MXPA98000034A - Process to remove unwanted material dematerial dese - Google Patents

Abstract

The present invention relates to a process for removing unwanted material from 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 removing the foam obtained from the desired material, the prepolymer having an NCO value of 2-10% by weight and the reaction product being obtained by reacting an excess amount of polymethylenemethylene-polyphenylene polyisocyanate comprising at least 25% by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof with a polyether polyol having an average nominal hydroxyl functionality of 2 to 4, an average hydroxyl equivalent weight in the number of 500 to 3000, and an oxyethylene content of at least 50% by weight, the amount of the prepolymer used being from 5 to 200 parts by weight per 100 parts by weight of the unwanted material or, characterized in that the prepolymer is combined with 2-100 parts by weight of water per part by weight of the prepolymer in more than 20 seconds before it is brought into contact with the materials

Description

PROCESS P A R: A RE M O VE R JWATE RJA_ L _NO_D IS ADO_D E MA TERIAL D E SE DO D ESC R I PC I O N D I N N I N N G L IS H The present invention relates to a process for removing unwanted material from desired material using a certain polymer. In GB1 1 70959 and US3869385 it has been described to spray suitable formulations to be polyurethane foam in water or sand to remove oil. DE331 5596 describes the use of polyurethane prepolymers, made of polyether polyols comprising 70-95% by weight of ethylene oxide units and polyisocyanates, as flocculating agents for the purpose of cleaning water comprising industrial waste. The flocculated waste is precipitated and therefore, it could be difficult to remove. Two prepolymers, having an NCO value or 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, have been used; a prepolymer making toluene diisocyanate and the other a mixture of 50/50 p / p of 2,4 'diisocyanate and 4-4'-diphenylmethane. The amounts of the prepolymer used are small. EP-41 5127 also describes the use of prepolymers as flocculation agents. EP-370349 describes the use of an isocyanate-terminated prepolymer to remove hydrocarbons, in particular oil, by preparing a gel. Removal of the gel becomes difficult because its resistance is rel evantly weak. EP-370349 describes the use of a prepolymer ro having an NCO value of 4.2% by weight, which has been made of toluene diisocyanate and a polyether polyol, which has been drained with about 2% by weight of propylene oxide. Furthermore, it is disclosed that the prepolymer can be mixed with water before the polymer prepoly comes in contact with the oil. On the smallest axis, the prepolymer is combined with water and mixed thoroughly for 25 seconds before it is combined with the oil. It is believed that this premix with water is conducted in order to achieve a certain degree of pre-reaction of the prepolymer and water; without such long mixing time, that under field conditions, could be and practically long, only lumps could be obtained, which could not be recovered. The copending application PCT / EP95 / 01 51 7 describes the use of a prepolymer, made of 4,4'-M DI and of a polyol having an oxyethylene content of 50-85% by weight, to remove oil spills from the Water. Furthermore, it is described that the prepolimer may be contacted with the oil / water as a broth, which is obtained by adding water to the prepolymer. Surprisingly, it has been found that the process for removing water oil using the prepolymer can be further improved by adding a certain amount of water to this prepolymer a few instants before the prepolymer comes into contact with the oil / water. The use of water reduces the viscosity of the prepolymer and changes the surface tension to such a degree that it is easier to apply the prepolymer to the oil / water: suitable spray patterns are obtained (fine droplets), especially when a spray gun is used , wherein the prepolymer and the