DK153796B - PROCEDURE FOR MANUFACTURING A POLYURETHING GLOVE. - Google Patents

Description

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The present invention relates to a process for producing a polyurethane foam.

Polyurethane foam is prepared by reacting a polyol with a polyisocyanate in the presence of a propellant and usually also one or more additives.

To modify the physical properties of the resulting foam in the desired manner, it is known to use pre-formed polymer-modified polyols (i.e., polyols containing additional polymeric material) in the reaction to form polyurethane, cf. eg. Thus, it is known to use polyol dispersions of polyaddition products of polyisocyanate and primary amines, secondary amines, hydrazines and hydrazides, and to use polyols wherein 15 are disjointed and with which is copolymerized polymeric material from in situ polymerization of ethylenically unsaturated monomers.

U.S. Patent No. 3,360,495 describes the formation of a dispersion by reacting an olamine with isocyanate.

However, it appears that the dispersion is used as a final product coating material. There is no indication of the possibility of using the dispersion as a starting material in the manufacture of a polyurethane.

The present invention relates to a process 25 for producing a polyurethane foam wherein a polyisocyanate is reacted in the presence of additives selected from propellants, catalysts, stabilizers, crosslinking agents, fire protection agents, pigments and fillers with a polymer modified polyol which is a solid. car dispersion prepared by polymerization of an alkanolamine with an organic polyisocyanate in the presence of a polyether polyol, the process being characterized in that the alkanolamine is a di- or trialkanolamine and is used in the polymerization in a molar ratio 35 to the polyisocyanate of 1.0: 0.5 to 1.0: 1.6, and that the alkanolamine has at least predominantly reacted polyfunctionally

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with the isocyanate to form a polyaddition product dispersed in the polyether polyol which has at least predominantly acted as unreacted carrier in the formation of the polymer modified polyol.

The present invention is based on the recognition that polyurethanes with good physical properties can be prepared using a starting material consisting of an olamine / isocyanate polyaddition product in a polyol support. The polyaddition product provides a complex "filler" effect on the resulting polyurethane material.

The polyaddition product / polyol starting material is referred to as a polymer-modified polyol, and other polymer-modified polyols are already known as mentioned. However, known polymer-modified polyols have a different structure and do not have the same effect on the physical properties of the resulting polyurethane as the polymer-modified polyol used in the present invention. In this regard, it is to be understood that the production of polyurethane, especially polyurethane foam, involves selection of the nature and proportions of various "routine" ingredients to achieve a desired balancing of properties, e.g. foam-resilience, strength, fire properties, etc.

This selection requires hands-on experience and may necessitate compromises, as it may be necessary to accept a slight deterioration of one physical property to obtain an appropriate level of another property.

The degree of permissible variation of "routine" constituents depends, among other things, on the nature of the polymer-modified polyol used as the starting material.

The present invention provides new possibilities for polyurethane formulation and thus other possibilities for physical properties as a result of the use of the new polymer-modified polyols. For example, it has been found possible to obtain high resilience polyurethane foams with formulations (as set forth in the Examples of the present specification) which do not burn easily.

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The polymer-modified polyol used in the invention is obtained by reacting an olamine with an isocyanate. Therefore, the polymer-modified polyol consists essentially of only 5 1. unreacted polyol support, and the 2. polyaddition product of isocyanate and olamine.

There is no significant reaction between the isocyanate and the polyol support, and the polyaddition product is prepared by reaction between the isocyanate and the oilmine without substantial involvement of other compounds.

That reaction is essentially exclusively between the olamine and the isocyanate is due to the use of a reaction mixture containing essentially only polyol, isocyanate and olamine, with the isocyanate / olamine ratio being selected to ensure that the only reaction what can actually take place is the reaction between isocyanate and olamine. In simplified terms, only isocyanate is sufficient to react with the more reactive oilmine, and not with the less reactive polyol.

As mentioned, polymer-modified polyols are known as polyurethane starting materials, but the particular starting material used in the present invention has not been described so far.

From GB Patent No. 1,571,183, which corresponds to 25 DE Publication No. 2,550,796, it is apparent that the state of the art is that in the preparation of a polymer-modified polyol for use in polyurethane production, amines and hydrazines and hydrazides are the essential compounds used for reaction with isocyanate and olamines 30 have heretofore been known only for use as modifying constituents or for providing functional groups for reaction with other essential constituents (see page 2, lines 38-45, in GB patent no. 1 571 183). The use of an olamine in itself is not described as the sole 35

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4 reactant or as the main reactant. In the present invention, the polymer-modified polyol used in the polyurethane process is essentially exclusively an olamine / isocyanate polyaddition product in a polyol support, while the olamine in the known polymer-modified polyols made with olamine is only partially contributed (in practice with only a small part) to the molecular structure.

