NL1028044C2 - Method and system for handling objects. - Google Patents

Description

METHOD AND SYSTEM FOR TREATING OBJECTS

The present invention relates to a method and device for treating objects, in particular metal objects.

A number of techniques are known for protecting steel structures against the effects of corrosion. A known technique is galvanizing, whereby a thin layer of zinc is applied to the object surface. The applied zinc layer offers a cathodic protection to the object, that is to say that when attacked, zinc sacrifices itself and thus protects the underlying metal.

Moreover, the corrosion products of zinc will fill in any damage such as scratches and the like, whereby additional protection is obtained.

The zinc can be deposited on the object by electro-chemical means, which is called electrolytic sinking. In addition, the zinc can be applied to the metal object by spraying zinc onto the surface of the object with the aid of spray guns, by allowing zinc to diffuse into a drum (Sherardizing) or by painting the zinc on the object ( zinc dust paints or cold galvanizing). A further possibility for applying zinc to a metal is hot-dip galvanizing, whereby the object to be treated is immersed in liquid zinc, which is located in a zinc bath at temperatures between 445 degrees and 465 degrees Celsius.

During hot-dip galvanizing, the object to be treated undergoes a pre-treatment in which dirt, oil and grease residues are removed from the object surface. ..... ........

deleted. As pre-treatment, the article is then placed in a bath with a dilute hydrochloric acid solution and pickled in to remove rust and mill scale.

This is followed by a "flux" treatment, in which the object to be treated is applied in a flux bath with, for example, zinc-ammonium chloride, in order to later obtain a good adhesion of the zinc to the steel. If the flux is first applied and then dried, it is called dry galvanizing. With wet galvanizing, the flux is spread over the zinc bath surface and the steel is pulled through. After being treated, a whole of zinc / iron alloy layers forms on the steel surface. After the said pretreatment, the object is immersed for a few minutes in the zinc bath, according to the known method, where the liquid zinc connects with the steel and over the entire surface thereof, and therefore also on the inside of any hollow structures in the object. During immersion, a number of (Gamma, Delta and Eta layer) alloy layers 20 are formed by reaction of zinc with metal, while when the object is removed from the zinc bath, a layer of pure zinc is formed.

There are a number of drawbacks to the known methods. Firstly, the use of chemical baths, such as hydrochloric acid baths, as a pretreatment of the steel adversely affects the environment. In addition, the supply of hydrochloric acid and the removal of (contaminated) hydrochloric acid entail high costs.

Furthermore, the known method entails a number of labor-intensive and relatively expensive steps such as arranging the steel in degreasing baths, pickling baths and any de-zincing baths in the case of renovating galvanized steel in the past. After all, the hydrochloric acid only removes the surface of the object and 1028044 3 further impurities remain on the object surface. This requires additional processing steps.

A further drawback of the known method and device is that the use of hydrochloric acid results in brittleness of the treated metal. Subsequently, galvanizing the brittle metal will result in a less smooth surface, which reduces the appearance of the galvanized product.

A further drawback of the known methods is that the objects have a zinc-colored appearance after the zinc treatment, which in many cases is undesirable. For example, when the treated articles are arranged in a space, it may be desirable to give the articles a different color.

Methods for coloring galvanized objects are known per se, for example with the aid of wet chemical processes. According to a known method, the so-called "green chromatography", the galvanized objects are for example treated with a mixture of chromic acid, phosphoric acid and sulfuric acid with the result that the objects thus treated have a green appearance. This known method, however, entails a heavy burden on the environment and is for that reason increasingly labeled unsuitable. Moreover, with the known method only a green appearance can be obtained.

It is an object of the present invention to provide a method and system in which the above-mentioned drawbacks are obviated and in which the articles can be treated quickly and efficiently in an environmentally friendly manner.

According to a first aspect of the invention, a method is provided for treating objects, in particular metal objects, 1028044 4, the method comprising the steps of: a) arranging the objects in a conveyor system; B) transporting the objects along blasting units and irradiating the objects with grains to remove at least one surface layer provided on objects; c) transporting the irradiated objects in a flux bath and fluxing at least the outside of the objects; d) transporting the fluxed object in a zinc bath and applying a zinc layer to the outside of the objects by reacting the outside of the object with the zinc from the zinc bath; e) transporting the galvanized objects along a coloring unit and applying a coloring agent and / or pigment-containing solution of predetermined color to the zinc layer by the coloring unit; F) drying the galvanized and colored objects

According to this aspect of the invention, the pretreatment steps of optionally de-zincing, degreasing, treatment with hydrochloric acid, and cleaning with water and the like can be replaced by a single step, namely irradiating the object. Hereby, not only is the roller layer removed from the object, but it is also possible, if desired, to remove more material layers such as the silicon layer from the object. This provides a cleaner surface of the article, which surface requires a smaller amount of zinc for galvanizing. The surface of an object blasted and galvanized in this way is smoother than would be possible with the known method.

