LIGHT-INDUCED COLD APPLICATION OF A THICK-LAYERED ANTICORROSIVE COATING WITH CONTROLLABLE KINETICS

Abstract

An anti-corrosive agent, a method for anticorrosive coating of a component and a system for anti-corrosive coating of a component are provided. The anti-corrosive agent, which is a body-cavity preserving agent, an agent for underbody sealing, an agent for permanent protective coating for storage and transportation or an agent for temporary protective coating for storage and transportation, is intended for the corrosion protection of a component, in particular an automotive part. The anti-corrosive agent can be applied without additional heating, is radiation-induced radical and/or cationic, preferably in the case of thick layers, crosslinking and has application-specific, controllable reaction kinetics and adapted heat resistance.

Claims

1. A process for the anti-corrosion coating of a motor vehicle component, wherein the anti-corrosive is a cavity preservation agent or an agent for underbody protective coating, the process comprising the steps: applying an anti-corrosive to the component, the anti-corrosive including at least one photoinitiator and optionally a photosensitizer, irradiating the anti-corrosive with radiation tailored to absorption by the at least one photoinitiator and by any optional photosensitizer, wherein the anti-corrosive is at the end of irradiation solid or else solidifies in a time-adjusted manner, the anti-corrosive comprising: 0.1% to 10.0% by weight of at least one photoinitiator, 0.0% to 0.1% by weight of a photosensitizer, 1.0% to 40.0% by weight of a binder, 0% to 10.0% by weight of a reactive diluent, 0.0% to 10.0% by weight of an additive, 5.0% to 50.0% by weight of an oil, 1.0% to 20.0% by weight of a wax, 0.0% to 40.0% by weight of an anti-corrosion additive, and 0.0% to 20.0% by weight of a filler and/or a pigment, based on 100% by weight of the anti-corrosive, the coating having a thickness of 50 to 8000 μm.

2. The process for the anti-corrosion coating as claimed in claim 1, wherein the anti-corrosive at the end of irradiation remains solid and/or flowable for a period t of 5 minutes or longer and thereafter solidifies, even in thick layers, within the range up to 5000 μm.

3. The process as claimed in claim 1, wherein the viscosity of the flowable anti-corrosive at room temperature at the end of irradiation is 10.sup.1 mPa.Math.s to 10.sup.6 mPa's.

4. The process as claimed in claim 2, wherein 0.1 hours≤t≤2 hours.

5. The process as claimed in claim 1, wherein the application of an anti-corrosive to the component step includes the steps of: spraying an anti-corrosive into/onto the component and allowing the anti-corrosive to penetrate/run.

6. The process as claimed in claim 1, wherein the entire process takes place at a temperature of ≤30° C.

7. The process as claimed in claim 1, wherein the at least one photoinitiator is selected from the group benzophenone, benzoyl ether, aminoketone, thioxanthone, acylphosphine oxide, sulfonium salt, ferrocenium salt, and iodonium salt.

8. The use as claimed in claim 1, wherein the binder is selected from the group consisting of an acrylate, for example a polyurethane acrylate, polyester acrylate or epoxy acrylate, unsaturated polyesters and thiolene system, vinyl ethers and heterocycles.

9. The process as claimed in claim 1, wherein the anti-corrosive comprises 4.0% to 6.0% by weight of the at least one photoinitiator, 0.0% to 0.1% by weight of a photosensitizer, 32.0% to 37.0% by weight of a binder-reactive diluent mixture, and 18.0% to 22.0% by weight of an oil-wax mixture, preferably wherein the at least one photoinitiator is a hydroxy ketone and a hydroxycyclohexyl phenyl ketone, wherein the binder is an acrylate, wherein the oil and the wax are a saturated and unsaturated fatty acid or long-chain, saturated, branched or cyclic hydrocarbons, the reactive diluent more preferably being trimethylpropane triacrylate.

