Coating materials generating structured surfaces

Abstract

Disclosed are coating material compositions including (i) at least one polyol component (A), (ii) at least one crosslinking agent component (B) having groups reactive toward hydroxyl groups of component (A), (iii) at least one polyamide component (P1) in which the acid amide groups are connected by a saturated, aliphatic hydrocarbyl radical having 6 to 10 carbon atoms. Component (P1) is used in particulate form in which a size distribution (D.sub.50) is 20 to 100 μm. The coating material compositions further include (iv) at least one polycarboxamide component (P2) possessing the following structural formula ##STR00001##
in which s is 1, 2 or 3, t is 0 or 1, s+t is 2 or 3, R is a specific (s+t)-valent organic radical, and at least one of the radicals R.sup.1 and R.sup.2 carries at least one hydroxyl group. Also disclosed are methods of producing the coating material compositions.

Claims

1. A coating material composition comprising (i) at least one polyol component (A), (ii) at least one crosslinking agent component (B) having groups reactive toward hydroxyl groups of component (A), (iii) at least one polyamide component (P1) wherein the acid amide groups are connected by a saturated, aliphatic hydrocarbyl radical having 6 to 13 carbon atoms, said component being used in a particulate form wherein the size distribution of the primary particles, determined by laser diffraction, possesses a particle size median (D.sub.50) of 20 to 100 μm, and (iv) at least one polycarboxamide component (P2), wherein the polycarboxamide component (P2) possesses the following structural formula ##STR00007## in which s is 1, 2 or 3, t is 0 or 1, and s+t is 2 or 3, R is an (s+t)-valent organic radical selected from the group consisting of (a) aliphatic hydrocarbon groups having 2 to 60 carbon atoms, (b) aliphatic or aliphatic-aromatic radicals containing 2 to 8 carboxamide groups and additionally 6 to 150 carbon atoms in the form of hydrocarbyl radicals, (c) aliphatic radicals containing 2 to 75 ether groups and additionally 4 to 150 carbon atoms in the form of hydrocarbyl radicals, and (d) aromatic hydrocarbon groups having 6 to 20 carbon atoms, R.sup.1 is hydrogen or C.sub.nH.sub.2nR.sup.3, in which n is 2 to 6 and R.sup.3 is hydrogen or a radical of the structure (X).sub.p—R.sup.4, in which p is 0 or 1 and, if p is 0, the radical R.sup.4 is OH, and, if p is 1, the radical X is an oxygen atom or a carboxylic ester group, and R.sup.4 i. is an aliphatic hydrocarbyl radical containing 1 to 3 hydroxyl groups and having 2 to 80 carbon atoms, or ii. is an aliphatic radical containing 1 to 3 hydroxyl groups, containing 0 to 39 groups selected from the group of ether groups and carboxylic ester groups, and additionally containing 2 to 80 carbon atoms in the form of hydrocarbyl radicals; and R.sup.2 is a radical C.sub.nH.sub.2n—(X).sub.p—R.sup.4, wherein n, p, X and R.sup.4 are defined as for R.sup.1; and R′—NH—R″ is a radical —C.sub.nH.sub.2n—NH—C.sub.nH.sub.2n—(X).sub.p—R.sup.4, a radical —R.sup.4′—X—C.sub.nH.sub.2n—NH—R.sup.1 or a radical —R.sup.4′—X—C.sub.nH.sub.2n—NH—C.sub.nH.sub.2n—(X).sub.p—R.sup.4, in which R.sup.4′ is an aliphatic hydrocarbyl radical containing 0 to 2 hydroxyl groups and having 2 to 80 carbon atoms, or R.sup.4′ is an aliphatic radical containing 0 to 2 hydroxyl groups, containing 0 to 39 groups selected from the group of ether groups and carboxylic ester groups, and additionally containing 2 to 80 carbon atoms in the form of hydrocarbyl radicals; and n, p, X and R.sup.4 are as defined for R.sup.1.

