POLYURETHANE FOAM

Abstract

A polyurethane foam is disclosed having unique load bearing characteristics rendering it suitable for a variety of applications. The foam exhibits high surface-softness and smoothness properties, making it well-suited for use in articles such as pillows and mattress toppers. However, upon continued application of pressure, the resilience of the foam increases sharply, translating into a remarkable support characteristics that make the foam suitable for use in the seat portions of chairs and sofas, as well as in the base portion of mattresses. The foams therefore address the limitations of conventional, high-resilience and visco-elastic polyurethane foams. A process of making the foam and its use in various articles is also disclosed.

Claims

1.-42. (canceled)

43. A polyurethane foam having a sag value of 2.8-3.5, wherein the sag value is calculated according to the following expression: $\mathrm{Sag}\mathrm{Value}=\frac{\mathrm{IFD}65\%}{\mathrm{IFD}25\%}$ and wherein IFD65% and IFD25% values are determined according to the protocol set forth in ISO 2439:2008.

44. The polyurethane foam of claim 42, wherein the polyurethane foam has a sag value of 3.0-3.5.

45. The polyurethane foam of claim 43, wherein the polyurethane foam has an IFD25% value of 10-40, wherein the IFD25% value is determined according to the protocol set forth in ISO 2439:2008.

46. The polyurethane foam of claim 43, wherein the polyurethane foam has an IFD40% value of 33-80, wherein the IFD40% value is determined according to the protocol set forth in ISO 2439:2008.

47. The polyurethane foam of claim 43, wherein the polyurethane foam has an IFD65% value of 50-115, preferably 690, wherein the IFD65% value is determined according to the protocol set forth in ISO 2439:2008.

48. The polyurethane foam of claim 43, wherein the polyurethane foam has: an IFD25% value of 10-40, an IFD40% value of 33-80, an IFD65% value of 50-115, and the IFD25% and IFD65% values are such that the sag value is 3.0-3.5.

49. The polyurethane foam claim 43, wherein the polyurethane foam has: an IFD25% value of 20-30, an IFD40% value of 40-70, an IFD65% value of 70-95, and the IFD25% and IFD65% values are such that the sag value is 3.0-3.5.

50. The polyurethane foam of claim 43, wherein the polyurethane foam has a density of 35-60 kg/m.sup.3.

51. The polyurethane foam of claim 43, wherein the polyurethane foam comprises a polyurethane formed by the reaction of at least one polyol having a molecular weight of 6,000-12,000 Da and an OH functionality of 2-4 with at least one methylene diphenyl diisocyanate having an NCO content of 26-33%.

52. The polyurethane foam of claim 43, wherein the polyurethane foam comprises one or more of a chlorinated phosphate ester and a halogen-free phosphate ester fire retardant, or a residue thereof.

53. The polyurethane foam of claim 43, wherein the polyurethane foam exhibits BS5852 Crib5 fire retardancy.

54. An article comprising a polyurethane foam according to claim 43.

55. The article of claim 54, wherein the article is a pillow, cushion, mattress, mattress topper, sofa, chair, seat or footwear insole.

56. The polyurethane foam of claim 43, wherein the polyurethane foam has a sag value of 3.1-3.4.

57. The polyurethane foam of claim 43, wherein the polyurethane foam has an IFD25% value of 20-30, wherein the IFD25% value is determined according to the protocol set forth in ISO 2439:2008.

58. The polyurethane foam of claim 43, wherein the polyurethane foam has an IFD40% value of 40-70, wherein the IFD40% value is determined according to the protocol set forth in ISO 2439:2008.

59. The polyurethane foam of claim 43, wherein the polyurethane foam has an IFD65% value of 60-90, wherein the IFD65% value is determined according to the protocol set forth in ISO 2439:2008.