10. System for performing the process for the anti-corrosion coating of a motor vehicle component as claimed in claim 1, the system comprising: an anti-corrosive, the anti-corrosive comprising: 0.1% to 10.0% by weight of at least one photoinitiator, 0.0% to 0.1% by weight of a photosensitizer, 1.0% to 40.0% by weight of a binder, 0% to 10.0% by weight of a reactive diluent, 0.0% to 10.0% by weight of an additive, 5.0% to 50.0% by weight of an oil, 1.0% to 20.0% by weight of a wax, 0.0% to 40.0% by weight of an anti-corrosion additive, and 0.0% to 20.0% by weight of a filler and/or a pigment, based on 100% by weight of the anti-corrosive, the coating having a thickness of 50 to 8000 μm, at least one radiation source for the irradiation of the anti-corrosive with radiation tailored to absorption by at least one photoinitiator and/or photosensitizer, wherein the anti-corrosive is at the end of irradiation solid or else solidifies in a time-adjusted manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0099] In the figures,

[0100] FIG. 1 shows a schematic representation of the different application methods,

[0101] FIG. 2 shows a schematic representation of the various exposure times of the samples,

[0102] FIGS. 3A-3F show the different run distances of samples as a function of irradiation intensity and wavelength,

[0103] FIGS. 4 to 6, 7A, and 7B show the run distance length as a function of wavelength and irradiation intensity at various irradiation times,

[0104] FIGS. 8 to 12 show the complete curing of a sample as a function of wavelength and irradiation intensity at various irradiation times,

[0105] FIGS. 13A-13B show the heat resistance of a sample (right) and of an unexposed reference “blank sample” (left), and

[0106] FIG. 14 shows a schematic representation of the relationships between the run distance and the various parameters.

EMBODIMENTS

[0107] FIG. 1 shows a schematic representation of the application methods for solvent CP systems, aqueous CP systems, and 100% CP systems according to the prior art. Also shown is the inventive cold-application method for a light-induced CP system. As mentioned, running zones and/or complex masking of components such as for example rocker panels are necessary when applying conventional CP systems. In addition, ovens are used to achieve complete evaporation of the medium or initiation of the DropStop. The schematic representation of the different application methods shows that the use of a light-induced cold-application method makes it possible to dispense with the abovementioned measures individually or in their entirety, allowing savings to be achieved on costs, energy, and time.

[0108] The light-induced CP system can accordingly be limited to the steps of light exposure (irradiation), application, optionally tilting of the component, and optionally allowing excess anti-corrosive to drip off. The component (body) can thus be supplied for assembly without the need for intermediate storage. As stated above, the light exposure and application steps can take place in any order. Thus, the anti-corrosive can be irradiated before and/or during application to a component, provided curing of the anti-corrosive takes place with a time delay. Alternatively, it is possible for the anti-corrosive to be applied to the component, with irradiation and curing carried out subsequently (immediately thereafter or with a time delay).

EXAMPLES

[0109] In the examples shown below all data in %, unless explicitly stated otherwise, refer to % by weight. In addition, unless explicitly stated otherwise, the sample (P_1b) having the composition described in Table 2 is assumed. Parameters once described likewise apply to further test parameters, unless explicitly stated otherwise. For example, the spacing or intensity of the radiation source is specified with reference to example 1. These parameters are the same in the other examples.

Example 1: Dependence on the Wavelength, Irradiation Time, and Irradiation Intensity

[0110] A sample (P_1b) is cured with each of three wavelengths (365 nm, 385 nm, and 405 nm) for different irradiation times (60 s, 10 s, 5 s, 2 s, 1 s, 0.5 s, and 0 s) and with each of two different irradiation intensities (100% and 15%) at a distance of 2.5 cm between the sample and the radiation source. Table 1 gives the intensity values of the various wavelengths. It has been shown that the intensity values, as described in the literature (H. Kuchling: Taschenbuch der Physik [Pocketbook of Physics], 17th edition, Fachbuchverlag Leipzig 2001), are proportional to the distance r according to the relationship 1/r.sup.2. The intensities in Table 1, which were determined at a distance of 4.5 cm, can on this basis be readily applied to the distance of 2.5 cm, as shown in the further examples.

TABLE-US-00001 TABLE 1 Intensity values of the different wavelengths at a distance of 4.5 cm between the measuring cell and the radiation source Wavelength Intensity Intensity in nm 15% in W 100% in W 365 0.82 5.31 385 1.14 6.91 405 1.11 6.83
The sample P_1b has the composition shown in Table 2. The sample may comprise further constituents of the anti-corrosive of the invention in the amounts listed. These additional constituents have been shown not to affect the properties shown below.

