PROCESS FOR WATER-PROOFING METAL ELEMENTS, PREFERABLY LARGE BOBBINS AND PRODUCT USED WITH SUCH PROCESS

Abstract

 Process for water-proofing metal elements, preferably large bobbins, and product used with said process which comprises two phases: an immersion phase and a cooling/drying phase. In the first immersion phase, the metal element is immersed in a liquid plastic material bath during a short period of time but sufficiently long to obtain a hardened layer of small thickness and a penetration of the isolating agent into the material cracks, if any, while in the second phase the plastic film is cooled/dried by aeration which solidifies the synthetic layer formed around the material. Both operations can be carried out by using a crane or hoisting blocks and the tools appropriate to the shape and size of the element to be protected, and the plastic material presented a tonality corresponding to the characteristics of the element, gravings can be performed before and/or after the cooling. The product for water-proofing metal elements is a plastified cellulosic ester which melts at 175°-190 °C forming a film which is all the more transparent and thin than the temperature is high, the part to be protected being immersed in the bath during 20 seconds and dried in ambient air during 30 seconds.

Description

[0001] The present invention, as its title indicates, is related to a process for protecting a metal element, particulary presented in the form of a bobbin or a bundle of metalic sheets against corrosion and product used for this purpose.

[0002] Metal products undergo oxidation when they are exposed to the aggression of environmental agents. This attack is much higher when they are subject to an acid, or salt ambient, ambients with high humidity or under any other highly corrosive conditions.

[0003] There have been several processes more or less successfully developed which tend to palliate this degradation. The better known processes comprise impregnation or immersion in passivators; nevertheless, these processes provide protections of a very short duration, or under optimum storage conditions, but they result unsuitable for long periods of time, against atmospheric agents, such as rain, air, sunshine or ice, etc. On the other hand, protection means such as paint, lac coatings, galvanizations, etc result expensive.

[0004] Therefore it becomes evident that other kinds of protection are required another kind of protections which practically extend the period of protection to indefinite and which do not involve high costs at the same time. It is also important to achieve a protection which does not require special storage conditions, which does not damage the environment, namely, which is not toxic, neither mal-odorous, etc, and which is easily recyclable.

[0005] These conditions are required for many materials which due to their weight, volume, shape, use, etc, are not found to be suitable for ceilinged storage under optimized temperature or humidity conditions.

[0006] The object of the present invention consists of a process which results in a new concept of protection and the product used in said process; for which, the idea of protection is based on the very Nature, on the ideal preservation conditions of fosilized insects which are still remained until our time. This concept of isolation for metal elements from outside oxidant agents by forming a layer of plastic material allows a practically indefinite storage and the exposition of the whole protecting layer/metal element to any sort of environment.

[0007] This method is capable of coating all kinds of metal elements, wherein they are considered as a volume and not as a surface, as it is the case of a metal bobbin or a package composed of sheets.

[0008] A bobbin of sheet of 12,000 Kg of weight has a surface of 12m². This sheet weight, which has a market price of $ 6.000 approximately, can be protected against oxidation with 12 Kg of plastic, the whole surface of the bobbin being coated with a thickness of 1,000 microns.

[0009] The price of plastic is 2.8 $/Kg, therefore, the ratio cost of Kg of plastic/cost of Kg of sheet to be protected (6,100 ÷ 12) is very low:

[0010] On the other hand, the time for applying the method is minimal, since, in approximately one minute, the bobbin becomes coated and protected.

[0011] Tests with medium size bobbins have been carried out in a Spanish company, with test samples introduced into a salt spray and an Amonia atmosphere for 700 hours. By extrapolating the results, it was apparent that protection of bobbins could be assured for a period of 4 years.

[0012] The process basically comprises immersion of the bobbin or the package of sheets into a bath of hot plastic such that it completely covers them, thus isolating it from external agents and hence mantaining the same until the protection is removed, when the necessity for their use is immediate.

[0013] The coating is carried out by a plasticized cellulosic ester which melts at 175°-190°C providing an elastic and transparent film such that the thickness can be adjusted by temperature thus achieving a thinner film as the higher the temperature is. In the case when a thicker layer is desired, the submersion of the piece into plastic may be repeated. The plastic is composed of 30-33% cellulosic resins, 67-70% plasticizers and additives which provide protection properties of the product. Said plastic is prepared by melting resins and subsequently adding the plasticizers into a reaction vessel at 150°C at a low stirring.

[0014] The coating has a anti-rust element and an antiadherent compound and the piece is immersed into a bath for 20 seconds being air-dried thereafter for 30 seconds.

[0015] The object of the present invention will be better understood with the help of the following description based on a practical example of embodiment. Said description is effected with the aid of the attached drawings in which:

Figure 1 is a perspective view and an elevation front view of a crane arm with the bobbin hanging therefrom, and a tank which contains the plastic bath.

Figure 2 is another variant of the perspective view and the front view in which a package of sheets instead of a bobbin is placed.

[0016] On the crane arm (1), the bundle or the bobbin are carried to a bath (4) which contains hot plastic according to the described composition at a constant and suitable temperature by means of any heating system. At the head (2) of said crane arm, tool assemblies (3) necessary for perfectly moving and hoisting metal pieces are placed.

[0017] A subsequent cooling of the protecting plastic layer provides a total embedding on the element until it is totally isolated from the outside. This cooling phase can be achieved by movement in the ambient or by artificial means such as ventilation, etc.

[0018] The protecting material contained within the tank (4) may exhibit any tonality or colour; likewise, it is possible to imprint on the protection any kind of inscription about the characteristics of the product contained or protected; this way, it is not necessary to break the coating in order to know the type of the product and its most notable characteristics.

[0019] Once the nature of the present invention, as well as a manner to take it into the practice are sufficiently described, it only remains for us to add that in its whole and in its forming parts, changes in shape, materials or disposal may be made whenever said alterations would not substantially vary those invention characteristics which are hereinafter claimed.

Claims

1. Process for water-proofing metal elements, preferably large bobbins, characterized in that it essentially comprises two phases: an immersion phase and another cooling/drying phase. Of which, in the first one, a metal element is immersed into a bath of plastic material in liquid state, for a short period of time, however sufficient for providing a hardened, slightly thick layer and for the penetration of the insulator into possible grooves of the material, while in the second phase, the plastic film is cooled/dried by airing which solidifies the synthetic layer formed arround the same, both operations being carried out with the help of a crane or hoisting block and the tool assemblies adapted to the shape and dimensions of the element to be protected, and in that the plastic material presents a tonality according to the characteristics of the element, and even performing imprints corresponding to the same, said imprints being performed before and/or after cooling.

2. Process for water-proofing metal elements, prefereably large bobbins, according to the previous claim, characterized in that the coating thickness may be regulated by temperature thus achieving a thinner film as the higher the temperature is, and in that the piece is immersed into the bath for 20 seconds, being thereafter dried through drying means either artificial or ambient air, the duration of drying being 30 seconds in the latter case.

3. Product used for a process for water-proofing metal elements, preferably large bobbins, characterized in that it is made of a plasticized cellulosic ester which melts at 175°-190°C preferably composed of 30-33% cellulosic resins, 67-70% plasticizers and additives which provide protection properties of the product.
The manner to prepare it is by melting resins and subsequently adding plasticizers into a reaction vessel at a low stirring at 150°C.

4. Product according to claim 3 characterized in that the coating has an anti-rust element and an antiadherent compound.

Drawing