SE450489B - PROCEDURE FOR PREPARING A POLYURETHANE BY REVERSING AN ISOCYANATE WITH A POLYMER-MODIFIED POLYOL - Google Patents

Description

450,489 these hydrogen atoms may be reactive with the isocyanate. If the alkanolamine is a tertiary amine, it contains several alcohol groups with active hydrogen atoms, and all of these hydrogen atoms may be reactive with the isocyanate. In either case, either all or only some of the reactive hydrogen atoms can react. It is believed that the polyaddition reaction produces straight and / or branched chains by reacting isocyanate groups and hydroxyl groups with each other to form urethane bonds (-NH-CO-O-) and by reacting isocyanate groups and amine groups to form urea bonds (-NH -CO-NH- or = N-CO-NH-). The polyaddition product may be mixed with and / or chemically reacted with the polyol (eg by copolymerization). The term polymer-modified polyol according to the present invention encompasses both physical and chemical combinations as well as mixtures thereof. It is believed, however, that the process of the invention usually results in a predominantly physical combination. Such a physical combination may be in the form of a solution or a stable dispersion of the polyaddition product in the polyol depending on the starting materials used. The choice of alkanolamine and possibly also the choice of polyol can in particular determine the physical state of the polymer-modified polyol.

In the process of the invention, the alkanolamine and the isocyanate are preferably mixed in a molar ratio of from about 1.0: 0.5 to 1.0: 1.5 in the presence of a polyether polyol having a molecular weight of from 200 to 10,000 (especially 2,800 -7,000), and the reacted alkanolamine and the reacted polyisocyanate together constitute 1-35% by weight, based on the weight of the polyol.

As the alkanolamine, Han of the invention can use any suitable alkanolamine or combination of alkanolamines.

Non-limiting examples include primary, secondary and tertiary alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, monoisopropanolamine, monoisopropanol diisopropanolamine, triisopropanolamine, N-methylisopropanolamine, N-ethylisopropanolamine and N-propylisopropanolamine.

The term alkanolamine according to the invention also includes substituted alkanolamines, and it is e.g. It is possible to use primary and secondary alkanolamines which are halogen-substituted on the nitrogen atom, or secondary or tertiary alkanolamines which are halogen-substituted on the alkyl group (ie the alcohol group is replaced by a halogen atom). In a particularly preferred embodiment, triethanolamine is used as the alkanolamine.

Any suitable organic polyisocyanate can be used, including such aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates commonly used in the preparation of polyurethanes from polyisocyanates and polyols (see, for example, British Patent Specification 1 H53 258 ).

As examples of suitable; Commercially available polyisocyanates include 2,, and 2,6-tolylene diisocyanates and mixtures of these isomers (commonly called TDI), polyphenyl polymethylene polyisocyanates of the type obtained by condensing aniline with formaldehyde and subsequent phosgenation (commonly called orene MDI), and polyisocyanates containing carbodiimide groups, urethane groups, allophonate groups, isocyanate groups, urea groups or biuret groups (commonly called polyisocyanates).

You can use any suitable pplyol, e.g. such polyether polyols having a molecular weight of 200-10,000 which are commonly used in the production of polyurethanes starting from polyisocyanates and polyols (see, for example, British Patent Specification 1 H82 213).

Such known polyether polyols can be obtained by reacting alkylene oxide with compounds containing active hydrogen atoms, the molecular weight of the reaction product depending on the amount of alkylene oxide reacted.

The polyaddition products obtained according to the invention can be modified by proportional use of monofunctional isocyanates, amines or N-dialkylalkanolamines. The average molecular weight of polyaddition products can e.g. is regulated by adding monofunctional compounds of this type in proportions of up to 25 mol%, calculated on the olamine component.

Examples of suitable monofunctional isocyanates are methyl, ethyl, isopropyl, isobutyl, hexyl, lauryl and stearyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, tolyl isocyanate, H-chlorophenyl isocyanate and diisopropylphenyl.