TABLE-US-00002 TABLE 2 Composition of the sample P_1b Amount used Name Material in % Omnirad α-Hydroxyketone/hydroxy- 4.8 184 cyclohexyl phenyl ketone Laromer PR Acrylate dissolved in 34.8 9052 trimethylpropane triacrylate AP 38-03 100% CP agent without DropStop 40 RME Saturated and unsaturated 20 fatty acids

[0111] FIG. 2 shows a schematic representation of the various exposure times of the samples including control. The samples and control are here not necessarily in two rows (FIGS. 3A-3E), but may also be in one row in a corresponding sequence (FIG. 3F).

[0112] 100 μl droplets are dripped onto a sheet steel (20 cm×50 cm) coated by cathodic dip painting (CDP) (for example a sheet steel coated with CathoGuard 800 or 900 (BASF SE)) and irradiated. After irradiation, the sheet is stood in an upright position. After 10 minutes, the run distance (=distance traveled by the sample on the sheet) is measured and also documented with a photograph. The sequence of the different exposure times is maintained here (see FIG. 2).

[0113] FIGS. 3A-3F show the different run distances of the droplets as a function of irradiation intensity (100% in FIGS. 3A, 3C, 3E; 15% in FIGS. 3B, 3D, 3F) and wavelength (365 nm in FIGS. 3A, 3B; 385 nm in FIGS. 3C, 3D; 405 nm in FIGS. 3E, 3F).

[0114] As expected, a shorter wavelength and longer exposure time achieve a shorter run distance and the irradiated droplet has higher strength (gel strength). At 365 nm and 100% irradiation intensity, all droplets solidify and only the unexposed reference has a run distance of 19 cm. Even the longest irradiation time of 60 s does not result in complete solidification (gelation) of the droplet at 405 nm and 15% intensity and instead a run distance of 6 cm is obtained.

[0115] Table 3 shows the run distance in cm as a function of wavelength, irradiation time, and irradiation intensity. The samples contain 4.8% Omnirad 184, 34.8% Laromer PR 9052, 20% RME, and 40% AP 38-03 (as per Table 2). In each case 100 μl of sample is applied in the form of a droplet to the CDP sheet and irradiated. The sheet is then stood in an upright position for 10 minutes. The mark.sup.1 indicates measurement according to the method specified herein. The mark.sup.2 refers to “oil running”, wherein a uniform run distance is not achieved.

TABLE-US-00003 TABLE 3 Run distance in cm as a function of wavelength, irradiation time, and irradiation intensity. Wave- Run distance.sup.1 in cm as a function length Intensity of irradiation time in nm in % 0 s 0.5 s 1 s 2 s 5 s 10 s 60 s 365 15 24 22 21 5 0 0 0 100 19 0 0 0 0 0 0 385 15 22 22 20 22 6.5 3.sup.2 4.5.sup.2 100 23 17 3 0 0 0 0 405 15 24 23 23 24 24 17 6 100 22 24 21.5 11.5 3 0 0

[0116] FIG. 4 shows the run distance in cm plotted against the wavelength and irradiation intensities for different irradiation times. Sample containing 4.8% Omnirad 184, 34.8% Laromer PR 9052, 20% RME, and 40% AP 38-03. 100 μl sample, irradiated, metal sheet stood in an upright position for 10 min.

[0117] FIG. 5 shows the run distance in cm plotted against the irradiation time at various wavelengths and different irradiation intensities. The sample contains 4.8% Omnirad 184, 34.8% Laromer PR 9052, 20% RME, and 40% AP 38-03 (as per Table 2). A droplet of in each case 100 μl of sample is applied to a metal sheet, irradiated, and the metal sheet is stood in an upright position for 10 min.

[0118] A correlation between run distance, wavelength, and irradiation time is evident: the longer the droplet is irradiated, the shorter the run distance (and the tougher the surface film and the deepening gelation brought about by the crosslinking reaction). And in addition: the higher the irradiation intensity, the shorter the run distance (FIGS. 3A-3F). The intensity of a system tailored to the wavelength has a greater effect on the run distance than on the wavelength itself, since with an irradiation time of 1 s and at 365 nm and 15% a run distance of 21 cm is obtained and at 385 nm and 100% the run distance is only 3 cm.

