DE4303887A1 - One-component rigid polyurethane foam system for aerosol cans - contains isocyanate prepolymer, known additives, volatile propellant and a viscous liq., satd. aliphatic hydrocarbon - Google Patents

Abstract

One-component systems (I) in pressurised containers, for prodn. of rigid polyurethane (PU) foam, comprise mixts. of (a) NCO gp.-contg. prepolymers obtd. by reaction of polyisocyanates with cpds. of mol.wt. 62-10,000 contg. at least 2 NCO-reactive H atoms, (b) known additives etc., (c) volatile liq. propellants with b.pt. below 0 deg.C/1-13 hPa, and (d) 0.25-2.5 wt.% (w.r.t. a) liq., satd. aliphatic hydrocarbons with dynamic viscosity 110-230 mPa.s at 20 deg.C and density 0.845-0.890 g/m3. Also claimed is rigid PU foam obtd. by hardening system (I) by the action of moisture after it leaves the pressure can. USE/ADVANTAGE - Used (esp. in aerosol cans) for filling applications, e.g. between window frames and walls, holes in walls etc., and fixing, e.g. door frames. Incorporation of (d) prevents the usual change in vol. or thickness due to diffusion processes, changes in temp. and/or humidity sec., and gives 1-component PU foam with improved dimensional stability.

Description

It is known to use one-component polyurethane foam by mixing polyols, foam stabilizers lisators, plasticizers, flame retardants, accelerators nigern and other aids in excess with di- and / or polyisocyanates in the presence of liquefied Propellants to free isocyanate groups Prepolymers. This reaction is more common as in pressure vessels z. B. aerosol cans.

When discharged, the reaction mass swells by evaporation of the blowing agent on (Frothing). By reacting with Moisture (e.g. ambient humidity) becomes the fer Obtained foam. This can come in many different ways Way are used, e.g. B. for filling and fastening purposes (door frame assembly).

A disadvantage of the PUR Foam is their tendency to diffuse through the Koh lendioxids from the closed cells and then eats air diffusion into the closed cells and / or due to increased temperature and / or increased humidity subject to a change in volume or thickness, which then leads to deformations on foamed components can lead. At elevated temperature (40-70 ° C) and / or increased air humidity (70-95% relative humidity) can be up to + 25% (expansion) and -25% (Shrink) linear change in thickness. Task of The invention is such a volume or thickness to largely avoid changing the one-component foam the.

It was surprisingly found that under Mit use of liquid, saturated, aliphatic Koh Hydrogen oils in the usual one-component systems the desired effect has been achieved. EP-A 0 066 830 also describes the production of PUR foam fabrics with improved dimensional stability based on One-component systems, however, goes with use of organosilicon compounds from a totally another group of substances.

The invention relates to hard polyurethane foam one-component systems that form substances in one Pressure vessels are available and represent mixtures of

• a) prepolymers containing isocyanate groups Lich by reacting polyisocyanates with Ver bonds with at least two compared to isocyanates reactive molecular hydrogen atoms weight 62-10 000,
• b) auxiliaries and additives known per se,
• c) blowing agents with a boiling point below 0 ° C / 1013 hPa, which in the pressure vessel z. T. blurs sigt present and evaporate when depressurized and
• d) liquid, saturated, aliphatic hydrocarbons in a concentration of 0.25-2.5% by weight (based on prepolymer a), which has a dynamic viscosity of 110-230 mPa · s at 20 ° C and a density of 0.845- 0.890 g / cm ³ (d 20 ° / 4 °).

According to the invention it is preferred that the blowing agent c) Tetrafluoroethane, difluoroethane, dimethyl ether, propane, Butane, carbon dioxide, nitrous oxide, if necessary in combination.

The invention also relates to rigid polyurethane foam fabrics, obtainable by curing the one-component Systems after they exit the pressure vessel Exposure to moisture.  

Starting components for the use according to the invention the prepolymers are:

• 1) Aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, such as those used for. B. by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, for example those of the formula Q (NCO) nin the
  n = 2-4, preferably 2 and 3, and
  Q is an aliphatic hydrocarbon residue with 2- 18, preferably 6-10 C atoms, a cycloaliphatic hydrocarbon residue with 4-15, preferably 5-10 C atoms, an aromatic hydrocarbon residue with 6-15, preferably 6-13 C- Atoms or an araliphatic hydrocarbon radical with 8-15, preferably 8-13 carbon atoms be mean z. B. such polyisocyanates, as described in DE-OS 28 32 253, pages 10-11. In particular, the technically easily accessible polyisocyanates, for. B. the 2,4- and 2,6-tolylene diisocyanate, and any mixtures of these isomers ("TDI"); Polyphenylpoly methylene polyisocyanates such as those produced by aniline-form aldehyde condensation and subsequent phosgenation ("crude MDI") and carbodimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups containing polyisocyanates ("modified polyisocyanates", in particular such modified polyisocyanates) Polyisocyanates derived from 2,4- and / or 2,6-tolylene diisocyanate or from 4,4'- and / or 2,4'-diphenylmethane diisocyanate.
• 2) Compounds with at least two versus Isocya nate reactive hydrogen atoms from one Molecular weight usually from 62-10,000. Here is understood in addition to amino groups, thio groups or compounds containing carboxyl groups preferably a hydroxyl-containing verb tions, in particular 2 to 8 hydroxyl groups pointing compounds, especially those from the mole Specular weight 100 to 6000, preferably 2000 to 6000, e.g. B. at least 2, usually 2 to 8, but preferably 2 to 6, hydroxyl groups pointing polyethers and polyesters as well as polycar bonate and polyester amides, such as those for Her position of homogeneous and cellular poly urethanes are known per se and how they z. B. in DE-OS 28 32 253, pages 11-18 become. Preferred polyethers are those based on from TMP or sucrose.