GB Patent No. 1,453,258 is a further example of prior art of the aforementioned kind. Herein is described 10 reaction of an amino compound with an isocyanate, and a large number of amino compounds are listed (on page 3).

However, the use of alkanolamine as the main reactant is not described. Olamines are referred to only as turnover modified agents (page 4, lines 78-98). This is the 15 common use of olamines which is included as a subsidiary feature in the description of the present application. In this context, it is to be understood that it is well known to use small amounts of olamine to modify the course of a main reaction (e.g., a polyol / isocyanate main reaction). In this known use of olamines, the equivalent amount of isocyanate far exceeds the amount of olamine, whereby the isocyanate reacts with both the olamine and the main constituent to form a product modified by inclusion of the olamine. In the present invention, the three components (polyol, isocyanate, olamine) are mixed so that there is essentially only enough isocyanate to react with the olamine and the polyol remains as unreacted carrier. In the subsequent polyurethane formation reaction of the invention, 30 more isocyanate is added to react with the polyol and small amounts of olamines can be added as modifiers. It is even possible to make some modification of the major isocyanate / olamine polyaddition reaction in the presence of a small amount of the same or another olamine, e.g. acts as a chain terminating agent.

The reactions of the invention can be illustrated schematically as follows:

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Step 1 - Preparation of inert filler dispersed in polyol: R1 (NCO) x + R2 (OH) (NH2) + R3 (OH) - polyisocyanate olamine polyol -R1-NHCO-O-R2-NHCO-NH- + R3 (OH) γ urethane-urea-unreacted bond binding polyol polyurethane / polyurea-10 polyaddition product

Step 2 - Preparation of final product polyurethane: 1 Ί R (Ν00) χ + polyadditi- + R (OH) + possibly Foam -15 Liquid Producer -R 2 -NHCOO-R3-NHCOO- + inert filler of polyurethane / polyurea polyaddition product 20

In the process of the invention, the olamine acts as a polyfunctional reactant and a polyaddition product is formed with the polyisocyanate. When the olamine is a secondary amine, it has alcohol and amino groups with active hydrogen atoms, all of which can be reactive to the isocyanate. When the olamine is a tertiary amine, it has several alcohol groups with active hydrogen atoms, all of which can be responsive to the isocyanate. In each case, it is possible that all or just some of the active hydrogen atoms are actually reacting. It is believed that the polyaddition reaction gives straight and / or branched chains by combining isocyanate and hydroxyl groups to form urethane bonds (-NH-COO-) and by combining isocyanate and amine groups to form urea bonds (-NH- C0-NH- or = N-C0-NH-) according to the circumstances. Said polyaddition product can 6

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o be mixed and / or be chemically combined (as by copolymerization) with the polyol, and it will be understood that the term "polymer modified polyol" thus includes both physical and chemical combinations and also mixtures thereof, although it is believed that the process In accordance with the invention, for the most part, it provides a predominantly physical combination. Such physical combinations may take the form of a solution or stable dispersion of the poly-addition product in the polyol depending on the starting materials used. In particular, the choice of olamine and possibly also polyol may determine the physical state of the polymer modified polyol.

In particular, the olamine and isocyanate are mixed in a molar ratio of approx. 1.0 / 0.5 to 1.0 / 1.5 in the presence of a polyether ether polyol having a molecular weight in the range of 200-10,000 (especially 2800-7000), and the reacted olamine and polyisocyanate together constitute 1-35 weight -%, based on the weight of the polyol.

Any suitable di- or trialkanolamine or combination thereof can be used as the olamine of the invention.

It is particularly preferred to use triethanolamine as alkanolamine.

Any suitable organic polyisocyanate, including aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, as known for use in the polyisocyanate / polyol polyurethane formation reaction can be used (see, for example, British Patent No. 1,453,258 ).

