REACTION SYSTEM FOR A ONE COMPONENT RIGID POLYURETHANE FOAM

Abstract

The invention relates to a one-component reaction system for producing rigid polyurethane foams (also called rigid PUR foams) having improved dimensional stability, to methods for producing same and the use thereof. The invention also relates to the rigid polyurethane foams produced using the one-component reaction system according to the invention.

Claims

1. A one-component reaction system for producing rigid polyurethane foams, comprising: A) at least one organic polyisocyanate component, B) at least one isocyanate-reactive component wherein the isocyanate-reactive functional groups are exclusively isocyanate-reactive functional groups having at least one Zerewitinoff-reactive hydrogen atom, C) at least one foam stabilizer, D) at least one catalyst suitable for catalyzing the reaction of the polyisocyanate component A) with the isocyanate-reactive component B), E) at least one physical blowing agent having a boiling point of less than 0° C., and optionally co-blowing agents, and F) optionally, assistant and/or additive substances, wherein the isocyanate-reactive component B) comprises at least 10% by weight, based on 100% by weight of the sum of the weight fractions of components A) to F), of a polyether carbonate polyol.

2. The one-component reaction system as claimed in claim 1, wherein component A) contains at least 90% by weight of aromatic polyisocyanates based on 100% by weight of component A).

3. The one-component reaction system as claimed in claim 1, wherein component B) contains a polyol having a functionality F.sub.n of 1.0 to 4.0, preferably 1.5 to 3.5, particularly 1.9 to 3.0.

4. The one-component reaction system as claimed in claim 1, wherein component B) contains a polyether polyol having an OH number of 50 to 300 mg KOH/g, preferably 75 to 275 mg KOH/g, especially preveably 100 to 250 mg KOH/g.

5. The one-component reaction system as claimed in claim 1, wherein as foam stabilizer C) compounds having a structural formula (I) ##STR00004## wherein x, y=integer>0 and x/y=dimethylsiloxane proportion<5, n, m=integer>0 and n/m=ethylene oxide/propylene oxide ratio; A=aryl, alkyl or H are employed.

6. The one-component reaction system as claimed in claim 1, comprising: 30% to 70% by weight of organic polyisocyanate component A), 15% to 50% by weight of isocyanate-reactive component B), 0.2% to 4.0% by weight of a foam stabilizer C), 0.1% to 1.0% by weight of catalyst D) and 10% to 30% by weight of at least one physical blowing agent having a boiling point of less than 0° C. and optionally co-blowing agents (component E) and 0.0% to 20.0% by weight of assistant and additive substances (component F), with the sum of the % by weights of components A), B), C), D), E), and F) totaling 100% by weight.

7. The one-component reaction system as claimed in claim 1, wherein the isocyanate index is 350 to 550.

8. A process for producing a one-component reaction system by reacting A) an organic polyisocyanate component and B) an isocyanate-reactive component wherein the isocyanate-reactive functional groups are exclusively isocyanate-reactive functional groups having at least one Zerewitinoff-reactive hydrogen atom, in the presence of C) at least one foam stabilizer, D) at least one catalyst suitable for catalyzing the reaction of the semi-prepolymer with atmospheric humidity, E) at least one physical blowing agent having a boiling point of less than 0° C., and optionally, co-blowing agents, and F) optionally, assistant and/or additive substances, wherein the isocyanate-reactive component B) comprises at least 10% by weight, based on 100% by weight of the sum of components A) to F), of a polyether carbonate polyol.

9. A process for producing a rigid polyurethane foam obtainable by mixing and reacting the components A) to F) of a one-component reaction system as claimed in claim 1 through exposure to moisture.

10. A process for producing a rigid polyurethane foam comprising a) producing a one-component reaction system by a process as claimed in claim 8, and b) exposing the one-component reaction system produced in step a) to moisture.

11. A rigid polyurethane foam obtainable by a process as claimed in claim 10.

12. (canceled)

13. A pressurized container, in particular a single-use pressurized containing a one-component reaction system as claimed in claim 1.

