EP1523457A1

EP1523457A1 - Solvent-free method for hydrophobic color coating of glass granulates, product therefrom and use thereof

Info

Publication number: EP1523457A1
Application number: EP03783916A
Authority: EP
Inventors: Andreas Schultze-Kraft
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-07-12
Filing date: 2003-07-10
Publication date: 2005-04-20
Also published as: DE10393341D2; AU2003254624A1; DE10231858A1; WO2004014815A1

Abstract

Disclosed is a simple, energy-saving, environmentally compatible and industrially safe method wherein glass granulates, preferably made of recycled glass, are color coated with a mixture of solvent-free, aqueous, dual component epoxy resin, water and colorant preferably an inorganic coloring pigment or with a mixture of solvent-free, aqueous, dual-component epoxy resin, an aqueous emulsion containing siloxane, a fine-grained powder made of glass and/or aluminum hydroxide and (preferably mineral) coloring pigment. The degree of water repellence can be established by a simple test. The products produced according to said method can be used for a variety of purposes as additives for organically and inorganically bound mortar, plaster mortar and base coatings and for moulded items and coatings made of concrete polymer or polymer artificial stone structured like granite.

Description

Solvent-free process for the hydrophobic color coating of glass granules, the product thereof and its use

description

The invention relates to a solvent-free process for producing hydrophobic color-coated glass (preferably recycled glass) granules, the hydrophobic or superhydrophobic color-coated glass granules produced by this process as products thereof and the use of these products.

BACKGROUND Colored sands or chips made of natural stone, from which cemento-hydraulic, pozzolanic or organically bound products - eg. As terrazzo floors, plaster or surface-finishing concrete coatings can produce nature only in a limited range of shades. To extend this spectrum, was the many years ago

Possibility discovered and used, relatively colorless but opaque, non-transparent natural stone sands or -Splitte, primarily quartz sand, coated with pigmented organic binder to color these as appearance-determining additives for inorganic or organic bound plaster and screeds and moldings and coatings out

Polymer concrete or granite-like structured polymer artificial stone use. Such colored sands or splits are z. B. under the name "colorite quartz" generally known.

An essential motive for the present invention was the recognition that for the coloring of an opaque, ie non-transparent mineral grain significantly more color pigment - and thus color pigment-binding binder - is needed than for the coloring of a transparent grain of glass: For a superficially dyed Non-transparent quartz grain is only visually appealing to the surface of the viewer, but not to the back surface, since the color pigments adhering to the back are removed from the visual perception by the opacity of the grain. In the case of a superficially colored transparent glass grain, on the other hand, the color pigments applied all over add up to the overall color impression, since, especially with a very thin and thus slightly translucent color coating, the color pigments applied to the back are optically perceived.

Experiments have shown that in order to obtain an equally intense optical color impression, the coloration of a transparent glass grain requires only 30-40% of the color pigment amount required for coloring a non-transparent quartz sand grain. The amount of binder required is correspondingly lower in order to bind the color pigments to the grain to be dyed. Thus, for example, for dyeing 1 kg of silica sand in the grain size range 0.8-1.5 mm, about 35-50 g by color coverage power of the color pigment) dyeing agent (= binder + pigment) is required for coloring 1 kg of colorless-transparent glass granules same size range but only 18 - 25 g.

The advantages of color-coated glass granules compared to color-coated natural sand are also very evident when the material is used as an appearance-determining additive for abrasion-stressed end products, eg. B. for floor coatings or surface-finished paving stones is used:

With color-coated natural sand or -splitt the use-related surface abrasion leads first and foremost to the abrasion of the top layer of paint, so that the natural color of the natural sand or split appears and the color-optical impression increasingly changed or distorted.

On the other hand, when using color-coated glass granules as the dominant aggregate, no noticeable color change occurs due to the surface abrasion, since the color pigment applied on the back and on the side also determines the color-optical impression.

An important motive for the process according to the invention, the products resulting therefrom and their use was not least the fact that, according to the invention, color-coated glass granules can easily be made from recycled glass - even from so-called "inferior" waste glass fractions, which are not suitable for conventional glass recycling in the glassworks but currently still costly to be disposed of in landfills.

REQUIREMENTS OF PROCEDURE AND PRODUCT

According to the motivation, which was not only economically but also ecologically oriented, the inventive task was also seen as rationally to make the process for hydrophobic color coating of recycled glass granules environmentally friendly, energetically economical, occupational safety and security as possible. This means in detail:

• The process should be single-layered, i. do not require adhesion-promoting priming of the glass granules.

