Adhesion promoter for solventborne primer surfacers

Abstract

The present invention relates to a solventborne primer surfacer which comprises at least one additive preparable by reacting at least one alpha,omega-hydroxy-functionalized oligoester which possesses an OH number of 30 to 160 mg KOH/g, a theoretical carbon-carbon double bond content of 1 to 2.5 mmol/g, a number-average molecular weight of 1000 to 3000 g/mol, and a weight-average molecular weight of 2800 to 10 000 g/mol, and at least one alkoxysilane which possesses an OH-reactive functional group, the sum of the weight percentage fractions of all additives of the invention being 0.5 to 10 wt %, based on the total amount of the solventborne primer surfacer. The present invention further relates to a process for producing multicoat paint systems, and to multicoat paint systems producible by means of said process. The invention further relates to the use of the additive identified above in solventborne primer surfacers for improving adhesion.

Claims

1. A solventborne primer surfacer comprising at least one organic solvent and at least one additive preparable by reacting (a) at least one alpha,omega-hydroxy-functionalized oligoester which possesses the following structural formula (I): ##STR00004## where the radicals R.sub.1 independently of one another are a linear or cyclic alkylene radical, the radicals R.sub.2 independently of one another are an alkylene or alkenylene radical, the ratio of alkylene to alkenylene radicals being such that the alpha,omega-hydroxy-functionalized oligoester of the structural formula (I) possesses a theoretical carbon-carbon double bond content of 1 to 2.5 mmol/g, and the index m is such that the number-average molecular weight of the alpha,omega-hydroxy-functionalized oligoester of the structural formula (I) is 1000 to 3000 g/mol, wherein the alpha,omega-hydroxy-functionalized oligoester possesses an OH number of 30 to 160 mg KOH/g, and a weight-average molecular weight of 2800 to 10 000 g/mol, and (b) at least one alkoxysilane of the structural formula (II)
A-RSi(R).sub.x(OR).sub.3-x where A is an OH-reactive functional group, R is an aliphatic radical having 2 to 12 carbon atoms, a cycloaliphatic radical having 3 to 12 carbon atoms, an aromatic radical having 6 to 12 carbon atoms, or an araliphatic radical having 7 to 18 carbon atoms, the radical R is a C.sub.1 to C.sub.12 alkyl radical, R is a methyl or ethyl radical, and x is 0 to 2, with the proviso that at least 90 mol % of all the OH groups of the alpha,omega-hydroxy-functionalized oligoester have been reacted with an OH-reactive functional group A, and, the sum of the weight percentage fractions of all additives of the invention is 0.5 to 10 wt %, based on the total amount of the solventborne primer surfacer.

2. The solventborne primer surfacer as claimed in claim 1, wherein the alpha,omega-hydroxy-functionalized oligoester is prepared using at least one saturated linear aliphatic dicarboxylic acid or anhydride thereof, at least one monounsaturated linear aliphatic dicarboxylic acid or anhydride thereof, and at least one saturated aliphatic diol.

3. The solventborne primer surfacer of claim 1, wherein the sum of the weight percentage fractions of all the additives is 1.5 to 7.5 wt %, based on the total amount of the solventborne primer surfacer.

4. The solventborne primer surfacer as claimed in claim 1, wherein the radicals R.sub.1 are linear alkylene radicals having 6 to 10 carbon atoms.

5. The solventborne primer surfacer of claim 1, wherein the radicals R.sub.2 are linear alkylene radicals having 4 to 8 carbon atoms or linear alkenylene radicals having 2 to 4 carbon atoms.

6. The solventborne primer surfacer of claim 1, wherein the alkoxysilane possesses the general structural formula (II.1)
OCNR.sub.1Si(R).sub.x(OR).sub.3-x where R.sub.1 is a C.sub.2 to C.sub.12 alkylene radical, a C.sub.2 to C.sub.12 alkenylene radical, or a polyunsaturated C.sub.4 to C.sub.12 alkylene radical, the radical R is a C.sub.1 to C.sub.12 alkyl radical, R is a methyl or ethyl radical, and x is 0 to 2.

