DE19604177A1 - Polyurethane materials - Google Patents

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

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 also harden in damp environment without bubbles and have a high mechanical strength. Another advantage of the materials according to the invention is that the for Manufacturing required components are stable in storage.

State of the art

The use of castor oil and / or other hydroxyl groups Triglycerides for the production of polyurethanes have been known for a long time. So will for example in Saunders, Frisch; Polyurethanes: Chemistry and Technology, II Technology, Interscience (1964) the production of elastomers from castor oil and corresponding isocyanates described. The available polyurethane masses but not about the desired material properties as they are for more demanding ones Applications are required. For example, only low tear resistance,  Tensile elongation as well as tensile and shear strength with usually insufficient hardness of the Material measured. The attempt to reduce the short gel time or Extend the pot life of the approaches to enable easy processing.

As a rule, the insufficient material properties were taken into account worn that castor oil in admixture with polyether polyols as a polyol component for Use came. This process did lead to improved material properties the polyurethanes formed after the reaction with isocyanates however, the hydrophilicity of the polyol component also increased to such an extent that the materials in humid environment by the reaction of the isocyanates with water high amounts of CO₂ release and there was a strong blistering especially 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 the hydroxyl groups on the fatty acid residues of the polyols first with alkylene oxides such as for example ethylene oxide or propylene oxide. This is how casting resins can be obtained, whose mechanical properties are superior to those made from castor oil are. The is silent about a transesterification of the triglycerides with alkoxylated polyols Publication.

US-A 3,424,766 teaches the production of so-called epoxidized urethane oils by first transesterified epoxidized triglycerides with polyols with 2 to 6 hydroxyl groups are then used with polyisocyanates to form the epoxidized urethane oils to implement. The document also mentions that the transesterification in question upcoming alcohols can be alkoxylated. The publication does not, however recognize that triglycerides bearing hydroxyl groups, in particular castor oil, with Polyols can be transesterified and so to improved polyurethane materials to lead.

The unpublished patent application with the file number 195 29 406.8 describes the Manufacture of polyurethane prepolymers for use in one-component,  moisture-curing foams or adhesives. Two-component (2K) foams or casting resins are not mentioned. Here, the transesterification of castor oil is included low molecular weight polyols, the use of alkoxylated polyols for However, transesterification is not disclosed. The oleochemical polyols are then immediately converted to polyurethane prepolymers. Trying to get the polyols before Storage of the reaction to the polyurethane surprisingly shows that after a short time phase separation occurs which leads to the uselessness of the polyol. The usage the polyols in 2K systems is therefore not possible.

The task was therefore to modify oleochemical polyols so that the Polyol component on the one hand to materials such as casting resins or 2-component foams can be processed with the required mechanical properties, on the other hand, however, a longer storage of the polyols as used in the same Two-component systems are essential, allowed. In particular, when curing in damp environment no or only slight blistering due to reaction with water occur and the pot life is not reduced.

Surprisingly, it has now been found that the transesterification products of Triglycerides bearing hydroxyl groups, in particular of castor oil, with the Alkoxylation products of polyfunctional, low molecular weight alcohols, also after show no phase separation for several months of storage. The implementation of such Systems with isocyanates leads to polyurethane masses with the desired mechanical Properties and low bubble formation due to reaction with water in moist Surroundings. The gel time of the batches could unexpectedly be compared to Reference systems can be increased significantly.

Description of the invention

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

• 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 thus obtainable with 0.1-30 mol of triglycerides per Moles of alkoxylated alcohol, with at least one of the fatty acid residues per Triglyceride molecule at least one, but the mixture on average per Molecule carries at least 1.5 OH groups,

for the production of polyurethanes with extended gel times.

Storage stability in the sense of the present invention refers to the period in which the polyol can be stored at rest without the performance properties be affected. In this context, use properties are considered understood those properties that allow optimal handling of the polyol and after the reaction with polyisocyanates to a material with at least lead to approximately the same quality as before the polyol was stored. Possibly A storage stability of two weeks can be sufficient to achieve the desired purpose However, it will usually be advantageous to have longer storage stabilities for example, two or four months. Ideally they are Polyols according to the invention are stable over a period of at least twelve months.