• The process should consistently avoid the use of solvent-containing substances in order to avoid polluting

To cause emissions, not to endanger workers' health and to exclude the risk of serious industrial accidents (explosive ignition of solvent vapors).

• The method should be feasible with the least possible expenditure of energy, in particular thermal energy. This is especially true for the required to dry the paint coat hot air effect. The complete dehumidification should take place at the lowest possible hot air temperature and the shortest possible exposure to warm air.

Critical criteria for the process to be invented and the product to be produced by this process were, above all, the specific requirements placed on this product.

It should be created a color-coated glass granules, which

- in contrast to all known color-coated glass granules - combines the following properties: 1. The colored coating should not only be non-hygroscopic, ie absorb moisture from the ambient air. It should not only be waterproof, ie in an aqueous environment do not dissolve or swell or absorb water in appreciable amount. But it should also repel water, ie its surface is a clearly hydrophobic

Feature.

2. The colored coating should permanently adhere firmly to the glass grain, even with high fluctuations in the ambient temperature - z. In the range between -25 ° C and + 85 ° C. 3. The colored coating should have a high abrasion resistance, so that it does not dust or bleed even under possibly high mechanical stress by compulsory mixing processes in the course of further processing of the color-coated glass granules. 4. The colored coating should have a good chemical resistance, d. H. the colored coated glass granules should be diluted with diluted alkalis and

Acids, salts and aggressive organic substances (such as monostyrene or methyl methacrylate), which could act on the granules during further processing to final products or in the application of the final products, be sufficiently resistant.

STATE OF THE ART

Methods are known for baking finish of glass surfaces or for melting colored pigments on glass surfaces. Possibly, such processes could also be applicable to glass granules.

However, they are not relevant in terms of the invention goal set here, since they are technically complex and require a high use of thermal energy.

Not relevant within the meaning of the aim of the invention are also all conceivable color coating methods using solvent-based synthetic resins. These include solvent-based epoxy or polyurethane systems as well as reaction resin systems such as unsaturated polyester resins or Polymethylmethacrylatharze containing in the unpolymerized state evaporative, usually foul-smelling and hazardous to health substances such as monomeric styrene or methyl methacrylate or release them in the course of the polymerization.

From DE P 4402 432, granite-like polymer artificial stones made from coated waste glass granules are known, whereby the coating of the old glass splinters:

from an aqueous solution of alkali metal silicates (= water glass) or an aqueous dispersion of acrylic copolymers, preferably

Styrene acrylate or a mixture of these two substances as a binder,

Dye (preferably inorganic pigments)

- As well as an outwardly compacting filling of transparent and / or opaline bright fine fillers of mineral origin composed.

The cited formulations do not meet the requirements described above for the product according to the invention: water glass is hygroscopic and water-soluble, mixtures of water glass and aqueous acrylate dispersions are likewise hygroscopic or water-absorptive.

By contrast, pigment-filled aqueous acrylate dispersions are less susceptible to moisture after they have cured. Coated surfaces tend to swell only after prolonged exposure to moisture. As a glass coating, however, they have no optimal adhesion to the glass and thus also no high abrasion resistance.

In addition, they are not sufficiently resistant to chemicals but can be dissolved by many aggressive chemical substances and organic solvents. None of the coating systems known from DE P 44 02432 fulfills the hydrophobic surface property of the color-coated glass granules required in the present case as an essential feature of the invention. WO 01/14277 describes surface-finished concrete blocks which are provided with a polymer artificial stone layer. This finishing layer contains, as appearance-determining main filler, waste glass granules which are produced by means of an aqueous dispersion of polyvinyl acetate and

(Preferably inorganic) color pigments was oberfiächig colored. However, this coating system for glass granules can not meet the requirements imposed on the invention presented here: Aqueous polyvinyl acetate dispersions - whether dyed or undyed - are slightly hygroscopic after drying. They swell when exposed to water, the surface of the coating is not hydrophobic. In addition, they react saponifying to alkaline influences and are sensitive to many aggressive organic substances such. For example, methyl methacrylate.

THE INVENTION SOLUTION

It has been found that all the requirements described above for the solvent-free process according to the invention for the hydrophobic color coating of glass granules are fulfilled by mixing the glass granules with a mixture of a solvent-free, aqueous, two-component epoxy resin system, water and dye (preferably inorganic mineral pigment).