60. The polyurethane foam of claim 43, wherein the polyurethane foam has a density of 40-60 kg/m.sup.3.

61. The polyurethane foam of claim 43, wherein the polyurethane foam has a density of 40-55 kg/m.sup.3.

62. The polyurethane foam of claim 43, wherein the polyurethane foam has a density of 45-50 kg/m.sup.3.

Description

EXAMPLES

[0745] One or more examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figures, in which:

[0746] FIG. 1 shows a continuous foam forming process used in the preparation of the foams of the examples and comparative examples. The process parameters were: mixing head pressure0.3 MPa; air injection0.1 L/min; raw materials temperature22 C.; foaming speed4.0 m/min; mixing head mixing speed5000 rpm.

[0747] FIG. 2 shows a box foaming (discontinuous) process.

MATERIALS AND METHODS

[0748] In following examples, the components used were: [0749] Polyol A: Caradol SC56-02 (560H value, 3000 mwt), available from Shell Chemicals Company; [0750] Polyol B: GLR2000 (2400H value, 700 mwt), available from Sinopec Shanghai Gaoqiao Chemical Company; [0751] Active Polyol C: polyol 330N (330H value 5000 mwt), available from Sinopec Shanghai Gaoqiao Chemical Company; [0752] Active polyol D: polyol GEP828 (28 OH value 8000 mwt) from Sinopec Shanghai Gaoqiao Chemical Company; [0753] Flame retardant FR508, available from Yoke Chemicals Company; [0754] Flame retardant synergist: melamine; [0755] Surfactant A: B2470, available from Evonik; [0756] Amine catalyst: Niax A1 (available from Momentive) and Dabco 33-LV (available from Air product); [0757] Tin Catalyst: K29 from Enovik; [0758] Toluene diisocyanate (TDI) is available from BASF; [0759] Modified methylene diphenyl diisocyanate (MDI) 6510, available from Huntsmen Chemicals Company (NCO % 29.9); [0760] Surfactant B: B8002, available from Evonik; [0761] Surfactant L5333 from Momentive; [0762] Cell opener: PK101, available from Fushun Chemical Company; [0763] Cell opener: KZ28, available from Nanjing Aosai Chemical Co. [0764] Blow agent: Methylene chloride; [0765] Chain extender/cross linker: Diethanol amine.

[0766] In the following examples, foams were prepared using the continuous foaming process depicted in FIG. 1.

Example 1

[0767] Having regard to Table 1 below, a flexible polyurethane foam was prepared according to the continuous foaming process depicted in FIG. 1 using the ingredients and amounts specified.

TABLE-US-00001 TABLE 1 Ingredients used in the preparation of flexible polyurethane foam of Example 1 Flow rate to mixer Ingredients Parts/php* head (kg/min) Active polyol D 100 120 Flame retardant FR 508 7 8.4 Melamine 10 12 H.sub.2O 3.2 3.84 Methylene chloride 7 8.4 Surfactant L5333 0.55 0.66 Amine catalyst 0.3 0.36 Tin Catalyst 0.03 0.04 Cell opening agent 3 3.6 Diethanol amine 0.8 0.96 Modified MDI 40** 48 *per hundred parts polyol; **amount of MDI was sufficient to give an ISO index of 75.

[0768] After forming, the foam was left to cure at room temperature for 72 hours.

[0769] The properties (density, sag value and fire retardancy) of the cured flexible polyurethane foam of Example 1 were then assessed. The results are presented in Table 2 below.

TABLE-US-00002 TABLE 2 Density, sag value and fire retardancy properties of flexible polyurethane foam of Example 1 Foam density (kg/m.sup.3) 45 IFD25%/N 22.1 IFD40%/N 34.8 IFD65%/N 72.2 Sag value (IFD65%/IFD25%) 3.3 BS5852 crib5 fire retardancy Pass, 34 g mass loss

