PUR foam with enlarged cell structure

Abstract

Described are (a) a process for production of polyurethane foam by reacting one or more polyol components with one or more isocyanate components, wherein wax having a congealing point in the range from 40 C. to 90 C. is employed as an additive, (b) a polyurethane foam obtainable by said process, (c) the use of waxes having a congealing point in the range from 40 C. to 90 C. as an additive in the manufacture of polyurethane foams to coarsen the foam structure, and also (d) a polyurethane foam production composition containing a wax having a congealing point in the range from 40 C. to 90 C.

Claims

1. A process for production of polyurethane foam, said process comprising: reacting one or more polyol components with one or more isocyanate components in the presence of an additive, wherein the additive is a wax having a predominately microcrystalline structure and having a congealing point from 50 C. to 85 C., and wherein the wax is present in an amount from 0.0001 to 0.1 parts by weight per 100 parts by weight of polyol, and wherein the wax is in a dispersed form and is present in a dispersion medium, said dispersion medium comprising at least one organic solvent.

2. The process according to claim 1, wherein the congealing point of the wax is from 55 C. to 80 C.

3. The process according to claim 1, wherein the wax is selected from mineral waxes, synthetic waxes and mixtures thereof.

4. The process according to claim 1, wherein the wax has an entirely microcrystalline structure.

5. A polyurethane foam obtained by a process according to claim 1.

6. The polyurethane foam according to claim 5, wherein said polyurethane foam is a polyurethane flexible foam, a hot-cure flexible foam, a rigid foam, an ester foam, a viscoelastic flexible foam or a high-resilience foam (HR foam).

7. The process according to claim 1, wherein the congealing point of the wax is from 60 C. to 75 C.

8. The process according to claim 1, wherein the one or more isocyanate components comprise 2, 4-toylene diisocynate.

9. A polyurethane foam obtained by a process according to claim 2.

10. A polyurethane foam obtained by a process according to claim 3.

11. The process according to claim 1, wherein the organic solvent is an ester of a monohydric or polyhydric alcohol.

12. The process of claim 11, wherein the ester is selected from the group consisting of a glycerol ester and a sorbitol ester.

13. The process according to claim 1, wherein dispersed form of the wax comprises from 0.1 to less than 10 weight percent of the wax and at least 90 weight percent of the dispersing medium.

14. A process for production of polyurethane foam, said process comprising: reacting one or more polyol components with 2, 4-toylene diisocynate in the presence of an additive, wherein the additive is a wax having a predominately microcrystalline structure and having a congealing point from 50 C. to 85 C., and wherein the wax is present in an amount from 0.0001 to 1 parts by weight per 100 parts by weight of polyol, and wherein the wax is in a dispersed form and is present in a dispersion medium, said dispersion medium comprising a glycerol ester or a sorbital ester.

15. The process according to claim 14, wherein the congealing point of the wax is from 60 C. to 75 C.

16. The process according to claim 14, wherein the wax is selected from mineral waxes, synthetic waxes and mixtures thereof.

17. The process according to claim 14, wherein the wax has an entirely microcrystalline structure.

18. A polyurethane foam obtained by a process according to claim 14.

19. The polyurethane foam according to claim 18, wherein said polyurethane foam is a polyurethane flexible foam, a hot-cure flexible foam, a rigid foam, an ester foam, a viscoelastic flexible foam or a high-resilience foam (HR foam).

Description

EXAMPLES

(1) The raw materials mentioned in Table 1 were used to produce all the foams referred to hereinafter.