7. The solventborne primer surfacer as claimed in claim 6, wherein R.sub.1 is a C.sub.2 to C.sub.6 alkylene radical.

8. The solventborne primer surfacer as claimed in claim 6, wherein x=0.

9. The solventborne primer surfacer of claim 1, wherein the oligoester (a) is obtained by reacting components that comprise at least one saturated linear aliphatic dicarboxylic acid and at least one mono- or polyunsaturated linear aliphatic dicarboxylic acid.

10. The solventborne primer surfacer of claim 1, wherein the oligoester (a) is obtained by reacting components that comprise at least one saturated linear aliphatic dicarboxylic acid and at least one mono- or polyunsaturated linear aliphatic dicarboxylic acid, and wherein a molar ratio of saturated dicarboxylic acid to mono- and/or polyunsaturated aliphatic dicarboxylic acid is from 0.5:1.5 to 1.5:0.5.

11. The solventborne primer surfacer of claim 1, wherein the at least one organic solvent is a member selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers, alcohols, and mixtures thereof.

12. A process for producing a multicoat paint system on a substrate, the process comprising (A) applying the primer surfacer of claim 1, and (B) applying a further coating material.

13. The process as claimed in claim 12, wherein i. the primer surfacer film obtained in step (A) is dried, ii. the coating material in step (B) is a topcoat material, and iii. the dried primer surfacer film and the topcoat film obtained in step (B) are jointly cured.

14. A multicoat paint system producible by the process as claimed in claim 13.

15. The process as claimed in claim 12, wherein i. a primer is applied to the substrate before the application of the primer surfacer in step (A), and the resulting primer film is dried, ii. the dried primer film and the primer surfacer film obtained in step (A) are jointly cured, iii. the further coating material in step (B) is a basecoat material, and is applied to the cured primer surfacer film and subsequently dried, and iv. a clearcoat material is applied to the dried basecoat film, and the dried basecoat film and the resulting clearcoat film are jointly cured.

16. A multicoat paint system producible by the process as claimed in claim 15.

17. A process for improving adhesion of a primer surfacer, the process comprising formulating at least one organic solvent and at least one additive into a solventborne primer surfacer, wherein the at least one additive is preparable by reacting (a) at least one alpha,omega-hydroxy-functionalized oligoester which possesses the following structural formula (I): ##STR00005## where the radicals R.sub.1 independently of one another are a linear or cyclic alkylene radical, the radicals R.sub.2 independently of one another are an alkylene or alkenylene radical, the ratio of alkylene to alkenylene radicals being such that the alpha,omega-hydroxy-functionalized oligoester of the structural formula (I) possesses a theoretical carbon-carbon double bond content of 1 to 2.5 mmol/g, and the index in is such that the number-average molecular weight of the alpha,omega-hydroxy-functionalized oligoester of the structural formula (I) is 1000 to 3000 g/mol, wherein the alpha,omega-hydroxy-functionalized oligoester possesses an OH number of 30 to 160 mg KOH/g, and a weight-average molecular weight of 2800 to 10 000 g/mol, and (b) at least one alkoxysilane of the structural formula (II)
A-RSi(R).sub.x(OR).sub.3-x where A is an OH-reactive functional group, R is an aliphatic radical having 2 to 12 carbon atoms, a cycloaliphatic radical having 3 to 12 carbon atoms, an aromatic radical having 6 to 12 carbon atoms, or an araliphatic radical having 7 to 18 carbon atoms, the radical R is a C.sub.1 to C.sub.12 alkyl radical, R is a methyl or ethyl radical, and x is 0 to 2, with the proviso that at least 90 mol % of all the OH groups of the alpha,omega-hydroxy-functionalized oligoester have been reacted with an OH-reactive functional group A, and, the sum of the weight percentage fractions of all additives of the invention is 0.5 to 10 wt %, based on the total amount of the solventborne primer surfacer.

