DE10350816A1 - Production of a low monomer-content, low viscosity mixture containing polymethylene polyphenylene polyisocyanates for polyurethane foam production comprises distillative separation - Google Patents

Abstract

Production of a low monomer-content mixture containing polymethylene polyphenylene polyisocyanates (PMDI) comprises distillative separation at evaporation temperature below 160[deg]C of a mixture containing by weight (a) 2-nuclearly-substituted (n-s) methylene diphenyl diisocyanate (MDI) (35+/- 17%); (b) 3-n-s MDI (26+/-6%); (c) 4-n-s MDI (12+/-4%); (d) 5-n-s MDI (5+/-3%); and (e) 6- and higher n-s MDI (23+/-10%).

Description

The The invention relates to a low-monomer polymethylene polyphenylene polyisocyanate mixture (referred to as polymer MDI or PMDI) containing less than 0.4 2% by weight of methylene diphenyl diisocyanate (MDI) containing 20 to 45 wt% 3-core MDI, 10 to 30 wt% 4-core MDI and 30 to 60 Wt% 5-core and higher-core MDI, a process for its preparation and its use as Isocyanate component for One-component and two-component foams.

Einkomponentenschaumstoffe from aerosol containers are common in the field of civil engineering applied assembly means for installation of windows and doors in buildings as well as filler for structural engineering conditional cavities or wall breakthroughs for pipe installations. Such an aerosol container includes a prepolymer and blowing agents and additives. By Discharge of its contents by means of propellant, its foaming by Froth effect and by its hardening with humidity, creates the desired foam.

Einkomponentenschaumstoffe based on NCO-containing prepolymers are the best known Foams of this type. There are different products, Depending on the composition lead to hard to soft elastic foams. adversely In all of these formulations is that significant amounts of monomeric Isocyanate are present in these NCO-containing prepolymers and thus while the foaming process a certain hazard potential by breathable isocyanate.

Known are in this group of foams but also formulations with significantly reduced levels of free monomeric isocyanates.

DE-A-4441696 describes the use of commercially available polymer-MDI's, wherein by distillation at temperatures above 160 ° C and partially removed monomeric MDI under reduced pressure conditions and the remainder Bottom product as isocyanate component for the preparation of a 1K PUR assembly foam is used.

adversely in the solution described in DE-A-4441696 is that a polymer-MDI with a still relatively high residual monomeric diisocyanate content is used. Another technical defect is the increased viscosity of the polymer MDI used. Furthermore, this is Isocyanate prepolymerized before use, giving an additional Working step and another negative viscosity increase means. The described aerosol foam based on this relatively low-monomer high-viscosity polymer MDI's therefore has insufficient properties on.

task The invention was therefore a particularly suitable monomerarmes Polymethylene polyphenylene polyisocyanate mixture (also known as polymer-MDI mixture or PMDI mixture), i. a product with low viscosity at the same time significantly reduced technically caused residual monomer content. It was another object of the invention, the PMDI mixture in a substantial improved method of its monomeric MDI content.

A It was also an object of the invention to add isocyanate components develop, which are technically advantageous to handle, in particular in terms of viscosity. Furthermore, it was the object of the invention, 1-component or 2-component foams in particular in the form of aerosol foams develop using the above isocyanate components.

The Tasks were solved starting from a special PMDI mixture of the 2-core content was reduced by a special procedure.

• a) ein PMDI-Gemisch, umfassend 35 ± 17 Gew.-% 2-Kern-Methylendiphenyldiisocyanat (MDI), 26 ± 6 Gew.-% 3-Kern-MDI, 12 ± 4 Gew.-% 4-Kern-MDI, 5 ± 3 Gew.-% 5-Kern-MDI, 23 ± 10 Gew.-% 6-Kern- und höherkerniges MDI, bereit gestellt wird und anschließend
• b) das PMDI-Gemisch einem destillativen Trennverfahren unterworfen wird, wobei die Verdampfungstemperatur weniger als 160°C beträgt.