2. The coating material composition as claimed in claim 1, wherein the polyamide component (P1) is obtained by ring-opening polymerization of lactams of the following formula (I): ##STR00008## in which n=6 to 10; or by polycondensation of alpha,omega-amino carboxylic acids of the formula (I′):
HOOC—R—NH.sub.2  (I′) where R═C.sub.9-13 alkylene.

3. The coating material composition as claimed in claim 1, wherein R is an (s+t)-valent organic radical selected from the group consisting of (a) aliphatic hydrocarbon groups having 6 to 44, carbon atoms, (b) aliphatic radicals containing 2 carboxamide groups and additionally 70 to 90 carbon atoms in the form of hydrocarbyl radicals, and (c) aliphatic radicals which contain 3 to 13 ether groups (—O—) and additionally 6 to 26 carbon atoms in the form of hydrocarbyl radicals.

4. The coating material composition as claimed in claim 1, wherein both radicals R.sup.1 and R.sup.2 independently of one another are the structure C.sub.nH.sub.2n—(X).sub.p—R.sup.4.

5. The coating material composition as claimed in claim 1, wherein polycarboxamide component (P2) is obtained by reaction of (A) a polycarboxylic acid (III) or a polycarboxylic ester (III) ##STR00009## in which R, s, and t are defined as in claim 1, and R.sup.5 is hydrogen or an alkyl radical having 1 to 6 carbon atoms; or an anhydride of the formula (III′) ##STR00010## in which R, R.sup.5, s, and t are defined as above, and (B) a primary or secondary amine of the formula HNR.sup.1R.sup.2, in which R.sup.1 and R.sup.2 are defined as in claim 1.

6. The coating material composition as claimed in claim 5, wherein the amine NHR.sup.1R.sup.2 is a dialkanolamine or the reaction product of a dialkanolamine with lactones or oxiranes.

7. The coating material composition as claimed in claim 1, wherein the melting point of the polyamide component (P1) according to DIN EN ISO 3146:2002-06 is in the range from 160° C. to 350° C.

8. The coating material composition as claimed in claim 1, wherein the polyol component (A) has a hydroxyl number of 80 to 250 mg KOH/g and is selected from the group of polyester polyols, polyurethane polyols, polysiloxane polyols, and poly(meth)acrylate polyols.

9. The coating material composition as claimed in claim 8, wherein the polyol component (A) is a poly(meth)acrylate polyol.

10. The coating material composition as claimed in claim 1, wherein the crosslinking agent component (B) comprises one or more crosslinking agents selected from the group of crosslinking agents having free isocyanate groups, crosslinking agents having blocked isocyanate groups, amino resins, and tris(alkoxycarbonylamino)triazines.

11. The coating material composition as claimed in claim 10, wherein the crosslinking agent component (B) comprises or consists of one or more crosslinking agents selected from the group of crosslinking agents having free isocyanate groups.

12. The coating material composition as claimed in claim 11, wherein the crosslinking agent is selected from the group consisting of hexamethylene 1,6-diisocyanate, isophorone diisocyanate, and 4,4′ methylenedicyclohexyl diisocyanate, their uretdione dimers, biuret dimers and/or isocyanurate trimers.

13. The coating material composition as claimed in claim 1, being free of silicas.

14. The coating material composition as claimed in claim 1, which comprises as matting agent (M) a silica whereof the size distribution of the primary particles has a particle size median (D.sub.50) below the median of the particles of the polyamide component (P1) used in the coating material.

15. A process for producing a coating material composition as defined in claim 1, wherein the components which are liquid at 25° C. are included wholly or partially in the initial charge, and the components which are solid at 25° C. are stirred in subsequently, with any remainder of the components which are liquid at 25° C.

16. A multicoat paint system which comprises as outermost clearcoat a coat obtained from a coating material composition as claimed in claim 1.

17. The multicoat paint system as claimed in claim 16, the clearcoat possessing a dry film thickness in the range from 20 to 60 μm.