Suitable commercially available polyisocyanates include 2,3- and 2,6-tolylene diisocyanates, mixtures of these isomers (commonly called TDI), polyphenyl polymethylene polyisocyanates of the type obtained by condensing aniline with formaldehyde followed by a phosgenation (generally called crude MDI). ), and polyisocyanates containing carbodiimide groups, urethane groups, allophanate groups, isocyanate groups, urea groups or biuret groups (commonly called polyisocyanates).

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Any suitable polyether polyol having a molecular weight in the range of 200-10,000 as known for use in the polyisocyanate / polyol polyurethane formation reaction can be used and as described in e.g. British patent no.

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

The polyaddition products used in the process of the present invention can be modified by suitable use of monofunctional isocyanates, amines or N-dialkylalkanolamines. For example, the average molecular weight of the polyaddition products can be regulated by incorporating monofunctional compounds of this type in proportions of up to 25 mole%, based on the olamine component.

Suitable monofunctional isocyanates include methyl, ethyl, isopropyl, isobutyl, hexyl, lauryl and stearyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, tolyl isocyanate, 4-chlorophenyl isocyanate and diisopropyl phenyl isocyanate.

Suitable monofunctional amines include dialkyl amines such as dimethylamine, diethylamine, dibutylamine, cyclohexylamine, and suitable N-dialkylalkanolamines include dimethylethanolamine and diethylethanolamine.

It will be appreciated that not all the alcohol / amine groups in the olamine used in the polyaddition reaction have to react with the isocyanate in any case, and thus the olamine can react to a certain extent monofunctionally, thereby acting as a chain breaker itself.

If desired, the polyaddition reaction can be catalyzed by the addition of substances such as those conventionally used as catalysts in the polyisocyanate / polyol-polyurea formation reaction. Thus, organometallic compounds such as stannous octoate and dibutyltin dilaurate and / or amines such as triethylenediamine may be used. The amount of catalyst used may be small compared to that of

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usually used in the polyurethane reaction, e.g. of the order of 0.02% rather than 0.2%, based on the total weight of polyol, although larger quantities can also be used if desired.

The reaction using a dialkanolamine need not require catalysis, but this may be advantageous for a trialkanolamine such as triethanolamine.

The molecular weight of the polyaddition product can be regulated by varying the quantitative ratio of the ol-10 II amine on the one hand to the polyisocyanate on the other (and using monofunctional components if used). Thus, although a molar ratio of olamine to polyisocyanate of 1.0 / 0.5 to 1.0 / 1.5 is preferred, and substantially equivalent molar amounts are particularly preferred, it is e.g. it is possible to use a higher proportion of the isocyanate if the higher viscosity or even rapid gelatinization that tends to occur at higher isocyanate content can be appropriately taken into account. An upper ratio of e.g. Thus, 1.0 / 1.55 or 1.0 / -20 1.6 may be possible. When the amount of isocyanate is reduced, the molecular weight of the polyaddition product also coincides with the viscosity. Generally, a molar ratio of olamine to organic polyisocyanate of 1.0 / 0.8 to 1.0 / 1.1 is preferred.

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Although the concentration of the reacted olamine and isocyanate (and thus of the polyaddition products) in the polyether polyol can vary widely, it should generally be between 1 and 35% by weight, preferably from 3 to 30% by weight. When a certain concentration of polyaddition product is required (e.g., for use in the production of polyurethane foams with certain optimum properties, a concentration of about 10% by weight may be required), this can be obtained directly by appropriate selection of the reactants for obtaining the required concentration or, alternatively, by subsequent dilution of a formed polystyrene.

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9 addition product with additional polyether polyol as the case may be.

In general, the reactants can be mixed at temperatures of 0 ° C or above the melting points of the reactants, whichever is the lowest, and up to 150 ° C. The reactants are preferably mixed at room temperature or just above their melting points, whichever is the lowest, and up to 70 ° C. It may also be possible to mix the reactants below their melting points.

The reaction is exothermic and a temperature increase is observed according to the proportion of polyaddition product produced, based on the weight of the polyether polyol.

The more thoroughly the reactants are mixed, the finer the particle size of the dispersion (when a dispersion is prepared) and the lower the viscosity.

Although a simple batch process can be used whereby one of the olamine and polyisocyanate reactants is first dissolved or dispersed in the polyether polyol, then the other is added in the range of maximum stirring, line mixing of the materials can also be used. In the latter case, all the reactants are pumped at controlled rates and can be mixed at the same time, 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 a longer period of time. For example, the polyaddition product in a polyether polyol can be dosed directly from a line mixing unit where the reaction takes place to the mixing head of a well-known polyurethane manufacturing machine. When the reaction between the olamine and the polyisocyanate is relatively slow, an intermediate residence vessel may be used between such a line mixing unit and the polyurethane blending head, so as to provide an additional period of time for complete reaction.