The invention thus provides a process for preparing a low-monomer mixture containing polymethylene polyphenylenepolyisocanate (PMDI), wherein

• a) a PMDI mixture comprising 35 ± 17% by weight 2-nucleus methylenediphenyl diisocyanate (MDI), 26 ± 6% by weight 3-core MDI, 12 ± 4% by weight 4-core MDI, 5 ± 3 wt% 5-core MDI, 23 ± 10 wt% 6-core and higher-nuclear MDI, and then
• b) the PMDI mixture is subjected to a distillative separation process, wherein the evaporation temperature is less than 160 ° C.

in the The scope of this invention is polymethylene polyphenylene polyisocyanate (PMDI) a mixture containing methylenediphenyl diisocyanate (as MDI or also referred to as monomeric MDI) with its higher-condensed Homologs understood, i. PMDI is a mixture of isocyanates with two and more aromatic nuclei and NCO groups.

PMDI becomes common by phosgenation of a mixture of isomers and homologues of the Diamino-diphenylmethane (MDA), which is obtained by condensation of aniline and formaldehyde available is manufactured. The homologues are formed by the condensation does not stop at the two-core product, but in decreasing quantity to the triune and higher nuclear Products continues.

The process according to the invention is generally carried out starting from a PMDI having the following composition:
a PMDI mixture comprising
35 ± 17% by weight of 2-methylenediphenyl diisocyanate (MDI),
26 ± 6 wt% 3-core MDI,
12 ± 4 wt% 4-core MDI,
5 ± 3 wt% 5-core MDI,
23 ± 10% by weight of 6-core and higher-nuclear MDI.

The Wt .-% - data refer to each 100% PMDI mixture.

In a preferred embodiment, the process according to the invention is carried out starting from a PMDI having the following composition:
43 ± 7% by weight of 2-methylenediphenyl diisocyanate (MDI),
24 ± 4 wt% 3-core MDI,
10 ± 4 wt% 4-core MDI,
5 ± 3 wt% 5-core MDI,
20 ± 8 wt% 6-core and higher-nuclear MDI.

The process according to the invention is particularly preferably carried out starting from the following PMDI composition:
47 ± 3% by weight of 2-methylenediphenyl diisocyanate (MDI),
23 ± 3 wt% 3-core MDI,
10 ± 3 wt% 4-core MDI,
5 ± 3 wt% 5-core MDI,
15 ± 6 wt% 6-core and higher-nuclear MDI.

in the inventive method For example, the above-mentioned PMDI mixture is subjected to a distillative separation process subjected and you get the low-monomer according to the invention Polymethylene polyphenylene polyisocyanate mixture (also known as low monomer PMDI mixture referred to).

It is an essential feature of the present invention that the distillative separation process is carried out at temperatures below 160 ° C. Prefers The separation process is at temperatures of 100 to 158 ° C, especially preferably from 120 to 155 ° C, in particular from 130 to 153 ° C carried out.

at the implementation the method according to the invention is the pressure in the separator generally 0.001 mbar to 10 mbar, preferably 0.01 mbar to 1 mbar, in particular 0.02 mbar to 0.9 mbar.

at the implementation the method according to the invention is Furthermore, the average residence time of the to be separated Mixture in the separator generally 30 to 1800 seconds, preferably 50 to 1600 seconds, more preferably 60 to 1500 Seconds.

When carrying out the process according to the invention, in addition, the evaporator capacity is generally 0.05 to 60 kg / m ² h, preferably 0.5 to 50 kg / m ² h. The temperature in the condenser is generally 30 to 60 ° C, preferably about 45 ° C.

In addition to the process according to the invention, the subject of the invention is also the corresponding process product, ie the object is a low-monomer polymethylene-polyphenylene polyisocyanate mixture containing
less than 0.4% by weight of 2-core methylene diphenyl diisocyanate (MDI), and containing
From 20 to 45% by weight of 3-core MDI,
10 to 30 wt% 4-core MDI and
From 30 to 60% by weight of 5-core and higher-nuclear MDI.

