MXPA98001710A - Antiputrefaciente material non-pollutant to cover recipients of polimerizac - Google Patents

Abstract

Ecological antiputrefacient material to be applied to internal surfaces of polymerization reactors of naphthenic type structure having a radical (OH), in position 1 and in one or more of positions 2, 3, 4 in accordance with the structure (

Description

ANTIPUTREFACIENTE MATERIAL NON-POLLUTANT TO COVER POLYMERIZATION CONTAINERS TECHNICAL FIELD The object of this invention is a non-polluting antiputrefacient material for coating polymerization vessels. It is known that the process for obtaining a polymer is carried out in reactors known as polymerization vessels. It is also known that during the polymerization, significant amounts of the material being polymerized are deposited on the walls of the reactor and on the respective ducts, forming a contaminating layer that prevents heat exchange and that covers the ducts, valves, etc. For this reason, for more than twenty years, antiputrefacient materials have been used to avoid depositing on the walls of the reaction vessel and the ducts of the material being polymerized. This invention contemplates these antiputrefacient materials.

BACKGROUND OF THE INVENTION Despite the use of different types of antipu refactory agents, there are still problems due to deposit formation, considering as main setbacks: considerable maintenance work to remove deposits with subsequent interruption of production, reactor opening and therefore immission into the atmosphere of large quantities of gaseous monomers with severe contamination of the environment; contamination of the resulting product, due to rotting parts (of very dark color) end up inside the polymerized material produced, with subsequent low quality and user complaints; - very serious ecological problems due to the elimination of deposits as waste. - The particles that are attached to the layer are of a bluish or dark brown color that tend to black, contaminating the polymers obtained in the form of black specks, which worsen the qualitative aspect of the finished product. In the prior art, antiputrefacient material has been developed with greater attention in the production of polyvinyl chloride in water suspension. Among the various substances used as antiprecipient agents, those of greatest interest were obtained through the technique that provides for the condensation of polyarylphenols with formaldehyde. For this purpose reference is made to: - The patent of E.U.A. No. 3,669,946 (filed in the United States on August 31, 1970, and described June 13, 1972) which describes the general concept behind the use of polar organic substances, such as, for example, naphthenic dyes, formaldehyde, alpha-naphthalemine, nigrosine and many others. - The patent of E.U.A. 3,825,434 published July 27, 1974, which describes an antiputrefacient agent obtained from the condensation of phenol with formaldehyde. It has been proven that this antiputrefacient material is not very effective in preventing deposits on the walls, apparently because the condensed phenol formaldehyde has a cross-linked structure. EP 0052421 describes a process for obtaining an antiputrefacient agent that differs from the previous ones by the fact that the phenol is replaced by 1-naphthol (cc-naphthol) in which the nuclear positions 2 and 4 are not replaced and the 3-position it is not substituted or has a substituent that does not attract electrons with force. FR.A.2 535 325 (TOYO SODA MANUF CO., LTD) of May 4, 1984: describes a process for non-aqueous polymerization of vinyl chloride using a -S03 Na radical. This product gives a solution with a lot of color clearly not acceptable in the procedure because it results in a contaminating color. In addition, this product has a low adhesive capacity on the inner surface of the reactor and is easily removable by the polyvinyl chloride monomer. EP.A, 0 096 319 (SHIN-ETSU CHEM., CO., LTD.) Of December 21, 1983: describes a method for preventing scale deposition in the polymerization of ethylenically unsaturated monomers. The method comprises coating the walls of the reactor in advance with an aqueous coating composition comprising an organic dye of sulfonic or carboxylic acid in the form of an alkali metal or ammonium salt and an aqueous colloidal dispersion of an inorganic material and then dyeing the coated surface. This solution has the same defects as the previous one. EP, A, 0 091 965 (SHIN-ETSU CHEM., CO., LTD.) Of October 26, 1983: describes a method for preventing the deposition of polymer flakes during the polymerization of vinyl monomer, wherein a solution of aqueous coating containing an alkali metal or ammonium salt of the sulfonic acid or carboxylic acid type having at least one pair of double bonds conjugated per molecule and polyvinyl alcohol in a specific ratio and having a pH not exceeding 7 wall of a reactor before conducting the polymerization. This solution has the same defects as the previous one and also has no efficiency in the prevention of scale build-up on the inner wall of the reactor during the polymerization and is not suitable for products that come into contact with food products, e.g., plastic bottles of mineral water. US, A, 4, 142 033 (D. WITENHAFER) of February 27, 1979: describes a polymerization inversion process for producing vinyl resins by a polymerization inversion technique in the presence of a two-layer coating on the surface internal of the polymerization reactor, in which it is provided to use dyes to make the sizing coating containing in its structure one or more radicals of -S03H and / or -S03Na. This product is of strong color and forces the operator to adopt techniques not suitable for medical and food PVC applications and having the same defects as the previous one and also, it is not able to work well at the polymerization temperature of PVC between 65 ' C - 75 ° C. These antiputrefacient products are of a dark brown or blue color that tends to black; furthermore, it has been observed that some of these products have very low efficiency at polymerization temperatures, and others when they come into contact with the oxygen in the air present in the polymerization vessels do offer effective protection and easily degrade in an irreversible manner. The aid of this invention is to avoid the above disadvantages and eliminate the aforementioned defects.

