DE2242678A1 - PROCESS FOR THE PRODUCTION OF POLYISOCYANURATES - Google Patents

Description

Process for the preparation of polyisocyanurates

The invention "relates to a process for the preparation of polyisocyanurates from a mixture of aromatic and aliphatic Polyisocyanates that cure in the presence of an initiator as well as applying this. "Method of manufacture of laminates that from .den. polyisocyanurates according to the invention manufactured- (rain st and e are characterized by good heat stability the end.

Polyisocyanurates, as obtained from aromatic diisocyanates, have good hardness, are flame-resistant and mechanically resistant up to relatively high temperatures, for example 180 ° C. However, they are brittle, which somewhat limits their applicability. In addition, it was found that the thermal stability is desirable at a temperature above 200 ° C

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leaves. The polyisocyanurates begin at these temperatures decompose, possibly due to the formation of Carbodiimide by reaction of free isocyanate groups that are still present in the high molecular weight network. This leads to Formation of cracked or foamed objects. In view of the good flame retardancy properties of poly-τ-. Isocyanurates would be very desirable to reduce thermal instability to be eliminated as far as possible. :

It has now been found that by using a mixture · ■■■■ ·: aromatic and aliphatic isocyanates in certain ratios to each other this problem can be solved. It Attempts have already been made to convert aliphatic diisocyanates into polyisocyanurates polymerize, however, most of the Trimerization catalysts, how to use them for aromatic Diisocyanate uses, inactive with aliphatic diisocyanates. In addition, those formed from aliphatic diisocyanates have Polyisocyanurates have so poor mechanical resistance at elevated temperatures that the articles made from them generally have little practical utility. Surprisingly, it has now been found according to the invention that both disadvantages, namely thermal instability aromatic polyisocyanurates and poor mechanical properties of aliphatic polyisocyanurates at increased Temperatures can be overcome by using a certain starting mixture.

The invention thus relates to a method for producing Polyisocyanurates based on a curable mixture of aromatic compounds and aliphatic polyisocyanates, this mixture the aromatic and aliphatic substances in a weight ratio between 1: 2 and 3> 5: 1 | preferably between Contains 1: 1 and 3: 1. Here is made between aromatic and aliphatic Polyisocyanates understood substances that contain isocyanate groups have bound to aromatic or aliphatic radicals.

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Examples of "useful aromatic polyisocyanates are: m- and p-phenylene diisocyanate, toluene-2,4-diisoeyanat and Toiuol-zje-diisocyanate, naphthol-I, 5-diisocyanate, diphenyl ether-4,4 ^f -diisoeyanat, benzophenone-4> 4 '-diisocyanate, diphenylmethane-4 * 4'-diisocyanate, triplienylmethane-4,4', 4 "-triisocyanate or mixtures thereof. Other useful base materials are mixtures obtained by reacting low molecular weight hydroxy compounds v / ie butanol, glycerol or glycol with, for example, toluene diisocyanate in an OH / NGO ratio of 1: 2 to 1: 4. It is preferred to use aromatic diisocyanates, especially those with an alkylene group between the two isocyanatoary residues. Very good results are obtained with diphenylmethane-4,4'-diisocyanate.

Examples of aliphatic polyisocyanates that can be used are: Hexane-1,6-diisocyanate, dodecane-1,12-diisoeyanate, cyclohexane-1,4- ^ -diisocyanate, dicyclohexylmethane ^ 4,4'-diisocyanaty 2-butene-1,4- diisocyanate and diethyl sulfide 2,2'-diisocyanate.

The polymerization of the mixture of aromatic and aliphatic Polyisocyanate takes place in the presence of a basic initiator, e.g. a Lewis base, especially a tertiary one Amine. Examples of such initiators are triethylamine, Pyridine, triethylenediamine, dimethylethanolamine, sodium carbonate, Potassium acetate, ITodium methylate, dimethylphenylphosphine, tetrahydro thiophen, hexahydrodimethylaniline, benzyldimethylamine, N-methylpiperidine and N-methylmorpholine. Generally applies one 0.05 to 5 mol-? » Initiator, calculated on the polyisocyanates, at.

Preferably, the starting mixture of polyisocyanates is also added a coinitiator added. A good acceleration effect of the Inition is obtained with epoxides, in particular with epoxides which are soluble in the polyisocyanate. Examples of such Epoxides are epichiorhydrin, propylene oxide, ethyl glycidate, Phenyl glycidyl ether and diglycidyl ether of diphenylol propane.

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Further applicable coinitiators are e.g. pivalolactone and carbamic acid esters such as ethyl esters of phenylcarbamic acid. These Esters can be formed in situ if a compound containing one or more hydroxyl groups, such as benzyl alcohol, is added to the mixture the aromatic and aliphatic polyisocyanates is added. The coinitiators are generally used in quantities of at least 0.05 mol $ based on polyisocyanates applied. As a rule, one can say that proportions over 5 mol # (based on polyisocyanates calculated) are not required, but can be used, such as lactone up to 200 mol- $. the Epoxides are generally used in amounts not exceeding 25 moles. Initiator and coinitiator should usually be in approximately equivolar proportions are present, e.g. per mole of initiator at least 0.5 »in particular 0.8 to 1.5 moles of coinitiator.

