MXPA96004894A - Process for the elimination of material contaminant of water or solid material hum - Google Patents

Abstract

The present invention relates to a process for removing unwanted material from the desired material, in the presence of water, by contacting an isocyanate-containing prepolymer with the materials, allowing the prepolymer to react with at least part of the water to forming a flexible foam and removing the foam obtained from the desired material, the prepolymer has an NCO value of 5-10% by weight and is the reaction product obtained by the reaction of an excessive amount of a polymethylene-polyphenylene polyisocyanate or diisocyanate of diphenylmethane comprising at least 25% by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof, with a polyether polyol having a nominal hydroxyl functionality, average, from 2 to 4, a hydroxyl equivalent weight average, in number, from 500 to 3000, and an oxyethylene content of at least 50% by weight, the amount of prepolymer used being from 5 to 200 parts by weight per 100 parts in weight of the material you do not want

Description

i 'PROCESS FOR THE ELIMINATION OF CONTAMINATING MATERIAL FROM WATER OR SOLID WET MATERIAL The present invention relates to a process for removing unwanted material from the desired material, using a certain polymer. British Patent GB1170959 and US Pat. No. 3869385 have described the spraying of appropriate formulations for the manufacture of foam.

\ Q of polyurethane on water or sand, in order to remove oil. European patent EP-370349 describes the use of an isocyanate-terminated prepolymer for the removal of hydrocarbons, in particular oil, by the preparation of a gel. Removal of the gel could be problematic since its resistance is relatively weak. European patent EP-370349 describes the use of a prepolymer having an NCO value of 4.2% by weight, which has been made from 0 of toluene dilsoclanate and a polyether polyol, to which it has been added at the end about 2% by weight of propylene oxide. German patent DE3315596 describes the use of polyurethane prepolymers made from 5 polyether polyols comprising 70-95% by weight of ethylene oxide units and polyisocyanates, as flocculation agents, in order to clean water containing waste industrial. The flocculated waste is precipitated and could therefore be difficult to recover. Two prepolymers have been used, which have an NCO value of 7% by weight, and which were made from a polyol comprising EO and PO units in a weight ratio of 75/25, and having a nominal functionality of 3 and a molecular weight of 4000; one prepolymer has been prepared from toluene diisocyanate and the other from a 50/50 w / w mixture of 2,4'- and 4,4'-di-phenyl-methane diisocyanate. The amounts of the prepolymer used are small. European patent EP-415127 also describes the use of prepolymers as flocculation agents. Surprisingly, it has been found that by using a certain amount of a special prepolymer, the unwanted material can be removed from the desired material in the presence of water, causing this prepolymer to come into contact with the materials. The prepolymer reacts with the water present and forms a flexible foam, whose foam comprises the undesired material. The flexible foam can be easily removed from the desired material.

