CA1298016C - Lessening volatile components in basecoats - Google Patents
Lessening volatile components in basecoatsInfo
- Publication number
- CA1298016C CA1298016C CA000533193A CA533193A CA1298016C CA 1298016 C CA1298016 C CA 1298016C CA 000533193 A CA000533193 A CA 000533193A CA 533193 A CA533193 A CA 533193A CA 1298016 C CA1298016 C CA 1298016C
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- components
- processing conditions
- aliphatic
- polyethers
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D171/00—Coating compositions based on polyethers obtained by reactions forming an ether link in the main chain; Coating compositions based on derivatives of such polymers
- C09D171/02—Polyalkylene oxides
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/38—Paints containing free metal not provided for above in groups C09D5/00 - C09D5/36
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/65—Additives macromolecular
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Paints Or Removers (AREA)
- Electroluminescent Light Sources (AREA)
- Luminescent Compositions (AREA)
- Polyethers (AREA)
Abstract
ABSTRACT
Process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic solvents The invention relates to a process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or solvents, for the production of multicoat finishes, preferably metallic finishes. In the process according to the invention, up to 10% by weight of the components which are volatile under processing conditions, are replaced by an aliphatic polyether or by mixtures of aliphatic polyethers, the aliphatic polyethers having a mean molecular weight of not less than 300, containing not less than one hydroxyl group per molecule and being liquid under normal conditions.
Process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic solvents The invention relates to a process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or solvents, for the production of multicoat finishes, preferably metallic finishes. In the process according to the invention, up to 10% by weight of the components which are volatile under processing conditions, are replaced by an aliphatic polyether or by mixtures of aliphatic polyethers, the aliphatic polyethers having a mean molecular weight of not less than 300, containing not less than one hydroxyl group per molecule and being liquid under normal conditions.
Description
272g3-6 ~298016 The invention relates to a process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or solvents, for the production of multicoat finishes, preferably metallic finishes.
In the area of automotive finishing in particular, but also in other areas, considerable interest centers on basecoat compositions for the production of multicoat finishes.
Multicoat finishes of the basecoat-clearcoat type have gained wide acceptance in automotive finishing, in particular for metallic finishes.
Basecoat-clearcoat finishes are produced in such a way that a pigmented basecoat is applied first, and after a short flash-off period without baking ~the wet-on-wet process), a clear-coat is applied over the basecoat and susbsequently the basecoat and clearcoat are baked together.
The paints for the production of these basecoats must be capable of being processed by the now customary economical wet-on-wet process, ie. they must be capable of being over-coated with a more or less transparent topcoat after a predrying period which is as short as possible, without baking, and without mani-festing interfering dissolution and strike-in phenomena.
In addition, still further problems must be solved in the development of paints for metallic finish basecoats. The metallic effect depends crucially on the orientation of the metallic pigment particles in the paint film. A metallic finish , ~298016 basecoat suitable for the wet-on-wet process must therefore pro-duce paint films in which the metallic pigments are present r after application, in a favorable spatial orientation and in which this orientation is rapidly fixed in such a way that it cannot be dis-turbed in the course of the coating process.
A whole range of basecoat compositions containing pre-dominantly organic diluents or solvents for the production of multicoat finishes, in particular metallic finishes, is known which is suitable for producing multicoat finishes with excellent 1 0 properties.
However, these known basecoat compositions have the disadvantage of containing a relatively low proportion of compo-nents which are non-volatile under the processing conditions.
It is a declared aim of paint manufacturers to reduce the proportion of components which are volatile under processing conditions in basecoat compositions containing predominantly organic diluents or solvents, for the production of multicoat finishes, preferably metallic finishes.
There has been no shortage of experiments aiming at increasing the proportion of non-volatile components at the expense of the volatile components.
Thus attempts have been made, for example, to reduce the mean molecular weight of the binders contained in the basecoat compositions and/or to add microgels and/or solid fillers to the basecoat compositions.
All these measures, however, have disadvantages.
i2980~6 If, for example, the mean molecular weight of the binder components in established, optimally balanced basecoat compositions containing metallic pigments is reduced, it is true that a part of the organic diluents or solvents which are volatile under processing conditions can be dispensed with, but against that one must balance a poorer metallic effect, redissolution problems, deterioration of color retention, and loss of reliabi-lity in application.
The addition of microgels usually affects the rheologi-cal properties of the paint systems; in addition, compatibilityproblems can occur.
Microgels cannot be added to established, optimally balanced basecoat compositions, in particular basecoat composi-tions containing metallic pigments, without creating further problems. They require an expensive adaptation of the total paint system to the amounts and type of the microgels to be added.
The addition of solid fillers to the basecoat composi-tions, in particular to basecoat compositions containing metallic pigments, has a negative effect on the appearance of the resultant finishes and usually does not permit any reduction of the absolute amount of components contained in the basecoat compositions which are volatile under processing conditions.
The present invention seeks to provide a process for increasing the proportion of the components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or solvents for the production of i298016 27293-6 multicoat finishesr preferably metallic finishes.
The process is believed to be applicable to many known and used optimally balanced basecoat compositions, in particular to basecoat compositions containing metallic pigments, without any large technical outlay, and it should not affect negatively the quality (for example redissolution behavior, color retention, reliability in application and achievable metallic effect) of the known, optimally balanced basecoat compositions.
Surprisingly, these objects can be achieved by replacing up to 10% by weight of the components which are volatile under processing conditions by an aliphatic polyether, or by mixtures of aliphatic polyethers the aliphatic polyethers having a mean molecular weight of not less than 300, containing not less than one, preferably not less than two, hydroxyl groups per molecule and being liquid under normnal conditions.
The invention also relates to the use of aliphatic polyethers, which are liquid under normal conditions, or of mix-tures of aliphatic polyethers, preferably polypropylene oxides, having a mean molecular weight of not less than 300 and containing not less than one, preferably not less than two, hydroxyl groups per molecule, for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compo-`~ sitions containing predominantly organic diluents or solvents, for ;~ the production of multicoat finishes, preferably metallic finishes.
; The process according to the invention can be employed for all basecoat compositions containing predominantly organic ' ~
~6 27293-6 diluents or solvents and which may also contain microgels, for the production of multicoat finishes, and is suitable for base-coat compositions which may also contain metallic pigments.
The process according to the invention is preferably used for basecoat compositions containing predominantly organic diluents or solvents, which are suitable for the production of metallic finishes of the basecoat-clearcoat type. Many such basecoat compositions are described in the literature. There are for example the compositions discussed in U.S. Patents 3,639,147;
4,576,868; 4,220,679; and 4,477,536. Paints containing metallic pigments and based on cellulose acetobutyrate/polyester, cellulose acetobutyrate/acrylate resin, polyurethane/polyester, microgel/
acrylate resin or microgel/polyurethane/polyester binder systems are particularly preferred.
The basecoat compositions under discussion are basecoat compositions which contain non-aqueous organic diluents or solvents.
