AQUEOUS COATING COMPOSITION AND USE THEREOF

Abstract

A coating composition for producing a coating with an adjustable coefficient of friction.

Claims

1. Aqueous coating composition for producing a coating with an adjustable coefficient of friction, the coating composition comprising: an organic binding agent, wherein the binding agent comprises a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid; and a lubricant.

2. The coating composition according to claim 1, wherein the at least one unsaturated hydrocarbon is selected from the group of aliphatic hydrocarbons with vinyl groups, aromatic hydrocarbons with vinyl groups, aliphatic hydrocarbons with alkynyl groups, aromatic hydrocarbons with alkynyl groups and mixtures thereof.

3. Coating The coating composition according to claim 1, wherein the at least one unsaturated hydrocarbon is selected from aliphatic and/or aromatic C2- to C20-compounds with alkynyl groups, aliphatic and/or aromatic C2- to C20-compounds with vinyl groups and mixtures thereof.

4. The coating composition according claim 1, wherein the at least one unsaturated carboxylic acid is selected from C2- to C20-alkenoic acids.

5. The coating composition according to claim 1, wherein the at least one unsaturated carboxylic acid is selected from the group of acrylic acid, esters of acrylic acid with C1- to C10-alcohols, methacrylic acid, esters of methacrylic acid with C1- to C10-alcohols, fumaric acid, and maleic acid.

6. The coating composition according to claim 1, comprising the organic binding agent in amounts of 2 to 70 wt. % based on the coating composition.

7. The coating composition according to claim 1, wherein the lubricant is selected from the group of organic lubricants, inorganic lubricants and mixtures thereof.

8. The coating composition according to claim 1, wherein the lubricant is selected from the group of waxes, graphene, graphite, boron nitride, molybdenum disulfide, plastic particles.

9. The coating composition according to claim 1, comprising the lubricant in amounts of 0.1 to 10 wt. % based on the coating composition.

10. The coating composition according to claim 1, wherein the coating composition is free of fluorine-containing compounds.

11. The coating composition according to claim 1, wherein the coating composition comprises platelet-shaped particles.

12. The coating composition according to claim 1, further comprising an inorganic binding agent.

13. The coating composition according to claim 12, wherein the inorganic binding agent is selected from silanes, silane hydrolysates, silicates, polysiliconates and mixtures thereof.

14. A coating composition comprising: an organic binding agent, wherein the binding agent comprises a copolymer of at least one olefin and at least one unsaturated carboxylic acid; an inorganic binding agent; and a lubricant.

15. A method comprising using the coating composition according to claim 1 as a topcoat for producing a coating with an adjustable coefficient of friction on a metallic substrate.

16. A method for producing a coating with a selectively adjustable coefficient of friction, the method comprising: providing a substrate having a cathodic corrosion protection coating at least in some areas thereof; applying the coating composition according to one claim 1 to the substrate in the at least in some areas thereof; and drying the coating composition applied to the substrate.

17. The method according to claim 16, wherein the coefficient of friction of the coated substrate is set in the range from 0.09 to 0.16, determined according to DIN EN ISO 16047:2013-01.

18. A metallic substrate comprising a coating, obtainable via the coating composition according to claim 1.

19. The metallic substrate according to claim 18, wherein the coating comprises the lubricant in amounts of 1 to 25 wt. % based on the coating.

20. The metallic substrate according to claim 18, wherein the coating comprises the organic binding agent in amounts of 60 to 99 wt. % based on the coating.

Description

WORKING EXAMPLES

[0212] To further illustrate the present invention and its advantages, several series of tests were carried out with topcoat compositions according to the invention, which are applied to screws. The sliding and frictional properties of the screws are then determined.

Examples 1 to 3

[0213] First, the properties of a topcoat composition exclusively comprising an organic binding agent based on an acrylic ester/methacrylic ester/styrene copolymer are investigated. Micronized polyethylene waxes and thickeners (RheoByk 7420 ES and Optigel) are added to the compositions. The coating compositions are given in Table 1 below.