Examples of suitable monofunctional amines are dialkylamines, e.g. dimethylamine, diethylamine, dibutylamine and cyclohexylamine, and examples of suitable N-dialkylalkanolamines are dimethylethanolamine and diethylethanolamine. It should be understood that not all alcohol groups and amine groups in the alkanolamine used in the polyaddition reaction of the invention need to react with the isocyanate in all circumstances, but the alkanolamine may in some cases react monofunctionally, thus acting as an agent which interrupts chain growth.

If desired, the polyaddition reaction according to the invention can be catalyzed by the introduction of such substances which are commonly used as catalysts in the production of polyurethanes starting from polyisocyanates and polyols. Thus, organometallic compounds such as stannous octoate and dibutyltin dilaurate and / or amines such as triethylenediamine can be used. The amount of catalyst used may be small in relation to the amount commonly used in polyurethane production, e.g. of the order of 0.02% rather than 0.2%, based on the total weight of the polyol. Larger amounts can, however, be used if desired.

When using a primary or secondary alkanolamine, catalysis may not be necessary, but catalysis may be advantageous when using a tertiary alkanolamine, such as triethanolamine.

The molecular weight of the polyaddition product can be controlled by varying the weight ratio between the alkanolamine on the one hand and the polyisocyanate on the other hand (as well as monofunctional components if used). Thus, although a molar ratio of alkanolamine to polyisocyanate from 1.0: 0.5 to 1.0: 1.5 is particularly preferred, and substantially equivalent molar amounts are particularly preferred, it is also possible to use a higher proportion of isocyanate if may allow the higher viscosity at higher isocyanate levels or the rapid gelation which tends to take place at higher isocyanate levels. An upper ratio of, for example, 1.0: 1.55 or 1.0: 1.6 may thus be possible. By reducing the amount of isocyanate, the molecular weight of the polyaddition product also decreases together with the viscosity. Generally, a molar ratio of alkanolamine to organic polyisocyanate of from 1.0: 0.8 to 1.0: 1.1 is preferred. Although the concentration of the reacted alkanolamine and the reacted isocyanate (ie the concentration of the polyaddition products) in the polyether polyol can vary widely, this concentration should usually be between 1 and 35% by weight, preferably from 3 to 30% by weight. . If a specific concentration of 450 489 of the polyaddition product is required (for use in the production of polyurethane foams with certain optimum properties, for example, a concentration of about 10% by weight may be required), this concentration can be obtained directly by appropriate selection of the reactants so that the required concentration is obtained, or a polyaddition product formed can be subsequently diluted with additional polyether polyol.

The reactants can usually be mixed at temperatures from 0 ° C, or temperatures above the melting points of the reactants, depending on the lowest temperature, up to 150 ° C. The reactants are preferably mixed at a temperature between room temperature or a temperature just above the melting point of the reactants, depending on which temperature is lowest, and 7000. It may also be possible to mix the reactants at temperatures below their melting points.

The reaction is exothermic, and an increase in temperature can be observed depending on the proportion of polyaddition product formed, calculated on the weight of the polyether polyol.

The more efficient the mixture of the reactants, the finer the particle size of the dispersion (if a dispersion is prepared) and the lower the viscosity. A simple batch process can be used, in which case either of the alkanol substances a fl iß fi ly 'isocyanate is first dissolved or dispersed in the polyether polyol, after which the other reactant is added in the zone where maximum mixing takes place, but a continuous addition and mixing can also be used. of the reactants. In the latter case, all the reactants are pumped at controlled rates, and they can be mixed simultaneously, or one reactant can first be mixed with the polyether polyol, after which the other reactant is added and mixed.