In addition to the products already shown, one can use for the production the polyisocyanurates according to the invention also introduce other components such as sand, bitumen, tar, pigments, dyes, Fiberglass fabric, broken or staple fiberglass, other polymers such as polyvinyl chloride.

Moldings can be produced by the process according to the invention, either by a casting technique or by lamination, especially where good curing is essential. In general, the hardening temperature will be increased to 100 or 200 ° C.

The polyisocyanurates obtained according to the invention are not meltable and not soluble in the solvent. They can be used with advantage for a wide variety of laminates and castings will.

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EXAMPLE I

Starting mixtures of diphenylmethane 4 »4 ^I diisocyanate (" MDI ") and 2,2,4 ~ trimethylhexane-1,6-diisocyanate (" TMHDI ") were prepared in various proportions at room temperature. 1% by weight of dimethylethanolamine and 1% by weight of phenylglycidyl ether were added to the mixtures and the whole was cured according to the following program:

1 hour at 20 ° C, 3 days at 50 ° 0, 1 hour at 150 ° G and

2 hours at 180 ° C. The castings thus obtained were

Maintained at 220 ° G and 250 ° C for two hours. The results are compiled in the following table.

Weight ¹¹ Vica t "softening. Temp. ⁰ G Appearance relationship at 0.1 mm Well 50/50 158 Well 60/40 198 Well 70/30 220 cracked 80/20 not determined foamed and 90/10 not determined swollen foamed and 100/0 not determined swollen

For comparison, 97 parts by weight of an aliphatic diisocyanate (hexane-1,6-diisocyanate) were mixed with 3 parts by weight of glycidyl ester of a, a ~ dimethyl carbonic acid with 9 to 11 carbon atoms and 1% by weight of triethylenediamine _f at room temperature for 16 hours and at 150 ° C cured for three hours. The appearance of the molding was good after heating to 220/250 ° C., but the "Vicat" softening temperature was lower than 60 ° C. at 0.1 mm. If the glycidyl ester was not used, there was almost no hardness at all.

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EXAMPLE II

3 parts by weight of dimethylethanolamine and 1 part by weight of phenylglyeidyl ether were added to a mixture of 2 parts of ItDI and one part of TMHDI. After 16 hours at room temperature, a hard, clear casting was obtained. Curing was continued at 180 ° C. for a further 5 hours. The shaped body then had a "Barcol" hardness of 45 », a softening temperature of 249 ° C. (ASTM D 648 under a load of 1810 kW / m ² ) and a notched impact strength (Izod) of 3.7 kj / m ² .

EXAMPLE III

To a mixture of 2 parts of MDI and 1 part TMIIDI 3 parts by weight of benzyldimethylamine, and 1 part by weight of phenyl glycidyl ether were added, and the mass of impregnating ei ^1; s glass fiber tissue (Clark & Schwebbel, 200 g / m, plane wet-'β electrical, Type 7628, treated with an epoxysilane size · grease Z 6040). A ten-layer laminate was pressed and cured for 16 hours at 50.degree. C., 1 hour at 100.degree. C., one hour at 150.degree. C. and 3 hours at 180.degree. That

Laminate had a flexural strength of 57.9 MN / in, a flexure at break of 4.9 mm (ASTM D 790) and a modulus of elasticity of 25,800 MN / m ² .

Claims

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Claims (9)

Claims 1 .. Process for the preparation of polyisocyanurates, thereby characterized in that one is a mixture of aromatic and aliphatic polyisocyanates in a weight ratio of 1: 2 "to 3.5: 1 cures in the presence of a basic initiator. 2. The method according to claim 1, characterized in that that a polyisocyanate mixture is cured in a weight ratio of 1: 1 to 3: 1. 3 · The method according to claim 1 or 2, characterized in that the polyisocyanates in the form of Uses diisocyanates. 4 · Method according to one of claims 1 Ms 3, characterized characterized in that aromatic diisocyanates are used in which two isocyanatoaryl radicals have an alkylene group are bound. 5. The method according to claim 4 _}, characterized in that one uses as aromatic Diisocy.anat Mphenylmethane-4,4'-diisocyanate. 6. The method according to any one of claims 1 to 5, characterized characterized in that a tertiary amine is used as the basic initiator. 7. The method according to any one of claims 1 to 6, characterized characterized in that in addition to the basic 309810/1031 1A-41 799 Initiator also uses an epoxy coinitiator. 8. The method according to claim 6 or 7t, thereby g e k e η η “I know that you have the initiator or initiators in one Apply an amount of 0.05 Ms 5 mol-56 calculated on poljisocjanate. 9. Yerfahren according to claim 8, characterized in that 0.8 Ms 1.5 mol of coinitiator each Get initiator applies. 'Application of the method' according to claim 1 for production by JJarainaten. 3 JO 1 Ο / ICM