HK1025331B - A process for preparing polyisocyanates containing iminooxadiazinedione groups - Google Patents

Description

Process for preparing polyisocyanates containing iminooxadiazinedione

Technical Field

The invention relates to a method for producing iminooxadiazinedione-containing trimerized isocyanates in the presence of a trimerization catalyst, namely a polyfluorinated quaternary phosphonium.

Background

Polyisocyanates containing iminooxadiazinedione (asymmetric trimers) are high-quality raw materials which can be used, for example, for the production of polyurethane lacquers and coatings (for example, DE-A19, 611, 849). In the known polyisocyanates containing isocyanurate (symmetric trimer), these polyisocyanates are present as auxiliary components.

Isocyanate oligomers having a significantly increased content of iminooxadiazinedione are the subject of DE-A19, 611, 849. Its advantages are described in this application, for example, as a raw material for the manufacture of polyurethane paints and coatings. For (di) isocyanate oligomers having at least three NCO groups, the iminooxadiazinedione-containing polyisocyanates have the lowest viscosity.

The preparation of iminooxadiazinedione-containing isocyanate trimers using polyfluoroammonium catalysts is described, for example, in DE-A19, 611, 849. When the process is shifted from laboratory to industrial scale, it is found that the proportion of asymmetric trimer in the trimer mixture is changed. In this application, the term "trimer mixture" refers to a general profile of symmetric trimers (isocyanurates) and asymmetric trimers (iminooxadiazinediones). Products prepared in this manner may also sometimes have high haze (greater than 1.5te (f) when measured with equipment manufactured by Hach).

Thermodynamic studies of the trimerization of 1, 6-hexamethylene diisocyanate with a polyfluoroammonium catalyst in a reaction calorimeter (see J.thermal anal.1983, 27, 215-228 for the protocol and principles of determination) show that in some experiments the evolution of heat with time is very different from the usual case. The heat generated after the addition of the catalyst generally increases and then decreases more or less, but steadily decreases to the heat of reaction, as a result of the deactivation of the catalyst in the reaction mixture, caused by thermal decomposition and reaction with traces of impurities in the isocyanate starting material.

In contrast, in many cases, the heat of reaction is initially released as rapidly as desired, after which the reaction subsides unusually rapidly and then begins anew. Surprisingly, some catalysts do not accelerate the reaction immediately after addition, but rather the reaction rate decreases for a short period of time after addition of the catalyst, and after the lowest rate of heat generation, there is no apparent external reason to accelerate again, as shown in example 2 and FIG. 1.

However, this phenomenon is not observed in all cases. It is also not dependent on the reaction temperature. If no informal changes in the heat of formation versus time curve are observed, the proportion of asymmetric trimer can reach the same height (i.e. more than 30 mole% in the trimer mixture) in laboratory experiments. If the abovementioned irregular variation in the heat-generating curve is observed, a product having a lower content of iminooxadiazinedione is obtained.

It is clear that the actual catalytically active form, which is formed only in an almost unpredictable manner during the reaction (caused by the addition of ammonium polyfluoride), will give rise to different products depending on the type of reaction (both formal and informal in the sense described above). This is a result of the action of oligomeric isocyanates or by-products present in these isocyanates.

This situation makes the specific, reproducible industrial manufacture of high-quality lacquer polyisocyanates with reproducible properties, such as viscosity, NCO content, dye index, haze etc., very difficult.

Disclosure of Invention

The object of the present invention is to provide a reproducible process which does not suffer from the myriad of situations described above, such that: 1) the reaction can be carried out in a predictable manner and is directly dependent on the amount of catalyst used. 2) The heat generated in the exothermic reaction is uniformly generated and can be uniformly discharged. 3) The desired product can be produced with a homogeneous composition and high quality.

This object is achieved by the process of the invention by trimerization of isocyanates with a polyfluorinated quaternary phosphonium.

The invention relates to a method for producing trimeric isocyanates, the trimer mixture containing at least 30 mol% iminooxadiazinedione (asymmetric trimer). The process of the invention is a process for the catalytic trimerization of a starting isocyanate selected from the group consisting of: a number average molecular weight of 140-600 and organic di-or polyisocyanates containing aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups.

R₄P⁺F^-n (HF) in which R represents identical or different aliphatic, aromatic and/or araliphatic C which may be branched₁-C₂₀The radicals, or two or more R radicals, may also form, together with one another and with the phosphorus atom, a saturated or unsaturated ring, and n is a value from 0.1 to 20.

Drawings

FIG. 1 is a graph of heat of formation versus time for a prior art trimerization reaction.

FIG. 2 is a graph of heat of formation versus time for the trimerization reaction of the present invention.

According to the invention, the term "trimer mixtures" includes isocyanates and iminooxadiazinediones.