18. The process of claim 17, wherein the at least one organic solvent is a member selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers, alcohols, and mixtures thereof.

Description

EXAMPLES

Preparation Examples

Example A: Preparation of an Alpha,Omega-Hydroxy-Functionalized Oligoester

(1) The reactants identified in table 1 are reacted as set out below in the molar proportions indicated therein. First of all, maleic anhydride (MAn), adipic acid (AD), and 1,6-hexanediol (HD) are charged to a 4-liter reactor made from stainless steel and equipped with a column, a condenser, and a water separator. Subsequently, 3% of xylene is added as an entrainer, and 0.1% of methylhydroquinone (the percentage figures are based on the amount of MAn, AD and HD used). The resulting reaction mixture is heated under lean air over the course of 5 hours. Throughout the reaction time, the temperature of the reaction mixture does not exceed 230 C. When an acid number of 2 mg KOH/g is reached, the reaction mixture is cooled to 80 C. The characteristic data for the resulting alpha,omega-hydroxy-functionalized oligoesters are as follows: OH number: 65 mg KOH/g Number-average molecular weight: 1412 g/mol Weight-average molecular weight: 3313 g/mol

(2) Theoretical carbon-carbon double bond content: 1.86 mmol/g

(3) TABLE-US-00001 TABLE 1 Amounts of substance of the reactants for use, in mol. Raw Amount of material substance 1 MAn 5.05 2 AD 5.53 3 HD 14.46 Solids content [%] 97

Example B: Preparation of an Inventive Additive (A1)

(4) A steel reactor equipped with a reflux condenser and a thermometer is charged with 27.4 parts of 3-isocyanatopropyltriethoxysilane from ABCR GmbH & Co. KG (European dispatch of Gelest INC. products), 9.4 parts of butyl acetate, 0.2 part of 1,4-diazabicyclo[2.2.2]octane, and 2.2 parts of triethyl orthoformate. From a dropping funnel, subsequently, a mixture of 46.3 parts of the alpha,omega-hydroxy-functionalized oligoester (example A) and 14.5 parts of butyl acetate is added dropwise under a nitrogen atmosphere, with stirring. After 6 hour stirring at 70-80 C., the NCO value is verified by titrimetry according to DIN EN ISO 11909 (date: May 2007) and the reaction is continued until an NCO value of 0 is found. The inventive additive A1 has a nonvolatiles content of 71.8 wt %.

(5) I) Refinish on Utility Vehicles

(6) I.1) Preparation of a Solventborne Primer Surfacer Comprising Additive (A1)

(7) A commercial primer surfacer was used. It is composed of the three components primer surfacer component, curing agent, and diluent. The respective compositions of these components are reproduced in table 2. The primer surfacer, curing agent, and diluent components are used in a ratio of 100:19.5:16, the ratio being based on the weight of the components. This gives the total amount of the primer surfacer. In each case, 0, 2, 4 and 6 wt % of the inventive additive (A1) is used, based on the total amount of the primer surfacer. A laboratory stirrer (260-1820 rpm) is employed for mixing. Additive A1 is added to the curing component.

