DE3103757C2 - - Google Patents

Description

Polyurethane foams and their manufacture from one Polyisocyanate with a polymer-modified polyol are known and are considered to be soft-elastic foams they are used in particular for upholstering seats. You have to go through just one for these purposes stable formula elasticity over a long service life and they must be flame-resistant.

GB-PS 15 01 172 describes a method of manufacture of polyurethane foams using Polyol dispersions from polyadducts of Polyisocyanate and primary amines, secondary amines and hydrazines or hydrazides in the presence of water, Activators, emulsifiers, foam stabilizers and other additives. Although these well-known foams have some have good properties but will have good flame resistance achieved by adding flame retardants, through which, however, the formation of a flexible foam becomes difficult and expensive.

DE-PS 13 01 128 is a one-step process known for the production of rigid foam polyurethanes. Here, a polyol is made from a condensation product, by reacting an organic polyhydroxy compound with an alkylene oxide with at least 3 carbon atoms was obtained, used and reacted with a diisocyanate.  

DE-OS 27 34 400 relates to a flame retardant Polyurethane foam and process for its production, an organic polyisocyanate with a Polyhydroxyl compound in the presence of water or others Blowing agents, catalysts and surfactants Funds is implemented. The polyhydroxyl compound consists of a polyol with at least two hydroxyl groups and a polyol with at least two hydroxyl groups and an aliphatic amino alcohol in one Quantity from 2.1 to 8.0 equivalents per hydroxyl group of the polyol. Used to increase flame resistance a corresponding additive in a quantity of less than 10 parts by weight per 100 parts by weight Polyol.

The aim of all of these processes is to make them flame retardant To produce polyurethane foams. By adding Additives, especially larger ones if necessary Amounts of flame retardants, however, flexibility the foams impaired, and none of the known Paths leads to really satisfactory foams.

The object of the invention is a method for the production to create a polyurethane foam that becomes one Product leads that in addition to excellent fire behavior also easy to process and highly durable Has flexibility.

The invention therefore relates to a method for manufacturing of a polyurethane foam by implementing one Polyisocyanate with a polymer modified polyol in Presence of blowing agents, catalysts and stabilizers and optionally crosslinking agents, flame retardant Agents, pigments and fillers. The method is characterized in that as polymer modified polyol uses one that  by implementing primary, secondary and / or tertiary alkanolamines with polyisocyanates in one Molar ratio of alkanolamine to polyisocyanate of 1: 0.5 to 1: 1.6 in the presence of a polyol has been.

Appropriate developments of the method according to the invention are marked in the subclaims.

This process creates a polyurethane foam get high quality, which is different from that of the GB-PS 15 01 172 known prior art through a better fire behavior and easier processing distinguished. This result is obviously surprising by replacing the polyamines, ureas and polyhydrazocarbonamides of the known method by the alkanolamines used according to the invention been achieved. Compared to the other two above known method mentioned that according to the invention Process received product even greater flexibility on. It is particularly surprising that the process even without adding significant amounts of flame retardants a high flame resistance of the foams is achieved, with practically no smoke development when extinguishing itself can be determined. These properties, excellent Flame behavior and high flexibility make that foam produced according to the invention to a valuable Product, especially in the upholstery of seating of motor vehicles and airplanes.

It was surprising to find that through use of alkanolamines in a certain molar ratio such a convincingly good product for polyisocyanate  that can be manufactured for its use important requirements fully.

The alkanolamine with one or more OH groups and one or more primary, secondary and / or tertiary amino groups act as a polyfunctional reactant, because of two or more reactive hydrogen atoms, being a polyaddition product is formed with the polyisocyanate. All or only some of the hydrogen atoms react. It is believed that the polyaddition reaction straight and / or branched chains by combination of the polyisocyanate and hydroxyl groups to to urethane bonds

(-NH-CO-O-)

respectively.

