PHENOLIC FOAM

Abstract

A phenolic foam formed from a composition comprising a phenolic resin, a blowing agent, an acid catalyst, and a surfactant comprising: (i) an ethoxylated castor oil, and (ii) a polysiloxane comprising a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises less than 50% of the total molecular weight of the polysiloxane.

Claims

1-45. (canceled)

46. A phenolic foam formed from a composition comprising: a phenolic resin, a blowing agent, an acid catalyst, and a surfactant comprising: (i) an ethoxylated castor oil, and (ii) a polysiloxane comprising a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises less than 50% of the total molecular weight of the polysiloxane.

47. The phenolic foam as claimed in claim 46 wherein the polysiloxane has a molecular weight of from about 9,500 to about 25,000 g/mol.

48. The phenolic foam as claimed in claim 46 wherein the surfactant has a hydrophilic to lipophilic balance (HLB) of between about 9 to about 13.

49. The phenolic foam as claimed in claim 46, wherein the side chain comprises propylene oxide.

50. The phenolic foam as claimed in claim 46, wherein the polysiloxane comprises a block copolymer of a dimethylsiloxane and a polyoxyalkyene.

51. The phenolic foam as claimed in claim 46, wherein the polysiloxane has a HLB of from about 7 to about 11.

52. The phenolic foam as claimed in claim 46, wherein the ethoxylated castor oil has a HLB of from about 12 to about 14.

53. The phenolic foam as claimed in claim 46, wherein the composition comprises ethoxylated castor oil from about 0.5 to about 10 parts per 100 parts of the phenolic resin.

54. The phenolic foam as claimed in claim 46, wherein the surfactant comprises 10% to 30% polysiloxane by weight based on the total weight of the surfactant.

55. The phenolic foam as claimed in claim 46, wherein the mixture of phenolic resin and surfactant of the composition has a viscosity of from about 2,600 cPs to about 4,000 cPs at 40° C.

56. The phenolic foam as claimed in claim 46, wherein the phenolic resin has a free formaldehyde content of from about 0.1% to about 0.5% when measured by titration according to ISO 11402:2004.

57. The phenolic foam as claimed in claim 46, wherein the blowing agent comprises a C.sub.1-C.sub.7 hydrocarbon, a C.sub.2 to C.sub.5 halogenated hydrocarbon, or a halogenated hydroolefin, or combination thereof.

58. The phenolic foam as claimed in claim 46, wherein the blowing agent comprises a halogenated hydroolefin selected from the group consisting of hydrofluoroolefins and hydrochlorofluoroolefins.

59. The phenolic foam as claimed in claim 46, wherein the blowing agent of the composition comprises from about 20 wt % to about 80 wt % C.sub.1-C.sub.7 hydrocarbon of total weight of blowing agent.

60. The phenolic foam as claimed in claim 46, wherein the blowing agent of the composition comprises from about 20 wt % to about 80 wt % halogenated hydroolefin of total weight of blowing agent.

61. The phenolic foam as claimed in claim 46, wherein the blowing agent comprises from 30 wt % to 50 wt % 1-chloro-3,3,3-trifluoropropene and from 50 wt % to 70 wt % C.sub.1-C.sub.7 hydrocarbon based on the total weight of the blowing agent.

62. The phenolic foam as claimed in claim 46, wherein the phenolic foam has a density of from about 10 kg/m.sup.3 to about 100 kg/m.sup.3 as measured according to ASTM D1622-14.

63. The phenolic foam as claimed in claim 46, wherein the phenolic foam has a compressive strength of from about 110 kPa to about 220 kPa, as measured by BS EN 826:2013.

64. The phenolic foam as claimed in claim 46, wherein the phenolic foam has an aged thermal conductivity of 0.022 W/m.Math.K or less when measured after aging for 14 days at 110° C. as measured according to 13166:2012.

65. A phenolic foam composition comprising: a phenolic resin, a blowing agent, an acid catalyst, and a surfactant comprising: (i). an ethoxylated castor oil, and (ii). a polysiloxane comprising a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises less than 50% of the total molecular weight of the polysiloxane.

66. A thermal insulation comprising the phenolic foam of claim 46.

67. A method of manufacturing a phenolic foam comprising: a. mixing a phenolic resin, a blowing agent, and a surfactant wherein the surfactant comprises i. an ethoxylated castor oil, and ii. a polysiloxane comprising a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises less than 50% of the total molecular weight of the polysiloxane, and b. adding an acid catalyst to catalyse a foaming reaction and produce a foam.