(8) TABLE-US-00002 TABLE 2 Composition of the primer surfacer used (primer surfacer component, curing agent, diluent). Curing agent Primer surfacer component Diluent Component wt % Component wt % Component wt % HDI-Basonat HI 190 B/S, 50.5 Commercial dispersion of 23.9 1-Methoxypropyl acetate 46.5 90% SN an OH-functional acrylate resin in organic solvents Xylene 5.0 Xylene 2.0 Butyl acetate 98-100% 30.0 Butyl acetate 98-100% 23.7 Solvent naphtha 3.7 Xylene 20.0 1-Methoxypropyl acetate 9.0 Nuosperse FA 601 0.2 Butyl glycol acetate 2.0 Silquest A-187 3.6 1-Methoxypropyl acetate 6.7 Ethyl 3- 1.5 ethoxypropionate Baysilon OL 44 0.7 Aerosil 380 0.2 Activator 7.5 Bentone 34, 100% 1.7 Lamp black-101 0.1 Bayferrox 920 1.8 Incomp KL 30 6.5 Heucophos ZP0 12.4 Luzenac 10MO 9.2 Titanium rutile 12.5 Shieldex AC 3 6.6 Butyl glycol acetate 1.5 1-Methoxypropyl acetate 2.7 Xylene 0.4 Leveling agent 0.5 Baysilone Fluid OL-44 0.1 Epoxy resin 8.6 Silquest A-187: gamma-glycidyloxypropyltrimethoxy-silane, Baysilon OL 44: Surface additive, activator: DBTL solution (1 wt % DBTL) in xylene/butyl acetate, Nuosperse FA 601: wetting and dispersing agent, Aerosil 380: hydrophilic fumed silica, Bentone 34: rheological additive, Russ flamm - 101: carbon black pigment, Bayferrox 920: yellow iron pigment, Incomp KL 30: mineral based on talc and dolomite, Heucophos ZP0: anticorrosion pigment, Luzenac 10MO: magnesium silicate, Shieldex AC 3: anticorrosion pigment.

(9) I.2) Production of Coated Substrates

(10) Substrates used were aluminum panels, each in the form of test plates with a size of 20100.45 cm. The panels were first of all abraded. This was done using P240 grade abrasive paper. Shortly before the application of the primer surfacer, the primer surfacer component, curing agent, and diluent were stirred together homogeneously using a wooden spatula. Application was by pneumatic spraying. It was followed by drying of the resulting primer surfacer film at room temperature for 60 minutes. Then a commercial topcoat material was applied by pneumatic spraying. This was followed by drying at room temperature for 10 minutes, after which primer surfacer film and topcoat film were cured jointly at a substrate temperature of 60 C. in a forced air oven for 30 minutes. In the resulting substrate, the primer surfacer coat had a dry film thickness of 77 micrometers and the topcoat had a dry film thickness of 75 micrometers.

(11) The commercial topcoat material is composed of the three components topcoat component, curing agent, and diluent. The topcoat, curing agent, and diluent components are used in a ratio of 100:19.5:16, the ratio being based on the weight of the components. The respective compositions of these components for preparing the topcoat material are reproduced in table 3.

(12) TABLE-US-00003 TABLE 3 Composition of the topcoat used (topcoat component, curing agent, diluent). Curing agent Topcoat component Diluent Component wt % Component wt % Component wt % HDI-Desmodur 90 Polyester 3.5 VOC 12.4 1-Methoxypropyl 6 N3600 acetate Butyl 10 Acetylacetone 2.2 Butyl acetate 98-100% 50 acetate 98-100% Benzoic acid D 0.4 Xylene 15 Methyl isobutyl ketone 1 Butyl glycol acetate 3 BYK-331 100% 0.08 Ethyl 1 ethoxypropionate BYK-358 N, 52% 0.1 Solvent naphtha 13 160/180 Tinuvin 292 0.31 White spirit 135/180 10 Tinstab BL 277 100% 0.04 Dipentene 2 BYK 054 0.18 Disparlon 9050 0.26 Xylene 3 Butyl acetate 98-100% 4.2 1-Methoxypropyl acetate 0.71 Acrylique 324 New Process BASF 21.1 Acrylique TSA UNO BASF 14.32 Bentone 34, 100% 0.2 Aerosil R972 0.3 Disperbyk-180 0.9 Titanium rutile, Tiona 595 37.3 Solvent naphtha 165/185 0.9 Additive M-P-A 2000X, 20% in xylene 0.001 Disperbyk-111 0.003 Bayferrox 3920 0.11 Disperbyk-166, 30% methylpropyl 0.001 acetate/butyl acetate 1:4 Spezialschwarz 100 carbon black 0.003 Activator 0.00015 Polyester 3.5 VOC is a commercial, OH-functional polyester (dispersion in organic solvents). Acrylique 324 New Process BASF is a conventional dispersion of an OH-functional OH-acrylate in organic solvents. Acrylique TSA UNO BASF is likewise a conventional dispersion of an OH-functional OH-acrylate in organic solvents. The activator is a catalyst.

