EP2013294A1

EP2013294A1 - Uv-curable undercoat

Info

Publication number: EP2013294A1
Application number: EP07728610A
Authority: EP
Inventors: Thomas Rentschler; Horst Van Beek; Reinhold KÖPP
Original assignee: Sachtleben Chemie GmbH
Current assignee: Venator Germany GmbH
Priority date: 2006-04-27
Filing date: 2007-04-27
Publication date: 2009-01-14
Also published as: BRPI0710865A2; CA2650477C; EP2013293A1; US20100291327A1; CA2650476A1; DE102007020468A1; BRPI0710795A2; WO2007125098A1; US8114513B2; CA2650476C; CA2650477A1; US20090169783A1; WO2007125099A1

Abstract

The invention relates to a UV-curable undercoat and to the production and use thereof.

Description

UV-curable primer

The present invention is a UV-curable primer, their preparation and the use of this primer.

In particular, the present invention is a UV-curable primer for coil coating containing finely divided barium sulfate, the preparation of this primer and their use.

Coil coating is understood to mean a special form of roller coating of cold-rolled metal strip. It is a continuous process with throughput speeds up to 250 m / min. Under these conditions it is necessary that a primer has a very good course and hardens quickly, so that a coil coating plant can be kept as short as possible. Therefore, UV curing is preferable to thermal curing. Since the metal strip is rolled after processing, the primer must be highly elastic.

The primer is the first layer of a multi-layer system and serves to impart adhesion of the entire layer structure. In the case of coil coating, it should also offer the highest possible corrosion protection for the metal strip and the sheets produced therefrom. Also, the primer should be wholly or partially free of chromate-containing anticorrosive pigments; these are ecologically questionable. In addition, it is desirable to be able to dispense with the organic pretreatment of the metal strip.

Prior art in the field of coil coating primers are in particular primers based on acrylates, in turn, in particular primers based on epoxy acrylates, urethane acrylates or mixtures thereof. Thus, for example, a known coil coating primer consists essentially of 90 parts of acrylate binder, 5 parts of adhesion promoter Ebecryl 171 and 5 parts of UV initiator Additol CPK. Primers based on these and similar compositions have as disadvantages low corrosion protection and adhesion. Probably due to the high Elasticity of the coatings with this and similar starting formulations, which allow a penetration of moisture and salts to the metal, the corrosion protection is bad. However, high elasticity is extremely important in the coil coating area because the metal strip is bent, rolled, and bent. The primers must understand these mechanical stresses without tearing.

Also known for a long time are hardenable compositions which contain finely divided particles, in particular nanoparticles based on silica or aluminum oxide. For example, see patent applications EP-A-1 179 575, WO-A-00/35599, WO-A-99/52964, WO-A-99/54412, DE-A-197 26 829 or DE-A-195 40,623. They are used in particular for the production of highly scratch-resistant coatings whose chemical resistance leaves something to be desired.

DE-A-10 2004 010 201 discloses curable compositions containing deagglomerated barium sulfate containing at least one dispersant and at least one crystallization inhibitor. These curable compositions have high scratch resistance and improved chemical resistance. However, the compositions disclosed in DE-A-10 2004 010 201, which can be used in particular in paints, are thermally cured.

WO-A-02/26852 discloses UV-curable coating materials containing barium sulfate without, however, disclosing anything about the particle size of the barium sulfate. These coating materials are used, inter alia, for the production of clearcoats, or color and effect solid-color topcoats, basecoats and multicoat coats in coil coating. However, WO-A-02/26852 does not disclose a primer.

A particle size of barium sulfate which can be used in UV-curable coatings, namely below 200 nm, is disclosed in DE-A-4133290. However, DE-A-4133290 does not disclose primer and the particle size of barium sulfate is only roughly outlined. A use of the clearcoat in coil coating disclosed in DE-A-4133290 is not disclosed. A UV-curable primer, which has a very good course, is highly elastic, offers very good corrosion protection and is completely or partially free of chromate-containing anticorrosive pigments and makes an organic pretreatment of the metal strip superfluous, can not be found in the prior art.

The object of the present invention is to remedy the deficiency in the prior art.

In particular, the object of the present invention is to provide a UV-curable primer for coil coating, which ensures an improved course, which can completely or partially dispense with chromate-containing anticorrosive pigments, in the use of which the organic pretreatment of the substrate can be dispensed with, which causes an improved corrosion protection and / or has a high elasticity.

