DEHYDRATED COATING COMPOSITIONS IN SOLID FORM, PRODUCTION METHOD THEREOF, AND METHOD FOR REHYDRATING SAME

Abstract

The present invention relates to a water-rehydratable solid composition for the production of an aqueous composition comprising a particular metal, a silane/(titanate and/or zirconate) binder, a method for producing such a composition, and a method for producing an aqueous composition comprising a particular metal, a silane/(titanate and/or zirconate) binder by hydrating such a solid composition.

Claims

1. A solid composition intended for the preparation of an anti-corrosion coating composition for metal parts based on particulate metal in aqueous dispersion, wherein the composition is solid, the composition is water-rehydratable, the composition is based on: a particulate metal or a mixture of particulate metals, a titanate precursor and/or a zirconate precursor and a silane bearing at least one function hydrolyzable to a hydroxyl function, the composition has a Ti/Si molar ratio ranging from 10/90 to 60/40.

2. The solid composition of claim 1, wherein the Ti/Si molar ratio varies from 20/80 to 50/50.

3. The solid composition of claim 1, wherein the composition is in powdered form, with a particle size ranging from about 2 m to about 3 mm.

4. The solid composition of claim 1, wherein the composition is in the form of a gel.

5. The solid composition of claim 1, wherein the titanate precursor is an organic titanate, and the zirconate precursor is an organic zirconate.

6. The solid composition of claim 1, wherein the silane additionally carries an epoxy function.

7. The solid composition of claim 6, wherein the silane is selected from epoxy-functional di- or trimethoxysilane and epoxy-functional di- or triethoxysilane, as well as mixtures thereof.

8. The solid composition of claim 1, wherein the particulate metal content ranges from 20 to 70% by weight, based on the total weight of the solid composition.

9. The solid composition of claim 1, wherein the particulate metal is selected from zinc and aluminum and their alloys and mixtures thereof or alloys thereof with manganese, magnesium, or tin.

10. The solid composition of claim 1, further based on a silicate.

11. The solid composition of claim 1, obtained by dehydration of an aqueous composition comprising the particulate metal, the titanate and/or zirconate precursor, the silane, optionally said a silicate, and water.

12. (canceled)

13. (canceled)

14. (canceled)

15. A process for preparing a solid composition comprising: a step of dehydrating an aqueous composition comprising: a particulate metal or a mixture of particulate metals, a titanate and/or zirconate precursor, a silane bearing at least one function hydrolyzable to a hydroxyl function, the composition has a Ti/Si molar ratio ranging from 10/90 to 60/40, optionally a silicate, and water; then, recovering a composition which is solid, which is water-rehydratable, which is based on the particulate metal or the mixture of particulate metals, the titanate precursor and/or the zirconate precursor, the silane bearing at least one function hydrolyzable to a hydroxyl function, the composition has a Ti/Si molar ratio ranging from 10/90 to 60/40, and optionally the silicate.

16. The process of claim 15, wherein dehydration is conducted by freeze-drying, zeodration, vacuum evaporation, or spray drying.

17. A process for preparing an aqueous composition comprising: providing a composition which is solid and which is based on a particulate metal or a mixture of particulate metals, a titanate precursor and/or a zirconate precursor, a silane bearing at least one function hydrolyzable to a hydroxyl function, the composition has a Ti/Si molar ratio ranging from 10/90 to 60/40, and optionally a silicate, then, hydrating the solid, composition.

18. The solid composition according to claim 1, wherein the Ti/Si molar ratio varies from 25/75 to 50/50.

19. The solid composition of claim 1, wherein the titanate precursor is selected from C.sub.1-C.sub.8 tetraalkyl titanates, and the zirconate precursor is selected from C.sub.1-C.sub.8 tetraalkyl zirconates.

20. The solid composition of claim 6, wherein the silane is selected from beta-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, 4-(trimethoxysilyl)butane-1,2-epoxide, gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyltriethoxysilane, octyltriethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, (2-diethylphosphatoethyl) triethoxy silane, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, methyl methacrylate trimethoxysilane, methyl methacrylate triethoxysilane and mixtures thereof.

21. The process of claim 15, wherein of the aqueous composition comprises at least 15% by weight of water, based on the total weight of the aqueous composition.

22. The process of claim 15, wherein of the aqueous composition further comprises an organic solvent, an ionic liquid, or mixtures thereof.

23. The process of claim 22, wherein of the aqueous composition comprises from 0.5 to 15% by weight, of organic solvent, ionic solvent, or mixtures thereof, based on the total weight of the aqueous composition.

Description

EXAMPLES

[0100] The following examples show ways in which the present invention may be implemented, but do not in any way limit the present invention.