(13) I.3) Investigation of the Adhesion Properties

(14) The adhesion properties of the coatings produced were investigated by cross-cut (DIN EN ISO 2409; date: April 2010) after four different aging conditions. For each primer surfacer composition, characterized by its additive content (no additive, 2 wt %, 4 wt %, and 6 wt %), a total of two samples were produced and were each investigated individually. From the results obtained, the average was formed for each primer surfacer composition.

(15) The first aging condition relates to storage at 40 C. for 16 hours. For the three further aging conditions, the samples were stored for 10 days in a conditioning chamber (CC) at 100% humidity and 40 C. (constant conditions test according to DIN EN ISO 6270-2 CH; date: September 2005). The adhesion of the samples was then investigated 1 hour, 3 hours, and 24 hours after removal from the conditioning chamber.

(16) The results obtained are set out in table 4. The entry none there means that delamination occurred neither between substrate and primer surfacer nor between primer surfacer and topcoat. Furthermore, the entry Ps/Tc means that delamination was observed between primer surfacer and topcoat.

(17) The adhesion was evaluated using a rating system with ratings from 0 to 5, with the rating 0 being awarded to coatings exhibiting no visible traces after the adhesion test (very good adhesion). The rating 5 was awarded to coatings which exhibited significantly detached regions after the adhesion test (inadequate adhesion).

(18) From the results set out in table 4 it follows that a distinct improvement can be achieved in the adhesion through the use of the additive.

(19) TABLE-US-00004 TABLE 4 Adhesion properties of the unadditized and additized primer surfacers. Aging- no 2 wt % 4 wt % 6 wt % condition additive additive additive additive 16 h after 1 1 1 0 40 C. Delamination none none none none between: 1 h after CC 3 3 0 1 Delamination Ps/Tc Ps/Tc none none between: 3 h after CC 5 5 2 3 Delamination Ps/Tc Ps/Tc Ps/Tc Ps/Tc between: 24 h after 4 3 1 2 CC Delamination Ps/Tc Ps/Tc Ps/Tc Ps/Tc between:

(20) II) Automotive Refinish

(21) II.1) Preparation of a Solventborne Primer Surfacer Comprising Additive (A1)

(22) A commercial primer surfacer was used. It is composed of the three components primer surfacer component, curing agent, and diluent. The respective compositions of these components are reproduced below in table 5. The primer surfacer component, curing agent, and diluent components are used in a ratio of 100:17.5:13.5, the ratio being based on the weight of the components. This produces the total amount of the primer surfacer. Amounts in each case of 0, 2, 4, and 6 wt % of the bifunctional additive (A1) of the invention are used, based on the total amount of the primer surfacer. Additization is carried out using a laboratory stirrer (260-1820 rpm). Additive A1 is added to the curing component.

(23) TABLE-US-00005 TABLE 5 Composition of the primer surfacer used (primer surfacer component, curing agent, diluent). Curing agent Primer surfacer component Diluent Component wt % Component wt % Component wt % HDI-Desmodur N3600 35.1 Polyester 5085 19.03 1-Methoxypropyl acetate 6 Butyl acetate 98-100% 41.1 Acrylester 365 2.2 Butyl acetate 98-100% 50 1-Methoxyprop-2-yl 4.25 BYK-P 104, 50% in 0.23 Xylene 15 acetate xylene/DIBK, 9:1 Xylene 5.65 Bentone 34, 100% 0.52 Butyl glycol acetate 3 Ethyl ethoxypropionate 1.6 Butyl acetate 98-100% 10.12 Ethyl ethoxypropionate 1 Tinstab BL 277 100% 0.06 1-Methoxypropyl 6.6 Solvent naphtha 160/180 13 acetate Desmodur XP 2565, 80% 12.3 Aerosil R972 1.48 White spirit 135/180 10 butyl acetate Talc AT Extra, Micro 5.15 Dipentene 2 China Clay Polwhite B 12.65 Zinc phosphate PZ 20 10.2 Tiona 595 10.54 Bayferrox 306 1.27 Blanc Fixe N 11.6 Zeeospheres G-400 5.15 Xylene 0.85 Tinstab BL 277 100% 0.1 DOW E.R. 671 60% 2.21 strength in xylene Butyl glycol acetate 0.1 Polyester 5085 is a conventional, OH-functional polyester (dispersion in organic solvents). Acrylester 365 is a conventional dispersion of an OH-functional OH-acrylate in organic solvents.