It is preferred to provide a process in which an aliphatic diisocyanate having a molecular weight of 140-300 is used as the isocyanate component to be trimerized, either as a pure compound or as a mixture of these compounds. The trimer mixture of the product of the process preferably contains at least 35%, more preferably at least 40 mole% of iminooxadiazinedione (asymmetric trimer).

According to a preferred embodiment of the invention, the quaternary phosphonium polyfluoride trimerisation catalyst is used in admixture with an alcohol having a molecular weight of from 32 to 250 g/mole.

To carry out the process of the present invention, the trimerization catalyst may be of the formula R₄P⁺F^-n (HF) in the form of pure or mixed compounds, where R represents identical or different aliphatic, aromatic and/or araliphatic C which may be branched₁-C₂₀And (4) a base. The R group may be substituted. Examples of suitable catalysts include commercially available products which may be salts with counter ions other than the fluoride of the polyfluoride, which salts can be readily converted to the polyfluoride form, such as chloride, bromide, iodide and (hydro) sulfate.See, for example, Synthesis 1988, 12, 953-. Examples include tetrakis (hydroxymethyl) phosphonium chloride and sulfate; and tetraethyl, tetrabutyl, tetraoctyl, tetrahexadecyl, tributyl (tetradecyl), tributyl (hexadecyl) and trioctyl (octadecyl) phosphonium chloride, bromide or iodide.

Since the pure catalyst is in most cases a solid (see example 1), it is generally required to use a catalyst solvent for the trimerization of the isocyanates according to the invention. Examples of such solvents include straight and branched chain primary, secondary and tertiary alcohols of 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, such as methanol, ethanol, n-and isopropanol, 1-and 2-butanol, isobutanol and 2-ethylhexanol.

The concentration of the trimerization catalyst in its mixture with the above-mentioned alcohol is not less than 10% by weight.

Triphenyl (alkyl) derivatives may also be used, although they are less preferred due to their poor solubility in the above solvents, especially alcohols, compared to the pure aliphatic substituted catalysts (examples 1c and 3-15).

Although the use of polyfluorides is known from DE-A19, 611, 849, this reference does not disclose the advantage that polyisocyanates having a particularly high content of iminooxadiazinedione can be prepared using quaternary phosphonium polyfluorides and in this way the preparation is highly reproducible and the products formed are also haze-free under all preparation conditions.

All examples of DE-A19, 611, 849 relate to catalysis with polyfluorides based on quaternary ammonium salts, which leads to the disadvantages discussed above. And there is no discussion of the specific role played by the nature of the cations in the catalyst molecules.

Based on the teaching of DE-A19, 611, 849, it was surprising that the nature of the counterion of the polyfluoride anion (in this case: quaternary phosphonium) plays a decisive role in the repetition of the desired reaction and in the formation of high-quality products having a high iminooxadiazinedione content and homogeneity (e.g.low turbidity). DE-A3, 902, 078, DE-A3, 827, 596 and EP-A0, 315, 692 propose the use of fixed or unfixed polyfluorophosphonium prepared in situ for the trimerization of isocyanates (phase transfer catalysis, see Isr.J.chem.1985, 26, 222-.

In EP-A0, 315, 692 which introduces the concept of phase transfer catalysis, a potassium fluoride-catalyzed process for preparing isocyanurate-containing compounds is described. It is also stated that the simultaneous presence of a phosphonium compound "increases the efficiency of the reaction". But polyfluorides are not mentioned. Phosphonium salts are also not used in the examples. The specification relates to the trimerization of aromatic isocyanates (TDI, MDI). In both examples, the trimerization of isocyanates containing aliphatically bound NCO groups which form isocyanurate groups is illustrated only by the reaction of n-butyl isocyanate with potassium fluoride. In example 1 of EP-A0, 315, 692, potassium fluoride is used as the sole catalyst; in example 5, potassium fluoride was used in the presence of a quaternary ammonium salt (benzyltrimethylammonium chloride).

This method is not practical for industrial scale applications due to the following disadvantages:

1) high reaction temperatures (120 ℃) and relatively long reaction times (8 hours for example 1 and 4 hours for example 5 of EP-A0, 315, 692), and high catalyst concentrations.

2) After the reaction, the technical disadvantage of the solid potassium salt component is removed by filtration (example 1 of EP-A0, 315, 692) or washing with water (which is disadvantageous for the preparation of products containing free isocyanate groups, example 5 of EP-A0, 315, 69). And

3) due to the combination of phosphonium salt and potassium fluoride, fluoride ions (which are described as effective catalysts) are continuously "extracted" from the insoluble inorganic phase into the isocyanate-containing organic phase.

EP-A235,388 describes a process for the preparation of mixtures of isocyanate polycarboxylic acids/polycarboxylic anhydrides as by-products in the presence of a quaternary onium salt in the presence of alkali metal fluorides as catalysts. On page 2, however, column 2, lines 21 to 23 indicate that NCO groups have reacted with one another without formation of product. In contrast, the product (asymmetric and symmetric trimer) was indeed prepared according to the invention.