The term polymer modified as used herein Polyol includes both physical and chemical Combinations and their mixtures. However, it is believed that the method according to the invention predominantly leads to a physical combination. Such can be in the form of a solution or a stable dispersion of the polyaddition product in the polyol, namely depending on the raw materials used.

The molar ratio of alkanolamine to polyisocyanate is from 1: 0.5 to 1: 1.6, where in the presence of a Polyether polyols with a molecular weight in the range from 200 to 10,000, in particular from 2800 to 7000 becomes. The converted alkanolamine to polyisocyanate gives 1 to 35 wt .-%, based on the weight of the polyol.

Practically all corresponding primary, secondary and tertiary alkanolamines and their combinations will. This also applies to substituted alkanolamines.  This is a particularly preferred alkanolamine Triethanolamine.

Aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic compounds are used as they are for the polyisocyanate / Polyol-polyurethane reaction for example GB-PS 14 53 258 are known. These are commercial products such as 2,4- and 2,6-tolylene diisocyanates as well as their mixtures, commonly referred to as TDI or polyphenylpolymethylene polyisocyanates, as by the condensation of aniline with formaldehyde and subsequent phosgenation obtained and generally as Raw MDI are referred to, or polyisocyanates Carbodiimide groups, urethane groups, allophonate groups, Isocyanate groups and urea or biuret groups, the are generally referred to as polyisocyanates.

Essentially all corresponding ones are suitable for implementation Polyols, for example polyether polyols a molecular weight of 200 to 10,000, such as from the GB-PS mentioned above are known.

It has been found that not all alcohol and amino groups of the alkanolamine used in the polyaddition reaction react with the polyisocyanate under all circumstances have to. In some cases, the alkanolamine can be monofunctional respond while doing in yourself as a Chain terminators work.

If desired, the polyaddition reaction can be carried out by adding of corresponding, in the polyisocyanate / polyol Catalysts used polyurethane reaction performed are, for example organometallic compounds, such as tin octoate and dibutyltin dilaurate and / or  Amines such as triethylenediamine. The amount of the catalyst can compared to that commonly used in manufacturing amount of polyurethane used be small e.g. B. 0.02 wt .-% versus 0.2 wt .-%, based on the polyol. However, larger quantities are not harmful.

If a primary or secondary alkanolamine in the Implementation of the alkanolamine used with the polyisocyanate catalysis is not absolutely necessary. But it can be beneficial if the reaction with a tertiary alkanolamine, for example Triethanolamine.

The molecular weight of the polyaddition product can by varying the quantitative ratio between the alkanolamine on the one hand and the polyisocyanate on the other can be set. Although a molar ratio of Alkanolamine to polyisocyanate in the range of 1.0: 0.5 to 1.0: 1.5 is preferred and essentially equivalent molar amounts are particularly expedient, it is possible to have a higher proportion of polyisocyanate to use when a higher viscosity or even rapid gelling that can be tolerated at higher isocyanate contents can occur. An upper one Limit would be, for example, 1.0: 1.55 or 1.0: 1.6 then possible. With a reduced amount of polyisocyanate becomes the molecular weight of the polyaddition product lowered along with the viscosity. In general becomes a molar ratio of alkanolamine to organic Polyisocyanate in the range of 1.0: 0.8 to 1.0: 1.1 preferred.

A desired concentration can be achieved either by direct Choice of reactants reached, or alternatively by subsequent dilution of the polyaddition product formed  adjusted with additional polyether polyol will.

In general, the reactants can Temperatures of 0 ° C or above their melting points, depending on which is deeper, up to 150 ° C with each other be mixed. Mixing is preferably carried out at room temperature or just above melting points the reactant, whichever Temperature is lower, up to 70 ° C. It is but also possible the reactants below to mix their melting points.

The reaction is exothermic and the temperature rises is determined according to the proportion of the polyaddition product formed, based on the weight of the polyether polyol, observed.