These basecoat compositions are supplied to the paint finisher with a viscosity which is higher than that required for the appli-cation. There the paint is processed by the user in such a way that (1) it is brought to the viscosity required for the applica-tion, by the addition of suitable organic solvents or diluents, (2) it is applied to the substrate by means of generally known application methods (in particular by air spraying or by electrostatic high-speed rotary atomization), (3) it is overcoated with a clearcoat after a flash-off i29~0i6 period generally lasting 30 to 500 seconds, and finally (4) it is baked in general from about 120 to 140C for about 20 minutes.
The term "components non-volatile under processing conditions" is in this context understood to mean paint components which do not lose more than 5% of their weight by volatilization, ie. by evaporation, under conditions prevailing in the processing stages (1) to (4).
The term "aliphatic polyethers" is understood to mean substances containing several strucural units of the general formula R-O, in which R represents an alkylene radical of 2 to 6 carbon atoms.
The aliphatic polyethers which can be used according to the invention, must possess a mean molecular weight of not less than 300. Furthermore, they must contain not less than one, preferably not less than two, hydroxyl groups per molecule and they must be liquid under normal conditions (ie. at about 20C
and 1 atmosphere pressure).
Provided that these limitations are observed, any aliphatic polyether which is soluble or dispersible in the organic solvents or diluents can be used for increasing the proportion of components which are non-volatile under processing conditions.
Examples of such aliphatic polyethers are polyalkylene oxide ~; polyols, such as for example polyethylene oxide polyols, poly-propylene oxide polyols as well as ethoxylation and/or propoxy-lation products of suitable di- to hexavalent starter molecules, ~2~0~6 27293-6 such as for example glycerol, trimethylolpropane, hexanetriol, pentaerythritol, sorbitol, sucrose, ammonia, ethylenediamine, aniline etc. Mixtures of aliphatic polyethers can also be used.
Polypropylene oxide polyols are preferably used. A particularly preferred embodiment employs a polypropylene oxide polyol or a mixture of polypropylene oxide polyols having a molecular weight of 300 to 900.
The addition of the aliphatic polyethers according to the invention is limited by two factors: on the one hand the aliphatic polyethers according to the invention behave in the coatings produced from the basecoat compositions as plasticizers, and on the other hand the aliphatic polyethers according to the invention increase the hydrophilicity of the coatings produced from the basecoat compositions. The extent of the two effects depends as much on the composition of the basecoat compositions as on the nature of the aliphatic polyethers used. The average person skilled in the art can rapidly determine by simple means in what amount a particular aliphatic polyether can be incorporated in a basecoat composition without the coatings produced from it being too soft or too hydrophilic.
Surprisingly, up to 10~ by weight of the components which are volatile under processing conditions can be replaced in established, optimally balanced basecoat compositions preferably containing metallic pigments, by the aliphatic polyethers according to the invention without negatively affecting 12980i6 27293-6 redissolution behavior, color retention, reliability in application or metallic effect of the coatings produced from the basecoat compositions.
The aliphatic polyethers according to the invention probably act as reactive diluents or solvents. They do not have - 7a -12980~6 27293-6 a negative effect on the good properties of optimally balanced basecoat compositions, they are non-volatile under processing conclitions and probably react in the baking process via their hydroxyl groups with suitable binder components, for example melamine-formaldehyde resins.
Surprisingly, it has been further found that the addi-tion according to the invention of such aliphatic polyethers also improves the spray mist pick-up and facilitates the electrostatic application.
By the process according to the invention a process has been made available which permits an increase, by very simple means, of the proportion of components which are non-volatile under processing conditions, in the basecoat compositions under discussion or to adjust it to a given value.
The invention is explained in further detail in the examplesbelow. All parts and percentages are by i29~0~6 weight, unless exDressly stated otherwise.
Example A 1 741 9 of a polyester prepared from adipic acid and neopentyl glycol with a hydroxyl value of 113 and 26.5 9 of diethylene glycol are weighed into a four-necked flask provided with a stirrer, thermometer and reflux condenser, and heated to 100C. The flask is then con-nected to a vacuum for half an hour in order to remove any moisture present. 1,850 9 of butyl acetate, 393 9 of 4,4'-dicyclohexylmethane diisocyanate and 0.3 9 of dibutyl tin dilaurate are added at 5 minute intervals and the temperature is kept at 10QC for 1.5 hours. The NC0 con-tent is then determined. It is 1.36%.
A dilution vessel is initially charged with a mixture of 1,840 9 of butyl acetate, 1,230 9 of n-butanol and 70 9 of hexamethylenediamine. The intermediate con-taining the NC0 groups is added in the course of 15-20 minutes with stirring. An almost colorless viscous solu-tion is obtained with a solids content of 20%.
Example A 2 1,300 9 of a caprolactone polyester with a hy-droxyl value of 112 are dehydrated with 73 9 of neopentyl glycol in vacuo as in Example A 1. After the addition of 1,850 9 of butyl acetate, 688 9 of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate are added first.
After about 5 minutes 0.3 9 of dibutyl tin dilaurate are added. After a reaction time of 2 hours at 100C, the NC0 content of the solution is 2.27%.
A dilution vessel is initially charged with a 12980~6 miYture of 1,490 9 of butyl acetate, l,b71 9 of n-butanol and 88 9 of 1,3-diaminopropane. The intermediate contain-ing the NC0 groups is added in the course of 15-20 minutes with stirring. An almost colorless v;scous solution is obtained with a sol;ds content of 30%.
Example A 3 1,500 9 of a polyester prepared from 1,6-hexane-diol, neopentyl glycol and adipic acid with a hydroxyl value of 75 are dehydrated in vacuo as in Example A 1.
After the addition of 2,200 9 of butyl acetate, 393 9 of 4,4'-dicyclohexylmethane diisocyanate are first added, followed by the addition, after about S minutes, of 0.3 9 of dibutyl tin dilaurate. After a reaction time of 2 hours at 100C the NC0 content of the solution is 0.98%.
A dilution vessel is initially charged with a mix-ture of 2,280 9 of butyl acetate, 1,490 9 of butanol and 98 9 of 1-amino-3-aminomethylcyclohexane. The inter-mediate containing the NC0 groups is added in the course of 15-20 minutes with stirring. A faintly yellowish v;s-cose solution with a solids content of 25~ is obtained.
Example B 1 111.3 9 of 1,3-propanediol, 329.9 9 of 2,2-dime-thyl-1,3-propanediol, 163.5 9 of 1,1,1-trimethylolpropane, 216.7 9 of phthalic anhydride, 243.0 9 of isophthalic acid, 245.0 9 of adipic acid, 30.0 9 of xylene and 2 9 of dibutyl tin oxide are weighed into a 2 liter four-necked flask provided with a stirrer, electric resistance heat-ing, a thermometer, a column packed with Pall rings, equipped with a head thermometer, a distillation bridge, 3 condenser and a receiver The reaction mixture is rapidly heated to 160C with stirring. rhe temperature is raised from 160C to 220C in the course of 5 hours at such a rate that the temperature at the head of the column does not exceed 103C. The temperature is maintained at 220C and esterification is continued until an acid number (according to DIN) of 15 is reached. The reaction mixture is then cooled to 140C, and the polyester is dissolved in 8ûO g of a 1:1 mixture of xylene and ethylglycol acetate with further cooling. A 60% solution, based on the solid polyester, of a polyester of a molecular weight of 93a and a hydroxyl value (DIN) of 160 is obtained.
