DE1519390B2 - STOVE-ON COATING MIXTURE - Google Patents

Description

The invention relates to a stovable coating mixture, consisting of a solution of phosphoric acid, in which (A) at least one metal chromate, metal dichromate or metal molybdate or mixtures of these compounds and (B) oxide, hydroxide, orthophosphate or monophosphate of magnesium, Aluminum hydroxide, aluminum orthophosphate, zinc hydroxide or zinc phosphate or mixtures of these Compounds and optionally other additives are present. In particular, it relates to mixtures that are to a high degree suitable for coating various, in particular metallic, surfaces, and a protective effect or the like or as a primer for applying certain other Materials can be used on the surfaces in question.

The previously available inorganic and organic coating materials were consistently subject to one or several physical limitations on their thermal and / or mechanical ability Processing or deformation without destroying the bond between the coating and the base layer to suffer. The properties of known coatings and binders were also considered on the dielectric or electrical conductivity often insufficient to meet the various requirements to suffice. The extent of the chemical compatibility of known coating materials was also, be it in relation to the documents themselves or in relation to those which may be contained in the coatings Additives, extremely limited.

It is already known that when iron surfaces are used as a substrate for paintwork, they can be closed passivate and phosphate. In "Fette und Seifen", No. 1, 1951, p. 22ff., It is said that the corrosion protection of all passivation layers is only limited and that it is unclear under which Conditions the corrosion resistance of phosphated layers become effective. Also in the German Patent specification 641 725, the Italian patent schi ift 494 010, the French patent specifications 824 517 and 1,066,186 as well as the US Pat. No. 2,030,601 described coating agents for iron, steel and other substrates all have disadvantages in terms of thermal load capacity and their resistance to corrosion.

Even the paint described in Italian patent specification 380 187 is not sufficiently resistant, if it is subjected to temperatures and temperature changes such as those described in e.g. B. in aircraft engines appear.

The invention makes the development in the field of such coating materials a considerable one

ίο step forward, the many new opportunities to create surfaces that meet today's technological requirements with available materials. With the mixtures according to the invention it is it has become possible to produce composite materials, their heat, abrasion, corrosion and strength properties, weight, mechanical deformability as well as their properties in chemical, electrical and nuclear physics terms so far practically were not achievable.

The invention relates to a stovable coating mixture consisting of a solution of Phosphoric acid, in which (A) at least one metal chromate, metal dichromate or metal molybdate or Mixtures of these compounds and (B) oxide, hydroxide, orthophosphate or monophosphate of Magnesium, aluminum hydroxide, aluminum orthophosphate, zinc hydroxide or zinc phosphate or Mixtures of these compounds and optionally other additives are present, which are characterized is that the solution is finely divided aluminum powder with a maximum grain size of 150 μ. contains. Provided Firstly, if the mixtures according to the invention are used primarily for binding purposes, they can for joining metals, secondly for joining semi-metals and thirdly for joining non-metallic materials, d. H. all solid inorganic substances not mentioned under 1 and 2 Materials, serve.

The metallic, intermetallic and non-metallic materials added to the basic mixtures can be viewed as additives or fillers, which are selected depending on the respective requirements. One of the most important aspects of the mixtures according to the invention is their relatively universal applicability, so that they can be used in combination with different additives or fillers, including multiple additives with a large number of substrates, the surfaces of the substrates to be coated having certain desirable properties, such as particularly dielectric and emission behavior, poor thermal insulation properties, chafing and seizure preventing properties, lubricity, electrical conductivity, corrosion resistance, oxidation resistance, erosion resistance, radiation absorption, etc. are imparted.
The mixtures can be applied by brushing, dipping and spraying. They dry and solidify in the air and can go through. Heating to temperatures between 120 and 320 ° C in a period of 1 to 60 minutes. They are non-flammable and do not contain any components that give off fumes that are toxic when used.

The coatings according to the invention form a film that is highly resistant to the chemical

3 4

Exposure to liquids, such as distilled water, cut, bent and coated sheet metal Hydrocarbons and other organic solvent spot welds, so that a continuous, Motor oil, hydraulic fluids, lent ceramic-metallic coated surface degreasing oil etc., is resistant, even if this substance holds against the exhaust gases from engines act long-term. Such a film shows no 5 corrosion resistance.

