DE1670667C3 - Process for the trimerization of aromatic polyisocyanates - Google Patents

Description

Process for the trimerization of aromatic polyisocyanates are known in large numbers. As catalysts for this Trimerisicrungsreaktion are in addition to strong basic compounds, such as the alkaline metal salts of organic acids and tertiary amines, especially suitable tertiary phosphines of the aliphatic and mixed aliphatic-aromatic series.

The phosphine catalysts allow working, preferably at low temperatures (about 50 C), whereby the production of almost colorless polymers is possible, but have the following disadvantages:

1. Ls are relatively large amounts of the technically sensitive and carefully handled catalyst required to complete the polymerization process in economical periods of time, and this high amount of catalyst remains together with a corresponding amount of stopper in the reaction mixture /.

2. When using 2,4-tolylene diisocyanal or of mixtures containing 2,4-toluene diisocyanate as the main component contain large amounts of solid reaction products at temperatures below 100 C, the / to part of 3.3'-diisocyanato-4,4'-dimethyldiphemluretdione, Partly from addition compounds such as isoevanurate cyanates with excess toluene diisocyanate order and as a thick, hardly stirrable Krisiallbrci the technical handling of the reaction mixture and make heat transfer so difficult that the use of suitable solvents is necessary will. Lct / lcres, in turn, makes the use of higher amounts of catalyst necessary.

3. The use of aromatic polyisocyanates in which the reactivity of the two isocvanate groups is equal to. was the production of low molecular weight trimers, i.e. with only one or few isocyanurate rings. often even impossible with the help of phosphines. So, for example the method of U.S. Patent 2,801,244 the use of diisocyanates ^ in which an isocyanate group is sterically hindered, and so forms z. B. 4,4'-diisocyanato-diphenylmethane, which contains NCO groups with the same reactivity in the treatment of phosphine catalysts with or without

ίο Solvent high molecular weight polymers with uretdione structure, which because of their poor solubility wedge for further processing as a reactive lacquer or adhesive component are unsuitable.

It has now been found that these disadvantages of the known trimerization processes can be made more aromatic Can overcome polyisocyanates.

The present invention therefore relates to a process for the trimerization of aromatic polyisocyanates with aliphatic, araliphatic and mixed aliphatic-aromatic phosphines as catalyst, which is characterized in that aliphatic isocyanates are used in the trimerization in such a way that an aromatic NCO group is used more than 0.5 aliphatic NCO groups.

preferably more than one aliphatic NCO group, and up to 13 aliphatic NCO groups come and heated to a maximum of 120 C. The reaction will be before The reaction mixture / aromatic isocyanates are too depleted when a certain NCO content is reached interrupted by adding known stoppers, and unreacted monomers are severed.

The term "trimerization" here means throughout both the formation of only one isocyanurate ring as well as information about the polyfunctionality of the isocyanates, the formation of several isocvanurate rings.

The addition of aliphatic isocyanates causes
1. A sharp increase in the rate of reaction, which can be more than ten times the rate of reaction which is observed under the same conditions with purely aromatic polyisocyanates. This co-catalysis is particularly surprising because aliphatic mono- or polyisocyanates alone are much more difficult to trim or polymerize with high phosphine concentrations. The addition of aliphatic isocyanates is therefore to be expected to slow down the trimerization reaction, which is only observed when the concentration of the aliphatic isocyanates in the reaction mixture exceeds about four to five times the concentration of the aromatic isocyanate groups. The quantitative results are shown in the graph at the end;

2. a suppression of the formation \ on in the reaction approach insoluble or high molecular weight intermediate or by-products. 4,4-diisocyanatodiphenyl methane and other aromatic diisocyanates with identically reactive isocyanate groups are based on this Way of a trimerization with phosphine catalysts accessible.

The British patent specification 856 372 already describes a mixed trimcrisalion aliphatic and aromatic Isocyanates using phosphine catalysts. However, the isocyanates get there always in strictly stoichiometric amounts of 1 mole of aliphatic isoeyanate to 2 moles of aromatic isoeyanate Linsal / .. The ratio of aliphatic to aromatic

table isocyanate groups is therefore never higher than 0.5 dimensioned.