DESCRIPTION OF THE INVENTION The first purpose was to make the pre-existing dark antiputrefactive agents colorless, so that the PVC scale particles, which arise from the walls of the reactor during the polymerization and / or during the rinsing, do not contaminate the finished product and the putrefactive that is going away. to coat. Taking into account the technique described in the patent of E.U.A. No. 2,848,436 published August 19, 1958, which claims the preparation of products of formaldehyde condensation with colorless alkyl phenols using sodium hydrosulfite, it was intended to use the same principle to prepare bleached antiputrefactive agents. However, as the antiputrefactive agents condensed to a maximum grid, it was not possible to use this technique since only a minimum discoloration occurred, passing the color from dark bluish to dark green, and, above all, a large amount of precipitated salts, which indicates that the reaction has not taken place. To reach the first positive results, it was necessary to find a product obtained under particular temperature and time conditions, for which the degree of crosslinking was not so great and would still allow the reaction with sodium hydrosulfite. In particular, it has been observed that the product deriving from the condensation of formaldehyde with alfanaphthol was the one that offered the best possibilities of modification. However, the results were not constant because the different and violent reactivity of formaldehyde made it difficult to control the reaction and intervention times. It was thought to find a solution also for this latter disadvantage by replacing the formaldehyde, the cause of the uncontrollable and irreversible network with the following type of reagents: a- sodium salt of hydroxymethansulfinic acid; b- sodium salt of hydroxymetanesulfonic acid; c- the product of the reaction between sodium hydrosulfite and formaldehyde prepared separately. By carrying out the reaction in the absence of oxygen and under particular time and temperature conditions, subsequently described in the appended examples, and using the sulfur derivatives, the desired decolorization results were obtained. The alkaline water solution of these products, at pH 12. 5 was perfectly clear and had a light yellow color, which, in the presence of oxygen, turned blue; in absence the solution quickly changed to its original color. The phenomenon can easily be repeated for a large number of samples. In these polymerization tests carried out in industrial reactors and described in the appended examples, the bleached non-polluting antiputrefacient agent (colorless or transparent) previously added with polyvinyl alcohol, formed on the walls of the reactors a thin film which appeared to be very resistant to abrasion, and above all, with very large anti-prudential properties. From the analyzes carried out subsequently, it appears that the new product has a completely new molecular structure when compared to that of pre-existing antiprecipient agents, and that it has an extraordinary resistance against the adhesion of the material being polymerized in the reactor.; it does not come off the wall, and it lasts longer, it disappears very slowly, and, in addition, only a thin layer is needed on the wall, therefore the amount of material used is less. The reasons for such a surprising effect were sought, and the only factor that can justify this surprising discovery, is the massive presence of sulfur, which not only explains a decolorizing function, but also acts as a binder of macromolecules, as a strong stabilizer of the molecules obtained, placing it in any free position of the naphthenic group, stabilizing it and making it a strong repellent, is not noticeable in the rubbers. Therefore, the product did not only have fading properties, but also some new and important non-stickiness, and in this way can be considered a much bigger innovation compared to the initial aid, particularly if one takes into account the large and serious ecological problems that still exist that cause current polymerization processes of vinyl chloride, styrene, acrylonitrile, butadiene, acrylic acid, polyacetate and many of their copolymers. Despite the enormous investment in studies and research to solve the problem, until now no satisfactory results have been obtained. In order to demonstrate the importance of the present invention, the inventors, who know that tests carried out in laboratories or small pilot reactors are not representative for the known reasons (different types of agitation, different surface-volume relationships and especially a non-uniform application on the internal surfaces of the reactor), they had the possibility, thanks to the collaboration of important chemical industries to exploit this interesting discovery, to test the new non-polluting antiputrefacient material for long periods in industrial production reactors.

