DE4233107A1 - Silicon as pigment in coatings - Google Patents

Abstract

The invention pertains to a method of coating metals by applying a substance that contains (A) at least one polymer and/or at least one constituent that cures into a polymer and (B) elementary silicon. Component (A) preferably contains a polyorganosiloxane and/or a constituent that cures into a polyorganosiloxane.

Description

The present invention relates to a method for loading Layering of metals with polymers and / or with Polymers reacting masses, which are elemental silicon contain.

State of the art

From US-A 5,093,289 it is known a suspension of sili con resin and silicon powder in xylene on a polyurethane apply foam with open-cell pore structure. The way coated foam is then pyrolyzed. Back remains a ceramic material based on in the present of carbon reactive silicon.

US-A-3,817,905, among others, contains zinc powder Coating agents described as a binder Partial hydrolyzate of a tricarbonoxyorganosilane contain.

task

The object of the present invention was to find a suitable one To provide pigment for metal coatings. A white Another object of the present invention was to coat to develop conditions that are stable even at high temperatures are. Furthermore, it was an object of the present invention Process for coating metals with metal pigments to develop funds, whereby the metal pigment does not NEN gives rise to the formation of hydrogen.

solution

The above tasks are accomplished by the present Er solved by a method for coating Me tallen by applying a mass, which

• A) at least one polymer and / or at least one to Po contains lymer hardening component, characterized, that the crowd too
• B) elemental silicon contains.

In this sense, metal alloys are also among metals, such as bronzes, brass types, steels, nickel silver and other copper fer-nickel alloys, duralumin, magnesium alloys, Aluminum bronze, tombac, lettering metal and the like more to understand. Also under metals in this sense are said to be semi-metals, such as silicon, and alloys of such semi-metals can be understood.  

The component used in the above-mentioned mass (B) is preferably silicon powder, especially such an average grain size of 0.3 µm to 30 µm, especially those with an average grain size of 1 µm to 10 µm, whole especially 2 µm to 7 µm.

Such silicon powder can by conventional comminution can be made from coarser grain silicon. Such methods can u. a. included the following steps sen: crushing in the jaw crusher, roller crusher, cone pulp cher, in the hammer mill, rod mill, drum mill, tube mill le, ball mill; Classification by air classifiers, hydrocyclones, Sieves; Atomizing silicon melt and the like.

The silicon used in the process according to the invention must do not meet high purity requirements. Outstanding it is suitable for this purpose as waste from the Rochow Synthesis of contaminated silicon. This has in generally a silicon content of about 60% by weight cent. Rochow synthesis is the direct synthesis of Me thylchlorosilanes by reacting methyl chloride with Silicon in the presence of copper as a catalyst.

This is used as component (B) in the process according to the invention elemental silicon is used in the coating mentioned tion mass preferably from 10 to 75 parts by weight, in particular from 25 to 60 parts by weight, each based per 100 parts by weight of component (A).

Preferably contains the in the inventive method settable component (A) a polyorganosiloxane, one too Polyorganosiloxane curable component and / or a copoly Mer resin from organosiloxane units and units from others organic resins.  

The polyorganosiloxanes or curable to polyorganosiloxane Ingredients can be mixed with organic resins such as Alkyd, acrylic, epoxy and phenolic resins can be used. As copolymer resins, also called combination resins, can the reaction products of organosilane and / or organo siloxanes with other organic resins, such as polyester, Alkyd and acrylic resins, and their prepolymers used become.

In this context, polyorganosiloxanes are in particular those of formula (1) preferred:

R _x (R′O) _y SiO _{(4-xy) / 2} (1),

where in the above formula mean
R are identical or different, optionally substituted C ₁ to C ₁₈ hydrocarbon radicals or hydrogen atoms,
R ′ identical or different radicals bonded to silicon via oxygen, namely optionally substituted C ₁ to C ₁₈ hydrocarbon radicals or hydrogen atoms,
x is an integer from 0 to 3 with an average value from 1.1 to 1.9,
y is an integer from 0 to 3 with an average value from 0.1 to 1.8,
with the proviso that the sum x + y has a maximum value of 2.5.