Blistering, no softening and no other albeit the mixtures according to the invention

Decomposition when the air temperature is particularly high for coating and bonding metallic

at least 1400 ⁰ C or at high speed surfaces are suitable and many below

is exposed to air friction, as in the application examples described on a metallic

Sheathing of missiles and related to jet propulsion underlay, however, is the invention

works is the case. ■■■ - under no circumstances should the coating and joining of metal

Limited by the addition of aluminum powder according to the lischer surfaces. The invention

Invention surprisingly a hitherto still mixtures were in fact successful with non-

never achieved combination of desirable metallic surfaces such as plastic, paper,

physical properties achieved, in particular 15 fiberglass, wood, and with ceramic materials

a very high heat resistance in connection, etc. connected.

with a practically unlimited resistance to corrosion. As an acidic component of the base mixes

A coating according to the invention can easily affect preferably 85 ° / _o orthophosphoric acid, H ₃ PO _4,

Impairment of its properties using constant temperature aqueous solution.

are subject to change of direction. Even at mechanical ² ° It has been found that under certain

Damage to the coating does not result in corrosion. Conditions an anhydrous or pure acid solution

instead of at the point of damage, which z. B. the case when may be desirable or necessary. At a

a paint composition according to the invention limited number of metallic substrates on

Application in place of aluminum powder with one of the mixtures according to the invention applied

other powders with electrical conductivity, it was found, for example, that an un-

puts. It is not yet fully understood what this desired reaction between the document and the

surprising effect of the additional coating according to the invention can be avoided if a water-

rate is due. free mix is used.

The burned-in film is in water and in orga- If anhydrous mixtures are used,

Insoluble in niche solvents. 30, the bond achieved is about as good as if the

With the addition of aluminum alloy according to the invention, aqueous mixtures have been used; In general, however, the non-aqueous metallized, ceramic coating, which is less universally usable in simple mixtures, e.g. B. can be applied to a steel sheet. When producing the finished product from the over 35 as they are suitable for a smaller number of documents than the aqueous mixtures,
With regard to the compounds of group (B) relatively small bending radius and cutting, a preferred mixture contains a mixture of shearing and welding work, magnesium oxide and magnesium phosphate,
without destroying the bond between the metal and the subsequent coating. So z. B. Exhaust 40 listed coating and binding mixtures consists of pots for motor vehicles. It is therein that, if necessary, other inorganic impairing constant unsolved problem, non-corrosive components can be added, thereby producing additional mufflers in an economical manner. borrowed, specific properties can be achieved. Attempts have already been made to mention the pigment substances that are currently being discussed. Substances such as the position of mufflers used inexpensive 45 aluminum oxide, boron nitride or molybdenum disilicide, steel after the manufacture of the muffler to give the coatings heat resistance and pull. This attempt, however, has various levels of abrasion resistance. In addition, additives cannot lead to the reasons so far unsuccessful. If coatings have dielectric or emission properties, sufficient time and care is taken to give a gap or the like.

loose, non-corrosive and abrasion-resistant coating 50 In the preferred embodiment of the invention

to be produced with certainty, the coating mixture according to the production method is used.

cost of the muffler prohibitively high. If one carries the magnesium dichromate before in the hexahydrate form

on the other hand after the production of the muffler and thus corresponds to the chemical formula MgCr ₂

a relatively inexpensive coating, so O ₇ 6 H ₂ O.

It is often the case that small corner areas or 55 If improved heat resistance is desired inaccessible areas are not coated. Is on, the aqueous solutions above can be used The Korro composition sets finely divided, inorganic substances in these uncoated areas sion a. As soon as the corrosion started on an exhaust pipe such as aluminum oxide, zirconium oxide, boron nitride, molybdenum the others can also be added with a disilicide and the like in amounts of 10 to 200 g Coated areas of further corrosion 60 become.

Put more curbs as these are below the The preferred blends according to the invention

Coating progresses. comprise an aqueous solution of the orthophosphorus

The coating mixtures according to the invention leave acid in combination with magnesium dichromate as

easily apply to inexpensive steel sheets, compound of group (A) and with a mixture

which creates a coating that, compared to the 65, consists of equal parts of magnesium oxide and

extremely aggressive chemicals contained in the exhaust- sium monophosphate as compounds of group (B).

system of internal combustion engines exist, this combination is used primarily because of their

is corrosion resistant. In addition, the great universality can be given preference. With others

In words, this basic mixture can be combined with more bases and more additives than any other known form.

If other compounds of group (A) and (B) 'are combined as desired, the resulting mixtures are applicable to not so many documents. If the latter, a little less preferred mixtures are compatible with certain documents, however, is the integrity and quality the bond is essentially as good as the preferred blend.

In general, the coating and adhesive mixtures according to the invention have what is required Constituents approximately in the amounts given below, which illustrate the invention as examples.

