MXPA98006860A - Reduction of polyoline amino contents recicla - Google Patents

Abstract

In a process for reducing the content of primary amines of a composition containing at least one polyol, in which a composition containing at least one polyol is mixed with at least one isocyanate containing only secondary and / or tertiary isocyanate groups, aliphatically united, the isocyanate is added in an amount of up to 5% by weight, based on the total composition and the preparation of a poly is obtained

Description

REDUCTION OF THE CONTENTS OF RECYCLED POLYOLINE AMINES The present invention relates to a process for reducing the content of primary amines of a composition comprising at least one polyol (deamination), wherein the composition containing at least one polyol is mixed with at least one isocyanate containing only groups secondary and / or tertiary isocyanates aliphatically bound. In addition, the invention relates to the use of these isocyanates to reduce the primary amine content of the composition containing at least one polyol (deamination). In the search for opportunities to recycle polymeric plastic materials, in particular polyaddition polymers, the glycolytic dissociation of systems containing polyurethane has proved useful in the field of polyurethanes or polyurethane-containing plastics. The objective of this process is to convert the polyurethanes and / or polyurea-polyurethanes into liquid products containing OH groups by reacting with compounds containing at least two OH groups to reduce the molecular weight. In the technical circle, the word "recycled polyols" has been established for those products that contain OH since these are obtained from the plastic products used or scrap manufactured in a reprocessing step. The recycled polyols can be, for example, reused to produce polyurethane materials, in particular to produce rigid PU foams, but also to produce sealant compositions. The processes for the glycolytic dissociation of the Polyurethane-containing polymers have been known for a long time. In the literature, the term "glycolysis" is often used instead of the term * "glycolytic dissociation". This term should not be confused with the biochemical degradation of the energy reserves of the glycogen body or starch in the human or animal body as described under the name "glyco-lysis" in important reference works (see, for example, Rompps Che ie Lexi on, 10th ed., Page 1579). In the present text, the term "glycolytic dissociation" will therefore be used to avoid ambiguity. For the purposes of this document, "dissociation * "glycolytic" means a process in which a polymer is dissociated with the aid of at least one dihydric alcohol to reduce molecular weight.20 The present methods for glycolytic dissociation is distinguished by glycols, catalysts and reaction conditions employees, usually using the glycols in a large stoichiometric excess The known processes for glycolytic dissociation also form, for example, as a result of the water content of # the glycols or by means of the glycolytic dissociation of the urea groups, the precursor amines of the isocyanates originally used to produce the polyurethane. The presence of these generally primary amines has a adverse effect on the processing properties of the composition containing at least one polyol formed by means of glycolytic dissociation. For example, the amines present in the composition containing at least one polyol catalyze a future reaction with the isocyanates to give polyurethanes, so that it is generally not possible to achieve sufficiently long processing times. In addition, urea compounds formed from amines and isocyanates usually have an adverse influence on the properties of the polyurethane material. resulting from the isocyanates and the composition containing at least one polyol. Another disadvantage of the presence of * Primary amines in the composition containing at least one polyol obtained by glycolytic dissociation is the normally toxic properties of these amines. Given the Polyurethanes are generally produced at least in part using aromatic isocyanate compounds, glycolytic dissociation forms primary aromatic amines whose carcinogenic, teratogenic and sometimes mutagenic potential is sufficiently well known. 25 Therefore, there have been attempts to convert the amines present in a polyol preparation in compounds that are "non-harmful" in terms of what has been mentioned in the above, by reaction with compounds that are reactive to the amines. In the rest of this document, this process will be summarized with the generic term "deamination". Thus, for example, DE-A 195 19 333 proposes to carry out the deamination by the addition of carbonic esters. A disadvantage of this process is the low selectivity of the carbonic esters in relation to the OH groups and the amino groups, for which reason a large amount of carbonic ester has to be used to react with as large a number of amino groups as possible. . On the one hand, this makes the economy of the process questionable and, on the other hand, generally only a low product quality is achieved when the polyurethanes are produced from these polyol preparations after deamination. DE-A 44 42 379 proposes to carry out glycolytic dissociation under moderate conditions using a very large excess of OH-containing compounds. For this purpose, the polyurethane-containing plastic to be dissociated is mixed with a polyol and mixed and ground in a high-speed crusher and mixer pump that generates high shear forces between the rotor and the stator. A disadvantage of this process is that only one Extremely low recycling speed can be achieved in this way, since large amounts of polyol have to be added to the plastic containing polyurethane. The proposal to dissociate plastics containing polyurethane by means of organic acids originates products highly free of amines. However, these are completely unsuitable for producing new polyurethane plastics or have very high viscosities and / or acidity indexes (see, for example, DE-A-195 12 778) which likewise makes processing difficult and difficult. it usually originates only products of little value. DE-A-44 27 250 describes the use of cyclic carbonates as a deaminant for the polyol preparations obtainable from polyurethane-containing plastics. The disadvantages of this process are the unpleasant odor of the resulting products and the low selectivity with respect to the OH groups and amino groups of the cyclic carbonate used for deamination. In the same problematic way in the use of carbonates is the increase in viscosity generally associated with deamination. DE-A-42 34 335 proposes to carry out the deamination by means of glycidyl ethers. However, this process, which is successful per se, has the disadvantage that glycidyl ethers have to be used in a very high excess since they also lack selectivity with respect to amino groups and OH groups. Due to the high known reactivity of isocyanate groups with OH groups, little attempts have been made to date to use an isocyanate to deaminate a composition containing at least one polyol. However, it would be desirable to carry out the deamination of the composition containing at least one polyol using isocyanates since the preparation of polyols resulting from the deamination is, as a rule, in any case subsequently processed to form polyurethanes and, in this form, there would be no problems of compatibility between the compounds produced by the deamination and the urethane groups in the polyurethane. An object of the present invention is to provide a process for reducing the content of primary amines of a composition containing at least one polyol (deamination), in which the deamination is carried out by means of isocyanates whose selectivity gives rise mainly to a reaction with the amino groups of the primary amines present in the composition containing at least one polyol and, in the case of which, a reaction with the OH groups of the composition containing at least one a polyol is deleted at less to a large extent. Another object of the invention is provide a process to deaminate a composition containing at least one polyol, which process does not significantly increase the viscosity of the composition containing at least one polyol and, thereby, produces a preparation of polyol having good processability. Another object of the present invention is to provide a process that allows the primary amine content of a composition containing at least one polyol to be reduced to less than 0.2% by weight, preferably less than 0.1% by weight.