As curable components to polyorganosiloxanes are Organosilanes preferred which condensable groups contain. They are especially silanes or silane mixtures of formula (2):

R _z SiX _(4-z) (2), wherein

R has the meaning given above under formula (1),
X identical or different condensable groups, preferably halogen atoms, hydroxyl groups, C ₁ - to C ₄ - alkoxy groups, Si-ON-bonded di- (C ₁ - to C ₄ -alkyl) ketoxime groups, Si-OC-bonded C ₁ - bis C ₄ -acyloxy groups, Si-N-bonded groups of the formula -NH ₂₄ , -NHR and -NR ₂ , and
z is an integer of 0, 1, 2, or 3
and their partial hydrolysates and partial condensates.

Examples of the above-mentioned radicals R and R 'are alkyl residues, such as the methyl, ethyl, n-propyl, iso-propyl, n- Butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl, tert-pentyl; Hexyl radicals, such as n-hexyl rest; Heptyl residues, such as the n-heptyl residue; Octyl residues like that n-octyl and iso-octyl, such as the 2,2,4-trimethylpen tylrest; Nonyl radicals, such as the n-nonyl radical; Decyl residues, like the n-decyl radical; Dodecyl radicals, such as the n-dodecyl radical; Okta decyl radicals, such as the n-octadecyl radical; Alkenyl residues like that Vinyl and allyl; Cycloalkyl radicals, such as cyclopentyl, Cyclohexyl, cycloheptyl and methylcyclohexyl; Aryl radicals such as the phenyl, naphthyl, anthryl and Phe nanthryl residue; Alkaryl residues, such as o-, m-, p-tolyl residues, xylyl residues and ethylphenyl residues; Aralkyl radicals, such as benzyl rest, the α- and the β-phenylethyl radical; Examples of substituted radicals R and R 'are cyanoalkylre ste, such as the ß-cyanoethyl, and halogenated hydrocarbon material residues, for example haloalkyl residues, such as the 3,3,3- Trifluoro-n-propyl radical, the 2,2,2,2 ', 2', 2'-hexafluoroisopro pyl residue, the heptafluoroisopropyl residue, and haloaryl residues, like the o-, m- and p-chlorophenyl radical.  

Preferred examples of compounds of formula (2) are Tetramethyl silicate, tetraethyl silicate, methyl trimethoxysi lan, methyltriethoxysilane, phenyltrimethoxysilane, vinyltri methoxysilane, vinyltriethoxysilane, i-octyltriethoxysilane, Dimethyldimethoxysilane, methylphenyldimethoxysilane, diphe nyldimethoxysilane, chloropropyltrimethoxysilane, vinyltris (methoxyethoxy) silane, vinyl triacetoxysilane, N- (2-amino ethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-ami nopropylmethyldimethoxysilane, N- (cyclohexyl) aminopropyltri methoxysilane, methacryloxypropyltrimethoxysilane, glycidoxy propyltriethoxysilane, mercaptopropyltrimethoxysilane and de ren partial hydrolysates.

The used in the coating process according to the invention Set components (A) are preferably in the form of a Solution in organic solvent or in the form of an aq dispersion.

In the first case contains the in the inventive method mass used as component (C) at least one organic chemical solvent.

If solvents are used, they are solvents or solvent mixtures with a boiling point or boiling point range up to 120 ° C at 0.1 MPa preferred. Examples for such solvents are alcohols, such as methanol, etha nol, n-propanol, iso-propanol; Ethers such as dioxane, tetrahy drofuran, diethyl ether, diethylene glycol dimethyl ether; chlo hydrocarbons such as dichloromethane, trichlor methane, carbon tetrachloride, 1,2-dichloroethane, trichlorethylene; Hydrocarbons, such as pentane, n-hexane, hexane isomer mixture Sche, heptane, octane, white spirit, petroleum ether, benzene, toluene ol, xylenes; Ketones such as acetone, methyl ethyl ketone, methyl  isobutyl ketone; Carbon disulfide and nitrobenzene, or Ge mix these solvents.

The term solvent does not mean that everyone Components in this must solve. The reaction can too in a suspension or emulsion of one or more reak tion partners. The reaction can also occur in a solvent mixture with a mixture gap are carried out, with at least in each of the mixed phases at least one reactant is soluble.

Is the Kom to be used in the inventive method component (A) in the form of an aqueous dispersion, so preferably to stabilize this dispersion at least an emulsifier was added.