[0101] Gas Phase Chromatography (GPC)

[0102] The analysis conditions are as follows:

[0103] Eluent=waterFlow rate=0.8 mL/minDilution=1 qs 60Injection=100 LDetector: Refractive Index at 35 C.TSK Gel type columns thermostatted at 40 C.: 1 pre-column+2 columns G2500PWXL+1 column G3000 PWXL+1 column G4000 PWXL.

[0104] Viscosity

[0105] Measurement of a flow time with a DIN 4 or AFNOR 4 type consistometric cup.

[0106] Preparation of the Test Panels:

[0107] Unless otherwise specified, test panels are typically cold rolled, low carbon steel panels. They may be prepared first by immersion in a cleaning solution. The panels may then be scrubbed with a cleaning pad, rinsed with water and then immersed again in the cleaning solution. After removing the solution, the panels are rinsed with tap water and dried.

[0108] Preparation of the Test Screws:

[0109] The screws are degreased in an alkaline medium at 80 C., then rinsed with water and dried before being shot-blasted.

[0110] Application of the Coating to the Test Parts and Weight of the Coating:

[0111] Clean parts are typically coated by dipping them into the coating composition, removing and draining excess composition from it, sometimes with a moderate stirring action, and then they are baked at a temperature corresponding to the technology that has been rehydrated. The coating weights (g/m.sup.2) are determined by comparative weighing before and after coating.

[0112] Corrosion Resistance TestHours of Salt Spray Resistance:

[0113] Salt spray tests are conducted according to ISO9227 (May 2012).

[0114] A score of 10 corresponds to 0 traces of red rust on the part.

Comparative Example 1: Dehydration by Freeze-Drying or Vacuum Evaporation of a Coating Composition Based on a Sol/Gel Binder Matrix Obtained from Precursors Based Solely on Si

[0115] Dehydration:

[0116] Freeze-Drying

[0117] 1 liter of a composition CC1, distributed in 4 round-bottom flasks, was freeze-dried, after prior freezing in liquid nitrogen. The freeze-drying operation, carried out at 80 C. and at a pressure of between 0.1 mbar and 0.26 mbar, took 24 h to obtain a dehydrated solid. The composition was subjected to distillation prior to freeze-drying to remove by evaporation the residual ethanol and water/ethanol azeotrope from the monomer reactions, and water was then added to obtain the same amount of final dry matter.

[0118] The resulting powder was stored for 2 weeks at room temperature and atmospheric pressure.

[0119] Vacuum Evaporation

[0120] 280 g of a composition CC1 was evaporated for 5 h under vacuum (20 mbar) at a water bath temperature of 40 C. to obtain a solid that could be finely ground.

[0121] The composition was subjected to distillation prior to vacuum evaporation to remove by evaporation the residual ethanol and water/ethanol azeotrope resulting from the monomer reactions, and water was then added to obtain the same amount of final dry matter.

[0122] The resulting powder was stored for 1 day at room temperature and atmospheric pressure.

[0123] In both processes, the composition CC1 is prepared from the compounds according to the data in the following table (% by mass introduced*relative to the initial total weight):

TABLE-US-00001 TABLE 1 CC1 Zn.sup.1 27.3 Al.sup.2 6.4 Glycidoxypropyltriethoxysilane 8 Tetraethyl orthosilicate 2 Dipropylene glycol 10 Water 37.6 Additives 8.7 .sup.1Zinc paste at about 92% in white spirit .sup.2Alu Chromal VIII powder marketed by Eckart Werke (Al dry matter: 80% by weight) *The levels given in Table 1 are the levels initially introduced into the mixture. Indeed, some of the constituents introduced can or will react with each other, at least partially, during the various stages of manufacture of the composition, or during subsequent baking, thus modifying the composition as it is prepared at the outset. This also applies to Tables 2 and 5.

[0124] Rehydration:

[0125] Rehydration tests of the powder from composition CC1, obtained after freeze-drying or vacuum evaporation, were attempted without success. In both cases, the Si binder-based composition powder obtained is not rehydratable.

Example 1: Dehydration by Freeze-Drying or Vacuum Evaporation of a Coating Composition Based on a Sol/Gel Binder Matrix Obtained from Si and Ti Based Precursors

[0126] Dehydration:

[0127] Freeze-Drying

[0128] 1 liter of a composition CI1, distributed in 4 round-bottom flasks, was freeze-dried after prior freezing in liquid nitrogen. The freeze-drying operation, carried out at 80 C. and at a pressure of between 0.1 mbar and 0.26 mbar, took 24 h to obtain a dehydrated solid which was subsequently ground into a fine powder with a particle size ranging from about 2 m to a few mm.