STRUCTURE OF THE NEW PRODUCT From subsequent analyzes it has been discovered, as claimed, that the main anti-prophylactic action of the product is given by the inclusion of sulfur in the radicals of the naphthenic structure. Therefore, the problem has been solved with a new antiputrefacient material. which is applied to the inner wall of a polymerization vessel as a protective coating, of the type including naphthenic type aromatic molecules with radicals in the 1 to 8 position, according to the arrangement: wherein at least one sulfur atom (S) is included in at least one of these radicals. In the antiputrefacient material there is a substantial presence of sulfur and the agent is characterized by the presence of sulfur which does not represent an impurity; therefore, its content must be greater than 0.25% by weight, preferably greater than 0.85%, the optimum percentage being 9.3%. Conveniently, the sulfur structure can be linked from the radical to oxygen (0). Equally conveniently, the radical is characterized by the presence of S0n where n can be 2 or 3. In the optimal solution the radical is characterized by the presence of the SOnNa group, where n can be 2 or 3.

From the tests and the spectroscopic examinations and from the analyzes on the products, it has been verified that the greater activity is obtained by adding to a naphthenic structure, salified sulphonic and sulphonic radicals through the presence of sodium in the substantial formulation - CH2S0nNa- if it links two of these structures. This characteristic as claimed in the present invention and being able to result in a liquid product, perfectly transparent and colorless in the absence of oxygen, becoming progressively dark in the presence of oxygen and becoming colorless if restored in the absence of oxygen, and resulting indeed, strongly effective in functioning as antiputrefacient, according to the scope of the invention. In the product, different molecules can coexist A. First type of molecules, simple: Where n can vary from 2 to 3. B. Second type of molecule, simple: OH Where n can vary from 2 to 3. C. Third type of molecule, simple: OH CH2S0nNa Where n can vary from 2 to 3. D. Fourth type of molecule, more complex, linking naphthenic tures: OH OnNa where n can vary from 2 to 3. E. Fifth type of molecule, even more complex, linking two naphthenic structures or intermediate reaction: Where n can vary from 2 to 3. F. Sixth type of molecule, an intermediate reaction even more complex: Where n can vary from 2 to 3. Therefore, the new product is characterized by the contemporary presence of these molecules, with one or the other prevailing according to the reaction conditions.

FORMATION OF THE NEW PRODUCT: The product to which the present invention relates, is obtained by causing the reaction of a product having naphthenic (aromatic) structure, such as for example of the alfanaphthol type, with the sodium salt of hydroxymethansulfinic acid having the empirical formula CH3Na? 3S and the following structural formula: D H \ I Na S - C - OH // 'I) H The sodium salt of hydroxymetansulfinic acid reacts with alfanaphthol in the weight ratio of 1 to 1.5, in 10% to 50% of water solution and bringing the solution to a temperature between 40 ° and 100 ° C under a nitrogen atmosphere and in an ambient alkaline (pH 11-13), forming the new product according to the present invention. The solution of the product thus condensed has a clear transparent appearance, and if it is left for a certain period in the presence of air (oxygen) it oxidizes slightly, turning bluish, but if the contact with oxygen is interrupted, the product returns to its original transparent clear appearance. This physical behavior provides that a completely new product has been synthesized, which is structurally different from those of the previous techniques, in which this physical phenomenon could not be observed. Several hypotheses have been made about the structural nature of the product, and even not being completely sure of the causes of this reversibility, it is believed that the phenomenon may be related to the presence of sulphonic or sulfinic radicals in the condensate. The reaction that takes place is substantially the following: +02 YELLOW SOLUTION >; CLEAR SOLUTION < BLUE -02 This characteristic also distinguishes the new product from those obtained with previous techniques. The structure of the resulting condensate, as provided, is very different and innovative not only because of the presence of the sulfur atom (S) in the respective radicals, but also because of the great reactivity and capacity of the molecules that are formed in this way.