The dispersion in polyether-polyol can be used either immediately after completion of the reaction or after an extended period of time. From a continuous mixing unit, where the reaction takes place, e.g. the polyaddition product in a polyether polyol is passed directly to the mixing chamber of a polyurethane production machine of well known type. If the reaction between the alkanolamine and the polyisocyanate is relatively slow, an intermediate holding tank between the continuous mixing unit and the mixing chamber of the polyurethane production machine can be used to allow a complete 450 489 reaction to take place.

To the polymer-modified polyol of the present invention, various additives can be added either during or after the reaction, such as activators, stabilizers, crosslinking agents, water, blowing agents, flame retardants and pigment pastes. The polyaddition product formed was used in the production of polyurethane foam. If the product is in the form of a stable polyol dispersion, i.e. a dispersion which does not sediment or at least remains in dispersion form when mixed with the other foaming ingredients, the dispersed polyaddition product is particularly effective as a polymeric filler in the production of highly elastic, easy-to-process foam.

The dispersed product increases the strength while breaking down the cell walls.

If the product is in the form of a polyol solution, it may be suitable for use in the production of polymeric materials which have properties other than the polymeric materials obtained with polyol dispersions.

If the polyaddition product is in the form of a stable dispersion, it is usually suitable for use in the production of soft, semi-hard and hard polyurethane foams with improved properties, such as increased hardness, and non-shrinking, highly elastic foams of well known type can be produced. because the polyol-dispersed polyaddition product has a cell-opening effect. In addition, the dispersions are also suitable for the preparation of L.ex. elastomers, coatings and coatings based on polyurethanes.

If the dispersion is to be used in the manufacture of a polyurethane, the polyol in the dispersion is usually used in the polyurethane-forming process, and the properties of the polyol, in particular its hydroxyl number and functionality, are thus selected in a known manner depending on the type of polyurethane produced. For the production of elastomers, e.g. the polyether polyol is preferably predominantly linear, i.e. difunctional, and it has hydroxyl numbers from 30 to 170.

For the production of foams, the polyether polyols are selected in a known manner to obtain either flexible, semi-flexible or rigid foams. For the production of flexible foams, the polyether polyols preferably have hydroxyl numbers from 20 to 80, and they contain 2-Ä hydroxyl groups per molecule. One can e.g. use ICI Polyol PBA 1253. If desired, mixtures of polyether-polyols can be used. 450 489 7 Organic polyisocyanates useful for the production of polyurethanes are known in the art, and the same organic polyisocyanates can be used as the polyisocyanates given above for the reaction with the alkanolamine.

The reaction mixture for producing polyurethane foam may also contain other conventional constituents of such reaction mixtures, depending on the type of polyurethane produced.

The reaction mixture may thus contain catalysts, e.g. tertiary amines and organic tin compounds, crosslinking agents or chain extenders, e.g. diethanolamine, triethanolamine, ethylene glycol, glycerol, dipropylene glycol and phenylenediamine, flame retardants, e.g. halogenated alkyl phosphates, and fillers, e.g. barium sulphate. To produce foam, blowing agents are mixed into the reaction mixture. Examples of suitable blowing agents are water which reacts with the polyisocyanate to form carbon dioxide and inert volatile liquids which evaporate under the influence of the exothermic reaction or as a result of a pressure drop if a mechanical "frothing" process is used. . Examples of such liquids are halogenated hydrocarbons having boiling points not exceeding 100 ° C at atmospheric pressure and preferably not exceeding 5000, especially chlorofluorocarbons such as trichlorofluoromethane and dichlorodifluoromethane, but also chlorinated hydrocarbons such as dichloromethane. The amount of blowing agent is selected in a known manner so as to obtain foam of the desired density.

It is usually convenient to use 0.005-0.3 moles of gas per 100 g of reaction mixture. The density of the foam formed can possibly be modified by overfilling, i.e. foaming the reaction mixture in a closed form with a volume less than the volume that would be taken up by the resulting foam if the reaction mixture was allowed to expand freely.

