COMPATIBILIZED BLENDS OF TEREPHALATE ESTER POLYOLS AND HYDROCARBON BLOWING AGENTS

Abstract

Formulated polyol compositions contain a terephthalic acid-based polyester polyol, a C4-7 hydrocarbon blowing agent, and a nonionic surfactant that has a hydrophilic-lipophilic balance of greater than 13 to 18.5. The formulated polyol compositions exhibit surprisingly good storage stability and resist stratifying into layers. The compositions are useful to make rigid polyurethane and/or polyisocyanurate foams. The good compatibility of the blowing agent leads to improved cell structure in the foams.

Claims

1. A formulated polyol composition comprising: a) at least one polyester polyol containing one or more terephthalic acid ester groups, the polyester polyol having a number average of at least 1.5 hydroxyl groups per molecule and a hydroxyl number of 150 to 350, or a mixture of at least 50 weight-% based on the weight of the mixture of the polyester polyol with up to 50 weight-% of one or more other polyols having a number average of at least 1.5 hydroxyl groups per molecule and a hydroxyl number of 150 to 350; b) 5 to 30 parts by weight, per 100 parts by weight of component a), of one or more aliphatic hydrocarbons having 4 to 7 carbon atoms; c) 0.25 to 20 parts by weight, per 100 parts by weight of component a), of one or more nonionic surfactants having a hydrophilic-lipophilic balance (HLB) of greater than 13 and up to 18.5.

2. The formulated polyol composition of claim 1 wherein the nonionic surfactant is selected from the group consisting of an ethoxylate of a fatty alcohol and/or fatty acid; a block copolymer of propylene oxide and/or butylene oxide and ethylene oxide; and an ethoxylate of a polyethylene oligomer, and the nonionic surfactant has an HLB of 14 to 18.

3. The formulated polyol composition of claim 2 which contains 0.5 to 10 parts by weight of the nonionic surfactant per 100 parts by weight of component a).

4. The formulated polyol composition of claim 2 wherein the polyester polyol containing one or more terephthalic acid ester groups has a number average of 2 to 2.5 hydroxyl groups per molecule and a hydroxyl number of 200 to 275.

5. The formulated polyol composition of claim 2 wherein the polyester polyol containing one or more terephthalic acid ester groups does not contain a pendant aliphatic hydrocarbon group having 6 or more carbon atoms.

6. The formulated polyol composition of claim 2 wherein the polyester polyol containing one or more terephthalic acid ester groups constitutes at least 85% of the weight of component a).

7. The formulated polyol composition of claim 2 wherein component c) includes at least 95% by weight of one or more pentane isomers.

8. The formulated polyol composition of claim 2 further comprising d) one or more foam-stabilizing surfactants and e) one or more urethane and/or isocyanate trimerization catalysts.

9. A method of making a polymeric foam, comprising A) forming a reaction mixture containing a) at least one polyester polyol containing one or more terephthalic acid ester groups, the polyester polyol having a number average of at least 1.5 hydroxyl groups per molecule and a hydroxyl number of 150 to 350, or a mixture of at least 50 weight-% based on the weight of the mixture of the polyester polyol with up to 50 weight-% of one or more other polyols having a number average of at least 1.5 hydroxyl groups per molecule and a hydroxyl number of 150 to 350; b) 5 to 30 parts by weight, per 100 parts by weight of component a), of one or more aliphatic hydrocarbons having 4 to 7 carbon atoms; c) 0.5 to 20 parts by weight, per 100 parts by weight of component a), of one or more nonionic surfactants having a hydrophilic-lipophilic balance (HLB) of greater than 13 and up to 18.5; d) one or more foam-stabilizing surfactants; e) one or more urethane and/or trimerization catalysts and f) at least one organic polyisocyanate in an amount sufficient to provide an isocyanate index of at least 90 and B) curing the reaction mixture under conditions such that component b) volatilizes and components a) and f) react to produce the polymeric foam.

10. The method of claim 9 wherein the nonionic surfactant is selected from the group consisting of an ethoxylate of a fatty alcohol and/or fatty acid; a block copolymer of propylene oxide and/or butylene oxide and ethylene oxide; and an ethoxylate of a polyethylene oligomer, and the nonionic surfactant has an HLB of 14 to 18.