In addition, an object of the invention is to provide a process for preparing polyol preparations from polyurethane-containing plastics whose process comprises a step of removing a composition containing at least one polyol, wherein the step of deamination has the advantages mentioned above in comparison with the prior art f. We have found that this objective is achieved by a process for reducing the content of primary amines of a composition containing at least one polyol, wherein a The composition containing at least one polyol is mixed with at least one isocyanate containing only secondary or tertiary or secondary and tertiary isocyanate groups, aliphatically bound, wherein the isocyanate is added in an amount of up to 5% by weight, based on the composition total, and a polyol preparation is obtained.

For the purposes of the present document, a "polyol preparation" is any preparation that contains at least one polyhydric alcohol (polyol) or a mixture of two or more different polyhydric alcohols and that has been deaminated according to the process of the present invention. . It is not important if this preparation has been formed as a result of a chemical reaction or by physical mixing of individual components or by both processes simultaneously. Also, the way in which amines have entered the polyol preparation is not important to carry out the process of the invention. For the purposes of the present invention, (a "composition containing at least one polyol" is a composition containing amines, which contains at least one polyhydric alcohol (polyol) or a mixture of two or more polyhydric alcohols. The "composition containing at least one polyol" which is used in the process of the present invention is preferably a recycled polyol containing amines which is obtained from the glycolytic dissociation of plastics containing polyurethane. For the purposes of the present invention, "polyurethane-containing plastics" are all plastics containing at least one polymeric compound containing the minus one polyurethane bond. These include, for example, polyurethanes obtained from polyols and polyisocyanates and polyurea-polyurethanes. The polyurethane-containing plastics which are used for glycolytic dissociation may also contain, for example, mineral fibers, glass fibers, synthetic textile fibers, in particular those based on polyesters or polyamides or polyesters and polyamides, without interfering with the glycolytic dissociation. . In the same way, plastics containing polyurethane can also contain polymers that are obtainable, for example, by polymerization of ethylenically unsaturated monomers. These include, for example, polyacrylonitrile, copolymers of polystyrene / acrylonitrile, acrylonitrile / butadiene / styrene and other polymers which are introduced into the polyurethane by the use of polymer polyols (grafted polyols). To carry out the glycolytic dissociation, the polyurethane-containing plastics are mixed with short-chain polyols, ie, compounds containing at least two OH groups, in the presence or absence of catalysts. Short chain polyols usually contain two or three OH groups and, in general, no more than about 20 carbon atoms, preferably from 2 to about 8 carbon atoms, which can be separated by heteroatoms, preferably by oxygen atoms.