According to the invention, the objects are surprisingly achieved by the features of the main claim. Preferred embodiments can be found in the subclaims.

In particular, the object is achieved by a UV-curable primer, the finely divided barium sulfate having an average particle size of 550 to 950 nm, preferably from 600 to 800 nm, more preferably from 650 to 750 nm or an average particle size of 10 to 120 nm, preferably from 20 to 100 nm, more preferably from 30 to 80 nm, most preferably from 40 to 60 nm. This is surprising since barium sulfate is considered to be chemically inert.

In connection with the barium sulfate used according to the invention mean particle size always median of the particle diameter. The median can be determined, for example, by laser diffraction.

Such a primer is not known from the prior art. - A -

The primer according to the invention completely surprisingly significantly improves the corrosion protection for the metal strip and the sheets produced therefrom, without the elastic properties of the primer suffering therefrom. So far, it has not been possible to improve both properties simultaneously to this extent. Hereinafter, the surface to be treated with the primer, be it the metal strip, the sheets made therefrom or any other surface that can be treated with the primer, will be called substrate for short.

In the case of the primer according to the invention, it is possible to dispense with anticorrosive pigments or to at least reduce their use, without this leading to a reduction of the corrosion protection.

In addition, can be dispensed with when using the primer according to the invention on the organic pretreatment of the substrate.

The primer according to the invention contains preferably 40 to 80% by weight of binder, 20 to 45% by weight of reactive diluent, 2 to 10% by weight of UV initiators, 1 to 25% by weight, preferably 2 to 15% by weight. , Particularly preferably 5 to 12 wt .-% barium sulfate, 0 to 10 wt .-% additives, 0 to 15 wt .-% coloring pigments and 0 to 15 wt .-% anticorrosive pigments.

In the barium sulfate used in the primer according to the invention, in contrast to the barium sulfates disclosed in DE-A-10 2004 010 201, it is possible to dispense with the use of dispersants and crystallization inhibitors.

The barium sulfate in the primer according to the invention has an average particle size of 550 to 950 nm, preferably from 600 to 800 nm, particularly preferably from 650 to 750 nm. An example of such barium sulfate is the product SACHTLEBEN micro from Sachtleben Chemie GmbH. In an alternative embodiment of the invention, the barium sulfate has an average particle size of 10 to 120 nm, preferably from 20 to 100 nm, more preferably from 30 to 80 nm, most preferably from 40 to 60 nm. An example of such barium sulfate is the product SACHTOPERSE HU-N from Sachtleben Chemie GmbH.

The barium sulfate according to the invention is preferably a so-called BLANC FIXE product. This is produced synthetically by a precipitation process. This impurities are largely eliminated, and set a narrow, defined particle size and particle size distribution. The precipitated barium sulfate is washed, dried and ground. The grinding can be done by pin mills or jet milling. The barium sulfate according to the invention may be coated with an organic substance which acts as a grinding aid during production and as a dispersing aid in the coating. The organic substances used are typically TMP (trimethylolpropane), TME (trimethylolethane), TEA (triethyleneamine) or polyacrylates. Alternatively, the barium sulfate of the invention may be derived from natural raw materials worked up by prior art processes, for example, purification and milling.

According to the invention, the binders used are preferably compounds having a UV-crosslinking acrylate or methacrylate function or a plurality of UV-crosslinking acrylate or methacrylate functions, preferably selected from epoxide acrylates, polyurethane acrylates, melamine acrylates, polyester acrylates, polyether acrylates, silicone acrylates, epoxy methacrylates,

Polyurethane methacrylates, melamine methacrylates, polyester methacrylates, polyether methacrylates, silicone methacrylates, unsaturated acrylic, methacrylic or polyester resins or mixtures of at least two of these compounds.

Preferred reactive diluents according to the invention are styrene, mono-, di-, tri- or tetra-functional acrylates or mono-, di-, tri- or tetrafunctional methacrylates or

Mixtures of at least two of these used. Reactive thinner are

Diluent for reducing the viscosity of the binder and are in the film formation by chemical reaction part of the binder, that is, they polymerize with. Most are structurally related monomers of the binder. According to the invention, the UV initiator is preferably selected from benzophenone, benzoin ether, benzil, benzil ketal, α-hydroxyalkylphenone, α-aminoalkylphenone, benzoylphosphine oxide or derivatives thereof. Mixtures of two or more of these compounds are also often used to optimize reactivity and depth cure. The use of the UV initiator is matched to the binder.