[0129] The composition was subjected to distillation prior to freeze-drying to remove by evaporation the residual ethanol and water/ethanol azeotrope from the monomer reactions, and water was then added to obtain the same amount of final dry matter.

[0130] The resulting powder was stored for 2 to 3 weeks at room temperature and atmospheric pressure.

[0131] Vacuum Evaporation

[0132] 350 g of a composition CI1 was evaporated for 7.5 h under vacuum (20 mbar) at a water bath temperature of 40 C. in order to obtain a solid that could be finely ground.

[0133] The composition was subjected to distillation prior to vacuum evaporation to remove by evaporation the residual ethanol and water/ethanol azeotrope resulting from the monomer reactions, and water was then added to obtain the same amount of final dry matter.

[0134] The resulting powder was stored for 1 day at room temperature and atmospheric pressure.

[0135] The composition of the composition CI1 is prepared from the compounds according to the data in the following table (% by mass introduced in relation to the initial total weight):

TABLE-US-00002 TABLE 2 CI1 Zn.sup.1 23.7 Al.sup.2 1.6 Glycidoxypropyltriethoxysilane 13.8 Tetraethyl orthosilicate 0.7 Tetra ethoxytitanate 4.4 Dipropylene glycol 5.5 Water 43.1 Additives 7.2 .sup.1Dry zinc .sup.2Alu Chromal VIII powder marketed by Eckart Werke In CI1, the Ti/Si molar ratio is 27/73.

[0136] Rehydration:

[0137] The powder from composition CI1, whether obtained by freeze-drying or by vacuum evaporation, was then easily rehydrated at a stirring speed of about 300-500 rpm, by adding demineralized water, so as to obtain a liquid with the same dry matter by weight as the original liquid composition (dry matter content=41-42%). The composition thus obtained is referred to as: [0138] CI1 when the powder is obtained by freeze-drying [0139] CI1 when the powder is obtained by vacuum evaporation.

[0140] The stability of CI1/CI1/CI1 compositions after thickening by adding a cellulosic thickener, under stirring, once the composition is completely rehydrated, and after one month of storage at 20 C. is equivalent, as shown in the following table:

TABLE-US-00003 TABLE 3 CI1 CI1 CI1 Viscosity CA4 (dry) at about 30 days, 20 C. 103 105 98 pH, at about 30 days, 20 C. 8.4 8.2 8.2

[0141] The salt spray performance obtained is equivalent, as shown in the following table:

TABLE-US-00004 TABLE 4 CI1 CI1 CI1 Coating weight (g/m.sup.2) 27.4 27.4 28.3 Salt spray resistance (hours) at t = 0 1368 1176 1368 Note 10

Example 2: Dehydration by Freeze-Drying or Vacuum Evaporation of a Sol/Gel Matrix Coating Composition Obtained from Si and Ti Precursors, Enriched with Ti

[0142] Dehydration:

[0143] Freeze-Drying

[0144] 1 liter of a composition CI2, distributed in 4 round-bottom flasks, was freeze-dried after prior freezing in liquid nitrogen. The freeze-drying operation, carried out at 80 C. and at a pressure of between 0.1 mbar and 0.26 mbar, took 24 h to obtain a dehydrated solid which was subsequently ground into a fine powder with a particle size ranging from about 2 m to a few mm.

[0145] The composition was subjected to distillation prior to freeze-drying to remove by evaporation the residual ethanol and water/ethanol azeotrope from the monomer reactions, and water was then added to obtain the same amount of final dry matter.

[0146] The resulting powder was stored for about 3 weeks at room temperature and atmospheric pressure.

[0147] Vacuum Evaporation

[0148] 1038 g of a composition CI2 was evaporated for 2.5 h under vacuum (20 mbar) at a water bath temperature of 40 C. to obtain a solid that could be finely ground.

[0149] The composition was subjected to distillation prior to vacuum evaporation to remove by evaporation the residual ethanol and water/ethanol azeotrope resulting from the monomer reactions, and water was then added to obtain the same amount of final dry matter.

[0150] The resulting powder was stored for 2 weeks at room temperature and atmospheric pressure.

[0151] The base compounds of the composition CI2 are given in the following table (% by mass introduced in relation to the initial total weight):

TABLE-US-00005 TABLE 5 CI2 Zn.sup.1 27.8 Al.sup.2 3.6 Glycidoxypropyltriethoxysilane 7.2 Tetra-isopropoxytitanate 7.2 Water 48.5 Additives 5.7 .sup.1Dry zinc .sup.2Alu Silbercote AQ E 2169 F3X

[0152] In CI2, the Ti/Si molar ratio is 50/50. After freeze-drying, the dry matter content is 96.8%.