The following are particularly suitable as anionic emulsifiers:

• 1. Alkyl sulfates, especially those with a chain length of 8 to 18 carbon atoms, alkyl and alkyl ether sulfates with 8 up to 18 carbon atoms in the hydrophobic residue and 1 to 40 ethyl lenoxide (EO) or propylene oxide (PO) units.
• 2. Sulfonates, especially alkyl sulfonates with 8 to 18 carbon atoms men, alkylarylsulfonates with 8 to 18 carbon atoms, taurides, Ester and half ester of sulfosuccinic acid with one term alcohols or alkylphenols with 4 to 15 carbon atoms men; if necessary, these alcohols or alkylphenols can also be ethoxylated with 1 to 40 EO units.
• 3. Alkali and ammonium salts of carboxylic acids with 8 to 20 C atoms in the alkyl, aryl, alkaryl or aralkyl radical.  
• 4. partial phosphoric acid esters and their alkali and ammonium salts, especially alkyl and alkaryl phosphates with 8 to 20 carbon atoms in the organic radical, alkyl ether or alkane ryl ether phosphates with 8 to 20 C atoms in the alkyl or Alkaryl residue and 1 to 40 EO units.

The following are particularly suitable as nonionic emulsifiers:

• 5. Alkyl polyglycol ethers, preferably those with 8 to 40 EO units and alkyl residues from 8 to 20 carbon atoms.
• 6. Alkylaryl polyglycol ethers, preferably those with 8 to 40 EO units and 8 to 20 carbon atoms in the alkyl and Aryl residues.
• 7. Ethylene oxide / propylene oxide (EO / PO) block copolymers preferably those with 8 to 40 EO or PO units.
• 8. Fatty acids with 6 to 24 carbon atoms.
• 9. Natural products and their derivatives, such as lecithin, lanolin, Saponins, cellulose; Cellulose alkyl ether and carboxy alkyl celluloses, the alkyl groups of which each have up to 4 Have carbon atoms.
• 10. Linear organo (poly) siloxanes containing polar groups, especially those with alkoxy groups with up to 24 C- Atoms and / or up to 40 EO and / or PO groups.

The following are particularly suitable as cationic emulsifiers:

• 11. Salts of primary, secondary and tertiary fatty amines with 8 to 24 carbon atoms with acetic acid, sulfuric acid, Hydrochloric acid and phosphoric acids.  
• 12. Quaternary alkyl and alkylbenzene ammonium salts, esp special ones whose alkyl group be 6 to 24 carbon atoms sits, especially the halides, sulfates, phosphates and acetates.
• 13. Alkylpyridinium, alkylimidazolinium and alkyloxazoli nium salts, especially those whose alkyl chain up to Has 18 carbon atoms, especially the halides, sulfates, Phosphates and acetates.

The coating produced in the process according to the invention depending on the type and nature of the component (A), at room temperature or at elevated temperature be hardened. The coatings can be catalysts and contain other additives that accelerate this hardening gene.

Such additives can include acids, bases as well as condensates cation catalysts known metal compounds such as tin compounds, organotin compounds, titanium compounds, Organotitanium compounds and the like.

Examples of acids are Lewis acids, such as BF ₃ , AlCl ₃ , TiCl ₃ , Sncl ₄ , SO ₃ , PCl ₅ , POCl ₃ , FeCl ₃ and its hydrates and ZnCl ₂ ; Brönstedt acids, such as hydrochloric acid, hydrobromic acid, sulfuric acid, chlorosulfonic acid, phosphoric acids, such as ortho, meta and polyphosphoric acids, boric acid, selenic acid, nitric acid, acetic acid, propionic acid, halogen acetic acids, such as trichloro and trifluoroacetic acid, oxalic acid, p -Toluenesulfonic acid, acidic ion exchangers, acidic zeolites, acid-activated bleaching earth, acid-activated carbon black, hydrogen fluoride, hydrogen chloride and the like.

Examples of bases are Lewis bases, such as the hydroxyl ion, the methanolate ion and the ethanolate ion and the isopropanolate ion; Brønstedt bases such as alkali and alkaline earth metal hydroxides such as LiOH, NaOH, KOH, RbOH, CsOH, Mg (OH) ₂ , Ca (OH) ₂ , Sr (OH) ₂ , Ba (OH) ₂ , and amides such as sodium - and potassium amide, hydrides, such as sodium, potassium and calcium hydride; Tetrahydrocarbon ammonium hydroxides such as tetramethylammonium hydroxide and benzyltrimethylammonium hydroxide; Tetrahydrocarbon phosphonium hydroxides, such as tetramethylphosphonium hydroxide.

Is component (A) by condensation of organosilici connections can be hardened, in particular by condensation of compounds of the formulas (1) and / or (2), if the use of catalysts is desired at all or is advantageous as catalysts tetrahydrocarbon ammonium hydroxides and tetrahydrocarbon phosphonium hydroxides preferred.