water are mixed, and a relatively high output of the prepolymer of this spray gun can be obtained; without this water, the outlet is low and the prepolymer leaves the nozzle of the gun as a jet stream. Furthermore, it was shown that the flexible foam, which is obtained after the prepolymer / water mixture has been combined with the oil / water and which contains the oil, is able to retain the oil very well after the foam has been removed from the surface of the water. Since the water is added to the prepolymer only a few moments before the prepolymer comes into contact with the oil / water, no significant pre-reaction occurs, particularly not when the water is applied at a temperature of 5-35. ° C. Consequently, the present invention relates to a process for removing unwanted material from 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 removing the foam obtained from the desired material, the prepolymer having an NCO value of 2-10% by weight preferably 5-1 0% by weight, and the reaction product being obtained by reacting an excessive amount of the polymethylene polyphenylene polyisocyanate comprises at least 25% by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof with a polyether polyol having an average nominal hydroxyl functionality of 2 to 4, an average hydroxyl equivalent weight in the number of 500 at 3000, and an oxyethylene content of at least 50% by weight, the amount of the prepolymer used being from 5 to 200 parts by weight per one hundred parts by weight. unwanted material weight, characterized in that the prepolymer is combined with 2-100, preferably 5-50 parts by weight of water per part by weight of the prepolymer in almost 20 seconds, preferably almost 10 seconds and most preferably almost 5 seconds before he comes in contact with the materials. This combination of 2-100 parts of water and a part of the prepolymer can be conducted through methods known in the art. The prepolymer can be added to the water or the water can be added to the prepolymer, optionally followed by mixing, before the prepolymer comes into contact with the materials. Advantageously, a device which is capable of applying a spray of liquid droplets on a surface, such as a spray gun, such a device is connected to a water supply and a supply of prepolymer, such supplies are combined in a supply before from the mouthpiece of the device. Surprisingly, it has been found that large quantities of water maintained at room temperature (5-35 ° C) could delay the reaction with the prepolymer for a sufficiently long time that could allow the use of water as a viscosity reducer of the polyisocyanate prepolymer. In addition, the present invention relates to the use of water as a viscosity reducer for a prepolymer having an NCO value of 2-10% by weight, and the reaction product being obtained by reacting an excessive amount of the polymethylene polyisocyanate. polyphenylene comprising at least 25% by weight of 4,4'-dimethylphenylmethane diisocyanate or a liquid variant thereof with a polyether polyol having an average nominal hydroxyl functionality of 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 water being used in an amount of 2 to 100 parts by weight per one part by weight of prepolymer. Although other materials than water can be used together with the prepolymer, it is preferred to use the prepolymer without additional material in the process according to the invention. The unwanted material in the context of the present application is a material that is brought into contact with another material-the desired material-and which is considered a contaminant of the desired material and which, therefore, must be removed separately from the material. desired material. The desired material is the material from which the unwanted material has to be removed separately. Combinations of unwanted / desired material are, for example, water / water, paint / water, ink / water, oil / sand (sea, beach), oil / rocks, other petroleum / water products and industrial waste / water.

