, the equivalent ratio of NCO: active hydrogen of the blocked NCO urethane prepolymer and the curing agent (ketimine) is usually 1: 0.
It is 1 to 2, preferably 1: 0.5 to 1.5. If the active hydrogen content is less than 0.1 or more than 2, curing will be insufficient and chipping resistance will be poor. By promoting the reaction between the prepolymer and the curing agent at the time of heating, the heat treatment temperature at the time of applying the coating is lowered or the time is reduced. For the purpose of shortening, a catalyst usually used for promoting dissociation of the blocked urethane prepolymer (organic metal compounds such as zinc octylate and tin octylate, tertiary amine compounds such as triethylenediamine and triethylamine) is used in combination. It is also possible.

The composition of the present invention is formed by diluting the blocked NCO urethane prepolymer and the ketimine in a solvent. If necessary, a pigment and a filler may be added as components of the composition.

Examples of the pigment include inorganic pigments such as titanium oxide, carbon black, red iron oxide, and oxide yellow, and organic pigments such as phthalocyanine blue and phthalocyanine green. As the filler, clay, calcium carbonate,
Barium sulfate, talc, alumina, silica, barite,
Hill stones and white clay are examples.

Further, as the solvent, the same solvent as that used in the production of the urethane polymer can be used, and as described above, since it has been a normal solvent type since the production of the urethane polymer, a similar solvent may be additionally blended as necessary at the time of forming a paint. The solid content concentration may be adjusted.

The composition of the present invention may also optionally contain a fibrin derivative, vinyl chloride resin, phenol resin, ketone resin, synthetic rubber, unsaturated polyester resin, epoxy resin, melamine resin,
Natural or synthetic resins such as urea resins and rosin resins;
Various auxiliaries such as a leveling agent, an anti-sagging agent, an antifoaming agent, a surfactant, a curing accelerator, an anti-repellent agent, a pigment dispersant, an antistatic agent and the like can also be used.

An example of the formulation of the composition of the present invention is as follows, for example. (% Is based on the weight of the composition.) Blocked NCO Usually 20-90% Urethane prepolymer (preferably 30-70%) Ketimine Usually 1-40% (preferably 1-25%) Pigment and usually 5- 80% filler (preferably 10 to 60%) solvent usually 10 to 70% (preferably 20 to 50%) other usually 1 to 20% compounding agent (preferably 1 to 10%) The composition of the present invention is known. It can be manufactured by the method of.
For example, the above components are mixed using an ordinary mixing device (dispers, three rolls, ball mill, steel mill, pebble mill, attritor, sand mill, sand grinder, roll mill, pot mill, high-speed stirrer with blades, etc.), and solvent type It can be obtained by converting it into a one-component paint.

The composition of the present invention can be applied directly to an untreated iron plate surface or a chemical conversion treated iron plate surface, directly to the surface of a galvanized iron plate, or to a surface such as an anion electrodeposition coated surface or a cation electrodeposition coated surface. Painted in the way.

The coating can be performed using an air spray coating machine, an airless spray coating machine, a hot airless spray coating machine, or the like. Since it takes time for the air spray coater to obtain the required film thickness, it is preferable to use the airless spray coater. In the case of an airless spray coating machine, it is usually possible to obtain the required film thickness in one or two strokes, depending on the stroke speed. Brushed,
Roller coating, spatula coating, etc. can be used when repairing or applying to complex areas.

The baking temperature of the composition of the present invention is usually 90 ° C. or higher, preferably
100 to 170 ° C, particularly preferably 110 to 150 ° C. The baking time is usually 120 minutes or less, preferably 10 to 60 minutes.

The dry film thickness formed by the composition of the present invention is usually 30-50.
It is 0 μ, preferably 50 to 350 μ. When the film thickness is less than 30 μ, the chipping resistance is insufficient, while when it exceeds 500 μ, defects such as cracking and sagging are likely to occur.

On the coating film formed from the composition of the present invention, an intermediate coating material is usually applied, and a top coating material is further applied.

The intermediate coating composition can be applied wet-on-wet even when the composition of the present invention is undried, or can be applied even when it is cured and dried. (Dry on wet).

The intermediate coating can be used to improve the gloss of the top coating and to fill fine irregularities on the coating surface, and usually epoxy resin-based paint, melamine alkyd resin-based paint, etc. are used. Examples of the coating method include spray coating method and electrostatic coating method. In addition, the intermediate coating may be omitted.

The top coating can be used for aesthetic purposes, and usually a melamine alkyd resin coating, a thermosetting acrylic resin coating or the like is used, and is applied in the same manner as the intermediate coating.

Wet-on the normal intermediate coating as described above.
After wet coating, it can be cured and dried at a normal baking temperature of about 120 to 170 ° C without any preliminary drying.

The composition of the present invention can be applied not only to the coating film after curing and drying of the base coating but also to any process such as the intermediate coating composition cured coating film or the top coating composition cured coating film.