However, as has been found, it achieves both the cocatalytic effect of the addition of aliphatic and especially the possibility of making the image undesirable To suppress insoluble intermediate and by-products, their full effectiveness only at higher aliphatic content. Precisely the trimerization of aromatic substances, which is important from a technical point of view Polyisocyanates, which is only represented in Examples 6 and 7 of the patent mentioned Without the formation of a precipitate and without the use of suitable solvents, this can only be carried out successfully feed when the ratio of the aliphatic to the aromatic isocyanate groups is greater than 0.5, preferably is greater than 1. The production of low molecular weight Trimeiisate of aromatic diisocyanates, their Isocyanate groups as in 4,4'-diphenylmethane diisocyanate have the same reactivity, is even according to the method of the British patent impossible.

Surprisingly, does the incorporation of larger proportions of aliphatic isocyanates in the reaction mixture mean? not that the reaction products of the process according to the invention also incorporated higher aliphatic compounds must contain.

The aliphatic isocyanate groups only take part in the trimerization reaction to a minor extent, as long as temperatures of 120 ° C. are not exceeded during the trimerization and the trimerization reaction is interrupted before the reaction batches are too depleted in aromatic isocyanates. If you z. B. a reaction mixture of 67 percent by weight 1,6-hexamethylene diisocyanate and 33 percent by weight 2,4-tolylene diisocyanate - NCO ratio so about 2 - trimerized until the NCO wide of the reaction mixture has dropped from 49.3 to 35 "" so contains the trimer about 40 ° ₀ Aliphatenanteil and the Aroniatenanteil in the monomer mixture of the distillate or the extract is depleted to 10 to 12 °, ₀ (see. example 1). in the trimerization of 4,4'-diphenylmethane diisocyanate which ratio is supposed to aromatic of aliphatic isocyanate be expedient even greater than 1.5, if one wishes to obtain residue-soluble Trimerisatc. at an NCO ratio of from 2 1,6-hexamethylene diisocyanate is incorporated only to about 28 ° / _0, when the reaction at an NCO-value is of 35 ° ₀ interrupts (see example 2).

With an increasing proportion of aliphatic in the trimer, this naturally changes its character, and the Finished products obtained therefrom are distinguished by increasing lightfastness and flexibility.

All aromatic polyisocyanates can be used as starting material for the process according to the invention serve. Particularly noteworthy are 2,4- and 2,6-tolylene diisocyanate, 2,4'- and 4,4'-diisocyanatodiphenylmethane as well as m- and p-phenylene diisocyanate, l-methoxyphenylene-2,4-diisocyanate, 4,4'-diisocyanatodiphenyl, 4,4'-diisocyanatodiphenyl ether, 4,4'-diisocvanatodiphenylpropane-2,2, 1,5-diisocyanatonaphthalene, 4,4 ', 4 "-triisocyanatotriphenylmethane, tris- (p-isocyanatophenyl) -thiophosphoric acid ester.

Aliphatic ^ and araliphatic isocyanates, which in the context of the process according to the invention, the trimerization catalyze and must be included in the reaction mixture in an amount that the ratio of aliphatic to aromatic isocyanate groups

(NCO ratio) exceeds the value of 0.5, are z. B. Diisocyanates such as 1,4-TetraniethyIendüsocyanat, 1,6-hexamethylene diisocyanate, 1,3- and 1,4-xylylene diisocyanate and their nuclear-substituted homologues. Aliphatic monoisocyanates behave in the same way. Suitable are e.g. E.g .: methyl isocyanate, Butyl isocyanate, f '»- chlorhexyl isocyanate or long-chain representatives such as stearyl and oil isocyanate as well Aralipaths, e.g. B. benzyl isocyanate.

As catalysts for the process according to the invention only aliphatic, araliphatic and mixed aliphatic-aromatic phosphines are suitable, e.g. Triethylphosphine, tri-n-butylphosphine, D'methylhenzylphosphine, Dimethylphenylphosphine. Tribenzylphosphine. Two alkyl groups can also become one Ring closed, as with P-butyl-phosphacyclopentane. The reaction can be interrupted at any time by adding stoppers known per se, see above that also reaction products of different degrees of trimerization can be obtained. Alkylating agents are preferably used as stoppers. how Dimethyl sulfate, methyl iodide or toluenesulfonic acid slcr and acylating agents such as benzoyl chloride, acetyl chloride, N-phenyl-N-methacrylic acid chloride or chloroformic acid ester in question. The trimerization is expediently interrupted at the latest when the NCO content is 50 to 60 "" des The initial value has decreased.