Apart from DE-A19, 611, 849, no prior publication describes the advantageous use of polyfluorides, i.e.adducts of HF-fluorides, for the modification of isocyanates. Furthermore, DE-A3, 902, 078 (page 3, lines 32 to 33, lines 60 to 61 and page 4, line 12) indicates that phosphonium fluorides are "less preferred" than the corresponding ammonium fluorides. It is also mentioned that the "iminooxadiazinedione content" is still of minor importance in the resulting product (page 4, lines 51 to 52). Examples 6 to 9 of DE-A3, 902, 078 describe iminooxadiazinedione and the proportional form of the two main products isocyanurate and oxadiazinetrione of the reaction, it being stated that the formation of iminooxadiazinedione in the trimerization reaction requires the presence of CO2 and this reaction is referred to as an undesirable side reaction.

It is not obvious from the foregoing prior art teachings that a fully dissolved quaternary polyfluorinated phosphonium in an organic medium is particularly advantageous for the highly reproducible preparation of haze-free isocyanate trimer resins, in which the content of iminooxadiazinedione is high.

It was particularly surprising to observe that, although they are very similar chemically, the use of the quaternary (poly) phosphonium fluorides according to the invention for the trimerization of isocyanates, in contrast to catalysis with quaternary ammonium polyfluorides, would, as determined thermodynamically, lead to a "conventional" course of reaction, i.e. an increase in heat followed by a decrease but a steady decrease in heat after addition of the catalyst in the expected manner, as a result of deactivation of the catalyst in the reaction mixture, for example, by reaction of the catalyst with traces of impurities in the starting isocyanate (example 3-1 and FIG. 2).

These effects are not due to the higher thermal stability of tetraorganophosphonium salts compared to the corresponding tetraorganophosphonium salts known in the literature (see, for example, Methoden der Organischen Chemie, "Houben-Weyl", 4 th edition, G.Thieme Verlag, Stuttgart, Vol.XII/1, p.47 and ibid., Vol.XI/2, p.633ff), as can be demonstrated by measurements of isocyanate trimerization at different temperatures. In the case of either the ammonium or phosphonium polyfluorides, the trimerization reaction is preferably carried out at a temperature at which no sign of decomposition is shown in the differential thermal analysis assay (DTA).

It is clear that the formation of the actually catalytically active form ("activated complex") from the procatalyst molecule and the isocyanate can be achieved quite well in the presence of an excess of the starting isocyanate, and in particular that better reproducibility is possible with the phosphonium catalysts of the present invention instead of the corresponding ammonium compounds.

The value of n in formula (I) is not critical; but for practical considerations and because of the unpleasant physiological properties of hydrogen fluoride, are based on the presence of fluoride (F)^-) Even if an excess is suitable for the preparation of polyisocyanates having a high iminooxadiazinedione content, it is not used in large excess. Based on the fluoride (F) present^-) Even with a 20-fold molar excess of hydrogen fluoride over the catalyst system, the resulting product is very desirable in terms of properties and has a high iminooxadiazinedione content (greater than 50 mol% in the trimer mixture, examples 3-11-3-13). However, stoichiometric amounts (n ═ 1) or less of HF than stoichiometric amounts (n ═ e.g. 0.5) based on the amount of fluoride ions are also entirely satisfactory, so n is preferably from 0.1 to 2.5.

The process of the invention is carried out at from 20 ℃ to 200 ℃, preferably from 30 ℃ to 120 ℃, more preferably from 40 ℃ to 100 ℃, the isocyanate groups of the starting isocyanates being reacted proportionally. Degree of reaction R_NCOIs 5% -60%, preferably 10% -40%, R_NCOIs the quotient of the difference between the NCO content of the starting isocyanate before trimerization and the NCO content of the reaction mixture after termination of the reaction, divided by the NCO content of the starting isocyanate before trimerization.

After deactivation of the catalyst, any unreacted monomers can be separated off by any known method, for example (thin-layer) distillation or extraction, and then recycled.

To achieve the required R_NCOThereafter, any method known in the art for terminating the trimerization reaction to form isocyanurate may be used in order to deactivate the catalyst. Examples include addition of a strong acid or acid derivative (e.g., benzoyl chloride, phosphorous acid or phosphoric acid and their esters, but not HF) in a molar amount less than, equal to or greater than the stoichiometric amount of fluoride (MW19) used, adsorption of bound catalyst followed by filtration removal, and thermal deactivation.

When the products of the invention are intended for use in polyurethane paints and coating compositions, excess starting (di) isocyanate, if low molecular weight "monomeric" (di) isocyanate, is preferably removed. The reformation of monomeric starting (di) isocyanates is advantageous in terms of excellent color index and color stability of the product and its high resistance to cleavage.

