WO1997029141A1

WO1997029141A1 - Polyurethane materials

Info

Publication number: WO1997029141A1
Application number: PCT/EP1997/000363
Authority: WO
Inventors: Roland Grützmacher; Bernd Beuer; Andreas Heidbreder; Peter Döbrich
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1996-02-06
Filing date: 1997-01-28
Publication date: 1997-08-14
Also published as: DE19604177A1; JP2000504750A; EP0879254A1

Abstract

Ester polyhydric alcohols which are stable in storage and can be obtained by (a) reaction of polyfunctional alcohols with 0.5 to 60 mol of ethylene oxide (EO) and/or propylene oxide (PO) per mol of alcohol and (b) transesterification of resulting polyhydric alcohols with 0.1 to 30 mol of triglycerides per mol of alkoxylated alcohol, wherein at least one of the fatty acid resid ues per triglyceride molecule carries at least one OH group, but the mixture on average has at least 1.5 OH groups per molecule. The invention relates to the use of said ester polyhydric alcohols for the preparation of polyurethane materials.

Description

"Polyurethane materials"

Field of the Invention

The invention relates to the production of polyurethane materials from storage-stable polyols and isocyanates. The polyurethane materials according to the invention cure without bubbles even in a moist environment and have high mechanical strength. Another advantage of the materials according to the invention is that the components required for production are stable in storage.

State of the art

The use of castor oil and / or other triglycerides bearing hydroxyl groups for the production of polyurethanes has long been known. For example, in Saunders, Frisch; Polyurethanes: Chemistry and Technology, D Technology, Interscience (1964) describes the production of elastomers from castor oil and corresponding isocyanates. However, the polyurethane compositions obtainable in this way do not have the desired material properties as are required for more demanding applications. For example, only low tear propagation strength, tensile elongation and tensile and shear strength are measured with the material not being sufficiently hard. The attempt to extend the short gel time or pot life of the batches in order to enable easy processing is also unsuccessful. The inadequate material properties were generally taken into account by using castor oil mixed with polyether polyols as the polyol component. Although this process led to improved material properties in the polyurethanes formed after the reaction with isocyanates, at the same time the hydrophilicity of the polyol component was increased to such an extent that the materials released large amounts of CO ₂ in a moist environment due to the reaction of the isocyanates with water, and thereby in particular There was a lot of blistering on the surface.

DE-OS 36 30 264 describes, for example, how the mechanical properties of polyurethanes from ring-opened, oleochemical polyols can be improved by first reacting the hydroxyl groups on the fatty acid residues of the polyols with alkylene oxides such as ethylene oxide or propylene oxide. Casting resins can thus be obtained whose mechanical properties are superior to those produced from castor oil. The publication is silent about transesterification of the triglycerides with alkoxylated polyols.

US Pat. No. 3,424,766 teaches the production of so-called epoxidized urethane oils by first transesterifying epoxidized triglycerides with polyols having 2 to 6 hydroxyl groups in order to then convert them with polyisocyanates to give the epoxidized urethane oils. The publication also mentions that the alcohols suitable for transesterification can be alkoxylated. However, the publication does not indicate that triglycerides bearing hydroxyl groups, in particular castor oil, can also be transesterified with polyols and thus lead to improved polyurethane materials.

The unpublished patent application with the file number 195 29 406.8 describes the production of polyurethane prepolymers for use in one-component, moisture-curing foams or adhesives. Two-component (2-component) foams or casting resins are not mentioned. Although the transesterification of castor oil with low molecular weight polyols is mentioned here, the use of alkoxylated polyols for the transesterification is not disclosed. The oleochemical polyols are then immediately converted to polyurethane prepolymers. The attempt to store the polyols before the conversion to the polyurethane shows, surprisingly, that after a short time phase separation occurs which leads to the polyol being unusable. The use of the polyols in 2-component systems is therefore not possible

It was therefore the task of modifying oleochemical polyols in such a way that the polyol component on the one hand can be processed to give materials such as casting resins or two-component foams with the required mechanical properties, on the other hand, however, the polyols had to be stored for a longer period of time, as used in the same way in two components Systems is indispensable, allowed In particular, when curing in a damp environment, there should be little or no bubble formation due to reaction with water and the pot life should not be reduced

Surprisingly, it has now been found that the transesterification products of triglycerides bearing hydroxyl groups, in particular castor oil, with the alkoxylation products of polyfunctional, low molecular weight alcohols show no phase separation even after several months of storage. The reaction of such systems with isocyanates leads to polyurethane compositions with the desired mechanical properties and a low level Blistering due to reaction with water in a damp environment Unexpectedly, the gel time of the batches could be significantly increased compared to reference systems