18. A method for producing structured coatings, the method comprising adding a formulation comprising at least one polyamide component (P1) as defined in claim 1 and at least one polycarboxamide component (P2) as defined in claim 1 as an additive to coating material compositions, and producing the structured coatings from the coating material compositions.

19. The coating material composition as claimed in claim 1, wherein R is an (s+t)-valent organic radical selected from the group consisting of (a) aliphatic hydrocarbon groups having 34 to 42 carbon atoms, (b) aliphatic radicals containing 2 carboxamide groups and additionally 70 to 90 carbon atoms in the form of hydrocarbyl radicals, and (c) aliphatic radicals which contain 3 to 13 ether groups (—O—) and additionally 6 to 26 carbon atoms in the form of hydrocarbyl radicals.

Description

EXAMPLES

(1) Unless noted otherwise, all figures are in parts by weight.

(2) Inventive clearcoat materials B1 and B2 are produced. Inventive clearcoat B1 is obtained from 100 parts by weight of the base varnish S1 (see table 1) and 33 parts by weight of the curing agent H (see table 2). Inventive clearcoat B2 is obtained from 106.7 parts by weight of the base varnish S2 (see table 1) and 33 parts by weight of the curing agent H (see table 2). For both inventive clearcoats, accordingly, the ratio of the polyol component (A) to the isocyanate component of the curing agent is identical.

(3) TABLE-US-00001 TABLE 1 Base varnish S1 S2 Polyol component (A).sup.1 67 67 Butyldiglycol acetate 6 6 Butylglycol acetate 3.6 3.6 Butyl acetate 5.4 5.4 Solvent naphtha 160/180 2.7 2.7 Ethoxypropyl acetate 4.4 4.4 Butanol 0.15 0.15 UV absorber 1.0 1.0 HALS 0.9 0.9 Polyether-modified 0.35 0.35 polydimethylsiloxane (flow control agent) Polycarboxamide component (P2).sup.2 0.2 0.2 Polyamide component (P1).sup.3 5.5 15 Matting agent (M).sup.4 2.8 0 .sup.1Poly(meth)acrylate polyol component based on 2-hydroxypropyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, and acrylic acid (65% form; drying: 1 h, 150° C.); OH number: 180 mg KOH/g, M.sub.w: about 4650 g/mol, acid number: about 7 mg KOH/g; .sup.2Polyhydroxycarboxamide .sup.3Polyamide 12, D.sub.50: 57 μm .sup.4Fumed silica; D.sub.50: 10 μm

(4) The liquid base varnish components are premixed. The solids are added subsequently with stirring using a Lenart disk. The mixture is stirred for about 20 minutes. Mixing takes place with a laboratory mixer (Vollrath 370W, model “EWTHV 0.5” from Paul Vollrath GmbH & Co. KG, rotary speed 1200 rpm, toothed disk d=90 mm) at about 800-1000 rpm.

(5) TABLE-US-00002 TABLE 2 Curing agent H Aliphatic polyisocyanate based on HDI trimers 80.6 (isocyanurates) Solvent Naphtha 160/180 9.7 Butyl acetate 9.7

(6) Comparison of Different Structuring Agents

(7) As an inventive example, the clearcoat of example B1 was used (polyamide component (P1); polyamide 12, D.sub.50=57 μm). To produce the noninventive clearcoats, component P1 in the base varnish S1 was replaced in equal amounts by the structuring agents 1 to 3 specified in table 3. This gives, accordingly, the comparative clearcoats VB1 (structuring agent 1), VB2 (structuring agent 2), and VB3 (structuring agent 3).