Other such starting components are Hydroxyl groups and / or amino groups and / or Thiol groups and / or carboxyl groups Compounds, preferably hydroxyl groups and / or Compounds containing amino groups, the usual Licher as a chain extender or Crosslinking agents serve. These connections point usually 2 to 8, preferably 2 to 4, against hydrogen atoms reactive via isocyanates on. Examples of this are found in DE-OS 28 32 253, pages 19-20.

The prepolymers are prepared in a manner known per se produced.

The auxiliary and contained in the mixture Additives are e.g. B.

• Catalysts of the type known per se,
• - Surface-active additives, such as emulsifiers and foam stabilizers, silicon organ African foam stabilizers are preferred and usually in an amount of 1-5% by weight, based on prepolymer a), are used,
• - Plasticizers, cell regulators of the known Kind of like paraffins or fatty alcohols or di methylpolysiloxanes as well as pigments or colors substances, flame retardants of the known Kind, e.g. B. tricresyl phosphate, also Stabilisa  against aging and weather influences and possibly fungistatic and bacterial static substances and fillers.

These auxiliaries and additives are, for example in DE-OS 27 32 292, pages 21-24.

Further examples of fiction, if any according to the surface-active additive to be used substances and foam stabilizers as well as cell regulators, Response retarders, stabilizers, flame retardants the substances, plasticizers, dyes and Fillers as well as fungistatic and bacterio statically active substances and details about use and mode of action of this addition medium are in the plastic manual, volume VII, edited by Vieweg and Höchtlen, Carl-Hanser- Verlag, Munich 1966, e.g. B. on pages 103-113 described.

Examples of blowing agents which are liquefied and / or gaseous in the pressure vessel and have a boiling point below 0 ° C./1013 hPa are:
Tetrafluoroethane, difluoroethane, dimethyl ether, propane, butane, carbon dioxide, nitrous oxide.

Examples of possible liquid, saturated aliphatic hydrocarbons are:
Paraffin oil viscous with a dynamic viscosity of 110-230 mPa · s at 20 ° C and a density of 0.845-0.890 g / cm ³ (d 20 ° / 4 °).

The finished foam can be used for filling purposes, e.g. B. between window frames and masonry, for breakthroughs and fastening purposes, e.g. B. for door frame assembly, be used.

Examples

Suitable dosing devices were used for the pre polymer formation necessary premixed component I and II placed in dry aerosol cans

Component I:
Oxypropylated glycerin adipic acid / phthalic acid ester with functional OH groups 100 g
Tris (2-chloroisopropyl) phosphate N-substituted morpholine polyether polysiloxane

Component II:
Crude diphenylmethane diisocyanate 143 g.

Finally, the required amount was put into the cans filled with blowing agent (difluoroethane). The component I became a liquid aliphatic hydrocarbon added.

Below are the dimensional stability values as linear change in thickness depending on the percentage (based on component I) of the paraffin used  after min. 4 weeks of storage in pure carbon dioxide gas shown. The values were determined according to the "Test method for the practical determination of the dimensions stability of PUR assembly foams ", P. Gruss (see Kunststoffe, 78 Born in 1988, pp. 1104-1106).

table

The foams do not tend to further storage for expansion (no positive change in thickness).

Claims (3)

1. Single component systems forming hard polyurethane foams, which are present in a pressure vessel and are mixtures of

• a) prepolymers containing isocyanate groups, obtainable by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms with a molecular weight of 62-10,000,
• b) auxiliaries and additives known per se,
• c) propellants with a boiling point below 0 ° C / 1013 hPa, which, for. T. liquefied and evaporate when depressurized and
• d) liquid, saturated, aliphatic hydrocarbons in a concentration of 0.25-2.5 percent by weight (based on prepolymer a)), which has a dynamic viscosity of 110-230 mPa · s at 20 ° C and a density of 0.845- 0.890 g / m ³ (d 20 ° / 4 °).

2. Single component forming hard polyurethane foams ten according to claim 1, characterized in that as a blowing agent tetrafluoroethane, difluoroethane, Di methyl ether, propane, butane, carbon dioxide, Distick material oxide, optionally in combination become. 3. Hard polyurethane foams, available through Hardening of the one-component systems according to claim 1 and 2 after exiting the pressure vessel by exposure to moisture.