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

Description

[0062] In a preferred embodiment the reaction system contains no short chain monools or hydroxyketones. In the context of the present application “short chain” is to be understood as meaning in particular monools and hydroxyketones having a molecular weight of <200 g/mol. Such compounds can act as cell openers, which is not desired here.

[0063] In a first embodiment the invention relates to a one-component reaction system for producing rigid polyurethane foams comprising the constituents: [0064] A) at least one organic polyisocyanate component, [0065] B) at least one isocyanate-reactive component whose isocyanate-reactive functional groups are exclusively those having at least one Zerewitinoff-reactive hydrogen atom, [0066] C) at least one foam stabilizer, [0067] D) at least one catalyst suitable for catalyzing the reaction of the polyisocyanate component A) with the isocyanate-reactive component B), [0068] E) at least one physical blowing agent having a boiling point of less than 0° C. and optionally co-blowing agents and [0069] F) optionally assistant and additive substances, [0070] characterized in that [0071] the isocyanate-reactive component B) contains at least 10% by weight, based on the sum of the weight fractions of A) to F)=100% by weight, of a polyether carbonate polyol.

[0072] In a second embodiment the invention relates to a one-component reaction system according to the first embodiment, characterized in that the component A) contains at least 90% by weight of aromatic polyisocyanates based on A)=100% by weight.

[0073] In a third embodiment the invention relates to a one-component reaction system according to either of embodiments 1 and 2, characterized in that the component B) contains a polyol having a functionality F.sub.n of 1.0 to 4.0, preferably 1.5 to 3.5, particularly preferably 1.9 to 3.0.

[0074] In a fourth embodiment the invention relates to a one-component reaction system according to any of embodiments 1 to 3, characterized in that the component B) contains a polyether polyol having an OH number of 50 to 300 mg KOH/g, preferably 75 to 275 mg KOH/g, especially preferably 100 to 250 mg KOH/g.

[0075] In a fifth embodiment the invention relates to a one-component reaction system according to any of embodiments 1 to 4, characterized in that as foam stabilizer C) compounds having a structural formula (II)

##STR00003## [0076] where x, y=integer>0 and x/y=dimethylsiloxane proportion<5, [0077] n, m=integer>0 and n/m=ethylene oxide/propylene oxide ratio; [0078] A=aryl, alkyl or H

[0079] are employed.

[0080] In a sixth embodiment the invention relates to a one-component reaction system according to any of embodiments 1 to 5, comprising the components: [0081] 30% to 70% by weight of organic polyisocyanate component A), [0082] 15% to 50% by weight of isocyanate-reactive component B), [0083] 0.2% to 4.0% by weight of a foam stabilizer C), [0084] 0.1% to 1.0% by weight of catalyst D) and [0085] 10% to 30% by weight of at least one physical blowing agent having a boiling point of less than 0° C. and optionally co-blowing agents (component E) and [0086] 0.0% to 20.0% by weight of assistant and additive substances (component F), in each case based on A)+B)+C)+D)+E)+F)=100% by weight.

[0087] In a seventh embodiment the invention relates to a one-component reaction system according to any of embodiments 1 to 6, characterized in that the isocyanate index is 350 to 550.

[0088] In an eighth embodiment the invention relates to a process for producing a one-component reaction system by reacting the organic polyisocyanate component A) with [0089] B) an isocyanate-reactive component whose isocyanate-reactive functional groups are exclusively those having at least one Zerewitinoff-reactive hydrogen atom [0090] in the presence of [0091] C) at least one foam stabilizer, [0092] D) at least one catalyst suitable for catalyzing the reaction of the semi-prepolymer with atmospheric humidity, [0093] E) at least one physical blowing agent having a boiling point of less than 0° C. and optionally co-blowing agents and [0094] F) optionally assistant and additive substances, [0095] characterized in that [0096] the isocyanate-reactive component B) contains at least 10% by weight, based on the sum of the weight fractions of A) to F)=100% by weight, of a polyether carbonate polyol.

[0097] In a ninth embodiment the invention relates to a process for producing a rigid polyurethane foam obtainable by mixing and reacting the components A) to F) of a one-component reaction system according to any of the embodiments 1 to 7 through exposure to moisture.