OTHER POSSIBLE TYPES OF REALIZATION The product can also be made by replacing the sodium salt of hydroxymethanesulfinic acid with the sodium salt of hydroxymethanesulfonic acid. In a more complex and costly manner, formaldehyde can also be reacted with sodium hydrosulfite and, therefore, the resulting product with a naphthenic, such as a-naphthol. Presumably the reaction occurs as follows: The sodium salt of hydroxymetansulfinic acid reacts with a-naphthol or its sodium salt, forming the carbocation. or its isom giving as a final result the p ructures previously named A, B, C, D, E and F. APPLICATION TESTS The product applied to the surface of the reactor in an atmosphere deprived of oxygen, once dry, has a light yellow-brown color, in contrast to the navy blue color that has a black color of the antiputrefaction agents currently used. In order to maintain not only the transparent appearance, but also its efficiency, the antiputrefacient material in the liquid state is kept in hermetic containers. The best preservation is obtained by pressurizing the container with inert gas, preferably nitrogen. The best containers are glass or, even better, polyethylene terephthalate (PET), so that the containers will not pollute the environment and can be completely recycled. The simplest configuration is that of bottles that is commonly used for gaseous mineral water. The product thus preserved remains unchanged, having a pale color slightly tending to yellow or yellow ivory, and in the tests for application on the walls of the reactor, forming deposits of antiputrefacient material on the walls a thin layer which becomes, as It was mentioned previously, of a light yellow-brown color. The application on the walls of the reactor is carried out in the absence of oxygen by spraying it with steam at high temperature. The higher the temperature, the greater the adhesion of the wall covering. So far the application tests have only been carried out in small laboratory reactors with an approximate volume of 1 liter. The results in these small reactors were always positive, even with low quality antiputrefactive materials, and this was due to the simple fact that the thickness of the coating is always the same, weight the volume / thickness ratio of the coating is notoriously different in a reactor of laboratory and those used for production. Actually, a production reactor can have a volume of 100,000 liters or more. The coating applied on the wall practically always has the same thickness, for example a few tenths of a millimeter. Therefore, the results of a coating of equal thickness in the reactors of totally different volume, which in the case described in the present invention had a ratio of 1 to 100,000, undoubtedly can not be considered identical.

For this reason, the tests were carried out directly in production reactors, as described in the following pages. It has been calculated that, in order to keep a 136 m3 reactor clean, with work cycles exceeding 1000 loads, approximately 6 LT is necessary. of water solution, prepared as described in example 1 and sprayed after each load. Taking into account that in 6 LT of an active ingredient solution at 5% there are only 300 grams of an antiputrefacient agent, and of these, only 30 grams form the protective layer that covers the internal parts of the reactor, while the remaining 270 condensates are recovered at the outlet after spraying with steam, it can be seen that the amount of antiputrefacient agent object of this invention is infinitely lower compared to the 45,000 kg of charged monomers. Actually, thanks to the minimum amount of product that can come into contact with finished polymers, it has never been possible with the analytical means currently used to detect product traces in polymers and in their finished products. This has been confirmed by means of various analytical tests carried out in order to ask the health authorities for permission to use the antiputrefacient agent in the production of polymers to make containers for food and medical articles. It has also been observed that the action of this new antiputrefacient agent occurs in two different stages, and with greater precision: a first application period, which can vary from 100 to 400 charges, which requires the quantities of antiprecipient agent indicated in the appended examples . In this way, the previous polymers or the other types of antiputrefacient agent that cover the micropores of the surfaces of the reactor that also acted as support for additional deposits, were removed perfectly. - a second and last cycle of application where the necessary quantities of antiputrefacient agent were reduced to half or even to 1/4, since the micropores of the internal surfaces of the reactor are already covered and well protected by an optimal quantity of the antiputrefacient agent object of the present invention. Inside the reactor, after 4 months of continuous operation (2.5 loads per day), it had a light yellow-brown color, with no trace of polymers and in particular having the upper parts in contact with the gas monomer phase (reflux condensers, safety valves and flow ducts) perfectly clean, which do not need any type of cleaning. This partial decrease in the quantities used of antiputrefacient agent, opposed to the previous techniques, allows to supply the reactor rinse to the tanks for the collection of water suspensions of the obtained polymer, without additional discharges of waste, and therefore allowing a technology of complete and effective loading and unloading, and above all cheap, of the polymerization containers, with a technique known to the experts of the sector as: "hole closed by man" As the sodium salt of hydroxymethansulfinic acid can also be prepared with an excess molar hydrosulfite, an analogous or improved condensate (a greater reducing effect) could also be obtained using this product.

EXAMPLES FOR THE PREPARATION AND APPLICATION EXAMPLE 1 PREPARATION OF NON-CONTAMINANT ANTI-COMPUTING AGENT In an 8000 liter stainless steel reactor, equipped with an anchor stirrer with a speed ranging from 20 to 40 rpm, 1200 kg are loaded respectively. of water, 180 kg of a solution of 30% NaOH, 270 kg. of alfanaftol under a rigorous nitrogen flow. The temperature is brought to 90 ° C. and in 2 hours 900 kg are filtered, of a water solution of sodium hydroxymethylene sulphate at 31.5% w / w.