Monomers that have not been converted can be removed under mild conditions after the reaction has been terminated. This can be achieved, in which only the monomers but not the trimers are soluble, 1. B., with aliphatic or cycloaliphatic hydrocarbons. By high vacuum distillation in suitable evaporators or by extraction with appropriate solvents

The effectiveness of the catalysts is already at temperatures a little above room temperature, considerable.

The reaction proceeds between -20 and + 15O ⁰ C., however according to the invention at temperatures up to 120 ° C, preferably between 40 and 120 ° C. As a result, the passing at higher temperatures in competition carbodiimide formation is avoided and there is obtained largely colorless products.

The amount of catalyst depends largely on the amount of aliphatic isocyanate added as cocatalyst dependent. In general, amounts range from 0.001 to 0.1 percent. Do you work under optimal conditions? Conditions, d. H. with an isocyanate ratio of 1 to 2, 0.01 to 0.05% is sufficient.

The process according to the invention is most expediently carried out with the exclusion of solvents, what by adding suitable amounts of aliphatic isocyanates and choosing suitable reaction temperatures is possible in any case. If solvents are used for the reaction, this is the case To increase the amount of catalyst, the more so the less polar the solvent is. Do you want in Esters. Ketones or chlorinated hydrocarbons !! obtain soluble low molecular weight process products, the reaction is advantageously interrupted before all of the monomeric isocyanate has reacted and this is separated by extraction with the solvents mentioned or by (thin-layer distillation. The separated Monomer mixtures can be easily analyzed by determining their refractive index;

1,670

this mainly based on aromatic polyisocyanate, the unreacted monomer mixture is separated

Armtcn mixtures can be distilled after appropriate earth.

Addition of the monomers as starting material for 186 parts by weight of a brittle light yellow:

use a new trimerization approach. Resin with an NCO value of 19.8%, obtained because

If the proportion of aliphatic isocyanate in the reaction with ethyl acetate in a 67% solution is less than the NCO ratio of 0.5 allows a viscosity of 725 cP / 20 to be converted. Al · corresponds, of course, mixed distillate will also result in 285 parts by weight of monomer mixture. However, one has to get back with the mixture in which the disadvantages already indicated by refraction, ie an analysis of an enrichment of the 1,6-hydrogen chloride higher amount of catalyst and the formation of insoluble isocyanates up to 89%, was found. The Ali by-products and the much lower yields of the phate fraction in the trimer is about 40%.
accept: because the trimerization reaction

must be given at a very early point in time - Example 2
broke, the trimer separated and the aliphatic

table isocyanal in the distillate or extract added 15 125 g freshly distilled pure 4,4'-diisocyanate

will. Such a procedure is unsuitable. Pheny! Methane (melting point 39.4 ') can be added by adding \ on

and uneconomical. 168 g UvHxamethylene diisocyanate and heating up

The products of the process have generally dissolved 100 ° C. and the trimcrization by adding NCO groups that are still free, but 0.15 g of tri-n-butylphosphine (0.05 ¹ V ₀ ) can also be initiated in this way. Be further trimerized so that no free NCO groups * ° the NCO content of the Rcaktionsmischuim are present. There are non-volatile substandard is 45 minutes to 35.3%, dropped, which usually is solid at room temperature resins in _ga b _e a mixture aus'o.lg is "Zuzcn. P-Toluolsulfonsäureselicnen cases form viscous liquids and methylesier 0, 1 g of dimethyl sulfate breaks the reaction well in the cold in a series of organic compounds and dissolves the reaction mixture in a thin solvent. For this purpose, esters such as vinegar can be subjected to layer distillation. From 240 g of ethyl acetate, butyl acetate and ethyl glycol mixture, 95 g of a brittle resin and 142 g of ether acetate, ketones, such as acetone, methyl ethyl ketone distillate, are obtained . are dichloromethane or Chlorbcnzol, particularly comparable 22.5 ⁰ Z ₀ of 4,4'-diisocyanatodiphenylmethane impoverished spent 3 <> _{The resin enl} | _1old thus about 28%, 1,6-hexa-