[0098] In a tenth embodiment the invention relates to a process for producing a rigid polyurethane foam comprising the steps of: [0099] a) producing a one-component reaction system by a process according to the eighth embodiment and [0100] b) exposing the one-component reaction system produced in step a) to moisture.

[0101] In an eleventh embodiment the invention relates to a rigid polyurethane foam obtainable by a process according to either of embodiments 9 and 10.

[0102] In a twelfth embodiment the invention relates to the use of a one-component reaction system according to any of embodiments 1 to 7 as 1-K expanding foam, wherein the one-component reaction system has been filled into a pressurized container.

[0103] In a thirteenth embodiment the invention relates to a pressurized container, in particular a single-use pressurized container, containing a one-component reaction system according to any of the embodiments 1 to 7.

[0104] In a fourteenth embodiment the invention relates to the use of rigid polyurethane foams according to the eleventh embodiment for applications in the construction industry.

[0105] Experimental Section

[0106] The rigid PUR foams according to the invention are produced by a two-stage process known to those skilled in the art in which the reaction components are discontinuously reacted with one another and then introduced into or onto suitable molds/substrates/cavities for curing. Examples are described in USA-A 2 761 565, in G. Oertel (ed.) “Kunststoff-Handbuch”, Volume VII, Carl Hanser Verlag, 3rd edition, Munich 1993, pages 284 ff., and in K. Uhlig (ed.) “Polyurethan Taschenbuch”, Carl Hanser Verlag, 2nd edition, Vienna 2001, pages 83-102.

[0107] Measurement of hydroxyl numbers was performed by NIR spectroscopy (Lambda 950, Perkin-Elmer, PC-controlled). The combination vibration of v(OH) and δ(OH) base vibrations were measured for the samples and calibration samples employed in the examples in the range from 2050 to 2100 mm The samples and calibration samples were temperature-controlled to 20° C. for the measurements. The calibration samples employed were polyether polyols whose OH number was determined according to the standard DIN 53240-2 (1998). The results of the NIR spectroscopy of the samples were compared with the results of the calibration samples by the Max-Min method to determine the OH number of the samples.

[0108] To determine the NCO content in the polyisocyanate the standard EN ISO 11909 (2007) was used.

[0109] Input Materials

TABLE-US-00002 Polyol 1 linear propylene glycol-started propylene oxide polyether, equivalent weight 501 g/mol, OH Number 112 mg KOH/g Polyol 2 glycerol-started propylene oxide polyether, equivalent weight 243 g/mol, OH Number 231 mg KOH/g Polyol 3 glycerol-started propylene oxide polyether, equivalent weight 360 g/mol, OH Number 156 mg KOH/g Polyol 4 linear propylene glycol-started polyether carbonate polyol, equivalent weight 500 g/mol, OH Number 112 mg KOH/g Polyol 5 glycerol-started polyether carbonate polyol, equivalent weight 355 g/mol, OH Number 158 mg KOH/g Polyol 6 glycerol/propylene glycol-started polyether carbonate polyol, equivalent weight 330 g/mol, OH Number 170 mg KOH/g FR flame retardant, tris(2-chloroisopropyl) phosphate (TCPP) Stab 1 polyether siloxane foam stabilizer (TEGOSTAB B 8870, Evonik) Stab 2 polyether siloxane foam stabilizer (Niax Silicone L-6164, Momentive) Stab 3 polyether siloxane foam stabilizer (TEGOSTAB B 8871, Evonik) Cell opener polysiloxane (Tegiloxan 100, Evonik) Catalyst 2,2′-dimorpholinyl diethyl ether (DMDEE) Blowing n-butane agent 1 Blowing isobutane (Merck) agent 2 Blowing dimethyl ether (Merck) agent 3 Blowing propane agent 4 Poly- Desmodur ® 44V20L, polymeric MDI having an isocyanate isocyanate content of 31.5% by weight (Covestro Deutschland AG)