The solution was maintained at 90 ° C for 12 hours and then 190 kg of a 30% NaOH solution was added. At the end of the reaction a perfectly clear yellow water solution was obtained, to which 800 kg of a 4% polyvinyl alcohol water solution was added, which has a viscosity at 20 ° C of 45 cP and a degree of hydrolysis that exceeds 99% OH. The mass was cooled and then diluted with water until a final percentage of solids equal to 5% was reached. The solution thus obtained was transferred into bottles of 1. 5 lt of PET under a flow of nitrogen. Then the bottles were listed for use in antiputrefacient tests in industrial production reactors. A. From the laboratory analysis carried out in the water solution of non-polluting antiputrefacient agent, the following results were obtained: Al.% Solid matter in an oven at 120 ° C for 3 hours: 5%. A2. pH = 12.3 A3. Specific weight at 20 ° C: 1,028 A4. Reversibility of the product in contact with air at room temperature - The 1.5 liter PET bottle is opened and an air flow is introduced for 5 seconds. - The bottle is closed and subjected to agitation for 1 minute. - The color of the solution changes from light yellow to dark blue. - The bottle, after 5 minutes, shows that a vacuum has formed inside it, and the color of the liquid, after approximately 60 minutes, changes once again from dark blue to light yellow. This test indicates that the product has absorbed all the oxygen supplied and that it is still active. B. Analysis in the dried product as such Evaporating the water of the solution at 60 ° C in a nitrogen environment, a colorless product was obtained in the form of a slightly yellow powder which is subjected to various analyzes: Bl. Elemental analysis The elemental analysis in the product was carried out with an Erba instrument model EA 1108, for the determination of carbon, hydrogen, nitrogen, sulfur and by means of atomic absorption spectroscopy (AAS) for the determination of sodium, gave the following results: - Ca rbono: 55.6% - Hydrogenated: 3.84% - Nitrogen: < 0.10% - Oxygen: 15.86% - Azuf re: 8.8% - SODIO. 15.8% B2. Spectrometric analysis An infrared spectrometer was used to analyze the product prepared by the following technique of the pellet in KBr at a concentration of 0.1% by weight. The instrument used was a Perkin-Elmer FT-IR model 7200. The spectrum showed the presence of bands that characterize the groups presumed in the description of the structure of the product and, in particular, the bands at 970 ctrr i, 640 CITG1 and 500 cpr1.

EXAMPLE 2 POLYMERIZATION TESTS OF SUSPENSION POLYVINYL CHLORIDE (PVC-S) IN LARGE INDUSTRIAL REACTORS In order to verify the specific efficiency of the new antiputrefactive agent prepared as described in example 1, a large reactor, having a volume of 136 m3, was chosen. This container is used in the production of K-57, a delicate type of PVCs, which has a low molecular weight and is therefore suitable for the production of bottles or containers (injection or blow) for mineral water and other products for medical use For several years, an antiputrefacient agent, produced in accordance with the known techniques described in the introduction of the present patent, was used in this reactor, and therefore, for many years the production has been optimized with the following parameters reported for each ca rga: a- reactor washing with high pressure water (>; 200 barias). b- application of the antiputrefacient agent with around 200 l of solvent. c- heating of the walls with external emission of toxic vapors from the solvents. d- rinsing the reactor and loading for polymerization. The charge formulation was as follows: - VCM: 45,000 Kg. - H20: 60,750 Kg. - Primary suspension agent of the partially hydrolyzed polyvinyl alcohol type, with degree of hydrolysis equal to 72% OH and viscosity of 4% of water solution equal to 7 cP: 27.0 Kg. Secondary suspension agent of the partially hydrolyzed polyvinyl alcohol type, with degree of hydrolysis equal to 55% OH: 27.0 Kg. - Catalyst type lauroyl peroxide: 22.5%. - Reaction temperature: 70 ° C. The reactor was equipped with a fixed reflux condenser to the upper part of said reactor and connected to it by means of 12"ducts.