(8) TABLE-US-00003 TABLE 3 Particle size median Name Chemical description (D.sub.50 in μm) Polyamide component Polyamide 12 57 (P1) Structuring agent 1 Methylpolyurea 31 (comparative) Structuring agent 2 Polypropylene 40 (comparative) Structuring agent 3 Copolyester 39 (comparative)

(9) The inventive clearcoat of example B1 and the noninventive clearcoats VB1, VB2, and VB3 were applied by pneumatic application to a metallic substrate (dry film thickness: 40 μm; flash-off time: 7 min at 23° C.; drying: 20 min at 140° C.) already coated with a cathodic electrocoat material (Cathoguard 500), an aqueous surfacer (FU48-9000; 25-30 μm dry film thickness; flash-off time: 10 min at 23° C.; drying 8 min 70° C.; baking: 17 min at 155° C.) from BASF Coatings GmbH, and a black aqueous basecoat (WB040; dry film thickness 10-15 μm; flash-off time: 5 min at 23° C.) from BASF Coatings GmbH.

(10) The dry film thickness of the clearcoat films formed from the coating materials of examples B1, VB1, VB2 and VB3 was 40 μm.

(11) Determination of the Dry Film Thicknesses

(12) The dry film thicknesses were determined microscopically at 500 times magnification in a ground section method. For this purpose, a piece of the coated substrate measuring approximately 2 cm×2 cm was cut out. The sample was fastened perpendicularly in a mount, which was placed into an embedding mold (diameter about 40 mm). A curable two-component epoxy embedding compound was mixed from 21 parts by weight of Epofix resin and 2.7 parts by weight of Epofix hardener (both from Struers GmbH, Willich, Germany), and this compound was poured into the embedding mold. The embedding compound was cured in the embedding mold for 18 hours. The cured embedding compound with the sample enclosed therein was subsequently removed, ground, and polished. Film thickness measurement took place by means of a microscope (Olympus BX51; reflected light dark field and transmitted light). The dry film thickness of the structured clearcoat was measured at the locations where no particles of structuring agent were apparent.

(13) Constant Condensation Conditions Test

(14) To verify the adhesive strength, the samples were exposed for 240 hours to a constant condensation conditions test in accordance with DIN EN ISO 6270-1: 2002-02 and then examined for blushing after an hour of reconditioning. The results are set out in table 4.

(15) Surface Characterization (Regularity of Structure)

(16) The surface characterization took place both via the tactile quality of the surface and via use of white-light interferometry (psurf mobile instrument from NanoFocus AG, Oberhausen, Germany), allowing the structure of the surface to be ascertained. The term “regularity” denotes a uniform distribution of the particles on the clearcoat surface, which in principle can also be evaluated on a visual basis. By means of the psurf mobile instrument, however, it is possible additionally to determine the height of the particle parts protruding from the clearcoat, which ought, in the sense of regularity, to exhibit very little variation. The results are set out in table 4.

(17) Daimler Gradient Oven Test

(18) In the Daimler gradient oven test (Daimler test method PBODC 371), investigations were carried out in particular into the resistance to fully demineralized water and to pancreatin. Only in the case of polyamide component (P1) was it possible to find resistance to both substances even at temperatures above 81° C. The results are set out in table 4.

(19) Scratch Resistance (AMTEC)

(20) The scratch resistance was determined in accordance with the AMTEC laboratory car wash test to DIN EN ISO 20566 (2007-01). The results are set out in table 4.

(21) TABLE-US-00004 TABLE 4 Test B1 VB1 VB2 VB3 Constant condensation Minimal Very Severe Slight conditions test blushing severe blushing blushing blushing Regularity of +++ + ++ + structure Gradient oven test +++ + +++ ++ (Daimler) Scratch resistance +++ ++ ++ + (AMTEC) +++: very good ++: good +: still good

(22) Sedimentation Behavior

(23) 100 g of the base varnish were introduced into a 200 ml wide-neck glass bottle and stored at room temperature for 7 days.