Example 3 2 60.4 9 of 1,2-ethanediol, 74.0 g of 1,2-propane-diol, 227.9 9 of 2,2-dimethyl-1,3-propanediol, 229.9 9 of 1,6-hexanediol, 485.1 9 of isophthalic acid, 40.0 9 of a mixture of aromatic solvents with a boiling range from 180 to 205C and 3.0 9 of dibutyl tin oxide are weighed out, using the apparatus described in Example ~ 1. The mixture is heated in the same manner as in Example 1 and esterified to an acid value of 20. It is then cooled to 160C, 213.3 9 of adipic acid and 93.5 9 of trimellitic anhydride are added and the temperature is aga;n brought to 200C. It is kept at 200C and esterification is ~ 25 allowed to proceed to an acid number of 25. The mixture ;~ is then cooled and dissolved as in Example B 1. A 60%
solution, based on the solid polyester, of a polyester with a molecular weight of 960 and a hydroxyl value of : :
115 is obtained.
~: :
12980~6 ~xamp~e B 3 Using the apparatus and procedure described in Example 8 l, the following are ~eighed out and esterified at not more than 220-C: 113.4 9 of 1,2-ethanediol, S 142.6 9 of 2,2-dimethyl-1,3-propanediol, 279.8 9 of hy-droxypivalic acid neopentyl glycol ester, 91.9 9 of 1,1,1-trimethylolpropane, 303.5 9 of isophthalic acid, 208.5 9 of hexahydrophthalic anhydride, 200.2 9 of adipic acid, 30 9 of xylene and 2 9 of dibutyl tin oxide.
Esterification is carried out at 220C to an acid number ¢f S. A 60% solution, based on the solid polyester, of a polyester with a molecular weight of 1,520 and a hydroxyl value of 100 is obtained.
Example B 4 Using the apparatus and procedure described in Example B 1, the following are weighed out and ester;fied at not more than 220C: 102.2 9 of 1,2-propanediol, 102.2 9 of 1,3-propanediol, 372.8 9 of 2,2-dimethyl-1,3-propanediol, 60.0 9 of 1,1,1-trimethylolpropane, 331.6 9 of phthalic anhydride, 172.0 9 of trimellitic anhydride, 196.3 9 of adipic acid and 40 9 of a mixture of aromatic solvents of a boiling range of 180-205C.
Heating is carried out as in Example B 1, paying special attention to the temperature at the head of the column, and esterification is allowed to proceed at 200C
to an acid number of 10. The reaction mixture is cooled and dissolved as described in Example 8 1. A 60% solution, based on the solid polyester, of a polyester with a molecular weight of 780 and a hydroxyl value of 198 is obtained.
Example C Melamine resin The following are weighed into a Z liter four-necked flask provided with electrical resistance heat-ing, a stirrer, a thermometer and a distillation ap-paratus for the continuous removal of ~ater with 3 water separator: 560 9 of isobutanol, 250 9 of a 37% aqueous formaldehyde solution, 30 9 of toluene and O.OS g of 85%
phosphoric acid. The reaction mixture is heated to 40C
and 95.3 9 of melamine are added. The mixture is heated to 85C and the temperature is slowly raised to 100C, so that the reaction mixture continuously distills, water being separated off. The mixture is kept at 100C until one part of it is compatible with 5 parts of a petroleum ether of boiling range 135-180C. The reflux part of the distillation apparatus is then closed off and 300 9 of solvent are distilled off; the temperature thereby rises to 115C. The temperature is then reduced to 80C and the reaction mixture is diluted with 65 9 of isobutanol. A
solution of a melamine resin with a solids content (60 min 100C) of 55~ and a viscosity of 250 sec (DIN 53 211) is obtained.
Example D Copolymer dispersion 200 9 of xylene and 100 9 of an ethylene/vinyl acetate copolymer with a vinyl acetate content of 12~ are weighed into a mixer which can be heated and is provided with a high-speed stirrer, the mixture is heated to 100C
and stirred until a homogeneous solution is obtained. The temperature is then reduced to 80C and the solution is precipitated with 700 9 or a mixture of xylene and butyl acetate, the temperature thereby dropping to 50~C. A
10% dispersion of the copolymer is obtained.
Example E 1 Preparation of a microgel concentrate .
2,510 9 of demineralized water are heated to 80C
with 34 9 of 35% sodium lauryl sulfate solution in 3 polymerization vessel provided with a stirrer, re~lux condenser and two inlet vessels.
A pre-emulsion, consisting of 1,267 9 of deminera-lized water, 65 9 of 35% sodium lauryl sulfate solution, 490 9 of butanediol diacrylate, 478 9 of methyl methacry-late and 140 9 of hydroxypropyl methacrylate is prepared, with stirring, in a seperate vessel provided with a stirrer.
One of the inlet vessels is charged with the ini-tiator solution, consisting of 14 g of ammonium per-sul-fate and 660 g of demineralized water. The pre-emulsion and the initiator solution are then metered in simul-taneously at such a rate that the addition of the pre-emulsion takes 2 hours and that of the initiator solu-tion 3 hours. The temperature is kept at 80C by cool-ing. At the end of the addition, the temperature is kept at 80C for a further 1 hour.
; A 20% dispersion of crosslinked particles insolu-ble in any organic solvent, is obtained.
2,000 g of this aqueous dispersion are vigorously shaken in a separating funnel with 620 9 of n-butanol for 10 minutes. After a waiting period of 30 minutes, 2 phases are obtained. The lower aqueous phase is discarded.
The butanol phase containing the microgel is ' ~
. .
12980~6 _ 15 _ transferrei into a distillation flask equipped with a water separator and a stirrer. a33 9 Ot the polyester described in Example B 2 and S00 9 of ethylglycol acetate are added. The remaining water is then distilled off azeotropically in vacuo at a temperature not higher than 60C. A microgel concentrate with a solids content of 32~o is obtained.
Example E 2 2,000 9 of the aqueous dispersion described in Example E 1 are vigorously shaken in a separating funnel with 800 9 of butyl acetate for 15 minutes. After a waiting period of 1.5 hours, 2 phases are obtained. The aqueous phase is discarded. The organic phase is trans-ferred into a distillation flask equipped with a water separator and a stirrer. 400 9 of a polyester prepared from adipic acid and neopentyl glycol with a hydroxyl value of 123 are added. Any water still present is then distilled azeotropically in vacuo at a temperature not higher than 60C. A microgel concentrate with a solids content of 60~ is obtained. 280 9 of 4,4'-dicyclohexyl-- methane diisocyanate and 0.3 9 of dibutyl tin dilaurate are added to 1,500 9 of this concentrate as in Example A 1. After a 2 hours' reaction, the NC0 content is 2.66~.