(2) TABLE-US-00001 TABLE 1 Raw materials for producing the foams polyol 1 trifunctional polyetherol, MW 3500, OHN 35, BAYER AG polyol 2 trifunctional polyetherol, OHN 29, 20% polyurea dispersion, BAYER AG polyol 3 trifunctional polyetherol, OHN 48, MW 3500, Dow Chemicals polyol 4 trifunctional polyetherol, OHZ 20, 45% styrene-acrylonitrile filled, DOW Chemicals polyol 5 trifunctional polyetherol, OHN 32, Bayer AG polyol 6 trifunctional polyetherol, OHN 30, 15 wt % styrene-acrylonitrile filled, DOW Chemicals catalyst 1 Tegoamin BDE (70% bis(2-dimethylaminoethyl) ether in dipropylene glycol), Evonik Industries AG catalyst 2 Tegoamine DEOA 85 (diethanolamine 85% in water), Evonik Industries AG catalyst 3 Tegoamin 33 (33% triethylenediamine in dipropylene glycol), Evonik Industries AG catalyst 4 triethanolamine 99% Evonik Industries AG catalyst 5 Tegoamin DMEA (dimethylethanolamine), Evonik Industries AG catalyst 6 Kosmos 29 (tin octoate), Evonik Industries AG (10% solution in polyol 1 or 3 or 6) catalyst 7 Tegoamin B 75 (75% Tegoamin 33, 25% Tegoamin BDE), Evonik Industries AG crosslinker 1 glycerol, technical grade crosslinker 2 Ortegol 204, (delayed action aqueous crosslinker preparation), Evonik Industries AG silicone stabilizer 1 Tegostab BF 2470, Evonik Industries AG (preparation of organomodified polysiloxanes) silicone stabilizer 2 Tegostab B 8680, Evonik Industries AG (preparation of organomodified polysiloxanes) silicone stabilizer 3 Tegostab B 8724 LF2, Evonik Industries AG (preparation of organomodified polysiloxanes) silicone stabilizer 4 Tegostab B 8715 LF2, Evonik Industries AG (preparation of organomodified polysiloxanes) silicone stabilizer 5 Tegostab B 8742 LF2, Evonik Industries AG (preparation of organomodified polysiloxanes) silicone stabilizer 6 Tegostab B 8707 LF2, Evonik Industries AG (preparation of organomodified polysiloxanes) mix 1 wax dispersion: Microwax with congealing point in range from 60 to 75 C. dispersed in sorbitan ester Isocyanate 1 tolylene diisocyanate, TDI 80, (80% of 2,4-isomers, 20% of 2,6- isomer), Bayer MaterialScience AG Isocyanate 2 VT 60/40, (60% TDI tolylene diisocyanate, 40% MDI Desmodur 44V20), Bayer MaterialScience AG

Example 1: As Applied to HR Slabstock Foam

(3) The formulation specified hereinbelow in table 2 was used to do a performance comparison (Comp) with the wax additive of the invention (Inv).

(4) TABLE-US-00002 TABLE 2 Formulation for production of HR slabstock foam (parts by weight per 100 parts by weight of polyol) Example Comp 1 Inv 1 Inv 2 polyol 1 60 60 60 polyol 2 40 40 40 water, total 4.20 4.20 4.20 water separate 3.78 3.78 3.78 isocyanate index 95.5 95.5 95.5 isocyanate 1 47.7 47.7 47.7 catalyst 1 0.07 0.07 0.07 catalyst 2 1.73 1.73 1.73 catalyst 3 0.5 0.5 0.5 mix 1 0 0.05 0.1 silicone stabilizer 2 1.0 1.0 1.0

(5) The foams were produced in the known manner by mixing all the components bar the isocyanate in a beaker and then admixing the isocyanate at a high stirring speed. The reaction mixture was then poured into an open 27 cm27 cm27 cm metal box lined with paper. The foamed material produced in the process had the physical properties described hereinafter.

(6) To quantify the cellular structure the foam slab was cut open and the uppermost plane of the cut surface was coloured with a black pen. A magnifying glass was used to count the number of cells within a centimeter by eye.

(7) The force-to-crush (FTC) was also measured in each case. The foams were compressed 10 times down to 50% of their height. The 1st measurement (FTC 1 in newtons) is a measure of the open-cell content of the foam. The foam was then completely crushed open (manually) in order for the 11th measurement (FTC 11 in newtons) to give the hardness of the crushed-open foam. The 1-11 value is a measure of the openability of a foam and is the arithmetic difference between an as-produced, still undamaged foam and the completely opened foam.

(8) Table 3 summarizes the comparative and inventive examples. The following mechanical properties were also measured: 40% compression load deflection to DIN EN ISO 3386 compression set to DIN EN ISO 1856 Airflow to DIN EN ISO 7231 ball rebound resilience to DIN EN ISO 8307 apparent density kg/m3 to DIN EN ISO 845 wet compression set by Toyota method TSM7100 G, Article 4.8.2 (Compression Set after Humidity Resistance) page 12 porosity (backpressure method): (EN ISO 29053)