Description

BRIEF DESCRIPTION OF FIGURES

[0092] FIG. 1a and FIG. 1b show the cell structure of a foam formed from a composition in which the surfactant comprises only a polysiloxane surfactant, no ethoxylated castor oil is present in the composition (comparative example 1). The cell structure is shown at 200× magnification. The cell structure is poor. The cell structure has a wide distribution of cell sizes and shows the presence of coalescence where cells have merged together to form large cells.

[0093] FIG. 2a and FIG. 2b show the cell structure of a foam formed from a composition in which the surfactant comprises an ethoxylated castor oil component and a polysiloxane component comprising a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises 51% of the total molecular weight of the polysiloxane (comparative example 3). The cell structure is shown at 200× magnification. The cell structure is poor. The cell structure has a wide distribution of cell sizes and shows the presence of coalescence where cells have merged together to form large cells.

DETAILED DESCRIPTION OF THE INVENTION

[0094] The invention will be more clearly understood from the following description thereof given by way of example only.

[0095] The composition for forming a phenolic foam comprises a phenolic resin, a surfactant, an acid catalyst, and a blowing agent.

[0096] A preferred type of phenolic resin which may be employed in the composition is a resole resin. Such resole resin can be obtained from the chemical reaction of phenol or a phenol-based compound such as cresol, xylenol, para-alkylphenol, para-phenylphenol, resorcinol, and the like with an aldehyde such as formaldehyde, furfural, acetaldehyde and the like using a catalytic amount of alkali such as sodium hydroxide, potassium hydroxide, calcium hydroxide, or an aliphatic amine such as trimethylamine, or triethylamine. These types of chemical constituent are commonly used in standard resole resin production, but the invention is not limited to phenolic foams manufactured from phenol resins formed from only those chemicals listed here.

[0097] The molar ratio of phenol groups to aldehyde groups is desirably in the range from 1:1 to 1:3. As the molar ratio of phenol to aldehyde groups decreases foams may have increased residual formaldehyde and this is undesirable.

[0098] The water content of the phenolic resin may be from about 4 wt % to about 9 wt %, based on the total weight of the phenolic resin, and as determined by Karl Fisher analysis. The phenolic resin having a low water content from about 4 wt % to about 9 wt % reduces the amount of acid catalyst needed to cure the foam.

[0099] The phenolic resin may have a viscosity of from about 17,000 cPs to about 24,000 cPs or less at 25° C.

[0100] The phenolic resin may have a viscosity of from about 2,600 cPs to about 4,000 cPs or less at 40° C.

[0101] The phenolic resin preferably has a free formaldehyde content of below about 0.5 wt % based on the total weight of the phenolic resin, suitably below about 0.4 wt %, suitably below about 0.3 wt %, suitably below about 0.2 wt % based on the total weight of the phenolic resin when measured by titration following ISO 11402:2004.

[0102] The composition of the present invention comprises a surfactant. The surfactant comprises (i) an ethoxylated castor oil, and (ii) a polysiloxane comprising a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises less than 50% of the total molecular weight of the polysiloxane.

[0103] The surfactant of the present invention comprises a polysiloxane which may have the general chemical structure:

##STR00001## [0104] wherein [0105] w is from 1 to 100, [0106] x is from 1 to 50, [0107] y is from 1 to 100, [0108] z is from 1 to 50.
The number of repeat units is not particularly limited as long as the polysiloxane comprises a side chain comprising polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain comprises less than 50% of the total molecular weight of the polysiloxane.

[0109] Desirably the polysiloxane contains Si—C bonds which are not prone to hydrolysis during acid catalysis of the condensation polymerisation reaction that occurs in phenolic foam manufacture, for example the —Si—(CH2)3—O— functionality in the hydroxy-terminated polyoxyalkylene polymethyl siloxane may offer resistance to hydrolysis during acid catalysis of the condensation polymerisation reaction that occurs in phenolic foam manufacture.

[0110] The polysiloxane may have a HLB from about 7 to about 11.

[0111] The polysiloxane may have a molecular weight of from about 9,500 to about 25,000 g/mol.