Description of the invention

The invention therefore relates to the use of storage-stable ester polyols obtainable from

a) reaction of at least difunctional alcohols with 0.5 to 60 moles of ethylene oxide (EO) and / or propylene oxide (PO) per mole of alcohol and b) transesterification of the polyols obtainable in this way with 0.1-30 mol of triglycerides per mol of alkoxylated alcohol, at least one of the fatty acid residues per triglyceride molecule carrying at least one, but the mixture on average, at least 1.5 OH groups per molecule,

for the production of polyurethanes with extended gel times

Storage stability in the sense of the present invention relates to the period in which the polyol can be stored at rest without the performance properties being impaired. In this context, usage properties are understood to mean those properties which permit optimum handling of the polyol and after the reaction with Polyisocyanates lead to a material with at least approximately the same quality as before the storage of the polyol. If necessary, a storage stability of two weeks may be sufficient to achieve the desired purpose, but it will generally be advantageous to have longer storage stability, for example two to achieve or four months Ideally, the polyols according to the invention are stable over a period of at least twelve months

To produce the polyols, hydroxyl-bearing triglycerides are transesterified with polyols. The hydroxyl-bearing triglycerides can be of either natural or synthetic origin. For example, unsaturated triglycerides can be epoxidized by persic acids and the oxiranes thus obtainable in acid or alkali-catalyzed ring-opening reactions with mono- or polyhydric alcohols convert to triglycerides bearing hydroxyl groups. Unsaturated triglycerides of synthetic and / or natural origin come into consideration in an iodine number range from 30 to 150, preferably from 85 to 125

Typical examples of the group of unsaturated triglycerides are linseed oil, palmol, palm kernel oil, coconut oil, peanut oil, tea oil, olive oil, ohvenkernol, Babassuol, Meadowfoamol, Chaulmoograol, Koπanderol, soybean oil, lardol, beef tallow, pork lard, Fischol, and sunflower oil and dermal oil and dermal oil and dermal oil new breed The ring opening of such oxiranes is usually carried out with monofunctional or polyfunctional alcohols, but the use of monofunctional alcohols is preferred for the purposes of the invention. Both the aliphatic and aromatic alcohols pay for the monofunctional alcohols, preference being given to the use of aliphatic alcohols. The alcohols used can be branched or unbranched, saturated or unsaturated, but preference is given to using aliphatic, saturated alcohols, in particular methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol and the like higher homologues are used for ring opening.

If necessary, fatty alcohols with 8 to 22 carbon atoms can also be used to open the ring. Fatty alcohols are primary aliphatic alcohols of the formula (I)

I ^ OH (I)

in which R ^{1 represents} an aliphatic, linear or branched hydrocarbon radical having 6 to 22 carbon atoms and 0 and / or 1, 2 or 3 double bonds

Typical examples are capron alcohol, caprylic alcohol, 2-ethylhexyl alcohol, capric alcohol, lauryl alcohol, isotridecyl alcohol, myπstyl alcohol, cetyl alcohol, palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, linoleol, alcohol alcohol, linoleol alcohol, linoleol alcohol, linoleol alcohol and brassidyl alcohol and their technical mixtures, which are obtained, for example, in the high-pressure hydrogenation of technical methyl esters based on fats and oils or aldehydes from Roelen's oxosynthesis and as a monomer fraction in the dimerization of unsaturated fatty alcohols In addition to the hydroxy-functional triglycerides obtainable by ring opening, the natural triglycerides with an OH function on the fatty acid residue, such as castor oil, are used in a preferred embodiment of the invention.

For the transesterification of the triglycerides, the alkoxylation products of polyfunctional, aliphatic alcohols are used according to the teaching of the invention. The alcohols used for this generally have functionalities of 2 to 10, preferably 2 to 6. These include in particular diols, e.g. 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol or neopentyl glycol and polyols, such as e.g. Trimethylolpropane, glycerin, trimethylolethane, pentaerythritol, sorbitol and / or oligomeric glycerols. However, the use of alkoxylated alcohols having 2 or 3 OH groups, such as ethanediol, propanediol, glycerol, pentaerythritol, trimethylolpropane and / or trimethylolethane, is particularly preferred.