(24) II.2) Production of Coated Substrates

(25) Substrates used were panels of steel, each in the form of test plates with a size of 20100.3 cm. The panels were first of all abraded. This was done using P180 grade abrasive paper. Shortly before application of the primer surfacer, the primer surfacer, curing agent, and diluent components were stirred together homogeneously using a wooden spatula. First a commercial primer was applied, followed by drying at room temperature for 10 minutes. The primer surfacer was then applied by pneumatic spraying, followed by drying at room temperature for 10 minutes. The two films were then baked at a substrate temperature of 60 C. in a forced air oven for 25 minutes. The primer had a dry film thickness of 16 micrometers, and the primer surfacer coat a dry film thickness of micrometers. The primer surfacer was subsequently sanded manually (P400 sanding pad) and then cleaned of sanding residues by conventional diluted cleaner. Next, a commercial basecoat material was applied, followed by drying at room temperature for 10 minutes. A commercial 2-component clearcoat material was then applied by pneumatic spraying, followed again by drying at room temperature for 10 minutes. The overall basecoat-clearcoat system was then baked at a substrate temperature of 60 C. in a forced air oven for 10 minutes. The basecoat had a dry film thickness of 15 micrometers, and the clearcoat a dry film thickness of 38 micrometers.

(26) A commercial primer was used. It is composed of the three components millbase, curing agent, and diluent. The respective compositions of these components are reproduced below. The millbase, curing agent, and diluent components are used in a ratio of 100:35.8:8, the ratio being based on the weight of the components.

(27) TABLE-US-00006 TABLE 6 Composition of the primer used (millbase component, curing agent, diluent). Millbase component Curing agent Diluent Component wt % Component wt % Component wt % Butanol 5.6 Ethanol 27 1-Methoxyprop-2-yl acetate 46.5 n-Propanol 21.8 Isopropanol 56 Butyl acetate 98-100% 30 Isobutanol 3 Butanol 13 Xylene 20 Butyl acetate 98-100% 8 Phosphoric acid 4 Butyl glycol acetate 2 Mowital B 30H, 100% 5.5 Ethyl ethoxypropionate 1.5 Xylene 7.8 Parosin FE 45.5 6.3 Phenodur PR 263 70% in butanol 3.4 Calcium naphthenate 4% Ca 0.4 Silica HDK T40 0.7 Tiona 595 9.8 Luzenac 10MO 7.7 Zinc oxide NC, 100% 2.1 Zinc phosphate PZ 20 5.7 Bayferrox 3910 3.7 Bayferrox 130BM 0.07 Lamp Black 101 powder 0.07 Plastopal H 73 IB/X 35:1 0.5 Solution Ethylcellulose 4 Solution Aldehydique 4.3 Plastopal H 73 IB/X 35:1 is a urea-formaldehyde resin. Tiona 95 is rutile. Phenodur PR 263 70% is a phenolic resin from Cytec.

(28) A commercial basecoat material was used. It is composed of the two components mixing varnish and standardizing additive. The respective compositions of these components are reproduced below. The basecoat material is prepared using the mixing varnish and standardizing additive components in a ratio of 2:1, the ratio being based on the volume of the components.