To produce the polyols, hydroxyl-bearing triglycerides with polyols transesterified. The triglycerides bearing hydroxyl groups can be both natural and also be of synthetic origin. For example, unsaturated triglycerides epoxidize with peracids and the oxiranes thus obtainable in acid or alkaline catalyzed ring opening reactions with mono- or polyhydric alcohols Implement triglycerides bearing hydroxyl groups. Coming as unsaturated triglycerides those of synthetic and / or natural origin 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, palm oil, Palm kernel oil, coconut oil, peanut oil, tea oil, olive oil, olive kernel oil, babassu oil, Meadowfoam oil, Chaulmoogra oil, coriander oil, soybean oil, Lard oil, beef tallow, Lard, fish oil, as well as sunflower oil and rapeseed oil from the old and new Breeding.

The ring opening of such oxiranes is usually mono- or polyfunctional Alcohols made, but the use according to the invention monofunctional alcohols preferred. Monofunctional alcohols include both the aliphatic and aromatic alcohols, the use aliphatic alcohols is preferred. The alcohols used can be branched or be unbranched, saturated or unsaturated, but use is preferred aliphatic, saturated alcohols. In particular methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, tert-butanol, pentanol, hexanol, heptanol and the 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 be used. Fatty alcohols include primary aliphatic alcohols of the formula (I) to understand,

R1 OH (I)

in R¹ for an aliphatic, linear or branched hydrocarbon radical with 6 up to 22 carbon atoms and 0 and / or 1, 2 or 3 double bonds.

Typical examples are capronic alcohol, caprylic alcohol, 2-ethylhexyl alcohol, caprinalko hol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, palmoleyl alcohol, Stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, Li nolyl alcohol, linolenyl alcohol, elaeostearyl alcohol, arachidyl alcohol, gadoleyl alcohol, Behenyl alcohol, eruca alcohol and brassidyl alcohol and their technical mixtures, the z. B. in the high-pressure hydrogenation of technical methyl esters based on fats  and oils or aldehydes from Roelen's oxo synthesis and as a monomer fraction arise in the dimerization of unsaturated fatty alcohols.

In addition to the hydroxy-functional triglycerides available through ring opening, in a preferred embodiment of the invention, the natural, with an OH function triglycerides equipped with fatty acid residues, such as castor oil, are used.

To transesterify the triglycerides according to the teaching of the invention Alkoxylation products used polyfunctional, aliphatic alcohols. The for this Alcohols used generally have functionalities of 2 to 10, preferably from 2 to 6. These include in particular diols, such as. B. 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol or neopentyl glycol and polyols, such as. B. Trimethylolpropane, glycerin, trimethylolethane, pentaerythritol, sorbitol and / or oligomeric Glycerine. However, the use of alkoxylated alcohols is particularly preferred 2 or 3 OH groups such as ethanediol, propanediol, glycerol, pentaerythritol, Trimethylolpropane and / or trimethylolethane.

The alkoxylation can be carried out under known conditions with ethylene oxide (EO) and / or propylene oxide (PO), the use of PO or predominantly Proportion of PO-containing mixtures is preferred. Such mixtures should then be more than Contain 70, preferably more than 80 and particularly preferably more than 90 wt .-% PO. Particularly good results can be achieved with the exclusive use of PO for alk oxylation. The polyols used according to the invention generally exist predominantly from 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 are preferred, have been alkoxylated. Especially the use of the Alkoxylation products of glycerol, especially with about 3 moles PO preferred according to the invention.

The alkoxylated polyols then become basic with the triglycerides catalyzed transesterification reaction at temperatures between 120 and 250 ° C.  

Usually about 0.1 to 3 moles of the alkoxylated polyol are used per mole of triglyceride used for the transesterification, but approximately equivalent amounts, such as 0.8 up to 1.2 moles of the alkoxylated polyol per mole of triglyceride are preferred.

The same catalysts are generally used for the transesterification as for the alkoxylation used, in the optimal case, the catalyst used in the alkoxylation can also can still be used for 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 have been proven. Especially Lithium contents of less than 100, preferably less than 70 and in particular less than 50 ppm affect the storage stability of the polyols compared to higher or identical contents of other alkali metals positive. Has proven to be particularly advantageous the use of particularly small amounts of catalyst in that the Catalyst does not have to be removed from the polyol mixture and the conversion to Polyurethane and its resulting material properties are not adversely affected. The Most suitable polyols in the sense of the invention have no or only minor Contain, advantageously less than 1 ppm of alkali metals other than lithium, where the lithium content should advantageously be 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 with free hydroxyl groups in a manner known to those skilled in the art in an addition reaction to form a urethane group. As Isocyanate components according to the invention are generally all the usual suitable polyfunctional aromatic and aliphatic isocyanates, such as also all oligomeric and polymeric isocyanate compounds, such as those from the Oligomerization or cyclization of polyisocyanates under the influence of moisture or can be prepared by reacting 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 (1,3,5-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 Form as well as in technical mixtures with or without solvents.