TABLE-US-00001 TABLE 1 Topcoat compositions with organic binding agent Composition 1 2 3 Acrylic acid ester/methacrylic acid 13 13 13 ester/styrene copolymer [wt. %] Micronized PE wax 3 3 3 [wt. %] RheoByk 7420 ES [wt. %] 0.3 0.9 Optigel [wt.-%] 10.0 Water [wt.-%] 83.7 83.1 77

[0214] Using dip spinners, the coating compositions are applied to the full surface of screws with a layer thickness of 7 ?m and then dried at 120? C. for 20 minutes.

[0215] The screws are then subjected to a friction coefficient determination according to DIN EN ISO 16047:2013-01. It is found that both the total coefficient of friction and the coefficient of friction in the head and thread each lie within the specified VDA window of 0.09 to 0.16.

[0216] For further investigation, the multiple tightening (5 tightenings) is examined on a steel surface, a surface provided with an organic cathodic dip coating (KTL) and an aluminum surface. It is shown that the friction coefficient window for multiple suits is only observed on steel. All three coating compositions show excellent heat release behavior. The values are given in Table 2 below.

TABLE-US-00002 TABLE 2 Investigation of friction and sliding properties Composition 1 1 3 CoF total 0.114 0.106 0.095 0.104-0.123 .sup.0.098-0.113 .sup.0.088-0.104 CoF head 0.110 0.094 0.084 0.101-0.132 .sup.0.088-0.099 .sup.0.076-0.091 CoF thread 0.119 0.122 0.109 0.108-0.130 .sup.0.111-0.142 .sup.0.100-0.121 Multiple tightening steel 10.117 10.110 10.105 30.121 30.120 30.110 ?.sub.tot.sup.1 0.117-0.129.sup. ?.sub.tot 0.110-0.124.sup. ?.sub.tot 0.105-0.111.sup. ?.sub.th.sup.2 0.126-0.126.sup. ?.sub.th 0.112-0.121 ?.sub.th 0.114-0.110 ?.sub.b.sup.3 0.110-0.131 .sup.?.sub.b 0.108-0.126 .sup.?.sub.b 0.099-0.112 Multiple tightening KTL 10.083 10.080 10.077 50.082 50.079 50.078 ?.sub.tot 0.083-0.082 ?.sub.tot 0.080-0.079.sup. ?.sub.tot 0.077-0.078.sup. ?.sub.th 0.079-0.076.sup. ?.sub.th 0.079-0.077 ?.sub.th 0.077-0.080 ?.sub.b 0.085-0.086.sup. .sup.?.sub.b 0.080-0.080 .sup.?.sub.b 0.077-0.077 Multiple tightening Alu 10.080 10.080 10.077 20.081 20.080 20.079 ?.sub.tot 0.080-0.081 ?.sub.tot 0.080-0.080.sup. ?.sub.tot 0.077-0.079.sup. ?.sub.th 0.078-0.072.sup. ?.sub.th 0.080-0.074 ?.sub.th 0.076-0.074 ?.sub.b 0.081-0.087.sup. .sup.?.sub.b 0.080-0.084 .sup.?.sub.b 0.078-0.083 Coating weight 0.023 0.027 0.038 Heat release 0.064 0.062 0.063 .sup.1?.sub.tot: Total friction coefficient .sup.2?.sub.th: Friction coefficient on thread .sup.3?.sub.b: Friction coefficient on head

Examples 4 and 5

[0217] In addition to the above tests 1 to 3, tests were carried out with an acrylic acid copolymer as binding agent. The compositions are given in Table 3 below and the tests on the friction and slip properties in Table 4 below. It can also be seen from Table 4 that the hot soldering properties of compositions 4 and 5 are excellent. The coefficients of friction are also always within the VDA window. This is also the case with multiple tightening, both on steel, a KTL and on aluminum.

TABLE-US-00003 TABLE 3 Topcoat compositions with organic binding agent Composition 4 5 Acrylic acid -Copolymer 18 18 [wt. %] Micronized PE wax 2 2 [wt. %] RheoByk 7420 ES [wt.-%] 0.3 Optigel [wt.-%] 5 Water [wt.-%] 78.7 75