[0112] The polysiloxane may comprise a polyoxyalkylene side chain which may be an ethylene oxide-propylene oxide copolymer side chain. The ethylene oxide-propylene oxide copolymer side chain may have 4 or more ethylene oxide units, for example 6 ethylene oxide units, for example 8 ethylene oxide units, for example 10 ethylene oxide units, for example 12 ethylene oxide units, for example 14 ethylene oxide units, for example 16 ethylene oxide units, for example 18 ethylene oxide units, for example 20 ethylene oxide units, for example more than 20 units of ethylene oxide. The ethylene oxide-propylene oxide copolymer side chain may have 4 or more propylene oxide units, for example 6 propylene oxide units, for example 8 propylene oxide units, for example 9 propylene oxide units, for example 10 propylene oxide units, for example 12 propylene oxide units, for example 14 propylene oxide units, for example 16 propylene oxide units, for example 18 propylene oxide units, for example 20 propylene oxide units, for example more than 20 units of propylene oxide. The polysiloxane may comprise a polysiloxyalkylene side chain wherein the ethylene oxide-propylene oxide copolymer side chain may comprise any combination of 4 or more ethylene oxide units and 4 or more propylene oxide units, for example 18 ethylene oxide units and 6 propylene oxide units, for example 6 ethylene oxide units and 18 propylene oxide units, for example 10 units of ethylene oxide units and 9 propylene oxide units, for example 20 ethylene oxide units and 20 propylene oxide units.

[0113] The surfactant which is used in the composition which forms the phenolic foam of the present invention comprises an ethoxylated castor oil. Castor oil is a non-drying oil derived from castor oil beans that contain relatively large amount of unsaturated acids such as ricinoleic acid, oleic acid, and linoleic acid and a small amount of saturated acids such as stearic acid and dioxystearic acid. The castor oil is ethoxylated. The castor oil may be polyethoxylated. The castor oil may have from about 10 to 50 ethylene oxide units, for examples 20 to 40 ethylene oxide units. The ethoxylated castor oil may have a HLB value of from about 12 to about 14.

[0114] In the present invention the polysiloxane component and the ethoxylated castor oil component are blended to form a surfactant which has a HLB value from about 9 to about 13.

[0115] The blowing agent may comprise any suitable blowing agent. In choosing the blowing agent, it must be remembered that the thermal conductivity of the phenolic foam is directly related to the thermal conductivity of the blowing agent entrapped in the foam i.e. the blowing agent trapped in the closed cells of the foam. Preferably, the blowing agent employed in the manufacture of the foam insulation cores of the present invention has low thermal conductivity and low environmental impact. Preferably, the blowing agents have low global warming potential and low ozone depletion potential. Preferably, the blowing agents have good fire retardancy properties. Suitably the blowing agent comprises a C.sub.1 to C.sub.7 hydrocarbon, a C.sub.2 to C.sub.5 halogenated hydrocarbon, a halogenated hydroolefin or combinations thereof.

[0116] Suitably the blowing agent comprises a C.sub.1 to C.sub.7 hydrocarbon which may be at least one of butane, pentane, hexane, heptane, or combinations thereof. Suitably the blowing agent comprises a C.sub.1 to C.sub.7 hydrocarbon which may be at least one of butane, pentane, hexane, heptane, or isomers thereof, or combinations thereof. Suitably the blowing agent comprises a C.sub.1 to C.sub.7 hydrocarbon which may be cyclopentane or isopentane, or combinations thereof.

[0117] Suitably, the C.sub.2 to C.sub.5 halogenated hydrocarbon is selected from 1,2-dichloroethene and isopropyl chloride, and combinations thereof.

[0118] Suitably the blowing agent comprises a halogenated hydroolefin, suitably selected from the group consisting of hydrofluoroolefins and hydrochloroolefins. suitably selected from the group consisting of 1-chloro-3,3,3-trifluoropropene, 1,3,3,3-tetrafluoro-1-propene, 2,3,3,3-tetrafluoro-1-propene, 1,1,1,4,4,4-hexofluoro-2-butene, and combinations thereof. The blowing agent may comprise 1-chloro-3,3,3-trifluoropropene, more suitably trans-1-chloro-3,3,3-trifluoropropene or cis-1-chloro-3,3,3-trifluoropropene or combinations thereof, preferably, trans-1-chloro-3,3,3-trifluoropropene.

[0119] The blowing agent of the composition of the invention may comprise C.sub.1 to C.sub.7 hydrocarbon from about 20 wt % to about 80 wt % of the total weight of blowing agent, suitably about 40 wt % to about 65 wt %, suitably about 45 wt % to about 60 wt % of the total weight of blowing agent.