The pure or solvent-based forms of methylene diisocyanate have an NCO value of 18.9 ""

Process products can also in their "Abspal- _an d soluble in ethyl acetate to a viscous,

tcrform \ i.e. in the form of its reaction products a clear solution with a solids content of 75% '

with phenols. Acetoacetic esters, malonic esters or di- The IR spectrum shows strong absorption bands

phenylamine derivatives are transferred . These 35 4,4.5,9.6.65 and 7.0 μ on (weaker bands are

Cleavers behave at high temperatures as at 3.4-5.7-6.25 and 7.3 μ) and thus proves the fso-

the free isocyanates and can advantageously always cyanurate structure of the product

can be used if, in reaction mixtures, if the reaction is interrupted as described above

with a compound containing hydroxyl or amino _groups only at an NCO value of 31 0% from

Long standing times are desired and the actual 40 _{is kept from 240 g of the} reaction mixture at the

high crosslinking reaction at elevated temperatures thin film distillation 122 g of distillate up to

should be made. The pure or i ₉ o _{/ o} can be depleted of 4,4'-diphenylmethane diisocyanate.

solvent-containing forms of the reaction products _and 114 g of isocyanurate, which has an NCO value of

has also with suitable mono- or polyalcohols and i _5j o ° / _o and a Molekulareewicht of 1036

Amines or with water and dehydrating 45 The proportion of built-in 1,6-hexamethylene diiso-

Implement means so that more or less high cyanate Iiect between 30 and 31 ° /

wetted products with low isocyanate contents contain- "°"
stand.

The process products can be used as adhesives, as B e i s ρ i e 1 3 Hardener for resins and for polyester and polyether 50

lacquers, as one-component lacquers and for production The following experiments are intended to show how Va-

of casting resins, elastomers and foams, a mixture of the molar ratio or the reaction

find application. Set of polymers can be obtained to measure.

B is ρ ie 1 1 55 A) Variation of the molar ratio

170 parts by weight of 2,4-toluene diisocyanate All experiments in this series are of 1.6 to 330 parts by weight of 1,6-hexamethylene diisocyanate, hexamethylene diisocyanate (H) and 2,4-Toluylendiisoauf 60 ^c C and heated cyanate by the addition of 0.125 Ge- (T ) carried out at 100 ⁰ C and with 0.015 percent by weight parts by weight (0.025%,) tri-n-butylphosphine trimeri- 6 ° tri-n-butylphosphine as a catalyst, siert. First of all, the approach must be cooled slightly. Only in experiment 5 (molar ratio 5: 1) is it. If after about 4 _1/2 hours an NCO value of 36% is expedient and the amount of catalyst is 0.1 Ge, the reaction is increased by adding percent by weight. The reactions are terminated at 0.1 part by weight of methyl p-toluenesulfonate and because at an NCO value of about 42, 0.1 part by weight of dimethyl sulfate and a short amount of 65, which corresponds to about a 20% conversion. The zen to 100 ⁰ C interrupted. In the case of slow through experimental details, the following table shows passage through a thin-film evaporator (vacuum. Experiments a) and b) represent Ver-0.8 Torr, temperature of the heating medium 180 to 190 ⁰ C) are equivalent experiments.

Disproportion H: T ν: I ν

Composition " _η H

of the starting product "," T

NCO value after termination of the reaction in °, _n

Reaction conversion calculated from the yield

Composition "." H

of the distillate "" T

NCO content of the end product in "."

Monomer content of the end product in "." .... Composition ¹ V ₀ H

of the end product ° / ₀ T

Molar ratio in the end product ν: 1 ν

Molecular weight

Experiment c)

0.2 16.3 S3.7 41.8 20.3 12.0

21.6 0.9 32.7 67.3 0.51 678 0.5
32.5
67.5
42.0
24.1
31.0
69.0
21.5

0.7

37.4

. 62.6

0.62
688

49.1
50.9
41.9
20.3
52.0
48.0
21.6

0.6
42.0
5S.0

0.76
680

65.9 34.1 42.1 24.5 74.0 26.0 21.4

0.2 44.4 55.6

0.S2 771

S2.S 17.2 42.4 23.5 91.0

9.0 1> U

0.2 57.0 43.0

1.37 1010

As the results show, it is thus possible, by changing the molar ratio in the starting product, to change the proportion of the aliphatic isocyanates built into the isocyanates within certain limits without increasing the size of the molecule. As the evaluation of the test series shows, the proportion is aliphatic isocyanates isocyanurate 32-44 ° / ₀ if it varies in the starting product 12 to 74 weight percent.