[0119] FIG. 6 shows the run distance for an irradiation intensity of 100% only. With the same irradiation time and intensity, the run distance is longer at lower light energy (longer wavelength). For example, the run distance at 1 s and 100% irradiation intensity is 3 cm long at 385 nm, but 21.5 cm long at 405 nm.

Example 2: Concentration Dependence

[0120] The concentration is another parameter with which the run distance can be controlled. As expected, a smaller proportion of reactive material (mixture of binder, photoinitiator and photosensitizer) results in less pronounced gelation of the droplet and thus in longer run distances.

[0121] Table 4 shows the run distances in cm as a function of wavelengths, irradiation times, and irradiation intensities. In each case 100 μl of sample is irradiated and the metal sheet is stood in an upright position for 10 min. Sample: P_1d (0.13% Omnirad 184, 6.53% Laromer PR 9052, 73.3% AP 38-03, and 20% RME). Sample: P_1e (0.02% Omnirad 184, 1.2% Laromer PR 9052, 78.7% AP 38-03, and 20% RME). The mark.sup.1 indicates measurement according to the method specified herein.

TABLE-US-00004 TABLE 4 Run distance in cm as a function of wavelength, irradiation time, and irradiation intensity. Run distance.sup.1 in cm as a function of Wavelength in Intensity in irradiation time in s Sample nm % 0 5 10 60 P_1d 365 100 15 3 2.5 0 405 15 15 8.5 6 2.5 P_1e 365 100 17 12.5 10.5 6.5

[0122] FIGS. 7A and 7B show the run distances of samples with an exposure time of: 60 s, 10 s, 5 s, and 0 s (from the left). FIG. 7A shows the run distances of sample P_1d (0.13% Omnirad 184, 6.5% Laromer PR 9052, 73.3% AP38-03, and 20% RME) at a wavelength of 405 nm with 100% intensity. FIG. 7B shows the run distance of sample P_1e (0.02% Omnirad 184, 1.2% Laromer PR 9052, 78.7% 38-03, and 20% RME) at a wavelength of 365 nm with 100% intensity. Thus in FIG. 7A the run distances are about 0.5 cm, 7 cm, 9 cm, and 15 cm, and in FIG. 7B the run distances are about 7.5 cm, 11 cm, 12.5 cm, and 16.5 cm.

[0123] With 0.13% Omnirad 184 and 6.53% Laromer PR 9052, the sample P_1d has a relatively low proportion of reactive material and can still be (at least partially) gelled at 405 nm and an intensity of 100% (see FIG. 7A).

[0124] At 365 nm and 100%, the run distance of sample P_1e (0.02% Omnirad 184 and 1.2% Laromer PR 9052) can be varied through exposure times of different length (see FIG. 7B).

[0125] This means that, even with a very low concentration of the reactive material (approx. 1%), it is possible to achieve a reduction in run distance (see FIG. 7B) through high light intensity (100%) and high light energy (wavelength: 365 nm).

Example 3: Complete Curing

[0126] Well test: 1 ml of a sample P1_b is pipetted into a well having a constant depth of 5000 μm and a volume of 1 ml and irradiated. The well is then stood in an upright position. It is observed whether the sample runs out of the well or develops a convexity.

[0127] Unirradiated reference: As soon as the well is stood in an upright position, the unirradiated sample material runs out of the well. The (unirradiated) material has very low viscosity and accordingly runs out of the well in liquid form (FIG. 8).

[0128] Irradiation of the sample at a wavelength of 405 nm for 10 s and an intensity of 15%: Irradiation with light having a wavelength of 405 nm, a light intensity of 15%, and an exposure time of 10 s is not sufficient to completely gel the material, with the result that it does not remain in the well after the well has been stood upright. A thin skin appears to form in the region of the interface layer exposed to radiation. However, this is not sufficient to hold back the unirradiated, underlying and therefore still liquid material (FIG. 9).

[0129] Irradiation of the sample at a wavelength of 365 nm for 10 s and an intensity of 15%: After irradiation with 365 nm and 15% for 10 s, the sample material does not run off as a result of being stood upright, but a clearly visible convexity develops. This indicates the presence of a superficial, highly flexible, and elastic layer that is evidently thicker than in the previous experiment (405 nm, 15%, 10 s). The convexity indicates incomplete gelation (FIG. 10).