If after applying the mass, the coating is increased Temperature is exposed to temperatures of 140 ° C up to 400 ° C, in particular from 180 ° C to 250 ° C, preferred.

The coatings produced according to the invention have compared to the conventional ones filled with zinc powder Advantage that the pigment does not match the other components reacted to form hydrogen. The invention Coatings are produced, at least if as Kom Component (A) compounds of the formulas (1) and / or (2) be set, even at temperatures up to at least 650 ° C resistant.  

use

The Be produced by the inventive method coatings can be applied to any type of metal to which polymer-based coatings have also been used up to now have been applied. Because of their high temperature resistance are those of those produced according to the invention Coatings which, as component (A), compounds of For contain (1) and / or (2), particularly suitable as High temperature coatings for all purposes for which one previously used zinc and aluminum as pigment.

In the examples below, if not each otherwise stated

• a) all quantities based on weight;
• b) all pressures 0.10 MPa (abs.);
• c) all temperatures 20 ° C.

Examples example 1

In a mixture of
14.0 g combination resin of a methylphenyl silicone resin and an epoxy resin (EPIKOTE® 1001 from Shell Chem. Comp.) In xylene with a solids content of about 50 wt.% And a silicone content of 50 wt.%, Based on the solids content (VP 4404 from Wacker-Chemie GmbH, Munich)
20.0 g of a mixture of aliphatic hydrocarbons (crystal oil K 30)
2.0 g butanol and
5.0 g tetra (n-butyl) titanate
were
35.0 g of technical silicon powder with a grain size of 7 microns and a silicon content of 98 wt .-% and
3.0 g hydrophobic fumed silica with a BET surface area of approximately 120 m ² / g (Wacker® HDK H 15)
stirred in rapidly at a speed of about 20 m / sec.

Example 2

In a mixture of
44.0 g of ethyl silicate with a viscosity of 37-38 mm ² / s at 25 ° C (TES 55 from Wacker-Chemie GmbH, Munich),
22.0 g crystal oil K 30,
22.0 g of ethyl glycol and
1.2 g acrylic plasticizer (Plexisol® PM 709 from Röhm GmbH, Darmstadt)
were
35.0 g technical silicon powder with an average grain size of 7 microns and a silicon content of 98 wt .-% and
1.0 g fumed silica with a BET surface area of 200 m ² / g (Wacker® HDK N 20)
stirred in rapidly at a speed of about 20 m / sec.

The coating compositions prepared in Examples 1 and 2 were placed on VA steel sheets with a 100 µm doctor blade After drying at room temperature, within 3 Heated to 1000 ° C for hours and cooled overnight. The Coatings adhered well to the steel sheets, though they warped strongly at the high temperatures.

Example 3

In 75 parts by weight of an emulsion of 50% by weight of water and 50% by weight of an emulsion of a medium-hard methylphenyl silicone resin with a content of 7% by weight of xylene, with a solids content of 42%, a viscosity of 40 mm ² / s, a nonionic emulsifier and an average particle size of approximately 1900 nm (Silres MP 42E from Wacker chemie GmbH, Munich)
25 parts by weight of technical silicon powder with an average grain size of 2 μm and a silicon content of 98% by weight were slowly stirred in using a 30 mm diameter dissolver disc. The mixture was then stirred at 4000 rpm for 10 minutes.

The coating agent was applied to a VA Sheet steel applied. Then 1 hour at room temperature temperature dried. Then was 1 hour at 200 ° C in Branded drying oven and in increments of each 100 ° C to 1000 ° C heated in air in a muffle furnace.

The coating adhered very well up to 800 ° C. At 900 ° C and The sheet warped at 1000 ° C and scaling occurred on.