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This smoother surface of the object furthermore makes it easier to give the objects the desired color or colors. The method of coloring the objects is such that the coloring step can be carried out quickly and efficiently and with a greatly reduced burden on the environment.

Preferably, the coloring unit comprises a color bath containing said solution containing said solution and step e of the method comprises placing the objects in said color bath, keeping the objects in the color bath for a predetermined time and removing the color bath. objects from the color bath. By arranging the objects in the dye bath for a predetermined time with the aid of the conveyor and immersing the objects in the dye bath, they can be provided with a correct color in an efficient manner.

For example, when use is made of a conveyor that moves the objects at a predetermined speed and the objects are dragged through the color bath at that speed, the objects can be submerged in the color bath for a sufficient period of time. At a relatively high speed and therefore a relatively short period of time, the objects acquire a light color, while at a low speed and therefore a long period of time, the objects acquire a deeper color. It has been found that good results can be achieved with a residence time of the objects in the color bath between 1 minute and 30 minutes and preferably between 2 and 10 minutes and even more preferably between 3 and 5 minutes.

The temperature of the solution can have a value between 30 ° and 100 ° Celsius. When water is used as a solvent, however, it is preferable to work at a temperature of between 60 ° and 80 ° Celsius. Sufficient dye can be incorporated in this temperature range in a short time.

As already mentioned above, hot-dip galvanized objects are passed through a zinc bath of high temperature (temperature of the zinc of at least 400 °

Celsius). The consequence of this is that the galvanized objects have a relatively high temperature when they reach the coloring unit. In such a situation it is preferable to choose the temperature of the color solution lower 10, preferably in the range between 15 ° and 40 °

Celsius. The objects can hereby be cooled and colored at the same time, which reduces the lead time of the treatment process.

As an alternative to or in addition to the use of a color bath, the objects can also be colored by designing the coloring unit with one or more spraying units, so that in step d the objects are colored by spraying the said solution onto the objects transported along it . Moreover, when a solution of a volatile solvent is used, such as ethanol, methyl ethyl ketone, cyclohexanone, methoxypropanol, etc. and the required colorant and / or the required pigment, the articles thus treated will dry very quickly (in practice within a few seconds).

According to another aspect of the present invention, a system is provided for treating objects, in particular metal objects, comprising: - a conveyor for transporting objects to be treated at an adjustable speed; - one or more jet throwers arranged along the conveyor for throwing one or more grain beams in the direction of objects moving along it 1028044 7 for removing at least the surface layer of the objects; a flux bath arranged along the conveyor for fluxing the objects moving through the bath; - a galvanizing bath arranged along the conveyor for thermally galvanizing the objects moving through the bath; - a coloring unit arranged along the conveyor for applying a dye and / or pigment-containing solution of predetermined color to the zinc layer of the objects moving along it.

In a preferred embodiment of the invention, the coloring unit comprises a color bath containing the said solution and the conveyor is arranged for arranging the objects in the said color bath, keeping the objects in the color bath for a predetermined time and removing the objects. from the color bath. The color bath is preferably provided with heating means 20 for bringing the color solution to the correct temperature.

In another preferred embodiment, the coloring unit comprises one or more spraying units arranged along the conveyor which can spray the said color solution in the direction of the objects.

Further advantages, features and details of the present invention will be elucidated on the basis of the following description of a preferred embodiment thereof. Reference is made in the description to the accompanying figures, in which:

Figure 1 is a schematic top view of a preferred embodiment of the invention; and 1028044 8

Figures 2a and 2b are schematic side views of the preferred embodiment of Figure 1.

Figures 1 and 2 show the preferred embodiment of a galvanizing device 1 according to the invention. The objects V to be galvanized, such as for example steel profiles, are supplied and coupled to a transport system at a starting position. The transport system is a hanging track system and in the embodiment shown comprises a chain box rail 2 along which, with the aid of rollers 21 (Fig. 10 2a), a number of (for example approximately 100) suspension elements 22 can be displaced at a distance of approximately 60 cm. Such a chain box rail system is per se of a conventional type and will not be discussed in detail herein. Other transport systems are also conceivable.

