DD252368A1 - ORGANIC PROTECTION LAYER FOR METALLIC REFLECTION AND / OR PROTECTION LAYERS - Google Patents

Abstract

The invention relates to an organic protective layer for metallic layers on glass, as they are used primarily for the production of color, gray and use mirrors. The aim of the invention is to improve the performance of metallic reflection and / or protective layers by an improved organic protective layer. The invention has for its object to provide an organic protective layer based on a paint. It has surprisingly been found that the organic protective layer according to the invention is formed by a single-coat paint which contains as binder a combination of an epoxy resin ester-amine resin system with a dicyclopentadiene-modified polyester resin and an epoxy resin.

Description

Field of application of the invention

The invention relates to the protection of metallic layers on glass, as they are used primarily for the production of color, gray and use mirrors. In this case, both the metallic reflection layers as well as possibly any further metallic protective layers are to be protected. Another field of application relates to the general application of the solution defined according to the invention for the protection of mineral substrates against the action of water, water vapor and corrosive media, especially at elevated temperatures.

Characteristic of the known technical solutions

In order to obtain organic protective layers for metallic reflection and / or protective layers on glass, use is made of single-layer and multi-layer coating systems which are applied by means of different application methods. Both paints based on fatty acid-modified alkyd resins, epoxy resins, epoxy resin esters and alkyd-amiri resin systems, epoxy resin-amine resin systems, acrylic resins or acrylic-alkyd resin combinations are known.

These paint systems have insufficient resistance to stress from water vapor of varying saturation or condensation on said substrates. This manifests itself in blistering and cracking as well as adhesion reduction followed by partial or complete detachment of the organic protective layer and as a result in the destruction of the metallic reflection layer. Even the complex multi-layer structure of such protective layers can only partially remedy this deficiency.

As a result of this instability, the useful life of the metallic reflection and / or protective layer is significantly reduced.

Object of the invention

The aim of the invention is to extend the service life of metal Refexions- and / or protective layers on G las by an improved organic Schutzscicht, which is obtained by a single-coat application of a coating material, even under extreme water vapor or Schwitzwasserbelastung.

Explanation of the essence of the invention

The invention has for its object to provide an organic protective layer for metallic reflection and / or protective layers on glass based on a paint, which in particular has improved adhesion and extended protection against the metallic reflection and / or protective layer.

Surprisingly, it was found that the organic protective layer of the invention WHA formed by a single layer to be applied pigmented paint which contains as binder a combination of the unknown per se epoxy resin ester-amine resin system with a dicyclopentadiene-modified polyester resin and an epoxy resin. The paint according to the invention has the following composition: 10-16% of a fatty acid-modified epoxy resin (epoxy resin ester)

4-10% of an amine resin

5-10% of a dicyclopentadiene-modified polyester resin having at least 20% dicyclopentadiene content 2-8% of an epoxy resin

37-41% inorganic and / or organic pigments and fillers 42-15% organic solvents

As fatty acid-modified epoxy resins conventional epoxy resin esters can be used. Preference is given to resins made from conjugated unsaturated fatty acids such as Rizinenfettsäure and medium molecular weight epoxy resins based on dian. As the amine resin, there can be used the known aminoplast lacquer resins suitable for heat-pressed and stoving paint systems. Preference is given to using melamine-formaldehyde resins of medium reactivity. Suitable dicyclopentadiene-modified polyesters are esterification products which may contain at least 20% of dicyclopentadiene, further customary raw materials such as dicarboxylic acid, polyalcohols, fatty acids, oils, etc. Preference is given to oil-free or polyesters with a maximum of 25% fatty acid, which are prepared from dicyclopentadiene, unsaturated dicarboxylic acids and dihydric alcohols.

As epoxy resins, the usual aromatic and aliphatic epoxy resins can be used. Preferably, medium molecular weight resins based on dian and epichlorohydrin are used. As inorganic and / or organic pigments and fillers, the generally known products can be used, such as. As titanium dioxide rutile, talc, Chromoxidgrün, iron oxides, acetylene black, barite, etc. Preferably, inert pigments and fillers are used. As organic solvents, the usual solvents in paint chemistry such as aliphatic and aromatic hydrocarbons, esters, ketones, etc. can be used. In addition to the listed constituents of the pigmented paint, the usual paint assistants can be used in a minor amount.

The paint according to the invention can be applied electrostatically by means of all customary application methods, but in particular by casting, flooding, dipping, rolling and spraying. The formation of the protective layer is preferably carried out by a thermal crosslinking process.