[0130] Irradiation of the sample at a wavelength of 365 nm for 60 s and an intensity of 15%: The irradiation at 365 nm and 15% for 60 s is sufficient to solidify the entire material. After the well has been stood upright, no material runs out and no convexity is discernible (FIG. 11).

[0131] Irradiation of the sample at a wavelength of 365 nm for 10 s and an intensity of 100%: The irradiation at 365 nm and a light intensity of 100% for only 10 s is likewise sufficient to solidify all of the material in the well. Being stood upright neither causes running nor the development of a convexity (FIG. 12).

[0132] By irradiating at different wavelengths with varying intensities and irradiation times, the materials (sample P1_b) can be completely gelled for a layer thickness of 5000 μm. All of the variations in parameters mentioned thus far contribute to making the material drip-free.

Example 4: Heat Stability

[0133] The thermal load capacity is determined by the heat stability of a material. For this purpose, a defined wet film thickness is applied to a cold-rolled sheet steel with the aid of a film-drawing frame. With conventional CP materials, activation and seasoning to solidify the samples must be taken into account after application. To analyze the heat stability, some material is removed from the lower third of the metal sheet using a spatula. The lower edge is marked with a felt pen. The samples are then heated in an oven at defined temperatures and the run-off behavior under the influence of temperature is observed (FIG. 13).

[0134] To investigate the heat resistance of the light-induced crosslinking material, the material (sample P1_b) is applied to two metal sheets, in each case with a wet film thickness of 500 μm. The material is then irradiated for 10 s with a wavelength of 365 nm and a radiation intensity of 100%.

[0135] The heat resistance of the unexposed blank sample (FIG. 13A) and of the exposed sample (FIG. 13B) is examined in an oven at 95° C. In the case of the blank sample, running was not seen until reaching a temperature of 75° C., whereas the irradiated sample showed no tendency to run even at a temperature of 95° C. These results suggest that the irradiation immediately crosslinks the material. There are therefore no concerns about running from components, even at very high temperatures.

[0136] It is possible to control the run distance via parameters such as irradiation time, light energy, irradiation intensity, and proportion of reactive material, it being possible to use any mixtures of reactive materials that differ both in respect of the individual component as such and in the amount thereof.

[0137] Depending on the technical options (for example the radiation source), the parameters can be altered in order to adjust the run distance. If, for example, a radiation source delivers only low irradiation intensities, the run distance can be controlled by means of a longer irradiation time (see FIG. 14).

[0138] It has also been shown that the heat stability (layer thickness of 500 μm) is achieved immediately after irradiation (365 nm, 100% 10 s). This is due to the fact that the material does not require any post-crosslinking time. The material is accordingly drip-free and temperature-resistant immediately after application and subsequent irradiation.

[0139] It has moreover been demonstrated that solidification of thick layers of e.g. 5000 μm can be readily achieved with irradiation of sufficient intensity and with a sufficiently long irradiation time.

[0140] The disclosure further comprises embodiments as set out in the clauses shown below.

Clause 1. An anti-corrosive that is a cavity preservation agent, an agent for underbody protective coating, an agent for permanent protective coating for storage and transport, or an agent for temporary protective coating for storage and transport, the anti-corrosive being intended for the corrosion protection of a component, in particular of a motor vehicle part, wherein the anti-corrosive can be applied without additional heating, undergoes radiation-induced free radical and/or cationic crosslinking, preferably in thick layers, and has application-based, controllable reaction kinetics and an adjusted heat resistance.
Clause 2. An anti-corrosive, comprising or consisting of:

[0141] 0.1% to 10.0% by weight of at least one photoinitiator,

[0142] 0.0% to 0.1% by weight of a photosensitizer,

[0143] 1.0% to 40.0% by weight of a binder,

[0144] 0% to 10.0% by weight of a reactive diluent,

[0145] 0.1% to 10.0% by weight of an additive,

[0146] 5.0% to 50.0% by weight of an oil,

[0147] 1.0% to 20.0% by weight of a wax,

[0148] 1.0%, to 40.0% by weight of an anti-corrosion additive, and

[0149] 0.0% to 20.0% by weight of a filler and/or a pigment, based on 100% by weight of the anti-corrosive, the anti-corrosive including at least one photoinitiator, the photoinitiator and/or the photosensitizer being tailored to the absorption of radiation, wherein the anti-corrosive is at the end of irradiation solid or else solidifies in a time-adjusted manner.