The alkoxylation can be carried out under conditions known per se with ethylene oxide (EO) and / or propylene oxide (PO), the use of PO or mixtures containing a predominant proportion of PO being preferred. Such mixtures should then contain more than 70, preferably more than 80 and particularly preferably more than 90% by weight of PO. Particularly good results are achieved with the exclusive use of PO for alkoxylation. The polyols used according to the invention generally consist predominantly of alcohols with alkylene oxides, usually in a ratio of 0.1 to 20 moles per mole of OH functionality, with amounts of 0.5 to 8 or 0.8 to 2 moles being preferred , have been alkoxylated. The use of the alkoxylation products of glycerol, in particular with about 3 mol PO, is particularly preferred according to the invention.

The alkoxylated polyols are then reacted with the triglycerides in a base-catalyzed transesterification reaction at temperatures between 120 and 250 ° C. Usually about 0.1 to 3 moles of the alkoxylated polyol are used for the transesterification per mole of triglyceride, but approximately equivalent amounts, for example 0.8 to 1.2 moles of the alkoxylated polyol, are preferred per mole of triglyceride. For the transesterification, the same catalysts are generally used as for the alkoxylation; in the optimal case, the catalyst used for the alkoxylation can also be used for the transesterification. The use of basic lithium compounds such as lithium hydroxide, lithium carbonate, lithium acetate, lithium alkoxylates or the lithium salts of higher fatty acids has proven particularly useful here. Lithium contents in particular of less than 100, preferably less than 70 and in particular less than 50 ppm have a positive effect on the storage stability of the polyols compared to higher or identical contents of other alkali metals. The use of particularly small amounts of catalyst has proven to be particularly advantageous in that the catalyst does not have to be removed from the polyol mixture and does not adversely affect the conversion to the polyurethane and its resulting material properties. The polyols which are most suitable for the purposes of the invention have no or only low contents, advantageously less than 1 ppm of alkali metals other than lithium, the lithium content advantageously being below 20 ppm.

In addition to these oleochemical polyols, the polyisocyanates are the second important building block for the polyurethane materials according to the invention.

Isocyanates react in a manner known to those skilled in the art with free hydroxyl groups in an addition reaction to form a urethane group. Suitable isocyanate components according to the invention are generally all customary, polyfunctional aromatic and aliphatic isocyanates, such as, for example, also all oligomeric and polymeric isocyanate compounds as can be prepared from the oligomerization or cyclization of polyisocyanates under the influence of moisture or by reaction of polyfunctional alcohols with polyisocyanates. The polyisocyanates can be used in excess and in deficit. examples for this are

Hexamethylene diisocyanate, HDI trimer (tris (6-isocyanatohexyl) isocyanurate) (Tolonate ^® HDT) (Rhone-Poulenc), 4,4-diphenylmethane diisocyanate (MDI) (Desmodur ^® VL) (Bayer), HDI-Biuret (l, 3, 5-tris (6-isocyanate-hexyl) biuret, hexamethylene diisocyanate biuret (Desmodur "N 75), (Bayer) and an aromatic polyisocyanate based on

Toluene diisocyanate (Desmodur L 67) (Bayer) The isocyanates can be used both in pure form and in technical mixtures with or without solvents

The reaction between polyols and isocyanates usually takes place in a temperature range between 0 and 100 ° C., preferably between 5 and 50 ° C. For processing, the components are usually first intensively mixed and then processed during the remaining pot life. The mixing of the components can be carried out either by the user himself by stirring, whirling or other measures suitable for mixing, but the mixing can also be carried out by an automatic device, for example when removed from a pressurized can with separate compartments for polyol and isocyanate, the resulting mixture can be further processed into coatings, casting resins, foams or composite materials

The invention thus also relates to polyurethanes with the property that storage-stable ester polyols are obtainable through

a) reaction of polyfunctional alcohols with 0.5 to 60 mol of ethylene oxide (EO) and / or propylene oxide (PO) and b) transesterification of the polyols thus obtainable with 0.1 to 30 mol of triglycerides, at least one of the fatty acid residues per triglyceride molecule being at least one one, but the mixture carries on average at least 1.5 OH groups per molecule,

were used to manufacture them

To produce polyurethane foams, at least one blowing agent and, if appropriate, a foam stabilizer are generally also necessary. In addition, other additives can be added, for example solvents, flame retardants, Plasticizers, cell regulators, emulsifiers, fungicides, fillers, pigments and anti-aging agents

