CS253786B1 - An emulsifying and dispersing system for polyurethane foams - Google Patents

Abstract

Emulsifying and dispersing system, consisting of ionic and nonionic surfactants, with alkyl polyglycol ether sulfate as the ionic substance and a block copolymer of ethylene oxide and propylene oxide as the nonionic substance. A mixture of these substances in a ratio of 1:10 to 1:30 favorably affects the foaming reaction of polyurethane foams.

Description

The invention relates to an emulsifying and dispersing system for polyurethane foams.

The production of polyurethane foam is already well developed and used. The basic manufacturing principle and technological details are given, for example, in Becker - Polyurethane (VEB Fachbuchverlag, Leipzig 1973).

In addition to the basic components - polyol and diisocyanate - other components such as catalysts, activators, water, surfactants and others are involved in the polyaddition reaction.

Polysiloxane compounds are predominantly mentioned and practically used in the literature as surfactants. However, some organic surfactants which are not based on the polysiloxane compound and which alone or in combination can give very good results are also known.

The foaming reaction, which is characteristic of polyurethane foams, is dependent - of course outside the catalyst foams and other recipe ingredients - on the choice and dosing of surfactants.

The formation of polyurethane foam has a number of characteristics. It begins with the release of gas, which initially dissolves immediately in the liquid phase. After some time, bubbles are released and so-called creaming occurs in the reaction mixture. A prerequisite for the release of bubbles is a saturated solution of the reaction mixture with gas and the presence of germs for the formation of cells. The initiator here is the air which is blown into the reaction mixture. Reducing surface tension also greatly facilitates the formation of germs.

Simultaneously with the formation of cells, it is necessary to temporarily stabilize this system. One of the basic conditions of foam formation is the presence of a surfactant in the reaction mixture which forms a surface film at the liquid-gas interface. As soon as the active substance comes into contact with the gas, the adsorbent layers are formed on the interfacial dug-gas and a foam is formed.

Between the formation of the cells and the final stabilization, which is the formation of the polymer structure, the time interval in which various processes take place with the cells takes place. Some cells grow, others shrink to disappear, others merge to form larger cells. In some cases, above-average cells may form and foam may collapse. Also, the cell walls themselves undergo various changes. They can remain intact and the resulting foam has cells closed, or the walls rupture partially or completely and the resulting foam has cells open. Again, under extreme conditions, the foam may collapse or deform.

For optimal cell formation in the liquid phase, for proper growth and for a smooth transition from the liquid phase to the solid polymer phase, surfactants are used, and as mentioned above, most often silicone compounds of the polyoxyalkylene polysiloxane type or surfactants of sulfated fatty alcohols, alkylphenols , oxyethylated fatty acids, ammonium salts of fatty acids, and others.

Some other theoretical dependencies of polyurethane foam formation as well as the effect of surfactants on the foam properties are described in more detail in the Author's Certificate No. 217 089. The object of the above invention was a combination of ionic and nonionic surfactants comprising the sodium salt of a sulfonated butyl oleic acid ester, a substituted polyglycol ester sulfate, and an ethylene propylene oxide copolymer. This mixture shows very good results not only by its effect on the prepared activator of all auxiliary components in water, but also on the formation of a uniform cell structure.

During detailed assessment in long-term practical use, the individual components of this mixture and their proportions were changed. This has led to optimization of the composition of the novel emulsifying and dispersing system of the present invention. The emulsifying and dispersing system consists of an ionic surfactant which is an alkylpolyglycol ether sulfate of the general formula R-O-IC ₂ H ₄₀ O _x -SO ₃ Me, where R is an alkyl and Me metal or ammonium cation and a non-ionic surfactant ¹ , which is a block copolymer of ethylene oxide and propylene oxide of the general formula HO- (C ₂ H ₍ 10) _x - (C ₃ H ₆ O) _x -H in a ratio of 1:10 to 1:30).

This emulsifying and dispersing system is characterized by an even greater influence on the course of the polyurethane foam formation reaction and extends the application possibilities to all basic types of polyurethane foams. It positively affects the surface tension of the whole reaction system, even with significantly different systems, differing both in chemical composition and viscosity parameters. Good results were also obtained with lower water content formulas, ie without the presence of secondary foaming agents. It also expands its possibilities of combination with polysiloxane surfactants.

The actual application of this system to the reaction mixture consists in its perfect mixing with the other components in the so-called activator, which is then dosed into the polyol component either directly or in the mixing chamber of the foaming machine.

Generally, the dosage of this surfactant system is selected in the range of 0.2 to 6.0% by weight. parts per 100 wt. d. a polyol with respect to the overall composition of the formulation, particularly considering whether the system is applied alone or together with the polysiloxane compound.

Example 1

Foam mixture containing 100 wt. d. polyester polyol (OH No. 49, molecules, mass 3500), prepared from glycerin, propylene oxide and ethylene oxide, 3.1 wt. d. water, 0.1 wt. target. amine, 0.6 wt. d. polysiloxane surfactant, 0.2 wt. d. an emulsifying and dispersing system of 0.015 wt. d. sodium alkyl polyglycol ether sulfate and 0.185 wt. % of a mixed copolymer of propylene oxide and ethylene oxide; Slovanik PV - 370

0.25 wt. d. The tin octoate at the 105 index of toluylene diisocyanate had reaction times - beginning of foaming 14 s, ending foaming 90 s - and corresponded to the requirements for preparing a soft polyurethane foam.

Example 2

Foam mixture containing 100 wt. d. a prep.lymer formed by the reaction of polytetramethylene ether glycol and toluylene diisocyanate, characterized by an NCO content of 6.3%, 3.1 wt. d. an emulsifying and dispersing system consisting of 0.2 wt. d. sodium alkyl polyglycol ether sulfate and 2.9 wt. d. Mixed copolymer of propylene oxide and ethylene oxide, Comm. Slovanik PV-370, 3.9 wt. d. phenylenediumin, 2.2 wt. d. tertiary amine, 8.0 wt. d. methylene chloride, 2.0 wt. d. The black pigment composition had reaction times - beginning of foaming 60 s, end of foaming 117 s, end of sieving 200 s - and corresponded to the requirements for the preparation of semi-hard microporous foam.

Example 3

Foam mixture containing 100 wt. d. polyether polyol (OH No. 360), 0.5 wt. d. water,

2.5 wt. d. an emulsifying and dispersing system of 0.15 wt. d. sodium alkyl polyglycol ether sulfate and 2.35 wt. d. a mixed copolymer of polyethylene oxide and ethylene oxide; Slovanik T-610, 0.4 wt. d. tertiary amine, 15.0 wt. d. Monofluorotrichloromethane at a 105 index diphenylraetane diisocyanate dosing time had a start time of 12 sec., a foaming end of 40 sec., and a sieve end of 120 sec.

Claims (1)

SUBJECT OF THE INVENTION An emulsifying and dispersing system for polyurethane foams consisting of ionic and non-ionic surfactants, characterized in that it contains as an ionic substance an alkyl polyglycol ether sulfate of the general formula R-O- (G 1 H 2 O) _x -SO ₃ Me, where R is C 1-6 alkyl. to C ^, x is from 3 to 5 and Me is a metal or ammonium cation and as a non-ionic substance a block copolymer of ethylene oxide and propylene oxide of the formula HO- (C2H4O) _χ - (Ο ^ ΗθΟ) _χ , -Η, where x is 45 to 50 and ax 13 to 17 in a weight ratio of 1:10 to 1:30.