[0770] As can be seen from the data presented in Table 2, the IFD25% of the flexible polyurethane foam of Example 1 is 22.1N, which is substantially lower than that observed for conventional, HR and visco-elastic polyurethane foams. This value reflects the high surface softness and smoothness of the flexible polyurethane foam of Example 1 when compared with other polyurethane foams. However in spite of the high surface softness and smoothness, the data presented in Table 2 illustrate that the sag value of the flexible polyurethane foamwhich is typically used to gauge the level of comfort offered by a foamis 3.3, which is notably higher than that observed for conventional, HR and visco-elastic polyurethane foams. This means that the foam of Example 1, despite having excellent surface softness and smoothness characteristics, also offers remarkable support, without excessive sinking. This is likely due to the fact that whilst the upper surface of the foam is soft, the firmness of the foam increases sharply upon continued application of pressure.

[0771] In addition to the above, the flexible polyurethane foam of Example 1 meets the BS5852 crib 5 flammability standarda UK requirement which is perhaps the most stringent of all international flame retardancy standards. Achieving high surface-softness, high sag value and BS5852 crib 5 compliance in a single polyurethane foam is particularly advantageous.

Comparative Example 2Conventional Flame-Retardant Polyurethane Foam

[0772] Having regard to Table 3 below, a flexible conventional flame-retardant polyurethane foam was prepared according to the continuous foaming process depicted in FIG. 1 using the ingredients and amounts specified.

TABLE-US-00003 TABLE 3 Ingredients used in the preparation of flexible polyurethane foam of Comparative Example 2 Flow rate to mixer Ingredients Parts/php* head (kg/min) Polyol, A 100 150 Flame retardant FR508 15 22.5 Melamine 30 45 H.sub.2O 3.2 4.8 Methylene chloride 3 4.5 Surfactant A 1.2 1.8 Amine catalyst 0.3 0.45 Tin Catalyst 0.24 0.36 TDI (NCO %: 48.3) 45.6** 68.4 *per hundred parts polyol; **amount of TDI was sufficient to give an ISO index of 115.

[0773] After forming, the foam was left to cure at room temperature for 72 hours.

[0774] The properties (density, sag value and fire retardancy) of the cured flexible polyurethane foam of Comparative Example 2 were then assessed. The results are presented in Table 4 below.

TABLE-US-00004 TABLE 4 Density, sag value and fire retardancy properties of flexible polyurethane foam of Comparative Example 1 Foam density (kg/m.sup.3) 32 IFD25%/N 85.5 IFD40%/N 123.2 IFD65%/N 189.5 Sag value (IFD65%/IFD25%) 2.2 BS5852 crib5 Pass, 32 g mass loss

[0775] The foam of Comparative Example 2 is a typical BS5852 Crib5-compliant conventional polyurethane foam. Despite being fire retardant, the conventional polyurethane foam of Comparative Example 2 has an extremely high IFD25% value, which manifests itself as poor surface softness characteristics. As a consequence, the foam of Comparative Example 2 is only suitable for use as a base layer in mattresses, and cannot be used in the upper surface on which a consumer sleeps.

Comparative Example 3Visco-Elastic Polyurethane Foam

[0776] Having regard to Table 5 below, a flexible polyurethane visco-elastic foam was prepared according to the continuous foaming process depicted in FIG. 1 using the ingredients and amounts specified.

TABLE-US-00005 TABLE 5 Ingredients used in the preparation of flexible polyurethane foam of Comparative Example 3 Flow rate to mixer Ingredients Parts/php* head ( kg/min ) Polyol A 50 75 Polyol B 50 75 H.sub.2O 2 3 Surfactant B 0.8 1.2 Amine catalyst 0.4 0.6 Tin Catalyst 0.08 0.12 cell open agent 4 6 TDI ( NCO %: 48.3) 37.2** 55.8 *per hundred parts polyol; **amount of TDI was sufficient to give an ISO index of 88.

[0777] After forming, the foam was left to cure at room temperature for 72 hours.

[0778] The properties (density, sag value and fire retardancy) of the cured flexible polyurethane visco-elastic foam of Comparative Example 3 were then assessed. The results are presented in Table 6 below.