The agitation system was based on 2 breakwaters and 3 levels of agitation. After a conversion equal to about 85% (pressure Dp 0.7-1 baria), the reactor was degassed and the suspended mass was transferred to the collection tanks. During the transfer the suspension was filtered through a large filter that blocks the scales with a diameter greater than 5 mm. The statistical data on the cleaning of the reactor and on the collection of scale, in this specific and difficult type of PVCs, were the following: 1 - flake collection in the transfer filter: around 80 Kg / load, contaminated by layers of Dark black coffee residue that comes off after each polymerization charge. 2 - in the opening of the man-made hole after 20 loads (batches) the reactor had the following problems: a) reflux condenser with visible deposits in the lower jacket wall and with deposits beginning to form on the internal walls. b) very hard deposits, 4 mm thick, in the ducts that connect the reactor with the condenser. c) internal walls of the reactor fairly clean, but with considerable deposits in the waterline, for example, the liquid gas phase during the reaction. d) a large layer of deposits in the arrow and in correspondence of the 3 levels of agitation, weighing around 90 kg. e) other blocks of deposits in correspondence of the supports for the lateral breakwater. f) Safety valves and blast discs considerably covered, which had to be cleaned or replaced. In order to remove these deposits and restore the reactor to normal polymerization conditions, huge amounts of work were required and losses were recorded in industrial production. From an ecological point of view, the user had to dispose of large quantities of degraded PVC deposits that were contaminated by the used antiputrefacient agent. In a reactor of such dimensions were installed the formulations and production cycles, a vapor spray system for the antiputrefactive agent prepared as described in example 1. The treatment was carried out as follows: - 6 lt of an agent Antiputrefacient in a water solution prepared as described in Example 1, was charged in a stainless steel barrel having a volume of 15 l and pressurized with nitrogen having a pressure of 15 bar.

- A vapor is passed at a pressure of approximately 8 bars through a 2"pipe entering the reactor head - After 30 seconds of steam influx, the solution previously stored in the barrel was introduced into the tank. In this way, in just 1 second the water solution of the antiputrefacient agent was sprayed inside the reactor and on all the parts connected to it - During the application, the internal walls were maintained at a normal polymerization temperature (around 70 ° + 8 ° C) - Exploiting one of the main characteristics of the new product, and especially coagulation at a pH lower than 11, 90% of the loaded antiputrefactive agent coagulates and precipitates together with the condensed vapor and can therefore be removed of the reactor and sent to the recovery equipment without causing any contamination - During the discharge, only 200 lt of water is needed to rinse the container before the polymerization process; even this rinse water is subjected to the treatment and reclaimed together with the previously mentioned mother liquors. - After this application, the internal walls of the reactor appear as bright stainless steel walls that have a pale brown film, extremely thin, uniform and scratch resistant. Using this application technique after each load, it has been possible to reach 1000 consecutive loads carrying only periodic inspections every 50 loads. The acquired data were the following: a) The flake recovered in the suspension transfer filter (after each load): - 10 Kg, having a pale color and without traces of contamination. b) After 50 loads (first inspection): - Clean the reflux condenser and the connection lines perfectly. - Clean the minimum agitators and jet traces (a few grams) of PVC at the union of the bolts. - Clean perfectly the internal parts of the reactor, which have only a few deposits in the waterline. c) Without having cleaned, the reactor was closed and 25 more loads were carried out, observing the heat exchange capacity of the reactor, since the latter is the parameter most sensitive to the effects of the deposits on the walls of the reactor. After 250 loads, the inspection only revealed a slight worsening of the problems described in A and therefore it was decided to continue for an indefinite period.

After 1000 charges it was decided to interrupt the test and carry out the review of all internal parts. Then the small deposits in the agitated and in the blades were removed and the thermocouples were cleaned, and, surprisingly it was discovered that the upper parts of the reactor, the blasting discs, the relief valves, the charging lines and the reflux condenser and others, they were perfectly clean and did not need intervention. It should be added that with this new antiputrefacient agent, the high pressure water was sufficient to clean, without requiring specialized personnel equipment to enter the reactor in order to carry out this difficult and dangerous cleaning operation. After these results, which classify the product at least 20 times better than the conventional antiputrefacient agent used in other similar reactors of the same plant, it can be concluded that the new non-polluting agent (as in example 1) has definitely resolved the environmental and production problems lamented by this plant.

