CS210081B1 - Process for producing polyurethane foam - Google Patents

Abstract

In the production of polyurethane foam, a tertiary amine is used as a foaming catalyst. A number of suitable tertiary amines are known, but new ones are still being found, which either alone or in combination with other amines create more suitable conditions for the technological reaction or are reflected in the resulting values of the produced foam. The invention addresses the use of diethylaminoethanol as a foaming catalyst in soft, semi-rigid and hard polyurethane foam and provides the reaction times for foam formation and the physical and mechanical values of the foam, proving the consistency of the technological reaction. Foams prepared in this way are fully usable in their main application areas - construction, automotive and furniture industries, etc.

Description

SUMMARY OF THE INVENTION The present invention provides a process for producing a soft, semi-hard and hard polyurethane foam in the presence of a novel amine-based catalyst.

Polyurethane foams are to be understood as meaning the products which have been prepared by the reaction of bifunctional or multifunctional isocyanates with polyether polyols and polyester polyols.

The reactions leading to the formation of polyurethane foam proceed slowly at normal temperature.

In order to achieve technically realistic Saxons, these reactions must be accelerated and harmonized with each other. This is achieved by means of catalysts.

Although bases and metals present in the polyol and other recipe components can also act catalytically, the presence of catalysts in the recipe is necessary. They can control the rate of crosslinking reactions between the starting components during the formation of the foam and enable the individual partial reactions to be harmonized for optimum foaming. The reconciliation of these reactions is very important as the gas evolution and polymer molecule growth must proceed at a rate such that the gas remains in the polymer and the polymer has sufficient stability at the end of the foaming to prevent foam collapse.

Tertiary amines and organic metal compounds are generally used as catalysts. · «

The catalytic action of tertiary amines is based on the formation of an isocyanate amine complex. According to the Baker mechanism, one could expect that the more basic the catalyst, the more active its effect should be, because the strength of the base is ^{- a} measure of the ease with which the amine gives its free spring to the proton electron. It is now known that the activity of a tertiary amine as a catalyst is also determined by its structure, and the smaller the steric hindering of the amine, the more active the amine as a catalyst. Indeed, once the complex is formed between the isocyanate and the amine, the NCO intermediate is in a better position to react with the polyol or water, thereby forming urethane, urea or carbon dioxide. The ease with which this complex forms helps to determine the rate of the catalyzed reaction. This demonstrates how important steric factors are in determining tertiary amine. Exposed nitrogen, without steric hindrance, allows the complex to form easily.

This theory is confirmed and triethylenediamine appears to be the most suitable tertiary amine to catalyze the formation of polyurethane foam.

In practice, however, it has been found that it is not always desirable to use very strong, so-called primary catalysts, exhibiting in the first stage high exothermicity with rapid polymerization progress and low carbon dioxide evolution during this period. In many cases, it is preferable to combine these catalysts with the so-called secondary catalysts to provide an even smoother and more balanced polyurethane foam catalysis.

The invention solves the use of diethylaminoethanol as an amine catalyst.

It is a catalyst with a low activation energy in which new, higher effects have been shown to ensure smoothness and balance of catalysis, especially where short foam start times and rapid foaming are required, especially when combined with strong catalysts.

The short starting times depend on the low activation energy of diethyleminoethanol in the reaction with the secondary hydroxyl groups and in part on the presence of highly reactive primary hydroxyl groups. Low activation energy with secondary hydroxyl groups is used to prevent the neutralization of trace amounts of acids in various raw materials and to protect a strong catalyst such as triethylenediamine. The relatively low activation energy allows the use of more amine with little effect on the foam growth pattern; but with a large capacity to neutralize trace amounts of acids.

Diethylaminoethanol, due to its hydroxyl group, binds to the polymer structure.

This prevents the formation of closed pore regions, the foam structure.

Its dosage is chosen from 0.08 to 12.0% by weight. parts.

The method of application of diethylaminoethanol is evident from the examples.

Example 1.

Foam mixture containing 100 wt. d, polyetherpolyol / no. OH 49, mol. h. 3500), prepared from glycerin, propylene oxide and ethylene oxide, 3.1 wt. d. water, 0 to 0.1 wt. d. triethylenediamine, 0.6 to 0.01 wt. d. diethylaminoethanol, 0.9 wt. d. polysiloxane surfactant, 0.2 wt. d. tin octoate at the 105 index of toluylene diisocyanate had reaction times - beginning of foaming 14 s, ending foaming 90 s - and produced a foam having a density of 30 kg / m < 2 > compressive and ductile strength ČSN 64 5431 0.12 MPa, 280%, permanent deformation ČSN 64 5442 2.7%.

The reaction times of the foam formation were balanced throughout, manifesting in a sufficiently long foam flow time and at a technically corresponding start and end of foaming fully usable in the production of block polyurethane foam.

Example 2.

Foam mixture containing 100 wt. d. polyether polyol / 6. OH 450, molek, d. 1300, functionality 3 /, 0 to 0.7 wt. d, triethylamine, 4.2 to 0.06 wt. d. diethylaminoethanol, 1.5 wt. d. polysiloxene surfactant, 25 wt. d. Monofluorotrichloromethane at an index of 105 for diphenylmethane diisocyanate metering had reaction times - beginning of foaming 55 s, ending foaming 320 s - and produced a foam having a bulk density of 45 kg / m 2 and a pore closure of 99% with other parameters according to rigid polyurethane foam technology.

Example 3.

Foam mixture containing 100 wt. d, polyether polyol (# OH) 35, moles. 4500, about 50% of the primary hydroxyl groups, 2.6 wt. d. water, 1.0 wt. d, triethanolamine, 0 to 0.2 wt. d. triethylenediamine, 1,2 and? 0.02 wt. d. diethylaminoethanol, 1.0 wt. d. polysiloxane surfactant, 0.2 wt. d. Dibutyltin dilaurate, when dosing a mixture of diphenylmethane diisocyanate and toluylene diisocyanate in a ratio of 1: 1 at an index value of 105, had reaction times - beginning of foaming 16 s, ending foaming 110 s - and produced foam 5441, 40% 0.45 kPa, tensile and tensile strength ČSN 64 5431 0.17 MPa and 140%, permanent deformation ČSN 64 5442 2.4%

Example 4.

Foam mixture containing 100 wt. d. polyester polyol / no. OH 50, mol. h. 2700], prepared from diethylene glycol, kye. edipol and triol, 3.7 wt. d. water, 1.4 wt. d. N-methylmorpholine, 0.05 wt. d. Deemorapide PP, 1.0 to 0.02 wt. d. diethylaminoethanol, 1 wt. d. The polysiloxane surfactant, when dispensing toluylene diamine cyanate at an index value of 95, had a reaction time - start of foaming 12 a, end of foaming 80 8 - and formed a foam with a density of 30 kg / m ³ , anti-compression resistance. kPa, tensile strength and ductility ČSN 64 5431 0.12 MPa and 270%, permanent deformation ČSN 64 5442 5% The reaction was sufficiently coordinated, no defects in the foam occurred; foam by its nature fully corresponds to its use for laminating textiles.

Claims (1)

SUBJECT OF THE INVENTION Process for preparing soft, semi-rigid and hard polyurethane foams by reacting bifunctional or multifunctional isocyanates with polyether polyols and polyester polyols in the presence of amine-based catalysts, characterized in that diethylaminoethanol in an amount of 0.08 to 12.0 wt. parts for polyetherpolyol or polyeaterpolyol.