Accordingly, the present invention is related to a process for the removal of unwanted material from the desired material, in the presence of water, by placing the isocyanate-containing prepolymer in contact with the materials, allowing the prepolymer to react with at least part of the water to form a flexible foam and removing the foam obtained from the desired material, the prepolymer has an NCO value of 5-10% by weight, and is the reaction product obtained by the reaction of an excessive amount of a polymethylene polyisocyanate. polyphenylene or diphenylmethane cyanate dies, comprising at least 25% by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof with a polyether polyol having a nominal hydroxyl functionality, average, from 2 to 4 , an average hydroxyl equivalent weight, in number from 500 to 3000, and an oxyethylene content of at least 50% by weight, the amount used being prepolymer or from 5 to 200 parts by weight per 100 parts by weight of the unwanted material. Although other materials may be used in conjunction with the prepolymer, it is preferred to use the prepolymer without additional material in the process according to the present invention. The unwanted material in the context of the present application is a material which is in contact with another material - the desired material - and which is considered to be a contaminant of the desired material, and which therefore has to be removed or separated from said desired material. The desired material is the material from which the unwanted material is to be removed or separated. The combinations of the unwanted / desired material are for example oil / water, paint / water, ink / water, oil / wet sand (beach), oil / wet rocks T other petroleum / water products. In particular, the process is useful for removing oil and other water-insoluble hydrocarbons from water. In the case where the desired material is not water, it must comprise enough water to allow the prepolymer to react. In general, the amount of water must be at least 20 parts by weight per 100 parts by weight of the applied prepolymer. . If the amount of water is less, the water must be added; in general, an amount of water added from 20 to 500 and preferably from 40 to 400 parts by weight per 100 parts by weight of applied prepolymer will suffice. The amount of prepolymer used may be in the range of 5 to 200, preferably 10 to 100, more preferably 20 to 80 parts by weight per 100 parts by weight of unwanted material. In practice, the amount of unwanted material can be estimated. If the amount was estimated too low the process can be repeated, and if the amount was estimated too high, some additional foam is formed. The prepolymer can be contacted with the materials, in a known manner, for example, spraying, pouring and beating. If desired, the prepolymer can be mixed with the materials. If desired, the prepolymer is contacted with the materials, such as a foam, which is obtained by the addition of steam, water or an inert gas, such as CO 2 or air, to the prepolymer, for example by means of a spray nozzle. . In addition, if desired, the prepolymer can be applied together with a diluent as an ester type plasticizer, for example, phthalate and propylene carbonate. The prepolymer is preferably allowed to react under ambient conditions. The process can even be applied at low ambient temperature, as long as this * sufficient water (liquid) is present. The prepolymer reacts with at least part of the water, depending on the amount of water available. In the sea the prepolymer, of course, reacts only with a smaller portion of water. When only a limited amount is available, for example 20 parts of water per 100 parts of prepolymer, all the water can be used in the reaction. In general, the reaction is complete in 1 to 15 minutes. The foam obtained contains unwanted material: it is included, absorbed and / or adsorbed. The flexible foam is then removed from the desired material, in any known manner. This can be taken or pulled from the desired material and subsequently dried and cut into small pieces and / or compressed. The collected foam, after drying preferably, and suitably is used for energy recovery. The polyisocyanate used in the preparation of the prepolymer can be selected from polyphenylene-polymethylene isocyanate po-1 comprising at least 25, preferably at least 50, and more preferably at least P.5S by weight diisocyanate of 4, '- ^ ifenylmethane (4,4'-MDI) or a liquid variant thereof. Preferably, the polyisocyanate has an isocyanate functionality of 2.0 to 3, preferably 2.0 to 2.3, more preferably 2.0 to 2.1. In the context of the present invention the term polymethylene-phenylene polyisocyanates includes diphenylmethane diisocyanates and oligomers thereof, known in the art as crude or polymeric MDI, having an isocyanate functionality greater than 2. The polyisocyanate it may consist essentially of pure 4,4'-diphenylmethane diisocyanate or mixtures of this diisocyanate with other isomers of diphenylmethane diisocyanate, for example the 2,4'-isomer optionally in conjunction with the 2,2'-isomer. The polyisocyanate can also be a variant of MDI derived from a polyisocyanate composition containing at least 25%, preferably at least 50% and more preferably at least 85% by weight of 4,4'-diphenylmethane diisocyanate. MDI variants are well known in the art and, for use according to the invention, include particularly liquid products obtained by the introduction of uretonimine and / or carbodiimide within said polyisocyanates, such as a carbodiimide-modified polyisocyanate and / or uretonimide, preferably having an NCO value of at least 25% by weight, and / or by reacting such a polyisocyanate with one or more polyols having a hydroxyl functionality of 2 to 6 and a molecular weight of 62-1000, to obtain a modified polyisocyanate, preferably having an NCO value of at least 25% by weight. The polyisocyanate may comprise minor amounts of polymethylene poly (phenylene) polyisocyanates having an isocyanate functionality greater than 2.; this amount is preferably such that the isocyanate functionality of the total polyisocyanate is 2.0 to 3, more preferably 2.0 to 2.3, more preferably 2.0 to 2.1. The polyol used in the preparation of the prepolymer preferably has an average nominal hydroxyl functionality of 2.5-3.5, an average hydroxyl equivalent weight in the number of 1000-3000 and an oxyethylene content of 50 to 85% by weight. The polyether polyols used in the preparation of the prepolymer include, products obtained by polymerization of ethylene oxide optionally together with another cyclic oxide such as tetrahydrofuran and, preferably, propylene oxide in the presence of polyfunctional initiators. Suitable initiator compounds contain a plurality of active hydrogen atoms and include water, butanediol, ethylene glycol, propi enplicol, diethylene glycol, triethylene glycol, dipropylene glycol, ethanolaraine, diethanolamine, triethanolamine, toluenediamine, diethylene toluene diamine, phenyl. -diamine, diphenylmethane diamine, ethylene diamine, cyclohexane diamine, cyclohexane dimethanol, resorcinol, bis bisol A, glycerol, triamotechpropane, 1,2,6-hexanotriol and pentaerythritol. Mixtures of initiators can be used The polyol can be obtained by the simultaneous addition or sequence of ethylene oxide and the other cyclic oxide to the initiator. The sequential addition can be conducted in any order. The sequential addition will give type rail polyols called block copolymers. Simultaneous addition will give polyols of the so-called random type. The most preferred, random polyoxyethylene-polyoxypropylene polyols have an oxyethylene content of 50 to 85% by weight. In order to obtain the preferred polyol having an average nominal hydfoxyl functionality of 2.5 to 3.5, a polyol having a nominal hydroxyl functionality of 3, or a mixture of polyols, which may have other hydroxyl functionality, may be used. nominal, average, with the proviso that the mixture is in the range of functionality above 2.5-3.5. The term "average nominal hydroxyl functionality" is used herein to indicate the average functionality (number of hydroxyl groups per molecule) of the polyol in the assumption that the average functionality of the polyoxyalkylene polyols present therein is identical with the the average functionality (number of active hydrogen atoms per mélecule) of the initiator or initiators used in its preparation, although in practice it is frequently somewhat smaller due to some terminal unsaturation. The prepolymer is conventionally prepared by reacting the polyisocyanate and the polyol at relative amounts, to obtain an NCO value of 5-10% by weight, at a temperature preferably between 40 and 100 ° C. The prepolymers thus prepared are liquid at ambient conditions. The polyisocyanates, polyols, prepolymers and the forms for preparing them are known as such; see for example European patent EP-547765. The stability of the prepolymer can be improved by the addition of a small amount of an organic or Lewis acid, such as benzoyl chloride, thionyl chloride and paratoluene sulphonic acid. The present invention is illustrated by the following examples.