The suspension elements 22 are advanced by a drive 8 which is connected to an electric drive motor 9. The transport system 2 is provided with two tensioning elements 10 and 11 in order to bring the system permanently under a certain voltage. Once the objects V to be treated are attached to the suspension elements 22 at the starting point B (arrow PJ, for example by hooking the objects thereto, the suspension elements are conveyed in the direction of arrow P2.

First of all, the untreated object V undergoes a blasting treatment in a blasting cabin 3. Objects are blasted in the blasting cabin by means of a number of blasting throwers arranged at a preset angle so that the surface layer is removed.

In this case, it is possible to choose to remove only the roller layer present on the object. In that case, the term surface layer only covers the roller layer of the object in question. However, if that is desirable, in addition to the 1028044 9!

J

more layers of the object are removed. For example, it is possible to remove unwanted unevenness from the object, so that it has a smoother and more attractive appearance.

By irradiating the object in the above-mentioned manner, it is so clean that it can be directly "fluxed" without additional processing. The term "fluxes" refers to the introduction or immersion of an object in a flux bath filled, for example, with zinc ammonium chloride. Figure 2a shows that the fluxing takes place by moving the object, hanging from a suspension element 22, through a flux bath 4.

After the flux layer has been dried on the object, for example by guiding the object along a drying unit 5, the object is guided through a zinc bath 6 (Figure 2a), which is filled with zinc of a temperature of around 453 ° C . It has been found that at this temperature and at a transport speed through the zinc bath in the order of magnitude of 50-250 cm per minute and preferably 80 cm per minute, an optimum chemical bond of the liquid zinc with the material of the article is achieved is being brought.

After having undergone the galvanizing treatment, the articles cool down by heat exchange with the environment such as the outside air or heat exchange in the color bath 7 to be described below. In the bath 7 there is a mixture of solvent, such as for example water or ethanol, and one or more colorants applied. In addition to dyes or instead, the mixture may contain pigment of proper color. Experiments have shown that dyes based on azo, disazo, phthalocyanine and carbonyl compounds are particularly suitable for coloring the galvanized objects. As previously stated, the articles can also be colored by arranging spray heads (not shown) on either side of the conveyor with which the articles transported along it can be sprayed with the color solution mentioned herein. Although the articles in this embodiment are not liquid-cooled, the present embodiment has the advantage that rapid color changes are possible. Moreover, the drying time of the articles treated in this way is generally shorter. This naturally results in a shortening of the total lead time. Finally, in some cases the spraying units are easier to fit into a conveyor.

In the color bath 7 embodiment (Figure 2), the objects are cooled from the aforementioned relatively high temperature (approximately 450 ° C) as a result of immersion in the zinc bath to approximately 85 ° C or less. After being cooled, the relevant object is transported until it has reached the end point E. Once there, the object can be removed from the relevant suspension element 22 and discharged (P3). Since the temperature of the objects is less than 80 ° C, employees can package the treated objects directly and without hindrance.

Figures 2a and 2b show a side view of a part of the device. In the embodiment shown, the blasting and fluxing take place directly one behind the other, in contrast to the embodiment of Figure 1.

The lead time of the system, i.e. the time between attachment of an object to be treated to a suspension element and removal of treated object 30 from the suspension element, is in the embodiment shown approximately 1 to 1.5 hours, while the capacity is variable between around 3000 and 5000 kg per hour.

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A number of experiments have been conducted to determine the parameters that influence the color process. Table 1 shows the results of a number of these color experiments.

Table 1 shows the results of a coloring process according to the invention (experiments 11-1) and of two coloring processes known per se, in which use is made of chemicals that are harmful to the environment.

Table 1: Overview of the results of the coloring of galvanized objects.