The better the reactants are mixed, the finer the particle size of the dispersion - if such is formed - and the smaller the Viscosity. It can be done in a simple batch process be worked in which one of the alkanolamine and Polyisocyanate reactants first in the polyether polyol dissolved or dispersed and then the other reactants in the zone of the most violent Movement is added. On the other hand, it is also possible to perform mixed operations in pipelines. All reaction participants are controlled pumped in controlled quantities and simultaneously mixed. Or it can be a reactant first mixed with the polyether polyol and then the other reactant can be added.  

The dispersion in the polyether polyol can either immediately after the reaction has ended or after a longer period Dwell time can be used. For example the polyaddition product in a polyether polyol from a row or pipe mixer where the implementation takes place directly in the mixing head of a known Dosing machine for polyurethane foam production will. If the reaction of the alkanolamine with the Polyisocyanate runs relatively slowly, between a storage tank for the mixer and the polyurethane mixing head interposed to complete implementation for an additional period of time grant.

The polymer modified polyol can be used either during or after the reaction additives, such as activators, Stabilizers, crosslinking agents, water, blowing agents, fire retardants and / or pigment pastes added will.

The polymer modified used in the present invention Polyol is used in the manufacture of polyurethane foam used. If the product is in the form of a stable polyol dispersion is present, d. H. in a dispersion that does not fail or at least during the mixing process with foaming agents other than dispersion remains stable is the dispersed polyaddition product particularly effective as a polymeric filler the production of very resilient, comfortable and easy to process foam. Such a dispersed Product gives strength while it is at the same time Tear open cell walls.

The product in the form of a polyol solution can be useful be for the production of a polyurethane foam,  who has other properties than one who under Use of polyol dispersions is formed.

In general, a polymer modified Polyol in the form of a stable dispersion is suitable for the production of soft, semi-hard and hard Polyurethane foams with improved properties, like greater hardness. Non-disappearing foams made of high elasticity as they are known in the industry since the polyol is dispersed Polyaddition product has an opening effect Has. The dispersions are also used for production of elastomers based on polyurethane, Suitable coatings and coatings.

In the manufacture of polyurethane foams the polyether polyols are selected in a manner known per se, for flexible, semi-flexible or rigid foams to build. Polyether polyols are used for flexible foams with a hydroxyl number of 20 to 80 and with 2 to 4 OH groups preferred per molecule. if desired mixtures of polyether polyols can also be used will. Organic polyisocyanates used in manufacturing of polyurethane foams are known and they can be the same as above described in the reaction with the alkanolamine are.

The reaction mixture for polyurethane foam formation can according to the type of polyurethane foam to be produced contain other conventional ingredients. Such additives are catalysts, for example tertiary amines and / or organic tin compounds; Crosslinking agents or chain extenders,  for example diethanolamine, triethanolamine, ethylene glycol, Glycerin, dipropylene glycol and phenylenediamine; flame retardants, for example halogenated Alkyl phosphates; and fillers, for example barium sulfate.

The reaction mixture is used to produce foams Blowing agent added. Examples of such blowing agents are liquids, including water, that with the polyisocyanate reacts, forming carbon dioxide becomes, or inert volatile liquids which during the exothermic reaction or under pressure with mechanical Evaporate foaming. Examples of such liquids are halogenated hydrocarbons with a Boiling point of not more than 100 ° C at atmospheric pressure. Preferred liquids are those whose Boiling point is not above 50 ° C. Particularly suitable Liquids are chlorofluorocarbons, for example trichlorofluoromethane and dichlorodifluoromethane, and chlorinated hydrocarbons, for example Dichloromethane. The amount of blowing agent to be added is chosen in a manner known per se to Obtain foams of the desired density. In general are 0.005 to 0.3 mol of gas per 100 g of reaction mixture Cheap. If desired, the density of the formed foam modified by "overpacking" will. The reaction mixture is in a given closed form, the volume of which is smaller than the finished foam would take if he could expand freely.

Generally speaking, the composition of the mixture be so for the polyurethane foam production that Ratio of isocyanate groups to active hydrogen atoms  essentially within the range of 0.9: 1 to 1.2: 1. But it can also be higher Ratios are used.

