DEHYDRATED BINDERS 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 silane/(titanate and/or zirconate) binder, a method for producing such a composition, and a method for producing an aqueous composition comprising a silane/titanate and/or zirconate) binder by hydrating such it solid composition.

Claims

1. A solid composition, intended for the preparation of an aqueous composition comprising a binder based on silane and titanate and/or zirconate, wherein the composition is water-hydratable the composition is solid the composition is based on; a titanate precursor and/or a zirconate precursor and a silane carrying 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 1, 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, further based on a silicate.

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

10. (canceled)

11. (canceled)

12. (canceled)

13. A process for preparing a solid composition, comprising: dehydrating an aqueous composition comprising a titanate precursor and/or a zirconate precursor, a silane carrying at least one function hydrolysable to a hydroxyl function having a Ti/Si molar ratio ranging from 10/90 to 60/40, optionally a silicate, and water: recovering a solid composition which is solid, which is water-hydratable, and which is based on the titanate and/or zirconate precursor, the silane, having a Ti/Si molar ratio ranging from 10/90 to 60/40, optionally the silicate, and water.

14. The process of claim 13, wherein the dehydration is carried out by freeze-drying, zeodration, vacuum evaporation or spray drying.

15. A process for preparing an aqueous composition comprising: providing a composition which is solid and which is based on a titanate precursor and/or a zirconate precursor, a silane bearing at least one function hydrolysable 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.

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

17. The solid composition of claim 5, wherein the organic titanate is selected from C.sub.1-C.sub.3 tetraalkyl titanates, and the organic zirconate is selected from C.sub.1-C.sub.8 tetraalkyl zirconates,

18. The solid composition of claim 7, 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.

19. The solid composition of claim 8, wherein the silicate is a silicon alkoxide.

20. The process of claim 13, wherein the aqueous composition comprises at least 25% by weight of water, based on the total weight of the aqueous composition.

21. The process of claim 13, wherein the aqueous composition comprises at least 32% by weight of water, based on the total weight of the aqueous composition.

22. The process of claim 13, wherein the aqueous composition further comprises a heavy organic solvent, an ionic liquid, or mixtures thereof.

23. The process of claim 13, wherein the aqueous composition comprises from 0.5 to 15% by weight of heavy organic solvent, ionic solvent, or mixtures thereof, based on the total weight of the aqueous composition.

Description

EXAMPLES

[0090] The following examples show ways in which the present invention may be implemented, but do not in any way limit the present invention.

Gel Phase Chromatography (GPC)

[0091] The analysis conditions are as follows:

[0092] 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.

Viscosity

[0093] Measurement of a flow time with a DIN 4 type consistometric cup.

Preparation of the Test Panels:

[0094] 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.

Preparation of the Test Screws:

[0095] The screws are degreased in an alkaline medium at 80 C., then rinsed with water and dried before being shot-blasted.

Application of the Coating to the Test Parts and Weight of the Coating:

[0096] Clean test screws are typically coated by dipping them into the coating composition, removing and draining excess composition from it, sometimes with moderate shaking. Clean test panels are typically coated by application to the Conway bar. The test parts are then subjected to immediate curing (180 C. to 310 C.) or drying at room temperature or pre-curing at a moderate temperature until the coating is dry to the touch and then cured (180 C. to 310 C.). The coating weights (g/m.sup.2) are determined by comparative weighing before and after coating.

Corrosion Resistance TestHours of Salt Spray Resistance:

[0097] Salt spray tests are conducted according to IS09227 (May 2012). A score of 10 corresponds to 0 traces of red rust on the part. A score of 9 corresponds to: 1 to 10 localized spots of red rust.

Comparative Example 1

Freeze-Drying of a sol/gel Binder Matrix Obtained from Precursors Based Solely on Si

[0098] 350 mL of binders of different compositions, LC1 to LC5, was successively lyophilized, after prior freezing in liquid nitrogen, in a 1-liter round-bottom flask. 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 or liquid. The binders LC1 and LC3 underwent two successive freeze-dryings of 24 hours.

[0099] Compositions LC3 to LC5 were distilled prior to freeze-drying to remove residual ethanol and water/ethanol azeotrope from the monomer reactions by evaporation, and water was then added to obtain the same amount of final dry matter.

[0100] The powders and viscous liquids obtained were stored for 1 month at room temperature and atmospheric pressure.