For the preparation of the trimer according to the invention, it is sufficient that the concentration of the catalyst (based on the weight of starting isocyanate and fluoride ion (MW 19)) is from 1ppm to 1%, preferably from 1ppm to 0.1%, more preferably from 1ppm to 0.05%.

According to a continuous embodiment of the process according to the invention, the oligomerization is carried out in a tubular reactor. Even when used as a highly concentrated solution or pure material, the product has a very low tendency to gel particles of the polyfluorophosphonium catalyst, which is advantageous for the process of the present invention.

The process of the invention can be carried out with dilution of the starting isocyanate or without addition of solvent. Suitable organic compounds include those which are inert to NCO, for example toluene, xylene, higher aromatics, esters, ethers, ketones, C₁₂-C₂₀Alkyl sulfonates and mixtures thereof.

Suitable starting isocyanates for the process according to the invention include di-or polyisocyanates having a number average molecular weight of 140-600 and containing aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups. The starting isocyanates can be used in pure form or as mixtures.Examples which may be mentioned include 1, 6-Hexamethylene Diisocyanate (HDI), 2-methylpentane-1, 5-diisocyanate (MPDI), 1, 3-bis (isocyanatomethyl) -cyclohexane (1, 3-H)₆-XDI), 3(4) -isocyanatomethyl-1-methylcyclohexyl isocyanate (IMCI), isophorone diisocyanate (IPDI), bis (isocyanatomethyl) Norbornane (NBDI), 4-isocyanatomethyl-1, 8-octane diisocyanate (triisocyanatononane, TIN), 1, 3-bis (isocyanatomethyl) benzene, 1, 3-bis (2-isocyanatopropyl-2) benzene and bis (4(2) -isocyanatocyclohexyl) methane (H)₁₂MDI, Desmodue W, available from Bayer AG). The process used for preparing the starting isocyanates, i.e.with or without phosgene, is unimportant. Preferred starting isocyanates are HDI, MPDI, 1, 3-H₆XDI, NBDI and mixtures of HDI and IPDI.

In some cases, for example in order to achieve the desired satisfactory properties of the product, it is advantageous to use mixtures of starting isocyanates in the process of the invention. For example, in (priming) lacquers for electric vehicles, based on linear aliphatic diisocyanates which may be branched, such as HDI, and cycloaliphatic diisocyanates, such as IPDI or H₁₂Polyisocyanate mixtures of MDI. These mixtures are usually prepared by mixing polyisocyanates prepared separately from the two starting diisocyanates. However, it may be advantageous to prepare them from mixtures of the corresponding monomer components by simultaneous mixed trimerization (EP-A0, 047, 452).

Many polyisocyanates based on the known cycloaliphatic diisocyanates are solid. They sometimes have a rather high melt viscosity, so that the separation of the monomers by means of current (thin-layer) distillation is rather difficult. For this reason, solvents or flow additives must be used during their processing, sometimes also in order to be able to carry out thin-layer distillation. If the loss of reactivity (resin yield) and NCO functionality during the preparation of these polyisocyanates is too great to be acceptable, the resulting solution of cycloaliphatic diisocyanate-based isocyanurate polyisocyanate is at a concentration of about 70% resin solids and has a readily processable dynamic viscosity of 1-10Pa.s (23 ℃).

In contrast, if mixtures of linear aliphatic isocyanates, such as HDI, and cycloaliphatic diisocyanates, such as IPDI, are trimerized by the process of the invention with at least partial formation of iminooxadiazinediones, products having flowability at room temperature (viscosity at 23 ℃ C. of less than 100Pa.s) are obtained. These products are more fluid in viscosity with the addition of solvent than products prepared by the prior art from the same isocyanate starting material and have the same NCO functionality and average molecular weight, as shown in example 4.

The products and product mixtures obtained by the process of the invention are therefore suitable starting materials for various applications, including the optional preparation of foams and also paints, coating compositions, adhesives and additives.

Before their use as the isocyanate component in polyurethane systems, the products of the present invention may be modified by reacting isocyanate groups to introduce urethane, urea, biuret and/or allophanate groups; or reacting some or all of the NCO groups with a reversible protecting agent to modify the products of the invention. Suitable protecting agents include phenols, lactams such as epsilon-caprolactam, oximes, di-and triazoles, amines such as dipropylamine and CH-acid compounds such as dialkyl malonates and acetoacetates.

The products prepared according to the invention, which may be in protected form, are particularly suitable for the preparation of water-dispersible or non-dispersible one-and two-component polyurethane coating compositions, since, compared with isocyanurate-polyisocyanates, their solution and melt viscosities are reduced and their appearance is identical or improved. The HDI-based products of the invention are therefore more resistant to flocculation or clouding than the corresponding products known to contain predominantly isocyanates, even if they are very diluted in the paint solvent. Moisture resistance (e.g., open-packed paint surface skinning or coating matte, also known as "gloss reduction," at high humidity and high ambient temperatures) is also improved compared to isocyanurate-containing products.

