EP1951776A1

EP1951776A1 - Pipa-polyole production method

Info

Publication number: EP1951776A1
Application number: EP06806127A
Authority: EP
Inventors: Catherine J. LÖVENICH; Hans Hettel; Bert Klesczewski; Christel Fussangel
Original assignee: Bayer MaterialScience AG
Current assignee: Bayer Intellectual Property GmbH
Priority date: 2005-10-22
Filing date: 2006-10-10
Publication date: 2008-08-06
Also published as: BRPI0617734A2; RU2008119951A; CA2626470A1; CN101291968A; US20070238796A1; JP2009512746A; DE102005050701A1; KR20080072862A; WO2007045372A1; NO20082169L

Abstract

The invention relates to a method for producing pyrrole-imidazole-polyamide (PIPA) polyols and the use thereof for producing polyurethane soft foam materials.

Description

Process for the preparation of PIPA polvolenes

The present invention describes a process for the preparation of PIPA polyols and their use for the production of flexible polyurethane foams.

PUR foams are obtained by reacting polyisocyanates and compounds having at least two reactive hydrogen atoms in the presence of blowing agents and other additives. An overview of the production of polyurethanes is given in Kunststoff-Handbuch, volume VE, "Polyurethane", 3rd edition, 1993, by Dr. G. Oertel (Carl Hanser Verlag).

Highly elastic HR foams are produced predominantly with filler-modified polyols. Different types of filled polyethers are known: polymer polyols (PMPOs), polyurea dispersions (PHD polyols) and polyisocyanate polyaddition polyols (PIPA polyols). PMPOs are obtained by the radical copolymerization of styrene and acrylonitrile in polyols (US Pat. No. 3,304,273 and US Pat. No. 3,823,201). PHD polyols (US Pat. No. 4,093,569 and GB-A 1,501,172) are prepared by the polyaddition reaction of hydrazines or amines with mono- , Dioder polyisocyanates prepared in polyols and PIPA polyols ("JPIP A-Process for the Future", K. Picken, Urethanes Technology, 1984, pp 23-24, GB-A 2,072,204) by the polyaddition of Polyisocyanates and alkanolamines (compounds having at least one hydroxyl group and at least one primary, secondary or tertiary amino group) in polyether polyols In all three cases, the polyether polyol is nearly inert, but the reaction of a small proportion of the polyol with the filler stabilizes the dispersion.

Highly elastic foams are not only more elastic than standard foams but show better fire properties. One goal of the soft foam manufacturers is the continuous improvement of the fire properties of the foams. Different fire tests are used for different end applications and in different countries. Typical examples are "Califonia 117A", "California 117D", "Motor Vehicle Safety System 302" and "3ritish Standard 5852 part 2, Crib V". In particular, the latter test can usually only be achieved by using a relatively high proportion of expensive flame retardants.

Although many PIPA polyols and their foams are known, other PIPA polyols are still being developed to enhance certain properties of the polyols and their foams.

The stability and / or viscosity of PIPA polyols is often problematic. In EP-A 129 977 good PIPA polyols are obtained when a dispersant is used in the preparation. Without the dispersant, the products are coarse, high viscosity or solid pastes. One goal of many developments is to increase the solids content to improve the properties of the foams made with the PIPA polyol and to reduce the amount of PIPA polyol to be transported. When increasing the filler content, an unacceptable increase in viscosity must be avoided. In EP-A 79 115 PIPA polyols are described with 40-80 wt.% Filler. A portion of the isocyanate is retained and added at a later stage. When a polyol is prepared with 50% filler (Example 3), the ratio of triethanolamine to TDI is very important: with 26.55 parts to 23.45 parts, a product is obtained which can be diluted to a filler content of 10% while with 23.08 parts to 26.92 parts a viscous, lumpy product is obtained which, when diluted to a filler content of 10%, forms aggregates.