In a preferred embodiment, the monomer-poor PMDI mixture according to the invention is a mixture containing
less than 0.1% by weight of 2-core methylene diphenyl diisocyanate (MDI), and containing
From 20 to 40% by weight of 3-core MDI,
10 to 30 wt% 4-core MDI and
From 35% to 60% by weight of 5-nuclear and higher-nuclear MDI.

at the mixture of this embodiment it is a PMDI mixture with no hazard labeling due to the 2-core MDI portion is necessary because this is less than 0.1 wt .-% is.

The Monomer arms according to the invention PMDI mixture generally has a viscosity at 25 ° C of 3 to 150 Pas (pascal-second) and at 50 ° C from 100 to 7000 mPas, preferably a viscosity at 25 ° C of 10 to 100 Pas and at 50 ° C of 300 to 5000 mPas, particularly preferably a viscosity at 25 ° C of 12 to 60 Pas and at 50 ° C of 500 to 4000 mPas, wherein the viscosity determined according to DIN 53 018 has been.

Of Furthermore, the monomer poor according to the invention PMDI mixture generally has a functionality of 3 to 5, preferably one functionality from 3.8 to 4.4, more preferably a functionality of 3.9 up to 4.3.

Of the NCO content of the PMDI mixture according to the invention is generally 27 to 33 wt .-%, preferably 28 to 32.5 wt .-%.

Finally, the invention relates to the use of the monomer-poor PMDI mixture according to the invention for the production of polyure than-1-component foam and / or polyurethane-2-component foam.

For the use of the low-monomer content of the invention PMDI mixture for the preparation of an isocyanate component for polyurethane-1 components and / or polyurethane 2-component foam are three preferred embodiments proposed, which are three different formulations an isocyanate component which is the low-monomer content of the invention PMDI mixture included. These isocyanate components are distinguished by making sure that it depends on the type and level of features you want the final foam is a special mixture of the low-monomer content of the invention PMDI and other liquid represents inert compounds or compounds carrying isocyanate end groups. It is also essential that these are isocyanate components acting at room temperature, as part of the manufacturing process the aerosol foams, with respect to their viscosity represent technically manageable components.

• i) erfindungsgemäßes monomerarmes PMDI-Gemisch und
• ii) Verdünnungsmittel.

The first preferred embodiment relates to an isocyanate component for producing 1-component polyurethane foams containing

• i) according to the invention low-monomer PMDI mixture and
• ii) diluent.

Around an isocyanate component in technically manageable viscosity and sufficient To obtain isocyanate content, the content of low-monomer polymer MDI should 50 to 95 wt .-%, preferably 60 to 90 wt .-%, based on the total weight of components i) and ii).

thinner are generally compounds that act as non-reactive substances significant dilution effect achieve. As a suitable diluent For example, trichloropropyl phosphate or other alkyl (or Anl) -phosphates proved. Furthermore is by its particularly thinning Effect dimethoxymethane suitable.

at Use of components i) and ii) is preferably to be ensured that an isocyanate component is obtained which is advantageous in viscosity is manageable.

at Use of a suitably matched polyol component and Propellant gases in the aerosol can it produces an isocyanate prepolymer, which despite the increased medium functionality the monomer poor compared to the conventional PMDI component too a hard-elastic foam with very good assembly properties leads.

When Polyols or polyol come (here and in the two below mentioned embodiments) the usual used in polyurethane chemistry polyetherols, polyesterols, Polymer polyols or mixtures thereof are used. In general, be the polyols used in an amount that the ratio of across from Isocyanate-reactive groups (OH groups) to isocyanate groups 1 to 1.1 to 1 to 10.

• i) erfindungsgemäßes monomerarmes PMDI-Gemisch,
• ii) Isocyanatprepolymere, erhältlich durch Umsetzung eines Polyisocyanats mit Polyolen und
• iii) gegebenenfalls Verdünnungsmittel.

The second preferred embodiment relates to an isocyanate component for producing 1-component polyurethane foams containing

• i) low-monomer PMDI mixture according to the invention,
• ii) isocyanate prepolymers obtainable by reacting a polyisocyanate with polyols and
• iii) optionally diluents.

In general, 100% by weight of components i) to iii) contains the following composition:
From 5 to 95% by weight, preferably from 10 to 30% by weight, of low-monomer PMDI (i),
0.1 to 95% by weight, preferably 30 to 70% by weight, of polyisocyanate prepolymers (ii),
0 to 50 wt .-%, preferably 10 to 40 wt .-% of diluent (iii).