The reaction between polyols and isocyanates usually takes place in one Temperature range between 0 and 100 ° C, preferably between 5 and 50 ° C instead. For Processing, the components are usually first intensively mixed and then processed during the remaining pot life. Mixing the components can either by the user himself by stirring, whirling or other for Mixing suitable measure take place, but the mixing can also by a automatic device, such as when removing from a pressurized standing can with separate compartments for polyol and isocyanate. That so The resulting mixture can become coatings, casting resins, foams or Composite materials are processed further.

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

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

were used to manufacture them.  

There is usually at least one for the production of polyurethane foams Blowing agent and possibly a foam stabilizer necessary. In addition, you can other additives are added, e.g. B. solvents, flame retardants, Plasticizers, cell regulators, emulsifiers, fungicides, fillers, pigments and old ones antifreeze.

1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and Dimethyl ether used. However, carbon dioxide, nitrous oxide, n-propane, n-butane and isobutane can be used. Serve as a blowing agent and solvent expediently chlorine-free fluorocarbons 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 to be understood on the one hand as stabilizers, the viscosity stability of the composition during manufacture, storage or effect application. For this, z. B. monofunctional carboxylic acid chlorides, monofunctional highly reactive isocyanates, but also non-corrosive inorganic acids suitable. Examples include benzoyl chloride, toluenesulfonyl isocyanate and phosphorus acid or phosphorous acid.

Furthermore, as stabilizers in the sense of this invention are antioxidants, UV stabilizers or to understand hydrolysis stabilizers. Choosing this On the one hand, stabilizers depend on the main components of the composition and on the other hand according to the application conditions and the expected ones Loads on the foam plastic. Usually antioxidants are mainly if necessary in combination with UV protection agents. examples for this 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").

To stabilize the ester bonds, hydrolysis stabilizers, e.g. B. of the carbodiimide type can be used.  

Another object of the invention is the use of the inventive Polyurethanes in composite materials and / or blends, where blends are homogeneous, to understand micro or macro separated mixtures with other plastics are. For this purpose, the polyurethanes can be mixed in different proportions one or more additional components together to form a material improved and / or new properties are processed. In contrast to the Fillers, which mainly have a cost-reducing function, take over the im The following addressed additives are functional, mainly with one Improvement of the physical material properties related task in the material.

The polyurethanes according to the invention are used to produce composite materials for example with natural or synthetic fibers, fiber short cuts, fabrics or the like processed together. Suitable materials are e.g. B. the natural Fibers such as silk, cotton, wool, jute, hemp flax, sisal, straw or the like, however, the secondary products of these fibers in their processed are also suitable Form, for example as a fabric. The fibers can be in both untreated and in treated form are incorporated into the polyurethanes of the invention. As Suitable finishes for surface treatment, for example, have been found on the sizes Siloxane-based or polyester-based, as those skilled in the art for such Surface treatments are known. The resulting composite materials have in many cases excellent stability, tear resistance, abrasion resistance and Toughness as required for many applications.

In addition to the natural fibers, fibers of a synthetic nature, such as for example Polyamide, polyester, polyether or carbon fibers but also inorganic fibers such as For example, glass fibers and glass fiber mats can be incorporated.

The invention therefore also relates to composite materials which result from the Have storage-stable polyols according to the invention prepared.

Claims (11)

1. Use of storage-stable ester polyols, obtainable from

• 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 the fatty acid residues per triglyceride molecule carrying at least one, but the mixture on average, carrying 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 containing 0.1 to 10, preferably 0.5 to 8 mol EO and / or PO alkoxylated were used. 4. Use according to one of claims 1 to 3, characterized in that for Alkoxylation PO is used. 5. Use according to one of claims 1 to 4, characterized in that as polyfunctional alcohol glycerin is used. 6. Use according to one of claims 1 to 5, characterized in that as an ester polyols alkoxylated polyols with 0.1 to 3, preferably 0.8 to 1.2 moles of castor oil were esterified.   7. Use according to one of claims 1 to 6, characterized in that polyols, whose alkali metal contents are less than 1 ppm, lithium of which is used is used. 8. Use of the polyurethanes according to one of claims 1 to 7 for the production of Composite materials. 9. Polyurethanes, characterized in that storage-stable ester polyols according to claim 1 and polyisocyanates were used to prepare them. 10. Composites, characterized in that storage-stable ester polyols according to An saying 1 and polyisocyanates were used for their preparation