In US Pat. No. 4,523,025 a polyamine is reacted with alkylene oxide in the first step and the product from this reaction is reacted with a polyisocyanate in the presence of a polyol. If the polyamine does not first react with the alkylene oxide, the reaction mixture gels too fast, the solids settle or the foams are of poorer quality. The disadvantage of this method is that an additional reaction step is necessary.

In WO 94/12553, in the preparation of PIPA polyols having a filler content of 25-70%, viscosity reduction and post-production viscosity stabilization (ie, little or no increase in viscosity over time) is achieved by a second olamine is added to the reaction mixture of isocyanate and olamine in a second mixing head. Without the addition of the second olamine, the product gels. In US Pat. No. 5,179,131, the stabilization of the viscosity is achieved by the addition of 0.05 to 0.5 parts by weight of a mono- or di-carboxylic acid.

In WO 94/20558 the viscosity and stability of the PIPA dispersions are improved by the use of a stabilizer. The stabilizer itself is again a PIPA polyol. In this way, PIPA polyols having a filler content of 30% by weight could be prepared in which the filler does not settle over time.

In WO 00/73364 it is described that the stability (and viscosity) of PBPA-polyols containing 30 - 80% filler to a high shear intensity can be improved by the preparation at 60 to 100 ⁰ C and in use.

DE-A 198 11 471 describes a process for the preparation of stable dispersions. This is achieved by the addition of a monofunctional amine (such as di-N-butylamine). The comparative examples without di-N-butylamine could either not be processed as a flexible foam polyol or led to a very non-uniform foam structure. In US-A 4,293,470 is by the Addition of 0.1-1.0 wt.% Of a secondary amine such as dibutylamine avoided a change in the viscosity of the filled polyol and thus achieved an improved storage stability. '

The use of water in the production of PPA or PHD polyols for the reduction of

Viscosity is known. According to US Pat. No. 4,093,569, more than 4% by weight (particularly preferably 10 to 25% by weight) of water is used. The disadvantage, however, is that the high water content must be removed before foaming. Other prior art documents therefore teach using lower levels of water. In US-A 4,497,913 about 0.1 to 0.5 wt .-% are

Water in the production of a filled polyol from a short-chain polyol and a polyisocyanate added. WO 2004/099281 describes the preparation of PIPA polyols having filler contents of 1-80% by weight from a short-chain polyol and an MDI-based isocyanate in the presence of 0.1-5% by weight of water ,

As described in WO 00/73364, many of the processes for preparing PIPA polyols result in products having a high viscosity, unstable products, or produce PP A polyols in an uncontrollable reaction that can cause foam collapse.

PD known from the prior art? A-polyols tend to inhomogeneity (clumping or agglomeration) or instability (phase separation or viscosity change) and are therefore not suitable for the production of foams.

The object of the present invention is to provide PIP A polyols having improved homogeneity. It has now been found that an improvement in the homogeneity can be achieved by adding urea in the production of polyol.

It is another object of the present invention to provide PIP A polyols which can be used to make flexible polyurethane foams wherein the flexible foams have improved fire behavior in terms of mass loss and burn time according to the British Standard 5822 part 2, Crib V fire test than conventional PIP A-polyols.

The invention relates to a process for the preparation of polyisocyanate polyaddition polyols (PIPA polyols) in which polyisocyanates are reacted with amines or alkanolamines or mixtures thereof in a polyether polyol in the presence of urea and water.

Toluene diisocyanate (TDI) is preferably used as the polyisocyanate in the process according to the invention, more preferably in the form of an isomer mixture containing 80% by weight of 2,4-TDI

(, TDI 80 '). In another embodiment, the polyisocyanate is diphenylmethane diisocyanate (MDI) used in the form of monomeric MDI, mixtures of MDI and its higher homologues Ho _¬ (polymeric MDI ") or mixtures thereof.