Experiment Pre-coloring Result treatment procedures Time Temp. Other (min) (Celsius) 1 _ A 20 60-80 spotty dark yellow 15 2 _ Al 60-80 not spotty rinsed after yellowing (dried in) 3 heated A 1 60-80 cooled in evenly to 250 ° C, color bath light yellow 15 min 4 PVP dip A 5 60-80 not rinsed spotlessly after light yellow PVP dip 5 heated A 1 60-80 cooled in evenly to 250 ° C, PVP bath and light yellow 15 min not rinsed after PVP dip 1 0 2 8 0 «4 12 6 heated A 1 60-80 cooled in uniform to 250 ° C, hydrogen light yellow 15 min + 2 peroxide bath min in 20% hydrogen peroxide 7 Alodine A 1 60-80 uniform 4830 light yellow 8 Alodine A 5 60-80 uniform 4830 dark yellow 9 _ B 5 20 not flushed after light blue colors 5 10 Alodine B 2 20 not flushed 4830 rinsed after light blue colors 11 chromate + B 2 20 spotty 5 min green boiling water 12 - C 2 20 13 - C 5 20 1 2 3 4 5 6 7 8 9 10 11 1028044

In experiments 1 and 2, no pretreatment 2 took place before the galvanized objects were 3 colored. In experiments 3-11, a pretreatment 4 has taken place. A pre-treatment may consist of a wet chemical process in which the galvanized objects have been treated with a wet chemical solution to form an oxide layer on the zinc surface of the objects.

8

The pretreatment can also consist of applying an organic coating layer to the galvanized surface of the object to receive the color solution therein. In 11 cases, heating has taken place in an oven 13 to a temperature of about 250 ° Celsius to simulate a cooling immediately after hot dip.

The "PVP dip" pre-treatment involves immersion of the galvanized article for 1 minute in a solution of 1 g / l polyvinylpyrrolidone at room temperature. This has the consequence that a very thin coating is provided on the zinc surface, which coating ensures a more even adhesion of the dye to the surface of the object. This pre-treatment has the advantage that the materials used are not or substantially not harmful to the environment, so that the total process of galvanizing and coloring remains environmentally friendly.

The pretreatment referred to as "Alodine 4830" (zirconization) involves immersion of the galvanized article for 10 s (experiment 7) and for 30 s (experiments 8 and 10) in a solution of 1 g / l fluorosirconic acid (H2ZrF6) in water, with a pH of 2 (with HNO 3) and at room temperature (supplier: Henkel).

The pretreatment referred to as "chromatography" or "chromation" refers to a process in which an object is kept in pH 200 for 2 minutes in a mixture of 200 g / l sodium dichromate and 10 g / l sulfuric acid (H 2 SO 4 (96%)) room temperature was submerged.

The galvanized objects can also be pretreated by oxidizing with hydrogen peroxide.

The wet chemical processes Alodine 4830, hydrogen peroxide and chromation have all been used to apply an oxide to incorporate the dye so that a more durable color is obtained. The oxide layer also offers protection against corrosion of the zinc.

The objects, whether or not pre-treated, were then immersed for a time in the table 1 0 2 8 0 4 4 14 in a bath with a different content each time:

Process A indicates that the article is immersed in 0.5 g / l Duasyn Yellow 3GF-SF in water at pH 6 and 60 ° Celsius (Disazo compound (Na 2 C 27 H 22 N 6 S 2 O 9)

Color index Direct Yellow 132, supplier: Clariant Benelux BV).

- Process B indicates that the article is immersed in 5 g / l Savinyl Blau GLS) in ethanol (Phtalocyanine 10 (C32H16N8M) solvent based 44, supplier: Clariant

Benelux BV); - Process C indicates that the article is immersed in 30 g / l Chromic acid (Cr03), - 10 ml / l phosphoric acid (H3 PO4 (85%)), 15 ml / l sulfuric acid (H2 SO4 (96%)) at 15 pH 1 and room temperature.

The experiments have shown that the concentration of the dyes influences the coloring of the object. At a concentration of 0.1 - 0.5 g / l a relatively light color has been observed, at a concentration of 5-10 g / l a relatively dark color has been found. The length of time during which the articles are immersed has a similar influence on the coloring of the article.

The present invention is not limited to the above-described preferred embodiment thereof, the requested rights are determined by the following claims, within the scope of which many modifications are conceivable.