(9) TABLE-US-00003 TABLE 3 Results for physical properties of foams Comp 1 Inv 1 Inv 2 density [kg/m.sup.3] 26.5 25.9 25.4 compression load deflection at 40% 1.8 1.8 1.8 compression/deformation/kPa compression set/% [70%, 22 h, 70 C.] 42.0 41.3 27.3 wet compression set/% [50%, 22 h, 50 C., 28.7 27.3 28.0 95% RH] cells/cm 11 10 9 FTC1/N 150 161 171 FTC11/N 64 67 68 FTC 1-11/N 86 94 103 airflow/scfm 0.36 0.42 0.40 rebound resilience/% 65 65 65

(10) The density measurement results show that no significant density fluctuations are incurred. Compression load deflection is likewise unaffected. The number of cells per centimeter decreases when the wax additive is employed, which corresponds to the foam becoming coarser.

Example 2: As Applied to HR Slabstock Foam

(11) The foam formulation specified hereinbelow in table 4 was used to do a performance comparison (Comp) with the additive mix of the invention (Inv).

(12) TABLE-US-00004 TABLE 4 Formulation for production of HR slabstock foam (parts by weight per 100 parts by weight of polyol) Example Comp 2 Inv 3 Inv 4 Inv 5 polyol 1 100 100 100 100 isocyanate index 101 101 101 101 isocyanate 1 41.02 41.02 41.02 41.02 water, total 3.0 3.0 3.0 3.0 water, separate 2.18 2.18 2.18 2.18 catalyst 1 0.1 0.1 0.1 0.1 catalyst 2 0.58 0.58 0.58 0.58 catalyst 3 0.4 0.4 0.4 0.4 catalyst 6 0.15 0.15 0.15 0.15 mix 1 0 0.05 0.1 0.2 crosslinker 2 3.0 3.0 3.0 3.0 silicone stabilizer 3 1.0 1.0 1.0 1.0

(13) The foams were produced in the known manner by mixing all the components bar the isocyanate in a beaker and then admixing the isocyanate at a high stirring speed. The reaction mixture was then poured into an open 27 cm27 cm27 cm metal box lined with paper. The foamed material produced in the process had the physical properties described hereinafter.

(14) Cellular structure and FTC were quantified by the above procedure.

(15) Table 5 summarizes the comparative and inventive examples.

(16) TABLE-US-00005 TABLE 5 Results for physical properties of foams Comp 2 Inv 3 Inv 4 Inv 5 density [kg/m.sup.3] 32.2 32.1 32.0 31.9 compression load deflection at 2.0 2.0 2.1 2.2 40% compression/deformation/kPa compression set/% [70%, 22 h, 18.0 11.3 6.0 4.0 70 C.] wet compression set/% [50%, 22 h, 20.7 19.3 16.7 19.3 50 C., 95% RH] cells/cm 11 10 9 8 FTC1/N 188 187 174 161 FTC11/N 68 70 69 73 FTC 1-11/N 120 117 105 88 airflow/scfm 0.47 0.45 0.56 0.47 rebound 65 65 65 65

(17) The density measurement results show that no significant density fluctuations are incurred. Compression load deflection is likewise not/scarcely affected. The number of cells per centimeter decreases with an increasing amount used for mix 1, which corresponds to the foam becoming coarser.

Example 3: As Applied to Conventional Flexible Slabstock Foam

(18) The foam formulation specified hereinbelow in table 6 was used to do a performance comparison (Comp) with the additive mix of the invention (Inv).

(19) TABLE-US-00006 TABLE 6 Formulation for production of flexible slabstock foam (parts by weight per 100 parts by weight of polyol) Example Comp 3 Inv 6 Inv 7 Inv 8 Inv 9 polyol 3 100 100 100 100 100 isocyanate index 110 110 110 110 110 isocyanate 1 40.10 40.10 40.10 40.10 40.1 water, total 3.0 3.0 3.0 3.0 3.0 catalyst 6 0.15 0.15 0.15 0.15 0.11 catalyst 7 0.15 0.15 0.15 0.15 0.15 mix 1 0 0.5 1.0 2.0 2.0 silicone stabilizer 1 0.8 0.8 0.8 0.8 0.8

(20) The foams were produced in the known manner by mixing all the components bar the isocyanate in a beaker and then admixing the isocyanate at a high stirring speed. The reaction mixture was then poured into an open 27 cm27 cm27 cm metal box lined with paper. The foamed material produced in the process had the physical properties described hereinafter.

(21) Cellular structure was quantified by the above procedure.