Further, the composition of the present invention can be coated and baked to form a coating film, and a normal intermediate coating composition, a top coating composition and the like can be further coated thereon to form a coating film by baking. Further, a normal intermediate coating composition, a top coating composition, or the like may be further coated on this and baked to form a coating film.

[Examples] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto.

Parts in the examples indicate parts by weight.

Example 1 1218 parts of tolylene diisocyanate, 2000 parts of polytetramethylene glycol (molecular weight = 1000), 134 parts of trimethylol propane, and 7 to 8 parts of carbitol acetate 4222 parts
The reaction was carried out at 0 ° C. for 3 hours to obtain a urethane prepolymer having an NCO% of 8.8% (solid content conversion). ε-caprolactam 870
NCO group disappeared when 1 part was added and further reacted at 80 to 90 ° C. for 3 hours. Blocked NC with 50% solids
O urethane prepolymer solution was obtained. Using this blocked NCO urethane prepolymer solution, a chipping resistant coating composition was prepared in the following blending ratio.

Blocked NCO urethane prepolymer solution 100 parts Ketimine from diethylenetriamine and methyl isobutyl ketone 7 parts, calcium carbonate 80 parts Titanium white 8 parts Carbon black 2 parts Aromatic petroleum naphtha (boiling range 100-200 ° C) 100 parts Next epoxy Of the above-mentioned chipping-resistant coating composition on a copper plate on which a rust-preventive undercoating film, which has been baked and cured by electro-deposition coating of a cationic cation electrodeposition coating, is applied by an airless coating machine.
It was coated so as to have a thickness of 200μ and baked and cured under the conditions of 140 ° C x 30 minutes.

Example 2 A blocked urethane prepolymer solution was obtained in the same manner as in Example 1 except that tolylene diisocyanate in Example 1 was replaced with diphenylmethane diisocyanate and the blocking agent was changed from ε-caprolactam to methylethylketoxime.

The reaction ratio of the blocked urethane prepolymer is as follows.

Diphenylmethane diisocyanate 1750 parts Polytetramethylene glycol (division amount = 1000) 2000 parts Trimethylolpropane 134 parts Carbitol acetate 4554 parts Methylethylketoxime 670 parts Carried out in the same manner as in Example 1 using the above blocked urethane prepolymer solution. A chipping resistant coating composition was prepared. This chipping-resistant paint was baked and cured in the same manner as in Example 1.

Comparative Example 1 Using the blocked NCO urethane prepolymer solution of Example 1, a chipping resistant coating composition was prepared in the following blending ratios.

Blocked NCO urethane prepolymer 100 parts PO adduct of ethylenediamine (molecular weight = 300) 8 parts Calcium carbonate 80 parts Titanium white 8 parts Carbon black 2 parts Aromatic petroleum naphtha (boiling range 100-200 ° C) 100 parts This chipping resistance The coating composition was baked and cured in the same manner as in Example 1.

Test Example 1 Table 1 shows the evaluation results of the coating properties, chipping resistance, and hot water resistance of the baked coating films of the chipping-resistant coating compositions obtained in Examples 1 and 2 and Comparative Example 1.

Coating film test method Paintability The coating composition was sprayed using an airless sprayer at a film pressure of 200 µm, baked at 140 ° C for 30 minutes, and the appearance (blister, armpit, etc.) of the coating film was examined.

Chipping resistance A JIS B-1 sample was prepared by baking a 200μ thick (after drying) chipping resistant coating composition onto an electrodeposition coated plate of 100 x 100 x 0.8mm.
3 types specified in 181-M-4 shaped iron hexagon nut 2m
From the height of the pipe through a tube with a pipe diameter of 20 mm and dropping it onto each sample plate having an angle of 45 ° with respect to the falling direction of the nut, and showing the total weight of the falling nut until the scratches in the coating film reach the metal surface. Shown in 1.

Hot water resistance The appearance was changed by immersing in warm water of 40 ℃ for 10 days.

"Effects of the Invention" The chipping-resistant coating composition of the present invention is superior in coating property to the underlying electrodeposition coating film, chipping resistance and hot water resistance as compared with the conventional ones.

Therefore, when applied to vehicles, etc., it exhibits excellent rust prevention. The chipping-resistant paint of the present invention is particularly useful as a rust-preventive paint for automobiles and the like because it exhibits the above effects.

Claims (4)

[Claims] 1. A solvent-type one containing a blocked NCO urethane prepolymer and an amine compound selected from the group consisting of (poly) alkylene polyamines, (poly) cycloalkylene polyamines and aromatic polyamines and ketimines from ketones. A chipping-resistant coating composition characterized by being liquid and bake-curable. 2. The blocked NCO urethane prepolymer is an NCO urethane prepolymer blocked with an oxime compound and / or a lactam.
The composition as described. 3. The blocked NCO urethane prepolymer is a blocked product of an NCO urethane prepolymer made of a high molecular weight polyol and optionally a low molecular weight polyol having an average number of functional groups of 2.01 or more and an organic polyisocyanate compound. The composition according to 1 or 2. 4. The composition according to claim 3, wherein the organic polyisocyanate is an aromatic polyisocyanate.