[0120] The blowing agent of the composition of the invention may comprise C.sub.2 to C.sub.5 halogenated hydrocarbon from about 20 wt % to about 80 wt % of the total weight of blowing agent, suitably about 40 wt % to about 65 wt %, suitably about 45 wt % to about 60 wt % of the total weight of blowing agent.

[0121] The blowing agent of the composition of the invention may comprise a halogenated hydroolefin from about 20 wt % to about 80 wt % of the total weight of blowing agent, suitably about 35 wt % to about 60 wt %, suitably 40 wt % to 50 wt % of the total weight of blowing agent.

[0122] The acid catalyst may comprise an organic acid or an inorganic acid or a combination thereof. The acid catalyst may comprise sulfuric acid, or phosphoric acid, or benzene sulfonic acid, or xylene sulfonic acid, or paratoluene sulfonic acid, or naphthol sulfonic acid, or phenol sulfonic acid or a combination thereof. The composition may comprise the acid catalyst from about 1 to about 20 parts per 100 parts per weight of phenolic resin, suitably from about 5 to about 15 parts by weight.

[0123] The phenolic foam formed from the composition suitably has a pH of greater than 3 and less than 5 as measured by EN 13468:2001(e).

[0124] The phenolic foam formed from the composition suitably has a density below 100 kg/m.sup.3 as measured by ASTM D1622-14, suitably the phenolic foam has a density below 60 kg/m.sup.3, most suitably the phenolic foam has a density below about 35 kg/m.sup.3.

[0125] The phenolic foam formed from the composition suitably has a compressive strength from about 110 kPa to about 220 kPa as measured by BS EN 826:2013.

[0126] The phenolic foam formed from the composition suitably may have a friability from about 10% to about 50%, suitably from about 20% to about 40% as measured by ISO 6187.

[0127] The phenolic foam formed from the composition suitably has an aged thermal conductivity after ageing for 14 days at 110° C. of less than 0.022 W/m.Math.K, for example less than 0.021 W/m.Math.K, as measured by EN 13166:2012 (Method 2 Annex C).

[0128] The phenolic foam formed from the composition suitably has a closed cell content of greater than 90% when measured according to ASTM D2856, suitably a closed cell content of greater than 92%, suitably a closed cell content of greater than 95% when measured according to ASTM D2856.

EXAMPLES

[0129] The present invention will be explained in detail with reference to Examples hereinafter, while the present invention will not be limited by these examples.

[0130] Phenolic foam products obtained in the Examples and Comparative Examples were measured for physical properties according to the following methods.

[0131] Thermal conductivity was measured according to EN 13166:2012 (Method 2 Annex C).

[0132] Phenolic foam samples of the Examples and Comparative Examples were dried at 70° C. for four days and thermal conductivity was measured according to EN 13166:2012.

[0133] Phenolic foam samples of the Examples and Comparative Examples were thermally aged at 110° C. for 14 days and conditioned according to EN 13166:2012 (Method 2 Annex C). This may be referred to the aged thermal conductivity.

[0134] pH of the phenolic foam was measured according to EN 13468:2001(e).

[0135] Density of the phenolic foam was measured according to ASTM D1622-14.

[0136] Compressive strength of the phenolic foam was measured according to BS EN826:2013.

[0137] Friability of the phenolic foam may be measured according to ISO 6187.

[0138] Closed cell content of the phenolic foam was measured according to ASTM D2856.

[0139] Water content was determined by Karl Fischer analysis and was performed using a Metrohm 870 KF Titrino.

[0140] Viscosity was determined using a Brookfield viscometer DV II+Pro instrument with a water batch attachment to measure viscosities at 25° C. or 40° C. depending on how viscous the resin is. A spindle is selected, and spindle rotation speed (RPM) required to achieve a torque between 35-55% (typically 20RPM)

Resin “A” Preparation

[0141] The following resin was used in the foam examples below. Phenolic resole resin used is a liquid Phenol-Urea-Formaldehyde resin. Resin “A” has a Phenol:Urea:Formaldehyde molar ratio of 1:0.25:2.0. Resin “A” has a viscosity of 17000-24000 cPs at 25° C., weight average molecular weight 700 to 900, and pH 6 to 8.