[0101] The composition of binders LC1 to LC5 is given in the following table (% by mass introduced* compared to the total initial weight):

TABLE-US-00001 TABLE 1 LC1 LC2 LC3 LC4 LC5 Glycidoxypropyltriethoxysilane 26 26 26 26 26 Tetraethyl orthosilicate 6.5 6.5 6.5 6.5 6.5 Dipropylene glycol 0 10 0 5 10 Water 67.5 57.5 67.5 62.5 57.5 Evaporation step before no no yes yes yes freeze-drying Mass % of residual ethanol 19 18 3 2.5 2 before freeze-drying after reaction of monomers
*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, 6 and 8.

[0102] Rehydration tests of binders LC1 and LC3, without dipropylene glycol, were then attempted without success. The resulting Si binder powder is not rehydratable. In binders comprising dipropylene glycol, LC2, LC4 and LC5, a more or less viscous liquid is obtained. This is dilutable with water but leads to an unstable polymer. Indeed, GPC graphs show a lack of molecular weight stability.

[0103] It should be noted that regardless of the mass content of residual ethanol before freeze-drying, freeze-drying is feasible.

Example 1

Freeze-Drying of a sol/gel Binder Matrix Obtained from Si and Ti Based Precursors, Enriched with Ti

[0104] 350 mL of binders of different compositions, LI1 to L12, were successively lyophilized, after prior freezing in liquid nitrogen, in a 1-liter round-bottom flask. 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 solid which was subsequently ground into a fine powder with a particle size ranging from about 2 pm to a few mm.

[0105] Compositions LI1 and L12 were subjected to distillation prior to freeze-drying in order to remove by evaporation the residual ethanol and water/ethanol azeotrope resulting from the monomer reactions, and water was then added in order to obtain the same amount of final dry matter.

[0106] The powders obtained were stored for 2 to 3 weeks at room temperature and atmospheric pressure.

[0107] The composition of the binders LI1 and L12 is given in the following table (% by mass introduced in relation to the initial total weight):

TABLE-US-00002 TABLE 2 LI1 LI2 Glycidoxypropyltriethoxysilane 22.2 22.2 Tetra-isopropoxytitanate 22.2 22.2 Dipropylene glycol 0 5 Water 54.6 49.6 Additive 1 1

[0108] In LI1 or L12, the Ti/Si molar ratio is 50/50. Before freeze-drying, the dry matter content is 22% by weight.

[0109] The powder from the binder LI2, the initial composition of which contains dipropylene glycol, 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 initial liquid composition. The binder thus obtained is called LI'2.

[0110] The rehydration of the powder from the binder LI1, which did not initially contain dipropylene glycol, took longer. The resulting binder is called LI1

[0111] After rehydration, the GPC spectra of the binders LI1, LI2 are equivalent to those of the binders LI1, L12: the molecular weights are stabilized.

[0112] Baths were made either with the binder LI2 or with the binder LI2 (B2 and B2 respectively), with the addition of 28.4% by weight of dry zinc and 1.87% by weight of Alu Chrome! VIII powder marketed by Eckart Werke (Al dry matter: 80% by weight), based on the total weight of the bath, additives, and water as solvent. The dry matters of baths B2 and B2 are 39%.

[0113] The stability of the baths B2 / B2 after one month of storage at 20 C. is equivalent, as shown in the following table:

TABLE-US-00003 TABLE 3 B2 B2 Viscosity DIN4 (dry) at 30 35 36 days, 20 C. pH, at 30 days, 20 C. 9 9

[0114] The binders LI2 and LI'2 were used for the preparation of anti-corrosion coatings (dry film), respectively CR2 and CR'2. The composition of the anti-corrosion coating (dry film) is given in the following table (theoretical mass%* in relation to the total weight):

TABLE-US-00004 TABLE 4 CR2 CR2 Binder L2 19 0 Binder L2 0 19 Zn 70.7 70.7 Al 3.7 3.7 Additives 6.6 6.6 *The percentages by weight given in this Table 4 correspond to the percentages by weight calculated considering that the dry matter of the binder is 22% by weight and that only non-volatile additives are counted.

[0115] The salt spray resistance performances obtained are similar, as shown in the following table:

TABLE-US-00005 TABLE 5 CR2 CR2 Coating thickness (m) 11 11.5 Salt spray resistance (hours) 504/ 336/ at t = 0 Note 10/9 840 552

Example 2

Freeze-Drying of a sol/gel Binder Matrix Obtained from Si and Ti Based Precursors, Enriched with Ti

[0116] 250 mL of binders of different compositions, LI3, LI4, LI5 and LI6, was successively lyophilized, after prior freezing in liquid nitrogen, in a 1-liter round-bottom flask. 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 solid which was subsequently ground into a fine powder with a particle size ranging from about 2 m to a few mm. drying The compositions LI3 to LI6 were subjected to distillation prior to freeze-drying in order to remove by evaporation the residual ethanol and water/ethanol azeotrope resulting from the monomer reactions, and water and 1 to 5% solvent (DPG/EL/CCU) were then added to obtain the same amount of final dry matter.