In particular, the process is useful for removing oil or other insoluble hydrocarbons in water from water. The amount of prepolymer used can vary from 5 to 200, preferably from 10 to 100, most preferably from 20 to 80 parts by weight per 100 parts by weight of the unwanted material. In practice, the amount of unwanted material can be estimated. If the quantity was estimated too low, the process can be repeated and if the quantity was estimated too high some additional foam is formed. The prepolymer / water mixture can be contacted with the materials in any known manner, for example, spraying, pouring and beating. If desired, the prepolymer can be mixed with the materials. The prepolymer is preferably allowed to react under ambient conditions. The process can still be applied at low ambient temperature, as much as is present-liquid-is present. The prepolymer reacts with part of the water to form a flexible foam. In general, the reaction is completed in 1 to 15 minutes. The foam obtained contains unwanted material: it is included, absorbed and / or absorbed. The flexible foam is then removed from the desired material in a known manner. It can be taken or pushed out of the desired material and subsequently dried and cut into smaller pieces and / or compressed. The collected foam, preferably after drying, can be used for energy recovery. The polyisocyanate used to make the prepolymer can be selected from polymethylene-polyphenylene polyisocyanates comprising at least 25, preferably at least 50 and most preferably at least 85% by weight of 4,4'-diphenylmethane diisocyanate (4 , 4 'MDI) or a liquid variant thereof. Preferably, the polyisocyanate has an isocyanate functionality of 2.0 to 3, more preferably 2.0 to 2.3, most preferably 2.0 to 2.1. In the context of the present invention, the term polymethylene-polyphenylene polyisocyanates include diphenylmethane diisocyanates and oligomers thereof, known in the art as unpurified or polymeric MDI, having an isocyanate functionality of greater than 2. The polyisocyanate may essentially consist of of pure 4,4'-diphenylmethane diisocyanate or mixtures of this diisocyanate with other isomers of diphenylmethane diisocyanate, for example, the 2,4'-isomer optionally together with the 2,2'-isomer. The polyisocyanate can also be a variant of MDI derived from such a polyisocyanate containing at least 25%, preferably at least 50% and most preferably at least 85% by weight of 4,4'-diphenylmethane diisocyanate. MDI variants are well known in the art and, for use in accordance with the invention, particularly include liquid products obtained by introducing uretonimine and / or carbodiimide groups in such polyisocyanates, such as a carbodiimide-modified polyisocyanate and / or uretonimine preferably having a NCO value of at least 25% by weight, and / or by reacting such polyisocyanate with one or more polyols having a hydroxyl functionality of 2-6 and a molecular weight of 62-1000 in order to obtain a modified polyisocyanate, preferably having an NCO value of at least 25% by weight. The polyisocyanate may comprise minor amounts of polymethylene-polyphenylene polyisocyanates having an isocyanate functionality greater than 2; this amount preferably is such that the isocyanate functionality of the total polyisocyanate is 2.0 to 2.5, more preferably 2.0 to 2.3, most preferably 2.0 to 2.1. The polyol used to prepare the prepolymer preferably has an average nominal hydroxyl functionality of 2-4 and most preferably 2.5-3.5, an average hydroxyl equivalent weight in the number of 1000-3000 and an oxyethylene content of 50 to 85% in weight. The polyether polyols used to prepare the prepolymer, include products obtained by the polymerization of ethylene oxide optionally together with another cyclic oxide such as tetrahydrofuran, butylene oxide 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, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, ethanolamine,. diethanolamine, triethanolamine, toluenediamine, diethyltoluenediamine, phenyldiamine, diphenylmethanediamine, ethylenediamine, cyclohexanediamine, cyclohexanedimethanol, resorcinol, bisphenol A, glycerol, trimethylolpropane, 1,2,6-hexanetriol and pentaerythritol. Mixtures of initiators can be used. The polyol can be obtained by the simultaneous or sequential addition 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 polyols of the so-called block copolymer type. The simultaneous addition will give polyols of the so-called random type. Random polyoxyethylene-polyoxypropylene polyols are more preferred, have an oxyethylene content of 50 to 85% by weight. In order to obtain the most preferred polyol having an average nominal hydroxyl functionality of 2.5 to 3.5 a polyol having a hydroxyl II functionality nominal 3 can be used or a mixture of polyols, which each can have other average nominal hydroxyl functionality providing the mixture in the scale of previous functionality 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 on the assumption that the average functionality of the polyoxyalkylene polyols present therein is identical with the functionality average (number of active hydrogen atoms per molecule) of the initiator or primers used in its preparation, although in practice they will usually be somewhat smaller due to some terminal unsaturation. The term "average" refers to an average number in the present specification. The prepolymer is conventionally prepared by reacting the polyisocyanate and the polyol in relative amounts in order to obtain an NCO value of 2-10% and preferably 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 forms for preparing them are known as such; see, for example, EP-547765.

