DE19512479A1 - Retarded, thermally activated catalyst, useful in polyurethane prodn. - Google Patents

Abstract

Catalyst (I) suitable for thermal activation is obtd. by reacting (a) organic isocyanates with (b) (cyclo)aliphatic tert. amines contg. OH and/or prim. and/or sec. amino gps and opt. (c) (cyclo)aliphatic cpd(s). contg. prim. and/or sec. amino gp(s). The ratio of NCO gps. to total OH and prim. and sec. amino gps. is (0.9-1.1:1); and (I) contains at least 200 mmole tert. amino gps./100 g and has a softening point of over 50 deg C. Pref. (I) is in the form of a suspension in polyols and/or plasticisers.

Description

The invention relates to new, thermally activated catalysts and their ver Application for the production of optionally foamed polyurethane products.

Polyurethane systems are characterized by the variety of their structural components from which the manufacture of cellular to compact molded parts with some allow variable densities across the cross section of the molded part. In addition to the typical direct structure-forming components, such as long-chain polyols on polyester or Polyether-based, short-chain crosslinking agents based on low molecular weight polyols, Polyamines or water, and polyisocyanates, are additives such as Catalysts or surface-active compounds, for the targeted Auf construction required. A key position among catalysts is tertiary aliphatic amines because they are very effective and especially those for Drive reactions accelerate such an important water reaction with polyisocyanates.

For special effects it has been found necessary that these water reaction starts with a delay, be it that before the foaming, a higher one Molecular weight must be formed or that to produce a compact Edge zone from the liquid components in the molding this reaction locally only in expires to a minor extent. It is also often an advantage that the full kata lytic efficacy begins with a delay, so as to fill a complicated Form to ensure a long filling time before the actual foaming process expires.

Attempts in this direction are salt-like adducts of tertiary amine containing catalysts with acids (e.g. US-PS 45 82 861) or carbamates  or carbon dioxide (z. B. US-PS 44 67 089), which act delayed, but the Have the disadvantage that in formulations the acids with other basic Components can react, so that the delayed reaction at the moment Effect does not come into play or only to a small extent.

The present invention relates to new, thermally activated catalysts available through implementation of

• I. with organic isocyanates
• II. Contain hydroxyl and / or primary and / or secondary amino groups the aliphatic and / or cycloaliphatic tertiary amines and gege if necessary
• III. primary and / or secondary amino groups containing aliphatic and / or cycloaliphatic compounds,

where the ratio of the isocyanate groups of component I. to the sum of Hydroxyl and / or primary and / or secondary amino groups of the compo nente II. and optionally the sum of the primary and / or secondary Ami nogroups of component III. 0.9: 1 to 1.1: 1 and the content of tertiary amino groups in the catalyst at least 200 mmol per 100 g of Kata lysator and the softening point of the catalysts is above 50 ° C. lies.

According to the invention, the ratio of the isocyanate groups of component I. to the sum of the hydroxyl and / or primary and / or secondary amino groups pen of component II. and optionally the sum of the primary and / or secondary amino groups of component III. preferably 0.95 to 1.05 and the Content of tertiary amino groups in the catalyst preferably 350 to 600 mmol per 100 g of catalyst. The softening point of the catalysts is preferred at temperatures from 70 to 250 ° C.

According to the invention, the commercially available mono- and Polyisocyanates are used, such as methyl, butyl or stearyl isocyanate,  Hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, Toluene diisocyanates or diisocyanatodiphenylmethanes with their polymers Structures or trimerizates of hexamethylene diisocyanate.

Tertiary amines, in particular of the following formulas, come as component II into consideration

particularly preferred

As component III. come especially low molecular weight amines with 2 to 6 Carbon atoms, such as ethylenediamine, hexamethylenediamine or butylamine, preferably ethylenediamine.  

The thermally activated catalysts according to the invention can be produced by using component II. with those in polyurethane chemistry usual polyols or plasticizers and the isocyanate at temperatures from 20 to 50 admits. The temperature is set by cooling so that it remains below the melting point of the adduct which forms. Possible if it is also not preferred to use the catalysts as liquids or solids Polyol by intensive cooling under the influence of gravity into a dispersion or transfer suspension. In the manufacture according to the invention, it has proven to be useful, the isocyanate immediately before the addition with additional dilute polyol or plasticizer.

The implementation of the invention can in simple stirring units or in Flow mixers (see, for example, DE-OS 25 13 815).

The polyols commercially available in polyurethane chemistry can be used as polyols are used, especially polyether polyols, such as those commercially available Polyethylene and / or polypropylene ether polyols of OH number 25-300, which by base-catalyzed conversion of ethylene and / or propylene oxide and starters, such as propylene glycol, trimethylolpropane or glycerin can be obtained. As inert Solvents or plasticizers are possible: propylene carbonate and / or Benzyl butyl phthalate. The polyether polyols with OH numbers of are preferred 30 to 200 used.