According to the invention, adhesion promoters are preferably used as additives.

The primer according to the invention may contain inorganic or organic colorants for coloring and covering the substrate, for example white pigments, colored pigments, black pigments or dyes. For primers intended to give transparent coatings, no colorant is added.

According to the invention, the anticorrosion pigments which can be used in the primer according to the invention are preferably organic inhibitors or inorganic anticorrosive pigments, for example metal phosphates, phosphosilicates or ion exchange pigments, or mixtures of these compounds.

Advantageously, the UV-curable primer according to the invention can also be prepared by adding and incorporating barium sulfate according to the invention into a commercially available UV-curable primer by methods according to the prior art.

The primer according to the invention is preferably used for coil coating in order to protect the substrate from corrosion and / or to achieve a uniform course of the coating on the substrate.

Further uses according to the invention are can coating and container coating. Again, the primer according to the invention is used to protect the respective substrate from corrosion and / or to achieve a uniform course of the coating on the substrate. Typical substrates on which the primer according to the invention is used consist for example of steel or aluminum, again for example in the form of metal sheets. The steel can be used without metallic pre-finishing or also with electrolytic galvanizing or hot-dip finishing, for example with zinc.

Furthermore, the substrates of steel or aluminum can be pretreated with organic chemicals for corrosion protection. However, according to the invention it is also possible to dispense with the pretreatment with organic chemicals in the substrates.

After the UV-curable primer according to the invention has been applied and completely cured with UV light, it may optionally be coated with a thermally curable topcoat, for example based on a polyester, polyester-melamine, polyurethane or PVDF binder system. The coating is preferably applied by roller or casting application method.

The UV-curable primer according to the invention can also be used, for example, for coating flat objects such as wood panels, fibreboards such as MDF (medium-density fiberboard), laminates, paper and / or films.

Typical applications of the substrates coated with the UV-curable composition according to the invention are, for example, add-on parts for roofs and facades, partition walls, ceiling elements, shop fittings, cabinets, shelves, domestic appliances, machine panels, doors, gates, lights, wheel rims, vehicle body parts and caravans.

The subject of the present invention is in detail:

a UV-curable primer containing barium sulfate;

a UV-curable primer containing barium sulfate, which is a mixture, preferably a dispersion; a UV-curable primer containing barium sulfate, the barium sulfate having an average particle size of from 10 to 120 nm, preferably from 20 to 100 nm, more preferably from 30 to 80 nm, most preferably from 40 to 60 nm;

a UV-curable primer containing barium sulfate, the barium sulfate having an average particle size of from 550 to 950 nm, preferably from 600 to 800 nm, more preferably from 650 to 750 nm;

a UV-curable primer, 1 to 25 wt .-%, preferably 2 to 15 wt .-%, particularly preferably 5 to 12 wt .-% barium sulfate;

a UV-curable primer containing barium sulfate and also binders, UV initiator (s), reactive diluent, optionally additive (s), optionally coloring pigments and / or optionally corrosion inhibitors;

a UV-curable primer containing 40 to 80% by weight of binder, 20 to 45% by weight of reactive diluent, 2 to 10% by weight of UV initiators, 1 to 25% by weight, preferably 2 to 15% by weight. %, more preferably 5 to 12% by weight of barium sulfate, 0 to 10% by weight of additives, 0 to 15% by weight of coloring pigments and 0 to 15% by weight of anti-corrosive pigments;

a UV-curable primer which is free of chromate-containing anticorrosive pigments;

a UV-curable primer, wherein binders with one or more UV-crosslinking acrylate or methacrylate functions are used, preferably selected from epoxy acrylates, polyurethane acrylates, melamine acrylates, polyester acrylates, polyether acrylates, silicone acrylates, epoxy methacrylates, polyurethane methacrylates, melamine methacrylates, polyester methacrylates, polyether methacrylates, Silicone methacrylates, unsaturated acrylic, methacrylic or polyester resins or mixtures of two or more of these compounds; a UV-curable primer, wherein the reactive diluents used are styrene, mono-, di-, tri- or tetra-functional acrylates or mono-, di-, tri- or tetrafunctional methacrylates or mixtures of two or more of these;

a UV-curable primer, wherein the UV initiator is selected from benzophenone, benzoin ethers, benzil, benzinketal, α-hydroxyalkylphenone, α-aminoalkylphenone, benzoylphosphine oxide, or their derivatives or mixtures of at least two or compounds and / or their derivatives;

a UV-curable primer, it being possible to use adhesion promoters as additives;

a UV-curable primer, it being possible to use inorganic and / or organic colorants for coloring and covering the substrate, for example white pigments, colored pigments, black pigments and / or dyes;

a UV-curable primer, wherein the anticorrosive pigments are organic inhibitors or inorganic anticorrosive pigments, for example metal phosphates, phosphosilicates or ion exchange pigments, or mixtures of these compounds;

a process for the preparation of the primer according to the invention, wherein a commercially available UV-curable primer barium sulfate of the invention