The present invention is illustrated through the following examples.

Example 1 A prepolymer is prepared by reacting 30 parts by weight of 4,4'-MDI and 70 parts by weight (ppp) of an EO / PO polyol having a molecular weight of 4000, a nominal functionality of 3 and an EO content of 75% by weight (random). The NCO value of the prepolymer was 7.8% by weight (prepolymer 1). A 1 liter plastic cup was filled with 120 ml of water followed by 40 g of used motor oil. To this cup, 400g of water and 20g of prepolymer 1 were added after being mixed for 5 seconds. Then, the contents of the flask were mixed thoroughly and allowed to react. After 5 minutes, a coherent flexible foam was removed from the surface of the water, such foam contained all the oil. The foam retained the oil for more than a day after it had been removed from the surface of the water.

Comparative Example 2 A container, having a diameter of 1 70 cm, was filled with water (the height of the water level was 40 cm from the bottom of the container). It was emptied to 1 liter of old motor oil or water and allowed to spread on the surface. Then, 300 g of prepolmer 1 was added through a spray gun with an air discharge nozzle. The gun with a length of 1 2 cm and a diameter of 7 mm; The nozzle was maintained at a distance of 1 meter from the surface of the oil. The maximum obtainable output of the prepol polymer was 1 50 g per my nuto (gun pressure applied 8 absolute bars). The prepolymer left the nozzle as a jet. The prepolymer was allowed to react for 10 minutes. Part of the prepol polymer was submerged to the bottom of the container and formed lumps of foam. Part of the flexible foam could be removed from the surface; this foam contained less than 2/3 of the oil.

Example 3 Example 2 was repeated with the proviso that water and prepolymer 1 were combined in a weight ratio of 20: 1 at the beginning of the gun (and therefore 12 cm from the nozzle). The prepolymer / water mixture left the nozzle as a spray of fine droplets. The output was 21 liters per minute. The spray was conducted for approximately 30 seconds at 6 bar absolute. The time between the combination of the prepolymer and the water and the contact of this combination with the oil / water could be calculated to be approximately 0.1 second. A coherent flexible foam containing all the oil was removed. There were no lumps in the bottom. The foam was able to retain all the oil for more than 1 day.

Example 4 Example 3 was repeated with the proviso that the spray gun had a simple nozzle (without air discharge). The result was the same.

Claims (12)

REI VI N D I CATION ES

1 . A process for removing unwanted material from 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 remove the foam obtained from the material desired, the prepolymer had an NCO value of 2-10% by weight and the reaction product obtained by reacting an excess amount of polyethylenemethane-polyethylene polyisocyanate comprising at least 25% by weight diisocyanate of 4,4-diphenyl methane or a liquid variant thereof with a polyether polyol having a nominal hydroxyl functional average of 2 to 4, an average hydroxyl equivalent weight in the number of 500 to 3000, and a content of oxyethylene of at least 50% by weight, the amount of the prepolymer used being from 5 to 200 parts by weight per 100 parts by weight of the undesired material, characterized in that the The prepolymer is combined with 2-1 00 parts by weight of the water per part by weight of the prepolymer in more than 20 seconds before it comes into contact with the materials.

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

3. The process according to claims 1-2, 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 claims 1-3, characterized in that the polyol has an oxyethylene content of 50 to 85% by weight.

5. The process, according to claims 1-4, characterized in that the polyol is a random polyoxyethylene-polyoxypropylene polyol.

6. The process, according to claims 1-5, characterized in that the water is contacted with the prepolymer at least 5 seconds before the prepolymer is contacted with the materials in an amount of 5-50 parts of water per part of prepolymer.

7. The process, according to claims 1-6, characterized in that the NCO value of the prepolymer is 5-1 0% by weight.

8. The use of water as a viscosity reducer for a prepolymer having an NCO value of 2-10% by weight and the reaction product being obtained by reacting an excessive amount of the polyethylene-polyethylene polyisocyanate characterized in that it comprises less 25% by weight of the 4,4'-diphenylmethane diisocyanate or a liquid variant thereof with a polyether polyol having an average nominal hydroxyl functionality of 2 to 4, an average equiv. weight of hydroxyl in number of 500 at 3000, and an oxyethylene content of at least 50% by weight, the water being used in an amount of 2 to 1000 parts by weight per part by weight of the prepol.

9. The use according to claim 8, characterized in that the polyisocyanate comprises at least 85% by weight of 4,4'-diphenylmethane diisocyanate or a liquid variant thereof.

10. The use, according to claims 8 and 9, characterized in that the polyol has an oxyethylene content of 50 to 85% by weight.

11. The use, according to claims 8-10, characterized in that the polyol is a random polyethylene-polyoxypropylene polyol.

12. The use, according to claims 8-11, characterized in that the NCO value of the prepolymer is 5-10% by weight. i and SUMMARY OF THE INVENTION A process for removing unwanted material from desired material containing water 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 obtained from the desired material.