[0142] Resin “A” resin contains from 4% to 6% free phenol, 0.1% to 0.5% free formaldehyde, and a water content of 4 to 9% (measured by Karl Fisher analysis).

[0143] The surfactants of the examples and comparative examples were mixed into resin “A” prior to the foam mixing procedure.

[0144] Foam Mixing Procedure

[0145] A phenolic foam product was prepared by foaming and curing a composition comprising: [0146] (a) 100 parts of resin “A” [0147] (b) a surfactant wherein the surfactant comprises 3.5 parts of an ethoxylated castor oil with from 10 to 50 ethylene oxide units and a surfactant of table 1, and [0148] (c) a blowing agent of table 2.

[0149] To 100 parts by weight of Resin “A” phenolic resin which comprises the surfactant at 25° C. is added and mixed powdered urea in the amounts shown in table 3. The resin is allowed to stand for between 12 and 24 hours. Next, the amount of blowing agent as shown in table 3 at 1° C. is mixed into the resin. Once a uniform emulsion has formed, the resin mixture is cooled to between 5° C. and 10° C. Next para-toluene sulfonic acid/xylene sulfonic acid blend (65/35 w/w) at 92% concentration in the amount shown in table 3 is quickly mixed in at 8° C. Foaming commences immediately. Mixing of the acid into resin takes less than 10 seconds and the resin mix is quickly poured into a 30×30×2.5 cm picture frame mould preheated to 70-75° C.

TABLE-US-00001 TABLE 1 Polysiloxane surfactants Polysiloxane Molecular weight of Wt % polyethylene surfactant Polysiloxane surfactant oxide (% EO) A 9457 37 B 15349 12 C 9671 32 D 14170 39 E 20479 30 F 14985 42 G 17281 51 H 16168 59 I 21950 51 J 26619 51

TABLE-US-00002 TABLE 2 Blowing agents Blowing Weight agent Blowing agent composition ratio A Cyclopentane isopentane blend 55.7:44.3 (85:15):HFO-1233zd(E) B Cyclopentane isopentane blend 50:50 (85:15):HFO-1336mmz(E) C Cyclopentane isopentane blend 52.4:47.6 (85:15):HFO-R1224zd(Z) D Cyclopentane isopentane blend 62.8:37.2 (85:15):t-DCE(E) E Cyclopentane isopentane blend 50:50 (85:15):HFO-1336mmz(Z)

TABLE-US-00003 TABLE 3 Foam compositions Parts by weight per 100 weight PF resin Blowing Polysiloxane PF Ethoxylated Polysiloxane Hydro Acid Examples Agent surfactant Resin Urea castor oil surfactant carbon HFO catalyst Comparative A C 100 4.00 0 4.53 6.31 5.02 11.22 Example 01 Comparative A — 100 4.00 4.5 0 6.31 5.02 11.23 Example 02 Comparative A G 100 4.04 3.5 1 6.43 5.11 11.02 Example 03 Comparative A I 100 4.00 3.5 1 6.49 5.16 11.11 Example 04 Comparative A J 100 4.05 3.5 1 6.45 5.13 11.07 Example 05 Comparative A H 100 4.02 4.2 1 6.80 5.41 10.99 Example 06 Example 01 A D 100 3.70 3.5 1.00 7.00 5.50 15.00 Example 02 A D 100 3.70 3.5 1.00 7.00 5.50 14.00 Example 03 A D 100 3.70 3.5 1.00 7.00 5.50 13.00 Example 04 A D 100 3.70 3.5 1.00 6.00 4.80 13.00 Example 05 A D 100 3.70 3.5 1.00 6.90 5.60 13.00 Example 06 A D 100 3.85 3.5 1 6.44 5.13 10.97 Example 07 A C 100 4.00 3.5 1.01 6.31 5.02 11.23 Example 08 A A 100 3.86 3.5 1 5.85 4.66 9.54 Example 09 A B 100 3.96 3.4 1 5.92 4.71 10.64 Example 10 A E 100 3.84 3.4 1 6.05 4.82 10.66 Example 11 A F 100 4.00 4 1.01 6.76 5.38 11.15 Example 12 B D 100 3.70 3.5 1 6.81 6.81 11.25 Example 13 C D 100 3.70 3.5 1 6.40 5.81 11.10 Example 14 D D 100 3.70 3.5 1 6.94 4.11 11.05 Example 15 D C 100 4.00 3.5 1.01 6.69 3.97 11.22 Example 16 E D 100 3.7 3.5 1 6.93 6.93 11.72

[0150] The phenolic foams of Examples 1 to 16 and comparative examples 1 to 6 were formed from the compositions as set forth in Table 3. After drying for 4 days @ 70° C., thermal conductivity, compressive strength and density was measured. Thermal conductivity was further measured after aging for 14 days @ 110° C. The results are shown in table 4.