The composition of the polyurethane-forming reaction mixture should generally be such that the ratio of isocyanate groups to active hydrogen atoms is substantially in the range of 0.911 to 1.2: 1, but higher ratios may be used if desired.

When producing a polyurethane foam, it is usually necessary to stabilize or control the cells formed by the addition of a foam stabilizer or cell regulator, such as a polysiloxane-polyalkylene oxide block polymer, which may contain direct carbon-silicon bonds or carbon. oxygen-silicon bonds between the organic units and the polysiloxane units. When producing highly elastic polyurethane foams, it is convenient to use dimethyl 450489 silicone oils or low molecular weight modifications thereof, eg silicon B8616 from Theodore Goldschmidt AG.

Depending on the type of polyurethane produced, different production methods can be used, such as the one-step method, the prepolymer method or the quasi-prepolymer method.

The components of the polyurethane-forming reaction mixture may be mixed with each other in any suitable manner, e.g. by using any of the mixing equipment commonly used for this purpose. Some of the individual components may be pre-mixed with each other to reduce the number of component streams that must be brought together in the final mixing step. It is often convenient to have a two-stream system, one stream comprising a polyisocyanate or a prepolymer and the other stream comprising all the other components of the reaction mixture.

The invention is illustrated by the following non-limiting examples, in which indications of parts and percentages refer to parts by weight and percentages by weight. Unless otherwise indicated, room temperature was used for the reactants.

The polyethers given in the examples are as follows.

Polyether A: A glycerol-based polyether of propylene oxide provided with 15% by weight of ethylene oxide to a hydroxyl number of 35 and a content of primary hydroxyl groups of about 75%.

Eolleter B: A trimethylolpropane-based polyether of propylene oxide provided with ethylene oxide to a hydroxyl number of BH and a content of primary OH groups of about 80%.

Polyether C: A glycerol-based polyether of propylene oxide and ethylene oxide to a hydroxyl number of M7 and a content of primary OH groups of less than 5%.

Polyether D: A linear polypropylene glycol having a hydroxyl number of 56 and containing secondary hydroxyl groups.

Example 1. 900 g of polyether A having a temperature of 2000 were mixed with H8, Y g of triethanolamine having a temperature of 20 ° C, the mixing being carried out with high speed stirring. Over a period of 5 s, 51.2 g of a mixture of 80% 2, N-itolylene diisocyanate and 20% 2,6-tolylene diisocyanate were then added. Then, 0.3 g of dibutyltin dilaurate was added as a catalyst, and a rapid reaction took place. The temperature of the reaction mixture rose from ZOOC to 3700 in a time of 5 minutes from the completion of the addition of the catalyst. After cooling, the resulting stable dispersion with a solids content of 10% had a viscosity of 1600 CP at 25 ° C. 300 g of the product prepared above were placed in a beaker, then 7.8 g of water, 3 g of diethanolamine, 0.21 g of bis- (2-dimethylaminoethyl) ether and 1.5 g of Goldschmídt Silicone B8616 were added.

The resulting mixture was stirred, and the temperature was adjusted to 2200. Then 0.75 g of dibutyltin dilaurate was added. After stirring for 10 s, 117 g of a mixture of 80% 2,1-tolylene diisocyanate and 20% 2,6-tolylene diisocyanate were added. After another 5 s, the mixture was poured into a box, where it was allowed to expand.

After an additional 105 s from completion of mixing, a non-shrinking, highly elastic foam had formed. This foam had the following properties.