The particularly suitable short chain polyols are ethylene glycol, oligoethylene glycols, propylene glycol, oligopropylene glycols, butanediols, neopentyl glycol, diethanolamine, methyldiethanolamine and triethanolamine. It is given specific prefereto the use of diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol or mixtures of two or more thereof. The catalysts f generally used are titanates, stannates or antimonatos or mixtures of two or more of these. The ratio of the mixing of the polyurethane-containing plastics to the short-chain compounds containing OH in general depends on the chemical structure of the polyurethane-containing plastic used and also on the OH number of the short chain compound containing OH that is uses. The weight ratio of the polyurethane-containing plastic to the short chain compound containing OH in general is from about 0.5: 1 to about 3: 1. The reaction temperature prevalent in the dissociation Glycolytic is usually set from about 180 ° C to about 250 ° C, preferably from about 200 ° C to about 235 ° C. The reaction time will generally depend on the crosslink density of the plastic containing polyurethane used, from about 1 to about 12 hours, preferably from about 2 to about 5 hours. The type of polyurethane that is present in the polyurethane-containing plastic is not of importafor use in the process of the present invention. Examples 5 of the polyurethanes that can be treated by the process of the present invention are polyester / polyurethanes and polyether / polyurethanes. After the glycolytic dissociation of the plastic containing polyurethane is completed, the composition contains amine containing at least one polyol generally first cooled to a temperature of not more than about 100 ° C. Accordingly, the invention in the same manner provides a process for preparing a preparation of polyol from a plastic containing polyurethane, in which a plastic containing polyurethane is mixed with a polyol and a mixture of two or more polyols and reacted from about 180 ° C to about 250 ° C, in the preseor abseof a catalyst, to give An amine-containing composition comprising at least one polyol and, after a reaction time of from about 0.5 to about 12 hours, is cooled from about 20 to about 80 ° C, wherein the composition containing amines and which contains at least one polyol Subsequently mixed with at least one isocyanate that f contains only secondary or tertiary isocyanate groups or aliphatically bound tertiary and tertiary isocyanates, wherein the at least one isocyanate is added in an amount of up to 5% by weight and a polyol preparation is obtained. In theory, the addition according to the present invention of at least one isocyanate is carried out from about 10 ° C to about 80 ° C, preferably from about 20 ° C to about 60 ° C, and particularly preferably from about 25 ° C to about 50 ° C. The at least one isocyanate can be added step by step, but it is also possible that the total amount of the isocyanate is added at one time. Theoretically, the stirring is carried out during the addition of at least one isocyanate. After the addition is complete, the mixture is shakes from about 10 to 180 minutes. The at least one isocinato is added in an amount of • up to about 10% by weight, based on the amine-containing composition, containing at least one polyol, preferably in an amount from about 0.1 to about 5% by weight, and particularly preferably in an amount from about 0.5 to about 3.0% by weight. The glycolytic dissociation of plastics containing polyurethane is generally carried out during25 as long as it takes to get a composition fluid containing amine containing at least one polyol. The viscosity of the amine-containing composition containing at least one polyol is, advantageously, up to about 8000 mPas (measured using a viscometer rotation at 25 ° C). If desired, the viscosity can be modified by the addition of diluents, preferably reactive diluents, in particular low molecular weight polyhydric alcohols. 'Examples of suitable reactive diluents are commercial polyols which are are selected considering the properties that are to be achieved when the polyol preparation is used in the polyurethanes. The polyol preparation obtainable after deamination according to the present invention Generally, it will have a viscosity which will generally be up to about 40 ° above the composition containing at least one polyol. It is preferred that the viscosity of the polyol preparation does not exceed about 10,000 mPas. The polyol preparation preferably has a viscosity from about 1500 mPas to about 8000 mPas. The isocyanates suitable for carrying out the process of the present invention are isocyanates containing at least two isocyanate groups which have exclusively aliphatic linkages in the secondary positions and / or tertiary.

For the purposes of the present invention, preference is given to the use of at least one isocyanate of the formula (I). where X is a linear or branched, saturated alkylene group or unsaturated having from about 4 to about 8 carbon atoms or an unsubstituted, aliphatically substituted aromatic or cycloaliphatic ring system, aromatically substituted or substituted with heteroatoms, R1, R2, RJ and R4 are, independently of each other, H or C6-C6 alkyl and R5 and R6 are, independently of one another, alkylene of d-C4. # It is particularly preferred that the radical pair R1, RJ, is different from the radical pair R ~, R4 and each pair is a pair of hydrogen atoms or a pair of alkyl groups of C? -C4. An example of an isocyanate that can be used in accordance with the present invention is 1,3-bis (2-isocyanatopropyl) benzene, also known as m-tetramethylxylylene diisocyanate (TMXDI) (CAS-No. 002778-42-9 ). 25 To carry out the glycolytic dissociation according to # with the present invention, plastics containing polyurethane, plastics are usually first crushed, but plastics containing unblended polyurethane can also be subjected to glycolytic dissociation.