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Additives such as activators, stabilizers, cross-linkers, water, propellants, fire protection agents and pigment pastes can be added to the polymer-modified polyol of this invention either during or after the reaction.

The polyadditon product is used in the production of polyurethane foam. When the product is in the form of a stable polyol dispersion, ie. a dispersion which does not precipitate or at least remain dispersed during mixing with the other foaming constituents, the dispersed polyaddition product is particularly effective as a polymeric filler in the production of highly resilient, easily processable foam, with such a dispersed product increasing in strength, that it breaks cell-15 walls.

The polyaddition product is in the form of a stable dispersion and is generally suitable for the production of soft, semi-hard and hard polyurethane foams having improved properties, such as increased hardness, and high-resilience non-shrinkable foams, such as is well known in the industry as the polyol dispersed polyaddition product has a cell opening effect. In addition, the dispersions are also suitable for preparing e.g. elastomers, coatings and coatings 25 based on polyurethanes.

When the dispersion is used to prepare a polyurethane, the polyurethane formation process will usually utilize the polyol in the dispersion and thus the properties of this polyol, especially its hydroxyl number and functionality, will be selected in known manner depending on the polyurethane type produced. In the manufacture of elastomers, the polyether polyol will e.g. preferably be predominantly linear, i.e. bifunctional, and will have hydroxyl numbers in the range of 30-170. In the manufacture of foams, the polyether-polyols are selected in a known manner so as to obtain foams which are flexible, semi-flexible or rigid. For manufacture o 11

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Thus, preferably, the polyether polyols have hydroxyl numbers in the range of 20-80 and 2-4 hydroxyl groups per unit length. molecule and, for example, may be mentioned "ICI Polyol PBA 1233". If desired, mixtures 5 of polyether polyols can be used.

Organic polyisocyanates which can be used in the preparation of the polyurethanes are described in the prior art and may be the same as the organic polyisocyanates described above for reaction with the olamine.

The reaction mixture for the production of polyurethane foam may also contain other conventional ingredients in such reaction mixture according to the type of polyurethane produced. Thus, the reaction mixture may contain catalyst, e.g. tertiary amines and organic tin compounds, cross-linking or chain-extending agents e.g. diethanolamine, triethanolamine, ethylene glycol, glycerol, dipropylene glycol and phenylenediamine, fire protection agents, e.g. halogenated alkyl phosphates, and fillers, e.g. barium sulphate.

20 In the manufacture of foams, propellants are added to the reaction mixture. Examples of suitable propellants include water which reacts with the polyisocyanate to form carbon dioxide, and inert volatile liquids which evaporate under the influence of the exothermic reaction or due to the pressure relief if a mechanical foaming process is used. Examples of such liquids are halogenated hydrocarbons having boiling points not above 100 ° C at atmospheric pressure and preferably not above 50 ° C, especially chlorofluorinated hydrocarbons such as trichlorofluoromethane and dichlorodifluoromethane, and also chlorinated hydrocarbons such as dichloromethane. The amount of the propellant is selected in known manner so as to obtain foams having the desired density. Generally, from 0.005 to 0.3 moles of gas per

100 g of reaction mixture appropriate. If desired, the density 35 of the foam made can be modified by "overfilling", i.e. by foaming the reaction mixture in a sealed 12

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in a form which has a smaller volume than the resulting foam would absorb if the reaction mixture was allowed to rise freely.

In general, the polyurethane-forming reaction mixture should have a composition such that the ratio of isocyanate groups to active hydrogen atoms is substantially within the range of 0.9 / 1 to 1.2 / 1, but higher ratios may be used if desired.

When preparing a polyurethane foam, it is usually necessary to stabilize or regulate the cells formed by the addition of a foam stabilizer or cell regulator such as polysiloxane-polyalkylene oxide block copolymers which may contain direct carbon-silicon or carbon. -oxygen-silicon bonds between the organic units and the polysiloxane units. When high resilience polyurethane foams are prepared, dimethylsilocone oils or modifications thereof of low molecular weight are satisfactory, e.g. "Theodore Goldschmidt AG silicone B8616".