1028044

Claims (28)

Method for treating objects, in particular metal objects, the method comprising the steps of: a) arranging the objects in a transport system; b) transporting the objects along radiating units and irradiating the objects with grains to remove at least one surface provided on objects; c) transporting the irradiated objects in a flux bath and fluxing at least the outside of the objects; d) transporting the fluxed object in a zinc bath and applying a zinc layer to at least the outside of the objects by reacting the outside of the object with the zinc from the zinc bath; E) transporting the galvanized objects along a coloring unit and applying a coloring agent and / or pigment-containing solution of predetermined color to the zinc layer by the coloring unit; f) drying the galvanized and colored objects. 2. Method as claimed in claim 1, wherein the coloring unit comprises a color bath containing said solution and step e comprises arranging the objects in said color bath, keeping the objects in the color bath for a predetermined time and removing the objects from the color bath. Method according to claim 2, comprising moving the objects through the color sheet. 1 o 2 8 0 4 4 Method according to claim 3, comprising moving the objects through the color bath at a predetermined speed. Method according to claim 4, wherein the transport speed through it is in the order of magnitude of 50 to 250 cm, preferably 80 cm, per minute. Method according to claim 5 or 4, comprising substantially continuous transport of the object through the color bath. A method according to any one of the preceding claims, wherein the residence time of the objects in the color bath is between 1 minute and 30 minutes and preferably between 2 and 10 minutes and even more preferably between 3 and 5 minutes. The method of claim 1, wherein the coloring unit comprises one or more spraying units and step e comprises spraying said solution onto the articles transported along it. 9. Method as claimed in claim 8, wherein a mixture of alcohol with colorant and / or pigment is used. A method according to any one of the preceding claims, wherein dye based on azo, disazo, phthalocyanine and / or carbonyl compounds is used. 11. Method as claimed in any of the foregoing claims, wherein the temperature of the solution has a value between 15 ° and 100 ° Celsius. A method according to any one of the preceding claims, wherein the temperature of the solution has a value between 60 ° and 80 ° Celsius. A method according to any one of the preceding claims, comprising in step d passing the objects through a zinc heated to a temperature of at least 400 ° Celsius and in step e passing the objects through 10 * 8044 a color solution with a temperature between 15 ° and 40 ° Celsius for simultaneously cooling and coloring the objects. 14. A method according to any one of the preceding claims, wherein the concentration of dye and / or pigment in the liquid is between 1 g / l and 10 g / l. 15. Method as claimed in any of the foregoing claims, wherein step e comprises pretreating the galvanized objects and subsequently applying the said color mixture. 16. System for treating objects, in particular metal objects, comprising: - a conveyor for transporting objects to be treated at an adjustable speed; 15. one or more jet throwers disposed along the conveyor for throwing one or more grain jets in the direction of objects moving along it for removing at least the surface layer of the objects; 20. a flux bath disposed along the conveyor for fluxing the objects moving through the bath; - a galvanizing bath arranged along the conveyor for thermally galvanizing the objects moving through the bath; 25. a coloring unit arranged along the conveyor for applying a colorant and / or pigment-containing solution of predetermined color to the zinc layer of the objects moving along it. 17. System as claimed in claim 16, wherein the coloring unit comprises a color bath containing said solution and the conveyor is adapted to place the objects in said color bath, keeping the objects for a predetermined time in the color bath and removing the objects from the color bath. 18. System as claimed in claim 17, wherein the conveyor is adapted for moving the objects through the color sheet. A system according to claim 18, wherein the conveyor is adapted to move the objects at a speed in the order of magnitude of 50 to 250 cm, preferably 80 cm, per minute. A system according to claim 16, wherein the coloring unit comprises one or more spraying units arranged along the conveyor which can spray said color mixture in the direction of the objects. 21. System as claimed in any of the claims 16-20, 15, comprising second spraying units for pre-treating the objects. The system of claim 16, wherein the conveyor and the color bath are arranged for a residence time of the objects in the color bath between 1 min 20 and 30 minutes and preferably between 2 and 10 minutes and even more preferably between 3 and 5 minutes. The system of any one of claims 16 to 22, wherein dye based on azo, disazo, phthalocyanine and / or carbonyl compounds is used. System as claimed in any of the claims 16-23, comprising heating means for bringing the color solution to a working temperature between 15 ° and 100 ° Celsius. 25. System as claimed in any of the claims 16-24, 30, comprising heating means for keeping the color liquid at a working temperature between 60 ° and 80 ° Celsius. 1028044 26. System as claimed in any of the claims 16-25, comprising second heating means for heating the zinc in the zinc bath to a temperature of at least 400 ° Celsius and first heating means for heating to a temperature of between 15 ° and 40 ° Celsius of the color liquid for simultaneously cooling and coloring the objects in the color bath. 27. System as claimed in any of the foregoing claims, wherein the method according to any of claims 1-15 is applied. A product obtained according to the method of any one of claims 1-15. 1028044