(24) TABLE-US-00005 TABLE 5 Base varnish VS1 (comparative) S3 Polyol component (A).sup.1 73 73 Butyldiglycol acetate 6.5 6.5 Butylglycol acetate 4 4 Butyl acetate 6.13 6.13 Solvent naphtha 160/180 3 3 Ethoxypropyl acetate 4.77 4.77 Butanol 0.15 0.15 UV absorber 1.1 1.1 HALS 1 1 Polyether-modified 0.35 0.35 polydimethylsiloxane (flow control agent) Polycarboxamide component (P2).sup.2 0 0.2 Polyamide component (P1).sup.3 6 6 Matting agent (M).sup.4 3 3 Sediment No sediment .sup.1Poly(meth)acrylate polyol component based on 2-hydroxypropyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, and acrylic acid (65% form; drying: 1 h, 150° C.); OH number: 180 mg KOH/g, M.sub.w: about 4650 g/mol, acid number: about 7 mg KOH/g; .sup.2Polyhydroxycarboxamide .sup.3Polyamide 12, D.sub.50: 57 μm .sup.4Fumed silica; D.sub.50: 10 μm

(25) In the absence of inventive component P2 from the base varnish (comparative base varnish VS1), an unwanted sediment is formed. In the case of the inventive base varnish there is no sediment.

(26) Determination of Phase Separation

(27) Phase separation was measured using a ruler. The results for the base varnishes S4 to S7 and S8 to S11 for different concentrations of component P2 are reported in table 6.

(28) TABLE-US-00006 TABLE 6 Base varnish S4 S5 S6 S7 S8 S9 S10 S11 Polyol 67 67 67 67 67 67 67 67 component (A).sup.1 Butyldiglycol 6 6 6 6 6 6 6 6 acetate Butylglycol 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 acetate Butyl acetate 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 Solvent naphtha 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 160/180 Ethoxypropyl 4.4 4.4 4.4 4.4 4.4 4.4 4.4 4.4 acetate Butanol 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 UV absorber 1 1 1 1 1 1 1 1 HALS 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 Polyether- 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 modified polydimethyl- siloxane (flow control agent) Polycarboxamide 0.2 0.5 0.7 1.0 0.2 0.5 0.7 1.0 component (P2).sup.2 Polyamide 9 9 9 9 14 14 14 14 component (P1).sup.3 Matting agent 4.sup.4 8 8 8 8 Matting agent 5.sup.5 6 6 6 6 Phase separation 12 11 11 10 27 26 25 22 in nm Sediment no no no no no no no no .sup.1Poly(meth)acrylate polyol component based on 2-hydroxypropyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, andacrylic acid (65% form; drying: 1 h, 150° C.); OH number: 180 mg KOH/g, Mw: about 4650 g/mol, acid number: about 7 mg KOH/g; .sup.2Polyhydroxycarboxamide .sup.3Polyamide 12, D.sub.50: 57 μm .sup.4Polyamide 12, a; D.sub.50: 11 μm .sup.5Polyamide 12, D.sub.50: 6 μm

(29) Circulation Line Stability

(30) The circulation line stability was tested by pumping base varnishes S1 and S2 (see table 1) around in a circulation line while exposing them to a shearing load, the prevailing conditions being as follows:

(31) Pressure at the return flow monitoring valve: 10 bar

(32) Back-and-forth strokes per minute: 18

(33) Volume (back-and-forth stroke): 0.6 l

(34) Prior to the shearing load in the circulation line (turn over=TO=0) and after 100, 500, 720, 1500, and 2000 turns, respectively, in the circulation line, the gloss of the coatings at 60° is measured. Circulation line stability of the coating materials is sufficient when the gloss at an angle of 60° is increased by not more than 10 gloss units after shearing by pumped circulation within a circulation line. The gloss was measured in each case at 60° using a commercial Byk Gardner gloss device, micro-TRI-gloss, cat. No. 4520 from Byk Gardner. The results are set out in table 7.

(35) TABLE-US-00007 TABLE 7 S1 S2 Number of turns Difference Difference (=TO) in the Gloss at relative Gloss at relative circulation line 60° to TO = 0 60° to TO = 0 0 14 0 7 0 100 15 1 6 −1 500 19 4 5 −2 720 19 4 5 −2 1500 21 7 5 −2 2000 19 4 4 −3