The following examples 1, 2 and 3 represent preferred base mixes of the coating and Binding mixtures, to which aluminum powder is then added. They have the following composition :

example 1

Water, H ₂ O, distilled ... 80 ecm

Orthophosphoric acid, H ₃ PO ₄ 20 ecm

Magnesium dichromate hexahydrate, MgCr ₂ O ₇ · 6 H ₂ O 15 g

A mix of the same
Parts of magnesium oxide, MgO, and magnesium monophosphate,
MgH ₄ (PO ₄ ), · 3 H ₂ O .... 10 g

B e i s ρ i e 1 2

Orthophosphoric acid (85%) 1 part

Water 3 to 6 parts in one

Part orthophosphoric acid

Magnesium dichromate - hexa-

hydrate 8 to 20 g to 100 ecm

Water-acid solution

Magnesium oxide 2 to 10 g per 100 ecm

Water-acid solution

Example 3

Water 80 ecm

Orthophosphoric acid (85 ° / _o solution) 20 cc
Magnesium dichromate hexa-

hydrate 15 g

Magnesium oxide 5 g

not attacked by the action of water, organic solvents and other liquids mentioned at the beginning. They have a good thermal stability, sufficient to destruction of the bond or an otherwise decomposition both at low temperatures in the order of -180 ° C and at high temperatures of the order of 1400 ⁰ C, provided that suitable Additives used to prevent. Furthermore, the coated surfaces are protected from corrosion. If the coating according to the invention is placed on a suitable substrate, e.g. If, for example, steel is applied, a corrosion-resistant material is obtained that can be bent and welded, making it possible to manufacture a wide range of products that can withstand temperatures of the order of 1000 ° C.

Example 4

Water, H ₂ O 3 to 6 parts of water

to one part of phosphoric acid

8 to 20 g per 100 ecm water-acid solution

30th

45

50

When preparing the mixtures, the commercially available orthophosphoric acid is preferably used Diluted water to reduce its specific gravity to 1158 to 1131 g / cc. Then become the remaining components according to example 1 or 2 are dissolved in the dilute phosphoric acid solution or suspended.

The applied films according to the invention are bonded to the metal surfaces in a relatively moisture-free atmosphere at an ambient temperature of about 27 ° C. After air drying, the layers can by heating to temperatures of 120 to 32O ⁰ C, are cured, preferably 210-320 ⁰ C, in a period of 1 to 60 minutes. In general, the higher the temperature selected, the shorter the required curing time.
The cured layers or films are orthophosphoric acid (85%);

H ₃ PO ₄
Magnesium dichromate hexa-

hydrate, MgCr ₂ O ₇ · _{6H 2} O

A mix of the same
Parts of magnesium oxide, MgO, and magnesium monophosphate,

MgH ₄ (PO ₄ ) ,, · 3 H ₂ O 2 to 10 g per 100 ecm

Water-acid solution

Aluminum powder 80 tol00gaufl00ccm

Water-acid solution

A mixture according to the previous statements has the following composition, for example:

Example 5

Water, distilled 80 ecm

Orthophosphoric acid (85%) 20 ecm
At least one connection

of group (A) 15 g

At least one connection

of group (B) 10 g

Aluminum powder 80 g

A preferred variant of the above composition is shown in the following example:

Example 6

Water, distilled 80 ecm

Orthophosphoric acid (85%) 20 ecm

Magnesium dichromate hexahydrate

A mix of the same
Parts made of magnesium oxide
and magnesium monophosphate 10 g

Aluminum powder 80 g

With the aforementioned mixtures produced using aluminum powder, remains preserve the electrical conductivity of the aluminum. So if the coating is on a metallic base, z. B. steel, is applied, it is possible to spot weld the coating material without the corrosion-resistant Adhesive layer is torn. aside from that

15 g

7 8

is in the mixtures that usually in the mixtures according to the invention alone or in

Aluminum powder occurring exothermic reaction combination can be added to the finished

avoided. Coating additional, specific properties such as

Other additives such as carbides, oxides, abrasion resistance, electrical resistance, radiation

Borides, nitrides, etc. can impart resistance, etc. to the aqueous solutions. -Ϊ

Claims (2)

Patent claims: 1. Baked-on coating mixture, consisting of a solution of phosphoric acid, in which (A) at least one metal chromate, metal dichromate or metal molybdate or mixtures of these Compounds and (B) oxide, hydroxide, orthophosphate or monophosphate of magnesium, aluminum hydroxide, Aluminum orthophosphate, zinc hydroxide or zinc phosphate or mixtures these compounds and optionally further additives are present, characterized in that that the solution is finely divided aluminum powder with a maximum grain size of 150 μ contains. 2. Coating mixture according to claim 1, characterized in that it is an aqueous phosphoric acid solution contains.