With the composition according to the invention, a well-adhering organic protective layer which can be applied by the above-mentioned application methods can be produced, which preferably forms a protective film for metallic reflection and / or protective layers by thermal crosslinking, which has excellent resistance to climatic influences, in particular water vapor or condensation. This result is surprising and could not be expected in any way. According to the known state of the art, the characteristic binders mentioned at the outset either alone or in combination with amine resins do not even approximately withstand the high loads as well as the combination according to the invention. However, dicyclopentadiene-containing polyesters, alone or in combination with amine resins, also completely fail under these conditions.

embodiments

The examples below contain paints made from 50 parts by weight of pigments (70% titanium dioxide rutile and 30% microtalkum) and 25 parts by weight of binder based on the solvent-free resin combination. The paints are adjusted to spray viscosity with mixtures of xylene, cyclohexanone and ethyl glycol acetate, thus coating the metallic reflection layer on glass. The organic protective layers are obtained by thermal crosslinking for 30 minutes at 180 ⁰ C. Their layer thickness is 45 ± 5μ.Γη. The assessment of the organic protective layers is carried out according to:

a) DIN 1238 (April 1983)

The condensation and salt spray tests are carried out over a period of 480 hours.

b) Cuttability of the glass samples

The nature of the protective layer at the cutting edge is described.

c) sandability over an edge length of 10cm

The nature of the protective layer on the abrasive edge is described. The paint according to the invention contains the following binder combination (paint 1): 11.1 parts of epoxy resin ester (solvent-free)

4.9 parts of amine resin (solvent-free)

3.3 parts of dicyclopentadiene-modified polyester (solvent-free)

5.7 parts epoxy resin (solvent free)

The epoxy resin ester used is a medium-molecular dianepoxide (epoxide equivalent weight 875) modified with about 40% of ricinium fatty acid.

The amine resin used is a butanol-etherified melamine-formaldehyde resin of moderate reactivity. The modified polyester is a reaction product of 1,3-butanediol and a; / 3-unsaturated dicarboxylic acid modified with about 30% dicyclopentadiene.

This reaction product has an acid value of 16.3 mgKOH / g, a viscosity of 225OmPa.s (2 ° C.) at a solids content of 75.1% by mass in xylene

 The epoxy resin used is a medium molecular weight dian epoxy resin (epoxy equivalent weight about 450).

In comparison, a paint (paint 2) was prepared with the following binder composition: 15 parts of dicyclopentadiene-modified polyester (solvent-free) from Example 1

5 parts of epoxy resin (solvent-free) from example 1 5 parts of amine resin (solvent-free) from example 1

As a further example of comparison (paint 3), a paint having the following binder combination was prepared: 29.8 parts of epoxy resin ester (solvent-free) from Example 1

4.2 parts of amine resin (solvent-free) from Example 1

Test results from paint

Condensation water according to DIN 1238

Salt spray test according to DIN 1238

Schneibarkeit

grindability

1 (according to the invention

2 (comparison)

3 (comparison)

500 h existed after 250 h of film destruction,

after 350 h of film destruction

500 h existed after 200 h staining

after 300 h

spotting

error-free spalling

flawless

flawless

unclean

grinding edge

light

spalling

flawless

The test results of the protective layers obtained from the coating materials demonstrate the significant increase in the performance properties of the organic protective layer according to the invention.

The protective effect against water vapor and Schwitzwasserbelastung and corrosive atmosphere (salt spray test) is increased over the prior art by at least 50%.

The inventive combination in the formulation of the paint has also been subjected to extensive testing for metallic reflective and / or protective coatings prepared under industrial production conditions.

The following metallic substrates were included: aluminum, silver, copper, titanium, brass, bronze, V2A steel.

The characteristic results of the tests are given in the table above.

Claims (6)

1. Organic protective layer for metallic reflection and / or protective layers on glass based on a single-coat paint applied, characterized in that this paint from 10-16% of a fatty acid modified epoxy resin 4-10% of an amine resin 5-10% of a polyester modified with at least 20% dicyclopentadiene 2-8% of an epoxy resin 37-41% of inorganic and / or organic amounts of pigs and fillers 42-15% of organic solvents
consists. 2. Organic protective layer according to item 1, characterized in that the fatty acid-modified epoxy resin used is preferably a conjugated with about 40% unsaturated fatty acid-modified dianepoxide. 3. Organic protective layer according to item 1 and 2, characterized in that is preferably used as the amine resin etherified melamine-formaldehyde resin. 4. Organic protective layer according to item 1-3, characterized in that the modified polyester is preferably a crosslinked product of at least 20% dicyclopentadiene, an a; ß unsaturated dicarboxylic acid and a dihydric alcohol is used. 5. Organic protective layer according to item 1-4, characterized in that a medium molecular weight dian epichlorohydrin epoxy resin is preferably used as the epoxy resin. 6. Organic protective layer according to item 1-5, characterized in that are preferably used as inorganic pigments, titanium dioxide, rutile, talc, Chromoxidgrün and iron oxides alone or in combination with other inert pigments and fillers.