B. Variation in sales

All experiments in this series are carried out with 1,6-He \ amethylene diisocyanate (H) and 2,4-tolylene diisocyanate (T) in a molar ratio of 2: 1 at one temperature of 60 C and with a concentration of 0.025 percent by weight Tri-n-butylphosphine carried out as a catalyst. The reaction has been at different NCO values canceled. The experimental details are given in the table below

1 t attempt 4th 5 NCO value after termination of the reaction in ° / ₀
Composition ° ₀ H
of the distillate% T 42.1
74
26th 38.0
81
19th 36.0
86
14th 34.6
90
10 32.5
95
5 NCO value of the end product in ° / ₀
Aliphatic content in the end product in ° / "
Viscosity of 67 ° / _o solution in ethyl acetate
in cP at ⁷ OC 21.4
44.4 20.7
43.2
400 19.8
42.5
725 18.8
42.0
1390 17.3
40.8
4400 Molecular weight 770 810 860 990 1200

The reaction product obtained in Experiment 3 consists mainly of a binuclear, which obtained in experiment 5 from a trinuclear isocyanurate.

Example 4

The tertiary phosphines of the aliphatic or mixed aliphatic-aromatic series suitable for carrying out the reaction differ only in their activity, not in their reaction behavior.

The IR spectrum of the reaction products does not change even when other catalysts are used.

The following table provides information on the relative catalytic activity. In all experiments, 67 g of 1,6-hexamethylene diisocyanate and 33 g of 2,4-tolylene diisocyanate were stirred at 60 ° C. with the specified catalyst.

catalyst

Molecular weight

Amount in Amount in NCO value according to mg m mole 3 hours 53 0.45 23.8 90 0.45 36.3 616 2.2 43.1 352 2.2 45.6 304 2.2 38.7 488 2.2 44.7

Triethylphosphine

Tri-n-butylphosphine ... Tricyclohexylphosphine. Triisopropylphosphine ... Phenyldimethylphosphine Phenyldibutylphosphine ..

The catalytic effectiveness of the phosphines used therefore decreases with decreasing basicity and increasing steric hindrance. The amount of catalyst, 113
202
280
160
138
222

which is necessary to achieve comparable reaction rates, therefore depends heavily on the Nature of the phosphine used.

Example 5

262 parts by weight of 4,4'-dicyclohexylmelane diisocyanate and S7 parts by weight of 2,4-tolylene diisocyanate (molar ratio 2: 1) are stirred with 1 part by weight of tri-n-butylphosphine at SO C until the NCO value rises to 36.1 in the course of about four hours 30.0 _"0 has dropped. The reaction is unreacted then by adding 0.5 parts by weight of dimethyl sulfate and 0.5 overall" Vicht share p-Toluolsulfonsäuremethvlester interrupted and (1er Monomerenüberschiili \ on diisocyanates in the thin film evaporator 180 hei C and 1 Torr in separated dry nitrogen stream. There are obtained:

a) 262 parts by weight of distillate, which according to the gaschrornatographisclien Separation to 14 "" from 2,4-toluylene diisocyanal and 84% of Dicvelohewl diisocyanate-4,4 'and which is obtained when standing for a long time dimeric toluene diisocyanate separates;

b) 80 parts by weight of an essentially mononuclear isocyanurate, which is about 56 ° "from toluene diisocyanate. 44 " ₀ consists of dicyclohexyldiisocyarate-4,4. The brittle resin has an NCO gelialt of 21.1", a molecular weight of 606 and dissolves without residue in ethyl acetate and other esters to form a yellow, viscous solution.