Detailed Description

The invention is further illustrated but is not limited by the following examples in which all parts and percentages are by weight unless otherwise indicated.

Examples

The mole percentages are determined by NMR spectroscopy and, unless otherwise indicated, are based on the sum of the NCO by-products formed by the modification reaction ("trimerization"). DPX400 manufactured by Bruker at 400MHz (¹H-NMR) or 100MNz (¹³C-NMR), under anhydrous CDCl₃About 5%, (¹H-NMR) or about 50% ((R)¹³C-NMR) samples were measured. In a selective solvent¹H chemical shift 0ppm (¹H-NMR) of 77.0ppm (¹³C-NMR) as a standard for determining ppm. Chemical shift data for the compounds in question are taken from the literature (see DieAngewandte Makromolekulare Chemie 1986, 141, 173-183 and the references cited therein) or are obtained by measuring the sample material. 3, 5-dimethyl-2-methylimino-4, 6-diketo-1, 3, 5-oxadiazine was prepared from methyl isocyanate according to the method described in Ber.d.dtsch.chem.ges.1927, 60, 295 using about 3% tri-n-butylphosphine as catalyst, in about 70% yield and its NMR chemical shift (ppm): 3.09; 3.08 and 2.84(¹H-NMR，CH₃) Or 148.3; 144.6 and 137.3(¹³C-NMR, C ═ O/C ═ N). The products of this process having the structure iminooxadiazinedione have a very similar structure to the C ═ O/C ═ N atom¹³C-NMR chemical shifts and can therefore be distinguished without any problem from other isocyanate by-products.

The dynamic viscosity was measured at 23 ℃ with a VT 550 viscometer manufactured by haak. The measurements were carried out at different shear rates in order to ensure that the flowability of the polyisocyanate mixtures according to the invention and of similar products corresponds to the flowability of the ideal Newtonian fluid. It is therefore not necessary to indicate the shear rate. The residual monomer amount was determined by gas chromatography.

The haze of the trimerized resin was measured using a device manufactured by Hach. For this purpose, scattered light was measured, and a light beam having a wavelength of 400-800nm was irradiated at an angle of 90 ° to the resin sample, and the measurement result was given in units of te (f) based on a formazan (formazine) standard solution.

Most of the reactions were carried out under nitrogen atmosphere with HDI as trimerizing isocyanate using a catalyst based on tetrabutylphosphonium hydrogen difluoride. These are merely illustrative of the advantages of the process of the present invention and do not limit the system or reaction conditions of the present invention. EXAMPLE 1 preparation of Polyquaternary phosphonium fluoride (stock solution)

The solution was prepared according to the method for preparing analogous ammonium compounds as provided in J.org.chem.1989, 54, 4827-4829. a) Bu in methanol/isopropanol₄P⁺F^-·nHF

Bu handle₄P⁺Cl^-A71.4% solution formed in isopropanol of 953.8g (Cyphos 443P, product manufactured by Cytec) corresponds to 2.3 moles of Bu₄P⁺Cl^-Dissolved in 1kg of commercial methanol (about 0.2% H)₂O) is in; 150g (2.58 moles) of potassium fluoride powder was added thereto, and stirred at 20 to 25 deg.C for 24 hours. The mixture was then filtered and the filtered residue washed with 2X 100g of commercial methanol; 150g (2.58 moles) of potassium fluoride powder was added to the combined filtrates, and the mixture was stirred at 20 to 25 ℃ for 24 hours. After filtration, it was washed with 2X 100g of commercial methanol and the mixture was freed largely of excess methanol and isopropanol in a rotary evaporator at temperatures of up to 30 ℃ and pressures of about 1 mbar and filtered again. The resulting substantially colorless solution had the following properties: fluoride (measured at PH 5.5 with ion sensitive electrode): 5.0% chlorine (total, gravimetric after decomposition): 0.4% MeOH (after normalization, analyzed by gas chromatography): 16.3% i-PrOH (after standardisation, gas use)Phase chromatography analysis): 7.3 percent

5.27g of anhydrous HF were added in portions to 100g of the above solution with stirring and cooling (< 20 ℃). When the exothermic reaction subsides, the tetrabutylphosphonium hydrogen difluoride solution thus obtained (stock solution 1, calculated fluoride content, F)^-Not total fluorine: 4.75%) was used for the trimerization of example 3-1.