TABLE-US-00006 TABLE 6 Density, sag value and fire retardancy properties of flexible polyurethane foam of Comparative Example 3 Foam density (kg/m.sup.3) 43 IFD25%/N 30.4 IFD40%/N 43.6 IFD65%/N 60.2 Sag value ( IFD65%/IFD25%) 2.0 BS5852 crib5 Fail, burnt out

[0779] The foam of Comparative Example 3 is a visco-elastic foam that is widely used in pillows, mattresses and mattress toppers. Although visco-elastic foams offer softness and are able to conform to the body in order to distribute body pressure evenly, they suffer from the standpoint of providing sufficient support. As can be seen from the data presented in Table 6, sag value of the visco-elastic foam of Comparative Example 3 is only 2.0, which translates to a consumers feeling that they are sunken into the foam, rather than being properly supported by it.

Comparative Example 4Flame-Retardant HR Polyurethane Foam

[0780] Having regard to Table 7 below, a flexible polyurethane HR foam was prepared according to the continuous foaming process depicted in FIG. 1 using the ingredients and amounts specified.

TABLE-US-00007 TABLE 7 Ingredients used in the preparation of flexible polyurethane foam of Comparative Example 4 Flow rate to mixer Ingredients Parts/php head (kg/min)* Active polyol C 100 150 Flame retardant 8 12 Melamine 15 18 H.sub.2O 3 4.5 Methylene chloride 3 4.5 Surfactant C 0.6 0.9 Amine catalyst 0.3 0.45 Tin Catalyst 0.1 0.15 Diethanol amine 1 1.5 TDI (NCO %: 48.3) 40.2** 60.3 *per hundred parts polyol; **amount of TDI was sufficient to give an ISO index of 110.

[0781] After forming, the foam was left to cure at room temperature for 72 hours.

[0782] The properties (density, sag value and fire retardancy) of the cured flexible polyurethane HR foam of Comparative Example 4 were then assessed. The results are presented in Table 8 below.

TABLE-US-00008 TABLE 8 Density, sag value and fire retardancy properties of flexible polyurethane foam of Comparative Example 4 Foam density (kg/m.sup.3) 31 IFD25%/N 67.4 IFD40%/N 100.5 IFD65%/N 182 Sag value 2.7 (IFD65%/IFD25%) BS5852 crib5 Pass, 35 g mass loss

[0783] The foam of Comparative Example 4 is a typical BS5852 Crib5-compliant HR polyurethane foam. The foam exhibits good support properties, due in part to the higher molecular weight of polyol used in comparison to conventional and visco-elastic foams, which makes the HR foam widely useable in the seat portion of chairs and sofas. However, the HR polyurethane foam of Comparative Example 4 has an extremely high IFD25% value, which manifests itself as poor surface softness characteristics. As a consequence, the foam of Comparative Example 4 is unsuitable for use in pillows and mattress toppers, wherein high surface-softness is necessary.

Example 5

[0784] Having regard to Tables 9 and 10 below, various polyurethane foams were prepared according to the continuous foaming process depicted in FIG. 1 using the ingredients and amounts specified.