The process of the present invention is not exclusive but particularly suitable for polyurethane-containing plastics that have been produced using diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) or MDI and TDI. The glycolytic dissociation is particularly suitable for the reprocessing of polyurethane-containing plastics such as those obtained, for example, in the demolition of old automobiles, for example, in the reprocessing of car body parts, boards and seats of automobiles, but also of scrap of manufacture coming from the production of rigid, flexible, integral and block foams. The polyol preparations that have been deaminated by the process of the present invention can be used later to produce polyurethanes again. The polyol preparations have a very long storage life, so that the production of polyurethane can be carried out directly after deamination or even after a storage time relatively long.

Accordingly, the invention also provides the use of a polyol preparation that has been prepared by one of the processes of the present invention to produce polyurethane. The invention is illustrated by the following examples without being limited thereby.

EXAMPLES In all the experiments the polyurethane-containing plastic used was polyurethane scrap 10 coming from the operations that produce and process polyurethane. The plastic containing polyurethane was crushed in a cutting mill to a size that allowed the material to be introduced into a reactor and subjected to glycolytic dissociation without further treatment. The glycol used for the glycolytic dissociation was placed in a flask provided with stirrer, separating funnel, thermometer and reflux condenser and was mixed with 0.1% by weight of dibultiltin dilaurate. as catalyst, calculated on the basis of the total batch. After heating the glycol to about 210 ° C, the plastic containing polyurethane was added at such a rate that the contents of the flask remained agitable and the temperature remained constant. After finish the addition, the reaction temperature of 200 ° C will kept for about 2 hours. The mixture was subsequently cooled to the reaction temperature indicated in Table 1, TMXDI was added and the mixture was stirred during the reaction time as indicated in Table 1. After the reaction was complete, the polyol preparation was cooled and analyzed. The preparation of polyol was characterized by determining the OH index (titrimetric), the viscosity at 25 ° C (rotation viscometer) and the content of amines primary (high resolution liquid chromatography, CLAP). The following tables show the raw materials, reaction conditions and results. Examples Cl, C3, C5 and C7 are comparative examples without the addition of TMXDI.

Table 1 F Abbreviations: PUR = polyurethane RIM = injection molding reaction 5 'MDI = 4, 4' - diphenylmethane diisocyanate

Claims (1)

1. CLAIMS A process for reducing the content of primary amines of a composition containing at least one polyol, wherein a composition containing at least one polyol is mixed with at least one isocyanate containing only secondary or tertiary or secondary and tertiary isocyanate groups, aliphatically joined, where the at least one isocyanate is added in an amount of up to 5% by weight, based on the total composition, and a polyol preparation is obtained. The process as mentioned in claim 1, wherein use is made of an isocyanate of the formula (I). where X is a linear or branched, saturated or unsaturated alkylene group having from 4 to 8 carbon atoms or an unsubstituted, aliphatically substituted, aromatically substituted or cycloaliphatic ring system, substituted or substituted with heteroatoms, R1, R2, R3 and R4 they are, independent of each other, H or Ci-Cß alkyl and R5 and R6 are, independent of each other, C 1 -C 4 alkylene. The process as recited in claim 2, wherein the pair of radicals R1, R3, is different from the pair of radicals R2, R4 and each pair is a pair of hydrogen atoms or a pair of C1-C4 alkyl groups. The process as mentioned in any of the preceding claims, wherein 1, 3-bis (2-isocyanatopropyl) benzene (TMXDI) is used as isocyanate. The process as mentioned in any of the preceding claims, wherein the composition containing at least one polyol contains a polyol obtained from plastics containing polyurethane. The process as mentioned in any of the preceding claims, wherein the composition containing at least one polyol has been obtained by glycolytic dissociation of the plastics containing polyurethane. The process as mentioned in any of the preceding claims, wherein the isocyanate is added in an amount from 0.1 to 5% by weight, based on the composition containing at least one polyol. A process for preparing a polyol preparation from a plastic containing polyurethane, in which a plastic containing polyurethane is mixed with a polyol and a mixture of two or more polyols and is made reacting from 180 ° C to about 250 ° C, in the presence or absence of a catalyst, to give a composition containing at least one polyol and, after a reaction time from 0.5 to 12 hours, cooled from 20 to 80 ° C, wherein the composition containing at least one polyol is subsequently mixed with at least one isocyanate containing only secondary or tertiary isocyanate or aliphatically bound tertiary and tertiary groups, wherein the at least one isocyanate is added in an amount of up to 5. % by weight and a polyol preparation is obtained. The use of the polyol preparation treated by a process as mentioned in any of claims 1 to 7 or prepared as mentioned in claim 8 to produce polyurethanes.