(22) TABLE-US-00007 TABLE 7 Results for physical properties of foams Comp 3 Inv 6 Inv 7 Inv 8 Inv 9 foam density [kg/m.sup.3] 30.3 30.3 30.8 31.0 31.8 compressive strength 4.2 4.2 3.9 4.2 3.8 (compressive stress at 40% compression)/ deformation in kPa compression set/% [70%, 0.0 0.0 0.0 0.0 0.0 22 h, 90 C.] wet set/% [50%, 22 h, 4.0 4.0 4.0 4.0 0 50 C., 95% RH] cells/cm 13.5 13 13 12.5 12.0 airflow/scfm 3.01 2.55 2.31 1.84 2.77 rebound resilience/% 50 50 50 50 50 porosity/mm water 26.2 30.2 33.6 50.0 23.2 column

(23) The density measurement results show that no significant density fluctuations are incurred. Compression load deflection is likewise barely affected. The number of cells per centimeter shows a decreasing tendency with increasing amount of mix 1 used, which corresponds to the foam becoming coarser. It is additionally noted that, as the proportion of mix 1 increases, the closed-cell content also increases slightly, as evidenced by the porosity. The open-cell nature of the foam is restorable by slightly adjusting the foam formulation (Inv 9).

Example 4: As Applied to HR Moulded Foam with MDI/TDI

(24) The foam formulation specified hereinbelow in table 8 was used to do a performance comparison (Comp) with the additive mix of the invention (Inv).

(25) TABLE-US-00008 TABLE 8 Formulation for production of HR moulded foam (parts by weight per 100 parts by weight of polyol) Example Comp 4 Inv 10 Inv 11 Inv 12 polyol 1 100 100 100 100 isocyanate index 102 102 102 102 isocyanate 2 46.24 46.24 46.24 46.24 water, total 3.0 3.0 3.0 3.0 catalyst 3 0.6 0.6 0.6 0.6 catalyst 4 2.0 2.0 2.0 2.0 catalyst 5 0.2 0.2 0.2 0.2 mix 1 0 0.05 0.1 0.2 silicone stabilizer 4 0.6 0.6 0.6 0.6

(26) The foams were produced in the known manner by mixing all the components bar the isocyanate in a beaker and then admixing the isocyanate at a high stirring speed. The reaction mixture was then poured into a cuboid-shaped mould of aluminium in the dimensions 404010 cm, which had been heated to 40 C., and the material was allowed to cure for 10 minutes.

(27) FTC and the number of cells per centimeter were quantified as above.

(28) TABLE-US-00009 TABLE 9 Results for physical properties of foams Comp 4 Inv 10 Inv 11 Inv 12 foam density [kg/m.sup.3] 46.0 46.1 46.0 46.1 compressive strength (compressive 2.9 2.9 3.0 3.3 stress at 40% compression)/deformation in kPa compression set/% [70%, 22 h, 0.0 0.0 0.0 0.0 70 C.] wet compression set/% [50%, 22 h, 0.0 0.0 0.0 0.0 50 C., 95% RH] cells/cm 10 9 8 5.5 FTC1/N 1047 864 716 542 FTC11/N 114 106 125 129 FTC 1-11/N 933 758 591 413 rebound resilience/% 73 72 71 70

(29) The density measurement results show that no significant density fluctuations are incurred. Compression load deflection is likewise only affected minimally. The number of cells per centimeter exhibits a distinct decrease with an increasing amount used for mix 1, which corresponds to the foam becoming coarser. It is additionally noted that there is a significant increase in the open-cell content with an increasing proportion for mix 1, as clearly indicated by FTC 1.

(30) (High FTC=high closed-cell content, low FTC=high open-cell content)

Example 5: As Applied to HR Moulded Foam with TDI

(31) The foam formulation specified hereinbelow in table 10 was used to do a performance comparison (Comp) with the additive mix of the invention (Inv).