- or with a mixture of a solvent-free, aqueous, two-component Epoxidharzsystem, an aqueous siloxane-containing emulsion, dye (preferably inorganic mineral pigment) and, if necessary, fine-grained powder of glass and / or aluminum hydroxide - coated, dehydrated and cured by reaction ,

By solvent-free, aqueous two-part epoxy resin systems are meant reaction-curing epoxy resin systems in which at least one of the two solvent-free components-the parent component or the hardener component-is dispersed or emulsified in water so that the solvent-free epoxy resin system can be diluted with water and / or solvent-free aqueous additives. It has been found that all the requirements described above, which are imposed on the product to be produced according to the invention, are fulfilled by producing the product - color-coated (recycled) glass granules having a hydrophobic surface - by the same process. Investigations have shown - in part surprisingly - that solvent-free, aqueous two-component epoxy resin systems - eg a polyamine-epoxy adduct and a mixture of bisphenol A-epichlorohydrin resin, p-tert-butylphenyl glycidyl ether and benzyl alcohol ^■ in the dehydrated and reaction-cured state have very good adhesion and abrasion resistance on glass surfaces, even if such

Resin systems were additionally diluted with up to 30% by weight of water prior to use and filled with up to 100% by weight of colored pigment (preferably inorganic mineral pigment). It has been found that glass granules coated with such a water-diluted and pigment-filled resin system dehumidify completely with little use of thermal energy (eg at a hot air temperature of 60-80 ° C.) in a very short time (eg up to 90 seconds) to let. The color-coated glass granules are dust-dry and non-sticky after cooling, so that the time-dependent reactive curing of the resin system in a storage vessel at ambient air temperatures> 10 ° C can take place without supply of thermal energy.

It has been found that the color coating of the granules after reaching the final strength not only has a strong adhesion and abrasion resistance but also a high chemical resistance and especially a clearly hydrophobic property of the surface. It has been found that the hydrophobic surface property of the color-coated glass grains according to the invention can be increased to a "superhydrophobic" property by enriching the described color coating with siloxane molecules:

In this case, the solvent-free, aqueous, two-component and pigment-filled epoxy resin system is not diluted with water but with a very low-viscosity, siloxane-containing aqueous emulsion, for example, an aqueous methylalkylsiloxane / acrylic acid ester copolymer

Emulsion.

The siloxane molecules bind to those contained in the coating mixture

Mineral pigments. For dyeing, no mineral pigments but e.g. organic pigments used, it is necessary that the mixture feinst- granular, as colorless as possible, powder of mineral origin, for. As glass and / or aluminum hydroxide and / or natural or synthetic mica is added so that the siloxane molecules find a binding partner. When using aluminum hydroxide, there are advantages in terms of the fire behavior of the coating: the flammability is reduced, self-extinguishing is favored.

In a special embodiment of the subject invention, the binder is mixed not only mineral color pigment and / or mineral fine filler of glass and / or aluminum hydroxide and / or mica but also metallic pigment -. Aluminum powder - or fine platelets made of - uncoated or epoxy-coated - aluminum foil. The addition of metallic pigment gives the coated granules a metallic luster comparable to that of electrically oxidised aluminum.

The addition of very thin platelets of aluminum foil (for example platelets in the format 200-600 μm × 200-600 μm × 5-15 μm) causes an optically effective partial mirroring of the glass granule grains.

BENEFITS AND CRITERIA OF HYDROPHOBIA

The color-coated glass granules according to the invention are primarily suitable for use as appearance-determining main additives for plaster or screeds bound in organic or inorganic form, as well as for moldings and facing layers made of polymer concrete or granite-like structured polymer artificial stone. Of course, such end products should also be suitable for outdoor use exposed to the weather. It can not be ruled out that the color-coated glass granules are processed into granite-structured end products whose microstructure is interspersed with fine capillary pores. This can be done, for example, if a very "lean", ie low-binder polymer mortar was not compacted with sufficient pressure or if the grading curve of the aggregates has too small a proportion of fine filler.

Water could penetrate through these capillary pores, which leads to long-term damage to the microstructure, especially in connection with frost / thaw changes. This danger is effectively prevented by the inventive hydrophobic color coating of the glass granules as the main additive: The water-repellent property of the glass grain surfaces prevents the penetration of water through the capillary pores - a kind of "impregnation from the inside" To the effectiveness of the hydrophobic surface property of the inventive color-coated To evaluate glass granules and to be able to compare them with non-hydrophobized granules, the following TEST PROCEDURE (see Figures 1.1 to 1.4) was used:

Into a 75 ml dish (A) were agglomerate mixtures (B + C) each consisting of:

- 60 g of granules to be tested for hydrophobicity in the particle size range 0.4 to 3 mm

(Grading curve: 34% by weight 0.4-1.0 mm, 33% by weight 1, 0-2.0 mm, 33% by weight 2.0-3.0 mm) as well as

- 20 g siloxanisierf.es glass flour in Komgrössenbereich 0.2 - 0.4 mm filled in a homogeneous mixture.