Particle size is added and incorporated by methods according to the prior art;

a process for the preparation of the primer according to the invention wherein barium sulfate of the particle size according to the invention is added and incorporated by methods according to the prior art to a UV-curable primer based on acrylates, preferably epoxy acrylates, urethane acrylates or mixtures of these acrylates; a method for coating substrates with the primer according to the invention, wherein a UV-curable primer based on acrylates, preferably epoxy acrylates, urethane acrylates or mixtures of these acrylates barium sulfate particle size of the invention added by methods according to the prior art, incorporated and the mixture applied to the substrate and UV cured;

a process for coating substrates with the primer according to the invention, wherein barium sulfate of the particle size according to the invention is added to a commercially available UV-curable primer by methods according to the prior art, and the mixture is applied to the substrate and UV-cured;

the use of the primer according to the invention for coating metallic surfaces, preferably of steel or aluminum, more preferably of plane metallic surfaces;

the use of the primer according to the invention for coil coating, can coating and / or container coating;

the use of the primer according to the invention for coating flat objects, preferably wood panels, fibreboards such as MDF, laminates, paper and / or foils;

the use of the primer according to the invention for the coating of substrates, wherein the substrate is pretreated with inorganic chemicals for corrosion protection, preferably electrolytically or by melting dipping refined, particularly preferably with zinc and / or zinc compounds electrolytically or by hot dipping;

the use of the primer according to the invention for coating substrates, wherein the substrate is pretreated with organic chemicals for corrosion protection; the use of the primer according to the invention for coating substrates, wherein pretreatment of the substrate for corrosion protection is dispensed with;

Use of the substrates coated with the primer according to the invention and / or by the process according to the invention in construction, in particular as add-on parts for roofs and facades, partitions, ceiling elements, shop fittings, cabinets, shelves, domestic appliances, machine panels, doors, gates, lights, wheel rims, as attachments of car bodies and caravans.

The invention is further illustrated by the following examples, without limiting them:

Example 1: General formulations for primers

Table 1: General formulations for compositions; all contents are given in weight percent (wt.%)

Recipe 1 2

Acrylate binder 70 63

Monomers 20 18

Adhesive 5 4,5

UV initiator 5 4,5

Barium sulfate 0 10

The formulation ingredients are predispersed on the dissolver for 10 minutes and then dispersed on the Skandex or with a bead mill. In the laboratory, 150 g preparation of the composition are used in a 500 ml chewing gum bottle with 500 g glass beads with a size of 2 mm. Then the dispersing fineness of the Hegmann wedge is checked. The dispersion is continued until the desired fineness is achieved, in the present case after 3 hours Skandex a fineness less than or equal to 6 microns. A corresponding comparative sample (formulation 1) contains no barium sulfate.

Application and testing:

The segregated from the beads approach the primer is applied with a spiral knife on freshly cleaned sheets (non-galvanized steel) and irradiated with the UV curing device (Eltosh, 2 passes at 120 W / cm ² , 3 m / min).

With a 30 μm spiral blade results in a layer thickness of 13 microns. The layer formed on the substrate based on formulation 2 on the substrate exhibits a smoother surface and better flow than the layer formed on the substrate based on formulation 1. In the adhesive strength and elasticity, no differences between the two coatings can be seen; Both coatings behave very well in terms of adhesive strength and elasticity (ball impact, rapid deformation). In the elasticity test (sagging), the layer produced with the primer based on formulation 1 shows slightly better elasticity. The layer produced with the primer based on formulation 2, on the other hand, exhibits improved hardness (pendulum damping).

However, there are significant advantages in terms of corrosion for the layer produced on the basis of the recipe 2.