TABLE-US-00009 TABLE 9 Composition and properties of various polyurethane foams Foam 1 2* 3 4* 5 6 FOAM COMPOSITION Active polyol D 100 100 100 100 100 100 Cell opener 3 3 3 3 3 5 KZ28/phpp Flame retardant 3 20 12 12 12 0 FR508/phpp Melamine/phpp 15 15 15 15 15 0 Silicone surfactant 0.7 0.7 0.7 0.7 0.7 0.7 L5333/phpp Amine catalyst/phpp 0.5 0.5 0.5 0.5 0.5 0.5 Tin catalyst/phpp 0.05 0.05 0.05 0.05 0.05 0.05 H2O/phpp 2 2 4 1 2 2 Blow agent/phpp 5 5 5 5 5 2 TEOA/phpp 0.6 0.6 0.6 0.6 0.6 0.6 ISO index** 90 90 90 90 90 100 FOAM PROPERTIES Cream time/s 10 12 8 30 10 8 Full rising time/s 163 183 125 N/A 172 159 Foam density/kg/m3 54.2 60.4 36.3 N/A 57.2 55.2 IFD 25/40/65(N) 29/43/91 29.3/41.1/78.2 39.5/62/110.2 N/A 25.2/41.3/77.2 23.5/40.3/79.2 Sag value 3.1 2.67 2.8 N/A 3.1 3.4 Ball resilience/% 62 52 50 N/A 65 69 Overall foam physical 5 2 3 N/A 5 5 performance (1-5; 1 = poor, 5 = excellent) FR BS5852 crib 5 test Fail. Foam Pass. Mass Fail. Foam N/A Pass. Mass Fail. Foam continued burning loss 38 g continued loss 35 g continued after 10 mins. after 4 mins burning after after 4 mins burning after Mass loss >60 g 35 sec 10 mins. 55 sec 10 mins. Mass loss >60 g Mass loss >60 g Comments Foam exhibits BS5852 crib Higher water Low water BS5852 crib Foam exhibits excellent 5 compliant, content gave content 5 compliant excellent physical physical properties. but high con- rise to certain hampered and excellent properties. Lack Not enough tent of flame defects in foam, foam rising. physical of flame flame retardant retardant and overall Sample not properties retardant meant to confer BS5852 compromised poorer cured foam was not crib 5 compliance physical proper- physical BS5852 crib ties of foam properties 5 compliant *comparative example; **ISO index achieved by adding appropriate amount of modified MDI; phpp-per hundred parts polyol

TABLE-US-00010 TABLE 10 Composition and properties of various polyurethane foams Foam 7* 8* 9* 10* 11* 12* FOAM COMPOSITION Active polyol D 100 100 100 100 100 100 Cell opener 3 3 3 3 3 3 KZ28/phpp Flame retardant 12 12 12 12 12 12 FR508/phpp Melamine/phpp 15 15 15 15 15 15 Silicone surfactant 0.7 0.7 0.7 0.7 0.1 2 L5333/phpp Amine catalyst/phpp 0.1 1 0.5 0.5 0.5 0.5 Tin catalyst/phpp 0.05 0.05 0.05 0.05 0.05 0.05 H2O/phpp 2 2 2 2 2 2 Blow agent/phpp 5 5 5 5 5 2 TEOA/phpp 0.6 0.6 0.6 0.6 0.6 0.6 ISO index** 90 90 70 120 90 90 FOAM PROPERTIES Cream time/s 40 2 16 8 11 10 Full rising time/s NA 81 192 150 NA 172 Foam density/kg/m3 NA NA 65.2 55.2 NA NA IFD 25/40/65(N) NA NA 14.2/24.2/45.2 40.4/65.8/110.8 NA NA Sag value NA NA 3.2 2.7 NA NA Ball resilience/% NA NA 53 52 NA NA Overall foam physical NA 1 2 2 1 1 performance (1-5; 1 = poor, 5 = excellent) FR BS5852 crib 5 test NA NA Fail. Foam Pass. Mass NA NA continued burning loss 28 g after 10 mins. after 3 Mass loss >60 g mins 56 sec Comments Insufficient Excessive amount Low ISO index High ISO Insufficient Excessive amount of of amine resulted in index resulted amount of amount amine catalyst caused overly soft in overly surfactant of surfactant catalyst foam to rise foam having firm foam led to led to for foam too quickly, poor support having larger cells, closed cell to rise causing characteristics. a closed causing foam structure, splitting Flame cell structure collapse while causing retardancy also and poor rising foam shrinkage compromised surface after curing smoothness *comparative example; **ISO index achieved by adding appropriate amount of modified MDI; phpp-per hundred parts polyol

[0785] The results presented in Tables 9 and 10 illustrate the effect of varying the amount of the various ingredients of the foam.

[0786] While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.