By means of a correspondingly shaped male mold, a trough-shaped depression was pressed onto the surface of the agglomerate. (Fig. 1.2)

15 ml of water (D) were added to each well. (Fig. 1.3).

The sinking time (t) of the water into the agglomerate was measured, ie the time until no water level above the agglomerate is more recognizable. (Fig. 1.4) For individual results of this test, see EXAMPLE 2.

Examples

1. for the production of hydrophobic color-coated glass granules

EXAMPLE 1 a:

20 kg of colorless transparent recycled glass granules in grain sizes of 0.4 to 3 mm should be hydrophobic color-coated in turquoise color.

For this purpose, 400 g water-dispersed, solvent-free, two-component

Epoxy resin diluted with 90 ml of water. 200 g of turquoise spinel pigment were stirred in.

In a ploughshare mixer, the granules were mixed with the liquid colorant. The mixing time was 60 seconds.

In a fluid bed dryer, the coated granules were dehydrated. The temperature of the air stream was 60 ° C. A complete dehumidification was achieved after 80 seconds.

After the cooling phase on the unheated section of the fluid bed dryer, the color-coated glass granules were dust-dry.

It was filled into a sack and stored at about 20 ° C.

After about 3 days, the hydrophobic color coat had reached its final strength by reactive curing.

EXAMPLE 1 b:

20 kg partly colorless-transparent partly brown-transparent granules from bottle-waste glass in grain sizes of 0.4 to 3 mm should be color-coated superhydrophobic in ocher hue.

For this purpose, 350 g of water-dispersed, solvent-free, two-component epoxy resin were diluted with 100 ml of an aqueous methylalkylsiloxane / acrylic ester copolymer emulsion. 200 g of ocher mineral pigment and 150 g of aluminum hydroxide (particle size 5 - 15 μm) were stirred in. In a ploughshare mixer, the granules were coated with the homogeneously mixed coloring agent. The mixing time was 60 seconds.

In a fluid bed dryer, the coated granules were dehydrated. The

Temperature of the air flow was 60 ° C. A complete dehumidification was achieved after 80 seconds.

It was filled into a sack and stored at about 20 ° C.

After about 3 days, the superhydrophobic paint coat had reached its final strength by reactive cure.

Example 1c:

20 kg of colorless transparent recycled glass granules in grain sizes of 0.8 to 1.2 mm should be hydrophobically coated in a slightly translucent ultramarine blue shade. The coating should be done with the smallest possible amount of dye.

For this purpose, first 133 g of an aqueous polyamine-epoxy resin adduct were stirred with 45 ml of a very low-viscosity aqueous methylalkylsiloxane / acrylic acid ester copolymer emulsion and 140 g of mineral ultramarine color pigment. Then, 66 g of the second resin component - a mixture of bisphenol A-epichlorohydrin resin, p-tert-butylphenyl glycidyl ether and benzyl alcohol - was homogeneously stirred.

In a compulsory mixer, the recycled glass granules were coated with the colorant. The mixing time was 60 seconds. In a fluid bed dryer, the coated granules were dehydrated. The hot air temperature was 80 ° C, the warm air exposure time was 120 seconds.

After the cooling phase on the unheated section of the fluid bed dryer, the color-coated glass granules were dust-dry and could be filled into a sack. EXAMPLE 1 d / 1e:

Each 20 kg of colorless transparent recycled glass granules in grain sizes of 0.8 to 1.2 mm should be hydrophobically color-coated in a slightly translucent ultramarine-blue shade with a partial reflective effect. Here, 2 different aqueous hardener components of the epoxy resin system should be used.

For this purpose, first 90 g of an aqueous polyamine adduct hardener, in a comparative experiment, 90 g of an aqueous polyaminoamide hardener, each additionally diluted with about 80 g of water. Each 120 g of mineral ultramarine pigment was stirred.

The hardener-pigment mixtures were then each mixed with 90 g of a viscosity-reduced, reactive-dilute bisphenol A resin with simultaneous stirring of 150 g of fine platelets of epoxy-coated aluminum foil in the format 600 μm × 600 μm × 5-10 μm. After about 40 minutes, the Glasgranulatchargen were each coated with one of these mixtures in the plowshare mixer. The mixing time was 60 seconds.