EXAMPLE 3 TESTS ON THE POLYMERIZATION OF LATEX (ABS) OF BUTADIENE OF ACRYLOSTIRENE In an industrial reactor of 28 m3, made of stainless steel iron, equipped with heating jacket, with two breakwaters and with a propeller-type stirrer, an emulsion polymerization of styrene-butadiene acrylonitrile was carried out to produce the basic latex for the production of ABS copolymers. The charge formulation normally used is the following: - Reactor filling: 80% - Water load: 65% - Butadiene load: 24.5% - Styrene load: 7% - Acrylonitrile load: 3.5% - Catalyst: persulfate - Emulsifier: resinous soap - Reaction temperature: 70 - 90ßC Normally, without preventive antiputrefactive treatment, the production cycle should be interrupted only after around 8 polymerization charges, due to the formation of polymer deposits consisting of internal parts of the reactor (walls, agitator and jetties). Such deposits reduce heat exchange between the reacting mass and the jacket, making it possible to control the polymerization temperature. Therefore, the reactor should be washed with toluene at 100 ° C for 18 hours in order to remove such deposits. In this polymerization process, the new antiputrefacient agent produced according to example 1 was tested by applying 1.5 l of this as previously described in example 2. Using this application technique after each load, it has been possible to reach 50 consecutive loads. , only doing periodic inspections every 15 loads. The results obtained were the following: - After 15 loads: There was no formation of deposits. - After 30 loads: There was formation of small deposits located only in some areas of the inner walls of the reactor. After 45 loads: There were more consistent deposits in some areas of the reactor and the waterline that, however, does not compromise the normal working procedure of the reactor. - After 50 charges: The reactor was washed in accordance with the normal procedure. In addition, it was proved that the application of the antiputrefactive agent did not influence even in a minimal way the qualitative characteristics of the finished product.

EXAMPLE 4 TESTS ON POLYMERIZATION IN POLYSTYRENE SUSPENSION HIGH IMPACT In a 45 m3 industrial reactor, made of stainless steel, equipped with a heating jacket, with two breakwaters and a propeller-type stirrer, a high-impact polystyrene (shock-proof) suspension polymerization was carried out. The charge formulation normally used is as follows: - Filling of the reactor: 32 tons. - Water / styrene + butidiene ratio: 0.8: 1.0 - Polyvinyl alcohol suspension agent: 0.15% Polymer composition: 90% reindeer / 10% polybutadiene - Polymerization temperature: 120 ° C - 160 ° C Normally, without preventive antiputrefactive treatment, the preventive cycle must be interrupted after approximately 40 polymerization charges, due to the formation of consistent polymer deposits located in particular in the upper part of the surge tank, on the shaft of the agitator and on the jetties. such deposits not only reduce the heat exchange between the reacting mass and the jacket, making it possible to control the polymerization temperature, but also the stability of the suspension. Therefore, the reactor must be washed with a solvent (toluene or ethyl benzene) at approximately 100 ° C for 20 hours, in order to remove deposits. In this polymerization process, the new non-polluting antiputrefactive agent produced according to example 1 was tested by applying 2.5 liters thereof as previously described in example 2. Using this application technique after each load, in the same interval time. and with the same number of loads, no deposits were detected in the internal parts that need to be washed with solvents. Therefore, 500 loads were carried out before having to wash the container. In addition, it was proved that by applying the antiputrefacient agent. the qualitative characteristics of the finished product did not change even in a minimal way.

EXAMPLE 5 TESTS ON POLYMERIZATION IN STYRENE EMULSION AND DIETILBENZOL In an industrial reactor of 10 m3, made of stainless steel, equipped with heating jacket, with two jetties and a propeller-type stirrer, an emulsion polymerization of styrene and diethylbenzene was carried out in order to produce ion exchange resins. The formulation of the charge normally used is the following: - Reactor filling: 85% - Water / monomer ratio: 1.0: 1.0 by weight - Catalyst: Organic peroxide. - Emulsifier: Cellulose compounds. Monomer composition: 50% reindeer / 50% diethylbenzene - Polymerization temperature: 65 - 85 ° C. Normally, without preventive anti-prophylactic treatment, the preventive cycle should be interrupted after 6-7 polymerization charges due to the formation of polymer deposits consisting of internal parts of the reactor (walls, agitator and breakwater). Such deposits reduce heat exchange between the reacting hub and the jacket, making it possible to control the polymerization temperature and modify the dynamic conditions of the agitation fluid. The reactor should, therefore, be flushed with toluene at 100 ° C for 10 hours in order to remove such deposits. In this polymerization process, the new non-polluting antiputrefactive agent produced according to example 1 was tested, applying 1.0 l of it as previously described in example 2.

Using this application technique after each load no deposit formation was detected during a productive cycle of at least 50 consecutive loads and without influencing the quality of the finished product. At the end of the experiment, normal production was carried out without an antiputrefactive treatment and an immediate formation of deposits was detected.