The Isocyanate prepolymers ii) are generally known from the prior Technique known processes prepared, for example by the Polyisocyanate, especially diisocyanate, at temperatures of about 50 to 80 ° C with polyols, in particular with diols, converted to a prepolymer becomes. To exclude side reactions by atmospheric oxygen, should the reaction vessel with a Inert gas, preferably nitrogen, to be rinsed. The polyol-polyisocyanate ratio becomes chosen so the NCO content of the prepolymer is 8 to 30% by weight, preferably 10 to 25 wt .-%, is.

In a preferred embodiment is guaranteed the monomer freedom for certain applications the prepolymer even before its mixing with the low-monomer content of the invention PMDI and the optional diluent demonomerised. The demonomerization is preferably carried out by Distillation. The resulting prepolymer preferably has one 2-core MDI content of less than 0.1% by weight and an NCO content from 1.5 to 14% by weight.

When using components i) to iii), it is preferable to ensure that an isocyanate component is obtained which is advantageously handleable in viscosity. When using an appropriately tuned, above described NEN polyol component and propellant gases in the aerosol can from an isocyanate prepolymer is produced, which despite the increased average functionality of the PMDI component leads to a foam having sufficient hardness for assembly purposes at elevated tensile properties.

• i) erfindungsgemäßes monomerarmes PMDI-Gemisch,
• ii) Isocyanatsilanprepolymere, erhältlich durch Umsetzung eines Polyisocyanats mit Polyolen und anschließender Umsetzung mit Silanen, die mindestens eine gegenüber Isocyanaten reaktive Gruppe aufweisen und
• iii) gegebenenfalls Verdünnungsmittel.

The third preferred embodiment relates to an isocyanate component for producing 1-component polyurethane foams containing

• i) low-monomer PMDI mixture according to the invention,
• ii) Isocyanatsilanprepolymere, obtainable by reacting a polyisocyanate with polyols and subsequent reaction with silanes having at least one isocyanate-reactive group and
• iii) optionally diluents.

In general, 100% by weight of components i) to iii) contains the following composition:
From 5 to 95% by weight, preferably from 10 to 30% by weight, of low-monomer PMDI (i),
0.1 to 95 wt .-%, preferably 30 to 70 wt .-% silane-terminated prepolymer (ii) and
0 to 50 wt .-%, preferably 10 to 40 wt .-% of diluent (iii).

Under Isocyanate silane prepolymers become reaction products of above described NCO prepolymers with silanes containing at least one isocyanates have reactive group, preferably aminosilanes, in particular amino (di- or tri-methoxy- or ethoxy) silanes. You will be in general made in such a way that in the first stage a NCO prepolymer of diisocyanates and polyols, especially diols, will be produced. In a second stage, the prepolymer with the silane which at least one isocyanate-reactive group has, preferably aminosilane reacted. In this chain-breaking Reaction are proportional, the isocyanate groups by the silane groups replaced. The conversion can be both equivalent but also in Aminosilanunterschuss (there are free NCO groups available).

to targeted influencing of the isocyanate content and the functionality is in Following the above-mentioned modification process, the monomer-poor according to the invention PMDI added to this prepolymer.

at Use of components i) to iii) is preferred to pay attention that an isocyanate component is obtained which is advantageous in viscosity is manageable. When using a suitably matched polyol component as well as propellants in the aerosol can it becomes an isocyanate prepolymer generated, which despite the increased middle functionality the PMDI component leads to a foam which contains both isocyanate as well as having silane end groups, bringing with it the possibility opens, one over both Silane groups as well over Urea curing foam with good mechanical properties.

For all three embodiments holds that the process of manufacturing the 1-component and / or 2-component aerosol foam from the above components the reaction of the components at stoichiometric excess the isocyanate component in a pressure vessel in the presence of liquid gases includes. The resulting dissolved in the liquefied gases prepolymer is in the case of processing to foam taken from the pressure vessel, foamed by solved Gas at changed Pressure conditions and hardens subsequently by humidity and / or further added Moisture to the finished foam.