In the process according to the invention, it is possible to use mono-, di- or trifunctional amines having primary, secondary or tertiary amino groups, preferably primary or secondary amino groups. Aliphatic, cycloaliphatic or aromatic amines can be used. Examples of suitable amines are N-methyl-1,3-propanediamine, phenylhydrazine, 1,12-diamino-4,9-dioxadecane, 1,2-propylenediamine and 1,3-propylenediamine, α-aminodiphenylmethane, N, N triamine dibenzylethylenediamine, amino-terminated polyols (such as Jeffamine ^® from. Huntsman ICI), N, N-bis (3-aminopropyl) methylamine, cyclohexylamine, 3-dimethylamino-l-propylamine, diethylene, aminoethylpiperazine. Preferred amines are l, 12-diamino-4,9-dioxadecane, 1,2 diamine, -Propy-, α-aminodiphenylmethane, N, N-dibenzylethylenediamine, difunctional polyoxypropylene lenamin having a number average molecular weight of 230 g / mol (Jeffamine ^® D230), 3-dimethylamino-1-propylamine, diethylenetriamine.

Suitable alkanolamines for the process according to the invention are diethanolamine (DEOA), 3-amino-1-propanol, aminoethylethanolamine, aminoethanol and aminoethoxyethanol. Diethanolamine, 3-amino-1-propanol or aminoethylethanolamine are preferred. Particular preference is given to using combinations of diethanolamine with other amines or alkanolamines. The mixing ratio DEOA to further amines or alkanolamines is preferably 0.5: 1 to 5: 1. The NH number of the mixtures is typically 400 to 700. The different reactivities of primary and secondary NH groups are not taken into account here. It is assumed for the formulation calculation that the OH groups in alkanolamines do not react.

Suitable polyether polyols for the process according to the invention generally have an OH number of 28 to 56, an OH functionality of 2 to 4 and an ethylene oxide content of 15 to 20% by weight.

In the method according to the invention, an aqueous urea solution is co-used. The weight ratio of urea to water is generally 1: 1. The solubility of urea in water at 2O ⁰ C is 1080 g / l, so that significantly concentrated solutions are not possible. A total of 0.5 to 5 parts by weight, preferably 1 to 2 parts by weight, based on the total formulation, of the aqueous urea solution with used. A more dilute solution can also lead to homogeneous dispersions. In this case, the quantities must be adjusted accordingly. However, very dilute solutions are not of interest if their use means that the PIPA polyols made therewith would contain more than about 3 parts water, typically 3 parts of water are used in foaming and one additional step (distillation to remove excess water) is not desired.

Optionally, 0.1 to 2.0 parts by weight, based on the total formulation, of an antioxidant can be added.

In the process according to the invention, polyisocyanate and amines or alkanolamines are used in such a ratio that the ratio of the isocyanate groups to the isocyanate-reactive NH or NH ₂ groups is 0.90 to 1.1, preferably 0.95 to 1.05, particularly preferred 1: 1. The PIPA polyols prepared by the process according to the invention have filler contents of from 1 to 50% by weight, preferably from 10 to 20% by weight.

The erfmdungsgemäße process can be carried out by first polyether polyol, amines or alkanolamines, water and urea are mixed and then the polyisocyanate is added. Alternatively, all components can be mixed simultaneously in a mixing head. The process according to the invention is generally carried out at room temperature.

The PIPA polyols prepared by the process according to the invention are notable for their particular homogeneity and can therefore be further processed advantageously into flexible polyurethane foams.

It is believed that urea chemically participates in the reaction in such a way as to stabilize the dispersion. As described in WO 94/20558, a polymer usable for polyurethane flexible foams must be a stable dispersion of discrete polymer particles in a base polyether. The filled polyol must also show good processing properties: The viscosity must be within an acceptable range, so that the filled polyol can be processed in conventional foam systems. Ideally, this filled polyol should also result in a foam with good cell opening: ie not too much cell opening, otherwise foam collapse occurs and not too little cell opening to avoid shrinkage or poor quality of the resulting foam. Examples

Unless otherwise stated, in the tables parts always parts by weight and percentages by weight. The viscosities of the PIPA polyols were measured with a rotary viscometer "Rheostress RS75" from Haake at a shear rate of 50 / s at 25 ° C. To determine the hydroxyl number (OH), a sample of the polyol in pyridine was added The excess acetic anhydride was saponified with water and the resulting acetic acid was titrated with sodium hydroxide solution The total base content was measured by potentiometric titration: the basic constituents of a sample dissolved in acetic acid titrated potentiometrically with perchloric acid.