TABLE-US-00004 TABLE 4 Investigation of friction and sliding properties Composition 4 5 CoF total 0.123 0.116 0.104-0.132 .sup.0.102-0.122 CoF head 0.129 0.122 0.106-0.144 .sup.0.113-0.127 CoF thread 0.116 0.109 0.102-0.123 .sup.0.089-0.119 Multiple tightening steel 10.111 10.112 30.110 30.113 ?.sub.tot.sup.1 0.111-0.114.sup. ?.sub.tot 0.112-0.114.sup. ?.sub.th.sup.2 0.112-0.098.sup. ?.sub.th 0.114-0.100 ?.sub.b.sup.3 0.110-0.125 .sup.?.sub.b 0.112-0.124 Multiple tightening KTL 10.107 10.097 50.124 50.113 ?.sub.tot 0.107-0.124 ?.sub.tot 0.097-0.113.sup. ?.sub.th 0.099-0.097.sup. ?.sub.th 0.096-0.091 ?.sub.b 0.114-0.142.sup. .sup.?.sub.b 0.098-0.129 Multiple tightening Alu 10.121 10.116 20.128 20.126 ?.sub.tot 0.121-0.128 ?.sub.tot 0.116-0.126.sup. ?.sub.th 0.095-0.090.sup. ?.sub.th 0.100-0.098 ?.sub.b 0.140-0.156.sup. .sup.?.sub.b 0.127-0.147 Coating weight 0.009 0.015 Heat release 0.063 0.063 .sup.1?.sub.tot: Total friction coefficient .sup.2?.sub.th: Friction coefficient on thread .sup.3?.sub.b: Friction coefficient on head

Examples 6 to 9

[0218] In examples 6 to 9, a mixture of an organic ethylene-acrylic acid copolymer and an inorganic binding agent in the form of a colloidal silicic sol is used. Thickeners and micronized polyethylene waxes are added to each of the compositions 6 to 9 in amounts of 1 wt. %.

[0219] The compositions are given in Table 5 below. The compositions are reapplied to the screws and tested for their frictional properties. The results of the tests are given in Table 6 below. It can be seen that the coefficients of friction are always within the desired VDA window.

TABLE-US-00005 TABLE 5 Topcoat compositions with organic and inorganic binding agent Composition 6 7 8 9 Ethylene-acrylic acid copolymer 20 20 20 20 [wt. %] Colloidal silicic sol [wt. %] 13 13 13 13 Micronized PE wax 1 1 1 1 [wt. %] RheoByk 7420 ES [wt. %] 0.9 0.8 Optigel [wt. %] 5 Water [wt. %] 78.7 78.1 69

TABLE-US-00006 TABLE 6 Investigation of friction and sliding properties Composition 6 7 8 9 CoF total 0.116 0.110 0.109 0.117 0.113-0.120 0.099-0.114 0.104-0.113 0.111-0.121 CoF head 0.119 0.110 0.110 0.115 0.109-0.125 0.093-0.117 0.103-0.114 0.107-0.120 CoF thread 0.112 0.112 0.107 0.120 0.103-0.123 0.105-0.119 0.102-0.112 0.112-0.129 Coating weight 0.040 0.033 0.035 0.019 Run-down time 30 27 32 25 Heat release 0.070

Examples 10 to 17

[0220] Furthermore, two series of tests are carried out in which, on the one hand, an organic binding agent based on an acrylic acid copolymer is used (examples 10 to 13). In addition, an inorganic binding agent in the form of a colloidal silicic sol is used in a second series of tests (Examples 14 to 17).

[0221] The compositions of test series 1 (examples 10 to 13) are given in Table 7 and the examples of test series 2 (examples 14 to 17) in Table 9.

[0222] The compositions are each applied to bolts and examined for their sliding and frictional properties. The results of these tests are shown in Tables 8 and 10.

[0223] It is shown that both the topcoats 10 to 13 with a purely organic binding agent and the topcoats 14 to 17 with a mixture of an organic and an inorganic binding agent comprise excellent properties.

[0224] All topcoats meet the VDA specifications in terms of coefficient of friction, total coefficient of friction, coefficient of friction at the head and coefficient of friction at the thread. The heat release behavior is also always acceptable.