-;~ A dilution vessel is charged with a mixture of Z5 1,090 9 of butyl acetate, 218 9 of n-butanol and 95 9 of 1-amino-3-aminomethylcyclohexane. The intermediate con-~- taining the NC0 groups and the microgel is added with stirring in the course of 15-20 minutes. A turbid paste-like mass with a bluish glitter with a solids content of - l6 40~ is obtained.
~xamples ~asecoats l to 10 The polyurethane/polyurea elastomer solutions described in Examples A 1 to A 3 are mixed, with stlrring, with the polyester solutions described in Examples 8 1 to 8 4, the melamine-formaldehyde resin described in Exam-ple C and, if appropriate, the copolymer dispersion des-cribed in Example D and/or the microgel dispersion des-cribed in Examples E 1 and E 2 in a vessel provided with a stirrer in such a manner that a homogeneous mixture is produced having the composition, based on 100 parts by weight of the solid, corresponding to the data in Table 1. Subsequently an amount of a non-leafing aluminum bronze indicated in the Table, in the form of a 65% paste with aliphatic hydrocarbons, is cautiously mixed to a dough with 1.5 times the amount of butyl acetate, based on the solid aluminum bronze, added to the previously described mixtures of polyurethane/polyurea elastomer solutions, polyester, melamine-formaldehyde resin solu-tions and, if appropriate, copolymer dispersion or micro-~ gel, and dispersed. The resultant mixtures are adjusted ; to a solids content of 25~ by weight using a mixture of 50 parts by weight of butyl acetate, 25 parts by weight of butylglycol acetate and 25 parts by weight of butanol.
Z5 Subsequently 6 to 7 parts by weight (based on the totalpaint system) of polypropylene oxide diol which is liquid under normal conditions and has a mean molecular weight of about 900, are added to the basecoats formulated in this manner.
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~298016 Examole K 1, Cle3rcoat-acrylate 941 g of a mixture of aromatic solvents with a boiling range of 156-170C are weighed into a 3 liter reaction vessel provided with a thermometer, a stirrer, electric resistance heating, a reflux condenser and an inlet vessel, and heated to 140C with stirring. A mix-ture of 223 9 of styrene, 223 9 of methyl methacrylate, 208 9 of 1,4-butanediol monoacrylate, 30 9 of acrylic acid, 803 9 of n-butyl acrylate and 18 g of di-tert-butyl peroxide is added to the reaction vessel from the inlet vessel in a regular stream in the course of 3 hours and the temperature is kept at 140C. The reaction mixture is kept at 140C for a further 30 minutes and then a soLution of 4 9 of di-tert-butyl peroxide in S0 9 of the mixture of aromatic solvents with a boiling range between 156 and 172C is added.
After a further 2 hours at 140C, an acryLate resin solution with a solidscontent of 60% is obtained.
The acrylate resin has an acid number of 14, a hydroxyl number of 109 and a viscosity of 250 mPa.s (determined as a 50% solution in xylene using the ICI viscometer).
Example K 2, CLearcoat 300 9 of the solution of the melamine-formaldehyde resin described in Example C, 150 9 of xylene and 50 9 of butylglycol acetate are added with stirring to 550 9 of the 60% acryLate resin solution described in ExampLe K 1 and cautiously mixed. A clearcoat with 3 sol ids content of 46.5% is obtained.
12980~6 ~ - 19 -?roduct~on of ~he coatings To produce the coatings, sections of body panels used in automotive mass Droduction finishing which have been passivated by iron phosphating and have received a coating of paint by cathodic electrodeposition and a baking filler, are coated ~ith the basecoats described in Examples 1 to 13 and the clearcoat described in Example K 2.
For this purpose, the viscosity of the basecoats described in Examples 1 to 10 iâ adjusted to a value of 16 sec according to DIN 53 211 using a solvent mixture of xylene and butyl acetate (70:30), and that of the clear-coat described in Example K 2 to a viscosity of 28 sec ac-cording to DIN 53 211 using this solvent mixture.
The pre-treated body panel sections, described above, are spray-coated with the adjusted basecoats using a flow-cup spray gun with a nozzle 1.2 mm wide and a spray pressure of 4 bar in such a manner that a basecoat dry film thickness of 12 to 17 ~m is obtained. The sprayed-on basecoat is spray-coated after 5 minutes with the ad-justed clearcoat, using the spraying conditions indicated above, in such a manner that a clearcoat dry film thick-~ ness of 35 to 40 ~m is obtained. After a 15 minutes' ;~ flash-off period at room temperature the panels are baked in a circulating air oven at 130C for 30 minutes.
The coatings prepared in this manner exhibit a metallic effect considered to be outstanding by an exPert, they meet the requirements of the tests listed in the tech-nical delivery conditions of automotive mass production finishing and they are indistinguishable from coatings ~ .
- 2~ -prepared from po~ye~her-free systems under the same con-ditions.
Systems which are free from polyethers require for the adjustment of spray viscosity a greater amount S of diluting solvent mixture than the systems according to the invention containing polyethers.
.
In the area of automotive finishing in particular, but also in other areas, considerable interest centers on basecoat compositions for the production of multicoat finishes.
Multicoat finishes of the basecoat-clearcoat type have gained wide acceptance in automotive finishing, in particular for metallic finishes.
Basecoat-clearcoat finishes are produced in such a way that a pigmented basecoat is applied first, and after a short flash-off period without baking ~the wet-on-wet process), a clear-coat is applied over the basecoat and susbsequently the basecoat and clearcoat are baked together.
The paints for the production of these basecoats must be capable of being processed by the now customary economical wet-on-wet process, ie. they must be capable of being over-coated with a more or less transparent topcoat after a predrying period which is as short as possible, without baking, and without mani-festing interfering dissolution and strike-in phenomena.
In addition, still further problems must be solved in the development of paints for metallic finish basecoats. The metallic effect depends crucially on the orientation of the metallic pigment particles in the paint film. A metallic finish , ~298016 basecoat suitable for the wet-on-wet process must therefore pro-duce paint films in which the metallic pigments are present r after application, in a favorable spatial orientation and in which this orientation is rapidly fixed in such a way that it cannot be dis-turbed in the course of the coating process.
A whole range of basecoat compositions containing pre-dominantly organic diluents or solvents for the production of multicoat finishes, in particular metallic finishes, is known which is suitable for producing multicoat finishes with excellent 1 0 properties.
However, these known basecoat compositions have the disadvantage of containing a relatively low proportion of compo-nents which are non-volatile under the processing conditions.
It is a declared aim of paint manufacturers to reduce the proportion of components which are volatile under processing conditions in basecoat compositions containing predominantly organic diluents or solvents, for the production of multicoat finishes, preferably metallic finishes.
There has been no shortage of experiments aiming at increasing the proportion of non-volatile components at the expense of the volatile components.
Thus attempts have been made, for example, to reduce the mean molecular weight of the binders contained in the basecoat compositions and/or to add microgels and/or solid fillers to the basecoat compositions.