The The present invention is illustrated by the following examples become.

The following examples are divided into:
Preparation of low-monomer polymer MDI
Preparation of an isocyanate component 1 (polymer MDI & diluent) and the 1-component aerosol foam built up on this component
Preparation of an isocyanate component 2 (polymer MDI & NCO prepolymer & diluent) and the 1-component aerosol foam built up on this component
Preparation of an isocyanate component 3 (polymer MDI & silane prepolymer & diluent) and the 1-component aerosol foam built up on this component
Preparation of low-monomer polymer MDI

example 1

In a laboratory evaporator type VKL 70-4 (VTA GmbH Deggendorf) were using polymeric MDI (BASF: Lupranat M 10 R) produced the claimed low-viscosity low-monomer polymer MDI. The starting product had the following core distribution:
47% 2-core MDI
23% 3-core MDI
10% 4-core MDI
5% 5-core MDI
15% 6-core and higher nuclear MDI

At an evaporation temperature of 153 ° C, an evaporator capacity between 4.4 and 0.5 kg / m ² · h, 0.04 mbar, a condenser temperature of 45 ° C and a residence time of 161 s was a low-viscosity low-monomer polymer MDI having an NCO content of 29.2 wt .-%, a viscosity of 2228 mPa · s at 50 ° C, a 2-core MDI content of 0.19 GPC FL% and a average functionality of 4.11.

Preparation of the isocyanate component 1:

Example 2

Out 820 g of the monomer-poor polymer MDI of Example 1 and 180 g of trichloropropyl phosphate an isocyanate component prepared.

These Isocyanate component has at an isocyanate content of 23.9 wt .-% a viscose at 25 ° C of 6600 mPas.

Preparation of the polyol component 1

Example 3

Out 200 g of a polyether polyol based on glycerol / propylene oxide with a hydroxyl content of 150 mgKOH / g, 550 g of a polyether polyol based on glycerol / propylene oxide / ethylene oxide with a hydroxyl content of 42 mgKOH / g, 80 g of a brominated polyether polyol having a Hydroxyl content of 330 mgKOH / g, 80 g of a polyethylene glycol with a hydroxyl content of 187 mgKOH / g, 25 g of a silicone foam stabilizer and 8 g Dimorpholinodiethylether and 0.5 g of a silicone defoamer is a Polyol component produced.

Production of the 1-component aerosol foam 1 (in the aerosol can)

Example 4

170 g of the polyol component of Example 3 are in a 1 liter aerosol can filled. For this purpose, 480 g of the isocyanate component according to Example 2 are metered and subsequently closed the aerosol can with a tilt valve. 152 g of tetrafluoroethane and 65 are successively passed through the valve g dimethyl ether as liquefied gases dosed. After the dosage of the individual components, the content by shaking homogenized. The onset of prepolymer reaction is only after 3 to 4 days completed. For the purpose of quick testing will be the finished aerosol can is stored for approx. 24 h at 50 ° C in a warming cabinet and is after that time and the cooling down Room temperature testable.

Production of the 1-component aerosol foam 1 (testing of the finished foam)

Example 5

paper Flies is applied to a solid surface and moistened.

On the tilt valve of the finished aerosol can according to Example 4 wid the associated Plastic tubes screwed on and the contents of the aerosol can, with valve down, by operation of the valve over the plastic tube under foaming taken.

The foaming Mixture hardens to a dimensionally stable hard elastic foam.

By another foaming of the remaining content in the gap of a conventional building construction doorframe and masonry the assembly suitability could be proven.

Preparation of an isocyanate component 2

Example 6

Out 155 g of the monomer-poor polymer MDI of Example 1, 618 g of a low-monomer prepolymer based on methylene diphenyl diisocyanate (2,4'-MDI) and a polypropylene glycol MW = 450 g / mol, 167 g trichloropropyl phosphate and 60 g of dimethoxymethane, an isocyanate component is prepared.

These Isocyanate component has at an isocyanate content of 9.70 wt .-% NCO a viscous at 25 ° C of 9500 mPas.