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Direct methods or prepolymer or quasi-prepolymer methods may be used as appropriate for the particular type of polyurethane produced.

The components of the polyurethane-forming reaction mixture can be mixed together in any convenient manner, e.g. using any of the mixing devices described in the prior art for ease. If desired, some of the individual components may be pre-mixed to reduce the number of component streams to be brought together in the final mixing step.

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It is often convenient to have a two-stream system in which one stream contains a polyisocyanate or prepolymer and the other stream contains all the other components of the reaction mixture.

The invention is illustrated by the following Examples 1-8 in which all parts are parts by weight and all percentages are weight percent. Unless otherwise indicated, ambient temperatures are used for the reactants. Examples 9 and 10 35

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Figure 13 illustrates the preparation of dispersions used in the process of the invention.

The abbreviations used in the examples for the polyethers have the following meanings:

Polyether A:

A glycerol-started polyether of propylene oxide ftiBd & 15% ethylene oxide having a hydroxyl number of 35 and a content of primary hydroxyl groups of approx. 75%.

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Polyether B:

A trimethylolpropane-started polyether of propylene oxide and ethylene oxide having a hydroxyl number of 34 and a content of primary hydroxyl groups of approx. 80%.

Polyether C:

A glycerol-started polyether of propylene oxide and ethylene oxide having a hydroxyl number of 47 and a content of primary hydroxyl groups of less than 5%.

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Polyether D:

A linear polypropylene glycol having a hydroxyl number of 56 containing secondary hydroxyl groups.

Example 1 25 o 900 g of polyether A at a temperature of 20 C are mixed with 48.7 g of triethanolamine at a temperature of 20 ° C.

During high speed mixing, 51.2 g of a mixture of 80% 2,4- and 20% 2,6- tolylene diisocyanate are added in 5 seconds. Then 0.3 g of dibutyltin dilaurate is added and a rapid reaction occurs, with the temperature of the mixture rising from 20 to 37 ° C over three minutes after the addition of the catalyst.

After cooling, the resulting stable dispersion with 10% solids has a viscosity of 1600 cP at 25 ° C.

Place 300 g of this product in a beaker and then add 7.8 g of water, 3 g of diethanolamine, 0.21 g of bis (2-dimethylaminoethyl) ether and 1.5 g of Gold

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schmidt Silicone B 8616 "(surfactant, presumably a polysiloxane-polyalkylene oxide copolymer) and stirred and the temperature adjusted to 22 ° C. Then 0.75 g of dibutyltin dilaurate is added and stirred for 10 seconds, then 117 g of a mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate. After a further 5 seconds the mixture is poured into a box and the expansion begins. high-resilient foam with the following characteristics: density, kg / m2 34 CLD, g / cm2 (1) 28 resilience,% (2) 63 (1) Resistance to compression at 40% deflection.

(2) Ball rebound in%.

Example 2 920 g of polyether A at 20 ° C is placed in a beaker and 32.1 g of diethanolamine at 30 ° C is added under mechanical stirring at room temperature. 47.9 g of a mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate are added over 30 seconds to the vortex of the stirred mixture.

A white stable dispersion is formed and the temperature rises from 20 to 37 ° C over 30 seconds after the addition of the isocyanate. The polyaddition product contains. the isocyanate and alkanolamine in a molar ratio of 0.9 / 1.0 and the final product contains 8.0% of the polyaddition product in polyether polyol and has an acceptable viscosity at ambient temperature.

30 g of the above product are 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 are added. and stir and set the temperature to 22 ° C. Next, 0.75 g of dibutyltin dilaurate was added and stirred for 10 seconds, then 117 g of a mixture of 80% 2.4- and 20% 2.6-toluene was added.

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diisocyanate. After another 5 seconds, the mixture is poured into a box and the expansion begins. After a further 105 seconds after the mixing is complete, a non-shrinking, high-resilient foam has been obtained, the properties of which are similar to the properties of the product prepared according to Example 1.

Example 3 (Comparative Example)

A foam is prepared according to the method described in Example 2, but the 300 g of the polyether polyethylene polyol addition product is replaced with 300 g polyether polyol (polyether A) and only 100 g of the isocyanate is used. The expansion to form a foam occurs as in Example 2, but the resulting foam shrinks and its properties cannot be measured.