[0153] Rehydration:

[0154] The powder from the composition CI2, whether obtained by freeze-drying or vacuum evaporation, was then easily rehydrated at a stirring speed of about 300 to 500 rpm by adding demineralized water, so as to obtain a liquid with the same dry matter by weight as the original liquid composition.

Example 3: Spray Dehydration of a Coating Composition Based on a Sol/Gel Binder Matrix Obtained from Si and Ti Based Precursors

[0155] Dehydration:

[0156] Approximately 2.2 kg of the composition CI3 diluted to 35% dry matter was spray dehydrated. The spray parameters were adjusted to obtain a dry powder with a temperature below 40 C.

[0157] The resulting powder was stored for 2 weeks at room temperature and atmospheric pressure.

[0158] The base compounds of the composition CI3 are given in the following table (% by mass introduced in relation to the initial total weight):

TABLE-US-00006 TABLE 6 CI3 Zn.sup.1 23.7 Al.sup.2 1.6 Glycidoxypropyltriethoxysilane 13.8 Tetraethyl orthosilicate 0.7 Tetra ethoxytitanate 4.4 Dipropylene glycol 2.5 Water 46.1 Additives 7.2 .sup.1Dry zinc .sup.2Alu Silbercote AQ E 2169 F3X In CI3, the Ti/Si molar ratio is 27/73. After spray drying, the dry matter content is 90.3%.

[0159] Rehydration:

[0160] The powder from the composition CI3 was easily rehydrated (<24 h) at a stirring speed of about 300 to 500 rpm, by adding demineralized water so as to obtain a liquid with the same dry matter by weight as the starting liquid composition (dry matter content=41-42%). The composition thus obtained is called: [0161] CI3 when the powder is obtained by spray drying [0162] The compositions CI3/CI3 after thickening by adding a cellulosic thickener, under stirring, once the composition is completely rehydrated, have the same parameters, as shown in the following table:

TABLE-US-00007 TABLE 7 CI3 CI3 Viscosity CA4 (dry) at about 30 days, 20 C. 126 101 pH, at about 30 days, 20 C. 8.4 8.3

[0163] The salt spray resistance performances obtained on screws are at least equivalent, or even superior, as shown in the following table:

TABLE-US-00008 TABLE 8 CI3 CI3 Coating weight (g/m.sup.2) at t = 0 26.1 27.7 Salt spray resistance (hours) at t = 0 672 1296 Note 10 Coating weight (g/m.sup.2) 25.3 23.8 at t = 1 month 20 C. Salt spray resistance (hours) at 720 672 t = 1 month 20 C. Note 10

Example 4: Dehydration by Vacuum Evaporation of a Coating Composition Based on a Sol/Gel Binder Matrix Obtained from Si and Ti Based Precursors

[0164] Dehydration:

[0165] 978 g of the composition CI4 of 60.7% dry matter was evaporated for 7 h 5 min under vacuum (20 mbar) at a water bath temperature of 40 C. to obtain a solid that could be finely ground.

[0166] The resulting powder was stored for 12 days at room temperature and atmospheric pressure.

[0167] The base compounds of the composition CI4 are given in the following table (% by mass introduced in relation to the initial total weight):

TABLE-US-00009 TABLE 9 CI4 Zn.sup.1 29.1 Al.sup.2 4.1 Glycidoxypropyltrimethoxysilane 18.3 Tetraethyl orthosilicate 1.4 Tetra ethoxytitanate 6 Dipropylene glycol 8 Alcohols (ethanol + 3% isopropanol) 5.2 Water 16.5 Additives 11.5 .sup.1Dry zinc .sup.2Alu Chromal VIII powder marketed by Eckart Werke In the composition CI4 the Ti/Si ratio is 24/76.

[0168] Rehydration:

[0169] The powder from the composition CI4 was easily rehydrated (<10 h) at a stirring speed of about 300 to 500 rpm, by adding demineralized water so as to obtain a dry matter liquid by weight of 38.6%. The composition thus obtained is called: [0170] CI4 when the powder is obtained by vacuum evaporation

[0171] The stability of compositions CI4/CI4 at a dry matter of 38%, after one month of storage at 20 C. is equivalent, as shown in the following table:

TABLE-US-00010 TABLE 10 60% CI4 diluted CI4 to 38% by adding (DM = 60%) demineralized water CI4 Viscosity CA4 (dry) at gel 21 23 about 30 days, 20 C. pH, at about 30 days, 20 C. NA 7.7 7.9