The following products are used in the examples:

Polyether A: trifunctional polyether polyol of OHZ 35 with an EO content of 17.5 wt .-%.

DEOA Diethanolamine

Desmodur ^® T80: mixture of 2,4- and 2,6-TDI (80:20), having an NCO content of 48

Wt .-%.

Irganox ^® 1135: antioxidant (Ciba Specialty Chemicals)

Irganox ^® 68b: antioxidant (Ciba Specialty Chemicals)

Jeffamine ^® D230: Polyoxypropylenamine, MW = 230 (Huntsman ICI).

Tegostab ^® B8681: polysiloxane-polyether-based foam stabilizer (Goldschmidt AG).

Niax ^® Al: bis (2-dimethylamino) ethyl ether in dipropylene glycol

(GE Specialty Chemicals).

Dabco ^® 33-LV: 33% triethylenediamine, 67% dipropylene glycol (Air Products).

Desmorapid ^® SO: tin 2-ethylhexanoate (Rhein Chemie)

Levagard PP: tris (2-chloroisopropyl) phosphate (Rhein Chemie). Method for Examples 1-9

Polyether A, the amines and / or alkanolamines and an aqueous urea solution (50 wt .-%) were placed in a mixing cup at room temperature. With a Pendraulik stirrer was stirred at -2400 U / min for two minutes. Desmodur ^® T80 was added in one portion and stirred at -2400 U / min for another 2 minutes. Due to the exothermic nature of the reaction, the mixture warmed significantly. Once the dispersion was cooled to about 6O ⁰ C, was added Irganox ^® 1135th

All PEPA dispersions 1 - 9 were homogeneous and had viscosities between 1800 and 4500 mPa · s (at 25 ^° C.). In Comparative Examples la-9a, PIPA production was carried out without urea: Instead of the aqueous urea solution, only water was used. Only in the case of ^" 6a was a homogeneous PEPA dispersion obtained.

Process for Comparative Examples Ia - 9a

Polyether A, the amines and / or alkanolamines and water were placed in a mixing cup at room temperature. With a Pendraulik stirrer was stirred at ~ 2400 U / min for two minutes. Desmodur ^® T80 was added in one portion and stirred at ~ 2400 U / min for another 2 minutes. Due to the exothermic nature of the reaction, the mixture warmed significantly. Once the dispersion was cooled to about 6O ⁰ C, was added Irganox ^® 1135th

In Comparative Examples 1b-9b, PIPA production was performed without urea and without water. All polyols were inhomogeneous.

Method for Comparative Examples Ib - 9Current Date 05.07.2006 10:00 b

Polyether A and the amines and / or alkanolamines were initially charged in a mixing cup at room temperature. With a Pendraulik stirrer was stirred at ~ 2400 U / min for two minutes. Desmodur ^® T80 was added in one portion and stirred at ~ 2400 U / min for another 2 minutes. Due to the exothermic nature of the reaction, the mixture warmed significantly. Once the dispersion was cooled to about 6O ⁰ C, was added Irganox ^® 1135th

The homogeneous PIPA dispersions 1-9 and 6a were used for the production of flexible foams (Examples 10-19):

Examples 10-19

100 parts of the PIPA polyol dispersions were stirred with water, Tegostab ^® B8681, DEOA, Niax ^® Al and Dabco 33-LV ^® for 20 s. After addition of Desmorapid SO ^®, the mixture was stirred for a further 10 s. Subsequently Desmodur ^® T80 was added and stirred for 8 to 13 s (depending on the start time). The reaction mixture was poured into a mold. The foam was after the end of the

Rising time 20 minutes at 100-120 ⁰ C baked.