TABLE-US-00004 TABLE 4 Foam characteristics 14 days @ 4 day @ 70° C. 110° C. Compressive Density Examples (mW/m .Math. K) (mW/m .Math. K) Strength (kPa) (kg/m.sup.3) Comparative 24.93 31.53  65.63 27.29 Example 01 Comparative 20.62 24.17 135.29 28.82 Example 02 Comparative 18.35 22.59 101.73 28.30 Example 03 Comparative 18.35 22.22  72.13 28.48 Example 04 Comparative 19.62 24.79 171.45 30.69 Example 05 Comparative 20.44 24.76 178.90 29.59 Example 06 Example 01 16.88 18.46 119.74 29.37 Example 02 16.86 18.47 120.51 29.27 Example 03 17.44 19.20 121.12 28.68 Example 04 16.56 17.63 135.10 30.14 Example 05 17.40 19.11 110.05 30.22 Example 06 17.96 19.73 N/A 28.74 Example 07 18.63 N/A 129.58 29.64 Example 08 21.43 N/A N/A 29.2 Example 09 17.71 20.53 N/A 27.75 Example 10 17.87 20.43 N/A 28.64 Example 11 18.98 N/A 157.98 29.53 Example 12 20.14 N/A 132.45 27.79 Example 13 19.12 21.00 141.15 30.28 Example 14 19.62 N/A 119.36 32.18 Example 15 18.63 N/A 129.58 29.64 Example 16 19.97 21.31 130.00 28.14

[0151] Comparative example 1 formed from a composition which did not contain ethoxylated castor oil exhibited poor thermal conductivity after drying for 4 days @ 70° C. and after aging for 14 days @ 110° C.

[0152] Comparative example 2 formed from a composition which did not contain a polysiloxane surfactant exhibited poor thermal conductivity after aging for 14 days @ 110° C.

[0153] The phenolic foams formed from a composition comprising a polysiloxane surfactant and an ethoxylated castor oil all exhibit acceptable thermal conductivity after drying for 4 days @ 70° C. but all exhibited poor thermal conductivity after aging for 14 days @ 110° C.

[0154] The surfactant has a significant effect on the structure of the cells of the foam. Comparative examples 1-6 produced foams in which the cell structure was irregular, there was a wide distribution of cell sizes, and some cells had coalesced to form large cells which all contributed to the foams exhibiting poor thermal conductivity after aging for 14 days @ 110° C.

[0155] Images of comparative example 1 (FIG. 1) and comparative example 3 (FIG. 2) were taken using a Keyance digital microscope system VH-Z100R with a real zoom lens set to ×200 magnification. Both comparative examples 1 and 3 clearly show a wide distribution of cell sizes and presence of coalescence where cells have merged together to form large cells. The wide distribution of cell sizes and coalescence of cells leads to poor aged thermal conductivities. The presence of coalescence where cells have merged together to form larger cells leads to porous cells and poor aged thermal conductivities. The poor aged thermal conductivity exhibited by the foams of the comparative examples are as expected considering the poor cell structure.

[0156] The phenolic foams formed from a composition comprising a polysiloxane surfactant wherein the polysiloxane comprises a side chain which comprises polyethylene oxide wherein the total molecular weight of the polyethylene oxide of the side chain is less than 50% of the total molecular weight of the polysiloxane of examples 1 to 16 produced foams which had excellent cell structure with a regular and uniform distribution of closed cells. Minimal imperfections on the cell walls were observed and coalescence of cells was not observed. The cell structure of examples 1 to 16 provides the foams with excellent thermal conductivity after aging for 14 days @ 110° C.

[0157] The phenolic foams formed from the composition of examples 1 to 6 and 9, 10, 11, and 16 show less lambda drift and have both low thermal conductivity after drying for 4 days @ 70° C. and after aging for 14 days @ 100° C. The low aged thermal conductivity of these examples is as expected considering their excellent cell structure. Example 7, 8, and 11-16 also have excellent cell structure.

[0158] The words “comprises/comprising” and the words “having/including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0159] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.