All these measures, however, have disadvantages.
i2980~6 If, for example, the mean molecular weight of the binder components in established, optimally balanced basecoat compositions containing metallic pigments is reduced, it is true that a part of the organic diluents or solvents which are volatile under processing conditions can be dispensed with, but against that one must balance a poorer metallic effect, redissolution problems, deterioration of color retention, and loss of reliabi-lity in application.
The addition of microgels usually affects the rheologi-cal properties of the paint systems; in addition, compatibilityproblems can occur.
Microgels cannot be added to established, optimally balanced basecoat compositions, in particular basecoat composi-tions containing metallic pigments, without creating further problems. They require an expensive adaptation of the total paint system to the amounts and type of the microgels to be added.
The addition of solid fillers to the basecoat composi-tions, in particular to basecoat compositions containing metallic pigments, has a negative effect on the appearance of the resultant finishes and usually does not permit any reduction of the absolute amount of components contained in the basecoat compositions which are volatile under processing conditions.
The present invention seeks to provide a process for increasing the proportion of the components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or solvents for the production of i298016 27293-6 multicoat finishesr preferably metallic finishes.
The process is believed to be applicable to many known and used optimally balanced basecoat compositions, in particular to basecoat compositions containing metallic pigments, without any large technical outlay, and it should not affect negatively the quality (for example redissolution behavior, color retention, reliability in application and achievable metallic effect) of the known, optimally balanced basecoat compositions.
Surprisingly, these objects can be achieved by replacing up to 10% by weight of the components which are volatile under processing conditions by an aliphatic polyether, or by mixtures of aliphatic polyethers the aliphatic polyethers having a mean molecular weight of not less than 300, containing not less than one, preferably not less than two, hydroxyl groups per molecule and being liquid under normnal conditions.
The invention also relates to the use of aliphatic polyethers, which are liquid under normal conditions, or of mix-tures of aliphatic polyethers, preferably polypropylene oxides, having a mean molecular weight of not less than 300 and containing not less than one, preferably not less than two, hydroxyl groups per molecule, for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compo-`~ sitions containing predominantly organic diluents or solvents, for ;~ the production of multicoat finishes, preferably metallic finishes.
; The process according to the invention can be employed for all basecoat compositions containing predominantly organic ' ~
~6 27293-6 diluents or solvents and which may also contain microgels, for the production of multicoat finishes, and is suitable for base-coat compositions which may also contain metallic pigments.
The process according to the invention is preferably used for basecoat compositions containing predominantly organic diluents or solvents, which are suitable for the production of metallic finishes of the basecoat-clearcoat type. Many such basecoat compositions are described in the literature. There are for example the compositions discussed in U.S. Patents 3,639,147;
4,576,868; 4,220,679; and 4,477,536. Paints containing metallic pigments and based on cellulose acetobutyrate/polyester, cellulose acetobutyrate/acrylate resin, polyurethane/polyester, microgel/
acrylate resin or microgel/polyurethane/polyester binder systems are particularly preferred.
The basecoat compositions under discussion are basecoat compositions which contain non-aqueous organic diluents or solvents.
These basecoat compositions are supplied to the paint finisher with a viscosity which is higher than that required for the appli-cation. There the paint is processed by the user in such a way that (1) it is brought to the viscosity required for the applica-tion, by the addition of suitable organic solvents or diluents, (2) it is applied to the substrate by means of generally known application methods (in particular by air spraying or by electrostatic high-speed rotary atomization), (3) it is overcoated with a clearcoat after a flash-off i29~0i6 period generally lasting 30 to 500 seconds, and finally (4) it is baked in general from about 120 to 140C for about 20 minutes.
The term "components non-volatile under processing conditions" is in this context understood to mean paint components which do not lose more than 5% of their weight by volatilization, ie. by evaporation, under conditions prevailing in the processing stages (1) to (4).
The term "aliphatic polyethers" is understood to mean substances containing several strucural units of the general formula R-O, in which R represents an alkylene radical of 2 to 6 carbon atoms.
The aliphatic polyethers which can be used according to the invention, must possess a mean molecular weight of not less than 300. Furthermore, they must contain not less than one, preferably not less than two, hydroxyl groups per molecule and they must be liquid under normal conditions (ie. at about 20C
and 1 atmosphere pressure).
Provided that these limitations are observed, any aliphatic polyether which is soluble or dispersible in the organic solvents or diluents can be used for increasing the proportion of components which are non-volatile under processing conditions.
Examples of such aliphatic polyethers are polyalkylene oxide ~; polyols, such as for example polyethylene oxide polyols, poly-propylene oxide polyols as well as ethoxylation and/or propoxy-lation products of suitable di- to hexavalent starter molecules, ~2~0~6 27293-6 such as for example glycerol, trimethylolpropane, hexanetriol, pentaerythritol, sorbitol, sucrose, ammonia, ethylenediamine, aniline etc. Mixtures of aliphatic polyethers can also be used.
Polypropylene oxide polyols are preferably used. A particularly preferred embodiment employs a polypropylene oxide polyol or a mixture of polypropylene oxide polyols having a molecular weight of 300 to 900.
The addition of the aliphatic polyethers according to the invention is limited by two factors: on the one hand the aliphatic polyethers according to the invention behave in the coatings produced from the basecoat compositions as plasticizers, and on the other hand the aliphatic polyethers according to the invention increase the hydrophilicity of the coatings produced from the basecoat compositions. The extent of the two effects depends as much on the composition of the basecoat compositions as on the nature of the aliphatic polyethers used. The average person skilled in the art can rapidly determine by simple means in what amount a particular aliphatic polyether can be incorporated in a basecoat composition without the coatings produced from it being too soft or too hydrophilic.
Surprisingly, up to 10~ by weight of the components which are volatile under processing conditions can be replaced in established, optimally balanced basecoat compositions preferably containing metallic pigments, by the aliphatic polyethers according to the invention without negatively affecting 12980i6 27293-6 redissolution behavior, color retention, reliability in application or metallic effect of the coatings produced from the basecoat compositions.
The aliphatic polyethers according to the invention probably act as reactive diluents or solvents. They do not have - 7a -12980~6 27293-6 a negative effect on the good properties of optimally balanced basecoat compositions, they are non-volatile under processing conclitions and probably react in the baking process via their hydroxyl groups with suitable binder components, for example melamine-formaldehyde resins.
Surprisingly, it has been further found that the addi-tion according to the invention of such aliphatic polyethers also improves the spray mist pick-up and facilitates the electrostatic application.
By the process according to the invention a process has been made available which permits an increase, by very simple means, of the proportion of components which are non-volatile under processing conditions, in the basecoat compositions under discussion or to adjust it to a given value.
The invention is explained in further detail in the examplesbelow. All parts and percentages are by i29~0~6 weight, unless exDressly stated otherwise.