Example 4

• a) In a mixture of
  44.0 g of ethyl silicate with a viscosity of 37-38 mm ² / s at 25 ° C (TES 55 from Wacker-Chemie GmbH, Munich),
  22.0 g crystal oil K 30,
  22.0 g of ethyl glycol and
  1.2 g Plexisol® PM 709
  were
  150.0 g of technical silicon powder with an average grain size of 7 microns and a silicon content of 98 wt .-% and
  1.0 g fumed silica with a BET surface area of 200 m ² / g (Wacker® HDK N 20)
  dispersed at a speed of about 20 m / sec.
• b) In a mixture of
  40.0 g of the methyl ester of a mixture of oligomeric methyl silicas of the average empirical formula CH ₃ Si (O) _1.1 (OCH ₃ ) _0.8 and a viscosity of 25-35 mm ² / sec at 25 ° C (Silres MSE 100 from Wacker -Chemie GmbH, Munich),
  3.0 g tetra (n-butyl) titanate and
  15.0 g xylene
  were
  10.0 g of silicon powder from Example 4a), 1.0 g of pyrogenic silica from Example 4a) and 30.0 g of talc
  dispersed at a speed of about 20 m / sec.
• c) In 75 g of an emulsion of a medium-hard methylphenyl silicone resin with a content of 7% by weight of xylene, with a solid content of 42% by weight, a viscosity of 40 mm ² / s, a nonionic emulsifier and a particle size of about 1900 nm (VP 4302 from Wacker-Chemie GmbH, Munich)
  were
  24.0 g of silicon powder from Example 4a),
  0.5 g silicone antifoam (S 1176 from Wacker-Chemie GmbH, Munich) and
  0.5 g of highly disperse silica with a BET surface area of 200 m ² / g was stirred in with a dissolver disk with a diameter of 30 mm. The mixture was then stirred at 4000 rpm for 10 minutes.

All coating agents were applied with a 100 µm doctor blade VA steel sheets applied. After that was 1 hour at room temperature dried. Then was 1 hour each at 200 ° C, then at 300 ° C and then at 400 ° C burned. All coatings adhered very well.

Treat them with the coating agent according to Example 4 c) Delten sheets were subjected to a salt spray test according to DIN 53210 subject. Table I below shows the results after 200, 500 and 1000 hours of salt spray test with VA steel sheets that have been treated at 200 ° C, 300 ° C or 400 ° C the. The rating number according to DIN 53210 is based on the Proportion of the surface affected by rust. Here means the rating number 0 = rustproof and 5 = more than 50% rust infestation. The coating agent of Example 4c is suitable as an anti-rust paint.  

Table I

Comparative Example 1

Examples 4a) and 4b) were repeated, the Silicon powder in Example 4a) by 400.0 g of zinc dust and was replaced by 10.0 g of zinc dust in Example 4b.

Zinkoli 615 from Stolberger Zincoli GmbH, GE, used.

The coating compositions were applied to VA Sheet steel applied and baked.

A water-based coating agent with zinc dust analog Example 4c) is not suitable for stoving because of a zinc-water reaction hydrogen is formed.

The sheets from Examples 4a), 4b) and the ent speaking comparative examples with zinc as a metal pigment were subjected to a salt spray test analogous to Example 4. In addition, the sheets were dried after drying at room temperature (20 ° C) tested. Table II shows the results. With a long test duration, here at 500 and 1000 hours, and  Silicon is a pigment at high baking temperatures also superior in rust protection.  

Table II

Claims (7)

1. Method for coating metals by applying a mass, which

• A) contains at least one polymer and / or at least one polymer-hardening component, characterized in that the composition also
• B) contains elemental silicon.

2. The method according to claim 1, wherein the mass as components te (B) silicon powder, preferably one of a medium leren grain size from 0.3 microns to 30 microns. 3. The method according to claim 1 or 2, wherein the elementary Silicon in the mass of from 10 to 75 parts by weight, each based on 100 parts by weight of the component (A) is included. 4. The method of claim 1, 2 or 3, wherein the components te (A) a polyorganosiloxane, one to polyorganosiloxane curable component and / or a copolymer resin Organosiloxane units and units of other organic Contains resins.   5. The method according to claim 4, wherein the component (A) contains a polyorganosiloxane of the formula (1) R _x (R′O) _y SiO _{(4-xy) / 2} (1), where in the above formula mean
R are identical or different, optionally substituted C ₁ to C ₁₈ hydrocarbon radicals or hydrogen atoms,
R ′ identical or different radicals bonded to silicon via oxygen, namely optionally substituted C ₁ to C ₁₈ hydrocarbon radicals or hydrogen atoms,
x is an integer from 0 to 3 with an average value from 1.1 to 1.9,
y is an integer from 0 to 3 with an average value from 0.1 to 1.8,
with the proviso that the sum x + y has a maximum value of 2.5. 6. The method according to any one of claims 1 to 5, wherein the Mass as component (C) at least one organic Contains solvents. 7. The method according to any one of claims 1 to 6, wherein according to Applying the mass the coating of elevated tempera is exposed.