A portion of the stock solution 1(200g) was freed from methanol and isopropanol to constant weight in a rotary evaporator for 6 hours at a temperature of up to 30 c and a pressure of about 1 mbar, reaching constant weight to a greater extent than is possible under the conditions (pressure, temperature). A colorless solution (166g) having the following properties was obtained. Fluoride (measured at pH 5.5 with an ion sensitive electrode; F originally present at 10.8% of this condition)^-Fluorine in the form of fluorine and fluorine in the form of HF added both as fluoride (F)^-) Detected as follows): HF content (simple 5.7% acidity titration with 0.1N NaOH using phenolphthalein as indicator): from the two values, F (formally) of the solution can be calculated^-The content was 5.4% and the molar ratio of F to HF was about 1: 1, i.e.HF was not removed because the concentration in the vacuum was too high. Chlorine (total, gravimetric after decomposition): 0.50% MeOH (after normalization, analyzed by gas chromatography): 3.4% i-PrOH (after standardisation, analysis by gas chromatography): 2.1% viscosity at 23 ℃ (mPas) 280

The mixture was liquid at room temperature and solidified to a white crystalline composition only when stored in the freezer compartment of a refrigerator (-12 ℃). Subsequent storage in a cold storage compartment (-2 ℃) changed the composition virtually completely back to liquid (cloudy solution containing solid particles). Then stored at room temperature (20-25 ℃) to give a homogeneous, transparent, colorless solution with the analytical data described above.

The highly concentrated solution thus obtained (hereinafter stock solution 2) can be used for the trimerization of HDI, for example (example 3-0), or also in the form of a mixture with various alcohols, further HF or further phosphonium fluorides (see also

Example 3, table 1). b) Bu in methanol/propanol₃(C₁₄H₂₉)P⁺F^-

Bu handle₃(C₁₄H₂₉)P⁺Cl^-500g of a 74.2% solution in isopropanol (Cyphos 3453P, product manufactured by Cytec) corresponds to 0.85 mole of Bu₃(C₁₄H₂₉)P⁺Cl^-Dissolved in 0.5kg of commercial methanol (about 0.2% H)₂O) is in; 50g (0.86 mol) of potassium fluoride powder was added thereto, and stirred at 20 to 25 ℃ for 24 hours at room temperature. The mixture was then filtered and the filtered residue washed with 2X 50g of commercial methanol; then, 50g (0.86 mol) of potassium fluoride powder was added to the combined filtrates, and the mixture was stirred at 20 to 25 ℃ for 24 hours. After filtration, it was washed with 2X 50g of commercial methanol and the mixture was freed largely of excess methanol and isopropanol in a rotary evaporator at temperatures of up to 30 ℃ and pressures of about 1 mbar and filtered again. The resulting substantially colorless solution had the following properties: fluoride (measured at PH 5.5 with ion sensitive electrode): 3.65% chlorine (total, gravimetric after decomposition): 0.145% MeOH (after normalization, analyzed by gas chromatography): 9.1% i-PrOH (after standardisation, analysis by gas chromatography): 3.8% c) Ph in methanol₃(Bu)P⁺F^-20g (56.3 mmol) of Ph₃(Bu)P⁺Cl^-(product of Chemconsterve) was dissolved in 40g of commercially available methanol (about 0.2% H)₂O) is in; 3.3g (56.8 mmol) of potassium fluoride powder was added thereto, and stirred at 20 to 25 deg.C (room temperature) for 24 hours. The mixture was then filtered and the filtered residue was washed with 2X 5g of commercial methanol; then, 3.3g (56.8 mmol) of potassium fluoride powder was added to the combined total filtrate, and stirred at 20 to 25 ℃ for 24 hours. After filtration, it is washed with 2X 5g of commercial methanol in a rotary evaporator at a temperature of up to 30 ℃The mixture was freed largely of excess methanol at a pressure of about 1 mbar until crystallization started and filtered. Filtration is carried out carefully to ensure that only the potassium salt formed as a result of too high a concentration of the solution is separated off, while the residue is free of phosphonium salt (soluble sample). The resulting solution had the following properties: fluoride (measured at PH 5.5 with ion sensitive electrode): 3.15% chlorine (total, gravimetric after decomposition): < 0.2% MeOH (after standardization, analysis by gas chromatography): 42.8 percent

Analogously to the preparation of stock solution 1 from the intermediate tetrabutylphosphonium fluoride solution, 1 equivalent of HF was added, the quaternary phosphonium fluorides obtained in examples 1b) and 1c) were converted into the corresponding hydrogen fluorides and were used for the trimerization of HDI in the manner described in example 3 (runs 3-14 and 3-15).

Example 2 comparative example

HDI trimerisation with quaternary ammonium hydrogen difluoride catalyst 1 (DE-A19, 611, 849 or co-pending U.S. application Ser. No. 08/822, 072).

According to J.org.chem.1989, 54, 4827-4829, FK in methanol, Quaternary ammonium chloride 336 (Quaternary ammonium chloride R manufactured by FlukaAG)₃(Me)N⁺Cl^-，R＝C₈-C₁₀Alkyl radical, C₈Essentially, the product contains isopropanol) by anion exchange to prepare the catalyst, which is then converted to R by the addition of HF₃(Me)N⁺〔HF₂〕^-Form, as described in example 1 (F of solution)^-The content is as follows: 2.05% other than HF₂ ^-Total fluorine of (a).