The corrosion test is repeated at a layer thickness of 50 μm. The results of the corrosion tests are shown in Table 2 below. The degree of rusting is assessed in accordance with DIN 53210, the degree of blistering in accordance with DIN 53209:

Table 2: Mechanical properties of the coatings produced with primers based on formulations 1 and 2

Recipe 1 2

Cross-hatch (Gt) O O

Erichsen cupping [mm] 9.5 8.7

Pendulum hardness [sec] 85 105

Ball stroke inverse> 200> 200

Ball impact revers> 200> 200

Salt spray test 50 h, 13 μm layer thickness, untreated steel:

Infiltration (mm) 2 2

Rust grade note 5 1

Bubble level m5g2 m2g2

Salt spray test 400 h, 50 μm layer thickness, untreated steel:

Infiltration (mm) 14 7

Rust grade grade 4 0 to 1

Bubble level m4g3 m1 g2 Fig. 1 a) shows the result of the 50-hour salt spray test at 13 μm layer thickness with the primer based on the recipe 1 generated layer, Fig. 1 b) shows the result of the 50 hours salt spray test at 13 micron layer thickness with the primer based on the recipe 2 generated layer.

Fig. 2 a) shows the result of the 400 hours salt spray test at 50 μm layer thickness with the primer based on the recipe 1 generated layer, Fig. 2 b) shows the result of the 400 hours salt spray test at 50 micron layer thickness with the primer based on the recipe 2 generated layer.

Example 2: Formulations based on epoxy acrylate

Table 3 shows formulations for primers based on epoxy acrylate, Ebecryl EB 3213 (Cytec), 75%, the content of barium sulfate is set between 0 and 15%. The mean particle size of the barium sulfate is 50 nm. DPGDA (dipropylene glycol diacrylate) and HDDA (hexanediol diacrylate) are reactive diluents; Ebecryl 171 (Cytec) is a coupling agent, HDMAP (2-hydroxy-2-methylpropiophenone) is a radical photoinitiator. All contents are given in weight percent (wt.%).

Table 3: Formulations based on epoxy acrylate

Recipe 3 4 5 6 7

Ebecryl EB 3213, 75% 56,00 54,90 53,20 50,40 47,60

DPGDA 25,00 24,50 23,75 22,50 21, 25

HDDA 9,00 8,80 8,55 8,10 7,65

EbecryM 71 5,00 4,90 4,75 4,50 4,25

Additol HDMAP 5.00 4.90 4.75 4.50 4.25

Barium sulfate 0 2 5 10 15

A 10 μm thick layer is produced on untreated steel sheets analogously to the method described in Example 1.

Table 4 shows the mechanical properties of the layers produced with the formulations listed in Table 3:

Table 4: Mechanical properties of the layers produced with the primers based on formulas 3 to 7

Recipe 3 4 5 6 7

Crosscut GT 4 4 3 1 O

Pendulum hardness [sec.] 189 198 206 209 207

Deepening [mm] 5.2 5.2 5.2 5.3 5.4

Ball stroke inverse 1 10 1 10 100 100 95

Ball impact reverse <10 <10 <10 <10 <10

3 shows the results of the corrosion protection test after 100 hours of corrosion test on untreated steel at a layer thickness of 10 μm: FIG. 3 a) Formulation 3; Fig. 3 b) recipe 4; Fig. 3 c) recipe 5; Fig. 3 d) recipe 6; Fig. 3 e) recipe 7th

4 shows the results of the corrosion protection test after 150 hours corrosion test on untreated steel at a layer thickness of 10 μm: FIG. 4 a) Formulation 3; FIG. Fig. 4 b) recipe 4; Fig. 4c) recipe 5; Fig. 4 d) recipe 6; Fig. 4 e) Recipe 7. The evaluation of the experiment shows that the use of the primers according to the invention improves the mechanical properties and the corrosion protection of the substrates coated therewith as follows:

- With increasing content of barium sulfate, the cross-cut of Gt 4 = poorly improves to Gt 0 = very good. This means that the adhesion of the layer produced according to the invention to the substrate is continuously improved;

- The pendulum damping increases slightly with the barium sulfate concentration. That means the layer gets a little harder. The UV curing process was not adversely affected; the introduced solid thus does not reduce the crosslinking of the binder;

- The Erichsen depression remains constant even with the addition of barium sulfate, that is, the elasticity of the layer is not changed;

As can be seen from FIGS. 3 and 4, the corrosion protection is significantly improved with increasing content of barium sulfate.