Density BU kg / m3 Pressure hole fastening at Hoz bending 28 p / cmz Bounce elasticity 63% Example 2. In a beaker 920 g of polyether A with a temperature of 20 ° C were introduced, and 32.1 g of diethanolamine with a temperature of 5000 were added at room temperature with mechanical stirring. . 07.9 g of a mixture of 80% 2, H-tolylene diisocyanate and 20% 2,6-tolylene diisocyanate were introduced into the vortex of the stirred mixture over a period of 30 s. A white, stable dispersion formed, and 30 s after the completion of the addition of isocyanate, the temperature had risen from 2000 to 5700. The polyaddition product contained the isocyanate and the alkanolamine in a molar ratio of 0.9: 1.0, and the final product contained 8.0 % polyaddition product in polyether-polyol and had an acceptable viscosity at room temperature. 300 g of the product prepared above were placed in a beaker, and then 7.8 g of water, 3 g of diethanolamine, 0.21 g of bis- (2-dimethylaminoethyl) ether and 1.5 g of Goldschmidt Silicone B8616 were added.

The resulting mixture was stirred, and the temperature was adjusted to 2200. Then 0.75 g of dibutyltin diurea was added. After stirring for 10 seconds, 117 g of a mixture of 80% 2,1-tolylene diisocyanate and 20% 2,6-tolylene diisocyanate were added. After another 5 s, the mixture was poured into a box, where it was allowed to expand.

After an additional 105 s from completion of mixing, a non-shrinking, highly elastic foam had formed. This foam had approximately the same properties as the foam prepared in Example 1. §5empg__ä. A foam was prepared in the same manner as described in Example 2 except that 300 g of polyether polyol additive product was replaced with 500 g of polyether polyol (polyether A). In addition, only 100 g of isocyanate were used. The mixture was allowed to expand to a foam in the same manner as in Example 2. The resulting foam shrank, and it was not possible to measure the properties of the foam.

Example A A polyaddition product was prepared in polyether-polyol using polyether A in the same manner as in Example 2, and foaming was also carried out in the same manner as in Example 2, except that all dibutyltin dilaurate was replaced by 0.6 g. tenn (II) - octoate. This gave a non-shrinking, highly elastic foam with approximately the same properties as given in Example 1.

Example 5. A polyaddition product and a polyurethane foam were prepared in the same manner as described in Example 2 except that polyether A was replaced with polyether B. The stable dispersion in polyether-polyol had a solids content of 8% and an acceptable viscosity at room temperature. The resulting foam did not shrink, and its properties were similar to those of Example 1 foam.

Example 6. A polyaddition product was prepared in polyether A in the same manner as described in Example 2 except that the molar ratio of isocyanate to alkanolamine was 1.1: 1.0. The total solids content was also 8% in this case. The resulting product had a high but useful viscosity, namely higher than 2500 cP at 2500. In preparing polyurethane foam in the same manner as in Example 2, a non-shrinking, highly elastic foam was obtained.

Example 7. A polyaddition product was prepared in polyether A in the same manner as described in Example 2 except that the molar ratio of isocyanate to alkanolamine was 0.5: 1.0: 1.0. The total solids content was 8%. In the preparation of polyurethane foam in the same manner as in Example 2, a shrinking foam was obtained. The properties of this foam could not be measured.

Example 8. A polyaddition product was prepared by mixing 920 g of polyether A having a temperature of 2000 with 2H, 5 g of diethanolamine having a temperature of 3000, after which 55.5 g of crude MDI were added with vigorous stirring. A polyaddition product was obtained in polyether-polyol with a solids content of 8% and with a useful but high viscosity, namely higher than 3000 cP at 2500.

A polyurethane foam was prepared in the same manner as in Example 2 to give a non-shrinkable, highly elastic foam. Example 48 A stable dispersion was prepared by mixing 800 g of polyether C at the temperature of 2000 with 80.2 g of diethanolamine of the temperature of 3000 while stirring at high speed.

With continued stirring, 119.75 g of a mixture of 80% 2,1-tolylene dicocyanate and 20% 2,6-tolylene diisocyanate were added. This addition was carried out over a period of 1 minute. A temperature rise of 2900 was obtained, and after cooling the product had an acceptable viscosity at room temperature and a solids content of 20%, Example 10. A stable dispersion was prepared in the same manner as in Example 9 except that polyether D was used instead of polyether C. the resulting polyaddition product in polyether D had a solids content of 20% and an acceptable viscosity at room temperature.