(29) TABLE-US-00007 TABLE 7 Composition of the basecoat material used. Standardizing Mixing varnish additive Component wt % Component wt % Conventional PU 72.8 Water 97.3 dispersion 1 Conventional PU 12 Biocide 0.2 dispersion 2 Conventional PU 1.6 Pluriol P900 1 dispersion 3 Butyl glycol 0.5 Laponite RD 1.5 Alu Star 6 Hydrolux 8154, 65% Alu Star 1.4 Hydrolux F90, 65% sec-Butanol 3.7 Raybo 61, 60% 0.1 TMDD BG 52 1.7 Farbru FW 2 0.004 carbon black Aerosil R972 0.5 Bayferrox 3910/R 0.04 Lanco Pew 1555 0.65 Lanco Pew 1555 is a water-thinnable polyether wax from Lubrizol.

(30) A commercial clearcoat material was used. It is composed of the three components millbase, curing agent, and diluent. The respective compositions of these components are reproduced below. The millbase, curing agent, and diluent components are used in a ratio of 100:50:8.6, the ratio being based on the weight of the components.

(31) TABLE-US-00008 TABLE 8 Composition of the clearcoat material used (millbase component, curing agent, diluent). Millbase component Curing agent Diluent Component wt % Component wt % Component wt % Ethyl ethoxypropionate 4 1-Methoxyprop-2-yl 3 1-Methoxypropyl acetate 6 acetate Methyl isobutyl ketone 6 Butyl acetate 98-100% 15 Butyl acetate 98-100% 50 Commercial acrylate 81 Xylene 10 Xylene 15 dispersion Benzoic acid D 1 Methyl isobutyl ketone 13 Butyl glycol acetate 3 Tinuvin 5941-R 2.2 DBTL 0.12 Ethyl ethoxypropionate 1 Commercial acrylate 3 Benzoic acid D 2.5 Solvent naphtha 160/180 13 dispersion Byk 325, 52% 0.2 Water scavenger 0.35 White spirit 135/180 10 Tinstab BL 277 100% 2.2 HDI-Desmodur N3600 56 Dipentene 2 Butyl acetate 98-100% 2.6

(32) II.3) Investigation of the Adhesion Properties

(33) The adhesion properties of the coatings produced were investigated as described under I.3) by means of cross-cut (DIN EN ISO 2409; date: April 2010) after four different aging conditions.

(34) The results obtained are set out in table 9. The entry none here means that delamination occurred between the coats. Furthermore, the entry Bc/Ps/Tc means that delamination was observed not only between basecoat and primer surfacer but also between primer surfacer and primer. The entry Bc/Ps/Su means that delamination was observed not only between basecoat and primer surfacer but also between primer surfacer, primer, and basecoat. The entry Ps/Pr, finally, means that delamination occurred exclusively between primer surfacer and primer.

(35) The adhesion was evaluated using a rating system with ratings from 0 to 5, with the rating 0 being awarded to coatings exhibiting no visible traces after the adhesion test (very good adhesion). The rating 5 was awarded to coatings which exhibited significantly detached regions after the adhesion test (inadequate adhesion).

(36) TABLE-US-00009 TABLE 9 Adhesion properties of the unadditized and additized primer surfacers. no 2 wt % of 4 wt % of 6 wt % of Aging condition additive additive additive additive 16 h after 40 C. 4.5 2.5 1.5 0.5 Delamination Bc/Ps/Pr Bc/Ps/Su Bc/Ps/Pr Bc/Ps/Su between: 1 h after CC 1.5 0.5 2.5 3 Delamination Bc/Ps/Pr Bc/Ps/Pr Bc/Ps/Pr Bc/Ps/Pr between: 3 h after CC 2.5 0 1 0 Delamination Bc/Ps/Pr none Bc/Ps/Pr none between: 24 h after CC 1 1 0.5 0.5 Delamination Ps/Pr Bc/Ps/Pr Bc/Ps/Pr none between:

(37) From the results set out in table 9, it follows that a distinct improvement in adhesion is achievable through the use of the additive.