Example 3: Formulations for coating compositions based on urethane acrylate

Table 5 shows formulations for primers based on urethane acrylate, Ebecryl EB 8307 (Cytec), 70%. The content of barium sulfate is adjusted to 0 and 10%. The mean particle size of the barium sulfate is 50 nm. All contents are given in percent by weight (% by weight). Table 5: Urethane acrylate primer formulations

Recipe 8 9

Ebecryl EB 8307, 70% 56,00 50,40

DPGDA 25.00 22,50

HDDA 9.00 8.10

Ebecryl 171 5.00 4.50

Additol HDMAP 5,00 4,50

Barium sulfate 0 10

Analogously to the method described in Example 1, a 10 μm thick layer is produced on untreated steel sheets.

Table 6 shows the mechanical properties of the layers made with primers based on the formulations listed in Table 5:

Table 6: Mechanical properties of the layers produced with formulations 8 and 9:

Recipe 8 9

Crosshatch GT O O

Pendulum hardness [sec.] 76 80

Deepening [mm] 8,2 8,3

Ball stroke inverse> 200> 200

Ball impact revers> 200> 200

5 shows the results of the corrosion protection test after 100 hours of corrosion test on untreated steel at a layer thickness of 10 μm: FIG. 5 a) Formulation 8; Fig. 5 b) recipe 9th

6 shows the results of the corrosion protection test after 150 hours corrosion test on untreated steel at a layer thickness of 10 μm: FIG. 6 a) Formulation 8; Fig. 6 b) recipe 9th

The evaluation of the experiment shows that the use of the primers according to the invention improves the mechanical properties and the corrosion protection of the substrates coated therewith as follows:

- The cross-hatch in the experiment with the recipe 9 is as well as in the experiment with the recipe 8 with Gt 0 = very good; this means that the adhesion of the primer according to the invention to the substrate is excellent and is not adversely affected by the addition of barium sulfate; - all other mechanical data such as pendulum damping, Erichsen depression, ball impact remain unchanged with the addition of barium sulfate; the very high elasticity is recognizable by the high depth values and the low pendulum hardness; The very good adhesion is also reflected in the ball impact.

As can be seen from FIGS. 5 and 6, the corrosion protection is significantly improved by the use of barium sulfate.

Example 4: Formulation based on recipe 1 on galvanized steel

A formulation 10 based on formulation 1 is prepared by adding 5% by weight of barium sulfate analogously to the method described in example 1. The average particle size of the barium sulfate is 50 nm. Similarly as in Example 1, a 10 μm thick layer is produced without barium sulfate (formulation 1) and with barium sulfate (formulation 10) on galvanized steel sheets. The coatings are then scribed lengthwise to simulate damage.

FIG. 7 shows the results of the corrosion protection test after 150 hours of corrosion test on galvanized steel at a layer thickness of 10 μm: FIG. 7 a) Formulation 1; FIG. Fig. 7 b) recipe 10th

The evaluation of the experiment shows that the primers according to the invention significantly reduce infiltration at the scribe.

Example 5: Combination of a UV-curable primer formulation with 10% by weight of an active anticorrosive pigment

Table 7: Formulations based on Laromer binder (BASF) with 10% by weight of an active anticorrosive pigment, all contents in% by weight

Recipe 1 1 1 1 1 1 1 1 1 1

Variant reference (a) (b) (C) (d)

Laromer UA9033 V 38, 13 36,00 33,90 31,77 29,65

Laromer PA 9039 V 8,13 7,68 7,22 6,77 6,32

Laromer TBCH 30.80 29.09 27.38 25.67 23.96

Byk 020 0.20 0.19 0.18 0.17 0.16

Shieldex C 303 10.00 10.00 10.00 10.00 10.00

Irgacure 184 8,12 7,68 7,22 6,77 6,32

Genocure MBF 4.62 4.36 4.10 3.85 3.59

Barium sulfate 0 5.00 10.00 15.00 20.00

In another UV-curable primer formulation (formulation 1 1, reference) with Laromer binders and monomer (both Fa. BASF) is barium sulfate of different particle size with varying proportions of 5, 10, 15 and 20 wt .-% (Variants (a) - (d)) is dispersed with a bead mill. This formulation also contains, as a constant constituent, 10% by weight of Shieldex C 303 (Grace) as an active anticorrosion pigment. Untreated steel sheets are coated 10 μm thick and tested for 75 hours in the salt spray test. The results show the following figures, in the respective representation 5 wt .-% barium sulfate above left (a), 10 wt .-% barium sulfate top right (b), 15 wt .-% barium sulfate bottom left (c), 20 wt .-% barium sulfate bottom right (cl):