Preparation of a polyol component 2

Example 7

Out 700 g of a polyether polyol based on sucrose / propylene oxide with a hydroxyl content of 410 mgKOH / g, 100 g of a polyethylene glycol with a hydroxyl content of 187 mgKOH / g, 100 g of a silicone foam stabilizer and 70 g of dimorpho-linodiethyl ether and 1.2 g of a silicone defoamer prepared a polyol component.

Production of the 1-component aerosol foam 2 (in the aerosol can)

Example 8

41 g of the polyol component of Example 7 are filled into a 1 liter aerosol can. For this purpose, 656 g of the isocyanate component according to Example 6 are metered and subsequently closed the aerosol can with a tilting valve. 122 g of tetrafluoroethane and 52 g of dimethyl ether are metered in successively as liquid gases through the valve. After dosing the individual components, the contents are homogenized by shaking. The onset of prepoly The reaction is completed after 3 to 4 days. For the purpose of rapid testing, the finished aerosol can is stored for approx. 24 h at 50 ° C in a warming cabinet and is after this time and the cooling to room temperature testable.

Production of the 1-component aerosol foam 1 (testing of the finished foam)

Example 9

paper Flies is applied to a solid surface and moistened.

On the tilt valve of the finished aerosol can according to Example 8 wid the associated Plastic tubes screwed on and the contents of the aerosol can, with valve down, by operation of the valve over the plastic tube under foaming taken.

The foaming Mixture hardens to a dimensionally stable elastic foam.

By another foaming of the remaining content in the gap of a conventional building construction doorframe and masonry, the mounting suitability could be detected because this elastic foam nevertheless has sufficient hardness.

Claims (10)

Process for the preparation of a low-monomer Mixture containing polymethylene polyphenylenepolyisocanate (PMDI), in which a) a PMDI mixture comprising 35 ± 17% by weight 2-nucleus methylenediphenyl diisocyanate (MDI), 26 ± 6% by weight 3-ring MDI, 12 ± 4 Wt% 4-core MDI, 5 ± 3 Wt% 5-core MDI, 23 ± 10 % By weight of 6-core and higher-nuclear MDI, is provided and subsequently b) the PMDI mixture a distillative separation process is subjected, wherein the evaporation temperature less than 160 ° C is. Method according to claim 1, characterized in that that the pressure in the separator 0.001 mbar to 10 mbar, preferably 0.01 mbar to 1 mbar. Method according to claim 1, characterized in that that the average residence time of the mixture to be separated in the separator 30 to 1800 seconds, preferably 50 to 1600 Seconds, is. Low-monomer polymethylene polyphenylene polyisocyanate mixture, containing less than 0.4% by weight of 2-methylenediphenyl diisocyanate (MDI) containing From 20 to 45% by weight of 3-core MDI, 10 to 30 wt .-% 4-core MDI and From 30 to 60% by weight of 5-nuclear and higher-nuclear MDI. Low-monomer PMDI mixture according to claim 4, characterized characterized in that it has a viscosity at 25 ° C of 3 to 150 Pa s and at 50 ° C of 100 up to 7000 mPa s. Low-monomer PMDI mixture according to claim 4 or 5, characterized in that it has a functionality of 3.8 to 4.4. Use of a low-monomer PMDI mixture after one of the claims 4 to 6 for the production of polyurethane-1-component foam and / or Polyurethane 2-component foam. Isocyanate component for the production of polyurethane 1-component and / or polyurethane 2-component foams, containing i) low-monomer PMDI mixture according to one of claims 4 to 6 and ii) diluent. Isocyanate component for the production of polyurethane 1-component and / or polyurethane 2-component foams, containing i) low-monomer PMDI mixture according to one of claims 4 to 6 ii) Isocyanate prepolymers, obtainable by reaction of a Polyisocyanate with polyols and iii) optionally diluents. Isocyanate component for the production of polyurethane 1-component and / or polyurethane 2-component foams, containing i) low-monomer PMDI mixture according to one of claims 4 to 6 ii) Polyisocyanatsilanprepolymere, obtainable by reaction of a Polyisocyanate with polyols and subsequent reaction with silanes iii) optionally diluents.