TABLE-US-00007 TABLE 7 Topcoat compositions with organic binding agent Composition 10 11 12 13 Ethylene-acrylic acid copolymer 15 15 15 15 [wt. %] Micronized PE wax 1 1 1 1 [wt. %] RheoByk 7420 ES [wt. %] 0.9 Optigel [wt. %] 5 10 Water [wt. %] 83.1 79 74 84

TABLE-US-00008 TABLE 8 Investigation of friction and sliding properties Composition 10 11 12 13 CoF total 0.122 0.123 0.112 0.116 0.117-0.129 0.118-0.127 0.102-0.121 0.113-0.119 CoF head 0.120 0.124 0.108 0.128 0.111-0.125 0.120-0.128 0.104-0.114 0.125-0.131 CoF thread 0.125 0.122 0.118 0.101 0.112-0.137 0.109-0.136 0.100-0.130 0.094-0.108 Coating weight 0.013 0.011 0.014 Run-down time 30 29 34 Heat release 0.053 0.064 0.062 0.060

TABLE-US-00009 TABLE 9 Topcoat compositions with organic and inorganic binding agent Composition 14 15 16 17 Ethylene-acrylic acid copolymer 15 15 15 15 [wt. %] Colloidal silicic sol [wt. %] 13 13 13 13 Micronized PE wax 1 1 1 1 [wt. %] RheoByk 7420 ES [wt. %] 0.9 0.8 Optigel [wt. %] 5 Water [wt. %] 70.1 70.2 66 71

TABLE-US-00010 TABLE 10 Investigation of friction and sliding properties Composition 14 15 16 17 CoF total 0.118 0.110 0.114 0.116 0.111-0.130 0.104-0.122 0.101-0.120 0.106-0.127 CoF head 0.114 0.105 0.108 0.116 0.102-0.126 0.099-0.114 0.097-0.121 0.102-0.128 CoF thread 0.123 0.118 0.122 0.115 0.115-0.134 0.109-0.132 0.107-0.134 0.102-0.125 Coating weight 0.028 0.031 0.029 Run-down time 48 31 42 Heat release 0.067 0.063 0.063 0.061

Examples 18 to 28

[0225] Furthermore, tests are carried out with binding agent systems containing an organic binding agent in the form of an acrylic acid copolymer and an inorganic binding agent in the form of a colloidal silicic sol and to which various lubricants are added.

[0226] Using dip spinners, the coating compositions are applied to the full surface of screws with a layer thickness of 7 ?m and then dried at 150? C. for 30 minutes.

[0227] The screws are then subjected to a coefficient of friction determination in accordance with DIN EN ISO 16047:2013-01.

TABLE-US-00011 TABLE 11 Topcoat compositions with organic and inorganic binding agents (50% organic and 50% inorganic) Composition 18 19 20 21 Ethylene-acrylic acid copolymer 15 15 15 15 [wt. %] Colloidal silicic sol [wt. %] 15 15 15 15 Lubricant [wt. %] graphite graphite graphite oS.sub.2 3 5 7 5 Water [wt. %] 77 75 73 75

TABLE-US-00012 TABLE 12 Topcoat compositions with organic and inorganic binding agent (30% organic and 70% inorganic) Composition 22 23 24 25 Ethylene-acrylic acid copolymer 9 9 9 9 [wt. %] Colloidal silicic sol [wt. %] 21 21 21 21 Lubricant [wt. %] boron nitride graphite MoS.sub.2 MoS.sub.2 5 5 3 5 Water [wt. %] 75 75 77 75

TABLE-US-00013 TABLE 13 Investigation of friction and sliding properties Composition 18 19 20 21 CoF total 0.107 0.137 0.120 0.116 0.094-0.116 0.133-0.145 0.116-0.123 0.096-0.133 CoF head 0.117 0.153 0.137 0.115 0.098-0.142 0.148-0.161 0.129-0.143 0.094-0.141 CoF thread 0.094 0.116 0.097 0.118 0.083-0.108 0.108-0.130 0.092-0.104 0.099-0.0136 Coating weight 0.034 0.034 0.043 0.024 Composition 22 23 24 25 CoF total 0.115 0.115 0.117 0.104 0.101-0.127 0.111-0.119 0.084-0.146 0.081-0.120 CoF head 0.121 0.119 0.107 0.100 0.103-0.133 0.113-0.129 0.090-0.135 0.081-0.117 CoF thread 0.107 0.109 0.131 0.109 0.097-0.120 0.096-0.126 0.059-0.162 0.081-0.134 Coating weight 0.031 0.031 0.026 0.025