In a fluid bed dryer, the coated granule batches were dehydrated. The temperature of the air stream was 85 ° C. A complete dehumidification was achieved after about 120 seconds. The aluminum flakes adhered to the glass grain surfaces with sufficient strength. After the cooling phase both color-coated glass granules were dust-dry. They were filled into sacks and stored at about 20 ° C. In both cases, the hydrophobic and partially mirrored color coat had reached its final strength after about 3 days by reactive curing

2. Examples of the detection of the hydrophobic surface property

The test was carried out according to the test method described on page 9, lines 16-31, ie in each case 60 g of test material were mixed with 20 g of siloxanized glass powder each time. The addition of the siloxanized (and thus hydrophobic) glass powder was made with the aim of delaying the sinking of the water into the agglomerate to allow a more precise observation. The experiments were carried out several times. The results given here represent average values.

EXAMPLE 2 a: In order to obtain comparative values, granules were first tested which do not correspond to the present invention and do not expect a hydrophobic surface property.

1. uncoated, washed and dried quartz sand: the mean sinking time of the water (t) was: 62 seconds

2. uncoated recycled glass granules: Mean sinking time (t): 47 seconds

3. Recycled glass granules, coated with water glass and mineral pigment and dehydrated: Mean absorption time (t): 8 seconds

4. Recycled glass granules, coated with an aqueous acrylate dispersion and mineral pigment, dehydrated and cured: Mean settling time (t): 28 seconds

5. Recycled glass granules, coated with an aqueous polyvinyl acetate dispersion, dehydrated and cured:

Mean sinking time (t): 35 seconds

6. Recycled glass granules, coated with an aqueous ethylene-vinyl acetate dispersion, dehydrated and cured:

Mean sinking time (t): 46 seconds

EXAMPLE 2 b:

The product according to the invention resulting from EXAMPLE 1 a was tested.

The mean sinking time (t) was 9 hours, 45 minutes EXAMPLE 2c:

The product according to the invention resulting from EXAMPLE 1 b was tested.

The mean sinking time (t) was more than 48 hours. The experiments were stopped after 48 hours, as it became clear that the water evaporates faster than seepage.

USE

The color-coated recycling glass granules produced by the process according to the invention can be used in many ways as an additive for organically or inorganically bound mortars, plaster mortars and screeds as well as for molded articles and coatings of polymer concrete or granite-like structured polymer artificial stone. Due to their hydrophobic property, they are particularly suitable for weather-stressed building materials or components such as e.g.

Façade elements and facade coatings, roof tiles, concrete, paving stones and slabs predestined.

For this 1 page drawings

Claims

Patent claims

1. Solvent-free process for the hydrophobic color coating of glass granules, characterized in that the glass granules with a mixture of a solvent-free, aqueous, two-component epoxy resin system, water and dye (preferably inorganic mineral pigment) - or with a mixture of a solvent-free, aqueous, two-component epoxy resin system , an aqueous siloxane-containing emulsion, dye (preferably inorganic mineral pigment) and, if necessary, fine-grained powder made of glass and / or aluminum hydroxide, dehydrated and hardened by reaction.

2. Hydrophobically color-coated glass granules, characterized in that they have been produced by the process according to claim 1.

3. Hydrophobic color coated glass granules according to claim 2, characterized in that the granules are made from recycled glass, i.e. colorless transparent flat glass waste and / or colorless-transparent and / or colored-transparent bottle glass exist.

4. Hydrophobically color-coated glass granules according to claim 2 or 3, characterized in that the coating binder is a reaction-hardened epoxy resin.

5. Hydrophobically color-coated glass granules according to one of claims 2 to 4, characterized in that the coating binder is filled with inorganic mineral pigment.

6. Hydrophobically color-coated glass granules according to one of claims 2 to 5, characterized in that the coating binder is enriched with siloxane molecules.

7. Hydrophobically color-coated glass granules according to one of claims 2 to 6, characterized in that the coating binder is additionally enriched with very fine-grained glass powder and / or aluminum hydroxide powder and / or powder made of natural or synthetic mica.

8. Hydrophobically color-coated glass granules according to one of claims 2 to 7, characterized in that the coating binder is additionally enriched with metallic powder or fine platelets made from uncoated or epoxy-coated aluminum foil.

9. Use of hydrophobically color-coated glass granules according to claims 2 to 8 as an additive for organically or inorganically bound mortars, plastering mortars and floor coatings and for moldings and coatings made from polymer concrete or granite-like structured polymer artificial stone.