EXAMPLE 1 A prepolymer is prepared by the reaction of 30 parts by weight of 4,4'-MDI and 70 parts by weight (pbw) of an E0 / P0 polyol having a molecular weight of 4000, a nominal functionality of 3 and content of EO 75% by weight (random). The NCO value of the prepolymer was 7.8% by weight (prepolymer 1). A number of 250 ml glass flasks were filled. with 120 ml. of water, followed by 2 grams. of oil for used motor. The flasks were shaken perfectly to mix the water and the oil. Subsequently, an amount of the aforementioned prepolymer was added. The flasks were vigorously shaken again for 2-3 seconds. A layer of flexible foam was formed on top of the water. The foam was taken from the water after 1-3 minutes. The amount of prepolymer used, the type of water used and the quality of the water after the flexible foam was removed are given in the following table.

TYPE OF WATER QUANTITY OF PREPLOYER QUALITY OF WATER (grams) Of the tap 0.24 Some oil in the emulsion From the tap 0.4 Some oil in the emulsion From the tap 0.5 No visible oil Faucet 0.9 No visible oil Faucet 1.6 No visible oil From sea 1.3 No visible oil In all cases a small amount of white precipitate was observed in the water after the foam was removed. It is believed that this precipitate is no longer reactive and is environmentally non-harmful, and that it contains a substituted urea resulting from a reaction of a reaction product of MDI and water with an additional MDI, which did not contribute to the formation of the flexib1e foam.

EXAMPLE 2 Prepolymers having an NCO value of 7.8% by weight were prepared from the polyol used in Example 1 and toluene diisocyanate (prepolymer 2) and a 50/50 weight / weight mixture of 4,4'-MDI and 2, 4 '-MDI (prepolymer 3). The prepolymers were prepared as in example 1. The oil removal experiment of example 1 was repeated with 150 ml. of water, 10 grs. of used oil for engine and varying amounts of different prepolymers. The amounts and type of prepolymer and the results are given in the following table.

PREPOLIMERO QUANTITY R E S U L T A D O (grams) 1 2.5 No visible oil in water; flexible foam was formed which contained oil. 1 2.5 Loose pieces of polymer were formed; no flexible foam was formed 3 2.5 No visible oil in water; flexible foam was formed which contained - the oil. 1 0.15 Flexible foam with low resistance; some oil visible in water. 3 0.15 Flexible foam with weak resistance; most oil visible in water. 1 0.015 Porous cake; most of the oil in water. 3 0.015 Loose pieces of foam; Most of the oil in the water.

The tests with the prepolímero 2 and with quantities of 0.15 and 0.015 grs. they are comparative tests.

Claims (5)

REVINDICATIONS

1. A process for the removal of unwanted material from the desired material, in the presence of water, by contacting an isocyanate-containing prepolymer, with the materials, allowing the prepolymer to react with at least part of the water to form a flexible foam and eliminating the foam obtained from the desired material, the prepolymer has an NCO value of 5-10% by weight and is the reaction product obtained by the reaction of an excessive amount of a polymethylene polyphenylene polyisocyanate or diphenylmethane diisocyanate comprising at least 25% by weight. % by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof, with a polyether polyol having a nominal hydroxyl functionality, average, from 2 to 4, an average hydroxyl quivalent weight, in number , from 500 to 3000, and an oxyethylene content of at least 50% by weight, the amount of prepolymer being used from 5 to 200 parts by weight per 100 parts by weight of the undesired material.

2. The process according to claim 1, characterized in that the amount of prepolymer is 10 to 100 parts by weight per 100 parts by weight of the undesired material.

3. The process according to claim 1 is characterized in that the polyisocyanate comprises at least 85% by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof.

4. The process according to any of claims 1 to 3, characterized in that the polyol has an oxyethylene content of 50 to 85% by weight.

5. The process according to any of claims 1 to 4, characterized in that the polyol is a random polyoxyethylene-polyoxypropylene polyol. SUMMARY A process for removing contaminating material from water or wet mate- rial is described, by contacting an isocyanate-containing prepolymer with the materials, allowing the prepolymer to react with the water to form a flexible foam and removing the foam. of water or solid matter.