Clause 3. The anti-corrosive according to clause 2, wherein at least one photoinitiator is selected from the group benzophenone, benzoyl ether, aminoketone, thioxanthone, acylphosphine oxide, sulfonium salt, ferrocenium salt, and iodonium salt.
Clause 4. The anti-corrosive according to either of clauses 2 or 3, wherein the binder is selected from the group consisting of an acrylate, for example a polyurethane acrylate, polyester acrylate or epoxy acrylate, unsaturated polyesters and thiol-ene system, vinyl ethers and heterocycles.
Clause 5. The anti-corrosive according to any of the clauses 2 to 4, wherein the anti-corrosive comprises 4.0% to 6.0% by weight of the at least one photoinitiator, 0.0% to 0.1% by weight of a photosensitizer, 32.0% to 37.0% by weight of a binder-reactive diluent mixture, and 18.0% to 22.0% by weight of an oil-wax mixture, preferably wherein the at least one photoinitiator is a hydroxy ketone and a hydroxycyclohexyl phenyl ketone, wherein the binder is an acrylate, wherein the oil and the wax are a saturated and unsaturated fatty acid or long-chain, saturated, branched or cyclic hydrocarbons, the reactive diluent more preferably being trimethylpropane triacrylate.
Clause 6. An anti-corrosion coating of a component according to any of the preceding clauses, wherein a heat resistance of the anti-corrosion coating can be adjusted and/or set.
Clause 7. A process for the anti-corrosion coating of a component, including or consisting of:

[0150] applying an anti-corrosive to the component, the anti-corrosive including at least one photoinitiator and optionally a photosensitizer,

[0151] irradiating the anti-corrosive with radiation tailored to absorption by the at least one photoinitiator and by any optional photosensitizer, wherein the anti-corrosive is at the end of irradiation solid or else solidifies in a time-adjusted manner.

Clause 8. The process for the anti-corrosion coating of a component according to clause 7, wherein the anti-corrosive at the end of irradiation remains solid and/or flowable for a period t of 5 minutes or longer and thereafter solidifies, even in thick layers, within the range up to 5000 μm.
Clause 9. The process according to either of clauses 7 to 8, wherein the viscosity of the flowable anti-corrosive at room temperature at the end of irradiation is 10.sup.1 mPa.Math.s to 10.sup.6 mPa.Math.s.
Clause 10. The process according to any of clauses 7 to 9, wherein 0.01 hours≤t≤2 hours.
Clause 11. The process according to any of clauses 7 to 10, wherein the application of an anti-corrosive to the component includes:

[0152] spraying an anti-corrosive into/onto the component and allowing the anti-corrosive to penetrate/run.

Clause 12. The process according to any of clauses 7 to 11, wherein the entire process takes place at a temperature of 30° C.
Clause 13. A system for the anti-corrosion coating of a component, including or consisting of:

[0153] an anti-corrosive, preferably an anti-corrosive as claimed in any of clauses 1 to 6, that is applied to the component, the anti-corrosive including at least one photoinitiator and/or photosensitizer,

[0154] at least one radiation source for the irradiation—which can take place before, during or after application and inside or outside the component—of the anti-corrosive with radiation tailored to absorption by at least one photoinitiator and/or photosensitizer, wherein the anti-corrosive is at the end of irradiation solid or else solidifies in a time-adjusted manner.

Clause 14. The system according to clause 13, wherein one or more of the following is adjustable: (i) a position L of the at least one radiation source in relation to the component, (ii) an intensity I of the radiation source, and (iii) a period t of irradiation of the component.
Clause 15. The anti-corrosive according to any of clauses 1 to 6, the process as claimed in any of clauses 7 to 12, or the system as defined in either of clauses 13 or 14, wherein the anti-corrosive is a cavity preservation agent, an agent for underbody protective coating, an agent for permanent protective coating for storage and transport, or an agent for temporary protective coating for storage and transport, the component preferably being a motor vehicle component.