1, 1,1,2-tetrafluoroethane, 1,1-difluoroethane and dimethyl ether are preferably used as blowing agents. However, carbon dioxide, nitrous oxide, n-propane, n-butane and isobutane can also be used as blowing agents and chlorine-free fluorocarbons are advantageously used with boiling points from -40 to + 60 ° C propane / butane mixtures and dimethyl ether or mixtures thereof

Furthermore, the foam-forming composition can additionally contain stabilizers. "Stabilizers" in the sense of this invention are, on the one hand, stabilizers which bring about a viscosity stability of the composition during production, storage or application. For this purpose, for example, monofunctional carboxylic acid chlorides, monofunctional highly reactive isocyanates, but also non- Corrosive inorganic acids are suitable. Benzoyl chloride, toluenesulfonyl isocyanate, phosphoric acid or phosphorous acid may be mentioned as examples

Furthermore, stabilizers for the purposes of this invention are antioxidants, UV stabilizers or hydrolysis stabilizers. The selection of these stabilizers depends, on the one hand, on the main components of the composition and, on the other hand, on the application conditions and the loads to be expected of the foam plastic. The main antioxidants are usually , if necessary in combination with UV protection agents. Examples of these are the commercially available sterically hindered phenols and / or thioethers and / or substituted benzotriazoles or the sterically hindered amines of the HALS type ("hindered amine light stabilizer")

Hydrolysis stabilizers, for example of the carbodhmide type, can optionally be used to stabilize the ester bonds

Another object of the invention is the use of the inventive. Polyurethanes in composite materials and / or blends, where blends are homogeneous, Micro- or also macro-separated mixtures with other plastics are to be understood. For this purpose, the polyurethanes in different mixture ratios with one or more additional components can be processed together to form a material with improved and / or new properties. In contrast to the fillers, which mainly have a cost-reducing function, The additives mentioned below assume a functional task in the material, which is mainly associated with an improvement in the physical material properties. For the production of composite materials, the polyurethanes according to the invention are processed, for example, with natural or synthetic fibers, fiber short cuts, fabrics or the like. Suitable materials are, for example, natural fibers such as silk, cotton, wool, jute, hemp, flax, sisal, straw or the like, but the secondary products of these fibers are just as suitable in their processed form m, for example as a fabric The fibers can be incorporated into the polyurethanes according to the invention both in untreated and in treated form. For example, sizes based on siloxane or polyester, as are known to those skilled in the art for such surface treatments, have proven to be suitable agents for surface treatment . In many cases, the resulting composite materials have excellent stability, tear resistance, abrasion resistance and toughness, as is required for many applications

In addition to natural fibers, synthetic fibers such as polyamide, polyester, polyether or carbon fibers, but also inorganic fibers such as glass fibers and glass fiber mats can also be incorporated

The invention thus also relates to composite materials which can be produced from the storage-stable polyols according to the invention

Claims

claims

1 Use of storage stable ester polyols, obtainable through

a) reaction of polyfunctional alcohol with 0.5 to 60 moles of ethylene oxide (EO) and / or propylene oxide (PO) per mole of alcohol and b) transesterification of the polyols thus obtainable with 0.1 to 30 moles of triglycerides per mole of alkoxylated alcohol, at least one of which Fatty acid residues per triglyceride molecule at least one, but the mixture carries on average at least 1.5 OH groups per molecule,

for the production of polyurethanes with extended gel times

2 Use according to claim 1, characterized in that polyfunctional alcohols with functionalities of 2 to 10, preferably 2 to 6 are used

3 Use according to one of claims 1 or 2, characterized in that polyfunctional alcohols which have been alkoxylated with 0.1, 10, preferably 0.5 to 8 mol of EO and / or PO are used

4. Use according to one of claims 1 to 3, characterized in that PO is used for the alkoxylation

5 Use according to one of claims 1 to 4, characterized in that glycerol is used as the polyfunctional alcohol

6 Use according to one of claims 1 to 5, characterized in that alkoxylated polyols which have been transesterified with 0.1 to 3, preferably 0.8 to 1.2 mol of castor oil are used as ester polyols Use according to one of claims 1 to 6, characterized in that polyols whose alkali metal contents are less than 1 ppm, with the exception of lithium, are used

Use of the polyurethanes according to one of claims 1 to 7 for the production of composite materials.

Polyurethanes, characterized in that storage-stable ester polyols according to claim 1 and polyisocyanates were used for their preparation

Composite materials, characterized in that storage-stable ester polyols according to claim 1 and polyisocyanates were used for their production