EXAMPLE 6 TESTS ON THE EMULSION POLYMERIZATION OF α-METILESTIRENE (α-SAN) In a 25 m3 industrial reactor, made of stainless steel, equipped with a heating jacket, with two breakwaters and a propeller-type stirrer, a polymerization of an emulsion of oc-metilesti reindeer was carried out in order to produce a-SAN. The formulation of the charge normally used is the following: - Filling of the reactor: 80% - Water load: 74% - Load of oc-metilesti reindeer: 26% - Catalyst: Common hydroxy peroxide - Emulsifier: Resinous soap. - Tempe ratu ra of reaction: 70 -90PC. Normally, without preventative antiput treatment, the preventive cycle must be interrupted after around 20 polymerization charges, due to the formation of consistent polymer deposits located in particular on the shaft of the agitator and on the jetties. These deposits modify the dynamic conditions of the agitation fluid, and therefore, the production must be interrupted, and the reactor washed with toluene. In this polymerization process, the new non-polluting antiputrefacient agent was tested according to example 1 by applying 1.5 l of it, as previously described in example 2. Using this application technique after each load, no deposits were detected they require washing with solvents, in the same interval and with the same number of charges. In addition, it was proved that the application of the antiputrefacient agent did not have a minimal influence on the qualitative characteristics of the finished product.

Claims (17)

NOVELTY OF THE INVENTION CLAIMS

1. - An antiputrefacient material to be applied as a protective coating of the internal walls of a polymerization reactor, which has naphthenic molecules of aromatic structure with radicals placed from 1 to 8, according to the following arrangement: comprising at least one of these radicals, at least one sulfur atom (S) and further characterized in that the antiputrefacient material contains sulfur greater than 0.25% by weight, and wherein said radicals containing a sulfur atom, they occupy at least one of the positions. 2, 3 and 4 of the following structure:

R (S) where R (S) represents a radical containing a sulfur atom (S), in any of positions 2, 3 or 4, or also in more than one of said positions and in which said radical also has at least one sodium atom or other brackish alkali metal -R (S, 0, Na) characterized in that in said radical is the presence of a methylenic group (CH2), said radical assuming the following structure: -CH2S0nNa where "n" it is variable from 2 to 3, and where: the characteristic of its structure is provided and limited in order to: - in the absence of oxygen it appears in the form of a clear transparent color, i if: - in the presence of oxygen, it becomes a bluish or dark color, and if: - the contact with oxygen is interrupted, it reverts to its original appearance. 2. An antiputrefacient material according to the preceding claims, further characterized in that in said radical there is the presence of a binder group (CH), said radical assuming the following structure: said radical being intended to join two identical and opposite naphthenic aromatic groups where "n" is variable from two to three.

3. An antiputrefacient material according to claims 1 and 2, further characterized in that the naphthenic structure has a radical (OH), in the position 1 according to the following structure: the positions 2, 3 or 4 being capable of being occupied by a radical containing at least one sulfur atom and the positions 2 or 4 being capable of constituting an intermediate link bridge between two identical and opposite naphthenic structures. Q | - |

4. - An antiputrefacient material according to the preceding claims, further characterized in that it has at least one molecule having the following structure: OH CH2SOnNa where "n" is variable from two to three.

5. An antiputrefacient material according to the preceding claims, further characterized in that it has at least one molecule of the following structure: CH2S0nNa where "n" is variable from two to three.

6. An antiputrefacient material according to the preceding claims, further characterized in that it has at least one molecule having the following structure: OH OnNa where "n" is variable from two to three.

7. An antiputrefacient material according to the preceding claims, further characterized in that it has at least one molecule of the following structure: where "n" is variable from two to three.

8. An antiputrefacient material according to the preceding claims, further characterized in that it has at least one molecule of the following structure: where "n" is variable from two to three.

9. An antiputrefacient material according to the preceding claims, further characterized in that it contains hydrosulfite.

10. An antiputrefacient material according to the preceding claims, further characterized in that it contains sodium hydrosulfite.

11. An antiputrefacient material according to the preceding claims, further characterized in that it contains bisulfite.

12. An antiputrefacient material according to the preceding claims, further characterized in that it contains sodium bisulfite.

13. An antiputrefacient product according to the preceding claims, further characterized because it is contained in hermetic containers, and impermeable to oxygen.

14. An antiputrefacient product according to the preceding claims, further characterized in that it is contained in containers pressurized with inert gas.

15. An antiputrefacient product according to the preceding claims, further characterized in that it is contained in containers pressurized with nitrogen.

16. An antiputrefacient product according to the preceding claims, further characterized in that it is contained in containers of plastic material (PET) of polyethylene terphthalate.

17. An antiputrefacient product according to the preceding claims, further characterized in that it is contained in plastic bottles of polyethylene terephthalate.