The stable dispersions prepared in Examples 1, 2 and 5-10 are of a nonionic nature. This means that the dispersions contain covalent polymeric substances free of ionic groups. Substantially no water or other ionic medium is used in the preparation of the dispersions or is present in the dispersions prepared. The presence of traces of water, which may be present in commercially available polyols and other starting materials, can be accepted even if the presence of water is usually inappropriate and should be kept as low as possible. The water content should preferably not be greater than 1% by weight, and most preferably the water content should be much lower, e.g. below 0.1% by weight, although it should be understood that under certain conditions it may be possible to carry out the process according to the invention at water contents above 1% by weight.

The polyols used in carrying out the process according to the invention may be of the triol type containing mainly primary hydroxyl groups in the men as such polyols are particularly useful as starting materials for the production of polyurethane foams. Since the preparation of polymer-modified polyols in accordance with the present invention, in particular such preparation as described in the above embodiments, involves reaction of the isocyanate exclusively or predominantly with α-ol moles, while the polyol acts exclusively or predominantly as unreacted carrier, it will be appreciated that it is possible to use any suitable polyol, specially selected in accordance with the requirements of a subsequent polyurethane-forming reaction, in which the polymer-modified polyol is to be used.

Claims (9)

450 489 12 One can thus e.g. use polyols, which are triols and / or diols and which contain primary and / or secondary hydroxyl groups, or polyols with any suitable structures. P a t e n t k r a v A process for the preparation of a polyurethane, wherein an isocyanate is reacted with a polymer-modified polyol, which in turn is prepared by polymerizing an alkanolamine with an organic polyisocyanate in the presence of a polyol, characterized in that the alkanolamine reacts at least predominantly polyfunctional with the isocyanate in a molar ratio of from 1.0: 0.5 to 1.0: 1.6, and that the polyol acts at least predominantly as an unreacted carrier in the formation of the polymer-modified polyol. Process according to Claim 1, characterized in that the alkanolamine and the isocyanate are reacted in a molar ratio of from 1.0: 0.8 to 1.0: 1.1 in the presence of a polyether polyol having a molecular weight of 200-10,000. and that the reacted alkanolamine and the reacted polyisocyanate together constitute 1-35% by weight, based on the weight of the polyol. 3. A process according to claim 2, characterized in that the total weight of the alkanolamine and the polyisocyanate is greater than 10%, based on the weight of the polyol, and that additional polyol is added after the polymerization of the alkanolamine with the isocyanate to dilute the polymer-modified polyol. 4. A process according to any one of claims 1-3, characterized in that the alkanolamine is triethanolamine. 5. A process according to any one of claims 1-4, characterized in that a catalyst is mixed with the alkanolamine and the polyisocyanate to catalyze the polymerization reaction between these substances, the catalyst being preferably selected from organometallic compounds and amines; and that additives are mixed with the alkanolamine and the polyisocyanate to modify the polymerization reaction between these substances, the reaction modifying additives being preferably selected from monofunctional isocyanates, monofunctional amines and dialkylalkanolamines. Process according to one of Claims 1 to 5, characterized in that the polymer-modified polyol is prepared in the form of a stable dispersion. 450 489 13 Process according to one of Claims 1 to 6, characterized in that the polyol used mainly contains primary new hydroxyl groups. Process according to any one of claims 1-7, characterized in that the isocyanate reacted with the polymer-modified polyol is the same isocyanate used in the preparation of the polymer-modified polyol. Process according to one of Claims 1 to 8, characterized in that the polyurethane-forming reaction between the isocyanate and the polymer-modified polyol is carried out in the presence of additives selected from blowing agents, catalysts, stabilizers, crosslinking agents, flame retardants, pigments. and fillers.