Fig. 8: Recipe 1 1, reference, only Shieldex;

Fig. 9: barium sulfate with 50 nm mean particle size; Fig. 10: Barium sulfate with 500 nm average particle size;

Fig. 1 1: barium sulfate with 700 nm average particle size;

Fig. 12: barium sulfate with 1000 nm mean particle size;

The figures show that the use of barium sulfate improves corrosion protection. As the content of barium sulfate increases, the protective effect improves. A barium sulfate having a mean particle size of 700 nm exhibits a greater effect than one having an average particle size of 1000 nm or 500 nm. A barium sulfate having an average particle size of 50 nm exhibits a greater effect than one having an average particle size of 1000 nm or 500 nm.

Example 6 Combination of a UV-Curable Primer Formulation with 5% by Weight of an Active Corrosion Protection Pigment

Table 8: formulations for primers based on Laromer binder (BASF) with 5% by weight of an active anticorrosive pigment, all contents in% by weight

Recipe 12

Laromer UA9033 V 36.00

Laromer PA 9039 V 7.68

Laromer TBCH 29.09

Byk 020 0.19

Shieldex C 303 5.00

Irgacure 184 7.68

Genocure MBF 4.36

Barium sulfate 10

In a UV-curable primer formulation (recipe 12) with Laromer binders and monomer (both Fa. BASF) barium sulfate of different particle size, each with 10 wt .-% is dispersed with a bead mill. This formulation contains as constant constituent 5% by weight of Shieldex C 303 (Grace) as an active anticorrosive pigment. Untreated steel sheets are coated 10 μm thick and tested in the salt spray test for 75 hours:

Fig. 13: Formulation 12 with barium sulfate with 700 nm average particle size; Fig. 14: Formulation 12 with barium sulfate with 500 nm average particle size. Example 6 confirms the result obtained in Example that the use of barium sulfate having an average particle size of 700 nm is more advantageous than the use of barium sulfate having an average particle size of 500 nm.

Example 7: UV-curable primer formulation without active anticorrosive pigment

Table 9: Formulations based on Laromer binder (BASF) without active anticorrosive pigment, all contents in% by weight

Recipe 13

Laromer UA9033 V 38, 13

Laromer PA 9039 V 8,13

Laromer TBCH 30.80

Byk 020 0,20

Shieldex C 303 0

Irgacure 184 8,12

Genocure MBF 4.62

Barium sulfate 10

In a UV-curable primer formulation (recipe 13) with Laromer binders and monomer (both Fa. BASF) barium sulfate of different particle size, each with 10 wt .-% is dispersed with a bead mill. This recipe contains no active anti-corrosive pigment. Untreated steel sheets are coated 10 μm thick and tested in the salt spray test for 75 hours: Fig. 15: Formulation 13 with barium sulfate with 700 nm average particle size; Fig. 16: Formulation 13 with barium sulfate with 500 nm average particle size.

The experiment shows that the anticorrosion effect in the binder formulation used is due solely to the use of barium sulfate.

Example 8: Different particle sizes of barium sulfate

Formulations based on the formulations of Example 2 were added with the addition of 5 wt .-% (Formulation 5, in the figures (a)), 10 wt .-% (Formulation 6, in the Figures (b)) and 15 % By weight (recipe 7, in the figures (c) each) of different barium sulfates prepared analogously to the process described in Example 2. The mean particle size of the barium sulfate varied from 50 nm to 1000 nm. Like Example 2, a 10 μm thick layer was produced on untreated steel sheets. Figs. 17 to 22 show the results of the corrosion protection test after 100 hours of corrosion test.

Fig. 17: reference without barium sulfate (formulation 3); Fig. 18: barium sulfate with 50 nm mean particle size; Fig. 19: barium sulfate with 200 nm mean particle size; Fig. 20: barium sulfate with 500 nm mean particle size; Fig. 21: barium sulfate with 700 nm mean particle size; Fig. 22: Barium sulfate with 1000 nm mean particle size.

The evaluation of the experiment shows that the primers according to the invention are particularly advantageous in corrosion protection when the barium sulphates used have particle sizes in ranges which are significantly smaller than 200 nm or lie between 500 nm and 1000 nm.

Claims

claims

1 . UV-curable primer, characterized in that it contains barium sulfate having an average particle size of 550 to 950 nm, preferably from 600 to 800 nm, more preferably from 650 to 750 nm.