Example A 1 741 9 of a polyester prepared from adipic acid and neopentyl glycol with a hydroxyl value of 113 and 26.5 9 of diethylene glycol are weighed into a four-necked flask provided with a stirrer, thermometer and reflux condenser, and heated to 100C. The flask is then con-nected to a vacuum for half an hour in order to remove any moisture present. 1,850 9 of butyl acetate, 393 9 of 4,4'-dicyclohexylmethane diisocyanate and 0.3 9 of dibutyl tin dilaurate are added at 5 minute intervals and the temperature is kept at 10QC for 1.5 hours. The NC0 con-tent is then determined. It is 1.36%.
A dilution vessel is initially charged with a mixture of 1,840 9 of butyl acetate, 1,230 9 of n-butanol and 70 9 of hexamethylenediamine. The intermediate con-taining the NC0 groups is added in the course of 15-20 minutes with stirring. An almost colorless viscous solu-tion is obtained with a solids content of 20%.
Example A 2 1,300 9 of a caprolactone polyester with a hy-droxyl value of 112 are dehydrated with 73 9 of neopentyl glycol in vacuo as in Example A 1. After the addition of 1,850 9 of butyl acetate, 688 9 of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate are added first.
After about 5 minutes 0.3 9 of dibutyl tin dilaurate are added. After a reaction time of 2 hours at 100C, the NC0 content of the solution is 2.27%.
A dilution vessel is initially charged with a 12980~6 miYture of 1,490 9 of butyl acetate, l,b71 9 of n-butanol and 88 9 of 1,3-diaminopropane. The intermediate contain-ing the NC0 groups is added in the course of 15-20 minutes with stirring. An almost colorless v;scous solution is obtained with a sol;ds content of 30%.
Example A 3 1,500 9 of a polyester prepared from 1,6-hexane-diol, neopentyl glycol and adipic acid with a hydroxyl value of 75 are dehydrated in vacuo as in Example A 1.
After the addition of 2,200 9 of butyl acetate, 393 9 of 4,4'-dicyclohexylmethane diisocyanate are first added, followed by the addition, after about S minutes, of 0.3 9 of dibutyl tin dilaurate. After a reaction time of 2 hours at 100C the NC0 content of the solution is 0.98%.
A dilution vessel is initially charged with a mix-ture of 2,280 9 of butyl acetate, 1,490 9 of butanol and 98 9 of 1-amino-3-aminomethylcyclohexane. The inter-mediate containing the NC0 groups is added in the course of 15-20 minutes with stirring. A faintly yellowish v;s-cose solution with a solids content of 25~ is obtained.
Example B 1 111.3 9 of 1,3-propanediol, 329.9 9 of 2,2-dime-thyl-1,3-propanediol, 163.5 9 of 1,1,1-trimethylolpropane, 216.7 9 of phthalic anhydride, 243.0 9 of isophthalic acid, 245.0 9 of adipic acid, 30.0 9 of xylene and 2 9 of dibutyl tin oxide are weighed into a 2 liter four-necked flask provided with a stirrer, electric resistance heat-ing, a thermometer, a column packed with Pall rings, equipped with a head thermometer, a distillation bridge, 3 condenser and a receiver The reaction mixture is rapidly heated to 160C with stirring. rhe temperature is raised from 160C to 220C in the course of 5 hours at such a rate that the temperature at the head of the column does not exceed 103C. The temperature is maintained at 220C and esterification is continued until an acid number (according to DIN) of 15 is reached. The reaction mixture is then cooled to 140C, and the polyester is dissolved in 8ûO g of a 1:1 mixture of xylene and ethylglycol acetate with further cooling. A 60% solution, based on the solid polyester, of a polyester of a molecular weight of 93a and a hydroxyl value (DIN) of 160 is obtained.
Example 3 2 60.4 9 of 1,2-ethanediol, 74.0 g of 1,2-propane-diol, 227.9 9 of 2,2-dimethyl-1,3-propanediol, 229.9 9 of 1,6-hexanediol, 485.1 9 of isophthalic acid, 40.0 9 of a mixture of aromatic solvents with a boiling range from 180 to 205C and 3.0 9 of dibutyl tin oxide are weighed out, using the apparatus described in Example ~ 1. The mixture is heated in the same manner as in Example 1 and esterified to an acid value of 20. It is then cooled to 160C, 213.3 9 of adipic acid and 93.5 9 of trimellitic anhydride are added and the temperature is aga;n brought to 200C. It is kept at 200C and esterification is ~ 25 allowed to proceed to an acid number of 25. The mixture ;~ is then cooled and dissolved as in Example B 1. A 60%
solution, based on the solid polyester, of a polyester with a molecular weight of 960 and a hydroxyl value of : :
115 is obtained.
~: :
12980~6 ~xamp~e B 3 Using the apparatus and procedure described in Example 8 l, the following are ~eighed out and esterified at not more than 220-C: 113.4 9 of 1,2-ethanediol, S 142.6 9 of 2,2-dimethyl-1,3-propanediol, 279.8 9 of hy-droxypivalic acid neopentyl glycol ester, 91.9 9 of 1,1,1-trimethylolpropane, 303.5 9 of isophthalic acid, 208.5 9 of hexahydrophthalic anhydride, 200.2 9 of adipic acid, 30 9 of xylene and 2 9 of dibutyl tin oxide.
Esterification is carried out at 220C to an acid number ¢f S. A 60% solution, based on the solid polyester, of a polyester with a molecular weight of 1,520 and a hydroxyl value of 100 is obtained.
Example B 4 Using the apparatus and procedure described in Example B 1, the following are weighed out and ester;fied at not more than 220C: 102.2 9 of 1,2-propanediol, 102.2 9 of 1,3-propanediol, 372.8 9 of 2,2-dimethyl-1,3-propanediol, 60.0 9 of 1,1,1-trimethylolpropane, 331.6 9 of phthalic anhydride, 172.0 9 of trimellitic anhydride, 196.3 9 of adipic acid and 40 9 of a mixture of aromatic solvents of a boiling range of 180-205C.
Heating is carried out as in Example B 1, paying special attention to the temperature at the head of the column, and esterification is allowed to proceed at 200C
to an acid number of 10. The reaction mixture is cooled and dissolved as described in Example 8 1. A 60% solution, based on the solid polyester, of a polyester with a molecular weight of 780 and a hydroxyl value of 198 is obtained.
Example C Melamine resin The following are weighed into a Z liter four-necked flask provided with electrical resistance heat-ing, a stirrer, a thermometer and a distillation ap-paratus for the continuous removal of ~ater with 3 water separator: 560 9 of isobutanol, 250 9 of a 37% aqueous formaldehyde solution, 30 9 of toluene and O.OS g of 85%
phosphoric acid. The reaction mixture is heated to 40C
and 95.3 9 of melamine are added. The mixture is heated to 85C and the temperature is slowly raised to 100C, so that the reaction mixture continuously distills, water being separated off. The mixture is kept at 100C until one part of it is compatible with 5 parts of a petroleum ether of boiling range 135-180C. The reflux part of the distillation apparatus is then closed off and 300 9 of solvent are distilled off; the temperature thereby rises to 115C. The temperature is then reduced to 80C and the reaction mixture is diluted with 65 9 of isobutanol. A
solution of a melamine resin with a solids content (60 min 100C) of 55~ and a viscosity of 250 sec (DIN 53 211) is obtained.