[0110] Producing the 1K Formulations in Single-Use Pressurized Containers

[0111] To produce the 1K formulations in single-use pressurized containers the required amounts of the polyol components were initially charged in a mixing vessel in turn and mixed with appropriate amounts of catalyst, blowing agent and assistant and additive substances (table 2). The mixture was subsequently transferred into a single-use pressurized container. Finally the amount of polyisocyanate corresponding to the index was added to the can and the can was sealed tight with a valve. The required amounts of the blowing agents were added via the fitted valve using a suitable metering unit. Finally, the single-use pressurized container was shaken until complete homogenization of the 1K formulation. The thus-produced 1K formulations are reported hereinbelow in the examples in table 3.

[0112] Determination of Shrinkage/Swellage (Ddimensional Stability)

[0113] The rigid PUR foam is dispensed from the can into a mold (600 mm×30 mm×60 mm) which has been lined with paper and sprayed with water. The resulting rigid PUR foam strand is removed from the mold after 1 day. Thickness is measured with a thickness tester in the middle of the strand (at 300 mm) The ratio of rigid PUR foam strand thickness to mold width (30 mm) represents the dimensional stability (shrinkage/swelling). The thickness of the middle of the strand (at 300 mm) is re-measured with a thickness tester 7 days after foaming The moisture required for curing is provided through the spraying of the paper with water. This procedure is independent of the atmospheric humidity present in each case and provides the most reproducible results.

[0114] All results relating to the 1-K reaction systems produced according to the present application and the resulting rigid polyurethane foams (free-rise foams) and their properties are summarized in table 3.

TABLE-US-00003 TABLE 2 1K formulation Example 1* 2 3* 4 5* 6 Polyol 1 g 91.20 — 91.20 — 30.12 30.12 Polyol 2 g 4.96 4.96 — — — — Polyol 3 g — — 4.96 — 30.12 — Polyol 4 g — 91.20 — 91.20 — — Polyol 5 g — — — 4.96 — — Polyol 6 g — — — — — 30.12 FR g — — — — 33.13 33.13 Stab 1 g 2.48 2.48 2.48 2.48 — — Stab 2 g 0.59 0.59 0.59 0.59 — — Stab 3 g — — — — 5.42 5.42 Cell opener g 0.08 0.08 0.08 0.08 — — Catalyst g 0.69 0.69 0.69 0.69 1.20 1.20 *comparative example

TABLE-US-00004 TABLE 3 Can formulation Example 1* 2 3* 4 5* 6 Total amount of 1K g 167.4 169.36 169.36 171.66 218.80 214.65 formulation from table 2 Blowing agent 1 g — — — — 24.9 25.0 Blowing agent 2 g 53.2 53.8 53.2 53.8 7 7.1 Blowing agent 3 g 29.3 29.6 29.3 29.6 13.7 13.7 Blowing agent 4 g 15.1 15.2 15.1 15.2 27 27 Polyisocyanate g 222.24 224.83 224.83 222.19 224.70 231.23 Fill amount g 487.18 492.86 492.86 492.57 516.06 518.67 Index 460.0 460.0 460.0 460.0 500.0 500.0 Proportion of polyether % by 0 31.3 0 31.8 0 12.5 carbonate polyol in can weight formulation Dimensional stability % 4 0 −6 −0.33 −20.67 1.7 of strand after 1 day Dimensional stability % 6 0.67 −3 0 −30.67 0 of strand after 7 days *comparative example

[0115] Examples 1, 3 and 5 were produced without the use of a polyether carbonate polyol and exhibit strong swellage (example 1) and shrinkage (examples 3 and 5) of the rigid PUR foam. Substitution of the polyether polyols from example 1 and 3 by appropriate polyether carbonate polyols results in markedly reduced swellage/shrinkage of the obtained rigid PUR foams in examples 2 and 4. A markedly improved dimensional stability of the rigid PUR foam compared to example 5 is likewise obtained in example 6 through the use of at least 10% by weight, based on the sum of the parts by weight of A) to F)=100% by weight, of a polyether carbonate polyol as an isocyanate-reactive component.