If a polyurethane foam is made, it is normally required to stabilize the cells or regulate that by adding a foam stabilizer or cell regulators, such as polysiloxane Polyalkylene oxide block copolymers are formed. The additives can be direct carbon-silicon bonds or carbon-oxygen-silicon bonds between the organic and the polysiloxane units exhibit. When "highly elastic" polyurethane foams are produced, are dimethyl silicone oils or their low molecular modifications are useful.

One-step or direct process as well as prepolymer or quasi-prepolymer processes depending on the desired polyurethane foam can be used.

The components of the reaction mixture for production of polyurethane foams can be used in any appropriately mixed together, so for example in one of the known mixers. If some of the individual components may be desired to be premixed to the number of streams reduce that brought to the final stage of mixing Need to become. It is often convenient to use a two-stream System use, where a stream is a polyisocyanate or a prepolymer and the second stream all contains other components of the reaction mixture.

The invention is based on a few exemplary embodiments explained in more detail. The quantities are all in weight or weight percent. If nothing else said, was always worked at room temperature.  

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

Polyether A

Polyether of propylene oxide started with glycerin, with 15% ethylene oxide, OH number 35, primary hydroxyl groups about 75%.

Polyether B

Polyether started with trimethylolpropane from Propylene oxide with ethylene oxide, OH number 34, primary Hydroxyl groups about 80%.

example 1

900 g of polyether A at 20 ° C. were mixed with 48.7 g of triethanolamine mixed at 20 ° C and at 20 ° C 51.2 g of a mixture from 80% 2,4- and 20% 2,6-tolylene diisocyanate mixed in violently for five seconds. 0.3 g dibutyltin dilaurate were added as a catalyst and it there was a quick response, taking the temperature of the mixture rose from 20 to 37 ° C during 3 minutes from the end of the addition of the catalyst.

After cooling, the stable dispersion had about 10 wt .-% solids a viscosity of 1600 mPa · s at 25 ° C.

300 g of the product obtained were placed in a beaker given and then 7.8 g of water, 3 g of diethanolamine, 0.21 g bis (2-dimethylaminoethyl) ether and 1.5 g a silicone oil added and stirred. The temperature was set at 22 ° C. Next came the Add 0.75 g of dibutyltin dilaurate. It was  Stirred for 10 seconds, and then 117 g a mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate admitted. After another five seconds it was Poured mixture into a box and it followed Expansion. After 105 seconds, starting from the end of mixing, was a non-waning, "highly elastic" Foam formed, the following properties featured:

Density, kg / m³34 CLD, g / cm² (¹) 28 elasticity,% (²) 63 (¹) compressive strength at 40% deflection.
(²) ball return%.

Example 2

920 g of polyether A at 20 ° C. were placed in a beaker and 32.1 g of diethanolamine at 30 ° C under mechanical Stirring added at room temperature. After that, during 30 seconds 47.9 g of a mixture of 80% 2.4 and 20% 2,6-tolylene diisocyanate in the vortex of the stirred mixture brought in. A white stable formed Dispersion, and the temperature was within 30 seconds after the addition of the polyisocyanate at 20 ° C. rose to 37 ° C. The polyaddition product contained the alkanolamine and polyisocyanate in a molar ratio of 0.9 and the final product contained 8.0% of the polyaddition product in polyether polyol. It had a usable viscosity at room temperature.

300 g of the polymer modified polyol were added to a Beaker and then with 7.8 g of water, 3 g Diethanolamine, 0.21 g bis (2-dimethylaminoethyl) ether and 1.5 g of silicone oil added. The mixture was stirred and set the temperature to 22 ° C. Subsequently  0.75 g of dibutyltin dilaurate was added and 10 seconds touched. This was followed by the addition of 117 g of one Mixture of 80% 2,4- and 20% 2,6-tolylene diisocyanate. This mixture was put in a box after 5 seconds poured where the expansion started. After another 105 Seconds, starting from the end of the mixing process, was a non-shrinking, "highly elastic" foam who had similar properties to that Product from example 1.