The start time is the period from the beginning of the last mixing operation to a visually perceptible change or a significant increase in the volume of the reaction mixture.

The rise time is the time between start of mixing and maximum vertical foam expansion. The bulk density is determined by determining the volume and mass of a test specimen.

The flow resistance (open-cell density) is determined by passing air through the test specimen and measuring the resistance of this air flow using a water column on a scale of 0 to 350 mm. The apparatus used for this purpose consists of a glass cylinder provided with a millimeter graduation of 0 to 350, whose inner diameter is 36 mm, and an inner tube of 7 mm clear width. This inner tube ends at the top in a T-piece, to which the air supply is connected on one side and the hose with the measuring head on the other side. The hose for the measuring head has an inner diameter of 12 mm and a length of 1.80 m. The glass cylinder is closed at the bottom and can be filled with water via the funnel at the rear. The tester is connected to a compressed air source via two taps, a pressure reducer and a hose of any length and diameter, with the pressure reducer set to approximately 2.0 bar. The glass container is filled with distilled water until the lower meniscus edge reaches the H ₂ O-hour mark. Then cock 1 is turned on and the flow rate on the cock 2 changed until the lower meniscus edge of the inner column reaches the 0 mm mark and thus a pre-pressure of 100 mm water column is set. After setting the pre-pressure, the measuring head is placed on the sample without pressure and the height of the water column in the inner tube is read off. This is equal to the flow resistance of the sample.

Dispersions 1-9 made with the aqueous urea solution resulted in acceptable flexible foams. Dispersion 6a, prepared without urea, resulted in an unacceptable high shrink foam. This shows that the use of an aqueous urea solution in the preparation of the PIPA polyol not only leads to an improvement in the polyol homogeneity, but can also have a positive influence on the foaming.

Comparative Examples 20-21

In Comparative Examples 20 and 21, the filled polyol was prepared with the catalyst dibutyltin dilaurate and without aqueous urea solution. Example 20 is directly comparable to Example 9. The polyols used in Examples 20 and 9 are both homogeneous, but that

Polyol in Example 20 results in foam collapse. Example 21 also used a polyol with dibutyl tylzinndilaurat prepared as a catalyst. However, the corresponding filled polyol was not homogeneous.

Examples 22 and 24 and Comparative Examples 23 and 25

Example 22 is a 10% PIPA prepared as in Example 9 except that in this case the PEPA polyol is made via a low pressure mixing head with a mechanical stirrer. In Comparative Example 23, a standard PIPA based on TEOA and with dibutyltin dilaurate catalysis was also prepared via a low-pressure mixing head with a mechanical stirrer. Both attempts resulted in stable PIPA polyols, which were foamed in Example 24 and Comparative Example 25 on a UBT unit. Although both products pass the Crib V fire test (mass loss <60g and firing time <10min), the mass loss and burn through time of the foams containing the PIPA polyols of the invention are lower in Example 24 than in Comparative Example 25. This shows that the Fire properties can be improved by optimizing the polyol combinations.

* Double determination

Claims

claims

A process for the preparation of polyisocyanate polyaddition polyols (PIPA polyols) in which polyisocyanates are reacted with amines or alkanolamines in a polyether polyol in the presence of urea and water.

2. The method according to claim 1, wherein the polyisocyanate used is a mixture of isomers of toluene diisocyanate (TDI) containing 80 wt .-% 2,4-TDI.

3. The method according to claim 1 or 2, are used in the alkanolamine as diethanolamine, 3-amino-l-propanol or aminoethyl ethanolamine.

4. The method according to any one of claims 1 to 3, are used in the mixtures of diethanolamine with amines or alkanolamines.

5. PIPA polyols obtainable by a process according to any one of claims 1 to 4.

6. Use of PEPA polyols according to claim 5 for the production of flexible polyurethane foams.