11. The method of claim 10 wherein which contains 0.5 to 10 parts by weight of the nonionic surfactant per 100 parts by weight of component a).

11. The method of claim 10 wherein the polyester polyol containing one or more terephthalic acid ester groups has a number average of 2 to 2.5 hydroxyl groups per molecule and a hydroxyl number of 200 to 275.

13. The method of claim 10 wherein the polyester polyol containing one or more terephthalic acid ester groups does not contain any pendant aliphatic hydrocarbon groups of 6 or more carbon atoms.

14. The method of claim 10 wherein the polyester polyol containing one or more terephthalic acid ester groups constitutes at least 85% of the weight of component a).

15. The method of claim 10 wherein component c) includes at least 95% by weight of one or more pentane isomers.

Description

Examples 1 and 2 and Comparative Sample A

[0075] Blends of Polyol A and various surfactants, at various surfactant concentrations, are evaluated for n-pentane retention and % upper phase volume in the manner described above. Solid surfactants are melted before blending with the polyol. The surfactants are:

[0076] For Comp. Sample A: An oligoethylene block-poly(ethylene glycol) containing 67% oxyethylene units. This surfactant has a molecular weight of 642 g/mol and an HLB of 12.6 (Surfactant A). It is a room temperature liquid.

[0077] For Ex. 1: A block copolymer of ethylene oxide and propylene oxide having a molecular weight of 5900 and an HLB of 15 (Surfactant B). This surfactant is a waxy solid at room temperature.

[0078] For Ex. 2: An oligoethylene block-poly(ethylene glycol) containing 90% oxyethylene units. This surfactant is a room temperature solid having a molecular weight of 1960 g/mol and an HLB of 18 (Surfactant C).

[0079] Results of the testing are as indicated in Table 2.

TABLE-US-00002 TABLE 2 Comp. A Ex. 1 Ex. 2 % Surfactant.sup.1 Surfactant HLB (parts 12.6 15 18 surfactant % Upper % Upper % Upper per 100 part Retained Phase Retained Phase Retained Phase Polyols A) n-pentane Volume n-pentane Volume n-pentane Volume .sup. 10 (11.1) 65.5 10 N.D. N.D. N.D. N.D. .sup. 5 (5.3) 66.7 10.3 80.0 0  N.D. N.D. .sup. 2 (2.2) N.D. N.D. 68.7 N.D. N.D. N.D. 1 (1) N.D. N.D. 75.3 12.5 65.6 0 0.5 (0.5) N.D. N.D. 56.7 14.8 56.0 0 0.25 (0.25) N.D. N.D. 54.7 13.2 67.3 5.7 *Comparative. .sup.1Based on combined weight of surfactant and polyol.

[0080] This data demonstrates the effect of surfactant HLB on compatibility. A surfactant with an HLB of 12.6 (Comp. Sample A) is poorly effective even when used at high concentrations of 5-10%. Mixtures containing that surfactant stratify easily upon standing.

[0081] In Example 1, the presence of 5% of a surfactant with an HLB of 15 results in very high retained n-pentane and no stratification into layers. A surfactant level as low as 1% results in better n-pentane retention than 5% of the 12.6 HLB surfactant of Comp. Sample A.

[0082] In Example 2, the 18 HLB surfactant, at levels as low as 0.25%, is at least as effective as 5% of the 12.6 HLB surfactant of Comp. Sample A in retaining n-pentane and preventing stratification. No stratification is seen even at the 0.5% surfactant level, and at the 1% surfactant level the retained n-pentane is as high as seen with 5% surfactant in Comparative Sample A.

Examples 3-4 and Comparative Samples B-C

[0083] Blends of Polyol A and various surfactants are evaluated for n-pentane retention and % upper layer volume in the manner previously described. The amount of surfactant and results of the testing are as indicated in Table 3.

[0084] The surfactants used in the various experiments are: [0085] Comp. B: A liquid triblock copolymer having a central poly(propylene oxide) blocks and terminal poly(ethylene oxide) blocks. This surfactant has a molecular weight of 2900 and an HLB of 8 (Surfactant D). [0086] Comp. C: A solid (at room temperature) triblock copolymer having a central poly(propylene oxide) blocks and terminal poly(ethylene oxide) blocks. This surfactant has a molecular weight of 2000 and an HLB of 10 (Surfactant E). [0087] Comp. D: A liquid oligoethylene block poly(ethylene glycol) having a molecular weight of 420 and an HLB of 11 (Surfactant F). [0088] Ex. 3: A room temperature solid PO-EO-PO triblock copolymer having a molecular weight of 8400 and an HLB of 16 (Surfactant G). [0089] Ex. 4: A room temperature solid polyethylene/polyethylene glycol block copolymer. It has a molecular weight of 2250 and an HLB of 16 (Surfactant H).