Example 4

The polyaddition product in polyether polyol is prepared using polyether A of Example 2 and foam-2Q also of Example 2, but the dibutyltin dilaurate is replaced with 0.6 g of stannous octoate. A high resilient non-shrinkable foam is obtained, the properties of which are similar to the properties of the product prepared according to Example 1.

Example 5

A polyaddition product is prepared and foamed according to Example 2, but the polyether A is replaced by polyether B. The stable dispersion in polyether polyol has a solids content of 8% and an acceptable viscosity 30 at ambient temperature. The resulting foam is non-shrinkable and has properties similar to those of the product prepared according to Example 1.

Example 6 A polyaddition product in polyether A is prepared according to Example 2, but the molar ratio of

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isocyanate and alkanolamine are 1.1 / 1.0 and the total solids content remains at 8%. The resulting product has a high but useful viscosity of over 2,500 cP at 25 ° C. Foam according to Example 2 gives a high resilient 5 non-shrinking foam.

Example 7 (Comparative Example)

A polyaddition product in polyether A is prepared according to Example 2, but the molar ratio of isocyanate to alkanolamine is 0.45 / 1.0 and the total solids content is 8%. Foam according to Example 2 gives a shrinking foam. The properties of this foam cannot be measured.

Example 8

A polyaddition product is prepared by taking 920 g of polyether A at a temperature of 20 ° C and mixing it with 24.5 g of diethanolamine at a temperature of 30 ° C and then with 55.5 g of crude MDI with vigorous stirring. A polyaddition product is obtained in polyether polyol with a solids content of 8% and a usable but high viscosity of over 3,000 cP at 25 ° C.

The product is foamed according to Example 2 to give a non-shrinkable high resilient foam.

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Example 9

A stable dispersion in polyether C at a temperature of 20 ° C is prepared by taking 800 g of polyether C and adding 80.24 g of diethanolamine at a temperature of 30 ° C and stirring at high speed before and during the addition of 119, 75 g of a mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate take place over 1 minute. A temperature rise of 29 ° C is observed and the product has, after cooling, an acceptable viscosity at ambient temperature and a solids content of 20%.

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Example 10

A stable dispersion is prepared according to Example 9, but the polyether C is replaced with polyether D. The resulting polyaddition compound in polyether D has a solids content of 20% and an acceptable viscosity at ambient temperature.

The stable dispersions prepared according to the preceding Examples 1, 2 and 5-10 are of a nonionic nature, i.e. the dispersions contain covalent polymeric substances without ionic groups. Furthermore, substantially no water or other ionic media is used in the preparation of the dispersions, nor are they present in them. As to the latter, the presence of traces of water which will tend to occur in commercially available polyols and other starting materials may be acceptable, although the presence of water is generally undesirable and should be kept as low as possible. Preferably, the water content should not be greater than 1% by weight, and the water content is notably much less than this value, e.g. below 0.1%, although it will be understood that in some cases it may be possible to carry out the process of the present invention with a water content greater than 1%.

The polyols used in carrying out the process of the present invention may be of the triol type containing predominantly primary hydroxyl groups, insofar as such polyols are particularly useful as starting materials for forming polyurethane foams. However, since the preparation of dispersions described in the examples above involves complete or mainly reaction of the isocyanate with the olamine and the polyether polyol, alone or mainly acting as unreacted carrier, it will be understood that it is possible to use any suitable polyether polyol. especially selected in accordance with the needs of the subsequent polyurethane formation reaction in which the polymer modified polyol is to be used. Thus, there can

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eg. polyols which are triols and / or diols and which have primary and / or secondary hydroxyl groups or any other suitable structure are used.

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Claims (2)

A process for preparing a polyurethane foam wherein a polyisocyanate in the presence of additives selected from propellants, catalysts, stabilizers, cross-linking agents, fire protection agents, pigments and fillers is reacted with a polymer-modified polyol which is a stable dispersion. prepared by polymerization of an alkanolamine with an organic polyisocyanate in the presence of a polyether polyol, characterized in that the alkanolamine is a di- or trialkanolamine and is used in the polymerization in a molar ratio to the polyisocyanate of 1.0 : 0.5 to 1.0: 1.6, and that the alkanolamine has at least predominantly reacted polyfunctionally with the isocyanate to form a polyaddition product dispersed in the polyether polyol which has at least predominantly acted as unreacted carrier in the formation of the polymer-modified polyol. Process according to claim 1, characterized in that the organic polyisocyanate reacting with the polymer-modified polyol is the same as that used to form the polymer-modified polyol.