[0117] The powders obtained were stored for 2 days at room temperature and atmospheric pressure.

[0118] The composition of the binders LI3, LI4, LI5 and LI6 is given in the following table (% by mass introduced in relation to the initial total weight):

TABLE-US-00006 TABLE 6 LI3 LI4 LI5 LI6 Glycidoxypropyltriethoxysilane 22.2 22.2 22.2 22.2 Tetra-isopropoxytitanate 22.2 22.2 22.2 22.2 Dipropylene glycol (DPG) 1 3 0 0 Ethyl lactate (EL) 0 0 0 5 Choline chloride urea (CCU) 0 0 5 0 Water 53.6 51.6 49.6 49.6 Additive 1 1 1 1

[0119] In LI3 or LI4 or LI5 or LI6, the Ti/Si molar ratio is 50/50. Before freeze-drying, the dry matter content is 22% by weight.

[0120] The powders from the binder LI3 or LI4 or LI5 or LI6 were 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 starting liquid composition. The binders thus obtained are called LI3, LI4, LIS, LI6, respectively. After rehydration, the GPC spectra of the binders LI3, LI4, LIS, LI6 are equivalent to those of the binders LI3, LI4, LI5, LI6: the molecular weights are stabilized.

[0121] The binders LI3, LI4, LI5, LI6, LI3, LI4, LIS, LI6 are used to make baths with the same composition as in Example 1, the binders LI2 or LI2 being replaced by the binders in this example.

[0122] The stability of the baths after one month's storage at 20 C. is equivalent whether the binder used is an initial binder (LI3, LI4, LI5) or a binder obtained by the process according to the invention (LI3, LI4, LI5). Baths made from the binder LI6 are not stable whereas they are stable when the binder is LI6.

[0123] The binders LI3, LI4, LI3, LI4, LI6 were used for the preparation of anti-corrosion coatings, respectively CR3, CR4, CR'3, CR'4, CR'6, of the same composition as in Example 1, the binders LI2 or LI2 being replaced by the binders of this example. The salt spray performance obtained is at least equivalent, as shown in the following table:

TABLE-US-00007 TABLE 7 CR3 CR4 CR3 CR4 CR6 Coating thickness (m) 8.7 9.3 8.1 9.9 9.5 Salt spray resistance 24/ 120/ 912/ 120/ 1344/ (hours) at t = 1 month, 240 168 984 1584 1344 20 C. Note 10/9

Example 3

Freeze-Drying of a sol/gel Binder Matrix Obtained from Si and Ti Based Precursors

[0124] 0.8 liter of binder LI7, distributed in 3 round-bottom flasks, and 1 liter of binder LI8, distributed in 4 flasks, were successively freeze-dried, after prior freezing in liquid nitrogen, in a 1 liter flask. The freeze-drying operation, carried out at 80 C. and at a pressure of between 0.1 mbar and 0.26 mbar, required 24 h to obtain a dehydrated solid/gel.

[0125] The compositions LI7 and LI8 were distilled 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.

[0126] The powders obtained were stored for 5 days at room temperature and atmospheric pressure.

[0127] The composition of the binders LI7 and LI8 is given in the following table (% by mass introduced in relation to the total initial weight):

TABLE-US-00008 TABLE 8 LI7 LI8 Glycidoxypropyltriethoxysilane 28 28 Tetra Ethoxytitanate 9.5 9.5 Tetraethyl orthosilicate 1.5 1.5 Dipropylene glycol 5.4 12.0 Water 55.6 49.0

[0128] In LI7 or LI8, the Ti/Si molar ratio is 28/72. Before freeze-drying, the solids content is 22% by weight.

[0129] The soft solid from the binder LI8 hardens over time. It was then rehydrated by adding demineralized water at a temperature of 40 C. to 60 C. and under stirring, so as to obtain a liquid (LI8) with the same dry matter by weight as the starting liquid composition.

[0130] The solid from the binder LI7 containing half as much dipropylene glycol rehydrates significantly slower, even at a temperature of 40 C. to 60 C.

[0131] It can therefore be seen that the addition of heavy organic solvent to the initial aqueous composition with a lower molar amount of titanate facilitates subsequent rehydration.