In the V4A reactor described in J.Therm anal.1983, 27, 215-228, stirring was first carried out under vacuum (0.1 mbar) at 60 ℃ for about 1 hour at a stirring speed of 1200 minutes^-1320g (1.9 mol) of HDI were allowed to release the dissolved gas. Nitrogen was passed in, and then 26ppm of catalyst 1 (based on fluoride ion (molecular weight 19) and HDI used) were added (catalyst 1 st addition in FIG. 1). After 5 minutes and againAfter 5 minutes, 6 or 3ppm F, respectively, were added^-Amount of catalyst (2 nd and 3 rd addition of catalyst in figure 1). After a total of 15 minutes, the reaction was stopped by adding 150mg of dibutyl phosphate and the reaction mixture was analyzed. The proportion of iminooxadiazinedione in the trimerization mixture was 9.5 mol%. The terpolymer resin obtained after thin-layer distillation at 140 ℃/0.2 mbar using a laboratory thin-layer evaporator of the short-circuit evaporator type has the same low content of iminooxadiazinedione and has a comparatively high haze (10.2TE (F)).

Attempts to reproduce those results have resulted in varied, largely analogous unsatisfactory results. Example 3 catalysis with phosphonium polyfluorides according to the invention

The stock solution 1 described in example 1a was used for the trimerization of HDI in a thermodynamic reactor (examples 3-1 in Table 1; see also FIG. 2). R_NCOAbout 20%; adding the molar amount of the catalyst and F^-The reaction was stopped with an equivalent amount of dibutyl phosphate consumed. F required for the reaction at 1/2/3 th addition of catalyst^-The amounts are shown in FIG. 2, i.e.based on HDI and fluoride ion F^-40/20/11ppmF by weight (molecular weight 19, not total fluorine)^-。

Other examples shown in Table 1 use stock solution 2 (run 3-0), and alcohols (runs 3-2 to 3-10), HF or tetrabutylphosphonium fluoride solutions may also be added as catalysts for HDI trimerization. In each case 200g (1.19 mol) of HDI were initially freed of gas dissolved in the diisocyanate mixture in a 250ml four-necked flask with internal thermometer, stirrer, reflux condenser, gas inlet and metering device for the catalyst solution at 60 ℃ and a pressure of about 0.1 mbar over a period of 1 hour. The trimerization is then carried out by introducing nitrogen and adding the catalyst in portions at an internal temperature of 60 ℃ and with a slight flow of nitrogen. In each case, R_NCOAbout 20%; adding the molar amount of the catalyst and F^-Dibutyl phosphate, in an amount comparable to the consumption (not total fluorine), stopped the reaction. F required for the reaction^-In amounts of HDI and fluoride ion F used^-(molecular weight 19, not TotalFluorine) 10-30ppmF by weight^-. Even with the use of a high concentration of stock solution 2, no solid formation was observed during the reaction. The iminooxadiazinedione contents of the products are given in Table 1. TABLE 1 results of HDI trimerization catalyzed by phosphonium polyfluorides

Example number	Alcohol(s)*	Bu4P+F-Or R4P+F-concentration [% ] (about)	F in the catalyst-HF (Mole)	Turbidity of the resin [ TE (F) ]	Proportion [ mol% ] of iminooxadiazinedione in trimer mixtures
						3-0	Methanol/isopropanol	80	1∶1	0.8	51
3-1	Methanol/isopropanol	70	1∶1	0.4	48
						3-2	Methanol	50	1∶1	0.5	45
3-3	Methanol	40	1∶1	1.4	42
						3-4	Methanol	40	1∶0.5	0.8	43
3-5	Isopropanol (I-propanol)	50	1∶1	0.5	47
						3-6	Isopropanol (I-propanol)	40	1∶1	0.4	42
3-7	Isopropanol (I-propanol)	30	1∶1	0.6	41
						3-8	Isopropanol (I-propanol)	20	1∶1	0.9	35
3-9	N-butanol	50	1∶1	0.5	44
						3-10	N-butanol	30	1∶0.5	0.5	38
3-11	Methanol/isopropanol	62	1∶5	0.5	53
						3-12	Methanol/isopropanol	50	1∶10	0.4	59
3-13	Methanol/isopropanol	37	1∶20	0.6	64
						3-14	Methanol/isopropanol	About 83% Bu3(C14H29)P+〔HF2〕-	1∶1	0.6	43
3-15	Methanol	About 57% Ph3BuP+〔HF2〕-	1∶1	0.5	44

^*In examples 3-2 to 3-10, only the alcohols added to further dilute the polyfluoride stock solution 2 are listed (for further explanation see the text of example 3) example 4-HDI/IPDI mixed trimerization of the invention