Example 6

140 parts 1,4-Tetramcthylenendiisoeyanat and 125 parts by weight of diphenylmethane diisocyanate 2.4 ' (Molvcrhäür.is 2: 1) are heated to 120 C, mixed with 2 parts by weight of phenyldimethylpho'phine and stirred until after about 4 hours an NCO content \ on 34.3 "" is reached. The further reaction is then by adding 4 parts by weight of a mixture from equal parts of methyl p-toluenesulfonate and dimethyl sulfate and stirring for one hour H) O C interrupted and the reaction mixture in the thin-film evaporator in polymer and unreacted Starting product separated (180 C. 1 Torr). Hs are obtained:

a) 112 parts by weight of distillate, which after the gas chromatographic Separation from 20 parts by weight of diphenyl methylene isocvanate 2.4 'and 92 parts by weight consists of tetramethylene diisocyanate;

b) 138 parts by weight of a resin which is soluble in ethyl acetate without residue and has an NCO value of 16.5 ° _u . The product mainly consists of a binuclear isocyanurate. however, it also contains small amounts of carbodiimide and uretonium moieties.

Example 7

222 parts by weight of 1-isocyanato-3-isocyanatmeothyI-3,5,5-trimethylcyclohexane and 87 parts by weight of 2,4-tolylene diisocyanate (molar ratio 2) are stirred at 60 ° C. with 0.3 parts by weight of tri-n-butylphosphine until the NCO value is dropped in the course of 4 ", hours from 41.0 to 32.4 °." by the addition of 0.2 parts by weight of dimethyl sulfate and 0.2 parts by weight of p-Toluolsulfonsäuremethy! ester and heating at 80 C, the further reaction is interrupted and unreacted Separated monomeric isocyanate in a thin-film evaporator at 185 ° C. and 1 torr. There are obtained: 218 parts by weight of distillate, which consists of 33 parts by weight of aromatic and 185 parts by weight of aliphatic diisocyanate and 81 parts by weight of a brittle, yellow-colored resin with an NCO value of 19, 4 "". which has a molecular weight of 780 and an aliphatic content of 41 "".

Example 8

194 parts by weight of 6-chloroheyl isocyanate and 75 parts by weight of c Diphenylmethane diisocyanate-4,4 'are mixed and heated to 120 ° with stirring. After

ίο Addition of 0.4 parts by weight of tri-n-butylphosphine the NCO value drops from 28.2 to 23.5% in the course of four to five hours. By adding 0.9 parts by weight of a mixture of dimethyl sulfate and methyl p-toluenesulfonate and a cinhour After stirring at 100 ° C., the further reaction is interrupted. The reaction mixture shows thereafter an NCO value of 23.3% and is in a thin film evaporator at 190 C and I Torr of freed unreacted monomers. Weiden obtained: 199 parts by weight of distillate, which after the gas chromatographic analysis from 178 g of chlorhexyl isocyanate and 21 g of diphenylmethane diisocyanate-4,4 ', and 63.5 g of a brittle, easily meltable one Resin. This shows an NCO value of 10.8 ""

and is soluble in ethyl acetate to give a 67 "solution with a viscosity of 23 P _10. The resin is a mononuclear isocyanurate composed of 2 moles of aromatic and 1 mole of aliphatic isocyanate. It contains small amounts of the carbodiimide formed by doubling the molecule. Chlorine content 5,3 ° ■ ", Molecular cevvichl 780.

Example 9

36 parts by weight of l-methyl ^^ - diisocyanalocyclohexane and 17.4 parts by weight of 2,4-toluene diisocyanate are heated to 80 C _and stirred with 0.13 parts by weight of tri-n-butylphosphine until the NCO value of Reaction mixture from 47.2 to 37.5 °: “has dropped. By adding 0.1 part by weight of a mixture of equal parts of dimethyl sulfate and methyl p-toluenesulfonate and stirring for an hour at 80 C, the reaction is terminated and the reaction product in a thin-film evaporator at 175 C and 0.5 torr of unreacted mono-

+5 kidneys freed. The following are obtained:

a) 35.8 parts by weight of distillate, which after the refractometric Analysis from 32.2 parts by weight of aliphatic! and from 3.6 parts by weight of aromatic isocyanurate exists and

b) 15.2 parts by weight of a brittle very poorly flowable resin in thin film evaporator from the NCO value 16.5, containing about 20 ⁰ Z _0, the aliphatic isocyanate. Molecular weight 84.