Example D Copolymer dispersion 200 9 of xylene and 100 9 of an ethylene/vinyl acetate copolymer with a vinyl acetate content of 12~ are weighed into a mixer which can be heated and is provided with a high-speed stirrer, the mixture is heated to 100C
and stirred until a homogeneous solution is obtained. The temperature is then reduced to 80C and the solution is precipitated with 700 9 or a mixture of xylene and butyl acetate, the temperature thereby dropping to 50~C. A
10% dispersion of the copolymer is obtained.
Example E 1 Preparation of a microgel concentrate .
2,510 9 of demineralized water are heated to 80C
with 34 9 of 35% sodium lauryl sulfate solution in 3 polymerization vessel provided with a stirrer, re~lux condenser and two inlet vessels.
A pre-emulsion, consisting of 1,267 9 of deminera-lized water, 65 9 of 35% sodium lauryl sulfate solution, 490 9 of butanediol diacrylate, 478 9 of methyl methacry-late and 140 9 of hydroxypropyl methacrylate is prepared, with stirring, in a seperate vessel provided with a stirrer.
One of the inlet vessels is charged with the ini-tiator solution, consisting of 14 g of ammonium per-sul-fate and 660 g of demineralized water. The pre-emulsion and the initiator solution are then metered in simul-taneously at such a rate that the addition of the pre-emulsion takes 2 hours and that of the initiator solu-tion 3 hours. The temperature is kept at 80C by cool-ing. At the end of the addition, the temperature is kept at 80C for a further 1 hour.
; A 20% dispersion of crosslinked particles insolu-ble in any organic solvent, is obtained.
2,000 g of this aqueous dispersion are vigorously shaken in a separating funnel with 620 9 of n-butanol for 10 minutes. After a waiting period of 30 minutes, 2 phases are obtained. The lower aqueous phase is discarded.
The butanol phase containing the microgel is ' ~
. .
12980~6 _ 15 _ transferrei into a distillation flask equipped with a water separator and a stirrer. a33 9 Ot the polyester described in Example B 2 and S00 9 of ethylglycol acetate are added. The remaining water is then distilled off azeotropically in vacuo at a temperature not higher than 60C. A microgel concentrate with a solids content of 32~o is obtained.
Example E 2 2,000 9 of the aqueous dispersion described in Example E 1 are vigorously shaken in a separating funnel with 800 9 of butyl acetate for 15 minutes. After a waiting period of 1.5 hours, 2 phases are obtained. The aqueous phase is discarded. The organic phase is trans-ferred into a distillation flask equipped with a water separator and a stirrer. 400 9 of a polyester prepared from adipic acid and neopentyl glycol with a hydroxyl value of 123 are added. Any water still present is then distilled azeotropically in vacuo at a temperature not higher than 60C. A microgel concentrate with a solids content of 60~ is obtained. 280 9 of 4,4'-dicyclohexyl-- methane diisocyanate and 0.3 9 of dibutyl tin dilaurate are added to 1,500 9 of this concentrate as in Example A 1. After a 2 hours' reaction, the NC0 content is 2.66~.
-;~ A dilution vessel is charged with a mixture of Z5 1,090 9 of butyl acetate, 218 9 of n-butanol and 95 9 of 1-amino-3-aminomethylcyclohexane. The intermediate con-~- taining the NC0 groups and the microgel is added with stirring in the course of 15-20 minutes. A turbid paste-like mass with a bluish glitter with a solids content of - l6 40~ is obtained.
~xamples ~asecoats l to 10 The polyurethane/polyurea elastomer solutions described in Examples A 1 to A 3 are mixed, with stlrring, with the polyester solutions described in Examples 8 1 to 8 4, the melamine-formaldehyde resin described in Exam-ple C and, if appropriate, the copolymer dispersion des-cribed in Example D and/or the microgel dispersion des-cribed in Examples E 1 and E 2 in a vessel provided with a stirrer in such a manner that a homogeneous mixture is produced having the composition, based on 100 parts by weight of the solid, corresponding to the data in Table 1. Subsequently an amount of a non-leafing aluminum bronze indicated in the Table, in the form of a 65% paste with aliphatic hydrocarbons, is cautiously mixed to a dough with 1.5 times the amount of butyl acetate, based on the solid aluminum bronze, added to the previously described mixtures of polyurethane/polyurea elastomer solutions, polyester, melamine-formaldehyde resin solu-tions and, if appropriate, copolymer dispersion or micro-~ gel, and dispersed. The resultant mixtures are adjusted ; to a solids content of 25~ by weight using a mixture of 50 parts by weight of butyl acetate, 25 parts by weight of butylglycol acetate and 25 parts by weight of butanol.
Z5 Subsequently 6 to 7 parts by weight (based on the totalpaint system) of polypropylene oxide diol which is liquid under normal conditions and has a mean molecular weight of about 900, are added to the basecoats formulated in this manner.
.
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., O _ o ,n N O N
aJ ~
J N 10 ~J
O C C" I I ~r II C~J I ~ I I ~.1 aJ
C C
al o C O O ~U ~ C~J
o ~n ~ 1 1 1 1'~I I
V~ _ ~ O
~ V~
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: ~ ~ : ~ O
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::
~298016 Examole K 1, Cle3rcoat-acrylate 941 g of a mixture of aromatic solvents with a boiling range of 156-170C are weighed into a 3 liter reaction vessel provided with a thermometer, a stirrer, electric resistance heating, a reflux condenser and an inlet vessel, and heated to 140C with stirring. A mix-ture of 223 9 of styrene, 223 9 of methyl methacrylate, 208 9 of 1,4-butanediol monoacrylate, 30 9 of acrylic acid, 803 9 of n-butyl acrylate and 18 g of di-tert-butyl peroxide is added to the reaction vessel from the inlet vessel in a regular stream in the course of 3 hours and the temperature is kept at 140C. The reaction mixture is kept at 140C for a further 30 minutes and then a soLution of 4 9 of di-tert-butyl peroxide in S0 9 of the mixture of aromatic solvents with a boiling range between 156 and 172C is added.
After a further 2 hours at 140C, an acryLate resin solution with a solidscontent of 60% is obtained.
The acrylate resin has an acid number of 14, a hydroxyl number of 109 and a viscosity of 250 mPa.s (determined as a 50% solution in xylene using the ICI viscometer).
Example K 2, CLearcoat 300 9 of the solution of the melamine-formaldehyde resin described in Example C, 150 9 of xylene and 50 9 of butylglycol acetate are added with stirring to 550 9 of the 60% acryLate resin solution described in ExampLe K 1 and cautiously mixed. A clearcoat with 3 sol ids content of 46.5% is obtained.
12980~6 ~ - 19 -?roduct~on of ~he coatings To produce the coatings, sections of body panels used in automotive mass Droduction finishing which have been passivated by iron phosphating and have received a coating of paint by cathodic electrodeposition and a baking filler, are coated ~ith the basecoats described in Examples 1 to 13 and the clearcoat described in Example K 2.