Example 4

Vacuum Evaporation of a sol/gel Binder Matrix Obtained from Si and Ti Based Precursors

[0132] 3640 g of the binder LI7, as described in Example 3 but not previously distilled, was evaporated in an Erlenmeyer flask for 12.5 hours under vacuum (20 mbar) at a water bath temperature of 40 C-45 C. to obtain a dehydrated solid/gel.

[0133] The soft solid from the binder LI7 hardens over time. It was then rehydrated after storage for 1 day at room temperature and atmospheric pressure by adding a mixture of demineralized water and dipropylene glycol (6.5% by weight of dipropylene glycol based on the total weight of the demineralized water/dipropylene glycol mixture) in 7 days at 20 C., so as to obtain a liquid with the same dry matter by weight as the starting liquid composition. The binder thus obtained with a composition identical to LI8 is called LI8.

[0134] After rehydration, the GPC spectrum of the binder LI8 is equivalent to that of the binder LI8: the molecular weights are stabilized.

[0135] The binders LI8, LI8 are used to make baths by adding 28.4% by weight of dry zinc and 1.87% by weight of Alu Chrome! VIII powder marketed by Eckart Werke, based on the total weight of the bath, additives and water as a solvent. The dry matters of the baths B3 and B3 are 41.6 and 41.3% respectively.

[0136] The stability of the baths after one month's storage at 20 C. is equivalent whether the binder used is an initial binder (LI8) or a binder obtained by the process according to the invention (LI8).

[0137] The binders LI8 and LI8 were used for the preparation of anti-corrosion coatings, CR8 and CR8 respectively. The composition of the anti-corrosion coating (dry film) is given in the following table (theoretical mass %* in relation to the total weight):

TABLE-US-00009 TABLE 9 CR8 CR8 Binder L8 26.2 0 Binder L8 0 26.2 Zn 61.6 61.6 Al 3.3 3.3 Additives 8.9 8.9 *The percentages by weight given in this Table 9 correspond to the percentages by weight calculated considering that the dry matter of the binder is 22% by weight and that only non-volatile additives are counted.

[0138] The salt spray resistance performances obtained are similar, as shown in the following table:

TABLE-US-00010 TABLE 10 CR8 CR8 Panel Coating weight (g/m.sup.2) 27.4 27.7 Salt spray resistance (hours) at t = 0 1392 792 Note 10 Screw Coating weight (g/m.sup.2) 23.6 25.4 AS IS 1512 1224 CTV (mechanical shocks) 1056 1344 Cth (Thermal shock: 96 h at 180 C.) 1512 1512 CTV + Cth (mechanical and 1176 624 thermal shock)

Example 5

Vacuum Evaporation of a sol/gel Binder Matrix Obtained from Si and Ti Precursors, Enriched with Ti

[0139] 1 to 2 kg of binder LI3 or LI4 or LI5, as described in Example 2, was evaporated for about 2.5 to 4 h under vacuum (20 mbar) in the rotary evaporator at 100 rpm at a water bath temperature of 40 C. to obtain a solid that can be finely ground.

[0140] The powders from the binder LI3 or LI4 or LI5 or LI6 were 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 starting liquid composition. The binders thus obtained are respectively named LI3, LI4, LI5, LI6.

[0141] After rehydration, the GPC spectra of the binders LI3, LI4, LI5, LI6 are equivalent to those of the binders LI3, LI4, LI5, LI6: the molecular weights are stabilized.

[0142] The binders LI3, LI4, LI5, LI6, LI3, LI4, LI5, LI6 are used to make baths with the same composition as in Example 1, the binders LI2 or LI2 being replaced by the binders in this example.

[0143] The stability of the baths after one month's storage at 20 C. is equivalent whether the binder used is an initial binder (LI3, LI4, LI5) or a binder obtained by the process according to the invention (LI3, LI4, LI5). Baths made from the binder LI6 are not stable whereas they are stable when the binder is LI6

[0144] The binders LI4, LI4, LI6 were used for the preparation of anti-corrosion coating compositions, respectively CR4, CR4, CR6, of the same composition as given in Example 1, the binders LI2 or LI2 being replaced by the binders of this example. The salt spray performance obtained is given in the following table:

TABLE-US-00011 TABLE 11 CR4 CR4 CR6 Coating thickness (m) 9.6 9.9 9.6 Salt spray resistance (hours) at 120/ 120/ 624/ t = 1 month, 20 C. Note 10/9 336 624 1056