The thermally activated catalysts are usually in the form of a Dispersion used in the above plasticizers or polyols. Here the solids content of the dispersions is about 5 to 25, preferably 10 to 20% by weight. With increasing solids content, some become highly viscous pseudoplastic dispersions obtained. This, in itself, undesirable rheological Properties do not constitute a serious impairment of use of the catalysts according to the invention, since they are typically in typical Amounts for catalysts from about 0.01 to 3 wt .-%, preferably 0.05 to 2% by weight of active substance (catalyst) are used.

The catalysts of the invention can be used to produce PU coating tings, PU bonds and molded polyurethane parts in a compact and preferred  foamed form can be used. The use of the invention is preferred contemporary catalysts for the production of optionally foamed poly urethane products.

The catalysts of the invention can be used alone or in a mixture with other, conventional polyurethane catalysts, such as tertiary amines will.

The catalysts of the invention have the advantage that they are initially the reaction as a heterogeneous and therefore slowed down in its effectiveness Connections exist and with progressive reaction (increasing Temperature) dissolve and become fully effective. This mechanism will intensified by cold molding temperatures, so that with such catalysts in a particularly advantageous manner, cellular molded parts with a good surface structure be preserved.

Examples Monofunctional tertiary amines (MA) (component II)

MA-1: N, N-dimethylpropylenediamine
MA-2: N, N-dimethylethylene diamine
MA-3: N, N-dimethylethanolamine
MA-4: N, N -diethylethylene diamine
MA-5: 4-amino-1-diethylaminopentane

Difunctional tertiary amines (DAG (component II)

DA-1: bis (3-aminopropyl) methylamine

Functional coreactants (DC) (component III)

DC-1: ethylenediamine
DC-2: butylamine

Isocyanates (component I)

ISO-1: stearyl isocyanate
ISO-2: hexamethylene diisocyanate
ISO-3: 4,4′-diisocyanatodicyclohexylmethane (Desmodur® W from Bayer AG)
ISO-4: 3-isocyanatomethyl-1,5,5-trimethyl-cyclohexyl isocyanate (IPDI)
ISO-5: prepolymer of 1 mol ISO-2 and 0.1 mol F-1: NCO content: 20.5%
ISO-5: 2,4-tolylene diisocyanate

Liquid media

F-1 polypropylene ether glycol with OH number 56
F-2 polyethylene ether glycol of OH number 185
F-3 propylene carbonate
F-4 benzyl butyl phthalate (Unimoll® BB from Bayer AG)

General manufacturing instructions

The compounds containing tertiary amino groups (MA and / or DA) with any co-reactants (DC) to be used in the liquid medium (F) submitted and the isocyanates (ISO) with good stirring at 20 to 40 ° C. dripped.

Finely divided, partly structurally viscous dispersions of tert-amino are obtained groups containing urethanes and / or ureas in polyols or others inert media such as polyethers or plasticizers.

The clear points of the 10% by weight solids are on the Kofler bench Dispersions determined.  

Products

Test procedure Zero attempt:

1020 g of polypropylene ether glycol (F-1) with OH number 56 become 178 g 2,4-tolylene diisocyanate reacted at 30 or 80 ° C.

After 50 minutes, an NCO value A of A-30 = 6.4 or A-80 = 5.6%.

Catalyzed experiment

Like zero attempt, but the reaction is carried out with 23 milliequivalents of tertiary amine Catalyzed form of MA-1.

After 50 minutes, an NCO value B of B-30 = 3.8 or B-80 = 3.2%.

The reaction mixture is clear from the start of the reaction.

Test attempt

Like zero attempt, but with the one given in the table below Amount of catalyst worked. Should NCO-reactive dispersants in Catalyst included, so was the amount of polypropylene ether glycol reduced accordingly. In the case of non-reactive dispersion media, the specified NCO value on the dispersant free composition for Converted for comparison purposes.

After 50 minutes, the NCO values C-30 given in the table are obtained or C-80.

The inhibition is expressed as a quotient multiplied by 100 (C-30-B-30) / (A-30-B-30) or (C-80-B-80) / (A-80-B-80).  

The reaction mixtures are cloudy and clear at 30 ° C Temperatures of 80 ° C mostly.

Result

Claims (4)

1. Thermo-activatable catalysts obtainable by the implementation of

• I. with organic isocyanates
• II. Hydroxyl and / or primary and / or secondary amino groups containing aliphatic and / or cycloaliphatic tertiary amines and optionally
• III. aliphatic and / or cycloaliphatic compounds containing primary and / or secondary amino groups,

the ratio of the isocyanate groups of component I. to that Sum of the hydroxyl and / or primary and / or secondary amino groups of component II. and optionally the sum of the primary and / or secondary amino groups of component III. 0.9: 1 to 1.1: 1 is and the content of tertiary amino groups in the catalyst is at least 200 mmol per 100 g of catalyst and the softening point of the catalysts is above 50 ° C. 2. Thermo-activatable catalysts according to claim 1, characterized records that they are in the form of suspensions in polyols and / or soft makers. 3. Use of the catalysts according to claims 1 and 2 for the preparation of possibly foamed polyurethane products.