For this purpose, the viscosity of the basecoats described in Examples 1 to 10 iâ adjusted to a value of 16 sec according to DIN 53 211 using a solvent mixture of xylene and butyl acetate (70:30), and that of the clear-coat described in Example K 2 to a viscosity of 28 sec ac-cording to DIN 53 211 using this solvent mixture.
The pre-treated body panel sections, described above, are spray-coated with the adjusted basecoats using a flow-cup spray gun with a nozzle 1.2 mm wide and a spray pressure of 4 bar in such a manner that a basecoat dry film thickness of 12 to 17 ~m is obtained. The sprayed-on basecoat is spray-coated after 5 minutes with the ad-justed clearcoat, using the spraying conditions indicated above, in such a manner that a clearcoat dry film thick-~ ness of 35 to 40 ~m is obtained. After a 15 minutes' ;~ flash-off period at room temperature the panels are baked in a circulating air oven at 130C for 30 minutes.
The coatings prepared in this manner exhibit a metallic effect considered to be outstanding by an exPert, they meet the requirements of the tests listed in the tech-nical delivery conditions of automotive mass production finishing and they are indistinguishable from coatings ~ .
- 2~ -prepared from po~ye~her-free systems under the same con-ditions.
Systems which are free from polyethers require for the adjustment of spray viscosity a greater amount S of diluting solvent mixture than the systems according to the invention containing polyethers.
.
Claims (6)
1. A process for increasing the proportion of components which are non-volatile under processing conditions, in basecoat compositions containing predominantly organic diluents or sol-vents, for the production of multicoat finishes, wherein up to 10% by weight of the components which are volatile under paint processing conditions, are replaced by an aliphatic polyether or by mixtures of aliphatic polyethers, the aliphatic polyethers having a mean molecular weight of not less than 300, containing not less than one hydroxyl group per molecule, and being liquid under normal conditions.
2. A process as claimed in claim 1, wherein the multi-coat finish is a metallic finish.
3. A process as claimed in claim 1, wherein the poly-ether or mixture of polyethers contains not less than two hydroxyl groups per molecule.
4. A process as claimed in claim 1, wherein the poly-ether or mixture of polyethers is at least one polypropylene oxide.
5. A process as claimed in claim 1, wherein up to 10% by weight of the components which are volatile under processing conditions, are replaced by a polypropylene oxide polyol or by mixtures of polypropylene oxide polyols having a mean molecular weight of 300 to 900.
6. A basecoat composition, for the production of multi-coat finishes, wherein up to 10% by weight of the components which are volatile under paint processing conditions have been replaced by an aliphatic polyether, or by mixtures of aliphatic polyethers, the aliphatic polyethers having a mean molecular weight of not less than 300, containing at least one hydroxyl group per molecule, and being liquid under normal conditions.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863610765 DE3610765A1 (en) | 1986-03-29 | 1986-03-29 | METHOD FOR INCREASING THE PROPORTION OF INGREDIENTS OF NON-VOLATILE IN PROCESSING CONDITIONS IN PRIMARY COATING COMPOSITIONS CONTAINING ORGANIC SOLVENTS |
| DEP3610765.4 | 1986-03-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1298016C true CA1298016C (en) | 1992-03-24 |
Family
ID=6297604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000533193A Expired - Lifetime CA1298016C (en) | 1986-03-29 | 1987-03-27 | Lessening volatile components in basecoats |
Country Status (8)
| Country | Link |
|---|---|
| EP (2) | EP0239796B1 (en) |
| JP (1) | JPH0613644B2 (en) |
| AT (1) | ATE57389T1 (en) |
| BR (1) | BR8707651A (en) |
| CA (1) | CA1298016C (en) |
| DE (2) | DE3610765A1 (en) |
| ES (1) | ES2018178B3 (en) |
| WO (1) | WO1987005923A1 (en) |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1253846B (en) * | 1964-06-11 | 1967-11-09 | Bayer Ag | Paint auxiliaries for water-dilutable binder systems |
| JPS5023412A (en) * | 1973-07-02 | 1975-03-13 | ||
| NL7602590A (en) * | 1976-03-12 | 1977-09-14 | Akzo Nv | Solvent-free, alkyd amino stoving resin compsn. - contains polyalkylene glycol and acid catalyst |
| US4150007A (en) * | 1977-10-25 | 1979-04-17 | Eastman Kodak Company | Aqueous coating of curable binder, cross-linker and oxyethylated 2,2,4-trimethylpentane-1,3-diol |
| JPS5676471A (en) * | 1979-11-26 | 1981-06-24 | Toto Kasei Kk | Coating material for metal |
| BE884612A (en) * | 1980-08-01 | 1980-12-01 | Grow Group Inc | COMPOSITION AND METHOD FOR MITIGATING POLLUTION RESULTING FROM THE APPLICATION OF A COATING COMPOSITION. |
| JPS58147466A (en) * | 1982-02-26 | 1983-09-02 | Nippon Steel Corp | Paint composition for precoated steel plate |
| FI843517L (en) * | 1983-10-17 | 1985-04-18 | Hercules Inc | BELAEGGNINGSKOMPOSITIONER INNEHAOLLANDE KOPOLYMERER AV ETYLENOXID OCH LAONGKEDJADE EPOXIDER. |
| JPS61193842A (en) * | 1985-02-25 | 1986-08-28 | 日本鋼管株式会社 | Two-coat two-baking precoated board having excellent heat-resistant property |
-
1986
- 1986-03-29 DE DE19863610765 patent/DE3610765A1/en not_active Withdrawn
-
1987
- 1987-02-26 AT AT87102780T patent/ATE57389T1/en not_active IP Right Cessation
- 1987-02-26 ES ES87102780T patent/ES2018178B3/en not_active Expired - Lifetime
- 1987-02-26 DE DE8787102780T patent/DE3765441D1/en not_active Expired - Lifetime
- 1987-02-26 EP EP87102780A patent/EP0239796B1/en not_active Expired - Lifetime
- 1987-02-26 WO PCT/EP1987/000116 patent/WO1987005923A1/en not_active Application Discontinuation
- 1987-02-26 EP EP87901466A patent/EP0298967A1/en not_active Withdrawn
- 1987-02-26 JP JP62501715A patent/JPH0613644B2/en not_active Expired - Lifetime
- 1987-02-26 BR BR8707651A patent/BR8707651A/en not_active IP Right Cessation
- 1987-03-27 CA CA000533193A patent/CA1298016C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE3765441D1 (en) | 1990-11-15 |
| JPH01501942A (en) | 1989-07-06 |
| EP0298967A1 (en) | 1989-01-18 |
| ES2018178B3 (en) | 1991-04-01 |
| WO1987005923A1 (en) | 1987-10-08 |
| ATE57389T1 (en) | 1990-10-15 |
| EP0239796B1 (en) | 1990-10-10 |
| EP0239796A1 (en) | 1987-10-07 |
| JPH0613644B2 (en) | 1994-02-23 |
| DE3610765A1 (en) | 1987-10-01 |
| BR8707651A (en) | 1989-08-15 |
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