Comparative Experiment I

A foam was produced as in Example 2, but instead of 300 g of the polymer modified Polyols 300 g of the polyether polyol and only 100 g of the Polyisocyanate were used. Foaming took place as in Example 2, but the one formed here Foam shrank, and its properties were not measurable.

Example 3

A polymer modified polyol was used of polyether A according to Example 2. Foaming was also carried out as in the example 2, except that the entire Dibutyltin dilaurate replaced by 0.6 g of tin octoate has been. It became a non-shrinking foam from maintain high elasticity, its properties resembled those of the foam from Example 1.

Example 4

It became a polymer modified polyol as in Example 2 manufactured and also in the same way foamed, with the exception that the polyether A was replaced by the polyether B. The stable  Dispersion in polyether polyol had a solids content of 8% and a usable viscosity at room temperature. A non-shrinking foam was obtained its properties are those of the product from Example 1 corresponded.

Example 5

It became a polymer modified polyol as in Example 2 produced, with the exception that the molar Ratio of alkanolamine to polyisocyanate was 1.1. The total solids remained at 8%. The received Product had a high but usable viscosity of over 2500 mPa · s at 25 ° C. Foaming according to the example 2 resulted in a highly elastic, non-shrinking Foam.

Comparative experiment II

It became a polymer modified polyol as in Example 2, except for the molar ratio from alkanolamine to polyisocyanate from 0.45. The total solids content was 8%. Foaming according to the example 2 showed a shrinking foam, and the properties it was not measurable.

The stable formed according to Examples 1 to 5 Dispersions are non-ionic in nature. This means, the dispersions contain covalent polymeric substances, where ion groups are missing. In addition, at Production of the dispersions neither water nor a other ionic medium used, and such compounds are also not included in the dispersions. However, the presence of water can be tolerated be, if necessary, in commercially available polyols and other starting products may be present. In general, however, there is water in the dispersions  undesirable, and its amount should be as low as be kept possible. The water content should be preferred not more than 1% by weight, expediently a lot less, for example less than 0.1% by weight. It however, it is understood that in some cases it is possible to use the method according to the invention in a Perform water content of more than 1 wt .-%.

The used in the method according to the invention Polyols can be triols, which are primarily primary Hydroxyl groups contain, as far as such polyols in particular are suitable as starting material for the Manufacture of polyurethane foams. However, since Process according to the invention for the production of polymer-modified polyols and especially at the formation of those described in the examples Dispersions completely or predominantly the polyisocyanate reacts with the alkanolamine and the polyol serves primarily as an unconverted carrier it is understandable that it is possible to add any value To choose alcohol that meets the requirements of a subsequent Polyurethane foam production corresponds. For example, triols and / or diols with primary and / or secondary hydroxyl groups or any other corresponding structures are used will.

Claims (4)

1. A process for producing a polyurethane foam by reacting a polyisocyanate with a polymer-modified polyol in the presence of blowing agents, catalysts and stabilizers and, if appropriate, crosslinking agents, flame retardants, pigments and fillers, characterized in that the polymer-modified polyol used is one which is obtained by reacting primary, secondary and / or tertiary alkanolamines with polyisocyanates in a molar ratio of alkanolamine to polyisocyanate of 1: 0.5 to 1: 1.6 in the presence of a polyol. 2. The method according to claim 1, characterized, that the alkanolamine and the polyisocyanate in a molar ratio of 1: 0.5 to 1: 1.5, as Polyol is a molecular weight polyether polyol from 200 to 10,000 used, the reacted Alkanolamine and the polyisocyanate together 1 make up to 35 wt .-%, based on the polyether polyol. 3. The method according to claim 2, characterized, that at a molar ratio of alkanolamine too Polyisocyanate from 1: 0.8 to 1: 1.1 works.   4. The method according to claims 1 to 3, characterized, that triethanolamine is used as the alkanolamine.