Example 10

161 parts by weight of 6-chlorohexyl isocyanate and 87 parts by weight of 2,4-tolylene diisocyanate are heated to 60 ° C. and 0.25 parts by weight of tri-butylphosphine are added while stirring. After just 15 minutes, the reaction is interrupted at an NCO value of 22.0 ° ₀ by adding 0.1 part by weight of dimethyl sulfate and 0.1 part by weight of methyl p-toluenesulfonate and heating to 80 ° C. for one hour. In a subsequent thin-film distillation at 190 ° C. and 1 torr, the unreacted monomeric diisocyanates are separated off. The following are obtained:

Il 12

a) 148 parts by weight of distillate from 126 parts by weight of phosphine trimerization should serve the following proportions of chlorhexyl isocyanate and 22 parts by weight of suehsreihen:
2,4-toluene diisocyanate, and

b) 89 parts by weight of isocyanurate with an NCO-A (lanus-shaped curve)
Value of 12.5 ⁰ Z ₀ and a chlorine content of 7.6%. 5

The resin is in lists and ketones without residue. 100 g each of a mixture of 2,4-toluylene diisoeya-

soluble and consists of a mixture of roughly gleinate (T) and 1 / i-hexamethylene diisocyanate (H) in total

chcn parts mononuclear and binuclear isocyanurate. given ratio are heated to 60 C and through

Addition of 100 never tri-n-butylphosphine (0.1 ⁿ ") die

^ Purification of the h.gur _{l0 Trimerjsalion} initiated. The time until the Rr-

To illustrate the co-catalytic effect, an NCO value of 40 "" is sufficient in the approaches

when adding aliphatic isocyanates when measuring is carried out.

a) g · H) Og immeasurably long in this test arrangement

b) 10 g; 90 g molar ratio 9.3 5 1/2 hours

c) 20 g; 80 g molar ratio 4.2 20 minutes

d) 30 g '70 g molar ratio 2.4 8 minutes

e) 40 g x 60 g molar ratio 1.6 6 minutes

f) 50 g; 50 g cannot be measured in this test arrangement because of the formation of insoluble deposits.

B (dashed curve) cyanate (T) and!, O-Hxamethylene diisocyanate (H) are given Ratio are in 100g water and

When using solvents and lower alcohol-free ethyl acetate dissolved, to 60 ° C

Reaction temperatures, the catalyst requirement is heated and the trinierization reaction by addition

to achieve similar reaction rates of 300 mg tri-n-butylphosphine (0.3 ° ■■ “, based on

larger, the co-catalytic effect of added ali- used isocyanate) initiated. The time to

however, phatic isocyanates is just as evident. to achieve an NCO value son 16 "" and

Measure 100 g of a mixture of 2,4-toluene diisocyanate.

a) 100 ε

b) 80 g

c) 60 g

Molar ratio 0 4'Z ₂ hours

20 g molar ratio 0.26 46 minutes
40 g molar ratio 0.69 35 minutes

d) 40g x 60g molar ratio 1.56 62 minutes

e) 20 g ⁴ 80 g no longer measurable in this test arrangement.

The two curves A and B show the time to reach the NCO value mentioned in the different mixing ratios in the two systems described.

1 sheet of drawings

Claims (3)

Patent claims: 1. Process for the trimerization of aromatic polyisocyanates with aliphatic, araliphatic and mixed aliphatic-.uromatic phosphines as catalysts, characterized in that that aliphatic isocyanates are used in the trimerization in such an amount that there are more than 0.5 and up to 10 aliphatic NCO groups for an aromatic NCO group, heated to a maximum of 120 ° C and the reaction before the reaction mixture of aromatic isocyanates too much depleted when a certain! NCO content is reached by adding itself known stopper interrupts and separates unreacted monomers. 2. The method according to claim 1, characterized in that aliphatic isocyanates in in such an amount that there is more than one aliphatic group on an aromatic NCO group NCO group is coming. 3. The method according to claim 1 to 2, characterized in that the trimerization is interrupted at the latest when the NCO content _{has dropped to 50 to 60 ° 0 of} the initial value.