In a 250ml four-necked flask with internal thermometer, stirrer, reflux condenser, gas inlet and metering device for the catalyst solution, a mixture of 100g (0.59 mol) of HDI and 100g (0.45 mol) of isophorone diisocyanate (IPDI) is first freed of the gases dissolved in the diisocyanate mixture at room temperature and a pressure of about 0.1 mbar over a period of 1 hour. The mixture was then heated to an internal temperature of 60 ℃ under a weak stream of nitrogen. Then, at this temperature, a total amount corresponding to 87ppmF was added dropwise in portions over about 20 minutes^-So that the internal temperature does not exceed 70 ℃. Trimerization was carried out until the NCO content of the mixture was 34.0%. The reaction was stopped by adding 150mg of di-n-butyl phosphate and stirring was continued at 70 ℃ for a further 1 hour. The unreacted monomeric diisocyanate was then separated off by thin-layer distillation in a short-path evaporator at 0.15 mbar and a heating medium temperature of 180 ℃. A clear (haze 0.9te (f)) and virtually colorless resin (66g, corresponding to a yield of 33%) having a viscosity in the pure state of 23800mpa.s, an NCO content of 20.2% and a residual monomer content of 0.03% HDI and 0.11% IPDI were obtained. The molar ratio of hydrinyloxadiazinedione to isocyanurate was 45: 55. Example 5 invention H₆of-XDITrimerization of

100g (0.51 mol) of 1, 3-bis (isocyanatomethyl) cyclohexane (H) are initially pretreated as described in example 4₆-XDI, Aldrich), then stock solution 1 (42 ppmF total) was added in portions over 3 hours at 58-60 ℃^-) Trimerization was thus carried out until the NCO content was 36.4%. 100mg of di-n-octyl phosphate were added to terminate the reaction and the reaction was stirred at 60 ℃ for a further 1 hour. Unreacted 1, 3-bis (isocyanatomethyl) cyclohexane is then separated off by thin-layer distillation in a short-path evaporator at 0.15 mbar and a heating medium temperature of 150 ℃. A clear and virtually colorless resin (34g, corresponding to a yield of 34%) was obtained which had an NCO content of 19.7% and which was just flowable in the pure state at room temperature (20-25 ℃ C.). The viscosity of an 80% solution in n-butyl acetate was 1570mPa.s, the NCO content being 15.8%. The residual monomer content was 0.03% of 1, 3-bis (isocyanatomethyl) cyclohexane (H)₆-XDI). The iminooxadiazinedione content of the trimer mixture was 52%.

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (12)

1. A process for preparing a trimerized polyisocyanate containing at least 30 mole% iminooxadiazinedione in a mixture of trimers which comprises catalytically trimerizing a starting isocyanate containing a member selected from the group consisting of: an organic di-or polyisocyanate having a number average molecular weight of 140-600 and containing aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups,

R₄P⁺F^-·n(HF)

wherein

Each R is the same or different and represents a straight or branched C₁-C₂₀Aliphatic, aromatic and/or araliphatic radicals, and

n is a value of 0.1 to 20.

2. The process of claim 1 wherein the starting isocyanate comprises an aliphatic diisocyanate having a molecular weight of 140 and 300.

3. The process of claim 1 wherein the starting isocyanate comprises 1, 6-hexamethylene diisocyanate, bis (isocyanatomethyl) -cyclohexane or bis (isocyanatomethyl) norbornane.

4. The process of claim 1 wherein said polyisocyanate trimer mixture contains at least 35 mole% iminooxadiazinedione.

5. The process of claim 2 wherein said polyisocyanate trimer mixture contains at least 35 mole% iminooxadiazinedione.

6. The process of claim 3 wherein said polyisocyanate trimer mixture contains at least 35 mole% iminooxadiazinedione.

7. The process according to claim 1, wherein the trimerisation catalyst is present in a mixture with an alcohol having a number average molecular weight of 32-250, the concentration of the trimerisation catalyst in the mixture being not less than 10% by weight.

8. The process according to claim 2, wherein the trimerisation catalyst is present in a mixture with an alcohol having a number average molecular weight of 32-250, the concentration of the trimerisation catalyst in the mixture being not less than 10% by weight.

9. A process according to claim 3 wherein the trimerisation catalyst is present in admixture with an alcohol having a number average molecular weight in the range 32 to 250, the concentration of the trimerisation catalyst in the mixture being not less than 10% by weight.

10. The process according to claim 4, wherein the trimerisation catalyst is present in a mixture with an alcohol having a number average molecular weight of 32-250, the concentration of the trimerisation catalyst in the mixture being not less than 10% by weight.

11. The process of claim 5 wherein the trimerisation catalyst is present in admixture with an alcohol having a number average molecular weight of 32-250, the concentration of the trimerisation catalyst in the mixture being not less than 10% by weight.

12. The process according to claim 6, wherein the trimerisation catalyst is present in a mixture with an alcohol having a number average molecular weight of 32-250, the concentration of the trimerisation catalyst in the mixture being not less than 10% by weight.