(32) TABLE-US-00010 TABLE 10 Formulation for production of HR moulded foam (parts by weight per 100 parts by weight of polyol) Example Comp 5 Inv 13 Inv 14 Inv 15 polyol 4 26.67 26.67 26.67 26.67 polyol 5 73.33 73.33 73.33 73.33 isocyanate index 98 98 98 98 isocyanate 1 46.3 46.3 46.3 46.3 water, total 3.98 3.98 3.98 3.98 water, separate 3.83 3.83 3.83 3.83 catalyst 1 0.06 0.06 0.06 0.06 catalyst 2 1.0 1.0 1.0 1.0 catalyst 3 0.41 0.41 0.41 0.41 crosslinker 1 0.6 0.6 0.6 0.6 mix 1 0 0.1 0.2 0.3 silicone stabilizer 5 0.7 0.7 0.7 0.7

(33) The foams were produced in the known manner by mixing all the components bar the isocyanate in a beaker and then admixing the isocyanate at a high stirring speed. The reaction mixture was then poured into a cuboid-shaped mould in the dimensions 404010 cm, which had been heated to 67 C., and the material was allowed to cure for 6 minutes.

(34) FTC and the number of cells per centimeter were quantified as above.

(35) TABLE-US-00011 TABLE 11 Results for physical properties of foams Comp 5 Inv 13 Inv 14 Inv 15 foam density [kg/m.sup.3] 33.1 32.7 32.9 32.8 compressive strength (compressive 3.0 2.9 3.0 3.1 stress at 40% compression)/deformation in kPa compression set/% [70%, 22 h, 6.4 5.6 1.6 0.0 70 C.] wet compression set/% [50%, 22 h, 28.0 31.2 27.2 22.4 50 C., 95% RH] cells/cm 15 14 11 9 FTC1/N 1927 1975 2038 1767 FTC11/N 158 168 180 181 FTC 1-11/N 1769 1807 1858 1586 rebound resilience/% 60 58 54 50

(36) The density measurement results show that no significant density fluctuations are incurred. Compression load deflection is not adversely affected. The number of cells per centimeter exhibits a distinct decrease with an increasing amount used for mix 1, which corresponds to the foam becoming coarser. It is additionally noted that there is an increase in the open-cell content with an increasing proportion for mix 1, as clearly indicated by FTC 1.

Example 6: As Applied to HR Slabstock Foam (Machine Foams)

(37) Foam slabs were produced on a low-pressure foaming machine from Polytec EMC type DG 107 in an otherwise customary manner. The foaming machine was operated with the following parameters: Output of A-component (polyol mixture): 2.4 kg/min Pump pressure for polyol: 15 bar Output for B-component (isocyanate): 0.66 kg/min Pump pressure for isocyanate: 10 bar Rotary speed: 3000 rpm: Process admission pressure 5.5 bar

(38) The foam slabs were produced using the formulation itemised in table 12. The three foaming processes were each carried out by mixing all the raw materials bar the isocyanate with each other and filling the mixture as the polyol mixture into the stock reservoir container of the machine. This polyol mixture was stirred/mixed with the isocyanate in the mixing head in the particular mixing ratio. Example Comp 6 is the comparative test to Inventive Examples Inv 16 and Inv 17.

(39) TABLE-US-00012 TABLE 12 Formulation for production of HR slabstock foam (parts by weight per 100 parts by weight of polyol) Example Comp 6 Inv 16 Inv 17 polyol 6 100 100 100 isocyanate index 105 105 105 isocyanate 1 28.5 28.5 28.5 water, total 2.00 2.00 2.00 water, separate 1.79 1.79 1.79 catalyst 1 0.05 0.05 0.05 catalyst 2 1.41 1.41 1.41 catalyst 3 0.15 0.15 0.15 catalyst 6 0.15 0.15 0.15 mix 1 0 0.075 0.15 silicone stabilizer 6 0.6 0.6 0.6

(40) The reaction mixture was then poured into an open 27 cm27 cm27 cm metal box lined with paper. The foamed material produced in the process had the physical properties described hereinafter.

(41) First a slice 5 cm in thickness was cut from the side of the foam obtained. Further, 1 cm of the bottom zone was removed. Thereafter, the remaining foam core was cut into a layer 12 cm high.

(42) FTC and the number of cells per centimeter were quantified as above.

(43) The results of these determinations are reported in Table 13.

(44) TABLE-US-00013 TABLE 13 Results for physical properties Comp 6 Inv 16 Inv 17 cells/cm 10 9.5 8.5 FTC1/N 166 130 125 FTC11/N 129 106 105 FTC 1-11/N 37 24 20

(45) As regards the number of cells, the inventive examples show that the use of mix 1 also leads to a coarsened cellular structure in this case. The force-to-crush values (FTC1) also reveal that Foams Inv 16 and Inv 17 have a higher open-cell content.