TABLE-US-00003 TABLE 3 Comp. B* Comp. C* Comp D* Ex. 3 Ex. 4 Surfactant HLB 8 10 11 16 16 % Surfactant.sup.1 (parts 5 (5.3) 5 (5.3) 5 (5.3) 1 (1) 1 (1) surfactant per 100 part Polyols A) Retained n-pentane, % 30 37 45 59 49 % Upper phase volume 8.8 14.0 9.6 0 0 *Comparative. .sup.1Based on combined weight of surfactant and polyol.

[0090] The higher amounts of retained n-pentane and lower upper phase volumes of the examples of the invention are clear indications of improved compatibilization of the blowing agent and terephthalate-based polyester polyol.

[0091] Sandwich panels having outer metal facing layers and a central foam layer are prepared using the following standard foam formulation. All ingredients except the polyisocyanate are formed into a polyol composition. The polyol composition is then combined with the polyisocyanate to produce a reaction mixture that is applied onto one of the metal facing layers and formed into a layer. The other facing layer is brought into position above the layer of the polyol composition. The polyol composition rises and cures in contact with the facing layers to form a urethane-modified polyisocyanurate foam having a thickness of 10 mm and a foam density as indicated in Table 4. The amount and type of surfactant also are as indicated Table 4.

TABLE-US-00004 Standard Foam Formulation Ingredient Parts by Weight Polyol A 87.9 Surfactant.sup.1 .sup.1 Triethyl phosphate 9.9 Silicone surfactant 3.8 Water 0.6 Amine catalysts 0.58 Trimerization catalyst 1.6 70/30 cis-/isopentane 20 mixture Polymeric MDI.sup.2 To 400 index .sup.1See Table 4. .sup.2Isocyanate content 30-31.4%, isocyanate functionality 2.8.

[0092] Tensile bond strength is measured on the resulting panels. 50 mm×50 mm×10 mm (foam thickness) sections are cut. A tensile force is applied perpendicular to the plane of the metal facings, and the force required to separate the foam from one of the metal facings is measured.

[0093] Surface smoothness is evaluated as an indication of how well the blowing agent became compatibilized in the polyol formulations. After removing a metal facing layer, the resulting exposed foam surface is painted black with a roller. Photos of the painted surface are taken. The images are processed using IMAGEJ Version 1.52A software, by selecting process/binary/operations and checking the “black background” box, so pixels with value 0 are shown as black and those set at 255 are shown as white. Using the threshold tool, the image/adjust/threshold is selected and the “dark background” box is checked. The lower threshold is adjusted to a value that will highlight most of the pixels in red, and “apply” is selected to obtain a binary image. Edit/selection/create selection is selected to select only the white pixels. By selecting analyze/measure, an area value is produced that represents white pixels, which is an indication of the surface smoothness.

[0094] Results of the testing are as indicated in Table 4.

TABLE-US-00005 TABLE 4 Surfactant type, amount.sup.1 (parts per 100 parts of Polyol A) D, 5% E, 5% B, 5 G, 1 H, 1 C, 1 (5.3) (5.3) (5.3) (1) (1) (1) HLB 8 10 15 16 16 18 Foam Density, g/L 39.5 38.5 43.5 38.5 39 40 TB.sup.2, bottom, kPa 180 180 200 150 200 200 TBS.sup.2, top, kPa 130 150 150 150 100 150 Smooth surface, % 41 52 70 77 80 86 .sup.1Based on combined weight of surfactant and polyol. .sup.2TBS is tensile bonding strength.

[0095] As shown in Table 4, the foams made using surfactants having an HLB of 15-18 have much smoother surfaces than those made with a surfactant having a lower HLB. The improved surface smoothness is an indication of better compatibilization of the pentane blowing agent into the terephthalate-based polyester polyol. Adhesion to the metal facing panels remains good and foam density is essentially unchanged.