2. UV-curable primer according to claim 1, characterized in that it contains binders, UV initiator (s), reactive diluents, optionally additive (s), optionally coloring pigments and / or optionally corrosion inhibitors.

3. UV-curable primer according to claim 1 or 2, characterized in that it contains 40 to 80 wt .-% binder, 20 to 45 wt .-% reactive diluents, 2 to

10% by weight of UV initiators, 1 to 25% by weight, preferably 2 to 15% by weight, particularly preferably 5 to 12% by weight of barium sulfate, 0 to 10% by weight of additives, 0 to 15% by weight % coloring pigments and 0 to 15 wt .-% anticorrosive pigments contains.

4. UV-curable primer according to at least one of claims 1 to 3, characterized in that are used as binders compounds having one or more UV-crosslinking acrylate or methacrylate functions, preferably selected from epoxy acrylates, polyurethane acrylates, melamine acrylates, polyester acrylates, polyether acrylates, silicone acrylates , Epoxy methacrylates, polyurethane methacrylates, melamine methacrylates,

Polyester methacrylates, polyether methacrylates, silicone methacrylates, unsaturated acrylic, methacrylic or polyester resins or mixtures of two or more of these compounds.

5. UV-curable primer according to at least one of claims 1 to 4, characterized in that as reactive diluent styrene, mono-, di-, tri- or tetrafunctional acrylates or mono-, di-, tri- or tetrafunctional methacrylates or mixtures of two or more of these are used.

6. UV-curable primer according to at least one of claims 1 to 5, characterized in that the UV initiator is selected from benzophenone, benzoin ethers, benzil, Benzinketale, α-hydroxyalkylphenol, α-aminoalkylphenone, Benzoylphosphinoxide, or derivatives thereof or mixtures two or more of these compounds and / or their derivatives.

7. UV-curable primer according to at least one of claims 1 to 6, characterized in that are used as additives adhesion improvers.

8. UV-curable primer according to at least one of claims 1 to 7, characterized in that for coloring and covering the substrate inorganic and / or organic colorants are used, preferably

White pigments, colored pigments, black pigments and / or dyes.

9. A UV-curable primer according to at least one of claims 1 to 8, characterized in that the anticorrosive pigments are organic inhibitors or inorganic anticorrosive pigments, for example metal phosphates, phosphosilicates or ion exchange pigments, or mixtures of these compounds.

10. A process for producing a UV-curable primer according to at least one of claims 1 to 9, characterized in that coating compositions based on acrylates, preferably epoxy acrylates, urethane acrylates or mixtures of these acrylates,

Barium sulfate having an average particle size of 550 to 950 nm, preferably from 600 to 800 nm, more preferably from 650 to 750 nm added and incorporated by methods according to the prior art.

1 1. A process for producing a UV-curable primer according to at least one of claims 1 to 9, characterized in that commercially available

Coating compositions barium sulfate having an average particle size of 550 to 950 nm, preferably from 600 to 800 nm, more preferably from 650 to 750 nm is added.

12. UV-curable primer, obtainable according to claim 10 or 11.

13. A method for coating surfaces with a UV-curable primer according to at least one of claims 1 to 9 or 12, characterized in that the primer is applied by methods according to the prior art on the surface of the substrate and UV-cured.

14. The method according to claim 13 for the coating of metallic surfaces, preferably of steel or aluminum, more preferably of flat surfaces made of steel or aluminum.

15. Use of the UV-curable primer according to at least one of claims 1 to 9 or 12 coated substrates in construction, preferably as

Attachments for roofs and facades, partitions, ceiling panels, for shop fittings, cabinets, shelves, appliances, machine panels, doors, gates, lights, wheel rims, as attachments of car bodies and caravans.

16. Use of a composition according to at least one of claims 1 to 9 or 12 for coil coating, can coating and / or container coating.

17. Use according to claim 15 or 16, characterized in that the substrate pretreated with inorganic chemicals for corrosion protection, preferably electrolytic or refined by hot dipping, more preferably with zinc and / or zinc compounds electrolytically or by

Melting is refined.

18. Use of a according to at least one of claims 1 to 9 or 12 for the coating of flat objects, preferably wood panels, fibreboard such as MDF, laminate plates, paper and / or films.

19. Use according to at least one of claims 15 to 18, characterized in that the substrate is pretreated with organic chemicals for corrosion protection.